This type of chips easy to solder with soldering iron, not hot air --use good gel type flux --do not apply solder on the pad before placing chip! --you can use big paper clip to hold chip on pcb So, apply gel flux to pads, place chip and touch legs on the corner using slightly "wet" tip
Yeah, bigtime. Don't waste your time with solder paste. That stuff is best for pads that are flat to the board. These types of chips actually make a perfect angle to accept the soldering iron tip laying alongside the pad and the pin.
The “drag” soldering technique works well with this. Use a big flat tip (chisel, screwdriver, or hoof) on a good temperature controlled iron for best results.
Adrian I think it's great to show something you're _not_ good at. Many things take practice and effort to get good at. I think it's important for us all to remember that. Kudos for the great video!
This is so true. if you watch some videos, they make this type of work look easy. I accidentally destroyed a IIsi board when trying to fix a SMD IC similar to these, felt really stupid that I couldn't just fix it like everyone else seems to be able to. This is very precise work that requires precise tools. Thanks for sharing Adrian!
I came to post this exact comment. No one is perfect at everything all the time. I'm glad i watched this video and read the comments. I learned a lot. Thanks, Adrian!
"Practice makes perfect." It's an old adage, but a good one. You're gaining experience, learning what _not_ to do is as important as what you _can_ do. For example, you were trying to solder with the PCB loose on the table top, I was thinking you needed a small vise, then I see you switched to those "helping hands" clips. Another tip is the soldering; it can be hard to find the appropriate temperature for what you're working on, regardless of whether you're using an iron or the hot air. You want to get the part and traces hot enough to let the solder flow, yet still not too hot to damage them. And I totally agree on the 63/37 solder, I've used that alloy of Kester for over 45 years. Quality tools and materials make the job easier.
@@chriswilkinson1122 Maybe counter-intuitively, this is the sort of work that requires the biggest hammer you got :) I mean: a wide tip high power soldering iron and lots of flux, and you just drag the tinned iron along, touching the pins and the board. The smaller the iron and the finer the tip the more daunting it gets. These jobs simply cannot be done with tools that have high thermal resistance, and very fine tipped “SMT” soldering irons are notoriously unsuitable for this job. You’d think you need finesse: no, you need low thermal resistance and lots of heat quickly, and thus a wide-tip iron that resembles a flat blade screwdriver - tip 5-8mm wide, 1-2mm thick, and an iron 75W at minimum, with good temperature regulation. It turns this into a very simple job and takes a few seconds per side of the IC to get it soldered. I had a job where I had to solder a few hundred PLCC chips many years ago, and I did it in a couple of hours using a 100W iron, a jar of homemade flux made of bow rosin dissolved in alcohol, and a brush to apply said flux. I then washed the boards in alcohol.
Adrian - great job! Your attitude of open mistakes is really awesome. Reminds me of Richard Feynman's discussions on how in science there is a bad habit of publishing only the working solution and not sharing all the dead-end learning - which he found incredibly valuable.
For solder paste, you're supposed to use a PCB stencil, which has cutouts for each pad. You line it up and then just smear it across the board. EEVBlog made a great video on it, it's episode 415
Adrian: THANK YOU for sharing the disappointments/mistakes as well as the successes. I've got 40 years of software expertise, but only recently started getting serious about electronics work, and it makes it much less discouraging on my old eyes to see others going through the same difficulties and sharing what they've learned in the process. Congrats on the working modules!
Soldering paste is applied with a stencil in the desired thickness and a scraper, so you get the exact amount you need on each contact (only). That way you only apply soldering mask ones, then place everything, and run over it with the heat gun once. Just about every custom PCB supplier also offers to make stencils.
Its easy to get frustrated while learning, but remember, your attitude about it makes or breaks your confidence and patience. Give yourself some credit, and keep a positive attitude. Everyone had to start somewhere with something new
One of my favorite parts of your channel is that you don't edit out mistakes or the challenges you experience. I love that we get to experience that with you. I really enjoy watching you work through the problem and finding a solution. So many people could benefit from these skills!
I’m glad people are making kits like this. The Apples and PCs still can be useful. Just because they are old does not mean they should be put out to pasture.
Apply the solder paste using a stencil. MUCH easier, and the stencils cost almost nothing from JLCPCB and the other Chinese suppliers. And also - the solder paste contains all the flux you need.
You don't really need a stencil for a small bunch of tiny PCBs, just right size needle and not ruining it by submerging in liquid flux and all it takes is but a ten seconds
I totally agree with you. This channel is real because Adrian IS real. Thank you for showing real life and not edited reality Adrian. I think you did just fine, all things considered!
Nice that you found out this oldschool technique. In the late '90 I worked for a wholesale computer parts supplier and to make more profit and sell for lower prices than the competition we bought separate chips and empty ram boards from China and just make 30-pin simm memory modules ourself. We also had a dedicated simm memory tester for quality control.
Don't worry about refrigeration of the solder paste. It's fine because you hadn't opened it yet. Once you have, you only need to keep it cool for long term storage. I've also had bad luck trying to hot air solder SMT using solder paste applied with a squeeze tube. I've had somewhat better luck using a stencil to apply the paste, at least for .85 mm spaced parts, not so much with 0.5mm spaced ones. Setting the chip down correctly, and removing solder bridges has been the major problem. I've actually done better with a VERY fine tipped soldering iron and VERY thin flux cored solder wire. QFTP and SOIC chips are easier than QFN! I have a binocular microscope to inspect my work. I think it's a 20x power (eyepieces are marked 10x, objective is marked 2x). It was a lucky find in the dumpster where I worked. Just had to make a home brew stand for it.
"J" lead style SMT chips can be tough to solder as the pins go under the package. Strip-soldering them might work if the PCB is pre-tinned with solder then cleaned back off, to get minimal solder on the pads as a wick. Use lots of flux on the PCB and then tack 2 pins of the IC with the iron, then strip-solder the rest. The hope is that the small amount of solder left on the pad is enough to wick (pull more) new solder in and not having a lot on the pads should stop pad-to-pad shorting from solder "squishing out" from the J-lead & package being pressed to the PCB pads. For hot air, I think your only good choice would be to try and get a stencil for the (JEDEC I believe) J-lead package style. A toaster oven converted to a reflow oven would be the better way to solder in this way, but you could get away with the hand tool and a hot plate. Using a DIP style hot air head would help to get both sides heated up at the same time and prevent over heating the IC and PCB. I agree 63/37 solder is the best way to go. Using lead-free would be a nightmare. Looks like an interesting project :D Cheers,
I have recently been informed that there's now really good lead-free (and silver-free) solder available at reasonable prices because the patent finally expired. It's apparently very, very similar in properties to the 63/37 solder we've all liked for a long time. Given that lead mining is a relatively dangerous job as mining goes (it's hard to not get contaminated with a metal you're mining) I think reducing consumption where practicable is a good idea. (If only there was a really good UV stable yellow pigment that didn't cost a fortune and wasn't at least as toxic as lead chromate so we could stop painting it on our roads.)
I've had only a small amount of exposure to J Lead SMT chips, but my hot-air technique for re-work / prototyping using these packages is to heavily tin the pads (such that there's a little convex bump on each), add a thin coating of liquid flux (not Louis Rossmann's version of a "thin coating", but enough to cover the tinned pads without meeting in the center), then position the IC as accurately as you can, and lightly hold the IC down using some tweezers or or a screwdriver or basically anything heat resistant, not so much that you're pushing it into the PCB, but enough to resist the hot air's tendency to blow the IC off of the board. All things going well, the solder should re-flow nicely under the pads and you'll feel when the surface tension of the solder has pulled it nicely into alignment. I find it best to move the hot air gun around, to apply heat evenly to the pins of the component, remembering that the pins are what you want to heat up, not the IC itself. I'm sure these components aren't as sensitive as modern stuff, and unlikely to coexist with them on the same board but if you're working in the vicinity of other (more delicate) components, it's good practice to put some kapton tape over other components close by or try and shield them from heat as much as possible. After soldering using a lot of flux, it's always a good idea to give the board a cleaning, if you have an ultrasonic, that's great, if not some IPA (not the beer) should be fine. Then once it's all working, go have yourself a nice local IPA (the beer this time).
It's nice to see how much effort people put into keeping these old computers going (and I very much include you in that Adrian). I must admit I nearly skipped this video thinking from the first part of the intro this was going to be just a video of Adrian installing some RAM chips in Macs, which didn't sound very interesting. That will teach me because of course it was really about him making some SIMMs, which I did find really interesting (and glad to see they worked).
To help with the warping, you might spend a little time blowing hot air over the whole PCB to warm it through before going in hard to solder. Also, solder stencils all the way, will really help to ensure just the right amount of solder is applied. 🙂
Some tips for the road: - Use a thin film of solder paste next time, spread it with a silicone pick or an old credit card across the leg pads. It doesn't have to cover the entire strip of each pad, just be on it. The heat will help it flow into place. - You don't need a stencil, but it does help. In a pinch, you can use something like a Cricut to cut some card for a one-time-use stencil. - When using hot air, it's helpful to heat your boards from underneath. This prevents the bowing of the boards from thermal expansion. There are professional solutions for this, but you can also get away with hot plates set on their lowest setting to help lower the amount of time you have to focus on a chip. If you can reliably have your hot plate sit at around 400F/200C, it can flow the entire board for you. If your hot plate has hot/cold zones pretty bad, a thin layer of sand at the bottom will even that out to a gentle, consistent heat. - When going at a chip, try to use a more broad tip for your hot air gun. Paste works best when the entire footprint of the package flows at the same time. That way, it can destress and flow easier and build more consistent tensions around the legs. This is something I had to get wrong a few times before I got the hang of.
^ this. The reason it needs to be refrigerated is because the gel flux will dry into a powder. It's still usable in that form, but it'll take a lot more effort to get it out of the syringe tip.
I knew as soon as you said solder paste and months ago, I said right out loud, "Not refrigerated, this is not gonna work..." the super tiny soldering tip is a must! You should also purchase the needle VOM meter leads too... they are a must as well...
Awesome!! My very first computer, I wanted 8MB, so I ordered 2 4MB SIMMs. When I tried to boot, it didn't recognize them, so then I learned that my 386 required banks of 4 SIMMs... So bought 2 more rather expensive SIMMs... DOS had no use for 16MB, and I didn't yet have a hard drive, so I created a 12MB RAM disk which I unzipped a couple of floppies into on every boot. Fond memories indeed!!
Some tips from my own experience that I haven't seen mentioned: -If your solder paste is dried out (it does contain flux by the way, that's what the solder balls are suspended in to make the "paste"), simply squirt some of it into a small disposable container (like a plastic shot glass, bottle lid or similar small well) and then add in a bit of paste flux and stir. This will thin the paste back out and make it apply much more evenly. When doing small hand work like this without a stencil (using a stencil is much easier, so get one if you have the chance when ordering a design yourself) I will often use a small slotted jeweler's screwdriver to transfer my "renewed" paste to the pads. You don't need to be perfect, it's more important to just have the paste in the right ballpark and to not have too much on the board. As you found, the hot air will "magically" wick the solder where it needs to go if everything works right -You want to get away with the lowest hot air temperature that still melts the solder in a reasonable timeframe (5-30 seconds, not minutes). This will minimize the chance that you damage the chips or board with excessive heat, like the warping you got. What I find really helps is pre-heating the board part of the way so that the hot air doesn't need to be cranked up as much to get the solder to melt. There's proper heating plates for this, but you'll get a lot of benefit by using cheap alternatives you might already have. Some suggestions are a thrift store cooking skillet/hotplate turned as low as it will go (don't use it for food afterward!), a 3D printer heated bed (this is what I use), or one of those heated silicone mats off amazon for opening up phones/tablets. Basically, anything flat that can get the board to a controlled 100c-150c will make a big difference and won't harm the board or components, making the hot air step much quicker and less likely to cause damage -Solder paste comes in three typical "Types" usually labeled T3, T4 or T5. This refers to the size of the tiny solder balls in the paste, with the higher numbers using finer balls. Since the smaller balls have more surface area and flow better, they're just straight-up easier to work with for hobbyists and the price difference is negligible at this scale. The MG Chemicals stuff you have looks like T3 (the largest and hardest to work with), so if you do end up ordering another syringe of paste at some point, make sure to get the T5 stuff. Sometimes it's not a major difference depending on the kind of work, but I'll take every advantage I can get when doing this kind of tricky hand rework! Other than the above tips, it's mostly about practice and technique. The exact airflow, temperature, and hot air positioning and angle all influence how the paste and chips will behave, so experiment to find a method that works for you. In general notes, I usually do wide circles a few inches above the PCB/chips to get the board "close" to melting temperature, then bring the tip in really close to quickly melt the solder and ensure the chips and board stay in the "danger zone" temperatures for as little time as possible. Thanks for all the great content you make, and especially thanks for going deep into the details of your full process and troubleshooting, including the failures and challenges! It's very helpful to others, especially those starting out in electronics, to see that the path is often far more convoluted and challenging than some perfectly produced guides might indicate! Always keep pushing and learning new skills, it will always pay dividends down the road.
Great video again, every day is a learning day and hopefully your video will help others learn. Solder paste is best left for when you have a stencil to restrict the amount of paste on the pad. Too much paste will cause solder balls to skate around on the board causing bridges some visible on the legs but others not so much behind them underneath the chips. If you have a stencil and some good quality paste designed for the job at hand then it can out perform soldering chips by soldering iron. The other thing to consider is the thermal shock to the chips, some are super sensitive to the temperature changes and others wont last if kept at too high for too long. If I had to fit these chips and didn't have a screen printer, pick n place machine, & reflow oven, then I'd use a nice pointy iron tip with some thin diameter tin lead solder. As others have said, apply some flux to the leads and pads. Apply some solder to one pad in one corner. Solder the chip in place on the one pad and check for squareness and positioning. Once happy, do the other corner and double check positioning - because its easier to fix it now than later. If all looks good, solder up the other legs. I was always told I used too much flux but my joints were virtually the same as what came out the reflow oven. You can use the same method to solder other smd components - solder one pad, position the part on the pads and heat up that one pad. Check position and solder up the other end. Flux is important and cleaning that off when finished is more so. Hot Air Guns are really only used when removing parts from a board. Tip: clean off the board with some IPA, use a cotton bud to help move the fluid about and remove stubborn deposits. Check the ideal operating temperatures of the paste / solder wire (too hot and you'll burn off the additives too soon).
Adrian. The reason why the computer is running faster with more memory is because it has to do less paging. Paging (also known as virtual memory) is where the computer will temporality cache memory on the hard drive.
Dude, I'm glad you shared the mistakes because we ALL make them, but wow bless you for never having watched a video on how solder paste works! That being said your brutal technique worked okay to be honest! Probably not on anything with a finer pitch or smaller components though! You mostly made it hard by adding flux. That made the paste slide around and stopped your components from "sticking:"" Alternatively, since you have a hot hair station use a clip to hold the chip down, apply gel flux and hot air and touch your solder to each pin, or just use an iron if your hands are stable enough, these chips aren't that tiny. Solder paste only realy works when you have a stencil. You don't need flux - the solder is kinda sticky to keep your parts sliding off once they're stuck into it. It's supposed to be a bit like a glue in a way. You had a lot of trouble because the flux made everything slide around.
Best way is with a small amount of solder paste on the pads only and then gently put the SIMMs on a flat electric frypan / skillet. I've done a ton of SOJ+SIMMs this way!
hey ! i'm sure you're now ready to solder smd components with solder paste ! i'ts nice to see that some of us are working fine to keep going with older macs
Great way to get ram into the classics if you can't find any. For soldering the ic's, there is no sarcasm behind this, there are some really good videos, PACE is one of them and remember flux* is your friend (the no clean one). Great video.
Way back in the day a Friend of my Mother's worked for a PC Repair shop. The Repair shop's owner cleaned out the back room and since I worked on Computers the guy gave me 6 boxes loaded with old parts. In one of the boxes there was a odd looking RAM board. It had two 30pin edge connectors with short ribbon cables around 5 inches going to a bigger board that was populated with a 72pin simm socket. The board had a couple of jumpers and misc logic on it. I never got a chance to try it but it looked like it made a 30pin simm based system use 72pin and used two 30pin sim slots. I have no idea what company produced, looked kinda home made since I remember seeing a bunch of flux residue on it.
I do this kind of work professionally and there are two ways in soldering J-Style SMD-Chips to P.C.B. that I prefer. The first is to use a tiny amount of Epoxyglue to fix the Chips in position on the clean (No flux etc.) Board and solder them with special SMD-solderingwire (0,3 mm Diameter) using a microscope. The second way is to plot a solderingmask and use it to portion the solderingpaste on the pads. After removing the mask I fix the Parts with ceramicglue (extremly fast) and use hot Air with 320 Degree Celsius. What you do is great, cause I had to search a long time to get hand on such SIMs . Good work, and greetings from germany!
Oh my, one can sense the frustration! These chips are massive, they should be very easy to solder by hand. Just use thinner solder (0.5mm), tack solder one pin, then the opposite one, then put some flux and solder the rest. Great to see that the modules worked.
A dedicated toaster oven can be used for surface mount. Instead of having a temperature controlled PID, I use a simple trick: I place a small length of fine solder wire on one of the PCBs. When it melts you wait a few seconds and it's done.
yea, its so thick and not really wanting to flow because it was not refrigerated. we use this stuff at work on our stencil printer. solder paste absolutely positively without a doubt needs refrigerated or the flux gets dry and bad. then it all turns to crap from there. Everytime I order it, I have to do overnight shipping from Digikey or mouser with dry ice.
@@THEtechknight There is also the no fridge pastes. Like the chip quik TS391LT. I was happy to find this out after having it on the shelf for a year before using it :D
Very experienced soldering iron/hot air wielder here: If you don't have a stencil like in your case, tin the pins with your iron so they each have a tiny mound of solder on them. This is enough solder. Then just cover the IC legs in flux (your flux pen is fine) and add plenty of flux to the board and it'll work. You're 95% of the way there. More flux and pre-tin the pads and you'll get it next time you try! This saves you having to worry about having too much solder.
Nice work, it always amazes me how members of the retro community figure out how to get round shortages of items. I suspect at some time in the future someone will come up with a replacement for the classic mac screens using a TFT screen as a replacement so that we can get round the shortage and failing nature of old CRT tubes, also means we can get rid of the dangerous voltages as well.
When the paste doesn't want to flow, I blob it out onto a piece of paper, and use a toothpick to smear a little on the pads. I also use a toothpick to remove extra paste.
That was a truly use useful video. I actually have a ton of RAM myself, in fact I just got a tester which should arrive today, but you never can have too many 4mb 30 pin modules. Great tip!
Use a fine tip soldering iron, 1: place a blob of solder on one pin. 2: place component on pads and aline it with pads, 3: solder first pin, 4: solder a pin on the other side of component, 5: solder the rest one at a time, clean. Job done. Also get yourself an ESD mat and strap to give the chips a chance.
I've never tried soldering J-lead packages like these RAMs but I'd imagine it would be quite hard to reach under the bend and get the iron where it's needed.
Adrian I know why I like watching your videos, you’re just so normal like me trying to solder, not the best! You seem a like a great guy to know and keep up the great videos! I’m always learning something I either forgot or didn’t know. Also the Commodore book I did get on Kindle and it’s been fantastic. Boy the mistakes they made back in the day but a lot of fun to read how the Vic and 64 were developed was fun also the PetJet antics!
I learned SMD soldering via a similar method to yours! First try was a disaster, I discovered that with solder paste, a little goes a long way! I used a toothpick to smear a film of solder paste on to a flux treated PCB I used two techniques, for some things like ICs I would heat up the solder first until it was evenly distributed over the pads, then I used tweezers to place the IC onto the tinned pads and used a little more flux carefully heated the IC until, like you discovered, the chip dragged itself into place. Other times I would skip meting the solder paste and applied the component direct to the pasted pads fluxing before hand. Experimenting with the airflow can help, using a lower speed can help you get the nozzle a bit closer without knocking the component off line and prevents random pieces of solder getting splattered around the PCB. I think it's just a case of feeling out what works and from then on just refining your technique. Now I find SMD soldering so easy I wonder why I didn't learn sooner!
I usually use a toothpick to get just enough paste to cover the solder pads, then heat the board until the chips "snap" into place. My heat source is the good old Harbor Freight science hair dryer.
I soldered SMD with hot air only once in a small workshop. If I remember correctly you place a chip on the PCB then put some paste at the pads/pins (e.g. in a small line). If you heat this up the flux in the paste should pull the chip and the solder to the pads automatically. If it doesn't work add more flux and reheat. In hard cases you can also use a hot soldering iron and draw it along the pins.
I’m a total noob as well and had always been scared of smd. Finally got brave and bought a hot air station. Now I actually prefer smd instead of through hole. I’m 50, with bad eyes, and shaky hands, if I can do it, I know you can. I have never used a stencil, and it would probably make the job easier, but I am living proof you don’t need them. The trick is getting the right amount of paste. It’s ok to smear the paste on if you use a consistent amount across al the pads. Be a little conservative with the amount you use, and you don’t need to pre-flux, there is already flux in the paste. Get the chip close to aligned but it does not have to be perfect, surface tension of the solder will pull the chip into place. If you do get bridges, take your soldering iron with the tip cleaned of solder and just touch the pins, the excess solder should flow onto the tip. If you have a stubborn bridge, hit it with the solder wick. One last thing, be mindful of how much air you are using, the air can blow small parts out of place. Thanks for another great video Adrian.
You do have to say, it is very satisfying to use DIY RAM that you hand-soldered. I love your moments of humility, they are hilarious... but don't be too hard on yourself =)
If you want to see an expert at SMD soldering, I recommend tronix fix. That guy is amazing! He doesn't reball APUs, but other than that he fixes modern gaming consoles. Another good one is HDD Recovery Services. He recovers dead hard drives (which sometimes requires chip swaps) as well as USB drives, SD cards, etc... He uses thermal paste all the time. HDD services always pokes the chip to verify that it will slide back into place to know it's correct. Oh and paste is not required. I see them take a big solder blob and just drag it down the line to pre-tin the contacts. Once you put the component on you can drag the soldering iron across the pins. It doesn't take much solder. Oh and both channels use a microscope.
I was feeling your pain with that soldering. I've recently fixed a bad ram chip on my Amiga A600 which are very similar 40-pin J Lead packages. In the end my technique was, flux on the pads, put a little solder on a corner pad, tack the chip corner down with the iron, solder the opposite corner with the iron, then you get the iron to a couple of pins at a time with a little solder on the tip and let the flux do the rest of the work, the solder should flow onto the pad and leg if all goes well. Or if you have very fine solder wire, you can just solder each pin with that.
That brings back memories.... back in the times when you paid 100 bucks per megabyte I made PCBs and soldered ram chips into them to get 4 additional 1MB modules for my 386... and then I had to replace one ceramic cap with a SMD version on every board because it collided with the simm socket....
Now you have memories from 2020 :) Soldering tip: place the chip w/o soldered pins, then solder one pin by hand. It's fixed now and the remaining pins can be soldered smoothly.
You don't really need flux on the components at all! Solder paste *is* flux mixed with small solder balls. For small DIY job, I mix a small blob of solder paste with a little bit of liquid flux from that pen in a ceramic cup, and then use a plastic toothpick to "pick" a small blob and move it around on the pads. The added flux makes it a bit more liquid and easier to spread. The "normal" consistency paste is made for stencils and is definitely too thick to manipulate.
Adrian, everyone has to start somewhere with new techniques. You can make the paste more liquid by warning it. I would do the bypass caps first too. A vacuum pickup can also help. You can get a really cheap air bulb one for about $1-2 so worth trying. Practice with the bent one a few times or practice with an old PC board. Good luck. Personally, even though I have experience doing SMD rework I would probably have slip soldered the legs with a soldering iron as they are visible along each side. get a large rounded chisel tip with a dip in the flat face which holds a bubble of solder. Good luck, I really enjoy your channel.
Soldering like these always amaze me when the solder just jumps into position. I tried my hands in SMD soldering a couple of days ago, I bought little PCB christmas trees and I have to assemble them by hand, 3x4 SMD LEDs, 4 SMD resistors and a triode. These components are so tiny, I had a hard time with it and I tried regular soldering iron. The good part was that the pads were already tinned but I had hard luck assembling my first attempt (bought 6 of them). I should try the heat gun for my next attempt.
The way you got it at 12:42 (when you re-did the second chip on the first board) is how you want it to be before you put the chip in in the first place. As others have mentioned, using a stencil helps A LOT. If not using it, apply the paste, heat it with the gun so it forms on the pins, maybe touch up with the iron if needed, and then heat it with the gun and add the chip. If you do it correctly, you should be able to do it without too much heat (which will cause the board to warp)
When I first started with surface mount soldering, I used solder paste in similar applications to this. it helped me get a lot better at hand rework. Keep it up and you might be doing rework at a professional level in a short time. That said, I definitely agree with the other people saying to use an iron for this application. The solder wicks around the legs really easily using an iron and a bit of flux, and doesn't warp the small/thin PCB.
Adrian, as usual it was a nice video! Keep it going man! As for the soldering, you could try this technique: First, apply some solder paste. Not much, and use an old credit card to help spreading it evenly. Then, you use the heat air to make the solder stick to the pads (here you will see how nice it magically goes to the right place). And finally you place the chip as you did on the first ones, holding with the tweezers, but not pressing too much against the chip. Hope that it works better for you! Much love from Brazil!
Great video, I never even thought of searching for a project like this. So my 386 and 486's will be very happy in a few weeks. I can't wait to see if my 386DX-40 can do 8x 4MB modules
@13:46 Just a tip, when soldering smd parts, pre tin only one side and only one pad. Put the part on it, easiest when only a two legged thingy, heat up the pad with a solder needle, whatch the part sink in and sit flush. Then do the other leg / pad with standard methode, heat pad then come in with your solder containing flux. With multi legged parts it is a little bit more challenging and requires some training, but advantage of only pre tinning and soldering one leg is, if the part is slightly turned or a little off center, you can still easily correct that. If position is good, start soldering a leg / pad at the adjacent side via common methode. Rinse and repeat, takes some time but the result is showable.
Very cool! When I first started doing smt work I actually made full stencils for the pcb’s I was using from overhead projector acetate and a cnc hobby cutting machine to make the holes and then applying the thin layer of paste using a plastic card to spread it over the stencil. It works pretty well, but I found you need pretty good accuracy and steady hands to place the chips. I don’t have steady hands. 😆 With all smt work these days, as it’s just prototype stuff, I always go the ‘lots of tacky flux and flood solder’ route. I’ve not tried j-lead or qfn, but you should be able to do it ok with flooding I think, but probably more awkward than soic or qfp. I usually put some tacky flux down on the pads, place the chip, then just flood with solder and tidy up with wick where needed. So much is just practice, and learning to keep your cool. 😆 Even under good conditions it’s a frustrating thing to do, but compound it with essential tremor and the patience of a saint can be required at times. I mostly use hot air just for removal these days, but everyone has their preferences and abilities. Great videos, keep on doing what you do. 😄
That is a nice upgrade for the Classic II! And I truly feel your pain with SMT. I have a half-finished EasyFlash 3 cartridge downstairs waiting for the inspiration to continue soldering the SMT resistors and caps that I can barely see.
If you pre-tin solder pads like that, it leaves a rounded surface, which in turn makes it very hard to keep the legs of the device you're mounting positioned correctly. Next time, clamp the device in position (use like a large paper binder type clip). Don't pre-tin the pads. After the device is correctly positioned, with its legs on the correct pads, apply flux, then solder the joint. If the device has a lot of legs, you can "strip solder" them in one continuous go by laying a length of solder wire (of the correct size) across the tops of the legs. You then apply the soldering iron tip to the junction of where the leg makes contact with the solder pad. The soldering iron tip should contact *both* the leg of the device and the pad. The solder wire will melt, and thanks to the flux, wick itself into the correct position. You can also use soldering paste (as long as it has been correctly stored ;) ) for this. My personal preference is paste. Make sure you use solder of the correct thickness! If you use a solder that is too fat, you'll end up having bridging problems. If you look at the solder you are about to use and think "well, that's going to be too thin" it's probably perfect; it doesn't take much solder to form a solid joint. I would also recommend that you don't use hot air for this type of work. Not only is it more difficult, but it is also a lot easier to end up with a dry joint, as the solder and legs typically get a lot hotter than the pad itself does. Just use a soldering iron tip of the appropriate size and type and make sure you touch both the pad and the leg. As others have pointed out, the carrying agent in solder paste is flux.
With solder paste it needs two stages of heat. one is just below the melting point to get the flux flowing and then increase to reflow the solder. Solder paste will have a reflow pattern data sheet to show the temps and time needed. When I do this with hot air I have a nice thick stone tile with a polished top so I don't damage my desk or silicone matt. I also never liked the paste from a syringe and had the same issues you did and would use something else to apply the paste. A stencil is so much quicker and saves a lot of mess, but for the number you have it's expensive. Soldering with the iron and plenty of good amtec bga flux is a lot easier for a small number of chips like this.
Hi Adrian. I think you did a good job considering the lack of tack flux. When you have trouble with solder between the pins, the first thing to try is a dab of flux, then drag the iron out from the pins.. tacky flux (designed for smd rework). If that doesn't work, touch the pins with a tiny (1-2mm wide) solder braid + extra flux. Doesn't matter if the solder bridge is behind the pins. It will just wick up on the braid. Personally I prefer flux and dragsolder, and solder paste only with stencil.
I wonder if the chips pin surfaces aren't doing you a favour. Maybe they are heavily oxidized and need some mechanical action to get clean. Not sure. I presume the chips are old stock.
And before I knew just what the video was going to be about, when you were talking about the rare high-capacity 30-pin memory, my immediate thought was "gee, sounds like some project some hobbyist group could come up with; some way of making substitute memory". And so what was the video about? Exactly that. But as you were soldering, I could just hear a Louis Rossmann commentary about how to solder going on in the back of my mind.
Nice interesting video. I like it that you don't stop the camera on the learning curve with smd. I only use dip components because i'm also afraid to mess up starting up smd soldering. After seeing this maybe i'll start with it
I recently bought a hot-air station. Like you said, it takes time and practice to get good at surface-mount soldering. To get some practice, I decided to remove and re-attach every component on a cheap DDR2 memory stick that I don't really need :) Also bent boards can be straightened if they are bent to their original state, fixed somehow in this state and heated up to less-then-solder-melting temperature for some time. Some folks even do this to fix bent PC motherboards.
One thing I was suprised to find out is that early Amiga computers were wuite memory starved even though pretty much everyone who had one upgraded even the A500 to 1mb. It seems to make a real difference uprading them over 8mb. Since they share the same MC680x0 CPU series as the Mac Classic II it makes sense that this would carry over.
The amiga uses 2 types of memory in most cases. We have Graphics mem, that memory is shared between the CPU and the chipset and we have fast mem that only the CPU can access giving the amiga a speedboost.
Adrian, I would suggest watching some of Louis Rossmann's MacBook repair videos for tips on SMT soldering with hot air - it's amazing to see how 'sloppy' you can be when applying the solder and how well it comes out. You will notice he uses a lot of flux (available from his store) to heat up the whole component, not just one side. I think you will learn a lot from his videos - I know I did, even after 40 years as an EE.
In your defence, the J-leg chips are a bit of a pain to solder. lol The last time I manually soldered some, it was for swapping the DRAMs on an Atari Jaguar that I was repairing for somebody. I thought it would be a quick job, but it had been many years since I soldered SOJ chips (even though I've been soldering TQFPs, QFNs, and all sorts since). I normally use a small 2mm chisel tip on a Metcal iron, tack down the corner pins, then manually solder the rest after adding a dab of liquid flux. But I had real trouble getting enough solder to wick between the pins and pads without bridging stuff. It took me about an hour to swap four DRAM chips. lol It looked fine in the end, but the fault turned out to be a tiny spot of corrosion on the Interrupt trace to the 68000. To second what others have said here, using solder paste directly with these chips is generally not the best idea for your sanity. :p It can be used on certain components if exactly the right amount is put across the pads. But really you needed a stencil, and you'd be amazed how quick and easy it is. This was genuinely my first ever attempt at using a solder stencil at home (about a year ago)... i.imgur.com/KBdaMXw.jpg i.imgur.com/Xnza7T9.jpg I did the solder paste in one *single* pass, by adding quite a thick line of paste at the top of the stencil, about an inch above the SMD holes. I then used a plastic business card as a squeegee, holding it at a 45-degree angle to the board, so the solder paste bunched up in a line as it rolled over all of the stencil holes. (using a fair amount of pressure to keep the squeegee edge flat to the stencil, and the PCB taped down very firmly. Taping down some junk PCBs around the main one is also important, so it keeps the correct height, and doesn't move at all.) I then just carefully plonked the components on, and reflowed the whole board in a modified toaster oven using a "Tiny Reflow V2" and fairly cheap leaded solder paste. For smaller stuff like the DRAMs, you can get away with just using a hot air station. I would recommend NOT dabbing the solder into the stencil like a lot of people seem to do on their first attempts. It's best to just do a single pass if possible, otherwise dabbing the paste tends to lift the stencil a tiny bit, and smears the paste underneath (shorting between pads etc.). As you said, soldering the SMD stuff definitely gets easier with practice and finding the right technique. But I wouldn't personally use solder paste for the SOJ chips, just manual soldering with a small chisel tip and plenty of flux.
The memory chips are quite accessible for hobbyists, and can be easily soldered with an iron and solder wire. I would guess that the pitch is 1.27mm. Unfortunately, they are no longer manufactured. The solder paste is dry, and that is why you need to keep it in the refrigerator. The flux simply evaporates if the solder paste is not kept in proper conditions, especially after being opened for the first time. You are better off using solder wire and some flux, and a temperature regulated iron (or a 25W iron cooled periodically) with a suitable tip. Hoof tips are great. Your hot air is probably too hot. You should use a bigger nozzle, reduce the heat a lot, reduce the air flow a bit as well (to keep the components from flying). Mind that you have to regulate the heat accordingly in relation to your air flow. Also, keep the distance from the board and try to pre-heat the board evenly, by wiggling the nozzle at a distance (about two or three inches away). When soldering, keep the nozzle at a distance of one inch. Take your time until the solder paste melts and flows. Your iron temp might be too hot as well, since you mentioned some lifted pads and traces. You should reduce the temps to below 300º, and be quick about it. Flux more than helps when cleaning solder bridges between pads. You just need to do one in and out movement, and that takes one or two seconds at most. Don't dwell too much and be quick! To clean the boards, doing ultra-sonic cleaning is ok, even recommended. Don't use soap and water. Use distilled water if the flux is water soluble, or use isopropyl alcohol if not. As for the silicone mat, I have the same you have. It is heat resistant, alright. But it is pretty much conductive and tends to warp due to thermal expansion. I would recommend an extra layer of two silicone translucent white ones on top of that. You can find them on eBay. In hindsight, I hope you view my advice as constructive. I was far from perfect when I first soldered, and I still have that PCB to remember my mistakes (namely, too much solder). It worked, but there is always room for improvement. In every case, practice makes perfect. So, practice a lot and drop the solder paste. You can find tutorials where SO-8/14/16 chips are soldered. The pitch is identical, despite the differences in the format of the leads. The technique is pretty much similar.
I seem to remember that Macs had virtual memory, which was system software that used the hard drive to supplement the machine’s physical ram. But virtual memory slowed things down. However, having a lot of physical memory for the system and programs allowed faster operation.
I must say well done Adrian!!!! I too do not go near SMD soldering for the same reason as you. It requires a certain skill to pull it off. Well done, great job!!!
Yeah I'm a bit apprehensive about SMD too for the same reason, although i must admit that the videos I've watched make it look relatively uncomplicated.
@@BertGrink it is much more difficult than it looks trust me. I lack the tools also so I dont bother. Through hole soldering is best. But would be worth attempting SMD work I suppose.
I do the odd bit of SMT soldering, most of the time its mounting though hole parts where SMT is supose to go. It is a little tricky & fiddely, but you do get the hang of it.
A smaller needle on your syringe makes things a lot easier. Also, if you pre-warm the pads the solder will flow and stick onto the pads a lot easier. I have spent some time hand soldering 0608 (and smaller) smd and it can be a pain as a beginner as you certainly discovered!
Per Wikipedia, for the IIci, it was popular to install faster memory in the first bank of SIMM slots, as this is the bank used by the video subsystem. Otherwise, a video card could be used to free-up system memory that otherwise would have been used for the video subsystem. As for the Classic II, the only issue with speed might be if on-board RAM were slower than SIMM ram (which is the case in the Mac IIsi). The Mac IIsi could get a video speedup by increasing disk cache which would take up space in the on-board slow RAM, which would relocate video ram from the slow RAM onto the faster SIMMs.
I think the technique you used was out of order. You should have 1) Apply flux to the pad 2) Place the Chip 3) use a small bead of Solder paste on the outside between the legs of the chip and the PCB 4) apply hot air then use a solder wick with flux to remove any soldering bridges. It would have been easier for you if you has a stencil as mentioned before in the comments.
great vid adrian. i was nervous when i first started smd soldering. but over the last year i can handle 144 pin fpga’s easily now. i dread any through hole soldering now.
really loving this video! its exactly the motivation and knowledge i need to try a heat station and smd myself; I think you could do a perfect job with the paste; trying to remove them without a ton of flux will let it get overheated more often
I always appreciate these videos. You are always so positive and it's a welcome break from doomscrolling. You're doing great! Surface mount is a very different kind of skill. Once the pandemic is over I can highly recommend Jessa at iPad Rehab for microsoldering training. They have a one-week course that was incredibly instructive for me. It's centered around phone repair but if you can do microsoldering on phones the type of work you're doing here will be child's play.
Hello Adrian's thanks for the great video and your soldering skills look like they are improving I have been working with electronics for 45 years . this ram will come in handy when finishing restoring my Mac Se/30 .
![Repairing an Apple Disk ][ drive with multiple faults](http://i.ytimg.com/vi/e1_aI88Xr98/mqdefault.jpg)
![Apple ][ plus: VIDEX 80 column card, CPM on the Apple II and servicing the disk drives](/img/n.gif)
This type of chips easy to solder with soldering iron, not hot air
--use good gel type flux
--do not apply solder on the pad before placing chip!
--you can use big paper clip to hold chip on pcb
So, apply gel flux to pads, place chip and touch legs on the corner using slightly "wet" tip
Yeah, bigtime. Don't waste your time with solder paste. That stuff is best for pads that are flat to the board. These types of chips actually make a perfect angle to accept the soldering iron tip laying alongside the pad and the pin.
The “drag” soldering technique works well with this. Use a big flat tip (chisel, screwdriver, or hoof) on a good temperature controlled iron for best results.
Why no pre-tinning the pads though? Hard to position the chip on the domed solder blobs?
@@benbaselet2026 Yes, exactly! Also all factory board include jlcpcb and over are already pre-tinned (HASL process)
Hmm, if you hit the applied paste with hot air before putting on the chip, wouldn't it tin the pads making for easier reflow when mounting the chips?
Adrian I think it's great to show something you're _not_ good at. Many things take practice and effort to get good at. I think it's important for us all to remember that. Kudos for the great video!
This is so true. if you watch some videos, they make this type of work look easy. I accidentally destroyed a IIsi board when trying to fix a SMD IC similar to these, felt really stupid that I couldn't just fix it like everyone else seems to be able to. This is very precise work that requires precise tools. Thanks for sharing Adrian!
I came to post this exact comment. No one is perfect at everything all the time. I'm glad i watched this video and read the comments. I learned a lot. Thanks, Adrian!
"Practice makes perfect." It's an old adage, but a good one. You're gaining experience, learning what _not_ to do is as important as what you _can_ do. For example, you were trying to solder with the PCB loose on the table top, I was thinking you needed a small vise, then I see you switched to those "helping hands" clips. Another tip is the soldering; it can be hard to find the appropriate temperature for what you're working on, regardless of whether you're using an iron or the hot air. You want to get the part and traces hot enough to let the solder flow, yet still not too hot to damage them. And I totally agree on the 63/37 solder, I've used that alloy of Kester for over 45 years. Quality tools and materials make the job easier.
@@chriswilkinson1122 Maybe counter-intuitively, this is the sort of work that requires the biggest hammer you got :) I mean: a wide tip high power soldering iron and lots of flux, and you just drag the tinned iron along, touching the pins and the board. The smaller the iron and the finer the tip the more daunting it gets. These jobs simply cannot be done with tools that have high thermal resistance, and very fine tipped “SMT” soldering irons are notoriously unsuitable for this job. You’d think you need finesse: no, you need low thermal resistance and lots of heat quickly, and thus a wide-tip iron that resembles a flat blade screwdriver - tip 5-8mm wide, 1-2mm thick, and an iron 75W at minimum, with good temperature regulation. It turns this into a very simple job and takes a few seconds per side of the IC to get it soldered. I had a job where I had to solder a few hundred PLCC chips many years ago, and I did it in a couple of hours using a 100W iron, a jar of homemade flux made of bow rosin dissolved in alcohol, and a brush to apply said flux. I then washed the boards in alcohol.
Adrian - great job! Your attitude of open mistakes is really awesome.
Reminds me of Richard Feynman's discussions on how in science there is a bad habit of publishing only the working solution and not sharing all the dead-end learning - which he found incredibly valuable.
I like that you always show your learning process and mistakes - it's all too rare in the world of UA-cam. Great to see that it worked out in the end!
Being humble is something we as a society have lost. Everyone wants to be "NUMBER 1!!" but accomplishing anything is an accomplishment in it self.
Homemade memory, that's pretty cool.
It’s incredible!
he will defiantly remember this project lol
For solder paste, you're supposed to use a PCB stencil, which has cutouts for each pad. You line it up and then just smear it across the board. EEVBlog made a great video on it, it's episode 415
Adrian: THANK YOU for sharing the disappointments/mistakes as well as the successes. I've got 40 years of software expertise, but only recently started getting serious about electronics work, and it makes it much less discouraging on my old eyes to see others going through the same difficulties and sharing what they've learned in the process. Congrats on the working modules!
Soldering paste is applied with a stencil in the desired thickness and a scraper, so you get the exact amount you need on each contact (only). That way you only apply soldering mask ones, then place everything, and run over it with the heat gun once. Just about every custom PCB supplier also offers to make stencils.
Its easy to get frustrated while learning, but remember, your attitude about it makes or breaks your confidence and patience. Give yourself some credit, and keep a positive attitude. Everyone had to start somewhere with something new
One of my favorite parts of your channel is that you don't edit out mistakes or the challenges you experience. I love that we get to experience that with you. I really enjoy watching you work through the problem and finding a solution. So many people could benefit from these skills!
I’m glad people are making kits like this. The Apples and PCs still can be useful. Just because they are old does not mean they should be put out to pasture.
Apply the solder paste using a stencil. MUCH easier, and the stencils cost almost nothing from JLCPCB and the other Chinese suppliers. And also - the solder paste contains all the flux you need.
Stencil, solder paste and frying pan! Easy peasy
@@cmorda11 Never tried the frying pan method. I have an old oven in my workshop ;)
+6million Stencils and then this just is pure magic sauce..
You don't really need a stencil for a small bunch of tiny PCBs, just right size needle and not ruining it by submerging in liquid flux and all it takes is but a ten seconds
No such thing as enough flux
I'm pretty competent at through-hole, but surface mount soldering is pretty new to me too. You're in good company.
Dont beat yourself up. Mistakes are great learning experiences. I love your channel and all the work you do. Keep it up! Thank you good sir!
I totally agree with you. This channel is real because Adrian IS real. Thank you for showing real life and not edited reality Adrian. I think you did just fine, all things considered!
0:15: "Ways ago, back in july." Haha, July? That's not that long a... wait!!! 😳
In 2020 time, July was tweventeen months ago.
@Llama Craft No idea what that means?
@@andrewgwilliam4831 it means what in japanese
@@Blaze-zm7zt How odd!
This is literally amazing. I've always wondered about homemade modules.
Nice that you found out this oldschool technique. In the late '90 I worked for a wholesale computer parts supplier and to make more profit and sell for lower prices than the competition we bought separate chips and empty ram boards from China and just make 30-pin simm memory modules ourself. We also had a dedicated simm memory tester for quality control.
Don't worry about refrigeration of the solder paste. It's fine because you hadn't opened it yet. Once you have, you only need to keep it cool for long term storage.
I've also had bad luck trying to hot air solder SMT using solder paste applied with a squeeze tube. I've had somewhat better luck using a stencil to apply the paste, at least for .85 mm spaced parts, not so much with 0.5mm spaced ones. Setting the chip down correctly, and removing solder bridges has been the major problem. I've actually done better with a VERY fine tipped soldering iron and VERY thin flux cored solder wire. QFTP and SOIC chips are easier than QFN!
I have a binocular microscope to inspect my work. I think it's a 20x power (eyepieces are marked 10x, objective is marked 2x). It was a lucky find in the dumpster where I worked. Just had to make a home brew stand for it.
"J" lead style SMT chips can be tough to solder as the pins go under the package.
Strip-soldering them might work if the PCB is pre-tinned with solder then cleaned back off, to get minimal solder on the pads as a wick.
Use lots of flux on the PCB and then tack 2 pins of the IC with the iron, then strip-solder the rest.
The hope is that the small amount of solder left on the pad is enough to wick (pull more) new solder in and not having a lot on the pads should stop pad-to-pad shorting from solder "squishing out" from the J-lead & package being pressed to the PCB pads.
For hot air, I think your only good choice would be to try and get a stencil for the (JEDEC I believe) J-lead package style. A toaster oven converted to a reflow oven would be the better way to solder in this way, but you could get away with the hand tool and a hot plate. Using a DIP style hot air head would help to get both sides heated up at the same time and prevent over heating the IC and PCB.
I agree 63/37 solder is the best way to go. Using lead-free would be a nightmare.
Looks like an interesting project :D
Cheers,
I have recently been informed that there's now really good lead-free (and silver-free) solder available at reasonable prices because the patent finally expired. It's apparently very, very similar in properties to the 63/37 solder we've all liked for a long time. Given that lead mining is a relatively dangerous job as mining goes (it's hard to not get contaminated with a metal you're mining) I think reducing consumption where practicable is a good idea. (If only there was a really good UV stable yellow pigment that didn't cost a fortune and wasn't at least as toxic as lead chromate so we could stop painting it on our roads.)
After soldering with an iron just add flux and reflow with the iron, Ive been doing this for years, solder paste goes bad fast once opened.
I've had only a small amount of exposure to J Lead SMT chips, but my hot-air technique for re-work / prototyping using these packages is to heavily tin the pads (such that there's a little convex bump on each), add a thin coating of liquid flux (not Louis Rossmann's version of a "thin coating", but enough to cover the tinned pads without meeting in the center), then position the IC as accurately as you can, and lightly hold the IC down using some tweezers or or a screwdriver or basically anything heat resistant, not so much that you're pushing it into the PCB, but enough to resist the hot air's tendency to blow the IC off of the board. All things going well, the solder should re-flow nicely under the pads and you'll feel when the surface tension of the solder has pulled it nicely into alignment. I find it best to move the hot air gun around, to apply heat evenly to the pins of the component, remembering that the pins are what you want to heat up, not the IC itself.
I'm sure these components aren't as sensitive as modern stuff, and unlikely to coexist with them on the same board but if you're working in the vicinity of other (more delicate) components, it's good practice to put some kapton tape over other components close by or try and shield them from heat as much as possible.
After soldering using a lot of flux, it's always a good idea to give the board a cleaning, if you have an ultrasonic, that's great, if not some IPA (not the beer) should be fine.
Then once it's all working, go have yourself a nice local IPA (the beer this time).
It's nice to see how much effort people put into keeping these old computers going (and I very much include you in that Adrian). I must admit I nearly skipped this video thinking from the first part of the intro this was going to be just a video of Adrian installing some RAM chips in Macs, which didn't sound very interesting. That will teach me because of course it was really about him making some SIMMs, which I did find really interesting (and glad to see they worked).
To help with the warping, you might spend a little time blowing hot air over the whole PCB to warm it through before going in hard to solder.
Also, solder stencils all the way, will really help to ensure just the right amount of solder is applied. 🙂
Thanks Adrian, with all the hours seen Rossman soldering videos and now yours i´m much confident to try surface soldering. Greatings from Argentina!
Some tips for the road:
- Use a thin film of solder paste next time, spread it with a silicone pick or an old credit card across the leg pads. It doesn't have to cover the entire strip of each pad, just be on it. The heat will help it flow into place.
- You don't need a stencil, but it does help. In a pinch, you can use something like a Cricut to cut some card for a one-time-use stencil.
- When using hot air, it's helpful to heat your boards from underneath. This prevents the bowing of the boards from thermal expansion. There are professional solutions for this, but you can also get away with hot plates set on their lowest setting to help lower the amount of time you have to focus on a chip. If you can reliably have your hot plate sit at around 400F/200C, it can flow the entire board for you. If your hot plate has hot/cold zones pretty bad, a thin layer of sand at the bottom will even that out to a gentle, consistent heat.
- When going at a chip, try to use a more broad tip for your hot air gun. Paste works best when the entire footprint of the package flows at the same time. That way, it can destress and flow easier and build more consistent tensions around the legs. This is something I had to get wrong a few times before I got the hang of.
Soldering is an art. Takes practice, knowledge and control.
When something like that says to keep refrigerated, that usually means after opening and breaking the seal.
^ this. The reason it needs to be refrigerated is because the gel flux will dry into a powder. It's still usable in that form, but it'll take a lot more effort to get it out of the syringe tip.
I knew as soon as you said solder paste and months ago, I said right out loud, "Not refrigerated, this is not gonna work..."
the super tiny soldering tip is a must! You should also purchase the needle VOM meter leads too... they are a must as well...
Awesome!! My very first computer, I wanted 8MB, so I ordered 2 4MB SIMMs. When I tried to boot, it didn't recognize them, so then I learned that my 386 required banks of 4 SIMMs... So bought 2 more rather expensive SIMMs... DOS had no use for 16MB, and I didn't yet have a hard drive, so I created a 12MB RAM disk which I unzipped a couple of floppies into on every boot.
Fond memories indeed!!
Some tips from my own experience that I haven't seen mentioned:
-If your solder paste is dried out (it does contain flux by the way, that's what the solder balls are suspended in to make the "paste"), simply squirt some of it into a small disposable container (like a plastic shot glass, bottle lid or similar small well) and then add in a bit of paste flux and stir. This will thin the paste back out and make it apply much more evenly. When doing small hand work like this without a stencil (using a stencil is much easier, so get one if you have the chance when ordering a design yourself) I will often use a small slotted jeweler's screwdriver to transfer my "renewed" paste to the pads. You don't need to be perfect, it's more important to just have the paste in the right ballpark and to not have too much on the board. As you found, the hot air will "magically" wick the solder where it needs to go if everything works right
-You want to get away with the lowest hot air temperature that still melts the solder in a reasonable timeframe (5-30 seconds, not minutes). This will minimize the chance that you damage the chips or board with excessive heat, like the warping you got. What I find really helps is pre-heating the board part of the way so that the hot air doesn't need to be cranked up as much to get the solder to melt. There's proper heating plates for this, but you'll get a lot of benefit by using cheap alternatives you might already have. Some suggestions are a thrift store cooking skillet/hotplate turned as low as it will go (don't use it for food afterward!), a 3D printer heated bed (this is what I use), or one of those heated silicone mats off amazon for opening up phones/tablets. Basically, anything flat that can get the board to a controlled 100c-150c will make a big difference and won't harm the board or components, making the hot air step much quicker and less likely to cause damage
-Solder paste comes in three typical "Types" usually labeled T3, T4 or T5. This refers to the size of the tiny solder balls in the paste, with the higher numbers using finer balls. Since the smaller balls have more surface area and flow better, they're just straight-up easier to work with for hobbyists and the price difference is negligible at this scale. The MG Chemicals stuff you have looks like T3 (the largest and hardest to work with), so if you do end up ordering another syringe of paste at some point, make sure to get the T5 stuff. Sometimes it's not a major difference depending on the kind of work, but I'll take every advantage I can get when doing this kind of tricky hand rework!
Other than the above tips, it's mostly about practice and technique. The exact airflow, temperature, and hot air positioning and angle all influence how the paste and chips will behave, so experiment to find a method that works for you. In general notes, I usually do wide circles a few inches above the PCB/chips to get the board "close" to melting temperature, then bring the tip in really close to quickly melt the solder and ensure the chips and board stay in the "danger zone" temperatures for as little time as possible.
Thanks for all the great content you make, and especially thanks for going deep into the details of your full process and troubleshooting, including the failures and challenges! It's very helpful to others, especially those starting out in electronics, to see that the path is often far more convoluted and challenging than some perfectly produced guides might indicate! Always keep pushing and learning new skills, it will always pay dividends down the road.
Great video , I'm glad you showed the learning process even though it was frustrating. It was interesting to watch.
Great video again, every day is a learning day and hopefully your video will help others learn.
Solder paste is best left for when you have a stencil to restrict the amount of paste on the pad. Too much paste will cause solder balls to skate around on the board causing bridges some visible on the legs but others not so much behind them underneath the chips. If you have a stencil and some good quality paste designed for the job at hand then it can out perform soldering chips by soldering iron. The other thing to consider is the thermal shock to the chips, some are super sensitive to the temperature changes and others wont last if kept at too high for too long.
If I had to fit these chips and didn't have a screen printer, pick n place machine, & reflow oven, then I'd use a nice pointy iron tip with some thin diameter tin lead solder. As others have said, apply some flux to the leads and pads. Apply some solder to one pad in one corner. Solder the chip in place on the one pad and check for squareness and positioning. Once happy, do the other corner and double check positioning - because its easier to fix it now than later. If all looks good, solder up the other legs.
I was always told I used too much flux but my joints were virtually the same as what came out the reflow oven.
You can use the same method to solder other smd components - solder one pad, position the part on the pads and heat up that one pad. Check position and solder up the other end. Flux is important and cleaning that off when finished is more so.
Hot Air Guns are really only used when removing parts from a board.
Tip: clean off the board with some IPA, use a cotton bud to help move the fluid about and remove stubborn deposits. Check the ideal operating temperatures of the paste / solder wire (too hot and you'll burn off the additives too soon).
Adrian. The reason why the computer is running faster with more memory is because it has to do less paging. Paging (also known as virtual memory) is where the computer will temporality cache memory on the hard drive.
When you order your PCBs you can order an SMT stencil that helps to get the paste only on the pads.
Dude, I'm glad you shared the mistakes because we ALL make them, but wow bless you for never having watched a video on how solder paste works! That being said your brutal technique worked okay to be honest! Probably not on anything with a finer pitch or smaller components though! You mostly made it hard by adding flux. That made the paste slide around and stopped your components from "sticking:""
Alternatively, since you have a hot hair station use a clip to hold the chip down, apply gel flux and hot air and touch your solder to each pin, or just use an iron if your hands are stable enough, these chips aren't that tiny. Solder paste only realy works when you have a stencil. You don't need flux - the solder is kinda sticky to keep your parts sliding off once they're stuck into it. It's supposed to be a bit like a glue in a way. You had a lot of trouble because the flux made everything slide around.
Best way is with a small amount of solder paste on the pads only and then gently put the SIMMs on a flat electric frypan / skillet. I've done a ton of SOJ+SIMMs this way!
hey ! i'm sure you're now ready to solder smd components with solder paste !
i'ts nice to see that some of us are working fine to keep going with older macs
Great way to get ram into the classics if you can't find any. For soldering the ic's, there is no sarcasm behind this, there are some really good videos, PACE is one of them and remember flux* is your friend (the no clean one). Great video.
Way back in the day a Friend of my Mother's worked for a PC Repair shop. The Repair shop's owner cleaned out the back room and since I worked on Computers the guy gave me 6 boxes loaded with old parts. In one of the boxes there was a odd looking RAM board. It had two 30pin edge connectors with short ribbon cables around 5 inches going to a bigger board that was populated with a 72pin simm socket. The board had a couple of jumpers and misc logic on it. I never got a chance to try it but it looked like it made a 30pin simm based system use 72pin and used two 30pin sim slots. I have no idea what company produced, looked kinda home made since I remember seeing a bunch of flux residue on it.
I do this kind of work professionally and there are two ways in soldering J-Style SMD-Chips to P.C.B. that I prefer. The first is to use a tiny amount of Epoxyglue to fix the Chips in position on the clean (No flux etc.) Board and solder them with special SMD-solderingwire (0,3 mm Diameter) using a microscope. The second way is to plot a solderingmask and use it to portion the solderingpaste on the pads. After removing the mask I fix the Parts with ceramicglue (extremly fast) and use hot Air with 320 Degree Celsius. What you do is great, cause I had to search a long time to get hand on such SIMs . Good work, and greetings from germany!
Oh my, one can sense the frustration! These chips are massive, they should be very easy to solder by hand. Just use thinner solder (0.5mm), tack solder one pin, then the opposite one, then put some flux and solder the rest. Great to see that the modules worked.
A dedicated toaster oven can be used for surface mount. Instead of having a temperature controlled PID, I use a simple trick: I place a small length of fine solder wire on one of the PCBs. When it melts you wait a few seconds and it's done.
9:45 "The paste doesn't have any flux" ... huh solder paste is literally tiny solder balls in suspension in a gel flux.
yea, its so thick and not really wanting to flow because it was not refrigerated. we use this stuff at work on our stencil printer. solder paste absolutely positively without a doubt needs refrigerated or the flux gets dry and bad. then it all turns to crap from there. Everytime I order it, I have to do overnight shipping from Digikey or mouser with dry ice.
@@THEtechknight There is also the no fridge pastes. Like the chip quik TS391LT. I was happy to find this out after having it on the shelf for a year before using it :D
@@bwack Yea I dont know anything about those.
i've got old old old solder paste that I am sure existed way before any SMD existed.
@@bwack The non-fridge paste doesn't work nearly as well in my experience though...
Very experienced soldering iron/hot air wielder here:
If you don't have a stencil like in your case, tin the pins with your iron so they each have a tiny mound of solder on them. This is enough solder. Then just cover the IC legs in flux (your flux pen is fine) and add plenty of flux to the board and it'll work. You're 95% of the way there. More flux and pre-tin the pads and you'll get it next time you try! This saves you having to worry about having too much solder.
Haha! That's exactly what you end up doing! :D I always say to friends and colleagues: "it only has to work, it doesn't know how ugly it looks!"
Making memories with your viewers, such a wholesome channel.
Nice work, it always amazes me how members of the retro community figure out how to get round shortages of items. I suspect at some time in the future someone will come up with a replacement for the classic mac screens using a TFT screen as a replacement so that we can get round the shortage and failing nature of old CRT tubes, also means we can get rid of the dangerous voltages as well.
When the paste doesn't want to flow, I blob it out onto a piece of paper, and use a toothpick to smear a little on the pads. I also use a toothpick to remove extra paste.
That was a truly use useful video. I actually have a ton of RAM myself, in fact I just got a tester which should arrive today, but you never can have too many 4mb 30 pin modules. Great tip!
I would recommend taping over the edge connector pins to eliminate the risk of getting any stray solder on them.
Making your own RAM is pretty darn cool. That's a very useful project for restoring old computers!
Use a fine tip soldering iron,
1: place a blob of solder on one pin.
2: place component on pads and aline it with pads,
3: solder first pin,
4: solder a pin on the other side of component,
5: solder the rest one at a time, clean.
Job done.
Also get yourself an ESD mat and strap to give the chips a chance.
I've never tried soldering J-lead packages like these RAMs but I'd imagine it would be quite hard to reach under the bend and get the iron where it's needed.
Adrian I know why I like watching your videos, you’re just so normal like me trying to solder, not the best! You seem a like a great guy to know and keep up the great videos! I’m always learning something I either forgot or didn’t know. Also the Commodore book I did get on Kindle and it’s been fantastic. Boy the mistakes they made back in the day but a lot of fun to read how the Vic and 64 were developed was fun also the PetJet antics!
I learned SMD soldering via a similar method to yours! First try was a disaster, I discovered that with solder paste, a little goes a long way! I used a toothpick to smear a film of solder paste on to a flux treated PCB I used two techniques, for some things like ICs I would heat up the solder first until it was evenly distributed over the pads, then I used tweezers to place the IC onto the tinned pads and used a little more flux carefully heated the IC until, like you discovered, the chip dragged itself into place. Other times I would skip meting the solder paste and applied the component direct to the pasted pads fluxing before hand. Experimenting with the airflow can help, using a lower speed can help you get the nozzle a bit closer without knocking the component off line and prevents random pieces of solder getting splattered around the PCB. I think it's just a case of feeling out what works and from then on just refining your technique. Now I find SMD soldering so easy I wonder why I didn't learn sooner!
I usually use a toothpick to get just enough paste to cover the solder pads, then heat the board until the chips "snap" into place. My heat source is the good old Harbor Freight science hair dryer.
Yes you are correct video mem was shared. The LC III I used back in the 90’s was a pig in mud until I threw more rake at it. Good job
I soldered SMD with hot air only once in a small workshop. If I remember correctly you place a chip on the PCB then put some paste at the pads/pins (e.g. in a small line). If you heat this up the flux in the paste should pull the chip and the solder to the pads automatically. If it doesn't work add more flux and reheat. In hard cases you can also use a hot soldering iron and draw it along the pins.
This is so hard to watch. Even magnifying lasers wouldn't help me without a sentient robotic assist. BRAVE.
I’m a total noob as well and had always been scared of smd. Finally got brave and bought a hot air station. Now I actually prefer smd instead of through hole. I’m 50, with bad eyes, and shaky hands, if I can do it, I know you can.
I have never used a stencil, and it would probably make the job easier, but I am living proof you don’t need them.
The trick is getting the right amount of paste. It’s ok to smear the paste on if you use a consistent amount across al the pads. Be a little conservative with the amount you use, and you don’t need to pre-flux, there is already flux in the paste.
Get the chip close to aligned but it does not have to be perfect, surface tension of the solder will pull the chip into place.
If you do get bridges, take your soldering iron with the tip cleaned of solder and just touch the pins, the excess solder should flow onto the tip. If you have a stubborn bridge, hit it with the solder wick.
One last thing, be mindful of how much air you are using, the air can blow small parts out of place.
Thanks for another great video Adrian.
Finally! I have found another Mac Classic II owner!
You do have to say, it is very satisfying to use DIY RAM that you hand-soldered. I love your moments of humility, they are hilarious... but don't be too hard on yourself =)
If you want to see an expert at SMD soldering, I recommend tronix fix. That guy is amazing! He doesn't reball APUs, but other than that he fixes modern gaming consoles. Another good one is HDD Recovery Services. He recovers dead hard drives (which sometimes requires chip swaps) as well as USB drives, SD cards, etc... He uses thermal paste all the time. HDD services always pokes the chip to verify that it will slide back into place to know it's correct. Oh and paste is not required. I see them take a big solder blob and just drag it down the line to pre-tin the contacts. Once you put the component on you can drag the soldering iron across the pins. It doesn't take much solder. Oh and both channels use a microscope.
I was feeling your pain with that soldering. I've recently fixed a bad ram chip on my Amiga A600 which are very similar 40-pin J Lead packages. In the end my technique was, flux on the pads, put a little solder on a corner pad, tack the chip corner down with the iron, solder the opposite corner with the iron, then you get the iron to a couple of pins at a time with a little solder on the tip and let the flux do the rest of the work, the solder should flow onto the pad and leg if all goes well. Or if you have very fine solder wire, you can just solder each pin with that.
That brings back memories.... back in the times when you paid 100 bucks per megabyte I made PCBs and soldered ram chips into them to get 4 additional 1MB modules for my 386... and then I had to replace one ceramic cap with a SMD version on every board because it collided with the simm socket....
Now you have memories from 2020 :)
Soldering tip: place the chip w/o soldered pins, then solder one pin by hand. It's fixed now and the remaining pins can be soldered smoothly.
You don't really need flux on the components at all! Solder paste *is* flux mixed with small solder balls. For small DIY job, I mix a small blob of solder paste with a little bit of liquid flux from that pen in a ceramic cup, and then use a plastic toothpick to "pick" a small blob and move it around on the pads. The added flux makes it a bit more liquid and easier to spread. The "normal" consistency paste is made for stencils and is definitely too thick to manipulate.
Adrian, everyone has to start somewhere with new techniques. You can make the paste more liquid by warning it. I would do the bypass caps first too. A vacuum pickup can also help. You can get a really cheap air bulb one for about $1-2 so worth trying. Practice with the bent one a few times or practice with an old PC board. Good luck. Personally, even though I have experience doing SMD rework I would probably have slip soldered the legs with a soldering iron as they are visible along each side. get a large rounded chisel tip with a dip in the flat face which holds a bubble of solder. Good luck, I really enjoy your channel.
Soldering like these always amaze me when the solder just jumps into position. I tried my hands in SMD soldering a couple of days ago, I bought little PCB christmas trees and I have to assemble them by hand, 3x4 SMD LEDs, 4 SMD resistors and a triode. These components are so tiny, I had a hard time with it and I tried regular soldering iron. The good part was that the pads were already tinned but I had hard luck assembling my first attempt (bought 6 of them). I should try the heat gun for my next attempt.
The way you got it at 12:42 (when you re-did the second chip on the first board) is how you want it to be before you put the chip in in the first place.
As others have mentioned, using a stencil helps A LOT. If not using it, apply the paste, heat it with the gun so it forms on the pins, maybe touch up with the iron if needed, and then heat it with the gun and add the chip.
If you do it correctly, you should be able to do it without too much heat (which will cause the board to warp)
You're so hard on yourself! Surface-mount stuff is REALLY difficult, so I give you tons of credit for even trying!
When I first started with surface mount soldering, I used solder paste in similar applications to this. it helped me get a lot better at hand rework. Keep it up and you might be doing rework at a professional level in a short time.
That said, I definitely agree with the other people saying to use an iron for this application. The solder wicks around the legs really easily using an iron and a bit of flux, and doesn't warp the small/thin PCB.
Adrian, as usual it was a nice video! Keep it going man! As for the soldering, you could try this technique: First, apply some solder paste. Not much, and use an old credit card to help spreading it evenly. Then, you use the heat air to make the solder stick to the pads (here you will see how nice it magically goes to the right place). And finally you place the chip as you did on the first ones, holding with the tweezers, but not pressing too much against the chip. Hope that it works better for you!
Much love from Brazil!
Great video, I never even thought of searching for a project like this. So my 386 and 486's will be very happy in a few weeks. I can't wait to see if my 386DX-40 can do 8x 4MB modules
@13:46 Just a tip, when soldering smd parts, pre tin only one side and only one pad. Put the part on it, easiest when only a two legged thingy, heat up the pad with a solder needle, whatch the part sink in and sit flush. Then do the other leg / pad with standard methode, heat pad then come in with your solder containing flux. With multi legged parts it is a little bit more challenging and requires some training, but advantage of only pre tinning and soldering one leg is, if the part is slightly turned or a little off center, you can still easily correct that. If position is good, start soldering a leg / pad at the adjacent side via common methode. Rinse and repeat, takes some time but the result is showable.
Very cool! When I first started doing smt work I actually made full stencils for the pcb’s I was using from overhead projector acetate and a cnc hobby cutting machine to make the holes and then applying the thin layer of paste using a plastic card to spread it over the stencil. It works pretty well, but I found you need pretty good accuracy and steady hands to place the chips. I don’t have steady hands. 😆
With all smt work these days, as it’s just prototype stuff, I always go the ‘lots of tacky flux and flood solder’ route. I’ve not tried j-lead or qfn, but you should be able to do it ok with flooding I think, but probably more awkward than soic or qfp. I usually put some tacky flux down on the pads, place the chip, then just flood with solder and tidy up with wick where needed.
So much is just practice, and learning to keep your cool. 😆 Even under good conditions it’s a frustrating thing to do, but compound it with essential tremor and the patience of a saint can be required at times. I mostly use hot air just for removal these days, but everyone has their preferences and abilities.
Great videos, keep on doing what you do. 😄
Oddly, those could just be soldered, but you need a binocular microscope, very thin solder, and a fine tip. You have the skill.
That is a nice upgrade for the Classic II! And I truly feel your pain with SMT. I have a half-finished EasyFlash 3 cartridge downstairs waiting for the inspiration to continue soldering the SMT resistors and caps that I can barely see.
Okay, this is fucking sick. Imagine soldering something together yourself and putting it into a motherboard and having it work!
If you pre-tin solder pads like that, it leaves a rounded surface, which in turn makes it very hard to keep the legs of the device you're mounting positioned correctly. Next time, clamp the device in position (use like a large paper binder type clip). Don't pre-tin the pads. After the device is correctly positioned, with its legs on the correct pads, apply flux, then solder the joint. If the device has a lot of legs, you can "strip solder" them in one continuous go by laying a length of solder wire (of the correct size) across the tops of the legs. You then apply the soldering iron tip to the junction of where the leg makes contact with the solder pad. The soldering iron tip should contact *both* the leg of the device and the pad. The solder wire will melt, and thanks to the flux, wick itself into the correct position. You can also use soldering paste (as long as it has been correctly stored ;) ) for this. My personal preference is paste.
Make sure you use solder of the correct thickness! If you use a solder that is too fat, you'll end up having bridging problems. If you look at the solder you are about to use and think "well, that's going to be too thin" it's probably perfect; it doesn't take much solder to form a solid joint.
I would also recommend that you don't use hot air for this type of work. Not only is it more difficult, but it is also a lot easier to end up with a dry joint, as the solder and legs typically get a lot hotter than the pad itself does. Just use a soldering iron tip of the appropriate size and type and make sure you touch both the pad and the leg.
As others have pointed out, the carrying agent in solder paste is flux.
With solder paste it needs two stages of heat. one is just below the melting point to get the flux flowing and then increase to reflow the solder. Solder paste will have a reflow pattern data sheet to show the temps and time needed. When I do this with hot air I have a nice thick stone tile with a polished top so I don't damage my desk or silicone matt. I also never liked the paste from a syringe and had the same issues you did and would use something else to apply the paste. A stencil is so much quicker and saves a lot of mess, but for the number you have it's expensive. Soldering with the iron and plenty of good amtec bga flux is a lot easier for a small number of chips like this.
Hi Adrian. I think you did a good job considering the lack of tack flux. When you have trouble with solder between the pins, the first thing to try is a dab of flux, then drag the iron out from the pins.. tacky flux (designed for smd rework). If that doesn't work, touch the pins with a tiny (1-2mm wide) solder braid + extra flux. Doesn't matter if the solder bridge is behind the pins. It will just wick up on the braid. Personally I prefer flux and dragsolder, and solder paste only with stencil.
I wonder if the chips pin surfaces aren't doing you a favour. Maybe they are heavily oxidized and need some mechanical action to get clean. Not sure. I presume the chips are old stock.
Louis Rossman will be screaming at the screen. "Heat the board" Fair play at having a go, many of us would be like erm nope.
Seeing that you struggle with certain soldering jobs does give me hope.
And before I knew just what the video was going to be about, when you were talking about the rare high-capacity 30-pin memory, my immediate thought was "gee, sounds like some project some hobbyist group could come up with; some way of making substitute memory". And so what was the video about? Exactly that.
But as you were soldering, I could just hear a Louis Rossmann commentary about how to solder going on in the back of my mind.
Nice interesting video. I like it that you don't stop the camera on the learning curve with smd.
I only use dip components because i'm also afraid to mess up starting up smd soldering. After seeing this maybe i'll start with it
I recently bought a hot-air station. Like you said, it takes time and practice to get good at surface-mount soldering. To get some practice, I decided to remove and re-attach every component on a cheap DDR2 memory stick that I don't really need :)
Also bent boards can be straightened if they are bent to their original state, fixed somehow in this state and heated up to less-then-solder-melting temperature for some time. Some folks even do this to fix bent PC motherboards.
One thing I was suprised to find out is that early Amiga computers were wuite memory starved even though pretty much everyone who had one upgraded even the A500 to 1mb. It seems to make a real difference uprading them over 8mb. Since they share the same MC680x0 CPU series as the Mac Classic II it makes sense that this would carry over.
The amiga uses 2 types of memory in most cases. We have Graphics mem, that memory is shared between the CPU and the chipset and we have fast mem that only the CPU can access giving the amiga a speedboost.
@@Voyager_2 Yeah, i was thinking that when he mentoned it, it sounds just like the "chip mem" & "fast mem" in the Amiga.
Adrian, I would suggest watching some of Louis Rossmann's MacBook repair videos for tips on SMT soldering with hot air - it's amazing to see how 'sloppy' you can be when applying the solder and how well it comes out. You will notice he uses a lot of flux (available from his store) to heat up the whole component, not just one side. I think you will learn a lot from his videos - I know I did, even after 40 years as an EE.
In your defence, the J-leg chips are a bit of a pain to solder. lol
The last time I manually soldered some, it was for swapping the DRAMs on an Atari Jaguar that I was repairing for somebody.
I thought it would be a quick job, but it had been many years since I soldered SOJ chips (even though I've been soldering TQFPs, QFNs, and all sorts since).
I normally use a small 2mm chisel tip on a Metcal iron, tack down the corner pins, then manually solder the rest after adding a dab of liquid flux.
But I had real trouble getting enough solder to wick between the pins and pads without bridging stuff. It took me about an hour to swap four DRAM chips. lol
It looked fine in the end, but the fault turned out to be a tiny spot of corrosion on the Interrupt trace to the 68000.
To second what others have said here, using solder paste directly with these chips is generally not the best idea for your sanity. :p
It can be used on certain components if exactly the right amount is put across the pads.
But really you needed a stencil, and you'd be amazed how quick and easy it is.
This was genuinely my first ever attempt at using a solder stencil at home (about a year ago)...
i.imgur.com/KBdaMXw.jpg
i.imgur.com/Xnza7T9.jpg
I did the solder paste in one *single* pass, by adding quite a thick line of paste at the top of the stencil, about an inch above the SMD holes.
I then used a plastic business card as a squeegee, holding it at a 45-degree angle to the board, so the solder paste bunched up in a line as it rolled over all of the stencil holes.
(using a fair amount of pressure to keep the squeegee edge flat to the stencil, and the PCB taped down very firmly. Taping down some junk PCBs around the main one is also important, so it keeps the correct height, and doesn't move at all.)
I then just carefully plonked the components on, and reflowed the whole board in a modified toaster oven using a "Tiny Reflow V2" and fairly cheap leaded solder paste. For smaller stuff like the DRAMs, you can get away with just using a hot air station.
I would recommend NOT dabbing the solder into the stencil like a lot of people seem to do on their first attempts.
It's best to just do a single pass if possible, otherwise dabbing the paste tends to lift the stencil a tiny bit, and smears the paste underneath (shorting between pads etc.).
As you said, soldering the SMD stuff definitely gets easier with practice and finding the right technique.
But I wouldn't personally use solder paste for the SOJ chips, just manual soldering with a small chisel tip and plenty of flux.
The memory chips are quite accessible for hobbyists, and can be easily soldered with an iron and solder wire. I would guess that the pitch is 1.27mm. Unfortunately, they are no longer manufactured.
The solder paste is dry, and that is why you need to keep it in the refrigerator. The flux simply evaporates if the solder paste is not kept in proper conditions, especially after being opened for the first time. You are better off using solder wire and some flux, and a temperature regulated iron (or a 25W iron cooled periodically) with a suitable tip. Hoof tips are great.
Your hot air is probably too hot. You should use a bigger nozzle, reduce the heat a lot, reduce the air flow a bit as well (to keep the components from flying). Mind that you have to regulate the heat accordingly in relation to your air flow. Also, keep the distance from the board and try to pre-heat the board evenly, by wiggling the nozzle at a distance (about two or three inches away). When soldering, keep the nozzle at a distance of one inch. Take your time until the solder paste melts and flows.
Your iron temp might be too hot as well, since you mentioned some lifted pads and traces. You should reduce the temps to below 300º, and be quick about it. Flux more than helps when cleaning solder bridges between pads. You just need to do one in and out movement, and that takes one or two seconds at most. Don't dwell too much and be quick!
To clean the boards, doing ultra-sonic cleaning is ok, even recommended. Don't use soap and water. Use distilled water if the flux is water soluble, or use isopropyl alcohol if not.
As for the silicone mat, I have the same you have. It is heat resistant, alright. But it is pretty much conductive and tends to warp due to thermal expansion. I would recommend an extra layer of two silicone translucent white ones on top of that. You can find them on eBay.
In hindsight, I hope you view my advice as constructive. I was far from perfect when I first soldered, and I still have that PCB to remember my mistakes (namely, too much solder). It worked, but there is always room for improvement. In every case, practice makes perfect. So, practice a lot and drop the solder paste. You can find tutorials where SO-8/14/16 chips are soldered. The pitch is identical, despite the differences in the format of the leads. The technique is pretty much similar.
I seem to remember that Macs had virtual memory, which was system software that used the hard drive to supplement the machine’s physical ram. But virtual memory slowed things down. However, having a lot of physical memory for the system and programs allowed faster operation.
I must say well done Adrian!!!! I too do not go near SMD soldering for the same reason as you. It requires a certain skill to pull it off. Well done, great job!!!
Yeah I'm a bit apprehensive about SMD too for the same reason, although i must admit that the videos I've watched make it look relatively uncomplicated.
@@BertGrink it is much more difficult than it looks trust me. I lack the tools also so I dont bother. Through hole soldering is best. But would be worth attempting SMD work I suppose.
@Damion Manuel ok I will check that channel out. Maybe I will give it a go, thanks.
I do the odd bit of SMT soldering, most of the time its mounting though hole parts where SMT is supose to go. It is a little tricky & fiddely, but you do get the hang of it.
A smaller needle on your syringe makes things a lot easier. Also, if you pre-warm the pads the solder will flow and stick onto the pads a lot easier. I have spent some time hand soldering 0608 (and smaller) smd and it can be a pain as a beginner as you certainly discovered!
Per Wikipedia, for the IIci, it was popular to install faster memory in the first bank of SIMM slots, as this is the bank used by the video subsystem. Otherwise, a video card could be used to free-up system memory that otherwise would have been used for the video subsystem. As for the Classic II, the only issue with speed might be if on-board RAM were slower than SIMM ram (which is the case in the Mac IIsi). The Mac IIsi could get a video speedup by increasing disk cache which would take up space in the on-board slow RAM, which would relocate video ram from the slow RAM onto the faster SIMMs.
I think the technique you used was out of order. You should have 1) Apply flux to the pad 2) Place the Chip 3) use a small bead of Solder paste on the outside between the legs of the chip and the PCB 4) apply hot air then use a solder wick with flux to remove any soldering bridges. It would have been easier for you if you has a stencil as mentioned before in the comments.
great vid adrian. i was nervous when i first started smd soldering. but over the last year i can handle 144 pin fpga’s easily now. i dread any through hole soldering now.
This was awesome! Don't be so hard on yourself, how else are you gonna learn without screwing up lol. I do, we all do. In many, many ways haha
really loving this video! its exactly the motivation and knowledge i need to try a heat station and smd myself; I think you could do a perfect job with the paste; trying to remove them without a ton of flux will let it get overheated more often
I always appreciate these videos. You are always so positive and it's a welcome break from doomscrolling.
You're doing great! Surface mount is a very different kind of skill. Once the pandemic is over I can highly recommend Jessa at iPad Rehab for microsoldering training. They have a one-week course that was incredibly instructive for me. It's centered around phone repair but if you can do microsoldering on phones the type of work you're doing here will be child's play.
Cool stuff, I'm glad to see someone has figured this out.
Hello Adrian's thanks for the great video and your soldering skills look like they are improving I have been working with electronics for 45 years . this ram will come in handy when finishing restoring my Mac Se/30 .
Love your videos bud. Easily one of my favorite channels.