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- Опубліковано 8 сер 2020
- Three ways to get your PCB design rejected by your PCB manufacturer.
1) Imperial/Metric conversion
2) Unexpected Trace/Space specifications
3) Goofing the Gerber resolution.
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#PCB #Manufacture #Tutorial - Наука та технологія
I actually always round up by default anyway to at least +0.05mm and sometimes even +0.1mm, just to be safe.
If I REALLY need that tolerance I always contact the manufacturer first.
I also stopped working in inches/imperial. To many companies and people screw these numbers up.
Excellent video Dave!!!!!
I guess we European circuit board designers where always aware of the imperial/metric issue.
@@outsideworld76 Yes, I guess, working in imperial units will give you a lot of other issues, like talking about ±5% or something is all of a sudden a much bigger step.
Which really works weird when you have something like non perfect fraction of inches.
I actually always wondered how they do that with Fahrenheit, since it's a non-linear scale. ±10% at 20 degrees F will give you a different tolerance compared to ±10% at 100 degrees F.
That's exactly the way to go. Never rely on the minimums of the manufacturer.
@@p_mouse8676 I really wonder how people in Celsius calculate melting and boiling points, as the underlying physics is based around absolute zero. Tin at 100 Deg. C is actually pretty close to melting and even 25 Deg. C is actually for metal migration still pretty warm. Yeah it takes time for the tin to eat into chopper - but hey: You car radio will be there for 10...15 years and it does get toasty and/or chilly in there.
What I want to say: using any degree system is non-sense when talking about temperature. Yes, Celsius is nice for boiling and freezing water and we happen to be salty water bags (close enough anyway), but for metals the scale is pretty much of no use.
@@sarowie That's not the point I was making. If you want to use a proper scale, use Kelvin.
The point is, that these scales are linear.
It really doesn't matter what a scale is based on. I don't understand why people keep saying that.
It's totally not relevant, because the number of a scale just simply shifts. Properties of materials also don't change with different scales.
Otherwise you are just to much stuck in absolute numbers and clearly don't understand what a scale is all about.
So people calculate melting points and boiling points the same way, just the numbers look different.
So I would really advice to read a bit more on the subject
Dave is finally in his final form
Brett Smith just need a jar for his head....
Lool
Yeeeeesssss... he will soon build his eternal body
Floating head? Looks like you're just 'flapping in the breeze' Dave 😂
He should also wear a green neck cover :D
@@antnk9040 Why not a green balaclava while we're at it. :)
yeah. a li'l bit of hot snot should fix it though.
lol I was like "WHATT??". :)
@@antnk9040 Yes, that Holly's (Red Dwarf) look would be great.
The floating head is great, imagine if you had a Microsoft Clippy-like Dave head in your PCB design software, "Uh-oh, it looks like that trace is too close to the pad!"
plus wah wah wahhh as the error sound
Sounds like a kicad plugin waiting to happen
The floating head is brilliant. I love it
Just imagine what a green balaclava would be like
Change the t-shirt to a turtleneck so you have a floating head.
But Australia man.
It gets hot... Guess air conditioning could help.
I have never seen anyone green screening and making a youtube vid as a floating head! This is genius, it lets more background be visible!
And head is the only important thing anyway.
I can't be the first, surely?
@@EEVblog Dave, don't underestimate your brilliance in the youtube space. A true trendsetter.
@@EEVblog A professor on Twitch does the same. Most videos are deleted, but here is a clip: www.twitch.tv/jhkrueger/clip/JollyShinyDotterelSpicyBoy
@@EEVblog Two years ago: ua-cam.com/video/M76g81G3bi8/v-deo.html - I like how he switches during the different parts of the video
We always lie that the head is the most important thing.
A shirt with just non green collar could avoid being strange
"Hi, it looks like you're trying to design a PCB!" unexpected flashback :D
*dink dink*
*shudder*
Dave using KiCAD's Gerber Viewer instead of Altium's one. Getting there, slowly, slowly... :)
Their viewer is the best I have seen. A few more features would be nice.
1) More layers (Yes I ran out)
2) Remember the file name for a layer and put it in the hint when you hover over the "visible".
3) A "there's your problem" layer that you can draw on
@@kensmith5694 you can go to the github project and propose as a feature
Come to the FOSS side, Dave! Bwahahahaha!
I guess after more than a decade of The Amp Hour, Chris's love of KiCad is finally rubbing off on Dave
I like the floating head, takes up way less space this way.
Agreed, it works well if the webcam view is at the top of the screen.
Love the floating head.
I like the floating head! Though it did remind me of Clippy.
"Hey! You're trying to design a PCB. Do you want......."
The resistance to adopt the metric system boggles me
I'm in the U.S., but do most of my mechanical design with metric dimensions and hardware as those parts are easy enough to source. But when you're putting together a board for people to add through-hole parts and solder themselves, well again it comes down to parts availability and the ubiquity of 0.1" (2.54mm) spacing. It does get weird when I have both JST 2.50mm connectors and 2.54mm pin headers, but overall it seems to work out best when the grid is in thou instead of mm.
It is very simple to do and costs are low, allow both today - no real problem, select a distant swap over date 10-100 years from now when only metric will be used, and all new stuff sold must use either both or metric only from a different future cut-off date.
As they say in the UK, we go metric inch by inch!
The machines were often designed "in the era of the inch". Notice how so many connectors are 2.54mm increments.
Soviet Union simply used a 2.5mm pitch instead of 2.54mm (0.1inch) when copying stuff. It was pretty much only noticeable with chips like 40pin CPU's where the error was enough to cause misalign. So we could start from such a "minor" tweak, I guess some machines could be adjusted for the small difference.
Could you Imagine if there was an Altium plugin like Mr Clippy for MS Word XD
Every time you do something dumb his head pops up
"oi! whatya doin ya bloody bludger!"
"that's not 0.9mm!"
"oi mate, yer DRC failed!"
Love the floating head. I recently ordered some PCBs from JLC as a complete and utter noob. The service was amazing. I messed up the gerber multiple times, and had issues with clearances etc; they were super helpful in getting it sorted (I felt pretty bad since it was only 5 boards!!). 1wk from order to delivery to UK so pretty stoked in the end.
They seem to treat their specifications in two ways - for some they'll reject a board and not try to manufacture it, but for others, I guess they just make it and if there are any manufacturing errors they can say "well, we told you you needed 0.2mm clearance".
This rounding error is definitely JLCPCB's fault. They've stated that is minimum trace width, so the minimum of the values should be sufficient. This also implies they should take care to round up, not down, if they're going to convert it. The row above implies either that mil is the source unit (as 0.127 is exact) or that they have 3 significant digits, so it should've said 3.55. Messy. Of course we can take the engineer's route and always pick the pessimistic value instead, but having to will cause cumulative margin errors.
The pad to track tolerance probably has more to do with guaranteeing the solder mask won't leave the track exposed or interfere with the pad soldering than any drill; drills are involved in the PTH and NPTH specs. This means the tolerances of three liquid processes combine (copper etching, soldermask, and soldering itself). Track to track is covered by solder mask so only the etching affects it, pad to pad may require masking off.
Like Dave said, you shouldn't be pushing the limits with a prototype PCB manufacturer anyway. That will simply leave you paying for a lot of defective boards with broken and/or shorted traces. I do my best to stay away from the minimums, and will only come close when necessary. If what you are designing needs the bare minimums listed by the manufacturer you are probably better off selecting a different (likely also more expensive) manufacturer to send your gerbers to.
I can see it both ways - on the one hand, if they say 3.5mil, they should do 3.5mil, otherwise it's false advertising and that's a very slippery slope. On the other hand, when you're pushing the envelope, it's your job to get the complete specification - at those widths, you need more than one number to describe their accuracy - how wavy is the trace, how parallel are it's edges, how wide is it's top compared to it's bottom...
PCB manufacturer is not a black box operation - good designers need to know how things work inside.
@@johnalexander2349 "they should do 3.5mil, otherwise it's false advertising and that's a very slippery slope"
They do not, in any way, guarantee that 3.5 mil works - they specifically say it is the minimum they accept.
@@ABaumstumpf No, in some countries' laws, it has to be functional for at least some applications.
I know there are cultural issues involved and such but frankly I think it's just not a sensible decision to work to deprecated measurement regimes in any field of science or industry in 2020. Why would you introduce such a source of potential error or conflict into your workstream when you have the simple choice not to?
It's amazing, the floating head Dave. Please let it randomly jump around the screen.
Now also get some green sleeves, so a floating head and 2 floating hands.
Sounds like a cool screensaver.
Can we get an ice cream van to go with the Green sleeves?
Love the floating head....
Somebody please send him a green balaclava
First time watching this channel. Very funny presentation. I've been designing PCB's and PWB's, yes there is a difference, for 42 years. I started using tape an mylar. There is no type, or technology of board that I haven't done. 25+ years for DOD and government and all types of commercial. Some important things for all of you to consider. Never design to minimum. Bigger is always better.
Gerber is only good for 7 decimal places( microns). Always output at max resolution to avoid truncation and roundoff. Consult with your fabricator before you start and as needed throughout your design.
You had tape on mylar, luxury!
ua-cam.com/video/ue7wM0QC5LE/v-deo.html
My first design was with "ink on copper" method.
You were fancy-pancy with your Bishop Graphics tape on mylar!
Dalo pen on copper clad for the win. Followed by stick-on resist footprints and tape on copper clad. Then comes the fancy-pancy stuff!
@@EEVblog Jeez. I might still have my original circa '79 Dalo pen in one of my junk boxes.
I've got flashbacks of vertically-hanging mylar sheets with tape in a pile on the bottom of the cabinet!
@@theantipope4354 I still have my exacto kit. Lost my slide rule.
Fun fact: Some board houses have different annular ring specifications for outer layers versus inner layers and sadly KiCAD doesn't let you specify these different tolerances for different (e.g. inner vs. outer) layers.
It is a feature that could be added. The nice thing about open source is improvements can be driven by what people actually want.
This will be available in Kicad v6. If you are adventurous enough you can already test it in the nightly builds (be aware that the graphical interface for entering the new DRC rules isn't done yet).
@@Eletronicafg
I think a plain text ascii configuration file and editing it is good enough.
Beating on the code that implements the feature seems a worthy thing to do next time I have nothing to do.
Excellent information, clearly presented as always. Could listen to Dave waffle on about PCB design for hours and learn a lot. There are that many considerations when you push the limits. Unfortunately.
The reason for the issue with 0.9mm is not that it automatically rejects 0.0889mm, but they round it up, and if that causes you to break clearance, that’s the rejection. The reason they put a larger clearance for pads to trace is because they want room for solder mask variance so they don’t expose your trace based on the offset tolerance levels. That’s why pad to pad don’t have that because they are both exposed, and trace to trace are both covered. They should have called it soldermask clearance though, but that’s probably what it’s for. Lastly, as you pointed out later, most manufacturers consider smaller BGA chips to be “advanced” so yeah, different capabilities for different levels of manufacturer.
Dave, you are amazing, I love the way you speak, your accent, and how deep you go into the subjects you talk about. As a just graduated electrical engineer it's amazing to watch your videos, thank you very much, your contribution to electrical engineering is priceless !!
I do love anything you post on PCB design...more please!
Thank you for all your detailed explanations that me as a dyslexic can understand. Wish coding could be explained so nicely. I struggle and it’s touch and go for me.
This is good info to have. Some fab houses like the one OshPark uses will take your board with whatever specs you have and try to fabricate it. They have minimums listed on the site, but if you go below that they will warn you that your yield could suffer and they will not attempt to remedy the situation for you. You're stuck with faulty boards.
I'm sure all fab houses are different, so knowing that some will just kick it back without even attempting it is very good to know.
LOVE head-on-a-plate-Dave!
Thanks. You just saved me a hassle with the silk screening on a couple device patterns on a board that I am designing now.
I'm loving the floating head thing!
Absolutely love the floating Dave
It’s airhead Dave! Hilarious and creepy at the same time.
I like this format actually, Dave, with these kind of videos.
Wonder how the green screen would fare with Mailbag.
Floating Dave finally!!! Awesome :-D
Dave, floating head is great. It looks great and it leaves more space in the video. Regarding the pads vs trace clearance, pad clearance will be limited by the solder mask tolerances, which often times is lower. About the BGAs, I think that in-pad vias are the way to go, if supported buy your board house.
I love the head concept! I just love it!
@EEVblog in kicad you can go in and set the minimums in the board setup but all you have to do is make sure that you check with the board maker company and get what their minimums are.
Loving the severed floating head.
Thanks for putting up this video, I'm just about to take the plunge and have my first board manufactured!
Things that may explain stuff.
The pads may be done on a different pass than the traces and this may lead to a repeatability issue. It certainly did in the past.
The soldermask edge to copper accuracy is not as good as copper to copper. This can make trouble of exposing a trace that was supposed to be under the mask.
Last I checked, Kicad stores X,Y as integer numbers of 1E-4 inch increments. You can suffer from two roundings as the dimensions are converted. This is done because the numbers for almost all packages come out more even in tiny fractions of an inch. History rules destiny on this.
Yes, and I think there is supposed to be a fine line of soldermask between those two exposed pads, and the soldermask is going to have a minimum width. There's going to be some small registration error between the soldermask and the pads.
I love Dave's head just flying everywhere
love the floating dave head XD. Though when you have your shoulders in and your body is cut off it's kind of neat as you can position yourself to be coming out of text boxes or whatever you are displaying at the time. Have fun with it, why not?
LOL floating head was the best. Great video.
I've never laughed this hard on an educational video before, thanks Dave for the bobbing head :)
Good video, thanks! Looks like old good Dave is back with us. :)
13:20 There are a few different reasons to have different spacing specs for plated and non-plated through holes, drilled vs. non drilled pads, and features on the same or on different nets and they are all etching and plating related.
PCBs in the 10/10 micron lines/space range are often produced in pattern plating mode. I.e. the pattern is not etched from a full thickness copper foil. Instead a thin seed layer is plated in electroless mode, then the photoresist is applied and the pattern is filled into the openings of the resist. After stripping the resist, the seed layer must be etched away between the traces and pads. This will always lead to some wedge-etching under the traces and my leave bridges, if the gaps are too small. This is what limits the line and space width capability of the process, and you can see, how shorts within the same net are not that critical.
With pads around holes, the problem is usually adhesion-related. During the PTH process, chemicals can creep between the pad and base material. That weakens adhesion of the whole pad, and causing air or water caught in these pockets that can explode in the reflow oven.
And there are lots and lots more things that can go wrong during muli-layer PCB manufacture...
Wonderful video
Even before you announced it I fell in love with your new shirt
Floating dave head is amazing, you should most definitely do it again!
Thanks for the video. I use JLCPCB myself, and it doesn't seem that they touch the gerbers at all. However, I haven't done any fine pitch (nothing finer than TSSOP-2, and no traces finer than 6mil) PCB's and so have not had any need to push the limits of their process.
I love the floating Dave head!
thanks very much it saved me a lot of time. and loved that floating dave 😀
Small drills do wander, but you also must align the the holes and vias among the various copper layers. When many layers are assembled, the probability of having all of the wanderings be small or in the same direction decreases.
I think the floating heads lends a unique character to the videos. It's a winner!
Nice video Dave- very helpful! Wondering why the pcb fab/software don't have an export/import default json file etc for the design rules. Would seem to solve a number of potential pitfals. You could also export the rules you like for different types of projects.
Ive always wanted a little floating Dave on my desktop
0:40 missed opportunity to do the pac-man WAKAWAKAWAKAWAKA
I don't know, on one hand its awesome to see you, on the other hand its a bit creepy.
Why not try a green scarf next time? :D
or green turtleneck
Why stop there - green facepaint - disembodied eyes, glasses and mouth, anyone?
Love the floating head Dave.
I can hear it now:
"Your design is stupid and you should feel bad!" - after reviewing a 2 layer breakout board for my 128 pin MIL circular connector
Dave, I love your floating head.
I add 16mil isolate on inner layers since I've had boards come back with the holes too far off. I also have had boards with spots that are not completely etched. I also had a board house not remove Silk over pads.
Floating severed Dave head is best! I agree with the turtleneck comments too. And extra bonus points if your ethereal head moves around and your eyes look at whatever you're talking about.
If JLC is using metric, they should really write that spec as "0.09mm (3.6mil)". The way it's written, I'd *totally* assume the actual value is US customary and they're providing a metric approximation for convenience. Providing US customary below the actual spec (rather than rounding up) helps no-one.
Floating head is perfect :) thanks for great video.
The gerber viewer has grid options for 0.1 thou. It lists imperial first and then metric.
The floating head is excellent :D
It sometimes appears your head is appearing from a via. With your energy level, make sure you add some thermal relief!
The head thing reminds me of RIchard III from the first Blackadder episode. "Have you got transport Dave?"
I agree with you Dave, it did look better with the shoulders aswell.
I read English / Metric conversion rounding caused issues with the Soviet IC industry. They rounded the 0.1" spacing. If boards/sockets and chips were from mixed systems, the more pins the harder to insert,
Good Vid. As usual! A tip on Pres. Kill the Hand movements.
LOVE floating Dave :D. it is better than pull up or pull down Dave .
with the laser micro drilling, you mentioned, for vias
do you have to worry much about the plating metals surface tension?
This is the exact problem I've faced with jlcpcb. If you have bgas is quite hard to route out signals. Due to those tolerances of pads and vias!
Love the floating Dave head!
I just placed an order with JLCPCB that has 3.5mil (0.0889mm) traces. It was approved. We'll see how it turns out in a couple weeks.
Love the floating head! I cannot avoid to think how floating hands also would feel
Big thumbs up for the floating head!
I tend to set my defaults to 6mil/6mil unless i need something special. I do this because after comparing most the common players for prototype PCBs, that is the largest spacing and width for their prototype boards. And that is another trap that I have noticed. Some places will list 3mil/3mil as their capabilities, but when you read the fine print, it is larger for their low volume prototype service.
For the floating head bit, make it bounce around like the old DVD screensaver logos, will he ever hit the corner of the screen perfectly? who knows!
i love the floating dave form
Weird-floating-dave-head is awesome! Some spider or octopus legs would make it even better!
not gonna lie! you are so awesome!
A big fan here!
Good to know, I typically work in mils when setting up my design rules. Lowest I've had was 4 mils with jlcpbc, so guess I was right on the edge of I needed to do a bit lower.
I remember seeing JLCPCB addons for KiCad somewhere. Might be that JLCPCB themselves distributes some of those packages.
Pad to track tolerance could be linked to accuracy of the solder mask. If the solder mask can't reliably cover the track within .2mm next to a pad you risk being unable to solder it without risking a bridge
good one thanks!.. oh and Holly Dave is a winner
I like the floating head really good
One fab stated the extra spacing was related to plating process, ion migration issues.
Pad to track clearance is about the accuracy of the placement of the solder mask. If the track is too close to the pad it might be accidentally exposed.
I’ve done a lot of PCBs on JLC and I think they check in software only the basic clearances. I’ve (accidentally) manufactured stuff well below their solder mask and silk screen tolerances and they usually come good (or in the case of solder mask once - completely missing). Haven’t tested them to drop below their requirements for trace widths/clearances but I think right in the upload page that will get immediately rejected (or price-adjusted).
Floating ED reminds me of the old game "Tonic Trouble" on WinXP hahahaha I love it
Love the floating head! NOOICE
You can assign a track to a net in KiCad (eeschema) by editing the track and picking the net at the top of the dialog, then it should let you connect them.
The severed talking head format is great Dave! It's hilarious, keep it!
Love the floating head
Dave - floating head is awesome. Try out a green turtle neck too for the next video.
i like the dave head without shoulders, saves screen space.
Love your green shirt! Long sleeve would be nice for floating hands!
With a wider view you could point really far in the screen with the floating hand, limited by your green screen I guess. FWIW, you can use your big tv as green screen.
Off the top of my head, you could import the Gerbers into pcbnew and check the actual trace widths there ;)
Actually I've ordered PCB at JLC with two 3.5mil tracks between BGA pads (at 0.6mm raster). They just made it without any complains.