What is The Right Pad Shape to use in PCB Footprints? | Tom Hausherr |
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- Опубліковано 9 вер 2024
- What pad shape do you think is the right one for footprints - Oblong, Rectangular or Rounded corners? I asked Tom Hausherr
You can watch the full interview with Tom here:
• How to create perfect ...
Links:
- Tom Hausherr: / tom-hausherr-cid-cit-4...
- Tom's company website: PCB Libraries www.pcblibrari...
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i must say i really like the short videos, they make me to be able to get a scope of the video and squeeze it into my schedule
For all who wonder about the radius, Tom recommends 25% of the shortest side, but not greater than 0.25 mm. So everything wider than 1 mm stays at 0.25mm.
For professional PCB design, the pad shape doesn't matter much for many components (see Mr. Hausherr's remarks for under-package pads in the last third of the video), and I understand that this channel is very much geared to the higher levels of PCB design. For 'hobbyists', so to speak, there's certainly no harm in mixing and matching pad shapes to signify things like polarity (square/rectangular pad = cathode), ground pins, and so on when a silkscreen is either not available or doesn't provide sufficient space to indicate.
You want to avoid sharp corners in HV designs cause the high electric field created from the geometry can increase chances of arcing so rectangular pads not always the best idea.
Thank you Robert for these types of videos.
I prefer rounded rectangular shape. Because when you use it, you can draw more traces between 2 pads because of the edges. And it is easy to build it. You are drawing directly rectangular then press CTRL+A and make it all rounded rectangular shape. Also, it has better looks, also when you solder it everywhere capture the soldering. Also, you can draw the trace onto the edge of the pad. And one more thing, it feels good and right :)
Yes, especially under BGA the corners can make difference.
@@RobertFeranec I haven't experienced with BGA yet. You are the GURU of the Altium and PCB design :). You should know better than most of the designers.
Love it Robert, more short snippets per topic!
These types of videos are awesome! Thank you!
I like rounded, cuz its look better! :)
I like rounded, cuz the routing becomes easier too! For the same component separation distance, the rounded pads will give larger copper-free area around the pads, so it becomes easier squeezing in the traces in between the two components :)
Great content as always Robert! I like the short videos and the clips from longer videos specifically based on a question. I seldomly have 2 hours to watch an entire video. 10 minutes is usually fine. What I see some youtubers do is they have a separate channel for clips from their longer interviews especially with podcasters. Maybe this is something you would want to look into.
Hello Robert, it's really great that your are helping others to think about the daily work. Thank you
Here I have one question, when a rectangular pads not cover solder in corners, the same will apply for Bottom terminations with rectangular pads. Why it is not recommended for bottom termination component's to have rounded rectangulars. I understand Tom said we should not reduce pad area, but still I don't think that solder will cover in corners. So I like to use rounded rectangles even for BTC. It improves rework ability by improving peel strength of pads.
Please correct me if I am wrong, I am so excited to know your response.
Thanks for this short videos !! Very useful format
Purely intuitively, I make the radius of curvature 20%.
The full interview had several important bits ... it would be helpful to break such interviews into shorter videos like this.
love the short video! thank you!
Nice video but it's clear you have a preference for rectangular pads which Tom doesn't share...
Thanks Robert!!!
His reason for using rounded rectangular pads is not very compelling. So what if that's how the stencil is made? So what if there is still some of the original plating visible? If he'd said something like the rectangular pad corners don't adhere as well so the chances of it peeling up are increased, then sure. But otherwise it is much easier and less prone to error for them to be consistent with pad shapes, in my opinion. As Robert said at the end, you can't really go wrong with making everything rectangular. That's my biggest gripe with PCB Libraries and the unapproved IPC7351 rev C. If it's not broken, don't fix it. It's making changes for the sake of making changes and has unilaterally been pushed into the market through PCB Libraries without support from the actual committee, or really anyone else. There is not much solid, corroborated data which suggests that these changes do any good in the real world.
Great video as usual.
love this channel!!
Actually some of this isn't entirely correct, the reason laser cuts have round corners is because it allows you to cut in a single vector path. Square corners require a laser to "step" - stop, position, move etc. A rounded rectangle allows a single non-stop cut path. Faster & more efficient.
How do you use a laser, which is circular and has a finite diameter, to cut an internal rectangle with sharp edges, without making cuts external to the rectangle like in a stencil?
@@lachlanchartier8061 That's because a laser is not of a finite diameter; real-life lasers have focal points, and they can be focused to converge at an infinitesimally small point (not technically in practice, but close enough). They are in practice to facilitate cutting (higher energy density) at the expense of focused cutting depth, actually.
Worth knowing!
Very useful Robert Sir.
I didn't even know this was a thing!
The tighter your design is the smaller pattern size you would want to use.
Was it as cutting a true rectangle was hard to cut out with a router bit.
👍👍Thank you!
Well there's your problem straight away, a rectangle IS an oblong, as are some ellipses. Oblong just describes any shape that is elongated in one direction. So you asked for oblong without understanding what an oblong is.
You asked manufacturers for oblong, they gave you oblong. I don't know about other countries but here in the UK oblong is often used (incorrectly) as synonymous with rectangle.
All of the shapes shown are oblongs.
Now I'm confused... dictionary definition of "oblong" is a rectangle! Does he mean "oval"?
i think i see it as when the masks were routed the rectangle would be cut with a round bit. So if the rectangle was 2mm wide the curves at the end would have the radius of the cutter e,g, 1mm. Now with laser cutting old ideas no longer count but we often stay with them as that’s what we are use to.
The correct term is "obround"
Any pcb software support D type pad?
Oh no, i've been using square pads in my libraries for 5 years now. =[
Maybe you are a good squeezer 😉
He sounds so disappointed in the end