Hello,
There are LT4200 datasheet

Any idea how to create "comb pad" shape (outlined red)?
Can I draw shape like filled polygon and then assign as pad?
Or draw some rectangular primitives and merge them and finally convert to pad?
How to do it right way?

Best Regards, Victor

Hi Reinier
Thank you very much.
Your recommendation work well!



Any other ways for creating specific pads?
Unfortunately (AFAIK) KiCAD can not define polygon (or poly combination) as pin ... Am I right?
There are "Custom Shape Primitives" in "Pad Properties" Menu... But this tab content is not active.

-- Regards,
Victor

UPD:

Found nice tutorial for creating custom primitives
https://www.youtube.com/watch?v=pSS_IRM5KIY

At least this will violate AD recommendation.
Also... do you have any PCB DRC errors about clearance?

On Tue, Mar 22, 2022 at 01:20 PM, Alan Pearce wrote:

This will allow the pads to produce the solder mask for each individual pin without having a long strip of solder.

My guess is that they expect solder along the strip, either for current capacity, thermal transfer, or both.

This is one of those cases where you want a part in hand as the documentation is wholly inadequate. They do an excellent job of hiding the thermal resistance spec (in the pin configuration drawing, no where in the specification tables) and almost no information on the conditions required to obtain this number other than "JEDEC PCB" which while useful, is far from complete. AD used to do a better job.
?
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Oz (in DFW) N1OZ

开云体育

Hi,

On Tue, Mar 22, 2022 at 01:20 PM, Alan Pearce wrote:

This will allow the pads to produce the solder mask for each individual pin without having a long strip of solder.

My guess is that they expect solder along the strip, either for current capacity, thermal transfer, or both.

Correct, page 15 under "Layout Considerations" it says "Make sure to minimize the solder joint resistance at these VDD pins by applying solder along the whole length of the V DD bar[...]"

This entire section talks a lot about resistance, heat, thermal vias, PCB layers, etc. Utterly fascinating stuff, I wish I would understand it...

No, it was a lucky find on my part. Blind monkeys sometimes find a banana too... ;-)

??? Konrad

Final result using Custom Shape Primitives

On Wed, Mar 23, 2022 at 04:14 PM, Konrad Rosenbaum wrote:

No, it was a lucky find on my part. Blind monkeys sometimes find a banana too... ;-)

Still a good find.? I had to really search for the thermal resistance, and it wasn't particularly useful when I found it.
?
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Oz (in DFW) N1OZ