topic Re: 9.4, different pad sizes in library (footprint) and pcb in EAGLE Forum (Read-Only)

9.4, different pad sizes in library (footprint) and pcb

notameadow — Fri, 30 Aug 2019 18:54:33 GMT

Hey,

I’m creating a custom part with custom pads, the size is 68/76 long (I know, it’s tight with 100mil spacing, that’s another matter).

But, in the footprint editor it looks like this:

Which is still within manufacturing tolerance for me, but the layout editor shows:

I have saved it, I have updated all, I also added a new part again from the library to be sure it's not some refresh issue.

What did I do wrong?

Thanks.

Re: 9.4, different pad sizes in library (footprint) and pcb

rachaelATWH4 — Fri, 30 Aug 2019 19:28:32 GMT

Hi,

This is a very common question and is due to the annular ring setting in the DRC. The pads of the footprint are defined in the library with the "auto" setting for the diameter parameter so EAGLE calculated the diameter based on the hole size and the DRC settings. You will need to adjust the setting to get the pads to look correct but beware this setting applies board wide so will likely to affect something else too.

Best Regards,

Rachael

Re: 9.4, different pad sizes in library (footprint) and pcb

notameadow — Fri, 30 Aug 2019 19:41:15 GMT

Thanks but I’m not sure that’s the case here - I don’t have diameter set to
auto (for the pads), it’s set to 76 with 68 hole.

Is there another auto in DRC that overrides this?

Re: 9.4, different pad sizes in library (footprint) and pcb

one-of-the-robs — Fri, 30 Aug 2019 19:59:01 GMT

Nonetheless, @rachaelATWH4 is right that it's the DRC rule. The DRC imposes a MINIMUM for manufacturability, and if your library specifies a pad size that would break that then the pads still get enlarged, even if they're not "auto". They just don't get shrunk if the annular ring setting is very small.

Re: 9.4, different pad sizes in library (footprint) and pcb

notameadow — Mon, 02 Sep 2019 11:46:17 GMT

Thank was indeed the case, thanks!