Bug #5109: reduce solder stop opening sizes for pads of U2, U3, U4 and U7 - OpenVizsla USB tracer/analyzer - Open Source Mobile Communications

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Bug #5109

closed

reduce solder stop opening sizes for pads of U2, U3, U4 and U7

Added by mschramm about 2 years ago. Updated about 2 years ago.

Status:

Resolved

Priority:

Normal

Assignee:

cibomahto

Category:

electronics

Target version:

3.4

Start date:

Due date:

% Done:

100%

Description

The solderstop openings overlap for the RAM IC, so there are no ligament between - I'm fine with that for a 0,8mm pitch IC.

But let's reintroduce something that has been better in the former design than now: for QFP packages, please reduce the size of the pads' solder mask openings for U2, U4 and U7.

Their pads are (here: FPGA) 0,3, and gap 0,2mm. PCB house would always remove solder stop overlaps on solder pads anyways, so you can use the minimum distance pad copper-solder stop of 0,03mm. If you use this, the remaining segment would be 0,14mm which is about twice the allowed minimum of 0,075mm.

Files

solderstop-FTDI.jpg	View solderstop-FTDI.jpg	78.5 KB	mschramm, 04/09/2021 01:56 PM
solderstop-FPGA.jpg	View solderstop-FPGA.jpg	79.5 KB	mschramm, 04/09/2021 01:56 PM
solderstop-RAM.jpg	View solderstop-RAM.jpg	82.9 KB	mschramm, 04/09/2021 01:56 PM
solder mask expansion rule.png	View solder mask expansion rule.png	26.5 KB	cibomahto, 04/09/2021 09:41 PM
solder mask gap.png	View solder mask gap.png	55.8 KB	cibomahto, 04/09/2021 09:41 PM
after.jpg	View after.jpg	162 KB	cibomahto, 05/22/2021 06:31 PM
track removed.jpg	View track removed.jpg	780 KB	cibomahto, 05/22/2021 06:31 PM
updated soldermask rule.jpg	View updated soldermask rule.jpg	149 KB	cibomahto, 05/22/2021 06:31 PM
track on U3.jpg	View track on U3.jpg	774 KB	cibomahto, 05/22/2021 06:31 PM

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Updated by mschramm about 2 years ago

Subject changed from reduce solder stop opening sized for pads of U2, U4 and U7 to reduce solder stop opening sizes for pads of U2, U4 and U7

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Updated by cibomahto about 2 years ago

File solder mask expansion rule.png solder mask expansion rule.png added
File solder mask gap.png solder mask gap.png added

This can be accomplished by adding a 'Solder mask expansion' rule that matches pads in U2,U4 and U7. Will apply after the differential pair routing is complete.

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Updated by mschramm about 2 years ago

Status changed from New to In Progress
% Done changed from 0 to 80

Looks good, please go ahead.

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Updated by cibomahto about 2 years ago

Added here: https://github.com/openvizsla/ov_ftdi/pull/46/commits/c0fcfa320e103b58bdb92f53467fdd30a578d304

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Updated by mschramm about 2 years ago

Status changed from In Progress to Resolved
% Done changed from 80 to 100

works for me - thanks!

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Updated by mschramm about 2 years ago

Subject changed from reduce solder stop opening sizes for pads of U2, U4 and U7 to reduce solder stop opening sizes for pads of U2, U3, U4 and U7
Status changed from Resolved to In Progress
Target version changed from 3.3 to 3.4
% Done changed from 100 to 80

For the last production run, I intentionally did not include U3 (SDRAM) for this, as a pitch of 0,8mm usually is not prone to fail here - but it happened on one PCBA that we had a short between two adjacent pins on U3.

Please therefore also decrease solder stop openings on U3's pads.

(re-opening ticket and resetting state to avoid an own one as it remains the same issue)

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