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Bug #5109

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

Added by mschramm 6 months ago. Updated 5 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
electronics
Target version:
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.

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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History

#1 Updated by mschramm 6 months 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

#2 Updated by cibomahto 6 months ago

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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.

#3 Updated by mschramm 6 months ago

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

Looks good, please go ahead.

#5 Updated by mschramm 6 months ago

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

works for me - thanks!

#6 Updated by mschramm 5 months 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)

#7 Updated by cibomahto 5 months ago

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The soldermask around the pins of U3 was opened with explicit tracks on the soldermask layer, so I removed those as well as updating the rule.

Implemented here: https://github.com/openvizsla/ov_ftdi/pull/48/commits/190ed0aff6dfbbedd690af5e0bbf6b072a60e401

#8 Updated by mschramm 5 months ago

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

resolved - thanks!

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