reduce solder stop opening sizes for pads of U2, U3, U4 and U7
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.
- 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.
- 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)
- File after.jpg after.jpg added
- File track on U3.jpg track on U3.jpg added
- File track removed.jpg track removed.jpg added
- File updated soldermask rule.jpg updated soldermask rule.jpg added
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.