Electronics Forum | Sat Jun 01 07:22:40 EDT 2019 | edhare
Just the opposite, reducing the standoff increases the shear strain range in temperature cycling, which lowers the number of cycles to failure.
Electronics Forum | Mon Jun 03 13:01:59 EDT 2019 | slthomas
Is there any chance that the boards were mechanically stressed (for instance, installed in a fixture) before, during, or after the testing? I'm just looking for other possible root causes.
Electronics Forum | Wed Aug 10 09:01:15 EDT 2005 | fctassembly
Hello Joseph, Sorry for the bad news but microcracking is a well known potential condition occuring with the SAC305 alloy. Microcracking is a condition being seen with many joints soldered with the SAC305 alloy. It is technically a shrinkage cavity
Electronics Forum | Tue Aug 02 22:49:55 EDT 2005 | davef
IPC-A-610D Section 5, shows a variety of photographs of: * Good lead-free solder connections * Lead-free soldering anomalies Hot Tear / Shrink Hole is one such anomaly. This shrinkage effect appears primarily on wave-soldered joints, but can also
Electronics Forum | Mon Aug 01 20:02:20 EDT 2005 | Joseph
We use SAC305 and top side particular joint temp. is 110 deg C, and the terminal finish for that particular lead is pure tin. It look like hot tearing at the primary side of PTH.
Electronics Forum | Mon Aug 01 06:59:02 EDT 2005 | Joseph
Dear all, We observed visible micro crack at top side of solder fillet during lead free wave solder process. We did not see any visible micro crack at bottom side, and it always located at joints of transformer. Any input be much appreciated. Best
Electronics Forum | Wed Aug 03 21:29:59 EDT 2005 | Ken
Yes, lead can promote fillet lift. In order to understand this defect you must begin looking at your lead frame mateials. some lead frames are more susceptable to this disorder. This is most likely a cte mismatch disorder. Lead contamination in
Electronics Forum | Wed Aug 10 10:41:23 EDT 2005 | patrickbruneel
Bob, Great theory if you're selling SN100C, but I have to disagree that an alloy being 4�C off eutectic will cause cracks. When a solder joint exits the solder wave, there is an immediate drop in temperature of 100�C. so being off 4�C is irrelevant.
Electronics Forum | Mon Oct 29 18:21:43 EST 2001 | slthomas
We recently have received a lot of warped (bowed and/or twisted behond IPC 600 specs.) bare boards (some our fabricator's fault, some ours by design) and I can't help but figure that long term reliability will suffer when building product with them.
Electronics Forum | Tue Oct 30 10:54:37 EST 2001 | slthomas
Hey, Preacher, choir here. Unfortunately I didn't get to make the call here (hot boards, new product, same ol' same ol'), but I dam* well am looking for future (print) backup to assist in persuading the bottom line guys that it's cheaper to wait for
