Electronics Forum | Fri May 31 23:48:14 EDT 2019 | dhanish
Thanks Dave..My customer proposing to reduce the solder volume.Can the TCT be improved by reducing the stand-off height?
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 | Sun Jun 30 20:00:56 EDT 2002 | redmary
the SOIC encounter solder crack after reliability test, the common process is: SMT---manual soldering---IPT(in process test)---potting---T/C(thermal cycling,only add current and voltage)---B/T and F/T (burn in and functional test). the condition is 2
Electronics Forum | Mon Jul 01 20:42:54 EDT 2002 | davef
Comments [questions] are: * It�s strange that an uggie ol� SOIC, 50 pitch, BIG honkin� solder pad, kinda thang is failing. Sumpin aint kosher, yano? * Where is the failure occurring [ie, lead to pad, pad to board, etc]? Talk about the breadth and di
Electronics Forum | Tue Nov 13 21:59:42 EST 2007 | davef
This processes has the potential to cause barrel cracking and pad lifting, because the heating is very hot [troop crank-up the volume on their iron when they see thick boards] for a relatively small area on one side of the board. What do we suggest
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 | 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
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 | Mon Oct 29 20:19:44 EST 2001 | davef
DON'T do it!!! The two problems you'll have are: 1 Poor manufacturing process control, resulting in weak solder connections. 2 Weak solder connections are stressed, when the board is straightened upon installation in the "box". There's several hits
