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 Mar 22 21:27:45 EST 2006 | KEN
Find out the lead frame alloy. Cte mismatch can cause the same defect. Ran into this 3 years ago wave soldering with Tin-Copper.....okay, you caught me. I admit it. Wavemaster larry told me about this and I'm posting it under my name. Shameful, I
Electronics Forum | Thu Sep 07 11:01:52 EDT 2006 | davef
BGA cracking is caused by mechanical stress. This may be the result of: * Rough handling of soldered board * Inadequate consideration during package design of CTE effects on BGA * Poor control of or selection of thermal ramp rates during soldering
Electronics Forum | Mon Nov 13 21:52:20 EST 2006 | davef
Higher Tg values are only one thing to look out for. Other things that are very important to watch are: * Td or Decomposition Temperature (the temperature that the epoxy actualy starts to break down). * CTE for the material. Some argue that Td is mo
Electronics Forum | Mon Nov 27 08:05:50 EST 2006 | davef
There is no standard for a strain gage measurement of allowable deflection of a board or a fixture. It's possible that your fixture is causing the BGA cracking that you see. What protion of the BGA is cracking? If it is the solder connection, sear
Electronics Forum | Sat Feb 03 08:56:09 EST 2007 | davef
Multiple leads in a single PTH is prohibited because: * Need to be able to remove and replace any component without impacting another. * Oversized hole required will result in increased solder defects and could also lead to flux entrapment. * Counte
Electronics Forum | Mon Aug 06 17:29:07 EDT 2007 | gsala
Hi Gents, I heard people having concernes by using 2512R SMD resistors due to potential solder joint reliability defect(CTE mismach among ceramic/alumina+solder+PCB) when soldered by lead free alloys (SAC like). Any experience/news about solder j
Electronics Forum | Sun May 24 21:12:59 EDT 2009 | keith78
I have a problem recently to qualify QFN package on solder joint reliability. The pcb thickness stated in IPC-9701 is 2.35mm but from the in-house test, QFN surface mount on 2.35mm thickness PCB board have a short cycle to failure due to higher CTE m
Electronics Forum | Wed Sep 30 11:32:45 EDT 2009 | pbarton
What type of conformal coating are you using and are you allowing the coating to migrate under the device in question? If you are allowing the coating unbder the BGA the problem could be CTE of coating is much greater than that of the BGA balls/sold
Electronics Forum | Thu Feb 11 08:14:41 EST 2010 | scottp
It's OK to have the daisychain done in the interposer rather than the die (and a lot cheaper) but in thermal cycling the parts MUST have representative die. That's where a large part of the CTE mismatch comes from to cause fatigue damage. Thermal c
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