Electronics Forum | Mon Jun 24 23:21:27 EDT 2019 | sssamw
You may need tell us the background, how PCBA being tested, the test setting and spec. Solder crack maybe due to CTE mismatch or mechanical strain.
Electronics Forum | Mon May 16 22:59:40 EDT 2005 | davef
We believe your problem is caused by the mismatch in CTE of the material ised in your BGA. In fact, this "potato chipping" [where the corners curl-up] is present in all BGA. The issue is the matter of degree. [Mismatching CTE is how old thermostats
Electronics Forum | Tue Mar 09 20:08:08 EST 2004 | davef
Warping BGA are the usual cause of shorts in the corners and are usually caused by the reflow profile. BGA have a natural tendency to warp due to CTE and package thermal mismatch, as you have seen at rework. The PBGA will go from a bowl shape to an
Electronics Forum | Sat Mar 01 08:17:40 EST 2003 | davef
You're correct that the FR4 is probably the best choise. The majority of the problems in developing your reflow recipe is going to come from the CTE mismatches in the CCBGA , CBGA and PBGA that you put on the board. The other side says given the pr
Electronics Forum | Wed Jan 12 13:27:42 EST 2005 | carobin
The two options I see are (not including underfill): 1) Have complete conformal coating coverage of all balls with no webbing in between balls because of CTE mismatches. If all the balls are not coated we see failure in humidity testing. or 2) Sea
Electronics Forum | Tue Jul 25 12:14:39 EDT 2006 | russ
All my studies led me to believe that it was CTE mismatch of this package. Altera was of less than 0 help in this matter. The other possibility was an ICT test fixture. Unfortunately (?) the design life of this product was at end and the new design
Electronics Forum | Mon Aug 21 19:35:51 EDT 2000 | Dave F
Kyung Sam Park: Sure, several causes of plastic QFP package delamination, other than humidity absorption, are: * Corrosion on component leads * CTE mismatch between leads and package materials * Package material adhesion strength degradation Wh
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 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
