Electronics Forum | Thu Oct 28 20:45:38 EDT 1999 | chris
Hi Dave, We suspect that the organic FM causes the non-wetting problem. FTIR analysis confirm that the FM is a flux residue. Dave we only used FTIR to detect organic contaminants, we also used SEM/EDX to determined the elemental composition of the
Electronics Forum | Mon May 25 08:37:28 EDT 2009 | d0min0
Hello, recently we changed supplier of the LF BGA, we did corossection and now have doubts... previous BGA specs : pitch 1mm, ball diameter 0.6mm future BGA specs : pitch 1mm, ball diameter 0.4mm on the crossecrion we found that one of the ball seem
Electronics Forum | Thu Nov 04 21:36:36 EST 1999 | chris
Hi John, Thanks to your reply, just one question is it possible that the solder paste ( flux material )applied to the pads cause the non-wet. regards Chris
Electronics Forum | Fri Nov 05 10:01:04 EST 1999 | Dave F
Chris: You can have more than "one question!!!" Anyhow, yes crappy solder paste can cause non-wetting, but before you go there understand why the paste is wetting some surfaces, but not others. Ta Dave F
Electronics Forum | Mon Sep 18 01:47:18 EDT 2017 | bukas
I would go with wire thickness + 0.4 to 0.8 mm for pad width, and pre-tinned lenght + 0.5mm what seems to me like problem is that it can easily roll off the pads in reflow oven
Electronics Forum | Thu Oct 28 09:25:35 EDT 1999 | Dave F
Chris: Typical non-wetting causes are: * Poorly controlled soldering process * Incorrect material * Surface contamination * Insufficient preheat * Misapplied solder mask * Shadowing Without intending to insult you, all of the causes of non-w
Electronics Forum | Fri Oct 29 09:36:42 EDT 1999 | Dave F
Chris: Thanks. SMTnet has a "Library." Buried deep within it is a listing of terms. The following is from that listing: Shadowing. When a component blocks the heat or solder wave flow from certain areas of the printed circuit board, resulting in
Electronics Forum | Thu Jun 04 20:06:30 EDT 2009 | davef
Since posting the above comment extolling the virtues of NSMD pads and disparaging SMD pads, we've learned that the points apply to all array devices, but in spite of that some designers of fine pitch [eg, 0.4, 0.5mm pitch] array devices choose SMD w
Electronics Forum | Fri Oct 29 10:02:28 EDT 1999 | John Thorup
Chris A lot of people have reported sudden, fab lot related problems with Ni/Au pads. These are usually characterized by a discoloration of the gold and called cheerful names like "black pad disease". This can be a process problem at your fab house
Electronics Forum | Tue Jun 02 21:27:22 EDT 2009 | davef
We've never heard of a situtation where oversized pads caused voiding. Your supplier is correct that the pads on the board should be the same size as the pads on the interposer, but this is to improve reliability issues. Search the fine SMTnet Archi
