Electronics Forum | Fri Mar 06 10:46:35 EST 2009 | davef
First, we agree with Loco that your QFP is nonwetting, rather than dewetting. Your sceen-shots look like ol' timey SnPb paste recipes. Turn-up the heaterometer dial. Second, on nitrogen: * We kinda think your O2 needs to be around 100ppm with 99.99%
Electronics Forum | Tue Oct 31 22:56:23 EST 2006 | davef
So at incoming inspection, what are the results for your "dip & look" solderability testing [IPC/JEDEC J-STD-002A] of the specific problem component?
Electronics Forum | Wed Nov 01 08:55:05 EST 2006 | russ
See if the solder is leaving the pad(s) and is wicking up the component. This is long shot but I have seen something similar to this possibly in a wave process. We had a very thin board and a very large QFP on top. During wave operation the solder
Electronics Forum | Thu Nov 02 12:18:31 EST 2006 | pbarton
What surface finish is your PCB?
Electronics Forum | Tue Oct 31 13:22:51 EST 2006 | realchunks
Are you using Houdini brand paste? It really depends on the part and pad size, but I kinda doubt that you�re paste is disappearing during the 2nd reflow. Do a side by side comparison of first pass versus second pass reflow and show your operator.
Electronics Forum | Tue Oct 31 13:32:16 EST 2006 | bobsavenger
yeah, that's what I've explained to them is that it is not going to disappear. Currently they are in the process of running this PCB again and I'm going to do the side by side comparison. Thanks for the input.
Electronics Forum | Tue Oct 31 08:08:15 EST 2006 | bobsavenger
I'm just looking for some fire-power here. We have a board that when it goes through reflow the first time, everything is fine and has good wetting. When we do the secondary side, one specific part is then Dewetting according to our production oper
Electronics Forum | Sun Aug 13 00:17:30 EDT 2017 | tsvetan
my guess is these components are with small pads and with not enough solder to hold them
Electronics Forum | Thu Oct 25 04:52:17 EDT 2001 | Vai
I'm running intrusive reflow. What happened was when the board went thru' the first reflow ( which is secondary side ), at Post reflow, I can see the solder joint quality is very good smooth and shiny. But when we proceed with the 2nd reflow, at Post
Electronics Forum | Mon Dec 22 19:43:43 EST 2003 | Dean
I have seen this affect on Immersion Tin and OSP. 70 to 90 % of the solder wicks to the lead and forms a "single" homogenous solder mass. This even though the pad was 100 % covered with paste... Evaluated different solder paste...did find variatio
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