Electronics Forum | Wed Jan 05 17:53:52 EST 2005 | SuePH
We had a contract in house that included a flex board which required an 18 hour bake at 105 degrees. The other brds got along fine with 2 hours, but the flex board would delaminate until we went to this long bake. I don't know how the engineer came
Electronics Forum | Wed Dec 22 19:09:17 EST 2004 | rohman23
Very strange...I just logged into the internet to come post this very question for all the lurking experts. We have a 16 layer rigid-flex that we have never baked. Our board vendor is expressing concern that we do not perform a pre-bake before assy
Electronics Forum | Wed Dec 22 18:09:07 EST 2004 | kmorris
At a previous job I had been taught that when reflow soldering polyimide flex circuits, it was necessary to pre-bake them before reflow soldering to prevent delamination. Our procedures said that there must be a 1hr bake prior to reflow, and the flex
Electronics Forum | Wed Mar 04 07:08:55 EST 1998 | Pat Copeland
I am looking for information on reflow temps for a flex board. There is only one 6 pin IC but the board has a 3M double sided tape. Is it possible to reflow without damaging the tape. Any suggestions?
Electronics Forum | Fri May 01 07:22:56 EDT 2009 | kareal
In my project of flip chip PGA production , I found serious delamination in interface of solder mask and first layer copper trace of substrate after UHAST 96hrs( 130C, 85%RH) reliability test. The delamination are always around one type solder bump,
Electronics Forum | Sat May 02 08:48:32 EDT 2009 | davef
You have a board defect. Any moisture and/or organic contaminants trapped by the solder resist during lamination may cause solder mask delamination, blistering and/or adhesion loss during subsequent soldering operations or during extended use.
Electronics Forum | Thu May 07 07:17:45 EDT 2009 | kareal
any other suggestion for it?
Electronics Forum | Fri May 08 21:53:07 EDT 2009 | kareal
X-section image: tin layer on top of copper trace.
Electronics Forum | Sat May 09 09:40:12 EDT 2009 | davef
The whitish tin layer and the solder mask appear to be incompatible, resulting in adhesion loss.
Electronics Forum | Sat May 02 23:31:06 EDT 2009 | kareal
Thanks davef. The defect always occurred during UHAST reliability, but not find in reflow. The key is that there is tin diffuse to copper trace under solder mask. is it a "normal" board defect and what is the potential risk for device? thanks!
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