Electronics Forum | Thu May 07 20:28:35 EDT 2009 | davef
From our notes, the following is a series of snips from: "Copper Dissolution in Tin" LJ Turbini, PhD, adjunct faculty member, University of Toronto, Materials Science and Engineering, SMT 2/07 As the solder becomes molten, copper from the board diff
Electronics Forum | Thu Sep 01 18:53:08 EDT 2005 | Board House
Pr. I agree with some of the above responses. if you are seeing Delam issues with incoming PCB's the following should be check. 1) Check the OEM Print to what Material they are calling out to be manufactured with. 2) If they are calling out for S
Electronics Forum | Fri May 08 20:59:21 EDT 2009 | kareal
Davef, do you have some information about your mention "tin was used to protect copper trace ans will be removed"? It is very important for my project. Because we are assy and test plant, no any information from PCB vendor. Thanks!
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 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 | 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!
Electronics Forum | Fri May 08 04:39:32 EDT 2009 | kareal
Hi Davef, I want to explain that the tin diffusion in my project is not on solder bump/Pad region. It is on copper trace between bumps. so it is very wondering for me.
Electronics Forum | Fri May 08 09:44:23 EDT 2009 | davef
Board fabricators use solder as a resist to protect copper traces from process chemicals. Fabricators remove this resist in later processing. It's possible that board fabrication processing is the source of the tin that you see.
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