Yes, I think our problem was oven contamination. We started wrapping
immersion silver boards in aluminum foil (loosely) during the bake. We have
not had any problems with delaminating or solder performance using this bake
out process. 

We have not tried to clean the oven yet, as we rarely see immersion silver.
I understand it is rather difficult. I think there are instructions in the
IPC SIR Handbook. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roberts, Jon
Sent: Monday, December 03, 2007 5:30 PM
To: [log in to unmask]
Subject: [TN] SILVER IMMERSION BOARDS ISSUE

We are experiencing silver immersion boards tarnishing during the solder
process (SMT Reflow).  Board manufacture along with some of our SMT process
engineer believe is sulfur getting on the board/assembly.  Has anyone
experience this recently?  Suspect areas are plastic bags, rubber bands, and
oven contamination. Any ideas or thoughts will be appreciated, Jon 

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