Paste another assembly and hand spray with active flux to promote
wetting to the oxidized pads.  

Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 21
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 
                           

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rich Wolbert
Sent: Wednesday, October 18, 2006 9:32 AM
To: [log in to unmask]
Subject: [TN] Oxidized PCBs

OK, I know you guys are probably going to shake your head on this one,
but
I have to ask. We have a double sided fine pitch SMT assembly and we
decided to go to white tin for the pad material. Here's where the
problem
comes in, we ran one side and when we started process the other side we
found counterfeit chips. We stopped production for two weeks until the
correct parts came in. When we tried to run the boards again, the PCB's
oxidized so badly over the two weeks that we can not get the solder to
wet. Any suggestions, other than scrapping the 170 assemblies at $600 a
piece?

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