I sent this link to one of our customers just the other day. We were seeing
a different problem but this might be what you have.
http://www.pwbrc.org/members/pdf/works99/Houghton.PDF#search=%22black%20pad%
22
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
Sent: Wednesday, September 20, 2006 11:48 AM
To: [log in to unmask]
Subject: [TN] ENIG Problem...
Hi All!
Wouldn't you know it, all these postings about ENIG and all of a sudden
an issue just started happening with some ENIG boards we're building.
The problem is sporadic. We're building a double-sided SMT board using a
SAC 305 paste, and I haven't seen any non-wetting problems with the SMT
yet.
We're selective wave soldering using SN96 and a RMA flux, and after
about 250-300 boards my touch-up operators flagged me down and said that
they're seeing some boards that have through-hole pads that aren't
wetting no matter what they do. Here's some pictures:
http://stevezeva.homestead.com/files/Non_Wetting_Pads.jpghttp://stevezeva.homestead.com/files/Non_Wetting_Pads_2.jpghttp://stevezeva.homestead.com/files/Non_Wetting_Pads_Close.jpg
The pads look like bare copper...no nickle. Is this related to the
latest thread? Like I said I haven't seen any SMT with this issue (yet),
and it just started showing up...we've built a few hundred boards with
no problems until now.
I'm having the operators set the boards aside with the problem. Am I
pretty much hosed with these boards?
-Steve Gregory-
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