Hi Ken: Maybe it is outgassing of organics from the tin....

Sorry Ken I couldn't help myself. 


                                                        Regards
	
Mike B.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Wednesday, June 21, 2006 9:16 AM
To: [log in to unmask]
Subject: [TN] Conformal Coat Voids

We are seeing something that we've never noticed before and wondering if
any of you have seen it and figured out a cure.

We are hand spray Type UR coating. The boards are very well cleaned and
dried prior to coating. What we are seeing is a lack of coating on top
of via's. It's most prevalent on small via's, .013" but we're seeing it
on some of the larger ones as well. When we black light the board you
can see black spots on top of the solder in the via.

It's not just a thin coating but an actual void area. It's exactly on
the dome of the solder of the via. Our nominal coating thickness is
around .003".

I sure would appreciate any help on finding a cure for this!

Thanks,

KennyB

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