Lee and all, thanks very much.  I've just sent a summary of the
responses to our CM and have asked for cross sectioning to be done.
Regardless of the "why" there's a very nice, but frustrated operator
named Carla on the production line having fits trying to insert tab A
into hole B and I've got to fix that before the next run.

Thanks for all the help! 


Bob

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee Parker
Sent: Tuesday, May 27, 2008 3:53 PM
To: [log in to unmask]
Subject: Re: [TN] PTH's With Immersion Silver

Robert

This is very bizarre.

I worked for Bell Laboratories many years and installed the first
immersion silver line in North America in the AT&T PCB facility. We ran
thousands upon thousands of boards through the process. We never had a
problem with undersized holes. I suggest you cross-section some holes
and measure the drilled hole diameter. Also, perhaps the fabricator
placed a layer of some foreign material (i.e. nickel) between the copper
and the silver or perhaps over-plated the copper.

Best regards

Lee

J. L. Parker Ph.D.
JLP Consultants LLC
(804) 779 3389


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Croslin, Robert
Sent: Tuesday, May 27, 2008 10:57 AM
To: [log in to unmask]
Subject: [TN] PTH's With Immersion Silver

We've been using immersion silver on our boards for quite a while with
great success, but in a recent run of a new product, we had the boards
come in with the PTH's used to mount RCA and audio connectors smaller
that usual.  The parts came in on the large end so it became very
difficult for the operator to insert them into the board.  Both holes
and parts were in tolerance and the holes were specified at the
recommended diameters.  Our CM has a woman who spent 20 years working in
pcb fab houses and she tells me that it's not at all unusual to have IS
boards with reduced ID's on the holes as opposed to HASL.  Has anyone
else experienced this?  If this is the case, we'll have to adjust for
this in the future, but it would be useful to know if this was an
anomaly or a normal condition?

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