Feel free to correct me if I'm wrong, but it is the nickel that breaks off
not the gold. The gold just comes with it, being plated over the nickel.
We've all heard of Ni-Cad batteries, well this is just a Ni-Cu battery and
the etch rate at the interface of the nickel and copper skyrockets. A
significant percentage of the time, the nickel breaks and splinters, but
does not fully detach, causing shorts from one trace to another. The only
solution is to attempt to reduce over-etching. Thicker nickel is not of
much help for this condition. It will still break off and "sliver",
regardless of thickness (within reason).


At 07:18 AM 10/11/02, you wrote:
>Steve: This is nothing new, it's inherent to the etch process with Cu/Au.
>You are getting excessive undercut and it's breaking off.
>You need tighter controls on your etching process. This includes chemical
>balance along with conveyor speed and inspection of product coming off the
>etcher. The goal is to minimize chemistry swings and exposure time in the
>etchant but still produce a complete etch.
>
>If possible 1/2oz outerlayer Cu will definitely help.
>
>Assuming you are plating Ni over the Cu prior to Au you may want to
>investigate a thicker Ni barrier plate to add support strength to the Au
>"wings" so they don't break off as easily.
>
>
>
>Regards
>
>Michael Barmuta
>
>Staff Engineer
>
>Fluke Corp.
>
>Everett WA
>
>425-446-6076
>
>
>-----Original Message-----
>From: Steve Mac Donald [mailto:[log in to unmask]]
>Sent: Thursday, October 10, 2002 1:00 PM
>To: [log in to unmask]
>Subject: [TN] Undercut peeling on all Gold Board
>
>
>Good Day to everyone,
>
>We have been experiencing an issue with deep gold plating after etch.  The
>undercut is breaking away making the traces look "hairy."  The gold either
>clings and drags away from the trace or breaks loose at LPI/Soldermask and
>floats in the ink to some other undesireable location. It is not consistent
>but it is persistant.  Has anyone had this issue before and could someone
>suggest some possible solutions? (It never happens with standard copper
>plating--just deep gold.)
>
>Thanks,
>
>Steve MacDonald
>Mass Design
>
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