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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