Why not put 100u-in of Nickel between the copper and gold?  This is typical
industry practice.  Gold over copper without solder reflow from the assembly
process is only asking for trouble.  After a few years oxidation from the
copper will be very apparent, and depending on the area of contact could
cause failures. The cost for adding the nickel should be minimal.

Be afraid, be very afraid...

Roger Stoops, CID
Trimble Navigation Ltd.



-----Original Message-----
From: Ray Klein [mailto:[log in to unmask]]
Sent: Wednesday, August 14, 2002 8:41 PM
To: [log in to unmask]
Subject: [TN] corrosion on gold flashed PCB's


Guys,

We use 6-8 micro inch of gold flash over copper on our surface layers.
Mostly these areas are covered with solder paste and don't cause a problem.
We are considering using large areas of the board as heat sinks without
solder paste and are concerned with corrosion of the copper underneath this
very thin gold layer. Has anyone tested for or had experience with this?

Ray Klein

JNI
10945 Vista Sorrento Pkwy
San Diego, CA 92130

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