Silver is prone to a phenomenon called "silver migration" which occurs under
certain conditions of humidity and voltage.  This can lead to bridging and
short circuits.  Silver is also prone to tarnishing.  For these reasons,
silver is mostly not allowed as a metallization on exposed areas of
circuitry or on external terminations.

Rob Schetty
Shipley-Ronal
Freeport, NY  USA


-----Original Message-----
From: Phil Hersey <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Wednesday, January 27, 1999 8:18 PM
Subject: [TN] Thermosonic ball bonding to .... silver?


>Has anyone experience with ball bonding to pure silver?  A thickfilm expert
>told me he tried it one time, thermal cycled the heck out of it, and the
>bond got stronger!  He had no idea why silver was not used for ball
bonding.
>Aluminum and gold are the only metals I know of commonly used for
>thermosonic ball bonding.
>
>If silver works, maybe I can convince my microvia PCB fabricator to install
>a silver bath- cheap'r 'n gold!
>
>Phil Hersey, Hytek Microsystems
>
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