If you are wire bonding to silver inside a sealed package, this should be OK. The majority of electronic components out there today with metallic lead frame substrates are electroplated with about 5 microns of silver to which the chip is attached and wire bonded, then the package is sealed and the components are sent for the remainder of assembly.
As for your second question, Shipley Ronal is a new company resulting from the recent acquisition by Rohm&Haas of the former LeaRonal; it represents the former LeaRonal combined with the PWB operations of Shipley company. Shipley Ronal is a leading supplier of metallization (electroless and electrolytic) processes and ancillary processes for the PWB, semiconductor packaging, connector, and decorative/base metal finishing industries.
Rob Schetty
Shipley Ronal
Freeport, NY USA
-----Original Message-----
From: Phil Hersey <[log in to unmask]>
To: Rob Schetty <[log in to unmask]>
Date: Thursday, January 28, 1999 12:04 PM
Subject: Re: [TN] Thermosonic ball bonding to .... silver?
Makes sense- I wonder if I could get away with it because my part is hermetically sealed?
Thanks Rob. BTW what does Shipley-Ronal do?
Resp.
Phil Hersey
-----Original Message-----
From: Rob Schetty <[log in to unmask]>
To: Phil Hersey <[log in to unmask]>; Technet <[log in to unmask]>
Date: Wednesday, January 27, 1999 11:02 PM
Subject: Re: [TN] Thermosonic ball bonding to .... silver?
>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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