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
>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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