Larry,
        The gold is an attempt to improve the solderability of the palladium.
The palladium can't be dissolved until solder is actually touching it.
The theory is that solder will wet out onto the gold quickly, then it
will have a longer contact time with the palladium to dissolve it.
        I don't have first hand knowledge, so I would like to know if the
theory holds true.  I would suspect only in limited situations since
solder paste brick usually covers the whole pad.  That means solder
would already be touching the palladium when it melts and wouldn't need
to wet out except in a solderability experiment.

>-----Original Message-----
>From:  Larry Tawyea [SMTP:[log in to unmask]]
>Sent:  Wednesday, December 08, 1999 7:55 AM
>To:    [log in to unmask]
>Subject:       Re: [TN] Ni/Pd/Au
>
>In a message dated 12/7/99 8:47:32 PM Central Standard Time, [log in to unmask]
>writes:
>
><< At Shipley Ronal we believe that this surface finish is very capable and
>will
> give you all you need. >>
>
>George,
>
>Just a simple question,  if the Pd dissolves into the solder with the gold
>and you are in effect soldering to the Ni, what function does the gold serve?
>
>Larry Tawyea
>
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