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February 2004

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Subject:
From:
Rudy Sedlak <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 12 Feb 2004 18:15:00 EST
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Nickle is normally used between Gold and Copper to prevent the Gold from
spontaneously alloying with the Copper, and disappearing after a time.

You are apparently currently using ENIG...Electroless Nickle, with immersion
Gold...typically the Gold is less than 0.25 micron thick.

When the folks in the UK used to have a standard set by their telecom people
which allowed, or even specified (!!!!) Gold over Copper, the Gold needed to
be 1 micron + thick, to delay this alloying process.

ENIG, properly done, has nearly an infinite shelf life before it must be
soldered.  Gold over Copper will have a finite shelf life, dependent on Gold
thickness.

Does this help?

Rudy Sedlak
RD Chemical Company

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