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Reply To: | TechNet E-Mail Forum. |
Date: | Thu, 12 Feb 2004 18:15:00 EST |
Content-Type: | text/plain |
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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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