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Thu, 14 Aug 1997 08:09:15 -0700 |
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Hi Jan and Stella,
It's me again, The Gold over bare copper is a real no! no!, since gold
diffuses very rapidly in copper (even at room temperature), this again creates
a gold/copper intermetallic which may be worse than the tin/copper ( I'm not
sure about the degree. Almost everyone plating gold uses a Nickel barrier plate
of about 200 microinches over copper before plating Gold.
I hope this is also of some help.
Les Connally
[log in to unmask]
> From: [log in to unmask], on 8/14/97 10:49 AM:
> > I'm no soldering expert, but I Know a little bit. The general problem
> > with mutiple thermal cycles is this: The tin forms a Tin/Copper >
> intermetallic with the Copper upon reflow.
>
> Les,
> "The board laminate is special nylon material and has gold over the bare
> copper pads." I'm neither a soldering expert but something got me
> thinking, Stella had gold over bare copper.
> Cu and Sn/Pb intermetallics are no good, the intermetallic is bronze (i
> think) and it's "almost" no-way you can solder on that. But that wasn't
> the issue here. As i wrote earlier, i'm no expert but anyway, does
> anyone know what kind of intermetallics you get from multiple thermal
> cycles with gold on bare copper??!
>
> Thank you,
> Jan Merstrand
>
>
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