Hi Rudy,
Of course there is exposed copper and nickel ( the board was made using gold
as etch resists, so there is exposed copper and nickel on sidewalls of
conductors), by why Silver, less noble and lower in electroafinity list than
Gold, is plating on Gold surfaces? Believe me, adhesion is very good.Tested
per IPC method using 3M standard tape for adhesion tests.
I made this test just to decide how to process PCB with gold plated fingers
in immersion Silver finishing.So the answer is : gold plated areas have to
be masked . But still - I was suprised.
And you know - in Holyland Sunday is like Monday...
Edward
Edward Szpruch
Eltek Ltd
P.O.Box 159 ; 49101 Petah Tikva Israel
Tel ++972 3 9395050 , Fax ++972 3 9309581
e-mail [log in to unmask]
> -----Original Message-----
> From: Rudy Sedlak [SMTP:[log in to unmask]]
> Sent: א מרץ 14 2004 15:23
> To: [log in to unmask]
> Subject: [TN] Immersion Silver on Gold
>
> Edward:
>
> It is far too early to be up on Sunday morning, but being awake, I will
> answer your question, even though it was directed at Bev.
>
> If the Gold plating is in electrical contact with any surface which will
> plate the Silver, such as Copper, or perhaps Nickle, and both surfaces are
> in the
> Silver plating solution, the Silver will plate everywhere... In immersion
> plating, the plating is caused by dissolution of the substrate metal,
> usually
> Copper in our industry, but the dissolved metal does not have to come from
> where
> the plated metal is actually deposited.
>
> I hope I have made this clear.
>
> Rudy Sedlak
> RD Chemical Company
>
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