Issues I read of was the surface roughness of the copper, and the thickness
of the deposit.
Are these maybe factors to be checked and improved by the circuit suppliers?
Gaby
----- Original Message -----
From: "R Sedlak" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, January 28, 2008 7:51 PM
Subject: Re: [TN] Microvoids immersion silver
> Gaby: Perhaps the ideal process to minimize/eliminate microvoids is one
> that is almost unknown. One of the more common issues in this process
> can be marginal developing of soldermask, which leaves residues on pads.
> Other than the obvious move, of keeping the developer in good condition
> (not necessarily so easy, soldermask developers are very difficult to
> clean out properly), the other insurance operation that can be done is to
> put an alkaline cleaner before the microetch which precedes the silver
> bath.
>
> This last suggestion should generate howls of protest, as everyone thinks
> that alkaliine cleaners strip soldermask... to which I can reply, not ALL
> of them do that. There are alkaline cleaners specifically designed to
> clean Copper, and leave soldermask unaffected.
>
> Good luck,
> Rudy Sedlak
> RD Chemical Company
>
> Gabriela Bogdan <[log in to unmask]> wrote: Dear Netters,
> Is there a preferred process for immersion silver finish in order to
> minimize microvoids?
> How do you choose the preferred immersion silver PCB supplier?
> Which test for bare boards could give the best information?
> Should I perform a print and reflow test for each batch, followed by
> x-ray?
> Which tests are the suppliers performing?
> Thanks,
> Gaby
>
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