Skipping phosphorous baths?  Since the problem seems to be that phosphor is
not solderable, eliminating the ability of a phosphor layer to build up
during a hyperactive IG corrosion attack might just work.  Perhaps a
"Technetter" can expound on how to plate up nickel without the phosphorous.
        There are several studies collaborating with each other that low
phosphorous levels in the nickel bath result in poor solderability and high
levels result in good solderability.

Thanks

Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]


> -----Original Message-----
> From: Ingemar Hernefjord (EMW) [SMTP:[log in to unmask]]
> Sent: Tuesday, September 12, 2000 8:37 AM
> To:   [log in to unmask]
> Subject:      [TN] BGA soldering and ENIG Phosphorous
>
> Got answers from Gerry, Stephan, Robert, Ryan and possibly some other,
> again thanks a lot. But Steph, you made me confused, you said higher P
> will eliminate aggressive mask attach from IG and reduce risk for building
> up fragile P-enrichet layers between Ni/Sn intermetal and Ni.  This is
> opposite to what some other of you told me, namely that you should avoid
> high P% baths.  So, what do we prefer: little Phosphorous or much
> Phosphorous. Please, don't say 'moderate'.
> Or is it more a question of what IG we use (Biunno's article about
> 'hyperactive IG corrosion on Nickel)?
>
> I can tell you the more simple solution if there is a problem: a company I
> know just skipped phosphorous baths, and there were no more BGA soldering
> problems.  What do you think?
>
> Ingemar
> Ericsson Microwave Systems
>
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