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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