Here is my two cents worth on the topic of Electroless Ni , Phosphorous
content.
Here at Shipley our recommendation for thickness of Electroless Ni is 100 to
250 uins or 2.5 to 6.0 microns.  For the gold thickness we recommend 2 - 4
uins (0.05 - 0.10 microns) as the best thickness to protect the Ni during
storage and not to create any Ni defects during processing.
As far as Phosphorous content in the Ni deposit we are presently staying with
7 -9% P.  We have seen data, where High phos (10 - 12%) and Low phos (5 -7%)
gave equally good results, with regards to incidences of "Black Pad".
Our tests indicate that High Phos is prone to skip plating and gold adhesion
failure.
The IPC Plating Subcommittee 4-14 will be meeting in Miami, during IPC Works
2000, at 1:30 to 3:00pm on September the 11th, 2000.  The agenda of the
meeting is to define an IPC-Standard for Electroless Nickel and Immersion
Gold as well as Electroless Gold, as surface finishes widely used in the
industry today. Anyone interested in participating is welcome to join the
meeting or send his input to me, and I will keep him or her informed of the
committee progress.
George Milad
Tech Marketing Mgr.
Shipley Ronal Inc
Chairman IPC Subcommittee 4 -14

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