electroless nickel for low rf attenuation?

I am interested in coating some aluminum parts for an RF (~100 MHz)
application. Is electroless nickel boron the best choice for high
electrical conductivity, over electroless nickel phosphorus? I am
interested in minimizing the RF attenuation. What level of boron is best?
Are there vendors who have expertise in electroless nickel boron? It does
not seem to be as common as electroless nickel phosphorus. Why? Any
information would be helpful.
Cheers,
Grant
My 11/15/2003 posting to sci.chem.coatings, sci.materials,
sci.physics.electromag:
What is the bulk electrical conductivity of a typical electroless nickel
deposit as a function of phosphorus content? Specifically:
1. Conductivity over the range 1% to 12.5% phosphorus by weight? For
example, is there a significant difference in conductivity between low-,
mid- and high-phosphorus deposits? Particularly, for 11-12.5% phosphorus
(high-phosphorus), is the conductivity higher or lower than for lower
phosphorus content?
2. DC (low frequency) and RF (up to 100 MHz)? Is there a significant
component to the resistivity attributed to the magnetic response of low- and
mid-phosphorus deposits? What is the best type of electroless nickel for
rf/microwave applications?
3. Does low temperature annealing (~135 deg. C) have any effect on the
electrical conductivity?
Grant