Re: electroless nickel for low rf attenuation?

Grant Kiehne wrote:
> 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?

If you want low skin effect loss, you don't want nickel of any sort. 
Gold, silver, and copper are the best things, with everything else a 
distant also-ran.  Inside a cavity, electroless copper lasts a long 
time.  It also tends to get smoother very rapidly as it gets thicker, 
which is also important for low RF attenuation at high frequencies.

Cheers,

Phil Hobbs