FCDEV3B update

[Mychaela Falconia]

Hello everyone,

I've got another update on the FCDEV3B front.  The people from pcbcart
finally got back to me with the price quotes for making our boards
with either selective OSP/ENIG finish or ENIG throughout as discussed
before, and the price is about the same either way, between $2400 and
$2500 USD.  This price is definitely affordable, i.e., the funds from
the generous 2016-12-23 donation are sufficient to cover it, thus I
can pay for the order and get the ball rolling as soon as I decide
between the two surface finish choices.

The one issue with using ENIG finish throughout is that the solder
joints are made with nickel rather than with copper, and the current
flowing through these joints has to pass through the nickel layer in
between the copper below and the SnPb above.  The nickel-phosphorus
layer that forms in the ENIG process has a lower conductivity (higher
resistivity) than copper or SnPb, and it is often stated that the
resulting higher resistance is bad for high frequency signals, which
may be an issue for our 1 GHz and 2 GHz RF.  Hence I will need to seek
some more expert advice before I make the final decision.

M~