[hpsdr] Suitable solder for Atlas

[Steven B. Dick]

 " I mentioned the gold plating on the PCB to a work colleague who is
involved in designing and building specialized engine control modules for
rally & racing cars, and he cautioned me around the concern of gold
embrittlement and the need to be careful using SN bearing solders on gold
plated PCBs and contacts".

I haven't built any HPSDR cards but it sounds like this board may be using
what is called "ENIG" or Electroless Nickel Immersion Gold."  This is one of
several industry standard processes.  Electroless nickel immersion gold
chemistries offer many strengths including excellent wettability,
coplanarity, surface oxidation and long shelf-life. It also provides both
good adhesion as well as providing outstanding electrical testability. The
gold layer is extremely thin and somewhat porous. It protects the underlying
nickel from oxidation.   The ENIG finish has historically been the best fine
pitch (flat) surface and lead-free option world-wide. The typical Nickel
thickness is 75 micro inches and 3-5 micro inches of gold. Disadvantages
include limited availability, higher cost and this being the only surface
finish that requires a two-part process. 

I would not have any concerns in this application.  I have seen one issue on
a very complex PC board with a connection failure that was caused by what's
known as "Intermetallics".  This problem was believed to be caused by some
sort of contamination introduced during the ENIG process after a failure
analysis. 

Regards, "Digital Steve", K1RF.


 1300496061.0