At risk of boring the regulars on Technet.....you need to understand the
difference between electroless and immersion plating.
All plating involved transfer of electrons to the metal ions in solution to
turn them from ions to metal.
In electroplating, these electrons come from the rectifier...via heavy wired
connections....but, you have not wired connections to some of the connectors,
so you cannot use electroplating...so you have a choice of electroless or
immersion plating.
In electroless plating, the electrons come from other chemicals in solution,
and can cause plating in places where you do not want it to occur, like on
tank walls, or on parts of the board you do not want plating to
occur....further, the reacted chemicals build up in solution, and affect
plating....altogether electroless plating can be a nightmare.....
Whereas in IMMERSION plating, the electrons are donated from the substrate
metal going into solution, thus immersion plating tend to be substrate
specific, i.e. the immersion Tin will plate ONLY on Copper.
Also, immersion plating is self limiting...when all the substrate is covered,
the plating stops, thus all immersion plating deposits are REAL thin....Tin
is the thickest I have ever heard of at 40 microinches (one micron),
Immersion Gold never gets over 10 microinches (0.25 micron). Whereas
electroless plating can build to any thickness you want, how long do you want
to leave it in the tank.
Any immersion plating system is infinitely easier to run than any electroless
system. Big windows, ease of maintenance, etc.
So, immersion Silver and Tin are always going to be easy and fun compared to
any plating that starts with the descriptor "Electroless".
Hope this helps.
Rudy Sedlak
RD Chemical Company
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