Joyce, 

Immersion plating reactions are driven by replacing a metal already on the surfuce with a metal in solution.  

Metal dissolved         Metal plated   Process
elecroless nickel         gold               ENIG
electroless palladium   gold              ENEPIG
copper electroplate      silver           Immersion silver
copper electropate       tin               Immersion tin

Immersion reactions inherently stop when the plated metal covers the surface of the metal being dissolved.  That means that immersion reactions cannot reach the thicknesses you ask 

That said, electroless reactions occur chemically where the metals plate on themselves and build thickness with time.  Elecroless copper, nickel, silver and gold are all known and can build thicknesses that you ask.  However, electroless reactions tend to have pretty pure metals (except electroless nickel that co-deposits phosphorus at some 4-12%).  Someone else that supplies electroless gold will have to comment about the "hardness" of that deposit.  

Electroplating can deposit essentially all the common metals and can co-deposit hardners (other metals) with gold with various properties and thicknesses. 

Denny Fritz

-----Original Message-----
From: Joyce Koo <[log in to unmask]>
To: TechNet <[log in to unmask]>
Sent: Wed, May 8, 2013 10:22 am
Subject: [TN] immersion gold


Joyce Koo
esearcher
aterials Interconnect Lab
ffice: (519) 888-7465 79945
lackBerry: (226) 220-4760
Gurus,
s there any great immersion gold process out there that can do 0.5 micron gold 
ith durability and good hardness?  (> 20 micro-inches).  I need to up date my 
nowledge... -being far from plating tank for too long.  Many thanks. 
est regards,
oyce

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