Dave Hillman's reply is right on the money regarding the technical aspects
underlying your questions. I would like to amplify on his answer, since the
original questions imply the need for some more fundamental explanation. 
Q: "Could anyone tell me is there any way to reduce the gold leaching from a
gold 
plated board. "
A: Gold in contact with liquid tin/lead solder will rapidly go into solution
with tin; therefore, there is no practical solution to prevent this
'leaching'. Dave Hillman writes: "make sure that you have enough solder
volume to allow the gold to dissolve evenly into the joint AND that your
process is such that the time and temperature profile allows this dissolution
to take place"--If there is not enough solder volume for the gold volume
present, the gold concentration, even at uniform dispersal, can be high
enough to cause gold embrittlement AND even if there is enough solder volume,
inadequate time and temperature profiles do not allow for uniform dispersal
of the gold throughout the solder volume and therefore might lead to locally
high enough Au concentrations to cause gold embrittlement.  
Q: "I have heard that hot air reflow will have more gold-leaching as compared
to 
Infrared reflow."
A: If proper reflow profiles are run, the reflow oven will not make any
difference.

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-mail: [log in to unmask] 

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