Dave - I am assuming that the board has other components that require
soldering as well as the wire bond sites. If that is so then the board fab
house has probably run a second image process where a dry film was used to
protect the 80 micro inches of gold. I believe they would run the 80 micro
inches first as the possibility of dry film breakdown for an 80 micro inch
plating dwell time is a possibility that they would want to minimize.  The
bonds you are picking up can be found in the adhesion promoters for dry
film. Question to ask is "did they apply dry film post gold application"? A
quick rinse in a caustic solution followed by a good rinse dry will remove
the contaminants if from the dry film.


Gerard


-----Original Message-----
From: David D. Hillman [mailto:[log in to unmask]]
Sent: Wednesday, August 11, 2004 3:01 PM
To: [log in to unmask]
Subject: [TN] Hard Gold Plating/Contaminate Question

Hi TechNet! Hey, looking for some help (Rudy, Frank, Gerard, plating
folks). Background:  I have a test board which with approximately 80
uinches of wirebondable hard gold plating that is having gold wirebond
process problems. An XPS (xray photoelectron spectroscopy) analysis of a
"good" versus "bad" test board revealed that the "bad" has significant
organic surface contamination for carbon and oxygen in the form of a
hydrocarbon (lots of C-C and C-H bonds). Now the question: can/will a
hydrocarbon species be codeposited into the gold plating thickness? I
understand the surface process/issues but the codeposit question came up.

Dave Hillman
Rockwell Collins
[log in to unmask]

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