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Letter 7027
Plating on Aluminum?
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I am interested in wet (immersion) process that will allow
deposition of thin (about one micron each) nickel and gold films on
aluminum die individually. Zincating is the process that I have heard
of, but how mature is this process? Is controlled cleaning/etching of
aluminum a problem even if the aluminum is of high purity (sputtered)
This process if matured enough can be used at flip chip
attachment.
Thanks
adarsh kumar
Microelectronics Research Lab - Columbia, Maryland, USA
Jan. +
Zincating is a very mature process, for large parts. Thousands of
miles of aluminum bus bar has been zincated then copper plated.
Hundreds of thousands (maybe millions) of aluminum automobile and
truck bumpers have been zincated then copper-nickel-chrome plated.
Tens of millions of die castings and electronic parts have been
zincated then plated.
Whether the process is suitable for your needs, though, I wouldn't
know. You might want to search for some of the papers on zincating by
David Lashmore, such as:
- "Immersion Deposit Pretreatments for Electroplating on
Aluminium - Literature Review", Plating & Surface Finishing,
Apr. 78.
- "Progress in Plating onto Aluminium", Plating & Surface
Finishing, Jan 80.
- " Plating on Aluminium - A Review", Plating & Surface
Finishing, June 85.
because his studies tended to look at the zincate film from a
material science point of view whereas many of the other papers talk
about more practical production-oriented issues in zincating.
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Ted Mooney, P.E.
finishing.com
Brick, New Jersey
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The use of zincate is well established as an adhesion layer for
Al. Developed a process for plating Ni and Au on very thin films of
Al on power devicesusing zincate as an activation layer. It was a
technology used to fabricate flip chips
RP Daniel
Microplex - Placentia, CA
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