Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Problems with a plating spec
We ordered from a supplier a lead frame that is going to be processed as a chip carrier and then wire bonded. The plating SPEC we created is:
"Plate a 510 Phosphor Bronze stamped coil with 50 micro inches of ductile nickel sulfamate over copper flash per ASTM 734, and then add
50 micro inches of soft gold, class 1, grade A, per ASTM B488."
Because the supplier does not have the possibility to do the copper flash we decided to remove the copper flash from the SPEC.
Questions: What impact will have the removing of the copper flash over the wire bonding step, if any? How important is the copper flash in this plating process?
Buyer - Maple Grove, MN, US
September 4, 2008
If the "lead" frame is Kovar, and not fired into ceramic,then an old fashion simple nickel chloride strike will be far better than a copper flash. You do not want copper around heat because it walks
(migrates) thru just about everything.
If the Kovar is "fired", then get back to us for a more aggressive activation suggestion.
If that frame is "lead" (Pb) the metal, then strike first in a fluoborate nickel electrolyte as the metal "lead" is insoluble in chlorides, sulphates, and sulfamates.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
September 8, 2008
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