Hello Everyone,

What kind of chemistry do you recommend for electrolytic Ni plate, sulfamate
or sulfate nickel, as applied on thermosonic wire-bond PCB? I was told long
time ago that sulfamate nickel is a 'low-stress' nickel being used in
various metal finishing jobs, including PCB; while the latter comes from a
Watt nickel bath. Some BGA designers says that as long as the metal surface
is clean, the two nickel types should work equally well.

I recently tried both and found that the sulfate nickel has a better
bondability, despite the fact that they come from two different vendors.

Can anyone tell me about the surface topography of each type of nickel? Do
they have different atomic packing in the plated layer? What actually does
low/high -stress mean, something related to hardness? Assuming they have the
same amount of gold plated on top, which one is more suitable for gold wire
ball bond?

Thanks in advance!

Regards, Benny.

Wire Bonder Process Eng'g
ASM Assembly Automation

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