Hi Nigel - the testing we conducted on the gold wirebonding of ENIG
finishes was not successful. My recommendation would be to go to an ENEPIG
finish if you wanted to use gold wire instead of aluminum. We have had very
good success with the ENEPIG finish (IPC-4556) for wirebonding.

Dave Hillman
Collins Aerospace
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On Wed, Dec 18, 2019 at 11:03 AM Nigel Burtt <[log in to unmask]> wrote:

> Semi-hypothetical question.
>
> Aluminium wire wedge bonding to PCB ENIG pads that meet IPC-A-600
> requirements is normal and OK, but if I also wanted to bond the same Al
> wires to PCB "soft gold" bondable pads (2um electrolytic gold over 2.5um
> Ni) on another similar PCB with suitable adjustment of the wedge bonder
> process parameters as necessary that gave me acceptable and comparable pull
> test strength results, what would be the likely long-term reliability of
> such an interface?
>
> Is this a simple No-No?
>
> Many thanks
>
> Nigel
>