Hi Nigel - So I would recommend getting a copy of George Harman's
"Wirebonding in Microelectronics", ISBN 0-930815-25-4. It is a great
reference for the basics of wirebonding and has the baseline information
you are looking for.

Dave Hillman
Collins Aerospace

On Thu, Dec 19, 2019 at 2:46 AM Nigel Burtt <[log in to unmask]> wrote:

> Thanks Dave and Joyce
>
> So my take-away from this advice is that Al wire-Au pad wedge bond is
> certainly not a definite No-No, but:
>
> (a) the finish must use gold of the right purity and hardness
> (b) the nickel coverage of the copper must be very good
> (c) the surface roughness of the pads must be controlled
>
> As to whether the reliability of this is at least as good as Al wire-ENIG
> pad, I guess some aging and testing would be needed?
>