George Harmon has a brief section on bonding Al to Ni in his Wire
Bonding in Microelectronics (sorta the bible of wire bonding).  He
states that the main difficulty in this system is the bondability of
the system, and not its reliability (which is pretty good).  I have
no experience bonding to this metallurgical system, but you may
want to check out this reference.

Brett Goldstein
Mechanical engineer
EVI, Inc.


> Hi,
> A certain vendor claims that thermosonic Al to Ni wirebonding is possible. I am
> looking for references to refute or support this claim. The precise claim is
> that on a flexible PCB constructed of:
> Kapton:    25 um
> Cu:        7-8 um
> Ni:        1.0 um
> Au:        0.2 um
> that thermosonic wire bonding with Al wire results in a wire bond to the Ni
> layer. This claim was made after being confronted with the IPC recommendation
> that at least 1 um of Au is required.
> If anyone could share his/her experience(s) on this subject, or, better yet,
> point me toward some authoritative reference(s), I would greatly appreciate it.
> TIA,
> Rusty
>
>
>
>
>
> Rusty Boyd
> OUHEP - http://oua4.nhn.ou.edu/
> [log in to unmask]
> office: (405)325-2890 x36316
> office fax: (405)325-7557
> home ph., fax and data: (405)447-5211
> University of Oklahoma
> Dept. of Physics and Astronomy
> 440 W. Brooks
> Norman, OK 73019
>
>

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