Hello again, Phil,

We have the same problem as you. I'm evaluating 37 to 150um aluminium
wedge bonding on FR-4 (and a lot of other materials) just now. As far as
I can see you have two alternativs: Cu/Ni/Au or Cu/Ni/Pd/Au. In the
former case you need thick gold, because too thin gold on nickel will
make the wedge to try bonding directly on nickel, which is less good
(nickel is too hard). In the later case there is a palladium layer
between the hard nickel and the gold, then you need only gold flash.

If you need info about the board, you may call ViaSystems UK. They make
good boards for your purpose, I think. Mail to
[log in to unmask]

Delvotec/Germany make good machines. We are buying a new one just now
for an automatic line. Call Josef Sedlmair ++49 89 62 995 125. He can
answer most of your questions. You are welcome to tell how it works
later. Maybe we can change experiences.             Good Luck

                                Ingemar Hernefjord
                              Ericsson Microwave Systems




> I just found out that I can replace a $120 LTCC substrate with a $1.95
> microvia PCB.  Trouble is the PCB comes with nickel/flash gold so
cannot be
> wire bonded using our gold ball bonding equipment.  Evidently it can
be
> bonded using ultrasonic aluminum wedge.  This MCM has over 700 wires
in a
> 1.5"x1.5" area (one of the ASIC's has 220 wires itself)- military
> application.
>
> Does anyone have experience with al. wedge on such boards?
Construction is
> 175C Tg FR4 core with 3 layers of photovia on top (photoimageable
epoxy
> plated up with copper).  Will it work?  Who makes the best bonder?
>
> Phil Hersey, Hytek Microsystems
>
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