Steve,

I also agree that the Au thickness is fine for Au wire but could be a
reliability problem for Al.  I have found that cooler temps (125C, even as
low as 110C) for softer substrates (non-ceramic) usually perform more
consistently when Au ball bonding.  With Flex, getting proper clamping is
very often an issue and I would certainly examine that possibility.

Good Luck,
Bruce Misner

> ----------
> From:         Steve Kelly[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Steve Kelly
> Sent:         Saturday, June 22, 2002 11:22 AM
> To:   [log in to unmask]
> Subject:      [TN] Wire bondable gold
>
> We made some flex circuits for a customer and wound up putting too much
> gold on - approx. 75 microinches. The nickel is averaging 153. The gold
> meets all the purity specs. Under the wire bond area is a large heat sink.
> My customer is having difficulties wire bonding. Is too much gold a
> problem or can the heat sink cause issues. Regards Steve Kelly
> --------------------------
> Sent from my BlackBerry Wireless Handheld (www.BlackBerry.net)
>
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