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Subject: Re: Ultrasonic heating?
Date: Mon, 9 Dec 2002 06:12:21 +0000 (UTC)
References: <3DF40E8E.7D390328@earthlink.net> <8MUI9.459416$S8.email@example.com>
NNTP-Posting-Date: Mon, 9 Dec 2002 06:12:21 +0000 (UTC)
User-Agent: tin/1.5.14-20020926 ("Soil") (UNIX) (Linux/2.4.19 (i686))
Sir Charles W. Shults III wrote:
> A number of wire bonders used a hollow tip that fed the gold bond wire
> through itself without a flame or other source of heat, but these are not ball
> bonding machines. The tip is driven with a high powered ultrasonic source,
> making the tip (which was piezo driven) oscillate and attach the wire through
> frictional heating. This resulted in a very small, localized heating effect
> that would influence the bond only.
> Ball bonding machines also feed the wire through a hollow tip (usually) and
> have a tiny flame that melts the wire end into a bead. This molten bead is then
> bonded to the die. The flame is typically hydrogen because it was very clean
> and produced a very high temperature.
Hmm, I hadn't realised the bead was still hot while being bonded.
Makes some sense though.
> I have not heard of an ultrasonic ball bonding machine, even though I once
> serviced many devices used in the fabrication of wafers and packaged chips.
Oops, sorry, I used "ball bond" where I meant "wire bond".
However, there are thermosonic ball bonders.
http://inquisitor.i.am/ | mailto:firstname.lastname@example.org | Ian Stirling.
Money is a powerful aphrodisiac, but flowers work almost as well.
-- Robert A Heinlein.
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