In a message dated 09/07/1999 3:23:11 PM Central Daylight Time,
[log in to unmask] writes:
<< Hi
Is ultrasonic cleaning of an assembled PCB considered harmful to components
(IC).
Martin >>
Hi Martin!
I've read the other responses about ultrasonic cleaning of assemblies, and
basically, that's what I've always understood...ultrasonics set-up harmonics
inside the IC's and can damage the wirebonds if the wafer or wire isn't very
secure (maybe encapsulation voids or something?)
But me thinks that damage has to do with the standard industrial ultrasonic
cleaners of the past. These usually have been fixed frequency (20KHz to
1000KHz), mega watt beasts that'll blast the rust offa piece of
steel!...'cept for the ones that your honey-bunch cleans her wedding ring
in...hehehe
I think I'm starting to see some light though, I mean with all the
chemistries out there, and what do ya' do with the waste, yada, yada,
yada...me thinks there must be a better way.
If you go to: http://www.neysonics.com you can see that these guys have been
looking at this stuff, and from my feeble mind it looks like they know what
they're talking about. They have equipment using what they call
"sweep-frequencies" which eliminates the standing waves and harmonics typical
in most ultrasonic tanks. Here's a paste from their WEB page:
MultiSONIK
CAE Ultrasonics introduces the MultiSONIK™ Multiple Frequency Ultrasonic
Generator. Representing a major breakthrough in ultrasonic cleaning
technology, the MultiSONIK™ is an advanced digital ultrasonic generator that
provides the ability to select single or multiple frequencies for a single
process tank. Featuring CAE Ultrasonics’ patented dual sweep technology, the
MultiSONIK™ can operate at 40, 72, 104 or 170kHz frequencies according to a
pre-determined sequence, or it can be programmed to alternate randomly
between frequencies. With a multi-frequency generator driving CAE
Ultrasonics’ unique universal transducer, cleaning performance is optimized
to a level not previously achievable with conventional ultrasonic cleaning.
This new, advanced technology revolutionizes sub-micron particle removal in
the critical cleaning of microelectronics, flat panels displays, disk drive
components and assemblies, semiconductors, optics and more. The new
MultiSONIK™ technology permits the exposure of components to a selectable or
continually changing array of application-specific ultrasonic cleaning
frequencies from just one generator to optimize your precision cleaning.
I'm gonna be looking into this pretty intensely...seems like the way to go to
me...
-Steve Gregory-
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