On  7 Sep 99 at 20:59, [log in to unmask] wrote:

> In a message dated 9/7/99 7:08:40 PM Central Daylight Time,
> [log in to unmask] writes:
>
> > I would not consider only ICs. I heard about possibe damages on
> >  crystals (especially if some harmonics from the ultrasound hit the
> >  quartz frequency) and ceramic chip capacitors (they cracked).
> >
> >  ... can of worms .....
> >  just my 2 cents
> >  Regards
> >  Matthias Mansfeld
> >
> Hello Matthias!
>
> Just curious, were those problems that you spoke of with a fixed frequency?

Hello, Steve,

yes, I assume @ good old 25 kHz. I must correct one
thing: I wrote about ceramic chip caps - I had a deep search in my
German mailing list archieves and it was a tantal cap size A from a
specific manufacturer which broke exactly at the bend of the "legs".

And I heard of problems with crystals and quartz oscillators on a
PCMCIA card. The housing was closed by ultrasound welding and,
depending on the exact position on the board, the parts were damaged
or not. Later examinations found that resonance on the PWB happened
and the places where the parts died had the maximum amplitude.

[...]

Regards
Matthias Mansfeld
-----------------------------------------------
Matthias Mansfeld Elektronik
* Printed Circuit Board Design and Assembly
Am Langhoelzl 11, D-85540 Haar, GERMANY
Phone: +49-89-4620 0937, Fax: +49-89-4620 0938
E-Mail: [log in to unmask]
Internet: http://www.mansfeld-elektronik.de

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