Rick Vernon wrote:
>
> Does anyone have experience with damage to surface mount crystals
> due to mounting or handling issues in processing PWAs?
>
> We see a failure mode where the crystal fails to oscillate due to
> mechanical shock or damage (according to FA from crystal mfg).
> Failures are detected at ICT. Some have made it to ESS and failed there.
>
> Thoughts and experiences appreciated.

Get confirmation from the crystal mfr that it is indeed
a *damaged* crystal.  They're usually more than willing
to confirm this.  If it's NOT crystal damage, then you
may have another problem.

You might have to be extremely diplomatic with this one,
but ask the designer/customer "out of curiousity" if the
crystal is supposed to be a "parallel" or "series" type.

I'm not a board maker, but I had a hell of a time solving
a problem once with a board that was supposedly suffering
from "crystal damage".  Our purchasing people were all over
the mfr about it.

Turned out the designer specified the wrong type of crystal.
The particular circuit required the crystal to be a "series"
type crystal.  What was being used incorrectly was a "parallel"
type crystal.  Sometimes they'd work.  Sometimes they wouldn't.

All I remember was carbon based waste products hitting the
proverbial fan in the design department once this was confirmed.

Happened long ago and details are a little fuzzy.

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################