Rick,
Is this a totally sealed crystal? Or a tunable crystal oscillator circuit
with an access hole in the case? Do you use a wash process? Could
moisture/water be getting into the case? We had a problem where all of the
above was hurting us. We had to have the crystal osc maker put a better
label/seal over the tuning hole. We then had to buy the raw stock
label/seal material to replace the original whenever a tech had to go in
and tune the varmint.

I am not aware of pure mechanical shock damage happening in our processes.
Our boards went through smt reflow, sometimes a glue process, thru hole
stuffing, wave solder, wash in an Aquastorm, board level test, system level
test, and then a whole lot of ESS cycling.






Rick Vernon <[log in to unmask]> on 05/05/99 08:33:22 AM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Rick Vernon <[log in to unmask]>



 To:      [log in to unmask]

 cc:      (bcc: Charles Barker/US/I-O INC)



 Subject: [TN] SM Crystal damage









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.

Rick Vernon, QA Engineer
Phoenix International Corp.
Fargo, ND

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