My prod floor used to HALT specific models (scrap) without warning, to
confirm process. Repeating material/process related quality, off the line
occasionally, makes sense.

Doing full/combined  test on fewer numbers is more effective.

RL

----- Original Message -----
From: Eric Christison <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, February 21, 2002 8:10 AM
Subject: [TN] Environmental Testing - parallel vs. sequential


> Fellow Technetters,
>
> I'm in the middle of a 'frank and forthright' discussion at the moment on
whether it is possible to justify substituting a set of environmental
> tests carried out in parallel on a device i.e.. 10 devices go through
vibration, another 10 go through high temp operating etc... for a customer
> requirement for sequential testing i.e. take 10 devices and put them
through all the tests.
>
> I'm of the opinion that even if you up the severity of each parallel test
it still isn't the same as a sequential test because you won't catch the
> failure mechanisms that results from a combination of effects e.g.. high
humidity weakening an adhesive joint which then fails the shock test. You
> wouldn't see a failure if you tested 10 devices for high humidity and
another 10 for shock.
>
> I'd be interested in some opinions or some literature references which
discuss this issue.
>
> Regards,
>
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