Eric,
You might be interested in this reference for behaviour of BGA solder joints
at high temperature under low frequency vibration.
http://www.packaging.buffalo.edu/paper4.pdf

Regards
John
-----Original Message-----
From: Eric Christison [mailto:[log in to unmask]]
Sent: 21 February 2002 13:11
To: [log in to unmask]
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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