In a message dated 11/30/1999 8:56:26 AM US Eastern Standard Time,
[log in to unmask] writes:

> And, can anyone tell me in paragraph D-4.3.5.1 of
>  IPC-J-STD-001a, what the control samples are and what the
>  sentence,"Additionally,six control boards(three for cleanliness testing and
>  three for SIR testing) shall not be processed beyond the initial pretest
>  preparation" means. What paragraph describes pretest preparation?
>  What is the pretest preparation process?
>

The control samples alluded to are unprocessed controls.  The intent is to
benchmark the starting condition of the test samples, before exposure to your
manufacturing process.  There is no paragraph that explains the pre-test
preparation.  None is outlined.  If you use the B-36 boards right out of the
package, as delivered to you from the fabricator, then set six aside for
controls.  This ASSUMES that the boards come to you clean enough.  Others
prefer to run the B-36 boards through the Omegameter (or similar) as a
precleaning treatment.  I have heard of others using cyclohexane.  Whatever
precleaning is used, set aside six samples after precleaning.  These are your
controls.  The use of the controls allows you to show a Before and After for
the candidate process.

The Ever Elusive Doug Pauls
CSL

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