Hi Edwin, see J-STD-001B (has been issued in October 1996), § D-5.1,
Sample Size: "A minimum of 10 vehicles shall be tested for each
material/process combination. This sample size was calculated by setting a
consumer risk at 10% (confidence of 90%). A complete explanation of how this
sample size was determined can be found in IPC-TR-467. It is recommended
that additional unprocessed vehicles be tested as controls."
        okydky, so weit - so gut:
*       for definition of consumer risk ask your QA guy (the propability to
miss a failure is 10%).
*       IPC-TR-467, §5.1:  it seems the sample size was so determined in
view of intermittend decreasing of the SIR because Electrochemical
Migration: §5.1 (or does have other technos other ideas?)
*       Initial pretest preparation: because during test configuration you
have to catch the process-influence (fluxer/solder resist/cleaning process)
on the Contamination/SIR. This means you have to exclude other influences
(fingerprints, initial contamination of the pcb surface..). For this purpose
I would suggest you should clean the samples before the "main-test
preparation" according IPC-TM-650, No. 2.6.3, §5.2.5 ... 5.2.10 or
IPC-TM-650, No. 2.6.3.3, §5.2.
Bernhard


> Date:    Tue, 30 Nov 1999 08:57:25 -0500
> From:    "Louis, Edwin @ CSE" <[log in to unmask]>
> Subject: Information Needed
>
> Does anyone have the telephone number for Contamination Studies
> Laboratories
> or that of Doug Pauls. 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?
>

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