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January 1999

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Subject:
From:
Tegehall Per-Erik <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 26 Jan 1999 08:54:49 +0100
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Excuse the late response but here is my opinion on the tests you
mentioned. The halide content determination, copper mirror test,
electromigration, silver chromate paper test, etc., are useful when
developing a new flux. If a flux do not passes the test, there is a big
risk for that it may cause reliability problems of an assembly. However,
passing the tests is no guarantee for that there will be no reliability
problems. That is the reason for that SIR testing is performed. It is
the only test that could be characterised as a reliability test.

Since the SIR on a PBA will be affected by practically all materials and
processes used for the production, evaluating the impact on SIR of a
flux on a bare test coupon with just a comb pattern, as is done during
qualification of a flux by flux manufacturers, is not enough. Instead,
SIR should be evaluated using a procedure as that described in Appendix
D (Material and Process Compatibility Testing) in IPC´s standard
J-STD-001B, i.e. using a test vehicle representing the substrate
materials, assembly materials, and fabrication processes and measuring
the SIR between solder joints to components with open circuit. If you
have done that, and passed the test, I do not see any reason for that
you should worry about the halide content.

Per-Erik Tegehall
IVF
SWEDEN

Phone: +46 31 706 61 48
Fax: +46 31 27 61 30
Email: [log in to unmask]

> ----------
> 
> Dear colleagues,
> 
> We would like to rationalise our PBA materials (solder pastes, flux)
> qualification procedures. Our question is:
> What is the added value of tests/measurements like halide content
> determination,
> copper mirror test, electromigration, silver chromate paper test,
> etc.,
> when one does a Surface Insulation Resistance (SIR) test? What do they
> tell more about the final product reliability? Does the SIR test not
> cover it all? For example, should we be worried about the halide
> content when the material passes the SIR test?
> 
> We welcome any comment.
> 
> Geert Willems
> Alcatel Bell
> 
> 

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