Understanding Surface Insulation Resistance
This paper covers differences between two common surface insulation resistance (SIR) specifications J-STD-004A and J-STD-004B.
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Authored By:
Chris Nash, Technical Support Engineer
Eric Bastow, Senior Technical Support Engineer
Indium Corporation
Summary
Many electronics manufacturers perform SIR testing to evaluate solder materials and sometimes the results they obtain differ significantly from those stated by the solder material provider. The difference in the results is typically the result of SIR coupon preparation. This paper will discuss the issue of SIR
coupon preparation, board cleaning techniques, and how board cleanliness directly affects SIR results.
We will also discuss the differences between two of the industry's most common SIR specifications J-STD-004A and -004 B. The subjective nature of SIR testing on water washable/soluble materials will also be reviewed. In addition, testing for SIR when the assembly process has multiple residue sources, such
as paste, wave solder flux, rework flux, etc., will be considered.
Initially Published in the IPC Proceedings
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