Reliability assessment of immersion silver finished circuit board assemblies using clay tests

This paper discusses issues regarding the reliability of immersion silver (ImAg) surface finish on printed circuit boards (PCBs) in high-sulfur environments with a focus on creep corrosion. The test approach used clay with sulfur to drive corrosion. It was found that silver sulfide had formed on the...

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Bibliographic Details
Published in2009 8th International Conference on Reliability, Maintainability and Safety pp. 1212 - 1216
Main Authors Yilin Zhou, Pecht, M.
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.07.2009
Subjects
Assembly
Circuit testing
Copper
Corrosion
Creep
creep corrosion
Galvanizing
immersion silver
Printed circuits
Silver
sulfur
Surface finishing
Weibull distribution
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Summary:This paper discusses issues regarding the reliability of immersion silver (ImAg) surface finish on printed circuit boards (PCBs) in high-sulfur environments with a focus on creep corrosion. The test approach used clay with sulfur to drive corrosion. It was found that silver sulfide had formed on the ImAg surfaces, but dendrite-shaped creep corrosion products were formed on the edges of the ImAg finished copper traces by galvanic corrosion. The creep distance and the content of CuS and Ag 2 S in the corrosion products were dependent on the relative location of the pad edges and the solder mask, which caused different extents of coverage of ImAg finish on the copper traces. A Weibull distribution with two parameters was used to analyze the length of the creep corrosion products, the values of which were used along with corrosion probability to assess the corrosion resistance of ImAg finished PCBs.
ISBN:1424449030
9781424449033
DOI:10.1109/ICRMS.2009.5270038