The influence of SO2 environments on immersion silver finished PCBs by mixed flow gas testing

This study focuses on the corrosion of immersion silver (ImAg) finished copper land patterns on printed circuit boards (PCBs) due to SO 2 exposure in a mixed flow gas chamber. Six test conditions were examined with varying concentrations, temperatures, relative humidity, and exposure times. The resu...

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Bibliographic Details
Published in2009 International Conference on Electronic Packaging Technology & High Density Packaging pp. 116 - 122
Main Authors Shunong Zhang, Shrivastava, A., Osterman, M., Pecht, M., Rui Kang
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.08.2009
Subjects
Chemical products
Circuit testing
Copper
Corrosion
Electrodes
Humidity
Land surface temperature
Printed circuits
Silver
Surface finishing
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Summary:This study focuses on the corrosion of immersion silver (ImAg) finished copper land patterns on printed circuit boards (PCBs) due to SO 2 exposure in a mixed flow gas chamber. Six test conditions were examined with varying concentrations, temperatures, relative humidity, and exposure times. The results indicated that there are two mechanisms of corrosion on ImAg-finished PCBs in an SO 2 gas environment: direct chemical corrosion and electrode reaction. No evidence shows that Ag 2 S and Cu 2 S or CuS were produced. In high humidity, chemical and electrode reaction both existed, and the corrosion products could included Ag 2 O, AgCl, Ag 2 SO 3 , CuO, CuCl 2 and CuCl, In low humidity, the chemical corrosion was predominant, and the corrosion products could include Ag 2 O, CuO. Passive films were formed on ImAg finished surface under long exposure time. The temperature from 30degC to 40degC did not have an obvious influence on the ImAg-finished PCBs.
ISBN:9781424446582
1424446589
DOI:10.1109/ICEPT.2009.5270782