Symposium Conference Proceedings

Discussion on Cu Dissolution in Pb-Free PTH Rework

Authors: Chuan Xia, May Yan, Scott Priore, and Kangeyan K.Ramachandran
Company: Cisco Systems Ltd.
Date Published: 4/18/2012   Conference: Symposium

Abstract: Rework process of Pb-free PTH connectors using conventional solder fountain equipment presents a number of new challenges and issues. Major concern will be the Cu dissolution of the soldered terminal of the copper barrel, due to the requirement of higher temperature used for Pbfree soldering. Higher pin counts connectors and board thickness will pose a great challenge during Pb-Free PTH rework. Excessive Cu dissolution can potentially cause quality & reliability issues. Currently there is no industry specification for remaining Cu plating thickness at post rework. Minimum 10 microns Cu thickness at the bottom knee will be required as experienced spec. to ensure the reliable Pb-free PTH solder joints.

This paper focuses on the PTH rework parameter research, which is considered to have significant impact to the cu dissolution rate. Standard test vehicle and selected PTH components were used in this study. DOE was designed to give a clear illustration on this impact. This paper describes base information of test vehicle & components, the wave soldering process, cross section, DOE study and data analysis, and the final conclusion on the study.

Key Words: 

Cu dissolution, PTH, Mini-Pot, DOE

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