SMTA International Conference Proceedings

Acceptance Testing Of Pb-Free Bar Solder Alloys

Authors: Elizabeth Elias Benedetto, Aileen Allen, Kris Troxel, Jian Miremadi
Company: Hewlett-Packard Company
Date Published: 10/13/2013   Conference: SMTA International

Abstract: Since the implementation of EU RoHS in 2006, the electronics industry has seen an expansion of available Pbfree1 alloys for wave soldering, miniwave rework, BGA and CSP solder balls, and, more recently, solder pastes for mass reflow. The risks associated with these alternate, low-silver (within the range of 0 to less than 3% silver), solder alloys, such as higher pot temperature, laminate damage, reduction in product life, copper dissolution and reduced thermal process windows may present manufacturing challenges and possible field reliability risks for OEMs. In order to take advantage of potential cost reduction opportunities afforded by these new alloys while mitigating manufacturing and reliability risks, HP had previously defined test protocols [1- 3] that could be used for assessing new Sn-Ag-Cu, Sn-Ag, and Sn-Cu alloys for general use in electronics.

For the past two years, HP has been analyzing data produced using the protocol for bar alloys. Some low-silver bar alloys, used in wave and miniwave soldering, have been found to be generally acceptable for PCBs up to 93 mil thickness in HP products.

This paper reviews the work completed thus far on these bar solder alloys, including wetting behavior, through-hole solder joint strength, barrel fill, and copper dissolution. The authors also report the changes that have been made to the test protocol.

This assessment approach only establishes the tests and data reporting requirements, not the acceptance criteria for alloys; pass/fail criteria may vary by industry segment, by company, and by product characteristics. The underlying data needed to evaluate new alloys, however, are likely to be similar in most cases. Thus, the assessment method provided in this paper is believed to be relevant across the entire electronics industry.

Key Words: 

Pb-free, bar solder alloy, acceptance testing, pin wetted length, copper dissolution, low-silver

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