SnAgGu micro-ball grid array (BGA) solder joint evaluation using a torsion mechanical fatigue test method

Claire Ryan, Bryan A. Rodgers, Jeff M. Punch

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Due to the hazard which lead poses to health and the environment the EU is banning its use in electrical and electronic equipment from July 2006. This ban along with the market drive to more environmentally friendly products means that tin-lead solders must be replaced with lead-free alternatives. This paper presents the results of an experimental investigation of the mechanical fatigue properties of tin-silver-copper (SnAgCu) solder joints with a baseline of tin-lead (SnPb). The test vehicle comprised of an 8-layer FR4 printed circuit board (PCB) mounted with four micro-ball grid array (BGA) components - each with a total of 100 solder balls in a 10×10 array. The solder joints were formed using surface mount reflow processes optimised for both solder types. A torsion mechanical fatigue test was employed to evaluate the solder joints - the principle of which was to stress the solder joints repetitively in order to determine the number of cycles to failure. The BGA components were daisy-chained - the resistance across each daisy-chain was monitored continuously during the cyclic defection of the test board. A profile of the increase in resistance with cycle number was established and the number of cycles to failure determined. The failure mechanism induced by the cycling was examined using crosssection and scanning electron microscopy (SEM) techniques. The results for SnAgCu joints show a superior performance during torsion mechanical fatigue testing than SnPb joints; giving a greater number of cycles to failure. The results from the tests presented in this paper show that the torsion test method provides a viable alternative to ATC as a qualification method for solder joints, while also providing substantial time savings - taking weeks rather than months to complete.

Original languageEnglish
Title of host publicationProceedings of the ASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems
Subtitle of host publicationAdvances in Electronic Packaging 2005
Pages1223-1228
Number of pages6
Publication statusPublished - 2005
EventASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems: Advances in Electronic Packaging 2005 - San Francisco, CA, United States
Duration: 17 Jul 200522 Jul 2005

Publication series

NameProceedings of the ASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems: Advances in Electronic Packaging 2005
VolumePART B

Conference

ConferenceASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems: Advances in Electronic Packaging 2005
Country/TerritoryUnited States
CitySan Francisco, CA
Period17/07/0522/07/05

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