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Characterizing Thermal Fatigue Reliability of Third Generation PB-Free Alloys
Analysis Lab |
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Authored By:Richard Coyle Nokia Bell Labs, Murray Hill, NJ, USA Richard Parker iNEMI, Tipton, IN, USA Keith Howell, Keith Sweatman Nihon Superior Co., Ltd., Osaka, Japan Dave Hillman Rockwell Collins, IA, USA Joe Smetana Nokia, Plano, TX USA Glen Thomas, Hongwen Zhang Indium Corp., Utica, NY,USA Stuart Longgood, Andre Kleyner Delphi, Kokomo, IN, USA Michael Osterman CALCE, College Park, MD, USA Eric Lundeen i3 Electronics, Endicott, NY, USA Polina Snugovsky Celestica, Inc., Toronto, ON, Canada Julie Silk Keysight Technologies, Santa Rosa, CA, USA Rafael Padilla, Tomoyasu Yoshikawa Senju Metal Industry Co., Tokyo, Japan Jasbir Bath Bath & Associates Consultancy, Fremont, CA, USA Mitch Holtzer Alpha Assembly Solutions, South Plainfield, NJ, USA Jerome Noiray, Frederic Duondel Sagem, Paris, France Raiyo Aspandiar Intel Corporation, Hillsboro, OR, USA Jim Wilcox Universal Instruments Corporation, Conklin, NY, USA SummaryDevelopment of the first generation of current commercial Pb-free solder alloys was based on, high Ag content, neareutectic Sn-Ag-Cu (SAC) compositions. Subsequently, second generation, lower Ag alloys were developed to address the shortcomings of near-eutectic SAC, particularly poor mechanical shock performance. The development of third generation Pb-free solder alloys is proceeding along two prominent paths. In one case, high-Ag content alloys are being modified with various major alloying additions to improve thermal fatigue performance in aggressive use environments and increase resistance to damage from high strain rate mechanical loading. In the other case, alloys with Ag content lower than SAC305 are being developed to address needs for better drop/shock resistance, lower processing (melting) temperature, and lower cost. This paper describes the planning and progress of an experimental program for evaluating the thermal fatigue performance of a number of third generation alternative Pbfree solder alloys. The program is being developed and executed through a collaboration of several major industrial consortia that includes membership from high reliability end users, solder suppliers, and electronic contract manufacturers. ConclusionsThe status of critical project items at the time of this writing is as follows: The solder ball attachment has been completed on all of the components required to populate the thermal cycling and baseline test matrix. The stencil printing process and surface mount reflow profile were developed using SAC305 components and solder paste during a pilot build conducted at Rockwell Collins. Multiple stencils have been ordered to facilitate the assembly of the complete test matrix. All but one of the solder pastes have been delivered to Rockwell Collins and are in refrigerated storage. The surface mount assembly of the test boards is anticipated to begin in early September 2016 depending on the delivery of the complete sets of components and solder pastes to Rockwell Collins. Thermal cycling will be performed at four participant sites: CALCE (-40/125 Celsius), i3 (-40/150 Celsius), Nokia Bell Labs (0/100 Celsius), and Rockwell Collins (-55/125 Celsius). Initially Published in the SMTA Proceedings |
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