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Lead-free composite solder

United States Patent Application

20170095891
A1
View the Complete Application at the US Patent & Trademark Office
A composite solder material for mixing with flux to provide a composite solder paste. The solder material includes a mixture having a relatively low melting solder or solder-forming powder and a relatively high melting Ni-containing reinforcement powder. Use of the solder paste under solder reflow conditions produces a high melting point solder joint by liquid phase diffusion bonding wherein a Ni-stabilized high temperature hexagonal (Cu,Ni).sub.6Sn.sub.5 phase is the solder joint matrix that bonds together the Ni-containing reinforcement powder particles. With each reflow cycle, more of the low melting solder or solder-forming powder is converted to the hexagonal (Cu,Ni).sub.6Sn.sub.5 matrix phase, raising the final melting temperatures of the post-processed solder joint and giving the solder the ability to withstand higher Joule-heating, all while improving resistance to solder joint cracking.
Anderson, Iver E. (Ames, IA), Choquette, Stephanie M. (Ames, IA), Reeve, Kathlene N. (Lafayette, IN), Harringa, Joel L. (Ames, IA)
Iowa State University Research Foundation, Inc.
15/ 330,496
September 28, 2016
CONTRACTUAL ORIGIN OF THE INVENTION [0002] This invention was made with government support under Grant No. DE-AC02-07CH11358 awarded by the U.S. Department of Energy. The government has certain rights in the invention.