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Lead-free solder

United States Patent

May 15, 2001
View the Complete Patent at the US Patent & Trademark Office
Ames Laboratory - Visit the Iowa State University Research Foundation - Office of Intellectual Property & Technology Transfer Website
A Sn--Ag--Cu eutectic alloy is modified with one or more low level and low cost alloy additions to enhance high temperature microstructural stability and thermal-mechanical fatigue strength without decreasing solderability. Purposeful fourth or fifth element additions in the collective amount not exceeding about 1 weight % (wt. %) are added to Sn--Ag--Cu eutectic solder alloy based on the ternary eutectic Sn--4.7%Ag--1.7%Cu (wt. %) and are selected from the group consisting essentially of Ni, Fe, and like-acting elements as modifiers of the intermetallic interface between the solder and substrate to improve high temperature solder joint microstructural stability and solder joint thermal-mechanical fatigue strength.
Anderson; Iver E. (Ames, IA), Terpstra; Robert L. (Ames, IA)
Iowa State University Research Foundation, Inc. (Ames, IA)
08/ 796,471
February 10, 1997
CONTRACTUAL ORIGIN OF THE INVENTION The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-82 between the U.S. Department of Energy and Iowa State University, Ames, Iowa, which contract grants to Iowa State University Research Foundation, Inc. the right to apply for this patent.