Title: Sintered nanosilver paste for high-temperature power semiconductor device attachment

Authors: Jesus N. Calata, Thomas G. Lei, Guo-Quan Lu

Addresses: Department of Materials Science and Engineering, Center for Power Electronics Systems, Virginia Polytechnic Institute and State University, 213 Holden Hall, Virginia Tech, Blacksburg, VA 24061-0237, USA. ' Department of Materials Science and Engineering, Center for Power Electronics Systems, Virginia Polytechnic Institute and State University, 213 Holden Hall, Virginia Tech, Blacksburg, VA 24061-0237, USA. ' Departments of Materials Science and Engineering and Electrical and Computer Engineering, Center for Power Electronics Systems, Virginia Polytechnic Institute and State University, 213 Holden Hall, Virginia Tech, Blacksburg, VA 24061-0237, USA

Abstract: Sintered nanosilver is a lead-free die-attach material that could substitute for solder alloys and conductive epoxies for packaging power semiconductor devices, especially for high-temperature applications. While the maximum use temperature of a solder is limited by its melting point, the sintered silver joint can be used above the processing temperature, thus enabling high-performance power devices based on SiC technology to operate at high temperature. It can be fired at temperatures below 300°C without requiring applied pressure to form a dense interconnection with thermal and electrical conductivities superior to those of common high-temperature solder alloys. Die-shear strengths between 25 and 35 MPa can be obtained which compares favourably to the shear strength of solder. Unlike solder, which tends to form large voids during reflow, the sintered silver has a low elastic modulus and a microstructure containing only randomly distributed micrometer-scale pores that eliminates hot spots in the joint.

Keywords: power electronics modules; packaging; nanoscale silver paste; low-temperature sintering; sintered joints; lead-free material; high-temperature die-attach; silicon carbide die-attach; semiconductor devices; sintered silver; thermal conductivity; electrical conductivity; die shear strength; elastic modulus; microstructure.

DOI: 10.1504/IJMPT.2009.022406

International Journal of Materials and Product Technology, 2009 Vol.34 No.1/2, pp.95 - 110

Published online: 04 Jan 2009 *

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