Nucleation Control and Thermal Aging Resistance of Near-Eutectic Sn-Ag-Cu-X Solder Joints by Alloy Design

TitleNucleation Control and Thermal Aging Resistance of Near-Eutectic Sn-Ag-Cu-X Solder Joints by Alloy Design
Publication TypeJournal Article
Year of Publication2009
AuthorsAnderson IE, Walleser JW, Harringa JL, Laabs F, Kracher A
Journal TitleJournal of Electronic Materials
Volume38
Pages2770-2779
Date Published12/01
ISBN Number0361-5235
Accession NumberISI:000272301900041
Keywords(zn, ag3sn, ag3sn blades, al) additions, LEAD-FREE SOLDERS, microstructure, mn, pb-free, pb-free solder, shear strength, solidification, thermal aging, undercooling
Abstract

Elemental (X) additions to Sn-3.5Ag-0.95Cu (SAC3595) solder were developed with minimal (< 0.25 wt.%) concentration to avoid pro-eutectic Ag3Sn blades by reducing undercooling (Delta T) and to eliminate thermal-aging-induced embrittlement. Calorimetry and microstructure results on simple Cu/Cu joints identified 0.21Zn, 0.10Mn, and 0.05Al as sufficient to reduce undercooling below that for SAC3595 and to eliminate Ag3Sn blades. A 211A degrees C melting onset for the X = Mn alloys also suggested the discovery of a new quaternary eutectic. Shear testing and microstructure analysis of larger joints showed that 0.05Al and 0.21Zn additions resulted in reduced as-soldered strength (30 MPa), like Sn-0.95Cu, but all joints showed ductile failure at about 30 MPa after 1000 h at 150A degrees C.

URL<Go to ISI>://000272301900041
DOI10.1007/S11664-009-0936-7