Isothermal aging of near-eutectic Sn-Ag-Cu solder alloys and its effect on electrical resistivity

• Published in: Journal of electronic materials Vol. 32; no. 12; pp. 1384 - 1391
• Main Authors: COOK, B. A, ANDERSON, I. E, HARRINGA, J. L, KANG, S. K
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01.12.2003; Springer Nature B.V
• Subjects: AGING; ALLOYS; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity of specific materials; Cross-disciplinary physics: materials science; rheology; ELECTRIC CONDUCTIVITY; Electronic transport in condensed matter; Exact sciences and technology; MATERIALS SCIENCE; Physics; Solid solution hardening, precipitation hardening, and dispersion hardening; aging; Solid solution, precipitation, and dispersion hardening; aging; Transition-metal compounds; Treatment of materials and its effects on microstructure and properties; Inorganic compounds; Electrical conductivity; Ternary alloys; Shear strength; heat treatment; Experimental study; Heat treatments; Tin alloys; Optical microscopy; Pb-free solder; Copper alloys; Aging; Microstructure; Soldered joints; Silver alloys; electrical resistivity; Transition element alloys
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-003-0105-3

Solder joints were prepared from seven eutectic and near-eutectic Sn-based compositions and characterized for electrical resistivity after 100 h and 1,000 h of isothermal aging at 423 K. The solder joint samples were prepared by hand soldering to copper substrates, and the post-heat treatment resistivity was measured at room temperature in a specially designed, four-point probe fixture. Compositions tested included Sn-3.5Ag, Sn-3.7Ag-0.9Cu, Sn-3.OAg0.5Cu, Sn-3.6Ag-1.0Cu, and Sn-3.9Ag-0.6Cu. In addition, the effect of a minor addition of a fourth element, designed to improve high-temperature shear strength, was also evaluated in the compositions Sn-3.7Ag-0.6Cu-0.3Co and Sn-3.7Ag-0.7Cu-0.2Fe. The observed changes in electrical resistivity are discussed in terms of microstructural coarsening, diffusional transport from the substrate, and nucleation of precipitate phases.