Activation energies of intermetallic growth of Sn-Ag eutectic solder on copper substrates

• Published in: Journal of electronic materials Vol. 26; no. 7; pp. 883 - 887
• Main Authors: FLANDERS, D. R, JACOBS, E. G, PINIZZOTTO, R. F
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01-07-1997; Springer Nature B.V
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Diffusion; interface formation; Exact sciences and technology; Metals. Metallurgy; Physics; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Crystal growth; Eutectic alloy; Intermetallic compounds; Interdiffusion; Copper base alloys; Solid-solid interfaces; X-ray spectroscopy; Experimental study; Substrates; Tin base alloys; Solder; Binary alloys; Tin alloys; Transition elements; Copper alloys; Aging; SEM; Kinetics; Copper; Diffusion; Activation energy; Silver alloys; Transition element alloys
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-997-0268-4

Intermetallic phases formed along a Sn-Ag eutectic solder/Cu interface during solid-state aging have been characterized, and the activation energies of Cu sub 3 Sn and Cu sub 6 Sn sub 5 growth have been calculated. Diffusion couples consisting of Cu /96.5Sn-3.5Ag/Cu were aged at 110 to 208 deg C for 0 to 32 days. After aging, the Cu/solder interfaces were examined using scanning electron microscopy and energy dispersive x-ray spectroscopy. The growth rate constants for each intermetallic layer were calculated assuming a simple parabolic diffusion-controlled growth model. The activation energy for Cu sub 3 Sn growth is 0.73 eV/atom and the activation energy for Cu sub 6 Sn sub 5 growth is 1.11 eV/atom.