Kinetics of reactive diffusion between Au and Sn during annealing at solid-state temperatures |
| |
Authors: | T. Yamada K. Miura M. Kajihara N. Kurokawa K. Sakamoto |
| |
Affiliation: | aGraduate School, Tokyo Institute of Technology, Yokohama 226-8502, Japan bDepartment of Materials Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan cTyco Electronics AMP Co. Ltd., Kawasaki 214-8533, Japan |
| |
Abstract: | The reactive diffusion between Au and Sn was experimentally studied at solid-state temperatures using Sn/Au/Sn diffusion couples prepared by a diffusion bonding technique. The diffusion couples were annealed at temperatures of T = 393 and 473 K for various times in an oil bath with silicone oil. After annealing, compound layers composed of AuSn4, AuSn2 and AuSn were recognized to form at the Au/Sn interface. The thickness of the AuSn4 layer is about six and four times greater than those of the AuSn2 and AuSn layers at T = 393 and 473 K, respectively. The ratio of the thicknesses of the compound layers is kept constant independently of the annealing time. The total thickness l of the compound layers is described as a function of the annealing time t by the equation l = k(t/t0)n, where t0 is unit time, 1 s. The exponent n is nearly equal to 1/2 at T = 393 K but takes a value between 1/4 and 1/2 at T = 473 K. Such an intermediate value of n at T = 473 K indicates that the grain boundary diffusion contributes to the reactive diffusion and the grain growth occurs at certain rates. As the annealing temperature decreases, the contribution of the grain boundary diffusion should become more remarkable, but the grain growth will slow down. Consequently, n becomes close to 1/2 at T = 393 K. According to the constancy of the ratio of the thicknesses, it is concluded that the same rate-controlling process works in the AuSn4, AuSn2 and AuSn layers at a constant annealing temperature. |
| |
Keywords: | Diffusion bonding EPMA Intermetallic compounds Bulk diffusion Solder |
本文献已被 ScienceDirect 等数据库收录! |
|