WELDING RESEARCH A B Fig. 12 — The thickness (X) of Ni3Sn4 intermetallic compounds formed during diffusion soldering of PdNi solid solution coated Pd/Ni couples NOVEMBER 2016 / WELDING JOURNAL 447-s A C D and PdSn intermetallics in this bonding case are similar to those in Case I. The apparent activation energy for the growth of PdSn and Ni3Sn4 intermetallic compounds as calculated from the measurements of intermetallic thicknesses in Fig. 7A and their Arrhenius B plots in Fig. 7B were 44.3 and 36.9 kJ/mol, respectively. It was found that the apparent activation energies for the growth of both intermetallics are slightly higher than those obtained in Case I. The discrepancy can be attributed to the extra reaction of a Sn interlayer with the Ag film in competition with those of Pd/Sn and Ni/Sn interfacial reactions. Shear tests indicated that satisfactory bonding strengths ranging from 10.6 to 17.3 MPa can be achieved with diffusion soldering at temperatures at various temperatures for 30 min using Sn/Ag/Sn interlayers (Case IV). Fig. 13 — Diffusion profiles of the Ni element in the PdNi solid solution covered Pd/Ni couples corresponding to the micrographs in Fig. 11 (Case IV): A — 275°C; B — 300°C; C — 325°C; D — 350°C.
Welding Journal | November 2016
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