Study of interfacial reactions between Sn3.5Ag0.5Cu composite alloys and Cu substrate

For development of a lead-free composite solder for advance electrical components, lead-free Sn3.5Ag0.5Cu solder was produced by mechanically mixing 0.5 wt.% TiO2 nanopowder with Sn3.5Ag0.5Cu solder. The morphology and growth kinetics of the intermetallic compounds that formed during the soldering reactions between Sn3.5Ag0.5Cu solder with intermixed TiO2 nanopowder and Cu substrates at various temperatures ranging from 250 to 325 °C were investigated. A scanning electron microscope (SEM) was used to quantify the interfacial microstructure at each processing condition. The thickness of interfacial intermetallic layers was quantitatively evaluated from SEM micrographs using imaging software. Experimental results show that a discontinuous layer of scallop-shaped Cu–Sn intermetallic compounds formed during the soldering. Kinetics analysis shows that the growth of such interfacial Cu–Sn intermetallic compounds is diffusion controlled with an activation energy of 67.72 kJ/mol.

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