High-temperature effects on kinetics and grain orientation of the Cu41Sn11 phase formed from the full Cu3Sn joint during the aging process

Abstract

In the present study, the intermetallic compound (IMC) joints consisting of Cu3Sn were aged at high temperatures of 540, 560, and 580 °C to form a sole phase of Cu41Sn11 in a short time period. The variations in morphology, growth kinetics, and grain orientation for the Cu41Sn11 phase originating from the Cu3Sn during the high temperature conditions were systematically investigated. The original Cu3Sn phase appeared as slender grains, while the final phase, which contained Cu41Sn11 grains, was displayed as coarse columnar grains. The growth kinetics for the Cu41Sn11 phase during the 540, 560, and 580 °C temperature testing periods were roughly controlled by the grain boundary diffusion and more precisely controlled by the activation energy, which was 72.86 kJ/mol. The growth rate constant of k0 was 2.5*10^7 μm3/min. The original Cu3Sn phase exhibited two preferred orientations of [100] and [203], while the Cu41Sn11 phase did not exhibit the apparent grain orientation. Various temperatures had specific effects on the kinetics and the orientation: The newly formed Cu41Sn11 grains were used to maintain the coherent or semi-coherent interface ((111)F//(100)P and [101]F//[010]P) and reduce the interfacial energy, which resulted in the step-growth mechanism during the early stage noted at 540 °C (lower temperature); by contrast, non-coherent interface between Cu3Sn and Cu41Sn11 was formed during the higher temperature (580 °C), which also resulted in the formation of more small-size cores with large amounts of grain boundaries without apparent orientation; their mechanism of growth was controlled by the grain boundary diffusion.