In situ study of real-time growth behavior of IMC morphology evolution during the Sn/Cu soldering cooling stage

Abstract

The morphology evolution of Cu6Sn5 intermetallic Compound (IMC) in cooling stage were studied. The IMC morphology is scallop-like with small plane observated by synchrotron radiation real-time imaging and high pressure air removing excess liquid solder cooling. But, the IMC morphology observated is prismatic with facet of interior portion and at exterior portion is scallop-like with small plane under air cooling and the cooling stage of synchrotron radiation real-time imaging condition. From that, it can be noted that the morphology evolution of IMC in the solder joint was greatly affected by the cooling phase of interfacial reaction, and IMC morphology partition phenomenon was found. With rise of the solder temperature, the thickness of IMC grows rapidly. At the same time, the thickness of the IMC in the inner region of the spherical solder joint reaches to 7.7245 μm, while the thickness of the IMC at the edge only reaches to 4.556 μm. In the analysis, the growth behavior of interface IMC in cooling stage is affected by copper precipitation in the solder. The precipitation of copper in the solder provides the necessary elements for the rapid growth of IMC in the cooling stage, resulting the IMC morphology transition during the cooling phase.