Abstract
Extreme temperature change has generally been the great challenge to spacecraft electronic components, particularly in long, periodic, deep-space exploration missions. Hence, researchers have paid more attention to the reliability of component packaging materials. In this study, the microstructure evolution on the interface of Cu/Ni/Au/Au-12Ge/Au/Ni/Cu joints, as well as the effects of extreme thermal shock on mechanical properties and the fracture mode in the course of extreme thermal changes between −196 and 150 °C, have been investigated. Results revealed that the interface layers comprised of two thin layers of NiGe and Ni5Ge3 compounds after Au-12Ge solder alloy was soldered on the Au/Ni/Cu substrate. After extreme thermal shock tests, the microstructure morphology converted from scallop type to planar one due to the translation from NiGe to Ni5Ge3. Meanwhile, the thickness of interface layer hardly changed. The shear strength of the joints after 300 cycles of extreme thermal shock was 35.1 MPa, which decreased by 19.61%. The fracture location changed from the solder to solder/NiGe interface, and then to the interface of NiGe/Ni5Ge3 IMC layer. Moreover, the fracture type of the joints gradually transformed from ductile fracture mode to brittle mode during thermal shock test. Simultaneously, the formation and extension of defects, such as micro-voids and micro-cracks, were found during the process of thermal shock due to the different thermal expansion coefficient among the solder, interface layer and substrate.
Highlights
Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) have restricted the use of conventional Sn-Pb solder due to the perniciousness of lead to the environment and the human body [1,2,3]
Some researchers have investigated the influences of cryogenic temperatures and cryogenic temperatures thermal cycling on the mechanical properties, fracture behavior and microstructure evolution of the solder joint, which indicates that the overall performance of the devices will degrade to a certain extent [18,19]
Cu/Ni/Au/Au-12Ge/Au/Ni/Cu joints were prepared and underwent high- and low-temperature thermal shock to investigated the effect of temperature change on the microstructure evolution and mechanical property of joints
Summary
Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) have restricted the use of conventional Sn-Pb solder due to the perniciousness of lead to the environment and the human body [1,2,3]. Some researchers have investigated the influences of cryogenic temperatures and cryogenic temperatures thermal cycling on the mechanical properties, fracture behavior and microstructure evolution of the solder joint, which indicates that the overall performance of the devices will degrade to a certain extent [18,19]. Cu/Ni/Au/Au-12Ge/Au/Ni/Cu joints were prepared and underwent high- and low-temperature thermal shock to investigated the effect of temperature change on the microstructure evolution and mechanical property of joints. Thereinto, both the Au and Cu layer were the coatings on. The microstructure and shear strength of Au-12Ge solder joints subjected to extreme thermal shock were investigated, and the fracture morphologies of solder joints at different cycles of shock were analyzed in this study [21,22]
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