Effect of ultrasonic treatment on interfacial reactions and microstructure of SnCr/CuFeNiCoCr solder joints

摘要

The influences of ultrasonic treatment on interfacial reactions and morphology of SnCr/CuFeNiCoCr solder joints were investigated. The as-reflowed solder joints were aged up to 360 h at different temperatures. The diffusion activation energy and growth kinetics of interfacial intermetallic compounds (IMCs) were analyzed during the isothermal aging. The results of the present study indicate that a single layer of (CuFeNiCr)Sn_2 IMC appeared at the SnCr/CuFeNiCoCr solder joints interface. Compared with the solder joint without ultrasonic treatment, the liquid solder would spread further along the ultrasonic orientation and the contact angle between substrate and liquid solder was reduced. In addition, the morphology of interfacial IMC layer could be changed from the rod shape to granular shape under the ultrasonic treatment. A thicker interfacial IMC layer was discovered in the joints after ultrasonic treatment. With the application of ultrasonic vibration, the grain size was refined. The diffusion activation energy of the interface (CuFeNiCr)Sn_2 IMC layer was obtained by fitting the relationship between diffusion constant (D) and reciprocal of temperature (1/T), which were 79.74 kJ·mol~(-1) and 54.05 kJ·mol~(-1) for ultrasonic treatment time of 0 s and 5 s, respectively.