Interfacial intermetallic compounds growth kinetics and mechanical characteristics of Ga-Cu interconnects prepared via transient liquid phase bonding

Driven by continuous miniaturization, higher performance, and functional robustness in three-dimensional (3D) embodiments of electronic devices, Ga which possesses a low melting point (29.8°C) has shown its potential uses in electronics packaging and integration. The use of Ga metal as a solder material to achieve low-temperature transient liquid phase bonding (TLPB) has emerged as a viable solution for reliable interconnections of future-generation products. This study investigates the interfacial intermetallic compounds (IMCs) structure, growth kinetics, and mechanical characteristics of Ga-Cu TLPB joints in the temperature range of 150 to 220°C. The Cu9Ga4 phase were observed and the growth rate of Ga-Cu IMCs has been investigated. The research findings indicate that the growth mechanism of interface IMCs is primarily diffusion-controlled, with CuGa2 grains exhibiting anisotropic growth. Their shear strength has reached 23.8 MPa, with a porosity of 1.82±0.07%. Furthermore, the fracture interface is presented and correlated with the experimental observations.