Feasibility Investigation and Characterization of Liquid Dispersant–Assisted Sintering of Silver to Bond Large‐Area Plates

Silver paste, as a novel thermal interface material, has wide applications in elevated temperature power electronics. In practice, usually pressure higher than 5 MPa is necessary for large‐area bonding by silver paste, regardless the fact that uneven pressure may cause fracture of brittle components such as chips and ceramic substrates. Herein, the feasibility of using liquid dispersant to assist large‐area silver sintering is proved. The introduced large‐area bonding method can obtain sound bonding with pressure lower than 5 MPa. The employed dispersants, namely, α terpineol, polyethylene glycol, and polyvinylpyrrolidone have improved sintering quality in various degrees. α terpineol shows the best bonding quality with average shear strength of 41.4 MPa. The bondline exhibits homogeneous porous structure with no obvious interfacial delamination. Plastic deformation of silver particles can be observed on fracture surface. In addition, the bonded plates with α terpineol show better long‐term reliability during thermal cycling tests than those without α terpineol. The liquid dispersant helps to accelerate rearrangement of silver particles, promote interfacial contact, and prevent interfacial delamination, thus increase the bonding strength and long‐term reliability of large‐area silver sintered plates.