Transparent Liquid Ag-Based Complex for the Facile Preparation of Robust Sintered Ag Joints in Power Devices

Abstract

Simplifying the bonding technique used to package power devices is crucial for electric vehicles and 5G communication. Herein, a transparent liquid Ag-based complex was employed to simplify the Ag sintering process. The complex can directly fabricate Ag nanostructures on substrates and dies by thermal decomposition at 180 °C for 30 min. These nanostructures consisted of linked nanoparticles with a wide size distribution and exhibited remarkable compressibility, indicating an excellent potential for sintering. Unlike traditional Ag paste, the Ag-based complex presented a single phase, and the obtained Ag nanostructures could be directly sintered at a low temperature. Robust sintered Ag joints with a high average shear strength of 45.4 MPa and a low porosity of 9.3% were successfully achieved by sintering at 300 °C and 5 MPa for 40 min. Such joint properties can be attributed to the frame−filler structure generated during sintering. This structure, which featured large Ag particles acting as frames and small Ag particles acting as bridges linking the frames, was beneficial for improving the sintering performance of the Ag nanostructures. The Ag-based complex could be used for the facile preparation of robust sintered Ag joints, creating possibilities for die attachment while reducing manufacturing costs.