Facile Preparation of Cu Micro-Nano Composite Particle Paste for Low Temperature Bonding

To solve the problems of high cost and agglomeration of nanoparticle paste, a novel and inexpensive Cu micro-nano composite paste was prepared and demonstrated for low temperature Cu-Cu bonding. The composite paste was mainly composed of micro particles (1 μm), nanoparticles (10 nm), and organic solvents, and the micron particles as the nucleation sites were coated by the prepared nanoparticles. Moreover, the influences of sintering temperature on the shear strength and microstructure of the bonded joints were investigated. Consequently, the shear strengths of the bonded joints are more than 30 MPa at the sintering temperature of 225°C, 250°C, and 275°C, respectively. Furthermore, their fracture surfaces show significant ductile deformation, and the bonded interfaces between the composite particles and substrates achieve the high purity metallurgical interconnection without the cracks.