Low-Temperature Sintering Bonding Using Silver Nanoparticle Paste for Electronics Packaging

Ag nanoparticles (NPs) with about 40 nm diameter covered with 5-8 nm organic shell were prepared by chemical reduction reaction. The thermal characteristics of Ag nanoparticle (NP) paste were measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The low-temperature sintering bonding processes using Ag NP paste were carried out at the temperature range of 150-350 degrees C for 5 min under the pressure of 3 MPa. The microstructures of the sintered joint and the fracture morphology were evaluated by scanning electron microscopy (SEM). The shear strength was used to evaluate the mechanical property of the sintered joint. TGA-DSC test showed that the Ag content is approximately 95.5 mass% in Ag NP paste. The average shear strength of the joint fabricated at 250 degrees C for 5 min under the pressure of 3 MPa was about 28 MPa, which could meet the requirements of electronics packaging working at high temperature. The joint shear strength increased with the increase of the sintering temperature due to much denser sintered Ag NPs and more comprehensive metallurgical bonds formed in the joint.