Pressureless low temperature sintering of Ag nanoparticles for interconnects

Cu-to-Cu interconnects were achieved by pressureless low temperature sintering of Ag nanoparticles for electronic packaging. Ag nanoparticles could be sintered so long as the chemical bonds by which organic shells connected with Ag nanoparticles were broken with no necessity that organic shells completely decomposed, which provided a way to lower bonding temperature. The pinecone-like recrystallization morphology of sintering Ag nanoparticles was observed by transmission electron microscopy, which resulted from the residuals of organic shells by sintering process. The thermal conductivity of sintered Ag nanoparticles was affected strongly by the recrystallization morphology because of grain boundary scattering effect. The shear strengths of joints reached 17-25 MPa at temperatures ranging from 150 °C to 200 °C.