Improved performance and long-term reliability of copper paste in electronic packaging by adding copper-coated Si particles

Purpose This study aims to introduce a composite micron copper paste with superior mechanical properties and enhanced reliability, achieved through the incorporation of reinforcement particles with a copper-coated Si microparticle (Si@Cu) core-shell structure. Design/methodology/approach Samples of Cu/sintered Cu/Cu joints prepared with Si@Cu 5 %, Cu-Si 5 % and Cu 100 % micron copper pastes were systematically analyzed under high-temperature aging (200 °C) and thermal cycling (−40 °C to 150 °C). The microstructure, shear strength and fracture morphology of these samples were thoroughly examined. Findings The Si@Cu 5 % copper paste achieved shear strength values of approximately 56 MPa after 1000 h of high-temperature aging and 52 MPa after 500 cycles of thermal cycling, demonstrating superior long-term reliability than the other two pastes. The superior shear strength was primarily attributed to nanoscale copper particles on the surface of the Si@Cu core-shell structure, which enhanced sintered layer density and improved quality. In addition, internal Si particles reduced the overall coefficient of thermal expansion to 16.3 ppm/°C, effectively mitigating thermal mismatch with the copper substrate, leading to higher long-term reliability of the sintered joint. Originality/value This study provides a theoretical basis and technical guidance for the development of high-reliability sintered copper pastes.