Fabrication of high-strength Cu-Cu joint by low-temperature sintering micron-nano Cu composite paste

To solve the problems of high cost of nano-metal paste and high porosity of die-attach layer, a novel and cost-effective micro-nano Cu composite paste was prepared and demonstrated for fabricating the high-strength Cu-Cu joint at low sintering temperature. The microstructures and bonding properties of Cu-Cu joints were systematically investigated by adjusting the mass ratio of nano- to micron particles and sintering parameters. Consequently, the Cu-Cu joints sintered at 250 degrees C display the high shear strength of 45.6 MPa, and the die-attach layers yield the low resistivity of 5.44 mu ohm cm and the low porosity of 2.67%. Furthermore, the Cu-Cu joints still present the high shear strength of 41.5 MPa at the low sintering temperature of 225 degrees C for 5 min. Therefore, the micro-nano Cu composite paste has a huge potential as a low-cost die-attach material for high-temperature electronic packaging.