High Strength die Attaching Structure Fabricated via in Situ Reduction-Sintering of Micron Copper Paste

A novel in-situ reduction method was designed to remove the native oxide on the micro-sized Cu particles’ surface during sintering. Ascorbic acid was innovatively introduced into the organic solvent as a reducing agent to prepare a micron Cu paste. The fresh copper surface was obtained by the reduction of oxide copper particles, which significantly improved surface activity and diffusivity. The sintered die attaching interconnection can achieve a shear strength of 57 MPa which is much higher than most published references, especially for a low sintering temperature of 250 °C.