Bondability Evaluation of Pressureless Sintering Copper Die-Bonding Paste

Abstract

This paper describes the sintering properties and bondability of pressureless sintering Cu die-bonding paste for power devices operating at high temperatures. The sintered density (D_s) and thermal conductivity of pressureless sintered Cu (in H₂, 300°C) were 78% and 180 Wm^–1K^–1, respectively. In a three-point bending test, sintered Cu has a higher 0.2% yield strength than pressure sintered Ag (in air, 300°C, 10 MPa, D_s = 87%) as a comparison material. The bonding strength of sintered Cu to the adherend (Cu, Ni, Ag and Ni/Au) was 30 MPa or more. The thermal cycle tolerance of 1,000 cycles (–40°C/200°C) or more was shown in a simulated power device package which was bonded using sintered Cu and encapsulated with epoxy molding compounds.