1998 年 47 巻 9 号 p. 953-958
Epoxy resins for encapsulating integrated circuit (IC) devices are filled with silica particles to reduce the thermal expansion coefficient and to improve thermal conductivity. Recently, the size of chips mounted in a package has increased rapidly with advances in large-scale integration technology. This trend creates a problem: increased mechanical stress in the package, which sometimes causes cracking in the encapsulation resin under temperature cycling. Hence, evaluation of the fracture properties of these materials has become an important issue in package design. This study reports the effects of the filler particle volume fraction on the static strength of smooth specimens and fracture toughness of silica-particulate-filled epoxy resins for IC encapsulation. The smooth specimen strength and fracture toughness were measured, respectively, by the three-point bending test and the double torsion test.
It was found that the fracture toughness increased with increasing volume fraction. The static strength of epoxy resins with a small amount of silica particulate was smaller than that of unfilled resins. The crack propagation in resins containing 30% volume fraction of large size particles was unstable. At larger than 45% volume fraction of particles, the crack propagation was stable. These crack propagation properties have been related to the plastic zone size of matrix and particle spacing.