Relationship of Particle Content and Size of Spherical Silica with the Flowability of Epoxy Molding Compounds for Large-Scale Integrated Circuits Packaging

The melting viscosities of different kinds of epoxy resins have been investigated in this paper. The results showed that tetramethyl biphenyl epoxy resin(TMBP) has very low melting viscosity(0.02Pa•s at 150°C) and can be blended with ortho-cresol novolac epoxy resin(ECN) in order to decrease the melting viscosity of epoxy molding compound(EMC). When the content of TMBP in the blend of ECN/TMBP was up to 40wt%, the viscosity of the blend decreased to 0.15 Pa•s from 0.8 Pa•s of ECN. In addition, the effects of the content, particle size of silica on the flowability of EMC have been researched systematically in the paper. The results showed that the melting viscosity of EMC increased greatly with the filling increasing of silica, and the particle size and the match of silica with different particle diameter had markedly influenced on the flowability of EMC. The melting viscosity of system with higher filling content of silica changed complicatedly with the increasing of shear rate, i.e., the viscosity of the system decreased with the increasing of shear rate in the range of low shear rate, then increased with the increasing of shear rate in the range of high shear rate, but decreased again with the increasing of shear rate in the range of higher shear rate. The system filled by silica with small particle diameter had low melting viscosity at low shear rate and high melting viscosity at high shear rate, but the melting viscosity of the system filled by silica with large particle diameter changed by contraries.