Optimal packing research of spherical silica fillers used in epoxy molding compound

Optimal packing of spherical silica fillers used in epoxy molding compound (EMC) field was studied through founding theoretical and experimental models based on Dinger-Funk equation. The former model kept the superposition contentment of calculated particle size distribution (PSD) curve with Dinger-Funk equation distribution curve while the later model ignored the superfine particle distribution area. 8 batches of samples with the same formulation except for filler compositions were prepared including 2 controls and 6 calculated ones with 3 different distribution modulus (0.34, 0.37&0.40) around the theoretical optimal one 0.37. Finished materials were characterized base on standard epoxy molding compound test matrix. Compared with 2 controls, flowability of materials through calculation was increased 30%~50% while keeping steady gel time and the same level of Flash & Bleed. In the mean time, viscosity of materials decreased significantly from 175 poise to 25 poise. It was suggested with applying the calculation method based on the algorithm Dinger-Funk Equation, the flowability of EMC could be obviously improved. The experimental model seemed slightly inferior to the theoretical one. Besides known benefiting physical mechanical properties, such as dielectric property, lower coefficient of thermal expansion and higher coefficient of thermal conductivity, the optimization of filler PSD can help to increase the filler content of epoxy molding compound and reduce viscosity, hence to improve workability and reliability of future packaging of advanced high density packaging for 3D integration.