The properties of AlN-filled epoxy molding compounds by the effects of filler size distribution

AlN filler was compared with crystalline silica as a filler for advanced epoxy molding compounds. Properties such as the thermal conductivity, dielectric constant, CTE, flexural strength, elastic modullus and water absorption ratio of water-resistant grade AlN-filled molding compounds according to the contents or size of AlN and the filler size distribution were evaluated. A spiral flow test was also carried out to measure the change in viscosity according to the AlN size distribution for improved fluidity. The properties of EMC that is filled with a 70 vol.% of 12 micron AlN was compared with a crystalline silica-filled EMC. Thermal conductivity was improved by 2.2 times, the dielectric constant was reduced to less than one-half, the flexural strength was improved, and the CTE was also reduced. A binary mixture of an AlN-filled (65 vol.%) EMC showed improved fluidity, thermal conductivity, dielectric constant, flexural strength and water resistance compared to a single-size AlN-filled EMC. The maximum improvement was obtained when the fraction of small particles in the binary mixture of the AlN is 0.2–0.3. The CTE of EMC was decreased by increasing the volume fraction of small particles in the binary mixture of the AlN.