Mixed filler combinations for enhanced thermal conductivity of liquid encapsulants for electronic packaging

Thermal management plays a very vital role in the packaging of high performance electronic devices. Effective heat dissipation is crucial to enhance the performance and reliability of the packaged devices. Liquid encapsulants used for glob-top, potting, and underfilling applications can strongly influence the package heat dissipation. Traditionally, these encapsulants are filled with silica and show a very poor thermal performance. The technical challenge is to develop encapsulants with improved thermal conductivity without compromising on other critical properties like viscosity, modulus of elasticity, coefficient of thermal expansion, moisture absorption, etc. In a previous study, the performance of encapsulants filled with ceramic fillers like alumina, silica coated aluminum nitride (SCAN), and boron nitride (BN) was compared with that of silica filled samples. It was found that SCAN filled samples have the desirable properties required of liquid encapsulants and also have a higher thermal conductivity than those filled with silica. This paper deals with the study of mixed combinations of fillers to further improve the thermal conductivity of SCAN filled samples. A thermal conductivity of 2.2 W/mK was attained with a combination of SCAN and BN.