Preparation, Structure and properties of aluminium nitride (A1N) reinforced polymer composites: Alternative substrate materials for microelectronic packaging

A series of composite materials of varying compositions based on a high temperature resistance engineering thermotropic liquid crystalline polymer and particulate aluminium nitride (A1N) were compounded at relatively low temperature using a co-rotating twin screw extruder/compounder equiped with the segmented screws. The compounded composites are injection moulded into different shapes, i.e., dumbbell, rectangular bar and cylindrical disk, for various physical and mechanical tests. In particular, detailed study was carried out to understand the effect of A1N on the dielectric constant (1 kHz to 10 MHz), thermal conductivity and thermal expansion behaviour of these materials. Results have shown that the thermal conductivity steadily increases with A1N filler concentration. An increase by about 80% in thermal conductivity of the composite materials is achieved as compared to the unfilled polymer. The dielectric constants of these composites were found to increase with filler content and range from 3.6 to 5.0 at 1kHz and 3.0 to 4.2 at 10 MHz. Substantial reduction in thermal expansion coefficient was also achieved in the composite materials. Attempt has been made to correlate the experimental data with composite theories.