The rapid development of the 5G communication technology requires the improvement of the thermal stability and dielectric performance of high-frequency copper clad laminates (CCL). A cyclic olefin copolymer (COC) resin was added to the original 1,2-polybutadienes (PB)/styrene ethylene butylene styrene (SEBS) binary resin system to construct a PB/SEBS/COC ternary polyolefin system with optimized dielectric properties, mechanical properties, and water absorption. Glass fiber cloths (GFCs) and SiO2 were used to fill the resin matrix so to reduce the thermal expansion coefficient (CTE) and enhance the mechanical strength of the composites. It was found that the CTE of polyolefin/GFCs/SiO2 composite laminates decreased with the increase of SiO2 loading at first, which was attributed to the strong interfacial interaction restricting the segmental motion of polymer chains between filler and matrix. It was obvious that the addition of COC and SiO2 had an effect on the porosity, as shown in the SEM graph, which influenced the dielectric loss (Df) of the composites directly. When the weight of SiO2 accounted for 40% of the total mass of the composites, the laminates exhibited the best comprehensive performance. Their CTE and Df were reduced by 63.3% and 22.0%, respectively, and their bending strength increased by 2136.1% compared with that of the substrates without COC and SiO2. These substrates have a great application prospect in the field of hydrocarbon resin-based CCL.
Keywords: dielectric properties; fillers; polymer-based composites; substrate materials.