2023 Volume 44 Issue 6 Pages 266-274
Formation mechanism of phase-separated structure of compounded composition of vinylsilyl group-terminated polyphenylene ether (VS-970) and hydrogenated styrene-butadiene block copolymer (SEBS) developed for high-speed communication multi-layer laminate applications was investigated. A mechanism was suggested in which nano-scale of dispersion consisted from butadiene-derived blocks of SEBS (P(E-B) blocks) present in the VS-970/SEBS composition grow during the curing process to form isolated phases. Whereas the polystyrene blocks (PS blocks) in SEBS dissolve in the polyphenylene ether (PPE) phase and located around the P(E-B) block dispersion, affecting the aggregation behavior of the P(E-B) blocks dispersion during the curing process. When SEBS with a low PS content is used, aggregation of P(E-B) blocks proceeds and a morphology containing a large elastomer phase of 100 nm size is formed. The cured product with a large elastomer phase exhibits a low dielectric loss tangent (Df) value, and this phenomenon was also confirmed in additive formulation systems such as reactive diluents. Laminates using VS-970 show a Df value (0.0029@10 GHz) that is 20% lower than the current technology, and every property such as Tg, solder heat resistance, and copper foil peel strength also satisfies the preliminary required properties.
