2023 Volume 44 Issue 1 Pages 11-26
As the core technologies to support recent high-capacity and high-speed data communication systems, the importance of flexible printed circuit boards (FPCs) used in mobile communication devices has significantly increased. To obtain FPCs compatible to 5G-communication technologies, novel high-temperature dielectric substrate materials with low dissipation factors (tan δ) at high operating frequencies (≥ 3.6 GHz) are strongly required. This review paper proposes the molecular design for novel heat-resistant dielectrics consisting of modified polyimides, poly(ester imide)s, and exhibits their excellent combined properties, including significantly reduced tan δ values at 10 GHz, extremely low linear coefficients of thermal expansion, suppressed water uptake, and very high glass transition temperatures.
