This focus review describes two types of thermoplastic films developed via formulation design technology for mmWave communication. The first type is a crystalline polyaryletherketone (PAEK)-based film, which is improved with plate-like fillers and miscible noncrystalline polymers. This film exhibits low dielectric properties, heat resistance, low thermal expansion, and excellent multilayer processing capabilities. The second type is a specialized polyolefin resin-based film, which achieves ultralow dielectric properties comparable to those of PTFE and combines excellent copper adhesion with customizable functionalities such as laser processability, transparency, and flame retardancy.
