Preparation of low dielectric constant and low loss PI/PTFE composite films by self-assembly of microbranched structures

The low surface energy of polytetrafluoroethylene (PTFE) makes it difficult to achieve a good bond with other materials, so PTFE composites have poor mechanical strength and electrical properties. When PTFE is added in situ, a micro-branched structure is introduced, and along with the continuous formation of the polymer branched structure, a uniformly distributed PTFE micro-phase is constructed in situ in the polyimide (PI) matrix. The method described in this study produces a PI/PTFE film with 5 wt% PTFE content. This film has a dielectric constant of 2.52, a dielectric loss factor of 0.0011, and a contact angle of 87.5 degrees. These properties make it an excellent choice for high-frequency flexible printed circuit (FPC) insulation.