| 摘要 |
PROBLEM TO BE SOLVED: To obtain a composite film having low permittivity, being uniform, having uniform formation, being lightweight and having a low coefficient of thermal expansion and a flexible printed circuit board made thereof. SOLUTION: This composite film is one having a structure having a continuous phase comprising a p-directing aromatic polyamide and a phase comprising a low-permittivity resin and having a permittivity of 3.2 or below at 1 MHz or below and a coefficient of thermal expansion within±50×10<-6> / deg.C. In this film, the part of the p-directing aromatic polyamide film is composed of fibrils having a diameter of 1μm or below and has a structure in which the fibrils are arranged in a plane in the form a network or a nonwoven fabric. The composite film is impregnated with a thermoplastic resin and/or a thermosetting resin to obtain a prepreg, and a printed circuit board or laminate is obtained by using such prepregs. |
