Insulating Substrate: The mainstream is polyimide (PI) (high temperature resistance 260℃+, dimensional stability, approximately 80% content); low-cost scenarios use polyester (PET) (low temperature resistance, prone to embrittlement); some special requirements involve modified CPI or aramid fiber esters.
Conductive Layer: For dynamic bending scenarios, rolled copper foil (RA) is preferred (excellent ductility); for static or low-cost scenarios, electrolytic copper foil (ED) is used; common thicknesses are 9μm–35μm (1/3oz–1oz).
Bonding and Protection: Traditional structures contain acrylic or polyimide adhesives (adhesive-based); high-performance systems use adhesive-free copper clad laminates (2L-FCCL) for direct hot-pressing, reducing dielectric loss and delamination risk; the outer layer is covered with a PI cover film for insulation protection.
