Low transmission loss flexible substrates using low Dk/Df polyimide adhesives

摘要

We developed solvent-soluble polyimides with good heat resistance and low dielectric constant (Dk) / dissipation factor (Df) characteristics by optimizing the composition ratio of the aliphatic, cycloaliphatic, and aromatic groups present in the polyimide back bone. We found that the adhesives prepared using our polyimides showed good adhesion to polyimide films and low profile copper foils and low Dk / Df. Furthermore, we developed a flexible copper clad laminate (FCCL) with our polyimde (PI) adhesives, low-pofile copper foils, and normal PI films. This FCCL showed a transmission loss similar to that of liquid crystal polymer (LCP) FCCLs at frequencies less than 15GHz. This result indicates that by using our PI adhesives, lower cost FCCLs can be prepared, which can then be used as high-frequency substrates.