Low Dispersion Loss Polyimides for High Frequency Applications

We have successfully developed novel low dielectric loss polyimides by investigation of molecular motion and polarity of polyimide chain. We achieved 0.003 of loss tangent and 2.6 of dielectric constant respectively. We found that molecular motion at -50 to -100C is correspond to the dielectric loss at 10-100GHz. To decrease the dielectric loss at high frequency, it is important to restrict molecular motion at low temperature. In addition, polar unit in polyimide chain affects the dielectric loss and dielectric constant. To reduce polar unit in the polyimide chain is also important to obtain low dielectric loss polyimide. Those polyimides are patternable by alkaline wet etching with positive photo-resist development and excimer UV laser drilling. Those low dielectric loss polyimides are useful for insulator of FO-WLP, Interposer and other RF applications for microelectronics.