Development of Low Dk and Df polyimides for 5G application

Abstract

We have newly developed non photosensitive and photosensitive polyimide having excellent electrical/mechanical properties. At first we have re-designed the polymer backbone in order to obtain low Dk and Df performance. As a result, our new non photosensitive PI achieved 2.9 of Dk at 20 GHz and 0.003 of Df at 20 GHz. In the next step, we selected the photo package of new PI carefully to maintain both low Dk/Df and high resolution. After that, we modified the photo initiator content, crosslinker content, and so on to have both high lithographic performance and high electrical performance. As a result, new photosentive PI cured at 320 °C showed 3.0 of Dk at 20 GHz and 0.006 of Df at 20 GHz. In addition, this material cured at 200 °C also showed 3.0 of Dk at 20 GHz and 0.009 of Df at 20 GHz. We also confirmed high mechanical properties of new PI. Elongation of this PI cured at >250 °C was approximately 70 %. From lithographic aspects, new PI achieved 15 μm L/S opening with 10 μm thickness.

Low Transmission Loss Cu Wirings with Smooth Seed Layer and High Adhesion against Prepregs

“…Fan-out wafer/panel level package (FO-WLP and FO-PLP) and transparent glass package with favorable electrical property are considered to be candidate for antenna in package (AiP) [6][7][8]. Flexible printed circuits (FPC) with flexible film composed of low-loss materials such as modified polyimide (M-PI), liquid crystal polymers (LCP) and fluorinated polymers are developed to apply to wiring connectors in edge devices [9][10][11]. In addition, Flip-Chip Ball Grid Array (FC-BGA) with organic or low temperature co-fired ceramic (LTCC) substrate is widely used in high end servers and super computers [12,13].…”