Creating a polymeric composite with high thermal conductivity, low dielectric constant, and tangent loss are essential for packaging high-speed electronics. Soft-materials are able to be injected and molded around the transistors but also inherently poor at conducting heat. Even though many approaches that inserting the high conductive component into the polymers are proved to be able to increase the thermal properties, the blended composite is still maintaining the thermal conductivity around ~1W/mK, which is still far lowered than that of the general metal. In this research, we successfully create the new composite materials, not only with better thermal and dielectric properties, but also can be compatible for mass manufacturing. We successfully resolve the uniform distribution of 2D materials (boron nitride) into polymers by pre-mixing the BN and Cellulose nanofibril as a blended component. The orientation of BN inside the polymer are matched by Bruggeman model and demonstration of water-resistance and heaters are discussed. The process increases the thermal conductivity of polymer from 0.2W/mK to 28.181W/mK and has medium to low dielectric constant ~2.4 and ultra-low tangent loss (<10-4) and are suitable for high-speed applications. Finally, we release a GaN film from silicon substrate, and then transfer to composite thin film. The device is biased under the low bias shows that gm is actually increased by 18%.