To improve the performance of Prepreg voids filling and flowing of heavy copper design, the performance of the of the solder mask flatness and solve the problem of bubbles of outer layers , etc., the resin with low CTE and excellent thixotropic fluidity is adopted to develop an prepreg resin with high flatness and low warpage. meanwhile, it can also cope with slot filling, and resin Voids Filling can effectively solve the process bottleneck of heavy copper board in the process of lamination and outer layer soldering.