Preparation method of printed circuit board of ultrathin metal layer

The present invention discloses a preparation method of a printed circuit board of an ultrathin metal layer. The method employs alkaline fatty amine gas and nitrogen through bubbling of copper sulphate solution to perform vacuum capacitance coupling discharge to generate low-temperature plasma, a polyimide film and an epoxy resin plate coated with glass fibre cloth are subjected to etching and surface processing of grafting active group to increase surface roughness and chemical activity, and the sputtering deposition or electroless copper plating of the film is directly performed to perform electroplating thickening to the required thickness of the copper film. The method does not need bonding agent (non-gel), and is high in peeling intensity so as to realize manufacturing of RPC (Rigid Printed Circuits), multiplayer plates and RFPC (Rigid-Flex Printed Circuits) of the ultrathin metal layer, etc.