Processing method of substrate-free circuit board

The invention discloses a processing method of a substrate-free circuit board. The method comprises the following steps: integrally coating a photosensitive material on a metal plate to form a photosensitive layer; selectively exposing the front surface and the back surface of the metal plate by using UV parallel light in a darkroom to obtain a front etching pattern area and a back etching patternarea which are symmetrical to each other; then, correspondingly performing spray etching on the front etching pattern area and the back etching pattern area along the vertical direction; and etchingthe front etching pattern area and the back etching pattern area until the front etching pattern area and the back etching pattern area are etched and communicated, further obtaining a semi-finished substrate-free circuit board a with a circuit structure, finally stripping the photosensitive layer on the surface of the semi-finished substrate-free circuit board a to expose the metal surface, and carrying out cleaning and d