Exposure machine is an indispensable equipment for modern manufacturing of printed circuit board (PCB). In the manufacturing process of PCB, one of the most critical processes is to transfer the negative image to the copper foil substrate. First, a layer of photosensitive material (such as liquid photosensitive adhesive, photosensitive dry film, etc.) is coated on the substrate, and then the photosensitive material coated on the substrate is subjected to light radiation to change its solubility. The resin in the non photosensitive part does not polymerize, but dissolves under the action of developer, and the resin in the photosensitive part remains on the substrate to form an image. This process is called exposure, which is the process completed by the exposure machine in the production of printed circuit boards