In daily life, the most commonly seen color of PCB solder mask is green. With the progress of the times, red, blue, purple, black, pink and other ink colors have been gradually introduced.

The liquid photo-imaging solder mask for circuit boards, usually called LPI or LPISM, is a two-component liquid ink that is mixed before application to maintain its shelf life. It is a relatively economical product designed for spraying, curtain coating or silk Designed for screen printing applications. The mask is a mixture of solvent and polymer to form a thin coating that adheres to different surfaces of the PCB circuit board. The mask usually achieves the original intention of the solder mask by coating areas of the circuit board that do not require any of the various final electroplating surface treatments available today. Unlike old epoxy inks that used to shield pads that require solder or other finishes, LPI inks are sensitive to ultraviolet light. The PCB circuit board panel is completely covered by the mask, and after a short "viscous curing cycle", it is exposed to an ultraviolet light source by using photolithography (exposure through film tools or direct laser imaging using an ultraviolet laser).