Solder Mask vs Paste Mask in PCB: Key Differences

Solder Mask (also known as solder resist layer) and Paste Mask (also known as solder paste layer) are two crucial layers in the manufacturing process of Printed Circuit Boards (PCBs).

Solder Mask is a type of solder resist paint, typically green in color, that covers the metal solder pads on a PCB. Its primary function is to protect the metal solder pads from external environmental factors such as dust, corrosive substances, etc. Solder Mask also helps reduce soldering errors, preventing short circuits and rework. By covering the solder pads, Solder Mask also provides good insulation performance.

Paste Mask is a layer used to determine the position and shape of solder paste (the adhesive for soldering metals) on the solder pads. It is a thin film, usually white or transparent. By applying Paste Mask on the PCB, manufacturers can accurately apply solder paste to the necessary soldering locations before assembling electronic components. The design of the Paste Mask should match the solder paste’s grain size to ensure proper adhesion to the solder pads, thus achieving high-quality soldering connections.

Therefore, Solder Mask and Paste Mask have different functions and roles in the PCB manufacturing process. Solder Mask is used to protect the pads and provide insulation, while Paste Mask is used to determine the location and shape of the solder paste for precise soldering connections.