Key Materials in Solder Mask Ink for Printed Circuit Board

Abstract Solder mask ink (SMI) layer can avoid the short circuit between electronic component and land for the fabrication of printed circuit board (PCB). More importantly, the layer not only protects the board from the corrosion of moisture, mildew, or salt spray but also reduces the contamination of weld, and increases the degree of insulation by forming stable three‐dimensional net structure. Therefore, the SMI plays a decisive role for the service life of PCB. This review mainly summarizes three types of SMI including epoxy resin ink, acrylic acid resin ink, and phenolic resin ink for PCB. The focus is the effect of the changes of key materials, such as the design of the binder resin, the selection of the curable agent, and the variation of the colorant and initiator on the performances of epoxy resin SMI layer. Then other types of ink such as acrylic acid resin ink and phenolic resin ink have been discussed, especially about how the change of the binder resin influences the SMI film properties. At last, the development trend of the SMI is proposed. The review has significant meaning for the development and improvement of the SMI and the investigation is important for the application and exploitability of the high‐quality PCBs.