Soldeermasker

Soldeermasker is the Dutch term for the solder mask used in printed circuit board (PCB) fabrication. In English, it refers to a thin polymer layer applied over copper traces to insulate them, protect against oxidation, and prevent solder bridges during assembly. The mask is a standard feature on most PCBs and plays a key role in solderability, reliability, and manufacturability.

There are two main formats: liquid photoimageable (LPI) solder mask and dry-film solder mask. LPI masks are applied as a liquid that is patterned by ultraviolet light through a photomask, then developed and cured. Dry-film masks are pre-laminated, exposed, and developed similarly. Materials are typically epoxy-based polymers, and the resulting layer is usually only a few tens of micrometers thick. Green is the traditional color, but masks are available in multiple colors for identification and inspection purposes.

The mask covers most copper areas and leaves openings, or apertures, over pads, vias, and test points. This selective exposure defines where solder will be applied and where it will be blocked, helping to control solder paste deposition and preventing bridging between adjacent conductors. In addition to electrical insulation, the mask provides environmental and chemical protection, contributes to soldering yield, and can influence thermal behavior and rework options.

In design and manufacturing, the solder mask is specified in PCB CAD data and manufacturability documentation. Considerations include mask expansion, tenting of vias, and mask-defined versus non-mask-defined pad styles. The Dutch term soldeermasker highlights its role as a standard feature in modern electronics production.