PCB Solder mask or PCB solder stop mask or solder resist is a thin lacquer-ish layer of polymer; it is applied to the copper traces of a PCB board for protection against oxidation and to prevent solder bridges; the formation of an undesirable electrical connection between two conductors by means of a small blob of solder. PCBs use solder masks to prevent this from happening. Solder mask does not only function to handle soldering assemblies; but, its presence is also essential for mass production assemblies that are soldered automatically using reflow or solder bath techniques. So, In today’s article, we will understand what is a PCB solder Mask, its types, and its need in PCB designing.
Top- and Bottom – side MasksEpoxy LiquidEpoxy liquid is a lower cost type of solder mask. It is a quick setting thermosetting polymer. It utilizes Silk screening printing technique that uses a woven mesh to support ink blocking stencils or patterns. The mesh creates open areas for ink transfer. After that, the final finishing process involves thermal curing.
Liquid photo image able solder mask comes as an ink formulation. The ink can be silkscreened or sprayed onto the PCB; the PCB is then exposed to the pattern and developed. Also, One type of process commonly used with liquid ink formulations is hot air surface leveling (HASL). It requires a clean environment, free of particles and contaminants. After that, that UV light exposure stage, the mask is removed using high pressure water sprays called developers.
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