A PCB stencil is a patterned sheet, usually metal or polymer, that controls where solder paste is deposited on a printed circuit board’s pads. The stencil has cutouts that match the board layout, letting paste be applied in a repeatable way before components are placed and the board is reflowed.
In cyber security, PCB stencils matter because they affect how reliably hardware is built. Consistent paste deposition helps reduce solder defects that can cause intermittent faults, weak joints, or boards that fail quality checks. That matters in secure device manufacturing, where reliability and traceability are part of supply-chain trust. In practice, stencils appear in prototype labs, contract assembly, and controlled production lines; defenders use accurate stencils to improve yield, while attackers or counterfeiters could exploit poor fabrication process control to introduce defects or weaken hardware integrity.