Where colour matters
- Inspection — green and blue give contrast for AOI; black absorbs light and hides thin traces; white shows every fingerprint and flux residue.
- Resolution — fine mask dams between pads are easier with mature green ink than with heavily pigmented colours.
- Thermal and UV — white mask yellows under prolonged heat and UV; matte finishes show handling marks.
- Assembly — dark mask makes fiducial recognition and rework harder for operators.
Practical rule
Choose colour for the product, then confirm the fine-pitch geometry can be printed in that ink. If the board has 0.4 mm pitch or a narrow mask dam, green or a specified matte ink with proven resolution is safer than an exotic colour.
Colour never changes the electrical function. It changes yield, inspection time and how the board looks after three years in the field.
