The Solder Mask is a thin protective polymer layer, which is applied on the conductive tracks of the printed circuit board in flexible PCB manufacturer during the manufacturing process. It protects the copper tracks from oxidation and helps avoiding short circuits. The color variation of the solder mask is the result of liquid photoimagible solder mask (LPI), a special ink, which can be screen printed, sprayed or coated on the PCB.

A Green, Blue, Red or Yellow looking PCB in flexible PCB manufacturer is not actually ‘Green, Blue, Red or Yellow’ all the way through. It gets its color from the solder mask coating, which gives it a unique identity. For any PCB board in flexible PCB manufacturer, the solder mask color selection is crucial, as it helps for enhanced readability, clear visibility of the components mounted on the board, and contrast between tracks, vacant spaces & silkscreen printing / markings.

The solder finish could be Glossy or Matte. A matte finish is slightly dull and soft. This means it will not reflect a lot of light directly but would look washed out under heavy light. PCBs with a Matte finish appear darker and don’t have a true shine, which makes them a good resort during fault detection. The glossy finish appears lighter in color and tends to reflect more light due to which they cannot be considered suitable for fault identification.