Apparatus for use in preparing a printed circuit board and photosensitive ink for in an ink jet printer

Apparatus for use in preparing a PCB product having highly dense conductors, the apparatus comprising:

• a common chassis;
• an inkjet printer mounted on said common chassis and being operative to selectively print unexposed photosensitive patterns on a PCB substrate, said unexposed photosensitive patterns having a thickness of less than 5 μm, wherein said unexposed photosensitive patterns are printed with a photosensitive ink comprising:
• a photoresist constituting 33-64 wt. % of said photosensitive ink;
• a solvent constituting 19.99-59.99 wt. % of said photosensitive ink;
• a humectant constituting 1-10 wt. % of said photosensitive ink;
• a surfactant constituting 0.01-0.1 wt. % of said photosensitive ink;
• an adhesion promoter constituting 1-3 wt. % of said photosensitive ink, said adhesion promoter having a molecular weight between 1700-70000 Da;
• and
• a basic solution constituting 2-3 wt. % of said photosensitive ink, said adhesion promoter being dissolved in said basic solution;
• and
• a pattern exposer mounted on said common chassis and being operative to expose said photosensitive patterns to radiation thereby to define exposed patterns, said exposed patterns having a pitch of less than 20 μm.