| 摘要 |
Paste-consistency photopolymer is imaged onto printed wiring boards by use of glass exposure plate having opaque image areas which contact portions of the board on which photopolymer is not to be exposed, and having clear areas elevated above the photopolymer surface. A printed wiring board is coated with UV-curable solder mask photopolymer and exposed to a strong UV lamp through the glass plate pressed against the printed wiring board by atmospheric pressure. As the glass plate does not contact the photopolymer, trapped air can escape and the gloss surface of the photopolymer is preserved. A non-collimated light source is used to produce high resolution photopolymer coatings at line speeds of 12 feet per minute. Where opaque and raised images contact printed wiring board, photopolymer there between is extruded sideward to form beneficial areas of increased photopolymer thickness. In addition to solder mask imaging, graphics of several colors can be produced.
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