Fabrication of printed wiring boards by projection imaging
US5138368A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1989 |
| Grant date | Aug 11, 1992 |
| Priority date | — |
| Expiry date | Mar 1, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/2057
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A hard copy such as a printed wiring board is fabricated by exposing to radiation a liquid crystal cell in which a desired pattern is written and directing the pattern-carrying radiation projected from the cell by transmission or reflection to a substrate which is coated with a material sensitive to the radiation and disposed alignedly at an exposure position by optical registration. The duration of the exposure is controlled for a given light intensity and for the type of the coating material. A pattern may be written in one cell substantially simultaneously as another cell is used for the projection imaging. After a produced pattern is compared with a reference pattern, corrections may be effected through a processor which controls the writing of a pattern in a cell.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.