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Step and Repeat Exposure Apparatus

IP.com Disclosure Number: IPCOM000077630D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Sutton, WJ: AUTHOR

Abstract

Highly accurate exposure of photosensitive emulsions and photoresist is required for producing printed circuits. Near-contact exposure and printing avoids the master or production image masks being inadvertently damaged or worn. In the step and repeat process the same image is repetitively exposed several times on the photosensitized plate, using a floating exposure head under which the plate is moved laterally.

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Step and Repeat Exposure Apparatus

Highly accurate exposure of photosensitive emulsions and photoresist is required for producing printed circuits. Near-contact exposure and printing avoids the master or production image masks being inadvertently damaged or worn. In the step and repeat process the same image is repetitively exposed several times on the photosensitized plate, using a floating exposure head under which the plate is moved laterally.

Accurate positioning of exposure head 1, carrying image mask 2, in relation to photosensitive plate 3 is ensured by relying on a gas film (air or nitrogen) to support head 1 above emulsion 4. A further gas film at the arcuate bearing surfaces 5 (curvature 12 - 18 inches) between head 1 and support base 6 (separation 0.1 mil) provides low friction, which enables the head to conform with variations in thickness of photosensitive plate 3, as head and plate are moved relative to each other.

Exposure of photosensitive emulsion 4 is accomplished by directing light from serpentine tubular lamp 7 through image mask 2 which, by evacuated channels 8, 9, is held in place in head 1 by vacuum attraction to elements 10.

At the arcuate bearing surfaces 5, resilient clamping devices 11 are mounted to maintain the required stability and to restrict any angular motion of head 1 relative to its support 6. To establish the gas films between support base 6 and exposure head 1 and between head 1 and plate 3, pressurized fluid is supplied thro...