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Elimination of Sag During Exposure of Glass Masters

IP.com Disclosure Number: IPCOM000037606D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Japp, RM: AUTHOR [+2]

Abstract

Gravitational sag of edge-supported glass master can be eliminated by using an air pressure differential across the master to enable closer undistorted proximity exposure during circuitization processing.

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Elimination of Sag During Exposure of Glass Masters

Gravitational sag of edge-supported glass master can be eliminated by using an air pressure differential across the master to enable closer undistorted proximity exposure during circuitization processing.

In Fig. 1, glass master 1, a phototool for exposing sensitized workpiece 2, serves as the bottom member of an evacuated chamber, formed with a top sheet 3 of quartz or fused silica glass and air-tight sidewalls 4. Evacuation occurs through duct 5 to produce a negative pressure sufficient to counterpart any sag in the glass master 1. Particulate contamination falling on the top glass 3 will not print defects because of the long distance to the workpiece surface.

An alternative arrangement is shown in Fig. 2 in which an illumination source 6 and sensitized workpiece 2 are within different controlled pressure compartments separated by glass master 1. An air-tight chamber 7 is divided into two compartments 7a and 7b by glass master 1 joined at its edges by seals 8 to the vertical chamber walls. Chamber 7a is supplied with filtered cooling air through duct 9 and some of the cooling air is diverted to pump 10 that supplies air through duct 11 to chamber 7b at a pressure higher by approximately one-half inch of water. Each compartment has restrictive vents to maintain the desired difference in air pressure and flatten glass master 1.

Disclosed anonymously.

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