Browse Prior Art Database

Art Work Exposure Method for Supply Planes

IP.com Disclosure Number: IPCOM000079993D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Hall, DE: AUTHOR [+3]

Abstract

Ground and voltage planes for printed-circuit panels are exposed first through a standard glass master to produce a latent image of clearance holes, and then through a special aperture to produce selected connections. This method eliminates manual opaquing of connections, improves accuracy, and reduces cost.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 98% of the total text.

Page 1 of 2

Art Work Exposure Method for Supply Planes

Ground and voltage planes for printed-circuit panels are exposed first through a standard glass master to produce a latent image of clearance holes, and then through a special aperture to produce selected connections. This method eliminates manual opaquing of connections, improves accuracy, and reduces cost.

In Fig. 1, a sensitized photographic plate 1 is aligned against a three-point locating fixture 2 and exposed through a standard glass master 3 having all clearance holes 4, borders, manufacturing lands, inspection targets and test patterns, as required. Sensitized plate 1 is to be a positive pattern, that is, opaque where copper is to be present on the final product. The resulting latent image is not developed but is to be again exposed.

Exposed plate 1 is next placed against a three-point fixture 2 of Fig. 2 and exposed for connections at desired points of latent clearance holes 5. Exposure may be done with a special aperture on a photoplotting table. The special apertures or configurations form a ring land connected in four places to the surrounding plane. The remaining partial ring provides a guide, making inspection of connections easier as well as locating all plated through-holes in case of subsequent change activity. Plate 1 is then developed so that openings 5 and ring land 7 appear as in Fig. 3. (Plate 1 is illustrated as only partially exposed at hole locations.)

1

Page 2 of 2

2

[This page contains 3 pictur...