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Surface Flatness Inspection Device

IP.com Disclosure Number: IPCOM000084800D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Weil, JM: AUTHOR

Abstract

Printed-circuit panels of the type employing laminated layers of copper and glass-epoxy combinations frequently show "dimpling" or surface waviness after the lamination process. The present arrangement provides an inspection device that discloses these defects quickly and easily to the naked eye.

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Surface Flatness Inspection Device

Printed-circuit panels of the type employing laminated layers of copper and glass-epoxy combinations frequently show "dimpling" or surface waviness after the lamination process. The present arrangement provides an inspection device that discloses these defects quickly and easily to the naked eye.

In its fundamental form the device comprises an optical diffraction grating that is placed on top of the surface to be inspected. The grating, in very close contact with the surface, covers the entire area to be inspected. One type of grating which can be used is a sheet of clear photoglass with closely spaced black lines; however, the grating characteristics are chosen so that suitable moire patterns define the contour, and to a certain extent the depth of the flatness anomalies found in the panel.

A preferred arrangement of the manner in which the inspection can be carried out is shown in the drawings wherein Fig. 1 illustrates the rectangular configuration which is found in the arrangement, with a broken out sectional view of one corner at AA, this broken out section being shown enlarged in Fig. 2. The laminated panel 3 which is to be inspected is supported by a suitable thickness of resilient material 5, such as foamed polyurethane, on a rigid support or table 7. Overlying the laminated panel 3, is a rectangular slab of photoglass 9, for example, with a ruled grating 11 provided on the bottom or contacting surface. The resilient sup...