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Detection of Defects in Metallized Glass Panels

IP.com Disclosure Number: IPCOM000083089D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 39K

Publishing Venue

IBM

Related People

d'Heurle, FM: AUTHOR [+2]

Abstract

In the fabrication of gas discharge display device panels, vacuum deposited metal films on the surface of plate-glass substrates are required to be etched into long metal lines. Many lines turn out to be discontinuous because of defects in the metal films. Some of the defects are inherent to the films themselves, while others originate in the glass substrate. This apparatus is directed to the detection, localization and measurement of such defects.

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Detection of Defects in Metallized Glass Panels

In the fabrication of gas discharge display device panels, vacuum deposited metal films on the surface of plate-glass substrates are required to be etched into long metal lines. Many lines turn out to be discontinuous because of defects in the metal films. Some of the defects are inherent to the films themselves, while others originate in the glass substrate. This apparatus is directed to the detection, localization and measurement of such defects.

Three separate illumination techniques are employed for defect detection. As shown in the figure, to detect pinholes, and the like, in the metal film, glass panel 1 is illuminated in transparency by light emanating from source 3 via diffuser 5. Fiber optic scan assembly 7 traverses the metal film in the X direction, on rod 9. As can be seen, the X-scan covers the width of the panel.

Line-by-line scanning is achieved by incrementing plate 1 in the Y direction at the end of each X line scan. Movement in the Y direction is achieved by incrementing panel holders 11 and 13 on slider rods 15 and 17. If desired, after scanning in the X direction, scanning in the Y direction may also be carried out.

As shown, photomultiplier 19 is coupled to scan assembly 7 via fiber optical bundle 21. Photomultiplier 19 acts to produce signals in response to light transmitted via pinholes, and the like, in the scanned metal film. The signals are stored, and may be averaged to give a measure of the average density of holes. By synchronization of the high values of X and Y signals, the X-Y coordinates of the larger pinholes may be determined.

It is also important to determine defects in the plate-glass substrate which may act to cause defects in the metal film. To achieve this, edge illumination is empl...