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Material and Method for Overcoating Gas Panel Substrates

IP.com Disclosure Number: IPCOM000081349D
Original Publication Date: 1974-May-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

McCarthy, DJ: AUTHOR [+3]

Abstract

In fabrication of a gaseous discharge display device, a conductor array is formed on a glass substrate and a glass slurry deposited over the conductor array. The assembly is then placed in an oven and the slurry reflowed to provide a uniform film of dielectric, insulating the conductor array from direct contact with the gas. The assembly requires that the dielectric be compatible with the glass substrate in factors such as the coefficient of expansion, etc. However, even utilizing compatible glasses, a curling of the edges of the substrate may occur during the dielectric reflow cycle. Such curling is undesirable, since it adversely affects both magnitude and uniformity of the chamber gap that can be obtained in a completed panel.

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Material and Method for Overcoating Gas Panel Substrates

In fabrication of a gaseous discharge display device, a conductor array is formed on a glass substrate and a glass slurry deposited over the conductor array. The assembly is then placed in an oven and the slurry reflowed to provide a uniform film of dielectric, insulating the conductor array from direct contact with the gas. The assembly requires that the dielectric be compatible with the glass substrate in factors such as the coefficient of expansion, etc. However, even utilizing compatible glasses, a curling of the edges of the substrate may occur during the dielectric reflow cycle. Such curling is undesirable, since it adversely affects both magnitude and uniformity of the chamber gap that can be obtained in a completed panel.

While the exact cause of this curling is not fully understood, one theory is that curling of the substrate is caused by surface tension forces in the substrate glass during reflow of the dielectric. The substrate glass behaves as a liquid during reflow, and attempts to conform to a minimum surface energy configuration with the resultant tendency to curl from the setter plate on which it rests during the oven cycle to minimize this high-energy interface

Applying a dielectric which lowers the interface energy on the upper surface of the substrate will further accentuate this tendency and, further, dielectrics with high-surface tension will exhibit greater curling characteristics than dielectrics with low-surface tension. Among the oxides normally present in glasses, lead oxide and barium oxide show the greatest tendency toward lower surface tension, while aluminum oxide shows the greatest tendency to increase surface tension.

In order to prevent curling under this theory, it is necessary to impart a high surface energy interface to the top of the substrate glass. For example, coating the entire top...