Corning Incorporated
Laminated glass article with low compaction and method for forming the same

Abstract:

A strengthened glass article (100), such as a substrate for a p-Si based transistors, includes first and second glass cladding layers (104, 106) and a glass core layer (102) disposed therebetween. A coefficient of thermal expansion [CTE] of each cladding layer (104, 106), which can be made of the same glass, is at least 1.times.10.sup.-7.degree. C..sup.-1 less than that of the core layer (102). Each of the core and cladding layers has a strain point less than 700.degree. C. A compaction of the glass article (100) is at most about 20 ppm [see FIG. 1]. A method includes forming a glass article and/or heating a glass article to a first temperature of at least about 400.degree. C. The glass article has a glass core layer (102) and a glass cladding layer (104, 106) adjacent to the core layer. The glass article is maintained at a temperature within a range of from 400.degree. C. to 600.degree. C. for a holding period from 30 to 90 minutes and subsequently cooled to a temperature of at most 50.degree. C. over a cooling period from 30 seconds to 5 minutes. The glass article (100) for heat strengthening may have been produced by the fusion overflow down draw process, e.g. as depicted in FIG. 3.