Method of separating strengthened glass

Abstract

A method is provided for separating or dividing strengthened glass articles, particularly strengthened glass sheets, into at least two pieces, one of which has a predetermined shape and / or dimension. A flaw is initiated in the glass at a depth that is greater than the depth of the strengthened surface layer of the glass, and a vent extending from the flaw is created at a vent depth that is greater than the depth of and outside the strengthened surface layer to at least partially separate the glass. In one embodiment, the vent is generated by treating the glass with a laser to heat the glass to a temperature in a range from about 50 DEG C below the strain point of the glass up to a temperature between the strain point and the anneal point of the glass. A glass article having at least one strengthened surface and at least one edge having an average edge strength of at least 200 MPa is also described.

Description

[0001] Related Application Cross Reference [0002] This application claims priority to US Application Serial No. 12 / 388935, filed February 19, 2009. Background technique [0003] Introducing a surface compressive stress profile into glass is a well known method of strengthening glass. Specifically, glass can be chemically strengthened by thermal tempering or ion exchange to introduce residual stress into the glass. Chemical strengthening by ion exchange involves exposing a glass containing alkali metal ions to a molten salt bath that contains more alkali metal ions than would otherwise be contained in the glass. Due to the chemical potential difference, some ions in the glass are replaced by larger ions to form a larger volume layer, which generates compressive stress in the surface of the glass, thereby compensating for the internal tensile stress, thereby maintaining the balance of the acting force. [0004] Although thermal tempering or chemical strengthening makes the g...

AI Technical Summary

Problems solved by technology

[0004] Although thermal tempering or chemical strengthening makes the glass strong and resistant to damage, residual stresses within the glass make cutting or separating chemically strengthened glass difficult

Specifically, mechanical scribing for cutting strengthened glass having a strengthening layer thickness greater than about 20 microns and a compressive stress greater than about 400 MPa often results in uncontrolled crack propagation and, in some cases, shattering of the glass

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