Strengthened glass articles having improved survivability

A strengthened glass article comprising:

• a thickness t≦1 mm, an inner region under a central tension CT, and at least one compressive stress layer adjacent the inner region and extending within the strengthened glass article from a surface of the strengthened glass article to a depth of layer DOL, wherein the strengthened glass article is under a compressive stress at the surface CSs,
• wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0-5 mol % Li2O, at least 3 mol % Al2O3, and at least 5 mol % Na2O, and
• wherein the DOL≧70 μm, a CSs/DOL ratio 2.5 MPa/μm, and wherein the strengthened glass article, when subjected to a point impact sufficient to break the strengthened glass article, has a frangibility index of less than 3.

A strengthened glass article comprising:

• a thickness t≦1 mm, an inner region under a central tension CT, and at least one compressive stress layer adjacent the inner region and extending within the strengthened glass article from a surface of the strengthened glass article to a depth of layer DOL, wherein the strengthened glass article is under a compressive stress at the surface CSs,
• wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0-5 mol % Li2O, at least 3 mol % Al2O3, and at least 5 mol % Na2O, and
• wherein the DOL≧70 μm, a CSs/DOL ratio≧3.0 MPa/μm, and the CT≦150 MPa.

A strengthened glass, the strengthened glass having an inner region under a central tension CT, and at least one compressive stress layer under a compressive stress CS, the compressive stress layer extending from a surface of the glass to a depth of compression and being adjacent to the inner region, wherein the strengthened glass has at least a 60% survival rate when dropped in a drop test from a height of at least 100 cm onto a drop surface utilizing a uniform drop testing procedure.

A method of producing a strengthened glass article having a thickness t≦1 mm and at least one compressive stress layer extending from a surface of the strengthened glass article to a depth of layer DOL≧70 μm, the method comprising:

• conducting a first ion exchange step by immersing an alkali aluminosilicate glass article in a first ion exchange bath at a temperature of greater than 400° C. for a time sufficient such that the compressive stress layer has a depth of at least 70 μm after the first ion exchange step;
• and
• optionally conducting a second ion exchange step by immersing the alkali aluminosilicate glass article in a second ion exchange bath different from the first ion exchange bath at a temperature of at least 350° C. for a time sufficient to produce the compressive layer having DOL≧90 μm.