METHOD OF SEPARATING STRENGTHENED GLASS

• US 20100291353A1
• Filed: 07/28/2010
• Published: 11/18/2010
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Streltsov, Alexander Mikhailovich, Dejneka, Matthew John, Gross, Timothy Michael, Gomez, Sinue, Harvey, Daniel R.
• Granted Patent: US 8,341,976 B2
• Time in Patent Office: Days
• US Class Current: 428/192
• CPC Class Codes: C03B 33/0222 Scoring using a focussed radiation beam, e.g. laser
• CPC Class Codes: C03B 33/04 Cutting or splitting in curves, especially for making spectacle lenses
• CPC Class Codes: C03B 33/091 using at least one focussed radiation beam, e.g. laser beam C03B33/0955 takes precedence
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 3/091 containing aluminium
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: Y02P 40/57 Improving the yield, e-g- reduction of reject rates
• CPC Class Codes: Y10T 225/12 With preliminary weakening
• CPC Class Codes: Y10T 428/24777 Edge feature
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A method of cutting a glass sheet that has been thermally or chemically strengthened along a predetermined line, axis, or direction with high speed and with minimum damage on the cut edges. The strengthened glass sheet may be an aluminoborosilicate glass material having at least one alkali metal oxide modifier, and the ratio

$\frac{{\mathrm{Al}}_2O_3\left(\mathrm{mol}\%\right)+B_2O_3\left(\mathrm{mol}\%\right)}{\sum \mathrm{modifiers}\left(\mathrm{mol}\%\right)}>1.$

At least one damage line is formed within the strengthened glass sheet. The at least one damage line is formed outside the strengthened compressive stress surface layers and within the tensile stress layer of the strengthened glass sheet. The at least one damage line may be formed by laser treatment. A crack is initiated in the strengthened glass sheet and propagated along the at least one damage line to separate the strengthened glass sheet along the predetermined line, axis, or direction into at least two pieces.

Claims

1. A method of separating a strengthened glass sheet, the method comprising:

providing the strengthened glass sheet, the strengthened glass sheet having a first surface and a second surface, wherein;

each of the first surface and the second surface has a strengthened surface layer under a compressive stress and extending from the surface to a depth of layer, and a central region under tensile stress; and

the strengthened glass sheet comprises an aluminoborosilicate glass material having at least one alkali metal oxide modifier, and the ratio

2. The method of claim 1, wherein forming the at least one damage line comprises forming at least one laser-induced damage line in the central region.

3. The method of claim 2, wherein the at least one damage line is formed by irradiating the strengthened glass sheet with a nanosecond pulsed laser.

4. The method of claim 3, wherein the nanosecond pulsed laser is operated at a power of less than about 4 W.

5. The method of claim 1, wherein forming the at least one damage line in the central region comprises forming a first damage line and a second damage line in the central region, the second damage line being located between the strengthened surface layer of the first surface and the first damage line, the first damage line and the second damage line defining a plane perpendicular to the first surface and the second surface.

6. The method of claim 1, wherein the strengthened surface layers of the first surface and the second surfaces are chemically strengthened surfaces.

7. The method of claim 1, wherein the strengthened surface layers are ion exchanged chemically strengthened surfaces.

8. The method of claim 7, wherein the strengthened surface layers of the first surface and the second surfaces have a compressive stress of at least about 400 MPa, the depth of layer is at least about 15 μ

m, and the central region has a tensile stress greater than about 15 MPa.

9. The method of claim 7, wherein the aluminoborosilicate glass material comprises:

60-72 mol % SiO₂;

9-16 mol % Al₂O₃;

5-12 mol % B₂O₃;

8-16 mol % Na₂O; and

0-4 mol % K₂O.

10. The method of claim 1, wherein

11. The method of claim 1, wherein the strengthened glass sheet has a Vickers median/radial crack initiation threshold of at least 10 kgf.

12. A method of separating a strengthened glass sheet, the method comprising:

providing the strengthened glass sheet, the strengthened glass sheet having a first surface and a second surface, wherein;

each of the first surface and the second surface have a strengthened surface layer under a compressive stress and extending from the surface to a depth of layer, and a central region under a tensile stress; and

the strengthened glass sheet comprises an aluminoborosilicate glass material having at least one alkali metal oxide modifier, and the ratio

13. The method of claim 12, wherein the first and second laser-induced damage lines are formed by irradiating the strengthened glass sheet with a nanosecond pulsed laser.

14. The method of claim 13, wherein the nanosecond pulsed laser is operated at a power of less than about 4 W.

15. The method of claim 12, wherein the strengthened surface layers are ion exchanged chemically strengthened surfaces.

16. The method of claim 15, wherein the strengthened surface layers of the first surface and the second surfaces have a compressive stress of at least about 400 MPa, the depth of layer is at least about 15 μ

m, and the central region has a tensile stress greater than about 15 MPa.

17. The method of claim 16, wherein the aluminoborosilicate glass material comprises:

60-72 mol % SiO₂;

9-16 mol % Al₂O₃;

5-12 mol % B₂O₃;

8-16 mol % Na₂O; and

0-4 mol % K₂O.

18. The method of claim 12, wherein

19. A strengthened glass article comprising:

a first surface and a second surface, wherein;

each of the first surface and the second surface has an ion exchanged strengthened surface layer under a compressive stress and extending from the surface to a depth of layer, and a central region under a tensile stress, and a central region under a tensile stress; and

the strengthened glass sheet comprises an aluminoborosilicate glass material having at least one alkali metal oxide modifier, and the ratio

20. The strengthened glass article of claim 19, wherein:

the aluminoborosilicate glass material comprises;

60-72 mol % SiO₂;

9-16 mol % Al₂O₃;

5-12 mol % B₂O₃;

8-16 mol % Na₂O; and

0-4 mol % K₂O;

the ion exchanged strengthened surface layers of the first surface and the second surfaces have a compressive stress of at least about 400 MPa and the depth of layer is at least 15 μ

m; and

the strengthened glass sheet has a Vickers median/radial crack initiation threshold of at least 10 kgf.