Strengthening variable thickness glass

Patent metadata

Field	Value
Publication number	US-10781135-B2
Application number	US-201113235036-A
Country	US
Kind code	B2
Filing date	Sep 16, 2011
Priority date	Mar 16, 2011
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

Apparatus, systems and methods for increasing the strength of glass are disclosed. The use of multi-bath chemical processing for a glass article can facilitate controlled chemical strengthening. Through multi-bath (or multi-step) chemical processing, differing levels of strengthening can be achieved for different portion of glass articles. The multi-bath chemical processing can be achieved through the use of successive chemical baths. Accordingly, glass articles that have undergone multi-bath chemical processing are able to be not only thin but also sufficiently strong and resistant to damage. The strengthened glass articles are well suited for use in consumer products, such as consumer electronic devices (e.g., portable electronic devices). In one embodiment, the glass member can pertain to a glass cover for a housing of an electronic device.

First claim

What is claimed is:

1. A method for chemically strengthening a piece of glass for use as a cover for an electronic device, the method comprising:
providing a piece of glass, the piece of glass having:
a first portion defining a middle region of a substantially planar top surface of the piece of glass and having a first thickness that is between 0.2 mm and 0.4 mm thick; and
a second portion defining a side region along a periphery of the substantially planar top surface of the piece of glass and having a second thickness that is between 0.6 mm and 1.0 mm thick;

applying a mask to the first portion of the piece of glass;
chemically strengthening the second portion of the piece of glass by placing the piece of glass in a first bath;
subsequently removing the mask from the first portion of the piece of glass;
chemically strengthening the first portion and the second portion of the piece of glass by placing the piece of glass in a second bath, such that:
the chemically strengthened first portion has a first depth of layer of between 30 microns and 40 microns; and
the chemically strengthened second portion has a second depth of layer of between 50 microns and 60 microns; and

positioning the piece of glass over a display of an electronic device.

2. A method as recited in claim 1 , wherein the chemically strengthening of the first portion to the first depth of layer of between 30 microns and 40 microns provides a first predetermined characteristic to the first portion.

3. A method as recited in claim 2 , wherein the chemically strengthening of the second portion to the second depth of layer of between 50 microns and 60 microns provides a second predetermined characteristic to the second portion.

4. A method as recited in claim 3 , wherein:
the first predetermined characteristic pertains to a first central tension limit; and
the second predetermined characteristic pertains to a second-central tension limit.

5. A method as recited in claim 1 , wherein the piece of glass has a thickness of not more than about 0.6 mm.

6. A method as recited in claim 1 , wherein the first thickness is between about 20-70% of the second thickness.

7. A method for strengthening a piece of glass, the piece of glass comprising:
a first portion defining a middle region of a substantially planar first surface and having a first thickness that is between 0.2 mm and 0.4 mm thick, and
a second portion defining a side region of the substantially planar first surface and having a second thickness that is between 0.6 mm and 1.0 mm thick, the side region extending around a periphery of the middle region, the method comprising:
applying a first mask to the second portion of the piece of glass;
chemically strengthening the first portion to a first depth of layer of between 30 microns and 40 microns;
subsequently removing the first mask from the second portion;
applying a second mask to the first portion;
chemically strengthening the second portion to a second depth of layer of between 50 microns and 60 microns;
subsequently removing the second mask from the first portion; and
attaching the piece of glass to a portable electronic device to define an outer surface of the portable electronic device.

8. A method as recited in claim 7 , wherein the first thickness of the piece of glass is not more than about 0.6 mm.

9. A method as recited in claim 8 , wherein the chemically strengthening of the first portion comprises placing the piece of glass in a first potassium solution.

10. A method as recited in claim 9 , wherein the chemically strengthening of the second portion comprises placing the piece of glass in the first potassium solution or a second potassium solution.

11. A method as recited in claim 7 , wherein the first thickness is 20-70% of the second thickness.

12. A method for strengthening a piece of glass for a housing for a portable electronic device defining a substantially planar surface and having a thinner region and a thicker region, the method comprising:
applying a first mask to the thinner region of the piece of glass;
chemically strengthening the thicker region;
subsequently removing the first mask from the thinner region; and
chemically strengthening both the thinner region and the thicker region, such that;
the chemically strengthened thinner region has a first depth of layer of between 30 microns and 40 microns; and
the chemically strengthened thicker region has a second depth of layer of between 50 microns and 60 microns,

wherein the thinner region corresponds to a middle region of the substantially planar surface having a first thickness that is between 0.2 and 0.4 mm thick, and the thicker region corresponds to a side region of the substantially planar surface surrounding the thinner region and having a second thickness that is between 0.6 to 1.0 mm thick; and
attaching the piece of glass to the portable electronic device.

13. A method as recited in claim 12 , wherein the second thickness of the thicker region is not more than about 0.6 mm.

14. A method as recited in claim 12 , wherein:
the chemically strengthening of the thicker region comprises placing the piece of glass in a first potassium solution, and
the chemically strengthening of the thinner region comprises placing the piece of glass in the first potassium solution or a second potassium solution.

15. A method for processing a glass piece for use as a cover for an electronic device, the method comprising:
masking a first portion of the glass piece to block ion exchange;
submerging the glass piece in a heated ion bath to facilitate ion exchange with at least a second portion of the glass piece other than the first portion which is masked;
removing the glass piece from the heated ion bath after a first predetermined duration;
unmasking the first portion of the glass piece after removing the glass piece from the heated ion bath;
subsequently submerging the glass piece in the heated ion bath or another heated ion bath to facilitate ion exchange with at least the first portion of the glass piece; and
removing the glass piece from the heated ion bath or the another heated ion bath after a second predetermined duration; and
positioning the glass piece over a display of an electronic device,
wherein the glass piece defines a substantially planar surface having a middle region and an outer peripheral region, the first portion defines at least part of the middle region of the substantially planar surface and has a first thickness that is between 0.2 and 0.4 mm thick, the first portion has a first depth of layer of between 30 microns and 40 microns, the second portion defines at least part of the outer peripheral region of the substantially planar surface and has a second thickness that is between 0.6 to 1.0 mm thick, and the second portion has a second depth of layer of between 50 microns and 60 microns.

16. A method as recited in claim 15 , wherein the method further comprises:
performing post-processing on the glass piece following removal of the glass piece from the heated ion bath or the another heated ion bath.

17. A method as recited in claim 15 , wherein
positioning the glass piece comprises attaching the glass piece to a portable electronic device, the glass piece serving as a portion of an outer surface of a housing of the portable electronic device.

18. A method as recited in claim 15 , wherein the glass piece has a thickness of not more than about 0.6 mm.

19. A consumer electronic product, comprising:
a housing having a front surface, a back

Assignees

• Weber Douglas J
• Apple Inc

Inventors

• Weber Douglas J

Classifications

• C03C21/002 Primary

  to perform ion-exchange between alkali ions (C03C21/005 takes precedence) · CPC title