Sapphire component with residual compressive stress

• US 9,623,628 B2
• Filed: 01/10/2013
• Issued: 04/18/2017
• Est. Priority Date: 01/10/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Kwong, Kelvin
• Primary Examiner(s): Kornakov, Michael
• Assistant Examiner(s): Qi, Hua
• Application Number:
  US13/738,200
• Publication Number:
  US 20140193606A1
• Time in Patent Office: 1,559 Days
• Field of Search: 117 3
• CPC Class Codes: B32B 3/266 characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
• CPC Class Codes: C04B 41/0036 Laser treatment working by laser beam B23K26/00
• CPC Class Codes: C04B 41/0081 characterised by the subsequent cooling step
• CPC Class Codes: C30B 29/20 Aluminium oxides
• CPC Class Codes: C30B 33/02 Heat treatment C30B33/04, C30B33/06 take precedence
• CPC Class Codes: H04M 1/0266 for a display module assembly
• CPC Class Codes: H04M 1/185 Improving the rigidity of the casing or resistance to shocks
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 428/24331 including nonapertured component
• CPC Class Codes: Y10T 428/24992 Density or compression of components

Abstract

A method comprises shaping an aluminum oxide ceramic material into a component for an electronic device. The component has first and second major surfaces. A selected region of one or both of the first and second major surfaces is heated to an annealing temperature. The selected region is then cooled below the annealing temperature, so that residual compressive stress is generated in the selected region.

Claims

1. A method comprising:

shaping a sapphire material into a sapphire component for an electronic device, the sapphire component having first and second major surfaces;

heating a selected region of one or both of the first and second major surfaces of the sapphire component to an annealing temperature that alters a chemical or physical property of the selected region, the annealing temperature being above 700°

C. and below 2030°

C.; and

quenching the selected region of the sapphire component below the annealing temperature by introducing a fluid to the selected region that cools the selected region at a higher rate as compared to a non-quenched cooling rate, such that residual compressive stress is generated in the selected region of the sapphire component;

wherein;

the selected region of the sapphire component having the generated residual compressive stress comprises a depth less than a thickness of the sapphire component; and

the sapphire component further comprises an untreated region positioned adjacent the selected region on the first major surface of the sapphire component.

2. The method of claim 1, further comprising assembling the sapphire component into the electronic device.

3. The method of claim 1, wherein shaping the sapphire material comprises forming the sapphire component with a substantially single crystal plane orientation between the first and second major surfaces.

4. The method of claim 3, wherein the selected region of the sapphire component is prone to impact when assembled into the electronic device.

5. The method of claim 4, wherein the sapphire component forms a cover glass for the electronic device, and the selected region of the sapphire component comprises a corner portion of the cover glass, when the sapphire component is assembled into the electronic device.

6. The method of claim 5, wherein the selected region of the sapphire component excludes a central portion of the cover glass, when the sapphire component is assembled into the electronic device.

7. The method of claim 6, wherein the selected region of the sapphire component comprises at least a portion of each of the first and second major surfaces.

8. The method of claim 1, wherein the selected region of the sapphire component excludes one of the first and second major surfaces.

9. The method of claim 1, further comprising defining a failure pattern in the sapphire component, based on the residual compressive stress generated in the selected region.

10. The method of claim 1, wherein heating the selected region of the sapphire component comprises laser heating one or both of the first and second major surfaces, in the selected region.

11. The method of claim 10, wherein cooling the selected region of the sapphire component comprises directing a jet of cooling fluid onto one or both of the first and second major surfaces, in the selected region.

12. The method of claim 11, wherein a substantially single crystal plane orientation is maintained between the first and second major surfaces of the sapphire component, throughout heating and cooling of the selected region.

13. The method of claim 12, wherein the sapphire component further comprises an inner portion positioned between the first and second major surfaces of the sapphire component, the inner portion comprising the substantially single crystal plane orientation.

14. The method of claim 10 further comprising depositing a surface coating over one or both of the first and second major surfaces of the selected region of the sapphire component prior to the laser heating one or both of the first and second major surfaces of the selected region of the sapphire component.

15. The method of claim 14, wherein the laser heating of one or both of the first and second major surfaces of the selected region further comprises:

removing the deposited surface coating from one or both of the first and second major surfaces of the selected region.

16. The method of claim 1, wherein the depth of the selected region of the sapphire component is within a range of approximately 1% of the thickness of the sapphire component and 10% of the thickness of the sapphire component.

17. The method of claim 1, wherein the quenching of the selected region of the sapphire component comprises cooling the selected region of the sapphire component such that the selected region of the sapphire component maintains a substantially single crystal plane orientation.

18. A method comprising:

shaping a sapphire material into a sapphire component for an electronic device, the sapphire component having first and second major surfaces;

heating the sapphire material to an annealing temperature that is within a range of between 700°

C. to 2030°

C.; and

forming a residual compressive stress in a selected region of the sapphire component by quenching the selected region of the sapphire component using a fluid that cools the selected region below the annealing temperature at an accelerated cooling rate that is greater than an unquenched cooling rate without the fluid, the selected region of the sapphire component having greater residual compressive stress than an untreated region of the sapphire component in which the residual compressive stress is not induced;

wherein;

the selected region of the sapphire component comprises a depth less than a thickness of the sapphire component; and

the untreated region of the sapphire component is positioned below the selected region, within the sapphire component.

19. The method of claim 18, wherein the selected region of the sapphire component comprises an aperture for an audio device.

20. The method of claim 18, wherein the sapphire component is positioned adjacent a display of the electronic device.

21. The method of claim 20, wherein the first major surface of the sapphire component is positioned adjacent the display and oriented toward an interior of the electronic device.

22. The method of claim 20, wherein the second major surface of the sapphire component is positioned opposite the display and oriented toward an exterior of the device.

23. The method of claim 20, wherein the display is visible through the sapphire component.

24. A method comprising:

heating a selected region of at least one surface of a sapphire component for an electronic device to an annealing temperature that is less than 2030°

C. and greater than 700°

C., the selected region exhibiting a material toughness distinct from an untreated region of the sapphire component based on the annealing temperature altering a chemical or physical property of the selected region;

quenching the selected region of the sapphire component below the annealing temperature such that a differential cooling rate is generated between the selected region and the untreated region of the sapphire component that is not subject to the quenching; and

creating a residual compressive stress in the selected region of the sapphire component, the generated residual compressive stress created in the selected region of the sapphire component comprises a depth less than a thickness of the sapphire component;

wherein

the selected region of the sapphire component is substantially surrounded by the untreated region of the sapphire component.

25. The method of claim 24, wherein the untreated region of the sapphire component comprises a compressive stress less than the residual compressive stress created in the selected region of the sapphire component.

26. The method of claim 24, wherein the untreated region is formed on:

the at least one surface of the sapphire component comprising the selected region; and

on at least one distinct surface, distinct from the at least one surface of the sapphire component comprising the selected region.

27. The method of claim 24, wherein the creating of the residual compressive stress in the selected region of the sapphire component further comprises creating the residual compressive stress in the selected region comprising at least a portion of a second surface of the sapphire component, the second surface distinct from the first surface.