Electronic device having selectively strengthened glass
Embodiments disclosed therein generally pertain to selectively strengthening glass. More particularly, techniques are described for selectively strengthening cover glass, which tends to be thin, for electronic devices, namely, portable electronic devices.
1. A portable electronic device comprising:
a display;
a touch sensing device positioned over the display; and
an enclosure enclosing the display and the touch sensing device, the enclosure including a glass member comprising:
a central portion positioned over the display and defining:
a central front surface having a central front compressive stress region and a central rear surface having a central rear compressive stress region, the central front compressive stress region extending to a first depth from the central front surface and the central rear compressive stress region extending to a second depth from the central rear surface; and
a peripheral portion at least partially surrounding the central portion and defining:
a peripheral front surface having a peripheral front compressive stress region and a peripheral rear surface having a peripheral rear compressive stress region, of the peripheral front compressive stress region extending to a third depth, greater than the first depth, from the peripheral front surface and the peripheral rear compressive stress region extending to a fourth depth from the peripheral rear surface that is greater than the second depth.
2. The portable electronic device of claim 1 , wherein:
the peripheral front compressive stress region has a peak compressive stress greater than a peak compressive stress of the central front compressive stress region.
3. The portable electronic device of claim 1 , wherein:
the peripheral front compressive stress region has a peak compressive stress about equal to a peak compressive stress of the central front compressive stress region.
4. The portable electronic device of claim 1 , wherein a length of the central portion along the central front surface is greater than a length of the peripheral portion along the peripheral front surface.
5. The portable electronic device of claim 1 , wherein the peripheral portion surrounds the central portion.
6. The portable electronic device of claim 1 , wherein a thickness of the glass member is less than 3 microns.
7. The portable electronic device of claim 1 , wherein:
the glass member is a glass sheet;
the enclosure further includes a housing defining an opening; and
the glass sheet is positioned over the opening and coupled to the housing.
8. A portable electronic device comprising:
a display;
a touch sensing device positioned over the display; and
a glass member at least partially enclosing the display and the touch sensing device and comprising:
a first portion positioned over the display and the touch sensing device and defining a first front surface and a first rear surface, the first front surface having a first compressive stress region extending to a first depth from the first front surface and the first rear surface having a second compressive stress region extending to a second depth from the first rear surface; and
a second portion adjacent to the first portion and defining a second front surface and a second rear surface, the second front surface having a third compressive stress region extending to a third depth, greater than the first depth, from the second front surface and having a peak compressive stress greater than a peak compressive stress of the first compressive stress region and the second rear surface having a fourth compressive stress region extending to a fourth depth, greater than the second depth.
9. The portable electronic device of claim 8 , wherein the second portion of the glass member further comprises a peripheral edge surface having a fifth compressive stress region extending to a fifth depth substantially equal to the third second depth.
10. The portable electronic device of claim 9 , wherein the second portion extends 2 mm to 10 mm from the peripheral edge surface.
11. The portable electronic device of claim 9 , wherein:
the peripheral edge surface defines four sides of the glass member; and
the first portion is positioned inward of the peripheral edge surface.
12. The portable electronic device of claim 9 , wherein the first portion and the second portion together span a width of the glass member.
13. The portable electronic device of claim 8 , wherein a distance between the first front surface and the first rear surface is about equal to a distance between the second front surface and the second rear surface.
14. The portable electronic device of claim 8 , wherein the third depth is greater than the first depth by at least 20 microns.
15. An electronic device comprising:
a display;
a touch sensitive layer; and
a chemically strengthened glass member positioned over the display and the touch sensitive layer, defining a front surface and a rear surface, and comprising:
a first portion positioned over the display and including:
a first compressive stress region along the front surface and having:
a first peak compressive stress; and
a first depth from the front surface; and
a second compressive stress region along the rear surface and having:
a second peak compressive stress that is about equal to the first peak compressive stress; and
a second depth, less than the first depth, from the rear surface; and
a second portion adjacent the first portion and including:
a third compressive stress region along the front surface and having a third depth, greater than the first depth, from the front surface; and
a fourth compressive stress region along the rear surface and having a fourth depth, greater than the second depth, from the rear surface.
16. The electronic device of claim 15 , wherein:
the chemically strengthened glass member further defines a peripheral edge surface; and
the chemically strengthened glass member further comprises a fifth compressive stress region extending along the peripheral edge surface and having a fifth depth that is substantially equal to the third depth and the fourth depth.
17. The electronic device of claim 16 , wherein the chemically strengthened glass member has:
a first central tension between the first compressive stress region and the second compressive stress region; and
a second central tension, greater than the first central tension, between the third compressive stress region and the fourth compressive stress region.
18. The electronic device of claim 15 , wherein the first compressive stress region is substantially uniform across a central portion of the front surface.
19. The electronic device of claim 18 , wherein the second compressive stress region is substantially uniform across a central portion of the rear surface.
20. The electronic device of claim 15 , wherein the chemically strengthened glass member comprises an aluminosilicate glass and each of the first compressive stress region and the second compressive stress region includes potassium ions.