# US 10,766,810 B2 · Targeted chemical strengthening of glass articles

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- Number: US 10,766,810 B2
- Document ID: US10766810B2
- Status: Granted
- Kind: B2
- Application number: 15/890,260
- Filed: 2018-02-06
- Published: 2019-04-04
- Granted: 2020-09-08
- Earliest claimed: 2017-09-29
- Assignees: Apple Inc.
- Applicants: Apple Inc.
- Inventors: Victor Luzzato; Tyler A. Marshall; Christopher C. Bartlow; Dale N. Memering
- Web page: https://patentgrep.com/patent/US10766810B2

## CPC

- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- B28D 1/18: by milling, e.g. channelling by means of milling tools
- C03B 23/0302: {between opposing full-face shaping moulds}
- C03C 15/00: Surface treatment of glass, not in the form of fibres or filaments, by etching (etching or surface-brightening compositions, in general C09K13/00)
- C03C 19/00: Surface treatment of glass, not in the form of fibres or filaments, by mechanical means (sand-blasting, grinding, or polishing glass B24)
- C03C 2204/08: Glass having a rough surface
- C03C 2218/34: Masking
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- B28D: WORKING STONE OR STONE-LIKE MATERIALS
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## Abstract

Components of an electronic device, such as glass articles, are susceptible to breakage, especially in regions where machining a glass article has created flaws. Chemical strengthening can be performed to create deeper compression layers at regions of a glass article that have been machined, include and/or are adjacent to an edge feature, have greater surface roughness, and/or have more or deeper cracks.

## Claims

### Claim 1

A glass article for an electronic device, the glass article comprising:
a first region having a first surface roughness, wherein the first region defines a first compression layer having a first depth, wherein the first surface roughness has a corresponding surface roughness parameter Ra that is greater than 10 μm; and
a second region having a second surface roughness less than the first surface roughness, wherein the second region defines a second compression layer having a second depth less than the first depth.

### Claim 2 (depends on 1)

The glass article of claim 1, wherein the first region includes an edge comprising a chamfer, curve, spline curve, s-curve, bevel, fillet, radius, or taper.

### Claim 3 (depends on 1)

The glass article of claim 1, wherein the first region includes an edge at a periphery of an opening that extends through the glass article.

### Claim 4 (depends on 1)

The glass article of claim 1, wherein the glass article comprises: a front surface; and
a back surface, wherein the first region includes an edge at a transition between the front surface to the back surface.

### Claim 5 (depends on 1)

The glass article of claim 1, wherein a thickness of the glass article is uniform across at least a portion of the first region and at least a portion of the second region.

### Claim 6 (depends on 1)

The glass article of claim 1, wherein the first and second compression layers each have a greater density of alkali metal ions than other portions of the glass article.

### Claim 7 (depends on 1)

The glass article of claim 1, wherein the first depth is greater than a depth of a crack extending from a surface of the first region.

### Claim 8 (depends on 1)

The glass article of claim 1, wherein the first depth is greater 50 μm and the second depth is less than 50 μm.

### Claim 9

A method of strengthening a glass article for an electronic device, the method comprising:
applying a mask to a glass article having a first region and a second region, the first region having a first surface roughness and the second region having a second surface roughness less than the first surface roughness, wherein the first region includes an edge and the mask covers the second region, wherein the first surface roughness has a corresponding surface roughness parameter Ra that is greater than 10 μm;
forming a first compression layer in the first region by chemically strengthening the first region;
removing the mask; and
forming a second compression layer in the second region by chemically strengthening the second region, wherein the first compression layer has a first depth and the second compression layer has a second depth less than the first depth.

### Claim 10 (depends on 7)

The method of claim 7, further comprising, prior to applying the mask, machining the first region of the glass article to form the edge.

### Claim 11 (depends on 7)

The method of claim 7, further comprising:
prior to applying the mask, heating the glass article having opposing first and second surfaces and a third surface connecting the first and second surfaces;
applying a press mold to the glass article to form the edge at the first surface or the second surface and to form an elongated portion at the third surface; and
removing the elongated portion from the third surface such that the third surface is substantially flat.

### Claim 12 (depends on 7)

The method of claim 7, further comprising:
prior to applying the mask, heating the glass article; and
applying a press mold to the glass article to form curved surfaces on the glass article.

### Claim 13 (depends on 12)

The method of claim 12, wherein the curved surfaces comprise a concave portion on a first side of the glass article and a convex portion on a second side of the glass article, the second side being opposite the first side.

### Claim 14 (depends on 7)

The method of claim 7, wherein the first and second compression layers each have a greater density of alkali metal ions than other portions of the glass article.

### Claim 15 (depends on 7)

The method of claim 7, further comprising, while forming the second compression layer in the second region, enlarging the first compression layer in the first region.

### Claim 16

A glass article for an electronic device, the glass article comprising:
a first region, wherein the first region defines a first compression layer having a first depth and a first surface roughness having a corresponding surface roughness parameter Ra that is greater than 10 μm; and
a second region, wherein the second region defines a second compression layer having a second depth less than the first depth and having a second surface roughness less than the first surface roughness,
wherein the glass article has a uniform thickness across the first region and the second region.

### Claim 17 (depends on 16)

The glass article of claim 16, further comprising an edge adjacent to a portion of the first region that has the uniform thickness.

### Claim 18 (depends on 17)

The glass article of claim 17, wherein the edge is disposed at a periphery of an opening that extends through the glass article.

### Claim 19 (depends on 16)

The glass article of claim 16, wherein the first and second compression layers each have a greater density of alkali metal ions than other portions of the glass article.