PATENT DOCUMENT

Publication Number: US-12043571-B2
Application Number: US-202218072891-A
Country: US
Kind Code: B2

Title: Electronic device having selectively strengthened glass

Abstract:
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.

Claims:
The invention claimed is: 
     
       1. A portable electronic device comprising:
 a touch-sensitive layer; and 
 an enclosure at least partially surrounding the touch-sensitive layer and comprising: 
 a housing; and 
 a glass member coupled to the housing and defining an exterior surface of the enclosure, the glass member comprising:
 an exterior compressive stress region extending from an exterior surface of the glass member to a first depth; 
 an interior compressive stress region extending from an interior surface of the glass member to a second depth; and 
 a peripheral compressive stress region extending between the exterior compressive stress region and the interior compressive stress region and extending from an edge surface of the glass member to a third depth that is greater than the first depth and the second depth. 
 
 
     
     
       2. The portable electronic device of  claim 1 , wherein:
 the exterior surface of the glass member is a first exterior surface; and 
 an exterior portion of the peripheral compressive stress region extends from a second exterior surface of the glass member. 
 
     
     
       3. The portable electronic device of  claim 2 , wherein:
 the interior surface of the glass member is a first interior surface; and 
 an interior portion of the peripheral compressive stress region further extends from a second interior surface of the glass member. 
 
     
     
       4. The portable electronic device of  claim 3 , wherein:
 the glass member further defines a peripheral tensile stress region between the exterior and interior portions of the peripheral compressive stress region; and 
 a central tension of the peripheral tensile stress region is greater than a central tension of a tensile stress region between the exterior and the interior compressive stress regions. 
 
     
     
       5. The portable electronic device of  claim 1 , wherein the first depth is substantially equal to the second depth. 
     
     
       6. The portable electronic device of  claim 1 , wherein:
 the portable electronic device further comprises a display stack; and 
 the touch-sensitive layer is included in the display stack. 
 
     
     
       7. The portable electronic device of  claim 1 , wherein:
 the exterior compressive stress region has a first peak compressive stress; 
 the interior compressive stress region has a second peak compressive stress; and 
 the peripheral compressive stress region has a third peak compressive stress that is substantially the same as the first and the second peak compressive stress. 
 
     
     
       8. A portable electronic device comprising:
 an enclosure including a glass member defining a front surface, a rear surface, and an edge surface extending between the front surface and the rear surface, the glass member comprising: 
 a front ion-exchanged layer extending from at least a portion of the front surface and defining a front compressive stress region having a first depth from the front surface; 
 a rear ion-exchanged layer extending from at least a portion of the rear surface and defining a rear compressive stress region having a second depth from the rear surface; and 
 a peripheral ion-exchanged layer extending from the edge surface and defining a peripheral compressive stress region having a third depth from the edge surface that is greater than the first depth and the second depth; and 
 a display positioned within the enclosure and below the glass member. 
 
     
     
       9. The portable electronic device of  claim 8 , wherein a peak compressive stress of the peripheral compressive stress region is greater than a peak compressive stress of the rear compressive stress region. 
     
     
       10. The portable electronic device of  claim 9 , wherein the first depth is greater than the second depth. 
     
     
       11. The portable electronic device of  claim 8 , wherein the glass member is formed of an aluminosilicate glass. 
     
     
       12. The portable electronic device of  claim 11 , wherein each of the front ion-exchanged layer, the rear ion-exchanged layer, and the peripheral ion-exchanged layer includes potassium ions. 
     
     
       13. The portable electronic device of  claim 8 , wherein the edge surface defines a rounded transition between the front surface and a side surface of the glass member. 
     
     
       14. The portable electronic device of  claim 8 , wherein:
 the enclosure further comprises a housing coupled to the glass member; and 
 the edge surface of the glass member is proximate a side surface of the housing. 
 
     
     
       15. A portable electronic device comprising:
 a camera; and 
 an enclosure at least partially surrounding the camera and including a glass member defining:
 a first compressive stress region extending along an exterior surface of the glass member and having a first depth from the exterior surface; 
 a second compressive stress region extending along an interior surface of the glass member and having a second depth from the interior surface; and 
 a third compressive stress region extending along an edge surface of the glass member and having a third depth from the edge surface that is greater than the first depth and the second depth. 
 
 
     
     
       16. The portable electronic device of  claim 15 , wherein the edge surface extends around a periphery of the glass member. 
     
     
       17. The portable electronic device of  claim 16 , wherein:
 the glass member defines an aperture surface that defines an aperture extending through the glass member; and 
 the camera is positioned adjacent the aperture. 
 
     
     
       18. The portable electronic device of  claim 17 , wherein the glass member further defines a fourth compressive stress region extending from the aperture surface to a fourth depth into the glass member. 
     
     
       19. The portable electronic device of  claim 18 , wherein the fourth depth is greater than the first depth and the second depth. 
     
     
       20. The portable electronic device of  claim 15 , wherein the glass member has a thickness less than 1 mm.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation patent application of U.S. patent application Ser. No. 16/878,393, May 19, 2020 and titled “Electronic Device Having Selectively Strengthened Glass,” which is a continuation patent application of U.S. patent application Ser. No. 15/660,839, filed Jul. 26, 2017 and titled “Electronic Device Having Selectively Strengthened Glass,” now U.S. Pat. No. 10,676,393, which is a continuation patent application of U.S. patent application Ser. No. 13/235,090, filed Sep. 16, 2011 and titled “Electronic Device Having Selectively Strengthened Glass,” now U.S. Pat. No. 9,725,359, which is a nonprovisional patent application of and claims the benefit of U.S. Provisional Patent Application No. 61/453,404, filed Mar. 16, 2011 and titled “Electronic Device Having Selectively Strengthened Glass,” the disclosures of which are hereby incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     Conventionally, small form factor devices, such as handheld electronic devices, have a display arrangement that includes various layers. The various layers include at least a display technology layer. Additionally, a sensing arrangement and/or a cover window may be disposed over the display technology layer. By way of example, the display technology layer may include or pertain to a Liquid Crystal Display (LCD) that includes a Liquid Crystal Module (LCM). The LCM generally includes an upper glass sheet and a lower glass sheet that sandwich a liquid crystal layer there between. The sensing arrangement may be a touch sensing arrangement such as those used to create a touch screen. For example, a capacitive sensing touch screen can include substantially transparent sensing points or nodes dispersed about a sheet of glass (or plastic). In addition, the cover window, which is typically designed as the outer protective barrier, may be glass or plastic. Glass tends to provide a better protective barrier given its strength and scratch resistance. There is, however, a continuing need for improved approaches for glass cover arrangements for electronic devices. 
     SUMMARY 
     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. 
     The invention can be implemented in numerous ways, including as a method, system, device or apparatus. Several embodiments of the invention are discussed below. 
     As a consumer electronic product, one embodiment can, for example, include at least a housing, electrical components disposed at least partially internal to the housing, and a cover glass coupled with the housing. The cover glass includes a selectively chemically strengthened surface region. 
     As a method for assembling an electronic product, one embodiment can, for example, include at least obtaining cover glass and selectively chemically strengthening one surface region of the cover glass differently than chemically strengthening an other surface region of the cover glass. Thereafter, the cover glass can be attached to a housing for the electronic product. 
     As a method for assembling an electronic product, one embodiment can, for example, include at least obtaining cover glass and shielding a portion of the cover glass. The shielding provides the cover glass with at least one shielded portion and at least one unshielded portion. The embodiment can also chemically strengthening the at least one unshielded portion of the cover glass. Thereafter, the cover glass can be attached to a housing for the electronic product. 
     As a method for assembling an electronic product, one embodiment can, for example, include at least obtaining cover glass and chemically strengthening the cover glass. Strengthening of a selected portion of the cover glass can be selectively enhanced. Thereafter, the cover glass can be attached to a housing for the electronic product. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIGS.  1 A and  1 B  are various views of an electronic device in accordance with one embodiment. 
         FIG.  2    shows a detailed partial cross sectional view of selective strengthening of exposed surface portions of cover glass. 
         FIGS.  3 A- 3 E  are simplified cross sectional views showing selective strengthening of cover glass in one embodiment. 
         FIGS.  4 A- 4 E  are simplified cross sectional views showing selective strengthening of cover glass in another embodiment. 
         FIGS.  5 A- 5 G  are simplified cross sectional views showing selective strengthening of cover glass in yet another embodiment. 
         FIGS.  6 A- 6 E  are simplified cross sectional views showing selective strengthening of cover glass in still yet another embodiment. 
         FIG.  7    is a flow diagram showing one embodiment of an assembly process. 
         FIG.  8    is a flow diagram showing another embodiment of an assembly process. 
         FIG.  9    is a flow diagram showing yet another embodiment of an assembly process. 
         FIG.  10    is a flow diagram showing still another embodiment of an assembly process. 
         FIG.  11    is a perspective view of an electronic device in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     Embodiments of the invention are discussed below with reference to  FIGS.  1 A- 11   . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments. 
       FIGS.  1 A and  1 B  are various views of an electronic device  100  in accordance with one embodiment. The electronic device  100  may, for example, be embodied as portable or handheld electronic device having a thin form factor (or low profile). The electronic device  100  can, for example, correspond to a media player, a media storage device, a Portable Digital Assistant (PDA), a tablet PCs, a computer, a cellular phone, a smart phone, a GPS unit, a remote control, and the like. 
     As shown in cross sectional view in  FIG.  1 A , the electronic device  100  may include a housing  102  that serves as the outer surface for the electronic device  100 . Electrical components  103  may be disposed within the housing  102 . The electrical components may include, but are not limited to, a controller (or processor), memory, battery, display, camera, and illuminator such as a flash. 
     Additionally, the electronic device  100  may have a cover glass  104 . The cover glass  104  may serve as an external surface, i.e., top surface, for the electronic device  100 . The cover glass  104  may also resist scratching and therefore may provide a substantially scratch-resistance surface for the top surface of the housing  102  for the electronic device  100 . The cover glass  104  may be coupled to the housing  102 , for example, using an adhesive  105 . 
     The electronic device  100  is shown in perspective view in  FIG.  1 B . Cover glass  104  may be provided over a display area. The cover glass  104  may be substantially transparent so that the display area can be viewed through the cover glass  104 . The display area may be disposed within the housing  102  of the electronic device  100 . The electronic device  100  may include a full view or substantially full view display area that consumes a majority of the front surface of the electronic device  100 . The display area may be embodied in a variety of ways. In one example, the display area may comprise at least a display such as a flat panel display and more particularly an LCD display. 
     The display area may alternatively or additionally include a touch sensing device positioned over a display screen. For example, the display area may include one or more glass layers having capacitive sensing points distributed thereon. Each of these components may be separate layers or they may be integrated into one or more stacks. In one embodiment, the cover glass  104  may act as the outer most layer of the display area. The adhesive  105  can be translucent and extend around the periphery so as to not optically interfere with the display area. 
     The electronic device  100  may include a display region (e.g., the display area) that includes various layers. The various layers may include at least a display, and may additionally include a sensing arrangement disposed over the display. In some cases, the layers may be stacked and adjacent one another, and may even be laminated thereby forming a single unit. In other cases, at least some of the layers are spatially separated and not directly adjacent. 
     For example, the sensing arrangement may be disposed above the display such that there is a gap there between. By way of example, the display may include a Liquid Crystal Display (LCD) that includes a Liquid Crystal Module (LCM). The LCM generally includes at least an upper glass sheet and a lower glass sheet that at least partially sandwich a liquid crystal layer there between. The sensing arrangement may be a touch sensing arrangement such as those used to create a touch screen. 
     For example, a capacitive sensing touch screen may include substantially transparent sensing points or nodes dispersed about cover glass  104 . The cover glass  104  may serve as the outer protective barrier for the display region. Typically, the cover glass  104  may be adjacent to the display region, but may also be integrated with the display region, such as another layer (outer protective layer). 
     As shown in  FIG.  1 B , the cover glass  104  may extend across the entire top surface of the housing  102 . In such a case, the edges of the cover glass  104  may be aligned, or substantially aligned, with the sides of the housing  102 . Given that the thickness of the cover glass  104  may be rather thin (i.e., less than a few millimeters), the glass material for the cover glass  104  can be selected from available glass that is stronger. For example, alumino silicate glass (e.g., DVTS from Corning) is one suitable choice for the glass material for the cover glass  104 . Other examples of glass materials include, but are not limited to including, sodalime, borosilicate, and the like. Still another example of glass material may be lithium based glass. Additionally, the edges of the cover glass  104  can be configured to correspond to a particular predetermined geometry. By machining the edges of the cover glass  104  to correspond to the particular predetermined geometry, the cover glass pieces can become stronger. For additional information about use of predetermined geometries, see U.S. Provisional Patent Application No. 61/156,803, filed Mar. 2, 2009 and entitled “Techniques for Strengthening Glass Covers for Portable Electronic Devices”, which hereby incorporated herein by reference in its entirety. 
     Moreover, as will be discussed in greater detail subsequently herein, the cover glass  104  can be selectively chemically treated for further strengthening. One suitable chemical treatment is to selectively expose one or more surface portions of the cover glass in a chemical bath containing potassium (e.g., KNO3) for a period of time (e.g., several hours) at an elevated temperature. Additionally, baths containing sodium may be used in conjunction with Lithium baths, as this combination may produce a compressive stress layer. In any case, the selective chemical treatment can desirably result in higher compression stresses at the selectively exposed surface portions of the cover glass pieces. The higher compression stresses may be the result ion exchange wherein K +  ions effectively replacing some Na ions at or near the selectively exposed surface portions of the cover glass. 
     As particularly shown in  FIG.  1 B , a selectively chemically strengthened surface region  110 A may comprise a selectively strengthened edge extremity  110 A of the cover glass. The selectively chemically strengthened surface region  110 A may have a width dimension, w, extending inwardly from peripheral edges of the cover glass. In other words, the selectively strengthened edge extremity  110 A may have a width dimension, w. The width dimension may be about two to five millimeters, or more. For example the width dimension may be about ten millimeters. A notional dashed line in  FIG.  1 B  representatively illustrates an inner extent of the selectively chemically strengthened surface region  110 A. 
     The apparatus, systems and methods according to embodiments described herein are especially suitable for cover glasses or displays (e.g., LCD displays) assembled in small form factor electronic devices such as handheld electronic devices (e.g., mobile phones, media players, personal digital assistants, remote controls, etc.) The apparatus, systems and methods can also be used for cover glasses or displays for other relatively larger form factor electronic devices (e.g., portable computers, tablet computers, displays, monitors, televisions, etc.). 
     In one embodiment, the size of a glass cover depends on the size of the associated electronic device. For example, with handheld electronic devices, the glass cover is often not more than five (5) inches diagonal. As another example, for portable electronic devices, such as smaller portable computers or tablet computers, the glass cover is often between four (4) to twelve (12) inches diagonal. As still another example, for portable electronic devices, such as full size portable computers, displays or monitors, the glass cover is often between ten (10) to twenty (20) inches diagonal or even larger. The glass cover is typically rather thin, such as having a thickness less than about 5 mm, or more specifically less than about 3 mm, or more specifically less than about 1 mm. 
       FIG.  2    shows a detailed partial cross sectional view of selective strengthening of exposed surface portions of cover glass  204 .  FIG.  2    diagrammatically illustrates a chemical treatment process of submerging the cover glass  204  in a heated potassium bath  203  (for example a molten KNO3 bath), for selective chemically strengthening the cover glass  204 . For example, the potassium bath may be heated to between about three-hundred and eighty degrees Celsius, and about four-hundred and fifty degrees Celsius. When the cover glass  204  is submerged or soaked in the heated potassium bath  203 , diffusion and ion exchange can occur at exposed surface portions of the cover glass  204 . Ion exchange may be inhibited in masked areas where corresponding surface portions of the cover glass are not exposed to the chemical bath. 
     As shown in  FIG.  2   , Na ions  205  which are present in cover glass  204  can diffuse into potassium bath  203 , while K +  ions  207  in potassium bath  203  can diffuse into cover glass  204  such that a compressive surface layer  209  can be formed. In other words, K +  ions  207  from potassium bath  203  can be exchanged with Na ions  205  to form compressive surface layer  209 . The K +  ions  207  can provide a compressive stress surface stress (CS) of the compressive surface layer  209 , which chemically strengthens the compressive surface layer  209  of the cover glass  204 . 
     Cover glass  204  is shown in  FIG.  2    as having a thickness (t). By controlling chemical treatment parameters such as the length of time of chemical strengthening treatment and/or the concentration of K +  ions  207  in potassium bath  203 , a depth (d) of compressive surface layer  209  and compressive stress surface stress (CS) of the compressive surface layer  209  may be substantially controlled. Depth of ion exchange (d) may be controlled in various ways for various cover glass thicknesses, for example by using high ion concentrations and/or bath temperatures and/or extended bath soak times, and/or by using applied electric fields to enhance diffusion. For example, bath soak time by be about six hours. In  FIG.  2   , the compressive surface layer  209  undergoing ion exchange is shown using cross hatching. 
     In some cases, K +  ions  207  may not diffuse into a center portion  211  of cover glass  204 . In  FIG.  2    the center portion  211  is shown without cross hatching. The central portion  211  of the cover glass  204  can have a central tension (CT) in response to the compressive stress surface stress (CS) of the compressive surface layer  209 . 
     As mentioned previously herein, ion exchange may be inhibited in masked areas where corresponding surface portions of the cover glass are not exposed to the chemical bath. Foil can, for example, be used for masking. Further, photolithographic patterning of ion exchange (selective chemical strengthening) of the cover glass may be done by photolithographically patterning masks thereon. In such case, photosensitive polyimide may be used for masking; or an applied over layer of aluminum (which may be applied by sputtering) may be photolithographically patterned into a patterned mask using photoresist and etching of the aluminum. 
       FIGS.  3 A- 3 E  are simplified cross sectional views showing selective strengthening of cover glass in one embodiment.  FIG.  3 A  shows cover glass  304  prior to a first strengthening treatment.  FIG.  3 B  shows a cover glass  304  after the first strengthening treatment, such as treatment in a first heated potassium bath for a first period of time as discussed previously herein. 
     In  FIGS.  3 B- 3 E  compressive surface layer  309  from undergoing ion exchange is shown using cross hatching. Compressive surface layer  309  can have a corresponding depth of compressive layer. In some cases, potassium ions may not diffuse into a center portion  311  of cover glass  304 . In  FIG.  3 B  the center portion  311  is shown without cross hatching. The central portion  311  of the cover glass  304  can have a central tension (CT) in response to the compressive stress surface stress (CS) of the compressive surface layer  309 . For example, hypothetically speaking, the following is theorized with respect to possible effects of the first strengthening treatment: the compressive surface layer  309  may have a peak compressive stress of about seven hundred and thirty Mega Pascals (730 Mega Pascals), and a depth of compressive layer of about thirty eight point six microns (38.6 microns); and the central portion  311  may have a central tension of about fifty-four Mega Pascals (54 Mega Pascals.) 
       FIG.  3 C  shows shielding  306  of a portion of the cover glass  304 , the shielding  306  providing the cover glass  304  with at least one shielded portion  308  and at least one unshielded portion  310 . Suitable masking  306  of the cover glass, as discussed previously herein, may be used for the shielding  306  of the cover glass  304 . For example, as shown in  FIG.  3 C  opposing major surfaces of the cover glass may be shielded by applied mask material  306 , so as to provide the shielded portion  308  of the cover glass. Edge extremities  310  of the cover glass  304  may be unshielded portions  310 . Mask  306  may be suitably patterned as desired for shielded portion  308  and unshielded portion  310 . For example, unshielded portion  310  may have a width dimension of about two to about five millimeters, or more. For example the width dimension may be about ten millimeters. 
       FIG.  3 D  shows cover glass  304  after a second strengthening treatment, such as treatment in a second heated potassium bath for a second period of time as discussed previously herein. Strengthening of a selected unshielded portion  310  of the cover glass can be selectively enhanced by the second strengthening treatment. Because it is unshielded, unshielded portion  310  may be substantially affected by the second strengthening treatment, so as to provide a selectively chemically strengthened surface region  310 A. Conversely, because it is shielded, shielded portion  308  of the other chemically strengthened surface region  308 A may be substantially unaffected by the second strengthening treatment. Accordingly, the selectively chemically strengthened surface region  310 A of the cover glass may have enhanced strengthening that is greater than strengthening of the other chemically strengthened surface region  308 A. In light of the foregoing, it should be understood that the selectively chemically strengthened surface region  310 A of the cover glass may be strengthened differently than the other chemically strengthened surface region  308 A. After the second strengthening treatment, the shielding  306  may be removed as shown in  FIG.  3 E . 
     In  FIGS.  3 D and  3 E , the selectively chemically strengthened surface region  310 A of the cover glass may have enhanced strengthening with an enhanced depth of compressive layer that is deeper than the depth of compressive layer of the other chemically strengthened surface region  308 A. For example, hypothetically speaking, it is theorized that the enhanced depth of compressive layer of the selectively chemically strengthened surface region  310 A may be about one hundred microns, while the depth of compressive layer of the other chemically strengthened surface region  308 A may be about thirty eight point six microns. 
     Comparing  FIG.  3 C  to  FIG.  3 D  for illustration of the effects of the second strengthening treatment, the enhanced, deeper depth of compressive layer of the selectively chemically strengthened surface region  310 A is highlighted with expanded cross hatching in the selectively chemically strengthened surface region  310 A. Similarly, a modified central region  311 A in  FIG.  3 D  is depicted as smaller, relative to corresponding central region  311  in  FIG.  3 C . Of course, it should be understood that since depth of compressive layer differences may be on the order of tens of microns, differences between  FIGS.  3 C and  3 D  may be shown as greatly exaggerated for ease of illustration. 
     Furthermore, it should be understood that the selectively chemically strengthened surface region  310 A of the cover glass may have enhanced strengthening, with an enhanced compressive stress that is greater than compressive stress of the other chemically strengthened surface region  308 A. For example, hypothetically speaking, it is theorized that the two regions  310 A,  308 A may have similar peak compressive stress of about seven hundred and thirty Mega Pascals. However, because of the aforementioned deeper depth of compressive layer, the selectively chemically strengthened surface region  310 A of the cover glass may have total accumulated compressive stress that is greater than corresponding total accumulated compressive stress of the other chemically strengthened surface region  308 A. 
     Moreover, the selectively chemically strengthened surface region  310 A of the cover glass may have enhanced strengthening, with an enhanced central tension that is greater than central tension of the other chemically strengthened surface region  308 A. For example, hypothetically speaking, it is theorized that the enhanced central tension of the selectively chemically strengthened surface region  310 A may be about ninety-one Mega Pascals, while the central tension of the other chemically strengthened surface region  308 A may be about fifty-one Mega Pascals. 
       FIGS.  4 A- 4 E  are simplified cross sectional views showing selective strengthening of cover glass in another embodiment.  FIG.  4 A  shows cover glass  404  prior to a first strengthening treatment. Prior to the first strengthening treatment,  FIG.  4 B  shows shielding  406  of a portion of the cover glass  404 , the shielding  406  providing the cover glass  404  with at least one shielded portion  408  and at least one unshielded portion  410 . Suitable masking  406  of the cover glass, as discussed previously herein, may be used for the shielding  406  of the cover glass  404 . For example, as shown in  FIG.  4 B  opposing major surfaces of the cover glass may be shielded by applied mask material  406 , so as to provide the shielded portion  408  of the cover glass. Edge extremities  410  of the cover glass  404  may be unshielded portions  410 . Mask  406  may be suitably patterned as desired for shielded portion  408  and unshielded portion  410 . 
       FIG.  4 C  shows a cover glass  404  after the first strengthening treatment, such as treatment in a first heated potassium bath for a first period of time as discussed previously herein. Compressive surface layer  409  from undergoing ion exchange in unshielded portion  410 A is shown using cross hatching. In some cases, potassium ions may not diffuse into a center portion  411  of cover glass  404 . In  FIG.  4 C  the center portion  411  is shown without cross hatching. 
     Because it is unshielded, unshielded portion  410 A may be substantially affected by the first strengthening treatment. Conversely, because it is shielded, shielded portion  408 A may be substantially unaffected by the first strengthening treatment. After the first strengthening treatment, the shielding  406  may be removed as shown in  FIG.  4 D . 
       FIG.  4 E  shows cover glass  404  after a second strengthening treatment, such as treatment in a second heated potassium bath for a second period of time as discussed previously herein. Because it has already undergone the first strengthening treatment, selectively chemically strengthened surface region  410 B may be substantially affected by the second strengthening treatment. In particular, strengthening of selectively chemically strengthened surface region  410 B can be selectively enhanced by the second strengthening treatment. However, it should be understood that because it was previously shielded, the other chemically strengthened surface region  408 B may not have been affected by the first chemical strengthening treatment, and may show relatively less effect after the second strengthening treatment. Accordingly, the selectively chemically strengthened surface region  410 B of the cover glass may have enhanced strengthening that is greater than strengthening of the other chemically strengthened surface region  408 B. In light of the foregoing, it should be understood that the selectively chemically strengthened surface region  410 B of the cover glass may be strengthened differently than the other chemically strengthened surface region  408 B. 
     In  FIGS.  4 D and  4 E , the selectively chemically strengthened surface region  410 B of the cover glass may have enhanced strengthening with an enhanced depth of compressive layer that is deeper than the depth of compressive layer of the other chemically strengthened surface region  408 B. Comparing  FIG.  4 D  to  FIG.  4 E  for illustration of the effects of the second strengthening treatment, the enhanced, deeper depth of compressive layer of the selectively chemically strengthened surface region  410 B is highlighted with expanded cross hatching in the selectively chemically strengthened surface region  410 B. Similarly, a modified central region  411 A in  FIG.  4 E  is depicted as smaller, relative to corresponding central region  411  in  FIG.  4 D . 
     Furthermore, it should be understood that the selectively chemically strengthened surface region  410 B of the cover glass may have enhanced strengthening, with an enhanced compressive stress that is greater than compressive stress of the other chemically strengthened surface region  408 B. Moreover, the selectively chemically strengthened surface region  410 B of the cover glass may have enhanced strengthening, with an enhanced central tension that is greater than central tension of the other chemically strengthened surface region  408 B. 
       FIGS.  5 A- 5 G  are simplified cross sectional views showing selective strengthening of cover glass in yet another embodiment.  FIG.  5 A  shows cover glass  504  prior to a first strengthening treatment.  FIG.  5 B  shows a cover glass  504  after the first strengthening treatment, such as treatment in a first heated potassium bath for a first period of time as discussed previously herein. Compressive surface layer  509  from undergoing ion exchange is shown using cross hatching. Compressive surface layer  509  can have a corresponding depth of compressive layer. In some cases, potassium ions may not diffuse into a center portion  511  of cover glass  504 . In  FIG.  5 B  the center portion  511  is shown without cross hatching. 
       FIG.  5 C  illustrates selective strengthening of selected surface portion  510  of the cover glass  504  using a second strengthening treatment of electric field assisted ion exchange strengthening in a heated environment, such as an electric furnace. Electrode placement may be chosen so that other surface portion  508  is substantially unaffected. An anode paste  520  and a cathode paste  522  may each have a suitable thickness, for example about one half to about one millimeter, wherein the pastes may comprise KNO3 and Al 2 O 3  and a suitable binder, and may be applied in contact with the cover glass  504 . The anode paste  520  and cathode paste  522  may be separate from each other by a suitable mask  524 , for example a high temperature rubber, such as a fluorinated rubber. 
     A suitable voltage may be approximately within a range from about one hundred volts to about three hundred volts, which may be applied to an anode electrode  526  (coupled to the anode paste  520 ) and to a cathode electrode  528  (coupled to the cathode paste  522 ) for a sufficient period of time, for example, approximately six hours. The anode electrode  526  and the cathode electrode  528  may employ a suitable metal. A noble metal such as platinum may be employed, or a temperature-resistant material such as tungsten or molybdenum. 
       FIG.  5 D  shows a detailed view of  FIG.  5 C , to illustrate selective strengthening of selected surface portion  510  of the cover glass  504  using the electric field assisted ion exchange strengthening. Notional dashed arrows are shown in  FIG.  5 D  to illustrate electric field assisted K +  ion diffusion into the selected surface portion. 
       FIG.  5 E  shows cover glass  504  after the second strengthening treatment of electric field assisted ion exchange strengthening.  FIG.  5 F  shows a detailed view of  FIG.  5 E .  FIG.  5 G  shows electrodes removed after the second strengthening treatment. Strengthening of selected surface region  510 A of the cover glass can be selectively enhanced by the second strengthening treatment. Selectively chemically strengthened surface region  510 A may be substantially affected by undergoing both the first and second strengthening treatment. However, the other chemically strengthened surface region  508 A may be substantially unaffected by the second strengthening treatment. Accordingly, the selectively chemically strengthened surface region  510 A of the cover glass may have enhanced strengthening that is greater than strengthening of the other chemically strengthened surface region  508 A. In light of the foregoing, it should be understood that the selectively chemically strengthened surface region  510 A of the cover glass may be strengthened differently than the other chemically strengthened surface region  508 A. 
     The selectively chemically strengthened surface region  510 A of the cover glass may have enhanced strengthening with an enhanced depth of compressive layer that is deeper than the depth of compressive layer of the other chemically strengthened surface region  508 A. Comparing  FIG.  5 C  to  FIG.  5 E  (and comparing detailed view  5 D to detailed view  5 F) for illustration of the effects of the second strengthening treatment, the enhanced, deeper depth of compressive layer of the selectively chemically strengthened surface region  510 A is highlighted with expanded cross hatching in the selectively chemically strengthened surface region  510 A. Similarly, a modified central region  511 A in  FIG.  5 E  is depicted as smaller, relative to corresponding central region  511  in  FIG.  5 C . 
     Furthermore, it should be understood that the selectively chemically strengthened surface region  510 A of the cover glass may have enhanced strengthening, with an enhanced compressive stress that is greater than compressive stress of the other chemically strengthened surface region  508 A. Moreover, the selectively chemically strengthened surface region  510 A of the cover glass may have enhanced strengthening, with an enhanced central tension that is greater than central tension of the other chemically strengthened surface region  508 A. 
       FIGS.  6 A- 6 E  are simplified cross sectional views showing selective strengthening of cover glass in still yet another embodiment.  FIG.  6 A  shows cover glass  604  prior to a first strengthening treatment.  FIG.  6 B  shows a cover glass  604  after the first strengthening treatment, such as treatment in a first heated potassium bath for a first period of time as discussed previously herein. 
     Compressive surface layer  609  from undergoing ion exchange is shown using cross hatching. Compressive surface layer  609  can have a corresponding depth of compressive layer. In some cases, potassium ions may not diffuse into a center portion  611  of cover glass  604 . In  FIG.  6 B  the center portion  611  is shown without cross hatching. 
       FIG.  6 C  shows shielding  606  of a portion of the cover glass  604 , the shielding  606  providing the cover glass  604  with at least one shielded portion  608  and at least one unshielded portion  610 . Suitable masking  606  of the cover glass, as discussed previously herein, may be used for the shielding  606  of the cover glass  604 . For example, as shown in  FIG.  6 C  a bottom major surface of the cover glass may be shielded by applied mask material  606 , so as to provide the shielded portion  608  of the cover glass. Edge extremities and a top major surface  610  of the cover glass  604  may be unshielded portions  610 . Mask  606  may be suitably patterned as desired for shielded portion  608  and unshielded portion  610 . 
       FIG.  6 D  shows cover glass  604  after a second strengthening treatment, such as treatment in a second heated potassium bath for a second period of time as discussed previously herein. Strengthening of a selected unshielded portion  610 A of the cover glass can be selectively enhanced by the second strengthening treatment. Because it is unshielded, unshielded portion  610 A may be substantially affected by the second strengthening treatment, so as to provide a selectively chemically strengthened surface region  610 A. Conversely, because it is shielded, shielded portion  608 A of the other chemically strengthened surface region  608 A may be substantially unaffected by the second strengthening treatment. Accordingly, the selectively chemically strengthened surface region  610 A of the cover glass may have enhanced strengthening that is greater than strengthening of the other chemically strengthened surface region  608 A. In light of the foregoing, it should be understood that the selectively chemically strengthened surface region  610 A of the cover glass may be strengthened differently than the other chemically strengthened surface region  608 A. After the second strengthening treatment, the shielding  606  may be removed as shown in  FIG.  6 E . 
     In  FIGS.  6 D and  6 E , the selectively chemically strengthened surface region  610 A of the cover glass may have enhanced strengthening with an enhanced depth of compressive layer that is deeper than the depth of compressive layer of the other chemically strengthened surface region  608 A. Comparing  FIG.  6 C  to  FIG.  6 D  for illustration of the effects of the second strengthening treatment, the enhanced, deeper depth of compressive layer of the selectively chemically strengthened surface region  610 A is highlighted with expanded cross hatching in the selectively chemically strengthened surface region  610 A. Similarly, a modified central region  611 A in  FIG.  6 D  is depicted as smaller, relative to corresponding central region  611  in  FIG.  6 C . 
     Furthermore, it should be understood that the selectively chemically strengthened surface region  610 A of the cover glass may have enhanced strengthening, with an enhanced compressive stress that is greater than compressive stress of the other chemically strengthened surface region  608 A. Moreover, the selectively chemically strengthened surface region  610 A of the cover glass may have enhanced strengthening, with an enhanced central tension that is greater than central tension of the other chemically strengthened surface region  608 A. 
       FIG.  7    is a flow diagram illustrating an assembly process  700  of one embodiment. The assembly process  700  may begin with obtaining  702  a cover glass. The assembly process  700  may continue with shielding  704  a portion of the cover glass. The shielding may provide the cover glass with at least one shielded portion and at least one unshielded portion. In one embodiment, such shielding  704  may involve patterning (or, more particularly, photolithographic patterning) on the cover glass. 
     The assembly process  700  may continue with chemically strengthening  706  the at least one unshielded portion of the cover glass. The at least one unshielded portion of the cover glass may be exposed to ion exchange. The assembly process  700  may continue with subsequently attaching  708  the cover glass to the housing. Once the cover glass has been attached to the housing, the assembly process  700  can end. 
       FIG.  8    is a flow diagram showing another embodiment of an assembly process  800 . The assembly process  800  may begin with obtaining  802  a cover glass. The assembly process  800  may continue with shielding  804  a portion of the cover glass. The shielding may provide the cover glass with at least one shielded portion and at least one unshielded portion. In one embodiment, such shielding  804  may involve patterning (or, more particularly, photolithographic patterning) on the cover glass. 
     The assembly process  800  may continue with chemically strengthening  806  the at least one unshielded portion of the cover glass. The at least one unshielded portion of the cover glass may be exposed to ion exchange. The assembly process  800  may continue with removing  808  the shielding. The assembly process  800  may continue with a second chemical strengthening  810  of the cover glass. The assembly process  800  may continue with subsequently attaching  812  the cover glass to the housing. Once the cover glass has been attached to the housing, the assembly process  800  can end. 
       FIG.  9    is a flow diagram showing yet another embodiment of an assembly process  900 . The assembly process  900  may begin with obtaining  902  a cover glass. The process  900  may begin with a first chemical strengthening  904  of the cover glass. The assembly process  900  may continue with shielding  906  a portion of the cover glass. The shielding may provide the cover glass with at least one shielded portion and at least one unshielded portion. In one embodiment, such shielding  906  may involve patterning (or, more particularly, photolithographic patterning) on the cover glass. 
     The assembly process  900  may continue with second chemical strengthening. In particular, the assembly process  900  may continue with chemically strengthening  908  the at least one unshielded portion of the cover glass. The at least one unshielded portion of the cover glass may be exposed to ion exchange. The assembly process  900  may continue with removing  910  the shielding. The assembly process  900  may continue with subsequently attaching  912  the cover glass to the housing. Once the cover glass has been attached to the housing, the assembly process  900  can end. 
       FIG.  10    is a flow diagram showing still another embodiment of an assembly process  1000 . The assembly process  1000  may begin with obtaining  1002  a cover glass. The assembly process  1000  may continue with chemically strengthening  1004  the cover glass. The assembly process  1000  may continue with selectively enhancing  1006  strengthening of a selected portion of the cover glass. The assembly process  1000  may continue with subsequently attaching  1008  the cover glass to the housing. Once the cover glass has been attached to the housing, the assembly process  1000  can end. 
       FIG.  11    is a perspective view of an electronic device in accordance with another embodiment. As particularly shown in  FIG.  11   , a selectively chemically strengthened surface region  1110 A may comprise a selectively strengthened edge extremity  1110 A of the cover glass. The selectively chemically strengthened surface region  1110 A may have a width dimension, w, extending inwardly from peripheral edges of the cover glass. In other words, the selectively strengthened edge extremity  1110 A may have a width dimension, w. The width dimension may be about two to five millimeters, or more. For example the width dimension may be about ten millimeters. A notional dashed line in  FIG.  11    representatively illustrates an inner extent of the selectively chemically strengthened surface region  1110 A. 
     Similarly the cover glass may have one or more apertures  1130 B,  1130 C extending through the cover glass, and one or more aperture edge regions  1110 B,  1110 C each adjacent to a respective one the apertures  1130 B,  1130 C. The selectively chemically strengthened surface region may further comprise the aperture edge regions  1110 B,  1110 C of the cover glass, each a respective width dimension, w. 
     Additional information on selective glass strengthening may be contained in U.S. patent application Ser. No. 12/847,926, filed Jul. 30, 2010, and entitled “ELECTRONIC DEVICE HAVING SELECTIVITY STRENGTHENING GLASS COVER GLASS,” which is hereby incorporated herein by reference. 
     Additional information on strengthening variable thickness glass is contained in U.S. Provisional Patent Application No. 61/453,398, filed Mar. 16, 2011, and entitled “STRENGTHENING VARIABLE THICKNESS GLASS”, which is hereby incorporated herein by reference; and in U.S. patent application Ser. No. 13/235,036, filed concurrently herewith, and entitled “STRENGTHENING VARIABLE THICKNESS GLASS”, which is hereby incorporated herein by reference 
     The advantages of the invention are numerous. Different aspects, embodiments or implementations may yield one or more of the following advantages. One advantage is that cover glass can be selectively strengthened in high damage risk areas such as edge extremity regions. Another advantage is that cover glass can be selectively strengthened adjacent to apertures where damage risk may be higher, due to defects introduced in machining or grinding in forming of the apertures. Another advantage is that high damage risk areas can be strengthened while limiting increases in overall central tension of the cover glass, and possible deleterious effects of over strengthening, by selectively strengthening selected portions of the cover glass. 
     The many features and advantages of the present invention are apparent from the written description and, thus, it is intended by the appended claims to cover all such features and advantages of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, the invention should not be limited to the exact construction and operation as illustrated and described. Hence, all suitable modifications and equivalents may be resorted to as falling within the scope of the invention.

Metadata:
Filing Date: 20221201
Publication Date: 20240723
Grant Date: 20240723
Priority Date: 20110316
Inventors: Weber, Douglas J.
Assignee: APPLE INC
CPC Classifications: [{"code": "C03C21/001", "inventive": false, "first": false, "tree": "[]"}, {"code": "C09K2323/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C21/002", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C21/005", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2457/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B17/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B2457/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B17/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C21/003", "inventive": true, "first": true, "tree": "[]"}, {"code": "C03C21/003", "inventive": true, "first": true, "tree": "[]"}, {"code": "C09K2323/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C21/005", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C21/002", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C21/001", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2457/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B17/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C21/003", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 46828270