PATENT DOCUMENT

Publication Number: US-11691912-B2
Application Number: US-201916659173-A
Country: US
Kind Code: B2

Title: Chemically strengthened and textured glass housing member

Abstract:
A glass member for a housing of an electronic device may include an aluminosilicate glass substrate defining a first surface of the glass member, the first surface having a first surface roughness, a fused composite coating bonded to a portion of the aluminosilicate glass substrate and defining a second surface of the glass member, the second surface having a second surface roughness greater than the first surface roughness, a first ion-exchanged layer extending into the glass member and through the fused composite coating, and a second ion-exchanged layer extending into the glass member from the first surface. The fused composite coating may include an amorphous glass matrix and a crystalline material dispersed in the amorphous glass matrix.

Claims:
What is claimed is: 
     
       1. A glass member for a housing of an electronic device, comprising:
 an aluminosilicate glass substrate defining a first surface of the glass member, the first surface having a first average surface roughness (Ra) below 1 micron; 
 a fused composite coating bonded to a portion of the aluminosilicate glass substrate and comprising:
 an amorphous glass matrix having a softening temperature that is lower than a softening temperature of the aluminosilicate glass substrate and a coefficient of thermal expansion that is greater than the coefficient of thermal expansion of the aluminosilicate glass substrate; and 
 crystalline particles having a softening temperature that is higher than the softening temperature of the amorphous glass matrix and a coefficient of thermal expansion that is less than the coefficient of thermal expansion of the amorphous glass matrix, the crystalline particles dispersed in the amorphous glass matrix and extending from a surface of the amorphous glass matrix, thereby defining a textured second surface of the glass member, the textured second surface having a second average surface roughness (Ra) between 1 micron and 10 microns; 
 
 a first ion-exchanged layer extending into the glass member and through the fused composite coating; and 
 a second ion-exchanged layer extending into the glass member from the first surface. 
 
     
     
       2. The glass member of  claim 1 , wherein the second ion-exchanged layer extends into the aluminosilicate glass substrate. 
     
     
       3. The glass member of  claim 1 , wherein the first ion-exchanged layer comprises:
 sodium ions, from the fused composite coating, in the aluminosilicate glass substrate; and 
 lithium ions, from the aluminosilicate glass substrate, in the fused composite coating. 
 
     
     
       4. The glass member of  claim 1 , wherein:
 the first ion-exchanged layer has a first composition and comprises sodium ions, lithium ions, and potassium ions; and 
 the second ion-exchanged layer has a second composition different from the first composition and comprises lithium ions and potassium ions. 
 
     
     
       5. The glass member of  claim 1 , wherein:
 the first ion-exchanged layer extends a first depth into the glass member; and 
 the second ion-exchanged layer extends a second depth into the glass member, the second depth different than the first depth. 
 
     
     
       6. The glass member of  claim 1 , wherein the crystalline particles have an average particle size of between about 0.1 microns and about 0.5 microns. 
     
     
       7. The glass member of  claim 1 , wherein the crystalline particles are ceramic particles. 
     
     
       8. The glass member of  claim 1 , wherein:
 the glass member defines a back of the electronic device; 
 the first surface defines a first region of the back of the electronic device; and 
 the second surface defines a second region of the back of the electronic device. 
 
     
     
       9. The glass member of  claim 1 , wherein a coefficient of thermal expansion of the fused composite coating is about the same as the coefficient of thermal expansion of the aluminosilicate glass substrate. 
     
     
       10. An electronic device comprising:
 a processor; 
 a display; and 
 a housing comprising a chemically strengthened glass member, the chemically strengthened glass member comprising:
 an aluminosilicate glass substrate defining a first surface of the chemically strengthened glass member, the first surface having a first average surface roughness (Ra) below 1 micron; and 
 a fused composite coating bonded to the aluminosilicate glass substrate and comprising:
 an amorphous glass matrix having a softening temperature that is lower than a softening temperature of the aluminosilicate glass substrate and a coefficient of thermal expansion that is greater than a coefficient of thermal expansion of the aluminosilicate glass substrate; and 
 particles of a crystalline material having a softening temperature that is higher than the softening temperature of the amorphous glass matrix and a coefficient of thermal expansion that is less than the coefficient of thermal expansion of the amorphous glass matrix, the particles of the crystalline material dispersed in the amorphous glass matrix and protruding from a surface of the amorphous glass matrix, thereby defining a textured second surface of the chemically strengthened glass member, the textured second surface having a second average surface roughness (Ra) between 1 micron and 10 microns; 
 
 
 a first ion-exchanged layer extending into the glass member and through the fused composite coating; and 
 a second ion-exchanged layer extending into the glass member from the first surface. 
 
     
     
       11. The electronic device of  claim 10 , wherein:
 the housing further defines a glass member defining a front of the electronic device and positioned over the display; and 
 the chemically strengthened glass member defines a back of the electronic device. 
 
     
     
       12. The electronic device of  claim 11 , wherein the second surface of the chemically strengthened glass member defines an exterior back surface of the electronic device. 
     
     
       13. The electronic device of  claim 10 , wherein:
 the first ion-exchanged layer has a first compressive stress profile; 
 the second ion-exchanged layer has a second compressive stress profile different than the first compressive stress profile; and 
 the chemically strengthened glass member further comprises a region between the first and second ion-exchanged layers having a tensile stress profile. 
 
     
     
       14. The electronic device of  claim 10 , wherein:
 the fused composite coating has a coefficient of thermal expansion that is about the same as the coefficient of thermal expansion of the aluminosilicate glass substrate. 
 
     
     
       15. The electronic device of  claim 10 , wherein the fused composite coating has a thickness between about 5 microns and about 20 microns. 
     
     
       16. A method comprising:
 providing an aluminosilicate glass substrate defining a first surface, the first surface having a first average surface roughness (Ra) below 1 micron; 
 applying to a second surface of the aluminosilicate glass substrate a composite coating comprising:
 a glass frit having a softening temperature that is lower than a softening temperature of the aluminosilicate glass substrate and a coefficient of thermal expansion that is greater than a coefficient of thermal expansion of the aluminosilicate glass substrate; 
 a crystalline material having a softening temperature that is higher than the softening temperature of an amorphous glass matrix formed by fusing the glass frit and having a coefficient of thermal expansion that is less than the coefficient of thermal expansion of the amorphous glass matrix; 
 a solvent; and 
 a resin; 
 
 drying the composite coating to remove the solvent; 
 heating the aluminosilicate glass substrate and the composite coating to fuse the glass frit, thereby producing a fused composite coating including the amorphous glass matrix, and to bond the fused composite coating to the aluminosilicate glass substrate and define a textured surface having an average surface roughness (Ra) between  1  micron and  10  microns and defined at least in part by the crystalline material protruding from a surface of the amorphous glass matrix, thereby forming a textured glass member; and 
 chemically strengthening the textured glass member thereby producing: 
 a first ion-exchanged layer extending into the textured glass member and through the fused composite coating; and 
 a second ion-exchanged layer extending into the textured glass member from the first surface. 
 
     
     
       17. The method of  claim 16 , wherein the operation of heating the aluminosilicate glass substrate and the composite coating causes sodium ions to migrate from the composite coating into the aluminosilicate glass substrate. 
     
     
       18. The method of  claim 16 , wherein the operation of heating the aluminosilicate glass substrate and the composite coating comprises heating the aluminosilicate glass substrate and the composite coating to a temperature above the softening temperature of the glass frit, below the softening temperature of the aluminosilicate glass substrate, and below the softening temperature of the crystalline material. 
     
     
       19. The method of  claim 16 , wherein the operation of chemically strengthening the textured glass member comprises submerging the textured glass member in a bath comprising potassium salt. 
     
     
       20. The method of  claim 16 , wherein the operation of applying the composite coating comprises screen printing the composite coating on one side of the aluminosilicate glass substrate.

Description:
This application is a nonprovisional patent application of and claims the benefit of 62/781,542, filed Dec. 18, 2018 and titled “Chemically Strengthened and Textured Glass Housing Member,” the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The described embodiments relate generally to chemically strengthened glass members with textured surfaces. 
     BACKGROUND 
     Electronic devices may use glass for various components and applications. For example, handheld and wearable electronic devices, such as tablet computers, mobile phones (e.g., smartphones), and electronic watches, may use glass housing components. Glass housing components for electronic devices may provide advantages such as transparency, scratch resistance, hardness, stiffness, and the like. Glass housing components may be processed to impart various characteristics or properties to the glass. For example, glass may be chemically strengthened or tempered to improve its strength and/or toughness. 
     SUMMARY 
     A glass member for a housing of an electronic device may include an aluminosilicate glass substrate defining a first surface of the glass member, the first surface having a first surface roughness, a fused composite coating bonded to a portion of the aluminosilicate glass substrate and defining a second surface of the glass member, the second surface having a second surface roughness greater than the first surface roughness, a first ion-exchanged layer extending into the glass member and through the fused composite coating, and a second ion-exchanged layer extending into the glass member from the first surface. The fused composite coating may include an amorphous glass matrix and a crystalline material dispersed in the amorphous glass matrix. The crystalline material may define a tactile texture along the second surface. The second ion-exchanged layer may extend into the aluminosilicate glass substrate. The first surface roughness may have an average surface roughness (Ra) between about 0.1 microns and about 3 microns. 
     The first ion-exchanged layer may include sodium ions, from the fused composite coating, in the aluminosilicate glass substrate, and lithium ions, from the aluminosilicate glass substrate, in the fused composite coating. The first ion-exchanged layer may have a first composition and may include sodium ions, lithium ions, and potassium ions. The second ion-exchanged layer may have a second composition different from the first composition and may include lithium ions and potassium ions. The first ion-exchanged layer may extend a first depth into the glass member, and the second ion-exchanged layer may extend a second depth into the glass member, the second depth different than the first depth. 
     An electronic device may include a processor, a display, and a housing comprising a chemically strengthened glass member. The chemically strengthened glass member may include an aluminosilicate glass substrate defining a first surface of the chemically strengthened glass member and a fused composite coating bonded to the aluminosilicate glass substrate and defining a second surface of the chemically strengthened glass member, the second surface having a surface roughness greater than a surface roughness of the first surface. 
     The housing may further define a glass member defining a front of the electronic device and positioned over the display, and the chemically strengthened glass member may define a back of the electronic device. The second surface of the chemically strengthened glass member may define an exterior back surface of the electronic device. 
     The fused composite coating may include an amorphous glass matrix and a crystalline material dispersed in the amorphous glass matrix. The chemically strengthened glass member may include a first ion-exchanged layer extending into the chemically strengthened glass member from the first surface and having a first compressive stress profile, a second ion-exchanged layer extending into the chemically strengthened glass member from the second surface and having a second compressive stress profile different than the first compressive stress profile, and a region between the first and second ion-exchanged layers and having a tensile stress profile. 
     The aluminosilicate glass substrate may have a first coefficient of thermal expansion, and the fused composite coating may have a second coefficient of thermal expansion that is the same as the first coefficient of thermal expansion. The fused composite coating may have a thickness between about 2 microns and about 20 microns. 
     A method may include applying, to a surface of an aluminosilicate glass substrate, a composite coating comprising a glass frit, a crystalline material, and a solvent. The method may further include drying the composite coating to remove the solvent, heating the aluminosilicate glass substrate and the composite coating to bond the composite coating to the aluminosilicate glass substrate and define a tactile surface defined at least in part by the crystalline material, thereby forming a textured glass member, and chemically strengthening the textured glass member. The operation of heating the aluminosilicate glass substrate and the composite coating may cause sodium ions to migrate from the composite coating into the aluminosilicate glass substrate. The method may further include coupling the textured glass member to a housing member of a mobile phone such that the composite coating defines an exterior surface of the mobile phone. 
     The operation of heating the aluminosilicate glass substrate and the composite coating may include heating the aluminosilicate glass substrate and the composite coating to a temperature above a softening temperature of the glass frit, below a softening temperature of the aluminosilicate glass substrate, and below a melting temperature of the crystalline material. The operation of chemically strengthening the textured glass member may include submerging the textured glass member in a bath comprising potassium salt. The operation of applying the composite coating may include screen printing the composite coating on one side of the aluminosilicate glass substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure 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: 
         FIG.  1 A  depicts a front perspective view of an example electronic device; 
         FIG.  1 B  depicts a rear perspective view of the electronic device of  FIG.  1 A ; 
         FIG.  1 C  depicts a partial cross-sectional view of the electronic device of  FIGS.  1 A- 1 B ; 
         FIG.  2 A  depicts a partial cross-sectional view of a glass member having a textured surface; 
         FIG.  2 B  depicts a detail view of a portion of the glass member of  FIG.  2 A  according to an embodiment; 
         FIG.  2 C  depicts a detail view of a portion of the glass member of  FIG.  2 A  according to another embodiment; 
         FIGS.  3 A- 3 C  depict a partial cross-sectional view of a glass member at various stages of ion exchange; 
         FIG.  4    depicts a flow chart of an example process for producing chemically strengthened and textured glass members; 
         FIG.  5 A  depicts a partial cross-sectional view of a glass member with a composite coating applied to a surface; 
         FIG.  5 B  depicts a partial cross-sectional view of the glass member of  FIG.  5 A  with fused a composite coating; 
         FIG.  6    depicts a perspective view of a locally textured glass member; and 
         FIG.  7    depicts example components of an electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The embodiments herein are generally directed to textured glass members for electronic devices, and more particularly, to glass housing members with textured surfaces that produce a particular tactile feel and appearance to the glass housing member. The textured surfaces may improve the functionality of an electronic device in various ways. For example, in the context of a smartphone, the textured surface may have a higher coefficient of friction than an untextured glass surface, allowing the phone to be more easily held in a user&#39;s hand and preventing the phone from slipping or sliding off of tables or other resting surfaces. As another example, fingerprints may be less visible on a textured surface as compared to a smooth, untextured glass surface. Other aesthetic results may also be achieved by the textured glass surfaces. 
     Textured glass members described herein may be formed by applying and bonding a composite coating to a glass substrate. The composite coating may include glass frit (e.g., glass powder or particulate), and optionally additional materials such as powders of crystalline materials. When heated, the composite coating, or components thereof, may soften and fuse together, and also bond to the underlying glass substrate. The resulting fused composite coating may have a particular surface roughness (Ra) that imparts a desired tactile feel to the glass member and ultimately to the electronic device housing in which it is incorporated. (The fused composite coating may have a particular translucency or other optical or visual property.) The surface roughness may be a result of incomplete melting and/or flowing of an amorphous glass frit material in the coating (e.g., the powder may not flatten completely along the exposed surface). Alternatively or additionally, other particulates in the coating may not soften, or may soften to a lesser degree than an amorphous glass frit, when the coating is fused, and thus may impart a surface texture to the exposed surface of the glass member. For example, particles or powder of a crystalline material may be mixed with an amorphous glass frit. When fused, the amorphous glass frit may fuse together to form a matrix that holds the particles or powder of the crystalline material. 
     After the composite coating is fused together and bonded to the substrate, the resulting textured glass member may be chemically strengthened to improve the strength, toughness, and/or other structural material property of the textured glass member. Chemical strengthening may include submerging the textured glass member in an ion-exchange bath, or any other suitable chemical strengthening process. 
     A textured glass member having particular characteristics, such as a particular surface roughness, may be achieved by selecting particular materials for the substrate and the composite coating, as well as by selecting particular processing steps and processing parameters. For example, in some cases, a target surface roughness may be specified for a textured glass member, and that surface roughness may be achieved by selecting a composite coating with particular properties, such as particle size and/or composition, as well as by selecting particular processing parameters, such as the time and temperature of a fusing operation. Other example properties of a textured glass member that may be controlled by adjusting the materials of the composite coating (and the processing parameters of the glass texturing process) include, without limitation, haziness, glossiness, roughness, transmissivity, transparency, translucency, and opacity. 
     Further, the materials for the substrate and the composite coating may also be selected so that the textured glass member does not warp or bend as a result of the chemical strengthening. For example, a textured glass surface may react to a chemical strengthening process differently than a smooth surface. Accordingly, in cases where a composite coating is applied to just one side of a glass substrate (or any other amount that is less than all sides), a chemical strengthening process may result in an asymmetrical internal force distribution within the textured glass member which may in turn result in a non-flat (e.g., curved) glass member. To mitigate this, the substrate and composite coating described herein may be selected so that the effect of a chemical strengthening process does not result in significant bending or warping. In some cases, this is achieved by selecting materials of the composite coating so that the composite coating has a same or similar coefficient of thermal expansion (CTE) as the substrate. In some cases, the CTE of the composite coating is different than that of the substrate in order to ensure symmetrical internal forces (or otherwise ensure that the resulting textured glass member is flat). 
       FIG.  1 A  shows an example electronic device  100  (also referred to herein simply as a “device”). The device  100  shown in  FIG.  1 A  is a mobile phone (e.g., a smartphone), but this is merely one representative example of a device that may be used in conjunction with the ideas disclosed herein. Other example devices include, without limitation, music/media players, tablet computers, laptop computers, wearable electronic devices, watches (e.g., mechanical, electrical, or electromechanical), and the like. 
     The electronic device  100  includes a housing  102  that includes a first glass member  106  and a second glass member  108 . The first glass member  106 , which may be referred to as a cover member, may cover or otherwise overlie a display and/or a touch sensitive surface (e.g., a touchscreen) of the device  100 , and may define an exterior front surface of the device  100 . Where the first glass member  106  overlies a display (e.g., a touch-sensitive display assembly  111 ), it may be transparent so that graphical outputs displayed by the display are visible through the first glass member  106 . The first glass member  106  may also define one or more openings, such as opening  112 , to allow internal components such as microphones, cameras, speakers, sensors, and the like, to have access to the surrounding environment of the device  100 . The second glass member  108  may define an exterior back surface of the device  100 . The first and second glass members  106 ,  108  may define the entire front and back surfaces, respectively, of the electronic device. 
     The first and second glass members  106 ,  108  may be attached to a housing member  110 . The housing member  110  may define at least a portion of the side surfaces of the device  100 . The housing member  110  may be formed from or include metal, glass, polymer, ceramic, composite, or any other suitable material or combination of materials. The first and second glass members  106 ,  108  may be attached to the housing member  110  via any suitable means, including adhesives, fasteners, glass frit bonds, welds, solder joints, or the like. 
     Either or both of the first and second glass members  106 ,  108  may include a tactile surface or texture. As used herein, a tactile surface or tactile texture may refer to a surface or texture that produces a tactile feel when touched or held by a user (e.g., by a user&#39;s finger). Tactile surfaces and textures may have a particular surface roughness (e.g., a surface roughness above a threshold value) and may have a different tactile feel than a conventional smooth or polished glass surface. In some cases, a “tactile surface” or a “tactile texture” may have or correspond to an average surface roughness value between about 0.1 microns and about 10 microns, between about 0.1 microns and about 5 microns, between about 1 micron and about 10 microns, between about 5 microns and about 8 microns, or any other suitable average surface roughness. 
     Either or both of the first and second glass members  106 ,  108  may be formed from or include a single layer or multiple layers. In the latter case, the multiple layers may be multiple glass layers, combinations of glass and other materials (e.g., plastics, polymers, ceramics, sapphire, etc.), coating layers, oleophobic coatings, paints, inks, or the like. 
     The textured surface may extend over any amount of either glass member. For example, the exterior surfaces defined by the first and second glass members  106 ,  108  may be textured. In some cases, only one or the other of the first and second glass members  106 ,  108  has a textured surface (e.g., the second glass member  108  may have a textured surface while the first glass member  106  is polished smooth or otherwise lacks the surface texture of the second glass member  108 ). In some cases, both the first and second glass members  106 ,  108  are textured, but the textures are different (e.g., they differ in surface roughness, haziness, glossiness, roughness, transmissivity, transparency, translucency, opacity, or the like). 
     In some cases, a non-glass member may be used instead of either or both of the first and second glass members  106 ,  108 . For example, either member may instead be a plastic member, ceramic member, sapphire member, metal member, or the like. Regardless of the exact materials or structures of the housing  102  of the device  100 , glass members may be textured as described herein. 
       FIG.  1 B  shows the back of the device  100 , As noted above, the second glass member  108  may define an exterior back surface of the device  100 . The second glass member may have a textured surface  114 , which may be produced by bonding a composite coating to a glass substrate. The textured surface  114  may improve the functionality of the device  100  in various ways. For example, as compared to a smooth glass surface (e.g., coated or uncoated polished float glass), the textured surface  114  may produce a particular tactile texture that makes the device  100  easier or more comfortable to hold. Further, the textured surface  114  may be less likely to show fingerprints or smudges than a smooth glass surface. The textured surface  114  may be configured to have a particular surface roughness to achieve a particular tactile texture, coefficient of friction, and/or appearance. For example, the textured surface  114  may have an average surface roughness (Ra) between about 0.1 microns and about 10 microns, between about 0.1 microns and about 3 microns, between about 0.2 microns and about 0.4 microns, between about 1 micron and about 10 microns, between about 5 microns and about 8 microns, or any other suitable average surface roughness. 
     The textured surface  114  may also be visually obscure components under the second glass member  108 . In some cases, the composite coating that forms the textured surface  114  may be mixed with or include a pigment, or ink, which may increase the opacity of and impart a color to the second glass member  108 . The textured surface  114  is shown in  FIG.  1 B  as extending over the entire exterior surface of the second glass member  108 . In some cases, the textured surface  114  may cover only a portion of a surface of a glass member, as shown and described herein with respect to  FIG.  6   . 
     Either or both of the first and second glass members  106 ,  108  may be chemically strengthened to improve the strength, hardness, toughness, or other physical property of the glass members. For example, the first and second glass members  106 ,  108  may be formed from or include aluminosilicate glass substrates that have been subjected to chemical strengthening processes. Other substrate materials are also possible, including, without limitation, borosilicate glass, soda lime glass, sapphire, ceramics, polymer materials, or the like. 
       FIG.  1 C  depicts a partial cross-sectional view of the electronic device  100  of  FIGS.  1 A and  1 B  along line A-A in  FIG.  1 A . The housing member  110  and the first and second glass members  106 ,  108  at least partially define an interior volume for receiving electronic components. As shown, the second glass member  108  defines the textured surface  114  along the exterior back side of the device  100 . In some cases, an interior surface  120  of the second glass member  108  may have a lower surface roughness than the exterior surface. For example, the interior surface  120  may lack a composite coating and as such may correspond to the bare surface of the glass substrate of the second glass member  108 . 
     As depicted in  FIG.  1 C , the device  100  includes a display  116  that is at least partially positioned within the interior volume of the housing  102 . In this example, the display  116  is coupled to the first glass member  106 . The display  116  may include a liquid-crystal display (LCD), light-emitting diode, organic light-emitting diode (OLED) display, an active layer organic light emitting diode (AMOLED) display, organic electroluminescent (EL) display, electrophoretic ink display, or the like. 
     As depicted in  FIG.  1 C , a component  118  is positioned at least partially within the interior volume. In this example, the component  118  is coupled to the second glass member  108 , though in other examples it may be secured to the housing  102  in a different manner. For example, the electronic device  100  may include one or more of a display, an input device, a sensor, memory, a processor, control circuitry, a battery, a circuit board, a frame or other supporting structure, an antenna, or the like. Additional or different components may also be positioned within housing  102 . The electronic device  100  may include various systems and/or components that can receive information from or about a user or the user&#39;s surroundings (e.g., touchscreens, microphones, biometric sensors, GPS systems). It is well understood that the use of personally identifiable information (such as information from or about a user or the user&#39;s environment and that is stored on or accessible by a device) should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
       FIG.  2 A  is a cross-sectional view of a glass member  200  having a textured surface. The glass member  200  may be an embodiment of the second glass member  108  of  FIGS.  1 A- 1 C , or any other glass member described herein (e.g., the first glass member  106 ). The glass member  200  defines a first surface  202  and a second surface  204 . The second surface  204  may define a surface texture resulting from a fused composite coating being bonded to a glass substrate and producing a particular tactile texture (e.g., feel) and appearance, as described above. As such, the glass member  200  may be integrated with an electronic device such that the second surface  204  defines an exterior surface of the device. 
     The surface roughness of the second surface  204  may be any suitable surface roughness to produce a particular tactile texture and appearance. For example, the surface roughness of the second surface  204  may have a surface roughness (Ra) between about 0.1 microns and about 10 microns, between about 0.1 and about 3 microns, between about 0.2 microns and about 0.4 microns, between about 1 micron and about 10 microns, between about 5 microns and about 8 microns, or any other suitable average surface roughness. The second surface  204  may also have particular optical properties that are selected to produce a desired functionality and/or appearance. For example, the second surface  204  may have a particular haziness, glossiness, roughness, transmissivity, transparency, translucency, and/or opacity. These properties may affect various functions of the exterior surface. For example, a surface with a higher glossiness may have a lower coefficient of friction as compared to a surface with a lower glossiness, and as such may affect the ease of use of a device. Particular values of properties such as surface roughness, haziness, glossiness, roughness, transmissivity, transparency, translucency, and opacity may be achieved by bonding a composite coating to a glass substrate, and by selecting particular materials and particular physical characteristics of the composite coating. 
     The first surface  202  may define an interior-facing surface. As shown, the first surface  202  may have a surface roughness that is less than that of the second surface  204 . In some cases, the surface roughness (Ra) of the first surface  202  may be below about 1 micron, below about 500 nanometers, below about 100 nanometers, or below about 10 nanometers. The first surface  202  may be polished to achieve a desired surface roughness, or the surface may be untreated after manufacturing and/or forming of the glass member  200 . For example, the surface roughness of the first side  202  may correspond to the surface that is produced as a result of a float glass manufacturing process. 
     As noted above, the second surface  204  may be defined by a fused composite coating  208  that is fused together and bonded to a portion of a glass substrate  206 .  FIG.  2 A  illustrates a boundary between the glass substrate  206  and the fused composite coating  208  with a dashed line, though this is merely illustrative, and the manner in which the fused composite coating  208  is bonded to the glass substrate  206  may result in a boundary that is not straight, flat, or distinct. For example, the fused composite coating  208  may be bonded to the glass substrate  206  by heating glass frit on the glass substrate  206  until the frit and the glass substrate  206  fuse together. 
     The glass substrate  206  may be formed of any suitable type of glass or other suitable material. For example, the glass substrate  206  may be an aluminosilicate glass, such as a lithium aluminosilicate glass. Other example materials may include soda lime glass, borosilicate glass, crystal glass, or the like. The glass substrate  206  may be of any suitable thickness. For example, the glass substrate  206  may have a thickness of about 2.0 mm, 1.5 mm, 1.0 mm, 0.8 mm, 0.5 mm, or any other suitable thickness (including any thickness between about 0.5 mm and about 2.0 mm). 
     The fused composite coating  208  may be formed of or include any suitable materials. For example, the fused composite coating  208  may include a matrix material and a particulate material dispersed within the matrix material. As another example, the fused composite coating  208  may include a matrix material without a separate particulate material. The matrix material may be fused together and may be bonded to the underlying substrate  206  to form a single unitary textured glass member. For example, the matrix material of the fused composite coating  208  may intermingle with the material of the substrate  206  such that it bonds directly to the substrate  206  without any interstitial adhesives or bonding layers. 
     The fused composite coating  208  may have a thickness that is less than that of the substrate  206 . For example, the fused composite coating  208  may have a thickness between about 1 micron and about 100 microns, or between about 1 micron and about 50 microns, or between about 2 microns and about 20 microns. The substrate  206  may have a thickness between about 0.2 mm and 2.0 mm, between about 0.5 mm and about 1.5 mm, between about 0.6 mm and about 1.0 mm, or any other suitable thickness. 
     The fused composite coating  208  may also include an ink, pigment, or other component that increases the opacity of the fused composite coating  208  and/or imparts a color to the fused composite coating  208 . For example, the fused composite coating  208  may include a white pigment that produces a glass member with a white, opaque appearance. The pigment may be integrated with or form part of the matrix of the composite coating  208 , or it may remain at least partially in particulate form and may contribute to the surface roughness of the glass member  200 . 
       FIG.  2 B  illustrates a detail view of a portion of the glass member  200 , corresponding to area B-B in  FIG.  2 A , illustrating one example composition of the fused composite coating  208 . In this example, the fused composite coating  208  includes a matrix material  210  and a particulate material  212  dispersed within the matrix material  210 . As shown, particles of the particulate material  212  partially protrude from the matrix material  210  to define the surface texture and/or roughness of the second surface  204  of the glass member  200 . The matrix material  210  may be fused together to form a rigid and/or secure matrix that holds the particulate material  212  in place and that bonds the composite coating  208  to the glass substrate  206 . 
     As described herein, the fused composite coating  208  may be formed by applying a composite coating that includes glass frit and the particulate material  212 . The glass frit may have a melting and/or softening temperature that is below that of the substrate  206  and also below that of the particulate material  212 . The composite coating  208  is then heated above the softening temperature of the glass frit and below the softening temperature of the particulate material  212  and then cooled, thereby fusing the glass frit and bonding the glass frit to the substrate  206 . In this way, the glass frit forms the matrix material  210  that secures the particulate material  212  in place and allows the particulate material  212  to define the surface roughness of the second surface  204 , and also bonds the fused composite coating to the substrate  206 . 
     The matrix material  210  and the particulate material  212  may be formed from any suitable materials. For example, the matrix material  210  may be an amorphous glass that originated as a glass frit material. The particulate material  212  may be a different amorphous glass, such as a glass frit that has a higher melting and/or softening temperature than the matrix material  210 . As another example, the particulate material  212  may be a crystalline material that has a higher melting and/or softening temperature than the matrix material  210 . Example crystalline materials include crystalline ceramic materials, crystalline quartz, or the like. In either case, because the melting and/or softening temperature of the particulate material  212  is higher than that of the matrix material, at least some particles of the particulate material may remain physically distinct from the matrix material  210  (e.g., having well-defined material boundaries) and may protrude from the matrix material  210  to define the surface roughness of the glass member  200 . 
     The density of the particulate material  212  within the matrix material  210  (as well as the size and shape of the particulate material  212 ) may be selected so as to produce a target surface roughness or other parameter. For example, larger particles may be selected to produce higher surface roughness, and rounder or more spherical particles may be selected to produce a higher gloss. Further, while  FIG.  2 B  illustrates particulate material  212  having a generally uniform composition, shape, and size, the fused composite coating  208  may have multiple particulate materials, such as two or more particulate materials having different average particle sizes, shapes, compositions, or the like. 
       FIG.  2 C  illustrates a detail view of a portion of the glass member  200 , corresponding to area B-B in  FIG.  2 A , illustrating another example composition of the fused composite coating  208 . In this example, the fused composite coating  208  includes a matrix material  220  without distinct particulates. In this example, the surface irregularity of the matrix material itself may define the surface roughness. The surface irregularity of the matrix material  220  may be formed by applying a glass frit material to the substrate  206  and then heating the glass frit until it softens and flows sufficiently to form a continuous layer while also maintaining a particular surface roughness. In some cases, the roughness and/or irregularity of the surface may generally correspond to the shape of the glass frit particles along the top of the coating. That is, because the coating starts as a glass frit powder, the irregular surface defined by the powder may remain at least somewhat irregular even after the powder is allowed to fuse to form a solid, continuous coating. 
     As described above, glass members with textured surfaces may be chemically strengthened to improve strength, toughness, or other physical property of the glass members. Chemical strengthening may include exchanging first ions in a glass member for larger second ions at a temperature below the strain point of the glass, thereby producing one or more compressive stress layers or regions in a portion of the glass member. The first ions may be first alkali metal ions and the second ions may be larger second alkali metal ions. For example, in the case of a lithium aluminosilicate glass substrate, the substrate may have a base composition (prior to ion exchange) which includes lithium ions, and at least some of the lithium ions may be exchanged for sodium ions and/or potassium ions during the ion-exchange operations. 
     Because chemical strengthening operations change the internal stresses in a glass substrate, such operations may result in changes to the shape and/or configuration of a substrate. In the case of a planar sheet, the symmetry of the sheet may result in substantially symmetrical internal stresses, resulting in little or no distortion or warping of the sheet. However, when a fused composite coating is applied to one surface of the substrate, the coated and uncoated surfaces may react differently to the chemical strengthening process which may result in warpage or distortion of the substrate. Accordingly, the fused composite coating may be selected so that the effects of a chemical strengthening process are sufficiently balanced to avoid or limit such warpage or distortion.  FIGS.  3 A- 3 C  illustrate examples of ion exchanges that may occur during the production of a textured glass member as described herein. 
       FIG.  3 A  illustrates a cross-sectional view of a glass member  300 , which may be an embodiment of the glass member  200  or any other glass member described herein, after a composite coating  302  is fused together and bonded to a substrate  304 . The fused composite coating  302  may include a matrix material that includes a glass frit having sodium ions, and the substrate  304  may include a glass having lithium ions (e.g., lithium aluminosilicate glass).  FIG.  3 A  shows an example ion exchange that may have occurred during the process of fusing the composite coating  302  and bonding the composite coating  302  to the substrate  304 . For example, when the composite coating is heated to perform the fusing and bonding operations, the heat may cause lithium ions from the substrate  304  to exchange for sodium ions in the fused composite coating  302 . 
       FIG.  3 B  illustrates the glass member  300  after the glass member  300  of  FIG.  3 A  is subjected to an ion-exchange bath or other ion-exchange process. For example, the glass member  300 , which includes the substrate  304  and the fused composite coating  302 , may be placed in an ion-exchange bath that includes a molten ionic salt (e.g., molten potassium salt, such as potassium nitrate). As a result of the ion-exchange bath or other chemical strengthening process, additional ion exchanges may occur in the glass member  300 . For example, lithium ions in the substrate  304  may be exchanged, through a first surface  306  of the glass member  300 , with potassium ions from the ion-exchange bath, as illustrated in  FIG.  3 B . Sodium ions may also be exchanged through the first surface  306  into the ion-exchange bath. 
     Additionally, as depicted in  FIG.  3 B , lithium ions may also be exchanged, through a second surface  308  of the glass member  300 , with potassium ions from the ion-exchange bath. The lithium ions may migrate from the substrate  304  into the ion-exchange bath. Additionally, lithium ions may migrate from the fused composite coating  302  into the ion-exchange bath. The composite coating, prior to being fused, may not contain lithium ions. Accordingly, the lithium ions that migrate out of the fused composite coating  302  may have migrated into the composite coating  302  from the substrate  304  during fusion and bonding of the coating  302 , as described with respect to  FIG.  3 A . 
     Sodium ions may migrate from the fused composite coating  302  into the ion-exchange bath. Additionally, sodium ions may migrate from the substrate  304  and into the ion-exchange bath. The sodium ions in the substrate  304  may have migrated into the substrate  304  from the fused composite coating  302  during fusion and boding of the coating  302 , as described with respect to  FIG.  3 A . Potassium ions may penetrate through the fused composite coating  302  and into the material of the substrate  304 , as shown in  FIG.  3 B . In other cases, the potassium ions may penetrate into the fused composite coating  302 , but not reach the substrate  304 . 
       FIG.  3 C  shows the glass member  300  after the glass member  300  is subjected to a chemical strengthening process (which may result in the ion exchanges described with respect to  FIGS.  3 A- 3 B ). In particular, the glass member  300  (which includes the substrate  304  and the fused composite coating  302 ) may have a first ion-exchanged layer  310  extending into the glass member  300  through the first surface  306  and having a first thickness  316  (e.g., extending a first depth into the glass member  300 ). The glass member  300  may also have a second ion-exchanged layer  314  extending into the glass member  300  through the second surface  308  and having a second thickness  318  (e.g., extending a second depth into the glass member  300 , optionally through the entire fused composite coating  302 ). The first and second thicknesses  316 ,  318  may be equal or they may be different. In some cases, the ion-exchanged layers  310 ,  314  may be different segments of a contiguous layer. For example, the ion-exchanged layers may be formed by submerging the glass member into an ion-exchange bath, as described herein, which may cause ions to be exchanged along all surfaces of the glass member. It will be understood that while the first and second ion-exchanged layers  310 ,  314  may be referred to as different layers, they may be different segments or areas of a single contiguous layer. 
     The first and second ion-exchanged layers  310 ,  314  may each have a compressive stress profile or gradient, and the glass member  300  may have a region  312  between the first and second ion-exchanged layers  310 ,  314  that has a tensile stress profile. The compressive stress profiles of the first and second ion-exchanged layers  310 ,  314  may be the same or they may be different from each other, but they may be balanced so that the glass member  300  does not significantly warp or bend as a result of the chemical strengthening profile. More particularly, in some cases the first ion-exchanged layer  310  may have a different thickness or depth of layer than the second ion-exchanged layer  314 . In such case, the peak compressive stress in the thinner layer may be greater than the peak compressive stress in the thicker layer. In this way, the glass member  300  may remain substantially flat even after chemical strengthening and despite the fact that the fused composite coating  302  may respond to chemical strengthening differently than the substrate  304 . Further, the first and second ion-exchanged layers  310 ,  314  may each have different compositions (e.g., they may have different types, amounts, concentrations, or combinations of ions). For example, the first ion-exchanged layer  310  may include lithium ions (from the substrate  304 ) and potassium ions (from the ion-exchange bath), while the second ion-exchanged layer  314  may include sodium ions (from the fused composite coating  302 ), lithium ions (from the substrate  304 ), and potassium ions (from the ion-exchange bath). The first ion-exchanged layer  310  may lack sodium ions, as the sodium ions in the second ion-exchanged layer  314  originated from the composite coating, which is not applied to the first surface  306 . Thus, the first ion-exchanged layer  310  may have a composition that includes potassium and lithium (and may lack sodium), and the second ion-exchanged layer  314  may have a different composition that includes potassium, lithium, and sodium. In some cases, the first ion-exchanged layer may include sodium ions from other sources, but not from the composite coating. In such cases, the concentration of sodium ions in the first ion-exchanged layer  310  may be different than (e.g., less than) the concentration of sodium ions in the second ion-exchanged layer  314 . In some cases, the ion concentrations of the potassium and lithium (and any other ions from chemical strengthening processes (or otherwise) that may be present in the textured glass member) may differ between the first and second ion-exchanged layers  310 ,  314 . 
     One property of a material that may affect how it responds to chemical strengthening is the coefficient of thermal expansion (CTE) of the material. The CTE of an uncoated, uniform material may be substantially uniform along all of its surfaces. A glass member with a substrate that is coated only on one side or only in localized areas may have areas having different CTEs. The difference in CTEs may result in warping and/or distortion of the glass member as a result of the chemical strengthening process. Accordingly, the material(s) of the fused composite coating  302  may be selected so that the CTE of the fused composite coating  302  is the same as that of the substrate  304 . In cases where the fused composite coating  302  comprises multiple different materials, the CTE may be an effective CTE of the fused composite coating  302 . For example, the fused composite coating  302  may include materials having CTEs higher than the substrate  304  mixed with materials having lower CTEs than the substrate, thereby producing a coating that has a CTE that is similar to or the same as the substrate. As noted above, a fused composite coating  302  may include an amorphous matrix material and particles of crystalline material. In such cases, the crystalline materials may have a lower CTE than the amorphous matrix material, and as such the crystalline materials may offset the higher CTE of the matrix materials. 
     In some cases, it may be beneficial for the CTE of the fused composite coating  302  to be different than that of the substrate  304 . For example, the types and concentrations of ions in a fused composite coating may cause the coated side of a glass member to react differently to a chemical strengthening bath, as compared to an uncoated side. Thus, in some cases configuring the fused composite coating to have a different CTE than the substrate itself may actually limit or minimize warping or bending of the glass member. 
     As shown in  FIG.  3 C , the second ion-exchanged layer  314  (and thus the compressive stress profile associated with the second ion-exchanged layer  314 ) is thicker than the thickness of the fused composite coating  302 . This reflects the ion-exchange behavior illustrated in  FIGS.  3 A- 3 B , where sodium ions and/or potassium ions penetrate through the fused composite coating  302  and into the substrate  304 . In other examples, however, the second ion-exchanged layer  314  (at least with respect to potassium ions) is less thick than the fused composite coating  302 . The lines shown in  FIG.  3 C  to illustrate the first and second ion-exchanged layers  310 ,  314  are merely illustrative, and it will be understood that the actual boundary of an ion-exchanged layer may not be as distinct as the lines shown in  FIG.  3 C . The boundaries of the ion-exchanged layers  310 ,  314 , such as those shown in  FIG.  3 C , may correspond to a particular concentration of a particular ion (e.g., where a concentration of potassium ions is below a threshold value), or to a particular internal stress value (e.g., where the internal stress is zero or crosses from a compressive stress to a tensile stress). 
       FIG.  4    is a flow chart of an example process  400  for producing textured glass members. Textured glass members produced according to this process may be used as components of electronic devices, such as tablet computers, mobile phones, watches or other wearable electronic devices, notebook computers, or the like. Further, any of the textured glass members described herein may be produced according to this process. 
     At operation  402 , a composite coating is applied to a surface of a substrate. The substrate may be any suitable substrate, as described herein. For example, the substrate may be an aluminosilicate glass substrate, a borosilicate glass substrate, a soda-lime glass substrate, or any other suitable glass substrate. The composite coating as applied may have any suitable depth. For example, the composite coating may have a thickness between about 1 micron and about 100 microns, or between about 1 microns and about 50 microns, or between about 2 microns and about 20 microns. 
     The composite coating may include various different components. For example, the composite coating may include powders or particulates that produce the tactile, textured surface of the glass member. Such particulates may include glass frit, powders of crystalline materials, ceramics, or the like. More particularly, as described herein, the composite coating may include one or more types of glass frit as well as one or more crystalline materials, and optionally additional solid (e.g., particulate) or liquid materials (e.g., non-glass materials, pigments, inks, filler materials, etc.). 
     The composite coating may also include materials that facilitate application of the composite coating and the formation of the fused composite coating, such as solvents, resins, emulsifiers, stabilizers, or the like. For example, the composite coating may include a solvent (e.g., a liquid solvent) that allows the composite coating to be applied to the glass substrate via pad printing, spraying, screen printing, or the like. The composite coating may also include a resin or other material that may harden or cure to stabilize the composite coating prior to the coating being fused together and bonded to the substrate. The composite coating may also include pigments, inks, colorants, or other materials that impart a particular color, opacity, or other visual property or characteristic to the composite coating. The composite coating may be or may resemble a liquid or a slurry. 
     The composite coating may be applied to the substrate using any suitable application process. For example, the composite coating may be applied using pad printing, screen printing, spraying, or any other application technique. The composite coating may be applied to any amount or portion of the substrate. For example, the composite coating may be applied to one side of the substrate (e.g., only one side). As another example, it may be applied to two sides of the substrate (e.g., a front and a back side). As yet another example, it may be applied to every surface of the substrate. In some cases, it may be applied to only localized regions of a surface of the substrate. For example, it may be applied in the shape of a logo, indicia, text, an image, a frame or border, or the like. 
     At operation  404 , after the composite coating is applied to the substrate, the composite coating may be dried. Drying the coating may include heating the coating (and optionally the substrate) to evaporate, dry, or otherwise remove the solvent(s) in the composite coating. The drying may include heating the coating to a temperature below a softening temperature of the substrate and the glass frit and crystalline materials of the composite coating. 
     At operation  406 , after the composite coating is dried, the composite coating and the substrate may be heated to fuse the composite coating (or at least portions of the composite coating), thereby forming a fused composite coating and bonding the fused composite coating to the substrate. Heating the substrate and the composite coating may include placing the coated substrate in a furnace or oven and heating the coated substrate at a target temperature for a duration. The target temperature and duration may depend at least in part on the composition of the composite coating, the composition of the substrate, the desired amount of flowing, melting, or softening of the composite coating, the thickness or other dimension of the substrate and/or the composite coating, or the like. In some cases, the temperature at which the coated substrate is heated is above a softening temperature of a glass frit material in the composite coating and below a softening temperature of the substrate (and optionally below a softening temperature and/or the melting temperature of an additional glass or crystalline material in the composite coating). In this way, the glass frit may flow and/or fuse together, and also bond to the substrate, without the substrate becoming hot enough to deform, flow, or melt. 
     In some cases, the heating profile may include heating the coated substrate at multiple different temperatures for different durations (e.g., heating at a first temperature for a first duration, and subsequently heating at a second temperature for a second duration). In some cases, the coated substrate itself reaches the target temperature (e.g., the coated substrate may be heated to the target temperature). Regardless of the particular heating profile or process used, the temperature(s) and duration(s) of heating may result in the composite coating becoming a solid, fused coating that is bonded to the underlying substrate, thus forming a textured glass member. 
     At operation  408 , the textured glass member produced by fusing the composite coating to the substrate (at operation  406 ) is chemically strengthened. Chemically strengthening the textured glass member may include submerging the textured glass member in an ion-exchange bath. The particular ion-exchange bath, as well as the temperature of the bath and the duration that the textured glass member is submerged in the bath, may be selected based at least in part on the composition of the substrate and/or the composite coating, a target depth of ion penetration layer(s), a target strength of the textured glass member, a target flatness of the textured glass member, or the like. 
     The ion-exchange bath may result in the exchange of ions between the ion-exchange bath and the substrate and/or the fused composite coating, resulting in ion-exchanged layers in the textured glass member. Example ion-exchanged layers that may result from the operation  408  are described with respect to  FIGS.  3 A- 3 C . 
     The ion-exchange bath may comprise a molten ionic salt. For example, when potassium ions are to be introduced into the textured glass member, the ion-exchange bath may comprise potassium nitrate or another suitable potassium salt. The concentration of the potassium salt may be from 30 mol % to 100 mol %. In embodiments, the concentration of potassium salt is greater than 50 mol %. In further embodiments, the ion-exchange bath may further comprise additional alkali metal ions in a lesser amount, such as sodium ions. The time the cover spends in the ion-exchange bath may be from 15 minutes to 4 hours. 
     The ion-exchange bath temperature may be from the melting point of the salt to approximately 600° C., or any other suitable temperature that is high enough to facilitate ion exchange without causing the textured glass member to melt or flow to a degree that it loses its general shape. In some cases, the temperature of the ion-exchange bath may be below a strain point or a glass transition point of the substrate, so that exchanging alkali metal ions in the glass and/or the fused composite coating with larger alkali metal ions tends to cause an expansion of an ion-exchanged zone of the textured glass member. However, expansion of the ion-exchanged layer of the textured glass member may be constrained by a remainder of the textured glass member which is not ion-exchanged. As a result, a compressive stress region, such as a biaxial residual compressive stress region, may be created in the ion-exchanged layer. 
     In some cases, the operation  408  of chemically strengthening the textured glass member may include more than one ion-exchange bath. For example, the textured glass member may be subjected to two or more ion-exchange baths (or other ion exchange processes). The ion-exchange baths may have different compositions (e.g., different exchangeable ions) and/or different temperatures, and the textured glass member may be subjected to the different baths for different durations. 
     In some cases, additional or fewer operations may be used to form the textured glass members described herein. For example, additional operations not described with respect to the process  400  may be employed (including but not limited to additional heating operations, curing operations, coating operations, polishing or other machining operations, or the like). Further, operations of the process  400  may be reordered and/or omitted. Other modifications or adjustments are also contemplated. 
     After the textured glass member is chemically strengthened, it may be coupled to a housing member of an electronic device. In some cases the textured glass member is coupled to the housing member such that the fused composite coating defines an exterior surface of the electronic device. For example, where the electronic device is a mobile phone, as described with respect to  FIGS.  1 A- 1 C , the textured glass member may define a back of the mobile phone, and the fused composite coating may define an exterior back surface of the device. 
       FIG.  5 A  illustrate cross-sectional views of a substrate  502  and a composite coating  504  after the composite coating  504  is applied to the substrate  502  and before the composite coating  504  is fused.  FIG.  5 B , described below, illustrates the substrate  502  after the composite coating  504  has been fused. 
     As noted above, a composite coating may include multiple different particulates. As shown in  FIG.  5 A , the composite coating  504  may include a glass frit  506  and particles of a crystalline material  508  (also referred to herein simply as “crystalline particles”). The glass frit  506  may have an average particle size. For example, the average particle size of the glass frit  506  may be between about 0.10 and 0.50 microns, between about 0.50 and 1.0 microns, between about 1.0 and 5.0 microns, or any other suitable size. The glass frit  506  may be formed from any suitable type of glass. The glass frit  506  may be a single composition of glass (e.g., all particles are of the same glass), or a combination of different glasses (e.g., the glass frit  506  is a combination of two or more different glasses). In cases where the glass frit  506  includes multiple types of glasses, the different glasses may have different average particle sizes. 
     The crystalline particles  508  may have an average particle size that may be the same as or different from the average particle size of the glass frit  506 . For example, the crystalline particles  508  may have an average particle size between about 0.10 and 0.50 microns, between about 0.50 and 1.0 microns, between about 1.0 and 5.0 microns, or any other suitable size. The crystalline particles  508  may be substantially homogenously or evenly distributed in the glass frit  506  to form a textured surface having a uniform appearance and/or tactile feel. 
     The composite coating may include other materials as well. For example, as described herein, the composite coating  504  may include pigments, inks, filler materials, non-glass particulates, or the like. Such additives or materials may be configured to produce a desired visual, optical, or physical property of the final resulting coated glass member, or to improve or change how the composite coating behaves during processing. 
       FIG.  5 B  shows the composite coating  504  after the glass frit  506  has fused to form a solid matrix  510  and to bond to the substrate  503 . As shown, the crystalline particles  508  may be substantially unchanged as a result of the fusing operation, and at least some of the crystalline particles  508  may protrude from the matrix  510  and define a textured, tactile surface of the textured glass member. In some cases, some of the crystalline particles may become amorphous as a result of heating that accompanies fusing the glass frit and/or chemically strengthening the textured glass member. For example, some of the crystalline particles  508  may become entirely amorphous, and may flow or soften so that they no longer maintain their shape (and do not protrude from the matrix  510  and/or become part of the matrix  510 ). As another example, some portion of individual crystalline particles  508  may become amorphous, which may change the size and/or shape of those particles but otherwise does not cause the crystalline particles  508  to lose their overall physical distinctiveness from the matrix  510  and their ability to define the surface roughness of the coating. 
       FIG.  5 B  shows that some of the particles of the glass frit  506  remain un-melted and/or retain a distinct physical shape and/or presence in the matrix  510  after the glass frit is otherwise fused. In other cases, none of the glass frit remains in this state, and all of the glass frit has been melted and/or flowed into a single amorphous mass. 
     As shown in  FIG.  5 B , the textured glass member  501  does not have significant cracks formed along the exterior surfaces. More particularly, the surface texture and resulting tactile feel of the surface of the textured glass member  501  is defined by the matrix  510  and the crystalline particles  508  (or, in the case of a coating without crystalline particles, a solid textured glass layer formed from a glass frit), rather than via cracks or fractures that may be produced as a result of chemical or physical etching. Accordingly, the textured glass member  501  may have a high strength and/or toughness and may provide a stable physical configuration for chemical strengthening. 
     Various properties of the composite coating may define or impact physical properties or characteristics of the textured glass member and the surface roughness of the fused composite coating. For example, the particular particle sizes of the glass frit  506  and the crystalline particles  508 , as well as the differences in size between the glass frit  506  and the crystalline particles  508 , may. More particularly, glass frit  506  and/or crystalline particles  508  having larger sizes may produce rougher surface textures. Also, the differences in CTE between two materials (e.g., glass frit and crystalline particles) may affect the roughness, with greater differences in CTEs resulting in greater surface roughness (e.g., rougher textures). 
     Properties of the composite coating  504  may also define or impact optical properties of the textured glass member. For example, crystalline materials may be less transparent than glass materials. Accordingly, greater amounts of crystalline particles relative to glass frit may result in a less transparent (e.g., more translucent or opaque) textured glass member. Also, the extent to which components of the composite coating  504  are allowed to melt or flow during fusing may affect the transparency of the resulting fused composite coating. For example, longer heating times and/or higher heating temperatures (which may increase the amount of melting, relaxing, and/or flowing of components of the composite coating) may result in higher transparency relative to lower times or temperatures. 
     As noted above, composite coatings may be applied to all or less than all of the surfaces of a glass substrate. For example, as shown and described above, a glass substrate may be coated along only those surfaces that define an exterior surface of an electronic device or electronic device housing.  FIG.  6    illustrates an example textured glass member  600  that has a fused composite coating over only a localized portion of the glass member  600 . For example, the textured glass member  600  defines a first surface  601  (which may correspond to a front or back exterior surface of an electronic device) and a second surface  605  opposite the first surface (which corresponds to the other of the front or back exterior surface of the electronic device). The first surface  601  includes a fused composite coating  602  over only a portion of the first surface  601 . As shown, the fused composite coating  602  defines a peripheral frame surrounding an un-coated central region  604 . The fused composite coating  602  may have a surface roughness as described herein. The second surface  605  of the glass member  600  may be entirely uncoated, or it may have a localized composite coating having a similar or identical positioning and/or layout as the fused composite coating  602  (e.g., defining a peripheral frame surrounding an uncoated central region). In other cases, the second surface  605  may have a localized fused composite coating having a different positioning and/or layout as the first surface  601 . 
       FIG.  7    depicts an example schematic diagram of an electronic device  700 . By way of example, the device  700  of  FIG.  7    may correspond to the electronic device  100  shown in  FIGS.  1 A- 1 C  (or any other electronic device described herein). To the extent that multiple functionalities, operations, and structures are disclosed as being part of, incorporated into, or performed by the device  700 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the device  700  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. 
     As shown in  FIG.  7   , a device  700  includes a processing unit  702  operatively connected to computer memory  704  and/or computer-readable media  706 . The processing unit  702  may be operatively connected to the memory  704  and computer-readable media  706  components via an electronic bus or bridge. The processing unit  702  may include one or more computer processors or microcontrollers that are configured to perform operations in response to computer-readable instructions. The processing unit  702  may include the central processing unit (CPU) of the device. Additionally or alternatively, the processing unit  702  may include other processors within the device including application specific integrated chips (ASIC) and other microcontroller devices. 
     The memory  704  may include a variety of types of non-transitory computer-readable storage media, including, for example, read access memory (RAM), read-only memory (ROM), erasable programmable memory (e.g., EPROM and EEPROM), or flash memory. The memory  704  is configured to store computer-readable instructions, sensor values, and other persistent software elements. Computer-readable media  706  also includes a variety of types of non-transitory computer-readable storage media including, for example, a hard-drive storage device, a solid-state storage device, a portable magnetic storage device, or other similar device. The computer-readable media  706  may also be configured to store computer-readable instructions, sensor values, and other persistent software elements. 
     In this example, the processing unit  702  is operable to read computer-readable instructions stored on the memory  704  and/or computer-readable media  706 . The computer-readable instructions may be provided as a computer-program product, software application, or the like. 
     As shown in  FIG.  7   , the device  700  also includes a display  708 . The display  708  may include a liquid-crystal display (LCD), organic light emitting diode (OLED) display, light emitting diode (LED) display, or the like. If the display  708  is an LCD, the display  708  may also include a backlight component that can be controlled to provide variable levels of display brightness. If the display  708  is an OLED or LED type display, the brightness of the display  708  may be controlled by modifying the electrical signals that are provided to display elements. The display  708  may correspond to any of the displays shown or described herein, such as the display  116  ( FIG.  1 C ) that is viewable through the first glass member  106 . 
     The device  700  may also include a battery  709  that is configured to provide electrical power to the components of the device  700 . The battery  709  may include one or more power storage cells that are linked together to provide an internal supply of electrical power. The battery  709  may be operatively coupled to power management circuitry that is configured to provide appropriate voltage and power levels for individual components or groups of components within the device  700 . The battery  709 , via power management circuitry, may be configured to receive power from an external source, such as an AC power outlet. The battery  709  may store received power so that the device  700  may operate without connection to an external power source for an extended period of time, which may range from several hours to several days. 
     In some embodiments, the device  700  includes one or more input devices  710 . An input device  710  is a device that is configured to receive user input. The one or more input devices  710  may include, for example, a rotatable input system, a push button, a touch-activated button, a keyboard, a key pad, or the like (including any combination of these or other components). In some embodiments, the input device  710  may provide a dedicated or primary function, including, for example, a power button, volume buttons, home buttons, scroll wheels, and camera buttons. 
     The device  700  may also include a sensor  724 . The sensor  724  may detect inputs provided by a user to one or more of the input devices  710  of the device  700 . The sensor  724  may also be a biometric sensor, such as a heart rate sensor, electrocardiograph sensor, temperature sensor, or any other type of sensor. In cases where the sensor  724  is a biometric sensor, it may include biometric sensing circuitry, as well as portions of a crown that conductively couple a user&#39;s body to the biometric sensing circuitry. Biometric sensing circuitry may include components such as processors, capacitors, inductors, transistors, analog-to-digital converters, or the like. 
     The device  700  may also include a touch sensor  720  that is configured to determine a location of a touch on a touch-sensitive surface of the device  700  (e.g., an input surface defined by the first or second glass members  106 ,  108 ). The touch sensor  720  may use or include capacitive sensors, resistive sensors, surface acoustic wave sensors, piezoelectric sensors, strain gauges, or the like. In some cases the touch sensor  720  associated with a touch-sensitive surface of the device  700  may include a capacitive array of electrodes or nodes that operate in accordance with a mutual-capacitance or self-capacitance scheme. The touch sensor  720  may be integrated with one or more layers of a display stack (e.g., the display  116 ,  FIG.  1 C ) to provide the touch-sensing functionality of a touchscreen. 
     The device  700  may also include a force sensor  722  that is configured to receive and/or detect force inputs applied to a user input surface of the device  700  (e.g., a surface of the first and/or second glass members  106 ,  108 ). The force sensor  722  may use or include capacitive sensors, resistive sensors, surface acoustic wave sensors, piezoelectric sensors, strain gauges, or the like. In some cases, the force sensor  722  may include or be coupled to capacitive sensing elements that facilitate the detection of changes in relative positions of the components of the force sensor (e.g., deflections caused by a force input). The force sensor  722  may be integrated with one or more layers of a display stack (e.g., the display  116 ) to provide force-sensing functionality of a touchscreen. 
     The device  700  may also include a communication port  728  that is configured to transmit and/or receive signals or electrical communication from an external or separate device. The communication port  728  may be configured to couple to an external device via a cable, adaptor, or other type of electrical connector. In some embodiments, the communication port  728  may be used to couple the device  700  to an accessory, including a dock or case, a stylus or other input device, smart cover, smart stand, keyboard, or other device configured to send and/or receive electrical signals. 
     While the device  700  is described as having a particular set of components, the device  700  is not limited to only those components described herein. For example, a device may include more than one of the components described with respect to  FIG.  7    or elsewhere in the instant application, and may indeed include other components not described herein. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. Also, when used herein to refer to positions of components, the terms above and below, or their synonyms, do not necessarily refer to an absolute position relative to an external reference, but instead refer to the relative position of components with reference to the figures.

Metadata:
Filing Date: 20191021
Publication Date: 20230704
Grant Date: 20230704
Priority Date: 20181218
Inventors: TATEBE, MASASHIGE
OSHIMA, TAKAHIRO
AKANA, JODY
CHINNAKARUPPAN, PALANIAPPAN
Deshpande, Tushar S.
NAKAJIMA, KENICHI
SANICHI, SHIGEHIRO
KATO, TAKASHI
TAKANO, KOJI
Assignee: APPLE INC
CPC Classifications: [{"code": "H01M50/1245", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C2203/52", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M50/124", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C3/083", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C17/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C21/002", "inventive": true, "first": true, "tree": "[]"}, {"code": "C03C2217/77", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C17/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "C03C21/002", "inventive": true, "first": true, "tree": "[]"}, {"code": "C03C17/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C2217/77", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C2217/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C2218/119", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C2218/13", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C2218/112", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C15/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02E60/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C2203/52", "inventive": false, "first": false, "tree": "[]"}, {"code": "C03C3/083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/124", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/1245", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C17/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "C03C2217/77", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 71072398