JP2019151534A - Cover glass and production method thereof - Google Patents

Abstract

To provide a cover glass comprising a curved region on a peripheral part, and a production method thereof.SOLUTION: A production method of the cover glass comprises at least, a protection step, a patterning step, an etching step and a chemical strengthening step. The protection step is a step for covering both principal surfaces of a glass preform 30 on which, a plurality of cover glasses 10 are formed with a protective film 32 having at least, etching resistance. The patterning step is a step for removing the protective film 32 on a region corresponding to at least a part of the peripheral part, on the second principal surface 36 of the glass preform 30. The etching step is a step for bringing the glass preform 30 into contact with an etchant, for forming a recess 38 on a region from which the protective film 32 is removed. The chemical strengthening step is a step for, after removing the protective film 32, performing chemical strengthening processing to whole region of the cover glass 10, for forming a chemical strengthening layer 40.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a cover glass having a curved region at a peripheral edge and a method for manufacturing the same.

  In recent years, a touch panel has been adopted in a wide range of fields as an interface when a user operates a device because of an advantage that an intuitive operation is possible. The cover glass for the touch panel is arranged on the side where the touch panel is exposed to the user, and is configured to accept a touch operation performed while the user visually recognizes a touch operation area where icons and the like are displayed. Due to the improved design due to the flatness of the cover glass and high transparency, the movement to replace with a touch panel has spread to devices that conventionally used physical buttons and keyboards. For example, in a portable electronic terminal such as a smartphone, most operations can be performed with a touch panel.

  Usually, the cover glass is manufactured by dividing into a desired individual glass substrate from a large glass base material, and the dividing process is generally performed by machining such as a scribe break process. is there. In recent years, there has been a demand for a cover glass that includes a curved region or a notch region in the contour portion for differentiation in terms of design, but the curved region or the notch region is divided using a scribing device. It was difficult to do.

  Thus, among the prior arts, there has been a technique for manufacturing a cover glass including a curved region or the like by dividing the glass substrate by etching (for example, see Patent Document 1). Furthermore, since it is possible to remove fine scratches on the end face by dividing by etching without performing machining such as scribe break, it is said that the strength of the cover glass is improved.

Japanese Patent No. 5654072

  The etching process can easily control the outer shape of the cover glass, but a convex protrusion is formed at the center in the thickness direction on the end surface of the cover glass. The protruding portion has a tapered shape, has low strength even in the end face, and may be damaged or chipped even with a slight impact. For this reason, it may be necessary to additionally perform an etching process or end face polishing after the dividing process to shorten the protruding distance of the protruding portion.

  Furthermore, some recent portable information terminals such as smartphones and tablets have a curved region for the purpose of design differentiation. For this reason, the cover glass must also be formed in a shape that follows the curved region, but productivity may be reduced by forming the curved region in the cover glass. An example of the bending process of the glass substrate includes a heat treatment process and mechanical polishing. In the heat treatment, the cover glass must be heated to the softening point and then processed with a mold or the like, and the productivity is low. The mechanical polishing process uses a polishing device such as a spindle. However, there are problems such as fine scratches on the glass substrate and a decrease in productivity when the polishing amount increases. Although it is conceivable to form a curved shape by an etching process, the shape that can be formed is limited due to the property that the etching process isotropically proceeds.

  The objective of this invention is providing the simple manufacturing method of the cover glass provided with the curved area | region in the peripheral part.

  The present invention is a cover glass composed of a single glass member, which is a flat central portion and a peripheral portion disposed around the central portion, from the first main surface to the second main surface. A cover glass manufacturing method including a peripheral portion having a curved region that is curved to the side, and includes at least a protection step, a patterning step, an etching step, and a chemical strengthening step. The protection step is a step of covering both main surfaces of the glass substrate for multi-faceting the cover glass with a protective layer having at least etching resistance. The patterning step is a step of removing the protective layer in a region corresponding to at least a part of the peripheral portion on the second main surface of the glass substrate. The etching step is a step of forming a recess in the region where the protective layer has been removed by bringing the glass substrate into contact with an etching solution. The chemical strengthening step is a process of forming a chemical strengthening layer over the entire area of the cover glass after removing the protective layer.

  By forming the chemical strengthening layer in a state where the concave portion is formed, a difference occurs in the total volume of the compressive stress layer on the first main surface side and the second main surface side in the peripheral portion. That is, the compressive stress is larger on the second main surface where the recess is formed. For this reason, the curved area | region where only a peripheral part curves toward the 2nd main surface side by the difference in compressive stress is formed.

  In addition, it is preferable that the method further includes a filling step of filling the concave portion with a transparent material after the chemical strengthening step. When the cover glass is attached in a state where the recess is formed, the visibility of the display image may be reduced due to the influence of refraction or the like in the recess. By filling the recess with a transparent material having the same optical characteristics as the cover glass, it is possible to suppress defects at the periphery.

  In the patterning step, the protective layer in a desired region can be removed. For example, only the boundary region between the central portion and the peripheral portion is patterned, or the outer peripheral portion of the central portion is patterned. It is also possible. The patterning process can be performed within a range in which a significant difference can be provided between the compressive stresses of the two main surfaces in the recess formed by the etching process.

  According to the present invention, it is possible to easily manufacture a cover glass having a curved region at the peripheral edge.

It is a figure which shows the outline of the cover glass which concerns on one Embodiment of this invention. It is a figure shown about the cover glass arrange | positioned on a portable information terminal. It is a figure shown about covering and patterning of the protective film to a glass base material. It is a figure shown about formation of the recessed part by the etching to a glass base material. It is a figure shown about formation of the compressive-stress layer to a cover glass. It is a figure shown about the cover glass with which the recessed part was filled with transparent resin. It is a figure shown about other patterning of the protective film coat | covered with the glass base material. It is a figure which shows the form of the cover glass in which the etching process of the cover glass and the compressive-stress layer were formed. It is a figure which shows an example of the other patterning of a cover glass. It is a figure which shows another embodiment about the shape of a recessed part.

  From here, the cover glass which concerns on one Embodiment of this invention using drawing is demonstrated. FIG. 1 is a view showing a cover glass 10 manufactured according to an embodiment of the present invention. The cover glass 10 is a glass substrate made of a single glass member having a first main surface 12 and a second main surface 14. The cover glass 10 includes a flat central portion 16 that occupies the central portion of the cover glass 10 and a peripheral edge portion 18 that is disposed around the central portion 16. The peripheral edge 18 has a curved region where the entire length of the cover glass 10 in the longitudinal direction is curved.

  The glass substrate used for the cover glass 10 is preferably aluminosilicate glass, but is not particularly limited, and soda glass or non-alkali glass may be used. The cover glass 10 preferably has a thickness of about 0.1 to 1.5 mm. The cover glass 10 has a compressive stress layer 40 formed thereon. The compressive stress layer 40 can be formed by a known ion exchange method, and the thickness of the formed compressive stress layer 40 is adjusted in the range of 5 to 100 μm. The compressive stress layer 40 is formed with almost the same thickness over the first main surface 12, the second main surface 14, and the end surface of the cover glass 10 of the cover glass 10.

  The central portion 16 is a flat region existing in the central portion of the cover glass 10. The thickness of the central portion 16 is preferably about 0.1 to 0.9 mm, but is not limited thereto. The peripheral edge 18 is an area formed on the peripheral edge of the cover glass 10. The peripheral edge portion 18 has a curved region that is inclined from the first main surface 12 side toward the second main surface 14 side in a region adjacent to the central portion 16. Moreover, the peripheral part 18 is comprised so that the 1st main surface 12 side may curve in convex shape toward the outer side. A boundary portion between the central portion 16 and the peripheral portion 18 is configured to have a rounded shape. The inclination angle of the peripheral edge 18 is appropriately adjusted according to the device to which the cover glass 10 is attached.

  The peripheral edge portion 18 is configured to be thinner than the central portion 16. As a plate | board thickness of the peripheral part 18, it is preferable that it is about 0.05-0.7 mm, and it is still more preferable that it is 0.4 mm or less. By reducing the plate thickness, the curved region can be easily formed. Further, the area of the peripheral edge portion 18 is formed to be relatively smaller than the area of the central portion 18. Specifically, the area of the peripheral portion 18 is preferably less than or equal to one half of the area of the central portion 16.

  Cover glass 10 can be used for portable information terminal 50 shown in Drawing 2 (A), for example. The portable information terminal 50 has an information display area 52 in the center. The information display area 52 is an area for displaying information such as icons on a flat panel display such as a liquid crystal display. Moreover, the peripheral part of the information display area 52 has a curved shape in a cross-sectional view.

  As shown in FIG. 2B, the cover glass 10 is arranged so that the central portion 16 corresponds to an area where the information display area 52 is arranged. Furthermore, since the cover glass 10 is curved so that the peripheral edge portion 18 corresponds to the curved shape of the end portion of the portable information terminal 50, the end portion of the portable information terminal 50 can be reliably protected. In the cover glass 101 having a flat shape, the end of the portable information terminal 50 is exposed as shown in FIG.

  From here, the manufacturing method of the cover glass 10 is demonstrated using FIGS. When manufacturing the cover glass 10, the large-sized glass base material 30 by which the several cover glass 10 was chamfered is normally used as shown in FIG. 3 (A). The cover glass 10 is formed into a desired shape by being divided into individual pieces from the glass base material 30. In the present embodiment, for the sake of convenience, processing for the glass base material 30 in which nine cover glasses 10 are arranged in a matrix of 3 rows and 3 columns will be described. However, the number of cover glasses 10 included in the glass base material 30 is increased or decreased as appropriate. Is possible. Moreover, although this embodiment demonstrates using the rectangular-shaped cover glass 10, the shape of a cover glass can be formed in a desired shape by an etching process.

  First, the protective film 32 having etching resistance is coated on the entire area of the first main surface 34 and the second main surface 36 of the glass base material 30. In the present embodiment, a self-adhesive film having at least resistance to hydrofluoric acid is used as the protective film 32. In addition to the film, a resin agent or a resist agent may be used as long as it has resistance to hydrofluoric acid.

  After covering both main surfaces of the glass base material 30 with the protective film 32, as shown in FIG. 3 (B) and FIG. 3 (C), the second main surface 34 is protected from the region corresponding to the peripheral portion 18. A patterning process for removing the film 32 is performed. An example of the patterning process includes a method of removing the protective film 32 using a laser device. The laser device used for the patterning process is not particularly limited as long as the glass base material 30 is not excessively damaged. When the glass base material 30 is coated using a photosensitive resist material, patterning can also be performed using photolithography. Moreover, when the cover glass 10 is arrange | positioned in the glass base material 30 at intervals, you may remove the protective film 32 also from the non-product area | region in which the cover glass 10 is not formed.

  Subsequently, an etching process is performed by bringing the glass base material 30 into contact with an etching solution. Examples of the etching treatment include a dip type etching method in which the glass base material 30 is immersed in the etching liquid and a spray type etching method in which the etching liquid is sprayed onto the glass base material 30. The etching solution contains at least hydrofluoric acid, and it is possible to add an inorganic acid such as hydrochloric acid or an etching aid such as a surfactant as necessary.

  By the etching process, a recess 38 is formed in a region not protected by the protective film 32 (see FIGS. 4A and 4B). The concave portion 38 formed by the etching process has a side portion 381 that is gently curved (see FIG. 5B). The side surface portion 381 is an inclined surface that extends from the bottom surface of the recess 38 toward the second main surface 36. Although the inclined surface of the side surface portion 381 has a curved shape, the shape of the inclined surface can be appropriately adjusted depending on the composition of the etching solution and the etching method, and is changed according to the shape of the article on which the cover glass 10 is disposed. Is done.

  The glass base material 30 in which the plurality of recesses 38 are formed is cut along the outer shape of the cover glass 10 after the protective film 32 is peeled off. The protective film 32 can be peeled off by applying a physical force to the protective film 32. The cutting process can be performed by using a known scribing device or laser device, or by an etching process, and may be executed by combining these processes. In the present embodiment, the glass base material 30 is cut along the broken line 46. Note that since the cutting region is thinned by the etching process, the cutting process can be performed relatively easily. As shown in FIG. 5A, the cover glass 10 that has been subjected to the cutting process has a recess 38 formed at the peripheral edge of the second main surface 34. Since the recess 38 is formed from the boundary between the central portion 16 and the peripheral portion 18 of the cover glass 10 to the end surface of the cover glass 10, the thickness of the peripheral portion 18 is configured to be thinner than that of the central portion 16. .

  Subsequently, a chemical strengthening process is performed on the cover glass 10. The chemical strengthening process is a process of forming the compressive stress layer 40 on the cover glass 10. A chemical strengthening process is performed by the well-known method of immersing a glass substrate in the molten salt containing an alkali ion. In this embodiment, the chemical strengthening treatment was performed by immersing the glass substrate in a potassium nitrate solution heated to 400 ° C. for 4 hours. The heating temperature of potassium nitrate is preferably adjusted to 350 to 450 ° C., and the immersion time of the glass substrate is preferably about 2 to 20 hours. The depth of the compressive stress layer 24 is preferably adjusted to 5 to 50 μm. Further, the first main surface 34, the second main surface 36, and the end surface of the cover glass 10 are subjected to chemical strengthening treatment under the same conditions, and the depth of the compressive stress layer 40 is substantially the same.

  In this case, due to the recess 38 formed in the second main surface 36, a difference occurs in the total volume of compressive stress in both main surfaces at the peripheral edge of the cover glass 10. That is, since the surface area of the second main surface 36 is larger than that of the first main surface 34 by the amount of the recess 38 and the side surface 381, the total compression stress layer 40 formed on the second main surface 36 is increased. The volume is larger than the total volume of the compressive stress layer 40 on the first main surface 34 side. For this reason, a larger compressive stress is applied to the second main surface 36, and the region facing the recess 38 is curved toward the second main surface 36. In particular, since the difference in compressive stress is greatest in the region corresponding to the side surface portion 381, a curved region is formed in the region corresponding to the side surface portion 381. In this case, the curved region is formed in a region adjacent to the central portion 16 in the peripheral edge portion 18.

  Although it is possible to set the cover glass 10 to the portable information terminal 50 or the like as it is, the visibility of the display image may be reduced by forming the recess 38. In order to prevent this, it is preferable to fill the recess 38 with a transparent resin 48 as shown in FIG. The transparent resin 48 is not particularly limited as long as it has an optical characteristic equivalent to that of the cover glass 10. For example, polyethylene, polypropylene, silicon resin, or the like can be used. Moreover, in the area | region corresponding to the recessed part 38, when a touch operation is requested | required, the transparent conductive material may be contained. By filling the transparent resin 48, visibility is not deteriorated due to light refraction or the like. Further, when the cover glass 10 is mounted, it is possible to stably fix the cover glass 10 on the mounting surface without causing a step. When the cover glass 10 is attached to a device such as the portable information terminal 50, an adhesive method that does not adversely affect the visibility such as a transparent silicon tape may be used. It is also possible to fill the recess 38 using such an adhesive. By using an adhesive, it is possible to suppress problems caused by differences in optical characteristics.

  In order to form the curved region, the area of the recess 38 is secured to a certain level or more, and a significant difference is provided in the total volume of the compressive stress layer 40 formed on the first main surface 34 and the second main surface 36. There is a need. In the present embodiment, the concave portions 38 formed in the entire area of the peripheral edge portion 18 improve the curvature and create a significant difference in surface area. However, the shape of the concave portion 38 is not particularly limited. Another embodiment of the recess 38 will be described with reference to FIGS.

  FIG. 7A and FIG. 7B are diagrams showing other patterning shapes of the protective film 32. In the present embodiment, the protective film 32 is removed only at the boundary between the central portion 16 and the peripheral edge 18 in the long side direction of the cover glass 10. The protective film 32 can be removed by the patterning method. The glass base material 30 subjected to the patterning process is sequentially subjected to an etching process and a cutting process, and the cover glass 10 is manufactured. Subsequently, the compressive stress layer 40 is formed by performing chemical strengthening treatment on the cover glass 10. In this case, as shown in FIG. 8C, the cover glass 10 is curved toward the second main surface 36 in the region where the recess 38 is formed. In the present embodiment, the entire area of the peripheral edge is not curved, but the surface area of the second main surface 36 is significantly increased by forming the recess 38, so that a curved region is formed. Is possible. Also in this embodiment, as shown in FIG. 8D, it is possible to fill the recess 38 with a transparent resin 48 as necessary.

  Further, when the cover glass 10 is curved not only in the long side direction but also in the short side direction, patterning is performed so as to surround the outer edge portion of the central portion 16 as shown in FIG. Remove it. By forming the concave portion 38 so as to surround the central portion 16, it is possible to form a curved region on the long side and the short side of the cover glass 10.

  The shape such as the curvature of the curved region can be controlled by the shape of the recess 38 and the depth of the compressive stress layer 40. For this reason, a desired shape can be formed by adjusting the conditions of the etching treatment and the chemical strengthening treatment according to the shape of the curved region. Moreover, since the connection part of the 2nd main surface 26 and the side part 381 is exhibiting the rounded shape by an etching process, when a curved area | region is formed, possibility that it will be damaged is suppressed.

  It is also possible to adjust the shape of the curved region by forming a plurality of recesses. In FIG. 10A, a first recess 60 and a second recess 62 are formed in a region corresponding to the peripheral edge of the cover glass 10. By forming the plurality of concave portions, it is possible to further increase the curvature of the curved region. In the present embodiment, the concave portions 60 and the concave portions 62 have the same shape, but the shape of the peripheral portion is obtained by, for example, forming a plurality of concave portions having different depths, or changing the shape such as the width of the concave portions. It is also possible to adjust.

  Moreover, as an example of the shape of the recessed part 38, the recessed part shown to FIG. 10 (B) is mentioned. In this embodiment, a first side surface portion 641 and a second side surface portion 642 are formed in the recess 38. The first side surface portion 641 is an inclined surface connected to the second main surface 36, and the second side surface portion 641 is an inclined surface connected to the bottom surface of the recess 38. The first inclined surface 641 and the second inclined surface 642 are connected and form the side surface of the recess 38. The first side surface portion 641 and the second side surface portion 642 have different inclination angles, and by having two inclined surfaces, the surface area of the recess 38 can be further increased. Note that such side portions having different inclination angles can be formed by performing the patterning process and the etching process a plurality of times. That is, after the first patterning process and the first etching process are performed and the region corresponding to the second side surface portion 642 is formed, the second patterning process and the second etching process are performed, whereby the first patterning process and the first etching process are performed. A side surface portion 641 is formed. In the second etching process, the second side surface portion 642 is also etched at the same time, so that it is possible to form two side surface portions having different inclination angles.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

10-cover glass 12-first main surface 14-second main surface 16-central portion 18-peripheral portion 30-glass base material 32-protective film 34-first main surface 36-second main surface 38 -Recess 40-Compression stress layer 48-Transparent resin 50-Personal digital assistant

Claims (5)

A cover glass composed of a single glass member, which is a flat central portion and a peripheral portion disposed around the central portion, and is curved from the first main surface to the second main surface side. A cover glass manufacturing method comprising a peripheral portion having a curved region,
A protective step of covering both main surfaces of the glass member with a protective layer having at least etching resistance;
A patterning step of removing the protective layer in a region corresponding to at least a part of the peripheral edge on the second main surface of the glass substrate;
An etching step of forming a recess in a region where the protective layer is removed by bringing the glass substrate into contact with an etching solution;
A chemical strengthening step of forming a chemically strengthened layer over the entire area of the cover glass after removing the protective layer;
The cover glass manufacturing method characterized by including.   The cover glass manufacturing method according to claim 1, further comprising a step of filling the concave portion with a transparent material after the chemical strengthening step.   3. The cover glass manufacturing method according to claim 1, wherein in the patterning step, the protective layer at a boundary portion between the central portion and the peripheral portion is removed.   The said patterning step WHEREIN: The said protective layer is removed so that the outer edge part of the said center part may be enclosed, The cover glass manufacturing method of any one of Claims 1-3 characterized by the above-mentioned. A cover glass composed of a single glass member,
A flat central portion;
A peripheral portion disposed around the central portion and having a curved region that is curved from the first main surface to the second main surface side; and
A compressive stress layer formed in the entire region of the central portion and the peripheral portion;
At least,
The peripheral edge portion has a region where the plate thickness is thinner than that of the central portion.

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