Brittle material chips, brittle material sheets, methods for manufacturing brittle material sheets, and methods for manufacturing brittle material chips

Abstract

To provide a brittle material chip, etc., excellent in flexibility.SOLUTION: A brittle material chip 100 including a brittle material layer 1 formed of a brittle material has a first processing mark 11 formed on one side of the brittle material layer in the thickness direction on at least one end surface of the brittle material layer and having a depth of 1 μm or more and less than the half thickness of the brittle material layer and has or has not a second processing mark 12 formed on the other side in the thickness direction on the end surface of the brittle material layer, facing the first processing mark in the thickness direction and having a depth of less than 1 μm.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a brittle material chip having a brittle material layer formed from a brittle material, a brittle material sheet in which the brittle material chip is formed by being divided along a planned division line, a method for manufacturing a brittle material sheet, and a method for manufacturing a brittle material chip. In particular, the present invention relates to a brittle material chip with excellent flexibility, a brittle material sheet, a method for manufacturing a brittle material sheet, and a method for manufacturing a brittle material chip. [Background technology]

[0002] In many cases, a protective material is placed on the outermost surface of image display devices used in televisions, personal computers, smartphones, smartwatches, and in-car displays to protect the image display device. Typically, a brittle material chip with a brittle material layer formed from a brittle material such as glass is used as the protective material. Brittle material chips are formed by preparing a brittle material sheet larger in dimensions than the brittle material chip using laser processing or the like, and then cutting this brittle material sheet into shapes and dimensions according to the intended use along predetermined cutting lines.

[0003] In recent years, flexible displays that can be deformed have been developed as image display devices, and there is a demand for brittle material chips used in flexible displays that have sufficient flexibility compared to conventional brittle material chips and are less prone to fracture due to deformation. However, according to the inventors' findings, conventional brittle material chips may have large processing marks on both sides of their end face (the end face corresponding to the planned cutting line of the brittle material sheet) in the thickness direction, which differ in surface properties from other parts (the part in the center in the thickness direction). It has been found that sufficient flexibility cannot be obtained due to these processing marks.

[0004] Furthermore, Non-Patent Document 1 describes a glass processing technique using ultrashort pulse laser light, which involves utilizing the filamentation phenomenon of ultrashort pulse laser light and applying a multi-focus optical system or a Bessel beam optical system to the ultrashort pulse laser light source. Furthermore, Non-Patent Document 2 describes the two-point bending stress of a thin glass substrate. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] John Lopez et al., “Glass Cutting Using Ultrashort Pulsed Bessel Beams,” [online], October 2015, International Congress on Applications of Lasers & Electro-Optics (ICALEO), [Accessed July 17, 2020], Internet (URL: https: / / www.researchgate.net / publication / 284617626_GLASS_CUTTING_USING_ULTRASHORT_PULSED_BESSEL_BEAMS) [Non-Patent Document 2] Suresh T. Gulati et al., “Two Point Bending of Thin Glass Substrate”, 2011, SID 11 DIGEST, p.652-654 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention was made to solve the problems of the prior art described above, and aims to provide a brittle material chip with excellent flexibility, a brittle material sheet, a method for manufacturing a brittle material sheet, and a method for manufacturing a brittle material chip. [Means for solving the problem]

[0007] To solve the aforementioned problems, the present inventors conducted diligent studies and found that if a brittle material chip having a brittle material layer has a first processing mark with a depth of 1 μm or more and less than half the thickness of the brittle material layer on one side in the thickness direction of the brittle material layer at at least one end face of the brittle material layer, and a second processing mark formed on the other side in the thickness direction of the brittle material layer, facing the first processing mark in the thickness direction, and having a depth of less than 1 μm, or if there is no second processing mark, then sufficient flexibility can be obtained to the extent that no problems occur even when the brittle material chip is used in a flexible display or the like, and thus the present invention was completed. This invention was completed based on the findings of the inventors described above.

[0008] In other words, to solve the above problem, the present invention provides a brittle material chip having a brittle material layer formed from a brittle material, wherein the chip has a first processing mark formed on one side in the thickness direction of the brittle material layer at at least one end face of the brittle material layer, having a depth of 1 μm or more and less than half the thickness of the brittle material layer, and a second processing mark formed on the other side in the thickness direction of the end face of the brittle material layer, facing the first processing mark in the thickness direction, and having a depth of less than 1 μm. ru , provides brittle material chips.

[0009] In the present invention, the "depth" of the first and second processing marks refers to the dimension in the thickness direction of the brittle material layer. Furthermore, in the present invention, "formed on one side in the thickness direction of the brittle material layer at one end face" means that it is formed to extend from the edge on one side in the thickness direction of one end face toward the center in the thickness direction. Similarly, "formed on the other side in the thickness direction of the end face" means that it is formed to extend from the edge on the other side in the thickness direction of one end face toward the center in the thickness direction. Furthermore, in the present invention, "having a first processing mark" is not limited to cases where the first processing mark is formed continuously (integrally) over the entire direction perpendicular to the thickness direction on one end face of the brittle material layer, but also includes cases where the first processing mark is formed continuously only in a part of the direction perpendicular to the thickness direction, or where the first processing mark is formed intermittently in the direction perpendicular to the thickness direction. Furthermore, in this invention, "its depth is 1 μm or more" means that if multiple first processing marks are formed, the maximum depth of those marks is 1 μm or more. Similarly, "its depth is less than 1 μm" means that if multiple second processing marks are formed, the maximum depth of those marks is less than 1 μm. The first and second processing marks can be recognized, for example, as pixel regions with large changes in density (contrast) or pixel regions with high brightness values ​​(pixel values) when an SEM image (scanning electron microscope image) is taken of the edge face of the brittle material layer, and the dimensions of those pixel regions in the thickness direction (thickness direction of the brittle material layer) can be identified as the depths of the first and second processing marks.

[0010] According to the brittle material chip of the present invention, a first processing mark having a depth of 1 μm or more and less than half the thickness of the brittle material layer is formed on one side in the thickness direction of the brittle material layer at at least one end face of the brittle material layer, and a second processing mark having a depth of less than 1 μm is formed on the other side in the thickness direction of the end face of the brittle material layer, facing the first processing mark in the thickness direction. ru Therefore, as the inventors have observed, sufficient flexibility can be obtained. As a result, it is less prone to breakage due to deformation and can be suitably used as a protective material for image display devices such as deformable flexible displays.

[0011] In the brittle material chip according to the present invention, if the depth of the second processing mark is large, the flexibility decreases. Therefore, preferably, the depth of the second processing mark is 100 nm or less.

[0012] In the brittle material chip according to the present invention, if the depth of the first processing mark is large, the flexibility decreases. Therefore, preferably, the depth of the first processing mark is 10 μm or less.

[0013] In the brittle material chip according to the present invention, preferably, the difference between the maximum value and the minimum value of the depth of the first processing mark is 3 μm or less. Also, in the brittle material chip according to the present invention, preferably, the minimum value of the depth of the first processing mark is 0.5 μm or more. In this way, when the brittle material sheet is divided to manufacture the brittle material chip, if the minimum value of the depth of the first processing mark is not 0 μm (in other words, the first processing mark is continuously formed in the direction orthogonal to the thickness direction on one end face of the brittle material layer), an advantage that it is easy to divide can be obtained.

[0014] In the brittle material chip according to the present invention, preferably, the brittle material layer is formed of glass and its thickness is 100 μm or less.

[0015] Preferably, the brittle material chip according to the present invention is substantially rectangular in plan view, and the end face having the first processing mark is a set of end faces corresponding to at least one set of opposing sides of the rectangle. In the above preferable configuration, "substantially rectangular in plan view" is not limited to the case where it is completely rectangular when viewed from the thickness direction of the brittle material chip, but is a concept including the case where the four corners are chamfered. Also, in the above preferable configuration, the first processing mark is not limited to the case where it is formed in the entire direction orthogonal to the thickness direction of a set of end faces. For example, it may be formed only in a portion that bends when the brittle material chip is used. For example, for the bent portion of the brittle material chip, in order for the brittle material chip to have sufficient flexibility, the first processing mark defined in the present invention (the first processing mark having a depth of 1 μm or more and less than half of the thickness of the brittle material layer) is formed (the depth of the second processing mark is less than 1 μm or the second processing mark is not formed), and for other portions, when the brittle material sheet is divided to manufacture the brittle material chip, it is also possible to adopt an aspect in which a first processing mark having a greater depth than the first processing mark defined in the present invention is formed so as to be easy to divide.

[0016] Also, in order to solve the above problems, the present invention provides a brittle material sheet that is divided along a planned division line to form the brittle material chips, the brittle material sheet having the first processed mark formed along the planned division line on one surface in the thickness direction of the brittle material layer, and having the second processed mark formed along the planned division line on the other surface in the thickness direction of the brittle material layer. ru It is also provided as a brittle material sheet.

[0017] In the present invention, "having the first processed mark formed along the planned division line" does not only refer to the case where the first processed mark is continuously (integrally connected) formed along the entire planned division line, but also includes the case where the first processed mark is continuously formed only on a part along the planned division line, and the case where the first processed mark is intermittently formed along the planned division line. The first processed mark of the brittle material sheet according to the present invention is a non-penetrating processed mark that opens on one surface in the thickness direction of the brittle material layer and extends toward the center in the thickness direction of the brittle material layer, and its depth is 1 μm or more and less than half of the thickness of the brittle material layer. When the brittle material sheet according to the present invention has a second processed mark, this second processed mark is a non-penetrating processed mark that opens on the other surface in the thickness direction of the brittle material layer and extends toward the center in the thickness direction of the brittle material layer, and its depth is less than 1 μm. By dividing the brittle material sheet according to the present invention along the planned division line, brittle material chips are formed where the locations corresponding to the planned division line become end faces. The depth of the first processed mark formed on the end face of the brittle material chip is 1 μm or more and less than half of the thickness of the brittle material layer. Even when a second processed mark is formed on the end face, its depth is less than 1 μm.

[0018] Furthermore, in order to solve the above problem, the present invention provides a brittle material sheet in which a brittle material chip according to any one of claims 1 to 5 is formed by being divided along a planned dividing line, The brittle material layer has a first processing mark formed along the planned division line on one side in the thickness direction, and the brittle material layer has a second processing mark formed along the planned division line on the other side in the thickness direction, or does not have a second processing mark. and has a resin material layer formed of a resin material that contacts the one surface of the brittle material layer without gaps and has a refractive index with an absolute value of the difference from the refractive index of the brittle material of 0.2 or less. It is also provided as a brittle material sheet.

[0019] This inventionAccording to the findings, as described below, when forming a first processing mark in the brittle material layer of a brittle material sheet using an ultrashort pulse laser light source, the reflection of laser light at the interface between the brittle material layer and the resin material layer is suppressed, which has the advantage of making it difficult to form a second processing mark with greater depth.

[0020] This invention In this case, for example, an adhesive is used as the resin material.

[0021] Furthermore, in order to solve the above problems, the present invention also provides a method for manufacturing a brittle material sheet, comprising a process mark formation step of forming a first process mark on one side of the brittle material layer in the thickness direction by arranging an ultrashort pulse laser light source so as to face the other side of the brittle material layer in the thickness direction of the brittle material sheet before the first process mark and the second process mark are formed, and irradiating the brittle material sheet with laser light emitted from the ultrashort pulse laser light source along the planned division line of the brittle material sheet to remove the brittle material.

[0022] In the method for manufacturing a brittle material sheet according to the present invention, "irradiating the brittle material sheet with laser light along the planned division line of the brittle material sheet" means irradiating the brittle material sheet with laser light along the planned division line when viewed from the thickness direction of the brittle material sheet. According to the method for manufacturing a brittle material sheet of the present invention, by adjusting the power and focal position of the laser beam, a first processing mark with a depth of 1 μm or more and less than half the thickness of the brittle material layer can be formed on one side of the thickness direction of the brittle material layer (the side opposite to the side on which the ultrashort pulse laser light source is located (the other side of the thickness direction)), and even if a second processing mark is formed, its depth can be suppressed to less than 1 μm.

[0023] Furthermore, in the case where the brittle material sheet has a resin material layer, the present invention also provides a method for manufacturing a brittle material sheet, comprising a process mark formation step of forming the first process mark by arranging an ultrashort pulse laser light source so as to face the brittle material layer of the brittle material sheet before the first and second process marks are formed, and irradiating the brittle material sheet with laser light emitted from the ultrashort pulse laser light source from the brittle material layer side of the brittle material sheet along the planned division line of the brittle material sheet to remove the brittle material.

[0024] According to the inventors' findings, the reason for the formation of the second processing mark is thought to be largely due to the reflection of laser light on one side of the brittle material layer in the thickness direction (the side opposite to the side where the ultrashort pulse laser light source is located). According to the method for manufacturing a brittle material sheet of the present invention, the absolute value of the difference between the refractive index of the resin material layer that is in contact with one side of the brittle material layer without any gaps and the refractive index of the brittle material layer is 0.2 or less. Therefore, the laser light incident on the brittle material layer from an ultrashort pulse laser light source is less likely to be reflected at the interface between the brittle material layer and the resin material layer. This has the advantage of making it difficult for deep second processing marks to be formed.

[0025] In the method for manufacturing a brittle material sheet according to the present invention, preferably, the laser light irradiated onto the brittle material sheet has a wavelength that is absorbed by the resin material layer but not absorbed by the brittle material layer. In the preferred method described above, "absorbed" means that the absorption coefficient at the wavelength of the laser light irradiated onto the brittle material sheet is 0.03 or greater, and "not absorbed" means that the absorption coefficient at the wavelength of the laser light irradiated onto the brittle material sheet is less than 0.03.

[0026] In the method for manufacturing a brittle material sheet according to the present invention, preferably, the focal point of the laser beam irradiated onto the brittle material sheet is located on the surface of the brittle material layer opposite to the side on which the ultrashort pulse laser light source is located, or at a position further away from the ultrashort pulse laser light source than that surface.

[0027] According to our findings, the above preferred method has the advantage that even when the thickness of the brittle material layer is small, in other words, when the effect of laser light reflection on one side of the brittle material layer in the thickness direction (the side opposite to the side on which the ultrashort pulse laser light source is located) becomes large, it is difficult to form a second processing mark with a large depth. Furthermore, it is more preferable that the focal point of the laser beam be located at a position further away from the ultrashort pulse laser light source than the surface of the brittle material layer on the side opposite to where the ultrashort pulse laser light source is located.

[0028] Furthermore, in the case where the brittle material sheet has a resin material layer, the present invention also provides a method for manufacturing a brittle material chip, comprising a peeling step of peeling the resin material layer from the brittle material sheet, and a cutting step of cutting the brittle material sheet along the planned cutting line by applying an external force that generates tension at the first processing mark to the brittle material sheet from which the resin material layer has been peeled off. Furthermore, if the brittle material sheet does not have a resin material layer, the above peeling process is unnecessary, and brittle material chips can be manufactured using only the above cutting process. [Effects of the Invention]

[0029] According to the present invention, it is possible to obtain a brittle material chip with excellent flexibility. [Brief explanation of the drawing]

[0030] [Figure 1] This is an explanatory diagram illustrating the steps of a method for manufacturing a brittle material chip according to one embodiment of the present invention. [Figure 2] This is an explanatory diagram illustrating the steps of a method for manufacturing a brittle material chip according to one embodiment of the present invention. [Figure 3] Figure 1 is a schematic diagram illustrating an example of how to set the focus of the laser beam emitted from the ultrashort pulse laser light source shown. [Figure 4]This figure schematically shows the structure of a brittle material chip manufactured by a method for manufacturing a brittle material chip according to one embodiment of the present invention. [Figure 5] This figure schematically illustrates the outline of the test conducted on the brittle material chip of Example 1. [Figure 6] This is an explanatory diagram illustrating the division process in Example 1. [Figure 7] This is a schematic diagram illustrating the sample used to measure the absorption coefficient. [Figure 8] This figure shows an overview of the tests and test results for the brittle material chips of Examples 1 and 2 and Comparative Examples 1 and 2. [Figure 9] This figure shows an overview of the tests and test results for the brittle material chips of Examples 3 and 4 and Comparative Examples 3 and 4. [Figure 10] This figure shows an overview of the tests and test results for the brittle material chips of Examples 5 to 9. [Figure 11] This figure shows an overview of the tests and test results for the brittle material chips of Comparative Examples 5 and 6. [Figure 12] Examples of SEM images of the end faces of brittle material chips from Comparative Example 3 and Example 4 are shown. [Figure 13] This figure shows an example of an image obtained by applying image processing such as binarization to the SEM image of the brittle material chip of Example 4. [Modes for carrying out the invention]

[0031] Hereinafter, with due reference to the attached drawings, a brittle material chip, a brittle material sheet, a method for manufacturing a brittle material sheet, and a method for manufacturing a brittle material chip according to one embodiment of the present invention will be described. First, the method for manufacturing a brittle material chip according to this embodiment will be described.

[0032] [Method for manufacturing brittle material chips] Figures 1 and 2 are schematic diagrams illustrating the steps of a method for manufacturing a brittle material chip according to one embodiment of the present invention. Figure 1 shows the process of forming a processing mark in the manufacturing method according to this embodiment. Figure 1(a) is a cross-sectional view, and Figure 1(b) is a plan view. Note that the ultrashort pulse laser light source is not shown in Figure 1(b). Figure 2 shows the peeling and cutting processes in the manufacturing method according to this embodiment. Figure 2(a) is a cross-sectional view showing the peeling process, and Figure 2(b) is a cross-sectional view showing the cutting process. Note that Figures 1 and 2 are for reference only, and the dimensions, scale, and shape of the components shown in the figures may differ from those of the actual components. The same applies to the other figures. The brittle material chip 100 produced by the manufacturing method according to this embodiment is produced by cutting the brittle material sheet 10. As shown in Figure 1, the brittle material sheet 10 according to this embodiment comprises a brittle material layer 1 formed from a brittle material, and a first resin material layer 2 (corresponding to the resin material layer of the present invention) formed from a resin material having a refractive index of 0.2 or less in absolute value difference from the refractive index of the brittle material, which is in contact without gaps on one side (the lower side in the example shown in Figure 1) of the brittle material layer 1 in the thickness direction (up and down direction in Figure 1, Z direction). Furthermore, the brittle material sheet 10 according to this embodiment has a second resin material layer 3 formed from a resin material, which is laminated on the brittle material layer 1 via the first resin material layer 2.

[0033] The brittle material layer 1, the first resin material layer 2, and the second resin material layer 3 are laminated by any suitable method. For example, the brittle material layer 1, the first resin material layer 2, and the second resin material layer 3 can be laminated by a so-called roll-to-roll method. That is, the brittle material layer 1, the first resin material layer 2, and the second resin material layer 3 can be laminated by conveying a long brittle material layer 1 and a long second resin material layer 3 with the first resin material layer 2 formed on its surface in the longitudinal direction, while aligning their longitudinal directions. Alternatively, the brittle material layer 1 and the second resin material layer 3 can be cut into predetermined shapes and then laminated via the first resin material layer.

[0034] Examples of brittle materials forming the brittle material layer 1 include glass and single-crystal or polycrystalline silicon. Examples of glass, according to its composition, include soda-lime glass, borate glass, aluminosilicate glass, quartz glass, and sapphire glass. Examples of glass, according to its alkali content, include alkali-free glass and low-alkali glass. The alkali metal content of the glass (e.g., Na2O, K2O, Li2O) is preferably 15% by weight or less, and more preferably 10% by weight or less.

[0035] The thickness of the brittle material layer 1 is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 30 μm or less. On the other hand, the thickness of the brittle material layer 1 is preferably 5 μm or more, more preferably 10 μm or more. If the thickness of the brittle material layer 1 is within this range, lamination with the second resin material layer 3 by a roll-to-roll method becomes possible.

[0036] When the brittle material forming the brittle material layer 1 is glass, the light transmittance of the brittle material layer 1 at a wavelength of 550 nm is preferably 85% or higher. When the brittle material forming the brittle material layer 1 is glass, the refractive index of the brittle material layer 1 at a wavelength of 550 nm is preferably 1.4 to 1.65. When the brittle material forming the brittle material layer 1 is glass, the density of the brittle material layer 1 is preferably 2.3 g / cm³. 3 ~3.0g / cm 3 More preferably 2.3 g / cm³ 3 ~2.7g / cm 3 That is the case.

[0037] When the brittle material forming the brittle material layer 1 is glass, a commercially available glass plate may be used as the brittle material layer 1, or a commercially available glass plate may be polished to the desired thickness before use. Examples of commercially available glass plates include Corning's "7059", "1737", or "EAGLE2000", Asahi Glass's "AN100", NH Techno Glass's "NA-35", Nippon Electric Glass's "G-Leaf" (registered trademark) or "OA-10", and Schott's "D263" or "AF45".

[0038] Various adhesives such as acrylic adhesives, polyethylene adhesives, urethane adhesives, and silicone adhesives can be used as the resin material forming the first resin material layer 2. Alternatively, various adhesives such as epoxy adhesives may be used.

[0039] Examples of the second resin material layer 3 include a single-layer film or a laminated film consisting of multiple layers made of plastic materials such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA) and other acrylic resins, cyclic olefin polymers (COP), cyclic olefin copolymers (COC), polycarbonate (PC), urethane resin, polyvinyl alcohol (PVA), polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polystyrene (PS), triacetylcellulose (TAC), polyethylene naphthalate (PEN), ethylene vinyl acetate (EVA), polyamide (PA), silicone resin, epoxy resin, liquid crystal polymer, and various resin foams. If the second resin material layer 3 is a laminated film consisting of multiple layers, various adhesives such as acrylic adhesives, polyethylene adhesives, urethane adhesives, silicone adhesives, and epoxy adhesives may be interposed between the layers, similar to the first resin material layer 2. Furthermore, a conductive inorganic film such as indium tin oxide (ITO), Ag, Au, or Cu may be formed on the surface of the second resin material layer 3. The thickness of the second resin material layer 3 is preferably 20 to 500 μm.

[0040] In the example shown in Figure 1, a preferred embodiment shows that the brittle material sheet 10 has both a first resin material layer 2 and a second resin material layer 3. However, the present invention is not limited to this, and even if the brittle material sheet 10 does not have both the first resin material layer 2 and the second resin material layer 3, or has only the second resin material layer 3 (where the brittle material layer 1 is laminated to the second resin material layer 3 via air or water), or has only the first resin material layer 2, it is possible to manufacture brittle material chips 100 using these brittle material sheets 10.

[0041] The manufacturing method according to this embodiment for manufacturing a brittle material chip 100 using the brittle material sheet 10 described above comprises a processing mark formation step, a peeling step, and a cutting step. Each step will be described in order below.

[0042] <Machining mark formation process> As shown in Figure 1, in the processing mark formation process, the ultrashort pulse laser light source 20 is positioned opposite the brittle material layer 1 of the brittle material sheet 10 before the formation of the first and second processing marks, which will be described later (on the upper side of the brittle material layer 1 in the example shown in Figure 1(a)). Then, the laser light (ultrashort pulse laser light) L1 emitted (pulsed) from the ultrashort pulse laser light source 20 is irradiated onto the brittle material sheet 10 from the side of the brittle material layer 1 along the planned division line of the brittle material sheet 10 to remove the brittle material that forms the brittle material layer 1, thereby forming the first processing mark 11. In this embodiment, as shown in Figure 1(b), the first processing mark 11 is formed integrally along the planned division line. Note that in Figures 1 and 2, the second processing mark 12, which may be formed simultaneously with the first processing mark 11 and will be described later, is not shown. In the example shown in Figure 1, the planned division line is a straight line DL extending in the Y direction, out of two orthogonal directions (X and Y directions) within the plane (XY 2D plane) of the brittle material sheet 10. The planned division line DL can be visually represented and actually drawn on the brittle material sheet 10, or its coordinates can be pre-inputted into a control device (not shown) that controls the relative positional relationship between the laser beam L1 and the brittle material sheet 10 on the XY 2D plane. The planned division line DL shown in Figure 1 is a virtual line whose coordinates have been pre-inputted into the control device and is not actually drawn on the brittle material sheet 10. Note that the planned division line DL is not limited to a straight line, but may also be a curve. By determining the planned division line DL according to the application of the brittle material sheet 10, the brittle material sheet 10 can be divided into any shape according to the application.

[0043] One possible method for irradiating the brittle material sheet 10 along the planned division line DL (scanning the laser beam L1) is to place and fix (for example, by suction) a single sheet of brittle material 10 on an XY2-axis stage (not shown), and then drive the XY2-axis stage with a control signal from a control device to change the relative position of the brittle material sheet 10 on the XY2-dimensional plane with respect to the laser beam L1. Alternatively, the position of the brittle material sheet 10 can be fixed, and the laser beam L1 emitted from the ultrashort pulse laser light source 20 can be deflected using a galvanometer mirror or polygon mirror driven by a control signal from a control device to change the position of the laser beam L1 irradiated onto the brittle material sheet 10 on the XY2-dimensional plane. Furthermore, it is possible to use both scanning of the brittle material sheet 10 using the XY2-axis stage and scanning of the laser beam L1 using a galvanometer mirror or the like in combination.

[0044] The brittle material forming the brittle material layer 1 is removed by utilizing the filamentation phenomenon of laser light L1 emitted from the ultrashort pulse laser light source 20, or by applying a multi-focus optical system (not shown) or a Bessel beam optical system (not shown) to the ultrashort pulse laser light source 20. Furthermore, the use of the filamentation phenomenon of ultrashort pulse laser light and the application of a multi-focus optical system or Bessel beam optical system to an ultrashort pulse laser light source are described in Non-Patent Document 1 mentioned above. In addition, Trumpf GmbH in Germany sells a product for glass processing that applies a multi-focus optical system to an ultrashort pulse laser light source. As the use of the filamentation phenomenon of ultrashort pulse laser light and the application of a multi-focus optical system or Bessel beam optical system to an ultrashort pulse laser light source are well known, further detailed explanations will be omitted here.

[0045] The laser light L1 emitted from the ultrashort pulse laser light source 20 and irradiated onto the brittle material sheet 10 preferably has a wavelength that is absorbed by the first resin material layer 2 but not absorbed by the brittle material layer 1. Specifically, the wavelength of the laser light L1 is preferably between 500 nm and 2500 nm, which exhibits high light transmittance when the brittle material forming the brittle material layer 1 is glass. In order to effectively induce nonlinear optical phenomena (multiphoton absorption), the pulse width of the laser light L1 is preferably 100 picoseconds or less, and more preferably 50 picoseconds or less. The pulse width of the laser light L1 is set, for example, between 350 femtoseconds and 10000 femtoseconds. The oscillation mode of the laser light L1 may be single-pulse oscillation or burst-mode multi-pulse oscillation.

[0046] In the processing mark formation process, the focal point of the laser beam L1 emitted from the ultrashort pulse laser light source 20 and irradiated onto the brittle material sheet 10 is set to be located on the surface of the brittle material layer 1 on the opposite side from where the ultrashort pulse laser light source 20 is located (the lower side in the example shown in Figure 1(a)) (i.e., the interface with the first resin material layer 1 in the example shown in Figure 1(a)) or at a position further away from the ultrashort pulse laser light source 20 than that surface (a lower position in the example shown in Figure 1(a)). As a result, the first processing mark 11 formed in the processing mark formation process opens on the side of the first resin material layer 2 and is a non-penetrating processing mark (not opening on the side opposite to the first resin material layer 2) that extends toward the center in the thickness direction (Z direction) of the brittle material layer 1. The mechanism by which the non-penetrating first processing mark 11 opening on the first resin material layer 2 side is formed is not entirely clear, but the inventors estimate that by setting the focal point of the laser beam L1 to the interface between the brittle material layer 1 and the first resin material layer 2, the energy of the laser beam L1 is concentrated and absorbed near the interface between the first resin material layer 2 and the brittle material layer 1, generating heat. This heat is then conducted to the brittle material layer 1, removing the brittle material at the conducted location and forming the first processing mark 11. The following describes how to set the focus of the laser beam L1.

[0047] Figure 3 is a schematic diagram illustrating an example of how to set the focus of the laser beam L1 emitted from the ultrashort pulse laser light source 20. In the example shown in Figure 3, a multifocus optical system is applied to the ultrashort pulse laser light source 20. Specifically, the multifocus optical system shown in Figure 3 consists of three axicon lenses 21a, 21b, and 21c. As shown in Figure 3, assuming that the spatial intensity distribution of the laser light L1 emitted from the ultrashort pulse laser light source 20 is a Gaussian distribution, the laser light L1 emitted in the range from point A to point B, where the intensity is relatively high, follows the optical path shown by the dashed line in Figure 3 and converges at the focus AF. In the processing mark formation process of this embodiment, 1 The focal point set near the interface between the resin material layer 2 and the brittle material layer 1 is the focal point AF where the laser beam L1, which oscillates in a relatively high-intensity range from point A to point B, converges. The range from point A to point B is, for example, the range where the intensity is 90% or more of the maximum intensity of the spatial intensity distribution of the laser beam L1. In the processing mark formation process, the positional relationship between the focal point AF of the laser beam L1 and the brittle material sheet 10 is adjusted so that the focal point AF of the laser beam L1 is at or below the interface between the brittle material layer 1 and the first resin material layer 2 (specifically, at a distance H (H≧0) below the interface). This distance H is preferably set to 0μm to 800μm, more preferably to 50μm to 600μm, and even more preferably to 200μm to 400μm. The spot diameter of the laser beam L1 in the focus AF is preferably set to 5 μm or less, more preferably to 3 μm or less.

[0048] Furthermore, when utilizing the filamentation phenomenon of laser light L1, as the laser light L1 passes through the brittle material layer 1, it self-focuses due to the Kerr effect, causing the spot diameter to decrease as it progresses. When the laser light L1 focuses to the energy threshold at which ablation occurs in the brittle material layer 1, the brittle material of the brittle material layer 1 is removed, and the first processed mark 11 is formed. As described above, by setting the position at which the laser light L1 focuses to the energy threshold at which ablation occurs (corresponding to the aforementioned focal point AF) at or below the interface between the brittle material layer 1 and the first resin material layer 2, it is possible to form a non-penetrating first processed mark 11 that opens on the first resin material layer 2 side and extends toward the center in the thickness direction (Z direction) of the brittle material layer 1.

[0049] By adjusting the power of the laser beam L1 emitted from the ultrashort pulse laser light source 20 and the position (distance H) of the focal point AF, it is possible to adjust the strength of the energy used to form the first processing mark 11 (remove the brittle material) (the magnitude of the intensity in the range from point A to point B). This makes it possible to adjust the depth of the first processing mark 11. Furthermore, even if the second processing mark 12, described later, is formed on the surface opposite to the interface between the brittle material layer 1 and the first resin material layer 2, it is possible to adjust it so that its depth is suppressed. The smaller the depth of the first processing mark 11, the more sufficient flexibility can be given to the brittle material chip 100 formed by cutting the brittle material sheet 10. On the other hand, if the depth of the first processing mark 11 is too small, it will hinder the cutting of the brittle material sheet 10 in the cutting process described later. Therefore, the depth of the first processing mark 11 is 1 μm or more and less than half the thickness of the brittle material layer 1, preferably 10 μm or less. Furthermore, as long as the depth of the first processing mark 11 is 1 μm or more, a smaller depth is more preferable in that sufficient flexibility can be obtained. Furthermore, if a second processing mark 12 is formed, and its depth is large, the flexibility of the brittle material chip 100 formed by cutting the brittle material sheet 10 will decrease. For this reason, the depth of the second processing mark 12 is less than 1 μm, and preferably 100 nm or less.

[0050] The processing mark formation step described above corresponds to the method for manufacturing a brittle material sheet according to this embodiment, and the brittle material sheet 10 after the processing mark formation step is performed corresponds to the brittle material sheet according to this embodiment.

[0051] <Peeling process> In this embodiment, the peeling step is performed after the processing mark formation step. As shown in Figure 2(a), in the peeling process, the first resin material layer 2 is peeled off from the brittle material sheet 10 on which the first processing marks 11 (and, in some cases, the second processing marks 12) have been formed, using known peeling means such as a peeling roller. In this embodiment, the second resin material layer 3 is peeled off at the same time as the first resin material layer 2, and as shown in Figure 2(a), a brittle material sheet 10 consisting only of the brittle material layer 1 is manufactured.

[0052] <Disassembly Process> The separation step in this embodiment is performed after the peeling step. As shown in Figure 2(b), in the division process, after the processing mark formation process and the peeling process, an external force is applied to the brittle material sheet 10 to divide the brittle material sheet 10 along the planned division line DL. In the example shown in Figure 2(b), the brittle material sheet 10 is divided into two brittle material chips 100 (100a, 100b). Examples of methods for applying external force to the brittle material sheet 10 include mechanical breaking (mountain folding), heating of the area near the planned separation line DL using infrared laser light, vibration application using an ultrasonic roller, and suction and lifting using a suction cup. When separating the brittle material sheet 10 by mountain folding, it is preferable to apply bending deformation so that the side where the first resin material layer 2 was located before the peeling process (the lower side in the example shown in Figure 2) becomes convex, so that tensile strain is generated in the first processing mark 11.

[0053] [Composition of brittle material chips] The configuration of the brittle material chip according to this embodiment will be described below. Figure 4 is a schematic diagram showing the structure of a brittle material chip 100 (100b) manufactured by the manufacturing method according to this embodiment (manufactured using the brittle material sheet 10 shown in Figure 1). Figure 4(a) is a side view seen from the Y direction (the direction in which the planned division line DL extends), and Figure 4(b) is a side view seen from the X direction (the direction perpendicular to the direction in which the planned division line DL extends). As shown in Figure 4, the brittle material chip 100 has a first processing mark 11 formed on one end face (a divided end face) of the brittle material layer 1 on one side (the lower side in the example shown in Figure 4) in the thickness direction (Z direction) of the brittle material layer 1. The brittle material chip 100 also has a second processing mark 12 formed on the other side (the upper side in the example shown in Figure 4) of the same end face of the brittle material layer 1, which is opposite to the first processing mark 11 in the thickness direction, or it does not have a second processing mark 12. Note that the part indicated by reference numeral 13 in Figure 4 is a part that does not have either the first processing mark 11 or the second processing mark 12.

[0054] As described above, the depth of the first processing marks 11 formed on the brittle material sheet 10 in the processing mark formation process is 1 μm or more and less than half the thickness of the brittle material layer 1, preferably 10 μm or less. Therefore, the depth of the first processing marks 11 formed on the end face of the brittle material chip 100 is also 1 μm or more and less than half the thickness of the brittle material layer 1, preferably 10 μm or less. More preferably 7 μm or less, and even more preferably 3 μm or less. Furthermore, as mentioned above, the depth of the second processing marks 12 that can be formed on the brittle material sheet 10 in the processing mark formation process is less than 1 μm, preferably 100 nm or less. Therefore, the depth of the second processing marks 12 that can be formed on the end face of the brittle material chip 100 is also less than 1 μm, preferably 100 nm or less. The first processing marks 11 and the second processing marks 12 can be recognized, for example, as pixel regions with large changes in density (contrast) or pixel regions with high brightness values ​​(pixel values) when an SEM image of the end face of the brittle material layer 1 is captured, and the dimension of that pixel region in the thickness direction (thickness direction of the brittle material layer 1) can be identified as the depth of the first processing marks 11 and the second processing marks 12. Figure 4(b) illustrates a state in which both the first processing mark 11 and the second processing mark 12 are formed to a substantially uniform depth along the direction (Y direction) in which the planned division line DL extends. However, the present invention is not limited to this, and the depths of the first processing mark 11 and / or the second processing mark 12 may be non-uniform. Also, Figure 4(b) illustrates a state in which both the first processing mark 11 and the second processing mark 12 are formed continuously (integrally connected) along the entire direction (Y direction) in which the planned division line DL extends. However, the present invention is not limited to this, and the first processing mark 11 and / or the second processing mark 12 may be formed continuously only in a part along the direction (Y direction) in which the planned division line DL extends, or may be formed intermittently along the direction (Y direction) in which the planned division line DL extends.

[0055] As described above, the brittle material chip 100 according to this embodiment has a first processing mark 11 on one side in the thickness direction of the brittle material layer 1 at least one end face of the brittle material layer 1, with a depth of 1 μm or more and less than half the thickness of the brittle material layer 1, and a second processing mark 12 formed on the other side in the thickness direction of the end face of the brittle material layer 1, facing the first processing mark 11 in the thickness direction, with a depth of less than 1 μm, or not having a second processing mark 12. Therefore, as the inventors have found, it is possible to obtain sufficient flexibility. For this reason, it is less prone to fracture due to deformation and can be suitably used as a protective material for image display devices such as deformable flexible displays.

[0056] The following describes an example of the results of tests conducted to evaluate the flexibility, etc., of the brittle material chips 100 (Examples 1-9) and the brittle material chips 100 (Comparative Examples 1-6) according to the present embodiment.

[0057] <Example 1> Figure 5 is a schematic diagram illustrating the outline of the test for the brittle material chip 100 of Example 1. The outline of the test for the brittle material chip 100 of Example 1 will be described below, with reference to Figure 5 as appropriate. In the brittle material sheet 10 used to manufacture the brittle material chip 100 of Example 1, the brittle material layer 1 is formed from alkali-free glass (specifically, "G-Leaf" (registered trademark) manufactured by Nippon Electric Glass Co., Ltd.) and has a thickness of 100 μm. Furthermore, the brittle material sheet 10 does not have a first resin material layer 2, and the brittle material layer 1 is laminated with air between it and a second resin material layer 3 made of a 50 μm thick PET film (specifically, "Diafoil S100" manufactured by Mitsubishi Chemical Corporation). As shown in Figure 5(a), the brittle material sheet 10 is a square with in-plane dimensions (in the XY 2-dimensional plane) of 150 mm × 150 mm. The dashed lines in Figure 5(a) are the planned division lines.

[0058] In the processing mark formation process, a Coherent "Monaco 1035-80-60" (oscillation wavelength 1035 nm, laser beam L1 pulse width 350-10000 femtoseconds, pulse oscillation repetition frequency maximum 50 MHz, average power 60 W) was used as the ultrashort pulse laser light source 20. Laser beam L1, emitted from the ultrashort pulse laser light source 20 at a predetermined output (15 W), was irradiated onto the brittle material sheet 10 from the brittle material layer 1 side via a multi-focus optical system. The output of the laser beam L1 emitted from the ultrashort pulse laser light source 20 was measured using an Ophir fan-cooled thermal sensor "FL400A-BB-50". The focal point AF of the laser beam L1 was set to the bottom surface of the brittle material layer 1 (i.e., distance H=0 μm). The relative movement speed (processing speed) of the laser beam L1 with respect to the brittle material sheet 10 was set to 125 mm / sec, and the pulse oscillation repetition frequency was set to 125 kHz. As shown in Figure 5(a), when the laser beam L1 was scanned along the planned division line so that the brittle material sheet 10 could be divided into a rectangular brittle material chip 100 with in-plane dimensions of 110 mm × 60 mm, a first processing mark 11 with a depth (maximum) of 11 μm was formed on the lower surface of the brittle material layer 1, which was integrally connected along the planned division line. In addition, a second processing mark 12 with a depth (maximum) of 0.2 μm was formed on the upper surface of the brittle material layer 1, which was also along the planned division line. In the division process, the brittle material sheet 10 was divided into brittle material chips 100 by folding it in a mountain shape along the planned division line, such that the side with the first processing mark 11 was convex (the side with the second processing mark 12 was concave). Specifically, the process was as follows: Figure 6 is a schematic diagram illustrating the division process of Example 1. As shown in Figure 6, in the division process, a division jig was placed on the side of the brittle material sheet 10 opposite the first processing mark 11, via a PET film for preventing damage. At this time, the division jig was positioned so that its tip coincided with the first processing mark 11 when viewed from the thickness direction of the brittle material sheet 10. Then, using the division jig as a fulcrum, the brittle material sheet 10 was bent so that the side with the first processing mark 11 became convex, thereby generating tensile strain in the first processing mark 11 and dividing it into brittle material chips 100.

[0059] <Example 2> Except for the fact that the thickness of the brittle material layer 1 was 50 μm, the same brittle material sheet 10 as in Example 1 was used, and the brittle material chip 100 was manufactured under the same conditions as in Example 1. The maximum depth of the first processing mark 11 was 9 μm, and the maximum depth of the second processing mark 12 was 0.15 μm.

[0060] <Comparative Example 1> Except for the fact that the thickness of the brittle material layer 1 is 30 μm, the same brittle material sheet 10 as in Example 1 was used, and the brittle material chip 100 was manufactured under the same conditions as in Example 1. The maximum depth of the first processing mark 11 was 7 μm, and the maximum depth of the second processing mark 12 was 15 μm.

[0061] <Comparative Example 2> A brittle material chip 100 was manufactured under the same conditions as in Comparative Example 1, except that a laminate (specifically, Nitto Denko's "E-MASK RP207" protective material for optical films) was used, in which a first resin material layer 2 (thickness after drying 20 μm) was formed by applying an acrylic adhesive to a second resin material layer 3 and drying it, and a brittle material sheet 10 was used in which a brittle material layer 1 was laminated on the first resin material layer 2 side of this laminate. The maximum depth of the first processing mark 11 was 9 μm, and the maximum depth of the second processing mark 12 was 6 μm.

[0062] <Comparative Example 3> Except for setting the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 to 50 μm below the bottom surface of the brittle material layer 1 (i.e., distance H = 50 μm), a brittle material chip 100 was manufactured using the same brittle material sheet 10 as in Comparative Example 1 and under the same conditions as in Comparative Example 1. The maximum depth of the first processing mark 11 was 3 μm, and the maximum depth of the second processing mark 12 was 11 μm.

[0063] <Example 3> Except for setting the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 in the processing mark formation process to 50 μm below the lower surface of the brittle material layer 1 (i.e., distance H = 50 μm), the same brittle material sheet 10 as in Comparative Example 2 was used and the same conditions as in Comparative Example 2 were used to manufacture the brittle material chip 100. The maximum depth of the first processing mark 11 was 5 μm, and the maximum depth of the second processing mark 12 was 0.6 μm.

[0064] <Example 4> A brittle material chip 100 was manufactured under the same conditions as in Example 3, except that a laminate was used in which a first resin material layer 2 (total thickness of the first resin material layer 2 and the second resin material layer 3 after drying) was laminated onto a second resin material layer 3, and a polyethylene-based adhesive was applied and dried (total thickness of the first resin material layer 2 and the second resin material layer 3 after drying is 30 μm) was laminated (specifically, the surface protective film "Toretec (registered trademark) 7832C" manufactured by Toray Film Processing Co., Ltd.) was used, and a brittle material sheet 10 was used in which a brittle material layer 1 was laminated on the first resin material layer 2 side of this laminate. The maximum depth of the first processing mark 11 was 6 μm, and the maximum depth of the second processing mark 12 was 0.1 μm.

[0065] <Comparative Example 4> A brittle material chip 100 was manufactured under the same conditions as in Comparative Example 3, except that a brittle material sheet 10 was used, in which a brittle material layer 1 was laminated on a second resin material layer 3 via water (pure water). The water used was produced using the "Purelight PR-0100SG" pure water system manufactured by Organo Corporation. The maximum depth of the first processing mark 11 was 3 μm, and the maximum depth of the second processing mark 12 was 7 μm.

[0066] <Example 5> Except for the fact that in the processing mark formation process, the output from the ultrashort pulse laser light source 20 was set to 41W and the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 was set to 370 μm below the lower surface of the brittle material layer 1 (i.e., distance H = 370 μm), the same brittle material sheet 10 as in Example 3 was used and the same conditions as in Example 3 were used to manufacture the brittle material chip 100. The depth (maximum value) of the first processing mark 11 was 2 μm, and the second processing mark 12 was not formed.

[0067] <Example 6> Except for the fact that in the processing mark formation process, the output from the ultrashort pulse laser light source 20 was set to 41W and the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 was set to 370 μm below the lower surface of the brittle material layer 1 (i.e., distance H = 370 μm), the same brittle material sheet 10 as in Example 4 was used and the same conditions as in Example 4 were used to manufacture the brittle material chip 100. The depth (maximum value) of the first processing mark 11 was 2.5 μm, and the second processing mark 12 was not formed.

[0068] <Example 7> Except for the fact that in the processing mark formation process, the output from the ultrashort pulse laser light source 20 was set to 41W and the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 was set to 370 μm below the bottom surface of the brittle material layer 1 (i.e., distance H = 370 μm), the same brittle material sheet 10 as in Comparative Example 4 was used and the same conditions as in Comparative Example 4 were used to manufacture the brittle material chip 100. The depth (maximum value) of the first processing mark 11 was 1.5 μm, and the second processing mark 12 was not formed.

[0069] <Example 8> Except for the fact that in the processing mark formation process, the output from the ultrashort pulse laser light source 20 was set to 41W and the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 was set to 370 μm below the bottom surface of the brittle material layer 1 (i.e., distance H = 370 μm), the same brittle material sheet 10 as in Comparative Example 3 was used and the same conditions as in Comparative Example 3 were used to manufacture the brittle material chip 100. The maximum depth of the first processing mark 11 was 1.5 μm, and the maximum depth of the second processing mark 12 was 0.1 μm.

[0070] <Example 9> Except for the fact that the thickness of the brittle material layer 1 was 50 μm, the same brittle material sheet 10 as in Example 5 was used, and the brittle material chip 100 was manufactured under the same conditions as in Example 5. The depth (maximum value) of the first processing mark 11 was 2 μm, and the second processing mark 12 was not formed.

[0071] <Comparative Example 5> Except for the fact that in the processing mark formation process, the output from the ultrashort pulse laser light source 20 was set to 15W and the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 was set to 220 μm above the lower surface of the brittle material layer 1 (i.e., distance H = -220 μm), the same brittle material sheet 10 as in Example 8 was used and the same conditions as in Example 8 were used to manufacture the brittle material chip 100. No first processing mark 11 was formed, and the depth (maximum value) of the second processing mark 12 was 20 μm.

[0072] <Comparative Example 6> Except for the fact that in the processing mark formation process, the output from the ultrashort pulse laser light source 20 was set to 15W and the focal point AF of the laser beam L1 irradiated onto the brittle material sheet 10 was set to 220 μm above the lower surface of the brittle material layer 1 (i.e., distance H = -220 μm), the same brittle material sheet 10 as in Example 5 was used and the same conditions as in Example 5 were used to manufacture the brittle material chip 100. The maximum depth of the first processing mark 11 was 0.2 μm, and the maximum depth of the second processing mark 12 was 20 μm.

[0073] <Evaluation details> The flexibility (specifically, bending strength) of the brittle material chips 100 obtained in Examples 1-9 and Comparative Examples 1-6 described above was evaluated. The fragility of the brittle material sheet 10 when it is broken into the brittle material chips 100 was also evaluated. Furthermore, the refractive index and extinction coefficient of the brittle material layer 1, the first resin material layer 2, and water were also evaluated. The details of each of these evaluation items are described below.

[0074] (Refractive index) The refractive indices of brittle material layer 1, first resin material layer 2, and water in Examples 1-9 and Comparative Examples 1-6 were measured using the JAWoollam M-2000 high-speed ellipsometer with rotational compensator. Specifically, the incident light beam diameter was set to approximately 2 mm x 8 mm, and the incident angle was set to 50°, 60°, and 70°. When measuring the refractive index of the first resin material layer 2, the wavelength of the incident light was set to 700 nm to 1680 nm, and when measuring the refractive index of the brittle material layer 1 and water, the wavelength of the incident light was set to 400 nm to 1680 nm. The refractive index at a wavelength of 1035 nm, which is the oscillation wavelength of the ultrashort pulse laser light source 20, was measured in each case. CompleteEASE was used as the analysis software.

[0075] (absorption coefficient) The absorption coefficients of brittle material layer 1, first resin material layer 2, and water in Examples 1-9 and Comparative Examples 1-6 were measured using a Hitachi U-4100 spectrophotometer. Since absorption in the near-infrared region, such as the oscillation wavelength of the ultrashort pulse laser light source 20 (1035 nm), is small, when measuring the absorption coefficients of brittle material layer 1, first resin material layer 2, and water, samples with a thickness of approximately 1-2 mm were prepared as described below, and the transmittance was measured. Because the surface reflectance contributes more to the measured transmittance than the absorptance, the surface reflectance was also measured, and a corrected transmittance (corrected transmittance = transmittance + surface reflectance) was calculated by adding the measured transmittance and the surface reflectance. The absorbance A was calculated using the following formula (1), and the absorption coefficient was calculated by dividing this absorbance A by the thickness of the sample. A = -log 10 (Corrected transmittance)...(1)

[0076] Figure 7 is a schematic diagram illustrating the samples used to measure the absorption coefficient. Figure 7(a) shows a schematic diagram of the sample used when measuring the transmittance of the brittle material layer 1 and the first resin material layer 2, Figure 7(b) shows a schematic diagram of the sample used when measuring the transmittance of water, and Figure 7(c) shows a schematic diagram of the sample used when measuring the reflectance of the surfaces of the brittle material layer 1, the first resin material layer 2, and water. As shown in Figure 7(a), when measuring the transmittance of the brittle material layer 1, 20 sheets of alkali-free glass (G-Leaf) (registered trademark) with a thickness of 100 μm were bonded together using an acrylic adhesive with a thickness of 15 μm to create a sample S1 with a thickness of approximately 2.3 mm. Then, light was shone from above onto this sample S1 and the transmittance was measured. Furthermore, as shown in Figure 7(a), when measuring the transmittance of the first resin material layer 2 (acrylic adhesive), a sample S1 with a thickness of 1 mm was prepared by laminating 50 layers of 20 μm thick adhesive of the optical film protective material "E-MASK RP207". Then, light was irradiated from above this sample S1 and the transmittance was measured. Furthermore, as shown in Figure 7(a), when measuring the transmittance of the first resin material layer 2 (polyethylene-based adhesive), 35 sheets of the surface protection film "Toretec® 7832C" with a total thickness of 30 μm were laminated together to create a sample S1 with a thickness of approximately 1 mm. Then, light was irradiated from above this sample S1 and the transmittance was measured. Furthermore, as shown in Figure 7(b), when measuring the water transmittance, a PET frame with a thickness of 2 mm was made from a PET sheet, water (pure water) was filled into this PET frame, and an alkali-free glass (G-Leaf® with a thickness of 100 μm) was used as a window material to create a sample S2 with a thickness of 2.2 mm. Then, light was shone from above into this sample S2 and the transmittance was measured. When measuring the reflectance of the surfaces of each of the above samples S1 and S2, a 50 μm thick black PET film (Lumirror® X30 manufactured by Toray Industries, Inc.) was placed beneath each sample S1 and S2, and light was shone from above to measure the reflectance of the surfaces.

[0077] (Disruptive) Ten samples of the brittle material sheet 10 were prepared for each of Examples 1-9 and Comparative Examples 1-6, and the fragmentation ability was evaluated by the number of samples that could be properly fragmented along the planned fragmentation line DL. In the test results described below, "◎" means that the sample could be fragmented in 9 or more pieces, "〇" means that it could be fragmented in 7 to 8 pieces, "△" means that it could be fragmented in 5 to 6 pieces, and "×" means that it could only be fragmented in 4 pieces or less.

[0078] (flexibility) To evaluate the flexibility (bending strength), a two-point bending test was performed on the brittle material chip 100. In the two-point bending test, as shown in Figure 5(b), the brittle material chip 100 was first placed on the fixed part 30 of a uniaxial stage equipped with a fixed part 30 and movable parts 40a and 40b, and the brittle material chip 100 was sandwiched between the movable parts 40a and 40b. At this time, by moving the movable part 40b, multiple brittle material chips 100 manufactured under the same conditions were prepared so that two-point bending tests could be performed for both cases: when the side with the first processing mark 11 of the brittle material chip 100 bends with a concave shape, and when the side with the first processing mark 11 bends with a convex shape. The front and back sides of the brittle material chips 100 were reversed and placed on the fixed part 30. Next, as shown in Figure 5(c), the position of the movable part 40a was fixed while the movable part 40b was moved toward the movable part 40a at a speed of 20 mm / min, thereby applying a bending stress to the brittle material chip 100. The bending strength of the brittle material chip 100 was then evaluated by the value of the distance D between the movable part 40a and the movable part 40b when the brittle material chip 100 fractured.

[0079] Specifically, the radius of curvature of the brittle material chip 100 was calculated geometrically from the interval D. Furthermore, the above interval D was substituted into equation (3) (same as equation (2) below) described in Non-Patent Document 2 to obtain the maximum stress σ maxIt was calculated and evaluated as the bending strength.

Number

[0080] <Test Results> Figs. 8 to 11 are diagrams showing the outlines and results of tests on the brittle material chips 100 of Examples 1 to 9 and Comparative Examples 1 to 6 described above.

[0081] Also, Fig. 12 shows examples of SEM images of the end faces of the brittle material chips 100 of Comparative Example 3 and Example 4. Fig. 12(a) is an example of the SEM image (magnification: 2.5×10 3 times) of the brittle material chip 100 of Comparative Example 3, Fig. 12(b) is an example of the SEM image (magnification: 2.5×10 3 times) of the brittle material chip 100 of Example 4, and Fig. 12(c) is an example of the SEM image (magnification: 50×10 3 times) of the brittle material chip 100 of Example 4. The SEM images shown in Fig. 12 were captured by using the ultra-high resolution field emission scanning electron microscope "Regulus8230" manufactured by Hitachi High-Tech Corporation, setting the acceleration voltage to 2 kV, and detecting secondary electrons. As can be seen from Figure 12, the first processing marks 11 and the second processing marks 12 can be recognized as pixel regions with large changes in density (contrast) or pixel regions with high brightness values ​​(pixel values), and the dimension in the thickness direction of these pixel regions (the thickness direction of the brittle material chip 100, and the vertical direction in Figure 12) can be identified as the depth of the first processing marks 11 and the second processing marks 12. D11 shown in Figure 12 max This is the maximum depth of the first processing mark 11, and D12 max This is the maximum depth of the second processing mark 12.

[0082] Figure 13 shows an example of an image obtained by applying image processing such as binarization to the SEM image of the brittle material chip 100 of Example 4. Figure 13(a) is the SEM image of the brittle material chip 100 of Example 4 shown in Figure 12(b) (magnification: 2.5 × 10⁻¹⁰ 3 Figure 13(b) is an SEM image (magnification: 50 × 10) of the brittle material chip 100 of Example 4 shown in Figure 12(c). The image was obtained by applying a binarization process to extract pixel regions with brightness values ​​higher than a predetermined threshold, and then applying known noise reduction processes such as small area removal and isolated point removal. 3 This image is obtained by applying a binarization process to extract pixel regions with a brightness value higher than a predetermined threshold (multiplied by a factor of 1), and then applying known noise reduction processes such as small area removal and isolated point removal. The depth D11 of the first processing mark 11 mentioned above. max The depth of the second processing mark 12 is D12. max The depth D11 of the first processing mark 11 can be determined by visual inspection of the SEM image shown in Figure 12, or by using an image like the one shown in Figure 13, based on the vertical coordinates of the pixel region (the pixel region shown in black in Figure 13) extracted by binarization and noise reduction processing using a known image processing device. max The depth of the second processing mark 12 is D12. max It is also possible to automatically identify them.

[0083] As shown in Figures 8 to 11, the brittle material chips 100 of Examples 1 to 9 all exhibited a bending strength of 500 MPa or more when bent with the first processing mark 11 side concave (which is the normal usage mode of the brittle material chip 100), while the brittle material chips 100 of Comparative Examples 1 to 6 exhibited a bending strength of at most 175 MPa when bent with the first processing mark 11 side concave, demonstrating sufficient flexibility. Among the brittle material chips 100 of Examples 1 to 9, in terms of flexibility, the brittle material chips 100 of Examples 4 to 9, in which the focal point AF position of the laser beam L1 was set to H = 50 μm to 400 μm during the processing mark formation process, have a bending strength (bending strength when the first processing mark 11 side is concave) of 1330 MPa or more, which is particularly preferable. Furthermore, in terms of divisibility, Examples 3 and 4, in which the focal point AF of the laser beam L1 was set to H=50μm during the processing mark formation process and a first resin material layer 2 (acrylic adhesive or polyester adhesive) was provided on the brittle material sheet 10, received a "◎" rating and can be said to be particularly preferred. In Comparative Examples 1 and 2, because the depth of both the first processing mark 11 and the second processing mark 12 was large, there were cases where the material could not be properly divided along the planned division line DL (divided at a location other than the planned division line DL), resulting in a "△" rating. In Comparative Examples 5 and 6, either the first processing mark 11 was not formed (depth 0μm in Comparative Example 5) or the depth of the first processing mark 11 was very small (depth 0.2μm in Comparative Example 6), resulting in cases where the material could not be divided, resulting in a "×" rating. [Explanation of Symbols]

[0084] 1...brittle material layer 2...Resin material layer (first resin material layer) 3...Second resin material layer 10. Brittle material sheet 11...1st machining mark 12...2nd machining mark 20. Ultrashort pulse laser light source 100, 100a, 100b... Brittle material chips AF...Focus DL... Planned line to be divided L1... Laser light

Claims

1. A brittle material chip having a brittle material layer formed from a brittle material, A first processing mark is formed on one side in the thickness direction of the brittle material layer at at least one end face of the brittle material layer, and has a depth of 1 μm or more and less than half the thickness of the brittle material layer. A second processing mark is formed on the other side in the thickness direction of the end face of the brittle material layer, facing the first processing mark in the thickness direction, and having a depth of less than 1 μm. Brittle material chip.

2. The depth of the second processing mark is 100 nm or less. The brittle material chip according to claim 1.

3. The depth of the first processing mark is 10 μm or less. The brittle material chip according to claim 1 or 2.

4. The brittle material layer is formed from glass and has a thickness of 100 μm or less. A brittle material chip according to any one of claims 1 to 3.

5. It is essentially a rectangle in plan view, The end face having the first processing marks is a set of end faces corresponding to at least one pair of opposing sides of the rectangle. A brittle material chip according to any one of claims 1 to 4.

6. A brittle material sheet, which is divided along a planned dividing line to form a brittle material chip according to any one of claims 1 to 5, The brittle material layer has a first processing mark formed along the planned division line on one side of its thickness direction, The other side of the brittle material layer in the thickness direction has the second processing mark formed along the planned division line, Brittle material sheet.

7. A brittle material sheet that, when divided along a planned dividing line, forms a brittle material chip according to any one of claims 1 to 5, The brittle material layer has a first processing mark formed along the planned division line on one side of its thickness direction, The other side of the brittle material layer in the thickness direction has the second processing mark formed along the planned division line, or does not have the second processing mark. The resin material layer is formed from a resin material having a refractive index that is in complete contact with one side of the brittle material layer and has an absolute difference of 0.2 or less from the refractive index of the brittle material. Brittle material sheet.

8. The aforementioned resin material is an adhesive. The brittle material sheet according to claim 7.

9. A method for producing a brittle material sheet according to claim 6, The process includes a mark formation step in which an ultrashort pulse laser light source is positioned so as to face the other side of the brittle material layer in the thickness direction of the brittle material sheet before the first and second processing marks are formed, and the brittle material sheet is irradiated with laser light emitted from the ultrashort pulse laser light source along the planned division line of the brittle material sheet to remove the brittle material, thereby forming the first processing mark on one side of the brittle material layer in the thickness direction. A method for manufacturing brittle material sheets.

10. A method for producing a brittle material sheet according to claim 7 or 8, The process includes a mark formation step in which an ultrashort pulse laser light source is positioned facing the brittle material layer of the brittle material sheet before the first and second processing marks are formed, and the laser light emitted from the ultrashort pulse laser light source is irradiated onto the brittle material sheet from the brittle material layer side of the brittle material sheet along the planned division line of the brittle material sheet to remove the brittle material, thereby forming the first processing mark. A method for manufacturing brittle material sheets.

11. The laser light irradiated onto the brittle material sheet has a wavelength that is absorbed by the resin material layer but not absorbed by the brittle material layer. A method for producing a brittle material sheet according to claim 10.

12. The focal point of the laser beam irradiated onto the brittle material sheet is located on the surface of the brittle material layer opposite to the side where the ultrashort pulse laser light source is located, or at a position further away from the ultrashort pulse laser light source than that surface. A method for manufacturing a brittle material sheet according to any one of claims 9 to 11.

13. A peeling step of peeling the resin material layer from a brittle material sheet manufactured by the method of claim 10 or 11, A cutting step in which the brittle material sheet is divided along the planned cutting line by applying an external force that generates tension at the first processing mark to the brittle material sheet from which the resin material layer has been peeled off, A method for manufacturing brittle material chips having [a certain characteristic].

Images