Cover glass

Abstract

This suppresses outgassing and reduces the degradation of the optical properties of the cover glass. [Solution] The cover glass is provided on the surface of a glass substrate and has a fine uneven structure, and is equipped with an anti-reflective layer made of a cured product of a photocurable resin. The cured product of the photocurable resin is a polymer of a first monomer having a monofunctional (meth)acryloyl group and a second monomer having two or more functional (meth)acryloyl groups. The first monomer has either a cyclic structure consisting only of single bonds, or a cyclic structure consisting of single and multiple bonds, or both. The content of the first monomer relative to the total first and second monomers is 20% by mass or more and 50% by mass or less. The content of the second monomer relative to the total first and second monomers is 50% by mass or more and 80% by mass or less. The content of residual monomers derived from the first monomer contained in the polymer is 0.3% by mass or less.

Description

Technical Field

[0001] The present invention relates to a cover glass.

Background Art

[0002] An electronic device in which a sensor element is mounted on a mounting substrate is provided in, for example, a mobile terminal such as a smartphone, an automobile, a monitoring system, or the like. In an electronic device, in order to improve the sensitivity of the sensor element, the sensor element is covered with a cover glass having an antireflection function.

[0003] As a cover glass having an antireflection function, a cover glass provided with an antireflection layer made of resin having a fine uneven structure has been developed. Such a cover glass is manufactured by supplying a curable resin composition between a master disk and a base material, curing it, and transferring the fine uneven structure of the master disk to the surface of the curable resin composition (nanoimprint method) (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When manufacturing the above-described electronic device, first, a cover glass is installed at a position facing the light receiving surface of the sensor element to assemble a sensor module. Then, the sensor module is placed on a mounting substrate and heated to solder (reflow) the sensor module to the mounting substrate.

[0006] As described above, the sensor module is heated during reflow soldering, and this heating causes outgassing from the anti-reflective layer of the cover glass. Outgassing degrades the optical properties of the cover glass, and in particular, it reduces the transmittance of light with wavelengths of 400 nm or higher.

[0007] Therefore, the present invention has been made in view of the above problems, and aims to provide a cover glass that can suppress the generation of outgassing and suppress the deterioration of the optical properties of the cover glass. [Means for solving the problem]

[0008] To solve the above problems, according to one aspect of the present invention, A cover glass that covers a sensor element mounted on a substrate for electronic devices, Glass substrate and An anti-reflective layer is provided on at least one surface of the glass substrate, having a fine uneven structure with an average period of irregularities less than or equal to the wavelength of visible light, and made of a cured product of a photocurable resin. Equipped with, The cured product of the photocurable resin is a polymer of a first monomer having a monofunctional (meth)acryloyl group and a second monomer having two or more functional (meth)acryloyl groups. The first monomer has a cyclic structure consisting only of single bonds, and a cyclic structure consisting of single bonds and multiple bonds, or one or both of these. The content of the first monomer relative to the total amount of the first monomer and the second monomer is 20% by mass or more and 50% by mass or less. The content of the second monomer relative to the total amount of the first monomer and the second monomer is 50% by mass or more and 80% by mass or less. A cover glass is provided in which the content of residual monomers derived from the first monomer contained in the polymer is 0.3% by mass or less. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress outgassing and thereby suppress the deterioration of the optical properties of the cover glass. [Brief explanation of the drawing]

[0010] [Figure 1] This is a flowchart illustrating a method for manufacturing an electronic device according to one embodiment of the present invention. [Figure 2] This is a process diagram illustrating the cleaning and pretreatment process, resin layer formation process, transfer process, curing process, release process, and post-curing process according to one embodiment of the present invention. [Figure 3] This is a process diagram illustrating the baking process according to one embodiment of the present invention. [Figure 4] This diagram illustrates an anti-reflective layer according to one embodiment of the present invention. [Figure 5] This is a process diagram illustrating the assembly process related to one embodiment of the present invention. [Figure 6] This is a process diagram illustrating the reflow process according to one embodiment of the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0012] Please note that in the drawings referenced in the following explanation, the size of some components may be exaggerated for illustrative purposes. Therefore, the relative sizes of the components shown in each drawing do not necessarily accurately represent the actual size relationships between the components.

[0013] [1. Methods for manufacturing electronic devices] First, referring to FIGS. 1 to 6, a method for manufacturing an electronic device 300 according to an embodiment of the present invention will be described. FIG. 1 is a flowchart for explaining a method for manufacturing an electronic device 300 according to an embodiment of the present invention. FIG. 2 is a process diagram for explaining a cleaning and pretreatment step S110, a resin layer forming step S120, a transfer step S130, a curing step S140, a release step S150, and a post-curing step S160 according to an embodiment of the present invention. In FIG. 2, for ease of understanding, the description of the treatment on the surface 14 is omitted. FIG. 3 is a process diagram for explaining a baking step S170 according to an embodiment of the present invention. FIG. 4 is a diagram for explaining an antireflection layer 40 according to an embodiment of the present invention. FIG. 5 is a process diagram for explaining an assembly step S180 according to an embodiment of the present invention. FIG. 6 is a process diagram for explaining a reflow step S190 according to an embodiment of the present invention.

[0014] As shown in FIG. 1, the method for manufacturing the electronic device 300 according to the present embodiment includes a cleaning and pretreatment step S110, a resin layer forming step S120, a transfer step S130, a curing step S140, a release step S150, a post-curing step S160, a baking step S170, an assembly step S180, and a reflow step S190. Hereinafter, each step will be described.

[0015] [Cleaning and Pretreatment Step S110] First, the glass substrate 10 is cleaned. The glass substrate 10 is formed of a transparent material such as, for example, non-alkali glass, borosilicate glass, quartz, or sapphire.

[0016] Then, as shown in FIG. 2, pretreatment and silane treatment are performed on the surface 12 of the glass substrate 10 and the surface 14 on the opposite side of the surface 12.

[0017] The pretreatment is, for example, corona discharge surface treatment, blast surface treatment, plasma surface treatment, excimer surface treatment, flame surface treatment, etching, polishing, etc. The silane treatment is performed by spin-coating a primer on the surfaces 12 and 14 of the glass substrate 10 and heating it. The primer is a silane coupling agent, for example, KBM5103, KBM603, KBM403, X-12-1048 manufactured by Shin-Etsu Chemical Co., Ltd.

[0018] [Resin layer forming step S120] As shown in FIG. 2, uncured resin layers 20 are formed on the surfaces 12 and 14 on both sides of the glass substrate 10. For example, an uncured resin layer 20 may be formed by applying an uncured photocurable resin to the surface 12 of the glass substrate 10 using a coating device (not shown). Alternatively, an uncured resin layer 20 may be formed by dropping an uncured photocurable resin onto the surface 12 of the glass substrate 10. That is, the uncured resin layer 20 is made of an uncured photocurable resin.

[0019] The uncured photocurable resin contains more than 0% by mass and 50% by mass or less of a monomer having a monofunctional (meth)acryloyl group, 50% by mass or more and less than 100% by mass of a monomer having a bifunctional or higher (meth)acryloyl group, and a photopolymerization initiator.

[0020] When the proportion of the monomer having a monofunctional (meth)acryloyl group contained in the uncured photocurable resin is less than or equal to the proportion of the monomer having a bifunctional or higher (meth)acryloyl group, it is possible to reduce the amount of outgas generated in the reflow step S190 described later. Also, when assembled as the electronic device 300, it is possible to improve the parallel line transmittance of the cover glass 100. Furthermore, the heat resistance of the antireflection layer 40 described later can be improved.

[0021] It is preferable that the monomer having a monofunctional (meth)acryloyl group has either a cyclic structure consisting only of single bonds, or a cyclic structure consisting of single and multiple bonds (e.g., a benzene ring), or both. Monomers having a monofunctional (meth)acryloyl group having a cyclic structure have a rigid carbon skeleton. Therefore, by including a monomer having a monofunctional (meth)acryloyl group having a cyclic structure in the uncured photocurable resin, the heat resistance of the anti-reflective layer 40 can be improved.

[0022] Monomers having a monofunctional (meth)acryloyl group include, for example, dicyclopentanyl (meth)acrylate and isobornyl (meth)acrylate, either one or both. Examples of monomers having a monofunctional (meth)acryloyl group include FA513M manufactured by Showa Denko Materials K.K., light acrylate IB-XA manufactured by Kyoeisha Chemical Co., Ltd., and light ester IB-X manufactured by Kyoeisha Chemical Co., Ltd.

[0023] Monomers having two or more functional (meth)acryloyl groups include, for example, either or both of dipentaerythritol hexaacrylate and dioxane glycol diacrylate. Another example of a monomer having two or more functional (meth)acryloyl groups is DPHA, R-604, manufactured by Nippon Kayaku Co., Ltd.

[0024] A photopolymerization initiator is, for example, Irgacure 184.

[0025] [Transfer process S130] The transfer process S130 is a process of transferring the fine uneven structure 32 of the master disc 30 to the uncured resin layer 20 provided on both sides of the glass substrate 10, surfaces 12 and 14.

[0026] As shown in Figure 2, the master plate 30 is pressed against the uncured resin layer 20, and the fine uneven structure 32 of the master plate 30 is transferred to the uncured resin layer 20, thereby forming a fine uneven structure 42 on the uncured resin layer 20. The average period of the unevenness in the fine uneven structure 42 is less than or equal to the wavelength of visible light. Here, the average period of the unevenness corresponds to the pitch between multiple protrusions (or pitch between multiple recesses) of the fine uneven structure 32. The average period of such unevenness is set to less than or equal to any wavelength within the visible light wavelength band, depending on the desired anti-reflective properties of the anti-reflective layer 40 provided on the cover glass 100. For example, if the visible light wavelength band is 360 nm to 830 nm, the average period of the unevenness may be, for example, 830 nm or less or 360 nm or less. In this embodiment, it is preferable that the master plate 30 is formed from a material that can transmit light (e.g., ultraviolet light).

[0027] [Curing process S140] The curing step S140 is a step in which the uncured resin layer 20, onto which the fine uneven structure 42 has been transferred, is irradiated with light to cure the uncured resin layer 20.

[0028] As described above, in this embodiment, the master disc 30 is made of a light-transmitting material. Therefore, as shown in Figure 2, the uncured resin layer 20 is irradiated with light while the master disc 30 is pressed against it. This cures the uncured resin layer 20 on the glass substrate 10. In other words, in this embodiment, the transfer process S130 and the curing process S140 are performed simultaneously (in parallel).

[0029] [Release process S150] After the uncured resin layer 20 has hardened, the master disc 30 is released from the hardened uncured resin layer 22. [Post-curing process S160] The uncured resin layer 22 after demolding is further irradiated with light to accelerate the curing of the uncured resin layer 22.

[0030] Thus, as shown in Figure 3, an anti-reflective layer 40 is formed on the surface 12 of the glass substrate 10, which is made of a cured product 24 of a photocurable resin and has a fine uneven structure 42 in which the average period of the unevenness is less than or equal to the wavelength of visible light.

[0031] As shown in Figure 4, the micro-textured structure 42 may be, for example, a so-called moth-eye structure. For example, the protrusions and recesses of the micro-textured structure 42 are arranged in the X and Y directions on the surface 12 (XY plane) of the glass substrate 10. The micro-textured structure 42 formed on the surface of the anti-reflective layer 40 can impart an anti-reflective function to the cover glass 100 that corresponds to the average period of the irregularities of the micro-textured structure 42.

[0032] Furthermore, as shown in Figure 3, in this embodiment, the other surface 14 (back surface) of the glass substrate 10 is subjected to the same treatment as the treatment performed on the surface 12 described above, thereby forming an anti-reflective layer 40 on the other surface 14.

[0033] In this way, a cover glass 100 is manufactured in which an anti-reflective layer 40 is formed on both sides of the glass substrate 10, surfaces 12 and 14. However, the example is not limited to this, and the anti-reflective layer 40 may be formed on only one surface of the glass substrate 10.

[0034] [Baking process S170] The baking process S170 is a process of heating the cover glass 100. The baking process S170 is a process of applying heat treatment as a pretreatment for the reflow process S190, which will be described later. In this embodiment, in the baking process S170, the cover glass 100 is heated at a temperature of 150°C or higher and less than 250°C for 30 minutes or more.

[0035] If the heating temperature of the cover glass 100 is less than 150°C, the amount of outgassing (hereinafter sometimes simply referred to as "monomer-derived outgassing") originating from the monomer having a monofunctional (meth)acryloyl group contained in the anti-reflective layer 40 is small. In other words, if the heating temperature of the cover glass 100 is less than 150°C, the amount of monomer having a monofunctional (meth)acryloyl group contained in the anti-reflective layer 40 is large. As a result, when the reflow process S190 is performed, a large amount of monomer-derived outgassing is generated.

[0036] Therefore, in the baking step S170, by heating the cover glass 100 to a temperature of 150°C or higher, monomer-derived outgassing can be suitably generated from the anti-reflective layer 40, thereby reducing the residual amount of monomer having a monofunctional (meth)acryloyl group contained in the anti-reflective layer 40. This makes it possible to reduce the amount of monomer-derived outgassing generated from the cover glass 100 in the subsequent reflow step S190.

[0037] On the other hand, if the heating temperature of the cover glass 100 is 250°C or higher, the anti-reflective layer 40 that makes up the cover glass 100 will deform, and the parallel line transmittance of the cover glass 100 will decrease.

[0038] Therefore, in this embodiment, in the baking step S170, the cover glass 100 is heated to a temperature of less than 250°C. This makes it possible to prevent a decrease in the parallel line transmittance of the cover glass 100 after the baking step S170 is performed.

[0039] To explain in more detail, when the baking process S170 of the cover glass 100 is performed, the parallel line transmittance of the cover glass 100 for light with a wavelength of 400 nm is, for example, 93% or more. Also, the parallel line transmittance of the cover glass 100 for light with a wavelength of 550 nm is, for example, 94% or more. The parallel line transmittance of the cover glass 100 for light with a wavelength of 650 nm is, for example, 94.5% or more. Also, the parallel line transmittance of the cover glass 100 for light with a wavelength of 900 nm is, for example, 95.5% or more.

[0040] The parallel line transmittance is calculated based on the following formula (1). Parallel transmittance [%]=(I / I0)×100…Formula (1)

[0041] In equation (1) above, I0 is the intensity of the parallel lines incident on the cover glass 100. I is the intensity of the parallel lines that have passed through the cover glass 100.

[0042] Furthermore, if the heating time of the cover glass 100 in the baking process S170 is less than 30 minutes, the amount of monomer-derived outgassing in the anti-reflective layer 40 is small. In other words, if the heating time of the cover glass 100 is less than 30 minutes, a large amount of monomer having a monofunctional (meth)acryloyl group remains in the anti-reflective layer 40. As a result, when the reflow process S190 is performed, a large amount of monomer-derived outgassing is generated.

[0043] Therefore, in the baking process S170, the cover glass 100 is heated for 30 minutes or more to reduce the amount of monomer having a monofunctional (meth)acryloyl group contained in the anti-reflective layer 40. This makes it possible to reduce the amount of monomer-derived outgassing in the subsequent reflow process S190.

[0044] Furthermore, the heating time of the cover glass 100 in the baking process S170 is preferably 60 minutes or less. Even if the heating time of the cover glass 100 exceeds 60 minutes, the amount of monomer-derived outgassing does not change much compared to when the heating time is 60 minutes, so the energy required for heating for more than 60 minutes is wasted. For this reason, by setting the heating time of the cover glass 100 in the baking process S170 to 60 minutes or less, it is possible to reduce the energy required for heating while ensuring the amount of monomer-derived outgassing is maintained, thereby improving energy efficiency.

[0045] The cover glass 100 according to this embodiment is manufactured by the above process. The cover glass 100 comprises a glass substrate 10 and an anti-reflective layer 40 provided on both sides of the glass substrate 10's surfaces 12 and 14. The anti-reflective layer 40 has a fine uneven structure 42 in which the average period of the unevenness is less than or equal to the wavelength of visible light, and consists of a cured product 24 of a photocurable resin. The cured product 24 of the photocurable resin is a polymer of monomers having monofunctional (meth)acryloyl groups and monomers having bifunctional or more (meth)acryloyl groups.

[0046] Preferably, the content of residual monomers derived from the monomer having a monofunctional (meth)acryloyl group contained in the polymer is 0.3% by mass or less. This makes it possible to maintain a high parallel line transmittance of the cover glass 100 and to reduce the amount of monomer-derived outgassing in the reflow process S190.

[0047] [Assembly process S180] Assembly process S180 is a process of assembling the sensor module 200 by placing the cover glass 100 after baking process S170 at a position facing the light-receiving surface 222 of the sensor element 220.

[0048] As shown in Figure 5, the assembly step S180 of this embodiment involves installing the cover glass 100 on the sensor unit 210 to assemble the sensor module 200. The sensor unit 210 includes a sensor element 220 and a package substrate 230.

[0049] The sensor element 220 is, for example, an image sensor, LiDAR, etc. The image sensor is, for example, a visible light image sensor, an infrared image sensor, an ultraviolet image sensor, or an X-ray image sensor. The image sensor may be, for example, a CCD image sensor or a CMOS image sensor.

[0050] The package substrate 230 is, for example, a ball grid array. In this embodiment, the package substrate 230 includes a housing section 232, a printed circuit board 234, and solder balls 236. The housing section 232 houses the printed circuit board 234. The housing section 232 is formed of, for example, epoxy resin. The plurality of solder balls 236 are provided on the lower surface of the housing section 232. The plurality of solder balls 236 are connected to the printed circuit board 234 by wiring (not shown).

[0051] The sensor element 220 is mounted on the printed circuit board 234. In this embodiment, the side of the sensor element 220 opposite to the light-receiving surface 222 contacts the printed circuit board 234. The sensor element 220 and the printed circuit board 234 are connected by bonding wires 234a.

[0052] As shown in Figure 5, in assembly step S180 according to this embodiment, the cover glass 100 is placed on the upper part of the housing portion 232 of the package substrate 230, and the cover glass 100 and the sensor element 220 are placed facing each other with a distance between them to assemble the sensor module 200. However, the assembly method of the sensor module 200 is not limited to the example in Figure 5, and other assembly methods are also possible as long as the cover glass 100 is placed in a position facing the light-receiving surface 222 of the sensor element 220.

[0053] [Reflow Process S190] The reflow process S190 is a process of placing the sensor module 200 on the mounting substrate 250 and heating it to a temperature of 250°C or higher. In this embodiment, the reflow process S190 involves placing the sensor module 200 on the mounting substrate 250 and then housing it in the reflow furnace RF. The temperature inside the reflow furnace RF is then raised to 250°C or higher.

[0054] During the reflow process S190, the heat treatment melts multiple solder balls 236 of the sensor module 200, and the sensor module 200 is soldered to the mounting substrate 250. This manufactures the electronic device 300. In the electronic device 300, a sensor element 220 covered by a cover glass 100 is mounted on the mounting substrate 250.

[0055] As described above, according to this embodiment, a baking step S170 is performed as a heating step preceding the reflow step S190. As a result, in the reflow step S190, the generation rate of outgassing from the anti-reflective layer 40 of the cover glass 100 that originates from monomers having monofunctional (meth)acryloyl groups is 0.5% by mass or less relative to the mass of the anti-reflective layer 40.

[0056] The outgassing rate is calculated based on the following formula (2) by analyzing the outgass generated when the anti-reflective layer 40 is heated to 265°C using a gas chromatography-mass spectrometer (GC-MS). OG[mass%]=PAc×S[mg] / PAs / C[mg]×100…Formula (2)

[0057] In formula (2) above, OG is the outgassing rate [mass%] derived from monomers having monofunctional (meth)acryloyl groups. PAc is the peak area of ​​outgassing derived from monomers having monofunctional (meth)acryloyl groups, obtained by gas chromatography-mass spectrometry. PAs is the peak area of ​​a standard substance (e.g., tetradecane), obtained by gas chromatography-mass spectrometry. S is the weight [mg] of the standard substance added during the measurement. C is the weight [mg] of the anti-reflective layer 40.

[0058] As described above, according to the manufacturing method of the electronic device 300 of this embodiment, by performing the baking step S170 before the reflow step S190, the generation rate of outgassing from the anti-reflective layer 40 of the cover glass 100 that originates from monomers having monofunctional (meth)acryloyl groups can be reduced to 0.5% by mass or less relative to the mass of the anti-reflective layer 40 during the reflow step S190.

[0059] This makes it possible to suppress the generation of outgassing, which could induce corrosion of wiring materials and other components within the electronic device 300, during high-temperature reflow processes (e.g., 250-270°C). Therefore, it is possible to suppress corrosion of the sensor element 220, printed circuit board 234, bonding wire 234a, and various wiring components provided on the mounting substrate 250 of the electronic device 300.

[0060] Furthermore, as a monomer having a monofunctional (meth)acryloyl group, a monomer having a cyclic monofunctional (meth)acryloyl group is used, and the baking process S170 is performed before the reflow process S190. This makes it possible to suppress the deterioration of the optical properties of the cover glass 100 caused by outgassing, such as yellowing of the cover glass 100 (deterioration of short-wavelength transmittance) and deterioration of anti-reflective performance (sagging of the fine uneven structure 42). Therefore, it becomes possible to improve the parallel line transmittance of the cover glass 100 in the electronic device 300, and to ensure high transmission performance of the cover glass 100 for light with wavelengths of 400 nm or more. In this way, by improving the transmission performance of the cover glass 100, the imaging performance of an image sensor covered with the cover glass 100 can be improved.

[0061] Conventionally, when cover glass is formed from a resin material, there is a problem that the transmittance drops for light in the short-wavelength visible light range. In contrast, the cover glass 100 according to this embodiment suppresses the drop in transmittance for light in the short-wavelength visible light range and ensures high transmittance for light with wavelengths of 400 nm or more.

[0062] To explain in more detail, when the cover glass 100 undergoes the reflow process S190, the parallel line transmittance of the cover glass 100 for light with a wavelength of 400 nm is, for example, 92% or more. Furthermore, the parallel line transmittance of the cover glass 100 for light with a wavelength of 550 nm is, for example, 94% or more. The parallel line transmittance of the cover glass 100 for light with a wavelength of 650 nm is, for example, 95% or more. Furthermore, the parallel line transmittance of the cover glass 100 for light with a wavelength of 900 nm is, for example, 95% or more.

[0063] As a result, incident light from the outside can pass through the high-transmittance cover glass 100 well and reach the sensor element 220. Therefore, it is possible to suppress the decrease in light-receiving sensitivity of the sensor element 220 caused by using a resin cover glass 100.

[0064] Furthermore, it is possible to suppress the re-reflection of light reflected by the sensor element 220 by the cover glass 100. This makes it possible to suppress false reactions of the sensor element 220 caused by re-reflection by the cover glass 100.

[0065] Furthermore, as described above, the parallel line transmittance of the cover glass 100 after the reflow process S190 for light with a wavelength of 400 nm, that is, the cover glass 100 of the electronic device 300, is, for example, 92% or more. Therefore, the cover glass 100 can be applied to a sensor element 220 that receives not only visible light but also infrared light.

[0066] Furthermore, by using a monomer having a cyclic monofunctional (meth)acryloyl group as the monomer having a monofunctional (meth)acryloyl group, deformation of the fine uneven structure 42 of the anti-reflective layer 40 can be suppressed. This makes it possible to avoid a decrease in the anti-reflective performance of the anti-reflective layer 40. [Examples]

[0067] The following sections will specifically describe examples and comparative examples of the present invention. It should be noted that the following examples are merely illustrative, and the method for manufacturing electronic devices and the cover glass according to the present invention are not limited to the examples described below.

[0068] Examples 1 to 7 and Comparative Examples 1 to 3 were prepared as cover glasses.

[0069] [Example 1] An uncured photocurable resin composition was prepared by mixing a monomer having a monofunctional (meth)acryloyl group, a monomer having two or more functional (meth)acryloyl groups, and a photopolymerization initiator. FA513M from Showa Denko Materials Co., Ltd. was used as the monomer having a monofunctional (meth)acryloyl group. DPHA and R-604 from Nippon Kayaku Co., Ltd. were used as the monomer having two or more functional (meth)acryloyl groups. The mixing ratio of DPHA to R-604 was 40:20. Irgacure 184 was used as the photopolymerization initiator. In Example 1, the content of monomers having two or more functional (meth)acryloyl groups was 60% by mass, the content of monomers having a monofunctional (meth)acryloyl group was 40% by mass, and the content of the photopolymerization initiator was 3% by mass.

[0070] A primer was spin-coated onto the glass substrate 10 and heated on a hot plate at 150°C for 4 minutes.

[0071] Then, the uncured photocurable resin composition was potted onto the primer-treated glass substrate 10, and the master plate 30 was placed over the uncured photocurable resin composition. After that, the transfer process S130 and the curing process S140 were performed using an imprint apparatus. The transfer process S130 and the curing process S140 were carried out under constant conditions of 40°C.

[0072] First, in the transfer process S130, the master disc 30 was pressurized to 1000N over 30 seconds, and then the pressure of 1000N was maintained for 30 seconds. Then, in the curing process S140, the photocurable resin composition was exposed using an LED lamp and the pressure was released over 10 seconds. Subsequently, the master disc 30 was released from the photocurable resin composition on the glass substrate 10, and then the photocurable resin composition on the glass substrate 10 was heated to 1000 mJ / cm using a UV conveyor. 2 The photocurable resin composition was cured by exposure. As a result, an anti-reflective layer 40 having a fine uneven structure 42, consisting of the cured product 24 of the photocurable resin composition, was formed on the glass substrate 10, and a cover glass 100 was obtained.

[0073] Next, the baking process S170 was performed. In the baking process S170, the cover glass 100 was heated at 150°C for 30 minutes using a hot plate. The cover glass 100 according to Example 1 was manufactured through the above process. Then, the reflow process S190 was performed. In the reflow process S190, the cover glass 100 was heated at 265°C for 5 minutes, and the outgassing rate was measured.

[0074] [Example 2] Except for setting the heating temperature in the baking process S170 to 180°C, the cover glass 100 according to Example 2 was manufactured in the same manner as in Example 1.

[0075] [Example 3] Except for setting the heating temperature in the baking step S170 to 200°C, the cover glass 100 according to Example 3 was manufactured in the same manner as in Example 1.

[0076] [Example 4] Except for setting the heating temperature in the baking process S170 to 220°C, the cover glass 100 according to Example 4 was manufactured in the same manner as in Example 1.

[0077] [Example 5] Cover glass 100 according to Example 5 was produced in the same manner as in Example 1, except for the blending ratio of DPHA and R-604 in the uncured photocurable resin composition, the content of monomers having two or more functional (meth)acryloyl groups, and the content of monomers having monofunctional (meth)acryloyl groups. In Example 5, the blending ratio of DPHA to R-604 was 50:20. In addition, the content of monomers having two or more functional (meth)acryloyl groups in the uncured photocurable resin composition was 70% by mass, and the content of monomers having monofunctional (meth)acryloyl groups was 30% by mass.

[0078] [Example 6] Cover glass 100 according to Example 6 was produced in the same manner as in Example 1, except for the blending ratio of DPHA and R-604 in the monomers having two or more functional (meth)acryloyl groups in the uncured photocurable resin composition, the content of monomers having two or more functional (meth)acryloyl groups, and the content of monomers having monofunctional (meth)acryloyl groups. In Example 6, the blending ratio of DPHA to R-604 was 60:20. In addition, the content of monomers having two or more functional (meth)acryloyl groups in the uncured photocurable resin composition was 80% by mass, and the content of monomers having monofunctional (meth)acryloyl groups was 20% by mass.

[0079] [Example 7] Cover glass 100 according to Example 7 was produced in the same manner as in Example 1, except for the blending ratio of DPHA and R-604 in the uncured photocurable resin composition, the content of monomers having two or more functional (meth)acryloyl groups, and the content of monomers having monofunctional (meth)acryloyl groups. In Example 7, the blending ratio of DPHA to R-604 was 70:20. In addition, the content of monomers having two or more functional (meth)acryloyl groups in the uncured photocurable resin composition was 90% by mass, and the content of monomers having monofunctional (meth)acryloyl groups was 10% by mass.

[0080] [Comparative Example 1] A cover glass according to Comparative Example 1 was manufactured in the same manner as in Example 1, except that the heating temperature in the baking step S170 was set to 250°C.

[0081] [Comparative Example 2] A cover glass according to Comparative Example 2 was manufactured in the same manner as in Example 1, except that the heating temperature in the baking step S170 was set to 130°C.

[0082] [Comparative Example 3] A cover glass according to Comparative Example 3 was manufactured in the same manner as in Example 1, except that the baking step S170 was omitted.

[0083] [Measurement of outgassing rate] The cover glass samples obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were heated to 265°C, and the resulting outgassing was analyzed by gas chromatography-mass spectrometry (GC-MS). The generation rate [mass%] of outgassing originating from monomers having monofunctional (meth)acryloyl groups was then calculated using formula (2) above.

[0084] [Measurement of parallel line transmittance] In Examples 1 to 7 and Comparative Examples 1 to 3 described above, the parallel line transmittance of the sample was measured after the baking process S170 but before the reflow process S190. In addition, in Examples 1 to 7 and Comparative Examples 1 to 3 described above, the parallel line transmittance of the cover glass was measured after the reflow process S190.

[0085] Parallel line transmittance was measured using a "UV-Vis-Near-Infrared Spectrophotometer V-770" manufactured by JASCO Corporation. Then, the transmittance of the cover glass at wavelengths of 400 nm, 550 nm, 650 nm, and 900 nm was calculated using the above formula (1).

[0086] Table 1 below shows the outgassing rate [mass%] and parallel line transmittance derived from monomers having monofunctional (meth)acryloyl groups in Examples 1 to 4. Table 2 below shows the outgassing rate [mass%] and parallel line transmittance derived from monomers having monofunctional (meth)acryloyl groups in Examples 5 to 7. In Tables 1, 2, and 3, "〇" indicates a good evaluation of each evaluation item, and "◎" indicates a very good evaluation.

[0087] [Table 1]

[0088] [Table 2]

[0089] As shown in Examples 1 to 4 of Table 1, it was confirmed that the higher the heating temperature in baking step S170, the lower the outgassing rate [mass%] derived from monomers having monofunctional (meth)acryloyl groups. Furthermore, it was found that the higher the heating temperature in baking step S170, the lower the total outgassing rate [mass%].

[0090] Furthermore, as shown in Examples 1 to 4 in Table 1, it was found that the higher the heating temperature in the baking process S170, the lower the parallel line transmittance at 400 nm of the sample after the baking process S170 but before the reflow process S190. However, even at the highest heating temperature of 220°C in the baking process S170 (Example 4), the parallel line transmittance for light at a wavelength of 400 nm was confirmed to be high at 93.2%.

[0091] As shown in Examples 1 to 4 of Table 1, regardless of the heating temperature in the baking process S170, it was confirmed that the parallel line transmittance of the sample after the baking process S170 but before the reflow process S190 for light at wavelengths of 550 nm, 650 nm, and 900 nm was high, at 94% or more.

[0092] Furthermore, as shown in Examples 1 to 4 in Table 1, it was found that the higher the heating temperature in the baking process S170, the lower the parallel line transmittance of the sample after the reflow process S190 for light at a wavelength of 400 nm. However, even at the highest heating temperature of 220°C in the baking process S170 (Example 4), the parallel line transmittance for light at a wavelength of 400 nm was confirmed to be high at 92%.

[0093] As shown in Examples 1 to 4 of Table 1, regardless of the heating temperature in the baking process S170, the parallel line transmittance of the sample after the reflow process S190 for light at wavelengths of 550 nm, 650 nm, and 900 nm was confirmed to be high at 94% or more.

[0094] Furthermore, as shown in Examples 1, 5 to 7 in Table 1, it was confirmed that the lower the content of monomers having monofunctional (meth)acryloyl groups in the uncured photocurable resin composition, the lower the outgassing rate [mass%] originating from monomers having monofunctional (meth)acryloyl groups. It was also found that the lower the content of monomers having monofunctional (meth)acryloyl groups in the uncured photocurable resin composition, the lower the total outgassing rate [mass%].

[0095] As shown in Examples 1, 5, and 7 of Table 1, regardless of the content of monomers having monofunctional (meth)acryloyl groups in the uncured photocurable resin composition, it was confirmed that the parallel line transmittance of the sample after the baking step S170 but before the reflow step S190 for light at wavelengths of 400 nm, 550 nm, 650 nm, and 900 nm was high, at 94% or more.

[0096] Furthermore, as shown in Examples 1, 5, and 7 in Table 1, regardless of the content of monomers having monofunctional (meth)acryloyl groups in the uncured photocurable resin composition, it was confirmed that the parallel line transmittance of the sample after the reflow process S190 for light at wavelengths of 400 nm, 550 nm, 650 nm, and 900 nm was high, at 92% or more.

[0097] Table 3 below shows the outgassing rate [mass%] and parallel line transmittance derived from monomers having monofunctional (meth)acryloyl groups for Comparative Examples 1 to 3. In Table 3, "△" indicates a poor evaluation of each evaluation item, and "×" indicates a very poor evaluation.

[0098] [Table 3]

[0099] As shown in Comparative Example 1 of Table 3, it was found that when the heating temperature in the baking step S170 is 250°C, the rate of outgassing [mass%] originating from monomers having monofunctional (meth)acryloyl groups, and the rate of total outgassing [mass%] are lower.

[0100] However, as shown in Comparative Example 1 in Table 3, when the heating temperature in the baking process S170 is 250°C, the parallel line transmittance of the sample after the baking process S170 but before the reflow process S190 for light at a wavelength of 400 nm was found to be low at 88.9%. Furthermore, it was found that the parallel line transmittance of the sample after the reflow process S190 for light at a wavelength of 400 nm was low at 88.3%.

[0101] As shown in Comparative Example 2 of Table 3, it was confirmed that when the heating temperature in baking step S170 was 130°C, the outgassing rate [mass%] originating from monomers having monofunctional (meth)acryloyl groups was high at 0.59 mass%. Furthermore, it was found that when the heating temperature in baking step S170 was 130°C, the total outgassing rate [mass%] was high at 0.69 mass%.

[0102] Furthermore, as shown in Comparative Example 2 of Table 3, when the heating temperature in the baking process S170 was 130°C, the parallel line transmittance of the sample after the baking process S170 but before the reflow process S190 was 93.7% for light at a wavelength of 400 nm. However, it was confirmed that when the heating temperature in the baking process S170 was 130°C, the parallel line transmittance of the sample after the reflow process S190 for light at a wavelength of 400 nm was low at 91.2%.

[0103] As shown in Comparative Example 3 of Table 3, it was confirmed that the outgassing rate [mass%] derived from monomers having monofunctional (meth)acryloyl groups was 0.32 mass% when the baking step S170 was not performed. Furthermore, it was found that the total outgassing rate [mass%] was high at 0.74 mass% when the baking step S170 was not performed.

[0104] Furthermore, as shown in Comparative Example 3 of Table 3, when the baking step S170 was not performed, the parallel line transmittance of the sample before the reflow step S190 for light at a wavelength of 400 nm was 93.4%. However, it was confirmed that when the baking step S170 was not performed, the parallel line transmittance of the sample after the reflow step S190 for light at a wavelength of 400 nm was low at 91.5%.

[0105] From the above results, it was confirmed that by setting the heating temperature in the baking process S170 to 150°C or higher and less than 250°C, the outgassing rate [mass%] derived from monomers having monofunctional (meth)acryloyl groups can be reduced to 0.5 mass% or less.

[0106] Furthermore, it was found that by setting the heating temperature in the baking process S170 to 150°C or higher and less than 250°C, the parallel line transmittance of the sample after the reflow process S190 for light with a wavelength of 400 nm can be made 92% or higher.

[0107] As described above, this embodiment makes it possible to reduce the rate of outgassing originating from monomers having monofunctional (meth)acryloyl groups and to maintain a high parallel line transmittance of the cover glass 100. Therefore, the manufacturing method of the electronic device 300 according to this embodiment can suppress corrosion of the electronic device 300 while maintaining a high parallel line transmittance of the cover glass 100.

[0108] Embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these embodiments. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention.

[0109] For example, in the above embodiment, the case was given in which the uncured resin layer 20 is cured by irradiating the uncured resin layer 20 with light while transferring the fine uneven structure 32 of the master disc 30 to the uncured resin layer 20. However, the uncured resin layer 20 may be cured by irradiating the uncured resin layer 20 with light after transferring the fine uneven structure 32 of the master disc 30 to the uncured resin layer 20.

[0110] Furthermore, in the above embodiment, the outgassing rate originating from monomers having monofunctional (meth)acryloyl groups was calculated using the results of analysis by gas chromatography-mass spectrometry (GC-MS) as an example. However, the outgassing rate originating from monomers having monofunctional (meth)acryloyl groups may be calculated using other methods. [Explanation of symbols]

[0111] S130 Transfer process S140 hardening process S170 Baking process S180 Assembly Process S190 Reflow Process 10 Glass substrate 12 Surface 14 Surface 20 Uncured resin layer 30 Original recordings 32 Fine uneven structure 40 Anti-reflection layer 42 Fine uneven structure 100 Cover glass 200 Sensor Modules 220 Sensor elements 222 Photosensitive surface 250 mounted circuit boards 300 Electronic Devices

Claims

[Claim 1] A cover glass that covers a sensor element mounted on a substrate for electronic devices, Glass substrate and An anti-reflective layer is provided on at least one surface of the glass substrate, having a fine uneven structure with an average period of irregularities less than or equal to the wavelength of visible light, and made of a cured product of a photocurable resin. Equipped with, The cured product of the photocurable resin is a polymer of a first monomer having a monofunctional (meth)acryloyl group and a second monomer having two or more functional (meth)acryloyl groups. The first monomer has a cyclic structure consisting only of single bonds, and a cyclic structure consisting of single bonds and multiple bonds, or one or both of these cyclic structures. The content of the first monomer relative to the total amount of the first monomer and the second monomer is 20% by mass or more and 50% by mass or less. The content of the second monomer relative to the total amount of the first monomer and the second monomer is 50% by mass or more and 80% by mass or less. A cover glass in which the content of residual monomers derived from the first monomer contained in the polymer is 0.3% by mass or less.

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