Sheet for encapsulating optical semiconductor element and optical semiconductor device

Abstract

To provide a sheet for encapsulating an optical semiconductor element that can sufficiently fill the gap between the optical semiconductor element and a substrate during encapsulation, and that is less likely to create gaps between a plurality of optical semiconductor elements.SOLUTION: A sheet 1 for encapsulating optical semiconductor elements is a sheet for encapsulating one or more optical semiconductor elements 6 placed on a substrate 5. The sheet 1 for encapsulating optical semiconductor elements comprises an encapsulation resin layer 2 that includes at least a curable resin layer (X) 21 and an adhesive layer 22. The viscosity of the curable resin layer (X)21 at the encapsulating temperature is 2 to 2000 kPas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet for encapsulating an optical semiconductor element and an optical semiconductor device. More specifically, the present invention relates to a sheet suitable for use in encapsulating an optical semiconductor element, and an optical semiconductor device having a structure in which the sheet encapsulates an optical semiconductor element. [Background technology]

[0002] Self-emitting display devices such as mini / micro LED display devices (Mini / Micro Light Emitting Diode Displays) are known to have a structure in which multiple LEDs are arranged on a substrate and sealed with a sealing resin. A known method for sealing the multiple LEDs collectively using the sealing resin is to pour liquid resin into the area where the multiple LEDs are arranged, bury the multiple LEDs, and then harden the liquid resin by applying heat or ultraviolet light.

[0003] However, the method of encapsulating optical semiconductor elements such as LEDs using a liquid resin has problems such as poor handling, such as dripping when the liquid resin is applied and adhesion of the liquid resin to unintended areas, etc. In contrast, by using an encapsulating sheet having an encapsulating layer for encapsulating optical semiconductor elements instead of using a liquid resin, it is possible to encapsulate the optical semiconductor elements easily and in a short time using a simple process.

[0004] As such a sealing sheet, for example, Patent Document 1 discloses a pressure-sensitive adhesive sheet which is a laminate of a colored pressure-sensitive adhesive layer and a colorless pressure-sensitive adhesive layer, and the colorless pressure-sensitive adhesive layer is positioned so as to contact an optical semiconductor element. Also, for example, Patent Document 2 discloses a resin sheet which includes a curable resin composition layer and is used for sealing electronic components. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-169262 [Patent Document 2] Japanese Patent Application Publication No. 2019-67852 Summary of the Invention [Problem to be solved by the invention]

[0006]

[0003] Incidentally, for example, in a flip-chip type semiconductor device in which an optical semiconductor element is directly bump-connected to a substrate, a gap exists between the bump-connected optical semiconductor element and the substrate. Liquid resins have conventionally been used as encapsulating resins (underfill materials) capable of filling such gaps. However, as described above, the method using liquid resins has the problem of poor handling, and therefore, an encapsulating sheet that is easy to handle is required even when used to fill the gaps.

[0007] However, in an encapsulating sheet composed of a pressure-sensitive adhesive layer as disclosed in Patent Document 1, the fluidity of the pressure-sensitive adhesive layer is low, making it difficult to sufficiently fill the gaps between the optical semiconductor elements and the substrate. Also, in an encapsulating sheet composed of a curable resin composition layer as disclosed in Patent Document 2, although the gaps can be sufficiently filled, the fluidity of the resin composition layer is too high, causing gaps to form between multiple optical semiconductor elements formed on the substrate, which may adversely affect the appearance of the optical semiconductor device.

[0008] The present invention was conceived under these circumstances, and its purpose is to provide a sheet for encapsulating optical semiconductor elements that can sufficiently fill the gap between the optical semiconductor element and the substrate when encapsulating the optical semiconductor element, and that is less likely to produce gaps between multiple optical semiconductor elements. [Means for solving the problem]

[0009] As a result of intensive research to achieve the above object, the present inventors have found that, with a specific encapsulating sheet, when an optical semiconductor element is encapsulated, it is possible to sufficiently fill voids between the optical semiconductor element and the substrate, and voids are unlikely to occur between a plurality of optical semiconductor elements. The present invention has been completed based on these findings.

[0010] That is, the present invention provides a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, the sheet includes a sealing resin layer including at least a curable resin layer and a pressure-sensitive adhesive layer; The sheet for encapsulating an optical semiconductor element is provided, wherein the viscosity of the curable resin layer at the encapsulation temperature is 2 to 2000 kPa·s.

[0011] The curable resin layer is preferably located on the optical semiconductor element side of the pressure-sensitive adhesive layer.

[0012] The curable resin layer preferably has thermosetting properties.

[0013] The curable resin layer preferably contains a black colorant.

[0014] The pressure-sensitive adhesive layer is preferably a non-colored pressure-sensitive adhesive layer.

[0015] The pressure-sensitive adhesive layer is preferably a diffusion functional layer.

[0016] The curable resin layer preferably has a light transmittance of 0 to 80% at a wavelength of 600 nm after curing.

[0017] In a state where the optical semiconductor element is encapsulated, the distance from the optical semiconductor element to the curable resin layer is preferably 0 to 20 μm.

[0018] The thickness of the pressure-sensitive adhesive layer is preferably 30% or more of the distance from the surface of the substrate to the apex of the optical semiconductor element.

[0019] The thickness of the curable resin layer is preferably 70 to 150 μm.

[0020] The thickness of the pressure-sensitive adhesive layer is preferably 30 to 100 μm.

[0021] The sheet for sealing an optical semiconductor element preferably includes a substrate and the sealing resin layer laminated on the substrate.

[0022] The pressure-sensitive adhesive layer is preferably located on the substrate side with respect to the thermosetting resin layer.

[0023] The present invention also provides an optical semiconductor device comprising: a substrate; an optical semiconductor element disposed on the substrate; and the optical semiconductor element encapsulation sheet or a cured product thereof that encapsulates the optical semiconductor element. [Effects of the Invention]

[0024] According to the optical semiconductor element encapsulation sheet of the present invention, when an optical semiconductor element is encapsulated, the gap between the optical semiconductor element and the substrate can be sufficiently filled, and gaps are unlikely to occur between multiple optical semiconductor elements. Therefore, when the resin filled between multiple optical semiconductor elements is colored, optical interference between the optical semiconductor elements can be suppressed, resulting in a good appearance of the optical semiconductor device. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view of a sheet for encapsulating an optical semiconductor element according to one embodiment of the present invention. [Figure 2] 2 is a partial cross-sectional view showing one embodiment of an optical semiconductor device using the optical semiconductor element encapsulation sheet shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0026] [Optical semiconductor element encapsulation sheet] The optical semiconductor element encapsulation sheet of the present invention includes at least an encapsulating resin layer including a curable resin layer and a pressure-sensitive adhesive layer. In this specification, the optical semiconductor element encapsulation sheet refers to a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate with the encapsulating resin layer. In this specification, "encapsulating an optical semiconductor element" refers to embedding at least a portion of the optical semiconductor element in the encapsulating resin layer or covering the optical semiconductor element with the encapsulating resin layer. The encapsulating resin layer has flexibility that allows it to embed at least a portion of the optical semiconductor element or to cover the optical semiconductor element with the encapsulating resin layer.

[0027] <Sealing resin layer> The encapsulating resin layer includes at least the curable resin layer and the adhesive layer. The encapsulating resin layer may include layers other than the curable resin layer and the adhesive layer. Each of the layers (curable resin layer and adhesive layer) constituting the encapsulating resin layer may be a single layer within the encapsulating resin layer, or may be multiple layers having the same or different compositions. When multiple curable resin layers and adhesive layers are included, the multiple layers may be laminated in contact with each other or may be laminated separately (for example, two curable resin layers laminated with one adhesive layer interposed therebetween).

[0028] When encapsulating an optical semiconductor element, it is preferable that at least one curable resin layer in the encapsulating resin layer be located on the optical semiconductor element side relative to at least one pressure-sensitive adhesive layer. In particular, it is preferable that the layer that comes into contact with the optical semiconductor element when encapsulating the optical semiconductor element (i.e., the layer in the encapsulating resin layer that is closest to the optical semiconductor element) be a curable resin layer. With this configuration, the curable resin layer flows during encapsulation of the optical semiconductor element to fill the gap between the optical semiconductor element and the substrate, and the pressure-sensitive adhesive layer can fill gaps between adjacent optical semiconductor elements that may be generated by the flow of the curable resin layer.

[0029] (curable resin layer) The encapsulating resin layer includes at least a curable resin layer having a viscosity of 2 to 2000 kPa·s at the encapsulating temperature. In this specification, the curable resin layer may be referred to as a "curable resin layer (X)." The encapsulating resin layer may include a curable resin layer other than the curable resin layer (X).

[0030] As described above, the viscosity of the curable resin layer (X) at the sealing temperature is 2 to 2000 kPa·s, preferably 3 to 1500 kPa·s, and more preferably 10 to 1200 kPa·s. When the viscosity is 2 kPa or more, the fluidity of the curable resin layer is not too low, making it difficult for voids to form between adjacent optical semiconductor elements. Furthermore, when the viscosity is 2000 kPa or less, the curable resin layer (X) flows during sealing of the optical semiconductor elements, filling the voids between the optical semiconductor elements and the substrate. The sealing temperature is preferably 35 to 120°C, more preferably 40 to 110°C, even more preferably 60 to 105°C, and particularly preferably 70 to 100°C. In other words, it is preferable that the viscosity at at least one point between 35 and 120°C (preferably 40 to 110°C, more preferably 60 to 105°C, and even more preferably 70 to 100°C) be within the above range. The viscosity can be controlled, for example, by the monomer composition and weight average molecular weight of the resin constituting the adhesive composition for forming the adhesive layer, the amount (addition amount) of the polyfunctional monomer and crosslinking agent used, and the type and content of other additives.

[0031] Examples of the curable resin layer include a thermosetting resin layer having thermosetting properties and an active energy ray-curable resin layer having active energy ray-curability. Examples of the active energy ray include an electron beam, ultraviolet light, α-rays, β-rays, γ-rays, and X-rays. Among these, a thermosetting resin layer is preferred from the viewpoint of ease of curing after being bonded to an optical semiconductor element.

[0032] Resins constituting the curable resin layer include known or commonly used resins, such as acrylic resins, urethane acrylate resins, urethane resins, rubber resins, epoxy resins, epoxy acrylate resins, oxetane resins, silicone resins, silicone acrylic resins, polyester resins, polyether resins (such as polyvinyl ether), polyamide resins, fluorine-containing resins, vinyl acetate / vinyl chloride copolymers, and modified polyolefins. Only one of the above resins may be used, or two or more may be used. Among these, acrylic resins are preferred.

[0033] The acrylic resin is a resin containing a structural unit derived from an acrylic monomer (a monomer component having a (meth)acryloyl group or a structure convertible thereto in the molecule) as a structural unit of the resin (polymer). Only one type of the acrylic resin may be used, or two or more types may be used.

[0034] The acrylic resin is preferably a resin containing the most structural units derived from (meth)acrylic acid esters by mass. In this specification, "(meth)acrylic" refers to "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to other terms.

[0035] The curable resin layer preferably contains a thermosetting resin, since it is preferable that the curable resin layer has thermosetting properties. As the thermosetting resin, a known or commonly used thermosetting resin can be used, for example, a resin having a thermosetting functional group. Among them, an acrylic resin having a thermosetting functional group (a thermosetting functional group-containing acrylic resin) is preferred as the thermosetting resin.

[0036] Examples of the thermosetting functional group include epoxy group-containing groups such as glycidyl groups, carboxy groups, hydroxy groups, isocyanate groups, and aziridyl groups. Among these, epoxy group-containing groups are preferred, and glycidyl groups are more preferred. That is, as an acrylic resin having a thermosetting functional group, a glycidyl group-containing acrylic resin is particularly preferred. The thermosetting functional group may be one type or two or more types.

[0037] The thermosetting functional group-containing acrylic resin preferably contains a structural unit derived from a monomer having a thermosetting functional group, and more preferably contains a structural unit derived from an acrylic monomer having a thermosetting functional group (a thermosetting functional group-containing acrylic monomer). Examples of the monomer having a thermosetting functional group include epoxy group-containing (meth)acrylic esters such as glycidyl group-containing (meth)acrylic esters, carboxy group-containing monomers, acid anhydride group-containing monomers, and hydroxy group-containing (meth)acrylic esters.

[0038] Examples of the glycidyl group-containing (meth)acrylic acid ester include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.

[0039] Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Examples of the acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, etc.

[0040] Examples of the hydroxy group-containing (meth)acrylic acid ester include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0041] Among the thermosetting functional group-containing acrylic monomers, epoxy group-containing (meth)acrylic esters are preferred, and glycidyl group-containing (meth)acrylic esters are more preferred. When the acrylic resin contains a structural unit derived from an epoxy group-containing (meth)acrylic ester, the epoxy group acts as a thermosetting functional group, and even without a curing agent, the reaction of the epoxy group proceeds by thermal curing, resulting in the curing of the curable resin layer. Therefore, the curable resin layer has appropriate flexibility after thermal curing, and is superior in encapsulating optical semiconductor elements.

[0042] The content of the structural units derived from the epoxy group-containing (meth)acrylic acid ester is preferably 5 to 50 mass %, more preferably 6 to 45 mass %, relative to the total amount (100 mass %) of all structural units of the acrylic resin in the curable resin layer. When the content is within this range, the curable resin layer has appropriate flexibility after thermal curing and is more excellent in sealing the optical semiconductor element.

[0043] The thermosetting functional group-containing acrylic resin may contain a constituent unit derived from a monomer other than the thermosetting functional group-containing monomer. Examples of the other monomer include (meth)acrylic acid esters other than the thermosetting functional group-containing acrylic monomer. The other monomers may be used singly or in combination of two or more.

[0044] Examples of the other (meth)acrylic acid esters include hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group. Examples of the hydrocarbon group-containing (meth)acrylic acid esters in the hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group include (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group, (meth)acrylic acid esters having an alicyclic hydrocarbon group such as (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid esters having an aromatic hydrocarbon group such as (meth)acrylic acid aryl esters. The hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group may be used singly or in combination of two or more.

[0045] Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and methyl (meth)acrylate. Examples of the acrylate include isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0046] Among the above-mentioned (meth)acrylic acid alkyl esters, (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group with a carbon number of 1 to 20 (preferably 1 to 14, more preferably 2 to 10, and even more preferably 2 to 8) are preferred. When the carbon number is within the above range, the flexibility of the thermosetting group-containing acrylic resin during heat curing tends to be more appropriate, and embeddability is further improved.

[0047] Examples of the (meth)acrylic acid ester having an alicyclic hydrocarbon group include (meth)acrylic acid esters having a monocyclic aliphatic hydrocarbon ring such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; and (meth)acrylic acid esters having a tricyclic or higher aliphatic hydrocarbon ring such as dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0048] Examples of the (meth)acrylic acid ester having an aromatic hydrocarbon group include (meth)acrylic acid phenyl ester and (meth)acrylic acid benzyl ester.

[0049] Examples of hydrocarbon group-containing (meth)acrylic acid esters having alkoxy groups include those in which one or more hydrogen atoms in the hydrocarbon group of the above hydrocarbon group-containing (meth)acrylic acid esters have been substituted with alkoxy groups, such as 2-methoxymethyl ester, 2-methoxyethyl ester, and 2-methoxybutyl ester of (meth)acrylic acid.

[0050] Examples of the other monomer components include polar group-containing monomers such as sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, and nitrogen atom-containing monomers. Examples of the sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of the phosphoric acid group-containing monomers include 2-hydroxyethyl acryloyl phosphate. Examples of the nitrogen atom-containing monomers include morpholino group-containing monomers such as (meth)acryloylmorpholine, cyano group-containing monomers such as (meth)acrylonitrile, and amide group-containing monomers such as (meth)acrylamide.

[0051] The thermosetting functional group-containing acrylic resin may contain a structural unit derived from a polyfunctional (meth)acrylate copolymerizable with the monomer components constituting the acrylic resin to form a crosslinked structure in the polymer skeleton. Examples of the polyfunctional (meth)acrylate include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. The polyfunctional (meth)acrylate may be used alone or in combination of two or more.

[0052] The thermosetting functional group-containing acrylic resin is obtained by polymerizing the above-mentioned various monomer components. The polymerization method is not particularly limited, but examples thereof include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). The obtained acrylic resin may be any of random copolymers, block copolymers, graft copolymers, etc.

[0053] The weight-average molecular weight of the epoxy group-containing acrylic resin is preferably 2,000 to 400,000, more preferably 30,000 to 300,000, from the viewpoint of providing a certain degree of hardness after curing of the curable resin layer and reducing adhesion between the side surfaces of the optical semiconductor device. When the weight-average molecular weight is within the above range, the embedding ability of the optical semiconductor element is superior. The weight-average molecular weight is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0054] The content of the epoxy group-containing acrylic resin is preferably 40% by mass or more (for example, 40 to 100% by mass) relative to the total amount (100% by mass) of resin in the curable resin layer, more preferably 50% by mass or more, and even more preferably 60% by mass or more. When the content is 40% by mass or more, the embeddability of the optical semiconductor element is superior.

[0055] The curable resin layer preferably contains a component having a functional group (second functional group) that can react with the thermosetting functional group (first functional group) in the thermosetting functional group-containing acrylic resin by heat. The second functional group is also a thermosetting functional group. In this case, the first functional group reacts with the second functional group when the curable resin layer is heated, thereby further promoting the curing of the curable resin layer.

[0056] The component having the second functional group may be a thermosetting functional group-containing acrylic resin having the first functional group, a thermosetting functional group-containing acrylic resin other than the thermosetting functional group-containing acrylic resin having the first functional group, or another component having a second functional group. Only one type of component having the second functional group may be used, or two or more types may be used.

[0057] Examples of combinations of the first functional group and the second functional group include a carboxy group and an epoxy group, an epoxy group and a carboxy group, a carboxy group and an aziridyl group, an aziridyl group and a carboxy group, a hydroxy group and an isocyanate group, an isocyanate group and a hydroxy group, etc. The combinations may be of only one type or two or more types.

[0058] When the curable resin layer contains the epoxy group-containing acrylic resin, the curable resin layer preferably contains a component having a functional group reactive with an epoxy group as the component having the second functional group. Examples of the functional group reactive with an epoxy group include a carboxy group, an aziridyl group, and a hydroxy group. Among these, a carboxy group and a hydroxy group are preferred. As the hydroxy group, a silanol group is preferred from the viewpoint of high acidity and excellent reactivity with an epoxy group.

[0059] The component having a carboxy group is preferably the resin described above, more preferably a carboxy group-containing acrylic resin. The inclusion of the carboxy group-containing acrylic resin facilitates the reaction between the epoxy group and the carboxy group in the epoxy group-containing acrylic resin, even without a curing agent, and provides superior sealing of optical semiconductor elements. Furthermore, the surface scratch resistance is further improved.

[0060] The carboxyl group-containing acrylic resin preferably contains a structural unit derived from a carboxyl group-containing monomer, more preferably a structural unit derived from a carboxyl group-containing acrylic monomer, such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, or crotonic acid.

[0061] The content of the structural units derived from the carboxyl group-containing acrylic monomer is preferably 1 to 50 mass %, more preferably 10 to 40 mass %, relative to the total amount (100 mass %) of all structural units of the carboxyl group-containing acrylic resin. When the content is within the above range, the curable resin layer has appropriate flexibility after thermal curing and is superior in encapsulating the optical semiconductor element.

[0062] The carboxyl group-containing acrylic resin may contain a constituent unit derived from a monomer other than the carboxyl group-containing monomer. Examples of the other monomer include (meth)acrylic acid esters other than the thermosetting functional group-containing acrylic monomer, the polar group-containing monomers, and the polyfunctional (meth)acrylates. The other monomers may be used singly or in combination of two or more.

[0063] Examples of the other (meth)acrylic acid esters include the hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group. As the (meth)acrylic acid alkyl esters in the hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group, (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 14, more preferably 1 to 10, and even more preferably 1 to 8) are preferred. When the carbon number is within the above range, the flexibility of the thermosetting group-containing acrylic resin is more likely to be appropriate, and the embeddability is further improved.

[0064] In order to properly exhibit basic properties such as adhesion to the optical semiconductor element in the curable resin layer, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group relative to the total amount (100% by mass) of all structural units of the carboxy group-containing acrylic resin is preferably 50 to 95% by mass, more preferably 60 to 90% by mass.

[0065] The weight-average molecular weight of the carboxyl group-containing acrylic resin is preferably 1,000 to 200,000, and more preferably 3,000 to 100,000. When the weight-average molecular weight is within the above range, the sealing properties of the optical semiconductor element are superior. The weight-average molecular weight is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0066] When the carboxyl group-containing acrylic resin is contained, the content of the carboxyl group-containing acrylic resin is preferably 5 to 60 mass %, more preferably 10 to 50 mass %, and even more preferably 25 to 45 mass %, relative to the total amount (100 mass %) of resin in the curable resin layer. When the content is within the above range, the curable resin layer has better thermosetting properties and better scratch resistance.

[0067] The curable resin layer may contain a colorant. For example, if the curable resin layer contains a colorant, it can prevent light reflection from metal wiring or the like provided on a substrate in an image display device. In particular, if the curable resin layer located closer to the optical semiconductor element than the pressure-sensitive adhesive layer, such as the curable resin layer (X), contains a colorant, when the optical semiconductor element is encapsulated, the gap between the optical semiconductor element and the substrate is filled, and a thin colored layer remains on the upper and side surfaces of the optical semiconductor element. This can further suppress optical interference between the optical semiconductor elements, improving the appearance of the optical semiconductor device.

[0068] The colorant may be a dye or a pigment as long as it is soluble or dispersible in the curable resin layer. Dyes are preferred because they can achieve low haze even with a small amount added, do not settle like pigments, and are easily distributed uniformly. Pigments are also preferred because they provide high color expression even with a small amount added. When using a pigment as a colorant, it is preferable that it has low or no conductivity. One or more of the above colorants may be used.

[0069] The colorant is preferably a black colorant. Known or commonly used colorants (pigments, dyes, etc.) for producing black can be used as the black colorant, including, for example, carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine soot, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complexes, anthraquinone-based colorants, and zirconium nitride. Alternatively, a colorant functioning as a black colorant may be used by combining and blending colorants producing colors other than black.

[0070] When the curable resin layer is an active energy ray-curable resin layer, the colorant preferably absorbs visible light and transmits light of a wavelength that can cure the active energy ray-curable resin layer.

[0071] From the viewpoint of imparting an appropriate anti-reflection property to the image display device, the content of the colorant in the curable resin layer is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, relative to the total amount (100% by mass) of the curable resin layer. The content of the colorant is, for example, 5% by mass or less, preferably 1% by mass or less, and more preferably 0.5% by mass or less. The content may be appropriately set depending on the type of colorant, the color tone and light transmittance of the image display device, and the like. The colorant may be added to the composition as a solution or dispersion in which it is dissolved or dispersed in an appropriate solvent.

[0072] The curable resin layer may contain other components in addition to the above-mentioned components, as long as the effects of the present invention are not impaired. Examples of the other components include thermoplastic resins, coupling agents such as silane coupling agents, crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), oligomers, antioxidants, fillers (organic fillers, inorganic particles, etc.), light-diffusing fine particles, antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, UV absorbers, polymerization inhibitors, granular materials, foil-like materials, etc. The other components may each be used alone or in combination of two or more.

[0073] The resin content in the curable resin layer is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the total amount (100% by mass) of the curable resin layer. The content is preferably 99.99% by mass or less, more preferably 99% by mass or less, and even more preferably 95% by mass or less. The content of the acrylic resin is preferably within the above range, the content of the thermosetting resin is preferably within the above range, and the content of the thermosetting functional group-containing acrylic resin is preferably within the above range.

[0074] The light transmittance at a wavelength of 600 nm after curing of the curable resin layer is not particularly limited, but from the viewpoint of further improving the anti-reflection function and contrast of metal wiring and the like in the optical semiconductor device, it is preferably 80% or less, more preferably 60% or less, even more preferably 40% or less, and particularly preferably 30% or less. Moreover, the light transmittance is 0% or more, and from the viewpoint of ensuring the brightness of the optical semiconductor device, it is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, particularly preferably 2% or more, and may be 2.5% or more, or 3% or more.

[0075] The thickness of the curable resin layer (X) is preferably 50 to 150 μm, more preferably 60 to 130 μm, and even more preferably 70 to 120 μm. If the thickness is 50 μm or more, a large amount of the curable resin layer remains between the optical semiconductor elements during encapsulation, making it difficult for gaps to form between the optical semiconductor elements. If the thickness is 150 μm or less, the brightness of the light emitted by the optical semiconductor elements will be higher.

[0076] The thickness of the curable resin layer (X) is preferably 60% or more, more preferably 70% or more, of the distance from the surface of the substrate to the apex of the optical semiconductor element. If the thickness is 60% or more, a large amount of the curable resin layer remains between the optical semiconductor elements during encapsulation, making it less likely that gaps will form between the optical semiconductor elements. The thickness is, for example, 130% or less, preferably 120% or less, more preferably 110% or less, of the distance from the surface of the substrate to the apex of the optical semiconductor element. If the thickness is 130% or less, the brightness of the light emitted by the optical semiconductor element will be higher.

[0077] (Adhesive layer) In this specification, the term "adhesive layer" refers to a layer that has the property of adhering two surfaces together and, if necessary, peeling them off due to the cohesive force of the chemical structure of the composition in response to external pressure (e.g., minute pressure). The adhesive layer is preferably a resin layer made of resin. Examples of resins constituting the adhesive layer include known or commonly used resins, such as acrylic resins, urethane acrylate resins, urethane resins, rubber resins, epoxy resins, epoxy acrylate resins, oxetane resins, silicone resins, silicone acrylic resins, polyester resins, polyether resins (e.g., polyvinyl ether), polyamide resins, fluorine-containing resins, vinyl acetate / vinyl chloride copolymers, and modified polyolefins. One or more of the above resins may be used.

[0078] Furthermore, known or commonly used pressure-sensitive adhesives can be used as the resin. Examples of the adhesive include acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, and mixtures thereof), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. One or more of the adhesives may be used.

[0079] The acrylic resin is a polymer containing, as a structural unit of the polymer, a structural unit derived from an acrylic monomer. The acrylic resin may be used alone or in combination of two or more.

[0080] Examples of the (meth)acrylic acid ester include hydrocarbon group-containing (meth)acrylic acid esters. Examples of the hydrocarbon group-containing (meth)acrylic acid ester include (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group, (meth)acrylic acid esters having an alicyclic hydrocarbon group such as (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid esters having an aromatic hydrocarbon group such as (meth)acrylic acid aryl esters. The hydrocarbon group-containing (meth)acrylic acid esters may be used singly or in combination of two or more.

[0081] Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and methyl (meth)acrylate. Examples of the acrylate include isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0082] Among the (meth)acrylic acid alkyl esters, (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group with a carbon number of 1 to 20 (preferably 1 to 14, more preferably 2 to 10) are preferred. When the carbon number is within the above range, it is easy to adjust the glass transition temperature of the acrylic resin, and it is easy to make the adhesive properties of the pressure-sensitive adhesive layer more appropriate.

[0083] Examples of the (meth)acrylic acid ester having an alicyclic hydrocarbon group include (meth)acrylic acid esters having a monocyclic aliphatic hydrocarbon ring such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; and (meth)acrylic acid esters having a tricyclic or higher aliphatic hydrocarbon ring such as dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0084] Examples of the (meth)acrylic acid ester having an aromatic hydrocarbon group include (meth)acrylic acid phenyl ester and (meth)acrylic acid benzyl ester.

[0085] The hydrocarbon group-containing (meth)acrylic acid ester preferably contains a (meth)acrylic acid alkyl ester having a linear or branched aliphatic hydrocarbon group, and more preferably contains a (meth)acrylic acid ester having an alicyclic hydrocarbon group, which provides a well-balanced adhesive layer and excellent conformability to the irregularities of the adherend.

[0086] In order to adequately exhibit the basic properties of the hydrocarbon group-containing (meth)acrylic ester, such as adhesiveness and adhesion to an adherend, in the pressure-sensitive adhesive layer, the proportion of the hydrocarbon group-containing (meth)acrylic ester in all monomer components constituting the acrylic resin is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, relative to the total amount (100% by mass) of all monomer components. Furthermore, from the viewpoint of copolymerizing other monomer components and obtaining the effects of those other monomer components, the proportion is preferably 95% by mass or less, more preferably 80% by mass or less.

[0087] The proportion of the (meth)acrylic acid alkyl ester having a linear or branched aliphatic hydrocarbon group in all the monomer components constituting the acrylic resin is preferably 30% by mass or more, more preferably 40% by mass or more, relative to the total amount (100% by mass) of all the monomer components, and is preferably 90% by mass or less, more preferably 70% by mass or less.

[0088] The proportion of the (meth)acrylic acid ester having an alicyclic hydrocarbon group in all the monomer components constituting the acrylic resin is preferably 1% by mass or more, more preferably 5% by mass or more, relative to the total amount (100% by mass) of all the monomer components, and is preferably 30% by mass or less, more preferably 20% by mass or less.

[0089] The acrylic resin may contain a structural unit derived from another monomer component copolymerizable with the hydrocarbon group-containing (meth)acrylic acid ester for the purpose of introducing a third functional group (described below) or for the purpose of modifying properties such as cohesive strength and heat resistance. Examples of the other monomer component include polar group-containing monomers such as carboxy group-containing monomers, acid anhydride monomers, hydroxy group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, and nitrogen atom-containing monomers. Only one type of each of the other monomer components may be used, or two or more types may be used.

[0090] Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Examples of the acid anhydride monomer include maleic anhydride, itaconic anhydride, etc.

[0091] Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0092] Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.

[0093] Examples of the sulfonic acid group-containing monomer include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

[0094] Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

[0095] Examples of the nitrogen atom-containing monomer include morpholino group-containing monomers such as (meth)acryloylmorpholine, cyano group-containing monomers such as (meth)acrylonitrile, and amide group-containing monomers such as (meth)acrylamide.

[0096] The polar group-containing monomer constituting the acrylic resin preferably contains a hydroxy group-containing monomer. Use of the hydroxy group-containing monomer facilitates the introduction of a third functional group, which will be described later. Furthermore, the acrylic resin and the pressure-sensitive adhesive layer have excellent water resistance, and are less likely to cloud and have excellent whitening resistance even when used in a high-humidity environment.

[0097] The hydroxy group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate, more preferably 2-hydroxyethyl (meth)acrylate.

[0098] In order to adequately exhibit the basic properties of the hydrocarbon group-containing (meth)acrylic acid ester, such as adhesiveness and adhesion to an adherend, in the pressure-sensitive adhesive layer, the proportion of the polar group-containing monomer in the total monomer components (100% by mass) constituting the acrylic resin is preferably 5 to 50% by mass, more preferably 10 to 40% by mass. In particular, from the viewpoint of achieving even better water resistance of the pressure-sensitive adhesive layer, it is preferable that the proportion of the hydroxy group-containing monomer be within the above range.

[0099] The other monomer components may further include vinyl monomers such as caprolactone adducts of (meth)acrylic acid, vinyl acetate, vinyl propionate, styrene, and α-methylstyrene; glycol acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and alkoxy group-substituted hydrocarbon group-containing (meth)acrylate (2-methoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, etc.).

[0100] The proportion of the other monomer components in all monomer components (100% by mass) constituting the acrylic resin is, for example, about 3 to 50% by mass, and may be 5 to 40% by mass or 10 to 30% by mass.

[0101] The acrylic resin may contain a structural unit derived from a polyfunctional (meth)acrylate copolymerizable with the monomer components constituting the acrylic resin to form a crosslinked structure in the polymer skeleton. Examples of the polyfunctional (meth)acrylate include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. The polyfunctional (meth)acrylate may be used alone or in combination of two or more.

[0102] In order to properly exhibit the basic properties of the hydrocarbon group-containing (meth)acrylic acid ester, such as adhesiveness and adhesion to the substrate, in the adhesive layer, the proportion of the polyfunctional (meth)acrylate in the total monomer components (100% by mass) constituting the acrylic resin is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0103] The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer that has the property of being cured by irradiation with active energy rays (active energy ray-curable pressure-sensitive adhesive layer), may be a pressure-sensitive adhesive layer that has thermosetting properties (thermosetting pressure-sensitive adhesive layer), or may be a pressure-sensitive adhesive layer that does not have the property of being cured (non-curable pressure-sensitive adhesive layer).

[0104] When the pressure-sensitive adhesive layer is an active energy ray-curable pressure-sensitive adhesive layer, examples of the pressure-sensitive adhesive layer include a layer containing a base polymer and an active energy ray-polymerizable monomer component or oligomer component having a functional group such as an active energy ray-polymerizable carbon-carbon double bond, and a layer containing a polymer (particularly, an acrylic resin) having an active energy ray-polymerizable functional group as a base polymer.

[0105] Examples of the active energy ray-polymerizable functional group include active energy ray-radical polymerizable groups, such as groups containing a carbon-carbon unsaturated bond, such as ethylenically unsaturated groups, and active energy ray-cationically polymerizable groups. Examples of the carbon-carbon unsaturated bond-containing group include vinyl groups, propenyl groups, isopropenyl groups, acryloyl groups, and methacryloyl groups. Examples of the active energy ray-cationically polymerizable group include epoxy groups, oxetanyl groups, and oxolanyl groups. Among these, groups containing a carbon-carbon unsaturated bond are preferred, with acryloyl groups and methacryloyl groups being more preferred. The active energy ray-polymerizable functional group may be of only one type or two or more types. The active energy ray-polymerizable functional group may be located on a polymer side chain, in the polymer main chain, or at the end of the polymer main chain.

[0106] The polymer having the active energy ray polymerizable functional group can be prepared by, for example, a method of reacting a polymer having a reactive functional group (third functional group) with a functional group (fourth functional group) that can form a bond with the third functional group and a compound having the active energy ray polymerizable functional group, while maintaining the active energy ray polymerizability of the active energy ray polymerizable functional group, to bond.Therefore, the polymer having the active energy ray polymerizable functional group preferably comprises a structural part derived from the polymer having the third functional group, and a structural part derived from the compound having the fourth functional group and the active energy ray polymerizable functional group.

[0107] Examples of combinations of the third functional group and the fourth functional group include a carboxy group and an epoxy group, an epoxy group and a carboxy group, a carboxy group and an aziridyl group, an aziridyl group and a carboxy group, a hydroxy group and an isocyanate group, and an isocyanate group and a hydroxy group. Among these, from the viewpoint of ease of reaction tracking, a combination of a hydroxy group and an isocyanate group, and a combination of an isocyanate group and a hydroxy group are preferred. The above combinations may be one type only, or two or more types.

[0108] Examples of the compound having the active energy polymerizable functional group and the isocyanate group include methacryloyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate (MOI), m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc. One or more of the above compounds may be used.

[0109] In order to further promote the curing of the active energy ray-curable pressure-sensitive adhesive layer, the content of the structural part derived from the compound having the fourth functional group and the active energy ray-polymerizable functional group in the acrylic resin having the active energy ray-polymerizable functional group is preferably 0.5 mol or more, more preferably 1 mol or more, even more preferably 3 mol or more, and particularly preferably 10 mol or more relative to the total amount (100 mol) of the structural part derived from the acrylic resin having the third functional group. The content is, for example, 100 mol or less.

[0110] The molar ratio of the fourth functional group to the third functional group in the acrylic resin having the active energy ray-polymerizable functional group [fourth functional group / third functional group] is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.2 or more, and particularly preferably 0.4 or more, from the viewpoint of further promoting the curing of the active energy ray-curable pressure-sensitive adhesive layer. Moreover, from the viewpoint of further reducing low-molecular-weight substances in the active energy ray-curable pressure-sensitive adhesive layer, the molar ratio is preferably less than 1.0, more preferably 0.9 or less.

[0111] The acrylic resin can be obtained by polymerizing the various monomer components described above. The polymerization method is not particularly limited, but examples thereof include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). The obtained acrylic resin can be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

[0112] The acrylic resin having the active energy ray-polymerizable functional group can be prepared, for example, by polymerizing (copolymerizing) a raw material monomer containing a monomer component having a third functional group to obtain an acrylic resin having the third functional group, and then subjecting a compound having the fourth functional group and the active energy ray-polymerizable functional group to a condensation reaction or addition reaction with the acrylic resin while maintaining the active energy ray-polymerizability of the active energy ray-polymerizable functional group.

[0113] Various common solvents may be used in the polymerization of the monomer components. Examples of the solvent include organic solvents such as esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. One or more of the solvents may be used.

[0114] The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization of the monomer components are not particularly limited and can be appropriately selected and used. The weight-average molecular weight of the acrylic resin can be controlled by the amounts of the polymerization initiator and chain transfer agent used and the reaction conditions, and the amounts used are appropriately adjusted depending on the types of these.

[0115] As the polymerization initiator used for polymerizing the monomer components, a thermal polymerization initiator, a photopolymerization initiator (photoinitiator), etc. can be used depending on the type of polymerization reaction. Only one of the above polymerization initiators may be used, or two or more of them may be used.

[0116] The thermal polymerization initiator is not particularly limited, and examples thereof include azo-based polymerization initiators, peroxide-based polymerization initiators, redox-based polymerization initiators, etc. The amount of the thermal polymerization initiator used is preferably 1 part by mass or less, more preferably 0.005 to 1 part by mass, and even more preferably 0.02 to 0.5 parts by mass, relative to 100 parts by mass of the total amount of all monomer components constituting the acrylic resin having the third functional group.

[0117] Examples of the photopolymerization initiator include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, titanocene-based photopolymerization initiators, etc. Among these, acetophenone-based photopolymerization initiators are preferred.

[0118] Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and methoxyacetophenone.

[0119] The amount of the photopolymerization initiator used is preferably 0.005 to 1 part by mass, more preferably 0.01 to 0.7 parts by mass, and even more preferably 0.18 to 0.5 parts by mass, relative to 100 parts by mass of the total amount of all monomer components constituting the acrylic resin. When the amount used is 0.005 part by mass or more (particularly 0.18 part by mass or more), it is easy to control the molecular weight of the acrylic resin to a low value, and the resin layer tends to have better conformability to irregularities.

[0120] The reaction between the acrylic resin having the third functional group and the compound having the fourth functional group and an active energy ray-polymerizable functional group can be carried out, for example, by stirring in a solvent in the presence of a catalyst. Examples of the solvent include those mentioned above. The catalyst is appropriately selected depending on the combination of the third functional group and the fourth functional group. The reaction temperature in the reaction is, for example, 5 to 100°C, and the reaction time is, for example, 1 to 36 hours.

[0121] The acrylic resin may have a structural moiety derived from a crosslinking agent. For example, the acrylic resin may be crosslinked to further reduce low-molecular-weight substances in the pressure-sensitive adhesive layer. Furthermore, the weight-average molecular weight of the acrylic resin may be increased. When the acrylic resin has active energy ray-polymerizable functional groups, the crosslinking agent crosslinks functional groups other than the active energy ray-polymerizable functional groups (e.g., between third functional groups, between fourth functional groups, or between a third functional group and a fourth functional group). Only one type of crosslinking agent may be used, or two or more types may be used.

[0122] Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a melamine-based crosslinking agent, a peroxide-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, an amine-based crosslinking agent, a silicone-based crosslinking agent, and a silane-based crosslinking agent. Among these, from the viewpoints of excellent adhesion to optical semiconductor elements and low impurity ions, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred as the crosslinking agent, and isocyanate-based crosslinking agents are more preferred.

[0123] Examples of the isocyanate-based crosslinking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of the isocyanate crosslinking agent include a trimethylolpropane / tolylene diisocyanate adduct, a trimethylolpropane / hexamethylene diisocyanate adduct, and a trimethylolpropane / xylylene diisocyanate adduct.

[0124] The content of the structural part derived from the crosslinking agent is not particularly limited, but is preferably 5 parts by mass or less, more preferably 0.001 to 5 parts by mass, and even more preferably 0.01 to 3 parts by mass, relative to 100 parts by mass of the total amount of the acrylic resin excluding the structural part derived from the crosslinking agent.

[0125] The pressure-sensitive adhesive layer is preferably a non-colored pressure-sensitive adhesive layer. The non-colored pressure-sensitive adhesive layer is a layer different from the colored layer and is not intended to prevent light reflection by metal wiring or the like. The non-colored pressure-sensitive adhesive layer may be a colorless layer or may be slightly colored. Furthermore, the non-colored pressure-sensitive adhesive layer may be, for example, a diffusion functional layer intended to exhibit a light-diffusing function, or may be a non-diffusion functional layer intended not to exhibit a light-diffusing function. The non-colored pressure-sensitive adhesive layer may be transparent or non-transparent.

[0126] The content of the colorant in the non-colored adhesive layer is preferably less than 0.2% by mass, more preferably less than 0.1% by mass, and even more preferably less than 0.05% by mass, relative to the total amount (100% by mass) of the non-colored adhesive layer, and may be less than 0.01% by mass or less than 0.005% by mass.

[0127] The total light transmittance of the non-colored pressure-sensitive adhesive layer is not particularly limited, but from the viewpoint of ensuring brightness, it is preferably 40% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. The upper limit of the total light transmittance of the non-colored pressure-sensitive adhesive layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

[0128] The total light transmittance of the non-colored pressure-sensitive adhesive layer is a value for a single layer, and can be measured by the method specified in JIS K7136 and JIS K7361-1, and can be controlled by the type and thickness of the non-colored pressure-sensitive adhesive layer.

[0129] The diffusion functional layer is a layer intended to diffuse light. When the pressure-sensitive adhesive layer is the diffusion functional layer, light emitted from the optical semiconductor element is diffused in the diffusion functional layer, and for example, light emitted from the side surface of the optical semiconductor element is emitted toward the front of the image display device, thereby improving the front brightness of the image display device. The diffusion functional layer is not limited, but preferably contains light-diffusing fine particles. That is, the diffusion functional layer preferably contains light-diffusing fine particles dispersed in the pressure-sensitive adhesive layer. Only one type of light-diffusing fine particles may be used, or two or more types may be used.

[0130] The light-diffusing fine particles have an appropriate refractive index difference from the resin constituting the diffusion functional layer, and impart diffusion properties to the diffusion functional layer. Examples of the light-diffusing fine particles include inorganic fine particles and polymer fine particles. Examples of materials for the inorganic fine particles include silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and metal oxides. Examples of materials for the polymer fine particles include silicone resin, acrylic resin (including polymethacrylate resin such as polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, and epoxy resin.

[0131] The polymeric fine particles are preferably fine particles made of silicone resin. The inorganic fine particles are preferably fine particles made of metal oxide. The metal oxide is preferably titanium oxide or barium titanate, more preferably titanium oxide. This structure provides the diffusion layer with superior light diffusion properties and reduces brightness unevenness.

[0132] The shape of the light-diffusing fine particles is not particularly limited, and may be, for example, spherical, flat, or irregular.

[0133] The average particle diameter of the light-diffusing fine particles is preferably 0.1 μm or more, more preferably 0.15 μm or more, even more preferably 0.2 μm or more, and particularly preferably 0.25 μm or more, from the viewpoint of imparting appropriate light diffusion performance. Furthermore, the average particle diameter of the light-diffusing fine particles is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less, from the viewpoint of preventing the haze value from becoming too high and displaying high-resolution images. The average particle diameter can be measured, for example, using a Coulter counter.

[0134] The refractive index of the light-diffusing fine particles is preferably 1.2 to 5, more preferably 1.25 to 4.5, even more preferably 1.3 to 4, and particularly preferably 1.35 to 3.

[0135] The absolute value of the refractive index difference between the light-diffusing fine particles and the resin constituting the diffusion functional layer (the resin layer in the diffusion functional layer excluding the light-diffusing fine particles) is preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.03 or more, and may be 0.04 or more, or 0.05 or more, from the viewpoint of more efficiently reducing brightness unevenness in the image display device. Furthermore, the absolute value of the refractive index difference between the light-diffusing fine particles and the resin is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image.

[0136] From the viewpoint of imparting appropriate light diffusion performance to the sheet for encapsulating optical semiconductor elements, the content of the light-diffusing fine particles in the diffusion functional layer is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.15 parts by mass or more, relative to 100 parts by mass of the resin constituting the diffusion functional layer. Moreover, from the viewpoint of preventing the haze value from becoming too high and displaying a high-resolution image, the content of the light-diffusing fine particles is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, relative to 100 parts by mass of the resin constituting the diffusion functional layer.

[0137] The haze value (50 μm thick) of the diffusion functional layer is not particularly limited, but from the viewpoint of efficiently reducing brightness unevenness, it is preferably 30% or more, more preferably 40% or more, even more preferably 50% or more, and particularly preferably 60% or more. It may be 70% or more, 80% or more, 90% or more, 95% or more, or 97% or more, and a value around 99.9% is preferable because it has a better effect of improving brightness unevenness. The upper limit of the haze value of the diffusion functional layer is not particularly limited, and may be 100%. The haze value may be a value before or after curing, but is preferably a value after curing.

[0138] The total light transmittance of the diffusion functional layer is not particularly limited, but from the viewpoint of ensuring brightness, it is preferably 40% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. The upper limit of the total light transmittance of the diffusion functional layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

[0139] The haze value and total light transmittance of the above-mentioned diffusion functional layer are values ​​for a single layer and can be measured by the methods specified in JIS K7136 and JIS K7361-1. They can be controlled by the type and thickness of the diffusion functional layer, the type and amount of light-diffusing microparticles, etc.

[0140] The haze value (50 μm thick) of the non-diffusion functional layer is not particularly limited, but from the viewpoint of achieving excellent brightness, it is preferably less than 30%, more preferably 10% or less, even more preferably 5% or less, particularly preferably 1% or less, and may be 0.5% or less. The lower limit of the haze value of the non-diffusion functional layer is not particularly limited.

[0141] The total light transmittance of the non-diffusion functional layer is not particularly limited, but from the viewpoint of ensuring brightness, it is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. Furthermore, the upper limit of the total light transmittance of the non-diffusion functional layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

[0142] The haze value and total light transmittance of the non-diffusion functional layer are values ​​for a single layer, and can be measured by the methods specified in JIS K7136 and JIS K7361-1. They can be controlled by the type and thickness of the non-diffusion functional layer.

[0143] In order to improve the brightness of the image display device, the content of the colorant and / or light-diffusing microparticles in the non-diffusion functional layer is preferably less than 0.01 parts by mass, and more preferably less than 0.005 parts by mass, per 100 parts by mass of the resin constituting the non-diffusion functional layer.

[0144] The light transmittance at a wavelength of 600 nm of the non-colored pressure-sensitive adhesive layer after curing (thickness: 50 μm) is not particularly limited, but from the viewpoint of further improving the brightness of the optical semiconductor device, it is preferably more than 80%, more preferably 85% or more, and even more preferably 90% or more. The light transmittance is 100% or less.

[0145] The gel fraction (proportion of insoluble components) of the pressure-sensitive adhesive layer is preferably 50% or more, more preferably 60% or more. The gel fraction is preferably 98% or less, more preferably 95% or less. When the gel fraction is 50% or more, the fluidity during encapsulation is not too low, allowing for better filling between optical semiconductor elements. When the gel fraction is 98% or less, appropriate flexibility is obtained, resulting in better encapsulation of optical semiconductor elements. The gel fraction can be controlled, for example, by the monomer composition and weight-average molecular weight of the resin constituting the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer, the amount (addition amount) of polyfunctional monomer and crosslinking agent used, and the type and content of other additives.

[0146] The thickness of the pressure-sensitive adhesive layer is preferably 30 to 100 μm, more preferably 35 to 90 μm, and even more preferably 40 to 80 μm. When the thickness is 30 μm or more, the filling property between the optical semiconductor elements is superior. When the thickness is 100 μm or less, the light extraction efficiency is superior, and the brightness of the semiconductor device is superior. The thickness of the pressure-sensitive adhesive layer is the thickness of the pressure-sensitive adhesive layer located on the opposite side of the curable resin layer (X) from the optical semiconductor element when encapsulated, and when multiple continuous pressure-sensitive adhesive layers are provided, it is the total thickness of the layers.

[0147] The thickness of the pressure-sensitive adhesive layer is preferably 30% or more of the distance from the surface of the substrate to the apex of the optical semiconductor element, more preferably 35% or more, and even more preferably 40% or more. A thickness of 30% or more provides better filling between the optical semiconductor elements. The thickness of the pressure-sensitive adhesive layer is the thickness of the pressure-sensitive adhesive layer located on the opposite side of the curable resin layer (X) from the optical semiconductor element during encapsulation, and is the total thickness when multiple continuous pressure-sensitive adhesive layers are provided.

[0148] In the encapsulating resin layer, the curable resin layer (X) is preferably located closer to the optical semiconductor element than the pressure-sensitive adhesive layer, and it is more preferable that no pressure-sensitive adhesive layer is provided on the optical semiconductor element side of the curable resin layer (X). Such a configuration allows for more sufficient filling of the space between the optical semiconductor element and the substrate. Furthermore, the encapsulating resin layer may include a curable resin layer (another curable resin layer) other than the curable resin layer (X) on the optical semiconductor element side of the curable resin layer (X), between the curable resin layer (X) and the pressure-sensitive adhesive layer, or on the opposite side of the pressure-sensitive adhesive layer from the curable resin layer (X).

[0149] Examples of the laminate structure of the encapsulating resin layer include [curable resin layer (X) / adhesive layer (diffusion functional layer)], [curable resin layer (X) / adhesive layer (non-diffusion functional layer)], and [curable resin layer (X) / adhesive layer (diffusion functional layer) / adhesive layer (non-diffusion functional layer)] (all in order from the optical semiconductor element side). Furthermore, in the laminate structure, a curable resin layer may be provided on the optical semiconductor element side of the curable resin layer (X), between the curable resin layer (X) and the adhesive layer, between the adhesive layers, and on the side of the adhesive layer opposite to the optical semiconductor element.

[0150] (Base material part) In the optical semiconductor element encapsulation sheet of the present invention, the encapsulating resin layer may be provided on at least one surface of a substrate. That is, the semiconductor element encapsulation sheet may include a substrate and the encapsulating resin layer provided on at least one surface of the substrate. When the optical semiconductor element encapsulation sheet of the present invention includes the substrate, the side of the encapsulating resin layer opposite to the side that contacts the optical semiconductor element is the side that contacts the substrate. In this case, the pressure-sensitive adhesive layer is located on the substrate side relative to the thermosetting resin layer (X). When the substrate is provided on the side of the encapsulating resin layer opposite to the optical semiconductor element side in the optical semiconductor element encapsulation sheet, the surface of the encapsulating resin layer can be made flat, thereby reducing the occurrence of diffuse reflection of light and improving the appearance of the optical semiconductor device both when the light is off and when the light is on. In addition, by forming an antiglare layer or an antireflection layer described below on the substrate, antiglare properties and antireflection properties can be imparted to the optical semiconductor device. Furthermore, the substrate serves as a support for the encapsulating resin layer in the optical semiconductor element encapsulation sheet, and the provision of the substrate portion makes the optical semiconductor element encapsulation sheet easy to handle.

[0151] The substrate portion may be a single layer, or may be multiple layers having the same or different compositions, thicknesses, etc. When the substrate portion is multiple layers, each layer may be bonded to another layer such as a pressure-sensitive adhesive layer. Note that the substrate layer used in the substrate portion is the part that is attached to the adherend together with the encapsulating resin layer, and the "substrate portion" does not include a release liner that is peeled off when the optical semiconductor element encapsulation sheet is used (attached) or a surface protection film that merely protects the surface of the substrate portion.

[0152] Examples of the substrate layer constituting the substrate part include glass and plastic substrates (particularly, plastic films). Examples of resins constituting the plastic substrate include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ionomer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester (random, alternating) copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-propylene copolymer, cyclic olefin polymer, ethylene-butene copolymer, ethylene-hexene copolymer, etc. Examples of suitable resins include polyolefin resins, polyurethanes, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT), polycarbonates, polyimide resins, polyether ether ketones, polyetherimides, polyamides such as aramids and wholly aromatic polyamides, polyphenyl sulfides, fluororesins, polyvinyl chloride, polyvinylidene chloride, cellulose resins such as triacetyl cellulose (TAC), silicone resins, acrylic resins such as polymethyl methacrylate (PMMA), polysulfones, polyarylates, and polyvinyl acetates. The above resins may be used singly or in combination. The substrate layer may be any of various optical films, such as antireflection (AR) films, polarizing plates, and retardation plates.

[0153] The thickness of the plastic film is preferably 20 to 300 μm, more preferably 40 to 250 μm. When the thickness is 20 μm or more, the supportability and handleability of the optical semiconductor element encapsulation sheet are further improved. When the thickness is 300 μm or less, the optical semiconductor element encapsulation sheet can be made thinner.

[0154] The surface of the substrate part on the side where the encapsulating resin layer is provided may be subjected to surface treatments such as physical treatments such as corona discharge treatment, plasma treatment, sand matting treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, and ionizing active energy ray treatment; chemical treatments such as chromic acid treatment; and adhesion-enhancing treatment using a coating agent (primer), for the purpose of improving adhesion and retention with the encapsulating resin layer. The surface treatment for improving adhesion is preferably applied to the entire surface of the substrate part on the side where the encapsulating resin layer is provided.

[0155] The thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of excellent support function and surface scratch resistance, and is preferably 300 μm or less, more preferably 250 μm or less, from the viewpoint of excellent transparency.

[0156] <Optical semiconductor element encapsulation sheet> The optical semiconductor element encapsulation sheet may include a layer having antiglare and / or antireflection properties. Such a configuration can suppress gloss and light reflection when encapsulating an optical semiconductor element, improving the appearance. An example of the antiglare layer is an antiglare-treated layer. An example of the antireflection layer is an antireflection-treated layer. The antiglare treatment and antireflection treatment can be performed by known or conventional methods. The antiglare layer and the antireflection layer may be the same layer or different layers. The optical semiconductor element encapsulation sheet may have only one layer or two or more layers. The antiglare and / or antireflection layer is preferably provided on the surface (preferably the front surface) of the optical semiconductor element encapsulation sheet opposite the side that contacts the optical semiconductor element with respect to the encapsulating resin layer.

[0157] The haze value of the optical semiconductor element encapsulation sheet is not particularly limited, but from the viewpoint of achieving a superior effect of suppressing brightness unevenness and designability, it is preferably 0.5% or more, more preferably 1% or more, and even more preferably 3% or more. The upper limit of the haze value is not particularly limited, and may be 100%, 80%, 60%, or 40%. The haze value may be a value before or after curing, but is preferably a value after curing.

[0158] The total light transmittance of the sheet for encapsulating an optical semiconductor element is not particularly limited, but is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less, from the viewpoint of further improving the anti-reflection function of metal wiring etc. and contrast. Moreover, the total light transmittance is preferably 0.5% or more, from the viewpoint of ensuring brightness.

[0159] The haze value and total light transmittance can be measured by the methods specified in JIS K7136 and JIS K7361-1, respectively, and can be controlled by the stacking order, type, thickness, etc. of the layers constituting the encapsulating resin layer and the base material portion.

[0160] In the sheet for encapsulating an optical semiconductor element, when the optical semiconductor element is encapsulated, the distance from the optical semiconductor element to the curable resin layer (X) is preferably 0 to 20 μm, more preferably 0 to 10 μm. When the distance is within the above range, the antireflection properties and brightness of the image display device are superior.

[0161] The thickness of the optical semiconductor element encapsulation sheet is preferably 5 to 600 μm, more preferably 10 to 550 μm, even more preferably 30 to 500 μm, still more preferably 40 to 450 μm, and particularly preferably 50 to 400 μm, from the viewpoints of improving the anti-reflection function and contrast of metal wiring and the like while more efficiently reducing color shift. Note that the thickness does not include the thickness of the release liner.

[0162] The thickness of the encapsulating resin layer is, for example, 5 to 500 μm, preferably 10 to 400 μm, and more preferably 100 to 300 μm. When the thickness is 5 μm or more, the encapsulation of the optical semiconductor element is improved. When the thickness is 500 μm or less, the thickness of the optical semiconductor device is thinner.

[0163] [Release liner] The encapsulating resin layer may be formed on a release-treated surface of a release liner. When the encapsulating resin layer is formed on the release liner, the side of the encapsulating resin layer that is on the side of the pressure-sensitive adhesive layer that contacts the release liner is the side that contacts the release liner. When the substrate portion is not present, both sides of the encapsulating resin layer may contact the release liner. The release liner is used as a protective material for the optical semiconductor element encapsulation sheet and is peeled off when encapsulating the optical semiconductor element. Note that the release liner is not necessarily provided.

[0164] The release liner is an element for covering and protecting the surface of the optical semiconductor element encapsulation sheet, and is peeled off from the sheet when the optical semiconductor element encapsulation sheet is attached to a substrate on which an optical semiconductor element is arranged.

[0165] Examples of the release liner include polyethylene terephthalate (PET) film, polyethylene film, polypropylene film, plastic film and paper whose surface is coated with a release agent such as a fluorine-based release agent or a long-chain alkyl acrylate-based release agent.

[0166] The thickness of the release liner is, for example, 10 to 200 μm, preferably 15 to 150 μm, and more preferably 20 to 100 μm. When the thickness is 10 μm or more, the release liner is less likely to break due to cuts during processing. When the thickness is 200 μm or less, the release liner is more easily peeled from the optical semiconductor element encapsulation sheet during use.

[0167] Fig. 1 is a cross-sectional view showing one embodiment of the optical semiconductor element encapsulation sheet of the present invention. As shown in Fig. 1, the optical semiconductor element encapsulation sheet 1 can be used to encapsulate one or more optical semiconductor elements arranged on a substrate, and includes a substrate part 4 and an encapsulating resin layer 2 formed on the substrate part 4. The substrate part 4 is composed of a substrate film 41 and a functional layer 42 which is a surface treatment layer, but may also be composed of the substrate film 41 without the functional layer 42.

[0168] 1, the encapsulating resin layer 2 is formed from a laminate of a curable resin layer (X) 21, which is a colored layer, and a pressure-sensitive adhesive layer 22. The pressure-sensitive adhesive layer 22 is directly laminated on the curable resin layer (X) 21. A release liner 3 is attached to the curable resin layer (X) 21, and a substrate part 4 is attached to the pressure-sensitive adhesive layer 22.

[0169] In FIG. 1 , the functional layer 42 is a layer not included in the encapsulating resin layer, and can be a layer that can impart various functions for encapsulating the optical semiconductor element. Examples of the functional layer include a layer including a surface treatment layer. Such a configuration results in excellent light diffusion properties and excellent light extraction efficiency for encapsulating an optical semiconductor element on which the functional layer including the surface treatment layer is laminated. Examples of the surface treatment layer include an antiglare treatment layer (anti-glare treatment layer), an anti-reflection treatment layer, and a hard coat treatment layer. The functional layer may be laminated on the encapsulating resin layer in the optical semiconductor element encapsulation sheet, or on the substrate if the substrate is provided. However, the functional layer is preferably laminated on the substrate, and is preferably laminated on the side of the substrate opposite to the side on which the encapsulating resin layer is provided.

[0170] [Method of manufacturing the sheet for encapsulating optical semiconductor elements] An embodiment of a method for producing the optical semiconductor element encapsulation sheet will be described. For example, the optical semiconductor element encapsulation sheet 1 shown in FIG. 1 is prepared by separately sandwiching a curable resin layer (X) 21 and a pressure-sensitive adhesive layer 22 between the release-treated surfaces of two release liners. One of the release liners bonded to the curable resin layer (X) 21 is release liner 3. Next, one of the release liners bonded to the pressure-sensitive adhesive layer 22 is peeled off to expose the surface of the pressure-sensitive adhesive layer 22, and the exposed surface is bonded to the substrate 4. Thereafter, one of the release liners bonded to the curable resin layer (X) 21 (the release liner other than release liner 3) is peeled off, and the release liner on the surface of the pressure-sensitive adhesive layer 22 is peeled off, and the exposed surface of the curable resin layer (X) 21 is bonded to the exposed surface of the pressure-sensitive adhesive layer 22. The lamination of the various layers can be performed using a known roller or laminator. In this manner, the optical semiconductor element encapsulation sheet 1 shown in FIG. 1 can be produced, in which the pressure-sensitive adhesive layer 22, the curable resin layer (X) 21, and the release liner 3 are laminated in this order on the substrate 4.

[0171] [Optical semiconductor device] The optical semiconductor device, such as an image display device, can be manufactured using the optical semiconductor element encapsulation sheet. The optical semiconductor device manufactured using the optical semiconductor element encapsulation sheet includes a substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet or a cured product of the sheet that encapsulates the optical semiconductor element. The cured product is a cured product obtained by thermally curing the curable resin layer (X) 21 (or further the pressure-sensitive adhesive layer 22) included in the optical semiconductor element encapsulation sheet, and specifically includes a cured encapsulating layer obtained by thermally curing the curable resin layer (X) 21.

[0172] Examples of the optical semiconductor element include light emitting diodes (LEDs) such as blue light emitting diodes, green light emitting diodes, red light emitting diodes, and ultraviolet light emitting diodes.

[0173] In the optical semiconductor device, the optical semiconductor element encapsulation sheet has excellent conformability to irregularities when the optical semiconductor elements are convex portions and the gaps between the multiple optical semiconductor elements are concave portions, and has excellent conformability and embeddability for the optical semiconductor elements, so it is preferable that the sheet encapsulates multiple optical semiconductor elements collectively.

[0174] FIG. 2 shows one embodiment of an optical semiconductor device using the optical semiconductor element encapsulation sheet 1 shown in FIG. 1 . The optical semiconductor device 10 shown in FIG. 2 includes a substrate 5, multiple optical semiconductor elements 6 arranged on one surface of the substrate 5, and a cured product of the optical semiconductor element encapsulation sheet 1. The cured product of the optical semiconductor element encapsulation sheet is formed by peeling the release liner 3 from the optical semiconductor element encapsulation sheet 1 and thermally curing the curable resin layer (X) 21 to form a cured encapsulating layer 7. For example, the cured encapsulating layer 7 comprises a cured resin layer 71 formed by thermally curing the curable resin layer (X) 21 and an adhesive layer 22. The multiple optical semiconductor elements 6 are encapsulated together in the cured encapsulating layer 7. The cured encapsulating layer 7 adheres closely to the optical semiconductor elements 6 and the substrate 5, conforming to the uneven shape formed by the multiple optical semiconductor elements 6, thereby embedding the optical semiconductor elements 6. The interface of the cured encapsulating layer 7 on the optical semiconductor element 6 side has an uneven shape conforming to the uneven shape, while the other interface is flat.

[0175] 2, the optical semiconductor element 6 is completely embedded and sealed within the cured resin layer 71 and the adhesive layer 22, and is sealed by the cured resin layer 71 and the adhesive layer 22. That is, the optical semiconductor element 6 is sealed by the cured sealing layer 7, which is a laminate of the cured resin layer 71 and the adhesive layer 22. The cured resin layer 71 fills the space between the optical semiconductor element 6 and the substrate 5, and the spaces between the multiple optical semiconductor elements 6 are filled with the cured resin layer 71 and the adhesive layer 22.

[0176] As described above, the optical semiconductor device encapsulates the optical semiconductor element with a cured encapsulating layer. The curable resin layer (X) has sufficient flexibility before curing, providing excellent conformability and fully embedding the optical semiconductor element. For example, upon heating, the curable resin layer (X) acts as an underfill material, flowing at the encapsulation temperature to fill the gap between the optical semiconductor element 6 and the substrate 5. It then hardens and fixes the optical semiconductor element after curing. This ensures that the optical semiconductor element adheres closely to the cured encapsulating layer, providing excellent encapsulation of the optical semiconductor element. Furthermore, the curable resin layer (X) located on the side and top surfaces of the optical semiconductor element 6 flows during encapsulation, forming recesses between the optical semiconductor elements, which are then filled with the adhesive layer. This reduces the likelihood of voids forming between the optical semiconductor element and the substrate, and between the optical semiconductor elements, resulting in an excellent appearance for the optical semiconductor device.

[0177] The optical semiconductor device may be a tiled structure of individual optical semiconductor devices, i.e., the optical semiconductor device may be a structure in which a plurality of optical semiconductor devices are arranged in a tiled pattern in a planar direction.

[0178] The image display device preferably includes a self-luminous display device. The self-luminous display device can also be combined with a display panel, if necessary, to form an image display device. In this case, the optical semiconductor elements are LED elements. Examples of the self-luminous display device include LED displays, backlights, and organic electroluminescence (organic EL) display devices. The backlight is preferably a full-surface direct backlight. The backlight includes, as at least a part of its components, a laminate including the substrate and a plurality of optical semiconductor elements arranged on the substrate. For example, in the self-luminous display device, a metal wiring layer is laminated on the substrate for transmitting light emission control signals to each LED element. LED elements emitting red (R), green (G), and blue (B) light are alternately arranged on the substrate via the metal wiring layer. The metal wiring layer is made of a metal such as copper, and adjusts the light emission intensity of each LED element to display each color.

[0179] The optical semiconductor element encapsulation sheet can be used in an optical semiconductor device that is folded when used, for example, an optical semiconductor device having a foldable image display device (flexible display) (particularly, a foldable image display device (foldable display)). Specifically, it can be used in a foldable backlight and a foldable self-luminous display device.

[0180] The sheet for encapsulating optical semiconductor elements has excellent conformability and embeddability for optical semiconductor elements, and can therefore be preferably used when the optical semiconductor device is either a mini LED display device or a micro LED display device.

[0181] [Method of manufacturing optical semiconductor device] The optical semiconductor device can be produced by a production method including, for example, a step of laminating the optical semiconductor element encapsulation sheet to the optical semiconductor element provided on the substrate to encapsulate the optical semiconductor element with the encapsulating resin layer (encapsulation step), and a step of curing the curable resin layer in a laminate obtained through the encapsulation step, the laminate including the substrate, the optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet encapsulating the optical semiconductor element, to obtain the cured product (curing step). The cured product is a cured product obtained by thermally curing the curable resin layer, and specifically includes a cured encapsulating layer obtained by curing the curable resin layer.

[0182] The manufacturing method may further include a step of dicing the laminate that has undergone the curing step to obtain an optical semiconductor device (dicing step). The manufacturing method may also include a tiling step of arranging a plurality of optical semiconductor devices obtained in the dicing step so that they are in contact with each other in a planar direction. The manufacturing method for the optical semiconductor device 10 shown in FIG. 2 will be described below with reference to the manufacturing method for the optical semiconductor device 10 shown in FIG. 2.

[0183] (Sealing process) The method for producing an optical semiconductor device using the optical semiconductor element encapsulation sheet includes an encapsulation step of laminating the optical semiconductor element encapsulation sheet to a substrate on which an optical semiconductor element is arranged and encapsulating the optical semiconductor element with an encapsulating resin layer. Specifically, the encapsulation step first involves peeling the release liner from the optical semiconductor element encapsulation sheet to expose the encapsulating resin layer. Then, the exposed surface of the optical semiconductor element encapsulation sheet is laminated to the substrate surface on which the optical semiconductor elements are arranged of a laminate (such as an optical member) comprising a substrate and optical semiconductor elements (preferably multiple optical semiconductor elements) arranged on the substrate. If the laminate comprises multiple optical semiconductor elements, the encapsulating resin layer is further arranged to fill gaps between the multiple optical semiconductor elements, thereby encapsulating the multiple optical semiconductor elements collectively. Specifically, the release liner 3 is peeled off from the sheet 1 for encapsulating optical semiconductor elements shown in Figure 1, and the exposed curable resin layer (X) 21 is placed opposite the surface of the substrate 5 on which the optical semiconductor element 6 is arranged, and the sheet 1 for encapsulating optical semiconductor elements is attached to the surface of the substrate 5 on which the optical semiconductor element 6 is arranged, and the optical semiconductor element 6 is embedded in the encapsulating resin layer 2 or adhered to it.

[0184] The temperature during the lamination (sealing temperature) is, for example, within a range from room temperature to 150°C, preferably 35 to 120°C, more preferably 40 to 110°C, even more preferably 60 to 105°C, and particularly preferably 70 to 100°C. The lamination may be performed under reduced pressure or pressure. This reduces or pressurizes the sheet for encapsulating an optical semiconductor element, preventing voids from forming between the encapsulating resin layer and the substrate or the optical semiconductor element. In the encapsulation step, the sheet is preferably laminated under reduced pressure and then pressurized. When reduced pressure is applied, the pressure is, for example, 1 to 100 Pa, and the depressurization time is, for example, 5 to 600 seconds. When pressurized, the pressure is, for example, 0.05 to 0.5 MPa, and the pressurization time is, for example, 5 to 600 seconds. This sealing step causes the curable resin layer (X) to flow at the sealing temperature and fill the space between the optical semiconductor element and the substrate.

[0185] (hardening process) In the curing step, a laminate (e.g., a laminate obtained in the encapsulation step) in which the optical semiconductor element encapsulation sheet is bonded to the substrate on which the optical semiconductor element is disposed is heated to cure the curable resin layer and, if necessary, the pressure-sensitive adhesive layer. Specifically, in the curing step, as shown in FIG. 2, the curable resin layer (X) 21 is cured to form a cured encapsulation layer 7, thereby obtaining a cured product of the optical semiconductor element encapsulation sheet 1. When the curable resin layer is thermosetting, the heating temperature during curing is, for example, within a range of 80 to 200°C, and the heating time is, for example, 1 minute to 24 hours.

[0186] (dicing process) In the dicing step, the laminate that has undergone the curing step is diced. Here, in the laminate that is subjected to the dicing step, the cured product of the optical semiconductor element encapsulation sheet and the substrate 5 extend wider in the planar direction than the optical semiconductor device 10 that will ultimately be obtained. In the dicing step, the side edges of the cured product of the optical semiconductor element encapsulation sheet and the substrate are diced and removed. The dicing can be performed by a known or conventional method, such as a method using a dicing blade or laser irradiation. In this manner, for example, the optical semiconductor device 10 shown in FIG. 2 can be manufactured.

[0187] (Tiling process) In the tiling step, the plurality of optical semiconductor devices obtained in the dicing step are tiled so as to be in contact with each other in the planar direction, thereby manufacturing, for example, one large image display device. [Example]

[0188] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0189] Manufacturing Example 1 (Preparation of acrylic prepolymer solution A) A separable flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube was charged with the following monomer components: 67 parts by mass of butyl acrylate (BA), 14 parts by mass of cyclohexyl acrylate (CHA), 19 parts by mass of 4-hydroxybutyl acrylate (4-HBA), 0.09 parts by mass of a photopolymerization initiator (trade name "omnirad 184", manufactured by IGM Resins Italia Srl), and 0.09 parts by mass of a photopolymerization initiator (trade name "omnirad 651", manufactured by IGM Resins Italia Srl). After that, nitrogen gas was introduced and the mixture was purged with nitrogen for about 1 hour while stirring. After that, the atmosphere was purged with nitrogen at 5 mW / cm. 2 The reaction rate was adjusted to 5 to 15%, and an acrylic prepolymer solution A was obtained.

[0190] Manufacturing Example 2 (Preparation of Pressure-Sensitive Adhesive Composition A) To the acrylic prepolymer solution A prepared in Production Example 1 (total amount of prepolymers taken as 100 parts by mass), 9 parts by mass of 2-hydroxyethyl acrylate (HEA), 8 parts by mass of 4-hydroxybutyl acrylate (4HBA), 0.02 parts by mass of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA" manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polyfunctional monomer, 0.35 parts by mass of a silane coupling agent (trade name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxypropyltrimethoxysilane), and 0.3 parts by mass of a photopolymerization initiator (trade name "omnirad 651" manufactured by IGM Resins Italia Srl) were added to obtain a pressure-sensitive adhesive composition A.

[0191] Manufacturing Example 3 (Preparation of adhesive layer A) 38.2 parts by mass of the adhesive composition A prepared in Production Example 2 was mixed with 23 parts by mass of "Tospearl 145" (a silicone resin with a refractive index of 1.42 and an average particle size of 4.5 μm, manufactured by Momentive Performance Materials Japan), 23 parts by mass of benzyl acrylate (BzA), 15.7 parts by mass of butyl acrylate (BA), 0.02 parts by mass of dipentaerythritol hexaacrylate (KAYARAD DPHA, manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polyfunctional monomer, and 0.09 parts by mass of a photopolymerization initiator (Omnirad 651, manufactured by IGM Resins Italia Srl) to obtain an adhesive composition. This pressure-sensitive adhesive composition was applied to the release-treated surface of a release liner (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side treated for release, thickness 38 μm) to form a resin composition layer, and then the release-treated surface of a release liner (trade name "MRF38", manufactured by Mitsubishi Chemical Corporation) was also laminated onto the resin composition layer. Next, the adhesive composition was illuminated with a black light at an integrated light intensity of 2520 mJ / cm. 2 Polymerization was carried out by irradiating with ultraviolet light until the temperature reached a temperature of 100° C., thereby preparing a pressure-sensitive adhesive layer A (thickness: 50 μm).

[0192] Manufacturing Example 4 (Preparation of adhesive layer B) A pressure-sensitive adhesive composition was obtained by mixing 38.2 parts by weight of the pressure-sensitive adhesive composition A prepared in Production Example 2 with 23 parts by weight of "Tospearl 145" (a silicone resin with a refractive index of 1.42 and an average particle size of 4.5 μm, manufactured by Momentive Performance Materials Japan, Inc.), 23 parts by weight of benzyl acrylate (BzA), 15.7 parts by weight of butyl acrylate (BA), and 0.2 parts by weight of dipentaerythritol hexaacrylate (KAYARAD DPHA, manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polyfunctional monomer. This pressure-sensitive adhesive composition was applied to the release-treated surface of a release liner (MRE38, manufactured by Mitsubishi Chemical Corporation; a polyethylene terephthalate film with a release treatment applied to one side, thickness 38 μm) to form a resin composition layer, and then the release-treated surface of a release liner (MRF38, manufactured by Mitsubishi Chemical Corporation) was also laminated to the resin composition layer. Next, a black light was used to measure the cumulative light intensity at 2520 mJ / cm 2 Polymerization was carried out by irradiating with ultraviolet light until the temperature reached a temperature of 100° C., thereby preparing a pressure-sensitive adhesive layer B (thickness: 50 μm).

[0193] Production Example 5 (Preparation of Thermosetting Resin Layer A) A resin composition solution with a solids concentration of 50% by weight was prepared by dissolving 63.9 parts by weight of an acrylic polymer (glycidyl methacrylate (GMA):ethyl acrylate (EA):butyl methacrylate (BMA) = 34% by weight:30% by weight:36% by weight, weight-average molecular weight 60,000), 34.1 parts by weight of an acrylic resin (trade name "UC-3000", a carboxyl group-containing acrylic resin, weight-average molecular weight 10,000, manufactured by Toa Gosei Co., Ltd.), 2.0 parts by weight of a silane coupling agent (trade name "KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.04 parts by weight of "Carbon Black #20" (manufactured by Mitsubishi Chemical Corporation) in methyl ethyl ketone. The resin composition solution was applied to the release-treated surface of a release liner (a release-treated film consisting of a 38 μm-thick polyethylene terephthalate film treated with silicone release agents) and then dried at 130°C for 2 minutes to produce a sheet-like thermosetting resin layer A with a thickness (average thickness) of 110 μm.

[0194] Manufacturing Example 6 (Preparation of Thermosetting Resin Layer B) A resin composition solution having a solids concentration of 50% by mass was prepared by dissolving 63.9 parts by mass of an acrylic polymer (glycidyl methacrylate (GMA):ethyl acrylate (EA):butyl methacrylate (BMA) = 34% by mass:30% by mass:36% by mass, weight-average molecular weight 60,000), 19.1 parts by mass of an acrylic resin (trade name "UC-3000", carboxyl group-containing acrylic resin, weight-average molecular weight 10,000, manufactured by Toa Gosei Co., Ltd.), 15.0 parts by mass of an acrylic resin (trade name "UC-3510", carboxyl group-containing acrylic resin, weight-average molecular weight 2,000, manufactured by Toa Gosei Co., Ltd.), 2.0 parts by mass of a silane coupling agent (trade name "KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.04 parts by mass of "Carbon Black #20" (manufactured by Mitsubishi Chemical Corporation) in methyl ethyl ketone. The above resin composition solution was applied to the release-treated surface of a release liner (a release-treated film made of a silicone release-treated polyethylene terephthalate film with a thickness of 38 μm), and then dried at 130°C for 2 minutes to produce sheet-shaped thermosetting resin layers B with thicknesses (average thicknesses) of 60 μm, 70 μm, 75 μm, and 110 μm.

[0195] Manufacturing Example 7 (Preparation of Thermosetting Resin Layer C) A resin composition solution having a solids concentration of 50% by mass was prepared by dissolving 63.9 parts by mass of an acrylic polymer (glycidyl methacrylate (GMA):ethyl acrylate (EA):butyl methacrylate (BMA) = 34% by mass:30% by mass:36% by mass, weight-average molecular weight 60,000), 34.1 parts by mass of an acrylic resin (trade name "UC-3000", carboxyl group-containing acrylic resin, weight-average molecular weight 10,000, manufactured by Toa Gosei Co., Ltd.), 2.0 parts by mass of a silane coupling agent (trade name "KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd.), and 20.0 parts by mass of "Tospearl 145" (manufactured by Momentive Performance Materials Japan, Inc., silicone resin with a refractive index of 1.42 and an average particle size of 4.5 μm) in methyl ethyl ketone. The above resin composition solution was applied to the release-treated surface of a release liner (a release-treated film made of a polyethylene terephthalate film with a thickness of 38 μm and treated with silicone release agent), and then dried at 130°C for 2 minutes to produce a sheet-shaped thermosetting resin layer C with a thickness (average thickness) of 160 μm.

[0196] Example 1 (Production of optical semiconductor element encapsulation sheet) One of the release liners (product name "MRE38") was peeled off from the adhesive layer A obtained in Production Example 3, and the exposed adhesive surface was bonded to the easy-adhesion treated surface of base film A (product name "T912E75 (UE80)", PET film, manufactured by Mitsubishi Chemical Corporation). Next, the release liner (product name "MRF38") was peeled off from the surface of the adhesive layer A to expose the adhesive surface. The exposed surface of the thermosetting resin layer A obtained in Production Example 5 was then superimposed on the exposed surface of the adhesive layer A, and the two were laminated at room temperature (23°C) with a hand roller to avoid air bubbles, and left for two days in a dark place. In this way, a sheet for encapsulating an optical semiconductor element of Example 1 consisting of [release liner / thermosetting resin layer A (110 μm) / adhesive layer A (50 μm) / substrate film A] was obtained.

[0197] Example 2 (Production of optical semiconductor element encapsulation sheet) An optical semiconductor element encapsulation sheet of Example 2 was produced in the same manner as Example 1, except that the thermosetting resin layer B (thickness 110 μm) obtained in Production Example 6 was used instead of the thermosetting resin layer A.

[0198] Example 3 (Production of optical semiconductor element encapsulation sheet) An optical semiconductor element encapsulation sheet of Example 3 was produced in the same manner as Example 1, except that the thermosetting resin layer B (thickness: 75 μm) obtained in Production Example 6 was used instead of the thermosetting resin layer A.

[0199] Example 4 (Production of optical semiconductor element encapsulation sheet) An optical semiconductor element encapsulation sheet of Example 4 was produced in the same manner as in Example 3, except that the pressure-sensitive adhesive layer B obtained in Production Example 4 was used instead of the pressure-sensitive adhesive layer A.

[0200] Example 5 (Production of optical semiconductor element encapsulation sheet) An optical semiconductor element encapsulation sheet of Example 5 was produced in the same manner as in Example 4, except that the thermosetting resin layer B had a thickness of 60 μm.

[0201] Example 6 (Production of optical semiconductor element encapsulation sheet) An optical semiconductor element encapsulation sheet of Example 6 was produced in the same manner as in Example 4, except that the thermosetting resin layer B had a thickness of 70 μm.

[0202] Comparative Example 1 (Production of optical semiconductor element encapsulation sheet) The exposed surface of the thermosetting resin layer C obtained in Production Example 7 was attached to the easy-adhesion treated surface of the base film A, and the resulting sheet was left for two days in a dark place. In this way, a sheet for encapsulating an optical semiconductor element of Comparative Example 1 consisting of [release liner / thermosetting resin layer C (160 μm) / base film A] was obtained.

[0203] <Evaluation> The sheets for encapsulating optical semiconductor elements produced in Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

[0204] (1) Gel fraction Approximately 0.1 g of the pressure-sensitive adhesive layer was sampled from the sheet for encapsulating optical semiconductor elements, wrapped in a porous tetrafluoroethylene sheet (trade name "NTF1122", manufactured by Nitto Denko Corporation) with an average pore size of 0.2 μm, and then tied with kite string. The weight at this time was measured and this weight was defined as the weight before immersion. The weight before immersion is the total weight (Z) of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer sampled above), the tetrafluoroethylene sheet, and the kite string. The total weight of the tetrafluoroethylene sheet and the kite string was also measured, and this weight was defined as the wrapping weight (Y). Next, the pressure-sensitive adhesive layer was wrapped in a tetrafluoroethylene sheet and tied with kite string (referred to as "sample"), which was placed in a 50 ml container filled with ethyl acetate and allowed to stand for 7 days at 23° C. Thereafter, the sample (after ethyl acetate treatment) was removed from the container, transferred to an aluminum cup, and dried in a dryer at 130° C. for 2 hours to remove the ethyl acetate, after which the sample was weighed and defined as the post-immersion weight (X). The gel fraction was then calculated using the following formula: Gel fraction [% (weight%)] = (XY) / (ZY) × 100

[0205] (2) Viscosity The viscosity of the thermosetting resin layer was measured at the encapsulation temperatures shown in Table 1. Specifically, approximately 0.1 g of the thermosetting resin layer was sampled from the optical semiconductor element encapsulation sheet and placed on a parallel plate (diameter 8 mm) as a measurement plate. A rheometer (product name "RheoStress6000", manufactured by HAAKE) was used to measure the melt viscosity (Pa s) of the sample at the encapsulation temperature by the parallel plate method. In this measurement, the gap between the parallel plates was 0.5 mm, the strain rate was 0.1 / sec, the heating rate was 5°C / min, and the measurement temperature range was 40 to 150°C.

[0206] (3) Appearance The release liner was peeled off from the optical semiconductor element encapsulation sheet, and the exposed surface of the thermosetting resin layer was attached to an adherend (8-inch wafer) that had been convexly processed to the height of the irregularities shown in Table 1. For attachment, an "MSV300" device manufactured by Nitto Seiki Co., Ltd. was used, and differential pressure attachment was performed with the wafer surface temperature set to the encapsulation temperature shown in Table 1. The differential pressure attachment conditions were a vacuum degree of 20 Pa and an attachment pressure of 0.1 MPa. In this way, an optical semiconductor device sample was produced.

[0207] The optical semiconductor device samples were visually observed between the convex portions of the adherend, and were evaluated as "good" if no gaps were found between the convex portions, and as "poor" if gaps were found.

[0208] [Table 1]

[0209] As shown in Table 1, when the viscosity of the thermosetting resin layer at the encapsulation temperature of the optical semiconductor element encapsulation sheet of the Examples was within a specific range, no gaps were generated between the convex portions of the optical semiconductor device sample encapsulated at that encapsulation temperature, and the optical semiconductor device sample had a good appearance. On the other hand, when the viscosity of the thermosetting resin layer at the encapsulation temperature was less than 2 kPa·s, gaps were generated between the convex portions of the optical semiconductor device sample encapsulated at that encapsulation temperature, and the optical semiconductor device sample was evaluated as having poor appearance. Furthermore, when an optical semiconductor element encapsulation sheet without a pressure-sensitive adhesive layer on the side opposite the adherend of the thermosetting resin layer was used (Comparative Example 1), gaps were generated between the convex portions of the optical semiconductor device sample, and the optical semiconductor device sample was evaluated as having poor appearance. Note that the optical semiconductor element encapsulation sheets used in all Examples and Comparative Examples function sufficiently as underfill materials.

[0210] Variations of the invention according to the present disclosure are described below. [Appendix 1] A sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, the sheet includes a sealing resin layer including at least a curable resin layer and a pressure-sensitive adhesive layer; The sheet for encapsulating an optical semiconductor element, wherein the viscosity of the curable resin layer at the encapsulation temperature is 2 to 2000 kPa·s. [Appendix 2] The sheet for encapsulating an optical semiconductor element according to Appendix 1, wherein the curable resin layer is located on the optical semiconductor element side with respect to the pressure-sensitive adhesive layer. [Appendix 3] The sheet for encapsulating an optical semiconductor element according to Appendix 1 or 2, wherein the curable resin layer has thermosetting properties. [Appendix 4] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 3, wherein the curable resin layer contains a black colorant. [Appendix 5] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 4, wherein the pressure-sensitive adhesive layer is a non-colored pressure-sensitive adhesive layer. [Appendix 6] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 5, wherein the pressure-sensitive adhesive layer is a diffusion functional layer. [Appendix 7] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 6, wherein the curable resin layer has a light transmittance of 0 to 80% at a wavelength of 600 nm after curing. [Appendix 8] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 7, wherein, in a state in which an optical semiconductor element is encapsulated, the distance from the optical semiconductor element to the curable resin layer is 0 to 20 μm. [Appendix 9] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 8, wherein the thickness of the pressure-sensitive adhesive layer is 30% or more of the distance from the surface of the substrate to the apex of the optical semiconductor element. [Appendix 10] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 9, wherein the thickness of the curable resin layer is 70 to 150 μm. [Appendix 11] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 10, wherein the pressure-sensitive adhesive layer has a thickness of 30 to 100 μm. [Appendix 12] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 11, comprising a substrate and the encapsulating resin layer laminated on the substrate. [Appendix 13] The sheet for encapsulating an optical semiconductor element according to Appendix 12, wherein the pressure-sensitive adhesive layer is located on the substrate side with respect to the thermosetting resin layer. [Appendix 14] An optical semiconductor device comprising: a substrate; an optical semiconductor element disposed on the substrate; and the sheet for encapsulating an optical semiconductor element or a cured product thereof according to any one of Appendices 1 to 13, which encapsulates the optical semiconductor element. [Explanation of symbols]

[0211] 1. Optical semiconductor element encapsulation sheet 2 Sealing resin layer 21 Curable resin layer (X) 22 adhesive layer 3 Release liner 4 Base material part 41 Base film 42 Functional Layer 5. Substrate 6. Optical semiconductor elements 7 Cured sealing layer 71 Hardened resin layer 10 Optical semiconductor device

Claims

1. A sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, the sheet includes a sealing resin layer including at least a curable resin layer and a pressure-sensitive adhesive layer; The sheet for encapsulating an optical semiconductor element, wherein the viscosity of the curable resin layer at the encapsulation temperature is 2 to 2000 kPa·s.

2. The sheet for encapsulating an optical semiconductor element according to claim 1 , wherein the curable resin layer is located on the optical semiconductor element side with respect to the pressure-sensitive adhesive layer.

3. The sheet for encapsulating an optical semiconductor element according to claim 1 , wherein the curable resin layer has thermosetting properties.

4. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the curable resin layer contains a black colorant.

5. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the pressure-sensitive adhesive layer is a non-colored pressure-sensitive adhesive layer.

6. The sheet for encapsulating an optical semiconductor element according to claim 5 , wherein the pressure-sensitive adhesive layer is a diffusion functional layer.

7. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the curable resin layer has a light transmittance of 0 to 80% at a wavelength of 600 nm after curing.

8. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the distance from the optical semiconductor element to the curable resin layer is 0 to 20 μm when the optical semiconductor element is encapsulated.

9. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the thickness of the pressure-sensitive adhesive layer is 30% or more of the distance from the surface of the substrate to a vertex of the optical semiconductor element.

10. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the curable resin layer has a thickness of 70 to 150 μm.

11. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 30 to 100 μm.

12. The optical semiconductor element encapsulation sheet according to claim 1 , comprising: a substrate; and the encapsulating resin layer laminated on the substrate.

13. The sheet for encapsulating an optical semiconductor element according to claim 12 , wherein the pressure-sensitive adhesive layer is located on the substrate side with respect to the thermosetting resin layer.

14. An optical semiconductor device comprising: a substrate; an optical semiconductor element disposed on the substrate; and the optical semiconductor element encapsulating sheet according to claim 1 or 2, or a cured product thereof, for encapsulating the optical semiconductor element.

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