Sheet for sealing optical semiconductor element and optical semiconductor device

Abstract

To provide a sheet for sealing an optical semiconductor element that excels in light extraction efficiency when sealing the optical semiconductor element.SOLUTION: A sheet 1 for sealing an optical semiconductor element is a sheet for sealing one or more optical semiconductor elements 6 arranged on a substrate 5. The sheet 1 for sealing the optical semiconductor element comprises a sealing resin layer 2 that includes at least a curable resin layer (X) 21. The curable resin layer (X)21 contains a curable resin and white particles, and has a melt viscosity of 20,000 Pas or less at 140°C. The curable resin layer 21 is a layer that comes into contact with the optical semiconductor element 6 when sealing the optical semiconductor element 6.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] Optical semiconductor elements emit more light to the sides than to the front (viewing side), and when conventional resin sheets are used to encapsulate optical semiconductor elements, the amount of light emitted from the sides from the optical semiconductor elements cannot be fully utilized. Therefore, when optical semiconductor elements are encapsulated with resin sheets, there is room for improvement in the extraction efficiency of light emitted by the optical semiconductor elements.

[0007] The present invention has been devised under these circumstances, and an object of the present invention is to provide a sheet for encapsulating an optical semiconductor element that has excellent light extraction efficiency when encapsulating an optical semiconductor element. [Means for solving the problem]

[0008] As a result of intensive research to achieve the above object, the present inventors have found that a specific sheet for encapsulating an optical semiconductor element has excellent light extraction efficiency when encapsulating an optical semiconductor element. The present invention has been completed based on these findings.

[0009] That is, the present invention provides a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, The sheet includes an encapsulating resin layer including at least a curable resin layer, the curable resin layer contains a curable resin and white particles, and has a melt viscosity at 140°C of 20,000 Pa s or less; The curable resin layer is a layer that comes into contact with an optical semiconductor element when the optical semiconductor element is encapsulated, thereby providing a sheet for encapsulating an optical semiconductor element.

[0010] The curable resin layer preferably has thermosetting properties.

[0011] The thickness of the curable resin layer is preferably 5 to 150 μm.

[0012] The content of the white particles in the curable resin layer is preferably 15 to 70% by mass with respect to the total amount of the curable resin layer.

[0013] The optical semiconductor element encapsulation sheet preferably has a total light reflectance of 50% or more at at least one point within a wavelength range of 450 to 800 nm after curing.

[0014] The curable resin layer preferably has a modulus of elasticity E' after curing of 500 to 6000 MPa.

[0015] In the sheet for encapsulating an optical semiconductor element, when the optical semiconductor element is encapsulated, the thickness of the curable resin layer on the optical semiconductor element is preferably 3 μm or less.

[0016] The present disclosure also provides an optical semiconductor device including 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]

[0017] The sheet for encapsulating an optical semiconductor element of the present invention has excellent light extraction efficiency when encapsulating an optical semiconductor element, and therefore, the sheet for encapsulating an optical semiconductor element of the present invention has high brightness when encapsulating an optical semiconductor element. [Brief explanation of the drawings]

[0018] [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

[0019] [Optical semiconductor element encapsulation sheet] The optical semiconductor element encapsulation sheet of the present invention includes at least an encapsulating resin 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 an 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 the optical semiconductor element to be embedded at least a portion of the optical semiconductor element or to be covered with the encapsulating resin layer.

[0020] <Sealing resin layer> The encapsulating resin layer includes at least a curable resin layer containing a curable resin and white particles and having a melt viscosity of 20,000 Pa·s or less at 140°C. In this specification, the curable resin layer may be referred to as a "curable resin layer (X)." The encapsulating resin layer may include layers other than the curable resin layer (X) (such as a curable resin layer other than the curable resin layer (X) or an adhesive layer). Each 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 (X) are included, the multiple layers may be stacked in contact with each other or may be stacked separately.

[0021] The optical semiconductor element encapsulation sheet of the present invention is in the form of a sheet (film) having an encapsulating resin layer including a curable resin layer (X) before encapsulating the optical semiconductor element. Furthermore, the curable resin layer (X) has curability before encapsulating the optical semiconductor element.

[0022] When encapsulating an optical semiconductor element, the curable resin layer (X) is located in the encapsulating resin layer so as to come into contact with the optical semiconductor element. The curable resin layer (X) is preferably located closest to the optical semiconductor element in the encapsulating resin layer. With this configuration, the curable resin layer flows during encapsulation of the optical semiconductor element, filling gaps between adjacent optical semiconductor elements and, if any, between the optical semiconductor element and the substrate.

[0023] (Curable resin layer (X)) As described above, the melt viscosity of the curable resin layer (X) at 140°C is 20,000 Pa·s or less, preferably 18,000 Pa·s or less. Having a melt viscosity of 20,000 Pa·s or less allows the curable resin layer (X) to flow during encapsulation of the optical semiconductor elements, filling gaps between adjacent optical semiconductor elements and, if present, between the optical semiconductor element and the substrate. The melt viscosity at 140°C is, for example, 500 Pa·s or more, and may be 1,000 Pa·s or more. A melt viscosity of 500 Pa·s or more prevents the flow of the curable resin layer (X) from becoming too low, making it difficult for gaps to form between adjacent optical semiconductor elements. The melt viscosity can be controlled, for example, by the monomer composition and weight-average molecular weight of the resin constituting the resin composition for forming the curable resin layer (X), the amount (addition amount) of polyfunctional monomer and crosslinking agent used, and the type and content of other additives.

[0024] Examples of the curable resin layer (X) 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 electron beams, ultraviolet rays, 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.

[0025] Resins constituting the curable resin layer (X) 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.

[0026] 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.

[0027] 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.

[0028] The curable resin layer (X) preferably contains a thermosetting resin, since it is preferable that the curable resin layer (X) has thermosetting properties. As the thermosetting resin, known or commonly used thermosetting resins can be used, for example, resins 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.

[0029] 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.

[0030] 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.

[0031] Examples of the glycidyl group-containing (meth)acrylic acid ester include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.

[0032] 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.

[0033] 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.

[0034] 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 heat curing, and the curable resin layer (X) is cured. Therefore, the curable resin layer (X) has appropriate flexibility after heat curing and is superior in encapsulating optical semiconductor elements.

[0035] 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 (X). When the content is within the above range, the curable resin layer (X) has appropriate flexibility after thermal curing and is more excellent in sealing the optical semiconductor element.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Examples of the (meth)acrylic acid ester having an aromatic hydrocarbon group include (meth)acrylic acid phenyl ester and (meth)acrylic acid benzyl ester.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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 (X) 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 property 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.

[0047] The content of the epoxy group-containing acrylic resin is preferably 5 to 80 mass %, more preferably 10 to 75 mass %, and even more preferably 30 to 70 mass %, relative to the total amount (100 mass %) of resin in the curable resin layer (X). When the content is within the above range, the embeddability of the optical semiconductor element is superior.

[0048] The curable resin layer (X) 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 (X) is heated, thereby further promoting the curing of the curable resin layer (X).

[0049] 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.

[0050] 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.

[0051] When the curable resin layer (X) contains the epoxy group-containing acrylic resin, it is preferable that the curable resin layer (X) 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.

[0052] 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.

[0053] 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.

[0054] The content of the structural unit derived from the carboxyl group-containing acrylic monomer is preferably 1 to 50 mass %, more preferably 3 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 (X) has appropriate flexibility after thermal curing and is more excellent in sealing the optical semiconductor element.

[0055] 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.

[0056] 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.

[0057] In order to properly exhibit basic properties such as adhesion to the optical semiconductor element in the curable resin layer (X), 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.

[0058] 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.

[0059] When the carboxyl group-containing acrylic resin is contained, the content of the carboxyl group-containing acrylic resin is preferably 15% by mass or more (for example, 15 to 100% by mass) relative to the total amount (100% by mass) of resin in the curable resin layer (X), more preferably 20% by mass or more, and even more preferably 25% by mass or more. When the content is 15% by mass or more, the thermosetting property of the curable resin layer (X) is superior. In addition, the scratch resistance of the surface is superior. The content is, for example, 80% by mass, and may be 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0060] The curable resin layer (X) contains white particles. When the curable resin layer (X) contains white particles, the curable resin layer (X) fills spaces between the optical semiconductor elements when the optical semiconductor elements are encapsulated, and reflects light emitted from the side surfaces of the optical semiconductor elements, thereby increasing the light extraction efficiency to the front (viewing side).

[0061] The white particles may be white organic or inorganic particles. Examples of the material for the organic particles include silicone resin, acrylic resin (including polymethacrylate resin such as polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, and epoxy resin. Examples of the inorganic particles include titanium oxide (rutile titanium dioxide, anatase titanium dioxide, and other titanium dioxides), zinc oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate (light calcium carbonate, heavy calcium carbonate, and other), barium carbonate, zinc carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, aluminum silicate, magnesium silicate, calcium silicate, barium sulfate, calcium sulfate, barium stearate, zinc oxide, zinc sulfide, talc, silica, alumina, clay, kaolin, titanium phosphate, mica, gypsum, white carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, and hydrated halloysite. The white particles may be used alone or in combination of two or more types.

[0062] The average particle size of the white particles is preferably 100 to 900 nm, more preferably 150 to 700 nm, and even more preferably 200 to 500 nm. When the average particle size of the white pigment is within the above range, light reflectivity is increased, and light emitted from the side of the optical semiconductor element is reflected, thereby increasing the light extraction efficiency to the front (viewing side). The average particle size can be measured, for example, using a Coulter counter.

[0063] The refractive index of the organic particles is preferably 1.2 to 1.9, more preferably 1.25 to 1.85, even more preferably 1.3 to 1.8, and particularly preferably 1.35 to 1.75.

[0064] The refractive index of the inorganic particles is preferably from 1.5 to 3.0, more preferably from 1.55 to 2.95, even more preferably from 1.6 to 2.9, and particularly preferably from 1.75 to 2.85.

[0065] The absolute value of the refractive index difference between the white particles and the resin constituting the curable resin layer (X) (the resin layer excluding the white particles in the curable resin layer (X)) is preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.2 or more, particularly preferably 0.3 or more, and may be 0.4 or more, or 0.5 or more, from the viewpoint of sufficiently increasing the total light reflectance.

[0066] The content of the white particles in the curable resin layer (X) is preferably 15% by mass or more, more preferably 17% by mass or more, and even more preferably 20% by mass or more, relative to the total amount (100% by mass) of the curable resin layer (X). The content of the white particles is, for example, 70% by mass or less, preferably 65% ​​by mass or less, and more preferably 60% by mass or less. The white particles may be added to the composition as a solution or dispersion in which they are dissolved or dispersed in an appropriate solvent.

[0067] The curable resin layer (X) 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 such 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, and foil-like materials. Each of the above other components may be used alone or in combination of two or more.

[0068] The resin content in the curable resin layer (X) is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, relative to the total amount (100% by mass) of the curable resin layer. The content is preferably 85% by mass or less, more preferably 83% by mass or less, and even more preferably 80% 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.

[0069] The total light reflectance at at least one point within a wavelength range of 450 to 800 nm after curing of the curable resin layer (X) is not particularly limited, but is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more, from the viewpoint of achieving superior light extraction efficiency from the front surface of the optical semiconductor element. The total light reflectance may be 100% or less, or may be 95% or less, or even 90% or less. The total light reflectance within the entire wavelength range of 450 to 800 nm after curing is preferably within the above range. The total light reflectance can be adjusted by adjusting the type of white particles contained in the curable resin layer (X), the average particle size of the white particles, the content of the white particles, and the absolute value of the difference in refractive index between the white particles and the resin constituting the curable resin layer (X).

[0070] The thickness of the curable resin layer (X) (average thickness before encapsulation of the optical semiconductor elements) is preferably 5 to 150 μm, more preferably 8 to 130 μm, and even more preferably 10 to 100 μm. If the thickness is 5 μm or more, a large amount of the curable resin layer (X) is present between the optical semiconductor elements during encapsulation, which allows sufficient reflection of light emitted from the side surfaces of the optical semiconductor elements, resulting in superior front light extraction efficiency. If the thickness is 150 μm or less, the brightness of the light emitted by the optical semiconductor elements will be higher.

[0071] 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. When the thickness is 60% or more, a large amount of the curable resin layer is present between the optical semiconductor elements during encapsulation, allowing sufficient reflection of light emitted from the side surfaces of the optical semiconductor element, resulting in superior front light extraction efficiency. 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. When the thickness is 130% or less, the brightness of the light emitted by the optical semiconductor element is increased.

[0072] The elastic modulus E' of the curable resin layer (X) after curing is not particularly limited, but is preferably 500 to 6000 MPa, more preferably 1000 to 5500 MPa, and even more preferably 1500 to 5000 MPa. When the elastic modulus E' is within the above range, chipping is unlikely to occur in the resin layer when optical semiconductor elements are sealed and brought into close contact with each other and then separated. The elastic modulus E' is the tensile storage modulus at 25°C, measured under conditions of a tensile mode and a frequency of 1 Hz.

[0073] The encapsulating resin layer may include layers other than the curable resin layer (X). Examples of such layers include a colored layer, a non-colored layer, and a diffusion layer. The diffusion layer may be either a colored layer or a non-colored layer. The other layer is preferably a resin layer, and may be, for example, a curable resin layer other than the curable resin layer (X) or an adhesive layer. In this specification, the term "adhesive layer" refers to a layer that adheres two surfaces together in response to external pressure (e.g., minute pressure) based on the cohesive force of the composition's chemical structure, and that can be peeled off as needed.

[0074] The colored layer is a layer containing a colorant, and is intended to prevent light reflection from metal wiring or the like provided on a substrate in an image display device. The colorant contained in the colored layer may be a dye or a pigment, as long as it is soluble or dispersible in the colored layer. Dyes are preferred because they can achieve low haze even with a small amount of addition, do not sediment like pigments, and are easily distributed uniformly. Pigments are also preferred because they provide high color expression even with a small amount of addition. When a pigment is used as a colorant, it is preferable that it has low or no conductivity. The colorants may be used alone or in combination of two or more types.

[0075] 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.

[0076] When the colored 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.

[0077] From the viewpoint of imparting an appropriate anti-reflection capability to the image display device, the content of the colorant in the colored layer is preferably 0.03% by mass or more, more preferably 0.1% by mass or more, relative to the total amount (100% by mass) of the colored layer. The content of the colorant is, for example, 2% by mass or less, preferably 1% by mass or less, and more preferably 0.6% 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.

[0078] The non-colored 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 layer may be a colorless layer or may be slightly colored. The non-colored layer may be transparent or non-transparent. The non-colored layer is preferably a resin layer made of resin.

[0079] The content of the colorant in the non-colored 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 layer, and may be less than 0.01% by mass or less than 0.005% by mass.

[0080] The total light transmittance of the non-colored 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 layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

[0081] The total light transmittance of the non-colored 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 layer.

[0082] The diffusion functional layer is a layer intended to diffuse light. When the encapsulating resin layer has 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 preferably a resin layer made of resin. 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 resin layer. Only one type of light-diffusing fine particles may be used, or two or more types may be used.

[0083] 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.

[0084] 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 configuration provides the diffusion layer with superior light diffusion properties and more suppresses brightness unevenness. The shape of the light-diffusing fine particles is not particularly limited, and may be, for example, spherical, flat, or irregular.

[0085] Examples of the laminate structure of the encapsulating resin layer include [curable resin layer (X)], [curable resin layer (X) / non-colored layer], [curable resin layer (X) / colored layer], [curable resin layer (X) / colored layer (diffusion function layer)], [curable resin layer (X) / colored layer (adhesive layer)], and [curable resin layer (X) / non-colored layer (adhesive layer)] (all in order from the optical semiconductor element side).

[0086] (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 the side that contacts the optical semiconductor element is the side that contacts the substrate. When the substrate is provided on the side of the encapsulating resin layer opposite the optical semiconductor element side of the optical semiconductor element, the surface of the encapsulating resin layer can be made flat, thereby reducing the occurrence of diffused 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 anti-glare layer or anti-reflection layer described below on the substrate, the optical semiconductor device can be imparted with anti-glare properties and anti-reflection properties. In addition, the substrate serves as a support for the encapsulating resin layer in the optical semiconductor element encapsulation sheet, and the presence of the substrate improves the handleability of the optical semiconductor element encapsulation sheet. Note that the substrate is not necessarily provided.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] <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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] In the sheet for encapsulating an optical semiconductor element, when the optical semiconductor element is encapsulated, the thickness of the curable resin layer (X) on the optical semiconductor element (thickness of the curable resin layer (X) on the viewing side of the optical semiconductor element) is preferably 3 μm or less, more preferably 2.5 μm or less, and even more preferably 2 μm or less. When the thickness is 3 μm or less, the brightness of the light emitted by the optical semiconductor element becomes higher. The thickness may be, for example, more than 0 μm, and may be 0.1 μm or more, 0.2 μm or more, or 0.5 μm or more.

[0097] The thickness of the optical semiconductor element encapsulation sheet is preferably 5 to 600 μm, more preferably 8 to 550 μm, and even more preferably 10 to 500 μm, from the viewpoints of improving the anti-reflection function and contrast of metal wiring, etc., while more efficiently reducing color shift. Note that the thickness does not include the thickness of the release liner.

[0098] The thickness of the encapsulating resin layer is, for example, 5 to 500 μm, preferably 8 to 400 μm, and more preferably 10 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.

[0099] [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 curable resin layer (X) of the encapsulating resin layer is the side that comes into contact with the release liner. When the substrate portion is not present, both sides of the encapsulating resin layer may come into contact with 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 1, the encapsulating resin layer 2 is formed of a laminate of a curable resin layer (X) 21 and a colored layer 22. The colored 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 colored layer 22.

[0104] In FIG. 1 , the functional layer 42 is a layer not included in the encapsulating resin layer, and can impart various functions to the optical semiconductor element encapsulation sheet. Examples of the functional layer include a layer including a surface treatment layer. Such a configuration allows the optical semiconductor element encapsulation sheet having the functional layer including the surface treatment layer laminated thereon to have excellent light diffusion properties and light extraction efficiency. Examples of the surface treatment layer include an antiglare treatment layer (antiglare treatment layer), an antireflection treatment layer, and a hard coat treatment layer. The functional layer may be laminated on the encapsulating resin layer of the optical semiconductor element encapsulation sheet, or, if the sheet has a substrate, on the substrate. 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.

[0105] [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 colored 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 colored layer 22 is peeled off to expose the surface of the colored 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 colored layer 22 is peeled off, and the exposed surface of the curable resin layer (X) 21 is bonded to the surface of the colored layer 22. The lamination of the various layers can be performed using a known roller or laminator. In this manner, the optical semiconductor element encapsulating sheet 1 shown in FIG. 1 can be produced, in which the colored layer 22, the curable resin layer (X) 21, and the release liner 3 are laminated in this order on the substrate part 4.

[0106] [Optical semiconductor device] The optical semiconductor device can be manufactured using the optical semiconductor element encapsulation sheet, such as an image display device. 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 of the curable resin layer (X) 21 provided in the optical semiconductor element encapsulation sheet, and specifically includes a cured encapsulating layer formed by thermally curing the curable resin layer (X) 21.

[0107] 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.

[0108] 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.

[0109] 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 a colored layer 22. The multiple optical semiconductor elements 6 are encapsulated collectively 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.

[0110] 2, the optical semiconductor elements 6 are completely embedded and sealed in the cured resin layer 71, and are sealed by the cured resin layer 71 and the colored layer 22. That is, the optical semiconductor elements 6 are sealed by the cured sealing layer 7, which is a laminate of the cured resin layer 71 and the colored layer 22. The cured resin layer 71 fills the spaces between the multiple optical semiconductor elements 6.

[0111] As described above, the optical semiconductor device encapsulates the optical semiconductor element with a cured encapsulation layer. The curable resin layer (X) has sufficient flexibility before curing, providing excellent conformability to irregularities, thoroughly embedding the optical semiconductor element, flowing at the encapsulation temperature to fill the spaces between the optical semiconductor element 6, and then curing, thereby fixing the optical semiconductor element. Therefore, the optical semiconductor element is in close contact with the cured encapsulation layer, providing excellent encapsulation of the optical semiconductor element. Furthermore, by positioning the curable resin layer (X) on the side surface of the optical semiconductor element 6, light emitted from the side surface of the optical semiconductor element 6 is reflected, increasing the amount of light toward the front (viewing side), resulting in excellent light extraction efficiency.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] [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 (X) in a laminate obtained through the encapsulation step, the laminate comprising 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 curing the curable resin layer (X), and specifically, comprises a cured encapsulating layer obtained by curing the curable resin layer (X).

[0117] 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.

[0118] (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.

[0119] 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, thereby preventing voids from forming between the encapsulating resin layer and the substrate or 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, filling the spaces between the optical semiconductor element and, if necessary, filling the spaces between the optical semiconductor element and the substrate.

[0120] (hardening process) In the curing step, a laminate (for example, a laminate obtained in the encapsulation step) in which the optical semiconductor element encapsulation sheet is attached to the substrate on which the optical semiconductor element is disposed is heated to cure the curable resin layer (X). Specifically, in the curing step, as shown in FIG. 2, the curable resin layer (X) 21 is cured to form a cured resin layer 71 and a cured encapsulation layer 7, thereby obtaining a cured product of the optical semiconductor element encapsulation sheet 1. When the curable resin layer (X) is thermosetting, the heating temperature during the curing step is, for example, within a range of 80 to 200°C, and the heating time is, for example, 1 minute to 24 hours.

[0121] (Cured resin layer removal process) When the optical semiconductor element encapsulation sheet is composed only of the curable resin layer (X), a cured resin layer, which is the cured product of the curable resin layer (X), is exposed on the surface of the substrate after the curing step. In this case, the manufacturing method may include a step of removing the cured resin layer on the surface (cured resin layer removal step). For example, if a cured resin layer is present on the optical semiconductor element, the cured resin layer can be removed by plasma etching to reduce the thickness of the cured resin layer on the optical semiconductor element or to remove it, thereby obtaining an optical semiconductor device with even better light extraction efficiency. Furthermore, after the cured resin layer removal step, another optical semiconductor element encapsulation sheet may be superimposed on the cured resin layer to encapsulate the optical semiconductor element. In this way, an optical semiconductor device can be manufactured in which no cured resin layer remains on the optical semiconductor element or in which the cured resin layer on the optical semiconductor element is extremely thin.

[0122] (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.

[0123] (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]

[0124] 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.

[0125] Example 1 A resin composition with a solids concentration of 50% by mass was prepared by dissolving 50 parts by mass of acrylic polymer A (glycidyl methacrylate (GMA):ethyl acrylate (EA):butyl methacrylate (BMA) = 34% by mass:30% by mass:36% by mass, weight-average molecular weight 60,000), 29 parts by mass of acrylic resin (product name "UC-3000", carboxy group-containing acrylic resin, manufactured by Toa Gosei Co., Ltd.), 1 part by mass of silane coupling agent (product name "KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd.), and 100 parts by mass of titanium oxide (product name "CR-95", refractive index: approximately 2.7, manufactured by Ishihara Sangyo Kaisha, Ltd.) as white inorganic particles in methyl ethyl ketone. The above resin composition 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 a sheet for encapsulating semiconductor elements made of a thermosetting resin layer with a thickness (average thickness) of 10 μm.

[0126] Examples 2 to 4, Comparative Example 1 The sheets for encapsulating optical semiconductor elements of each example were produced in the same manner as in Example 1, except that the blending amounts of various raw materials were changed as shown in Table 1. The units of the values ​​shown in Table 1 are "parts by mass."

[0127] [Table 1]

[0128] <Evaluation> The sheets for encapsulating optical semiconductor elements produced in the examples and comparative examples were evaluated as follows. The results are shown in Table 2.

[0129] (1) Total light reflectance after curing The thermosetting resin layer obtained in each example was heated at 150°C for 1 hour to cure and prepare a measurement sample. Then, using a UV-Vis-NIR spectrophotometer (product name "V-670DS", manufactured by JASCO Corporation) and an integrating sphere unit, the total light reflectance spectrum in the wavelength range of 400 to 900 nm was measured, and the total light reflectance at a wavelength of 800 nm was read from the obtained spectrum. Note that the total light reflectance values ​​in the wavelength range of 450 to 800 nm were all equal to or greater than the total light reflectance value at 800 nm.

[0130] (2) Melt viscosity The thermosetting resin layers obtained in each example were laminated to prepare a laminate of thermosetting resin layers approximately 300 μm thick, which was then punched out into a cylindrical shape with a diameter of 8 mm to prepare a measurement sample. The measurement sample was measured in shear mode using a rheometer (product name "HAAKEMARS III Rheometer", manufactured by ThermoScientific) at a frequency of 1 Hz in the range of 80 to 160°C at a heating rate of 5°C / min, and the melt viscosity at 140°C was calculated.

[0131] (3) Room temperature tensile storage modulus E' after curing The thermosetting resin layers obtained in each example were stacked at 90°C until a thickness of 200 μm was reached, and then cut into 10 mm wide x 40 mm long strips using a utility knife. These were then cured by heating at 150°C for 1 hour to prepare measurement samples. The dynamic storage modulus of the samples was measured using a solid viscoelasticity measuring device (trade name "RSAII" manufactured by Rheometric Scientific) in tension mode at a frequency of 10 Hz and a chuck distance of 22.5 mm over a temperature range of -10 to 250°C at a heating rate of 10°C / min, and the tensile storage modulus E' at 25°C was calculated.

[0132] (4) Front light extraction efficiency The thermosetting resin layer surface of the optical semiconductor element encapsulation sheet obtained in each example was bonded to alkali-free glass at 90°C. After bonding, the sheet was heated at 150°C for 1 hour to cure. After curing, the release liner was peeled off. An LED lamp (product name "LK-3PG", manufactured by EK Japan Co., Ltd.) was connected to a battery box (product name "AP-180", manufactured by EK Japan Co., Ltd.) and the LED lamp was turned on. The LED lamp was tightly attached to the resin layer side of the evaluation sample. The detection unit of an illuminance meter (product name "TESTO-540", manufactured by Testo Co., Ltd.) was placed directly to the side of the LED light source, 5 cm away. The illuminance was then measured and evaluated based on the following evaluation criteria. [Evaluation criteria] ◎:30(lx) or more ○: 20~29(lx) △: 10~19(lx) ×: 9(lx) or less

[0133] (5) Chip The optical semiconductor element encapsulation sheet obtained in each example was superimposed on a pattern wafer with a height of 10 μm, a length of 30 μm, and a width of 15 μm, and encapsulation was performed in a vacuum press at 140°C x 0.3 MPa x 600 seconds, followed by thermal curing at 150°C x 1 hour to prepare an encapsulated sample. The encapsulated sample was diced into 10 mm x 10 mm pieces, and the cut surface of the encapsulated sample was observed to confirm the amount of resin chipping at the wafer edge. The sample was then evaluated based on the following evaluation criteria. [Evaluation criteria] ◎: The amount of resin chipping from the wafer edge to the inside of the resin is less than 10 μm ×: The amount of resin chipping from the wafer edge to the resin interior is 10 μm or more

[0134] (6) Layer thickness on the chip after encapsulation The encapsulated sample obtained in the above chipping evaluation was observed under SEM, and the layer thickness on the convex portion of the pattern wafer was measured from the obtained SEM image, and the average value of three points was taken as the layer thickness on the chip.

[0135] [Table 2]

[0136] As shown in Table 2, the optical semiconductor element encapsulation sheet of the example had a thermosetting resin layer with a melt viscosity of 20,000 Pa s or less at 140°C, which allowed it to fill the gaps between the patterned wafers during encapsulation without creating voids, thereby adequately encapsulating the optical semiconductor elements. Furthermore, the thermosetting resin layer contained white particles, which resulted in high total light reflectance after curing and was evaluated as having excellent front light extraction efficiency.

[0137] 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 an encapsulating resin layer including at least a curable resin layer, the curable resin layer contains a curable resin and white particles, and has a melt viscosity at 140°C of 20,000 Pa s or less; The sheet for encapsulating an optical semiconductor element, wherein the curable resin layer is a layer that comes into contact with an optical semiconductor element when the optical semiconductor element is encapsulated. [Appendix 2] The sheet for encapsulating an optical semiconductor element according to Appendix 1, wherein the curable resin layer has thermosetting properties. [Appendix 3] The sheet for encapsulating an optical semiconductor element according to Appendix 1 or 2, wherein the thickness of the curable resin layer is 5 to 150 μm. [Appendix 4] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 3, wherein the content of the white particles in the curable resin layer is 15 to 70 mass % with respect to the total amount of the curable resin layer. [Appendix 5] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 4, which has a total light reflectance of 50% or more at at least one point within a wavelength range of 450 to 800 nm after curing. [Appendix 6] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 5, wherein the curable resin layer has a modulus of elasticity E' of 500 to 6000 MPa after curing. [Appendix 7] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 6, wherein, in a state where the optical semiconductor element is encapsulated, the thickness of the curable resin layer on the optical semiconductor element is 3 μm or less. [Appendix 8] 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 7, which encapsulates the optical semiconductor element. [Explanation of symbols]

[0138] 1. Optical semiconductor element encapsulation sheet 2 Sealing resin layer 21 Curable resin layer (X) 22 Colored 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 an encapsulating resin layer including at least a curable resin layer, the curable resin layer contains a curable resin and white particles, and has a melt viscosity at 140°C of 20,000 Pa s or less; The sheet for encapsulating an optical semiconductor element, wherein the curable resin layer is a layer that comes into contact with an optical semiconductor element when the optical semiconductor element is encapsulated.

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

3. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the curable resin layer has a thickness of 5 to 150 μm.

4. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein a content ratio of the white particles in the curable resin layer is 15 to 70 mass % with respect to the total amount of the curable resin layer.

5. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the total light reflectance at at least one point within a wavelength range of 450 to 800 nm after curing is 50% or more.

6. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the curable resin layer has a modulus of elasticity E' of 500 to 6000 MPa after curing.

7. 3. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the thickness of the curable resin layer on the optical semiconductor element is 3 μm or less when the optical semiconductor element is encapsulated therein.

8. 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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