Sheets for encapsulating optoelectronic semiconductor devices and optoelectronic semiconductor devices

Abstract

The present invention provides a sheet for encapsulating optical semiconductor elements that can suppress brightness variations and adequately fill the gap between the optical semiconductor element and the substrate. [Solution] The photo-semiconductor element encapsulation sheet 1 is a sheet for encapsulating one or more photo-semiconductor elements 6 arranged on a substrate 5. The photo-semiconductor element encapsulation sheet 1 comprises an encapsulation resin layer 2 which includes at least a thermosetting resin layer 21 containing light-diffusing fine particles. The thermosetting resin layer 21 is a layer that comes into contact with the photo-semiconductor element 6 when the photo-semiconductor element 6 is encapsulated. Preferably, the viscosity of the thermosetting resin layer 21 at the encapsulation temperature is 30,000 Pa·s or less.

Description

Technical Field

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

Background Art

[0002] Self-luminous display devices such as Mini / Micro Light Emitting Diode Displays are known to have a structure in which a plurality of LEDs are arranged on a substrate, and the plurality of LEDs are sealed with a sealing resin. As a method for collectively sealing the plurality of LEDs using the sealing resin, a method is known in which a liquid resin is poured into a region where the plurality of LEDs are arranged to embed the plurality of LEDs, and then the liquid resin is cured by heat or ultraviolet irradiation.

[0003] However, the method of sealing optical semiconductor elements such as LEDs using a liquid resin has a problem of poor handleability, such as sagging occurring when applying the liquid resin and the liquid resin adhering to unintended regions. In contrast, by adopting the form of a sealing sheet provided with a sealing layer for sealing the optical semiconductor element instead of using a liquid resin, the optical semiconductor element can be sealed easily in a simple process in a short time.

[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 is positioned such that the colorless pressure-sensitive adhesive layer is in contact with the optical semiconductor element. It is described that according to the pressure-sensitive adhesive sheet, luminance variation (luminance unevenness) can be suppressed when the sheet is brought into contact with and follows the uneven shape formed by the substrate and the optical semiconductor elements mounted on the substrate.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-169262 [Overview of the project] [Problems that the invention aims to solve]

[0006] From the perspective of further suppressing brightness variations and increasing the efficiency of light extraction from optoelectronic semiconductor devices, it is sometimes necessary to improve the haze of the encapsulating material. To increase the haze of the encapsulating material, it is possible to use a high refractive index material.

[0007] Incidentally, in a flip-chip type semiconductor device in which an optoelectronic element is directly bump-connected to a substrate, for example, a void exists between the bump-connected optoelectronic element and the substrate. However, conventional sealing sheets containing high refractive index materials have not adequately filled such voids when sealing semiconductor devices with these voids.

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

[0009] As a result of diligent research to achieve the above objectives, the inventors of the present invention have found that, with a specific sealing sheet, when an optical semiconductor element is sealed, brightness variations can be suppressed and the gap between the optical semiconductor element and the substrate can be sufficiently filled. The present invention was completed based on these findings.

[0010] In other words, the present invention is a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, The above sheet comprises a sealing resin layer which includes at least a thermosetting resin layer containing light-diffusing fine particles, The above thermosetting resin layer is a layer that comes into contact with the optical semiconductor element when the optical semiconductor element is sealed, thereby providing an optical semiconductor element encapsulation sheet.

[0011] The above-mentioned thermosetting resin layer preferably has a viscosity of 30,000 Pa·s or less at the sealing temperature.

[0012] The thermosetting resin layer described above preferably has a room-temperature modulus E' of 500 to 6000 MPa after curing.

[0013] The thickness of the thermosetting resin layer is preferably 10 to 200 μm.

[0014] The above-mentioned sheet for encapsulating the optical semiconductor element preferably has an anti-glare and / or anti-reflective layer on the surface opposite to the side that contacts the optical semiconductor element relative to the encapsulating resin layer.

[0015] Furthermore, the present invention provides an optical semiconductor device comprising a substrate, an optical semiconductor element disposed on the substrate, and an optical semiconductor element encapsulation sheet or a cured product thereof for encapsulating the optical semiconductor element. [Effects of the Invention]

[0016] The optical semiconductor element encapsulation sheet of the present invention suppresses brightness variations when encapsulating an optical semiconductor element and can sufficiently fill the gap between the optical semiconductor element and the substrate. Therefore, the optical semiconductor device encapsulated with the optical semiconductor element encapsulation sheet exhibits excellent light diffusion and light extraction efficiency. [Brief explanation of the drawing]

[0017] [Figure 1] This is a cross-sectional view of a sheet for encapsulating an optical semiconductor device according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of a sheet for encapsulating an optical semiconductor device according to another embodiment of the present invention. [Figure 3] Figure 1 is a partial cross-sectional view showing one embodiment of an optical semiconductor device using a sheet for encapsulating optical semiconductor elements. [Figure 4] FIG. 1 is a partial cross-sectional view showing another embodiment of an optical semiconductor device using the sheet for sealing an optical semiconductor element shown in FIG. 1. [Figure 5] It is a cross-sectional view of a sample used for evaluation of embedding performance in Examples. [Figure 6] It is a top view of a dummy element used for evaluation of embedding performance in Examples. [Modes for Carrying Out the Invention]

[0018] [Sheet for Sealing Optical Semiconductor Element] The sheet for sealing an optical semiconductor element of the present invention is at least provided with a sealing resin layer including a thermosetting resin layer containing light-diffusing fine particles. In this specification, the sheet for sealing an optical semiconductor element refers to a sheet for sealing one or more optical semiconductor elements disposed on a substrate with the sealing resin layer. Further, in this specification, "sealing an optical semiconductor element" means embedding at least a part of the optical semiconductor element in the sealing resin layer, or following and covering the optical semiconductor element with the sealing resin layer. The sealing resin layer preferably has flexibility that allows at least a part of the optical semiconductor element to be embedded therein, or allows the optical semiconductor element to be followed and covered by the sealing resin layer.

[0019] <Sealing Resin Layer> The sealing resin layer at least includes the thermosetting resin layer. The sealing resin layer may include other layers than the thermosetting resin layer. Each of the layers constituting the sealing resin layer (the thermosetting resin layer and other layers) may be a single layer in the sealing resin layer, or may be a multilayer having the same or different composition. When a plurality of thermosetting resin layers are included, the plurality of layers may be laminated in contact with each other, or may be laminated separately (for example, two thermosetting resin layers are laminated via another layer).

[0020] When encapsulating an optical semiconductor element, it is preferable that at least one thermosetting resin layer in the encapsulating resin layer is a layer that comes into contact with the optical semiconductor element when it is encapsulated, and is the layer closest to the optical semiconductor element in the encapsulating resin layer. With this configuration, the thermosetting resin layer can flow when the optical semiconductor element is encapsulated, filling the gap between the optical semiconductor element and the substrate.

[0021] (thermosetting resin layer) The above-mentioned thermosetting resin layer is a resin layer that has thermosetting properties. Examples of resins constituting the above-mentioned thermosetting resin layer include known and conventional 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 (polyvinyl ether, etc.), polyamide resins, fluororesins, vinyl acetate / vinyl chloride copolymers, and modified polyolefins. One type of resin may be used, or two or more types may be used. Among these, acrylic resins are preferred.

[0022] The above-mentioned acrylic resin is a resin that contains constituent units derived from acrylic monomers (monomer components having a (meth)acryloyl group or a structure convertible thereto in the molecule) as constituent units of the resin (polymer). The above-mentioned acrylic resin may be used by one type only, or by two or more types.

[0023] The above-mentioned acrylic resin is preferably a resin that contains the largest mass percentage of constituent units derived from (meth)acrylic acid ester. 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.

[0024] From the viewpoint of having thermosetting properties, the above-mentioned thermosetting resin layer preferably contains a thermosetting resin. As the above-mentioned thermosetting resin, known or conventional thermosetting resins can be used, for example, resins having thermosetting functional groups. Among these, acrylic resins having thermosetting functional groups (acrylic resins containing thermosetting functional groups) are preferred as the above-mentioned thermosetting resin.

[0025] Examples of the thermosetting functional groups include epoxy group-containing groups such as glycidyl groups, carboxyl groups, hydroxyl groups, isocyanate groups, and aziridyl groups. Among these, epoxy group-containing groups are preferred, and glycidyl groups are more preferred. In other words, acrylic resins containing glycidyl groups are particularly preferred as acrylic resins having thermosetting functional groups. The thermosetting functional groups may consist of only one type or two or more types.

[0026] The above thermosetting functional group-containing acrylic resin preferably contains structural units derived from monomers having thermosetting functional groups, and more preferably contains structural units derived from acrylic monomers having thermosetting functional groups (thermosetting functional group-containing acrylic monomers). Examples of monomers having thermosetting functional groups include epoxy group-containing (meth)acrylic acid esters such as glycidyl group-containing (meth)acrylic acid esters, carboxyl group-containing monomers, acid anhydride group-containing monomers, and hydroxyl group-containing (meth)acrylic acid esters.

[0027] Examples of the glycidyl group-containing (meth)acrylic acid esters mentioned above include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.

[0028] Examples of the above carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the above acid anhydride group-containing monomers include maleic anhydride and itaconic anhydride.

[0029] Examples of the hydroxyl group-containing (meth)acrylic acid esters mentioned above 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.

[0030] Among the thermosetting functional group-containing acrylic monomers mentioned above, epoxy group-containing (meth)acrylic acid esters are preferred, and glycidyl group-containing (meth)acrylic acid esters are more preferred. When the acrylic resin contains constituent units derived from epoxy group-containing (meth)acrylic acid esters, the epoxy groups act as thermosetting functional groups, and even without the addition of a curing agent, the reaction of the epoxy groups proceeds by thermosetting, and the thermosetting resin layer hardens. For this reason, the thermosetting resin layer has appropriate flexibility after thermosetting and exhibits superior sealing properties for optical semiconductor devices.

[0031] The content of the constituent units derived from the epoxy group-containing (meth)acrylic acid ester is preferably 5 to 50% by mass, and more preferably 6 to 45% by mass, relative to the total amount (100% by mass) of all constituent units of the acrylic resin in the thermosetting resin layer. When the content is within the above range, the thermosetting resin layer has appropriate flexibility after heat curing and exhibits superior sealing properties for optical semiconductor devices.

[0032] The above-mentioned thermosetting functional group-containing acrylic resin may contain constituent units derived from monomers other than the above-mentioned thermosetting functional group-containing monomer. Examples of the above-mentioned other monomers include other (meth)acrylic acid esters other than the above-mentioned thermosetting functional group-containing acrylic monomer. Only one of the above-mentioned other monomers may be used, or two or more may be used.

[0033] Examples of the above-mentioned other (meth)acrylic acid esters include hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group. Examples of hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group include alkyl (meth)acrylic acid esters having linear or branched aliphatic hydrocarbon groups, cycloalkyl (meth)acrylic acid esters having alicyclic hydrocarbon groups, and aryl (meth)acrylic acid esters having aromatic hydrocarbon groups. Only one type of hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group may be used, or two or more types may be used.

[0034] Examples of the above alkyl (meth)acrylate esters 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 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.

[0035] Among the above alkyl (meth)acrylate esters, alkyl (meth)acrylate esters having linear or branched aliphatic hydrocarbon groups with 1 to 20 carbon atoms (preferably 1 to 14, more preferably 2 to 10, and even more preferably 2 to 8) are preferred. When the number of carbon atoms is within the above range, the flexibility of the thermosetting group-containing acrylic resin during thermosetting is more appropriate, and the embedding ability is further improved.

[0036] Examples of (meth)acrylic acid esters having the above-mentioned 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 three or more aliphatic hydrocarbon rings 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.

[0037] Examples of (meth)acrylic acid esters having the above-mentioned aromatic hydrocarbon group include phenyl (meth)acrylate and benzyl (meth)acrylate.

[0038] Examples of hydrocarbon group-containing (meth)acrylic acid esters having an alkoxy group include those in which one or more hydrogen atoms in the hydrocarbon group of the above hydrocarbon group-containing (meth)acrylic acid ester are substituted with an alkoxy group, such as 2-methoxymethyl ester, 2-methoxyethyl ester, and 2-methoxybutyl ester of (meth)acrylic acid.

[0039] Other monomer components mentioned above include polar group-containing monomers such as sulfonic acid group-containing monomers, phosphate group-containing monomers, and nitrogen atom-containing monomers. Examples of sulfonic acid group-containing monomers include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of phosphate group-containing monomers include 2-hydroxyethylacryloyl phosphate. Examples of 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.

[0040] The above-mentioned thermosetting functional group-containing acrylic resin may contain constituent units derived from polyfunctional (meth)acrylates copolymerizable with monomer components constituting the acrylic resin in order to form a crosslinked structure in its polymer backbone. Examples of the above-mentioned polyfunctional (meth)acrylates 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. Only one type of the above-mentioned polyfunctional (meth)acrylate may be used, or two or more types may be used.

[0041] The above-mentioned thermosetting functional group-containing acrylic resin is obtained by polymerizing the various monomer components described above. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). Furthermore, the resulting acrylic resin may be a random copolymer, block copolymer, graft copolymer, or any other type.

[0042] The weight-average molecular weight of the epoxy group-containing acrylic resin described above is preferably 2,000 to 400,000, and more preferably 30,000 to 300,000, from the viewpoint of having a certain degree of hardness after curing of the thermosetting resin layer and reducing the adhesion between the sides of the optoelectronic device. When the weight-average molecular weight is within the above range, the embedding properties of the optoelectronic device are superior. The weight-average molecular weight described above is measured by gel permeation chromatography (GPC) and the value is calculated on a polystyrene basis.

[0043] The content of the epoxy group-containing acrylic resin is preferably 40% by mass or more (for example, 40 to 100% by mass), more preferably 50% by mass or more, and even more preferably 55% by mass or more, based on the total amount of resin (100% by mass) in the thermosetting resin layer. When the content is 40% by mass or more, the embedding properties of the optical semiconductor device are superior. The content is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 75% by mass or less.

[0044] The thermosetting resin layer preferably contains a component having a thermosetting functional group (first functional group) in the thermosetting functional group-containing acrylic resin described above, and a functional group (second functional group) that can react with heat. The second functional group is also a thermosetting functional group. In this case, the reaction between the first functional group and the second functional group during heating of the thermosetting resin layer further accelerates the curing of the thermosetting resin layer.

[0045] The component having the second functional group described above may be a thermosetting functional group-containing acrylic resin having the first functional group described above, or a thermosetting functional group-containing acrylic resin other than the thermosetting functional group-containing acrylic resin having the first functional group described above, or any other component having the second functional group. The component having the second functional group may be used by one or by two or more.

[0046] Examples of combinations of the first functional group and the second functional group include carboxyl group and epoxy group, epoxy group and carboxyl group, carboxyl group and aziridyl group, aziridyl group and carboxyl group, hydroxyl group and isocyanate group, and isocyanate group and hydroxyl group. The above combinations may consist of only one type or two or more types.

[0047] When the above epoxy group-containing acrylic resin is included, the thermosetting resin layer preferably contains a component having a functional group that is reactive with the epoxy group as the component having the second functional group. Examples of functional groups that are reactive with the epoxy group include carboxyl groups, aziridyl groups, and hydroxyl groups. Among these, carboxyl groups and hydroxyl groups are preferred. As for the hydroxyl group, a silanol group is preferred from the viewpoint of high acidity and excellent reactivity with the epoxy group.

[0048] The component having the carboxyl group is preferably the resin described above, and more preferably a carboxyl group-containing acrylic resin. When the carboxyl group-containing acrylic resin is included, the reaction between the epoxy group and the carboxyl group in the epoxy group-containing acrylic resin proceeds more easily, even without the addition of a curing agent, and the sealing properties of the optical semiconductor device are improved. Furthermore, the scratch resistance of the surface is further improved.

[0049] The above-mentioned carboxyl group-containing acrylic resin preferably contains structural units derived from carboxyl group-containing monomers, and more preferably contains structural units derived from carboxyl group-containing acrylic monomers. Examples of the above-mentioned carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0050] The content of the constituent units derived from the above-mentioned carboxyl group-containing acrylic monomer is preferably 1 to 50% by mass, and more preferably 10 to 40% by mass, relative to the total amount (100% by mass) of all constituent units of the above-mentioned carboxyl group-containing acrylic resin. When the above content is within the above range, the thermosetting resin layer has appropriate flexibility after heat curing and exhibits superior sealing properties for optical semiconductor devices.

[0051] The above-mentioned carboxyl group-containing acrylic resin may contain constituent units derived from monomers other than the above-mentioned carboxyl group-containing monomer. Examples of the above-mentioned other monomers include other (meth)acrylic acid esters other than the above-mentioned thermosetting functional group-containing acrylic monomer, the above-mentioned polar group-containing monomer, and the above-mentioned polyfunctional (meth)acrylate. Only one of the above-mentioned other monomers may be used, or two or more may be used.

[0052] Other (meth)acrylic acid esters mentioned above include, for example, hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group. Among the alkyl (meth)acrylic acid esters in the hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group, alkyl (meth)acrylic acid esters having linear or branched aliphatic hydrocarbon groups with 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 number of carbon atoms is within the above range, the flexibility of the thermosetting group-containing acrylic resin is made more appropriate and the embedding ability is further improved.

[0053] In order to appropriately exhibit basic properties such as adhesion to the above-mentioned optical semiconductor device in the thermosetting resin layer, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester, which may have an alkoxy group, to the total amount (100% by mass) of all constituent units of the carboxyl group-containing acrylic resin is preferably 50 to 95% by mass, and more preferably 60 to 90% by mass.

[0054] The weight-average molecular weight of the above-mentioned 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 optoelectronic semiconductor device are superior. The above-mentioned weight-average molecular weight is measured by gel permeation chromatography (GPC) and the value is calculated on a polystyrene basis.

[0055] When the above-mentioned carboxyl group-containing acrylic resin is included, the content of the carboxyl group-containing acrylic resin is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and even more preferably 25 to 45% by mass, based on the total amount of resin (100% by mass) in the thermosetting resin layer. When the above-mentioned content is within the above range, the thermosetting properties of the thermosetting resin layer are superior. Furthermore, the scratch resistance of the surface is superior.

[0056] The above-mentioned thermosetting resin layer contains light-diffusing fine particles. More specifically, the above-mentioned thermosetting resin layer contains light-diffusing fine particles dispersed in the adhesive layer. Therefore, the above-mentioned thermosetting resin layer functions as a diffusion functional layer intended to diffuse light after thermal curing. Light emitted from the optical semiconductor element is diffused in the diffusion functional layer, and for example, light emitted from the side of the optical semiconductor element is emitted towards the front of the image display device, thereby improving the front brightness of the image display device. Only one type of light-diffusing fine particle may be used, or two or more types may be used.

[0057] The above-mentioned light-diffusing fine particles have an appropriate refractive index difference with the resin constituting the thermosetting resin layer, and impart diffusion performance after the thermosetting resin layer has cured. Examples of light-diffusing fine particles include inorganic fine particles and polymer fine particles. Examples of materials for inorganic fine particles include silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and metal oxides. Examples of materials for polymer fine particles include silicone resin, acrylic resin (including polymethacrylate resins such as polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, and epoxy resin.

[0058] The polymer fine particles are preferably composed of silicone resin. The inorganic fine particles are preferably composed of metal oxides. The metal oxides are preferably titanium oxide and barium titanate, and more preferably titanium oxide. Having such a configuration results in superior light diffusion after curing of the thermosetting resin layer and further suppression of brightness variations.

[0059] The shape of the above-mentioned light-diffusing particles is not particularly limited and may be, for example, perfectly spherical, flattened, or irregularly shaped.

[0060] From the viewpoint of providing appropriate light diffusion performance, the average particle size (median diameter) of the above light-diffusing fine particles is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.7 μm or more, and particularly preferably 1 μm or more, and may also be 5 μm or more or 10 μm or more. Furthermore, the larger the average particle size, the lower the viscosity of the thermosetting resin layer at the sealing temperature, and the more sufficiently the void between the optical semiconductor element and the substrate can be filled. Furthermore, from the viewpoint of sufficiently filling the void between the optical semiconductor element and the substrate, the average particle size of the above light-diffusing fine particles is preferably 40 μm or less, more preferably 35 μm or less, and even more preferably 30 μm or less. The average particle size can be measured, for example, using a Coulter counter.

[0061] The proportion of light-diffusing fine particles with a particle diameter of 20 μm or less among the above-mentioned light-diffusing fine particles is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, based on the total amount of the above-mentioned light-diffusing fine particles (100% by mass). When the above proportion is 25% by mass or more, the void between the optical semiconductor element and the substrate can be sufficiently filled. The above proportion may be 100% by mass, or 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less. The above particle diameter can be measured, for example, using a Coulter counter.

[0062] The refractive index of the above 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.

[0063] The absolute value of the refractive index difference between the light-diffusing fine particles and the resin constituting the thermosetting resin layer (the resin layer from which the light-diffusing fine particles have been removed in the thermosetting resin layer) is preferably 0.001 or higher, more preferably 0.01 or higher, even more preferably 0.02 or higher, particularly preferably 0.03 or higher, and may also be 0.04 or higher, or 0.05 or higher, from the viewpoint of more efficiently reducing brightness variations 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 lower, more preferably 4 or lower, and even more preferably 3 or lower, from the viewpoint of preventing excessive haze and displaying high-definition images.

[0064] From the viewpoint of imparting appropriate light diffusion performance to the sheet for encapsulating optical semiconductor devices, the content ratio of the light-diffusing fine particles in the thermosetting resin layer is preferably 0.1% by mass or more, more preferably 0.7% by mass or more, and even more preferably 2% by mass or more, relative to the total amount (100% by mass) of the thermosetting resin layer. Furthermore, from the viewpoint of preventing excessive haze and displaying high-definition images, the content ratio of the light-diffusing fine particles is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0065] The thermosetting resin layer described above may contain other components besides those described above, as long as they do not impair the effects of the present invention. Examples of these other components include colorants, 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.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, granules, foils, and the like. Each of these other components may be used individually or in combination of two or more.

[0066] The resin content in the thermosetting 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 thermosetting resin layer. The above content is preferably 99.9% by mass or less, more preferably 99.3% by mass or less, and even more preferably 98% by mass or less. Furthermore, the acrylic resin content is preferably within the above range, the thermosetting resin content is preferably within the above range, and the thermosetting functional group-containing acrylic resin is preferably within the above range.

[0067] The haze (100 μm thickness) of the thermosetting resin layer described above is not particularly limited, but from the viewpoint of efficiently reducing brightness variation, 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 also be 70% or more, 80% or more, 90% or more, 95% or more, or 97% or more, and even more preferably around 99.9% for superior brightness variation improvement effect. The upper limit of the haze of the thermosetting resin layer described above is not particularly limited, i.e., it may be 100%. The haze may be a value before or after curing, but it is preferably a value after curing.

[0068] The total light transmittance (100 μm thickness) of the thermosetting resin layer described above 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. Furthermore, the upper limit of the total light transmittance of the thermosetting resin layer described above is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less. The total light transmittance described above may be the value before or after curing, but it is preferable to use the value after curing.

[0069] The haze and total light transmittance of the above-mentioned thermosetting resin layer are single-layer values ​​and can be measured by the methods specified in JIS K7136 and JIS K7361-1. These values ​​can be controlled by the type and thickness of the thermosetting resin layer, the type and amount of light-diffusing fine particles, etc.

[0070] The viscosity of the thermosetting resin layer described above is preferably 30,000 Pa·s or less at the sealing temperature, more preferably 25,000 Pa·s or less, even more preferably 20,000 Pa·s or less, and particularly preferably 15,000 Pa·s or less. When the viscosity is 30,000 Pa·s or less, the thermosetting resin layer flows when the optical semiconductor element is sealed, allowing for more sufficient filling of the gap between the optical semiconductor element and the substrate. Furthermore, the viscosity at the sealing temperature is, for example, 1,000 Pa·s or more, preferably 4,000 Pa·s or more, and more preferably 7,000 Pa·s or more. When the viscosity is 1,000 Pa·s or more, the fluidity of the thermosetting resin layer does not become too low, making it difficult to form gaps between adjacent optical semiconductor elements. The sealing temperature is preferably 50 to 150°C, and more preferably 80 to 120°C. That is, it is preferable that the viscosity at at least one point between 50 and 150°C (preferably 80 to 120°C) is within the above range. The viscosity can be controlled, for example, by the monomer composition of the resin used to form the thermosetting resin layer, the weight-average molecular weight, the amount of crosslinking agent used (amount added), and the type and content of other additives.

[0071] The cured room-temperature modulus (cured room-temperature tensile storage modulus) E' of the above thermosetting resin layer is preferably 500 to 6000 MPa, more preferably 600 to 5000 MPa, and even more preferably 700 to 3000 MPa. When the cured room-temperature modulus E' is within the above range, stickiness is further reduced, and sheet damage is less likely to occur when separating multiple optoelectronic devices containing encapsulated optical semiconductor elements from adjacent optoelectronic devices.

[0072] The thickness of the thermosetting resin layer is preferably 10 to 200 μm, more preferably 20 to 180 μm, and even more preferably 30 to 150 μm. When the thickness is within the above range, the light diffusion properties are superior, and the brightness of the light emitted by the optical semiconductor device becomes higher.

[0073] (Other layers) Other layers mentioned above include uncolored resin layers. These uncolored resin layers are different from the diffusion function layer and the colored layer, and are not intended to diffuse light, nor are they intended to prevent light reflection by metal wiring or the like. The uncolored resin layer may be colorless or slightly colored. It is preferable that the uncolored resin layer be provided on the side of the thermosetting resin layer opposite to the side that contacts the optical semiconductor element. The uncolored resin layer may also be a curable resin layer or an adhesive layer. In this specification, "adhesive layer" refers to a layer that, when subjected to external pressure (e.g., minute pressure), adheres to two surfaces based on the cohesive force based on the chemical structure of the composition, and has the property of being able to be peeled off if necessary.

[0074] The content ratio of the coloring agent in the above-mentioned uncolored resin 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 uncolored resin layer, and may also be less than 0.01% by mass or less than 0.005% by mass.

[0075] From the viewpoint of improving the brightness of the image display device, the content of light-diffusing fine particles in the above-mentioned uncolored resin 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 uncolored resin layer.

[0076] The haze of the above-mentioned uncolored resin layer (100 μm thickness) 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 of the above-mentioned uncolored resin layer is not particularly limited.

[0077] The total light transmittance of the uncolored resin layer described above 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. Furthermore, the upper limit of the total light transmittance of the uncolored resin layer described above is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

[0078] The haze and total light transmittance of the above-mentioned uncolored resin layer are single-layer values ​​and can be measured by the methods specified in JIS K7136 and JIS K7361-1, and can be controlled by the type and thickness of the uncolored resin layer.

[0079] Examples of the structure (layered structure) of the encapsulating resin layer mentioned above include a thermosetting resin layer and a thermosetting resin layer / uncolored resin layer (listed in order from the optical semiconductor device side).

[0080] <Base material part> In the optical semiconductor device encapsulation sheet of the present invention, the encapsulation resin layer may be provided on at least one surface of the substrate portion. That is, the semiconductor device encapsulation sheet may comprise a substrate portion and the encapsulation resin layer provided on at least one surface of the substrate portion. When the optical semiconductor device encapsulation sheet of the present invention comprises the substrate portion, the side of the encapsulation resin layer opposite to the side in contact with the optical semiconductor device is the side in contact with the substrate portion. Providing the substrate portion on the side of the encapsulation resin layer opposite to the optical semiconductor device in the optical semiconductor device encapsulation sheet makes the surface of the encapsulation resin layer flat, thereby reducing diffuse reflection of light and improving the appearance of the optical semiconductor device both when it is off and when it is lit. Furthermore, by forming an anti-glare layer or an anti-reflective layer on the substrate portion as described later, anti-glare and anti-reflective properties can be imparted to the optical semiconductor device. In addition, the substrate portion serves as a support for the encapsulation resin layer in the optical semiconductor device encapsulation sheet, and its presence improves the handling of the optical semiconductor device encapsulation sheet. Note that the substrate portion is not necessarily required.

[0081] The above-mentioned base material portion may be a single layer or a multi-layered portion with the same composition or different thicknesses. If the above-mentioned base material portion is a multi-layered portion, each layer may be bonded together with other layers such as an adhesive layer. Note that the base material layer used in the base material portion is the part that is attached to the adherend together with the above-mentioned sealing resin layer, and the release liner that is peeled off when the photosemiconductor element encapsulation sheet is used (attached), and the surface protection film that merely protects the surface of the base material portion are not included in the "base material portion".

[0082] Examples of the substrate layers constituting the above-mentioned substrate include glass and plastic substrates (especially plastic films). Examples of the resins constituting the above-mentioned plastic substrate include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-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 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 fully aromatic polyamides; polyphenyl sulfides; fluororesins; polyvinyl chloride; polyvinylidene chloride; cellulose resins such as triacetylcellulose (TAC); silicone resins; acrylic resins such as polymethyl methacrylate (PMMA); polysulfones; polyarylates; and polyvinyl acetate. One or more of the above resins may be used. The above substrate layer may be various optical films such as anti-reflective (AR) films, polarizing plates, and phase difference plates.

[0083] The thickness of the above plastic film is preferably 20 to 300 μm, and more preferably 40 to 250 μm. If the thickness is 20 μm or more, the support and handling of the sheet for encapsulating the optical semiconductor device are further improved. If the thickness is 300 μm or less, the sheet for encapsulating the optical semiconductor device can be made thinner.

[0084] The surface of the substrate portion on the side with the sealing resin layer may be subjected to surface treatments such as physical treatments like corona discharge treatment, plasma treatment, sandblasting, ozone exposure treatment, flame exposure treatment, high-voltage electric shock exposure treatment, and ionization active energy ray treatment; chemical treatments like chromic acid treatment; or easy-adhesion treatments using a coating agent (primer) in order to improve adhesion and retention with the sealing resin layer. It is preferable that the surface treatment to improve adhesion is applied to the entire surface of the substrate portion on the side with the sealing resin layer.

[0085] The thickness of the above-mentioned substrate portion is preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of excellent functionality as a support and surface scratch resistance. The thickness of the above-mentioned substrate portion is preferably 300 μm or less, and more preferably 250 μm or less, from the viewpoint of superior transparency.

[0086] <Sheet for encapsulating optoelectronic semiconductor devices> The above-mentioned sheet for encapsulating optical semiconductor elements may include a layer having anti-glare and / or anti-reflective properties. Such a configuration can suppress gloss and light reflection when encapsulating optical semiconductor elements, thereby improving the appearance. An anti-glare layer is an example of the anti-glare layer. An anti-reflective layer is an example of the anti-reflective layer. The anti-glare treatment and anti-reflective treatment can each be carried out by known or conventional methods. The anti-glare layer and the anti-reflective layer may be the same layer or different layers. The anti-glare and / or anti-reflective layer may consist of only one layer or two or more layers. It is preferable that the anti-glare and / or anti-reflective layer is provided on the side of the sheet for encapsulating optical semiconductor elements opposite to the side in contact with the optical semiconductor element (preferably the surface) relative to the encapsulating resin layer.

[0087] The haze of the above-mentioned sheet for encapsulating the optical semiconductor device is not particularly limited, but from the viewpoint of efficiently reducing brightness variation, 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 also be 70% or more, 80% or more, 90% or more, 95% or more, or 97% or more, and even more preferably around 99.9% for superior brightness variation improvement effect. The upper limit of the haze of the above-mentioned sheet for encapsulating the optical semiconductor device is not particularly limited, i.e., it may be 100%. The above-mentioned haze may be the value before or after curing, but the value after curing is preferred.

[0088] The total light transmittance of the above-mentioned optical semiconductor element encapsulation sheet 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. Furthermore, the upper limit of the total light transmittance of the above-mentioned optical semiconductor element encapsulation sheet is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less. The above-mentioned total light transmittance may be the value before or after curing, but the value after curing is preferred.

[0089] The haze and total light transmittance mentioned above can be measured by the methods specified in JIS K7136 and JIS K7361-1, respectively, and can be controlled by the lamination order, type, and thickness of each layer constituting the sealing resin layer and the substrate.

[0090] In the above-mentioned sheet for encapsulating the optical semiconductor element, the distance from the optical semiconductor element to the thermosetting resin layer is preferably 0 to 20 μm, and more preferably 0 to 10 μm, when the optical semiconductor element is encapsulated. When the distance is within the above range, the brightness of the image display device is improved.

[0091] The thickness of the sheet used to encapsulate the above-mentioned optical semiconductor device is preferably 10 to 600 μm, more preferably 20 to 550 μm, even more preferably 30 to 500 μm, even more preferably 40 to 450 μm, and particularly preferably 50 to 400 μm, from the viewpoint of more efficiently reducing color shift. The release liner is not included in the above thickness.

[0092] The thickness of the above-mentioned sealing resin layer is, for example, 10 to 500 μm, preferably 20 to 400 μm, and more preferably 100 to 300 μm. If the thickness is 10 μm or more, the sealing performance of the optical semiconductor device is improved. If the thickness is 500 μm or less, the thickness of the optical semiconductor device becomes thinner.

[0093] [Removable Liner] The above-mentioned sealing resin layer may be formed on the peel-off surface of the peel-off liner. When the above-mentioned sealing resin layer is formed on the peel-off liner, it is preferable that the thermosetting resin layer of the sealing resin layer is on the side that contacts the peel-off liner. If the above-mentioned base material is not present, both sides of the sealing resin layer may be on the side that contacts the peel-off liner. The peel-off liner is used as a protective material for the sheet used to encapsulate the optical semiconductor element and is peeled off when encapsulating the optical semiconductor element. Note that the peel-off liner is not necessarily required.

[0094] The above-mentioned peel-off liner is an element for covering and protecting the surface of the sheet used to encapsulate the optical semiconductor element, and is peeled off from the sheet when the sheet is bonded to the substrate on which the optical semiconductor element is placed.

[0095] Examples of the above-mentioned release liners include polyethylene terephthalate (PET) film, polyethylene film, polypropylene film, plastic films and paper products whose surfaces are coated with release agents such as fluorine-based release agents and long-chain alkyl acrylate-based release agents.

[0096] The thickness of the above-mentioned release liner is, for example, 10 to 200 μm, preferably 15 to 150 μm, and more preferably 20 to 100 μm. If the thickness is 10 μm or more, the release liner is less likely to break when cut during processing. If the thickness is 200 μm or less, the release liner is easier to peel off from the sheet for encapsulating the optical semiconductor element during use.

[0097] Figure 1 is a cross-sectional view showing one embodiment of the optical semiconductor device encapsulation sheet of the present invention. As shown in Figure 1, the optical semiconductor device encapsulation sheet 1 can be used to encapsulate one or more optical semiconductor devices arranged on a substrate, and comprises an encapsulation resin layer 2 and a functional layer 4 formed on the encapsulation resin layer 2.

[0098] In the photoelectronic device encapsulation sheet 1 shown in Figure 1, the encapsulation resin layer 2 is composed of a thermosetting resin layer 21. A release liner 3 is attached to one side of the thermosetting resin layer 21, and a functional layer 4 is formed on the other side. The photoelectronic device encapsulation sheet 1 shown in Figure 1 may also include a base material. If a base material is included, the base material consists of a base film and a functional layer 4 which is a surface treatment layer, and the base material is provided on the side of the encapsulation resin layer 2 opposite to the side that encapsulates the photoelectronic device, such that the functional layer 4 becomes the surface of the photoelectronic device encapsulation sheet 1.

[0099] Figure 2 is a cross-sectional view showing another embodiment of the optical semiconductor device encapsulation sheet of the present invention. In the optical semiconductor device encapsulation sheet 1 shown in Figure 2, the encapsulation resin layer 2 is formed from a laminate of a thermosetting resin layer 21 and a non-colored resin layer 22, and the functional layer 4 is formed on the surface of the non-colored resin layer 22. The non-colored resin layer 22 is directly laminated to the thermosetting resin layer 21. A release liner 3 is attached to the thermosetting resin layer 21, and the functional layer 4 is formed on the non-colored resin layer 22. Otherwise, it is the same as the optical semiconductor device encapsulation sheet shown in Figure 1.

[0100] In Figures 1 and 2, the functional layer 4 is a layer not included in the sealing resin layer, and is a layer that can provide various functions for sealing the optical semiconductor element. Examples of the functional layer include a layer including a surface treatment layer. With this configuration, the optical semiconductor element encapsulation sheet with a laminated functional layer including a surface treatment layer has excellent light diffusion properties and excellent light extraction efficiency. Examples of the surface treatment layer include an anti-glare treatment layer, an anti-reflective treatment layer, and a hard coat treatment layer. The functional layer may be formed by applying an embossed or other uneven shape to the surface of a layer located on the surface of the sealing resin layer opposite to the side that seals the optical semiconductor element (thermosetting resin layer 21 in Figure 1, uncolored resin layer 22 in Figure 2), or a separately manufactured functional layer may be bonded to the surface of the sealing resin layer 2. The functional layer may be laminated on the sealing resin layer in the optical semiconductor element encapsulation sheet, or, if the base material is provided, it may be laminated on the base material.

[0101] [Method for manufacturing sheets for encapsulating optoelectronic semiconductor devices] An embodiment of the manufacturing method for the optical semiconductor device encapsulation sheet described above will now be explained. For example, the optical semiconductor device encapsulation sheet 1 shown in Figure 1 is made by creating a thermosetting resin layer sandwiched between the peeling surfaces of two peeling liners. One of the peeling liners bonded to the thermosetting resin layer 21 is peeling liner 3. Next, the other peeling liner (not peeling liner 3) is peeled off and an embossed or other uneven shape is applied to the exposed surface to form a functional layer 4. In this way, the optical semiconductor device encapsulation sheet 1 shown in Figure 1 can be made by laminating the peeling liner 3, the thermosetting resin layer 21, and the functional layer 4 in this order.

[0102] [Optical Semiconductor Equipment] An optoelectronic device such as an image display device can be manufactured using the above-described optoelectronic device encapsulation sheet. The optoelectronic device manufactured using the above-described optoelectronic device encapsulation sheet comprises a substrate, an optoelectronic device disposed on the substrate, and the above-described optoelectronic device encapsulation sheet or a cured product obtained by curing the sheet. The cured product is a cured product obtained by thermosetting the thermosetting resin layer 21 (or further, a non-colored resin layer 22) of the optoelectronic device encapsulation sheet, and specifically comprises a cured encapsulation layer obtained by thermosetting the thermosetting resin layer 21.

[0103] Examples of the above-mentioned optical semiconductor devices include light-emitting diodes (LEDs) such as blue light-emitting diodes, green light-emitting diodes, red light-emitting diodes, and ultraviolet light-emitting diodes.

[0104] In the above-described optical semiconductor device, the sheet for encapsulating the optical semiconductor elements is preferable because it is excellent in its ability to conform to irregularities when the optical semiconductor elements are convex portions and the gaps between multiple optical semiconductor elements are concave portions, and it is excellent in its conformability and embedding of the optical semiconductor elements.

[0105] Figure 3 shows an embodiment of an optical semiconductor device using the optical semiconductor element encapsulation sheet 1 shown in Figure 1. The optical semiconductor device 10 shown in Figure 3 comprises a substrate 5, a plurality of optical semiconductor elements 6 arranged on one side 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 when the release liner 3 is peeled off from the optical semiconductor element encapsulation sheet 1, and a cured encapsulation layer 7 is formed by the thermal curing of the thermosetting resin layer 21. For example, the cured encapsulation layer 7 consists of a cured resin layer 71 formed by the thermal curing of the thermosetting resin layer 21. The plurality of optical semiconductor elements 6 are encapsulated together in the cured encapsulation layer 7. The cured encapsulation layer 7 adheres closely to the optical semiconductor elements 6 and the substrate 5, following the uneven shape formed by the plurality of optical semiconductor elements 6, and embeds the optical semiconductor elements 6.

[0106] In the optical semiconductor device 10 shown in Figure 3, the optical semiconductor element 6 is completely embedded and sealed within the cured resin layer 71, and is also sealed by the cured resin layer 71. That is, the optical semiconductor element 6 is sealed by a cured sealing layer 7 consisting of the cured resin layer 71. The cured resin layer 71 fills the space between the optical semiconductor element 6 and the substrate 5, and the spaces between multiple optical semiconductor elements 6 are filled with the cured resin layer 71, which is in contact with the bottom and side surfaces of the optical semiconductor elements 6.

[0107] Figure 4 shows another embodiment of the optical semiconductor device using the optical semiconductor element encapsulation sheet 1 shown in Figure 1. The optical semiconductor device 10 shown in Figure 4 includes a colored layer 8 formed on a substrate 5. That is, the optical semiconductor device 10 shown in Figure 4 includes a substrate 5, a plurality of optical semiconductor elements 6 arranged on one side of the substrate 5, a colored layer 8 formed on the aforementioned one side of the substrate 5, and a cured product of the optical semiconductor element encapsulation sheet 1. By including the colored layer 8, reflection of light due to metal wiring and the like can be prevented. The colored layer 8 is formed on the substrate 5 with a thickness that does not reach the bottom surface of the optical semiconductor elements 6. Therefore, in Figure 4 as well, the cured resin layer 71 fills the space between the optical semiconductor elements 6 and the substrate 5, and the spaces between the plurality of optical semiconductor elements 6 are filled in the cured resin layer 71, which is in contact with the bottom and side surfaces of the optical semiconductor elements 6.

[0108] As described above, the optical semiconductor device encapsulates the optical semiconductor element with a cured encapsulation layer. The thermosetting resin layer has sufficient flexibility before curing, providing excellent conformability to uneven surfaces and adequately embedding the optical semiconductor element. Upon heating, the thermosetting resin layer acts as an underfill material, flowing at the encapsulation temperature to fill the space between the optical semiconductor element 6 and the substrate 5. After subsequent curing, it fixes the optical semiconductor element in place. As a result, the optical semiconductor element 6 adheres closely to the cured encapsulation layer, resulting in excellent encapsulation of the optical semiconductor element 6. Furthermore, since the cured resin layer 71 containing light-diffusing fine particles fills the space between the optical semiconductor element 6 and the substrate 5, brightness variations are further suppressed. Therefore, the optical semiconductor device encapsulated with the optical semiconductor element encapsulation sheet exhibits excellent light diffusion, superior light extraction efficiency, and a superior appearance.

[0109] The above-mentioned optical semiconductor device may consist of individual optical semiconductor devices arranged in a tiled configuration. That is, the above-mentioned optical semiconductor device may consist of multiple optical semiconductor devices arranged in a tiled manner in a planar direction.

[0110] The above-mentioned image display device preferably includes a self-emissive display device. Furthermore, the self-emissive display device can be combined with a display panel as needed to form an image display device. In this case, the optical semiconductor element is an LED element. Examples of the self-emissive display device include LED displays, backlights, or organic electroluminescent (organic EL) display devices. The backlight is particularly preferably a full-surface direct-lit backlight. The backlight includes, for example, a laminate comprising the substrate and a plurality of optical semiconductor elements arranged on the substrate as at least part of its constituent components. For example, in the self-emissive display device, a metal wiring layer for sending light emission control signals to each LED element is laminated on the substrate. Each LED element emitting red (R), green (G), and blue (B) light is 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 level of each LED element to display each color.

[0111] The above-described sheet for encapsulating optical semiconductor elements can be used in optical semiconductor devices that are used in a folded manner, such as flexible displays (in particular, foldable displays). Specifically, it can be used in foldable backlights and foldable self-emissive display devices.

[0112] The above-mentioned sheet for encapsulating the optical semiconductor element has excellent conformability and embedding properties for the optical semiconductor element, and can therefore be preferably used in both cases where the optical semiconductor device is a mini-LED display device and a micro-LED display device.

[0113] [Manufacturing method for optoelectronic devices] The above-described optical semiconductor device can be manufactured by a manufacturing method comprising, for example, a step of bonding the optical semiconductor element encapsulation sheet to the optical semiconductor element provided on the substrate to encapsulate the optical semiconductor element with the encapsulation resin layer (encapsulation step), and a step of curing the thermosetting resin layer in a laminate obtained through the encapsulation step, which comprises the substrate, the optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet that encapsulates the optical semiconductor element, to obtain the cured product (curing step). The cured product is a cured product obtained by thermosetting the thermosetting resin layer, and specifically comprises a cured encapsulation layer obtained by curing the thermosetting resin layer.

[0114] The above manufacturing method may further include a step of dicing the laminate that has undergone the curing step to obtain an optoelectronic device (dicing step). Furthermore, the above manufacturing method may further include a tiling step of arranging a plurality of optoelectronic devices obtained in the dicing step so that they are in contact in a planar direction. The manufacturing method of the optoelectronic device 10 shown in Figure 3 will be described below with due reference.

[0115] (Sealing process) In a method for manufacturing an optical semiconductor device using the above-described optical semiconductor device encapsulation sheet, the method includes an encapsulation step of bonding the optical semiconductor device encapsulation sheet to a substrate on which optical semiconductor devices are arranged, and encapsulating the optical semiconductor devices with an encapsulation resin layer. Specifically, in the above encapsulation step, first, the release liner is peeled off from the optical semiconductor device encapsulation sheet to expose the encapsulation resin layer. Then, the exposed surface of the optical semiconductor device encapsulation sheet is bonded to the substrate surface on which the optical semiconductor devices are arranged of a laminate (such as an optical member) comprising a substrate and optical semiconductor devices (preferably a plurality of optical semiconductor devices) arranged on the substrate. If the laminate comprises a plurality of optical semiconductor devices, the encapsulation resin layer is further positioned to fill the gaps between the plurality of optical semiconductor devices, thereby encapsulating the plurality of optical semiconductor devices collectively. Specifically, the thermosetting resin layer 21 is exposed by peeling off the release liner 3 from the optical semiconductor element encapsulation sheet 1 shown in Figure 1, and then positioned facing the surface of the substrate 5 on which the optical semiconductor element 6 is located. The optical semiconductor element encapsulation sheet 1 is then bonded to the surface of the substrate 5 on which the optical semiconductor element 6 is located, and the optical semiconductor element 6 is embedded in or adhered to the encapsulation resin layer 2.

[0116] The temperature during the bonding process (sealing temperature) is preferably 50 to 150°C, and more preferably 80 to 120°C. Furthermore, the bonding process may be performed under reduced pressure or increased pressure. Reduced pressure or increased pressure can suppress the formation of gaps between the sealing resin layer and the substrate or optical semiconductor element. In the sealing process, it is preferable to bond the optical semiconductor element sealing sheet under reduced pressure, and then apply pressure. When reducing pressure, the pressure is, for example, 1 to 100 Pa, and the reduction time is, for example, 5 to 600 seconds. When applying pressure, the pressure is, for example, 0.05 to 0.5 MPa, and the pressurization time is, for example, 5 to 600 seconds. Through this sealing process, the thermosetting resin layer flows at the sealing temperature, filling the space between the optical semiconductor element and the substrate.

[0117] (hardening process) In the curing step described above, the laminate (for example, the laminate obtained in the sealing step described above) in which the optical semiconductor element encapsulation sheet is bonded to the substrate on which the optical semiconductor element is arranged is heated to cure the thermosetting resin layer and, if necessary, the other layers. Specifically, in the curing step described above, for example as shown in Figure 3, the thermosetting resin layer 21 is cured to form a cured sealing layer 7, and a cured product of the optical semiconductor element encapsulation sheet 1 is obtained. If the thermosetting resin layer is thermosetting, the heating temperature during curing is, for example, in the range of 80 to 200°C, and the heating time is, for example, 1 minute to 24 hours.

[0118] (Dicing process) In the dicing process described above, the laminate that has undergone the curing process is diced. Here, in the laminate subjected to the dicing process, the cured material of the optoelectronic element encapsulation sheet and the substrate 5 extend more broadly in the planar direction than the final optoelectronic device 10. Then, in the dicing process described above, the cured material of the optoelectronic element encapsulation sheet and the side edges of the substrate are diced and removed. The dicing can be carried out by known or conventional methods, for example, by a method using a dicing blade or by laser irradiation. In this way, for example, the optoelectronic device 10 shown in Figure 2 can be manufactured.

[0119] (Tiling process) In the tiling process described above, the multiple optoelectronic devices obtained in the dicing process are arranged and tiled so that they are in contact in a planar direction. In this way, for example, one large image display device can be manufactured. [Examples]

[0120] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. Table 1 shows the types and content (in parts by mass) of each raw material in the resin compositions used in the examples and comparative examples.

[0121] Example 1 A resin composition with a solid content of 50% by mass was prepared by dissolving 58 parts by mass of acrylic polymer A (glycidyl methacrylate (GMA): ethyl acrylate (EA): butyl methacrylate (BMA) = 32% by mass: 32% by mass: 36% by mass, weight-average molecular weight 60,000), 35 parts by mass of acrylic resin (product name "UC-3000", carboxyl group-containing acrylic resin, weight-average molecular weight 10,000, manufactured by Toagosei Co., Ltd.), 2 parts by mass of silane coupling agent (product name "KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd.), and 5 parts by mass of silicone resin (product name "Tospearl 145", manufactured by Momentive Performance Materials Japan, refractive index: 1.42, average particle size: 4.5 μm) as light-diffusing fine particles in methyl ethyl ketone. The above resin composition was applied to the release surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm) and then dried at 130°C for 2 minutes. Subsequently, a release liner (product name "MRE38", manufactured by Mitsubishi Chemical Corporation, 38 μm thick) was bonded at 90°C to produce a sheet for encapsulating optical semiconductor devices consisting of a thermosetting resin layer with an average thickness of 100 μm.

[0122] Examples 2, 3, Comparative Example 1 A sheet for encapsulating optical semiconductor devices was prepared in the same manner as in Example 1, except that the proportions of each raw material were changed as shown in Table 1.

[0123] Example 4 A sheet for encapsulating an optoelectronic semiconductor device was prepared in the same manner as in Example 3, except that a silicone resin (product name "Silcrush-A150G", manufactured by Nikko Rica Co., Ltd., refractive index: 1.42, average particle size: 25 μm) was used as the light-diffusing fine particles.

[0124] Comparative Example 2 (Preparation of acrylic prepolymer A) In a separable flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen gas inlet tube, 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 photopolymerization initiator (trade name "omnirad 184," manufactured by IGM Resins Italia Srl), and 0.09 parts by mass of photopolymerization initiator (trade name "omnirad 651," manufactured by IGM Resins Italia Srl) were added as monomer components. Then, nitrogen gas was introduced and the flask was purged with nitrogen for approximately 1 hour while stirring. After that, the nitrogen gas was purged at 5 mW / cm². 2 Polymerization was carried out by irradiating with ultraviolet light, and the reaction rate was adjusted to 5-15% to obtain acrylic prepolymer A.

[0125] (Fabrication of sheets for encapsulating optoelectronic semiconductor devices) 7 parts by mass of acrylic prepolymer A, 7 parts by mass of 2-hydroxyethyl acrylate (HEA), 0.7 parts by mass of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) as a polyfunctional monomer, 0.1 parts by mass of silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxypropyltrimethoxysilane), 0.2 parts by mass of photopolymerization initiator (trade name "omnirad 651", manufactured by IGM Resins Italia Srl), and 5 parts by mass of silicone resin (trade name "Tospearl 145", manufactured by Momentive Performance Materials Japan, refractive index: 1.42, average particle size: 4.5 μm) as light-diffusing fine particles were added to obtain an adhesive composition (resin composition). This adhesive composition was applied to the release surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation, 38 μm thick) to form a resin composition layer, and then the release surface of another release liner (product name "MRE38", manufactured by Mitsubishi Chemical Corporation, 38 μm thick) was bonded onto the resin composition layer. Next, a black light was used to measure the cumulative light intensity of 2520 mJ / cm². 2Polymerization was carried out by UV irradiation until the desired state was reached, and a sheet for encapsulating optical semiconductor devices consisting of an adhesive layer with an average thickness of 100 μm was fabricated.

[0126] [Table 1]

[0127] <Rating> The optoelectronic semiconductor device encapsulation sheets prepared in the examples and comparative examples were evaluated as follows. The results are shown in Table 2.

[0128] (1) Hayes The release liner (product name "MRE38") was peeled off the optoelectronic device encapsulation sheets obtained in the examples and comparative examples, and the exposed surface was bonded to a glass plate. The optoelectronic device encapsulation sheets from Example and Comparative Example 1 were heat-cured at 150°C for 1 hour and used as evaluation samples. Next, the release liner (product name "MRF38") was peeled off, and the sheet was placed in a haze meter (product name "HN-150N", manufactured by Murakami Color Science Laboratory Co., Ltd.) so that light was incident from the exposed surface, and the haze was measured according to the method specified in JIS K7136.

[0129] (2) Total light transmittance The release liner (product name "MRE38") was peeled off the optoelectronic device encapsulation sheets obtained in the examples and comparative examples, and the exposed surface was bonded to a glass plate. The optoelectronic device encapsulation sheets from Example and Comparative Example 1 were heat-cured at 150°C for 1 hour and used as evaluation samples. Next, the release liner (product name "MRF38") was peeled off, and the samples were placed in a haze meter (product name "HN-150N", manufactured by Murakami Color Science Laboratory Co., Ltd.) so that light was incident from the exposed surface, and the total light transmittance was measured according to the method specified in JIS K7361.

[0130] (3) Viscosity at sealing temperature The release liners were peeled off from the optoelectronic device encapsulation sheets obtained in the examples and comparative examples, and the laminates were stacked to create a laminate with a thickness of approximately 300 μm. This laminate was then punched out into a cylindrical shape with a diameter of φ8 mm to serve as a measurement sample. The above measurement sample was measured using a rheometer (product name "HAAKE MARS iQ Air", manufactured by ThermoSCIENTIFIC) in shear mode, at a frequency of 1 Hz, in the range of 80 to 150°C at a heating rate of 5°C / min, and the viscosity at the encapsulation temperature of 100°C was read.

[0131] (4) Tensile storage modulus E' at room temperature after curing The release liner was peeled off from the photoelectronic semiconductor device encapsulation sheets obtained in Example and Comparative Example 1, and the sheets were stacked at 90°C until a thickness of 200 μm was achieved. These sheets were then cut into strips measuring 5 mm in width and 50 mm in length using a utility knife. The strips were heated at 150°C for 1 hour to cure them and used as measurement samples. The dynamic storage modulus of the above measurement samples was measured using a solid viscoelasticity analyzer (product name "RSA-G2", manufactured by TA Instruments) in tensile mode, at a frequency of 10 Hz and a chuck distance of 20 mm, in the range of -10 to 150°C at a heating rate of 10°C / min. The tensile storage modulus E' at 25°C was then calculated.

[0132] (5) Missing The release liner (product name "MRE38") of the optoelectronic device encapsulation sheet obtained in the examples and comparative examples was peeled off, and the exposed surface was placed on a pattern wafer measuring 10 μm in height, 40 μm in length, and 20 μm in width. The pattern wafer was then encapsulated using a vacuum press at 100°C × 0.3 MPa × 600 seconds. The optoelectronic device encapsulation sheets from Example and Comparative Example 1 were heat-cured at 150°C × 1h to obtain evaluation samples. The evaluation samples after encapsulation were diced into 10 mm × 10 mm pieces, and the amount of chipping was observed and evaluated based on the following evaluation criteria. <Evaluation Criteria> ○: The amount of resin chipping from the wafer edge into the resin interior is less than 10 μm. ×: The amount of resin chipping from the wafer edge into the resin interior is 10 μm or more.

[0133] (6) Brightness variation The release liner (product name "MRE38") was peeled off the optoelectronic device encapsulation sheets obtained in the examples and comparative examples, and the exposed surface was bonded to a glass plate. The optoelectronic device encapsulation sheets from Example and Comparative Example 1 were heat-cured at 150°C for 1 hour and used as evaluation samples. An LED lamp (product name "LK-3PG," manufactured by EK Japan Co., Ltd.) was placed at the top of the screen to a height of 2.4 cm. The glass plate side of the central part of the evaluation sample was placed in close contact with the LED lamp. A battery box (product name "AP-180," manufactured by EK Japan Co., Ltd.) was connected to the LED lamp to turn it on, and the diameter of the circular image projected onto the screen was measured. Brightness variation was evaluated according to the evaluation criteria below. <Evaluation Criteria> ○: Diameter exceeds 2cm ×: Diameter less than 2cm

[0134] (7) Implantability The method for evaluating embedding performance will be explained with reference to Figures 5 and 6. Figure 6 shows a plan view of the dummy element used for evaluation. The V-V' cross section in Figure 6 corresponds to the cross section of the dummy element in Figure 5. An evaluation sample 13 with a thickness of 200 μm was prepared by peeling off the release liners from both sides of the optoelectronic semiconductor element encapsulation sheet obtained in the examples and comparative examples and laminating them. Separately, a glass plate 12 and a dummy element 9 mounted on one side of the substrate 91 via a plurality of cylindrical dummy bumps 92 were prepared. The size of each dummy element 9 was 1 mm × 1 mm × 200 μm thick. The height of the dummy bump 92 in the thickness direction was 20 μm. A semiconductor sample 11 was prepared by placing the evaluation sample 13 on the dummy element 9. Then, the glass plate 12 and the evaluation sample 13 of the semiconductor sample 11 were sandwiched between hot plates, and the dummy element 9 was encapsulated in a vacuum press at 100°C × 0.3 MPa × 600 seconds. Then, after sealing the dummy bump 92 and glass plate 12 in the dummy element 9, the degree to which the resin from the evaluation sample 13 penetrated between the substrate 91 and the glass plate 12 was observed, and the embedding ability was evaluated based on the following evaluation criteria. <Evaluation Criteria> ◎: Resin intrusion from the edge of dummy element 9 is 0.3 mm or more at most. ○: The maximum resin penetration from the edge of dummy element 9 is 0.2 mm or more but less than 0.3 mm. △: The maximum resin penetration from the edge of dummy element 9 is 0.1 mm or more but less than 0.2 mm. ×: The maximum resin penetration from the edge of dummy element 9 is less than 0.1 mm.

[0135] [Table 2]

[0136] As shown in Table 2, the optoelectronic device encapsulation sheet in the examples was found to have suppressed brightness variation and good embedding properties, and to be able to sufficiently fill the void between the optoelectronic device and the substrate. On the other hand, when light-diffusing fine particles were not included (Comparative Example 1), brightness variation was not suppressed. Furthermore, when an adhesive layer was used instead of a thermosetting resin layer as the optoelectronic device encapsulation sheet (Comparative Example 2), the embedding properties were insufficient, and it was determined that the void between the optoelectronic device and the substrate could not be sufficiently filled.

[0137] The following describes variations of the invention relating to this disclosure. [Note 1] A sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, The sheet comprises a sealing resin layer which includes at least a thermosetting resin layer containing light-diffusing fine particles, The thermosetting resin layer is a layer that comes into contact with the optical semiconductor element when the optical semiconductor element is sealed, in a sheet for encapsulating an optical semiconductor element. [Note 2] The thermosetting resin layer has a viscosity of 30,000 Pa·s or less at the sealing temperature, as described in Note 1, for use as a sheet for encapsulating optical semiconductor devices. [Note 3] The thermosetting resin layer has a room-temperature modulus E' of 500 to 6000 MPa after curing, and is a sheet for encapsulating optical semiconductor devices as described in Note 1 or 2. [Note 4] The thickness of the thermosetting resin layer is 10 to 200 μm, a sheet for encapsulating optical semiconductor devices as described in any one of Notes 1 to 3. [Note 5] The photo-semiconductor element encapsulation sheet according to any one of Notes 1 to 4, wherein the surface of the encapsulation resin layer opposite to the side in contact with the photo-semiconductor element has an anti-glare and / or anti-reflective layer. [Appendix 6] An optoelectronic device comprising a substrate, an optoelectronic semiconductor element disposed on the substrate, and an optoelectronic semiconductor element encapsulation sheet or a cured product thereof as described in any one of Appendices 1 to 5, for encapsulating the optoelectronic semiconductor element. [Explanation of Symbols]

[0138] 1. Sheet for encapsulating optical semiconductor devices 2 Sealing resin layer 21 Thermosetting resin layer 22 Non-colored resin layer 3. Peel-off liner 4 Functional Layers 5 circuit boards 6. Optoelectronic semiconductor devices 7 Cured sealing layer 71 Cured resin layer 8 Colored layer 9 Dummy elements 91 circuit board 92 Dummy Bump 10 Optoelectronic devices 11 Semiconductor Samples 12 glass plates 13 Evaluation Samples

Claims

1. A sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, The sheet comprises a sealing resin layer which includes at least a thermosetting resin layer containing light-diffusing fine particles, The thermosetting resin layer is a layer that comes into contact with the optical semiconductor element when the optical semiconductor element is sealed, in a sheet for encapsulating an optical semiconductor element.

2. The sheet for encapsulating an optical semiconductor device according to claim 1, wherein the thermosetting resin layer has a viscosity of 30,000 Pa·s or less at the sealing temperature.

3. The sheet for encapsulating an optical semiconductor device according to claim 1 or 2, wherein the thermosetting resin layer has a room-temperature modulus E' of 500 to 6000 MPa after curing.

4. The sheet for encapsulating optical semiconductor elements according to claim 1 or 2, wherein the thickness of the thermosetting resin layer is 10 to 200 μm.

5. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, wherein the surface of the encapsulating resin layer opposite to the side in contact with the optical semiconductor element is provided with a layer having anti-glare and / or anti-reflective properties.

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

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