Optical semiconductor element sealing sheet and optical semiconductor device

Abstract

To provide an optical semiconductor element sealing sheet that excels in optical characteristics, optical semiconductor element sealing properties, and workability during tiling, and is less likely to cause damage to the sheet when separating adjacent optical semiconductor devices.SOLUTION: An optical semiconductor element sealing sheet 1 is a sheet for sealing one or more optical semiconductor elements 6 arranged on a substrate 5. The optical semiconductor element sealing sheet 1 comprises a sealing resin layer 2 that includes at least a thermosetting adhesive layer 21 containing a coloring agent and a light diffusing agent. The thermosetting adhesive layer 21 is a layer that comes into contact with the optical semiconductor element 6 when the optical semiconductor element 6 is sealed with the optical semiconductor element sealing sheet 1. After curing of the sealing resin layer 2, the optical semiconductor element sealing sheet 1 has a light transmittance of 9 to 73% at a wavelength of 600 nm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sheet for encapsulating an optoelectronic device and an optoelectronic device. More specifically, the present invention relates to a sheet suitable for use in encapsulating an optoelectronic device, and an optoelectronic device having a structure in which the optoelectronic device is encapsulated with the sheet.

Background Art

[0002] In self-emitting display devices such as mini / micro light emitting diode displays (Mini / Micro Light Emitting Diode Display), a plurality of LEDs are arranged on a substrate, and those having a structure in which the plurality of LEDs are encapsulated with an encapsulating resin are known. As a method of collectively encapsulating the plurality of LEDs using the encapsulating resin, a method is known in which a liquid resin is poured into a region where the plurality of LEDs are arranged, the plurality of LEDs are buried, and then the liquid resin is cured by heat or ultraviolet irradiation.

[0003] However, in the method of encapsulating an optoelectronic device such as an LED using a liquid resin, there is a problem that the handleability is poor, such as dripping when applying the liquid resin and the liquid resin adhering to an unintended region. On the other hand, instead of using a liquid resin, by adopting the form of an encapsulating sheet provided with an encapsulating layer for encapsulating an optoelectronic device, it is possible to easily encapsulate the optoelectronic device in a simple process and in a short time.

[0004] In an image display device including a self-emitting display device, wirings of metal oxides such as metal and ITO (metal wirings) are arranged on the substrate of the display panel. Such a display device has a problem that, for example, at the time of turning off the light, light is reflected by the metal wiring or the like, and the appearance of the screen is poor and the design property is inferior. For this reason, a technique using an antireflection layer for preventing reflection by the metal wiring is adopted as an encapsulating material for encapsulating an optoelectronic device.

[0005] In addition, in a display using a self-luminous display device, there has been a problem that unevenness in brightness (luminance unevenness, luminance variation) occurs due to the light source of the optical semiconductor element. When luminance variation occurs, a phenomenon called "color shift" occurs, in which the color tone changes depending on whether the display is viewed from the front or from an oblique viewing angle. For this reason, the encapsulant is required to have excellent antireflection properties, little luminance variation, and excellent optical properties such as high luminance.

[0006] By the way, with the increase in image quality such as 4K and 8K, the demand for larger-screen image display devices is growing. In addition, the use of larger-screen image display devices for advertising displays and signage such as billboards in outdoor areas and public facilities is also progressing. However, when manufacturing a larger-screen image display device, there is a problem that the yield decreases and the manufacturing cost increases. In order to manufacture a larger-screen image display device at a lower cost, a tiling display in which a plurality of optical semiconductor devices such as image display devices are arranged side by side in a tile shape is being studied.

[0007] Patent Document 1 discloses a tiling display device in which a plurality of display devices each including a light-emitting diode substrate with an encapsulant that encapsulates a light-emitting diode with an encapsulant containing a thermoplastic resin are arranged in parallel.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] Here, the above-mentioned sealing sheet is excellent in the sealing property of the optical semiconductor element, and it is important to be excellent in the adhesion to the optical semiconductor element and the substrate provided with the optical semiconductor element in order to sufficiently seal the optical semiconductor element. However, when an adhesive layer using a thermoplastic resin is used as a sealing member as described in Patent Document 1, the adhesiveness is high, and when a plurality of optical semiconductor devices are arranged in a tile shape, that is, during tiling, the optical semiconductor device is difficult to separate from the hand or the jig, and there is a problem of poor workability.

[0010] Further, when misalignment or the like occurs between adjacent optical semiconductor devices during tiling or when rearrangement is necessary, position correction is performed. In order to perform position correction, it is necessary to temporarily separate adjacent optical semiconductor devices. However, when separating, the sealing sheet in one optical semiconductor device and the sealing sheet in the other adjacent optical semiconductor device may adhere to each other and pull, and a defect may occur in the sealing sheet in one optical semiconductor device. A sealing sheet excellent in adhesion to an optical semiconductor element and a substrate is particularly likely to cause such a problem.

[0011] The present invention has been conceived under such circumstances, and an object thereof is to provide an optical semiconductor element sealing sheet that is excellent in optical characteristics, the sealing property of the optical semiconductor element, and workability during tiling, and in which sheet defects are less likely to occur when adjacent optical semiconductor devices are separated from each other.

Means for Solving the Problems

[0012] As a result of intensive studies to achieve the above object, the present inventors have found that according to a specific sealing sheet, it is excellent in optical characteristics, the sealing property of the optical semiconductor element, and workability during tiling, and sheet defects are less likely to occur when adjacent optical semiconductor devices are separated from each other. The present invention has been completed based on these findings.

[0013] That is, the present invention is a sheet for sealing one or more optical semiconductor elements disposed on a substrate, The sheet includes at least a resin layer for sealing including a thermosetting adhesive layer containing a colorant and a light diffusing agent. The thermosetting adhesive layer is a layer that contacts the optical semiconductor element when the optical semiconductor element is sealed. Provided is an optical semiconductor element sealing sheet in which the light transmittance of the sheet at a wavelength of 600 nm after curing of the resin layer for sealing is 9 to 73%.

[0014] The thickness of the thermosetting adhesive layer is preferably 10 to 150 μm.

[0015] The elastic modulus E' at normal temperature before curing of the thermosetting adhesive layer is preferably 500 to 4000 MPa.

[0016] The elastic modulus E' at normal temperature after curing of the thermosetting adhesive layer is preferably 500 to 4000 MPa.

[0017] The haze value of the sheet after curing of the resin layer for sealing is preferably 30% or more.

[0018] In the state where the optical semiconductor element is sealed, the distance from the optical semiconductor element to the thermosetting adhesive layer is preferably 0 to 20 μm in the optical semiconductor element sealing sheet.

[0019] The surface of the resin layer for sealing on the side opposite to the side in contact with the optical semiconductor element may be provided with a layer having antiglare properties and / or antireflection properties.

[0020] The present invention also provides an optical semiconductor device including a substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element sealing sheet or a cured product thereof for sealing the optical semiconductor element.

Effects of the Invention

[0021] According to the sheet for encapsulating an optical semiconductor element of the present invention, it is excellent in optical characteristics, the sealing property of the optical semiconductor element, and workability during tiling, and it is difficult for the sheet to be damaged when separating adjacent optical semiconductor devices. For this reason, after tiling the optical semiconductor devices, when there is a misalignment or rearrangement is required between adjacent optical semiconductor devices while having excellent optical characteristics, it is possible to easily correct the position without problems, reduce the loss of the optical semiconductor devices, and manufacture a display with good appearance economically and excellently.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0023] [Sheet for Encapsulating Optical Semiconductor Element] The sheet for encapsulating an optical semiconductor device of the present invention includes at least an encapsulating resin layer containing a thermosetting adhesive layer including a colorant and a light diffusing agent. In the present specification, the sheet for encapsulating an optical semiconductor device refers to a sheet for encapsulating one or more optical semiconductor devices disposed on a substrate with the encapsulating resin layer. Further, in the present specification, "encapsulating an optical semiconductor device" means embedding at least a part of the optical semiconductor device in the encapsulating resin layer or following and covering it with the above encapsulating resin layer. The above encapsulating resin layer has flexibility that enables at least a part of the optical semiconductor device to be embedded or to follow and cover it with the above encapsulating resin layer. Further, in the present specification, the thermosetting adhesive layer containing the above colorant and light diffusing agent may be referred to as "the thermosetting adhesive layer of the present invention".

[0024] <Encapsulating resin layer> The above encapsulating resin layer includes at least the thermosetting adhesive layer of the present invention. The above encapsulating resin layer may include other layers other than the thermosetting adhesive layer of the present invention. Each layer constituting the above encapsulating resin layer may be a single layer in the above encapsulating resin layer, or may be a multi-layer having the same or different compositions. When multiple layers of the thermosetting adhesive layer of the present invention are included, the above multi-layers may be laminated in contact with each other, or may be laminated separately (for example, two thermosetting adhesive layers of the present invention are laminated via another layer).

[0025] In the resin layer for sealing, the layer that comes into contact with the optical semiconductor element when the optical semiconductor element is sealed (that is, the layer closest to the optical semiconductor element side in the resin layer for sealing) is the thermosetting adhesive layer of the present invention. When the layer in contact with the optical semiconductor element is the thermosetting adhesive layer of the present invention, it has excellent workability before thermosetting and exhibits adhesiveness to the optical semiconductor element and the substrate after thermosetting. When the resin layer for sealing contains multiple layers of the thermosetting adhesive layer of the present invention, at least one thermosetting adhesive layer of the present invention may be located at the position closest to the optical semiconductor element side in the resin layer for sealing. It is preferable that all layers in the resin layer for sealing are adhesive layers having thermosetting properties (thermosetting adhesive layers). In this specification, an "adhesive layer" is different from a pressure-sensitive adhesive layer, and does not have tackiness or adhesiveness on the surface, or has extremely low tackiness or adhesiveness, and has curability and adheres to the adherend by curing.

[0026] (Thermosetting Adhesive Layer of the Present Invention) The thermosetting adhesive layer of the present invention contains at least a colorant. The thermosetting adhesive layer of the present invention is preferably a layer for the purpose of preventing reflection of light by metal wiring or the like provided on a substrate in an image display device. The colorant may be a dye or a pigment as long as it can be dissolved or dispersed in the thermosetting adhesive layer of the present invention. Dyes are preferable because low haze can be achieved even with a small amount of addition, and they do not have sedimentation properties like pigments and are easily distributed uniformly. Pigments are also preferable because high color expression can be achieved even with a small amount of addition. When a pigment is used as the colorant, it is preferably one with low conductivity or no conductivity. The colorant and the light diffusing agent may be used alone or in combination of two or more.

[0027] As the above coloring agent, a black coloring agent is preferred. As the above black coloring agent, known or commonly used coloring agents (pigments, dyes, etc.) for exhibiting black color can be used. 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 complex, anthraquinone-based coloring agent, zirconium nitride, etc. can be mentioned. Further, a coloring agent that functions as a black coloring agent by combining coloring agents that exhibit colors other than black may also be used.

[0028] When the thermosetting adhesive layer of the present invention is a radiation-curable resin layer, the above coloring agent preferably absorbs visible light and has permeability to light having a wavelength at which the above radiation-curable resin layer can be cured.

[0029] From the viewpoint of imparting an appropriate antireflection ability to the image display device, the content ratio of the coloring agent in the thermosetting adhesive layer of the present invention is preferably 0.03% by mass or more, more preferably 0.08% by mass or more, based on the total amount (100% by mass) of the thermosetting adhesive layer of the present invention. Further, the content ratio of the above coloring agent is, for example, 2% by mass or less, preferably 1% by mass or less, more preferably 0.6% by mass or less. The above content ratio may be appropriately set according to the type of the coloring agent, the color tone and light transmittance of the image display device, etc. The coloring agent may be added to the composition as a solution or dispersion obtained by dissolving or dispersing it in an appropriate solvent.

[0030] The thermosetting adhesive layer of the present invention contains a light diffusing agent and is a layer having a function of diffusing light. The thermosetting adhesive layer of the present invention is preferably a resin layer composed of a resin. The thermosetting adhesive layer of the present invention preferably contains a light diffusing agent dispersed in the resin layer. By having the thermosetting adhesive layer of the present invention in the above-mentioned resin layer for sealing, the light emitted from the optical semiconductor element diffuses in the diffusion functional layer, and for example, the light emitted from the side surface of the optical semiconductor element is emitted in the front direction of the image display device, improving the front luminance of the image display device. As for the above-mentioned light diffusing agent, only one kind may be used, or two or more kinds may be used.

[0031] The above-mentioned light diffusing agent is preferably light diffusing fine particles. The above-mentioned light diffusing fine particles have an appropriate refractive index difference from the resin constituting the thermosetting adhesive layer of the present invention and impart diffusion performance to the thermosetting adhesive layer of the present invention. Examples of the light diffusing fine particles include inorganic fine particles and polymer fine particles. Examples of the material of the inorganic fine particles include silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, metal oxides, and the like. Examples of the material of the polymer fine particles include silicone resin, acrylic resin (including polymethacrylate resins such as polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, epoxy resin, and the like.

[0032] As the above-mentioned polymer fine particles, fine particles composed of silicone resin are preferable. Also, as the above-mentioned inorganic fine particles, fine particles composed of metal oxide are preferable. As the above-mentioned metal oxide, titanium oxide and barium titanate are preferable, and titanium oxide is more preferable. By having such a configuration, the light diffusing property of the thermosetting adhesive layer of the present invention is more excellent, and the luminance variation is more suppressed.

[0033] The shape of the above-mentioned light diffusing fine particles is not particularly limited, and may be, for example, spherical, flat, or irregular.

[0034] From the perspective of imparting appropriate light diffusion performance, the average particle diameter of the above light-diffusing fine particles is preferably 0.1 μm or more, more preferably 0.15 μm or more, still more preferably 0.2 μm or more, and particularly preferably 0.25 μm or more. Also, from the perspective of preventing the haze value from becoming too high and displaying a high-definition image, the average particle diameter of the above light-diffusing fine particles is preferably 12 μm or less, more preferably 10 μm or less, and still more preferably 8 μm or less. The average particle diameter can be measured using, for example, a Coulter counter.

[0035] The refractive index of the above light diffusing agent is preferably 1.2 to 5, more preferably 1.25 to 4.5, still more preferably 1.3 to 4, and particularly preferably 1.35 to 3.

[0036] From the perspective of more efficiently reducing the luminance variation of the image display device, the absolute value of the refractive index difference between the above light diffusing agent and the resin constituting the thermosetting adhesive layer of the present invention (for example, the resin layer excluding various additives such as a colorant and a light diffusing agent in the thermosetting adhesive layer of the present invention) is preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, and particularly preferably 0.03 or more, and may be 0.04 or more, or 0.05 or more. Also, from the perspective of preventing the haze value from becoming too high and displaying a high-definition image, the absolute value of the refractive index difference between the light diffusing agent and the resin is preferably 5 or less, more preferably 4 or less, and still more preferably 3 or less.

[0037] From the perspective of imparting appropriate light diffusion performance to the sheet for encapsulating an optical semiconductor element, the content of the above light diffusing agent in the thermosetting adhesive layer of the present invention is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more with respect to 100 parts by mass of the resin constituting the thermosetting adhesive layer of the present invention. Also, from the perspective of preventing the haze value from becoming too high and displaying a high-definition image, the content of the light diffusing agent is preferably 100 parts by mass or less, more preferably 70 parts by mass or less with respect to 100 parts by mass of the resin constituting the thermosetting adhesive layer of the present invention.

[0038] When the thermosetting adhesive layer of the present invention is the above resin layer, examples of the resin constituting the resin layer include known or commonly used resins, such as acrylic resins, urethane acrylate resins, urethane resins, rubber resins, epoxy resins, epoxy acrylate resins, oxetane resins, silicone resins, silicone acrylic resins, polyester resins, polyether resins (such as polyvinyl ether), polyamide resins, fluorine resins, vinyl acetate / vinyl chloride copolymers, modified polyolefins, and the like. Only one kind of the above resin may be used, or two or more kinds may be used. Among them, acrylic resins are preferred.

[0039] The above 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) as a structural unit of the resin (polymer). Only one kind of the above acrylic resin may be used, or two or more kinds may be used.

[0040] The above acrylic resin preferably contains the largest mass ratio of the structural unit derived from (meth)acrylate. In this specification, "(meth)acryl" means "acryl" and / or "methacryl" (either one or both of "acryl" and "methacryl"), and the same applies to others.

[0041] The thermosetting adhesive layer of the present invention preferably contains a thermosetting resin. As the above thermosetting resin, known or commonly used resins having thermosetting properties can be used, for example, resins having thermosetting functional groups. Among them, as the above thermosetting resin, an acrylic resin having a thermosetting functional group (a thermosetting functional group-containing acrylic resin) is preferred.

[0042] Examples of the above-mentioned thermosetting functional groups include epoxy group-containing groups such as glycidyl groups, carboxy groups, hydroxy groups, isocyanate groups, aziridyl groups, etc. Among them, epoxy group-containing groups are preferred, and glycidyl groups are more preferred. That is, as the acrylic resin having a thermosetting functional group, glycidyl group-containing acrylic resin is particularly preferred. The above-mentioned thermosetting functional group may have only one kind or two or more kinds.

[0043] The above-mentioned 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 (thermosetting functional group-containing acrylic monomer). Examples of the monomer having the above-mentioned thermosetting functional group include epoxy group-containing (meth)acrylic acid esters such as glycidyl group-containing (meth)acrylic acid esters, carboxy group-containing monomers, acid anhydride group-containing monomers, hydroxy group-containing (meth)acrylic acid esters, and the like.

[0044] Examples of the above-mentioned glycidyl group-containing (meth)acrylic acid ester include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and the like.

[0045] Examples of the above-mentioned carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. Examples of the above-mentioned acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, and the like.

[0046] 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.

[0047] Among the thermosetting functional group-containing acrylic monomers, 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 a structural unit derived from an epoxy group-containing (meth)acrylic acid ester, the epoxy group acts as a thermosetting functional group, and even when no curing agent is blended, the reaction of the epoxy group proceeds by thermosetting, and the thermosetting adhesive layer of the present invention cures. Therefore, the thermosetting adhesive layer of the present invention has appropriate flexibility after thermosetting and is excellent in the sealing property of the optical semiconductor element.

[0048] The content ratio of the structural unit derived from the epoxy group-containing (meth)acrylic acid ester is preferably 5 to 50% by mass, more preferably 6 to 45% by mass, based on the total amount (100% by mass) of all the structural units of the acrylic resin in the thermosetting adhesive layer of the present invention. When the content ratio is within the above range, the thermosetting adhesive layer of the present invention has appropriate flexibility after thermosetting and is excellent in the sealing property of the optical semiconductor element.

[0049] The thermosetting functional group-containing acrylic resin may contain a structural unit derived from other monomers other than the thermosetting functional group-containing monomer. Examples of the other monomers include other (meth)acrylic acid esters other than the thermosetting functional group-containing acrylic monomers. Only one kind of the other monomers may be used, or two or more kinds may be used.

[0050] 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 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 alone or in combination of two or more.

[0051] Examples of the above-mentioned (meth)acrylic acid alkyl 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, 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, eicosyl (meth)acrylate, and the like.

[0052] Among the above (meth)acrylic acid alkyl esters, those having a linear or branched aliphatic hydrocarbon group with 1 to 20 carbon atoms (preferably 1 to 14, more preferably 2 to 10, still more preferably 2 to 8) are preferred. When the number of carbon atoms is within the above range, the flexibility of the above thermosetting group-containing acrylic resin during thermosetting is more likely to be appropriate, and the embedding property is further improved.

[0053] Examples of the (meth)acrylic acid ester having the above 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, cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; (meth)acrylic acid esters having an aliphatic hydrocarbon ring of three or more rings such as dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, and the like.

[0054] Examples of the (meth)acrylic acid ester having the above aromatic hydrocarbon group include phenyl (meth)acrylate, benzyl (meth)acrylate, and the like.

[0055] Examples of the hydrocarbon group-containing (meth)acrylic acid ester 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, 2-methoxybutyl ester of (meth)acrylic acid, and the like.

[0056] Examples of the other monomer components further 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-hydroxyethylacryloyl 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.

[0057] In order to form a crosslinked structure in the polymer skeleton of the above thermosetting functional group-containing acrylic resin, it may contain a structural unit derived from a polyfunctional (meth)acrylate copolymerizable with the monomer components constituting the acrylic resin. Examples of the 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, dipentaerythritol hexa(meth)acrylate, and the like. Only one kind of the polyfunctional (meth)acrylate may be used, or two or more kinds may be used.

[0058] The above-mentioned acrylic resin containing a thermosetting functional group is obtained by polymerizing the various monomer components described above. The polymerization method is not particularly limited, and examples thereof include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by irradiation with active energy rays (active energy ray polymerization method). Further, the obtained acrylic resin may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

[0059] From the viewpoint of having a certain degree of hardness after curing of the thermosetting adhesive layer of the present invention and reducing the adhesion between the side surfaces of the optical semiconductor device, the weight average molecular weight of the above-mentioned epoxy group-containing acrylic resin is preferably 2,000 to 400,000, more preferably 30,000 to 300,000. When the above weight average molecular weight is within the above range, the embedability of the optical semiconductor element is excellent. The above weight average molecular weight refers to a value measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0060] The content ratio of the above-mentioned epoxy group-containing acrylic resin is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, based on the total amount (100% by mass) of the resin in the thermosetting adhesive layer of the present invention. When the above content ratio is 20% by mass or more, the embedability of the optical semiconductor element is excellent. Further, the above content ratio is preferably 99% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0061] The thermosetting adhesive layer of the present invention preferably contains a component having a functional group (second functional group) capable of reacting with heat with the thermosetting functional group (first functional group) in the above-mentioned acrylic resin containing a thermosetting functional group. The above second functional group is also a thermosetting functional group. In this case, the curing of the thermosetting adhesive layer of the present invention is further promoted by the reaction between the first functional group and the second functional group when the resin layer is heated.

[0062] 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 the second functional group. Only one kind of the component having the second functional group may be used, or two or more kinds may be used.

[0063] Examples of the combination 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, and the like. Only one kind of the combination may be used, or two or more kinds may be used.

[0064] When the epoxy group-containing acrylic resin is included, the thermosetting adhesive layer of the present invention preferably includes, as the component having the second functional group, a component having a functional group reactive with an epoxy group. Examples of the functional group reactive with an epoxy group include a carboxy group, an aziridyl group, a hydroxy group, and the like. Among them, a carboxy group and a hydroxy group are preferable. From the viewpoint of high acidity and excellent reactivity with an epoxy group, a silanol group is preferable as the hydroxy group.

[0065] The component having the carboxy group is preferably the resin, more preferably a carboxy group-containing acrylic resin. When the carboxy group-containing acrylic resin is contained, the reaction between the epoxy group and the carboxy group in the epoxy group-containing acrylic resin proceeds more easily even when no curing agent is blended, and the sealing property of the optical semiconductor element is more excellent. In addition, the surface scratch resistance is even more excellent.

[0066] The above carboxy group-containing acrylic resin preferably contains a structural unit derived from a carboxy group-containing monomer, and more preferably contains a structural unit derived from a carboxy group-containing acrylic monomer. Examples of the above carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like.

[0067] The content ratio of the structural unit derived from the above carboxy group-containing acrylic monomer is preferably 1 to 50% by mass, more preferably 10 to 40% by mass, based on the total amount (100% by mass) of all the structural units of the above carboxy group-containing acrylic resin. When the above content ratio is within the above range, the thermosetting adhesive layer of the present invention has appropriate flexibility after thermosetting and is excellent in the sealing property of the optical semiconductor element.

[0068] The above carboxy group-containing acrylic resin may contain a structural unit derived from other monomers other than the above carboxy group-containing monomer. Examples of the above other monomers include other (meth)acrylic acid esters other than the above thermosetting functional group-containing acrylic monomers, the above polar group-containing monomers, the above polyfunctional monomers, and the like. Only one kind of the above other monomers may be used, or two or more kinds may be used.

[0069] Examples of the above other (meth)acrylic acid esters include hydrocarbon group-containing (meth)acrylic acid esters which may have the above alkoxy group. Among the (meth)acrylic acid alkyl esters in the hydrocarbon group-containing (meth)acrylic acid esters which may have the above 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, still more preferably 1 to 8) are preferable. When the number of carbon atoms is within the above range, it is easier to make the flexibility of the above thermosetting group-containing acrylic resin more appropriate and the embedding property is further improved.

[0070] In order to appropriately exhibit basic properties such as adhesion to the above-mentioned optical semiconductor element in the thermosetting adhesive layer of the present invention, the ratio of the hydrocarbon group-containing (meth)acrylate ester which may have an alkoxy group to the total amount (100% by mass) of all constitutional units of the above-mentioned carboxyl group-containing acrylic resin is preferably 50 to 95% by mass, more preferably 60 to 90% by mass.

[0071] The weight average molecular weight of the above-mentioned carboxyl group-containing acrylic resin is preferably 1000 to 200000, more preferably 3000 to 100000. When the weight average molecular weight is within the above range, the sealing property of the optical semiconductor element is more excellent. The weight average molecular weight refers to a value measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0072] When the above-mentioned carboxyl group-containing acrylic resin is included, the content ratio of the above-mentioned carboxyl group-containing acrylic resin is preferably 1 to 60% by mass, more preferably 10 to 50% by mass, still more preferably 15 to 45% by mass with respect to the total amount (100% by mass) of the resin in the thermosetting adhesive layer of the present invention. When the content ratio is within the above range, the thermosetting property of the thermosetting adhesive layer of the present invention is more excellent. Also, the surface scratch resistance is more excellent.

[0073] The thermosetting adhesive layer of the present invention may contain other components other than the above-mentioned components as long as the effects of the present invention are not impaired. Examples of the other components include thermoplastic resins, coupling agents such as silane coupling agents, crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), oligomers, anti-aging agents, fillers (organic fillers, inorganic particles, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, granular materials, foil materials, and the like. Each of the above-mentioned other components may be used alone or in combination of two or more.

[0074] The content ratio of the resin in the thermosetting adhesive layer of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more with respect to the total amount (100% by mass) of the thermosetting adhesive layer of the present invention. The above content ratio is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass or less. Further, the content ratio of the acrylic resin is preferably within the above range, the content ratio of the thermosetting resin is preferably within the above range, and the thermosetting functional group-containing acrylic resin is preferably within the above range.

[0075] The thermosetting adhesive layer of the present invention can be formed, for example, using a thermosetting resin composition (adhesive composition). The thermosetting adhesive layer of the present invention can be produced, for example, by applying the above adhesive composition to the release-treated surface of a release liner or a substrate to form an adhesive composition layer, and then solidifying the adhesive composition layer by desolvation by heating or polymerization by radiation irradiation.

[0076] The elastic modulus G' at 130 °C before curing of the thermosetting adhesive layer of the present invention is preferably 0.5 to 10 kPa, more preferably 0.7 to 8 kPa, and still more preferably 1 to 6 kPa. When the elastic modulus G' is within the above range, the embedability or followability of the optical semiconductor element is excellent, and when the optical semiconductor element is sealed, the surface of the sealing sheet becomes flat and the appearance is good.

[0077] The elastic modulus E' at room temperature (25 °C) before curing of the thermosetting adhesive layer of the present invention is preferably 500 to 4000 MPa, more preferably 700 to 3000 MPa, and still more preferably 1000 to 2000 MPa. When the elastic modulus E' is within the above range, stickiness is further reduced and workability is excellent.

[0078] The elastic modulus E' at room temperature after curing of the thermosetting adhesive layer of the present invention is preferably 500 to 4000 MPa, more preferably 700 to 3000 MPa, and still more preferably 1000 to 2000 MPa. When the elastic modulus E' is within the above range, stickiness is further reduced and chipping is less likely to occur.

[0079] The ratio of the room temperature elastic modulus E' after curing to the room temperature elastic modulus E' before curing [room temperature elastic modulus E' after curing / room temperature elastic modulus E' before curing] of the thermosetting adhesive layer of the present invention is preferably 0.6 to 2.0, more preferably 0.8 to 1.5, and even more preferably 0.9 to 1.2. When the above ratio is within the above range, the change in hardness before and after curing is small, and the workability and scratch resistance are excellent.

[0080] The light transmittance at a wavelength of 600 nm after curing of the thermosetting adhesive layer of the present invention is 9% or more, preferably 10% or more, and more preferably 12% or more. When the above light transmittance is 9% or more, the luminance of the optical semiconductor device is good. The above light transmittance is 73% or less, preferably 70% or less, and more preferably 66% or less. When the above light transmittance is 73% or less, the antireflection function and contrast of metal wiring and the like in the optical semiconductor device are excellent.

[0081] From the viewpoint of efficiently reducing the luminance variation, the haze value of the thermosetting adhesive layer of the present invention is preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more. From the viewpoint of ensuring the front luminance and visibility when the optical semiconductor element is sealed, the haze value is preferably 99% or less, more preferably 90% or less, and even more preferably 85% or less. The above haze value may be any value before or after curing, but is preferably the value after curing.

[0082] The total light transmittance of the thermosetting adhesive layer of the present invention is not particularly limited, but from the viewpoint of ensuring light transmissibility, it is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, even more preferably 2% or more, even more preferably 2.5% or more, and particularly preferably 3% or more. The above total light transmittance is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less.

[0083] The above haze value and total light transmittance are each single-layer values and can be measured by the methods defined in JIS K7136 and JIS K7361-1, and can be controlled by the type and thickness of the thermosetting adhesive layer of the present invention, the type and blending amount of the colorant and light diffusing agent, etc.

[0084] The thickness of the thermosetting adhesive layer of the present invention (the thickness of the thermosetting adhesive layer of the present invention that is closest to the optical semiconductor element side in the above sealing resin layer) is preferably 10 to 150 μm, more preferably 20 to 100 μm. When the above thickness is 10 μm or more, the antireflection property is more excellent and the luminance variation can be more suppressed. When the above thickness is 150 μm or less, the luminance of the optical semiconductor device is more excellent.

[0085] (Non-diffusion functional layer) The above sealing resin layer may include, as the above other layer, a non-diffusion functional layer that does not aim to exhibit a function of diffusing light. Further, the above non-diffusion functional layer is a layer that does not aim to prevent reflection of light by metal wiring or the like. The above non-diffusion functional layer may be a colorless layer or may be slightly colored. The above non-diffusion functional layer may be transparent or non-transparent. The above non-diffusion functional layer is preferably a resin layer composed of resin. Examples of the resin constituting the above non-diffusion functional layer include those exemplified and described as the resins that the above thermosetting adhesive layer of the present invention may contain.

[0086] The content ratio of the colorant in the above non-diffusion functional layer is preferably less than 0.2% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.05% by mass, and may be less than 0.01% by mass or less than 0.005% by mass, based on the total amount (100% by mass) of the non-diffusion functional layer.

[0087] The haze value of the non-diffusing functional layer is not particularly limited, but from the viewpoint of achieving excellent luminance, it is preferably less than 30%, more preferably 10% or less, still more preferably 5% or less, particularly preferably 1% or less, and may be 0.5% or less. The lower limit of the haze value of the non-diffusing functional layer is not particularly limited. When the non-diffusing functional layer has curability, the haze value may be any value before or after curing, but is preferably the value after curing.

[0088] The total light transmittance of the non-diffusing functional layer is not particularly limited, but from the viewpoint of ensuring luminance, it is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, particularly preferably 90% or more. The upper limit value of the total light transmittance of the non-diffusing functional layer is not particularly limited, and may be less than 100%, may be 99.9% or less, or may be 99% or less. When the non-diffusing functional layer has curability, the total light transmittance may be any value before or after curing, but is preferably the value after curing.

[0089] The haze value and the total light transmittance of the non-diffusing functional layer are each a value of a single layer and can be measured by the methods defined in JIS K7136 and JIS K7361-1, and can be controlled by the type, thickness, etc. of the non-diffusing functional layer.

[0090] From the viewpoint of achieving excellent luminance of the image display device, the content of the colorant and / or light-diffusing fine particles in the non-diffusing functional layer is preferably less than 0.01 part by mass, more preferably less than 0.005 part by mass, based on 100 parts by mass of the resin constituting the non-diffusing functional layer.

[0091] The above-mentioned resin layer for sealing may have a single-layer structure composed of a single layer of the thermosetting adhesive layer of the present invention, or may have a laminated structure including the thermosetting adhesive layer of the present invention. Examples of the laminated structure of the above-mentioned resin layer for sealing include: a structure composed of two layers of the thermosetting adhesive layer of the present invention; a structure composed of two layers, one layer being the thermosetting adhesive layer of the present invention and the other layer being the above-mentioned other layer (for example, the above-mentioned non-diffusion functional layer) (regardless of the order); a structure composed of three layers, one layer being the thermosetting adhesive layer of the present invention and the other two layers being two layers selected from the thermosetting adhesive layer of the present invention and the above-mentioned other layer respectively (regardless of the order); a structure composed of four layers, one layer being the thermosetting adhesive layer of the present invention and the other three layers being three layers selected from the thermosetting adhesive layer of the present invention and the above-mentioned other layer respectively (regardless of the order). More specifically, for example, [the thermosetting adhesive layer of the present invention], [the thermosetting adhesive layer of the present invention / non-diffusion functional layer] (in the above order from the side of the optical semiconductor element), etc. can be mentioned.

[0092] (Base material part) In the sheet for sealing an optical semiconductor element of the present invention, the above-mentioned resin layer for sealing may be provided on at least one surface of the base material part. That is, the above-mentioned sheet for sealing a semiconductor element may include a base material part and the above-mentioned resin layer for sealing provided on at least one surface of the base material part. When the sheet for sealing an optical semiconductor element of the present invention includes the above-mentioned base material part, the side of the resin layer for sealing opposite to the side in contact with the optical semiconductor element is the side in contact with the base material part. When the base material part is provided on the side of the sheet for sealing an optical semiconductor element opposite to the optical semiconductor element side of the resin layer for sealing, the surface of the resin layer for sealing can be made flat, thereby making it less likely to cause irregular reflection of light, and improving the appearance of the optical semiconductor device both when it is turned off and when it is emitting light. In addition, by forming an anti-glare layer or an anti-reflection layer described later on the above-mentioned base material part, anti-glare properties and anti-reflection properties can be imparted to the optical semiconductor device. Further, in the sheet for sealing an optical semiconductor element, it serves as a support for the resin layer for sealing, and by including the above-mentioned base material part, the handleability of the sheet for sealing an optical semiconductor element is excellent. Note that the base material part does not necessarily have to be provided.

[0093] The above base material part may be a single layer, or may be a multi-layer with the same or different compositions, thicknesses, etc. When the above base material part is a multi-layer, each layer may be bonded together by other layers such as an adhesive layer. Note that the base material layer used for the base material part is the part that is attached to the adherend together with the above sealing resin layer, and a release liner that is peeled off when using (attaching) the optical semiconductor element sealing sheet, or a surface protection film that only protects the surface of the base material part is not included in the "base material part".

[0094] Examples of the base material layer constituting the above base material part include glass and plastic base materials (especially plastic films). Examples of the resin constituting the above plastic base material 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)acrylate (random, alternating) copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-propylene copolymer, cyclic olefin polymer, ethylene-butene copolymer, ethylene-hexene copolymer and other polyolefin resins; polyurethane; polyethylene terephthalate (PET), polyethylene naphthalate, polybutylene terephthalate (PBT) and other polyesters; polycarbonate; polyimide resin; polyetheretherketone; polyetherimide; polyamide such as aramid and wholly aromatic polyamide; polyphenyl sulfide; fluororesin; polyvinyl chloride; polyvinylidene chloride; cellulose resin such as triacetyl cellulose (TAC); silicone resin; acrylic resin such as polymethyl methacrylate (PMMA); polysulfone; polyarylate; polyvinyl acetate and the like. The above resins may be used alone or in combination of two or more. The above base material layer may be various optical films such as an antireflection (AR) film, a polarizing plate, and a retardation plate.

[0095] The thickness of the above 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 sheet for encapsulating the optoelectronic device are further improved. When the thickness is 300 μm or less, the sheet for encapsulating the optoelectronic device can be made thinner.

[0096] The surface of the above base material portion on the side provided with the above resin layer for encapsulation is, for the purpose of enhancing the adhesion, retention, etc. with the resin layer for encapsulation, for example, physical treatments such as corona discharge treatment, plasma treatment, sand mat processing treatment, ozone exposure treatment, flame exposure treatment, high voltage shock exposure treatment, ionization radiation treatment, etc.; chemical treatments such as chromic acid treatment, etc.; surface treatments such as easy adhesion treatment with a coating agent (primer) may be performed. The surface treatment for enhancing the adhesion is preferably performed on the entire surface of the base material portion on the side of the resin layer for encapsulation.

[0097] The thickness of the above base material portion is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of excellent functions as a support and scratch resistance of the surface. The thickness of the above base material portion is preferably 300 μm or less, more preferably 250 μm or less, from the viewpoint of more excellent transparency.

[0098] <Sheet for Encapsulating Optoelectronic Device> The sheet for encapsulating the optical semiconductor element may be provided with a layer having antiglare properties and / or antireflection properties. By having such a configuration, when the optical semiconductor element is encapsulated, gloss and light reflection can be suppressed, and the appearance can be made better. Examples of the layer having antiglare properties include an antiglare treatment layer. Examples of the layer having antireflection properties include an antireflection treatment layer. The antiglare treatment and the antireflection treatment can each be carried out by known or conventional methods. The layer having antiglare properties and the layer having antireflection properties may be the same layer or different layers from each other. The layer having antiglare properties and / or antireflection properties may have only one layer or two or more layers. The layer having antiglare properties and / or antireflection properties is preferably provided on the surface (preferably the front surface) of the sheet for encapsulating the optical semiconductor element, which is opposite to the side in contact with the optical semiconductor element of the sheet for encapsulating the optical semiconductor element, with respect to the encapsulating resin layer.

[0099] From the viewpoint of efficiently reducing luminance variation, the haze value of the sheet for encapsulating the optical semiconductor element is preferably 30% or more, more preferably 35% or more, and still more preferably 40% or more. The haze value may be any value before or after curing, but is preferably the value after curing.

[0100] The total light transmittance of the sheet for encapsulating the optical semiconductor element is not particularly limited, but from the viewpoint of ensuring light transmittance, it is preferably 0.5% or more, more preferably 1% or more, still more preferably 1.5% or more, still more preferably 2% or more, still more preferably 2.5% or more, and particularly preferably 3% or more. The total light transmittance is preferably 70% or less, more preferably 60% or less, and still more preferably 50% or less.

[0101] The haze value and the total light transmittance can each be measured by the methods defined in JIS K7136 and JIS K7361-1, and can be controlled by the lamination order, type, thickness, etc. of each layer constituting the encapsulating resin layer and the base material part.

[0102] When the sheet for encapsulating the optical semiconductor element is in a state where the optical semiconductor element is encapsulated, the distance from the optical semiconductor element to the thermosetting adhesive layer of the present invention (the thermosetting adhesive layer of the present invention closest to the optical semiconductor element side in the encapsulating resin layer) is preferably 0 to 20 μm, more preferably 0 to 10 μm. When the distance is within the above range, the antireflection property and brightness of the image display device are excellent.

[0103] The thickness of the sheet for encapsulating the optical semiconductor element is preferably 5 to 600 μm, more preferably 10 to 550 μm, still more preferably 30 to 500 μm, still more preferably 40 to 450 μm, and particularly preferably 50 to 400 μm, from the viewpoint of improving the antireflection function such as metal wiring and contrast and more efficiently reducing the color shift. Note that the release liner is not included in the above thickness.

[0104] The thickness of the encapsulating resin layer is, for example, 5 to 500 μm, preferably 10 to 400 μm, and more preferably 30 to 300 μm. When the thickness is 5 μm or more, the encapsulation property of the optical semiconductor element becomes better. When the thickness is 500 μm or less, the thickness of the optical semiconductor device becomes thinner.

[0105] [Release liner] The encapsulating resin layer may be formed on the release-treated surface of the release liner. When the encapsulating resin layer is formed on the release liner, the thermosetting adhesive layer of the present invention (the thermosetting adhesive layer of the present invention closest to the optical semiconductor element side in the encapsulating resin layer) of the encapsulating resin layer is on the side in contact with the release liner. When there is no base material portion, both surfaces of the encapsulating resin layer may be on the side in contact with the release liner. The release liner is used as a protective material for the sheet for encapsulating the optical semiconductor element and is peeled off when encapsulating the optical semiconductor element. Note that the release liner is not necessarily provided.

[0106] The above release liner is an element for covering and protecting the surface of the sheet for encapsulating an optical semiconductor element, and is peeled off from the sheet when the sheet for encapsulating an optical semiconductor element is bonded to a substrate on which the optical semiconductor element is disposed.

[0107] Examples of the above release liner include a polyethylene terephthalate (PET) film, a polyethylene film, a polypropylene film, a plastic film or paper surface-coated with a release agent such as a fluorine-based release agent or a long-chain alkyl acrylate-based release agent.

[0108] The thickness of the above release liner is, for example, 10 to 200 μm, preferably 15 to 150 μm, more preferably 20 to 100 μm. When the thickness is 10 μm or more, the release liner is less likely to break due to cutting during processing. When the thickness is 200 μm or less, the release liner can be more easily peeled off from the sheet for encapsulating an optical semiconductor element during use.

[0109] FIG. 1 and FIG. 2 are cross-sectional views showing an embodiment of the sheet for encapsulating an optical semiconductor element of the present invention. As shown in FIGS. 1 and 2, the sheet 1 for encapsulating an optical semiconductor element can be used to encapsulate one or more optical semiconductor elements disposed on a substrate, and includes a base material portion 4 and a resin layer 2 for encapsulation formed on the base material portion 4. The base material portion 4 is composed of a base material film 41 and a functional layer 42 which is a surface treatment layer, but may be composed of only the base material film 41 without the functional layer 42.

[0110] In the sheet 1 for encapsulating an optical semiconductor element shown in FIG. 1, the resin layer 2 for encapsulation is formed of a single layer of the thermosetting adhesive layer 21 of the present invention. A release liner 3 is attached to one surface of the thermosetting adhesive layer 21 of the present invention, and the base material portion 4 is attached to the other surface.

[0111] In the sheet 1 for encapsulating an optical semiconductor device shown in Fig. 2, the encapsulating resin layer 2 is formed from a laminate of the thermosetting adhesive layer 21 of the present invention and the non-diffusion functional layer 22. The non-diffusion functional layer 22 is directly laminated on the thermosetting adhesive layer 21 of the present invention. A release liner 3 is attached to the thermosetting adhesive layer 21 of the present invention, and a base material portion 4 is attached to the non-diffusion functional layer 22.

[0112] In Figs. 1 and 2, the functional layer 42 is a layer not included in the above-described encapsulating resin layer, and examples of the layer that can impart various functions to the sheet for encapsulating an optical semiconductor device include a layer containing a surface treatment layer. By having such a configuration, the sheet for encapsulating an optical semiconductor device having a functional layer including a surface treatment layer laminated thereon is excellent in light diffusibility and light extraction efficiency. Examples of the surface treatment layer include an antiglare treatment layer (anti-reflection treatment layer), an antireflection treatment layer, and a hard coat treatment layer. The functional layer may be laminated on the encapsulating resin layer in the sheet for encapsulating an optical semiconductor device, or may be laminated on the base material portion when the base material portion is provided. However, it is preferably laminated on the base material portion, and more preferably laminated on the side opposite to the side of the base material portion provided with the encapsulating resin layer.

[0113] [Method for manufacturing a sheet for encapsulating an optical semiconductor device] An embodiment of the method for manufacturing the sheet for encapsulating an optical semiconductor device will be described. For example, the sheet 1 for encapsulating an optical semiconductor device shown in Fig. 1 is produced by forming the thermosetting adhesive layer 21 of the present invention sandwiched between the release surfaces of two release liners. One of the release liners bonded to the thermosetting adhesive layer 21 of the present invention is the release liner 3. Next, one of the release liners attached to the thermosetting adhesive layer 21 of the present invention (the release liner other than the release liner 3) is peeled off to expose the surface of the thermosetting adhesive layer 21 of the present invention, and the exposed surface is bonded to the base material portion 4. In this way, the sheet 1 for encapsulating an optical semiconductor device shown in Fig. 1, in which the thermosetting adhesive layer 21 of the present invention and the release liner 3 are laminated in this order on the base material portion 4, can be produced.

[0114] Further, the sheet 1 for sealing an optical semiconductor element shown in FIG. 2 is produced by separately manufacturing, for example, the thermosetting adhesive layer 21 and the non-diffusion functional layer 22 of the present invention, each of which is sandwiched between the release surfaces of two release liners. One of the release liners bonded to the thermosetting adhesive layer 21 of the present invention is the release liner 3. Next, one of the release liners attached to the non-diffusion functional layer 22 is peeled off to expose the surface of the non-diffusion functional layer 22, and the exposed surface is bonded to the base material portion 4. Then, one of the release liners (the release liner other than the release liner 3) bonded to the thermosetting adhesive layer 21 of the present invention is peeled off, and the release liner on the surface of the non-diffusion functional layer 22 is peeled off to expose the surface of the non-diffusion functional layer 22, and the exposed surface of the thermosetting adhesive layer 21 of the present invention is bonded to the exposed surface of the non-diffusion functional layer 22. The lamination of various layers can be performed using known rollers or laminators. In this way, the sheet 1 for sealing an optical semiconductor element shown in FIG. 2, in which the non-diffusion functional layer 22, the thermosetting adhesive layer 21 of the present invention, and the release liner 3 are laminated in this order on the base material portion 4, can be produced.

[0115] [Optical Semiconductor Device] An optical semiconductor device such as an image display device can be produced using the above-described sheet for sealing an optical semiconductor element. The optical semiconductor device produced using the above-described sheet for sealing an optical semiconductor element includes a substrate, an optical semiconductor element disposed on the substrate, and the above-described sheet for sealing an optical semiconductor element or a cured product obtained by curing the sheet for sealing the optical semiconductor element. The cured product is a cured product obtained by thermally curing the thermosetting adhesive layer 21 included in the sheet for sealing an optical semiconductor element, and specifically includes a cured sealing layer obtained by thermally curing the thermosetting adhesive layer 21 of the present invention.

[0116] 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.

[0117] In the above optical semiconductor device, the sheet for encapsulating the optical semiconductor element is excellent in followability to unevenness when the optical semiconductor element is a convex portion and the gap between a plurality of optical semiconductor elements is a concave portion, and is excellent in followability and embedability of the optical semiconductor element. Therefore, it is preferable to encapsulate a plurality of optical semiconductor elements together.

[0118] FIG. 3 shows an embodiment of an optical semiconductor device using the sheet 1 for encapsulating an optical semiconductor element shown in FIG. 1. The optical semiconductor device 10 shown in FIG. 3 includes a substrate 5, a plurality of optical semiconductor elements 6 disposed on one surface of the substrate 5, a cured encapsulation layer 7 that encapsulates the optical semiconductor elements 6, and a base material portion 4 laminated on the cured encapsulation layer 7. The plurality of optical semiconductor elements 6 are encapsulated together in the cured encapsulation layer 7. The cured encapsulation layer 7 is formed of a single layer of a diffusion function coloring layer 71. The diffusion function coloring layer 71 follows the uneven shape formed by the plurality of optical semiconductor elements 6, adheres closely to the optical semiconductor elements 6 and the substrate 5, and embeds the optical semiconductor elements 6. Further, the diffusion function coloring layer 71 follows the uneven shape, and the interface on the optical semiconductor element 6 side has an uneven shape, while the other interface is flat.

[0119] FIG. 4 shows an embodiment of an optical semiconductor device using the sheet 1 for encapsulating an optical semiconductor element shown in FIG. 2. The optical semiconductor device 10 shown in FIG. 4 includes a substrate 5, a plurality of optical semiconductor elements 6 disposed on one surface of the substrate 5, a cured encapsulation layer 7 that encapsulates the optical semiconductor elements 6, and a base material portion 4 laminated on the cured encapsulation layer 7. The plurality of optical semiconductor elements 6 are encapsulated together in the cured encapsulation layer 7. The cured encapsulation layer 7 is formed by laminating a diffusion function coloring layer 71 and a non-diffusion function layer 72. The diffusion function coloring layer 71 follows the uneven shape formed by the plurality of optical semiconductor elements 6, adheres closely to the optical semiconductor elements 6 and the substrate 5, and embeds the optical semiconductor elements 6. Further, the diffusion function coloring layer 71 follows the uneven shape, and the interface on the optical semiconductor element 6 side has an uneven shape, while the other interface is flat.

[0120] The hard encapsulation layer 7 is formed by the encapsulation resin layer 2. Specifically, the hard encapsulation layer 7 is formed by the curing of the encapsulation resin layer 2. For example, in the optical semiconductor device 10 shown in FIG. 3, it is composed of a diffusion function coloring layer 71 formed by the thermal curing of the thermosetting adhesive layer 21 of the present invention. For example, in the optical semiconductor device 10 shown in FIG. 4, it is composed of a diffusion function coloring layer 71 formed by the thermal curing of the thermosetting adhesive layer 21 of the present invention and a non-diffusion function layer 72 formed by the thermal curing of the non-diffusion function layer 22.

[0121] In the optical semiconductor device 10 shown in FIG. 4, the optical semiconductor element 6 is completely embedded and encapsulated in the diffusion function coloring layer 71 and is indirectly encapsulated by the non-diffusion function layer 72. That is, the optical semiconductor element 6 is encapsulated by the hard encapsulation layer 7 composed of a laminate of the diffusion function coloring layer 71 and the non-diffusion function layer 72. The above optical semiconductor device is not limited to such a mode. For example, as shown in FIG. 5, the optical semiconductor element 6 may be completely embedded and encapsulated in the diffusion function coloring layer 71 and the non-diffusion function layer 72.

[0122] As described above, the above optical semiconductor device encapsulates the optical semiconductor element with a hard encapsulation layer. The thermosetting adhesive layer of the present invention has sufficient flexibility before thermal curing, has excellent unevenness followability, fully embeds the optical semiconductor element, and fixes the optical semiconductor element after thermal curing. Therefore, the optical semiconductor element is in close contact with the hard encapsulation layer, and the sealing property of the optical semiconductor element is excellent. In addition, since the side surface of the thermosetting adhesive layer has low adhesiveness, the workability is excellent. Also, in the tiled state, when separating adjacent optical semiconductor devices from each other, they can be easily separated, and sheet breakage and adhesion of the sheets of adjacent optical semiconductor devices are less likely to occur. And the thermosetting adhesive layer of the present invention has excellent antireflection property and luminance balance because the light transmittance after curing is within a specific range, and the luminance variation is suppressed by containing a light diffusing agent, and the optical characteristics are excellent.

[0123] The above optical semiconductor device may be one in which individual optical semiconductor devices are tiled. That is, the above optical semiconductor device may be one in which a plurality of optical semiconductor devices are arranged in a tile shape in the planar direction.

[0124] FIG. 6 shows an embodiment of an optical semiconductor device fabricated by arranging a plurality of optical semiconductor devices. The optical semiconductor device 20 shown in FIG. 6 is formed by arranging a total of 16 optical semiconductor devices 10 (4 in the vertical direction and 4 in the horizontal direction) in a tile-like pattern in the planar direction. At the boundary 20a between two adjacent optical semiconductor devices 10, the optical semiconductor devices 10 are adjacent to each other, but they can be easily separated. Defects on the side surface of the cured encapsulation layer 7 and adhesion of the resin missing on the side surface of the cured encapsulation layer from one adjacent optical semiconductor device to the other are less likely to occur.

[0125] The above image display device preferably includes a self-emitting display device. Further, an image display device can be formed by combining the self-emitting display device and, if necessary, a display panel. In this case, the optical semiconductor element is an LED element. Examples of the self-emitting display device include an LED display, a backlight, or an organic electroluminescence (organic EL) display device. The backlight is particularly preferably a full-array direct-lit backlight. The backlight includes, for example, at least a part of a laminate including the substrate and a plurality of optical semiconductor elements arranged on the substrate as a constituent member. For example, in the above self-emitting display device, a metal wiring layer for sending a light emission control signal to each LED element is laminated on the substrate. Each LED element that emits light of each color of red (R), green (G), and blue (B) is alternately arranged on the substrate via the metal wiring layer. The metal wiring layer is formed of a metal such as copper and adjusts the light emission intensity of each LED element to display each color.

[0126] The above sheet for encapsulating an optical semiconductor element can be used for an optical semiconductor device that is used after being bent, such as an image display device that can be bent (flexible display) (particularly, an image display device that can be folded (foldable display)). Specifically, it can be used for a foldable backlight and a foldable self-emitting display device, etc.

[0127] Since the sheet for encapsulating the optical semiconductor element is excellent in followability and embeddability of the optical semiconductor element, it can be preferably used in both the case where the optical semiconductor device is a mini-LED display device and the case where it is a micro-LED display device.

[0128] [Method for manufacturing an optical semiconductor device] The optical semiconductor device can be manufactured, for example, by a manufacturing method including a step of bonding the sheet for encapsulating the optical semiconductor element 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 heating a laminate including the substrate, the optical semiconductor element disposed on the substrate, and the sheet for encapsulating the optical semiconductor element that encapsulates the optical semiconductor element obtained through the encapsulation step to cure the thermosetting adhesive layer of the present invention to obtain the cured product (heating step). The cured product is a cured product obtained by thermally curing the thermosetting adhesive layer of the present invention, and specifically includes a cured encapsulation layer obtained by thermally curing the thermosetting adhesive layer of the present invention.

[0129] The manufacturing method may further include a step of dicing the laminate obtained through the heating step to obtain an optical semiconductor device (dicing step). Further, the manufacturing method may further include a tiling step of arranging a plurality of optical semiconductor devices obtained in the dicing step so as to be in contact with each other in the planar direction. Hereinafter, the manufacturing method of the optical semiconductor device 10 shown in FIG. 3 and the optical semiconductor device 20 shown in FIG. 6 will be described with appropriate reference.

[0130] (Encapsulation step) In a method of manufacturing an optical semiconductor device using the sheet for encapsulating an optical semiconductor element, the method includes an encapsulation step of bonding the sheet for encapsulating an optical semiconductor element to a substrate on which the optical semiconductor element is disposed and encapsulating the optical semiconductor element with an encapsulating resin layer. Specifically, in the encapsulation step, first, a release liner is peeled off from the sheet for encapsulating an optical semiconductor element to expose the encapsulating resin layer. Then, the exposed surface of the sheet for encapsulating an optical semiconductor element is bonded to the surface of the substrate of the laminate (such as an optical member) including the substrate and the optical semiconductor element (preferably a plurality of optical semiconductor elements) disposed on the substrate, on which the optical semiconductor element is disposed. When the laminate includes a plurality of optical semiconductor elements, the encapsulating resin layer is further arranged to fill the gaps between the plurality of optical semiconductor elements, and the plurality of optical semiconductor elements are encapsulated together. Specifically, the thermosetting adhesive layer 21 of the present invention exposed by peeling off the release liner 3 from the sheet 1 for encapsulating an optical semiconductor element shown in FIG. 1 is arranged to face the surface of the substrate 5 on which the optical semiconductor element 6 is disposed, and the sheet 1 for encapsulating an optical semiconductor element is bonded to the surface of the substrate 5 on which the optical semiconductor element 6 is disposed, and the optical semiconductor element 6 is embedded or closely adhered to the encapsulating resin layer 2.

[0131] The temperature during the bonding is, for example, in the range from room temperature to 150°C. Further, during the bonding, depressurization or pressurization may be performed. By depressurization or pressurization, it is possible to suppress the formation of voids between the encapsulating resin layer and the substrate or the optical semiconductor element. Further, in the encapsulation step, it is preferable to bond the sheet for encapsulating an optical semiconductor element under reduced pressure and then pressurize. The pressure during depressurization is, for example, 1 to 100 Pa, and the depressurization time is, for example, 5 to 600 seconds. The pressure during pressurization is, for example, 0.05 to 0.5 MPa, and the pressurization time is, for example, 5 to 600 seconds.

[0132] (Heating step) In the above heating step, the laminate in which the sheet for sealing the optical semiconductor element is bonded to the substrate on which the optical semiconductor element is disposed (for example, the laminate obtained in the above sealing step) is heated to cure the thermosetting adhesive layer of the present invention and, if necessary, the non-diffusion functional layer. In the above heating step, specifically, as shown in FIG. 3, the thermosetting adhesive layer 21 of the present invention is cured to form the cured sealing layer 7, and a cured product of the sheet for sealing the optical semiconductor element 1 is obtained. The temperature during the above heating is, for example, in the range of 80 to 200°C, and the heating time is, for example, 1 minute to 24 hours.

[0133] (Dicing step) In the above dicing step, the laminate that has undergone the above heating step is diced. Here, in the laminate to be subjected to the dicing step, the cured product of the sheet for sealing the optical semiconductor element and the substrate 5 extend wider in the planar direction than the finally obtained optical semiconductor device 10. Then, in the above dicing step, the side end portions of the cured product of the sheet for sealing the optical semiconductor element and the substrate are diced and removed. The above dicing can be performed by a known or conventional method, for example, a method using a dicing blade or a method using laser irradiation. In this way, for example, the optical semiconductor device 10 shown in FIG. 2 can be manufactured.

[0134] (Tiling step) In the above tiling step, the plurality of optical semiconductor devices obtained in the above dicing step are tiled by arranging them in contact with each other in the planar direction. In this way, for example, the optical semiconductor device 20 (for example, one large image display device) shown in FIG. 6 can be manufactured. The optical semiconductor devices obtained by tiling are excellent in the sealing property of the optical semiconductor elements, and when separating adjacent optical semiconductor devices from each other, sheet defects and adhesion of the sheets of adjacent optical semiconductor devices are less likely to occur.

Example

[0135] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0136] Example 1 49.55 parts by mass of acrylic polymer A1 (glycidyl methacrylate (GMA): ethyl acrylate (EA): butyl methacrylate (BMA) = 34% by mass: 30% by mass: 36% by mass, weight average molecular weight 60,000), 27 parts by mass of acrylic resin B (trade name "UC-3000", carboxyl group-containing acrylic resin, manufactured by Toagosei Co., Ltd.), 0.3 parts by mass of "Carbon Black #20" (manufactured by Mitsubishi Chemical Corporation), 20 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), and 3 parts by mass of silane coupling agent (trade name "KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd.) were dissolved in methyl ethyl ketone to prepare a resin composition solution having a solid content concentration of 50% by mass. The above resin composition solution was applied onto the release-treated surface of a release liner (a release-treated film made of a polyethylene terephthalate film having a thickness of 38 μm and subjected to a silicone release treatment), and then dried at 130°C for 2 minutes to produce a sheet-like thermosetting resin composition (thermosetting adhesive layer) having a thickness (average thickness) of 30 μm, which was used as a sealing sheet.

[0137] Examples 2 to 3, Comparative Examples 1 to 2 A sheet-like thermosetting resin composition (thermosetting adhesive layer) was produced in the same manner as in Example 1 except that the blending amounts and thicknesses of the respective components were changed as shown in Table 1, and this was used as a sealing sheet.

[0138] Comparative Example 3 95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid, 249 parts by mass of ethyl acetate as a solvent, and 0.2 parts by mass of azobisisobutyronitrile were mixed to obtain a monomer composition. The obtained monomer composition was put into a 1 L round-bottom separable flask equipped with a separable cover, a separatory funnel, a thermometer, a nitrogen inlet tube, a Liebig condenser, a vacuum seal, a stirring rod, and a stirring blade, and purged with nitrogen while stirring. Then, while flowing nitrogen and stirring, it was polymerized by holding at 65 °C for 4 hours and then at 75 °C for 2 hours to obtain Polymer A. To 100 parts by mass of this Polymer A, 3 parts by mass of a black pigment (trade name "ATDN101 Black", manufactured by Dainichi Seika Kogyo Co., Ltd.), 20 parts by mass of a silicone resin (trade name "Tospearl 145", manufactured by Momentive Performance Materials Japan Co., Ltd., refractive index: 1.42, average particle size: 4.5 μm), 0.4 parts by mass of a crosslinking agent (trade name "Coronate HX", manufactured by Tosoh Corporation), and 0.01 parts by mass of a catalyst (trade name "Narsem Ferric Oxide II", manufactured by Nippon Chemical Industry Co., Ltd.) were added to obtain an adhesive composition. The above adhesive composition was applied onto the release-treated surface of a release liner (a release-treated film made of a polyethylene terephthalate film having a thickness of 38 μm and subjected to a silicone release treatment), and then dried at 130 °C for 2 minutes to produce a sheet-like adhesive layer having a thickness (average thickness) of 30 μm, which was used as a sealing sheet.

[0139] <Evaluation> The following evaluations were performed on the sealing sheets obtained in the examples and comparative examples. The results are shown in Table 1.

[0140] (1) Elastic modulus G' at 130 °C before curing The sealing sheets obtained in the examples and comparative examples were laminated to produce a laminate of a resin composition having a thickness of about 300 μm, which was punched into a cylindrical shape with a diameter of φ8 mm to obtain a measurement sample. Using a rheometer (trade name "HAAKE MARS III Rheometer", manufactured by Thermo SCIENTIFIC), the above measurement sample was measured in a shear mode at a frequency of 1 Hz in the temperature range of 80 to 160 °C at a heating rate of 5 °C / min to calculate the elastic modulus G' at 130 °C.

[0141] (2) Tensile storage elastic modulus E’ at room temperature (25 °C) before curing The sealing sheets obtained in the examples and comparative examples were overlapped under the condition of 60 °C until the thickness reached 200 μm, cut out into strips with a width of 10 mm × a length of 40 mm using a cutter knife, and used as measurement samples. Using a solid viscoelasticity measuring device (trade name "RSAIII", manufactured by Rheometric Scientific), in the tensile mode, at a frequency of 1 Hz and a chuck distance of 22.5 mm, the dynamic storage elastic modulus was measured in the range of -10 to 250 °C at a heating rate of 5 °C / min, and the tensile storage elastic modulus E’ at 25 °C was calculated.

[0142] (3) Tensile storage elastic modulus E’ at room temperature (25 °C) after curing The sealing sheets obtained in the examples and comparative examples were overlapped under the condition of 60 °C until the thickness reached 200 μm, cut out into strips with a width of 10 mm × a length of 40 mm using a cutter knife, heated and cured at 150 °C × 1 h, and used as measurement samples. Using a solid viscoelasticity measuring device (trade name "RSAIII", manufactured by Rheometric Scientific), in the tensile mode, at a frequency of 1 Hz and a chuck distance of 22.5 mm, the dynamic storage elastic modulus was measured in the range of -10 to 250 °C at a heating rate of 5 °C / min, and the tensile storage elastic modulus E’ at 25 °C was calculated.

[0143] (4) Light transmittance after curing Regarding the sealing sheets obtained in the examples and comparative examples, they were then heated and cured at 150 °C for 1 hour and used as measurement samples. Then, using an ultraviolet-visible near-infrared spectrophotometer (trade name "V-670DS", manufactured by JASCO Corporation) and an integrating sphere unit, the total light transmittance spectrum in the wavelength range of 300 to 2000 nm was measured, and the transmittance at a wavelength of 600 nm was read from the obtained spectrum.

[0144] (5) Haze value For the sealing sheets obtained in the examples and comparative examples, they were heated at 150°C for 1 hour for curing, and then those stored at 125°C for 1000 hours were used as measurement samples. And they were set in the sample chamber of a haze meter (trade name "NDHG2000", manufactured by Nippon Denshoku Industries Co., Ltd.), and the haze value was measured using the light source D65.

[0145] (6) Appearance (flatness) The sealing sheets obtained in the examples and comparative examples were sealed on a pattern wafer with a height of 10 μm, a length of 30 μm, and a width of 15 μm at 130°C × 0.3 MPa × 600 seconds using a vacuum press device, and samples after heat curing at 150°C × 1 h were prepared. The height of the undulation on the surface of the release liner was measured with Dekak, and the difference between the maximum value and the minimum value of the surface undulation was measured. And the appearance was evaluated based on the following evaluation criteria. [Evaluation criteria] ◎: The difference between the maximum value and the minimum value of the surface undulation is less than 2 μm 〇: The difference between the maximum value and the minimum value of the surface undulation exceeds 2 μm and is less than 4 μm ×: The difference between the maximum value and the minimum value of the surface undulation exceeds 4 μm

[0146] (7) Luminance A film (trade name "Lumirror S10", thickness 12 μm) manufactured by Toray Industries, Inc. with a size of 30 mm × 30 mm was placed in the center of a glass plate (trade name "S9112", 76 × 52 mm) manufactured by Matsunami Glass Industry Co., Ltd., and the sealing sheets obtained in the examples and comparative examples were stacked on it, and sealed at 130°C × 0.3 MPa × 600 seconds using a vacuum press device. And the luminance was evaluated based on the following evaluation criteria. [Evaluation criteria] ◎: The transmittance of the film part is 50% or more 〇: The transmittance of the film part is 40% or more and less than 50% △: The transmittance of the film part is 30% or more and less than 40% ×: The transmittance of the film part is less than 30%

[0147] (8) Luminance variation The release liners on the optical semiconductor element side of the sealing sheets obtained in the examples and comparative examples were peeled off and bonded to a glass plate to obtain samples. An LED lamp (manufactured by E-Kei Japan Co., Ltd., product name "LK-3PG") was installed at the upper part of the screen so that the height was 2.4 cm. The glass plate side of the center of the above sample prepared by luminance measurement was brought into close contact with the LED lamp. A battery box (manufactured by E-Kei Japan Co., Ltd., product name "AP-180") was connected to the LED lamp to turn on the LED lamp, and the diameter of the circular image projected on the screen was measured, and the luminance variation was evaluated according to the following criteria. 〇: The diameter exceeds 2 cm ×: The diameter is 2 cm or less

[0148] (9) Anti-reflection property For the sealing sheets obtained in the examples and comparative examples, the surface where the release film on the optical semiconductor element side was peeled off and exposed was bonded to an aluminum foil to prepare samples. The obtained samples were installed in "SolidSpec3700" (manufactured by Shimadzu Corporation) so that the release liner on the side opposite to the optical semiconductor element side was on the light source side, and the reflectance (%) at 280 to 780 nm was measured. Then, the anti-reflection property was evaluated based on the following evaluation criteria. [Evaluation criteria] ◎: The reflectance at 550 nm is 8.5% or less 〇: The reflectance at 550 nm exceeds 8.5% and is 10% or less △: The reflectance at 550 nm exceeds 10% and is 25% or less ×: The reflectance at 550 nm exceeds 25%

[0149] (10) Workability The sealed samples prepared in the above appearance evaluation were diced into a size of 10 mm × 10 mm, and the amount of resin overflow and creep from the wafer edge were evaluated. Then, the workability was evaluated based on the following evaluation criteria. [Evaluation criteria] ◎: The amount of resin overflow and creep from the wafer edge are less than 10 μm ×: The amount of resin overflow and creep from the wafer edge are 10 μm or more

[0150] (11) Chipping The samples used in the above workability evaluation were observed to confirm the amount of chipping, and evaluation was performed based on the following evaluation criteria. [Evaluation Criteria] ◎: The amount of resin chipping from the edge of the wafer into the resin is less than 10 μm ×: The amount of resin chipping from the edge of the wafer into the resin is 10 μm or more

[0151] (12) Reliability After the samples after encapsulation prepared in the above appearance evaluation were subjected to 3 cycles of 260 °C × 1 minute, the presence or absence of peeling between the encapsulation sheet and the wafer was confirmed using SAT. And the reliability was evaluated based on the following evaluation criteria. [Evaluation Criteria] ◎: Among those subjected to n9 input, the number of those showing a black shadow in SAT is 0 / 9 〇: Among those subjected to n9 input, the number of those showing a black shadow in SAT is 1 / 9 or more and 3 / 9 or less ×: Among those subjected to n9 input, the number of those showing a black shadow in SAT is 4 / 9 or more

[0152]

Table 1

[0153] As shown in Table 1, the encapsulation sheet of the example was evaluated to be excellent in antireflection property, with little variation in luminance, excellent optical properties, excellent workability, no chipping, and excellent reliability. On the other hand, when the light transmittance was high or low (Comparative Examples 1 and 2), it was evaluated to have low antireflection property, or low luminance and inferior optical properties. Also, when an adhesive layer was used instead of the thermosetting adhesive layer (Comparative Example 3), it was evaluated to be inferior in workability, with chipping occurring and voids occurring during encapsulation, resulting in inferior reliability.

[0154] Hereinafter, variations of the invention according to the present disclosure will be described. [Appendix 1] A sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, The sheet includes a resin layer for sealing that includes at least a thermosetting adhesive layer containing a colorant and a light diffusing agent. The thermosetting adhesive layer is a layer that contacts the optical semiconductor element when the optical semiconductor element is sealed. An optical semiconductor element sealing sheet, wherein the light transmittance of the sheet at a wavelength of 600 nm after curing of the resin layer for sealing is 9 to 73%. [Appendix 2] The optical semiconductor element sealing sheet according to Appendix 1, wherein the thickness of the thermosetting adhesive layer is 10 to 150 μm. [Appendix 3] The optical semiconductor element sealing sheet according to Appendix 1 or 2, wherein the elastic modulus E' at room temperature before curing of the thermosetting adhesive layer is 500 to 4000 MPa. [Appendix 4] The optical semiconductor element sealing sheet according to any one of Appendices 1 to 3, wherein the elastic modulus E' at room temperature after curing of the thermosetting adhesive layer is 500 to 4000 MPa. [Appendix 5] The optical semiconductor element sealing sheet according to any one of Appendices 1 to 4, wherein the haze value of the sheet after curing of the resin layer for sealing is 30% or more. [Appendix 6] The optical semiconductor element sealing sheet according to any one of Appendices 1 to 5, wherein the distance from the optical semiconductor element to the thermosetting adhesive layer in a state where the optical semiconductor element is sealed is 0 to 20 μm. [Appendix 7] The optical semiconductor element sealing sheet according to any one of Appendices 1 to 6, further comprising a layer having antiglare properties and / or antireflection properties on the surface of the resin layer for sealing opposite to the side in contact with the optical semiconductor element. [Appendix 8] An optical semiconductor device comprising a substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element sealing sheet according to any one of Appendices 1 to 7 or a cured product thereof for sealing the optical semiconductor element.

Explanation of Reference Numerals

[0155] 1 Optical semiconductor element sealing sheet 2 Resin layer for sealing 21 Thermosetting adhesive layer of the present invention 22 Non-diffusion functional layer 3 Release liner 4 Base material part 41 Substrate film 42 Functional layer 5 Substrate 6 Optoelectronic semiconductor device 7 Hardened encapsulation layer 71 Diffusion functional coloring layer 72 Non-diffusion functional layer 10, 20 Optoelectronic semiconductor device

Claims

1. A sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, wherein the sheet comprises a resin layer for encapsulation including at least a thermosetting adhesive layer containing a colorant and a light diffusing agent, the thermosetting adhesive layer being a layer that contacts the optical semiconductor element when the optical semiconductor element is encapsulated, and the light transmittance of the sheet at a wavelength of 600 nm after curing of the resin layer for encapsulation is 9 to 73%. A sheet for encapsulating an optical semiconductor element.

2. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the thickness of the thermosetting adhesive layer is 10 to 150 μm.

3. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, wherein the elastic modulus E' at room temperature before curing of the thermosetting adhesive layer is 500 to 4000 MPa.

4. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, wherein the elastic modulus E' at room temperature after curing of the thermosetting adhesive layer is 500 to 4000 MPa.

5. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, wherein the haze value of the sheet after curing of the resin layer for encapsulation is 30% or more.

6. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, wherein the distance from the optical semiconductor element to the thermosetting adhesive layer in a state where the optical semiconductor element is encapsulated is 0 to 20 μm.

7. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, comprising a layer having antiglare property and / or antireflection property on the surface of the resin layer for encapsulation opposite to the side contacting the optical semiconductor element.

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 according to claim 1 or 2 or a cured product thereof.

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