JP7572264B2 - Optical semiconductor element encapsulation sheet and method for producing optical semiconductor device - Google Patents

Description

The present invention relates to a sheet for encapsulating optical semiconductor elements. More specifically, the present invention relates to a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate. The present invention also relates to a method for manufacturing an optical semiconductor device.

For example, backlights used in liquid crystal display devices are known to have a structure in which multiple LEDs are arranged on a substrate, and the multiple LEDs are sealed with sealing resin. A method for sealing the multiple LEDs collectively using the sealing resin is known in which liquid resin is poured into the area where the multiple LEDs are arranged, the multiple LEDs are buried, and the liquid resin is then hardened by exposure to heat or ultraviolet light (see, for example, Patent Document 1).

JP 2017-66390 A

However, the method of using liquid resin to seal optical semiconductor elements such as LEDs has problems with poor handling, such as dripping when applying the liquid resin and adhesion to unintended areas.

In response to this, by using an encapsulating sheet having an encapsulating layer for encapsulating the optical semiconductor element, rather than using a liquid resin, it is possible to encapsulate the optical semiconductor element in a simple process and in a short time. Here, it is important that the encapsulating sheet has excellent encapsulation properties for the optical semiconductor element and excellent adhesion to the optical semiconductor element and the substrate having the optical semiconductor element in order to encapsulate the optical semiconductor element sufficiently.

Demand for larger-screen image display devices is growing with the trend toward higher image quality, such as 4K and 8K. Large-screen image display devices are also increasingly being used for signage, such as advertising displays and bulletin boards, outdoors and in public facilities. However, manufacturing large-screen image display devices poses problems of lower yields and higher manufacturing costs. In order to manufacture large-screen image display devices at lower cost, tiling displays, in which multiple optical semiconductor devices such as image display devices are arranged in a tiled pattern, are being considered. When multiple optical semiconductor devices are arranged in a tiled pattern, that is, when tiling, if there is a positional shift between adjacent optical semiconductor devices or if rearrangement is required, position correction is performed.

Here, when tiling optical semiconductor devices in which optical semiconductor elements are encapsulated with an encapsulating sheet, it is necessary to temporarily separate adjacent optical semiconductor devices in order to correct the position during tiling. However, when separating them, the encapsulating sheet of one optical semiconductor device and the encapsulating sheet of the other adjacent optical semiconductor device may come into close contact with each other and attract each other, resulting in defects such as defects in the encapsulating sheet of one optical semiconductor device or a part of the encapsulating sheet being transferred and attached to the other optical semiconductor device. Such defects are particularly likely to occur with encapsulating sheets that have excellent adhesion to optical semiconductor elements and substrates.

The present invention was conceived under these circumstances, and its purpose is to provide a sheet for sealing optical semiconductor elements that has excellent sealing properties for optical semiconductor elements, while preventing damage to the sheet or adhesion of adjacent optical semiconductor devices when separating the sheets from each other.

As a result of intensive research conducted by the present inventors to achieve the above object, they have found that a sheet for sealing optical semiconductor elements, which has a sealing portion having a non-radiation curable adhesive layer and a radiation curable resin layer, with the non-radiation curable adhesive layer located on the surface of the sealing portion facing the optical semiconductor element, has excellent sealing properties for optical semiconductor elements, while being less susceptible to damage to the sheet or adhesion of the sheets of adjacent optical semiconductor devices when the devices are separated from each other. The present invention has been completed based on these findings.

That is, the present invention provides a sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, comprising:
a substrate and a sealing portion provided on one surface of the substrate for sealing the optical semiconductor element;
The present invention provides a sheet for encapsulating optical semiconductor elements, wherein the encapsulating portion has a non-radiation-curable pressure-sensitive adhesive layer that is located on the surface facing the optical semiconductor element when the optical semiconductor element is encapsulated, and a radiation-curable resin layer that is laminated on the non-radiation-curable pressure-sensitive adhesive layer.

As described above, the sheet for sealing optical semiconductor elements includes a sealing portion in which a non-radiation curable adhesive layer and a radiation curable resin layer are laminated. The sealing portion is an area in the sheet for sealing optical semiconductor elements that seals the optical semiconductor elements. The non-radiation curable adhesive layer is located on the surface of the sealing portion that is on the optical semiconductor element side when sealing the optical semiconductor element. By having the non-radiation curable adhesive layer located on the surface, when the sheet for sealing optical semiconductor elements seals the optical semiconductor element, the adhesion of the non-radiation curable adhesive layer to the optical semiconductor element and the substrate is excellent, and the sealing performance of the optical semiconductor element is excellent. After sealing, the radiation curable resin layer is cured by irradiation with radiation, and the adhesion of the side surface of the sealing sheet is reduced. As a result, the adhesion between the sealing portions of adjacent optical semiconductor devices in a tiling state is low, and when adjacent optical semiconductor devices are separated from each other, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other. In addition, the substrate portion serves as a support for the sealing portion, and the sheet for sealing optical semiconductor elements is excellent in handleability due to the substrate portion. In addition, when dicing after encapsulating an optical semiconductor element with the sheet for encapsulating optical semiconductor elements to produce an optical semiconductor device, stickiness at the diced portion can be further suppressed, making it possible to produce an optical semiconductor device with a good appearance.

The radiation curable resin layer is preferably thicker than the non-radiation curable adhesive layer. With this configuration, the low adhesion of the radiation curable resin layer after curing in adjacent optical semiconductor devices becomes dominant over the high adhesion between the non-radiation curable adhesive layers in adjacent optical semiconductor devices in a tiling state, so that the adhesion between the sealing portions is even lower, and when adjacent optical semiconductor devices are separated from each other, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other. In addition, when dicing after sealing an optical semiconductor device with a sheet for sealing an optical semiconductor device, stickiness of the diced portion can be further suppressed, and an optical semiconductor device with a good appearance can be produced.

The sealing portion may include a layer containing a colorant. With this configuration, when the optical semiconductor device is tiled and applied to a display, it is possible to suppress color mixing of the light emitted by each optical semiconductor element when the optical semiconductor device is in use, and to adjust the appearance of the display when the optical semiconductor device is not in use.

The optical semiconductor element encapsulation sheet preferably has a layer having anti-glare and/or anti-reflection properties. With such a configuration, when the optical semiconductor device is tiled and applied to a display, the gloss and light reflection of the display can be suppressed, improving the appearance of the display.

The optical semiconductor element encapsulation sheet preferably has a layer mainly composed of a polyester resin and/or a polyimide resin. With such a configuration, the optical semiconductor element encapsulation sheet has excellent heat resistance, and the thermal expansion of the optical semiconductor element encapsulation sheet in a high-temperature environment can be suppressed, improving dimensional stability. In addition, the sheet can be given rigidity, improving handling and retention.

The hardness of the cross section of the radiation curable resin layer after curing, measured by nanoindentation at a temperature of 23°C, is preferably 1.4 MPa or more. With this configuration, the radiation curable resin layer has an appropriate hardness after curing, and when adjacent optical semiconductor devices are separated in a tiling state, damage to the sheet and adhesion of the sheets of adjacent optical semiconductor devices are even less likely to occur.

The present invention also provides an optical semiconductor device comprising a substrate, an optical semiconductor element disposed on the substrate, and a cured product formed by curing the radiation curable resin layer of the optical semiconductor element encapsulation sheet that encapsulates the optical semiconductor element. After the radiation curable resin is cured, such an optical semiconductor device is less likely to suffer damage to the sheet or adhesion of the sheets of adjacent optical semiconductor devices when adjacent optical semiconductor devices are separated from each other. In addition, stickiness of the diced portion can be suppressed during dicing, making it possible to produce an optical semiconductor device with a good appearance.

The optical semiconductor device may be a backlight for a liquid crystal screen. The optical semiconductor device may also be a self-luminous display device. The optical semiconductor device has a good appearance when applied to an optical semiconductor device having a display, and is therefore preferably applied as a backlight for a liquid crystal screen or a self-luminous display device.

The present invention also provides an image display device that includes the above-mentioned backlight and a display panel.

The present invention also provides an image display device that includes the above-mentioned self-luminous display device.

The present invention also provides a method for producing an optical semiconductor device, comprising a dicing step of dicing a laminate comprising a substrate, an optical semiconductor element disposed on the substrate, and a cured product of the radiation-curable resin layer of the optical semiconductor element encapsulation sheet, which encapsulates the optical semiconductor element, to obtain an optical semiconductor device.

When the radiation-curable resin layer is irradiated with radiation and cured, curing is inhibited on the side where oxygen is present, and curing is likely to be insufficient. In contrast, according to the above-mentioned manufacturing method including the above-mentioned dicing step, for a laminate including a cured product of a sheet for encapsulating optical semiconductor elements, including a cured encapsulating layer obtained by curing the radiation-curable resin layer by radiation irradiation, the side end portion that is insufficiently cured in the dicing step can be cut off and removed to obtain an optical semiconductor device in which an area that has been sufficiently cured and has reduced adhesion is exposed on the side. In the optical semiconductor device manufactured in this way, the adhesion of the side surface of the radiation-curable resin layer after curing is sufficiently reduced, so that when adjacent optical semiconductor devices are separated in a tiling state, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other.

The manufacturing method may further include a radiation exposure step of irradiating radiation to a laminate including the substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet that encapsulates the optical semiconductor element, thereby curing the radiation curable resin layer and obtaining the cured product.

The manufacturing method may include a sealing step of bonding the sheet for sealing an optical semiconductor element to the optical semiconductor element provided on the substrate to seal the optical semiconductor element with the sealing portion, and then the radiation irradiation step may be performed.

The manufacturing method may further include a tiling step of arranging the multiple optical semiconductor devices obtained in the dicing step so that they are in contact with each other in a planar direction.

The sheet for sealing optical semiconductor elements of the present invention has excellent sealing properties for optical semiconductor elements, while being less susceptible to damage to the sheet or adhesion of the sheets of adjacent optical semiconductor devices when separating adjacent optical semiconductor devices. Therefore, after tiling of the optical semiconductor devices, if there is a positional shift between adjacent optical semiconductor devices or if rearrangement is required, the position can be easily corrected without any problems, reducing loss of optical semiconductor devices and enabling the economical production of attractive displays.

1 is a cross-sectional view of a sheet for encapsulating an optical semiconductor element according to one embodiment of the present invention. 1 is a cross-sectional view of an optical semiconductor device using a sheet for encapsulating an optical semiconductor element according to one embodiment of the present invention. 3 is an external view showing one embodiment of an optical semiconductor device produced by tiling the optical semiconductor device shown in FIG. 2. 4A to 4C are cross-sectional views illustrating a sealing step in one embodiment of a method for manufacturing an optical semiconductor device. 5 shows a cross-sectional view of a laminate obtained after the sealing step shown in FIG. 4 . FIG. 6 is a cross-sectional view showing a laminate obtained by carrying out a radiation exposure step on the laminate shown in FIG. 5 . 7 is a cross-sectional view showing a dicing position in a dicing step of the stack shown in FIG. 6;

[Optical semiconductor element encapsulation sheet]
The sheet for encapsulating an optical semiconductor element of the present invention comprises at least a substrate and an encapsulation portion for encapsulating an optical semiconductor element, the encapsulation portion being provided on one surface of the substrate. In this specification, the sheet for encapsulating an optical semiconductor element refers to a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate. In this specification, the term "encapsulating an optical semiconductor element" refers to embedding at least a portion of the optical semiconductor element in the encapsulation portion.

The sheet for encapsulating optical semiconductor elements of the present invention may include a release liner in addition to the substrate and encapsulating portions. In this case, the release liner is attached to the surface of the encapsulating portion opposite the substrate. The release liner is used as a protective material for the encapsulating portion, and is peeled off when encapsulating the optical semiconductor element. The release liner is not necessarily provided.

The optical semiconductor element encapsulation sheet of the present invention may also have a surface protective film on the surface of the substrate (the surface opposite to the encapsulation portion). When an optical film described below is used as the substrate, the optical film can be protected until it is used. Note that the surface protective film does not necessarily have to be provided.

Hereinafter, one embodiment of the sheet for encapsulating optical semiconductor elements of the present invention will be described. FIG. 1 is a cross-sectional view showing one embodiment of the sheet for encapsulating optical semiconductor elements of the present invention. As shown in FIG. 1, the sheet for encapsulating optical semiconductor elements 1 can be used to encapsulate one or more optical semiconductor elements arranged on a substrate, and includes a substrate part 2, an encapsulating part 3, and a release liner 4. The encapsulating part 3 is provided on one side of the substrate part 2. The release liner 4 is attached to the surface of the encapsulating part 3 (the surface opposite to the side having the substrate part 2). In other words, the sheet for encapsulating optical semiconductor elements 1 includes the substrate part 2, the encapsulating part 3, and the release liner 4 in this order.

The optical semiconductor element encapsulation sheet preferably includes a layer having anti-glare and/or anti-reflection properties. With such a configuration, when the optical semiconductor device is tiled and applied to a display, the gloss of the display and light reflection can be suppressed, and the appearance of the display can be improved. An example of the layer having anti-glare properties is an anti-glare treatment layer. An example of the layer having anti-reflection properties is an anti-reflection treatment layer. The anti-glare treatment and the anti-reflection treatment can be performed by known or conventional methods. The layer having anti-glare properties and the layer having anti-reflection properties may be the same layer or different layers. The layer having anti-glare properties and/or anti-reflection properties may have only one layer, or two or more layers.

The layer having anti-glare and/or anti-reflection properties may be a layer included in the substrate, a layer included in the sealing portion, or another layer not included in the substrate or sealing portion, but is preferably a layer included in the substrate and/or sealing portion, and more preferably a layer included in the substrate.

The optical semiconductor element encapsulation sheet preferably has a layer mainly composed of a polyester resin and/or a polyimide resin (the component with the highest mass ratio among the constituent resins). With such a configuration, the optical semiconductor element encapsulation sheet has excellent heat resistance, and the thermal expansion of the optical semiconductor element encapsulation sheet can be suppressed in a high-temperature environment, improving dimensional stability. In addition, the sheet can be given rigidity, improving handling and retention. The layer mainly composed of the polyester resin and/or the polyimide resin may have only one layer, or two or more layers.

The layer mainly composed of the polyester resin and/or polyimide resin may be any of the layers included in the substrate, the layers included in the sealing portion, or other layers not included in the substrate or sealing portion, but is preferably a layer included in the substrate and/or sealing portion, and more preferably a layer included in the substrate.

(Sealing part)
The encapsulating portion has a resin layer (radiation curable resin layer) having a property of being cured by irradiation with radiation, and an adhesive layer (non-radiation curable adhesive layer) not having a property of being cured by irradiation with radiation. The non-radiation curable adhesive layer is located on the surface of the encapsulating portion that faces the optical semiconductor element when encapsulating the optical semiconductor element. Specifically, the non-radiation curable adhesive layer is located on the surface of the sheet for encapsulating an optical semiconductor element that faces the optical semiconductor element when encapsulating the optical semiconductor element (the sheet surface excluding the release liner when a release liner is provided). For example, in the sheet 1 for encapsulating an optical semiconductor element shown in FIG. 1, the encapsulating portion 3 is composed of a radiation curable resin layer 31 and a non-radiation curable adhesive layer 32. The non-radiation curable adhesive layer 32 is located on the surface of the sheet 1 for encapsulating an optical semiconductor element opposite to the substrate portion 2, excluding the release liner 4.

By positioning the non-radiation curable adhesive layer on the surface, when the sheet for sealing an optical semiconductor element seals an optical semiconductor element, the non-radiation curable adhesive layer has excellent adhesion to the optical semiconductor element and the substrate, and the sheet for sealing the optical semiconductor element has excellent sealing properties. After sealing, the radiation curable resin layer is cured by irradiation with radiation, and the adhesion of the side surface of the sheet for sealing decreases. As a result, the adhesion between the sealing parts of adjacent optical semiconductor devices in a tiling state is low, and when adjacent optical semiconductor devices are separated from each other, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other. In addition, the substrate part serves as a support for the sealing part, and the sheet for sealing an optical semiconductor element has excellent handleability by including the substrate part. In addition, when dicing after sealing an optical semiconductor device to produce an optical semiconductor device by sealing an optical semiconductor element with the sheet for sealing an optical semiconductor element, the stickiness of the diced part can be further suppressed, and an optical semiconductor device with a good appearance can be produced.

In the sealing portion, the radiation non-curable adhesive layer and the radiation curable resin layer are laminated. The radiation non-curable adhesive layer and the radiation curable resin layer may be laminated directly without any other layer, or may be laminated via another layer. The radiation non-curable adhesive layer and the radiation curable resin layer may each be a single layer, or may be multiple layers having the same composition or different thickness. When the sealing portion has at least one of the radiation non-curable adhesive layer and the radiation curable resin layer in a plurality of layers, the multiple layers may be laminated continuously or may be laminated via another layer. When the sealing portion has multiple layers of the radiation non-curable adhesive layer, it is sufficient that one layer is present on the surface opposite to the substrate of the sheet for sealing optical semiconductor elements, and the position of the other radiation non-curable adhesive layer is not particularly limited.

The ratio of the thickness (total thickness) of the radiation curable resin layer to the thickness (total thickness) of the non-radiation curable adhesive layer [thickness of radiation curable resin layer/thickness of radiation non-curable adhesive layer] is preferably 0.1 or more, more preferably 0.8 or more, even more preferably more than 1.0, and particularly preferably 4 or more. When the ratio is 0.1 or more, damage to the sheet or adhesion of the sheets of adjacent optical semiconductor devices is less likely to occur when adjacent optical semiconductor devices are separated from each other. In addition, the ratio is preferably 200 or less, more preferably 150 or less.

The radiation curable resin layer is preferably thicker than the non-radiation curable adhesive layer. With this configuration, the low adhesion of the radiation curable resin layer after curing in adjacent optical semiconductor devices becomes dominant in the tiling state, rather than the high adhesion between the radiation non-curable adhesive layers in adjacent optical semiconductor devices, so that the adhesion between the sealing parts is even lower, and when adjacent optical semiconductor devices are separated from each other, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other. In addition, when dicing is performed after sealing an optical semiconductor device with an optical semiconductor element sealing sheet to produce an optical semiconductor device, the stickiness of the diced part can be further suppressed, and an optical semiconductor device with a good appearance can be produced. Note that, when there are multiple radiation curable resin layers or multiple radiation non-curable adhesive layers, the above thickness is the total thickness (total thickness) of the multiple layers.

The thickness of the non-radiation curable adhesive layer located on the surface of the optical semiconductor element encapsulation sheet (i.e., the surface of the encapsulation portion) is preferably 1 μm or more, more preferably 4 μm or more, and even more preferably 15 μm or more. When the thickness is 1 μm or more, the adhesion of the optical semiconductor element encapsulation sheet to the optical semiconductor element and the substrate is superior. The thickness is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. When the thickness is 500 μm or less, when adjacent optical semiconductor devices are separated from each other, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other. In addition, when dicing the optical semiconductor device, stickiness of the diced portion can be further suppressed, and an optical semiconductor device with a good appearance can be produced.

The thickness (total thickness) of the radiation curable resin layer is preferably 20 to 800 μm, more preferably 30 to 700 μm, and even more preferably 50 to 600 μm. If the thickness is 20 μm or more, damage to the sheet and adhesion of the sheets of adjacent optical semiconductor devices are less likely to occur when adjacent optical semiconductor devices are separated from each other. If the thickness is 800 μm or less, the thickness of the sealing portion can be reduced, and the optical semiconductor device can be made thinner.

The optical semiconductor element encapsulation sheet preferably includes a radiation curable resin layer that is the thickest of all layers constituting the encapsulation portion. Note that a layer in which multiple layers of the same composition are directly laminated is considered to be one layer. In addition, when there are two or more thickest layers, all of the layers correspond to the thickest layer.

The ratio of the thickness (total thickness) of the radiation curable resin layer to the total thickness (excluding the release liner and surface protective film) of the sheet for encapsulating optical semiconductor elements (100%) is preferably 5 to 90%, more preferably 10 to 85%, and even more preferably 40 to 80%. If the ratio is 5% or more, damage to the sheet or adhesion of the sheets of adjacent optical semiconductor devices is less likely to occur when adjacent optical semiconductor devices are separated from each other. If the thickness is 90% or less, the thickness of the encapsulation portion can be reduced, allowing the optical semiconductor device to be made thinner.

After curing, the radiation curable resin layer preferably has a hardness of 1.4 MPa or more at a layer cross section measured by nanoindentation at a temperature of 23°C, more preferably 11.0 MPa or more, and even more preferably 63.0 MPa or more. The hardness by nanoindentation is determined by continuously measuring the load and indentation depth on the indenter when the indenter is pressed into the target surface, both during loading and unloading, and from the load-indentation depth curve obtained. If the hardness is 1.4 MPa or more, the radiation curable resin layer has an appropriate hardness after curing, and when adjacent optical semiconductor devices are separated from each other in a tiling state, damage to the sheet and adhesion of the sheets of adjacent optical semiconductor devices are even less likely to occur.

The radiation-curable resin layer has radiation curing properties. Examples of the radiation include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays.

Examples of the radiation-curable resin layer include a layer containing a base polymer and a radiation-polymerizable monomer component or oligomer component having a functional group such as a radiation-polymerizable carbon-carbon double bond, and a layer containing a polymer having a radiation-polymerizable functional group as a base polymer.

The resin constituting the radiation-curable resin layer may be a known or commonly used radiation-curable resin, such as an acrylic resin, a urethane acrylate resin, an epoxy resin, an epoxy acrylate resin, an oxetane resin, a silicone resin, a silicone acrylic resin, or a polyester resin. Only one of the above resins may be used, or two or more of them may be used.

The radiation-curable resin layer is preferably a resin layer having adhesive properties, i.e., a radiation-curable adhesive layer. With such a configuration, the optical semiconductor element can be easily embedded when sealing the optical semiconductor element, and the adhesion between the substrate and the non-radiation-curable adhesive layer located on the surface of the optical semiconductor element side before radiation curing is excellent, resulting in superior sealing of the optical semiconductor element.

The adhesive forming the non-radiation curable adhesive layer can be a known or conventional pressure-sensitive adhesive that is not radiation curable, i.e. does not contain a compound having radiation curability. However, it may contain a small amount of a compound having radiation curability that is unavoidably transferred from another laminated layer. Examples of the adhesive include acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, a mixture of these, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. Only one type of the adhesives may be used, or two or more types may be used.

The sealing portion may have layers other than the radiation curable resin layer and the non-radiation curable adhesive layer. However, the ratio of the total thickness of the radiation curable resin layer and the non-radiation curable adhesive layer to the thickness of the sealing portion (100%) is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 96% or more.

The sealing portion may include a layer containing a colorant. With this configuration, when the optical semiconductor device is tiled and applied to a display, it is possible to suppress color mixing of light emitted by each optical semiconductor element when the optical semiconductor device is in use, and to adjust the appearance of the display when the optical semiconductor device is not in use. The layer containing the colorant may be only one layer, or may have two or more layers.

The layer containing the colorant may be the radiation curable resin layer, the non-radiation curable adhesive layer, or any other layer other than these, but it is preferable that the radiation curable resin layer and/or the non-radiation curable adhesive layer is a layer containing a colorant, and it is more preferable that the non-radiation curable adhesive layer is a layer containing a colorant.

As the above-mentioned colorant, a black-based colorant is preferable. As the above-mentioned black-based colorant, a colorant (pigment, dye, etc.) for presenting a known or conventional black color can be used, for example, carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine smoke, 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 colorant, zirconium nitride, etc. Only one type of black-based colorant may be used, or two or more types may be used. In addition, a colorant that functions as a black-based colorant may be used by combining and blending colorants that present a color other than black.

(Base material)
The substrate serves as a support for the encapsulation portion, and the substrate provides the sheet for encapsulating optical semiconductor elements with excellent handling properties. The substrate may be a single layer, or may be a multilayer having the same or different compositions, thicknesses, etc. When the substrate is a multilayer, each layer may be bonded to another layer such as a pressure-sensitive adhesive layer. The substrate layer used in the substrate is a portion that is attached to a substrate having an optical semiconductor element together with the encapsulation portion when the sheet for encapsulating optical semiconductor elements is used to encapsulate the optical semiconductor element, and the release liner that is peeled off when the sheet for encapsulating optical semiconductor elements is used (attached) and the surface protection film that merely protects the surface of the substrate are not included in the "substrate".

Examples of the substrate layer constituting the substrate part include glass and plastic substrates (particularly plastic films). Examples of the resin constituting the plastic substrate include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ionomers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester (random, alternating) copolymers, ethylene-vinyl acetate copolymers (EVA), ethylene-propylene copolymers, cyclic olefin polymers, ethylene-butene copolymers, ethylene-hexene copolymers, etc. Examples of the resin include polyolefin resins, polyurethanes, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT), polycarbonates, polyimide resins, polyether ether ketones, polyetherimides, polyamides such as aramids and fully aromatic polyamides, polyphenyl sulfides, fluororesins, polyvinyl chloride, polyvinylidene chloride, cellulose resins such as triacetyl cellulose (TAC), silicone resins, acrylic resins such as polymethyl methacrylate (PMMA), polysulfones, polyarylates, and polyvinyl acetates. Only one of the above resins may be used, or two or more of them may be used.

The substrate layer may be an anti-reflection (AR) film, a polarizing plate, a retardation plate, or any other optical film. When the substrate portion has an optical film, the optical semiconductor element encapsulation sheet can be applied directly to an optical member.

The plastic film preferably contains a polyester resin and/or a polyimide resin as the main component (the component with the highest mass ratio among the constituent resins). With such a configuration, the sheet for encapsulating optical semiconductor elements has excellent heat resistance, and the thermal expansion of the sheet for encapsulating optical semiconductor elements in a high-temperature environment can be suppressed, improving dimensional stability. In addition, the rigidity of the sheet can be imparted, improving handling and retention.

The thickness of the plastic film is preferably 20 to 200 μm, and more preferably 40 to 150 μm. If the thickness is 20 μm or more, the supportability and handleability of the sheet for encapsulating optical semiconductor elements are further improved. If the thickness is 200 μm or less, the thickness of the sheet for encapsulating optical semiconductor elements can be reduced, and the optical semiconductor device can be made thinner.

The substrate preferably includes a plastic film mainly composed of a polyester resin and/or a polyimide resin, and an optical film. Optical films such as polarizing plates generally tend to be poor in support and handling, and by using them in combination with the plastic film, the advantages of both can be utilized. In this case, it is particularly preferable that the plastic film is on the sealing portion side of the substrate.

The substrate preferably includes a layer having antiglare and/or antireflection properties. The layer having antiglare and/or antireflection properties is obtained as the antiglare treatment layer or antireflection treatment layer by, for example, performing antiglare treatment and/or antireflection treatment on at least one surface of the substrate layer. The antiglare treatment layer and the antireflection treatment layer may be the same layer or different layers. The antiglare treatment and the antireflection treatment can be performed by known or conventional methods.

The surface of the substrate on the side having the sealing portion may be subjected to a surface treatment such as physical treatment such as corona discharge treatment, plasma treatment, sand mat processing treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, and ionizing radiation treatment; chemical treatment such as chromate treatment; and adhesion-enhancing treatment using a coating agent (primer). The surface treatment for enhancing adhesion is preferably applied to the entire surface of the substrate on the sealing portion side.

In the sheet 1 for sealing optical semiconductor elements shown in FIG. 1, the substrate 2 is a multilayer having an optical film 21 and a plastic film 23, and the optical film 21 and the plastic film 23 are bonded together via an adhesive layer 22. In addition, the surface of the optical film 21 facing the plastic film 23 is treated with an anti-glare treatment and an anti-reflection treatment.

The thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of excellent support function and surface scratch resistance. The thickness of the substrate is preferably 300 μm or less, more preferably 200 μm or less, from the viewpoint of excellent transparency.

(Release Liner)
The release liner is an element for covering and protecting the surface of the encapsulating portion, and is peeled off from the sheet when the optical semiconductor element encapsulating sheet is attached to a substrate on which an optical semiconductor element is arranged.

Examples of the release liners include polyethylene terephthalate (PET) films, polyethylene films, polypropylene films, plastic films and papers whose surfaces are coated with a release agent such as a fluorine-based release agent or a long-chain alkyl acrylate-based release agent.

The thickness of the release liner is, for example, 10 to 200 μm, preferably 15 to 150 μm, and more preferably 20 to 100 μm. If the thickness is 10 μm or more, the release liner is less likely to break due to cuts during processing. If the thickness is 200 μm or less, the release liner is more easily peeled off from the sealing portion during use.

(Optical semiconductor element encapsulation sheet)
The ratio of the total thickness of the substrate and the encapsulating portion in the optical semiconductor element encapsulation sheet is preferably 80% or more, more preferably 90% or more, relative to 100% of the thickness of the optical semiconductor element encapsulation sheet (excluding the release liner and the surface protective film). In addition, it is preferable that the ratio of the thickness from the substrate surface to the encapsulating portion surface, including the substrate and the encapsulating portion, is within the above range.

The total thickness of the substrate and sealing portion in the optical semiconductor element encapsulation sheet is preferably 100 to 900 μm, and more preferably 200 to 800 μm. In addition, it is preferable that the thickness from the substrate surface to the sealing portion surface, including the substrate and sealing portion, is within the above range.

One embodiment of the method for producing a sheet for encapsulating optical semiconductor elements of the present invention will be described. For example, the sheet for encapsulating optical semiconductor elements 1 shown in FIG. 1 can be produced by the following method. First, a radiation curable resin layer 31 is formed on the plastic film 23 constituting the substrate portion 2. The radiation curable resin layer 31 can be produced by applying a resin composition for forming the radiation curable resin layer 31 to one side of the plastic film 23 to form a resin composition layer, and then performing curing other than radiation irradiation, such as desolvation by heating or heat curing, to solidify the resin composition layer. When the thickness of the radiation curable resin layer 31 is to be increased, a radiation curable resin layer produced in the same manner on the release-treated surface of a release liner may be laminated on the radiation curable resin layer formed on the plastic film 23.

The resin composition forming the radiation-curable resin layer may be in any form as long as it does not impair the radiation curability of the radiation-curable resin layer. For example, the adhesive composition may be an emulsion type, a solvent type (solution type), a hot melt type, etc. Among these, the solvent type is preferred because it is easy to obtain an adhesive layer with excellent productivity.

On the other hand, a radiation non-curable adhesive layer 32 is formed on the release-treated surface of a release liner 4 prepared separately. The radiation non-curable adhesive layer 32 can be produced by applying the adhesive composition that forms the radiation non-curable adhesive layer 32 onto the release-treated surface of the release liner 4 to form an adhesive composition layer, and then heating to remove the solvent and harden the adhesive composition layer to solidify it. The radiation non-curable adhesive layer is then laminated on the radiation curable resin layer. In this way, a laminate having a configuration of [plastic film 23/radiation curable resin layer 31/radiation non-curable adhesive layer 32/release liner 4] is obtained.

The adhesive composition forming the non-radiation curable adhesive layer may be in any form. For example, the adhesive composition may be an emulsion type, a solvent type (solution type), an active energy ray curable type, a hot melt type, or the like. Among these, solvent type and active energy ray curable adhesive compositions are preferred because they are easy to obtain an adhesive layer with excellent productivity.

On the other hand, a laminate of the optical film 21 and the adhesive layer 22 is prepared. Specifically, for example, the adhesive layer 22 is formed on the release-treated surface of a separately prepared release liner in the same manner as the radiation-non-curable adhesive layer 32, and then the optical film 21 is laminated on the adhesive layer 22 to produce the laminate. The release liner is then peeled off to expose the adhesive layer 22, which is then laminated to the surface of the plastic film 23 of the laminate on which the radiation-curable resin layer 31 is not formed. For example, known or conventional coating methods can be used to apply the resin composition or adhesive composition, and examples of such methods include roll coating, screen coating, and gravure coating. In addition, the lamination of various layers can be performed using known rollers or laminators. In this manner, the optical semiconductor element encapsulation sheet 1 shown in FIG. 1 can be produced.

The method for producing the optical semiconductor element encapsulation sheet of the present invention is not limited to the above-mentioned method. When the substrate portion is composed of multiple layers, the substrate portion can be produced first, and then a radiation curable resin layer and a non-radiation curable adhesive layer can be laminated in appropriate combinations on the substrate portion, so that the non-radiation curable adhesive layer is located on the surface.

Using the sheet for sealing an optical semiconductor device of the present invention, a non-radiation curable adhesive layer is laminated on a substrate on which an optical semiconductor element is arranged, and the optical semiconductor element is sealed by the sealing portion, thereby obtaining an optical semiconductor device. Specifically, first, the release liner is peeled off from the sheet for sealing an optical semiconductor element of the present invention to expose the non-radiation curable adhesive layer. Then, the exposed surface of the sheet for sealing an optical semiconductor element of the present invention is laminated to the substrate surface on which the optical semiconductor element is arranged of an optical member comprising a substrate and an optical semiconductor element (preferably a plurality of optical semiconductor elements) arranged on the substrate, and when the optical member comprises a plurality of optical semiconductor elements, the non-radiation curable adhesive layer is further arranged so as to fill the gaps between the plurality of optical semiconductor elements, and the plurality of optical semiconductor elements are sealed together. In this way, the sheet for sealing an optical semiconductor device of the present invention can be used to seal the optical semiconductor element. The sheet for sealing an optical semiconductor device of the present invention may also be used to seal the optical semiconductor element by laminating the sheet under reduced pressure or while applying pressure. Examples of such methods include those disclosed in JP 2016-29689 A and JP 6-97268 A.

[Optical semiconductor device]
An optical semiconductor device can be produced using the sheet for encapsulating an optical semiconductor element of the present invention. The optical semiconductor device produced using the sheet for encapsulating an optical semiconductor element of the present invention comprises a substrate, an optical semiconductor element disposed on the substrate, and a cured product obtained by curing the sheet for encapsulating an optical semiconductor element of the present invention, which encapsulates the optical semiconductor element. The cured product is a cured product obtained by curing the sheet for encapsulating an optical semiconductor element of the present invention by irradiation with radiation, and specifically comprises a cured encapsulating layer obtained by curing the radiation-curable resin layer in the sheet for encapsulating an optical semiconductor element of the present invention by irradiation with radiation.

Examples of the optical semiconductor elements include light-emitting diodes (LEDs), such as blue light-emitting diodes, green light-emitting diodes, red light-emitting diodes, and ultraviolet light-emitting diodes.

In the above optical semiconductor device, the optical semiconductor element encapsulation sheet of the present invention has excellent conformability to irregularities when the optical semiconductor elements are convex portions and the gaps between multiple optical semiconductor elements are concave portions, and has excellent embedding properties for the optical semiconductor elements, so it is preferable that multiple optical semiconductor elements are encapsulated together.

Figure 2 shows one embodiment of an optical semiconductor device using the optical semiconductor element encapsulation sheet 1 shown in Figure 1. The optical semiconductor device 10 shown in Figure 2 includes a substrate 5, a plurality of optical semiconductor elements 6 arranged on one side of the substrate 5, and a cured product 1' of the optical semiconductor element encapsulation sheet that encapsulates the optical semiconductor elements 6. The cured product 1' of the optical semiconductor element encapsulation sheet is formed by peeling the release liner 4 from the optical semiconductor element encapsulation sheet 1 and curing the radiation curable resin layer 31 by radiation irradiation to form a cured encapsulation layer 31'. The multiple optical semiconductor elements 6 are encapsulated together in the encapsulation section. The radiation non-curable adhesive layer 32 in the encapsulation section adheres closely to the optical semiconductor elements 6 and the substrate 5, following the uneven shape formed by the multiple optical semiconductor elements 6, and embeds the optical semiconductor elements 6.

In the optical semiconductor device 10 shown in FIG. 2, the optical semiconductor element 6 is completely embedded and sealed in the non-radiation curable adhesive layer 32, and is indirectly sealed by the cured sealing layer 31'. The optical semiconductor device is not limited to this embodiment, and may be an embodiment in which a part of the optical semiconductor element 6 protrudes from the non-radiation curable adhesive layer 32, the part is embedded in the cured sealing layer 31', and the optical semiconductor element 6 is completely embedded and sealed between the non-radiation curable adhesive layer 32 and the cured sealing layer 31'.

As described above, the optical semiconductor device seals the optical semiconductor element with a non-radiation curable adhesive layer and a cured sealing layer that is a cured product of the radiation curable resin layer. Therefore, the optical semiconductor element is in close contact with the non-radiation curable adhesive layer, which provides excellent sealing properties for the optical semiconductor element, and the side surface of the cured sealing layer has low adhesion, so that when adjacent optical semiconductor devices are separated from each other in a tiled state, they can be easily separated, and sheet damage and adhesion of adjacent optical semiconductor device sheets are unlikely to occur.

The optical semiconductor device may be a tiled arrangement of individual optical semiconductor devices. In other words, the optical semiconductor device may be a tiled arrangement of multiple optical semiconductor devices in a planar direction.

Figure 3 shows one embodiment of an optical semiconductor device fabricated by arranging multiple optical semiconductor devices. The optical semiconductor device 20 shown in Figure 3 is a tiled arrangement (tiling) of multiple optical semiconductor devices 10 in the planar direction, with four in the vertical direction and four in the horizontal direction, for a total of 16 devices. 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, and there is little risk of damage to the side of the sealing portion or adhesion of the resin that has been lost on the side of the sealing portion from one adjacent optical semiconductor device to the other.

The optical semiconductor device is preferably a backlight for a liquid crystal screen, and particularly preferably a full-surface direct-light type backlight. In addition, the backlight can be combined with a display panel to form an image display device. When the optical semiconductor device is a backlight for a liquid crystal screen, the optical semiconductor element is an LED element. For example, in the backlight, a metal wiring layer for sending a light emission control signal to each LED element is laminated on the substrate. Each LED element emitting light of each color, red (R), green (G), and blue (B), is alternately arranged on the substrate of the display panel via a metal wiring layer. The metal wiring layer is formed of a metal such as copper, and reflects the light emitted by each LED element, thereby reducing the visibility of the image. In addition, the light emitted by each LED element of each color of RGB is mixed, reducing the contrast.

The optical semiconductor device is preferably a self-luminous display device. The self-luminous display device can be combined with a display panel as necessary to form an image display device. When the optical semiconductor device is a self-luminous display device, the optical semiconductor element is an LED element. Examples of the self-luminous display device include an organic electroluminescence (organic EL) display device. For example, in the self-luminous 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 emitting light of each color, red (R), green (G), and blue (B), is alternately arranged on the substrate via a metal wiring layer. The metal wiring layer is formed of a metal such as copper, and the light emission degree of each LED element is adjusted to display each color.

The optical semiconductor element encapsulation sheet of the present invention can be used in optical semiconductor devices that are folded when used, such as optical semiconductor devices having a foldable image display device (flexible display) (particularly, a foldable image display device (foldable display)). Specifically, it can be used in foldable backlights and foldable self-luminous display devices.

The optical semiconductor element encapsulation sheet of the present invention has excellent embeddability for optical semiconductor elements, and can therefore be preferably used when the optical semiconductor device is a mini LED display device or a micro LED display device.

[Method of manufacturing optical semiconductor device]
The optical semiconductor device can be produced, for example, by a production method including at least a dicing step of dicing a laminate including a substrate, an optical semiconductor element disposed on the substrate, and a cured product obtained by curing the radiation-curable resin layer of the sheet for encapsulating an optical semiconductor element of the present invention, which encapsulates the optical semiconductor element, to obtain an optical semiconductor device. The cured product is a cured product obtained by curing the sheet for encapsulating an optical semiconductor element of the present invention by irradiation with radiation, and specifically includes a cured encapsulating layer obtained by curing the radiation-curable resin layer in the sheet for encapsulating an optical semiconductor element of the present invention by irradiation with radiation.

When the radiation-curable resin layer is irradiated with radiation and cured, curing is inhibited on the side where oxygen is present, and curing is likely to be insufficient. In contrast, according to the above-mentioned manufacturing method including the above-mentioned dicing step, for a laminate including a cured product of a sheet for encapsulating optical semiconductor elements, including a cured encapsulating layer obtained by curing the radiation-curable resin layer by radiation irradiation, the side end portion that is insufficiently cured in the dicing step can be cut off and removed to obtain an optical semiconductor device in which an area that has been sufficiently cured and has reduced adhesion is exposed on the side. In the optical semiconductor device manufactured in this way, the adhesion of the side surface of the radiation-curable resin layer after curing is sufficiently reduced, so that when adjacent optical semiconductor devices are separated in a tiling state, the sheet is less likely to be damaged or the sheets of adjacent optical semiconductor devices are less likely to adhere to each other.

The manufacturing method may further include a radiation exposure step of irradiating radiation to a laminate including the substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet that encapsulates the optical semiconductor element, thereby curing the radiation curable resin layer and obtaining the cured product.

The manufacturing method may include a sealing step of bonding the sheet for sealing an optical semiconductor element to the optical semiconductor element provided on the substrate and sealing the optical semiconductor element with the sealing portion before the radiation irradiation step.

The above manufacturing method may further include a tiling step in which multiple optical semiconductor devices obtained in the dicing step are arranged in contact with each other in a planar direction. Below, the manufacturing method of the optical semiconductor device 10 shown in FIG. 2 and the optical semiconductor device 20 shown in FIG. 3 will be described with appropriate reference.

(Sealing process)
In the above-mentioned encapsulation step, the sheet for encapsulating optical semiconductor elements of the present invention is attached to a substrate on which an optical semiconductor element is arranged, and the optical semiconductor element is encapsulated by the encapsulation part. In the above-mentioned encapsulation step, specifically, as shown in FIG. 4, the radiation non-curable adhesive layer 32 of the sheet for encapsulating optical semiconductor elements 1 from which the release liner 4 has been peeled is arranged so as to face the surface of the substrate 5 on which the optical semiconductor element 6 is arranged, and the sheet for encapsulating optical semiconductor elements 1 is attached to the surface of the substrate 5 on which the optical semiconductor element 6 is arranged, and the optical semiconductor element 6 is embedded in the encapsulation part 3 as shown in FIG. 5. As shown in FIG. 4, the substrate 5 used for encapsulation extends wider in the planar direction than the substrate 5 in the optical semiconductor device 10 shown in FIG. 2, and the optical semiconductor element 6 is not arranged near the end of the substrate 5. In addition, the sheet for encapsulating optical semiconductor elements 1 to be affixed extends wider in the planar direction than the substrate 5 to be affixed. That is, the area of the surface of the sheet for encapsulating optical semiconductor elements 1 to be affixed in the encapsulation step facing the substrate 5 is larger than the area of the surface of the substrate 5 to be affixed in the encapsulation step facing the sheet for encapsulating optical semiconductor elements 1. This is because the area of the laminate of the sheet 1 for encapsulating an optical semiconductor element and the substrate 5 that is to be used for the optical semiconductor device is sufficiently cured in the subsequent radiation exposure process, while the areas near the edges of the sheet 1 for encapsulating an optical semiconductor element and the substrate 5 that may not be sufficiently cured are diced and removed in the subsequent dicing process.

The temperature during the lamination is, for example, within the range of room temperature to 110°C. In addition, the pressure may be reduced or pressurized during the lamination. By reducing the pressure or applying pressure, it is possible to prevent the formation of voids between the sealing portion and the substrate or the optical semiconductor element. In the sealing step, it is preferable to laminate the optical semiconductor element sealing sheet under reduced pressure and then apply pressure. When reducing the pressure, the pressure is, for example, 1 to 100 Pa, and the depressurization time is, for example, 5 to 600 seconds. When applying pressure, the pressure is, for example, 0.05 to 0.5 MPa, and the depressurization time is, for example, 5 to 600 seconds.

(Radiation Irradiation Step)
In the radiation irradiation step, radiation is irradiated to a laminate (e.g., a laminate obtained in the encapsulation step) in which the sheet for encapsulating an optical semiconductor element is attached to the substrate on which the optical semiconductor element is disposed, to cure the radiation curable resin layer. Specifically, in the radiation irradiation step, as shown in FIG. 6, the radiation curable resin layer 31 is cured to form a cured encapsulation layer 31', and a cured product 1' of the sheet for encapsulating an optical semiconductor element 1 is obtained. As described above, examples of the radiation include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays. Among these, ultraviolet rays are preferred. The temperature during radiation irradiation is, for example, within the range of room temperature to 100° C., and the irradiation time is, for example, 1 minute to 1 hour.

(Dicing process)
In the dicing step, a laminate (e.g., a laminate having undergone the radiation irradiation step) including a substrate, an optical semiconductor element disposed on the substrate, and a cured product of the optical semiconductor element encapsulation sheet of the present invention that encapsulates the optical semiconductor element is diced. Here, in the laminate to be subjected to the dicing step, the cured product 1' of the optical semiconductor element encapsulation sheet and the substrate 5 extend wider in the planar direction than the optical semiconductor device 10 finally obtained, as described above. Then, in the dicing step, the side end portions of the cured product of the optical semiconductor element encapsulation sheet and the substrate are diced and removed. Specifically, dicing is performed at the position of the dashed line shown in FIG. 7 to remove the side end portions. The dicing can be performed by a known or conventional method, for example, a method using a dicing blade or laser irradiation. In this manner, for example, the optical semiconductor device 10 shown in FIG. 2 can be manufactured.

Here, in the above manufacturing method, it is important to perform dicing in a state where the radiation curable resin layer is cured, for example, by undergoing the above radiation irradiation step. If dicing is performed in a state where the radiation curable resin layer is not cured, when the side end of the sheet for sealing optical semiconductor elements is to be pulled apart and removed after dicing, the adhesion between the radiation curable resin layers in the side end to be removed and the remaining optical semiconductor device is high, and they may adhere to each other and attract each other, resulting in defects in the radiation curable resin layer in the remaining optical semiconductor device, or a part of the radiation curable resin layer of the side end to be removed may be transferred and attached to the remaining optical semiconductor device. In contrast, by providing the above dicing step in which dicing is performed in a state where the radiation curable resin layer is cured, the radiation curable resin layer is cured to become a cured sealing layer, so that the adhesion of the side of the diced part is low, and the occurrence of the above defects can be suppressed.

In addition, when the radiation curable resin layer is irradiated with radiation and cured, curing is inhibited on the side where oxygen is present, and curing is likely to be insufficient. In contrast, according to the manufacturing method including the dicing step, in a state where the radiation curable resin layer is cured, the end portion where the curing is insufficient in the dicing step is cut off and removed, thereby obtaining an optical semiconductor device with sufficiently cured side and reduced adhesion. In the optical semiconductor device manufactured in this way, the adhesion of the side is sufficiently reduced after the radiation curable resin layer is cured, so that when adjacent optical semiconductor devices are separated in a tiling state, the sheet is unlikely to be damaged or the sheets of the adjacent optical semiconductor devices are unlikely to adhere to each other. On the other hand, if the dicing step is not included, the side where the curing is insufficient comes into contact with the adjacent optical semiconductor device during tiling, so that when adjacent optical semiconductor devices are separated from each other, the side surfaces are likely to adhere to each other and attract each other, causing defects such as damage to the radiation curable resin layer in one optical semiconductor device or a part of the radiation curable resin layer in the other optical semiconductor device being transferred and attached to one optical semiconductor device.

(Tiling process)
In the tiling step, the multiple optical semiconductor devices obtained in the dicing step are arranged in a tiled manner so as to be in contact with each other in a planar direction. In this manner, for example, the optical semiconductor device 20 shown in Fig. 3 can be manufactured. The optical semiconductor device obtained by tiling has excellent sealing properties for optical semiconductor elements, and is less likely to suffer from sheet damage or adhesion of the sheets of adjacent optical semiconductor devices when the adjacent optical semiconductor devices are separated from each other.

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

Example 1
<TAC film/binder adhesive layer>
As monomer components, 2-ethylhexyl acrylate (2EHA) 69.7 parts by mass, 2-methoxyethyl acrylate (MEA) 10 parts by mass, 2-hydroxyethyl acrylate (HEA) 13 parts by mass, N-vinyl-2-pyrrolidone (NVP) 6 parts by mass, N-hydroxyethyl acrylamide (HEAA) 1.3 parts by mass, 2,2'-azobisisobutyronitrile 0.1 parts by mass as a polymerization initiator, and ethyl acetate 200 parts by mass as a polymerization solvent were charged into a separable flask and stirred for 1 hour while introducing nitrogen gas. In this way, after removing oxygen from the polymerization system, the temperature was raised to 63 ° C., reacted for 10 hours, and ethyl acetate was added to obtain an acrylic polymer solution with a solid content concentration of 30% by mass. To 100 parts by mass of the acrylic polymer, 0.2 parts by mass of an isocyanate-based crosslinking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals, Inc.) as a crosslinking agent, 0.15 parts by mass of γ-glycidoxypropyltrimethoxysilane (product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent, and 0.2 parts by mass of a polyol obtained by adding propylene oxide to ethylenediamine as a crosslinking accelerator (product name "EDP-300", manufactured by ADEKA Corporation) were added to prepare a pressure-sensitive adhesive composition (solution). Next, the pressure-sensitive adhesive composition (solution) was applied to the release-treated surface of a release liner (separator) (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying was 25 μm, and the mixture was heated and dried at normal pressure at 60 ° C. for 1 minute and at 155 ° C. for 1 minute to obtain a double-sided pressure-sensitive adhesive sheet as a binder pressure-sensitive adhesive layer. Then, the adhesive surface of the binder adhesive layer was laminated to the untreated surface of a triacetyl cellulose (TAC) film (product name "DSR3-LR", manufactured by Dai Nippon Printing Co., Ltd., total thickness 45 μm, anti-glare/anti-reflection treatment) using a hand roller so as to avoid trapping air bubbles. In this way, a laminate having a configuration of [TAC film/binder adhesive layer/release liner] was produced.

<PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer>
(UV curable adhesive layer)
189.77 parts by mass of butyl acrylate (BA), 38.04 parts by mass of cyclohexyl acrylate (CHA), 85.93 parts by mass of 2-hydroxyethyl acrylate (HEA), 0.94 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 379.31 parts by mass of methyl ethyl ketone as a polymerization solvent were placed in a 1L round-bottom separable flask, a separable cover, a separating funnel, a thermometer, a nitrogen inlet tube, a Liebig condenser, a vacuum seal, a stirring rod, and a stirring blade in a polymerization experimental apparatus equipped with the stirring rod and the stirring blade, and the mixture was substituted with nitrogen at room temperature for 6 hours while stirring. Thereafter, the mixture was polymerized by holding at 65°C for 4 hours and at 75°C for 2 hours while stirring under nitrogen inflow, to obtain a resin solution.
The resin solution was then cooled to room temperature. Thereafter, 57.43 parts by mass of 2-isocyanatoethyl methacrylate (product name "Karenz MOI", manufactured by Showa Denko K.K.) was added to the resin solution as a compound having a polymerizable carbon-carbon double bond. Furthermore, 0.29 parts by mass of dibutyltin(IV) dilaurate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred at 50°C for 24 hours in an air atmosphere to obtain a base polymer.
1.5 parts by mass of an isocyanate compound (product name "Coronate L", manufactured by Tosoh Corporation, solid content 75% by mass) and 1 part by mass of 2,2-dimethoxy-1,2-diphenyl-1-one (product name "Omnirad 651", manufactured by IGM Resins Italia Srl) were mixed with 100 parts by mass of the solid content of the obtained base polymer. The solid content was adjusted to 20 to 40% by mass using toluene as a dilution solvent, to obtain a pressure-sensitive adhesive solution (1).

This adhesive solution (1) was applied to the treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) so that the thickness after drying would be 112.5 μm, and the film was heated and dried at normal pressure at 50°C for 1 minute and at 125°C for 5 minutes to form an ultraviolet-curable adhesive layer (1). On the other hand, the adhesive solution (1) obtained above was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 112.5 μm, and the film was heated and dried at normal pressure at 50°C for 1 minute and at 125°C for 5 minutes to form an ultraviolet-curable adhesive layer (2).

Then, the adhesive layer surfaces of the ultraviolet-curable adhesive layer (1) formed on the PET film and the ultraviolet-curable adhesive layer (2) formed on the release liner were bonded together using a hand roller while being careful not to trap air bubbles, to form one ultraviolet-curable adhesive layer. The release liner was then peeled off. In this way, a laminate having a configuration of [PET film/ultraviolet-curable adhesive layer] was produced.

(Radiation non-curable adhesive layer)
Acrylic acid butyl acrylate (BA) 189.77 parts by mass, cyclohexyl acrylate (CHA) 38.04 parts by mass, 2-hydroxyethyl acrylate (HEA) 85.93 parts by mass, 2,2'-azo as a polymerization initiator 0.94 parts by mass of bisisobutyronitrile and 379.31 parts by mass of methyl ethyl ketone as a polymerization solvent were placed in a 1 L round-bottom separable flask equipped with a separable cover, a separating funnel, a thermometer, a nitrogen inlet tube, a Liebig condenser, and The mixture was placed in a polymerization experiment apparatus equipped with a vacuum seal, a stirring rod, and a stirring blade, and the mixture was purged with nitrogen at room temperature for 6 hours while stirring. After that, the mixture was purged with nitrogen at 65°C for 4 hours while stirring. The mixture was then kept at 75° C. for 2 hours to polymerize, yielding a resin solution.
The obtained resin solution was mixed with 1.5 parts by mass of an isocyanate compound (product name "Coronate L", manufactured by Tosoh Corporation, solid content 75% by mass) per 100 parts by mass of the solid content of the base polymer. As a dilution solvent, the solid content was adjusted to 20 to 40 mass %, to obtain a pressure-sensitive adhesive solution (2).

This adhesive solution (2) was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 25 μm, and the solution was dried by heating at 125°C for 2 minutes under normal pressure to form a non-radiation-curable adhesive layer.

(PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer)
The non-radiation-curable adhesive layer was attached to the surface of the ultraviolet-curable adhesive layer of a laminate having a structure of [PET film/ultraviolet-curable adhesive layer] using a hand roller so as to avoid air bubbles being trapped in. In this way, a laminate having a structure of [PET film/ultraviolet-curable adhesive layer/non-radiation-curable adhesive layer/release liner] was produced.

<Optical semiconductor element encapsulation sheet>
The release liner was peeled off from the laminate having the structure of [TAC film/binder adhesive layer/release liner], and the exposed binder adhesive layer surface was attached to the PET film surface of the laminate having the structure of [PET film/ultraviolet ray curable adhesive layer/non-radiation curable adhesive layer/release liner] using a hand roller so as not to trap air bubbles. After that, aging was performed at 50° C. for 48 hours, and the optical semiconductor element encapsulation sheet of Example 1 having the layer structure of [TAC film/binder adhesive layer/PET film/ultraviolet ray curable adhesive layer/non-radiation curable adhesive layer/release liner] was produced.

Example 2
An optical semiconductor element encapsulation sheet of Example 2 was produced in the same manner as in Example 1, except that the thickness of the ultraviolet-curable pressure-sensitive adhesive layer (1) was 100 μm, the thickness of the ultraviolet-curable pressure-sensitive adhesive layer (2) was 100 μm (total thickness of the ultraviolet-curable pressure-sensitive adhesive layers: 200 μm), and the thickness of the non-radiation-curable pressure-sensitive adhesive layer was 50 μm.

Example 3
<PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer>
(UV curable adhesive layer)
The adhesive solution (1) prepared in Example 1 was applied onto a treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) so that the thickness after drying would be 125 μm, and the applied solution was heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form an ultraviolet-curable adhesive layer.

(Radiation non-curable adhesive layer)
The adhesive solution (2) prepared in Example 1 was applied onto the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 125 μm. The coating was dried by heating at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form a non-radiation curable pressure-sensitive adhesive layer.

<Optical semiconductor element encapsulation sheet>
An optical semiconductor element encapsulation sheet of Example 3 was produced in the same manner as in Example 1, except that the non-radiation-curable pressure-sensitive adhesive layer and the ultraviolet-curable pressure-sensitive adhesive layer obtained above were used.

Example 4
The adhesive solution (1) prepared in Example 1 was applied onto the treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) so as to have a thickness of 125 μm after drying, and heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form an ultraviolet-curable adhesive layer (1). On the other hand, the adhesive solution (1) prepared in Example 1 was applied onto the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so as to have a thickness of 125 μm after drying, and heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form an ultraviolet-curable adhesive layer (2).
Then, three layers of the above-mentioned ultraviolet-curable adhesive layer (2) prepared separately were laminated on the above-mentioned ultraviolet-curable adhesive layer (1) to prepare an ultraviolet-curable adhesive layer having a total thickness of 500 μm.

The adhesive solution (2) prepared in Example 1 was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 5 μm, and the solution was dried by heating at 125°C for 2 minutes under normal pressure to form a non-radiation-curable adhesive layer.

The optical semiconductor element encapsulation sheet of Example 4 was produced in the same manner as in Example 1, except that the non-radiation curable adhesive layer and the ultraviolet-curable adhesive layer obtained above were used.

Example 5
The adhesive solution (1) prepared in Example 1 was applied onto a treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) so that the thickness after drying would be 25 μm, and the applied solution was dried by heating at normal pressure at 50° C. for 1 minute and at 125° C. for 2 minutes to form an ultraviolet-curable adhesive layer.

The adhesive solution (2) prepared in Example 1 was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 112.5 μm, and the solution was dried by heating at normal pressure at 50°C for 1 minute and at 125°C for 5 minutes to form a non-radiation-curable adhesive layer (1).

Then, the adhesive layer surfaces of the ultraviolet-curable adhesive layer formed on the PET film and the non-radiation-curable adhesive layer (1) formed on the release liner were attached to each other using a hand roller while being careful not to trap air bubbles, and then the release liner was peeled off. In this way, a laminate having a configuration of [PET film/ultraviolet-curable adhesive layer/non-radiation-curable adhesive layer (1)] was produced.

On the other hand, the adhesive solution (2) prepared in Example 1 was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 112.5 μm, and the solution was dried by heating at normal pressure at 50°C for 1 minute and at 125°C for 5 minutes to form a non-radiation-curable adhesive layer (2).

Then, the adhesive layer surfaces of the radiation non-curable adhesive layer (1) in the laminate having the configuration of [PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer (1)] and the radiation non-curable adhesive layer (2) formed on the release liner were bonded together using a hand roller to avoid the inclusion of air bubbles, forming one non-radiation-curable adhesive layer. In this way, a laminate having the configuration of [PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer/release liner] was produced.

The release liner was peeled off from the laminate having the structure of [TAC film/binder adhesive layer/release liner] prepared in Example 1, and the exposed binder adhesive layer surface was attached to the PET film surface of the laminate having the structure of [PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer/release liner] using a hand roller, taking care not to introduce air bubbles. After that, aging was performed at 50°C for 48 hours, and the optical semiconductor element encapsulation sheet of Example 5 having the layer structure of [TAC film/binder adhesive layer/PET film/UV-curable adhesive layer/non-radiation-curable adhesive layer/release liner] was prepared.

Comparative Example 1
The adhesive solution (2) prepared in Example 1 was applied onto the treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) to a thickness of 125 μm after drying, and heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form a non-radiation-curable adhesive layer (1). On the other hand, the adhesive solution (2) prepared in Example 1 was applied onto the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) to a thickness of 125 μm after drying, and heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form a non-radiation-curable adhesive layer (2).

Then, the adhesive layer surfaces of the non-radiation-curable adhesive layer (1) formed on the PET film and the non-radiation-curable adhesive layer (2) formed on the release liner were bonded together using a hand roller while being careful not to trap air bubbles, to form one non-radiation-curable adhesive layer. In this way, a laminate having a configuration of [PET film/non-radiation-curable adhesive layer/release liner] was produced.

The release liner was peeled off from the laminate having the structure of [TAC film/binder adhesive layer/release liner] prepared in Example 1, and the exposed binder adhesive layer surface was attached to the PET film surface of the laminate having the structure of [PET film/non-radiation curable adhesive layer/release liner] using a hand roller while being careful not to introduce air bubbles. After that, aging was performed at 50°C for 48 hours, and a sheet for encapsulating optical semiconductor elements of Comparative Example 1 having a layer structure of [TAC film/binder adhesive layer/PET film/non-radiation curable adhesive layer/release liner] was prepared.

Comparative Example 2
The adhesive solution (1) prepared in Example 1 was applied onto the treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) so as to have a thickness of 125 μm after drying, and heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form an ultraviolet-curable adhesive layer (1). On the other hand, the adhesive solution (1) prepared in Example 1 was applied onto the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so as to have a thickness of 125 μm after drying, and heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 5 minutes to form an ultraviolet-curable adhesive layer (2).

Then, the adhesive layer surfaces of the ultraviolet-curable adhesive layer (1) formed on the PET film and the ultraviolet-curable adhesive layer (2) formed on the release liner were bonded together using a hand roller while being careful not to trap air bubbles, to form one ultraviolet-curable adhesive layer. In this way, a laminate having a configuration of [PET film/ultraviolet-curable adhesive layer/release liner] was produced.

The release liner was peeled off from the laminate having the structure of [TAC film/binder adhesive layer/release liner] prepared in Example 1, and the exposed binder adhesive layer surface was attached to the PET film surface of the laminate having the structure of [PET film/UV-curable adhesive layer/release liner] using a hand roller, taking care not to introduce air bubbles. After that, aging was performed at 50°C for 48 hours, and a sheet for encapsulating optical semiconductor elements of Comparative Example 2 having a layer structure of [TAC film/binder adhesive layer/PET film/UV-curable adhesive layer/release liner] was prepared.

Comparative Example 3
The adhesive solution (2) prepared in Example 1 was applied onto a treated surface of a PET film (product name "T912E75 (UE80-)", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) so as to give a dried thickness of 25 μm, and then heated and dried at normal pressure at 50° C. for 1 minute and at 125° C. for 2 minutes to form a non-radiation curable adhesive layer.

The adhesive solution (1) prepared in Example 1 was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 112.5 μm, and the solution was dried by heating at normal pressure at 50°C for 1 minute and at 125°C for 5 minutes to form an ultraviolet-curable adhesive layer (1).

Then, the adhesive layer surfaces of the non-radiation curable adhesive layer formed on the PET film and the ultraviolet-curable adhesive layer (1) formed on the release liner were attached to each other using a hand roller while being careful not to trap air bubbles, and then the release liner was peeled off. In this way, a laminate having a configuration of [PET film/non-radiation curable adhesive layer/ultraviolet-curable adhesive layer (1)] was produced.

On the other hand, the adhesive solution (1) prepared in Example 1 was applied to the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying would be 112.5 μm, and the solution was dried by heating at normal pressure at 50°C for 1 minute and at 125°C for 5 minutes to form an ultraviolet-curable adhesive layer (2).

Then, the adhesive layer surfaces of the ultraviolet-curable adhesive layer (1) in the laminate having the configuration of [PET film/non-radiation-curable adhesive layer/ultraviolet-curable adhesive layer (1)] and the ultraviolet-curable adhesive layer (2) formed on the release liner were bonded together using a hand roller so as to avoid the inclusion of air bubbles, forming one ultraviolet-curable adhesive layer. In this way, a laminate having the configuration of [PET film/non-radiation-curable adhesive layer/ultraviolet-curable adhesive layer/release liner] was produced.

The release liner was peeled off from the laminate having the structure of [TAC film/binder adhesive layer/release liner] prepared in Example 1, and the exposed binder adhesive layer surface was attached to the PET film surface of the laminate having the structure of [PET film/non-radiation curable adhesive layer/UV curable adhesive layer/release liner] using a hand roller so as not to introduce air bubbles. After that, aging was performed at 50°C for 48 hours, and a sheet for encapsulating optical semiconductor elements of Comparative Example 3 was prepared, having a layer structure of [TAC film/binder adhesive layer/PET film/non-radiation curable adhesive layer/UV curable adhesive layer/release liner].

<Evaluation>
The ultraviolet-curable pressure-sensitive adhesive layers and the sheets for encapsulating optical semiconductor elements obtained in the examples and comparative examples were evaluated as follows. The results are shown in the table below.

(1) Hardness by nanoindentation method The optical semiconductor element encapsulation sheets obtained in the examples and comparative examples were irradiated with ultraviolet light from the TAC film side under the following ultraviolet irradiation conditions to cure the ultraviolet curable adhesive layer. After that, the sheets were frozen at -40°C to -30°C for 10 to 15 minutes, and then cut in the thickness direction using an ultramicrotome under the frozen conditions to expose the cross section of the cured ultraviolet curable adhesive layer. Then, the optical semiconductor element encapsulation sheet with the exposed cross section was fixed to a metal stage attached to the device by solidifying Pentel correction fluid (product number "XEZL1-W"), and then a polyimide film was attached to the window of the device to block light and then evaluation was performed. Using a nanoindenter (product name "Tribolindenter", manufactured by HYSITRON Inc.), nanoindentation measurement was performed on the surface of the cured ultraviolet curable adhesive layer under the following nanoindentation measurement conditions. The obtained hardness is shown in Table 1.
<Ultraviolet ray irradiation conditions>
Ultraviolet irradiation device: Product name "UM810", manufactured by Nitto Seiki Co., Ltd. Light source: High pressure mercury lamp Irradiation intensity: 50 mW/cm ² (Measuring device: Product name "Ultraviolet illuminometer UT-101", manufactured by Ushio Inc.)
Irradiation time: 100 seconds Accumulated light quantity: 5000 mJ/ ^cm2
<Nanoindentation measurement conditions>
Indenter used: Berkovich (triangular pyramid type)
Measurement method: Single indentation measurement Measurement temperature: 23°C
Press depth setting: 3.0 μm
Load speed: 500nm/s
Unloading speed: 500nm/s

(2) Dicing Evaluation For the optical semiconductor element encapsulation sheets obtained in the examples and comparative examples, the entire surface of the adhesive layer exposed by peeling off the release liner was attached to the pattern surface of a substrate (product name "Lead-free universal substrate ICB93SGPBF", manufactured by Sanhayato Co., Ltd.) with a hand roller to prepare a test sample. The adhesive layer area of the optical semiconductor element encapsulation sheet is larger than the area of the substrate to be attached. The lamination was performed in an environment of a temperature of 22°C and a humidity of 50% so as not to introduce air bubbles. Thereafter, the above test sample was irradiated with ultraviolet light from the TAC film side under the following ultraviolet light irradiation conditions (1) to cure the ultraviolet-curable adhesive layer. The test sample using the optical semiconductor element encapsulation sheet of Comparative Example 1, which does not have an ultraviolet-curable adhesive layer, was not irradiated with ultraviolet light.
<Ultraviolet irradiation conditions (1)>
Ultraviolet irradiation device: Product name "UM810", manufactured by Nitto Seiki Co., Ltd. Light source: High pressure mercury lamp Irradiation intensity: 50 mW/cm ² (Measuring device: Product name "Ultraviolet illuminometer UT-101", manufactured by Ushio Inc.)
Irradiation time: 100 seconds Accumulated light quantity: 5000 mJ/ ^cm2

After the ultraviolet irradiation, a dicing tape (product name "NBD-5172K", manufactured by Nitto Denko Corporation) was attached to the surface of the substrate on the side of the test sample on which the optical semiconductor element encapsulation sheet was not attached. A dicing ring for dicing was attached to the adhesive surface of the dicing tape. After attachment, the sample was left for 30 minutes in a light-shielded environment at a temperature of 22°C. Then, the laminate of the test sample and the dicing tape was subjected to blade dicing at a position 5 mm inward from the side edge of the substrate under the following dicing conditions.
<Dicing conditions>
Dicing device: Product name "DFD-6450", manufactured by Disco Corporation Cutting method: Single cut Dicing speed: 30 mm/sec Dicing blade: Product name "P1A861 SDC400N75BR597", manufactured by Disco Corporation Dicing blade rotation speed: 30,000 rpm
Blade height: 85 μm
Water volume: 1.5 L/min Dicing interval: 10 mm
Distance of one dicing: Full length of test sample

The blade used for dicing was one that had been dress diced using the following method.
A dicing ring and a board (product name "DRESSER BOARD BGCA0172", manufactured by Disco Corporation) were attached to the adhesive layer of a dicing tape (product name "NBD-7163K", manufactured by Nitto Denko Corporation) to prepare a workpiece for processing. The obtained workpiece was then diced under the following dress dicing conditions to obtain a blade for the blade dicing.
<Dress dicing conditions>
Dicing equipment: Product name "DFD-6450", manufactured by Disco Corporation Cutting method: Single cut Dicing speed: 55 mm/sec Dicing blade: Product name "P1A861 SDC400N75BR597" (new), manufactured by Disco Corporation Dicing blade rotation speed: 35,000 rpm
Blade height: 500 μm
Water volume: 1.5 L/min. Dicing distance per time: Total length of board. Dicing interval: 1 mm interval. Dicing times: 100 times.

After the blade dicing, ultraviolet light was irradiated from the dicing tape base material side under the ultraviolet light irradiation conditions (2) described below to reduce the peel strength of the dicing tape to the substrate.
<Ultraviolet irradiation conditions (2)>
Ultraviolet irradiation device: Product name "UM810", manufactured by Nitto Seiki Co., Ltd. Light source: High pressure mercury lamp Irradiation intensity: 50 mW/cm ² (Measuring device: Product name "Ultraviolet illuminometer UT-101", manufactured by Ushio Inc.)
Irradiation time: 10 seconds Accumulated light quantity: 500 mJ/ ^cm2

Then, the laminate of the test sample and the substrate, cut into strips by blade dicing, was peeled off from the dicing tape, and those in which peeling of the test sample from the substrate was confirmed during dicing were rated as "B," and those in which peeling was not confirmed were rated as "A."

(3) Stringiness evaluation Two laminates of the test sample and the substrate cut into strips in the above dicing evaluation were peeled off from the dicing tape. Next, the two laminates were bonded together with the cut surfaces exposed by dicing, and left in that state for 24 hours in an environment at a temperature of 50°C. The two bonded strips were then removed and left in an environment at a temperature of 22°C and humidity of 50% for 3 hours. Then, an attempt was made to peel the bonded cut surfaces off by hand, and those that could not be peeled off or could be peeled off but had noticeable stringiness of the adhesive layer were rated as "D", those that could be peeled off but had slight stringiness of the adhesive layer were rated as "C", those that required force to peel off but could be peeled off without stringiness of the adhesive layer were rated as "B", and those that did not require any particular force to peel off and could be peeled off without stringiness of the adhesive layer were rated as "A".

As shown in Table 1, the optical semiconductor element encapsulation sheet (Example) of the present invention had good results in the dicing evaluation, and was evaluated as having excellent adhesion of the sheet to the optical semiconductor element and the substrate, and excellent encapsulation of the optical semiconductor element. In addition, the stringiness evaluation had good results, and it was evaluated that the adhesion of the encapsulation side surface was low, and that when adjacent optical semiconductor devices were pulled apart, the sheet was unlikely to be damaged or the sheets of adjacent optical semiconductor devices were unlikely to adhere to each other.

On the other hand, when there was no UV-curable adhesive layer (Comparative Example 1), the results of the stringiness evaluation were poor. Also, when there was no radiation-non-curable adhesive layer (Comparative Example 2), and when the layer located on the surface on the optical semiconductor element side was an UV-curable adhesive layer (Comparative Example 3), the results of the dicing evaluation were poor, and the sealing ability of the optical semiconductor element was evaluated to be poor.

Reference Signs List 1 Optical semiconductor element encapsulation sheet 1' Cured product of optical semiconductor element encapsulation sheet 2 Substrate portion 21 Optical film 22 Pressure-sensitive adhesive layer 23 Plastic film 3 Sealing portion 31 Radiation-curable resin layer 31' Cured sealing layer 32 Non-radiation-curable pressure-sensitive adhesive layer 4 Release liner 5 Substrate 6 Optical semiconductor device 10, 20 Optical semiconductor device

Claims (16)

A sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, comprising:
a substrate and a sealing portion provided on one surface of the substrate for sealing the optical semiconductor element;
the encapsulating portion has a non-radiation-curable pressure-sensitive adhesive layer located on a surface facing the optical semiconductor element when the optical semiconductor element is encapsulated, and a radiation-curable resin layer laminated on the non-radiation-curable pressure-sensitive adhesive layer,
the substrate, the radiation curable resin layer, and the non-radiation curable pressure-sensitive adhesive layer are laminated in this order;
the radiation is at least one selected from the group consisting of an electron beam, an ultraviolet ray, an α-ray, a β-ray, a γ-ray, and an X-ray;
The non-radiation-curable pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive, The sheet for encapsulating an optical semiconductor element according to claim 1 , wherein the radiation curable resin layer is thicker than the non-radiation curable pressure-sensitive adhesive layer. The sheet for encapsulating an optical semiconductor element according to claim 1 , wherein the encapsulating portion includes a layer containing a colorant. The sheet for encapsulating an optical semiconductor element according to any one of claims 1 to 3, comprising a layer having antiglare properties and/or antireflection properties. 5. The sheet for encapsulating an optical semiconductor element according to claim 1, further comprising a layer containing a polyester resin and/or a polyimide resin as a main component. 6. The sheet for encapsulating optical semiconductor elements according to claim 1, wherein a cross section of the radiation curable resin layer after curing has a hardness of 1.4 MPa or more at a temperature of 23° C. as measured by a nanoindentation method. The sheet for encapsulating optical semiconductor elements according to any one of claims 1 to 6, wherein the non-radiation curable adhesive layer and the radiation curable resin layer are directly laminated without any other layer therebetween. 8. An optical semiconductor device comprising: a substrate; an optical semiconductor element disposed on the substrate; and a cured product obtained by curing the radiation-curable resin layer of the optical semiconductor element encapsulation sheet according to claim 1, which encapsulates the optical semiconductor element. The optical semiconductor device according to claim 8, which is a backlight for a liquid crystal display. An image display device comprising the backlight and a display panel according to claim 9. The optical semiconductor device according to claim 8, which is a self-luminous display device. An image display device comprising the self-luminous display device according to claim 11. 8. A method for producing an optical semiconductor device, comprising: a dicing step of dicing a laminate comprising a substrate, an optical semiconductor element disposed on the substrate, and a cured product obtained by curing the radiation-curable resin layer of the sheet for encapsulating an optical semiconductor element according to claim 1, which encapsulates the optical semiconductor element, to obtain an optical semiconductor device. 14. The method for producing an optical semiconductor device according to claim 13, further comprising a radiation exposure step of irradiating a laminate including the substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet that encapsulates the optical semiconductor element with radiation to cure the radiation curable resin layer and obtain the cured product. 15. The method for producing an optical semiconductor device according to claim 14, further comprising a sealing step of bonding the sheet for sealing an optical semiconductor element to the optical semiconductor element provided on the substrate to seal the optical semiconductor element with the sealing portion, and then performing the radiation irradiation step. The method for producing an optical semiconductor device according to any one of claims 13 to 15, further comprising 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 a planar direction.

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