JP7841850B2 - Adhesive sheet for transferring electronic components and method for processing electronic components using the adhesive sheet for transferring electronic components - Google Patents

Description

This invention relates to an adhesive sheet for transferring electronic components and a method for processing electronic components using the adhesive sheet.

Conventionally, when transferring electronic components from one component to another, the electronic components are received using an adhesive sheet, and then transferred to the other component. For example, when incorporating an LED chip into a device, the LED chip formed on the component is first transferred to an adhesive sheet, and then transferred from the adhesive sheet to the designated device or component.

As described above, an adhesive sheet equipped with an active energy ray-curable adhesive layer can be used as an adhesive sheet for temporarily fixing electronic components (i.e., receiving and then transferring electronic components). Such an adhesive sheet exhibits a predetermined adhesive strength before irradiation with active energy rays (e.g., ultraviolet light), allowing it to securely fix electronic components. After irradiation with active energy rays, the adhesive layer hardens, reducing its adhesive strength and facilitating the pickup of electronic components.

In recent years, there has been a growing trend towards the widespread use of miniaturized and thin electronic components. Because these components often lack sufficient contact area with the adhesive sheet and are prone to damage during removal, adhesive sheets equipped with an active energy ray-curable adhesive layer that balances both fixation and release properties are preferred. However, particularly with miniaturized and thin electronic components (e.g., 100 μm square or less, 30 μm thickness or less), when the electronic component is received and fixed, it becomes embedded in the adhesive layer to a high degree. This results in a problem where, even after the adhesive layer has hardened, the component is difficult to remove and prone to damage.

Japanese Patent Publication No. 2020-53558

This invention was made to solve the above-mentioned conventional problems, and its objective is to provide an adhesive sheet for transferring electronic components that offers excellent fixing and peeling properties for electronic components, preventing damage and other malfunctions even when the electronic components are small and thin, and enabling the receiving and transfer of such electronic components.

The adhesive sheet for transferring electronic components according to the present invention comprises a substrate and an adhesive layer disposed on at least one side of the substrate, wherein the adhesive layer has a nanoindenter modulus of 500 MPa or less at 25°C after irradiation with ultraviolet light at 460 mJ/ ^cm² .
In one embodiment, the amount of sinking of the adhesive sheet using TMA in a 40°C environment is 3 μm to 27 μm.
In one embodiment, the thickness of the adhesive layer is 2.1 μm to 35 μm.
In one embodiment, the normal nanoindenter modulus of the adhesive layer at 25°C is 0.4 MPa or higher.
In one embodiment, the normal probe tack value of the adhesive layer is 8 N/ ^cm² or higher.
In one embodiment, the substrate is made of a polyester resin.
In one embodiment, the thickness of the substrate is 30 μm to 200 μm.
In one embodiment, the electronic component is a mini-LED or a micro-LED.
In one embodiment, the adhesive sheet for transferring electronic components comprises the adhesive layer, the substrate, and another adhesive layer in this order.
According to another aspect of the present invention, a method for processing an electronic component is provided. This processing method is a method for processing an electronic component using the above-mentioned adhesive sheet for transferring electronic components, and includes the steps of: a) transferring an electronic component placed on a first member onto the adhesive layer of the adhesive sheet; and b) picking up the electronic component with a second member and peeling the electronic component off the adhesive sheet.
In one embodiment, the electronic component is a mini-LED or a micro-LED.
In one embodiment, step b includes step b-1 of bringing the second member into contact with the electronic component on the adhesive layer, step b-2 of irradiating the adhesive sheet with active energy rays, and step b-3 of picking up the electronic component with the second member and peeling the electronic component from the adhesive sheet.
In one embodiment, the first component is a sapphire substrate.
In one embodiment, the electronic component is a micro-LED, and step a includes irradiating the sapphire substrate on which a plurality of micro-LEDs are arranged with UV laser light to transfer the micro-LEDs to the adhesive sheet.
In one embodiment, a portion of the micro-LEDs arranged on the sapphire substrate are selectively transferred to the adhesive sheet.

According to the present invention, it is possible to provide an adhesive sheet for transferring electronic components that offers excellent fixation and release properties for electronic components, preventing malfunctions even when the electronic components are small and thin, and enabling the receiving and transfer of such electronic components.

This is a schematic cross-sectional view of an adhesive sheet according to one embodiment of the present invention. This is a schematic cross-sectional view of an adhesive sheet according to another embodiment of the present invention.

A. Figure 1 is a schematic cross-sectional view of an adhesive sheet for transferring electronic components according to one embodiment of the present invention. The adhesive sheet 100 for transferring electronic components according to this embodiment comprises a base material 10 and an adhesive layer 20 disposed on at least one side of the base material 10. Figure 2 is a schematic cross-sectional view of an adhesive sheet according to another embodiment of the present invention. The adhesive sheet 200 according to this embodiment comprises an adhesive layer 20, a base material 10, and another adhesive layer 30.

The adhesive layer 20 contains an active energy ray-curable adhesive. The adhesive layer containing the active energy ray-curable adhesive hardens and its adhesive strength decreases upon irradiation with active energy rays. The adhesive sheet for transferring electronic components (hereinafter also simply referred to as the adhesive sheet) of the present invention has a predetermined adhesive strength before irradiation with active energy rays, allowing for the desirable fixation of electronic components. However, after irradiation with active energy rays, the adhesive strength decreases as described above, making it possible to easily peel off (transfer) the electronic components.

The adhesive layer 20 has a nanoindenter modulus of 500 MPa or less at 25°C after irradiation with 460 mJ/ ^cm² of ultraviolet light. The nanoindenter modulus is the modulus of elasticity obtained from the load-indenter-indenter depth curve, which is obtained by continuously measuring the load and indentation depth on the indenter when the indenter is pressed into a sample (e.g., the adhesive surface) during loading and unloading. Details of the measurement method for the nanoindenter modulus will be described later. The above ultraviolet irradiation is performed, for example, by irradiating the adhesive layer with ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, integrated light intensity: 460 mJ/ ^cm² , irradiation energy: 70 W/ ^cm² , irradiation time: 6.6 seconds) using an ultraviolet irradiation device (manufactured by Nitto Seiki Co., Ltd., product name "UM-810").

Generally, when fixing electronic components on an adhesive layer, a portion (or all) of the electronic component may become embedded in the adhesive layer, thereby achieving a predetermined fixing force. On the other hand, when removing electronic components, the embedding of the electronic component can hinder peelability. In this invention, because the nanoindenter elastic modulus of the cured adhesive layer is within the above range, the degree of freedom of movement of the electronic component in the planar direction on the adhesive layer is high. This allows for easy peeling of the electronic component even if a portion of it is embedded. Using such an adhesive sheet, even when small, thin electronic components (e.g., mini-LEDs, micro-LEDs) are attached, they can be peeled off without damaging the electronic component. Furthermore, as described above, desirable peelability is achieved, allowing for sufficient embedding of the electronic component. As a result, the adhesive sheet of this invention also exhibits excellent electronic component fixing properties.

The initial adhesive strength at 23°C when the adhesive layer of the above-mentioned adhesive sheet is attached to a stainless steel plate (SUS304) is preferably 0.1 N/20 mm to 30 N/20 mm, and more preferably 0.1 N/20 mm to 15 N/20 mm. Within this range, an adhesive sheet capable of holding electronic components well can be obtained. The adhesive strength is measured according to JIS Z 0237:2000. Specifically, the adhesive sheet is attached to a stainless steel plate (arithmetic mean surface roughness Ra: 50 ± 25 nm) by one back-and-forth motion of a 2 kg roller, left for 30 minutes at 23°C, and then peeled off under conditions of a peeling angle of 180° and a tensile speed of 300 mm/min for measurement. While the adhesive strength of the adhesive layer changes upon irradiation with active energy rays, in this specification, "initial adhesive strength" refers to the adhesive strength before irradiation with active energy rays.

In one embodiment, the adhesive layer of an adhesive sheet is attached to a stainless steel plate (SUS304), and the adhesive strength at 23°C after irradiation with 460 mJ/ ^cm² of ultraviolet light is preferably 0.01 N/20 mm to 0.3 N/20 mm, and more preferably 0.02 N/20 mm or more and less than 0.2 N/20 mm. Within this range, an adhesive sheet with excellent peelability can be obtained. Note that the adhesive strength after ultraviolet irradiation can be measured after attaching the adhesive layer to the substrate and then irradiating the adhesive surface with ultraviolet light.

The thickness of the adhesive sheet is preferably 1 μm to 300 μm, and more preferably 3 μm to 200 μm.

The above adhesive sheet preferably has a depth of indentation of 2 μm to 35 μm, more preferably 3 μm to 27 μm, even more preferably 4 μm to 25 μm, and particularly preferably 5 μm to 20 μm in a 40°C environment using a thermomechanical analyzer (TMA). Within this range, the electronic component to be adhered is adequately embedded in the adhesive layer, resulting in an adhesive sheet with excellent fixation (i.e., acceptance) and release (i.e., transfer) properties. "Depth of indentation in a 40°C environment using a TMA" refers to the depth of indentation after 20 minutes of contact between the probe and the adhesive layer using a thermomechanical analyzer (TMA). The measurement conditions are: probe diameter: 1.0 mm, mode: needle insertion mode, nitrogen gas flow rate: 50.0 ml/min, indentation load: 0.5 N, and measurement ambient temperature: 40°C.

B. Adhesive Layer As described above, the nanoindenter modulus of the adhesive layer at 25°C after UV irradiation is 500 MPa or less. More preferably, the nanoindenter modulus of the adhesive layer at 25°C after irradiation with 460 mJ/ ^cm² of UV light is 450 MPa or less, even more preferably 400 MPa or less, particularly preferably 350 MPa or less, and most preferably 300 MPa or less. Within this range, the above effect is significant. Furthermore, the nanoindenter modulus of the adhesive layer at 25°C after irradiation with 460 mJ/ ^cm² of UV light is 1 MPa or more, more preferably 5 MPa or more, even more preferably 10 MPa or more, particularly preferably 50 MPa or more, and most preferably 100 MPa or more. Within this range, an adhesive sheet with excellent fixing properties and capable of transferring electronic components with good positional accuracy can be obtained. Furthermore, the elastic modulus of the adhesive layer can be adjusted by any appropriate method, such as the composition of the adhesive constituting the adhesive layer, for example, the structure of the polymer contained in the adhesive, or the type and amount of crosslinking agent contained in the adhesive.

The normal state nanoindenter modulus of the adhesive layer at 25°C is preferably 0.1 MPa to 55 MPa, more preferably 0.2 MPa to 40 MPa, even more preferably 0.3 MPa to 30 MPa, and particularly preferably 0.3 MPa to 20 MPa. Within this range, an adhesive sheet with excellent fixation capabilities for electronic components can be obtained. "Normal state nanoindenter modulus" refers to the modulus of elasticity before irradiation with active energy rays.

In one embodiment, the normal nanoindenter modulus of the adhesive layer at 25°C is preferably 10 MPa or less, more preferably 8 MPa or less, and even more preferably 3 MPa or less. Within this range, an adhesive sheet with particularly excellent fixing properties for electronic components can be obtained.

In another embodiment, the normal nanoindenter modulus of the adhesive layer at 25°C is preferably 0.4 MPa or higher, more preferably 0.5 MPa or higher, and even more preferably 0.8 MPa or higher. Within this range, the transferability of electronic components from a predetermined material (e.g., a sapphire substrate) to an adhesive sheet is improved. Such an adhesive sheet with excellent transferability for electronic component acceptance is particularly useful in processes (e.g., PSLLO processes) where only a portion of multiple electronic components arranged on a predetermined material are selectively accepted by the adhesive sheet.

The storage modulus of the adhesive layer at 25°C is preferably 10 MPa or less, more preferably 5 MPa or less, and even more preferably 0.01 MPa to 3 MPa. "Storage modulus at normal conditions" refers to the modulus of elasticity before irradiation with active energy rays. The method for measuring the storage modulus will be described later.

The adhesive layer described above preferably has a tensile modulus of 0.05 MPa to 100 MPa at 25°C after irradiation with 460 mJ/ ^cm² of ultraviolet light, and more preferably 0.1 MPa to 70 MPa. The method for measuring the tensile modulus will be described later.

The thickness of the adhesive layer is preferably 1.5 μm to 50 μm, more preferably 2.1 μm to 35 μm, and even more preferably 3 μm to 30 μm. Within this range, the electronic component to be adhered to is adequately embedded in the adhesive layer, resulting in an adhesive sheet with excellent fixation (i.e., acceptance) and peelability (i.e., transfer).

In one embodiment, the thickness of the adhesive layer is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. By reducing the thickness of the adhesive layer, the transferability when transferring electronic components from a predetermined member (e.g., a sapphire substrate) to an adhesive sheet is improved. Such an adhesive sheet with excellent transferability when receiving electronic components is particularly useful in processes (e.g., PSLLO processes) where only a portion of multiple electronic components arranged on a predetermined member are selectively received by the adhesive sheet.

The normal probe tack value of the adhesive layer described above is preferably 8 N/ ^cm² or higher, more preferably 12 N/ ^cm² or higher, and even more preferably 15 N/ ^cm² or higher. Within this range, an adhesive sheet with excellent fixing properties for electronic components can be obtained. The upper limit of the normal probe tack value of the adhesive layer described above is, for example, 60 N/ ^cm² . The method for measuring the probe tack value will be described later. "Normal probe tack value" means the probe tack value before irradiation with active energy rays.

The adhesive layer described above preferably has a probe tack value of 15 N/ ^cm² or less, and more preferably 12 N/ ^cm² or less, after irradiation with 460 mJ/ ^cm² of ultraviolet light. Within this range, an adhesive sheet with excellent peelability can be obtained.

(Activated energy ray curing adhesive)
As described above, the adhesive layer contains an active energy ray curing type adhesive.

Examples of base polymers constituting the above adhesive include acrylic polymers, rubber polymers (e.g., natural rubber, chloroprene rubber, styrene-butadiene rubber, nitrile rubber, etc.), polyesters, urethane polymers, polyethers, silicone polymers, polyamides, fluorine polymers, ethylene-vinyl acetate polymers, epoxy resins, vinyl chloride polymers, cyanoacrylate polymers, cellulose polymers (nitrocellulose polymers, etc.), phenolic resins, polyimides, polyolefins, styrene polymers, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, polyvinyl butyral, polybenzimidazole, melamine resins, urea resins, resorcinol polymers, etc. These polymers may be used individually or in combination of two or more. From the viewpoint of adhesion and cost, acrylic polymers and rubber polymers are preferred, and acrylic polymers are more preferred. The term "base polymer" refers to the main component of the polymer contained in the adhesive. The above polymer is preferably a rubbery polymer that exhibits rubber elasticity in the temperature range around room temperature. Furthermore, in this specification, "main component" refers to a component present in an amount exceeding 50% by weight, unless otherwise specified.

As the above-mentioned acrylic polymer, for example, a polymer of a monomer raw material containing alkyl (meth)acrylate as the main monomer and a secondary monomer copolymerizable with the main monomer is preferred. Here, the main monomer refers to the component that accounts for more than 50% by weight of the monomer composition in the above-mentioned monomer raw material. The content of the main monomer is preferably 60 to 100 parts by weight, and more preferably 70 to 99.5 parts by weight, based on 100 parts by weight of the total amount of monomer in the monomer raw material.

As the alkyl (meth)acrylate, for example, a compound represented by the following formula (1) can be suitably used.
CH ₂ =C(R ¹ )COOR ² (1)
Here, ^R1 in formula (1) above is a hydrogen atom or a methyl group. ^R2 is a branched or linear alkyl group having 1 to 20 carbon atoms (hereinafter, this range of carbon atoms may be expressed as "C1-20"). ^R2 is preferably a branched or linear C1-14 alkyl group, more preferably a branched or linear C6-14 alkyl group, and even more preferably a branched or linear C8-12 alkyl group.

Specific examples of the alkyl (meth)acrylates mentioned above include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate. Examples include alkyl (meth)acrylates, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. These alkyl (meth)acrylates can be used individually or in combination of two or more. Among these, 2-ethylhexyl acrylate (2EHA) and lauryl (meth)acrylate (LA, LMA) are particularly preferred.

In one embodiment, an alkyl (meth)acrylate in which ^R2 is a branched or linear alkyl group having 8 or more carbon atoms is used. By using such a monomer as the main monomer, an adhesive sheet can be obtained that has a desirable elastic modulus before and after curing and is particularly excellent in fixing and peeling properties for electronic components. Examples of alkyl (meth)acrylates in which ^R2 is a branched or linear alkyl group having 8 or more carbon atoms include 2EHA, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, and dodecyl (meth)acrylate. The content ratio of constituent units derived from alkyl (meth)acrylate in which ^R2 is a branched or linear alkyl group having 8 or more carbon atoms is preferably 60 to 100 parts by weight, and more preferably 70 to 95 parts by weight, per 100 parts by weight of the base polymer.

The secondary monomers copolymerizable with the main monomer, alkyl (meth)acrylate, can be useful for introducing crosslinking sites into acrylic polymers or for enhancing the cohesive strength of acrylic polymers. Furthermore, it is preferable to use monomers as secondary monomers that have a functional group (functional group a) that can react with the functional group (functional group b) of the carbon-carbon double bond-containing monomer described later. As secondary monomers, for example, the following functional group-containing monomer components can be used individually or in combination of two or more.
Carboxylate group-containing monomers: for example, ethylenically unsaturated monocarboxylic acids such as acrylic acid (AA), methacrylic acid (MAA), and crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and citraconic acid, and their anhydrides (maleic anhydride, itaconic anhydride, etc.);
Hydroxyl group-containing monomers: for example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether;
Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate;
Epoxy group-containing monomers: e.g., glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether;
Cyano group-containing monomers: e.g., acrylonitrile, methacrylonitrile;
Keto group-containing monomers: for example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetate, vinyl acetate;
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine;
Alkoxysilyl group-containing monomers: for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane;
Isocyanate group-containing monomers: (meth)acryloyl isocyanate, 2-(meth)acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate.
Furthermore, it is preferable not to use amide group-containing monomers that can produce polymers with high affinity for metals, from the viewpoint of maintaining release properties.

In one embodiment, a hydroxyl group-containing monomer is preferably used as the sub-monomer, and 2-hydroxyethyl (meth)acrylate may be more preferably used. Using this monomer, an adhesive sheet can be obtained that has a desirable elastic modulus before and after curing, and exhibits particularly excellent fixing and release properties for electronic components.

The content ratio of the constituent units derived from the above-mentioned sub-monomers is preferably 0.1 to 40 parts by weight, and more preferably 1 to 30 parts by weight, per 100 parts by weight of the base polymer. Within this range, an adhesive layer with high cohesive strength and excellent tackiness can be formed.

Furthermore, when using a base polymer having a carbon-carbon double bond, as described later, it is preferable to use a sub-monomer having a functional group (functional group a) that can react with the functional group (functional group b) of compound B having a carbon-carbon double bond, as described later. In this case, the type of sub-monomer is determined by the type of compound B. As sub-monomers having functional group a, for example, carboxyl group-containing monomers, epoxy group-containing monomers, hydroxyl group-containing monomers, and isocyanate group-containing monomers are preferred, with hydroxyl group-containing monomers being particularly preferred. By using a hydroxyl group-containing monomer as the sub-monomer, the acrylic polymer has hydroxyl groups. In contrast, by using an isocyanate group-containing monomer as compound B having a carbon-carbon double bond, the hydroxyl groups of the acrylic polymer react with the isocyanate groups of the compound, and a carbon-carbon double bond derived from compound B is introduced into the acrylic polymer.

Furthermore, other copolymerization components besides the aforementioned sub-monomers can be used for purposes such as increasing the cohesive strength of the acrylic polymer. Examples of such copolymer components include vinyl ester monomers such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyltoluene; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl di(meth)acrylate, and isobornyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as aryl (meth)acrylate (e.g., phenyl (meth)acrylate), aryloxyalkyl (meth)acrylate (e.g., phenoxyethyl (meth)acrylate), and arylalkyl (meth)acrylate (e.g., benzyl (meth)acrylate); olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy group-containing monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; and the like. Other copolymerization components besides these secondary monomers can be used individually or in combination of two or more. The amount of such other copolymerization components is, for example, 2 to 20 parts by weight per 100 parts by weight of the total amount of monomer in the monomer raw material.

Furthermore, polyfunctional monomers can be used as copolymerizable components for purposes such as crosslinking acrylic polymers. As the polyfunctional monomer, one or more of the following can be used: hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, etc. The amount of the polyfunctional monomer is, for example, 30 parts by weight or less per 100 parts by weight of the total amount of monomer in the monomer raw material.

The above-mentioned acrylic polymer can be obtained by any suitable polymerization method. Examples include solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.

Preferably, a carbon-carbon double bond is introduced into the base polymer (preferably an acrylic polymer). By using a base polymer having a carbon-carbon double bond, an adhesive layer that hardens with active energy rays (typically ultraviolet light) can be formed. In addition to the above method, in this invention, it is also possible to form a curable adhesive layer using an adhesive containing a polymerizable monomer or oligomer and an acrylic polymer. However, from the viewpoint of obtaining an adhesive sheet with excellent peelability, it is preferable to form the curable adhesive layer using a base polymer having a carbon-carbon double bond.

Any suitable method can be used to produce a base polymer having a carbon-carbon double bond. For example, one method involves reacting a polymer A having functional group a with compound B having a functional group (functional group b) that can react with functional group a, and a carbon-carbon double bond. In this case, it is preferable to carry out the reaction in a way that prevents the disappearance of the carbon-carbon double bond; for example, condensation reactions and addition reactions can be employed. As polymer A, for example, as described above, a polymer obtained by copolymerizing an alkyl (meth)acrylate as the main monomer with a sub-monomer having functional group a can be used.

Examples of combinations between functional group a and functional group b include combinations of carboxyl group and epoxy group, combinations of carboxyl group and aziridyl group, and combinations of hydroxyl group and isocyanate group. Among these, the combination of hydroxyl group and isocyanate group is preferred from the viewpoint of reaction traceability. From the viewpoint of polymer design, a combination in which the acrylic polymer has a hydroxyl group and the compound has an isocyanate group is particularly preferred.

Examples of compounds having the carbon-carbon double bond and functional group b include isocyanate group-containing monomers (isocyanate group-containing compounds). Among these, 2-(meth)acryloyloxyethyl isocyanate is more preferred.

The amount of isocyanate group-containing monomer blended is preferably 1 to 40 parts by weight, more preferably 5 to 30 parts by weight, and even more preferably 8 to 15 parts by weight, per 100 parts by weight of the polymer before the introduction of the carbon-carbon double bond (i.e., polymer A).

Alternatively, a carbon-carbon double bond may be introduced while retaining the hydroxyl groups present in polymer A. This allows for increased crosslinking when the adhesive layer is heated. In this case, the molar ratio (a/b) of the hydroxyl group (functional group a) to the isocyanate group (functional group b) should be greater than 1, and preferably 1.1 or higher.

The weight-average molecular weight Mw of the above base polymer (preferably an acrylic polymer) is preferably 10 × ^10⁴ to 500 × ^10⁴ , more preferably 20 × ^10⁴ to 200 × ^10⁴ , and even more preferably 30 × ^10⁴ to 100 × ^10⁴ . Within this range, an adhesive layer with minimal residue and excellent adhesion can be formed. In this specification, Mw refers to the value obtained by GPC on a standard polystyrene basis.

Preferably, the adhesive contains a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, amine-based crosslinking agents, and the like. These crosslinking agents can be used individually or in combination of two or more.

The content ratio of the above-mentioned crosslinking agent is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 8 parts by weight, per 100 parts by weight of the base polymer of the adhesive. Within this range, an adhesive layer with appropriately adjusted nanoindenter modulus can be formed.

In one embodiment, an isocyanate-based crosslinking agent is preferably used. Isocyanate-based crosslinking agents are preferred because they can react with a variety of functional groups. Specific examples of the above-mentioned isocyanate-based crosslinking agents include: lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; isocyanate adducts such as trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), and isocyanurate derivative of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"); and the like. Preferably, a crosslinking agent having three or more isocyanate groups is used.

The above-mentioned isocyanate-based crosslinking agent is preferably added in such a way that the number of functional groups of the isocyanate-based crosslinking agent is 10 mol% to 50 mol%, and more preferably 20 mol% to 40 mol%, relative to the number of functional groups in the base polymer that can react with the isocyanate-based crosslinking agent. Adding it in such amounts allows for the formation of an adhesive layer with appropriately adjusted nanoindenter modulus.

The above adhesive may further contain any suitable additives as needed. Examples of such additives include photopolymerization initiators, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers), pigments, dyes, fillers, antioxidants, conductive materials, UV absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and solvents.

C. Substrate The substrate may be composed of any suitable resin. Examples of such resins include polyethylene resins, polypropylene resins, polybutene resins, polymethylpentene resins and other polyolefin resins, polyurethane resins, polyester resins, polyimide resins, polyetherketone resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, silicone resins, cellulose resins, ionomer resins, and the like.

In one embodiment, a substrate made of a polyester resin is used as the substrate. A substrate made of a polyester resin preferably has rigidity, and using such a substrate can prevent misalignment when fixing electronic components.

The thickness of the above-mentioned substrate is preferably 2 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 10 μm to 200 μm.

In one embodiment, a substrate with a thickness of 30 μm to 200 μm (preferably a substrate made of polyester resin) is used. Using a substrate of this thickness prevents misalignment when fixing electronic components.

D. Another adhesive layer The other adhesive layer may be composed of any suitable adhesive. The adhesive may be a curing type adhesive or a pressure-sensitive type adhesive. The other adhesive layer may include, for example, acrylic adhesives, rubber adhesives, silicone adhesives, etc.

The thickness of the aforementioned adhesive layer is, for example, 1 μm to 100 μm.

E. Method for Manufacturing Adhesive Sheets The above-mentioned adhesive sheet can be manufactured by any suitable method. The adhesive sheet can be obtained, for example, by coating the above-mentioned adhesive onto a substrate. Various coating methods can be employed, such as bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, and screen printing. Alternatively, a method in which an adhesive layer is formed on a release liner and then bonded to the substrate may be employed.

F. How to use adhesive sheets (processing method for electronic components)
The adhesive sheet of the present invention can be used in the processing of any suitable electronic component to transfer the electronic component between members. For example, in one embodiment, a method for processing an electronic component using the adhesive sheet is provided, which includes (a) a step a in which the electronic component placed on a first member is transferred onto the adhesive layer of the adhesive sheet (the adhesive sheet receives the electronic component), and (b) a step b in which the electronic component is picked up by a second member and peeled off the electronic component from the adhesive sheet (the electronic component is transferred from the adhesive sheet). Any suitable processing steps may be performed before step a, between step a and step b, and after step b.

In one embodiment, multiple electronic components are arranged on the first member. In one embodiment, in step a, all electronic components arranged on the first member are transferred onto the adhesive sheet. In another embodiment, a portion of the electronic components arranged on the first member are selectively transferred onto the adhesive sheet.

In one embodiment, step b includes step b-1 of bringing the second member into contact with the electronic component on the adhesive layer, step b-2 of irradiating the adhesive sheet (substantially the adhesive layer) with active energy rays, and step b-3 of picking up the electronic component with the second member and peeling it off the adhesive sheet.

In one embodiment, the above-mentioned electronic component may be an LED. In one embodiment, a mini-LED or micro-LED may be used as the LED. A mini-LED is, for example, an LED chip with a side length of 100 μm or more, and has a structure in which a growth support substrate such as a sapphire substrate is adjacent to a light-emitting (epitaxial) layer mainly composed of gallium nitride. In this specification, even if the side length is 100 μm or less, an LED chip having a growth support substrate such as a sapphire substrate is defined as a mini-LED. The side length of a mini-LED chip is, for example, 50 μm to 500 μm, and the thickness is, for example, 30 μm to 200 μm. A micro-LED is, for example, an LED chip with a side length of 100 μm or less, and has a structure in which the light-emitting (epitaxial) layer mainly composed of gallium nitride is separated from the growth support substrate such as a sapphire substrate, and consists only of the light-emitting (epitaxial) layer. In this specification, LED chips that do not have a growth support substrate such as a sapphire substrate, even if one side is 100 μm or more, are defined as micro-LEDs. The side length of a micro-LED chip is, for example, 5 μm to 200 μm, and the thickness is, for example, 3 μm to 30 μm.

In one embodiment, the electronic component is an LED (preferably a micro-LED), and the first member is a sapphire substrate. In this embodiment, in step a, UV laser light is irradiated onto the sapphire substrate on which the LEDs are arranged to transfer the LEDs to the adhesive sheet. Here, the LEDs are detached from the sapphire substrate by chemically decomposing the interface between the sapphire substrate and the LEDs through UV laser irradiation. Specifically, gallium nitride present near the interface between the sapphire substrate and the LEDs is decomposed into liquid metallic gallium and gaseous nitrogen by UV laser irradiation, and the LEDs are separated from the sapphire substrate. In one embodiment, all LEDs arranged on the sapphire substrate are transferred onto the adhesive sheet. In another embodiment, a portion of the LEDs arranged on the sapphire substrate are selectively transferred onto the adhesive sheet.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The test and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" are based on weight.

(1) Nanoindenter Elastic Modulus Using a nanoindenter (Hystron Inc., product name "Triboindenter TI-950"), the elastic modulus of the adhesive layer surface was measured under normal conditions and after irradiation with 460 mJ/ ^cm² ultraviolet light, using a single indentation method at a predetermined temperature (25°C) with measurement conditions of indentation speed of approximately 500 nm/sec, withdrawal speed of approximately 500 nm/sec, and indentation depth of approximately 3000 nm.

(2) Storage modulus of adhesive layer in normal state A dynamic viscoelasticity measuring device (TA Instruments Co., Ltd., product name "ARES-G2") was used to measure the storage modulus G' and loss factor tanδ at a measurement frequency of 1 Hz, strain of 0.05%, and 25°C. Specifically, an adhesive sheet without a substrate and with a thickness of 50 μm was prepared using the adhesive in normal state obtained in the examples and comparative examples. This adhesive sheet was laminated to a thickness of 1.0 mm or more, punched out to a size of φ8 mm using a jig, and set on the probe of the ARES-G2. Measurements were taken from -50°C to 200°C at a heating rate of 5°C/min. From the obtained data, the value of the storage modulus G' at 25°C was extracted.

(3) Tensile modulus of the adhesive layer after irradiation with 460 mJ/ ^cm² ultraviolet light A dynamic viscoelasticity measuring device (TA Instrument Co., Ltd., product name "RSA-3") was used to measure the tensile modulus E' at a measurement frequency of 1 Hz, strain of 0.05%, and 25°C. Specifically, an adhesive sheet without a substrate and with a thickness of 50 μm was prepared using the adhesives obtained in the examples and comparative examples, and this adhesive sheet was laminated to a thickness of 200 μm or more. With release liners attached to both sides of the sample, the adhesive layer was irradiated once from each side with 460 mJ/ ^cm² ultraviolet light, and the release liners were removed to obtain a sample with a width of 10 mm. The distance between the chucks was set to 20 mm, and measurements were taken at a heating rate of 5°C/min. from 0°C to 200°C. From the obtained data, the value of the tensile modulus E' at 25°C was extracted.

(4) Probe Tack The entire surface of the adhesive sheet (20 mm wide x 50 mm long) opposite the adhesive layer on the evaluation surface was attached to a glass slide (Matsunami Glass Industry Co., Ltd., 26 mm x 76 mm) using a 2 kg hand roller via double-sided adhesive tape (Nitto Denko Corporation, product name "No. 5600"). Next, the probe tack value of the exposed adhesive layer surface, and the probe tack value after irradiating the exposed adhesive layer surface with 460 mJ/ ^cm² of ultraviolet light, were measured using a probe tack measuring instrument (RHESCA, product name "TACKINESS Model TAC-II") with a 5 mmφ SUS probe terminal, under the following conditions: probe descent speed (Immorsion speed): 120 mm/min, test speed (test speed): 600 mm/min, adhesion load (Preload): 20 gf, and adhesion holding time (press time): 1 second. Measurements were performed with N=5, and the average of these measured values was taken as the probe tack value. Furthermore, for the adhesive sheets of Examples 17 to 22, the adhesive surface opposite to the adhesive layer on the evaluation surface was attached to the above-mentioned slide glass using a 2 kg hand roller, and the probe tack value was measured under the same conditions as above.

(5) Adhesion Strength The adhesive layer of the adhesive sheet was attached to SUS304BA, and the adhesion strength of the adhesive sheet to SUS304BA was measured according to the method conforming to JIS Z 0237:2000 (bonding conditions: 2 kg roller, one reciprocation, tensile speed: 300 mm/min, peel angle: 180°, measurement temperature: 23°C). In addition, the adhesive layer of the adhesive sheet was attached to polyethylene terephthalate film (Toray Industries, Ltd., product name "Lumirror S10", thickness: 25 μm), and the adhesion strength of the adhesive sheet to polyethylene terephthalate film was measured by peeling the adherend from the adhesive sheet according to the method conforming to JIS Z 0237:2000 (bonding conditions: 2 kg roller, one reciprocation, tensile speed: 300 mm/min, peel angle: 180°, measurement temperature: 23°C).
Furthermore, after attaching the adhesive to the substrate as described above, the adhesive strength was measured using the method described above after irradiating the adhesive layer with ultraviolet light at 460 mJ/ ^cm² .

(6) TMA Penetration Depth Using a thermomechanical analyzer (TA-instrument Co., Ltd., product name "TMA Q400"), a φ1.0 mm probe was used, and the penetration depth of the adhesive sheet was measured from the adhesive layer side in needle insertion mode under the following conditions: nitrogen gas flow rate: 50.0 ml/min, indentation load: 0.5 N, measurement ambient temperature: 40°C, and indentation loading time: 20 min. Measurements were performed with N=5, and the average value of N=3, excluding the maximum and minimum values from these measurements, was taken as the sample penetration depth.

(7) Chip embedding performance during bonding If the sinking depth of the adhesive sheet, as measured by thermomechanical analysis (TMA), is 3 μm or more and less than 27 μm, the embedding performance is excellent (○ in the table), and if it is 27 μm or more, the embedding performance is excessive (× in the table).

(8) Deformation of the substrate The deformation of the substrate was calculated by subtracting the thickness of the adhesive layer of the adhesive sheet from the depth of the adhesive sheet's sinking, which was measured by thermomechanical analysis (TMA). If the depth of the adhesive sheet's sinking was less than the thickness of the adhesive layer, it was assumed that there was no deformation of the substrate.

(9) Chip positional accuracy If the amount of deformation of the substrate calculated from the depth of sinking of the adhesive sheet measured by thermomechanical analysis (TMA) is less than 20 μm, the positional accuracy when receiving the chip is excellent (○ in the table), and if it is 20 μm or more, the positional accuracy when receiving the chip is insufficient (× in the table).

(10) Shear adhesive strength after irradiation with 460 mJ/ ^cm² ultraviolet light The adhesive sheets (size: 20 mm x 20 mm) obtained in the examples and comparative examples were fixed by attaching the side opposite to the adhesive layer to a predetermined base (for example, a 26 mm x 76 mm slide glass manufactured by Matsunami Glass Industry Co., Ltd.), and a 1 mm x 1 mm silicon chip was placed on the surface of the adhesive layer of the adhesive sheet. The silicon chip was then heat-pressed using a heat press machine at 40°C and 0.05 MPa for 1 minute to prepare an evaluation sample. For fixing the adhesive sheets without another adhesive layer to the base, double-sided adhesive tape (Nitto Denko Corporation, product name "No. 5600") was used. An evaluation sample was prepared by irradiating the adhesive layer of the adhesive sheet with the silicon chip with ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, integrated light intensity: 460 mJ/ ^cm² , irradiation energy: 70 W/ ^cm² , irradiation time: 6.6 seconds) using an ultraviolet irradiation device (manufactured by Nitto Seiki Co., Ltd., product name "UM-810") from a predetermined base side of the obtained evaluation sample.
For the evaluation sample, under an ambient temperature of 25°C, a Nordson Dage 4000 was used. The measurement terminal was set on the side of a 1 mm x 1 mm silicon chip at a height of 50 μm from the bonding surface, and an external force was applied horizontally to the chip at a shear rate of 500 μm/sec. The maximum breaking load was read from the resulting load-displacement curve and defined as the shear adhesive strength at an ambient temperature of 25°C. Measurements were performed with N=5, and the average value of N=3 (excluding the maximum and minimum values) was defined as the shear adhesive strength of the sample.

(11) Transferability When the shear adhesive strength after irradiation with 460 mJ/ ^cm² ultraviolet light is less than 2000 N/ ^cm² , the transferability when transferring chips is excellent (indicated by ○ in the table). When it is 2000 N/ ^cm² or more but less than 2400 N/ ^cm² , the transferability when transferring chips is good (indicated by △ in the table). When it is 2400 N/ ^cm² or more, the transferability when transferring chips is insufficient (indicated by × in the table).

[Production Example 1] Preparation of Acrylic Polymer A 88.8 parts by weight of 2-ethylhexyl acrylate (2-EHA), 11.2 parts by weight of hydroxyethyl acrylate (HEA), 0.2 parts by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BW"), and toluene were mixed. The resulting mixture was polymerized at 60°C under a nitrogen gas stream to obtain an acrylic copolymer with a weight-average molecular weight (Mw) of approximately 600,000.
To a toluene solution containing 100 parts by weight of an acrylic copolymer, 12 parts by weight of methacryloyloxyethyl isocyanate (MOI) and 0.06 parts by weight of butyltin dilaurate were added to induce an addition reaction of the MOI, thereby preparing an acrylic polymer A having a carbon-carbon double bond.

[Production Example 2] Preparation of Acrylic Polymer B 91 parts by weight of lauryl methacrylate (LMA), 9.3 parts by weight of 2-ethylhexyl methacrylate (2-HEMA), 0.2 parts by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BW"), and toluene were mixed. The resulting mixture was polymerized at 60°C under a nitrogen gas stream to obtain an acrylic copolymer.
To a toluene solution containing 100 parts by weight of an acrylic copolymer, 9.1 parts by weight of methacryloyloxyethyl isocyanate (MOI) and 0.04 parts by weight of butyltin dilaurate were added to induce an addition reaction of the MOI, thereby preparing acrylic polymer B having a carbon-carbon double bond.

[Production Example 3] Preparation of Acrylic Polymer C 100 parts by weight of 2-ethylhexyl acrylate (2-EHA), 25.5 parts by weight of acryloylmorpholine (ACMO), 18.5 parts by weight of hydroxyethyl acrylate (HEA), 0.2 parts by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BW"), and toluene were mixed. The resulting mixture was polymerized at 60°C under a nitrogen gas stream to obtain an acrylic copolymer with a weight-average molecular weight (Mw) of approximately 900,000.
To a toluene solution containing 100 parts by weight of an acrylic copolymer, 8.5 parts by weight of methacryloyloxyethyl isocyanate (MOI) and 0.04 parts by weight of butyltin dilaurate were added to induce an addition reaction of the MOI, thereby preparing an acrylic polymer C having a carbon-carbon double bond.

[Production Example 4] Preparation of Acrylic Polymer D 75 parts by weight of 2-ethylhexyl acrylate (2-EHA), 15 parts by weight of acryloylmorpholine (ACMO), 22 parts by weight of hydroxyethyl acrylate (HEA), 0.2 parts by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BW"), and toluene were mixed. The resulting mixture was polymerized at 60°C under a nitrogen gas stream to obtain an acrylic copolymer.
To a toluene solution containing 100 parts by weight of an acrylic copolymer, 17.7 parts by weight of methacryloyloxyethyl isocyanate (MOI) and 0.04 parts by weight of butyltin dilaurate were added to induce an addition reaction of MOI, thereby preparing an acrylic polymer D having a carbon-carbon double bond.

[Production Example 5] Preparation of Acrylic Polymer E 50 parts by weight of butyl acrylate (BA), 39 parts by weight of ethyl acrylate (EA), 20 parts by weight of hydroxyethyl acrylate (HEA), 0.3 parts by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BW"), and toluene were mixed. The resulting mixture was polymerized at 60°C under a nitrogen gas stream to obtain an acrylic copolymer.
To a toluene solution containing 100 parts by weight of an acrylic copolymer, 19.5 parts by weight of methacryloyloxyethyl isocyanate (MOI) and 0.06 parts by weight of butyltin dilaurate were added to induce an addition reaction of MOI, thereby preparing an acrylic polymer E having a carbon-carbon double bond.

[Production Example 6] Preparation of Acrylic Polymer F 30 parts by weight of 2-ethylhexyl acrylate (2-EHA), 70 parts by weight of methyl acrylate (MA), 10 parts by weight of acrylic acid (AA), 0.4 parts by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BW"), and toluene were mixed and heated at 70°C to prepare a toluene solution of acrylic copolymer (acrylic polymer F).

[Example 1]
To a toluene solution of the above-mentioned acrylic polymer A, 3 parts by weight of an isocyanate crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad" (Omnirad 127): 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one) were added per 100 parts by weight of the solids content of the acrylic polymer to prepare an adhesive. This adhesive was coated onto one side of a PET substrate (100 μm, manufactured by Toray Industries, Inc., "Lumirror S1N") to obtain an adhesive sheet A (adhesive layer/PET substrate) having an ultraviolet-curable adhesive layer (thickness: 2 μm).
The obtained adhesive sheet A was subjected to the above evaluation. The results are shown in Table 1.

[Examples 2-16, Example 23, Comparative Examples 1-3]
An adhesive sheet was obtained in the same manner as in Example 1, except that the acrylic polymer, crosslinking agent, tackifier, and photopolymerization initiator shown in Table 1 were used in the amounts shown in Tables 1 and 2, and the substrate shown in Table 1 was used. The obtained adhesive sheet was subjected to the above evaluation. The results are shown in Tables 1 and 2.
The compounds used in the examples and comparative examples are as follows:
- "YS Polystar S145": Terpene phenol-based tackifier, manufactured by Yasuhara Chemical Co., Ltd. - "UV-1700": Active energy ray-curable oligomer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "Shiko UV-1700B")
• "Omnirad 651": Manufactured by BASF, product name "Omnirad 651"
• "PET (Printed Product)": PET film manufactured by Daisan Paper Industry Co., Ltd. (Thickness: 50 μm, light red solid print)
- "PO": A substrate obtained by supplying a propylene-based thermoplastic elastomer (manufactured by Mitsubishi Chemical Corporation, trade name "Zelus") containing propylene and ethylene-propylene rubber components to a Braco T-die molding machine (set temperature: 230°C) and forming it into a film with a thickness of 80 μm.

[Example 17]
An adhesive sheet i (adhesive layer/PET substrate) was obtained in the same manner as in Example 1, except that the acrylic polymer, crosslinking agent, tackifier, and photopolymerization initiator shown in Table 1 were used in the amounts shown in Table 1.
A coating solution was prepared by adding 0.6 parts by weight of epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C") to a toluene solution containing 100 parts by weight of acrylic polymer G (a copolymer of 95 parts by weight of 2-ethylhexyl acrylate (2-EHA) and 5 parts by weight of acrylic acid (AA)). This coating solution was applied to the side of the PET substrate of the adhesive sheet i opposite to the adhesive layer to obtain adhesive sheet I (adhesive layer/PET substrate/another adhesive layer (thickness: 30 μm)). The obtained adhesive sheet was subjected to the above evaluation. The results are shown in Table 3.

[Examples 18-22]
An adhesive sheet was obtained in the same manner as in Example 17, except that a substrate with the thickness shown in Tables 3 and 4 was used. The obtained adhesive sheet was subjected to the above evaluation. The results are shown in Tables 3 and 4.

10 Base material 20 Adhesive layer 100, 200 Adhesive sheet

Claims (14)

An adhesive sheet for transferring electronic components, comprising a base material and an adhesive layer disposed on at least one side of the base material,
The adhesive layer exhibits a nanoindenter modulus of 100 MPa to 500 MPa at 25°C after irradiation with 460 mJ/ ^cm² of ultraviolet light.
The amount of sinking of the TMA adhesive sheet for transferring electronic components in a 40°C environment is 3 μm to 27 μm.
Adhesive sheet for transferring electronic components. The adhesive sheet for transferring electronic components according to claim 1, wherein the thickness of the adhesive layer is 2.1 μm to 35 μm. The adhesive sheet for transferring electronic components according to claim 1 or 2, wherein the normal state nanoindenter elastic modulus of the adhesive layer before irradiation with active energy rays at 25°C is 0.4 MPa or higher. The adhesive sheet for transferring electronic components according to any one of claims 1 to 3, wherein the normal probe tack value of the adhesive layer before irradiation with active energy rays is 8 N/ ^cm² or more. The adhesive sheet for transferring electronic components according to any one of claims 1 to 4, wherein the substrate is made of a polyester resin. The adhesive sheet for transferring electronic components according to any one of claims 1 to 5, wherein the thickness of the substrate is 30 μm to 200 μm. The adhesive sheet for transferring electronic components according to any one of claims 1 to 6, wherein the electronic component is a mini-LED or a micro-LED. An adhesive sheet for transferring electronic components according to any one of claims 1 to 7, comprising the adhesive layer, the substrate, and another adhesive layer in this order. A method for processing electronic components using an adhesive sheet for transferring electronic components as described in any one of claims 1 to 8,
Step a of transferring the electronic components placed on the first member onto the adhesive layer of the adhesive sheet,
The process includes step b, which involves picking up the electronic component with a second member and peeling the electronic component off the adhesive sheet.
Methods for processing electronic components. The method for processing an electronic component according to claim 9, wherein the electronic component is a mini-LED or a micro-LED. The aforementioned step b is
Step b-1 involves bringing the second member into contact with the electronic component on the adhesive layer,
Step b-2 involves irradiating the adhesive sheet with active energy rays,
The process includes step b-3, in which the electronic component is picked up by the second member and the electronic component is peeled off the adhesive sheet.
A method for processing an electronic component according to claim 9 or 10. The method for processing an electronic component according to claim 10 or 11, wherein the first component is a sapphire substrate. The aforementioned electronic component is a microLED,
The method for processing an electronic component according to claim 12, further comprising, in step a, irradiating the sapphire substrate on which a plurality of micro-LEDs are arranged with UV laser light to transfer the micro-LEDs to the adhesive sheet. The method for processing an electronic component according to claim 13, wherein a portion of the micro-LEDs arranged on the sapphire substrate are selectively transferred to the adhesive sheet.