Adhesive sheet and method for processing object

Abstract

The present invention is capable of picking up an object held on an adhesive sheet having an adhesive layer having recesses and projections on the surface thereof by a milder operation. An adhesive sheet is provided with an adhesive layer having recesses and projections on the surface thereof. The adhesive layer has a tensile fracture stress at 23 DEG C of 20 MPa or more.

Description

Technical Field

[0001] This invention relates to a method for processing adhesive sheets and objects. Background Technology

[0002] Adhesive sheets can be used to temporarily hold objects. For example, such adhesive sheets can be used to transfer an object to a desired location.

[0003] Adhesive sheets come in various shapes depending on their application. For example, Patent Document 1 describes providing grooves on the surface of the adhesive layer to remove air bubbles after bonding.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-147418 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The inventors of this application have studied the creation of irregularities on the surface of the adhesive layer of an adhesive sheet. This configuration reduces the holding force of the sheet on the object, making it easier to pick up the object from the sheet for transfer printing. On the other hand, to reduce damage to the object during pickup, a gentler handling method is required.

[0009] The object of the present invention is to enable the picking up of objects held in an adhesive sheet having an adhesive layer having an uneven surface with gentler operation.

[0010] Solution for solving the problem

[0011] Through repeated and in-depth research, the inventors discovered that by appropriately adjusting the tensile fracture stress of the adhesive layer in the adhesive sheet, the picking up of objects becomes easier, thereby solving the aforementioned problem. Further repeated research led to the completion of this invention.

[0012] That is, the present invention relates to the following [1] to

[14] .

[0013] [1] An adhesive sheet having an adhesive layer having an uneven surface, wherein the tensile breaking stress of the adhesive layer at 23°C is 20 MPa or more.

[0014] [2] According to the adhesive sheet described in [1], wherein the tensile breaking stress is less than 100 MPa.

[0015] [3] The adhesive sheet according to any one of [1] to [2], wherein the adhesive sheet further comprises a release layer having a surface with a surface that is complementary to the surface of the adhesive layer.

[0016] [4] The adhesive sheet according to any one of [1] to [3], wherein the adhesive sheet can be extended by more than 1% in the surface direction.

[0017] [5] An adhesive sheet according to any one of [1] to [4], wherein the adhesive layer has a plurality of protrusions that are defined by recesses and are separated from each other, the spacing between the plurality of protrusions being more than 1 μm and less than 100 μm.

[0018] [6] The adhesive sheet according to any one of [1] to [5], wherein the adhesive layer has a plurality of protrusions and the plurality of protrusions are of uniform height.

[0019] [7] The adhesive sheet according to any one of [1] to [6], wherein the adhesive layer comprises an acrylic resin and an energy-curable resin.

[0020] [8] According to the adhesive sheet of [7], wherein the energy-curable resin comprises poly(meth)acrylate as a structural unit.

[0021] [9] The adhesive sheet according to any one of [7] to [8], wherein the energy-curable resin is 8 parts by mass or more relative to 100 parts by mass of the acrylic resin.

[0022]

[10] The adhesive sheet according to any one of [7] to [9], wherein the adhesive layer further comprises a crosslinking agent of the acrylic resin, the crosslinking agent being at least 0.05 parts by mass relative to 100 parts by mass of the acrylic resin.

[0023]

[11] A method for processing an object, the method comprising: a holding step of holding the object on an adhesive layer of an adhesive sheet according to any one of [1] to

[10] ; and a peeling step of peeling the object off the adhesive layer of the adhesive sheet.

[0024]

[12] According to the object processing method described in

[11] , the object processing method further includes: an extension step, in which the adhesive sheet holding the object is extended along the surface direction, and in the peeling step, the object is peeled off from the adhesive layer of the adhesive sheet after it has been extended along the surface direction.

[0025]

[13] A method for processing an object according to any one of

[11] to

[12] , wherein, in the peeling step, an adsorption member is used to peel the object from the adhesive layer of the adhesive sheet.

[0026]

[14] A method for processing an object according to any one of

[11] to

[13] , wherein, in the peeling step, the object is peeled from the adhesive layer of the adhesive sheet without applying physical stimulation to the opposite side of the adhesive layer of the adhesive sheet.

[0027] Invention Effects

[0028] This invention enables the picking up of objects held in an adhesive sheet having an adhesive layer with an uneven surface through gentler operation.

[0029] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. It should be noted that, in the drawings, the same or identical components are labeled with the same reference numerals. Attached Figure Description

[0030] The accompanying drawings, which are included in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0031] Figure 1 This is a cross-sectional view of a sheet material according to one embodiment.

[0032] Figure 2A This is a cross-sectional view showing an example of the unevenness or roughness of a sheet material.

[0033] Figure 2B This is a cross-sectional view showing an example of the unevenness or roughness of a sheet material.

[0034] Figure 3A This is a top view showing an example of the unevenness or texture of a sheet material.

[0035] Figure 3B This is a top view showing an example of the unevenness or texture of a sheet material.

[0036] Figure 3C This is a top view showing an example of the unevenness or texture of a sheet material.

[0037] Figure 4A This is a cross-sectional view showing an example of the unevenness or roughness of a sheet material.

[0038] Figure 4B This is a cross-sectional view showing an example of the unevenness or roughness of a sheet material.

[0039] Figure 4C This is a cross-sectional view showing an example of the unevenness or roughness of a sheet material.

[0040] Figure 5A This diagram illustrates the method of expanding sheet material.

[0041] Figure 5BThis diagram illustrates the method of expanding sheet material.

[0042] Figure 6 This is a flowchart of an object transfer method. Detailed Implementation

[0043] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention as defined in the claims, and that not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more features from the plurality of features described in the embodiments can be combined arbitrarily. Furthermore, identical or identical components are labeled with the same reference numerals, and repeated descriptions are omitted.

[0044] (definition)

[0045] In this specification, the mass-average molecular weight (Mw) and number-average molecular weight (Mn) are values ​​converted from standard polystyrene determined by size exclusion chromatography, specifically based on JIS K7252-1:2016. Furthermore, in this specification, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," as do other similar terms.

[0046] In this specification, when a lower limit value (e.g., a range of content, etc.) of 1 or more is described, and an upper limit value of 1 or more is also described, it can be understood that any combination of the lower limit value and the upper limit value is described. For example, the description that it is preferred to be 1 or more, more preferably 2 or more, further preferably 3 or more and preferably 9 or less, more preferably 8 or less, and further preferably 7 or less clearly indicates that the numerical range can be any one of 1 or more and 9 or less, 1 or more and 8 or less, 1 or more and 7 or less, 2 or more and 9 or less, 2 or more and 8 or less, 2 or more and 7 or less, 3 or more and 9 or less, 3 or more and 8 or less, and 3 or more and 7 or less.

[0047] (The composition of the sheet)

[0048] An adhesive sheet according to one embodiment of the present invention includes a substrate 120 and an adhesive layer 110 having an uneven surface. The adhesive sheet can be used as a transfer sheet for temporarily holding an object and transferring it to a transfer destination. For example, the adhesive sheet can be used to receive an object held on another holding substrate, temporarily hold the object, and transfer the object to a desired position at the transfer destination. The substrate 120 can support the adhesive layer 110. Hereinafter, a schematic diagram of an adhesive sheet as one embodiment will be used. Figure 1 The composition of such adhesive sheets will be explained.

[0049] (Substrate)

[0050] The substrate 120 functions as a support for the adhesive layer 110. The substrate 120 is located on the side of the adhesive layer 110 opposite to the side with the uneven surface.

[0051] As described below, the adhesive sheet of this embodiment can be extended. From this viewpoint, a flexible substrate can be used as the substrate 120. Furthermore, by using a flexible substrate as the substrate 120, the cushioning when holding an object can be improved, the lamination of the adhesive sheet can be made easier, or the adhesive sheet can be rolled into a roll. As the substrate 120, a resin film can be used, for example. A resin film is a film using a resin-based material as the main material, and can be formed from a resin material, and may also contain additives in addition to the resin material. The resin film may have laser transmittance.

[0052] Specific examples of resin membranes include: polyethylene membranes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE); polypropylene membranes, polybutene membranes, polybutadiene membranes, poly(4-methyl-1-pentene) membranes, ethylene-norbornene copolymer membranes, and norbornene resin membranes; ethylene copolymer membranes such as ethylene-vinyl acetate copolymer membranes, ethylene-(meth)acrylate copolymer membranes, and ethylene-(meth)acrylate copolymer membranes; polyvinyl chloride membranes and vinyl chloride copolymer membranes; polyester membranes such as polyethylene terephthalate membranes and polybutylene terephthalate membranes; polyurethane membranes; polyimide membranes; polystyrene membranes; polycarbonate membranes; and fluoropolymer membranes. Furthermore, membranes containing mixtures of two or more materials, cross-linked membranes formed by cross-linking the resins that form these membranes, and modified membranes such as ionomer membranes can also be used. In addition, the substrate 120 can also be a laminated film made of two or more resin films.

[0053] From the viewpoint of facilitating the expansion of the adhesive sheet, the substrate 120 is preferably a polyolefin-based film or a vinyl chloride copolymer film. Examples of polyolefin-based films include polyethylene films, polypropylene films, and copolymers containing ethylene-methacrylic acid copolymer (EMAA), or copolymers containing unsubstituted olefins such as ethylene or propylene as structural units. Examples of vinyl chloride copolymer films include vinyl chloride-polyvinylidene chloride copolymer films, vinyl chloride-vinyl acetate copolymer films, and vinyl chloride-ethylene copolymer films. The form of such copolymers is not particularly limited and can be any of block copolymers, random copolymers, alternating copolymers, and graft copolymers. It should be noted that these films may also contain other resin components or additives.

[0054] The thickness of the substrate 120 is not particularly limited. From the viewpoint of balancing support and winding properties, it is preferably 10 μm or more, more preferably 25 μm or more, and even more preferably 40 μm or more. On the other hand, it is preferably 500 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, even more preferably 150 μm or less, even more preferably 120 μm or less, and particularly preferably 90 μm or less.

[0055] To facilitate the uniform expansion of the adhesive sheet, the tensile modulus of the substrate 120 is preferably 50 MPa or more, more preferably 80 MPa or more, even more preferably 120 MPa or more, preferably 2500 MPa or less, more preferably 1000 MPa or less, and even more preferably 500 MPa or less. In this specification, the tensile modulus is measured according to JIS K7161-1:2014.

[0056] Similarly, in order to facilitate the expansion of the adhesive sheet, the elongation at break of the substrate 120 is preferably 105% or more, more preferably 110% or more, and even more preferably 115% or more. In this specification, the elongation at break is measured in accordance with JIS K 7127:1999.

[0057] (Adhesive layer)

[0058] The adhesive layer 110 is an adhesive layer and may contain resin. As described above, the adhesive layer 110 has an uneven surface. It should be noted that the adhesive sheet may have two or more adhesive layers 110. For example, the adhesive sheet may be a laminate of one or more adhesive layers 110.

[0059] (Composition of the adhesive layer)

[0060] Examples of resins included in the adhesive layer 110 include rubber-based resins such as polyisobutylene resins, polybutadiene resins, and styrene-butadiene resins, acrylic resins, urethane resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. The adhesive layer may be heat-resistant; examples of materials for the adhesive layer 110 with such heat resistance include polyimide resins and silicone resins. The adhesive layer 110 may contain copolymers having two or more structural units. The form of such copolymers is not particularly limited and can be any of block copolymers, random copolymers, alternating copolymers, and graft copolymers.

[0061] The resin included in the adhesive layer 110 is preferably an adhesive resin that has adhesive properties on its own. Furthermore, the resin is preferably a polymer with a mass-average molecular weight (Mw) of 10,000 or more. From the viewpoint of improving retention, the mass-average molecular weight (Mw) of the resin is preferably 10,000 or more, more preferably 70,000 or more, and even more preferably 140,000 or more. Furthermore, from the viewpoint of suppressing the storage modulus to a predetermined value or less, it is preferably 2 million or less, more preferably 1.2 million or less. Furthermore, from the viewpoint of improving retention, the number-average molecular weight (Mn) of the resin is preferably 10,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more. Furthermore, from the viewpoint of suppressing the storage modulus to a predetermined value or less, it is preferably 2 million or less, more preferably 1.5 million or less, and even more preferably 1.2 million or less. It should be noted that, as described later, when the adhesive layer 110 includes a resin derived from an energy-reactive resin, its mass-average molecular weight (Mw) and number-average molecular weight (Mn) refer to the mass-average molecular weight (Mw) and number-average molecular weight (Mn) before the energy-given crosslinking reaction. Furthermore, the glass transition temperature (Tg) of the resin is preferably -75°C or higher, more preferably -70°C or higher, preferably 5°C or lower, and more preferably -20°C or lower. By keeping the Tg within this range, it is easy to maintain the retention of the adhesive layer 110 and the storage modulus within the range described later.

[0062] The amount of resin contained in the adhesive layer 110 can be appropriately set according to the required retention and storage modulus of the adhesive layer 110, relative to the total amount of the components constituting the adhesive layer 110. It is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, preferably 99.99% by mass or less, more preferably 99.95% by mass or less, further preferably 99.90% by mass or less, further preferably 99.80% by mass or less, and further preferably 99.50% by mass or less.

[0063] From the viewpoint of morphological stability of the unevenness of the adhesive layer surface, the storage modulus of the adhesive layer 110 is preferably 0.001 MPa or more, more preferably 0.01 MPa or more, further preferably 0.03 MPa or more, and even more preferably 0.07 MPa or more. On the other hand, in terms of suppressing positional displacement when holding an object, a low storage modulus of the adhesive layer 110 is preferable. From this viewpoint, the storage modulus of the adhesive layer 110 is preferably 100 MPa or less, more preferably 50 MPa or less, further preferably 20 MPa or less, and particularly preferably 5 MPa or less. In this specification, the storage modulus is measured according to JIS K 7244-1:1998. Specifically, a cylindrical sample with a thickness of 3 mm and a diameter of 8 mm is prepared, and the storage modulus of the sample is measured using a viscoelastic measuring device by torsional shear method at 1 Hz and 23 °C, thereby determining the storage modulus of the adhesive layer 110.

[0064] In one embodiment, the resin contained in the adhesive composition forming the adhesive layer 110 may include a thermoplastic resin. That is, the adhesive layer 110 may be formed of a thermoplastic resin. When using a thermoplastic resin, the resin is softened by heating, making it easy to form unevenness in the adhesive layer 110, and furthermore, it is easy to maintain the unevenness formed by cooling. Examples of thermoplastic resins include rubber-based resins, acrylic resins, urethane resins, and olefin-based resins. Examples include polybutadiene-based thermoplastic elastomers using butadiene as a monomer, styrene-based thermoplastic elastomers using styrene as a monomer, and acrylic thermoplastic elastomers using (meth)acrylic acid or (meth)acrylate as monomers.

[0065] The composition of adhesive layer 110 will be described below. However, the composition of adhesive layer 110 is not limited to the composition shown below.

[0066] (Acrylic resin (A))

[0067] In one embodiment, the adhesive composition forming the adhesive layer 110 comprises an acrylic resin. The acrylic resin is a resin containing (meth)acrylic acid or (meth)acrylate as a monomer. From the viewpoint of improving adhesion, the weight-average molecular weight (Mw) of the acrylic resin is preferably 10,000 or more, more preferably 100,000 or more, and even more preferably 500,000 or more. Furthermore, from the viewpoint of suppressing the storage modulus to a predetermined value or less, it is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,200,000 or less.

[0068] The glass transition temperature (Tg) of the acrylic resin is preferably -75°C or higher, more preferably -70°C or higher, preferably 5°C or lower, and more preferably -20°C or lower. By keeping the Tg within this range, it is easy to obtain an adhesive layer 110 having the above-mentioned energy storage modulus.

[0069] When an acrylic resin has two or more structural units, its glass transition temperature (Tg) can be calculated using the Fox formula. The Tg of the monomer used to derive the structural units can be the value described in a polymer datasheet or adhesive manual.

[0070] Examples of (meth)acrylates constituting acrylic resins include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, decyl methacrylate, undecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, myristyl methacrylate, pentadecyl methacrylate, palmitate methacrylate, heptadecanyl methacrylate, stearyl methacrylate, etc., which constitute alkyl esters. Alkyl methacrylates with a chain structure having 1 to 18 carbon atoms; cycloalkyl methacrylates such as isobornyl methacrylate and dicyclopentyl methacrylate; aralkyl methacrylates such as benzyl methacrylate; cycloalkenyl methacrylates such as dicyclopentenyl methacrylate; cycloalkenyl methacrylates such as dicyclopentenoxyethyl methacrylate; cycloalkenoxyalkyl methacrylates such as dicyclopentenoxyethyl methacrylate; imide methacrylates; glycidyl methacrylates and other methacrylates containing glycidyl groups; hydroxyl-containing methacrylates such as methyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate; and methacrylates containing substituted amino groups such as N-methylaminoethyl methacrylate. Here, "substituted amino" refers to a group having a structure in which one or two hydrogen atoms of the amino group are replaced by a group other than hydrogen atoms.

[0071] Acrylic resins can be, for example, resins obtained by copolymerizing one or more monomers selected from itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-hydroxymethylacrylamide, in addition to (meth)acrylate or (meth)acrylic acid.

[0072] The monomers that make up acrylic resins can be just one type or two or more types. In the case of two or more types, their combination and ratio can be arbitrarily chosen.

[0073] In one embodiment, the acrylic resin comprises monomers having hydroxyl groups as structural units. In addition to hydroxyl groups, the acrylic resin may also have functional groups such as vinyl, (meth)acryloyl, amino, carboxyl, and isocyanate groups, which can bond with other compounds. These functional groups of the acrylic resin, represented by hydroxyl groups, can be bonded to other compounds via a crosslinking agent (C) described later, or they can be directly bonded to other compounds without a crosslinking agent (C).

[0074] The amount of acrylic resin in the total amount of resin in the adhesive composition can be appropriately set according to the required adhesive strength and storage modulus of the adhesive layer 110, preferably 0% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, further preferably 50% by mass or more, preferably 100% by mass or less, more preferably 95% by mass or less, further preferably 90% by mass or less, and further preferably 80% by mass or less.

[0075] (Energy-reactive resin (B))

[0076] In one embodiment, the adhesive composition forming the adhesive layer 110 comprises an energy-reactive resin (B). An energy-reactive resin (B) is a resin whose elastic modulus increases upon application of energy. It should be noted that the energy-reactive resin can be a resin derived from energy-reactive monomers. In this case, the energy-reactive resin is a resin obtained by polymerizing energy-reactive monomers upon application of energy.

[0077] Energy-reactive resins include those reactive to energy rays and those reactive to heat. Energy-reactive resins are those whose elastic modulus increases upon exposure to energy rays. For example, an energy-reactive resin can be an energy-ray-curing resin. Heat-reactive resins, on the other hand, are those whose elastic modulus increases upon heating. The resin included in the adhesive layer 110 is more preferably a thermoplastic energy-reactive resin, and even more preferably a thermoplastic energy-reactive resin. The type of energy ray is not particularly limited; examples include ultraviolet light, electron beams, or ionizing radiation. Ultraviolet light is preferred as the energy ray, meaning the resin is preferably an ultraviolet-reactive resin.

[0078] Thermoplastic energy-reactive resins are energy-reactive resins that are thermoplastic at least before being given energy. Furthermore, resins derived from energy-reactive resins mean that the resin is obtained from an energy-reactive resin. For example, a resin derived from an energy-reactive resin is a cross-linked energy-reactive resin.

[0079] When using such an energy-reactive resin, the formed uneven shape can be easily maintained by applying energy (e.g., irradiating with energy rays) after the unevenness is formed on the resin.

[0080] As such an energy-reactive resin, a polymer with polymerizable functional groups can be used. A polymerizable functional group is a functional group that crosslinks through the application of energy (e.g., irradiation by energy rays). Examples of such polymerizable functional groups include alkenyl groups such as vinyl and allyl, (meth)acryloyl groups, oxetyl groups, and epoxy groups.

[0081] For example, diene-based rubbers, composed of polymers having polymerizable functional groups at the ends of the main chain and / or on the side chains, can be used as energy-reactive resins. Diene-based rubbers refer to rubbery polymers having double bonds in the polymer main chain. Specific examples of diene-based rubbers include polymers using butadiene or isoprene as monomers (i.e., having butenidyl or pentenidyl as structural units). Preferred energy-reactive resins include polybutadiene resin (PB resin), styrene-butadiene-styrene block copolymer (SBS resin), and styrene-isoprene-styrene block copolymer. These resins can be used as UV-reactive resins.

[0082] From the viewpoint of easily maintaining the uneven shape of the adhesive layer 110, the average number of polymerizable functional groups per molecule of these energy-reactive resins is preferably 1.5 or more, more preferably 2 or more. On the other hand, from the viewpoint of improving the adhesion and flexibility of the adhesive layer 110, this average number is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less.

[0083] The adhesive layer 110 may contain one type of resin or two or more types of resin. In one embodiment, the adhesive layer 110, in addition to containing a thermoplastic resin or a resin derived from a thermoplastic energy-reactive resin, also contains a liquid resin, a resin derived from an energy-reactive liquid resin, or a resin derived from an energy-reactive monomer. A liquid resin refers to a resin that is liquid at room temperature (25°C) before mixing. Furthermore, an energy-reactive liquid resin refers to an energy-reactive resin that is liquid at room temperature (25°C) before mixing and before energy is applied. Furthermore, a resin derived from an energy-reactive monomer refers to a resin obtained by polymerizing an energy-reactive monomer through energy application. Thus, by adding a liquid resin or monomer, the retention and storage modulus of the adhesive layer 110 can be easily controlled.

[0084] In terms of easily maintaining the uneven shape of the adhesive layer 110, a preferred embodiment of the adhesive layer 110 comprises a resin derived from an energy-reactive liquid resin. Examples of such liquid resins include diene-based rubbers, and more specifically, polybutadiene-based resins using butadiene as a monomer.

[0085] In another embodiment, the adhesive layer 110 comprises any combination of resin and resin derived from an energy-reactive liquid resin or an energy-reactive monomer. For example, the adhesive layer 110 may comprise an acrylic resin (A) and a resin derived from an energy-reactive liquid resin or an energy-reactive monomer. With such a combination, it is also easy to apply energy (e.g., irradiation with energy rays) after forming an irregularity on a film of the mixture of acrylic resin (A) and energy-reactive liquid resin or energy-reactive monomer, thereby causing the energy-reactive liquid resin or energy-reactive monomer to polymerize and maintain the formed irregularity.

[0086] Examples of energy-reactive monomers include difunctional or polyfunctional compounds incorporating polymerizable functional groups such as vinyl and allyl groups, (meth)acryloyl groups, oxobutyl groups, and epoxy groups. Preferred examples of energy-reactive monomers include poly(meth)acrylates such as difunctional (meth)acrylates. Thus, the adhesive layer 110 can comprise an energy-curable resin containing poly(meth)acrylates as structural units. Specific examples of poly(meth)acrylates include cycloalkyl di(meth)acrylates such as tricyclodecanediethanol diacrylate.

[0087] Furthermore, the ratio of the energy-reactive resin (B) to the total amount of the components constituting the adhesive layer 110 can be selected based on the desired retention and storage modulus of the adhesive layer 110. For example, this ratio is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 8% by mass or more, further preferably 10% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less.

[0088] Furthermore, as described above, the adhesive layer 110 may comprise an acrylic resin (A) and an energy-reactive resin (B). In this case, the amount of the energy-reactive resin relative to the acrylic resin can be selected based on the desired retention and storage modulus of the adhesive layer 110. For example, the amount of the energy-reactive resin relative to 100 parts by mass of the acrylic resin is preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 8 parts by mass or more, particularly preferably 10 parts by mass or more, preferably 100 parts by mass or less, more preferably 75 parts by mass or less, and further preferably 50 parts by mass or less. In this case, the energy-reactive resin is, for example, an energy-curable resin, such as a resin derived from an energy-curable monomer. Here, parts by mass refers to the mass basis of the solid component, and unless otherwise specified, it is the mass basis.

[0089] (Other components of the adhesive layer)

[0090] The adhesive composition forming the adhesive layer 110 may contain components other than resin. For example, the adhesive composition may contain one or more of a crosslinking agent (C), a photopolymerization initiator (D), an antioxidant (E), and other additives.

[0091] Examples of crosslinking agents (C) include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and metal chelate-based crosslinking agents. These crosslinking agents can be used individually or in combination of two or more.

[0092] Among these crosslinking agents, isocyanate-based crosslinking agents are preferred from the perspectives of improving cohesion and thus adhesion, and ease of acquisition. Examples of isocyanate-based crosslinking agents include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and phenylenediamine diisocyanate; alicyclic polyisocyanates such as dicyclohexylmethane-4,4'-diisocyanate, dicycloheptan triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, methylene bis(cyclohexylene) isocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexylene isocyanate, and hydrogenated phenylenediamine diisocyanate; noncyclic aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; and other polyisocyanate compounds. In addition, as isocyanate-based crosslinking agents, examples include trimethylolpropane adduct-type modifiers of the polyisocyanate compound, biuret-type modifiers formed by reaction with water, and isocyanurate-type modifiers containing isocyanurate rings.

[0093] The adhesive composition may contain one crosslinking agent or two or more crosslinking agents. From the viewpoint of suitable crosslinking reaction, the content of the crosslinking agent in the adhesive composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1% by mass or less.

[0094] For example, the crosslinking agent can be a crosslinking agent for an acrylic resin (A). For example, an isocyanate-based crosslinking agent for an isocyanurate-type modifier can be used as a crosslinking agent for an acrylic resin containing monomers having hydroxyl groups as structural units. In this case, the amount of crosslinking agent relative to the acrylic resin can be selected in a manner that allows for a suitable crosslinking reaction. For example, the amount of crosslinking agent relative to 100 parts by mass of the acrylic resin is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, further preferably 0.2 parts by mass or more, particularly preferably 0.4 parts by mass or more, preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 2 parts by mass or less.

[0095] The photopolymerization initiator (D) initiates the crosslinking reaction by the application of energy (e.g., irradiation by energy rays). In the case where the adhesive composition contains an energy-reactive resin (B), since the adhesive layer 110 also contains the photopolymerization initiator (D), the crosslinking reaction can proceed even with the application of energy at a lower level.

[0096] Examples of photopolymerization initiators (D) include 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, 8-chloroanthraquinone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0097] The adhesive composition may contain one polymerization initiator or two or more polymerization initiators. The content of the photopolymerization initiator in the adhesive composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0098] Examples of antioxidants (E) include hindered phenolic compounds, aromatic amine compounds, sulfur compounds, or phosphate compounds.

[0099] Other additives that may be included in the adhesive layer 110 are not particularly limited, such as ultraviolet absorbers such as benzotriazole compounds, oxazolamide compounds or benzophenone compounds; light stabilizers such as hindered amines, benzophenones or benzotriazoles; resin stabilizers such as imidazole resin stabilizers, dithiocarbamate resin stabilizers, phosphorus resin stabilizers or thioester resin stabilizers; fillers, pigments, extenders and softeners, etc.

[0100] When the adhesive layer 110 contains these additives, the content of the additives in the adhesive layer 110 is preferably 0.0001% by mass or more, more preferably 0.01% by mass or more, particularly preferably 0.1% by mass or more, further preferably 1% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less.

[0101] (Shape of the adhesive layer)

[0102] The adhesive layer 110 of this embodiment has an uneven surface. In one embodiment, the adhesive layer 110 has a plurality of protrusions on its surface that are defined by recesses and are separated from each other. The plurality of protrusions can be separated by recesses that are continuous throughout the entire adhesive layer 110.

[0103] Figure 2A and Figure 2B This is a side view showing the shape of the adhesive layer 110. Figure 3A , Figure 3B as well as Figure 3C This is a top view showing the shape of the adhesive layer 110. Figure 2A and Figure 3AAn example of the adhesive layer 110 before expansion is shown. Figure 2B and Figure 3B An example of the expanded adhesive layer 110 is shown. Furthermore, in Figure 2A and Figure 2B The image depicts an element 140 held by a protrusion 111 of an adhesive layer 110. On the other hand, in... Figure 3A , Figure 3B as well as Figure 3C The element 140 held by the protrusion 111 is omitted.

[0104] like Figure 2A and Figure 3A As shown, protrusions 111 can be regularly arranged on the surface of the adhesive layer 110. Regular arrangement of protrusions means that the protrusions are arranged in a straight line at fixed intervals. Alternatively, the protrusions 111 can be arranged with regularly varying intervals. For example, the interval between protrusions may be shorter in the center of the adhesive sheet and longer at the periphery. Furthermore, the protrusions can also be irregularly arranged.

[0105] Figure 3C This is a top view showing another shape of the adhesive layer 110. (Example) Figure 3C As shown, striped protrusions 111 may also be provided on the surface of the adhesive layer 110. Figure 3C In the design, linear protrusions 111 with a fixed width are arranged at fixed intervals. The width or interval of the linear protrusions 111 can vary regularly, or the linear protrusions 111 can be arranged irregularly.

[0106] In this embodiment, the adhesive sheet is expanded. Figure 2A and Figure 3A The adhesive layer 110 shown is deformed as follows Figure 2B and Figure 3B The adhesive layer 110' is shown. Comparing adhesive layer 110 and adhesive layer 110', in adhesive layer 110', by expansion, the spacing P of each protrusion 111 increases, and the number of protrusions 111 holding an element 140 decreases. Therefore, in adhesive layer 110', the force holding the element 140 by the protrusions 111 is reduced compared to adhesive layer 110. Furthermore, by expanding the adhesive sheet, shear stress acts between the protrusions 111 and the element 140. The inventors of this application have observed that this is also related to the reduced holding force of the protrusions 111 on the element 140.

[0107] From the viewpoint of adjusting the holding force, the spacing P of the protrusions 111 before expansion is preferably 1 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, and even more preferably 15 μm or more. On the other hand, from the viewpoint of increasing the contact area between the adhesive layer 110 and the object to improve the holding force, this spacing P is preferably 100 μm or less, more preferably 75 μm or less, even more preferably 50 μm or less, even more preferably 35 μm or less, and even more preferably 25 μm or less. Here, the spacing P of the protrusions 111 refers to the distance between the center point of any chosen protrusion 111 and the center point of the other protrusion 111 closest to that protrusion 111. For example, in Figure 2A In the case where the protrusions 111 are arranged at fixed intervals, the spacing P represents the distance between the center point of the protrusions 111 on a straight line and the center point of the nearest other protrusion 111. When the protrusions 111 are arranged on multiple straight lines, the spacing P represents the distance between the center points of the protrusions on the straight line with the shortest spacing. In this specification, the interval between the protrusions 111 refers to the interval between the centers of the protrusions.

[0108] The specific shape of the protrusion 111 is not particularly limited. For example, the protrusion 111 may be in the shape of a pillar. As a specific example, the protrusion 111 may be cylindrical or prismatic. Furthermore, as mentioned above, the protrusion 111 may extend in a linear shape or in a wavy or other curved shape. Moreover, a tapered portion may also be provided in these protrusions 111.

[0109] Figure 4A A cross-sectional view of an adhesive layer 110 according to one embodiment, passing through the protrusion 111 and perpendicular to the surface of the adhesive layer 110, is shown. Figure 4A The convex portion 111 shown has a tapered portion, meaning that the tip of the convex portion 111 tapers. Furthermore, as... Figure 4B As shown, the top end of the protrusion 111 can also be curved. With this configuration, the impact when holding an object using the adhesive layer 110 is further mitigated, thus the adhesive layer 110 easily holds the object without shifting. Alternatively, the top end of the protrusion can also be flat.

[0110] like Figure 4A As shown, the surface of the adhesive layer 110 may have flat recesses and protrusions 111 protruding from the recesses. In this way, the multiple protrusions 111 of the adhesive layer 110, which are separated from each other, can also be defined by the recesses.

[0111] As another example, such as Figure 4B As shown, the convex portion can be hemispherical or part of a sphere. Furthermore, as... Figure 4CAs shown, the protrusion 111 can also be T-shaped. As yet another example, the protrusion 111 can be a shape formed by the aggregation of multiple particles, mushroom-shaped, lotus leaf-like, or needle-like. As yet another example, the surface of the adhesive layer 110 can be rough or fibrous, and such a surface can also be described as having unevenness.

[0112] From the viewpoint of maintaining the holding force of the object, the width or diameter of each protrusion 111 is preferably 1 μm or more, more preferably 2 μm or more, further preferably 5 μm or more, and even more preferably 10 μm or more. On the other hand, from the viewpoint of improving the ease of peeling off the object, it is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and even more preferably 20 μm or less. Here, the width and diameter of the protrusion 111 refer to the minimum distance and maximum distance (in the case of two parallel lines connecting the two sides of the protrusion 111 on the surface of the recess, respectively) Figure 4A (represented by D).

[0113] Furthermore, from the viewpoint of maintaining the holding force of the object, the area of ​​each protrusion 111 is preferably 10 μm. 2 The above, and more preferably 20μm 2 The above, and more preferably 30μm 2 That's all. On the other hand, from the viewpoint of improving the ease of peeling off the object, 2000 μm is preferred. 2 The following, and more preferably, is 1000 μm 2 The following, and more preferably 500μm 2 Below. Here, the area of ​​the protrusion 111 refers to the area of ​​the portion protruding from the surface of the concave portion (in... Figure 4A In the case of a circle with diameter D, the area is...

[0114] In one embodiment, from the viewpoint of improving the ease of peeling off the object, the height of each protrusion 111 is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. On the other hand, from the viewpoint of improving morphological stability, the height of each protrusion 111 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. This allows for variation in the object's holding force. Here, the height of the protrusion 111 is... Figure 4A The letter H represents the number of protrusions. Furthermore, in one embodiment, the height of the plurality of protrusions in the adhesive layer 110 is uniform. In another embodiment, the adhesive layer 110 may include a first plurality of protrusions having a first uniform height and a plurality of second protrusions having different heights. Here, the plurality of second protrusions may have a second uniform height. For example, protrusion 111 may be composed of such first and second protrusions. In yet another embodiment, the adhesive layer 110 may also have a plurality of protrusions with random heights.

[0115] Furthermore, from the viewpoint of maintaining the holding force of the object, the total area of ​​the protrusions 111 relative to the area of ​​the adhesive layer 110 is preferably 1% or more, more preferably 5% or more, even more preferably 10% or more, even more preferably 18% or more, and even more preferably 40% or more. On the other hand, from the viewpoint of improving the ease of peeling off the object, the total area of ​​the protrusions relative to the area of ​​the adhesive layer 110 is preferably 95% or less, more preferably 75% or less, and even more preferably 60% or less.

[0116] The unevenness of the adhesive layer 110 can be designed according to the shape of the object held by the adhesive sheet. For example, from the viewpoint of maintaining the holding force of the object, the ratio of the bonding area of ​​the adhesive layer 110 to the area of ​​the object is preferably 1% or more, more preferably 2% or more, further preferably 3% or more, further preferably 4% or more, further preferably 5% or more, further preferably 7% or more, and further preferably 10% or more. On the other hand, from the viewpoint of improving the ease of peeling off the object, the ratio of the bonding area of ​​the adhesive layer 110 to the area of ​​the object is preferably 95% or less, more preferably 70% or less, further preferably 50% or less, and further preferably 30% or less. Figure 4A In this case, the bonding area is equivalent to the area of ​​a circle with diameter T. It should be noted that the bonding area may change if the position of the object on the adhesive sheet shifts. In this case, it is preferable that the ratio of the bonding areas falls within the above range regardless of the position of the object being treated.

[0117] (Characteristics of the adhesive layer)

[0118] In one embodiment of the adhesive sheet, the amount of work required to peel an object from the adhesive layer 110 is adjusted. For example, from the viewpoint of picking up the object under gentler conditions, after pressing the mirror surface of a silicon chip with dimensions of 5.0 mm × 5.0 mm onto the adhesive layer of the adhesive sheet with a contact pressure of 0.3 MPa, the amount of work required to peel the silicon chip from the adhesive layer is 25 μJ or less, preferably 15 μJ or less, more preferably 10 μJ or less, and even more preferably 7 μJ or less. On the other hand, from the viewpoint of ensuring the holding force of the object, under the same conditions, the amount of work required to peel the silicon chip from the adhesive layer is 0.1 μJ or more, more preferably 0.3 μJ or more, and even more preferably 0.7 μJ or more.

[0119] This amount of work can be evaluated by measuring probe adhesion at 23°C and under a contact load of 8N. Specifically, a probe with a silicon chip of dimensions 5.0mm × 5.0mm is fixed at its tip. The chip is then pressed against the adhesive layer of the adhesive sheet with a contact pressure of 0.3MPa, with the mirror surface of the silicon chip in contact with the adhesive layer, and the probe adhesion at the chip-adhesive layer interface is measured. The amount of work is represented by the area under the graph showing the relationship between the probe's travel distance and the adhesive force.

[0120] Such work can be adjusted, for example, by controlling the composition of the adhesive layer 110. For example, the work can be reduced by increasing the proportion of the energy-reactive resin constituting the adhesive layer 110 or by increasing the proportion of the crosslinking agent.

[0121] It should be noted that the inventors of this application have studied the force required to peel an object from the adhesive layer 110 and found that the force required to peel an object from the adhesive layer 110 is not fixed, depending on the stretching position on the silicon chip, etc. On the other hand, according to the inventors' research, they found that by controlling the amount of work done as described above, an object can be stably picked up from the adhesive layer 110 under gentle conditions. Furthermore, in one embodiment, the object is peeled from the adhesive layer 110 after the adhesive sheet is expanded, but by adjusting the amount of work done before expansion as described above, the object can be easily peeled from the expanded adhesive sheet.

[0122] In one embodiment of the adhesive sheet, the tensile breaking stress of the adhesive layer 110 is adjusted. For example, from the viewpoint of being able to pick up objects under gentler conditions, the tensile breaking stress of the adhesive layer 110 at 23°C is 20 MPa or more, preferably 22 MPa or more, and more preferably 23 MPa or more. On the other hand, from the viewpoint of ensuring the holding force of the object, the tensile breaking stress of the adhesive layer 110 at 23°C is 100 MPa or less, preferably 50 MPa or less, more preferably 40 MPa or less, and even more preferably 30 MPa or less.

[0123] It should be noted that the tensile fracture stress of the adhesive layer 110 can be determined using a viscoelastic measuring device at a test temperature of 23°C and a strain rate of 0.1 / s by uniaxial tensile viscosity measurement. The sample used in the measurement can be prepared by cutting it from the adhesive sheet. There are no particular limitations on the sample size; for example, a sample with a width of 5 mm, a length of 30 mm, and a thickness of 0.1 mm can be used.

[0124] Such tensile stress at break can be adjusted, for example, by controlling the composition of the adhesive layer 110. For example, the tensile stress at break can be increased by increasing the proportion of the energy-reactive resin constituting the adhesive layer 110 or by increasing the proportion of the crosslinking agent.

[0125] The inventors of this application have observed that by controlling the tensile fracture stress of the adhesive layer 110 as described above, the adhesive layer 110 tends to extend along the substrate 120 when the adhesive sheet is extended. Therefore, shear stress is easily generated between the object and the adhesive layer 110, thus making it easier to pick up the object.

[0126] In one embodiment of the adhesive sheet, the adhesive force of the adhesive layer 110 is adjusted. For example, from the viewpoint of being able to pick up objects under gentler conditions, the adhesive force of the adhesive layer 110 to the silicon mirror, measured at a peel angle of 180 degrees and a peel speed of 300 mm / min, is 35 mN / 50 mm or less, preferably 30 mN / 50 mm or less, and more preferably 28 mN / 50 mm or less. On the other hand, from the viewpoint of ensuring the retention force of the object, the adhesive force of the adhesive layer 110 based on the same measurement conditions is 1 mN / 50 mm or more, preferably 3 mN / 50 mm or more, more preferably 10 mN / 50 mm or more, and even more preferably 15 mN / 50 mm or more.

[0127] It should be noted that the adhesive force of the adhesive layer 110 can be measured using a tensile testing machine at 23°C and 50%RH (relative humidity) according to JIS Z0237:2000. Furthermore, in one embodiment, the object is peeled off from the adhesive layer 110 after the adhesive sheet is expanded, but by adjusting the adhesive force before expansion as described above, the object can be easily peeled off from the expanded adhesive sheet.

[0128] Such adhesive strength can be adjusted, for example, by controlling the composition of the adhesive layer 110. For example, by increasing the proportion of the energy-reactive resin constituting the adhesive layer 110, or by increasing the proportion of the crosslinking agent, a tendency to decrease adhesive strength can be observed.

[0129] (Sheet peeling)

[0130] In addition, such as Figure 1 As shown, the adhesive sheet in this embodiment may also include a release sheet 150, which is in contact with the adhesive layer 110 and has a surface with irregularities complementary to the surface with irregularities of the adhesive layer 110. For illustration, in Figure 1 The image shows the state in which the adhesive layer 110 is separated from the release sheet 150.

[0131] The release sheet 150 has a release layer 160. The release layer 160 is a layer that is easily peelable from the adhesive layer 110. The release layer 160 may have a surface that is complementary to the surface of the adhesive layer 110. That is, the release layer 160 has a recess 161, which has a shape complementary to the convex portion 111. However, it is not necessary for the recess 161 to have a shape complementary to the convex portion 111.

[0132] The release sheet 150 may have a substrate 170 on a surface that does not contact the adhesive layer 110. This substrate 170 may be designed identically to the substrate 120, but does not need to have the same composition or structure. For example, the material of the substrate 120 may be EMAA, and the material of the substrate 170 may be polyethylene terephthalate. Furthermore, the release sheet 150 may have an undercoat (not shown) between the release layer 160 and the substrate 170.

[0133] (Other layers)

[0134] The sheet material described above may have layers other than a substrate and an adhesive layer. For example, another adhesive layer may be provided on the substrate on the side opposite to the adhesive layer. With the aid of such an adhesive layer, the sheet material can be adhered to other objects. The type of the other adhesive layer is not particularly limited; for example, a common adhesive can be used to form the other adhesive layer.

[0135] (Manufacturing methods for adhesive layers and sheets)

[0136] There are no particular limitations on the manufacturing methods of the adhesive layer and the sheet. For example, a sheet with an adhesive layer 110 on a substrate 120 can be manufactured as follows: First, an organic solvent is added to a raw material composition containing the components of the adhesive layer 110 to prepare a solution of the raw material composition. Then, the solution is coated onto the substrate 120 to form a coating film, and then dried, thereby providing an adhesive layer on the substrate 120. Furthermore, by performing a surface treatment to create an uneven surface on the adhesive layer, an adhesive layer 110 with uneven surfaces can be formed.

[0137] Examples of organic solvents used in preparing solutions of raw material compositions include toluene, ethyl acetate, and methyl ethyl ketone. Examples of coating methods for the solution include spin coating, spray coating, bar coating, doctor blade coating, roller coating, roller knife coating, doctor blade coating, die coating, gravure coating, and printing methods (e.g., screen printing and inkjet printing).

[0138] There are no particular limitations on the process of creating irregularities on the surface of the adhesive layer 110. For example, an embossing method can be used to create irregularities on the surface of the adhesive layer 110. In the embossing method, a mold with a shape on the surface that is complementary to the irregularities to be created can be used. Specifically, irregularities can be created on the surface of the adhesive layer by pressing the adhesive layer onto the substrate with a mold while heating the adhesive layer. As a more specific method, the adhesive layer can be pressed with a mold, heated and maintained for a specified time, then cooled and the mold removed. When heating the adhesive layer, for example, the adhesive layer can be heated to a temperature higher than the softening point of the adhesive layer. Furthermore, there is no particular limitation on the time the adhesive layer is held in the heated state; for example, it can be held for more than 10 seconds or less than 10 minutes. As a specific method for heating the adhesive layer while pressing it with a mold, a method of vacuum laminating the adhesive layer onto the substrate with a mold can be cited. It should be noted that, instead of performing the two-stage process of forming the adhesive layer and forming the irregularities, an adhesive layer with irregularities on the surface can be formed on the substrate in a single-stage process. In addition, a release sheet 150 having a release layer 160 with irregularities as described above can also be used as a mold.

[0139] As another method, the adhesive layer 110 with a rough surface can be formed by spraying a solution of the raw material composition. Alternatively, the adhesive layer 110 with a rough or fibrous surface can be formed by adding filler to a solution of the raw material composition and then coating such a solution. Yet another method, the adhesive layer 110 with an uneven shape can be directly formed on the substrate 120 by coating a solution of the raw material composition according to a desired pattern using a printing method such as inkjet printing.

[0140] (Instructions for using adhesive sheets)

[0141] The adhesive sheet of this embodiment can be used to process objects. For example, the adhesive sheet of this embodiment can be used to temporarily hold an object. Furthermore, the adhesive sheet of this embodiment can be used to transfer objects. As a specific example, the adhesive sheet of this embodiment can be used to transfer a semiconductor chip obtained by cutting to a desired location. (See also...) Figure 6 The flowchart describes the method for processing an object using the adhesive sheet of this embodiment.

[0142] (S10: Object retention)

[0143] In S10, an object is held on the adhesive layer of the adhesive sheet in this embodiment. It should be noted that the type of object is not particularly limited. The object can be, for example, a component. Examples of components include: semiconductor chips such as LED chips, semiconductor chips with protective films, and semiconductor chips with die-attach film (DAF). Furthermore, the component can be a miniature light-emitting diode, a power device, a MEMS (Micro Electromechanical Systems) chip, or a controller chip, or a component thereof. Additionally, the component can be a monolithic material such as a wafer, panel, or substrate. For example, the component can have a circuit surface on which an integrated circuit with circuit objects such as transistors, resistors, and capacitors is formed. Furthermore, the component is not necessarily limited to a monolithic material; it can also be various non-monolithic wafers or various substrates.

[0144] Furthermore, the size of the object is not particularly limited. For example, the size of the object can preferably be 100 μm. 2 The above, and more preferably 500μm 2 The above, and more preferably 1000μm 2 That's all. On the other hand, the object's size can also preferably be 100mm. 2 The following, or more preferably, is 25mm 2 The following, and more preferably 1mm 2 the following.

[0145] Examples of wafers include silicon wafers, silicon carbide (SiC) wafers, and compound semiconductor wafers (e.g., gallium phosphide (GaP) wafers, gallium arsenide (GaAs) wafers, indium phosphide (InP) wafers, and gallium nitride (GaN) wafers). The size of the wafer is not particularly limited, but is preferably 6 inches (approximately 150 mm in diameter) or larger, more preferably 12 inches (approximately 300 mm in diameter) or larger. It should be noted that the shape of the wafer is not limited to a circle; for example, it can also be square or rectangular.

[0146] Examples of panels include fan-out semiconductor packages (such as FOWLP or FOPLP). That is, the object being processed can be a semiconductor package before or after monolithization in fan-out semiconductor packaging manufacturing technology. The size of the panel is not particularly limited; for example, it can be a square substrate of approximately 300–700 mm.

[0147] Examples of substrates include glass substrates, sapphire substrates, and compound semiconductor substrates.

[0148] In one embodiment, an element is transferred from a holding substrate to an adhesive sheet, where the adhesive sheet holds the transferred element. For example, a semiconductor wafer can be attached to a wafer substrate and then diced. The element on the wafer substrate obtained by dicing can then be bonded to the adhesive layer 110 of the adhesive sheet. Then, by applying external stimulation such as a laser, the adhesion between the wafer substrate and the element can be reduced. Through this process, the element can be transferred from the wafer substrate to the adhesive sheet. Alternatively, by transferring the element obtained by dicing a semiconductor wafer to a holding substrate, a holding substrate with the element attached can be obtained. Then, the element attached to the holding substrate can be transferred to the adhesive layer 110 of the adhesive sheet using the same method.

[0149] In another embodiment, the element adhered to the holding substrate can also be separated from the holding substrate by external stimulation. Specifically, the element is separated relative to the holding substrate. Furthermore, the element is brought relatively close to the adhesive sheet. Then, by bringing the element into contact with the adhesive layer 110 of the adhesive sheet, the element is separated from the holding substrate and captured onto the adhesive sheet. The type of external stimulation is not particularly limited; examples include energy application, cooling, expansion of the holding substrate, and physical stimulation (e.g., pressing the back of the holding substrate with a pin). By using one or more of these external stimuli, the bonding force between the holding substrate and the element can be reduced, and the element can be separated from the holding substrate. For example, the element can be separated from the holding substrate by irradiating a laser (laser peeling). In such an embodiment, pressure is generated between the element and the adhesive layer 110 when the separated element approaches the adhesive layer 110. However, by making the surface of the adhesive layer 110 uneven, the pressure generated between the element and the adhesive layer 110 is mitigated, thus making it easier to capture the element at the desired position on the adhesive sheet.

[0150] In another embodiment, a semiconductor wafer is bonded to the adhesive layer 110 of the adhesive sheet. Then, the semiconductor wafer on the adhesive layer 110 is cut to form an element. In this way, the adhesive sheet can also hold the element.

[0151] (S20: Extension of adhesive sheet)

[0152] In one embodiment of the object processing method, the adhesive sheet of the object is extended along the surface direction. Figure 6 In the flowchart shown, the adhesive sheet extends along the surface direction in S20. (Refer to...) Figure 2A , Figure 2B , Figure 3A , Figure 3B as well as Figure 3CAs described above, by expanding the adhesive sheet, the holding force of the object is reduced, thus making it easier to peel the object off in subsequent processes. From the viewpoint of sufficiently reducing the holding force of the object, the adhesive sheet in one embodiment can be expanded by more than 1% or more in the planar direction (e.g., one direction or two orthogonal directions), or by more than 5%.

[0153] There is no particular limitation on the method of expanding the adhesive sheet. For example, the expansion of the adhesive sheet can be carried out in one direction, in two directions, or in multiple directions. There is also no particular limitation on the expansion rate of the adhesive sheet. For example, from the viewpoint of sufficiently reducing the holding force of the object, the expansion rate of the adhesive sheet in one direction can be 1% or more, or 5% or more. Furthermore, from the viewpoint of preventing breakage of the adhesive sheet, the expansion rate of the adhesive sheet in one direction can be 50% or less, or 20% or less. From the same viewpoint, the expansion rate of the adhesive sheet in two mutually orthogonal directions can be 1% or more, or 5% or more; on the other hand, it can be 50% or less, or 20% or less.

[0154] As a specific example, the adhesive sheet is fixed to the frame, and the base is pressed into the adhesive sheet within the frame, thereby allowing the adhesive sheet to expand. (See reference...) Figure 5A and Figure 5B Let's illustrate this with an example. Figure 5A The states of the adhesive sheet retaining elements 140a to 140d are shown. For example... Figure 5A As shown, the outer periphery of the adhesive sheet can be fixed to the frame 320. The shape of the frame 320 is not particularly limited. For example, the frame 320 can be a circular or rectangular frame member with an opening. In one embodiment, a circular annular frame is used as the frame. By using the annular frame, the adhesive sheet can be extended in all directions.

[0155] Then, the adhesive sheet fixed to the frame 320 is brought into contact with the base 310, and then... Figure 5B The frame 320 is displaced (pulled down) towards the base 310, thereby expanding the adhesive sheet. It should be noted that the base 310 is not particularly limited in its construction; for example, it may be cylindrical or cuboid in shape. Furthermore, the base 310 may also be mesh-like or annular. The frame 320 may displace relative to the base 310 at a speed of 0.1 mm / sec or more, or at a speed of 1 mm / sec or more. In this case, from the viewpoint of sufficiently reducing the holding force on the object, the amount of displacement of the frame 320, i.e., the pulling-down amount, may be, for example, 1 mm or more, or 5 mm or more. On the other hand, from the viewpoint of suppressing breakage of the adhesive sheet, the amount of displacement of the frame 320 may be 30 mm or less, or 20 mm or less.

[0156] (S30: Peeling off the object)

[0157] In S30, the object is peeled off from the adhesive layer 110 of the adhesive sheet. Figure 6 In the flowchart, the object is peeled off from the adhesive layer 110 of the adhesive sheet after it has been extended along the surface direction. The method of peeling off the object is not particularly limited. For example, the method described above can be used as a method for transferring an object adhered to a holding substrate to the adhesive sheet. Specifically, an adsorption member such as a vacuum chuck can be used to peel the object off the adhesive layer 110 of the adhesive sheet. Then, the adsorbed object can be moved to the desired position at the transfer destination. By expanding the adhesive sheet and reducing the holding force generated by the adhesive layer 110, the object can be peeled off from the adhesive layer 110 of the adhesive sheet without applying physical stimulation such as pressing with a pin to the opposite side of the adhesive layer 110.

[0158] It should be noted that, according to the research of the inventors of this application, when attempting to peel an object from the adhesive layer 110 using an adsorption member without physical stimulation, if the adsorption force is increased to match the height of the holding force of the adhesive layer 110, the object, such as the component, is prone to breakage. Therefore, in this embodiment, the adhesive force of the adhesive layer 110 has been adjusted.

[0159] This process allows for the transfer of objects to any desired destination using adhesive sheets. Furthermore, this transfer method can be used to manufacture electronic components or semiconductor devices. It should be noted that the object held by the adhesive sheet can be processed or manufactured.

[0160] Example

[0161] The present invention will be described in more detail below with reference to specific examples. However, the present invention is not limited to any of the examples described below. Unless otherwise specified, the parts and percentages in the examples refer to the mass of the solid components.

[0162] The following compounds were used in the examples and comparative examples.

[0163] <(A) Composition: Acrylic resin>

[0164] As an acrylic resin, an acrylic copolymer is used (monomer mass ratio: 2-ethylhexyl acrylate / 2-hydroxyethyl acrylate / acrylic acid = 92.8 / 7.0 / 0.2, mass-average molecular weight (Mw): 1.1 million).

[0165] <(B) Component: Energy-reactive resin>

[0166] Tricyclodecanediethanol diacrylate is used as an energy-reactive resin.

[0167] <(C) Component: Crosslinking Agent>

[0168] As a crosslinking agent, an isocyanurate-type polyisocyanate derived from hexamethylene diisocyanate is used.

[0169] <(D) Component: Photopolymerization initiator>

[0170] 2,4,6-Trimethylbenzoyldiphenylphosphine oxide was used as the photopolymerization initiator.

[0171] <Evaluation of Tensile Fracture Stress>

[0172] The tensile fracture stress of the adhesive layer used in each embodiment was determined as follows. An adhesive layer with a thickness of 0.1 mm was prepared from the adhesive composition obtained in each embodiment. The resulting adhesive layer was cut into pieces 5 mm wide and 30 mm long. Using a viscoelasticity measuring device (Anton Paar, product name "MCR302"), the tensile fracture stress of the adhesive layer at 23°C was determined by uniaxial tensile viscosity measurement at a test temperature of 23°C and a strain rate of 0.1 / s.

[0173] <Pick-up Evaluation>

[0174] The selection and evaluation of the components of the adhesive sheet obtained in each embodiment were carried out in the following manner. First, the adhesive layer of the adhesive sheet obtained in each embodiment was glued to an annular frame (made of stainless steel, with an inner diameter of 194 mm), and the adhesive sheet was cut according to the outer diameter of the annular frame.

[0175] Next, the wafer substrate (mirror-finished silicon wafer, 6 inches, 150 μm thick) was fixed onto a separately prepared dicing tape. The wafer substrate was then cut into 8.2 mm × 8.2 mm squares, thus obtaining multiple components (silicon chips, each 8.2 mm × 8.2 mm × 150 μm in size). These components were then bonded to the adhesive layer of the adhesive sheet at the center of the inner side of the aforementioned annular frame, with the mirror finish attached to the adhesive layer. Bonding was performed by lamination at room temperature (23°C). Then, the components were transferred from the dicing tape to the adhesive sheet by peeling off the dicing tape. This yielded an adhesive sheet containing multiple components and supported by the annular frame, which served as an evaluation sample.

[0176] The obtained evaluation sample was placed on the pickup device (manufactured by Canon Machinery Co., Ltd., product name "BESTEM-D510"). After expanding the adhesive sheet, a vacuum suction chuck was used to pick up the component. It should be noted that the expansion of the adhesive sheet is as follows... Figure 6The process is as shown. That is, with the element supported by the base 310 across the adhesive sheet, the frame 320, which serves as a ring frame, is pulled down 10 mm relative to the base 310, thereby expanding the adhesive sheet. Furthermore, in this evaluation, it is assessed whether the element can be picked up without using a needle to press against the side of the adhesive sheet opposite to the element to be adsorbed (the substrate).

[0177] (Example 1)

[0178] An adhesive composition was prepared by dissolving the amounts of acrylic resin (A), energy-reactive resin (B), crosslinking agent (C), and photopolymerization initiator (D) shown in Table 1 in toluene. Table 1 shows the parts by weight of the solid components of each material.

[0179] The adhesive composition was applied to the release surface of a release sheet (manufactured by Lintec Corporation, trade name: SP-PET382150, which is formed by laminating an organosilicon-based release agent on a polyethylene terephthalate film, with a thickness of 38 μm), and the resulting coating was dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 25 μm.

[0180] On this adhesive layer, an EMAA film (ethylene-methacrylic acid copolymer film, acid content 9% by mass, formed by embossing one side of the surface into a pear skin shape, thickness 80μm) is used as the substrate, and the non-embossed side of the EMAA film is bonded to the adhesive layer.

[0181] After peeling off the release sheet, the adhesive layer is bonded to a pre-formed concave mold and vacuum-laminated at 60°C for 300 seconds. Next, an ultraviolet irradiation machine (Heraeus) is used with an illuminance of 130 mW / cm². 2 Light intensity 210 mJ / cm 2 Ultraviolet light is used to create an adhesive sheet with a textured surface. The textured surface of the adhesive layer of the adhesive sheet is similar to... Figure 2A Similarly, the columns are arranged in a grid-like shape. The spacing P between the columns in the adhesive sheet is 20 μm. Furthermore, Figure 4A The height (H) of each pillar shown is 8 μm, the diameter (T) of the top end is 8 μm, and the diameter (D) of the base is 16 μm. Furthermore, the ratio of the area of ​​the adhesive layer to the area of ​​the bonding portion of the element to be captured (i.e., the area of ​​the top surface of the protrusion) to the area of ​​the adhesive sheet is approximately 12.6%. It should be noted that, as the aforementioned replication mold, a replication mold with a surface shape complementary to such a concave-convex shape is used.

[0182] The adhesive strength of the adhesive layer was evaluated using the prepared adhesive composition according to the method described above. Furthermore, the pick-up performance of the elements held in the obtained adhesive sheet was evaluated according to the method described above. The evaluation results are shown in Table 1. In the pick-up evaluation, "A" indicates pick-up capability, and "F" indicates non-pick-up capability.

[0183] (Examples 2-3)

[0184] Using the amounts of energy-reactive resin (B) and photopolymerization initiator (D) shown in Table 1, except that the adhesive composition was prepared in the same manner as in Example 1, and an adhesive sheet was made.

[0185] (Comparative Examples 1 to 3)

[0186] Using the amounts of energy-reactive resin (B), crosslinking agent (C), and photopolymerization initiator (D) shown in Table 1, except that the adhesive composition was prepared in the same manner as in Example 1, and an adhesive sheet was made.

[0187]

[0188] A comparison of Examples 1 to 3 with Comparative Examples 1 to 3 shows that when the tensile fracture stress of the adhesive layer is 20 MPa or more, the chuck can be used to pick up the element.

[0189] (Examples 4 to 6)

[0190] An adhesive composition was prepared by dissolving the energy-reactive resin (B'), crosslinking agent (C), and photopolymerization initiator (D') in toluene in the amounts shown in Table 2. An adhesive sheet was then produced using this adhesive composition in the same manner as in Example 1. The following substances were used as components (B') and (D').

[0191] <(B') Component: Energy-reactive resin>

[0192] As an energy-reactive resin, an energy-reactive group is introduced into the polymer side chain via hydroxyl groups by reacting an acrylic copolymer (monomer mass ratio: butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 52 / 20 / 28) with 2-hydroxyethyl acrylate in a 90% equivalent amount of 2-hydroxyethyl acrylate. The resin has mass-average molecular weight (Mw): 520,000, number-average molecular weight (Mn): 155,000.

[0193] <(D') Component: Photopolymerization initiator>

[0194] 1-Hydroxycyclohexylphenyl ketone was used as the photopolymerization initiator.

[0195]

[0196] In Examples 4 to 6, it was also confirmed that when the tensile fracture stress of the adhesive layer is 20 MPa or more, the chuck can be used to pick up the element.

[0197] The invention is not limited to the above-described embodiments and can be modified and altered in various ways within the scope of the invention's intent.

[0198] This application claims priority based on Japanese Patent Application No. 2023-156493, filed on September 21, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An adhesive sheet having an adhesive layer having an uneven surface, wherein the tensile breaking stress of the adhesive layer at 23°C is 20 MPa or more.

2. The adhesive sheet according to claim 1, wherein, The tensile fracture stress is below 100 MPa.

3. The adhesive sheet according to claim 1, wherein, The adhesive sheet further comprises a release layer having a surface with irregularities that are complementary to the surface with irregularities of the adhesive layer.

4. The adhesive sheet according to claim 1, wherein, The adhesive sheet can expand by more than 1% along the surface direction.

5. The adhesive sheet according to claim 1, wherein, The adhesive layer has a plurality of protrusions that are separated from each other and whose boundaries are defined by recesses, wherein the spacing between the plurality of protrusions is more than 1 μm and less than 100 μm.

6. The adhesive sheet according to claim 1, wherein, The adhesive layer has multiple protrusions, and the height of the multiple protrusions is uniform.

7. The adhesive sheet according to claim 1, wherein, The adhesive layer comprises an acrylic resin and an energy-curable resin.

8. The adhesive sheet according to claim 7, wherein, The energy-curable resin contains poly(meth)acrylates as structural units.

9. The adhesive sheet according to claim 7, wherein, The energy-curable resin is at least 8 parts by mass relative to 100 parts by mass of the acrylic resin.

10. The adhesive sheet according to claim 7, wherein, The adhesive layer further comprises a crosslinking agent of the acrylic resin, wherein the crosslinking agent is present in an amount of 0.05 parts by mass or more relative to 100 parts by mass of the acrylic resin.

11. A method for processing an object, the method comprising: The holding process involves holding an object on the adhesive layer of the adhesive sheet according to any one of claims 1 to 10; and The peeling process involves peeling the object from the adhesive layer of the adhesive sheet.

12. The method for processing an object according to claim 11, wherein, The method for processing the object further includes an extension step, in which the adhesive sheet holding the object is extended along the surface direction. In the peeling process, the object is peeled off from the adhesive layer of the adhesive sheet after it has been extended along the surface direction.

13. The method for processing an object according to claim 11, wherein, In the peeling process, an adsorption member is used to peel the object from the adhesive layer of the adhesive sheet.

14. The method for processing an object according to claim 11, wherein, In the peeling process, the object is peeled from the adhesive layer of the adhesive sheet without applying physical stimulation to the opposite side of the adhesive layer.

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