Method for peeling object from adhesive sheet and method for manufacturing article

Abstract

The present invention makes it possible to peel an object, held on an adhesive sheet provided with an adhesive layer having recesses and protrusions on the surface, by a milder operation.　A method for peeling an object from an adhesive sheet comprising a substrate and an energy ray-sensitive adhesive layer having recesses and protrusions on the surface. The adhesive sheet holding the object on the adhesive layer expands in a surface direction. The adhesive layer of the adhesive sheet expanded in the surface direction is irradiated with energy rays. The object is peeled from the adhesive layer of the adhesive sheet irradiated with energy rays.

Description

Method for peeling an object from an adhesive sheet and method for manufacturing an article.

[0001] This invention relates to a method for peeling an object from an adhesive sheet and a method for manufacturing an article, and more particularly to the manufacturing of a semiconductor chip.

[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 position.

[0003] On the other hand, in order to improve production efficiency, it is also required to make it easier to peel objects off the adhesive sheet. For example, Patent Document 1 discloses an adhesive sheet having an adhesive layer that is expandable in the planar direction and has irregularities on its surface, configured to facilitate the peeling of objects.

[0004] International Publication No. 2024 / 063124

[0005] When using adhesive sheets, it is desirable that they possess both object-holding power and ease of removal of objects from the sheet. In particular, when handling fragile objects such as thin semiconductor chips, it is necessary to minimize the force required to pick up the object.

[0006] One embodiment of the present invention aims to enable the removal of an object held on an adhesive sheet having an adhesive layer with an uneven surface using a milder operation.

[0007] The inventors of this invention, after diligent research, discovered that the above problem can be solved by expanding the adhesive sheet and irradiating it with energy rays prior to peeling the object from the adhesive sheet. After further research, they completed the present invention.

[0008] In other words, embodiments of the present invention relate to the following [1] to

[10] . [1] A method for peeling an object from an adhesive sheet comprising a base material and an energy ray reactive adhesive layer having irregularities on its surface, the method comprising: an expansion step of expanding the adhesive sheet holding the object in the adhesive layer in the planar direction; an irradiation step of irradiating the adhesive layer of the expanded adhesive sheet with energy rays; and a peeling step of peeling the object from the adhesive layer of the adhesive sheet irradiated with energy rays. [2] The peeling method according to [1], wherein the expansion in the expansion step reduces the holding force of the object by the adhesive sheet. [3] The peeling method according to any one of [1] to [2], wherein before the expansion step, the irregularities of the adhesive layer holding the object are flattened, and in the expansion step, the adhesive sheet is expanded so that the irregularities of the adhesive layer are restored. [4] The peeling method according to any one of [1] to [3], wherein, before the expansion step, the object and the adhesive layer are in surface contact, and during the expansion step, the adhesive sheet is expanded such that the convex portion of the adhesive layer contacts the object while the concave portion of the adhesive layer separates from the object. [5] The peeling method according to any one of [1] to [4], wherein, in the peeling step, the object is peeled off the adhesive layer of the adhesive sheet using an adsorption member. [6] The peeling method according to any one of [1] to [5], wherein, in the peeling step, the object is peeled off the adhesive layer of the adhesive sheet without applying physical stimulation from the opposite side of the adhesive layer of the adhesive sheet. [7] The peeling method according to any one of [1] to [6], wherein, in the peeling step, the object is peeled off the adhesive layer of the adhesive sheet while applying physical stimulation from the opposite side of the adhesive layer of the adhesive sheet. [8] The peeling method according to any one of [1] to [7], wherein, in the expansion step, the adhesive sheet is expanded by 25% or more in the surface direction. [9] The peeling method according to any one of [1] to [8], wherein the surface of the adhesive layer has a plurality of protrusions, and the pitch of the plurality of protrusions is 1 to 100 μm.A method for manufacturing an article, comprising the steps of: peeling the object from the adhesive sheet according to the peeling method described in any one of [1] to [9]; and manufacturing an article by performing post-processing on the object.

[0009] One embodiment of the present invention makes it possible to peel off an object held on an adhesive sheet having an adhesive layer with an uneven surface using a milder operation.

[0010] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

[0011] The attached drawings are included in the specification and constitute part thereof, illustrating embodiments of the present invention and are used together with the description to explain the principles of the present invention.

[0012] Cross-sectional view of an adhesive sheet according to one embodiment. Cross-sectional view of an adhesive sheet according to one embodiment. Top view of an adhesive sheet according to one embodiment. Top view of an adhesive sheet according to one embodiment. Diagram illustrating a method of using the adhesive sheet according to one embodiment. Diagram illustrating a method of using the adhesive sheet according to one embodiment. Flowchart of a method of using the adhesive sheet according to one embodiment.

[0013] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined in any way. Furthermore, identical or similar configurations will be given the same reference numeral, and redundant descriptions will be omitted.

[0014] (Definitions) In this specification, mass-average molecular weight (Mw) and number-average molecular weight (Mn) are values ​​on a standard polystyrene basis measured by size exclusion chromatography, specifically values ​​measured according to JIS K7252-1:2016. Also in this specification, "(meth)acrylic acid" is a term that refers to both "acrylic acid" and "methacrylic acid," and the same applies to other similar terms.

[0015] In this specification, when a numerical range (e.g., a range of content, etc.) is described with one or more lower limits and one or more upper limits, it can be understood that any combination of lower and upper limits within that range is described. For example, the statement "preferably 1 to 9, more preferably 2 to 8, and even more preferably 3 to 7" clearly means that the numerical range may be any of the following: 1 to 9, 1 to 8, 1 to 7, 2 to 9, 2 to 8, 2 to 7, 3 to 9, 3 to 8, and 3 to 7. As another example, the statement "preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less" has the same meaning. Also, in this specification, parts by mass and mass percent indicate a proportion based on the mass of solids unless otherwise specified.

[0016] (Removal Method) One embodiment of the present invention relates to a method for removing an object from an adhesive sheet. The adhesive sheet comprises a base material and an energy-ray reactive adhesive layer having irregularities on its surface. In this specification, the statement that the adhesive layer is energy-ray reactive means that the storage modulus of the adhesive layer is improved by irradiation with energy rays. Examples of the configuration of the adhesive sheet will be described later with reference to Figures 1A, 1B, 2A, and 2B. Hereinafter, a method for removing an object from an adhesive sheet 100 comprising a base material 120 and an adhesive layer 110 will be described with reference to Figures 3A, 3B, and 4.

[0017] The adhesive sheet 100 has an object pre-held in the adhesive layer 110. The adhesive sheet 100 can be used to handle the object. For example, the adhesive sheet 100 according to one embodiment can be used to temporarily hold an object. For example, the adhesive sheet 100 can be used to receive an object held on another holding substrate, temporarily hold the object, and transfer the object to a desired position on a transfer destination. As a specific example, the adhesive sheet according to one embodiment can be used to transfer a semiconductor chip obtained by dicing to a desired position.

[0018] For example, an object can be bonded in advance to the adhesive layer 110 of the adhesive sheet 100. The type of the object is not particularly limited. The object may be, for example, an element. Examples of elements include semiconductor chips such as LED chips, semiconductor chips with a protective film, and semiconductor chips with a die attach film (DAF). The element may also be a micro light-emitting diode, a mini light-emitting diode, a power device, a MEMS (Micro Electro Mechanical Systems), a controller chip, or a component of any of these. The element may also be a singulated piece of a wafer, panel, substrate, or the like. The element may, for example, have a circuit surface on which an integrated circuit including circuit elements such as transistors, resistors, and capacitors is formed. Furthermore, the element is not necessarily limited to a singulated piece, and may be various unsingulated wafers, various substrates, or the like.

[0019] In addition, the size of the object is not particularly limited. For example, the size of the object is preferably 100 μm ２ to 5000 mm ２ , more preferably 1000 μm ２ to 2000 mm ２ , still more preferably 10000 μm ２ to 1000 mm ２ , still more preferably 1000000 μm ２ (1 mm ２ ) to 500 mm ２ , particularly preferably 25000000 μm ２ (25 mm ２ ) to 200 mm ２ . The thickness of the object is also not particularly limited. For example, the thickness of the object is preferably 1 μm to 100 cm, more preferably 3 μm to 1 mm, and still more preferably 5 μm to 100 μm.

[0020] 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, 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, and more preferably 12 inches (approximately 300 mm in diameter) or larger. The shape of the wafer is not limited to circular, and may be square or rectangular, for example.

[0021] Examples of panels include fan-out type semiconductor packages (e.g., FOWLP or FOPLP). That is, the workpiece may be a semiconductor package before or after individualization in fan-out type semiconductor package manufacturing technology. The size of the panel is not particularly limited, but may be, for example, a rectangular substrate of about 300 to 700 mm.

[0022] Examples of substrates include glass substrates, sapphire substrates, or compound semiconductor substrates.

[0023] In one embodiment, an object is transferred from a holding substrate to an adhesive sheet 100, and the adhesive sheet 100 holds the transferred object. For example, a semiconductor wafer can be attached to a holding substrate, and then the semiconductor wafer can be diced. The element on the holding substrate obtained by dicing can then be brought into close contact with the adhesive layer 110 of the adhesive sheet 100. Subsequently, the adhesion between the holding substrate and the element can be reduced by applying an external stimulus such as laser light. In another embodiment, the element attached to the holding substrate may be separated from the holding substrate by an external stimulus. Specifically, the element moves away from the holding substrate relative to the holding substrate. Also, the element moves closer to the adhesive sheet relative to the adhesive sheet. Then, the element is separated from the holding substrate and captured by the adhesive sheet when it comes into contact with the adhesive layer 110 of the adhesive sheet. Through such a process, the element can be transferred from the holding substrate to the adhesive sheet 100.

[0024] In one embodiment, the adhesive layer 110 holds the object while maintaining its uneven surface. In this case, the object is in contact with the convex portions of the adhesive layer 110, but not with the concave portions.

[0025] On the other hand, in one embodiment, the unevenness of the adhesive layer 110 is flattened by the object being held. In this case, the object is in surface contact with the adhesive layer 110. This surface contact between the object and the adhesive layer 110 improves the holding force of the object by the adhesive layer 110. Furthermore, surface contact between the object and the adhesive layer 110 allows the adhesive layer 110 to protect the surface (back surface) of the object that is facing the adhesive layer 110.

[0026] Furthermore, processing may be performed on the object attached to the adhesive layer 110 of the adhesive sheet 100. The processing method is not particularly limited. For example, processes such as wiring formation, back metal formation, cleaning, plating, dicing, back grinding, and sealing can be performed. For example, if a semiconductor wafer is attached to the adhesive layer 110 of the adhesive sheet 100, the semiconductor wafer on the adhesive layer 110 can be diced.

[0027] (S410: Expansion of the adhesive sheet) In S410, the adhesive sheet 100 that holds the object to the adhesive layer 110 is expanded in the planar direction. By expanding the adhesive sheet 100 in the planar direction, the holding force of the object by the adhesive sheet 100 is reduced. Also, by expanding the adhesive sheet 100 in the planar direction, the spacing between objects attached to the adhesive sheet 100 widens. For example, when a semiconductor wafer is diced on the adhesive sheet 100, the spacing between elements widens as the adhesive sheet 100 expands in the planar direction. Therefore, it becomes easier to selectively pick up objects in S430.

[0028] The method of expanding the adhesive sheet 100 is not particularly limited. For example, the expansion of the adhesive sheet 100 may be carried out in one direction, two directions, or multiple directions. The expansion rate of the adhesive sheet 100 is also not particularly limited. For example, the expansion rate of the adhesive sheet 100 in one direction is preferably 5 to 300%, more preferably 10 to 200%, even more preferably 20 to 150%, and particularly preferably 50 to 100%. In one embodiment, the adhesive sheet 100 is expanded by 25% or more in the planar direction. By increasing the expansion rate, the holding force of the object can be sufficiently reduced. By decreasing the expansion rate, the breakage of the adhesive sheet can be suppressed. From a similar viewpoint, the expansion rates of the adhesive sheet in two mutually orthogonal directions are preferably 5 to 300%, more preferably 10 to 200%, even more preferably 20 to 150%, and particularly preferably 50 to 100%.

[0029] The method for expanding the adhesive sheet 100 will be further described with reference to Figures 3A and 3B. Figure 3A shows an adhesive sheet to which objects 140a to 140d are attached. Objects 140a to 140d are semiconductor elements obtained by framing a semiconductor wafer. As shown in Figure 3A, the outer periphery of the adhesive sheet 100 can be fixed to the frame 320. For example, the adhesive layer 110 can be attached to the frame 320. The shape of the frame 320 is not particularly limited. For example, the frame 320 may be a circular or rectangular frame-shaped member having an opening. In one embodiment, a circular ring frame is used as the frame. By using a ring frame, the adhesive sheet 100 can be expanded in all directions. On the other hand, instead of a frame, two or more separate fixing members may be used. The adhesive layer 110 can be attached to each fixing member, and the adhesive sheet 100 can be expanded by pulling the fixing members away from each other.

[0030] Figure 3B shows the adhesive sheet 100 expanded in the planar direction at S410. As shown in Figure 3B, the adhesive sheet 100 can be expanded by bringing the adhesive sheet fixed to the frame 320 into contact with the base 310, and then displacing (pulling down) the frame 320 toward the base 310. The configuration of the base 310 is not particularly limited and may, for example, be cylindrical or rectangular. The base 310 may also be mesh-like or ring-shaped. The speed of displacement of the frame 320 relative to the base 310 is preferably 0.1 to 10 mm / second, more preferably 0.5 to 5 mm / second. Increased displacement improves productivity. Slower displacement can suppress damage to the adhesive sheet. The amount of displacement of the frame 320 is preferably 1 to 150 mm, more preferably 10 to 100 mm. Increased displacement can sufficiently reduce the holding force of the object. Decreased displacement can suppress damage to the adhesive sheet.

[0031] As described above, in one embodiment, the adhesive layer 110 holds the object while maintaining its uneven surface. Due to the expansion of the adhesive sheet 100 in S410, shear stress acts between the objects 140a to 140d and the protrusions 111 of the adhesive layer 110 that hold the objects 140a to 140d. Furthermore, due to the expansion of the adhesive sheet 100, the pitch P of the protrusions 111 increases, and the number of protrusions 111 that hold each of the objects 140a to 140d decreases. As a result, the holding force of the objects 140a to 140d by the protrusions 111 of the adhesive layer 110 decreases.

[0032] In one embodiment, as shown in Figure 3A, before S410, the irregularities of the adhesive layer 110 to which the objects 140a to 140d are attached are flattened. Then, in S410, as shown in Figure 3B, the adhesive sheet 100 is expanded so that the protrusions 111 of the adhesive layer 110 come into contact with the objects 140a to 140d, while the recesses of the adhesive layer 110 move away from the objects 140a to 140d. That is, the adhesive sheet 100 is expanded so that the irregularities of the adhesive layer 110 are restored. By expanding the adhesive sheet 100 in the planar direction, shear stress acts between the adhesive layer 110 and the objects, resulting in the restoration of the irregularities of the adhesive layer 110. At this time, the objects 140a to 140d, which were in surface contact with the adhesive layer 110, move away from the recesses of the adhesive layer 110 and are held by the protrusions 111 of the adhesive layer 110. Therefore, the holding power of the adhesive layer 110 over objects 140a to 140d is greatly reduced.

[0033] (S420: Energy ray irradiation) In S420, the adhesive layer 110 of the adhesive sheet 100, which was expanded in the planar direction in S410, is irradiated with energy rays. Irradiation with energy rays improves the storage modulus of the energy ray-reactive adhesive layer 110, and the object-holding force of the adhesive layer 110 decreases. In this way, by combining the expansion of the adhesive sheet 100 and the irradiation of the adhesive sheet 100 with energy rays, it becomes easier to peel objects from the adhesive sheet 100.

[0034] The type of energy ray is not particularly limited and examples include ultraviolet light, electron beams, or ionizing radiation. Preferably, the energy ray is ultraviolet light, meaning the adhesive layer 110 is preferably ultraviolet reactive. The amount of energy ray irradiated can be set according to the type of adhesive layer 110 and the desired holding force. For example, when irradiating with ultraviolet light, the amount of ultraviolet light should be 20 to 1000 mJ / cm² from the viewpoint of sufficiently reducing the holding force and shortening the processing time. ２ Preferably, the concentration is 100 to 500 mJ / cm². ２ It is preferable that it be so.

[0035] In the present embodiment, after expanding the adhesive sheet 100 in S410, the adhesive layer 110 is irradiated with energy rays in S420. When expanding the adhesive sheet 100 in a state having higher object holding force before irradiation with energy rays, the objects 140a to 140d are likely to move following the expansion of the adhesive sheet 100. Therefore, compared with the case where the adhesive sheet 100 is expanded after irradiation with energy rays, it is possible to widen the intervals between the objects 140a to 140d so that the intervals are more uniform. For this reason, it becomes easier to selectively pick up objects in S430.

[0036] As described above, in one embodiment, before the expansion of the adhesive sheet 100, the adhesive layer 110 holds an object while maintaining unevenness. The expansion of the adhesive sheet 100 in S410 causes shear stress to act between the objects 140a to 140d and the convex portions 111 of the adhesive layer 110 holding the objects 140a to 140d, and the convex portions 111 are at least partially peeled from the objects 140a to 140d. By irradiating with energy rays in this state, the holding force of the objects 140a to 140d by the adhesive layer 110 is greatly reduced. On the other hand, when expanding the adhesive sheet 100 after irradiation with energy rays, the storage elastic modulus of the adhesive layer 110 is improved while the convex portions 111 are in close contact with the objects 140a to 140d, so that the object holding force by the adhesive layer 110 is maintained relatively high. In this way, compared with the case where the adhesive sheet 100 is expanded after irradiation with energy rays, irradiating with energy rays after expanding the adhesive sheet 100 can reduce the holding force of the adhesive layer 110 to a greater extent.

[0037] Furthermore, as described above, in one embodiment, before the pressure-sensitive adhesive sheet 100 is expanded, the irregularities of the pressure-sensitive adhesive layer 110 to which the objects 140a to 140d are attached are crushed, and the expansion of the pressure-sensitive adhesive sheet 100 restores the irregularities of the pressure-sensitive adhesive layer 110. In this case, by irradiating an energy ray in S420 after expanding the pressure-sensitive adhesive sheet 100 in S410, the storage modulus of the pressure-sensitive adhesive layer 110 is improved while the contact area between the pressure-sensitive adhesive layer 110 and the object is reduced. For this reason, the object holding force of the pressure-sensitive adhesive layer 110 after the irregularities are restored is further reduced. On the other hand, when expanding the pressure-sensitive adhesive sheet 100 after irradiating an energy ray, the storage modulus of the pressure-sensitive adhesive layer 110 is improved by the energy ray irradiation, which makes it difficult for the irregularities to be restored even by the expansion of the pressure-sensitive adhesive sheet 100. For this reason, surface contact between the pressure-sensitive adhesive layer 110 and the object is maintained, and the object holding force by the pressure-sensitive adhesive layer 110 is kept relatively high. As described above, compared with expanding the pressure-sensitive adhesive sheet 100 after irradiating an energy ray, irradiating an energy ray after expanding the pressure-sensitive adhesive sheet 100 can reduce the holding force of the pressure-sensitive adhesive layer 110 to a greater extent.

[0038] (S430: Peeling of Object) In S430, the object is peeled from the pressure-sensitive adhesive layer 110 of the pressure-sensitive adhesive sheet 100 irradiated with an energy ray in S420. The method for peeling the object is not particularly limited. For example, the method described above as a method for transferring an object attached to a holding substrate to the pressure-sensitive adhesive sheet 100 can be used. As an example, the object can be peeled from the pressure-sensitive adhesive layer 110 using a suction member such as a vacuum collet. Then, the sucked object can be moved to a desired position at the transfer destination.

[0039] In one embodiment, by reducing the holding force of the pressure-sensitive adhesive layer 110 in S430, the object can be peeled from the pressure-sensitive adhesive layer 110 without applying physical stimulation such as pressing using a pin or the like from the opposite surface of the pressure-sensitive adhesive layer 110. However, the object may be peeled from the pressure-sensitive adhesive layer 110 while applying physical stimulation from the opposite surface of the pressure-sensitive adhesive layer 110.

[0040] Furthermore, according to the inventors' studies, when attempting to peel an object from the adhesive layer 110, increasing the suction force in accordance with the holding force of the adhesive layer 110 makes the object, such as an element, more susceptible to damage. In particular, when peeling thin objects such as elements, increasing the suction force makes the object even more susceptible to damage. On the other hand, reducing the holding force of the object in the adhesive layer 110 may cause the object to shift position while being held. In this embodiment, the holding force of the object changes due to the expansion of the adhesive sheet 100 and the irradiation of the adhesive sheet 100 with energy rays. Therefore, it is possible to achieve both a high holding force of the adhesive layer 110 while the object is being held by the adhesive sheet 100 and a low holding force of the adhesive layer 110 when peeling the object from the adhesive sheet 100. From this viewpoint, the adhesive sheet of this embodiment is suitable for handling thin objects. For example, the thickness of the object held by the adhesive sheet is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 10 μm or less.

[0041] By following the procedure described above, an object can be transferred to any destination using the adhesive sheet 100. Another embodiment of the present invention relates to a method for manufacturing an article. Such a manufacturing method may include a step of manufacturing an article by performing post-processing on the object peeled off from the adhesive sheet 100 in S430. The type of post-processing is not particularly limited. For example, processes such as wiring formation, back metal formation, cleaning, plating, individualization, thinning, and sealing can be performed.

[0042] (Adhesive Sheet) The following describes an example of the configuration of the adhesive sheet 100. Figure 1A is a schematic cross-sectional view showing the adhesive sheet 100 according to one embodiment. Figure 2A is a schematic top view showing the adhesive sheet 100. The adhesive sheet 100 has an adhesive layer 110 and a base material 120. The adhesive layer 110 has irregularities on its surface.

[0043] (Base material) The base material 120 functions as a support for the adhesive layer 110. The base material 120 is located on the side opposite to the side of the adhesive layer 110 that has irregularities.

[0044] In this embodiment, the adhesive sheet 100 is expandable in the planar direction. From this viewpoint, a flexible substrate can be used as the base material 120. Furthermore, by using a flexible substrate as the base material 120, the cushioning when holding an object can be improved, the lamination of adhesive sheets can be facilitated, or the adhesive sheets can be made into a roll form. As the base material 120, for example, a resin film can be used. The resin film is a film in which a resin-based material is used as the main material, and may consist of a resin material or may contain additives in addition to the resin material. The resin film may have laser light transmittance.

[0045] Specific examples of resin films include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film; polyolefin films such as polypropylene film, polybutene film, polybutadiene film, poly(4-methyl-1-pentene) film, ethylene-norbornene copolymer film, and norbornene resin film; ethylene copolymer films such as ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, and ethylene-(meth)acrylic acid ester copolymer film; polyvinyl chloride films such as polyvinyl chloride film and vinyl chloride copolymer film; polyester films such as polyethylene terephthalate film and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; and fluororesin film. In addition, films containing a mixture of two or more materials, crosslinked films in which the resin forming these films is crosslinked, and modified films such as ionomer films may also be used. Furthermore, the base material 120 may be a laminated film in which two or more resin films are laminated.

[0046] From the viewpoint of facilitating the expansion of the adhesive sheet, the base material 120 is preferably a polyolefin film or a vinyl chloride copolymer film. Examples of polyolefin films include polyethylene films, polypropylene films, and copolymers containing unsubstituted olefins such as ethylene or propylene as constituent units, such as ethylene copolymers containing ethylene-methacrylic acid copolymer (EMAA). Examples of vinyl chloride copolymer films include vinyl chloride-vinylidene 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 may be block copolymers, random copolymers, alternating copolymers, or graft copolymers. These films may also contain other resin components or additives.

[0047] The thickness of the base material 120 is not particularly limited, but from the viewpoint of achieving both support and roll winding properties, it is preferably 10 to 500 μm, more preferably 25 to 200 μm, even more preferably 40 to 150 μm, even more preferably 45 to 120 μm, and particularly preferably 55 to 90 μm.

[0048] To facilitate the uniform expansion of the adhesive sheet, the tensile modulus of the base material 120 is preferably 50 to 2500 MPa, more preferably 80 to 2000 MPa, even more preferably 100 to 1000 MPa, and particularly preferably 120 to 500 MPa. In this specification, the tensile modulus is measured according to JIS K7161-1:2014.

[0049] Similarly, to facilitate the expansion of the adhesive sheet, the elongation at break of the base material 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.

[0050] (Adhesive layer) The adhesive layer 110 is an adhesive layer. The adhesive layer 110 may contain a resin. Preferably, the resin contained in the adhesive layer 110 is an adhesive resin that is adhesive on its own. On the other hand, the resin contained in the adhesive layer 110 does not have to be an adhesive resin. If the resin contained in the adhesive layer 110 is not an adhesive resin, a tackifier can be added to the adhesive layer 110.

[0051] The following describes examples of the composition of the adhesive layer 110. However, the composition of the adhesive layer 110 is not limited to those shown below.

[0052] (Resin) The adhesive layer 110 may contain a resin. The adhesive layer 110 may contain one type of resin or two or more types of resins. Examples of resins contained in the adhesive layer 110 include rubber 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 110 may also contain a copolymer having two or more constituent units. The form of such a copolymer is not particularly limited and may be a block copolymer, a random copolymer, an alternating copolymer, or a graft copolymer.

[0053] The mass-average molecular weight (Mw) of the resin is 10,000 to 2,000,000, more preferably 70,000 to 1,500,000, and even more preferably 140,000 to 1,200,000, from the viewpoint of improving retention and keeping the storage modulus below a predetermined value. The number-average molecular weight (Mn) of the resin is 10,000 to 2,000,000, more preferably 50,000 to 1,500,000, and even more preferably 100,000 to 1,200,000, from the viewpoint of improving retention and keeping the storage modulus below a predetermined value.

[0054] The glass transition temperature (Tg) of the resin is preferably -75 to 5°C, and more preferably -70 to -20°C, from the viewpoint of improving retention strength. If the resin has two or more constituent units, the glass transition temperature (Tg) of the resin can be calculated using Fox's formula. The Tg of the monomers that derive the constituent units used in this case can be the values ​​listed in the Polymer Data Handbook or the Adhesion Handbook.

[0055] From the viewpoint of improving holding power, the resin content in the adhesive layer 110 is preferably 70% by mass or more and less than 100% by mass, more preferably 80 to 99% by mass, and even more preferably 90 to 98% by mass.

[0056] In one embodiment, the resin contained in the adhesive layer 110 may include a thermoplastic resin. When a thermoplastic resin is used, it becomes easy to form irregularities on the adhesive layer 110 by heating and softening the resin, and it also becomes easy to maintain the formed irregular shape by cooling. Examples of thermoplastic resins include rubber-based resins, acrylic-based resins, urethane-based resins, and olefin-based resins.

[0057] In this embodiment, the adhesive layer 110 is energy-ray reactive. For example, the adhesive layer 110 may have an energy-ray reactive component in addition to the resin. Alternatively, the adhesive layer 110 may contain an energy-ray reactive resin.

[0058] Energy-ray reactive components can be compounds into which polymerizable functional groups have been introduced. A polymerizable functional group is a functional group that is crosslinked by irradiation with energy rays. Examples of such polymerizable functional groups include multiple bond-containing groups, oxetanyl groups, and epoxy groups. Examples of multiple bond-containing groups include alkenyl groups such as vinyl and allyl groups, and double bond-containing groups such as (meth)acryloyl groups. Crosslinking of such polymerizable functional groups proceeds in the presence of a suitable polymerization initiator or crosslinking agent.

[0059] The energy-ray-reactive component may be a difunctional or polyfunctional monomer into which polymerizable functional groups as described above have been introduced. Examples of such monomers include polyvalent (meth)acrylates such as difunctional (meth)acrylates. Specific examples of polyvalent (meth)acrylates include cycloalkyl di(meth)acrylates such as tricyclodecanedimethanol diacrylate.

[0060] Energy-ray reactive resins refer to resins whose storage modulus improves upon irradiation with energy rays. Energy-ray reactive resins may also be energy-ray curable resins. In this specification, resins whose storage modulus has already improved due to energy ray irradiation and whose storage modulus does not improve further upon irradiation with energy rays (for example, UV-curable resins after curing is complete) are not included in the definition of energy-ray reactive resins.

[0061] An energy-ray reactive resin is, for example, a polymer having energy-ray curable groups. This polymer may be a copolymer. Examples of energy-ray curable groups include the multiple bond-containing groups, oxetanyl groups, and epoxy groups mentioned above. In one embodiment, the energy-ray reactive resin has polymerizable double bonds. Polymerizable double bonds refer to double bonds that serve as substrates for chain polymerization. For example, crosslinking can be formed between polymerizable double bonds by energy ray irradiation. Examples of polymerizable double bonds include alkenyl groups such as vinyl groups and allyl groups, and aliphatic carbon-carbon double bond-containing groups such as (meth)acryloyl groups. By irradiating such an energy-ray reactive resin with energy rays, the energy-ray curable groups of the polymer can be crosslinked with each other. In one embodiment, the energy-ray curable groups are ultraviolet-curable groups.

[0062] In one embodiment, the main component of the adhesive layer 110 is an energy-ray reactive resin. From the viewpoint of reducing the object holding force after energy ray irradiation, the content of the energy-ray reactive resin relative to the total amount of components constituting the adhesive layer 110 is preferably 50% by mass or more and less than 100% by mass, more preferably 70 to 90% by mass, and even more preferably 90 to 98% by mass.

[0063] (Energy-reactive resin having side chains containing energy-curable groups) Energy-reactive resins may have side chains containing energy-curable groups. Such energy-reactive resins may be polymers containing repeating units having energy-curable groups.

[0064] For example, the energy-ray reactive resin may be an acrylic polymer. The acrylic polymer is a polymer of monomers containing (meth)acrylic acid ester. The acrylic polymer may be a homopolymer or a copolymer. Alternatively, the acrylic polymer may be a copolymer of acrylic acid ester and methacrylic acid ester.

[0065] The acrylic polymer, which is an energy-ray reactive resin, may have repeating units derived from an (meth)acrylic acid ester having an energy-ray curable group. An example of an (meth)acrylic acid ester having an energy-ray curable group is an (meth)acrylic acid ester monomer having a polymerizable double bond via a hydroxyl group in the side chain. In one embodiment, the (meth)acrylic acid ester having a polymerizable double bond may be an acryloyl group-containing (meth)acrylic acid ester.

[0066] Specific examples of (meth)acrylic acid esters having polymerizable double bonds include those formed by urethane bonding of a hydroxyl group-containing (meth)acrylic acid ester and an isocyanate alkyl (meth)acrylate. The alkyl group in the isocyanate alkyl (meth)acrylate may be, for example, an alkyl group having 1 to 6 carbon atoms. A specific example of an isocyanate alkyl (meth)acrylate is 2-isocyanate ethyl methacrylate. In other words, an acrylic polymer that is an energy-ray reactive resin may have a hydroxyl group that has been modified to introduce a polymerizable double bond.

[0067] Hydroxy group-containing (meth)acrylic acid esters can be, for example, esters of (meth)acrylic acid with a dihydric or higher alcohol. Here, the dihydric or higher alcohol can be, for example, an alkanediol having 1 to 14 or 1 to 6 carbon atoms. Specific examples of hydroxy group-containing (meth)acrylic acid esters include hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0068] As described above, the acrylic polymer may be a copolymer. Such acrylic polymers may contain repeating units derived from various (meth)acrylic acid esters other than hydroxyl group-containing (meth)acrylic acid esters.

[0069] Examples of such (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, pentadecyl (meth)acrylate, palmityl (meth)acrylate, heptadecyl (meth)acrylate, and stearyl (meth)acrylate Examples include alkyl (meth)acrylate esters in which the alkyl group constituting the alkyl ester has a chain structure with 1 to 18 or 1 to 6 carbon atoms; cycloalkyl (meth)acrylate esters in which the cycloalkyl group constituting the cycloalkyl ester, such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate, has 1 to 18 carbon atoms; aralkyl (meth)acrylate esters in which the aralkyl group constituting the aralkyl ester, such as benzyl (meth)acrylate, has 1 to 18 carbon atoms; cycloalkenyl (meth)acrylate esters such as dicyclopentenyl (meth)acrylate; cycloalkenyloxyalkyl (meth)acrylate esters such as dicyclopentenyloxyethyl (meth)acrylate; imide (meth)acrylate; glycidyl group-containing (meth)acrylate esters such as glycidyl (meth)acrylate; and substituted amino group-containing (meth)acrylate esters such as N-methylaminoethyl (meth)acrylate. Here, "substituted amino group" refers to a group having a structure in which one or two hydrogen atoms of an amino group are replaced by a group other than a hydrogen atom.

[0070] Here, from the viewpoint of increasing the object retention force before energy ray irradiation and significantly decreasing the object retention force by energy ray irradiation, the copolymerization rate of the (meth)acrylic acid ester having polymerizable double bonds in the acrylic polymer is preferably 5 to 50%, more preferably 7 to 40%, even more preferably 10 to 35%, and particularly preferably 15 to 30%. Here, the copolymerization rate represents the molar ratio of the (meth)acrylic acid ester repeating units having polymerizable double bonds to the total repeating units contained in the acrylic polymer.

[0071] Acrylic polymers may contain repeating units other than those derived from (meth)acrylic acid esters. For example, acrylic polymers may contain repeating units derived from one or more monomers selected from itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.

[0072] (Energy-reactive resin crosslinked with a crosslinking agent having energy-curable groups) The energy-reactive resin may be a resin crosslinked with a crosslinking agent having energy-curable groups. The crosslinking agent having energy-curable groups may be a compound having two or more functional groups that bond to the functional groups of the resin, and an energy-curable group.

[0073] For example, a crosslinking agent may be a polyfunctional isocyanate having polymerizable double bonds. Such a crosslinking agent can crosslink resins having hydroxyl groups. A polyfunctional isocyanate is a compound having two or more isocyanate groups or substituents equivalent to isocyanate groups. A substituent equivalent to an isocyanate group refers to a substituent capable of forming a urethane bond with a hydroxyl group. For example, polyfunctional isocyanates include trimethylolpropane adduct-type modified compounds, biuret-type modified compounds, and isocyanurate-type modified compounds of compounds having two or more isocyanate groups.

[0074] A polyfunctional isocyanate can be a compound having one or more polymerizable double bonds and two or more isocyanate groups. In one embodiment, the polyfunctional isocyanate has 2 to 3 isocyanate groups per molecule. Also in one embodiment, the polyfunctional isocyanate has 1 to 2 polymerizable double bonds per molecule. The polyfunctional isocyanate may be, for example, a urethane acrylate having one or more polymerizable double bonds and two or more isocyanate groups. Examples of such polyfunctional isocyanates include EBECRYL 4141, 4396, 4397, 4510, 4950, and 4250 (manufactured by Daicel Ornex Co., Ltd.). By using a compound with a relatively large molecular weight, such as a urethane acrylate, as the polyfunctional isocyanate, the degree of freedom of crosslinking via the polyfunctional isocyanate is increased, thereby improving the flexibility and object-holding power of the adhesive layer 110 before energy ray irradiation. Furthermore, the decrease in the object-holding force of the adhesive layer 110 when irradiated with energy rays can be made even greater.

[0075] From the viewpoint of increasing the degree of freedom of crosslinking via the polyfunctional isocyanate, improving the flexibility and object-holding capacity of the adhesive layer 110, while maintaining the shape of the adhesive layer 110, the mass-average molecular weight of the polyfunctional isocyanate is preferably 400 to 2000, more preferably 500 to 1800, and even more preferably 600 to 1500.

[0076] In one embodiment, the resin is an acrylic polymer crosslinked with a crosslinking agent having energy-ray curable groups. The acrylic polymer crosslinked with the crosslinking agent having energy-ray curable groups may be, for example, an acrylic polymer having repeating units derived from the above-mentioned hydroxyl group-containing (meth)acrylic acid ester.

[0077] Furthermore, the resin crosslinked with a crosslinking agent having energy-ray curable groups may also have side chains containing energy-ray curable groups. For example, the acrylic polymer crosslinked with the crosslinking agent may have repeating units derived from a (meth)acrylic acid ester having energy-ray curable groups, as described above. In this case, energy irradiation can promote crosslinking between the energy-ray curable groups contained in the side chains of the resin and the energy-ray curable groups of the crosslinking agent. This further promotes the reduction in object retention force due to energy irradiation.

[0078] For example, an energy-reactive resin may be obtained by modifying an acrylic polymer having hydroxyl groups by introducing polymerizable double bonds to some of the hydroxyl groups, and then crosslinking another portion of the hydroxyl groups with a crosslinking agent having energy-curable groups. Thus, the energy-reactive resin may have hydroxyl groups that have been modified by introducing polymerizable double bonds, and hydroxyl groups that have been crosslinked with a crosslinking agent having energy-curable groups.

[0079] In another embodiment, the resin is a urethane prepolymer crosslinked with a crosslinking agent having energy-ray curable groups. The adhesive layer 110 according to one embodiment contains a urethane prepolymer crosslinked with a polyfunctional isocyanate having polymerizable double bonds. That is, this adhesive layer 110 contains a urethane-based adhesive. This urethane-based adhesive also contains a urethane resin. The adhesive layer 110 having a urethane prepolymer crosslinked with a polyfunctional isocyanate easily maintains its uneven shape before the object is attached, but the uneven shape is easily crushed when the object is attached. Furthermore, the uneven shape is easily restored when the adhesive layer 110 is expanded after the object has been attached.

[0080] In this specification, urethane prepolymer refers to a prepolymer of urethane resin having urethane bonds within its molecule. The urethane prepolymer is a precursor of urethane resin, and urethane resin is obtained by crosslinking the urethane prepolymer. In this embodiment, the urethane prepolymer has hydroxyl groups. The urethane prepolymer is crosslinked via the hydroxyl groups with a polyfunctional isocyanate.

[0081] Such urethane prepolymers can be obtained by the reaction of a polyol with a polyfunctional isocyanate. That is, the urethane prepolymer can have a structure in which the polyol is linked via urethane bonds. More specifically, the urethane prepolymer can have a structure in which the polyol is linked via urethane bonds and the main chain of the polyfunctional isocyanate. In this reaction, by using an excess of polyol, a urethane prepolymer having hydroxyl groups can be obtained.

[0082] Examples of polyols include polyether polyols, polycarbonate polyols, and polyester polyols.

[0083] Examples of polyether polyols include polyether diols and polyether polyols with three or more functionalities. Other examples of polyether polyols include those obtained by coupling one or more of these polyether polyols using a coupling agent such as methylenedichloride.

[0084] Specific examples of polyether diols include poly(oxyalkylene) glycols such as poly(oxyethylene) glycol, poly(oxypropylene) glycol, poly(oxytetramethylene) glycol, and poly(oxy-3-methyltetramethylene) glycol; copolymerized poly(oxyalkylene) diols such as ethylene oxide / propylene oxide copolymer diol, tetrahydrofuran / ethylene oxide copolymer diol, and tetrahydrofuran / 3-methyltetrahydrofuran copolymer diol (copolymerization ratio is, for example, 1 / 9 to 9 / 1); and alkylene oxide adducts of bisphenol compounds such as bisphenol A, bisphenol B, bisphenol E, or bisphenol F. Specific examples of polyether polyols with three or more functions include alkylene oxide adducts of trivalent or higher polyhydric alcohols, such as alkylene oxide adducts of glycerin and alkylene oxide adducts of trimethylolpropane.

[0085] Examples of polyester polyols include polyester diols, trifunctional or more polyester polyols, and polyols obtained by coupling one or more of these using a coupling agent. Specific examples of polyester polyols include low molecular weight polyols with a molecular weight of 1000 or less, condensed polyester diols obtained by reacting the above-mentioned polyether polyols with dicarboxylic acids, and polylactone diols obtained by ring-opening polymerization of lactones having 4 to 12 carbon atoms. Examples of dicarboxylic acids include aliphatic dicarboxylic acids having 4 to 10 carbon atoms such as succinic acid, adipic acid, or sebacic acid, and aromatic dicarboxylic acids having 8 to 15 carbon atoms such as terephthalic acid or isophthalic acid. Examples of lactones include ε-caprolactone and γ-valerolactone.

[0086] Examples of polycarbonate diols include polyhexamethylene carbonate diol.

[0087] In another embodiment, the urethane prepolymer has urea bonds within its molecule. Such a urethane prepolymer can be obtained by reacting a mixture of a polyol and a polyamine with a polyfunctional isocyanate. That is, the urethane prepolymer can have a structure in which the polyol and polyamine are linked via urethane or urea bonds.

[0088] The weight-average molecular weight (Mw) of the urethane prepolymer is preferably 10,000 to 1,000,000, more preferably 30,000 to 800,000, even more preferably 50,000 to 600,000, and particularly preferably 100,000 to 400,000. Increasing the weight-average molecular weight makes it easier to improve the viscosity while maintaining the storage modulus of the adhesive layer 110, thus making it easier to flatten and restore uneven shapes. Decreasing the weight-average molecular weight can improve the object-holding capacity of the adhesive layer 110.

[0089] The hydroxyl value of the urethane prepolymer is preferably 3.0 to 35 mg KOH / g, more preferably 6.0 to 25 mg KOH / g, and even more preferably 9.0 to 15 mg KOH / g. Increasing the hydroxyl value improves the crosslinking density, making it easier to maintain the uneven shape of the adhesive layer 110. Conversely, decreasing the hydroxyl value makes it easier to maintain the viscosity of the adhesive layer 110. This hydroxyl value represents the mass (mg) of potassium hydroxide (KOH) equivalent to the hydroxyl groups contained in 1 g of solid content of the urethane prepolymer. In this specification, the hydroxyl value is the value measured by Method A (acetylation method) as defined in JIS K1557-1:2007.

[0090] (Other components of the adhesive layer) The adhesive layer 110 may contain components other than resin. For example, the adhesive layer 110 may contain one or more of a photopolymerization initiator, an antioxidant, and other additives.

[0091] The photopolymerization initiator initiates a crosslinking reaction in response to irradiation with energy rays. Because the adhesive layer 110 also contains a photopolymerization initiator, the crosslinking reaction in the adhesive layer 110 proceeds even with the application of relatively low energy.

[0092] Examples of photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0093] The adhesive layer 110 may contain one type of photopolymerization initiator, or it may contain two or more types of photopolymerization initiators. The content of the photopolymerization initiator in the adhesive layer 110 is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.1 to 2 parts by mass.

[0094] Examples of antioxidants include phenolic compounds such as hindered phenol compounds, aromatic amine compounds, sulfur compounds, and phosphorus compounds such as phosphate ester compounds.

[0095] Other additives that the adhesive layer 110 may contain are not particularly limited, but include, for example, ultraviolet absorbers such as benzotriazole compounds, oxazolic acidamide compounds, or benzophenone compounds; light stabilizers such as hindered amine, benzophenone, or benzotriazole compounds; resin stabilizers such as imidazole resin stabilizers, dithiocarbamate resin stabilizers, phosphorus resin stabilizers, or sulfur ester resin stabilizers; fillers, pigments, bulking agents, and softeners.

[0096] If the adhesive layer 110 contains these additives, the content of the additives in the adhesive layer 110 is preferably 0.0001 to 20% by mass, more preferably 0.01 to 10% by mass, and particularly preferably 0.1 to 3% by mass.

[0097] (Shape of the adhesive layer) The surface of the adhesive layer 110 according to this embodiment has an uneven surface. In one embodiment, the adhesive layer 110 has a plurality of convex portions on its surface that are separated from each other and whose boundaries are defined by recesses. Each of the plurality of convex portions may be separated by recesses that are continuous throughout the entire adhesive layer 110. For example, the adhesive layer 110 may have flat recesses and convex portions 111 that protrude from the flat recesses.

[0098] As shown in Figure 2A, the surface of the adhesive layer 110 may have protrusions 111 arranged regularly. Regular arrangement of protrusions means that the protrusions are aligned in a straight line at regular intervals. On the other hand, the protrusions 111 may be arranged so that the intervals between them vary regularly. For example, the intervals between the protrusions 111 may be shorter in the center of the adhesive sheet 100 and longer in the peripheral area of ​​the adhesive sheet 100. Furthermore, the protrusions 111 may be arranged irregularly.

[0099] Figure 2B is a top view showing another shape of the adhesive layer 110. As shown in Figure 2B, the surface of the adhesive layer 110 may be provided with stripe-shaped protrusions 111. In Figure 2B, line-shaped protrusions 111 having a certain width are arranged at regular intervals. The width or spacing of these line-shaped protrusions 111 may vary regularly, or the line-shaped protrusions 111 may be arranged irregularly.

[0100] The pitch P of the protrusions 111 is preferably 1 to 100 μm, more preferably 5 to 50 μm, even more preferably 10 to 35 μm, and even more preferably 15 to 25 μm. The holding force can be limited by increasing the pitch P. Conversely, the holding force can be increased by shortening the pitch P to increase the contact area between the adhesive layer 110 and the object. Here, the pitch P of the protrusions 111 refers to the distance between the center point of one arbitrarily selected protrusion 111 and the center point of the nearest other protrusion 111. For example, in Figure 2A, the pitch P of the protrusions 111 represents the distance between the center point of a protrusion 111 and the center point of the nearest other protrusion 111 on a straight line in which the protrusions 111 are aligned at regular intervals. If the protrusions 111 are aligned on multiple straight lines, the pitch P represents the distance between the center points of the protrusions 111 on the straight line in which the protrusions 111 are aligned at the shortest pitch. In the case of Figure 2B, the pitch P of the protrusions 111 represents the distance between adjacent protrusions 111. In this specification, the distance between protrusions 111 means the distance between the centers of the protrusions 111.

[0101] The specific shape of the protrusion 111 is not particularly limited. For example, the protrusion 111 may have a pillar shape. Specifically, the protrusion 111 may have a cylindrical shape, a prismatic shape, a cone shape, a pyramidal shape, a spherical shape, or a hemispherical shape. Also, as described above, the protrusion 111 may extend in a linear shape or in a curved shape such as a wave shape. Furthermore, these protrusions 111 may be provided with a taper or reverse taper. For example, as shown in Figure 1B, the protrusion 111 may be tapered. Also, as shown in Figure 1B, the tip of the protrusion 111 may be curved. With such a configuration, the impact when attaching an object to the adhesive layer 110 is further mitigated, making it easier for the adhesive layer 110 to hold the object without it shifting. On the other hand, the tip of the protrusion 111 may be flat. As another example, the protrusion 111 may be hemispherical or part of a sphere. Also, the protrusion 111 may be T-shaped. As yet another example, the protrusions 111 may be in the shape of a collection of grains, mushroom-shaped, lotus leaf-shaped, or needle-shaped. As yet another example, the surface of the adhesive layer 110 may be rough or fibrous, and such a surface can also be said to have irregularities.

[0102] The width or diameter of each protrusion 111 is preferably 1 to 100 μm, more preferably 2 to 50 μm, even more preferably 5 to 30 μm, and even more preferably 10 to 20 μm. Increasing the width or diameter of the protrusion 111 can maintain the holding force of the object. Conversely, decreasing the width or diameter of the protrusion 111 can improve the ease of peeling the object. Here, the width and diameter of the protrusion 111 refer to the minimum and maximum distances (represented as W in Figure 1B) between two parallel lines tangent to the protrusion 111 on the surface of the recess, respectively.

[0103] Furthermore, the area of ​​each protrusion 111 is preferably 10 to 2000 μm. ２ , more preferably 20 to 1000 μm ２ More preferably 30 to 500 μm ２Therefore, by increasing the area of ​​the protrusion 111, the holding force of the object can be maintained. Conversely, by decreasing the area of ​​the protrusion 111, the ease of removing the object can be increased. Here, the area of ​​the protrusion 111 refers to the area of ​​the part that protrudes from the surface of the recess (in the case of Figure 1B, the area of ​​a circle with diameter W).

[0104] In one embodiment, the height of each protrusion 111 is preferably 1 to 20 μm, more preferably 3 to 15 μm, and even more preferably 5 to 10 μm. By increasing the height of the protrusion 111, the ease of peeling the object can be improved. Conversely, by decreasing the height of the protrusion 111, the holding force of the object can be improved. Here, the height of the protrusion 111 is represented by H in Figure 1B. Also in one embodiment, the heights of the multiple protrusions 111 on the adhesive layer 110 are uniform. In another embodiment, the adhesive layer 110 may have a first plurality of protrusions having a first uniform height and a second plurality of protrusions having different heights. Here, the second plurality of protrusions may have a second uniform height. For example, the protrusion 111 may consist of such first and second protrusions. In a further embodiment, the adhesive layer 110 may have a plurality of protrusions 111 of random heights.

[0105] Furthermore, the total area of ​​the protrusions 111 relative to the area of ​​the adhesive layer 110 is preferably 1 to 95%, more preferably 5 to 75%, even more preferably 10 to 70%, even more preferably 18 to 65%, and even more preferably 40 to 60%. By increasing the total area of ​​the protrusions 111, the holding force of the object can be maintained. Conversely, by decreasing the total area of ​​the protrusions 111, the ease of peeling the object can be improved.

[0106] The thickness of the adhesive layer 110 is preferably 1 to 100 μm, more preferably 2 to 75 μm, even more preferably 5 to 50 μm, and particularly preferably 10 to 30 μm. Increasing the thickness of the adhesive layer 110 improves the holding power. Conversely, making the adhesive layer 110 thinner reduces the volume of the adhesive sheet 100. Note that the thickness of the adhesive layer 110 refers to the thickness including the protrusions 111.

[0107] (Release Sheet) The adhesive sheet 100 according to this embodiment may also have a release sheet 150 in contact with the adhesive layer 110, as shown in Figure 1A. For illustrative purposes, Figure 1A shows the adhesive layer 110 and the release sheet 150 separated. As shown in Figure 1A, the release sheet 150 has an uneven surface that is complementary to the uneven surface of the adhesive layer 110. However, it is not essential that the release sheet 150 has a shape complementary to the uneven surface of the adhesive layer 110. For example, the surface of the release sheet 150 may be flat.

[0108] The release sheet 150 has a release layer 160. The release layer 160 is a layer that is easily peeled off from the adhesive layer 110. The release layer 160 may have an uneven surface that is complementary to the uneven surface of the adhesive layer 110. That is, the release layer 160 has a recess 161, and the recess 161 has a shape that is complementary to the protrusion 111.

[0109] The release sheet 150 may have a base material 170 on the side that does not come into contact with the adhesive layer 110. This base material 170 can be designed in the same way as the base material 120, but it does not need to have the same composition or structure as the base material 120. The release sheet 150 may also have an undercoat layer (not shown) between the release layer 160 and the base material 170.

[0110] (Other layers) The adhesive sheet 100 may have layers other than the base material 120 and the adhesive layer 110. Such additional layers may be provided between these layers or on the outside of these layers. For example, an additional adhesive layer may be provided on the surface of the base material 120 opposite to the adhesive layer 110. The adhesive sheet 100 can be attached to another object via such an adhesive layer. The type of the additional adhesive layer is not particularly limited, and for example, an additional adhesive layer can be formed using a general adhesive.

[0111] The planar shape of the adhesive sheet 100 is not particularly limited. In the example shown in Figure 2A, the adhesive sheet 100 is circular. However, the adhesive sheet 100 may be a circular shape with a portion missing. For example, the adhesive sheet 100 may have a shape obtained by cutting off each end of a circle with a straight line. The adhesive sheet 100 may also have another shape, such as an ellipse or a rectangle. The planar shapes of the adhesive layer 110 and the base material 120 may correspond to the planar shape of the adhesive sheet 100.

[0112] (Method for manufacturing adhesive sheet) There are no particular restrictions on the method for manufacturing the adhesive sheet 100. For example, an adhesive composition can be applied to a substrate 120 and dried. The adhesive composition can be prepared by adding an organic solvent to a raw material composition containing each component of the adhesive layer 110 described above. Furthermore, irregularities can be formed on the surface of the layer of the adhesive composition thus formed. There are no particular restrictions on the process for creating the irregularities. For example, irregularities can be created on the surface of the layer using an imprint method. In the imprint method, a mold having an irregular surface complementary to the irregularities to be created can be used. In this way, an adhesive layer 110 having irregularities on its surface is formed. Specifically, the layer of the adhesive composition can be pressed with a mold, the layer can be heated and maintained for a predetermined time, then the material layer can be cooled and the mold can be removed. As a specific method for heating the material layer while pressing the layer with a mold, a method of vacuum laminating the layer of the adhesive composition provided on the substrate 120 with the mold can be mentioned. During heating for drying or for creating irregularities, the crosslinking reaction of the resin by the crosslinking agent described above may proceed.

[0113] Alternatively, a release sheet 150 having a release layer 160 with irregularities as described above may be used as a mold. As described above, the surface of the release sheet 150 may have an irregular surface complementary to the irregular surface of the adhesive layer 110. In this case, by providing a layer of adhesive composition on the irregular surface of the release sheet 150, an adhesive layer with irregularities can be provided on the surface (i.e., the interface between the adhesive layer 110 and the release sheet 150). Furthermore, the substrate 120 can be attached to the surface of the adhesive layer 110 opposite to the irregular surface. The adhesive layer 110 may be formed on the substrate 120 by this method.

[0114] Alternatively, an adhesive layer 110 having a rough surface can be provided by spray-applying the adhesive composition. Furthermore, an adhesive layer 110 having a rough or fibrous surface can also be provided by adding a filler to the adhesive composition and applying such a solution. Yet another method is to directly provide an adhesive layer 110 having an uneven surface on the substrate 120 by applying the adhesive composition according to a desired pattern using a printing method such as an inkjet method.

[0115] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited in any way to the following examples.

[0116] The following compounds were used in the examples and comparative examples.

[0117] <(A) Component: Urethane Prepolymer> As the urethane prepolymer, a urethane adhesive main component (manufactured by artience Co., Ltd., product name "Ciabein SP-205", weight-average molecular weight 110,000), which is a polyol component, was used. The material used is a urethane prepolymer solution composition, containing 50 parts by mass of urethane prepolymer per 100 parts by mass of the solution composition. The hydroxyl value of the solution composition is 5.0 mgKOH / g, and the hydroxyl value of the urethane prepolymer itself is 10 mgKOH / g.

[0118] <Component (B): Polyfunctional Isocyanate> As the polyfunctional isocyanate, an isocyanate group-containing urethane acrylate (manufactured by Daicel Ornex Co., Ltd., product name "EBECRYL4141", number of acrylate groups per molecule: 1, number of isocyanate groups per molecule: 2.0, mass ratio of isocyanate groups in solid content: 12.8%, average molecular weight: 700, viscosity: 10000 mPa·s / 23℃) was used.

[0119] A coating solution for an adhesive composition was prepared by dissolving 100 parts by mass of urethane prepolymer (A), 2.46 parts by mass of polyfunctional isocyanate (B), 0.12 parts by mass of photopolymerization initiator (2,2-dimethoxy-2-phenylacetophenone), 0.02 parts by mass of tin-based catalyst (dioctyl tin dilaurate), and 0.5 parts by mass of curing retarder (acetylacetone) in toluene.

[0120] This adhesive composition coating liquid was applied to the release surface of a release sheet (fine embossed release sheet) with a concave shape, and the resulting coating film was dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. The uneven shape of the formed adhesive layer on its surface was a grid-like arrangement of pillars, similar to that shown in Figure 2A. The pitch (P) between pillars in the adhesive sheet was 20 μm. In addition, as shown in Figure 1B, the height (H) of each pillar was 8 μm, the diameter of the tip (T) was 8 μm, and the diameter of the base (W) was 16 μm. The release sheet had a concave shape on its surface that was complementary to this uneven shape.

[0121] An adhesive sheet was prepared by laminating the unembossed surface of a substrate (ethylene methacrylic acid copolymer (EMAA) film, acid content 9% by mass, with a textured surface on one side due to embossing, thickness 80 μm, tensile modulus 160 MPa) onto the adhesive layer thus obtained.

[0122] The obtained adhesive sheet was attached to a ring frame (made of stainless steel, with an inner diameter of 194 mm), and the adhesive sheet was cut to match the outer diameter of the ring frame. Next, a wafer substrate (ground silicon wafer, 8 inches in diameter, 150 μm thick) was fixed to a separately prepared dicing tape. Then, by dicing the wafer substrate into 10 mm x 10 mm squares, multiple elements (silicon chips, with an element size of 10 mm x 10 mm x 150 μm) were obtained. The obtained multiple elements were attached to the adhesive layer of the adhesive sheet in the central part of the inside of the ring frame, so that the ground surface was attached to the uneven surface of the adhesive layer. The attachment was performed by vacuum lamination under conditions of 40°C and 0.5 MPa. Then, by peeling off the dicing tape, the multiple elements were transferred from the dicing tape to the adhesive sheet. In this way, the multiple elements were held in place by the adhesive layer of the adhesive sheet supported by the ring frame. At this time, the adhesive layer of the adhesive sheet and the elements were in surface contact. In other words, the unevenness of the adhesive layer was flattened, and the element adhered not only to the protrusions of the adhesive layer but also to the recesses.

[0123] Next, the adhesive sheet was expanded. The expansion of the adhesive sheet was performed as shown in Figures 3A and 3B. That is, with the element supported by the base 310 through the adhesive sheet, the ring frame, frame 320, was pulled down 60 mm relative to the base 310 to expand the adhesive sheet. The pulling speed was 1 mm / second. Immediately after expanding the adhesive sheet, a portion of the element surface was separated from the recess in the adhesive layer. In other words, a portion of the unevenness of the adhesive layer at the interface between the element and the adhesive layer was restored. Furthermore, after leaving it for a while, all of the unevenness of the adhesive layer at the interface between each element and the adhesive layer was restored.

[0124] Next, the adhesive sheet was irradiated with ultraviolet light. Specifically, the adhesive sheet attached to the ring frame was irradiated with an irradiation intensity of 230 mW / cm using an ultraviolet irradiation device (Heraeus). ２ , light intensity 190mJ / cm ２ Ultraviolet light was then applied.

[0125] Finally, the element was detached from the adhesive sheet. Specifically, the adhesive sheet, after UV irradiation, was placed in a pickup device (manufactured by Canon Machinery Corporation, product name "BESTEM-D510"). After expanding the adhesive sheet, the element was picked up using a vacuum suction collet. In this process, the element was picked up without poking the side of the adhesive sheet opposite to the element to be picked up (the base material) with a needle. It was confirmed that the element could be picked up without damage using this method.

[0126] The invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention.

[0127] This application claims priority based on Japanese Patent Application No. 2025-053675, No. 2025-053677, No. 2025-053678, No. 2025-158143, and No. 2025-158147, all of which are incorporated herein by reference.

[0128] 100: Adhesive sheet, 110: Adhesive layer, 111: Protrusion, 120: Base material, 150: Release sheet, 160: Release layer, 161: Recess, 170: Base material, P: Pitch

Claims

1. A method for peeling an object from an adhesive sheet comprising a base material and an energy-ray reactive adhesive layer having irregularities on its surface, the method comprising: an expansion step of expanding the adhesive sheet holding the object in the adhesive layer in the planar direction; an irradiation step of irradiating the adhesive layer of the expanded adhesive sheet with energy rays; and a peeling step of peeling the object from the adhesive layer of the adhesive sheet irradiated with energy rays.

2. The peeling method according to claim 1, wherein the expansion in the expansion step reduces the holding power of the object by the adhesive sheet.

3. The peeling method according to claim 1, wherein, prior to the expansion step, the irregularities of the adhesive layer holding the object are flattened, and in the expansion step, the adhesive sheet is expanded so that the irregularities of the adhesive layer are restored.

4. The peeling method according to claim 1, wherein, prior to the expansion step, the object and the adhesive layer are in surface contact, and in the expansion step, the adhesive sheet is expanded such that the convex portion of the adhesive layer contacts the object while the concave portion of the adhesive layer separates from the object.

5. The peeling method according to claim 1, wherein in the peeling step, the object is peeled off from the adhesive layer of the adhesive sheet using an adsorption member.

6. The peeling method according to claim 1, wherein in the peeling step, the object is peeled from the adhesive layer of the adhesive sheet without applying physical stimulation from the opposite side of the adhesive layer of the adhesive sheet.

7. The peeling method according to claim 1, wherein in the peeling step, the object is peeled from the adhesive layer of the adhesive sheet while applying physical stimulation from the opposite side of the adhesive layer of the adhesive sheet.

8. The peeling method according to claim 1, wherein in the expansion step, the adhesive sheet is expanded by 25% or more in the planar direction.

9. The peeling method according to claim 1, wherein the surface of the adhesive layer has a plurality of protrusions, and the pitch of the plurality of protrusions is 1 to 100 μm.

10. A method for manufacturing an article, comprising the steps of: peeling the object from the adhesive sheet according to the peeling method described in claim 1; and manufacturing an article by performing post-processing on the object.

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