Laminate

Abstract

Provided is a laminate comprising: an adhesive sheet for catching an element distant from a holding substrate; and a release sheet laminated on one surface of the adhesive sheet. The adhesive sheet is provided with an adhesive layer. The adhesive layer has irregularities on a surface thereof. The release sheet is provided with a release layer that contacts the adhesive layer. The release layer has irregularities on a surface thereof. The release sheet has a release force of 1000 mN / 50 mm or less at a release angle of 180° with respect to the adhesive sheet measured at a release speed of 300 mm / minute.

Description

[Technical Field]

[0001] The present invention relates to a laminate. [Background technology]

[0002] Elements used in electronic components or semiconductor devices are often obtained by forming a large number of elements at once. For example, semiconductor chips are obtained by dicing a semiconductor wafer attached to an adhesive. When mounting such semiconductor chips on a semiconductor device, the semiconductor chips are often transferred. For example, Patent Document 1 discloses a method of transferring a semiconductor chip by irradiating the semiconductor chip with a laser (laser lift-off method). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-141181 Summary of the Invention [Problem to be solved by the invention]

[0004] When an element is moved from a substrate before transfer to a substrate after transfer, the element is captured by the substrate after transfer. When transferring such an element, a deviation may occur between the position of the element on the substrate before transfer and the position of the element on the substrate after transfer. However, by providing an uneven surface on the adhesive sheet that captures the element to be transferred, the positional deviation of the element during capture can be suppressed.

[0005] On the other hand, the adhesive sheet is attached to a release sheet until immediately before use, and is then peeled off from the release sheet and used to transfer the element. However, if the adhesive sheet has an uneven surface, the adhesive sheet is strongly bonded to the release sheet, making it difficult to peel off the adhesive sheet from the release sheet.

[0006] An object of the present invention is to provide a laminate that allows an element to be transferred to an appropriate position and has improved releasability of the release sheet from the pressure-sensitive adhesive sheet. [Means for solving the problem]

[0007] After extensive research, the inventors discovered that the above problem could be solved by adjusting the release force of a release sheet relative to an adhesive sheet having unevenness. After further research, they completed the present invention.

[0008] That is, the present invention relates to the following [1] to

[12] . [1] A laminate comprising an adhesive sheet for capturing an element separated from a holding substrate, and a release sheet laminated on one side of the adhesive sheet, the pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer has an uneven surface; the release sheet includes a release layer in contact with the adhesive layer, and the release layer has an uneven surface; A laminate in which the peel strength of the release sheet at a peel angle of 180° to the pressure-sensitive adhesive sheet, measured at a peel speed of 300 mm / min, is 1000 mN / 50 mm or less. [2] The laminate according to [1], wherein the release layer contains a non-silicone release agent. [3] The laminate according to [1] or [2], wherein the release layer contains a non-silicone olefin-based release agent. [4] The laminate according to any one of [1] to [3], wherein the unevenness of the surface of the adhesive layer is complementary to the unevenness of the surface of the release layer. [5] A laminate according to any one of [1] to [4], wherein the release layer has a plurality of recesses on its surface that are spaced apart and bounded by protrusions, and the height of the recesses in the release layer is 1 μm or more. [6] The laminate according to any one of [1] to [5], wherein the adhesive layer is formed from an adhesive composition containing an energy ray-curable compound (B). [7] The laminate according to any one of [1] to [6], wherein the adhesive layer is formed from an adhesive composition containing an acrylic resin (A). [8] The laminate according to any one of [1] to [7], wherein the adhesive layer is formed from an adhesive composition containing an acrylic resin (A) and an energy ray-curable compound (B). [9] A laminate according to any one of [1] to [8], wherein the adhesive layer has on its surface a plurality of convex portions spaced apart from one another and bounded by concave portions, and the pitch of the plurality of convex portions of the adhesive layer is 1 μm or more and 100 μm or less.

[10] The adhesive layer has a surface having a plurality of protrusions spaced apart from one another and bounded by recesses, and each of the plurality of protrusions on the adhesive layer has an area of ​​10 μm 2 More than 2000μm 2 The laminate according to any one of [1] to [9] below.

[11] A laminate according to any one of [1] to

[10] , wherein the adhesive layer has a surface having a plurality of convex portions spaced apart from each other and bounded by concave portions, and the ratio of the area of ​​the adhesive layer occupied by the convex portions to the area of ​​the adhesive layer is 1% or more and 95% or less.

[12] A laminate described in any one of [1] to

[11] , wherein the adhesive layer is configured so that the ratio of the adhesive area between the adhesive layer and one of the elements to the area of ​​one of the elements is 1% or more and 95% or less. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminate that allows an element to be transferred to an appropriate position and has improved releasability of the release sheet from the pressure-sensitive adhesive sheet. [Brief explanation of the drawings]

[0010] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Figure 1] FIG. 1 is a schematic diagram of a laminate according to an embodiment. [Figure 2A]FIG. 3 is a top view showing an example of the unevenness of the adhesive sheet. [Figure 2B] FIG. 3 is a top view showing an example of the unevenness of the adhesive sheet. [Figure 2C] FIG. 3 is a top view showing an example of the unevenness of the adhesive sheet. [Figure 3A] FIG. 3 is a cross-sectional view showing an example of the unevenness of the pressure-sensitive adhesive sheet. [Figure 3B] FIG. 3 is a cross-sectional view showing an example of the unevenness of the pressure-sensitive adhesive sheet. [Figure 4A] Schematic diagram illustrating element separation and capture. [Figure 4B] Schematic diagram illustrating element separation and capture. [Figure 4C] Schematic diagram illustrating element separation and capture. [Figure 5A] FIG. 4 is a top view showing an example of the unevenness of the release sheet. [Figure 5B] FIG. 4 is a top view showing an example of the unevenness of the release sheet. [Figure 5C] FIG. 4 is a top view showing an example of the unevenness of the release sheet. [Figure 6A] FIG. 3 is a cross-sectional view showing an example of the unevenness of the release sheet. [Figure 6B] FIG. 3 is a cross-sectional view showing an example of the unevenness of the release sheet. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Furthermore, the same reference numerals are used for the same or similar components, and redundant explanations will be omitted.

[0012] (definition) In this specification, the mass average molecular weight (Mw) and number average molecular weight (Mn) are values ​​measured by size exclusion chromatography in terms of standard polystyrene, specifically, values ​​measured in accordance with JIS K7252-1: 2016. In addition, 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.

[0013] As used herein, the term "electronic components" encompasses all components used in electronics and electrical engineering, as well as all components constituting electronic devices. Electronic components may be made of semiconductors, conductors, and / or insulators, or a combination thereof. Examples of electronic components include active components (mainly made of semiconductors, such as transistors, ICs, LSIs, VLSIs, diodes, light-emitting diodes, thyristors, three-terminal regulators, and image sensors), passive components (such as resistors, capacitors, speakers, coils, transformers, relays, piezoelectric elements, quartz crystal oscillators, ceramic oscillators, and varistors), and structural components (such as wiring components, printed circuit boards, connectors, and switches). The term "semiconductor device" as used herein refers to any device that utilizes the properties of semiconductors, such as processors, memories, and sensors. Examples of semiconductor devices include micro-light-emitting diodes, mini-light-emitting diodes, power devices, MEMS (microelectromechanical systems), and controller chips.

[0014] In this specification, when one or more lower limits and one or more upper limits of a numerical range (e.g., a range of content, etc.) are described, it can be understood that any combination of the lower limit and upper limit therein is described. For example, a description of 1 or more, 2 or more, 3 or more, and 9 or less, 8 or less, or 7 or less clearly means that the numerical range may be any 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.

[0015] <<<Laminate according to this embodiment>>> The laminate according to this embodiment comprises an adhesive sheet for capturing an element separated from a holding substrate and a release sheet laminated on one side of the adhesive sheet. The adhesive sheet comprises an adhesive layer having an uneven surface, and the release sheet comprises a release layer in contact with the adhesive layer having an uneven surface. This allows the element to be transferred to an appropriate position. Furthermore, the peel strength of the release sheet at a peel angle of 180° measured at a peel speed of 300 mm / min is 1000 mN / 50 mm or less from the adhesive sheet. This improves the releasability of the release sheet from the adhesive sheet, allowing the adhesive sheet to be easily peeled from the release sheet.

[0016] <<Laminate structure>> FIG. 1 shows a schematic diagram of a laminate according to one embodiment. In one embodiment, the laminate may include an adhesive layer 110, an adhesive sheet substrate 120, a release layer 130, and a release sheet substrate 140. However, it is not essential that the adhesive sheet and the release sheet include the adhesive sheet substrate 120 and the release sheet substrate 140. For example, the adhesive sheet may be composed of only the adhesive layer 110, and the release sheet may be composed of only the release layer 130. In this case, an adhesive layer 110 and a release layer 130 with high supportability can be used.

[0017] The laminate usually has the adhesive sheet and release sheet attached until immediately before use. The aforementioned characteristics of the laminate may vary depending on the composition, properties, etc. of the adhesive sheet and release sheet, which will be described later. In one embodiment, the laminate can be obtained by bonding an adhesive sheet and a release sheet together so that the adhesive layer 110 of the adhesive sheet and the release layer 130 of the release sheet are in contact with each other. Alternatively, the laminate may be formed by forming the adhesive layer 110 on the release layer 130 of the release sheet, which has an uneven surface, and then bonding the adhesive sheet substrate 120 onto the adhesive layer 110. Details of each component will be described later.

[0018] <<Peeling force>> In the laminate according to this embodiment, the peel strength of the release sheet from the adhesive sheet at a peel angle of 180° measured at a peel speed of 300 mm / min is 1000 mN / 50 mm or less. The upper limit of the peel strength of the release sheet from the adhesive sheet is preferably 1000 mN / 50 mm or less, more preferably 800 mN / 50 mm or less, more preferably 500 mN / 50 mm or less, even more preferably 200 mN / 50 mm or less, and particularly preferably 100 mN / 50 mm or less. This improves the releasability of the release sheet from the adhesive sheet, making it easier to peel adhesive sheets with uneven surfaces from the release sheet.

[0019] On the other hand, the lower limit of the peel strength of the release sheet relative to the pressure-sensitive adhesive sheet is not particularly limited, but is preferably 1 mN / 50 mm or more, more preferably 2 mN / 5 mm or more, more preferably 10 mN / 50 mm or more, even more preferably 15 mN / 50 mm or more, and particularly preferably 20 mN / 50 mm or more. This allows the laminate to be maintained. The peel strength of the laminate can be preferably in the range of 1 mN / 50 mm or more to 1000 mN / 50 mm or less, more preferably 2 mN / 5 mm or more to 800 mN / 50 mm or less, more preferably 10 mN / 50 mm or more to 500 mN / 50 mm or less, even more preferably 15 mN / 50 mm or more to 200 mN / 50 mm or less, and particularly preferably 20 mN / 50 mm or more to 100 mN / 50 mm or less.

[0020] The method for measuring the peel strength of the release sheet from the pressure-sensitive adhesive sheet will be explained in the Examples.

[0021] <<Adhesive sheet>> <Adhesive layer> The adhesive sheet according to this embodiment has an adhesive layer 110, which is an adhesive layer that may contain a resin. The adhesive sheet may also have two or more adhesive layers 110. For example, the adhesive sheet may have a laminate of one type of adhesive layer 110, or two or more types of adhesive layers 110. The surface of the adhesive layer 110 has irregularities. The adhesive sheet captures the element separated from the holding substrate in the adhesive layer 110, and allows gas compressed between the element and the adhesive layer 110, which is generated when the element and the adhesive layer 110 approach each other, to escape into the recesses of the adhesive sheet. This relieves the pressure generated between the element and the adhesive layer. Details of the capture of the element by the adhesive sheet will be described later.

[0022] (Shape of adhesive layer) If the surface of the adhesive layer 110 has recesses, the pressure generated between the element and the adhesive layer can be alleviated, and the position of the element held on the adhesive sheet can be prevented from shifting. Therefore, the specific shape of the recesses and projections on the surface of the adhesive layer 110 is not limited. On the other hand, the recesses and projections on the surface of the adhesive layer 110 are complementary to the recesses and projections on the surface of the release layer, which will be described later.

[0023] In one embodiment, adhesive layer 110 has a plurality of spaced apart protrusions bounded by recesses on its surface. Each of the plurality of protrusions may be separated by a continuous recess throughout adhesive layer 110. Providing a continuous recess around such protrusions can enhance the pressure relief effect.

[0024] In one embodiment, the recesses located around each of the plurality of protrusions continue to the edge of the adhesive layer 110. By providing recesses that continue to the edge of the adhesive layer 110 in this way, gas compressed between the element and the protrusions of the adhesive layer 110 can be efficiently released to the outside of the element. Figures 2A to 2C are top views showing the shape of such adhesive layer 110.

[0025] As shown in FIG. 2A, protrusions 111 may be regularly arranged on the surface of the adhesive layer 110. Regularly arranging the protrusions 111 means that the protrusions 111 are lined up in a straight line at regular intervals. Alternatively, as shown in FIG. 2B, the protrusions 111 may be arranged so that the intervals between them vary regularly. In the example of FIG. 2B, the intervals between the protrusions 111 are short at the center of the adhesive sheet and long at the periphery of the adhesive sheet. This configuration improves the retention of the adhesive sheet while allowing compressed gas to efficiently escape from the periphery of the element via the wider recesses. Furthermore, the protrusions 111 may be arranged irregularly.

[0026] 2C is a top view showing another shape of adhesive layer 110. As shown in FIG. 2C, stripe-shaped protrusions 111 may be provided on the surface of adhesive layer 110. In FIG. 2C, linear protrusions 111 having a constant width are arranged at regular intervals. On the other hand, as in FIG. 2B, the width or interval of linear protrusions 111 may vary regularly, or linear protrusions 111 may be arranged irregularly.

[0027] 2B, the smallest interval among all the intervals between all the protrusions 111 in the center of the adhesive sheet may be shorter than the smallest interval among all the intervals between all the protrusions 111 in the peripheral part of the adhesive sheet. Here, the central part refers to, for example, a circular area having 1 / 4 of the area of ​​the adhesive sheet and centered on the center of gravity of the adhesive sheet, and the peripheral part refers to, for example, the entire area of ​​the adhesive sheet other than the central part.

[0028] The pitch P of the convex portions 111 is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more, from the viewpoint of enhancing the pressure relaxation effect. On the other hand, from the viewpoint of increasing the contact area between the adhesive layer 110 and the element and suppressing misalignment during capture, this pitch is preferably 100 μm or less, more preferably 75 μm or less, more preferably 50 μm or less, even more preferably 35 μm or less, and particularly preferably 25 μm or less. Here, the pitch of the convex portions 111 refers to the distance between the center point of an arbitrarily selected convex portion 111 and the center point of another convex portion 111 closest to that convex portion 111. For example, in the case of FIG. 2A, the pitch of the convex portions 111 represents the distance between the center point of the convex portion 111 on a line on which the convex portions 111 are arranged at regular intervals and the center point of another convex portion 111' closest to that convex portion 111. When the convex portions 111 are arranged on multiple straight lines, the pitch represents the distance between the center points of the convex portions on the line arranged at the shortest pitch. Also, when the convex portions have an elongated shape as shown in Figure 2C and the center points of the convex portions are difficult to identify, the pitch represents the distance from the boundary of the convex portion 111 on the same side to the boundary of the nearest other convex portion 111'.

[0029] The specific shape of the protrusions 111 is not particularly limited. For example, the protrusions 111 may have a pillar (column) shape. As a specific example, the protrusions 111 may have a cylindrical shape or a prismatic shape. As described above, the protrusions 111 may extend in a line shape, or may extend in a curved shape such as a wavy shape. Furthermore, these protrusions 111 may be tapered.

[0030] 3A shows a cross-sectional view of an adhesive layer 110 according to one embodiment, taken perpendicular to the surface of the adhesive layer 110 and passing through a protruding portion 111. The protruding portion 111 shown in FIG. 3A is tapered, i.e., the protruding portion 111 is tapered. As shown in FIG. 3A, the surface of the adhesive layer 110 may have flat recesses and protruding portions 111 protruding from the recesses. In this way, the adhesive layer 110 has a plurality of protruding portions 111 that are spaced apart from one another and may be bounded by the recesses.

[0031] 3B, the tip of the protrusion 111 may be hemispherical or have a curved surface like a part of a sphere. With this configuration, the impact when the element separated from the holding substrate comes into contact with the adhesive layer 110 is further reduced, making it easier for the adhesive layer 110 to capture the element in an appropriate position. On the other hand, the tip of the protrusion may be flat.

[0032] Furthermore, the protrusions 111 may have a shape of a collection of particles, the surface of a lotus leaf, or needle-like. 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.

[0033] The width or diameter of each protrusion 111 is the width or diameter of its base, not its tip, and from the viewpoint of increasing adhesiveness and suppressing positional displacement during capture, is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 5 μm or more, and particularly preferably 10 μm or more. On the other hand, it is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less. Here, the width and diameter of protrusion 111 refer to the minimum and maximum distances (represented by D in FIG. 3A ) between two parallel lines that contact protrusion 111 from both sides on the surface of the recess.

[0034] The area of ​​each of the protrusions 111 is preferably 10 μm from the viewpoint of increasing adhesiveness and suppressing positional deviation during capture. 2 More preferably, 20 μm or more 2 More preferably, 30 μm or more 2 On the other hand, the area of ​​each of the protrusions 111 is preferably 2000 μm or less from the viewpoint of enhancing the pressure relaxation effect. 2 Less than or equal to 1000 μm, more preferably 2 Less than 500 μm, even more preferably 2 Here, the area of ​​the convex portion 111 means the area of ​​the portion protruding from the surface of the concave portion (the area of ​​a circle with a diameter D in the case of FIG. 3A).

[0035] Furthermore, from the viewpoint of enhancing shock absorption and suppressing displacement during capture, 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 enhancing shape 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. Here, the height of protrusion 111 is represented by H in FIG. 3A.

[0036] Furthermore, the area of ​​each protrusion 111 relative to the area of ​​the adhesive layer 110 is preferably 1% or more, more preferably 5% or more, more preferably 10% or more, even more preferably 18% or more, and particularly preferably 40% or more, from the viewpoint of increasing adhesiveness and suppressing positional deviation during capture. On the other hand, the area of ​​each protrusion 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, from the viewpoint of increasing the pressure relaxation effect.

[0037] The unevenness of the adhesive layer 110 may be designed according to the shape of the element held by the adhesive sheet. For example, the ratio of the adhesion area between the adhesive layer 110 and one element to the area of ​​one element is preferably 1% or more, more preferably 2% or more, more preferably 3% or more, more preferably 4% or more, more preferably 5% or more, even more preferably 7% or more, and particularly preferably 10% or more, relative to the 100% area of ​​one element, from the viewpoint of enhancing adhesion and suppressing positional displacement during capture. On the other hand, the ratio of the adhesion area between the adhesive layer 110 and one element to the area of ​​one element is preferably 95% or less, more preferably 70% or less, even more preferably 50% or less, and particularly preferably 30% or less, from the viewpoint of enhancing the pressure relaxation effect. In the case of FIG. 3A, the adhesion area corresponds to the area of ​​a circle with a diameter T. Note that the adhesion area may change if the capture position of the element on the adhesive sheet is shifted. In this case, the adhesion area ratio may fall within the above range regardless of the capture position of the element.

[0038] (adhesive layer thickness) The thickness of the adhesive layer 110 is not particularly limited, but from the viewpoint of adhesiveness, it can be preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, preferably 70 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. The thickness of the adhesive layer 110 can be in the range of preferably 1 μm or more and 70 μm or less, more preferably 5 μm or more and 50 μm or less, and even more preferably 10 μm or more and 40 μm or less.

[0039] (Composition of Adhesive Layer (Adhesive Composition)) The adhesive composition forming the adhesive layer 110 contains a resin. Examples of resins contained in the adhesive composition include rubber-based resins such as polyisobutylene-based resins, polybutadiene-based resins, and styrene-butadiene-based resins, acrylic-based resins, urethane-based resins, polyester-based resins, olefin-based resins, silicone-based resins, and polyvinyl ether-based resins. The adhesive layer may also be heat-resistant. Examples of heat-resistant adhesive layer materials include polyimide-based resins and silicone-based resins. The adhesive composition forming the adhesive layer 110 may contain a copolymer having two or more types of structural units. The form of such a copolymer is not particularly limited and may be any of a block copolymer, a random copolymer, an alternating copolymer, and a graft copolymer. The resin contained in the adhesive composition forming the adhesive layer 110 may be composed of one type of resin or two or more types of resins.

[0040] The resin contained in the adhesive composition forming the adhesive layer 110 can be an adhesive resin that exhibits adhesiveness by itself. The resin can be a polymer having a mass average molecular weight (Mw) of 10,000 or more. From the viewpoint of improving adhesive strength, 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. From the viewpoint of suppressing the modulus of elasticity to a predetermined value or less, the mass average molecular weight (Mw) of the resin is preferably 2,000,000 or less, more preferably 1,200,000 or less, and even more preferably 900,000 or less. From the viewpoint of improving adhesive strength, 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. From the viewpoint of suppressing the modulus of elasticity to a predetermined value or less ...2,000,000 or less, more preferably 1,000,000 or less, and even more preferably 700,000 or less. As described below, when the adhesive layer 110 contains a resin derived from an energy ray curable resin, the 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 crosslinking reaction due to energy application.

[0041] From the viewpoint of improving adhesive strength, the glass transition temperature (Tg) of the resin is preferably −75° C. or higher, more preferably −70° C. or higher, and preferably −10° C. or lower, more preferably −20° C. or lower.

[0042] The amount of resin relative to the total amount of components constituting the adhesive composition forming adhesive layer 110 can be set appropriately depending on the desired adhesive strength of adhesive layer 110, but is preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, and particularly preferably 60% by mass or more, and is preferably 99.99% by mass or less, more preferably 99.95% by mass or less, and even more preferably 99.90% by mass or less.

[0043] thermoplastic resin 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 can be formed from a thermoplastic resin. When a thermoplastic resin is used, it becomes easy to form irregularities in the adhesive layer 110 by heating the resin to soften it, and it also becomes easy to maintain the irregular shape formed by cooling the resin. Examples of thermoplastic resins include rubber-based resins, acrylic-based resins, urethane-based 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-based thermoplastic elastomers using (meth)acrylic acid esters as a monomer.

[0044] Acrylic resin (A) In one embodiment, the thermoplastic resin may be an acrylic resin (A). From the viewpoint of improving adhesive strength, the mass average molecular weight (Mw) of the acrylic resin (A) 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 elastic modulus to a predetermined value or less, the mass average molecular weight (Mw) is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less.

[0045] From the viewpoint of improving adhesive strength, the glass transition temperature (Tg) of the acrylic resin (A) is preferably −75° C. or higher, more preferably −70° C. or higher, and preferably 75° C. or lower, more preferably 25° C. or lower, and even more preferably −55° C. or lower.

[0046] When the acrylic resin (A) has two or more structural units, the glass transition temperature (Tg) of the acrylic resin (A) can be calculated using the Fox equation. The Tg of the monomer from which the structural unit is derived can be calculated using the value listed in the Polymer Data Handbook or the Adhesive Handbook.

[0047] Examples of the (meth)acrylic acid ester constituting the acrylic resin (A) 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, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, (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, stearyl (meth)acrylate, etc., in which the alkyl group constituting the alkyl ester has a chain structure having 1 to 18 carbon atoms ( (Meth)acrylic acid alkyl esters; (meth)acrylic acid cycloalkyl esters such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; (meth)acrylic acid aralkyl esters such as benzyl (meth)acrylate; (meth)acrylic acid cycloalkenyl esters such as dicyclopentenyl (meth)acrylate; (meth)acrylic acid cycloalkenyloxyalkyl esters such as dicyclopentenyloxyethyl (meth)acrylate; imide (meth)acrylates; glycidyl (meth)acrylate, etc. Examples of the hydroxyl group-containing (meth)acrylic acid ester include glycidyl group-containing (meth)acrylic acid esters; hydroxyl group-containing (meth)acrylic acid esters such as 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; and substituted amino group-containing (meth)acrylic acid esters such as N-methylaminoethyl (meth)acrylate.Here, the term "substituted amino group" refers to a group having a structure in which one or two hydrogen atoms of an amino group have been substituted with a group other than a hydrogen atom.

[0048] The acrylic resin (A) may be, for example, a resin obtained by copolymerizing one or more monomers selected from (meth)acrylic acid ester, (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylolacrylamide, and the like.

[0049] The acrylic resin (A) may be composed of one kind of monomer or two or more kinds of monomers, and when two or more kinds of monomers are used, the combination and ratio thereof can be selected arbitrarily.

[0050] The acrylic resin (A) may have, in addition to hydroxyl groups, functional groups capable of bonding to other compounds, such as vinyl groups, (meth)acryloyl groups, amino groups, carboxy groups, isocyanate groups, etc. These functional groups, including the hydroxyl groups of the acrylic resin (A), may bond to other compounds via the crosslinking agent (C) described below, or may bond directly to other compounds without the crosslinking agent (C).

[0051] The amount of acrylic resin (A) in the total amount of resin in the adhesive composition can be set appropriately depending on the desired adhesive strength of the adhesive layer 110, but is preferably 0% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 50% by mass or more, and is preferably 100% by mass or less, more preferably 95% by mass or less, even more preferably 80% by mass or less, particularly preferably 60% by mass or less.

[0052] Energy ray curable resin (B) In one embodiment, the resin contained in the adhesive composition forming the adhesive layer 110 may include an energy ray-curable resin (B). "Energy ray-curable" refers to the property of being cured by irradiation with energy rays, and energy ray-curable resin (B) refers to a resin that is cured by irradiation with energy rays. "Energy rays" refers to electromagnetic waves or charged particle beams that have an energy quantum, and examples thereof include ultraviolet rays, radioactive rays, and electron beams. Ultraviolet rays can be irradiated using, for example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like as an ultraviolet light source. Electron beams generated by an electron beam accelerator or the like can be irradiated. "Energy ray-polymerizable" refers to the property of being polymerized by irradiation with energy rays.

[0053] When such an energy ray curable resin (B) is used, by providing energy (for example, by irradiating with energy rays) after forming the irregularities in the resin, it becomes easy to maintain the irregularities that have been formed.

[0054] The energy ray-curable resin (B) can be a monomer, oligomer, or polymer having a polymerizable functional group introduced therein. The polymerizable functional group is a functional group that crosslinks upon application of energy (e.g., irradiation with energy rays). Examples of the polymerizable functional group include vinyl groups, alkenyl groups such as allyl groups, (meth)acryloyl groups, oxetanyl groups, and epoxy groups.

[0055] From the viewpoint of improving adhesive strength, the mass average molecular weight (Mw) of the energy ray curable resin (B) is preferably 100 or more, more preferably 150 or more. From the viewpoint of suppressing the elastic modulus to a predetermined value or less, the mass average molecular weight (Mw) is preferably 2 million or less, more preferably 1 million or less, and even more preferably 200,000 or less. When a monomer or oligomer is used as the energy ray-curable resin (B), the number average molecular weight (Mn) of the energy ray-curable resin (B) is, from the viewpoint of polymerizability, preferably 100 or more, more preferably 150 or more. Moreover, from the viewpoint of suppressing the elastic modulus to a predetermined value or less, it is preferably 5000 or less, more preferably 1000 or less, and even more preferably 500 or less. When a polymer is used as the energy ray-curable resin (B), the mass average molecular weight (Mw) of the energy ray-curable resin (B) is preferably 10,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more, from the viewpoint of improving adhesive strength. Also, from the viewpoint of keeping the elastic modulus at or below a predetermined value, it is preferably 2,000,000 or less, more preferably 500,000 or less, and even more preferably 300,000 or less.

[0056] From the viewpoint of easily maintaining the uneven shape of the pressure-sensitive adhesive layer, the average number of polymerizable functional groups per molecule in the energy ray-curable resin (B) is preferably 1.5 or more, more preferably 2 or more. On the other hand, from the viewpoint of improving the adhesiveness and flexibility of the pressure-sensitive adhesive layer, this average value is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less.

[0057] In one embodiment, the energy ray curable resin (B) can be a monomer or oligomer having a polymerizable functional group. Examples of such energy ray curable compounds include polyvalent (meth)acrylate monomers such as glycerin di(meth)acrylate, glycerin tri(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate; urethane (meth)acrylate; polyester (meth)acrylate; polyether (meth)acrylate; and epoxy (meth)acrylate. Among these, from the viewpoint of maintaining the formed uneven shape, preferred are glycerin di(meth)acrylate, glycerin tri(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate.

[0058] In one embodiment, the energy ray-curable resin (B) can be a diene-based rubber composed of a polymer having a polymerizable functional group at the end of the main chain and / or in the side chain. Diene-based rubber refers to a rubbery polymer having a double bond in the polymer main chain. Specific examples of diene-based rubber include polymers using butadiene or isoprene as a monomer (i.e., having butenediyl or pentenediyl groups as structural units). In one embodiment, the energy ray-curable resin (B) can be a polybutadiene resin, a styrene-butadiene-styrene block copolymer, or a styrene-isoprene-styrene block copolymer.

[0059] The amount of the energy ray curable resin (B) in the total amount of resin in the adhesive composition can be set appropriately depending on the desired adhesive strength of the adhesive layer 110, but is preferably 0% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 50% by mass or more, and is preferably 100% by mass or less, more preferably 95% by mass or less, even more preferably 80% by mass or less, particularly preferably 60% by mass or less.

[0060] In one embodiment, the pressure-sensitive adhesive composition may contain an acrylic resin (A) and an energy ray-curable resin (B). The relationship between the contents of the acrylic resin (A) and the energy ray-curable resin (B) can be appropriately set depending on the desired adhesive strength of the pressure-sensitive adhesive layer 110. In one embodiment, the content of the acrylic resin (A) in the total content of the acrylic resin (A) and the energy ray-curable resin (B) is preferably 0% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 50% by mass or more, and preferably 100% by mass or less, more preferably 95% by mass or less.

[0061] 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.

[0062] Crosslinker (C) The pressure-sensitive adhesive composition may contain a crosslinking agent (C) for crosslinking by bonding functional groups of the resin with other compounds. Examples of the crosslinking agent (C) include isocyanate-based crosslinking agents (crosslinking agents having an isocyanate group) such as tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and adducts of these diisocyanates, epoxy-based crosslinking agents (crosslinking agents having a glycidyl group) such as ethylene glycol glycidyl ether, aziridine-based crosslinking agents (crosslinking agents having an aziridinyl group) such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine, metal chelate-based crosslinking agents (crosslinking agents having a metal chelate structure) such as aluminum chelate, and isocyanurate-based crosslinking agents (crosslinking agents having an isocyanuric acid skeleton).

[0063] The pressure-sensitive adhesive composition may contain one type of crosslinking agent or may contain two or more types of crosslinking agents. From the viewpoint of appropriately carrying out the crosslinking reaction, the content of the crosslinking agent (C) in the pressure-sensitive adhesive composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and is preferably 5% by mass or less, more preferably 4% by mass or less, even more preferably 2% by mass or less.

[0064] Photopolymerization initiator (D) The pressure-sensitive adhesive composition may contain a photopolymerization initiator (D) that initiates a crosslinking reaction in response to the application of energy (for example, irradiation with energy rays). When the pressure-sensitive adhesive composition contains an energy ray-curable resin (B), the pressure-sensitive adhesive layer 110 further contains a photopolymerization initiator (D), so that the crosslinking reaction proceeds even when a relatively low amount of energy is applied.

[0065] Examples of the photopolymerization initiator (D) include 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0066] The pressure-sensitive adhesive composition may contain one type of polymerization initiator or two or more types of polymerization initiators. The content of the photopolymerization initiator (D) in the pressure-sensitive adhesive composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less.

[0067] Antioxidant (E) The pressure-sensitive adhesive composition may contain an antioxidant (E). Examples of the antioxidant (E) include phenol-based antioxidants such as hindered phenol-based compounds, aromatic amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants such as phosphate ester-based compounds.

[0068] Furthermore, the adhesive composition forming the adhesive layer 110 may contain one or more of an ultraviolet absorber, a light stabilizer, a resin stabilizer, a filler, a pigment, an extender, a softener, and the like.

[0069] <Adhesive sheet substrate> The adhesive sheet substrate 120 included in the adhesive sheet according to this embodiment functions as a support for the adhesive layer 110. The type of adhesive sheet substrate 120 is not particularly limited, and can be a hard substrate or a flexible substrate, such as a plastic film, a metal foil such as aluminum or stainless steel, glassine paper, fine paper, coated paper, impregnated paper, or synthetic paper. In one embodiment, the adhesive sheet substrate 120 can be a flexible substrate from the viewpoints of improving cushioning when capturing an element, facilitating attachment to other components, improving peelability, facilitating lamination, or enabling formation into a roll form. For example, a resin film can be used as the adhesive sheet substrate 120.

[0070] The resin film is a film that uses a resin-based material as a main material, and may be made of a resin material alone or may contain an additive in addition to a resin material. The resin film may be laser beam transmissive.

[0071] Specific examples of resin films include polyethylene films such as low-density polyethylene film, linear low-density polyethylene film, and high-density polyethylene film; polyolefin films such as polypropylene film, polybutene film, polybutadiene film, polymethylpentene 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 films; polyimide films; polystyrene films; polycarbonate films; and fluororesin films. Films containing a mixture of two or more materials, crosslinked films in which the resins forming these films are crosslinked, and modified films such as ionomer films may also be used. The adhesive sheet substrate 120 may also be a laminate film in which two or more resin films are laminated.

[0072] From the viewpoints of versatility, relatively high strength that makes it easy to prevent warping, and heat resistance, the resin film may be a single-layer film selected from the group consisting of polyethylene films, polyester films, and polypropylene films, or a laminate film in which two or more types of films selected from this group are laminated.

[0073] The thickness of the pressure-sensitive adhesive sheet substrate 120 is not particularly limited, but from the viewpoint of achieving both supportability and roll winding ability, it is preferably 10 μm or more, more preferably 25 μm or more, even more preferably 40 μm or more, preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 90 μm or less. The thickness of the pressure-sensitive adhesive sheet substrate 120 is preferably in the range of 10 μm or more and 500 μm or less, more preferably 25 μm or more and 200 μm or less, and even more preferably 40 μm or more and 90 μm or less.

[0074] <Other layers> The adhesive sheet may have layers other than the adhesive sheet substrate 120 and the adhesive layer 110. For example, an additional adhesive layer may be provided on the surface of the adhesive sheet substrate 120 opposite the adhesive layer 110. The adhesive sheet can be attached to another substrate such as quartz glass via such an adhesive layer. The type of the additional adhesive layer is not particularly limited, and the additional adhesive layer can be formed using, for example, a general adhesive.

[0075] <Method of manufacturing adhesive sheets> There are no particular limitations on the method for manufacturing the adhesive sheet. In one embodiment, an adhesive sheet having an adhesive layer 110 provided on an adhesive sheet substrate 120 can be manufactured as follows. First, an organic solvent is added to the adhesive composition that forms the above-mentioned adhesive layer 110 to prepare a solution of the adhesive composition. This solution is then applied to the adhesive sheet substrate 120 to form a coating film, which is then dried, thereby providing an adhesive layer on the adhesive sheet substrate 120. Furthermore, by performing a process to provide irregularities on the surface of this adhesive layer, an adhesive layer 110 having irregularities can be formed.

[0076] In another embodiment, an adhesive sheet having adhesive layer 110 provided on adhesive sheet substrate 120 can be produced as follows. First, an organic solvent is added to the adhesive composition that forms adhesive layer 110 described above to prepare a solution of the adhesive composition. This solution is then applied to a mold or release sheet that has concaves and convexes opposite to those of adhesive layer 110 (complementary concaves and convexes) to form a coating film, which is then dried to produce adhesive layer 110. Adhesive layer 110 is then attached to adhesive sheet substrate 120 to produce an adhesive sheet.

[0077] Examples of organic solvents used to prepare a solution of the pressure-sensitive adhesive composition include toluene, ethyl acetate, and methyl ethyl ketone. Examples of methods for applying the solution include spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, gravure coating, and printing methods (e.g., screen printing and inkjet printing).

[0078] In one embodiment of the pressure-sensitive adhesive sheet, there are no particular limitations on the process for providing irregularities on the surface of the adhesive layer. For example, irregularities can be provided on the surface of the adhesive layer using an imprinting method. In the imprinting method, a mold having a surface shape complementary to the irregularities to be provided can be used. Specifically, irregularities can be provided on the surface of the adhesive layer by heating the adhesive layer while pressing the adhesive layer provided on the adhesive sheet substrate with the mold. A more specific method involves pressing the adhesive layer with the mold, heating the adhesive layer, and maintaining the temperature for a predetermined period of time, after which the adhesive layer is cooled and the mold is 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. The time for which the adhesive layer is maintained in the heated state is also not particularly limited, and may be maintained for, for example, 10 seconds or more or 10 minutes or less. A specific method for heating the adhesive layer while pressing the adhesive layer with the mold includes vacuum laminating the adhesive layer provided on the adhesive sheet substrate and the mold. Instead of performing the two-stage process of forming the adhesive layer and forming the irregularities, adhesive layer 110 having irregularities on its surface may be formed on adhesive sheet substrate 120 in a single stage.

[0079] As another method, an adhesive layer 110 having a textured shape can be provided by spray-coating a solution of the adhesive composition. Furthermore, an adhesive layer 110 having a rough or fibrous surface can be provided by adding a filler to a solution of the adhesive composition and coating such a solution. As yet another method, an adhesive layer having a textured shape can be directly provided on an adhesive sheet substrate by coating a solution of the adhesive composition according to a desired pattern using a printing method such as an inkjet method.

[0080] Furthermore, an adhesive sheet that does not have an adhesive sheet substrate 120 can be produced by forming an adhesive composition into a sheet. Furthermore, an adhesive layer may be formed by applying a liquid adhesive containing the adhesive composition to any object. In these cases, after forming the adhesive layer, a treatment may be performed to provide irregularities on the surface of the adhesive layer, or the adhesive layer may be formed by a method that forms irregularities on the surface.

[0081] <Capturing the element> The pressure-sensitive adhesive sheet according to this embodiment can be used to capture an element separated from a holding substrate. For example, the pressure-sensitive adhesive sheet can be used as a die catch sheet for catching a die such as a semiconductor die. This element is used to manufacture electronic components or semiconductor devices.

[0082] (Preparing the adhesive sheet) 4A to 4C are schematic diagrams illustrating separation and capture of an element. Capture of an element from a holding substrate using an adhesive sheet will be described with reference to FIGS. 4A to 4C. As shown in FIG. 1, an adhesive sheet and a release sheet are usually attached to a laminate until immediately before use. Just before use, as shown in FIG. 4A, the release sheet is peeled off from the laminate, and an adhesive sheet 150 having an uneven adhesive layer is prepared.

[0083] (Preparation of element and support substrate) As shown in FIG. 4B, element 170 is prepared, which is attached to holding substrate 160 so as to face adhesive sheet 150.

[0084] element The type of element is not particularly limited. The element may be, for example, a semiconductor chip such as an LED chip, a semiconductor chip with a protective film, or a semiconductor chip 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), or a controller chip, or a component thereof. The element may also be an individualized object such as a wafer, a panel, or a substrate. The element may have, for example, a circuit surface on which an integrated circuit having circuit elements such as transistors, resistors, and capacitors is formed. The element is not necessarily limited to an individualized object, and may also be various un-individualized wafers or various substrates.

[0085] The size of the element is not particularly limited. The size of the element is, for example, preferably 100 μm. 2 More preferably, 500 μm or more 2 More preferably, 1000 μm or more 2 On the other hand, the size of the element is preferably 100 mm 2 Less than 25mm, more preferably 2 Less than, and even more preferably, 1 mm 2 When small-sized elements are used, the laser lift-off method described below is suitable for separating the elements because it is easy to selectively separate small elements.

[0086] Examples of wafers include semiconductor wafers such as 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 (diameter approximately 150 mm) or larger, and more preferably 12 inches (diameter approximately 300 mm) or larger. The shape of the wafer is not limited to a circle, and may be an angular shape such as a square or rectangle.

[0087] The panel may be a fan-out semiconductor package (e.g., FOWLP or FOPLP). That is, the workpiece may be a semiconductor package before or after singulation in a fan-out semiconductor package manufacturing technique. The size of the panel is not particularly limited, but may be, for example, a rectangular substrate of about 300 to 700 mm.

[0088] The substrate may be a glass substrate, a sapphire substrate, or a compound semiconductor substrate.

[0089] holding board The type of the holding substrate is not particularly limited. For example, the holding substrate may be an adhesive sheet or a tray. The adhesive sheet may have an adhesive layer, and this adhesive layer may be provided on a substrate. In this case, the holding substrate can hold the element on the adhesive layer. The substrate may be a resin film or a hard substrate.

[0090] The method for preparing such a holding substrate for holding elements is not particularly limited. For example, a semiconductor wafer can be attached to the holding substrate, and the semiconductor wafer can then be diced. By dicing the semiconductor wafer in this manner, elements can be obtained, and a holding substrate with elements attached thereto can be obtained.

[0091] As another method, a semiconductor wafer can be diced, and the resulting elements can be transferred to a holding substrate to obtain a holding substrate with elements attached thereto. For example, a semiconductor wafer held on a wafer substrate can be diced, and then the resulting elements can be brought into close contact with the adhesive layer of the holding substrate. Then, an external stimulus such as laser light can be applied to reduce the adhesive strength between the wafer substrate and the elements. By this process, the elements can be transferred from the wafer substrate to the holding substrate.

[0092] As will be described later, in one embodiment, the element is separated from the holding substrate by irradiation with laser light (laser lift-off method). When using such a method, the adhesive layer of the holding substrate may contain a laser beam absorbent. Examples of the laser beam absorbent include one or more selected from pigments and dyes.

[0093] (Isolation and capture of elements) As shown in FIG. 4C , an external stimulus causes element 170, which is attached to holding substrate 160, to separate from holding substrate 160 and be captured by adhesive sheet 150. In one embodiment, holding substrate 160 and adhesive sheet 150 are stationary, and element 170, which has been separated from holding substrate 160, moves toward adhesive sheet 150. For example, when using the laser lift-off method described below, element 170 can move toward adhesive sheet 150 due to gas pressure generated by irradiation with laser light. However, it is not essential that element 170 move. For example, holding substrate 160 may move away from element 170. Alternatively, adhesive sheet 150 may move toward element 170.

[0094] separation The type of external stimulus used to separate the elements is not particularly limited, but examples include application of energy, cooling, stretching of the holding substrate, and physical stimulus (e.g., pressing the back surface of the holding substrate with a pin, etc.) By using one or more of these external stimuli, the bonding force between the holding substrate and the elements can be reduced, and the elements can be separated from the holding substrate.

[0095] Examples of energy application methods include local heating, light irradiation, and heat ray irradiation. Examples of light irradiation methods include infrared irradiation, visible light irradiation, and laser light irradiation. In one embodiment, the external stimulus is laser light irradiation, i.e., the element is separated from the holding substrate by laser lift-off. In this case, the laser light is directed toward the holding substrate at the attachment site of the specific element. For example, such laser light irradiation can be performed from the side of the holding substrate opposite the element. This generates gas at the contact site between the specific element and the holding substrate. For example, when the laser light is absorbed by the adhesive layer, at least a portion of the adhesive layer sublimes, generating gas. This sublimation of at least a portion of the adhesive layer reduces the adhesion area between the specific element and the adhesive layer, thereby reducing the adhesive strength between the specific element and the holding substrate. Furthermore, the pressure of the generated gas also reduces the adhesive strength between the specific element and the holding substrate. As a result, the specific element is separated from the holding substrate.

[0096] The conditions for irradiating the laser beam are not particularly limited. From the viewpoint of selectively and efficiently separating some elements, the frequency of the laser beam is preferably 10,000 Hz or more and 100,000 Hz or less. The beam diameter of the laser beam is preferably 10 μm or more, more preferably 20 μm or more, and is preferably 100 μm or less, more preferably 40 μm or less. The output of the laser beam is preferably 0.1 W or more and 10 W or less. The scanning speed of the laser beam is preferably 50 mm / sec or more and 2000 mm / sec or less.

[0097] capture 4C , element 170 separated from holding substrate 160 is captured by adhesive sheet 150. Specifically, element 170 moves relatively away from holding substrate 160. Also, element 170 moves relatively closer to adhesive sheet 150. Then, element 170 comes into contact with adhesive layer 110 of adhesive sheet 150, whereby element 170 is captured by adhesive sheet 150.

[0098] The gas compressed between the element and the adhesive layer 110 due to the element and the adhesive layer 110 coming close to each other can escape into the recesses in the adhesive sheet. In this way, the unevenness of the adhesive layer 110 can alleviate the pressure generated between the element 170 and the adhesive layer 110. Therefore, it is possible to prevent the pressure generated between the element and the adhesive layer 110 from shifting the holding position of the element on the adhesive sheet.

[0099] <<Release sheet>> <Release layer> The release sheet according to this embodiment has a release layer 130, which is in contact with the adhesive layer and may contain a resin. As described above, the surface of the release layer 130 has irregularities. The irregularities on the surface of the release layer 130 are complementary to the irregularities on the surface of the adhesive layer 110. In other words, the shape of the convex portions 111 of the adhesive layer 110 is similar to the shape of the concave portions 132 of the release layer 130, and the shape of the concave portions 112 of the adhesive layer 110 is similar to the shape of the convex portions 131 of the release layer 130. The release sheet may have two or more release layers 130. For example, the release sheet may have a laminate of one type of release layer 130 or two or more types of release layers 130.

[0100] (Shape of the peeling layer) In one embodiment, the release layer 130 has a plurality of spaced apart recesses bounded by protrusions on its surface. Each of the plurality of recesses may be separated by a protrusion that is continuous throughout the release layer 130. As described above, the recesses and protrusions on the surface of the release layer 130 are complementary to the recesses and protrusions on the surface of the release layer 130, and the specific shape of the recesses and protrusions on the surface of the release layer 130 is not limited.

[0101] In one embodiment, the convex portions located around each of the plurality of recesses are continuous to the edge of the release layer 130. FIGS. 5A to 5C are top views showing the shape of such a release layer 130. As shown in FIG. 5A, the recesses 132 may be regularly arranged on the surface of the release layer 130. Regularly arranging the recesses 132 means that the recesses 132 are aligned in a straight line at regular intervals. Alternatively, as shown in FIG. 5B, the recesses 132 may be arranged so that the intervals between them vary regularly. In the example of FIG. 5B, the intervals between the recesses 132 are short at the center of the release sheet and long at the periphery of the release sheet. Furthermore, the recesses 132 may be irregularly arranged.

[0102] Fig. 5C is a top view showing another shape of the release layer 130. As shown in Fig. 5C, stripe-shaped recesses 132 may be provided on the surface of the release layer 130. In Fig. 5C, linear recesses 132 having a constant width are arranged at regular intervals. However, as in Fig. 5B, the width or interval of the linear recesses 132 may vary regularly, or the linear recesses 132 may be arranged irregularly.

[0103] 5B, the minimum spacing among all the recesses 132 in the center of the release sheet may be shorter than the minimum spacing among all the recesses 132 in the peripheral portion of the release sheet. Here, the center refers to, for example, a circular region having 1 / 4 of the area of ​​the release sheet and centered on the center of gravity of the release sheet, and the peripheral portion refers to, for example, the entire area of ​​the release sheet other than the center.

[0104] As described above, the unevenness of the surface of the release layer 130 is complementary to the unevenness of the surface of the adhesive layer 110. Therefore, the pitch P of the recesses 132 of the release layer 130 can be the same as the pitch of the protrusions 111 of the adhesive layer 110. Therefore, the pitch of the recesses 132 is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. Meanwhile, this pitch is preferably 100 μm or less, more preferably 75 μm or less, more preferably 50 μm or less, even more preferably 35 μm or less, and particularly preferably 25 μm or less. Here, the pitch of the recesses 132 refers to the distance between the center point of one arbitrarily selected recess 132 and the center point of another recess 132 closest to that recess 132. For example, in the case of Fig. 5A, the pitch of the recesses 132 represents the distance between the center point of the recesses 132 on a line on which the recesses 132 are arranged at regular intervals and the center point of the recess 132 and another recess 132' that is closest to the recess 132. When the recesses 132 are arranged on multiple lines, the pitch represents the distance between the center points of the recesses on the line that is arranged at the shortest pitch. Also, for example, when the recesses have an elongated shape as shown in Fig. 5C and the center points of the recesses are difficult to identify, the pitch represents the distance from the boundary on the same side of the recess 132 to the boundary of the nearest other recess 132'.

[0105] The specific shape of the recess 132 is not particularly limited. For example, the recess 132 may be recessed in a pillar (column) shape. As a specific example, the recess 132 may be recessed in a cylindrical shape or a rectangular column shape. Furthermore, as described above, the recess 132 may be recessed so as to extend in a line, or may be recessed so as to extend in a curved shape such as a wave shape. Furthermore, these recesses 132 may be tapered.

[0106] Figure 6A shows a cross-sectional view of a release layer 130 according to one embodiment, taken through a recess 132 and perpendicular to the surface of the release layer 130. The recess 132 shown in Figure 6A is tapered, i.e., the recess 132 is tapered. As shown in Figure 6A, the surface of the release layer 130 may have flat protrusions and recesses 132 recessed from the protrusions. In this manner, multiple recesses 132 spaced apart from one another may be bounded by the protrusions.

[0107] 6B, the bottom of the recess 132 may be curved like a hemisphere or a part of a sphere. Alternatively, the bottom of the recess may be flat. As yet another example, the recess 132 may be recessed in the shape of a collection of grains, the surface of a lotus leaf, or a needle. As yet another example, the surface of the release layer 130 may be recessed in a rough or fibrous shape, and such a surface may also be said to have unevenness.

[0108] As described above, the unevenness of the surface of the release layer 130 is complementary to the unevenness of the surface of the adhesive layer 110, but in order to make it easier to peel the adhesive layer 110 from the release layer 130, the dimensions of the recesses 132 of the release layer 130 described below can be the same as or larger than the dimensions of the protrusions 111 of the adhesive layer 110.

[0109] The width or diameter of each recess 132 is the width or diameter of its top, not its bottom, and is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 5 μm or more, and particularly preferably 10 μm or more. On the other hand, it is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less. Here, the width and diameter of recess 132 refer to the minimum and maximum distances (represented by D in FIG. 6A ) between two parallel lines that contact recess 132 from both sides on the surface of the convex portion.

[0110] The area of ​​each recess 132 is preferably 10 μm 2 More preferably, 20 μm or more 2 More preferably, 30 μm or more2 On the other hand, the area of ​​each of the protrusions 111 is preferably 2000 μm 2 Less than or equal to 1000 μm, more preferably 2 Less than 500 μm, even more preferably 2 Here, the area of ​​the recess 132 means the area of ​​the portion recessed from the surface of the protrusion (the area of ​​a circle with a diameter D in the case of FIG. 6A).

[0111] The height (depth) of each recess 132 is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. On the other hand, the height (depth) of each recess 132 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. Here, the depth of recess 132 is represented by H in FIG. 6A.

[0112] Furthermore, the area of ​​each recess 132 relative to the area of ​​the release layer 130 is preferably 1% or more, more preferably 5% or more, more preferably 10% or more, even more preferably 18% or more, and particularly preferably 40% or more. On the other hand, the area of ​​each recess 132 relative to the area of ​​the release layer 130 is preferably 95% or less, more preferably 75% or less, and even more preferably 60% or less.

[0113] (thickness of release layer) The thickness of the release layer 130 is not particularly limited, but from the viewpoint of release properties, it can be preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, preferably 50 μm or less, more preferably 45 μm or less, and even more preferably 40 μm or less. The thickness of the release layer 130 can be in the range of preferably 10 μm or more and 50 μm or less, more preferably 15 μm or more and 45 μm or less, and even more preferably 20 μm or more and 40 μm or less.

[0114] (Composition of Release Layer (Release Agent Composition)) The release agent composition forming the release layer 130 contains a resin. In one embodiment, the resin contained in the release agent composition may be a polyolefin such as a polyethylene resin, a thermoplastic elastomer such as an olefin-based thermoplastic elastomer, a fluororesin such as tetrafluoroethylene, or a mixture thereof. The release agent composition forming the release layer 130 may also contain a non-silicone release agent (resin) or a non-silicone olefin-based release agent (resin). Examples of such resins include polyethylene resin and an olefin-based thermoplastic elastomer. If the release agent composition contains a silicone resin, a silicone compound layer derived from the silicone resin may be formed on the surface of the device during manufacturing. By using a non-silicone release agent (resin) or a non-silicone olefin-based release agent (resin) as the resin contained in the release agent composition forming the release layer 130, a silicone compound layer will not be formed on the surface of the device during manufacturing, and proper circuit formation may be achieved.

[0115] In one embodiment, when the resins contained in the release agent composition are an olefin-based thermoplastic elastomer and a polyethylene resin, the olefin-based thermoplastic elastomer and the polyethylene resin can satisfy the following conditions.

[0116] In one embodiment, the olefin-based thermoplastic elastomer may be an ethylene-propylene copolymer, an ethylene-octene copolymer, or the like. For example, the olefin-based thermoplastic elastomer may be an ethylene-propylene copolymer. By using an ethylene-propylene copolymer as the olefin-based thermoplastic elastomer, a release sheet with excellent releasability can be obtained.

[0117] The density of the olefin-based thermoplastic elastomer is not particularly limited, but is preferably 0.80 g / cm 3 More preferably, 0.86 g / cm 3 The density of the olefin-based thermoplastic elastomer is preferably 0.90 g / cm or more. This improves heat resistance. 3or less, more preferably 0.88 g / cm 3 The density of the olefin-based thermoplastic elastomer is preferably 0.80 g / cm or less. This improves releasability. 3 More than 0.90g / cm 3 or less, more preferably 0.86 g / cm 3 More than 0.88g / cm 3 It can be as follows:

[0118] In one embodiment, the polyethylene resin may be synthesized using a transition metal catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. For example, a polyethylene resin synthesized using a metallocene catalyst has excellent release properties and heat resistance.

[0119] The density of the polyethylene resin is not particularly limited, but is preferably 0.890 g / cm 3 More preferably, 0.900 g / cm 3 The density of the polyethylene resin is preferably 0.925 g / cm or more. This improves heat resistance. 3 or less, more preferably 0.922 gg / cm 3 The density of the polyethylene resin is preferably 0.890 g / cm or less. This improves the releasability. 3 More than 0.925g / cm 3 or less, more preferably 0.900 g / cm 3 More than 0.922g / cm 3 It can be as follows:

[0120] The mass ratio (compounding ratio) of the olefin-based thermoplastic elastomer to the polyethylene resin is not particularly limited, but is preferably 25:75 to 75:25, and more preferably 40:60 to 60:4. This improves the releasability and heat resistance. The release agent composition forming the release layer 130 may contain other resin components and various additives such as plasticizers and stabilizers.

[0121] <Release sheet substrate> The release sheet substrate 140 included in the release sheet according to this embodiment functions as a support for supporting the release layer 130. The type of release sheet substrate 140 is not particularly limited, and may be a hard substrate or a flexible substrate. For example, a resin film may be used as the release sheet substrate 140. Furthermore, the same material as the adhesive sheet substrate 120 described above may be used as the release sheet substrate 140.

[0122] The thickness of the release sheet substrate 140 is not particularly limited, but from the viewpoint of achieving both supportability and roll winding ability, it can be preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The thickness of the release sheet substrate 140 can be preferably in the range of 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, and even more preferably 30 μm or more and 100 μm or less.

[0123] <Other layers> The release sheet may have layers other than the release sheet substrate 140 and the release layer 130. For example, an intermediate layer may be provided between the release sheet substrate 140 and the release layer 130 to improve the adhesion between them.

[0124] <Method of manufacturing the release sheet> There are no particular limitations on the method for producing the release sheet. In one embodiment, a release sheet having a release layer 130 provided on a release sheet substrate 140 can be produced as follows. First, an organic solvent is added to the release agent composition that forms the release layer 130 described above to prepare a solution of a pressure-sensitive adhesive composition. This solution is then applied to the release sheet substrate 140 to form a coating film, which is then dried, thereby providing a release layer on the release sheet substrate 140. Furthermore, a treatment to provide irregularities on the surface of this release layer can be performed to form a release layer 130 having irregularities.

[0125] In another embodiment, a release sheet having a release layer 130 provided on a release sheet substrate 140 can be produced as follows. First, an organic solvent is added to the release agent composition that forms the release layer 130 described above to prepare a solution of the release agent composition. This solution is then applied to a mold or adhesive sheet having an inverse (complementary) unevenness to the unevenness of the release layer 130 described above to form a coating film, which is then dried to produce the release layer 130. The release layer 130 is then attached to the release sheet substrate 120, thereby producing a release sheet.

[0126] The organic solvent used to prepare the release agent composition solution and the method for applying the solution can be the same as those used for the pressure-sensitive adhesive composition described above.

[0127] In the production of the pressure-sensitive adhesive sheet in one embodiment, there are no particular limitations on the treatment for providing irregularities on the surface of the release layer, and the same methods as those for the pressure-sensitive adhesive layer described above can be used.

[0128] Furthermore, a release sheet that does not have a release sheet substrate 140 can be produced by forming a release agent composition into a sheet. Furthermore, a release layer may be formed by applying a liquid release agent containing the release agent composition to any object. In these cases, after the release layer is formed, a treatment may be performed to provide irregularities on the surface of the release layer, or the release layer may be formed by a method that forms irregularities on the surface. [Example]

[0129] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. In each example, parts and percentages are by weight unless otherwise specified.

[0130] In producing the pressure-sensitive adhesive sheets in the examples and comparative examples, the following compounds were used. (Component (A)) Acrylic copolymer (A1): Monomer ratio 2-ethylhexyl acrylate / 2-hydroxyethyl acrylate / acrylic acid = 92.8 / 7.0 / 0.2, mass average molecular weight (Mw) 1.1 million

[0131] ((B) component) Energy ray curable resin (B1): Toagosei Co., Ltd., product name "Aronix M-920" Energy ray curable resin (B2): Toagosei Co., Ltd., product name "Aronix M-930"

[0132] ((C) component) Crosslinker (C1): Isocyanurate-type polyisocyanate derived from hexamethylene diisocyanate

[0133] ((D) component) Photopolymerization initiator (D1): 1-hydroxycyclohexyl phenyl ketone

[0134] Example 1 Preparation of adhesive sheets A pressure-sensitive adhesive composition was prepared by dissolving 100 parts by weight of an acrylic acid ester copolymer (A), 5.0 parts by weight of an energy ray-curable resin (B1), 0.5 parts by weight of a crosslinking agent (C), and 0.15 parts by weight of a photopolymerization initiator (D1) in toluene. This pressure-sensitive adhesive composition was applied to the release-treated surface of a processing sheet (manufactured by Lintec Corporation, product name "SP-PET382150", thickness 38 μm), and the resulting coating was dried at 100 °C for 2 minutes to form a 25 μm-thick adhesive layer. A substrate (polyethylene terephthalate film, thickness 50 μm) was attached to this adhesive layer to prepare a pressure-sensitive adhesive sheet with a smooth surface.

[0135] Fabrication of release sheets with uneven surfaces A release agent composition was prepared by dissolving 50 parts by weight of an olefin-based thermoplastic elastomer containing an ethylene-propylene copolymer and 50 parts by weight of a polyethylene resin in toluene. This release agent composition was applied to a polyethylene terephthalate film (38 μm thick), and the resulting coating was dried at 100°C for 2 minutes to form a release layer with a thickness of 20 μm. The release layer was then softened by heating to 160°C, and a master mold with a pre-formed convex shape was attached to it to produce a release sheet with a concave-convex shape on its surface.

[0136] After peeling off the process sheet, the adhesive layer of the adhesive sheet was attached to a release sheet having an uneven surface, and the laminate was vacuum laminated at 60°C for 300 seconds. Next, an ultraviolet irradiator (Heraeus) was used to irradiate the adhesive layer with an illuminance of 130mW / cm. 2 , light intensity 210mJ / cm 2 By irradiating the adhesive sheet with ultraviolet light at 1000 kJ / cm, a laminate was produced which was composed of an adhesive sheet having an uneven surface and a release sheet having an uneven surface.

[0137] The uneven shape of the adhesive layer of the adhesive sheet was a grid-like arrangement of pillars, similar to Figure 2A. The pitch (P) between the pillars in the adhesive sheet was 20 μm. Also, as shown in Figure 3A, the height (H) of each pillar was 8 μm, the diameter (T) of the tip end was 8 μm, and the diameter (D) of the base end was 16 μm. The ratio of the area of ​​the adhesive layer and the captured element's adhesive portion (i.e., the area of ​​the tip end of the convex portion) to the area of ​​the adhesive sheet was approximately 12.6%. The uneven shape of the adhesive layer of the adhesive sheet had a surface shape complementary to the uneven shape of the release sheet.

[0138] (Examples 2 to 4 and Comparative Examples 1 and 2) Laminates of Examples 2 to 4 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the types and blending ratios of each component were changed to those shown in Table 1.

[0139] (Reference Examples 1 and 2) The laminates of Reference Examples 1 and 2 were obtained in the same manner as in Example 1, except that the types and blending ratios of each component were changed to those shown in Table 1 and no irregularities were formed on the surface of the adhesive sheet.

[0140] (peel force) The laminates obtained in the examples and comparative examples were cut into pieces 150 mm long x 50 mm wide. The liner peel strength of the release sheet (the strength when the release sheet side is folded back at 180° and peeled) was measured using a universal tensile tester (Shimadzu Corporation) at 23°C and 50% RH (relative humidity) using a 180° peel method at a tensile speed of 300 m / min. The peel strength results are shown in Table 1.

[0141] [Table 1]

[0142] The peel strength of the laminates of Examples 1 to 4 was 1000 mN / 50 mm or less, which indicated that the laminates of Examples 1 to 4 allowed the pressure-sensitive adhesive sheets having an uneven surface to be easily peeled from the release sheet.

[0143] On the other hand, the peel strength was 1000 mN / 50 mm or more for the laminates of Comparative Examples 1 and 2. This means that for the laminates of Comparative Examples 1 and 2, the pressure-sensitive adhesive sheets having an uneven surface could not be easily peeled from the release sheet.

[0144] Although the embodiments of the invention have been described above, the invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

[0145] This application claims priority based on Japanese Patent Application No. 2022-151756 filed on September 22, 2022, Japanese Patent Application No. 2022-151757 filed on September 22, 2022, Japanese Patent Application No. 2023-058459 filed on March 31, 2023, Japanese Patent Application No. 2023-058460 filed on March 31, 2023, Japanese Patent Application No. 2023-058462 filed on March 31, 2023, and Japanese Patent Application No. 2023-058463 filed on March 31, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A laminate comprising an adhesive sheet for capturing an element separated from a holding substrate, and a release sheet laminated on one side of the adhesive sheet, the pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer has an uneven surface; the adhesive layer contains an acrylic resin (A) crosslinked with an isocyanate-based crosslinking agent (C), and the amount of the isocyanate-based crosslinking agent (C) per 100 parts by mass of the acrylic resin (A) is 0.5 parts by mass or more; the surface of the adhesive layer has a plurality of pillar-shaped convex portions, the height of the convex portions is 1 μm or more and 20 μm or less, and the pitch of the plurality of convex portions is 1 μm or more and 100 μm or less; the release sheet comprises a release layer in contact with the pressure-sensitive adhesive layer, the release layer being made of a release agent composition, the release agent composition containing an olefin-based thermoplastic elastomer and a polyethylene resin, and the release layer having an uneven surface; A laminate in which the peel strength of the release sheet at a peel angle of 180° from the pressure-sensitive adhesive sheet measured at a peel rate of 300 mm / min is 1000 mN / 50 mm or less.

2. The laminate according to claim 1 , wherein the release layer has a thickness of 10 μm or more.

3. The laminate according to claim 2 , wherein the release sheet further comprises a release sheet substrate having a thickness of 10 μm or more that supports the release layer.

4. The laminate according to claim 1 , wherein the unevenness of the surface of the adhesive layer is complementary to the unevenness of the surface of the release layer.

5. the release layer has a surface having a plurality of spaced apart recesses bounded by protrusions; The laminate according to claim 1 , wherein the height of the recessed portion of the release layer is 1 μm or more.

6. The laminate according to claim 1 , wherein the adhesive layer is formed from an adhesive composition containing the acrylic resin (A), an energy ray-curable compound (B), and the isocyanate-based crosslinking agent (C).

7. the adhesive layer has a surface having a plurality of protrusions spaced apart from one another and bounded by recesses; The area of ​​each of the plurality of protrusions of the adhesive layer is 10 μm ２ More than 2000 μm ２ 2. The laminate of claim 1, wherein:

8. the adhesive layer has a surface having a plurality of protrusions spaced apart from one another and bounded by recesses; The laminate according to claim 1 , wherein a ratio of an area occupied by the convex portions of the adhesive layer to an area of ​​the adhesive layer is 1% or more and 95% or less.

9. The laminate according to claim 1 , wherein the adhesive layer is configured so that the ratio of the adhesive area between the adhesive layer and one of the elements to the area of ​​one of the elements is 1% or more and 95% or less.

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