Pressure-sensitive adhesive sheet, production method therefor, and method for separating object from pressure-sensitive adhesive sheet
Patent Information
- Application Number
- PCT/JP2026/012664
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-28
- Filing Date
- 2026-03-27
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026012664_01102026_PF_FP_ABST
Abstract
Description
Adhesive sheet, method for manufacturing the same, and method for peeling an object from the adhesive sheet
[0001] This invention relates to an adhesive sheet, a method for manufacturing the same, and a method for peeling an object from an adhesive sheet, 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 objects to a desired position. Furthermore, to improve production efficiency, it is also desirable to facilitate the removal of objects from the adhesive sheet. For example, Patent Document 1 discloses an adhesive sheet having an adhesive layer with irregularities on its surface, configured to facilitate the removal of objects.
[0003] International Publication No. 2024 / 063124
[0004] Adhesive sheets are sometimes fixed to a fixing member such as a frame. For example, with the outer circumference of the adhesive sheet fixed to a frame such as a ring frame, an object may be attached to the adhesive sheet, the object on the adhesive sheet may be processed, the adhesive sheet may be expanded, or the object may be peeled off the adhesive sheet. The adhesive sheet is fixed to the frame in a way that provides sufficient fixing force for the above-mentioned processing. On the other hand, the work can be simplified by simply attaching the adhesive sheet to the frame. However, the adhesive sheet described in Patent Document 1 has irregularities on its surface, which leaves room for improvement in terms of fixing force when attached to a frame.
[0005] The present invention aims to improve the fixing strength when an adhesive sheet having an adhesive layer with an uneven surface is attached to a fixing member such as a frame.
[0006] After extensive research, the inventors discovered that the above problem could be solved by designing an adhesive layer suitable for attachment to fixed members such as frames. Further investigations led to the completion of the present invention.
[0007] In other words, embodiments of the present invention relate to the following [1] to
[14] . [1] An adhesive sheet comprising a laminate having a base material, a second adhesive layer, and a first adhesive layer in this order, wherein the first adhesive layer covers a part of the second adhesive layer, the adhesive surface of the first adhesive layer has an uneven portion, and the second adhesive layer has an adhesive surface in its peripheral portion that has a flat portion not covered by the first adhesive layer. [2] The adhesive sheet according to [1], wherein the uneven portion of the first adhesive layer is surrounded by the flat portion of the second adhesive layer. [3] The adhesive sheet according to any one of [1] to [2], wherein the material of the first adhesive layer and the material of the second adhesive layer are the same. [4] The adhesive sheet according to any one of [1] to [2], wherein the material of the first adhesive layer and the material of the second adhesive layer are different. [5] The adhesive sheet according to any one of [1] to [4], wherein the adhesive strength of the second adhesive layer is higher than the adhesive strength of the first adhesive layer. [6] The adhesive sheet according to any one of [1] to [5], wherein the tensile modulus of the flat portion of the second adhesive layer is lower than the tensile modulus of the portion of the second adhesive layer covered by the first adhesive layer. [7] The adhesive sheet according to any one of [1] to [6], wherein the interlayer adhesion between the first adhesive layer and the second adhesive layer, as evaluated by the cross-cut method in accordance with JIS K5600-5-6:1999, is 0, 1, or 2. [8] The adhesive sheet according to any one of [1] to [7], wherein the adhesive sheet is expandable by 10% or more in one direction, and the adhesive force between the first adhesive layer and the second adhesive layer is configured such that the first adhesive layer expands in accordance with the second adhesive layer when the adhesive sheet is expanded by 10% or more by supporting the flat portion of the second adhesive layer. [9] The adhesive sheet according to any one of [1] to [8], wherein the flat portion is provided along at least a part of the outer edge of the second adhesive layer and has a width of 5 mm or more.
[10] The adhesive sheet according to any one of [1] to [9], wherein the uneven portion is provided with a plurality of protrusions, and the height of the plurality of protrusions is uniform.
[11] The adhesive sheet according to any one of [1] to
[10] , wherein the uneven portion is provided with a plurality of protrusions, and the height of each of the plurality of protrusions is 1 μm or more.
[12] The adhesive sheet according to any one of [1] to
[11] , wherein the uneven portion is provided with a plurality of protrusions, and the pitch of the plurality of protrusions is 1 μm or more and 100 μm or less.
[13] A method for peeling off an object attached to the uneven portion of an adhesive sheet according to any one of [1] to
[12] , comprising: an expansion step of expanding the adhesive sheet supported by a frame attached to the flat portion of the adhesive sheet in the planar direction; and a peeling step of peeling the object off the adhesive surface of the adhesive sheet.
[14] A method for manufacturing an adhesive sheet comprising a laminate having a base material, a second adhesive layer, and a first adhesive layer in this order, comprising: a step of preparing the first adhesive layer having an uneven portion formed on the first surface; and a step of laminating the second adhesive layer and the base material on the second surface of the first adhesive layer such that the second adhesive layer has an adhesive surface with a flat portion in its peripheral area that is not covered by the first adhesive layer.
[0008] This technology can enhance the fixing strength when an adhesive sheet with an adhesive layer having an uneven surface is attached to a fixing member such as a frame.
[0009] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.
[0010] 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.
[0011] Cross-sectional view of an adhesive sheet according to one embodiment. Top view of an adhesive sheet according to one embodiment. Cross-sectional view of the adhesive layer 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 manufacturing method for the adhesive sheet according to one embodiment. Flowchart of a method of using the adhesive sheet according to one embodiment.
[0012] 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.
[0013] (Definition) In this specification, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," as do other similar terms.
[0014] 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 that it is 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 clearly means that the numerical range may be any of the following: 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. Also, in this specification, parts by mass and mass percent indicate a proportion based on the mass of solids unless otherwise specified.
[0015] (Adhesive Sheet) The adhesive surface of the adhesive sheet according to one embodiment of the present invention has an uneven portion and a flat portion provided around the periphery of the adhesive surface. By attaching the flat portion to the frame, the fixing force of the adhesive sheet by the frame can be increased.
[0016] Adhesive sheets can be used as transfer sheets to temporarily hold an object and transfer it to a destination. For example, an adhesive sheet can be used to receive an object held on another holding substrate, temporarily hold the object, and transfer the object to a desired position on a destination.
[0017] Figure 1A is a schematic cross-sectional view showing an adhesive sheet 100 according to one embodiment. Figure 1B is a schematic top view showing the adhesive sheet 100. The adhesive sheet 100 comprises a laminate having a base material 130, an adhesive layer 120, and an adhesive layer 110 in that order. The adhesive sheet 100 according to this embodiment may have two or more adhesive layers, including the adhesive layer 110 and the adhesive layer 120.
[0018] (Adhesive Layers) The adhesive layers 110 and 120 are each adhesive layers. In this embodiment, the adhesive surface 111 of the adhesive sheet 100 includes the surfaces of the adhesive layers 110 and 120. Here, the adhesive layer 110 covers a part of the adhesive layer 120. The adhesive layer 110 may be a laminate of two or more adhesive layers. Similarly, the adhesive layer 120 may be a laminate of two or more adhesive layers. In this case, the materials of each adhesive layer constituting the adhesive layer 110 or 120 may be the same or different.
[0019] The adhesive layer 120 has an adhesive surface having a flat portion 115 that is not covered by the adhesive layer 110. The adhesive surface of the adhesive layer 120 has such a flat portion 115 in its peripheral area. The flat portion 115 has a flat surface. Furthermore, the flat portion 115 is designed to attach a fixing member such as a frame. On the other hand, the adhesive surface of the adhesive layer 110 has an uneven portion 112. The uneven portion 112 is a region having an uneven surface. In one embodiment, the uneven portion 112 is designed to hold an object. Thus, the flat portion 115 has a flatter surface than the uneven portion 112. The adhesive strength of a flat adhesive surface to a solid is expected to be higher than the adhesive strength of an adhesive surface with an uneven surface to a solid. Since the adhesive sheet 100 has a flat portion 115 in addition to the uneven portion 112, the fixing strength of the adhesive sheet 100 can be increased by attaching the adhesive sheet 100 to a fixing member such as a frame via the flat portion 115.
[0020] Such flat portions 115 are provided on at least a part of the outer edge of the adhesive layer 120. In order to sufficiently fix the adhesive sheet 100 to the fixing member, in one embodiment, the flat portions 115 are provided at at least two locations on the outer edge of the adhesive layer 120 so as to sandwich the adhesive layer 110 in the planar direction. As shown in Figure 1B, in one embodiment, the adhesive layer 110 is smaller than the adhesive layer 120 in plan view. Also, the entire adhesive layer 110 is on top of the adhesive layer 120. Also, as shown in Figure 1B, in one embodiment, the adhesive layer 110 is surrounded by the flat portions 115. That is, the entire outer edge of the adhesive layer 120 is outside the outer edge of the adhesive layer 110 and is not covered by the adhesive layer 110. In this way, the flat portions 115 are provided so as to surround the adhesive layer 110 along the outer edge of the adhesive layer 120.
[0021] The planar shapes of the adhesive layers 110 and 120 are not particularly limited. In the example shown in Figure 1B, the planar shape of the adhesive layer 110 is circular. However, the adhesive layer 110 may be a circular shape with a portion missing. For example, the adhesive layer 110 may have a shape obtained by cutting off each end of a circle with a straight line. The adhesive layer 110 may have another shape, such as an ellipse or a rectangle. Similarly, the planar shape of the adhesive layer 120 may be circular, a circular shape with a portion missing, an ellipse, or a rectangle.
[0022] In one embodiment, the planar shape of the adhesive layer 110 is circular or substantially circular. The planar shape of the adhesive layer 120 is also circular or substantially circular. In this case, the circular or substantially circular adhesive layer 110 and the circular or substantially circular adhesive layer 120 may be concentric. In this case, an annular or substantially annular flat portion 115 is formed around the adhesive layer 110.
[0023] The difference between the diameter of the adhesive layer 110 and the diameter of the adhesive layer 120 is preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 50 mm or less. In one embodiment, the inscribed circle to which the outer circumference of the adhesive layer 110 is in contact and the circumscribed circle to which the outer circumference of the adhesive layer 120 is in contact can be defined. In this case, the difference between the diameter of the inscribed circle and the diameter of the circumscribed circle is preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 50 mm or less.
[0024] In one embodiment, the flat portion 115 is provided to have a width of 5 mm or more. The width of the flat portion 115 refers to the minimum length of the flat portion 115 in a direction perpendicular to the outer edge of the adhesive layer 120 at each position of the flat portion 115. In one embodiment, the flat portion 115 is provided to have a width of 5 mm or more along at least a part of the outer edge of the adhesive layer 120. In another embodiment, the flat portion 115 is provided to have a width of 5 mm or more along the entire outer edge of the adhesive layer 120. From the viewpoint of improving adhesion to the fixing member while ensuring a larger adhesive layer 110, the width of the flat portion 115 is preferably 5 mm or more and 50 mm or less, and more preferably 10 mm or more and 25 mm or less.
[0025] The thickness of the adhesive layer 110 is preferably 1 μm to 100 μm, more preferably 2 μm to 75 μm, even more preferably 5 μm to 50 μm, and particularly preferably 10 μm to 30 μm. Increasing the thickness of the adhesive layer 110 improves the adhesive strength of the adhesive layer 110 through the uneven portion 112. In one embodiment, the adhesive layer 110 is thicker than the adhesive layer 120. Also, by making the adhesive layer 110 thinner, the volume of the adhesive sheet 100 can be reduced. Note that the thickness of the adhesive layer 110 refers to the thickness including the protrusions 113.
[0026] The thickness of the adhesive layer 120 is preferably 1 μm to 100 μm, more preferably 2 μm to 50 μm, even more preferably 3 μm to 20 μm, and particularly preferably 5 μm to 10 μm. Increasing the thickness of the adhesive layer 120 improves the tensile strength and makes it easier for the adhesive layer 110 to expand as the adhesive layer 120 expands. Also, making the adhesive layer 120 thinner can reduce the volume of the adhesive sheet 100.
[0027] As described above, the adhesive surface of the adhesive layer 110 has an uneven portion 112. The uneven portion 112 may have a convex portion 113 and a concave portion 114. The convex portion 113 refers to a portion of the adhesive surface of the adhesive layer 110 that protrudes relative to the concave portion 114. As shown in Figure 1B, the entire adhesive surface of the adhesive layer 110 may be an uneven portion 112. On the other hand, the uneven portion 112 may be provided only on a part of the adhesive surface of the adhesive layer 110. In one embodiment, the uneven portion 112 of the adhesive layer 110 is surrounded by a flat portion 115 of the adhesive layer 120.
[0028] In one embodiment shown in Figures 1A and 1B, the uneven portion 112 has a plurality of protrusions 113 whose boundaries are defined by recesses 114 and which are spaced apart from each other. Each of the plurality of protrusions 113 may be spaced apart by recesses 114 that are continuous throughout the entire uneven portion 112. For example, the uneven portion 112 may have flat recesses 114 and protrusions 113 that project from the recesses 114.
[0029] As shown in Figure 1B, the adhesive surface of the adhesive layer 110 may have protrusions 113 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 113 may be arranged so that the intervals between them vary regularly. For example, the intervals between the protrusions 113 may be short in the center of the uneven surface 112, and longer in the peripheral area of the uneven surface 112. Furthermore, the protrusions 113 may be arranged irregularly.
[0030] Figure 2 is a top view showing another shape of the adhesive layer 110. As shown in Figure 2, the adhesive surface of the adhesive layer 110 may be provided with stripe-shaped protrusions 113. In Figure 2, line-shaped protrusions 113 having a certain width are arranged at regular intervals. The width or spacing of these line-shaped protrusions 113 may vary regularly, or the line-shaped protrusions 113 may be arranged irregularly.
[0031] The pitch P of the protrusions 113 is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, even more preferably 10 μm to 35 μm, and even more preferably 15 μm 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 113 refers to the distance between the center point of one arbitrarily selected protrusion 113 and the center point of the nearest other protrusion 113. For example, in Figure 1B, the pitch P of the protrusions 113 represents the distance between the center point of a protrusion 113 on a straight line in which the protrusions 113 are aligned at regular intervals and the center point of the nearest other protrusion 113. When the protrusions 113 are aligned on multiple straight lines, the pitch P represents the distance between the center points of the protrusions on the straight line in which the protrusions 113 are aligned at the shortest pitch. In Figure 2, the pitch P of the protrusions 113 represents the distance between adjacent protrusions 113. In this specification, the distance between protrusions 113 means the distance between the centers of the protrusions.
[0032] The specific shape of the protrusion 113 is not particularly limited. For example, the protrusion 113 may have a pillar shape. Specifically, the protrusion 113 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 113 may extend in a linear shape or in a curved shape such as a wave shape. Furthermore, these protrusions 113 may be provided with a taper or a reverse taper. For example, the protrusion 113 may be provided with a taper. That is, as shown in Figure 1C, a cross-sectional view of the adhesive layer 110, the protrusion 113 may taper to a point. Also, as shown in Figure 1C, the tip of the protrusion 113 may be a curved surface. With such a configuration, the impact when holding an object with the uneven surface 112 is further mitigated, making it easier for the uneven surface 112 to hold the object without it shifting. On the other hand, the tip of the protrusion 113 may be a flat surface. As another example, the protrusion may be hemispherical or part of a sphere. Furthermore, the protrusions 113 may be T-shaped. In yet another example, the protrusions 113 may be in the shape of a collection of grains, mushroom-shaped, lotus leaf-like, or needle-shaped. In yet another example, the uneven surface 112 may be rough or fibrous, and such a surface can also be said to have unevenness.
[0033] The width or diameter of each protrusion 113 is preferably 1 μm to 100 μm, more preferably 2 μm to 50 μm, even more preferably 5 μm to 30 μm, and even more preferably 10 μm to 20 μm. By increasing the width or diameter of the protrusion 113, the holding force of the object can be maintained. Conversely, by decreasing the width or diameter of the protrusion 113, the ease of peeling the object can be increased. Here, the width and diameter of the protrusion 113 refer to the minimum and maximum distances (represented as W in Figure 1C) between two parallel lines tangent to the protrusion 113 on both sides of the surface of the recess, respectively.
[0034] Furthermore, the area of each protrusion 113 is preferably 10 μm ２ 2000 μm or more ２ More preferably, 20 μm ２ 1000 μm or more ２ More preferably 30 μm２ 500 μm or more ２ or less. By increasing the area of the protrusions 113, the holding force for an object can be maintained. Further, by reducing the area of the protrusions 113, the ease of peeling the object can be improved. Here, the area of the protrusion 113 means the area of the portion protruding from the surface of the recess (in the case of FIG. 1C, the area of a circle with diameter W).
[0035] In one embodiment, the height of each protrusion 113 is preferably 1 μm or more, and preferably 20 μm or less. Further, the height of the protrusion 113 is more preferably 3 μm or more and 15 μm or less, still more preferably 5 μm or more and 10 μm or less. By increasing the height of the protrusions 113, the ease of peeling the object can be improved. Further, by reducing the height of the protrusions 113, the holding force for the object can be improved. By adjusting the height of the protrusions 113, the holding force for the object can be changed. Here, the height of the protrusion 113 is represented by H in FIG. 1C. Further, in one embodiment, the heights of the plurality of protrusions of the adhesive layer 110 are uniform. In another embodiment, the adhesive layer 110 may include 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 protrusions 113 may be composed of such first protrusions and second protrusions. In a further embodiment, the adhesive layer 110 may have a plurality of protrusions with random heights.
[0036] Further, the total area of the protrusions 113 relative to the area of the adhesive layer 110 is preferably 1% or more and 95% or less, more preferably 5% or more and 75% or less, still more preferably 10% or more and 70% or less, still more preferably 18% or more and 65% or less, even more preferably 40% or more and 60% or less. By increasing the total area of the protrusions 113, the holding force for an object can be maintained. Further, by reducing the total area of the protrusions 113, the ease of peeling the object can be improved.
[0037] Furthermore, the pressure-sensitive adhesive sheet 100 according to one embodiment is expandable in the planar direction. As will be described later, expanding the pressure-sensitive adhesive sheet 100 deforms the pressure-sensitive adhesive layer 110 shown in FIG. 3A as illustrated in FIG. 3B. Expansion of the pressure-sensitive adhesive sheet 100 causes shear stress to act between the protrusions 113 and an object. Additionally, expansion of the pressure-sensitive adhesive sheet 100 increases the pitch P of the protrusions 113 and decreases the number of protrusions 113 that hold a single object. The inventors of the present application consider that for these reasons, the holding force of the protrusions 113 on the object 300 decreases. From the viewpoint of sufficiently reducing the holding force for an object, the pressure-sensitive adhesive sheet 100 according to one embodiment may be expandable by 1% or more in the planar direction (for example, in one direction or two orthogonal directions), may be expandable by 5% or more, or may be expandable by 10% or more. The pressure-sensitive adhesive sheet 100 according to one embodiment has improved fixing force when adhered to a fixing member. Therefore, the pressure-sensitive adhesive sheet 100 is suitable for applications in which the pressure-sensitive adhesive sheet 100 is greatly expanded to 5% or more, or 10% or more via the fixing member.
[0038] (Example Composition of Pressure-Sensitive Adhesive Layer) Hereinafter, example compositions of the pressure-sensitive adhesive layers 110 and 120 will be described. Here, the material of the pressure-sensitive adhesive layer 110 and the material of the pressure-sensitive adhesive layer 120 may be the same. On the other hand, the material of the pressure-sensitive adhesive layer 110 and the material of the pressure-sensitive adhesive layer 120 may be different. That is, the pressure-sensitive adhesive layer 110 and the pressure-sensitive adhesive layer 120 may each independently be formed of the materials exemplified below. However, the compositions of the pressure-sensitive adhesive layers 110 and 120 are not limited to those shown below.
[0039] The adhesive layer may contain a resin. The adhesive layer may contain one type of resin or two or more types of resins. Examples of resins included in the adhesive layer 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 may also be heat-resistant, and examples of materials for such a heat-resistant adhesive layer include polyimide resins and silicone resins. The adhesive layer 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.
[0040] Furthermore, the glass transition temperature (Tg) of the resin is preferably -75°C or higher, more preferably -70°C or higher, preferably 5°C or lower, and more preferably -20°C or lower, from the viewpoint of improving the adhesive strength of the adhesive layer. 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.
[0041] The amount of resin contained in the adhesive layer relative to the total amount of components constituting the adhesive layer can be appropriately set according to the required adhesive strength of the adhesive layer, but is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, preferably 99.99% by mass or less, more preferably 99.95% by mass or less, even more preferably 99.90% by mass or less, even more preferably 99.80% by mass or less, and even more preferably 99.50% by mass or less.
[0042] In one embodiment, the resin contained in the adhesive layer may include a thermoplastic resin. When a thermoplastic resin is used, it becomes easy to form irregularities in the adhesive layer by heating and softening the resin, and it 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. Examples include polybutadiene-based thermoplastic elastomers in which butadiene is used as the monomer, styrene-based thermoplastic elastomers in which styrene is used as the monomer, and acrylic-based thermoplastic elastomers in which (meth)acrylic acid or (meth)acrylic acid ester is used as the monomer.
[0043] In one embodiment, the adhesive layer is energy-ray reactive. For example, the adhesive layer may contain an energy-ray reactive component in addition to the resin. Alternatively, the adhesive layer may contain an energy-ray reactive resin. In this specification, an adhesive layer being energy-ray reactive means that its storage modulus is improved by irradiation with energy rays. Irradiating an energy-ray reactive adhesive layer with energy rays increases its storage modulus. Irradiating an energy-ray reactive adhesive layer with energy rays also reduces its adhesive strength. The type of energy ray is not particularly limited and examples include ultraviolet rays, electron beams, or ionizing radiation. The energy ray is preferably ultraviolet rays, meaning the adhesive layer is preferably ultraviolet-reactive.
[0044] In one embodiment, in order to control the holding force of an object while increasing the fixing force to the fixing member, the adhesive strength of the adhesive layer 120 is higher than that of the adhesive layer 110. Here, the adhesive strength of the adhesive layer 110 is evaluated at the uneven portion 112. The adhesive strength of the adhesive layer 120 is evaluated at the flat portion 115. In this specification, adhesive strength refers to the value measured according to the 180° peel method. Specifically, an adhesive sheet is cut to a size of 25 mm x 50 mm so that the adhesive layer to be measured is exposed, and then the surface of the adhesive layer is pressed onto the mirror surface of a mirror silicon wafer using a laminator. After pressing, the sample for adhesive strength measurement is prepared by leaving it to stand for 1 hour in an environment of 23°C and 50% RH (relative humidity). The adhesive strength (N / 25mm) of the prepared adhesive strength sample is measured using a tensile testing machine at 23°C and 50% RH (relative humidity) with a peel angle of 180° and a tensile speed of 300 mm / min. Except for the measurement conditions described above, the procedure follows JIS Z0237:2000. If a 25mm x 50mm sample cannot be cut, the adhesive strength may be measured using a smaller sample, and the adhesive strength may be adjusted according to the sample width. Furthermore, if it is difficult to grip the sample with the testing machine's grips and peel it at a 180° angle, a tape of the same width as the sample but longer can be attached to the sample as a lead, and the test can be performed by gripping this lead with the testing machine's grips. This lead tape preferably has high adhesive strength to adhere sufficiently to the sample and rigidity to prevent deformation during the test, such as a tape made of polyethylene terephthalate.
[0045] From a similar viewpoint, in one embodiment, the elastic modulus of the adhesive layer 120 is lower than that of the adhesive layer 110. For example, the storage modulus in the flat portion 115 of the adhesive layer 120 may be lower than the storage modulus in the uneven portion 112 of the adhesive layer 110. Also in one embodiment, the gel fraction in the flat portion 115 of the adhesive layer 120 is lower than the gel fraction in the uneven portion 112 of the adhesive layer 110. With such a configuration, the fixing force to the fixing member in the flat portion 115 can be increased, while the holding force of the object in the uneven portion 112 can be controlled. In this specification, the storage modulus is measured by the torsional vibration method in accordance with JIS K7244-7:2007.
[0046] In one embodiment, the cohesive force at the flat portion 115 of the adhesive layer 120 is greater than the cohesive force at the uneven portion 112 of the adhesive layer 110. With this configuration, the fixing force to the fixing member at the flat portion 115 of the adhesive layer 120 can be increased, and even when the adhesive sheet 100 is expanded, it is possible to suppress the adhesive sheet 100 from slipping off the fixing member.
[0047] In this specification, cohesive force refers to the value measured according to the holding force measurement method of JIS Z0237:2009. Specifically, after cutting the adhesive sheet to a size of 25 mm x 150 mm, the surface of the exposed adhesive layer is pressed onto a stainless steel plate (SUS304, 600 grit) using a roller so that the adhesive area is 25 mm x 25 mm. After pressing, a 2 kg weight is suspended and left to stand for 70,000 seconds in a 40°C environment to measure the holding force (the time until the adhesive sheet peels off the stainless steel plate, or the distance shifted after 70,000 seconds if it does not peel off). Except for the measurement conditions described above, the method follows JIS Z0237:2009.
[0048] In one embodiment, the interlayer adhesion between the adhesive layer 110 and the adhesive layer 120 is high. Due to the high interlayer adhesion between the adhesive layer 110 and the adhesive layer 120, the adhesive layer 110 expands easily to follow the expansion of the portion of the adhesive layer 120 covered by the adhesive layer 110. In this specification, adhesion is measured according to the cross-cut adhesion test (JIS K5600-5-6:1999). That is, a grid pattern of cuts at 2 mm intervals is made in the adhesive layer 110, and peeling is checked when cellophane tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") is applied and peeled off. The test results are classified as follows. The adhesion test result between the adhesive layer 110 and the adhesive layer 120 is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0. 0: The edges of the cuts are perfectly smooth, and there is no peeling at any of the grid lines. 1: Small peeling of the coating at the intersections of the cuts. 1: The area affected in the cross-cut is clearly no more than 5%. 2: The paint is peeling along the edges of the cut and / or at the intersections. The area affected in the cross-cut is clearly more than 5% but not more than 15%. 3: The paint is partially or completely peeling along the edges of the cut and / or peeling in various parts of the eye. The area affected in the cross-cut is clearly more than 15% but not more than 35%. 4: The paint is partially or completely peeling along the edges of the cut and / or peeling in several places of the eye. The area affected in the cross-cut is clearly no more than 35%. 5: Any degree of peeling that cannot be classified in category 4.
[0049] In one embodiment, the interlayer adhesion between the adhesive layer 110 and the adhesive layer 120 is configured such that when the adhesive sheet 100 is expanded by 10% or more by supporting the flat portion 115 of the adhesive layer 120, the adhesive layer 110 expands in accordance with the adhesive layer 120. With this configuration, the adhesive layer 110 can be expanded by expanding the adhesive layer 120 while supporting the adhesive layer 120 with a fixing member. In one embodiment, when the adhesive sheet 100 is expanded by 10% or more, preferably 20% or more, and more preferably 30% or more in one direction by supporting the flat portion 115 of the adhesive layer 120, no delamination occurs between the adhesive layer 110 and the adhesive layer 120.
[0050] The interlayer adhesion between the adhesive layer 110 and the adhesive layer 120 described above can be improved by using a material with high adhesive strength as the material for the adhesive layer 120. Examples of such materials for the adhesive layer 120 include acrylic resins such as the acrylic ester copolymer described above. On the other hand, the material for the adhesive layer 110 can be selected to obtain an appropriate holding force for the object. From this viewpoint, the material for the adhesive layer 110 may be a urethane resin. Furthermore, the adhesive layer 110 may be energy-ray reactive. If the adhesive layer 110 is energy-ray reactive, irradiating the adhesive layer 110 to which the object is attached with energy rays will reduce the holding force of the object by the adhesive layer 110. Therefore, it becomes easy to peel off the object without damage. As an example of such a material for the adhesive layer 110, the energy-ray reactive acrylic ester copolymer described above can be used.
[0051] In one embodiment, the adhesive layer 110 and the adhesive layer 120 each have a uniform composition. On the other hand, the materials constituting each part of the adhesive layer 110 or the adhesive layer 120 may be different. For example, the flat portion 115 of the adhesive layer 120 and the portion of the adhesive layer 120 covered by the adhesive layer 110 may be formed of different materials.
[0052] In one embodiment, the elastic modulus of the flat portion 115 of the adhesive layer 120 is lower than the elastic modulus of the portion of the adhesive layer 120 covered by the adhesive layer 110. For example, the tensile elastic modulus of the flat portion 115 of the adhesive layer 120 may be lower than the tensile elastic modulus of the portion of the adhesive layer 120 covered by the adhesive layer 110. With such a configuration, the fixing force to the fixing member at the flat portion 115 of the adhesive layer 120 can be increased, while the adhesive layer 110 can easily expand in response to the expansion of the portion of the adhesive layer 120 covered by the adhesive layer 110. Such an adhesive layer 120 can be produced by forming an adhesive layer having the energy ray reactivity described above, and then irradiating the central portion of the adhesive layer with energy rays while shielding the peripheral portion. This central portion corresponds to the portion that is to be covered by the adhesive layer 110, or the portion that is already covered by the adhesive layer 110. Thus, in one embodiment, the material of the portion of the adhesive layer 120 covered by the adhesive layer 110 is the material of the flat portion 115 of the adhesive layer 120, which has been further crosslinked. In one embodiment, the gel fraction of the portion of the adhesive layer 120 covered by the adhesive layer 110 is higher than the gel fraction of the flat portion 115 of the adhesive layer 120. Examples of materials for such an adhesive layer 120 include energy-ray reactive acrylic ester copolymers.
[0053] In one embodiment, the cohesive force at the flat portion 115 of the adhesive layer 120 is greater than the cohesive force at the portion of the adhesive layer 120 covered by the adhesive layer 110. For example, the cohesive force at the flat portion 115 of the adhesive layer 120 may be greater than the cohesive force at the portion of the adhesive layer 120 covered by the adhesive layer 110. With such a configuration, the fixing force at the flat portion 115 of the adhesive layer 120 to the fixing member can be increased, and even when the adhesive sheet 100 is expanded, it is possible to suppress the adhesive sheet 100 from slipping off the fixing member.
[0054] In one embodiment, a crosslinking agent is used as the material for the flat portion 115 of such an adhesive layer 120. For example, by adding a crosslinking agent to the material for the flat portion 115, the cohesive force of the flat portion 115 can be increased. In another embodiment, an energy-ray reactive acrylic ester copolymer is used as the material for the flat portion 115 of such an adhesive layer 120. In this case, the cohesive force of the flat portion 115 can be increased by irradiation with energy rays.
[0055] (Base material) The base material 130 functions as a support for the adhesive layers 110 and 120. The base material 130 is located on the side of the adhesive layer 120 opposite to the adhesive layer 110. The base material 130 may have the same planar shape as the adhesive layer 120. On the other hand, the base material 130 may be larger than the adhesive layer 120.
[0056] In one embodiment, the adhesive sheet 100 is expandable in the planar direction. From this viewpoint, a flexible substrate can be used as the base material 130. Furthermore, by using a flexible substrate as the base material 130, 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 130, 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.
[0057] 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 130 may be a laminated film in which two or more resin films are laminated.
[0058] From the viewpoint of facilitating the expansion of the adhesive sheet, the base material 130 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.
[0059] The thickness of the base material 130 is not particularly limited, but from the viewpoint of achieving both support and roll winding properties, it is preferably 10 μm or more, more preferably 25 μm or more, even more preferably 40 μm or more, on the other hand, it is preferably 500 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, even more preferably 120 μm or less, and particularly preferably 90 μm or less.
[0060] To facilitate the uniform expansion of the adhesive sheet, the tensile modulus of the base material 130 is preferably 50 MPa or more, more preferably 80 MPa or more, even more preferably 120 MPa or more, preferably 2500 MPa or less, more preferably 1000 MPa or less, and even more preferably 500 MPa or less. In this specification, the tensile modulus is measured in accordance with JIS K7161-1:2014.
[0061] Similarly, to facilitate the expansion of the adhesive sheet, the elongation at break of the base material 130 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.
[0062] (Release layer) The adhesive sheet according to this embodiment may also have a release sheet 150 in contact with the adhesive surface 111, as shown in Figure 1A. For illustrative purposes, Figure 1A shows a state in which the adhesive surface 111 and the release sheet 150 are separated.
[0063] As shown in Figure 1A, the release sheet 150 can have a shape complementary to at least a portion of the adhesive surface 111 of the adhesive layer 110. For example, the surface of the release sheet 150 can have an uneven surface complementary to the uneven portion 112. However, it is not essential that the release sheet 150 has a shape complementary to the adhesive surface 111. For example, the surface of the release sheet 150 may be flat.
[0064] 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. In the example in Figure 1A, the release layer 160 has a recess having a shape complementary to the convex portion 113 of the uneven portion 112, and a convex portion having a shape complementary to the recess 114 of the uneven portion 112. As shown in Figure 1A, the entire release sheet 150 may also have an uneven surface. That is, the surface of the release sheet 150 that is in contact with the flat adhesive layer 120 may have an uneven surface.
[0065] 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 130, but it does not need to have the same composition or structure as the base material 130. The surface of the base material 170 on the side facing the release layer 160 may have an uneven surface. For example, the uneven surface of the release sheet 150 may be formed by the uneven surface of the base material 170 and a thin release layer 160 provided on this uneven surface along the unevenness. The release sheet 150 may also have an undercoat layer (not shown) between the release layer 160 and the base material 170.
[0066] (Other layers) The adhesive sheet 100 may have layers other than the base material 130, the adhesive layer 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 130 opposite to the adhesive layer 120. 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.
[0067] (Method for manufacturing adhesive sheet) There are no particular restrictions on the method for manufacturing the adhesive sheet 100. Below, an example of a method for manufacturing the adhesive sheet 100 will be described with reference to Figure 4.
[0068] In step S410, an adhesive composition to be used as the material for the adhesive layer 110 and an adhesive composition to be used as the material for the adhesive layer 120 are prepared. The adhesive composition can be prepared by adding an organic solvent to the raw material composition containing the components of the adhesive layer 110 or the adhesive layer 120 as described above.
[0069] Examples of organic solvents used to prepare adhesive compositions include toluene, ethyl acetate, and methyl ethyl ketone. Methods for applying the solution include, for example, 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).
[0070] In S420, an adhesive layer 110 is prepared in which an uneven surface 112 is formed on the first surface. In S420, the adhesive layer 110 can be formed using the adhesive composition prepared in S410. There are no particular restrictions on the process of creating the uneven surface. For example, the surface of the layer can be created using an imprint method. In the imprint method, a mold having an uneven surface complementary to the uneven surface to be created can be used. Specifically, the layer of the adhesive composition can be pressed with a mold, the layer can be heated and maintained for a predetermined time, and then the material layer can be cooled. Such a layer of adhesive composition can be made by applying the adhesive composition to a mold to form a coating film, and then drying it. In this way, an adhesive layer 110 having an uneven surface 112 can be formed. When heating, for example, the material layer can be heated to a temperature higher than the softening point of the layer of adhesive composition. A specific method for heating the material layer while pressing the layer with a mold is to vacuum laminate the layer of adhesive composition and the mold. A release sheet 150 may be used as a mold. In this case, an adhesive layer 110 having an uneven portion 112 at the interface between the adhesive layer 110 and the release sheet 150 can be provided on the release sheet 150.
[0071] On the other hand, in order to improve the maintenance of the uneven shape, a crosslinking reaction may be performed on the resin contained in the adhesive composition when forming the unevenness on the surface of the layer of the adhesive composition or after the unevenness has been formed. For example, in one embodiment in which the adhesive composition contains an acrylic ester copolymer having monomers that can react with a crosslinking agent, the monomers can be crosslinked with each other by reacting the acrylic ester copolymer with a crosslinking agent. By proceeding with the curing reaction in the layer of the adhesive composition in this way, the storage modulus of the adhesive layer 110 can be increased, and the maintenance of the uneven shape can be improved. As a specific example, an adhesive layer 110 having an uneven surface can be formed by curing the layer of the adhesive composition while a mold having an uneven surface complementary to the unevenness is in contact with the layer of the adhesive composition. When the layer of the adhesive composition contains a copolymer before crosslinking and a thermal crosslinking agent, the crosslinking reaction proceeds by heating the material layer while pressing it with a mold, and an adhesive layer 110 containing the crosslinked copolymer is formed. By using a crosslinking reaction by heating in this way, unreacted energy ray curable groups can be left in the adhesive layer 110.
[0072] Alternatively, the uneven surfaces 112 can be created by spray-applying the adhesive composition. Furthermore, the uneven surfaces 112 having a rough or fibrous surface can be created by adding a filler to the adhesive composition and applying such a solution. Yet another method is to create the adhesive layer 110 by applying the adhesive composition according to a desired pattern using a printing method such as an inkjet method.
[0073] In step S430, the adhesive layer 120 and the base material 130 are laminated onto the second surface of the adhesive layer 110 such that the adhesive layer 120 has an adhesive surface with a flat portion 115 in its peripheral area that is not covered by the adhesive layer 110. For example, an adhesive layer 120 larger than the adhesive layer 110 can be laminated onto the adhesive layer 110 or onto a release sheet 150 on which the adhesive layer 110 is provided. In this case, the laminate obtained by laminating the adhesive layer 120 onto the base material 130 may be attached to the adhesive layer 110. The lamination of the adhesive layer 120 onto the base material 130 can be performed by forming a coating film on the base material 130 using an adhesive composition that will be the material for the adhesive layer 120, and then drying it. In this way, an adhesive sheet 100 can be manufactured which has a laminate comprising the base material 130, the adhesive layer 120, the adhesive layer 110, and, if necessary, a release sheet 150, in this order. The adhesive sheet 100 may be further cut to have a desired shape. This manufacturing method makes it easy to control the positional relationship between the adhesive layer 110 and the adhesive layer 120.
[0074] Alternatively, a layer of adhesive composition may be laminated onto a laminate obtained by laminating the adhesive layer 120 onto the substrate 130. Then, by creating irregularities on the surface of the layer of adhesive composition, an adhesive layer 110 can be formed.
[0075] (Method of using the adhesive sheet) The adhesive sheets according to each of the above embodiments can be used to handle objects. For example, the adhesive sheet according to one embodiment can be used to temporarily hold an object. Also, the adhesive sheet according to one embodiment can be used to transfer an object. 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.
[0076] A method for handling an object using an adhesive sheet according to one embodiment will be explained with reference to the flowchart in Figure 5.
[0077] (S510: Attachment to frame) In S510, the flat surface of the adhesive sheet is attached to the frame. For example, as shown in Figure 3A, the flat portion 115, i.e., the adhesive layer 120, can be attached to the frame 320. Since the adhesive layer 120 is adhesive, in one embodiment, no additional adhesive is used to attach the adhesive layer 120 to the frame 320. Also, the frame 320 does not need to have a structure that clamps the flat portion 115. In one embodiment, the fixing of the adhesive sheet 100 by the frame 320 is achieved solely by the adhesive force between the adhesive layer 120 and the frame 320.
[0078] The shape of the frame 320 is not particularly limited. For example, the frame 320 may be a circular, substantially circular, or rectangular frame-shaped member having an opening. In one embodiment, a circular ring frame is used as the frame 320. By using a ring frame, the adhesive sheet 100 can be expanded in all directions. Alternatively, two or more separate fixing members may be used instead of a frame. The adhesive sheet 100 can be expanded by attaching the adhesive layer 120 to each fixing member and pulling the fixing members away from each other.
[0079] (S520: Holding the object) In S520, the object is held on the adhesive surface of the adhesive sheet. The type of 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 protective films, and semiconductor chips with die attach films (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 a pieced material such as a wafer, panel, or substrate. The element may have a circuit surface on which an integrated circuit having circuit objects such as transistors, resistors, and capacitors is formed. Furthermore, the element is not necessarily limited to a pieced material, and may be various wafers or various substrates that have not been pieced.
[0080] In addition, the size of the object is not particularly limited. For example, the size of the object is preferably 100 μm ２ or more, more preferably 10000 μm ２ or more, still more preferably 1000000 μm ２ or more (1 mm ２ or more), still more preferably 25 mm ２ or more, particularly preferably 50 mm ２ or more. On the other hand, the size of the object is preferably 5000 mm ２ or less, more preferably 2000 mm ２ or less, still more preferably 1000 mm ２ or less, still more preferably 500 mm ２ or less, particularly preferably 200 mm ２ or less. The thickness of the object is also not particularly limited. For example, the thickness of the object is preferably 1 μm or more, more preferably 5 μm or more. On the other hand, the thickness of the object is preferably 1 cm or less, more preferably 1 mm or less, still more preferably 100 μm or less.
[0081] 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 (about 150 mm in diameter) or more, more preferably 12 inches (about 300 mm in diameter) or more. The shape of the wafer is not limited to a circular shape, and may be, for example, a rectangular shape such as a square or a rectangle.
[0082] 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 singulation in a fan-out type semiconductor package manufacturing technology. The size of the panel is not particularly limited, and it may be, for example, a square-shaped substrate of about 300 to 700 mm.
[0083] Examples of the substrate include glass substrates, sapphire substrates, and compound semiconductor substrates.
[0084] In one embodiment, elements are transferred from a holding substrate to an adhesive sheet, and the adhesive sheet holds the transferred elements. For example, a semiconductor wafer can be attached to a wafer substrate, and then the semiconductor wafer can be diced. The elements on the wafer substrate obtained by dicing can then be brought into close contact with the adhesive layer 110 of the adhesive sheet. Subsequently, the adhesion between the wafer substrate and the elements can be reduced by applying an external stimulus such as laser light. Through such a process, elements can be transferred from the wafer substrate to the adhesive sheet. Alternatively, elements obtained by dicing a semiconductor wafer can be transferred to a holding substrate to obtain a holding substrate to which elements are attached. The elements attached to the holding substrate can then be transferred to the adhesive layer 110 of the adhesive sheet in the same manner.
[0085] In another embodiment, an element attached to a holding substrate may be separated from the holding substrate by an external stimulus. Specifically, the element moves away from the holding substrate relative to it, and also moves closer 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. The type of external stimulus is not particularly limited, but examples include energy application, cooling, expansion of the holding substrate, and physical stimulus (e.g., pressing on the back surface of the holding substrate using a pin, etc.). By using one or more of these external stimuli, the bonding force between the holding substrate and the element can be reduced, and the element can be separated from the holding substrate. For example, the element can be separated from the holding substrate by irradiation with laser light (laser lift-off method). In such an embodiment, when the separated element approaches the adhesive layer 110, pressure is generated between the element and the adhesive layer 110. However, because the adhesive layer 110 has an uneven portion 112, the pressure generated between the element and the adhesive layer 110 is mitigated, making it easier to capture the element at a desired position on the adhesive sheet.
[0086] In further embodiments, processing can be performed on an object held on the adhesive layer 110 of the adhesive sheet. The processing method is not particularly limited. For example, processing such as wiring formation, back metal formation, cleaning, plating, pulverization, thinning, and sealing can be performed. For example, a semiconductor wafer may be attached to the adhesive layer 110 of the adhesive sheet. Then, an element can be formed by dicing the semiconductor wafer on the adhesive layer 110. Such processing can also be performed with the adhesive sheet fixed to the frame. The adhesive sheet can hold the element by this method as well.
[0087] Note that S520 may be performed before S510. That is, the adhesive sheet to which the object is attached may be attached to the frame.
[0088] (S530: Expansion of the adhesive sheet) In S530, the adhesive sheet to which the object is attached is expanded. In this example, the adhesive sheet, which is supported by a frame attached to the flat part of the adhesive sheet, is expanded in the planar direction. As described above, the expansion of the adhesive sheet reduces the holding force of the object by the uneven parts of the adhesive sheet.
[0089] The method of expanding the adhesive sheet is not particularly limited. For example, the expansion of the adhesive sheet may be carried out in one direction, two directions, or multiple directions. The expansion rate of the adhesive sheet is also not particularly limited. For example, the expansion rate of the adhesive sheet in one direction is preferably 1% to 50%, and more preferably 5% to 20%. 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 rate of the adhesive sheet in two mutually orthogonal directions is preferably 1% to 50%, and more preferably 5% to 20%.
[0090] An example of a method for extending the adhesive sheet will be further explained with reference to Figures 3A and 3B. Figure 3A shows the state in which the adhesive sheet 100 is holding objects 300a to 300d. As shown in Figure 3A, the flat portion 115, i.e., the adhesive layer 120, is attached to the frame 320.
[0091] Then, by bringing the adhesive sheet 100 fixed to the frame 320 into contact with the base 310, and further displacing (pulling down) the frame 320 toward the base 310 as shown in Figure 3B, the adhesive sheet 100 can be expanded. The structure 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 frame 320 may be displaced relative to the base 310 at a speed of, for example, 0.1 mm / sec or more, or at a speed of 1 mm / sec or more. In this case, the amount of displacement of the frame 320 is preferably 1 mm to 30 mm, and more preferably 5 mm to 20 mm. By increasing the amount of displacement, the holding force of the object can be sufficiently reduced. By decreasing the amount of displacement, damage to the adhesive sheet can be suppressed.
[0092] Furthermore, in order to reduce the object-holding force due to the uneven surface of the adhesive sheet, the adhesive layer 110 may be irradiated with energy rays. By irradiating an energy-ray-reactive adhesive layer with energy rays, the storage modulus of the adhesive layer increases, and the adhesive force decreases. In this case, the flat portion 115 may be shielded from the energy rays.
[0093] The amount of energy rays applied during the processing step can be set according to the type of adhesive layer 110 and the desired adhesive strength. For example, when irradiating with ultraviolet light, the amount of ultraviolet light is set to 20 mJ / cm² from the viewpoint of sufficiently reducing the adhesive strength. ２ Preferably, it is 100 mJ / cm² or higher. ２ It is more preferable that the above conditions are met. Furthermore, the amount of ultraviolet light should be 1000 mJ / cm² from the viewpoint of shortening the processing time. ２ Preferably, it is 500 mJ / cm². ２ The following is more preferable:
[0094] (S540: Detachment of object) After expanding the adhesive sheet, in S540, the object is detached from the adhesive surface of the adhesive sheet. The method of detaching the object is not particularly limited. For example, the method described above can be used as a method for transferring an object attached to a holding substrate to the adhesive sheet. As an example, an adsorption member such as a vacuum collet can be used to detach the object from the adhesive surface of the adhesive sheet. The adsorbed object can then be moved to a desired position on the transfer destination. By reducing the holding force of the object by the adhesive surface as in this embodiment, the object can be detached from the adhesive surface of the adhesive sheet without applying physical stimulation such as pressing with a pin from the opposite side of the adhesive surface of the adhesive sheet. In this embodiment, by using a process to reduce the adhesive force, it is possible to achieve both a high holding force of the adhesive surface when holding an object to the adhesive sheet and a low holding force of the adhesive surface when detaching an object from the adhesive sheet. From this viewpoint, the handling method and adhesive sheet of this embodiment are particularly 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.
[0095] By following the procedure described above, an object can be transferred to any destination using an adhesive sheet. Another embodiment of the present invention relates to a method for peeling an object from an adhesive sheet that is holding the object on its adhesive surface. Such a peeling method may include a step of expanding the adhesive sheet, as in S530, and a step of peeling off the object, as in S540.
[0096] Furthermore, such a peeling method can be used to manufacture electronic components or semiconductor devices having elements. For example, a method for manufacturing an article according to one embodiment of the present invention may include a step of manufacturing an article by performing post-treatment on the object in addition to a step of peeling the object from the adhesive sheet according to the above peeling method. The type of post-treatment is not particularly limited. For example, treatments such as wiring formation, back metal formation, cleaning, plating, individualization, thinning, and sealing can be performed.
[0097] 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.
[0098] This application claims priority based on Japanese Patent Application No. 2025-055511, filed on 28 March 2025, and all of its contents are incorporated herein by reference.
[0099] 100: Adhesive sheet, 110: Adhesive layer, 112: Uneven part, 115: Flat part, 120: Adhesive layer, 130: Base material
Claims
1. An adhesive sheet comprising a laminate having a base material, a second adhesive layer, and a first adhesive layer in this order, wherein the first adhesive layer covers a part of the second adhesive layer, the adhesive surface of the first adhesive layer has an uneven portion, and the second adhesive layer has an adhesive surface in its peripheral portion that has a flat portion not covered by the first adhesive layer.
2. The adhesive sheet according to claim 1, wherein the uneven portion of the first adhesive layer is surrounded by the flat portion of the second adhesive layer.
3. The adhesive sheet according to claim 1, wherein the material of the first adhesive layer and the material of the second adhesive layer are the same.
4. The adhesive sheet according to claim 1, wherein the material of the first adhesive layer and the material of the second adhesive layer are different.
5. The adhesive sheet according to claim 1, wherein the adhesive strength of the second adhesive layer is higher than the adhesive strength of the first adhesive layer.
6. The adhesive sheet according to claim 1, wherein the tensile modulus of the flat portion of the second adhesive layer is lower than the tensile modulus of the portion of the second adhesive layer covered by the first adhesive layer.
7. The adhesive sheet according to claim 1, wherein the interlayer adhesion between the first adhesive layer and the second adhesive layer, as evaluated by the cross-cut method in accordance with JIS K5600-5-6:1999, is 0, 1, or 2.
8. The adhesive sheet according to claim 1, wherein the adhesive sheet is expandable by 10% or more in one direction, and the adhesive force between the first adhesive layer and the second adhesive layer is configured such that when the adhesive sheet is expanded by 10% or more by supporting the flat portion of the second adhesive layer, the first adhesive layer expands in accordance with the expansion of the second adhesive layer.
9. The adhesive sheet according to claim 1, wherein the flat portion is provided along at least a part of the outer edge of the second adhesive layer and has a width of 5 mm or more.
10. The adhesive sheet according to claim 1, wherein the uneven portion is provided with a plurality of protrusions, and the height of the plurality of protrusions is uniform.
11. The adhesive sheet according to claim 1, wherein the uneven portion is provided with a plurality of protrusions, and the height of each of the plurality of protrusions is 1 μm or more.
12. The adhesive sheet according to claim 1, wherein the uneven portion is provided with a plurality of protrusions, and the pitch of the plurality of protrusions is 1 μm or more and 100 μm or less.
13. A method for peeling an object attached to the uneven portion of an adhesive sheet according to any one of claims 1 to 12, comprising: an expansion step of expanding the adhesive sheet, which is supported by a frame attached to the flat portion of the adhesive sheet, in the planar direction; and a peeling step of peeling the object from the adhesive surface of the adhesive sheet.
14. A method for manufacturing an adhesive sheet comprising a laminate having a base material, a second adhesive layer, and a first adhesive layer in this order, the method comprising: preparing the first adhesive layer having an uneven surface formed on the first surface; and laminating the second adhesive layer and the base material on the second surface of the first adhesive layer such that the second adhesive layer has an adhesive surface with a flat portion in its peripheral area that is not covered by the first adhesive layer.