Electronic component equipped with adhesive sheet, and transfer sheet

Abstract

This electronic component equipped with an adhesive sheet includes: an adhesive sheet having a base material layer and an ultraviolet-curable adhesive layer provided on the base material layer; and an electronic component provided on the ultraviolet-curable adhesive layer of the adhesive sheet. A surface of the electronic component that is in contact with the ultraviolet-curable adhesive layer has an insulating region and a conductor region. The ultraviolet-curable adhesive layer is a thermally cured product of an adhesive composition. The adhesive composition comprises a (meth)acrylic resin (A) containing structural units represented by formulae (2) and (3). In formula (2), R3 represents a hydrogen atom or a methyl group, and R4 represents a group that has a hydroxy group on a carbon atom and that has, on a carbon atom adjacent to said carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid. In formula (3), R5 represents a hydrogen atom or a methyl group, and R6 represents a group that has, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxyl group of an unsaturated monocarboxylic acid and that has, on a carbon atom adjacent to said carbon atom, a residue obtained by removing a hydrogen atom from a carboxyl group of an unsaturated monocarboxylic acid.

Description

Electronic parts with adhesive sheets and transfer sheets

[0001] The present disclosure relates to an electronic component with an adhesive sheet and a transfer sheet.

[0002] BACKGROUND ART Conventionally, as a wiring board used for mounting electronic components such as semiconductor elements, a wiring board has been known which is formed by alternately laminating insulating layers formed by thermally curing insulating sheets in which a heat-resistant fiber base material such as glass cloth is impregnated with a thermosetting resin composition and wiring conductors formed of metal foil such as copper foil, and electrically connecting the wiring conductors located above and below the insulating layer with each other via through conductors formed by curing a conductive paste filled in through holes formed in the insulating layer.

[0003] For example, Patent Document 1 describes a method for manufacturing a wiring board, which includes the steps of: placing a transfer sheet, which has a wiring conductor made of metal foil releasably held on an adhesive layer adhered to one main surface of a transfer base film, on a main surface of an insulating sheet containing an uncured thermosetting resin composition so that the wiring conductor is in contact with the main surface of the insulating sheet; pressing the transfer sheet against the insulating sheet at a predetermined temperature to embed the wiring conductor in the main surface of the insulating sheet; and peeling the transfer base film together with the adhesive layer from the main surface of the insulating sheet to transfer the wiring conductor to the main surface of the insulating sheet.

[0004] JP 2010-129910 A

[0005] The transfer sheet is required to have the following performance: when the transfer substrate film is peeled off from the adherend together with the adhesive layer, the adhesive layer must be removable without remaining on the adherend.

[0006] In recent years, with the miniaturization of wiring patterns, pressure-sensitive adhesive layers are being required to have both higher levels of adhesive strength and releasability, and to prevent the pressure-sensitive adhesive layer from being transferred to an adherend, etc. In particular, a surface containing an insulating material such as a resin and an area containing a conductive material such as a wiring conductor may behave differently toward the pressure-sensitive adhesive, and there is a strong demand for a pressure-sensitive adhesive layer that exhibits excellent properties in terms of adhesive strength, releasability, and transfer prevention for surfaces where areas with different adhesive properties coexist.

[0007] Sheets having a pressure-sensitive adhesive layer are also used in processes where both adhesive strength and releasability are required, such as in tapes used in processing electronic components such as semiconductor elements.

[0008] The present disclosure provides an electronic component with an adhesive sheet, the electronic component having an adhesive sheet attached with excellent adhesive strength to the surface of an adherend having an insulating region and a conductive region, and which can be peeled off after the adhesive sheet is no longer needed without leaving any adhesive residue on the electronic component.The present disclosure also provides a transfer sheet having an adhesive layer that has excellent adhesive strength sufficient to hold a conductor layer when forming a wiring conductor, and that can be peeled off after transferring the wiring conductor to the adherend without being transferred to the adherend.

[0009] The present disclosure includes the following aspects: [1] An electronic component with a pressure-sensitive adhesive sheet, comprising: a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer; and an electronic component provided on the ultraviolet-curable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, wherein a surface of the electronic component in contact with the ultraviolet-curable pressure-sensitive adhesive layer has an insulating region and a conductive region, the ultraviolet-curable pressure-sensitive adhesive layer is a thermoset product of a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition contains a (meth)acrylic resin (A) containing structural units of the following formulae (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.) [2] A transfer sheet comprising: a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer; and a wiring conductor partially provided on the ultraviolet-curable pressure-sensitive adhesive layer, wherein the ultraviolet-curable pressure-sensitive adhesive layer is a heat-cured product of a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition comprises a (meth)acrylic resin (A) containing structural units of the following formulas (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.) [3] A sheet with a conductor layer for a transfer sheet, comprising: a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer; and a conductor layer provided on the ultraviolet-curable pressure-sensitive adhesive layer, wherein the ultraviolet-curable pressure-sensitive adhesive layer is a thermoset product of a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition contains a (meth)acrylic resin (A) containing structural units of the following formulae (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８represents a group containing an epoxy group.) [4] The electronic component with a pressure-sensitive adhesive sheet, the transfer sheet, or the conductor layer-attached sheet for a transfer sheet according to any one of [1] to [3], wherein the thickness of the base layer is 5 to 500 μm, and the thickness of the ultraviolet-curable pressure-sensitive adhesive layer is 1 to 300 μm. [5] The transfer sheet or the conductor layer-attached sheet for a transfer sheet according to [2] or [3], wherein the thickness of the wiring conductor or the conductor layer is 0.5 to 100 μm, and is in the range of 0.01 to 1.20 times the thickness of the ultraviolet-curable pressure-sensitive adhesive layer. [6] The electronic component with a pressure-sensitive adhesive sheet, the transfer sheet, or the conductor layer-attached sheet for a transfer sheet according to any one of [1] to [5], wherein the pressure-sensitive adhesive composition contains: the (meth)acrylic resin (A), a photopolymerization initiator (B), and a crosslinking agent (C). [7] A method for producing a conductor layer-equipped sheet for a transfer sheet according to any one of [3] to [6], comprising the steps of: providing a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer; and providing a conductor layer on the exposed surface of the ultraviolet-curable pressure-sensitive adhesive layer. [8] A method for producing a transfer sheet, comprising the steps of: providing a resist layer on the exposed surface of the conductor layer of the conductor layer-equipped sheet for a transfer sheet according to any one of [3] to [6], exposing the resist layer through a photomask, and developing it with a developer to form a resist layer patterning step; etching the exposed region of the conductor layer formed in the patterning step to remove by etching, thereby forming a wiring conductor; and removing the resist layer on the wiring conductor formed in the etching step. [9] A method for producing a wiring board, comprising the step of bringing the surface of the transfer sheet according to any one of [2] and [4] to [6], on which the wiring conductor is provided, into contact with an insulating sheet, and transferring the wiring conductor to the insulating sheet.

[10] A method for manufacturing a wiring board, comprising providing a sealing layer on the surface of the transfer sheet according to any one of [2] and [4] to [6], on which the wiring conductor is provided.

[11] The method for manufacturing a wiring board according to

[10] , comprising providing a conductive path that penetrates the sealing layer so that a part of the wiring conductor is connected to the conductive path.

[12] A method for producing an electronic device, comprising: a preparation step of preparing a substrate having an insulating region and a conductive region on its surface; an attachment step of attaching, to the surface of the substrate, an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer; a processing step of processing the substrate to which the adhesive sheet has been attached; an ultraviolet-irradiation step of irradiating the adhesive sheet with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer; and a peeling step of peeling the adhesive sheet from the substrate, wherein the ultraviolet-curable adhesive layer is a thermoset product of an adhesive composition, and the adhesive composition contains a (meth)acrylic resin (A) containing structural units of the following formulae (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.

[0010] According to the present disclosure, it is possible to provide an electronic component with an adhesive sheet, which has an adhesive sheet attached with excellent adhesive strength to the surface of an adherend having an insulating region and a conductive region, and which can be peeled off without leaving any adhesive on the electronic component after the adhesive sheet is no longer needed. Furthermore, according to the present disclosure, it is possible to provide a transfer sheet having an adhesive layer that has excellent adhesive strength sufficient to hold a conductor layer when forming a wiring conductor, and that can be peeled off without being transferred to the adherend after transferring the wiring conductor to the adherend.

[0011] FIG. 1 is a schematic diagram illustrating an exemplary method for manufacturing a fan-out type package; FIG. 2 is a schematic diagram illustrating an electronic device according to an embodiment; FIG. 3 is a schematic diagram illustrating an exemplary method for manufacturing an electronic device according to an embodiment; FIG. 4 is a schematic diagram illustrating an exemplary method for manufacturing an electronic device according to an embodiment;

[0012] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

[0013] In this specification, when "to" is used to describe a numerical range, the numerical values ​​at both ends are the upper and lower limits, respectively, and are included in the numerical range. When multiple upper or lower limits are listed, numerical ranges can be created using all combinations of the upper and lower limits. Similarly, when multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining the upper and lower limits from those numerical ranges.

[0014] In this specification, (meth)acrylic means "acrylic" or "methacrylic", (meth)acrylate means "acrylate" or "methacrylate", and (meth)acryloyloxy means "acryloyloxy" or "methacryloyloxy".

[0015] <Electronic Component with Adhesive Sheet> An electronic component with an adhesive sheet according to one embodiment includes an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer, and an electronic component provided on the ultraviolet-curable adhesive layer of the adhesive sheet. By using an electronic component with an adhesive sheet as an intermediate, a product with little adhesive residue from the adhesive layer can be obtained.

[0016] <Electronic Component> An electronic component in one embodiment has an insulating region and a conductive region on the adhesion surface of the pressure-sensitive adhesive sheet. The insulating region is a region formed of an electrical insulator such as resin. The conductive region is a region formed of an electrical conductor such as metal. The pressure-sensitive adhesive sheet has excellent adhesive strength to multiple regions containing different materials, i.e., insulating regions and conductive regions, and can be peeled off without leaving any adhesive residue in either region after ultraviolet irradiation, so it is preferably used for electronic components having insulating regions and conductive regions. The pressure-sensitive adhesive sheet is attached to the adhesion surface of the electronic component as a protective tape for the adhesion surface of the electronic component or as a temporary fixing tape for the electronic component in the processing process of the electronic component. Specifically, the pressure-sensitive adhesive sheet is used in, for example, a backgrinding process for semiconductor wafers, fan-out type packaging (FO-WLP: Fan-Out Wafer level Package), 2. The electronic component can be used in a semiconductor chip sealing process and a semiconductor element assembly dicing process when manufacturing an xD SiP or the like, as well as in a mounting process for mounting semiconductor elements, electronic elements, etc. on a substrate such as an interposer. Examples of electronic components include semiconductor wafers, semiconductor chips, semiconductor element assembly, semiconductor elements, electronic elements, and substrates.

[0017] The adhesive strength of a pressure-sensitive adhesive sheet can be reduced by ultraviolet (also referred to as UV) irradiation. UV irradiation of a pressure-sensitive adhesive sheet can be carried out, for example, as follows: UV is irradiated onto the pressure-sensitive adhesive sheet attached to the adherend surface. As a result, the UV is irradiated onto the UV-curable pressure-sensitive adhesive layer through the substrate of the pressure-sensitive adhesive sheet, and the unsaturated bonds in the pressure-sensitive adhesive layer form a three-dimensional crosslinked structure and harden. As a result, the adhesive strength of the pressure-sensitive adhesive layer is reduced. Note that if the adherend is optically transparent, UV may be irradiated from the adherend side toward the pressure-sensitive adhesive sheet.

[0018] Examples of light sources used for UV irradiation include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, chemical lamps, and black lights.

[0019] The UV irradiation dose applied to the adhesive sheet is 50 to 3,000 mJ / cm ２ is preferably 100 to 600 mJ / cm ２ It is more preferable that the UV irradiation dose applied to the pressure-sensitive adhesive sheet is 50 mJ / cm. ２ When the UV irradiation dose is 3,000 mJ / cm or more, the ultraviolet-curable pressure-sensitive adhesive layer can be cured at a sufficiently high curing rate by UV irradiation, and the adhesive strength of the pressure-sensitive adhesive layer after UV irradiation can be sufficiently reduced. ２ Even if the UV irradiation dose is increased to 3,000 mJ / cm, the effect is not commensurate with the increase. ２ By setting the temperature as follows, the pressure-sensitive adhesive sheet can be economically peeled off while reducing the effect of UV irradiation on the adherend.

[0020] In one embodiment, a method for manufacturing a semiconductor device includes the steps of: preparing a semiconductor wafer having an insulating region and a conductive region on its surface; attaching an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer to the surface of the semiconductor wafer; processing the semiconductor wafer with the adhesive sheet attached; irradiating the adhesive sheet with ultraviolet light to photocure the ultraviolet-curable adhesive layer; and peeling the adhesive sheet from the semiconductor wafer. In this embodiment, the processing step can be, for example, a back-grinding step.

[0021] In one embodiment, a method for manufacturing a semiconductor element includes a preparation step of preparing a semiconductor chip having an insulating region and a conductive region on its surface; an attachment step of attaching an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer to the surface of the semiconductor chip; a sealing step of sealing the semiconductor chip with the adhesive sheet attached; an ultraviolet irradiation step of irradiating the adhesive sheet with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer; and a peeling step of peeling the adhesive sheet from the semiconductor chip.

[0022] In one embodiment, a method for manufacturing a semiconductor element includes a preparation step of preparing a semiconductor element assembly having an insulating region and a conductive region on its surface; an attachment step of attaching an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer to the surface of the semiconductor element assembly; a dicing step of dicing the semiconductor element assembly with the adhesive sheet attached to separate it into semiconductor elements; an ultraviolet irradiation step of irradiating the adhesive sheet with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer; and a peeling step of peeling the adhesive sheet from the semiconductor elements.

[0023] A method for manufacturing a semiconductor device will be described below with reference to FIG. 1. FIG. 1 is a process flow diagram of an exemplary method for manufacturing a fan-out package, and each step will be described below. (a): A semiconductor chip 20 has an insulating region 16 and a conductive region 18 on its surface. An adhesive sheet 15, which includes a base layer 12 and an ultraviolet-curable adhesive layer 14 provided on the base layer 12, is attached to the surface of the semiconductor chip 20 to obtain an adhesive sheet-attached electronic component 100. (b): The semiconductor chip 20 is encapsulated with a sealing resin 22 to form a connected semiconductor element structure 200. (c): The adhesive sheet 15 is irradiated with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer 14 and reduce its adhesive strength, and then the adhesive sheet 15 is peeled off from the connected semiconductor element structure 200. (d): A rewiring layer 24 is formed on the connected semiconductor element structure 200. (e): Conductor posts 26 and bumps 28 are formed on the rewiring layer 24. (f): An adhesive sheet 15 having a base layer 12 and an ultraviolet-curable adhesive layer 14 provided on the base layer 12 is attached to the rewiring layer 24 of the connected semiconductor element body 200 to obtain an adhesive sheet-attached electronic component 110. (g): The connected semiconductor element body 200 with the adhesive sheet 15 attached is diced to separate into semiconductor elements 300. (h): The adhesive sheet 15 is irradiated with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer 14 and reduce its adhesive strength, and then the adhesive sheet 15 is peeled off from each semiconductor element 300.

[0024] In FIG. 1, one chip is encapsulated in one semiconductor element, but the number of encapsulated chips is not limited. By encapsulating multiple chips in one semiconductor element, a 2.xD SiP can be manufactured. In FIG. 1, adhesive sheet 15 is attached in steps (a) and (f), but an adhesive sheet having another adhesive layer can be used in place of adhesive sheet 15 in either step. From the viewpoint of reducing adhesive residue on the adherend, it is preferable to use adhesive sheet 15 in both steps.

[0025] In one embodiment, a method for manufacturing an electronic device includes the steps of: preparing a substrate having an insulating region and a conductive region on its surface; attaching an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer to the surface of the substrate; processing the substrate to which the adhesive sheet has been attached; irradiating the adhesive sheet with ultraviolet light to photocure the ultraviolet-curable adhesive layer; and peeling the adhesive sheet from the substrate. In this embodiment, examples of the processing steps include a mounting step, a sealing step, a noise suppression layer forming step, a cutting step, and a singulation step.

[0026] 2 is a vertical cross-sectional view showing an example of an electronic device that can be manufactured by the manufacturing method of an electronic device according to one embodiment. In the following description, the upper side in FIG. 2 will be referred to as "top" and the lower side as "bottom."

[0027] The electronic device 400 shown in FIG. 2 includes a substrate 32 having conductor posts 26 arranged to penetrate the substrate 32 in the thickness direction, a semiconductor element 34 and electronic elements 36 such as a capacitor and a coil arranged on the substrate 32, a sealing portion 42 that seals the semiconductor element 34 and the electronic elements 36, wiring 30 formed on the underside of the substrate 32 and electrically connected to the conductor posts, bumps 28 electrically connected to the wiring 30, a covering portion 40 that covers the wiring 30 and has openings 41 (not shown in FIG. 2 ) that expose the bumps 28, and a noise suppression layer 38 that covers the upper surface and side surfaces of the sealing portion 42, the side surfaces of the substrate 32, and part of the side surfaces of the covering portion 40.

[0028] The substrate 32 is a substrate that supports the semiconductor element 34 and the electronic element 36. The shape of the substrate 32 in a plan view is usually a quadrilateral such as a square or a rectangle. A plurality of through holes are formed in the substrate 32, penetrating through the substrate 32 in the thickness direction, and the conductor posts 26 are provided corresponding to the through holes.

[0029] The semiconductor element 34 and the electronic element 36 are arranged on the substrate 32 so that electrode pads (not shown) on the bottom surfaces of the semiconductor element 34 and the electronic element 36 correspond to the conductor posts 26. With the semiconductor element 34 and the electronic element 36 arranged in such positions, the sealing portion 42 is formed to cover the top surfaces of the semiconductor element 34, the electronic element 36, and the substrate 32.

[0030] The conductor posts 26 formed corresponding to the through holes in the substrate 32 are electrically connected at their upper ends to electrode pads provided on the semiconductor element 34 or electronic element 36. Wiring 30 formed in a predetermined shape is provided on the lower surface of the substrate 32, and part of it is electrically connected to the lower ends of the conductor posts 26.

[0031] Bumps 28 are electrically connected to the underside of the wiring 30, thereby electrically connecting the semiconductor element 34 or electronic element 36 to the bumps 28 via the electrode pads, conductor posts 26, and wiring 30. Furthermore, a covering portion 40 is provided to cover the wiring 30, and the covering portion 40 has openings 41 for exposing the bumps 28 from the underside thereof.

[0032] The noise suppression layer 38 is provided to cover the upper surface of the sealing portion 42, the side surfaces of the sealing portion 42, the side surfaces of the substrate 32, and part of the side surfaces of the covering portion 40. The noise suppression layer 38 blocks electromagnetic waves generated from at least one of the semiconductor element 34 and the electronic element 36 provided on the substrate 32 and other electronic components located outside the electronic device 400, thereby suppressing noise caused by the electromagnetic waves. Note that the noise suppression layer 38 has part of the wiring 30 exposed on the side surface of the covering portion 40, and the wiring 30 is electrically connected to the noise suppression layer 38, so that the noise suppression layer 38 is electrically grounded via the wiring 30.

[0033] 2 includes one semiconductor element 34 and two electronic elements 36, the number of semiconductor elements 34 and electronic elements 36 is not limited to this. The electronic device may include either one of a semiconductor element or an electronic element. While the electronic device 400 in FIG. 2 includes a noise suppression layer 38, the electronic device may not include the noise suppression layer 38.

[0034] (Method for manufacturing electronic device 400) Electronic device 400 can be manufactured using an adhesive sheet. The adhesive sheet is attached to the surface of the substrate as a protective tape for the surface of the substrate or as a temporary fixing tape for the substrate during processing. By using an electronic component with an adhesive sheet as an intermediate, an electronic device can be obtained with little adhesive residue from the adhesive layer.

[0035] The electronic device 400 having the above-described configuration can be manufactured by, for example, the following method. A manufacturing method for an electronic device according to one embodiment includes the following steps: a preparation step of preparing an electronic component assembly including a substrate, at least one selected from a semiconductor element and an electronic element arranged on a first surface of the substrate, and a sealing portion formed on the first surface of the substrate to seal the substrate and the at least one selected from the semiconductor element and the electronic element, the electronic component assembly including wiring formed on the second surface of the substrate, a covering portion formed on the second surface of the substrate, the covering portion covering the substrate and the wiring and having an opening through which a portion of the wiring is exposed, and a bump electrically connected to the wiring exposed in the opening; a cutting step of cutting the electronic component assembly in the thickness direction to form recesses through which side surfaces of the electronic component assembly are exposed, corresponding to each electronic component assembly to be formed, thereby forming the electronic component assembly; a noise suppression layer forming step of forming a noise suppression layer covering the top surface and side surfaces of the electronic component assembly; and a singulation step of singulating the electronic component assembly by extending the recesses through the covering portion to singulate the electronic component assembly. The method for manufacturing an electronic device further includes a bonding step of bonding an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer to a surface of a substrate having an insulating region and a conductive region, a UV irradiation step of irradiating the adhesive sheet with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer, and a peeling step of peeling the adhesive sheet from the substrate. Note that the surface of the substrate does not mean only the surface of the substrate itself, but also means the surface of the outermost layer if wiring, a coating, bumps, etc. are formed on the surface of the substrate.

[0036] A specific embodiment of the method for manufacturing an electronic device having these steps will be described in detail below with reference to Figures 3 to 5. Figures 3 to 5 are process flow diagrams of an exemplary manufacturing method for collectively manufacturing a plurality of electronic devices 400. In the following description, the upper side in Figures 3 to 5 will be referred to as "upper" and the lower side will be referred to as "lower."

[0037] 4A, a sealed electronic component linked body 500 is prepared, which is provided with wiring 30, coverings 40, and bumps 28. The sealed electronic component linked body 500 is prepared, for example, through the following steps [1-1] to [1-7].

[0038] [1-1] A substrate 32 as shown in FIG. 3( a) is prepared. The substrate 32 has a plurality of pre-formed through holes and further has conductor posts 26 embedded in the substrate 32 corresponding to the through holes. The conductor posts 26 are formed at positions corresponding to the electrode pads of the semiconductor elements 34 and electronic elements 36 when the semiconductor elements 34 and electronic elements 36 are placed on the substrate 32 in step [1-5] described below. In other words, the number of conductor posts 26 on the substrate 32 is the same as the total number of terminals of the plurality of semiconductor elements 34 and electronic elements 36 placed on the substrate 32. An adhesive sheet may be attached to the bottom or top surface of the substrate 32 for protection or temporary fixation.

[0039] The substrate 32 is cut in the thickness direction into individual pieces, and thereby functions as an interposer, supporting the semiconductor element 34 and the electronic element 36 .

[0040] The substrate 32 is not particularly limited as long as it has a hardness sufficient to support the semiconductor element 34 and the electronic element 36. Specific examples include rigid substrates such as a core substrate made of a core material and a build-up substrate made of a build-up material, and flexible substrates. Of these, build-up substrates are preferred because of their excellent processability.

[0041] The build-up material is not particularly limited, but examples thereof include those composed primarily of a cured resin composition containing a thermosetting resin such as a phenolic resin, a urea resin, a melamine resin, or an epoxy resin, a curing agent, and an inorganic filler. Among these, it is preferable that the build-up material contain an epoxy resin from the viewpoints of the adhesiveness of the pressure-sensitive adhesive sheet and the releasability in the peeling step.

[0042] The core material is not particularly limited, but examples thereof include those primarily composed of thermosetting resins such as cyanate resins, epoxy resins, bismaleimide-triazine resins, etc. Among these, it is preferable that the core material contains an epoxy resin from the viewpoint of the adhesiveness of the pressure-sensitive adhesive sheet and the releasability in the peeling step.

[0043] Examples of flexible substrates include those made primarily of thermoplastic resins such as polyimide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene (PTFE), polyimidebenzoxazole (PIBO), and liquid crystal polymers.

[0044] The material of the flexible substrate may contain a rubber component to impart stretchability. Examples of the rubber component include at least one selected from the group consisting of acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. The rubber component may be used alone or in combination of two or more.

[0045] From the viewpoint of imparting thermosetting properties, the rubber component may have a crosslinking group. The crosslinking group may be any reactive group capable of promoting a reaction that crosslinks molecular chains. Examples thereof include (meth)acrylic groups, vinyl groups, epoxy groups, styryl groups, amino groups, isocyanurate groups, ureido groups, cyanate groups, isocyanate groups, mercapto groups, hydroxy groups, carboxy groups, and acid anhydride groups. Preferably, the rubber component contains at least one selected from acid anhydride groups and carboxy groups. An example of a rubber component having an acid anhydride group is rubber partially modified with maleic anhydride.

[0046] The material of the flexible substrate may be a cured product of a resin composition containing a rubber component. This resin composition may contain a crosslinking component. Examples of the crosslinking component include a compound having at least one reactive group selected from the group consisting of a (meth)acrylic group, a vinyl group, an epoxy group, a styryl group, an amino group, an isocyanurate group, a ureido group, a cyanate group, an isocyanate group, a mercapto group, a hydroxy group, and a carboxy group. A cured product containing a crosslinked polymer can be formed by the reaction of these reactive groups. From the viewpoint of improving heat resistance, the crosslinking component is preferably a compound having at least one reactive group selected from an epoxy group, an amino group, a hydroxy group, and a carboxy group. The crosslinking components may be used alone or in combination of two or more.

[0047] For example, by combining a rubber having a maleic anhydride group or a carboxy group with a compound having an epoxy group, particularly excellent effects can be obtained in terms of stretchability, heat resistance, low moisture permeability, adhesion between the flexible substrate and the wiring conductor, and low tackiness of the flexible substrate. A flexible substrate with low tackiness has good workability.

[0048] The compound having an epoxy group is not particularly limited as long as it has an epoxy group in the molecule, and may be, for example, a general epoxy resin. Examples of epoxy resins include monofunctional epoxy resins, bifunctional epoxy resins, and polyfunctional epoxy resins. Although there are no particular limitations, at least one selected from the group consisting of bifunctional epoxy resins and polyfunctional epoxy resins is preferred from the viewpoint of obtaining sufficient curability.

[0049] Examples of epoxy resins include bisphenol A, bisphenol F, phenol novolac, naphthalene, dicyclopentadiene, and cresol novolac epoxy resins, as well as resins in which an aliphatic chain skeleton has been introduced into these epoxy resins. The use of an epoxy resin in which an aliphatic chain skeleton has been introduced can impart flexibility to a flexible substrate. An example of a commercially available epoxy resin in which an aliphatic chain skeleton has been introduced is EXA-4816 (DIC Corporation). From the viewpoints of curability, low tack, and heat resistance, phenol novolac, cresol novolac, naphthalene, and dicyclopentadiene epoxy resins are preferred. These epoxy resins can be used alone or in combination of two or more types.

[0050] 3B, wiring 30 patterned into a predetermined shape is formed on the surface of the substrate 32 opposite to the surface on which the semiconductor element 34 and the electronic element 36 are arranged, i.e., the lower surface, so as to be electrically connected to the conductor post 26. At this stage, an adhesive sheet may be attached to the lower surface of the substrate 32 and the wiring 30, and the process may proceed to step [1-5].

[0051] The method for forming the wiring 30 is not particularly limited, and examples thereof include I: a method for forming the wiring 30 using a plating method such as electrolytic plating or electroless plating, and II: a method for forming the wiring 30 by supplying a liquid material containing a conductive material to the substrate 32 and drying and solidifying it. It is preferable to form the wiring 30 using method I, especially electrolytic plating. Electrolytic plating makes it possible to easily and reliably form the wiring 30 having excellent adhesion to the conductor post 26.

[0052] [1-3] (Covering Portion Forming Step) As shown in FIG. 3C, the covering portion 40 is formed so as to cover the substrate 32 and the wiring 30.

[0053] Such a covering portion 40 is usually mainly composed of a thermosetting resin. Examples of thermosetting resins include epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, polyimide resin, silicone resin, and polyurethane resin. The thermosetting resins can be used alone or in combination of two or more. Among them, epoxy resin is preferred because it is easily available and has excellent heat resistance.

[0054] Examples of epoxy resins include those obtained by reacting a compound having two phenolic hydroxyl groups, such as bisphenol A, bisphenol F, bisphenol AD, hydroquinone, methylhydroquinone, dimethylhydroquinone, dibutylhydroquinone, resorcinol, methylresorcinol, biphenol, tetramethylbiphenol, dihydroxynaphthalene, or dihydroxydiphenyl ether, with epichlorohydrin and / or methylepichlorohydrin; those obtained by reacting a condensate of a compound in which one or more of the above-mentioned compounds having two phenolic hydroxyl groups have been glycidyl-etherified with one or more of the above-mentioned compounds having two phenolic hydroxyl groups, with epichlorohydrin and / or methylepichlorohydrin; phenol novolac resin, cresol novolac resin, bisphenol A novolac resin, dicyclopentadiene phenol resin, terpene phenol resin, phenol aralkyl resin, and naphthol novolac resin.

[0055] The covering portion 40 can be formed, for example, using a method similar to the method for forming the sealing portion 42 described below.

[0056] 3(d), an opening 41 is formed in the covering portion 40 so as to expose a portion of the wiring 30. At this stage, an adhesive sheet may be attached to the wiring 30, the covering portion 40, and the opening 41, and the process may proceed to step [1-5]. Before performing step [1-5], the process may proceed to step [1-7].

[0057] The openings 41 are formed so as to correspond to positions where the bumps 28 will be formed in the subsequent process [1-7]. The method for forming the openings 41 in the covering portion 40 is not particularly limited, but an example is a method in which the covering portion 40 is etched using a resist layer formed on the covering portion 40 as a mask so as to expose the regions where the openings 41 are to be formed.

[0058] [1-5] If an adhesive sheet is attached to the upper surface of the substrate 32, peel it off, and as shown in FIG. 3( e), the semiconductor element 34 and the electronic element 36 are placed on the upper surface of the substrate 32 on which the wiring 30 and the covering portion 40 having the opening 41 are provided.

[0059] When placing the semiconductor element 34 and the electronic element 36 on the substrate 32, the semiconductor element 34 and the electronic element 36 are placed so that the electrode pads of the semiconductor element 34 and the electronic element 36 correspond to the positions of the conductor posts 26 provided on the substrate 32, respectively.

[0060] The semiconductor element 34 and the electronic element 36 may or may not be fixed to the substrate 32, but are preferably fixed with an adhesive (also called an underfill material) such as an epoxy adhesive, which effectively prevents the semiconductor element 34 and the electronic element 36 from being misaligned when the semiconductor element 34 and the electronic element 36 are sealed in step [1-6].

[0061] [1-6] As shown in FIG. 3(f), a sealing portion 42 is formed on the upper surface of the substrate 32, i.e., the surface on which the semiconductor element 34 and the electronic element 36 are arranged, so as to cover the substrate 32, the semiconductor element 34, and the electronic element 36.

[0062] This allows for the production of an electronic component sealed assembly 500 in which the substrate 32, semiconductor element 34, and electronic element 36 are sealed by the sealing portion 42 on the upper surface side of the substrate 32, with the wiring 30 and covering portion 40 provided on the lower surface side.

[0063] The method for forming the sealing portion 42 is not particularly limited, but examples include a method in which a molten thermosetting resin composition such as a granular epoxy resin composition is supplied to the upper surface of the substrate 32 so as to cover the substrate 32, the semiconductor element 34, and the electronic element 36, and then the molten thermosetting resin composition is compression molded. According to this method, the semiconductor element 34 and the electronic element 36 can be easily and densely sealed on the substrate 32.

[0064] [1-7] (Bump Connection Step) If an adhesive sheet is attached to the underside of the substrate 32, it is peeled off, and as shown in Fig. 3(g), bumps 28 are formed so as to electrically connect to the wiring 30 exposed at the opening 41 of the covering portion 40. If steps [1-5] and [1-6] are performed after step [1-7], an adhesive sheet may be attached to the covering portion 40 and the bumps 28 before proceeding to step [1-5].

[0065] By configuring the connection between the conductor post 26 and the bump 28 via the wiring 30, the bump 28 can be positioned at a different position from the conductor post 26 in the surface direction of the substrate 32. In other words, the bump 28 and the conductor post 26 can be positioned so that their centers do not overlap. Therefore, the bump 28 can be formed at a desired position on the underside of the obtained electronic device 400.

[0066] The method for joining the bumps 28 to the wiring 30 is not particularly limited, but for example, a method of interposing a viscous flux between the bumps 28 and the wiring 30 can be mentioned.

[0067] Examples of materials constituting the bumps 28 include solder, silver solder, copper solder, phosphorus copper solder, and other brazing materials.

[0068] Through the above-described steps [1-1] to [1-7], the sealed electronic component linked body 500 provided with the wiring 30, the covering portion 40, and the bumps 28 is prepared.

[0069] As described above, the wiring 30, the covering 40, the openings 41, and the bumps 28 are formed collectively on the sealed electronic component assembly 500, not on the sealed electronic component assembly 600 (described later), which simplifies the process of forming the wiring 30, the covering 40, and the bumps 28, thereby saving time and labor. As a result, the productivity of the electronic device 400 is improved.

[0070] 3 illustrates the case where the wiring 30 and the covering portion 40 including the opening 41 are formed on the lower surface of the substrate 32 prior to the formation of the sealed electronic component linked body 500, but the method for manufacturing the electronic device 400 is not limited to this method. For example, the wiring 30 and the covering portion 40 including the opening 41 may be formed on the lower surface of the substrate 32 after the sealed electronic component linked body 500 is formed.

[0071] The formation of the bumps 28 in the openings 41 of the covering portion 40 may be performed not after the formation of the sealed electronic component linked body 500, but prior to the formation of the sealed electronic component linked body 500, i.e., prior to the arrangement of the semiconductor element 34 and the electronic element 36 and the formation of the sealing portion 42. In this case, an adhesive sheet may be attached to the covering portion 40 and the bumps 28, followed by the arrangement of the semiconductor element 34 and the electronic element 36 and the formation of the sealing portion 42, and the cutting step of the sealed electronic component linked body 500 may proceed with the adhesive sheet still attached.

[0072] 4( a), an adhesive sheet 15 is attached to the covering portion 40 and the bumps 28. Next, as shown in FIG. 4( b), the sealed electronic component linked body 500 is fixed using, for example, a wafer ring, and then, using a dicing blade, the sealed electronic component linked body 500 is cut in the thickness direction at positions corresponding to each sealed electronic component 600 to be formed, i.e., corresponding to each region where one semiconductor element 34 and two electronic elements 36 to be provided in the electronic device 400 are sealed with the sealing portion 42, to form recesses 43 so that the side surfaces of the sealed electronic component 600 are exposed.

[0073] As a result, the electronic component sealed assembly 500 is obtained in a state where the electronic component sealed assembly 600 is separated into individual pieces corresponding to each combination of one semiconductor element 34 and two electronic elements 36, forming a lattice shape in a planar view, and is attached to the adhesive sheet 15 via the wiring 30, covering portion 40 and bumps 28.

[0074] In this case, the adhesive sheet 15 has a cushioning effect, and when the electronic component sealed assembly 500 is cut, cracks, chips, etc. can be suppressed or prevented from occurring in the electronic component sealed assembly 500, as well as in the wiring 30, the covering portion 40, and the bumps 28.

[0075] As shown in FIG. 4C , the cutting of the sealed electronic component assembly 500 using a dicing blade is preferably performed in the thickness direction of the covering portion 40, reaching a position that penetrates the thickness corresponding to the wiring 30, and reaching partway through the covering portion 40. This ensures that the sealed electronic component assembly 500 can be singulated. In addition, with the sealed electronic component assembly 600 attached to the adhesive sheet 15 via the wiring 30, covering portion 40, and bumps 28, the side surfaces of the sealed electronic component 600, i.e., the side surfaces of the sealing portion 42 and the substrate 32, and part of the side surface of the covering portion 40, can be reliably exposed in the recesses 43.

[0076] (Noise Suppression Layer Forming Process) Next, as shown in FIG. 4D, the noise suppression layer 38 is formed to cover the top and side surfaces of the sealed electronic component 600 and part of the side surface of the covering portion 40 .

[0077] The noise suppression layer 38 is formed, for example, through the following steps [2-1] and [2-2]. In addition to the following steps, the noise suppression layer 38 may also be formed by a PVD method.

[0078] [2-1] An electromagnetic wave shielding film having a release layer, which is an insulating layer, and a noise suppression layer 38 laminated on the release layer is prepared, and the electromagnetic wave shielding film is laminated on the surface of the sealed electronic component 600 on which the sealing portion 42 of the sealed electronic component 600 is formed, with the noise suppression layer 38 facing the sealed electronic component 600.

[0079] The method for attaching the electromagnetic wave shielding film to the sealed electronic component 600 is not particularly limited, and examples thereof include vacuum pressure forming and press molding. Vacuum pressure forming is a method in which, for example, a vacuum pressure laminator is used to cover the top and side surfaces of the sealed electronic component 600 with the electromagnetic wave shielding film. Vacuum pressure forming is performed by setting the sealed electronic component 600 and the electromagnetic wave shielding film in a superimposed state in a closed space that can be held under a vacuum atmosphere so that the surface of the sealed electronic component 600 on which the sealing portion 42 is formed faces the surface of the electromagnetic wave shielding film on the noise suppression layer 38 side, and then heating them to create a vacuum atmosphere in the closed space so that the electromagnetic wave shielding film and the sealed electronic component 600 approach each other uniformly from the electromagnetic wave shielding film side, and then pressurizing the closed space.

[0080] In this way, by applying pressure uniformly from the electromagnetic shielding film side and creating a vacuum atmosphere in the closed space, the release layer presses the noise suppression layer 38 into correspondence with the shape of the recess 43, and in conjunction with this pressing, the noise suppression layer 38 deforms into correspondence with the shape of the recess 43. As a result, with the noise suppression layer 38 pressed into correspondence with the shape of the recess 43, the top surface and side surfaces of the sealed electronic component 600 and part of the side surface of the covering 40 are covered by the noise suppression layer 38.

[0081] In this way, by covering the top surface and side surfaces of the sealed electronic component 600 with the noise suppression layer 38, it is possible to impart electromagnetic wave shielding properties to the resulting electronic device 400. Because part of the wiring 30 is exposed on the side surface of the covering 40, covering part of the side surface of the covering 40 with the noise suppression layer 38 allows the wiring 30 and the noise suppression layer 38 to be electrically connected. As a result, the noise suppression layer 38 is electrically grounded via the wiring 30.

[0082] If electrical grounding of the noise suppression layer 38 is not required, the formation of the noise suppression layer 38 on the side surface of the covering 40 can be omitted. In this case, the formation of the recess 43, i.e., the cutting of the sealed electronic component assembly 500, does not need to be performed so as to reach partway through the covering 40; it is sufficient to perform the cutting until the substrate 32 is penetrated.

[0083] In the step of attaching the electromagnetic wave shielding film by vacuum and pressure forming, the temperature at which the film is attached is not particularly limited, but is preferably 15°C or higher and 220°C or lower, and more preferably 20°C or higher and 210°C or lower.

[0084] The pressure at which the patch is applied is not particularly limited, but is preferably 0.1 MPa or more and 20.0 MPa or less, and more preferably 0.5 MPa or more and 15.0 MPa or less.

[0085] The application time is not particularly limited, but is preferably from 5 seconds to 90 minutes, more preferably from 30 seconds to 10 minutes.

[0086] By setting the conditions in the process of attaching the electromagnetic wave shielding film within the above range, the noise suppression layer 38 can be pressed into the recesses 43 between adjacent electronic component sealed bodies 600, and this noise suppression layer 38 can reliably cover the top and side surfaces of the electronic component sealed body 600 and part of the side surface of the covering portion 40.

[0087] In this process, the electromagnetic wave shielding film is used to cover the electronic component sealed body 600 and the covering portion 40 with the noise suppression layer 38, with the noise suppression layer 38 pressed into the recesses 43 between adjacent electronic component sealed bodies 600.

[0088] The press molding method is carried out, for example, by placing an electromagnetic wave shielding film on the surface on which the sealing portion 42 of the sealed electronic component 600 attached to the adhesive sheet 15 is formed, and further placing a cushioning material on this electromagnetic wave shielding film, sandwiching these from the upper and lower sides between two flat plates, and then bringing the two flat plates close to each other and applying pressure.

[0089] In this way, even by bringing the electromagnetic wave shielding film and the electronic component encapsulated body 600 close to each other with the cushioning material disposed on the electromagnetic wave shielding film, the release layer presses the noise suppression layer 38 into correspondence with the shape of the recess 43, and in conjunction with this pressing, the noise suppression layer 38 can be deformed into correspondence with the shape of the recess 43. Therefore, with the noise suppression layer 38 pressed into correspondence with the shape of the recess 43, the noise suppression layer 38 can cover the top and side surfaces of the electronic component encapsulated body 600 and part of the side surface of the covering 40.

[0090] In the electromagnetic wave shielding film, the release layer presses the noise suppression layer 38 into the recess 43 to conform to the shape of the recess 43, thereby functioning as a buffer material that prevents the pressed-in noise suppression layer 38 from breaking when covering the top and side surfaces of the sealed electronic component 600 and part of the side surface of the covering 40. The release layer of the electromagnetic wave shielding film is peeled off from the noise suppression layer 38 in step [2-2].

[0091] The constituent material of the release layer is not particularly limited, and examples thereof include resin materials such as syndiotactic polystyrene, polymethylpentene, polybutylene terephthalate, polyethylene terephthalate, polypropylene such as non-axially oriented polypropylene and biaxially oriented polypropylene, cyclic olefin polymer, silicone, styrene elastomer resin, styrene butadiene rubber, acrylic rubber, epoxy resin, polyphenol, polyurethane, etc. Among these, non-axially oriented polypropylene is preferred from the viewpoints of the ability of the release layer to be pressed into the noise suppression layer and heat resistance.

[0092] The storage modulus of the release layer at 100°C is preferably 1.0E+04 Pa or more and 1.0E+11 Pa or less, more preferably 1.0E+05 Pa or more and 1.0E+10 Pa or less, and even more preferably 1.0E+06 Pa or more and 5.0E+09 Pa or less.

[0093] The thickness of the release layer is not particularly limited, but is preferably 20 μm or more and 1000 μm or less, and more preferably 70 μm or more and 500 μm or less.

[0094] The noise suppression layer 38 has the function of blocking electromagnetic waves generated from at least one of the semiconductor element 34 and electronic element 36 included in the electronic component encapsulated body 600 and other electronic components, etc. located outside the electronic component encapsulated body 600.

[0095] The noise suppression layer 38 is not particularly limited and may be one that blocks electromagnetic waves in any form. Examples of the noise suppression layer 38 include a reflective layer that blocks electromagnetic waves incident on the noise suppression layer 38 by reflecting them, and an absorbing layer that blocks electromagnetic waves incident on the noise suppression layer 38 by absorbing them.

[0096] [2-2] In this step, the release layer is peeled off from the electromagnetic wave shielding film attached to the sealed electronic component 600 .

[0097] When the release layer is peeled off, peeling occurs at the interface between the release layer in the electromagnetic wave shielding film and the noise suppression layer 38 , resulting in the release layer being peeled off from the noise suppression layer 38 .

[0098] Therefore, a plurality of sealed electronic components 600 are formed at once, with the noise suppression layer 38 provided on the top and side surfaces, in a state where they are attached to the adhesive sheet 15 via the covering portion 40, wiring 30, and bumps 28.

[0099] The method for peeling the release layer is not particularly limited, but manual peeling is preferred, for example. In manual peeling, for example, one end of the release layer is first grasped and the release layer is peeled from the grasped end from the noise suppression layer 38, and then the release layer is sequentially peeled from the end toward the center and then toward the other end, thereby peeling the release layer from the noise suppression layer 38.

[0100] The peeling temperature is preferably 180°C or less, more preferably 165°C or less, and even more preferably 150°C or less.

[0101] By performing the above-described steps [2-1] and [2-2], the top surface and side surfaces of the sealed electronic component 600 and part of the side surface of the covering portion 40 can be covered with the noise suppression layer 38, with the release layer being peeled off from the noise suppression layer 38, as shown in FIG. 4( d ).

[0102] Examples of the PVD method include sputtering. Examples of the sputtering method include magnetron sputtering, bipolar sputtering, DC (direct current) sputtering, RF (radio frequency) sputtering, reactive sputtering, and ion beam sputtering. The sputtering conditions are not particularly limited. For example, metals such as Cr, Cu, Ti, Ag, Pt, and Au, alloys such as Ni—Cr, SUS, and Cu—Zn, or ITO, SiO ２ , TiO ２ , Nb ２ O ５ Alternatively, a metal oxide such as ZnO may be used as a target and an inert gas such as Ar may be used to form the film.

[0103] (Singulation process) As shown in FIG. 5( a), the adhesive sheet 15 attached to the covering portion 40 and the bumps 28 is peeled off, and another adhesive sheet 15 is attached to the noise suppression layer 38 on the upper surface of the plurality of sealed electronic components 600 as shown in FIG. 5( b).

[0104] Next, the sealed electronic component 600 with the adhesive sheet 15 attached via the noise suppression layer 38 is fixed using, for example, a wafer ring. Thereafter, as shown in FIG. 5( c), a dicing blade is used to cut the recesses 43 in the thickness direction, penetrating the covering portion 40. By cutting the covering portion 40, individual electronic devices 400 can be obtained in a state where they are attached to the adhesive sheet 15. Furthermore, as shown in FIG. 5( d), the adhesive sheet 15 can be peeled off to obtain the electronic device 400. Instead of the adhesive sheet 15, an adhesive sheet having another adhesive layer can also be used.

[0105] (Attachment Step) In the above method, attachment of the adhesive sheet 15 to the surface of the substrate 32 having an insulating region and a conductive region can be carried out, for example, by placing the adhesive sheet 15 on a dicer table, placing the adherend surface of the base material 32 on the adhesive sheet 15, and lightly pressing it. If the adherend surface has bumps 28, this can be carried out by embedding the bumps 28 in the adhesive sheet 15. It is also possible to attach the adhesive sheet 15 to the adherend surface in advance, and then place them on the dicer table.

[0106] The adhesive sheet 15 protects the adherend surface of the substrate 32 while it is attached, and also serves as a temporary fixing material while various processes are performed on the surface of the substrate 32. Note that in some steps, an adhesive sheet having another adhesive layer may be used instead of the adhesive sheet 15.

[0107] (Ultraviolet Irradiation Step and Peeling Step) When it becomes necessary to process the adherend surface or place the adhesive sheet on another substrate, the adhesive sheet 15 is no longer needed and is peeled off from the adherend surface. The peeling of the adhesive sheet 15 is performed after the adhesive strength of the adhesive sheet 15 has been reduced by UV irradiation.

[0108] Although the method for manufacturing the electronic device 400 collectively has been described here, the electronic device 400 may be manufactured individually. Also, although the method for manufacturing the electronic device 400 having the noise suppression layer 38 has been described here, the noise suppression layer 38 may not be formed. In this case, the electronic device 400 can be obtained by singulating in the cutting step described above.

[0109] <Transfer Sheet> A transfer sheet according to one embodiment includes a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer, and a wiring conductor partially provided on the ultraviolet-curable pressure-sensitive adhesive layer. The transfer sheet can be used, for example, in the manufacture of a wiring board.

[0110] (Wiring Conductor) The wiring conductor is a conductor layer provided on an ultraviolet-curable pressure-sensitive adhesive layer, on which a wiring pattern is formed. The wiring material is not particularly limited as long as it is a commonly used, electrically conductive material. In particular, copper or a copper-containing alloy is preferably used from the viewpoint of wiring formability. Examples of the conductor layer include conductor foils such as metal foils and conductor plating films. Among these, metal foils are preferred. Examples of metal foils suitable for forming wiring patterns include copper foil, titanium foil, stainless steel foil, nickel foil, permalloy foil, 42 alloy foil, kovar foil, nichrome foil, beryllium copper foil, phosphor bronze foil, brass foil, nickel silver foil, aluminum foil, tin foil, lead foil, zinc foil, solder foil, iron foil, tantalum foil, niobium foil, molybdenum foil, zirconium foil, gold foil, silver foil, palladium foil, Monel foil, Inconel foil, and Hastelloy foil. From the viewpoint of appropriate elastic modulus, the metal foil is preferably selected from copper foil, gold foil, nickel foil, and iron foil, and more preferably copper foil. Copper foil allows for easy formation of a wiring pattern by photolithography.

[0111] The copper foil is not particularly limited, and can be, for example, an electrolytic copper foil or rolled copper foil used in copper-clad laminates and flexible wiring boards. Commercially available electrolytic copper foils include 3EC-M3-VLP-18 (Mitsui Mining & Smelting Co., Ltd.), F0-WS-18 (Furukawa Electric Co., Ltd., product name), NC-WS-20 (Furukawa Electric Co., Ltd., product name), YGP-12 (Nippon Denkai Co., Ltd., product name), GTS-18 (Furukawa Electric Co., Ltd., product name), and F2-WS-12 (Furukawa Electric Co., Ltd., product name). Commercially available rolled copper foils include TPC foil (JX Nippon Mining & Metals Corporation, product name), HA foil (JX Nippon Mining & Metals Corporation, product name), HA-V2 foil (JX Nippon Mining & Metals Corporation, product name), and C1100R (Sumitomo Mitsui Metal Mining Copper and Brazing Co., Ltd., product name). Copper foils that have been subjected to a roughening treatment may be used from the viewpoint of adhesion to the insulating sheet to which the wiring conductor is transferred. From the viewpoint of folding resistance, rolled copper foil may be used.

[0112] The metal foil may have a roughened surface formed by roughening treatment. In this case, the metal foil is typically provided on the ultraviolet-curable pressure-sensitive adhesive layer so that the roughened surface faces away from the ultraviolet-curable pressure-sensitive adhesive layer. From the viewpoint of adhesion between the insulating sheet onto which the wiring conductor is transferred and the metal foil, the surface roughness Ra of the roughened surface may be 0.1 to 3 μm, or 0.2 to 2.0 μm. In order to easily form fine wiring, the surface roughness Ra of the roughened surface may be 0.3 to 1.5 μm.

[0113] The surface roughness Ra is measured using a surface profiler Wyko NT9100 (Veeco) under the following conditions: Inner lens: 1x Outer lens: 50x Measurement range: 0.120 x 0.095 mm Measurement depth: 10 μm Measurement method: Vertical Scanning Interferometry (VSI)

[0114] The wiring conductor can be provided on the ultraviolet-curable adhesive layer, for example, by forming a conductor layer on the ultraviolet-curable adhesive layer and etching it into a predetermined pattern by photolithography.

[0115] The thickness of the wiring conductor or conductor layer is preferably 0.5 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the wiring conductor or conductor layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. The thickness of the wiring conductor or conductor layer is preferably 0.5 to 100 μm, more preferably 5 to 50 μm, and even more preferably 10 to 30 μm. When the thickness of the wiring conductor or conductor layer is 0.5 μm or more, poor transfer of the wiring conductor is suppressed. When the thickness of the wiring conductor or conductor layer is 100 μm or less, the resistivity is sufficiently low, making it easy to form a highly accurate microstructure, and the surface of the adherend after transfer can be smoothed, preventing problems when laminating an insulating sheet to which the wiring conductor has been transferred.

[0116] The thickness of the wiring conductor or conductor layer is preferably 0.01 times or more, more preferably 0.1 times or more, and more preferably 0.6 times or more, relative to the thickness of the ultraviolet-curable pressure-sensitive adhesive layer. The thickness of the wiring conductor or conductor layer is preferably 1.20 times or less, more preferably 1.15 times or less, and even more preferably 1.00 times or less, relative to the thickness of the ultraviolet-curable pressure-sensitive adhesive layer. The thickness of the wiring conductor or conductor layer is preferably 0.01 to 1.20 times, and more preferably 0.1 to 1.15 times, relative to the thickness of the ultraviolet-curable pressure-sensitive adhesive layer.

[0117] <Method for manufacturing transfer sheet> The transfer sheet can be manufactured from, for example, a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer, and a sheet with a conductor layer for transfer sheet having a conductor layer provided on the ultraviolet-curable pressure-sensitive adhesive layer. In one embodiment, the method for manufacturing the transfer sheet includes a resist layer patterning step of providing a resist layer on the exposed surface of the conductor layer of the sheet with a conductor layer for transfer sheet, exposing the resist layer through a photomask, and developing the resist layer with a developer, an etching step of removing the exposed region of the conductor layer formed by the patterning step by etching to form a wiring conductor, and a removal step of removing the resist layer on the wiring conductor formed by the etching step.

[0118] The material of the resist layer used in the patterning step can be a known material, and is not particularly limited as long as it has a patterning function. The form of the resist is also not particularly limited, and it may be applied to the exposed surface of the conductor layer in the form of a dry film, or may be applied to the exposed surface of the conductor layer in the form of a liquid and then heated and dried to form a film. The resist layer may be either negative or positive.

[0119] The resist layer is patterned by exposing it to light through a photomask and developing it with a developer. As a result, the areas where the resist layer is washed away with the developer become exposed areas where the conductor layer is exposed, and the areas where the resist layer remains become masked areas where the conductor layer is masked.

[0120] The developer may be, for example, a sodium carbonate solution.

[0121] In the etching step, the conductive layer regions not masked by the resist layer, i.e., the exposed regions of the conductive layer, are removed by etching such as plasma etching, chemical etching, etc. Examples of etching solutions include a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and a ferric chloride solution.

[0122] In the removal step, the resist layer on the wiring conductor is removed. The removal can be performed using, for example, a stripping solution. After the removal, it is preferable to perform cleaning. Examples of the stripping solution include a sodium hydroxide solution.

[0123] The transfer sheet can be produced, for example, by a process of laminating an ultraviolet-curable adhesive layer onto a base layer to obtain an adhesive sheet, a process of laminating a conductor layer onto the ultraviolet-curable adhesive layer of the adhesive sheet to obtain a sheet with a conductor layer for the transfer sheet, and a process of etching the conductor layer of the sheet with a conductor layer for the transfer sheet into a predetermined pattern using photolithography technology to form a wiring conductor.

[0124] <Method for manufacturing a sheet with a conductor layer for a transfer sheet> In one embodiment, the sheet with a conductor layer for a transfer sheet includes a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer, and a conductor layer provided on the ultraviolet-curable pressure-sensitive adhesive layer. In one embodiment, the method for manufacturing a sheet with a conductor layer for a transfer sheet includes the steps of providing a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer, and providing a conductor layer on the exposed surface of the ultraviolet-curable pressure-sensitive adhesive layer. As described above, examples of the conductor layer include a conductor foil and a conductor plating film.

[0125] The method for providing the conductor foil is not particularly limited, and examples thereof include a method of directly applying a pressure-sensitive adhesive composition to the conductor foil, and a method of applying a pressure-sensitive adhesive composition for forming an ultraviolet-curable pressure-sensitive adhesive layer onto a substrate to form an ultraviolet-curable pressure-sensitive adhesive layer, and then laminating the formed ultraviolet-curable pressure-sensitive adhesive layer on the conductor foil.

[0126] The conductive plating film can be formed by, for example, a conventional plating method used in an additive process or a semi-additive process. For example, after a plating catalyst application process for adhering palladium to an ultraviolet-curable pressure-sensitive adhesive layer provided on a substrate is performed, the ultraviolet-curable pressure-sensitive adhesive layer is immersed in an electroless plating solution to deposit an electroless plating layer having a thickness of 0.3 to 1.5 μm, i.e., a conductive plating film, on the entire surface of the primer. If necessary, electrolytic plating can be further performed to adjust the required thickness. Any electroless plating solution can be used as the electroless plating solution, and there are no particular limitations. Conventional electrolytic plating methods can also be used, and there are no particular limitations. The conductive plating film may be a copper plating film from the standpoints of cost and resistance value.

[0127] The sheet with a conductor layer for transfer sheet can be produced, for example, by the method shown below.

[0128] In the first embodiment, a conductor layer is provided on the ultraviolet-curable adhesive layer of the adhesive sheet, and pressure treatment is performed in an autoclave. The pressure treatment in an autoclave is usually performed at a temperature of 10 to 50° C. and a pressure of 20 to 80 N / cm ２The pressure may be applied for about 5 to 60 minutes at a pressure of about 100 psi, but the optimum conditions can be determined appropriately depending on the composition of the adhesive composition used.

[0129] In the second embodiment, a conductor layer is provided on the ultraviolet-curable pressure-sensitive adhesive layer during the curing of the pressure-sensitive adhesive sheet, and the curing is continued. In this case, the conductor layer is laminated at a stage before the final gel fraction is reached during the process of adjusting the gel fraction of the pressure-sensitive adhesive layer in the curing step.

[0130] In the third embodiment, the adhesive composition is directly applied to the conductor layer to form an ultraviolet-curable adhesive layer, and then curing is performed.

[0131] These methods allow the interface between the ultraviolet-curable pressure-sensitive adhesive layer and the conductor layer to adhere tightly without any gaps, preventing the penetration of chemicals used in the subsequent etching process and allowing the formation of a good wiring conductor. By appropriately adjusting the lamination conditions, it is possible to adjust the balance between the adhesive strength of the ultraviolet-curable pressure-sensitive adhesive layer and the peelability after UV irradiation.

[0132] <Method for manufacturing wiring board> In one embodiment, a method for manufacturing a wiring board includes a transfer step of contacting the surface of a transfer sheet on which the wiring conductor is provided with an insulating sheet and transferring the wiring conductor to the insulating sheet. Examples of the insulating sheet include a heat-resistant fiber substrate impregnated with a thermosetting resin composition, a core substrate, a build-up substrate, and a flexible substrate. The core substrate, the build-up substrate, and the flexible substrate may be the same as those described above.

[0133] The form of the heat-resistant fiber substrate is not particularly limited, and examples thereof include woven fabrics and nonwoven fabrics. Examples of heat-resistant fibers include glass fibers, aramid fibers, and wholly aromatic polyester fibers. Examples of thermosetting resin compositions include resin compositions containing thermosetting resins such as epoxy resins, bismaleimide triazine resins, polyimide resins, fluororesins, phenolic resins, and allyl-modified polyphenylene ether resins. Preferably, a thermosetting resin that is liquid at room temperature is used. From the viewpoints of the adhesiveness of the transfer sheet and the releasability in the peeling process, it is preferable that the thermosetting resin composition contains an epoxy resin.

[0134] The wiring conductor can be transferred to the insulating sheet, for example, by the following method. The surface of the transfer sheet on which the wiring conductor is provided is placed on at least one main surface of the insulating sheet and they are pressed together. Next, UV irradiation is performed, and the base layer and the photocured adhesive layer of the transfer sheet are peeled off from the insulating sheet, thereby transferring the wiring conductor to the main surface of the insulating sheet. The light source and UV irradiation dose used for UV irradiation are the same as those described above.

[0135] A method for manufacturing a wiring board will be described in more detail below, taking as an example a wiring board in which insulating layers, which are cured products of heat-resistant fiber substrates impregnated with a thermosetting resin composition, and wiring conductors are alternately laminated, with the wiring conductors sandwiching the insulating layer between them electrically connected by conductor posts provided in through-holes formed in the insulating layer. Such a wiring board can be manufactured, for example, as follows: (a) A protective resin film is removably attached to both main surfaces of an insulating sheet in which a heat-resistant fiber substrate is impregnated with an uncured thermosetting resin composition. (b) Next, laser processing is performed on the insulating sheet with the protective resin film attached to form multiple through-holes that penetrate the insulating sheet together with the resin film. (c) Next, a conductive paste containing a conductor powder such as metal is filled into one of the through-holes by screen printing from above the resin film on one side of the insulating sheet. In this case, the resin film with the through-holes functions as a printing mask. (d) Next, the resin film is peeled off and removed from both main surfaces of the insulating sheet with the through-holes filled with the conductive paste. (e) Next, the transfer sheet is placed on at least one main surface of the insulating sheet so that the wiring conductor contacts and covers the end of the conductive paste, and they are pressed together to embed the wiring conductor into the main surface of the insulating sheet. (f) Next, UV irradiation is performed, and the base layer and the photo-cured adhesive layer of the transfer sheet are peeled off from the main surface of the insulating sheet with the embedded wiring conductor, thereby transferring the wiring conductor to the main surface of the insulating sheet. (g) Finally, multiple insulating sheets with the transferred wiring conductors are stacked, and heated and pressurized using a press to harden the insulating sheets and conductive paste, thereby obtaining a wiring board.

[0136] The above steps (a) to (g) are explained in more detail below. In step (a), an insulating sheet that will become the insulating layer of the wiring substrate and a resin film with an adhesive layer are first prepared. The thickness of the insulating sheet is, for example, 30 to 200 μm.

[0137] The thickness of the resin film is, for example, 5 to 25 μm. Examples of materials for the resin film include heat-resistant resins such as polyethylene terephthalate. One main surface of the resin film is coated with an adhesive layer. The adhesive layer is preferably an acrylic resin-based adhesive. The thickness of the adhesive layer is, for example, 3 to 7 μm.

[0138] Next, protective films are attached to both the upper and lower main surfaces of the insulating sheet via adhesive layers. Then, in (b), a plurality of through holes are formed in the insulating sheet with the resin films attached to the upper and lower surfaces via the adhesive layers. The through holes are formed, for example, by irradiating the insulating sheet with the resin films attached to the upper and lower surfaces via the adhesive layers with laser light from the top side.

[0139] Next, in (c), the through holes are filled with a conductive paste. For example, the through holes are filled by supplying the conductive paste onto the resin film on the upper surface and then sliding a hard rubber squeegee over the conductive paste. In this process, the resin film on the upper surface functions as a mask for filling the through holes with the conductive paste.

[0140] An exemplary conductive paste contains a metal powder made of an alloy of tin, silver, bismuth, and copper, and a triazine-based thermosetting resin such as triallyl cyanurate, triallyl isocyanurate, trisepoxypropyl isocyanurate, or tris(2-hydroxyethyl) isocyanurate. The conductive paste exhibits conductivity due to contact between the metal powder particles. The content of the metal powder is preferably 80 to 95 mass% relative to the total amount of the conductive paste. If the content of the metal powder is 80 mass% or more, the metal powder particles are more likely to contact each other, thereby reducing resistivity. If the content is 95 mass% or less, the viscosity of the conductive paste containing the metal powder and the triazine-based thermosetting resin is appropriate, resulting in good filling properties.

[0141] Next, in (d), the resin film is peeled off and removed together with the adhesive layer from both main surfaces of the insulating sheet.

[0142] Next, in (e), a transfer sheet is prepared, which includes a pressure-sensitive adhesive sheet having a base layer and an ultraviolet-curable pressure-sensitive adhesive layer provided on the base layer, and a wiring conductor partially provided on the ultraviolet-curable pressure-sensitive adhesive layer. The wiring conductor is releasably held on the ultraviolet-curable pressure-sensitive adhesive layer.

[0143] The transfer sheet is placed on at least one main surface of the insulating sheet so that the wiring conductor contacts and covers the end of the conductive paste, and these are pressed together at a temperature of 100 to 150°C and a pressure of 0.2 to 1.0 MPa, for example, to embed the wiring conductor into the main surface of the insulating sheet.

[0144] Next, in step (f), the transfer sheet is irradiated with UV light from the base layer side of the transfer sheet to photocure the ultraviolet-curable adhesive layer, and then the base layer of the transfer sheet is removed together with the photocure adhesive layer from above the insulating sheet and the wiring conductor, thereby transferring the wiring conductor so that it remains on the insulating sheet. By these operations, a plurality of insulating sheets to which the wiring conductor has been transferred are produced.

[0145] Next, in (g), the multiple insulating sheets are stacked one on top of the other in a predetermined arrangement and heated while being pressed, thereby thermally curing the thermosetting resin of the insulating sheets and the thermosetting resin of the conductive paste, thereby obtaining a wiring board in which insulating layers, which are cured products of heat-resistant fiber base materials impregnated with a thermosetting resin composition, and wiring conductors are alternately stacked, and the wiring conductors located above and below the insulating layers are electrically connected to each other by conductor posts provided in through holes formed in the insulating layers.

[0146] In one embodiment, the method for manufacturing a wiring board includes providing a sealing layer on the surface of the transfer sheet on which the wiring conductor is provided, and further includes providing a conductive path that penetrates the sealing layer so that a portion of the wiring conductor is connected to the conductive path.

[0147] A method for providing the sealing layer includes, for example, supplying a molten thermosetting resin composition such as a granular epoxy resin composition onto the upper surface of a transfer sheet so as to cover the wiring conductor, and then compression molding the molten thermosetting resin composition.

[0148] A method for providing a conductive path that penetrates the sealing layer includes, for example, providing a resist layer on the sealing layer, exposing the area where the conductive path is to be provided using photolithography technology, removing the exposed area by etching to provide a through hole, and forming a conductive post in the through hole.

[0149] <Adhesive Sheet> The adhesive sheet has a base layer and an ultraviolet-curable adhesive layer provided on the base layer.

[0150] (Substrate Layer) The substrate layer may be made of any known inorganic substrate, polymer sheet, or polymer film, and is not particularly limited. Examples of inorganic substrates include glass and glass cloth. Specific examples of polymer sheets and polymer films include polymer sheets and polymer films containing at least one of the following materials: polyolefins such as crystalline polypropylene, amorphous polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, very low-density polyethylene, low-density linear polyethylene, polybutene, and polymethylpentene; ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester (random or alternating) copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, polyurethanes, polyesters such as polyethylene terephthalate and polyethylene naphthalate; polycarbonates, polyimides, polyether ether ketones, polyetherimides, polyamides, wholly aromatic polyamides, polyphenylsulfide, aramids, fluororesins, polyvinyl chloride, polyvinylidene chloride, cellulose-based resins, silicone resins, and mixtures of these with plasticizers, and cured products obtained by crosslinking these by electron beam irradiation.

[0151] In particular, the substrate layer is preferably transparent, and the total light transmittance of the substrate layer is preferably 70% or more, more preferably 80% or more. From the viewpoint of heat resistance, the substrate layer preferably contains at least one selected from polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, and polyether ether ketone. For applications requiring flexibility, the substrate layer preferably contains at least one selected from polyolefin and polyvinyl chloride.

[0152] The thickness of the substrate layer is preferably 5 to 500 μm, more preferably 5 to 100 μm, and even more preferably 5 to 50 μm. If the thickness of the substrate layer is 5 μm or more, wrinkles and twisting of the pressure-sensitive adhesive sheet are suppressed. Therefore, when the pressure-sensitive adhesive sheet is used as a transfer sheet, disconnection of the wiring conductor is prevented and workability is good. If the thickness of the substrate layer is 500 μm or less, peelability is good. When the pressure-sensitive adhesive sheet is used as a transfer sheet, further, lamination properties and positioning accuracy in the transfer process are good.

[0153] (UV-curable adhesive layer) The UV-curable adhesive layer is a thermoset product of the adhesive composition described below. Because the adhesive layer is UV-curable, the adhesive sheet has good adhesive strength while protecting or temporarily fixing the surface of electronic components, and can be easily peeled from the adherend after the adhesive sheet is no longer needed without leaving any adhesive residue on the adherend. Because the adhesive layer is UV-curable, the adhesive sheet has good adhesive strength from the time when the wiring conductor is formed until it is transferred to the adherend, and is excellent in dimensional accuracy of the wiring conductor and positioning accuracy during transfer. After the wiring conductor is transferred, the adhesive strength of the adhesive layer is reduced by UV irradiation, allowing the adhesive sheet to be easily peeled from the adherend without leaving any adhesive residue on the adherend.

[0154] The conditions for heat curing are not particularly limited, but typically, the PSA composition is heat-cured by heat drying and / or curing after application. Heat drying conditions are typically 25 to 180°C, preferably 60 to 150°C, and typically 1 to 20 minutes, preferably 1 to 10 minutes. By performing heat drying within the above range, if the PSA composition contains a solvent, the solvent can be removed. The conditions for curing the heat-dried sheet in an oven for a certain period of time are not particularly limited, but typically 25 to 100°C, preferably 30 to 80°C, and typically 1 to 30 days, preferably 1 to 14 days. By curing under the above conditions, the gel fraction of the PSA layer can be adjusted to the desired range.

[0155] The thickness of the ultraviolet-curable pressure-sensitive adhesive layer is preferably 1 μm or more, more preferably 5 μm or more. The thickness of the ultraviolet-curable pressure-sensitive adhesive layer is preferably 300 μm or less, more preferably 100 μm or less, and even more preferably 30 μm or less. The thickness of the ultraviolet-curable pressure-sensitive adhesive layer is preferably 1 to 300 μm, more preferably 5 to 100 μm, and even more preferably 5 to 30 μm. When the thickness of the ultraviolet-curable pressure-sensitive adhesive layer is 1 μm or more, the ultraviolet-curable pressure-sensitive adhesive layer has sufficient adhesive strength, wrinkles and twists of the pressure-sensitive adhesive sheet are suppressed, and workability is good. Therefore, when the pressure-sensitive adhesive sheet is used as a transfer sheet, breakage of the wiring conductor is prevented. When the thickness of the ultraviolet-curable pressure-sensitive adhesive layer is 1 μm or more, transfer defects are suppressed when the pressure-sensitive adhesive sheet is used as a transfer sheet. When the thickness of the ultraviolet-curable pressure-sensitive adhesive layer is 300 μm or less, transfer of the pressure-sensitive adhesive layer to the adherend can be suppressed. If the thickness of the ultraviolet-curable adhesive layer is 300 μm or less, when the adhesive sheet is used as a transfer sheet, the lamination property and positioning accuracy in the transfer step are good.

[0156] <Adhesive Composition> The adhesive composition contains a (meth)acrylic resin (A) containing structural units of the following formulae (1) to (3), and optionally the following formula (4).

[0157] (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.

[0158] The pressure-sensitive adhesive composition preferably contains a photopolymerization initiator (B) and a crosslinking agent (C) in addition to the (meth)acrylic resin (A). By containing the photopolymerization initiator (B) and the crosslinking agent (C), it is possible to impart both heat-curing and photo-curing properties to the pressure-sensitive adhesive composition.

[0159] ((Meth)acrylic resin (A)) [Structural unit of formula (1)] The (meth)acrylic resin (A) contains a structural unit of the following formula (1): The structural unit of formula (1) contributes to imparting adhesive strength.

[0160] In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms. ２ is preferably a linear or branched chain alkyl group, more preferably a linear or branched chain alkyl group having 1 to 10 carbon atoms, and even more preferably a linear or branched chain alkyl group having 4 to 8 carbon atoms. The structural unit of formula (1) does not have to be of one type. R of each structural unit １ may be different from each other, and R ２ may also be different.

[0161] Specific examples of monomers that lead to the structural unit of formula (1) include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and decyl (meth)acrylate. Among these, from the viewpoints of ease of synthesis of the (meth)acrylic resin (A), adhesive properties, and releasability after UV irradiation, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and from the viewpoint of releasability after UV irradiation, 2-ethylhexyl (meth)acrylate is more preferred.

[0162] The monomers which derive the structural unit of formula (1) may be used alone or in combination of two or more.

[0163] The ratio of the structural units of formula (1) to all structural units of the (meth)acrylic resin (A) is preferably 50 to 99 mol%, more preferably 60 to 98 mol%, and even more preferably 70 to 95 mol%. When the structural units of formula (1) are 50 mol% or more, sufficient adhesiveness to the adherend can be obtained before UV irradiation. When the structural units of formula (1) are 99 mol% or less, a sufficient proportion of the structural units of formulas (2) and (3), described below, can be ensured, thereby achieving sufficient photocurability as a pressure-sensitive adhesive composition and, ultimately, the desired releasability after UV irradiation.

[0164] [Structural Unit of Formula (2)] The (meth)acrylic resin (A) contains a structural unit of the following formula (2). This allows the hydroxy group moiety to crosslink with the crosslinking agent (C), resulting in a UV-curable pressure-sensitive adhesive layer being formed by thermal curing. Furthermore, the ethylenically unsaturated group introduced into the side chain imparts photocurability to the pressure-sensitive adhesive composition, reducing adhesive strength after UV irradiation and improving releasability from an adherend.

[0165] In formula (2), R ３ represents a hydrogen atom or a methyl group, R ４represents a group having a hydroxy group on a carbon atom and having a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom. From the viewpoint of heat resistance, the carbon atom having a hydroxy group preferably has one hydrogen atom, and the carbon atom having a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid preferably has one or two hydrogen atoms. The structural unit of formula (2) does not have to be of one type. The R of each structural unit ３ may be different from each other, and R ４ may also be different.

[0166] R ４ Specific examples of the residue obtained by removing a hydrogen atom from the carboxy group of an unsaturated monocarboxylic acid constituting the formula (A) include residues obtained by removing a hydrogen atom from the carboxy group of unsaturated monocarboxylic acids such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, crotonic acid, propiolic acid, cinnamic acid, monomethyl maleate, monoethyl maleate, monoisopropyl maleate, monomethyl fumarate, and monoethyl itaconate. Among these, from the viewpoint of ease of synthesis of the (meth)acrylic resin (A), a residue obtained by removing a hydrogen atom from the carboxy group of (meth)acrylic acid, i.e., a (meth)acryloyloxy group, is preferred.

[0167] Specific examples of the structural unit of formula (2) include structural units of the following formulae (2-1-1) and (2-1-2): (In formula (2-1-1), R ９ represents a hydrogen atom or a methyl group, R １０ represents a divalent linking group, R １１ , R １２ , R １４ and R １５ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R １３ represents a single bond or a divalent linking group, R １６ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, —COOR (wherein R represents an alkyl group having 1 to 6 carbon atoms), or a phenyl group. (In formula (2-1-2), R１７ represents a hydrogen atom or a methyl group, R １８ represents a divalent linking group, R １９ , R ２０ , R ２２ and R ２３ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R ２１ represents a single bond or a divalent linking group, R ２４ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, —COOR (wherein R represents an alkyl group having 1 to 6 carbon atoms), or a phenyl group.

[0168] In formula (2-1-1), R １０ The divalent linking group represented by is an alkylene group having 1 to 20 carbon atoms, -R ５５ -O-R ５６ - (wherein, R ５５ and R ５６ R each independently represents an alkylene group having 1 to 10 carbon atoms. １０ Examples of the alkylene group having 1 to 20 carbon atoms represented by R include a methylene group, an ethylene group, and a butylene group. Among these, from the viewpoint of adhesion to an adherend, an alkylene group having 1 to 10 carbon atoms is preferred, and a methylene group and an ethylene group are more preferred. ５５ and R ５６ Examples of the alkylene group having 1 to 10 carbon atoms represented by R include a methylene group, an ethylene group, and a butylene group. Among these, an alkylene group having 1 to 6 carbon atoms is preferred from the viewpoint of photocurability. １０ is an alkylene group having 1 to 10 carbon atoms, and -R ５５ -O-R ５６ - is preferred, and a methylene group, an ethylene group, and -(CH ２ ) ｎ -O-(CH ２ ) ｙ - (n is an integer of 1 to 6, and y is an integer of 1 or 2) is more preferred. n is preferably an integer of 2 to 6, and y is preferably an integer of 1 or 2.

[0169] In formula (2-1-1), R １１ , R １２ , R １４ and R １５R each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. １１ , R １２ , R １４ and R １５ The alkyl group having 1 to 6 carbon atoms represented by R is, for example, a methyl group. １１ and R １２ are preferably hydrogen atoms. １４ is preferably a hydrogen atom or a methyl group. １５ is preferably a hydrogen atom.

[0170] In formula (2-1-1), R １３ represents a single bond or a divalent linking group. Examples of the divalent linking group include an alkylene group having 1 to 20 carbon atoms, -R ５７ -O-R ５８ - (wherein, R ５７ and R ５８ each independently represents an alkylene group having 1 to 10 carbon atoms; ５９ -CO-O-R ６０ -CO-, -R ６１ -CO-O-R ６２ - (wherein, R ５９ ~R ６２ R each independently represents an alkylene group having 1 to 10 carbon atoms. １３ Examples of the alkylene group having 1 to 20 carbon atoms represented by R include a methylene group, an ethylene group, and a butylene group. １３ From the viewpoint of photocurability, a single bond and an alkylene group having 1 to 6 carbon atoms are preferred, and a single bond is more preferred.

[0171] In formula (2-1-1), R １６ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, -COOR (wherein R represents an alkyl group having 1 to 6 carbon atoms), or a phenyl group. １６ Examples of the alkyl group having 1 to 6 carbon atoms represented by R include a methyl group and an ethyl group. １６ is preferably a hydrogen atom.

[0172] In formula (2-1-2), R１８ ~R ２４ Specific and preferred examples of R in formula (2-1-1) １０ ~R １６ and the same respectively.

[0173] A specific example of a method for deriving the structural unit of formula (2-1-1) or formula (2-1-2) is to introduce a structural unit of formula (4-1) described below, and then react the epoxy group of formula (4-1) with the carboxy group of an unsaturated monocarboxylic acid to introduce a residue obtained by removing a hydrogen atom from the carboxy group of the unsaturated monocarboxylic acid. The monomer that derives the structural unit of formula (4-1) may be used alone or in combination of two or more kinds, and the unsaturated monocarboxylic acids to be reacted may be used alone or in combination of two or more kinds.

[0174] Specific examples of the structural unit of formula (2) include the structural unit of formula (2-2) below. (In formula (2-2), R ３７ represents a hydrogen atom or a methyl group, R ３８ represents a single bond or a divalent linking group, R ３９ , R ４１ and R ４２ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R ４０ represents a single bond or a divalent linking group, R ４３ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, —COOR (wherein R represents an alkyl group having 1 to 6 carbon atoms), or a phenyl group, and X1 represents a saturated hydrocarbon ring.

[0175] R ３８ Examples of the divalent linking group represented by are alkylene groups having 1 to 20 carbon atoms, -R ６３ -O-R ６４ - (wherein, R ６３ and R ６４ each independently represents an alkylene group having 1 to 10 carbon atoms; ６５ -O- (wherein, R ６５ represents an alkylene group having 1 to 10 carbon atoms, —COO—, and combinations thereof. ３８Examples of alkylene groups having 1 to 20 carbon atoms constituting R include methylene, ethylene, butylene, and cyclohexylene groups. Among these, from the viewpoint of adhesion to the adherend, alkylene groups having 1 to 10 carbon atoms are preferred, and methylene and ethylene groups are more preferred. ６３ and R ６４ Examples of the alkylene group having 1 to 10 carbon atoms represented by R include a methylene group, an ethylene group, and a butylene group. Among these, an alkylene group having 1 to 6 carbon atoms is preferred from the viewpoint of photocurability. ６５ Examples of the alkylene group having 1 to 10 carbon atoms represented by R include a methylene group, an ethylene group, and a butylene group. Among these, an alkylene group having 1 to 6 carbon atoms is preferred from the viewpoint of photocurability. ３８ Examples of the -R include a single bond, an alkylene group having 1 to 10 carbon atoms, and -R ６５ -O- is preferred, and a single bond, a methylene group, an ethylene group, and -(CH ２ ) ｍ -O- (where m is an integer of 1 to 3) is more preferred.

[0176] In formula (2-2), R ３９ , R ４１ and R ４２ R each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ３９ , R ４１ and R ４２ The alkyl group having 1 to 6 carbon atoms represented by R is, for example, a methyl group. ３９ is preferably a hydrogen atom. ４１ is preferably a hydrogen atom or a methyl group. ４２ is preferably a hydrogen atom.

[0177] In formula (2-2), R ４０ and R ４３ Specific and preferred examples of R in formula (2-1-1) １３ and R １６ and the same respectively.

[0178] In formula (2-2), X1 represents a saturated hydrocarbon ring. The saturated hydrocarbon ring preferably has 4 to 20 carbon atoms, more preferably 5 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms. The saturated hydrocarbon ring may be a monocyclic ring or a condensed ring. Preferred saturated hydrocarbon rings are a cyclohexyl group, a cyclopentyl group, and a tricyclodecanyl group.

[0179] From the viewpoint of heat resistance, the structural unit of formula (2) preferably contains a structural unit of formula (2-2).

[0180] A specific example of a method for deriving the structural unit of formula (2-2) is to introduce a structural unit of formula (4-2) described below, and then react the epoxy group of formula (4-2) with the carboxy group of an unsaturated monocarboxylic acid to introduce a residue formed by removing a hydrogen atom from the carboxy group of the unsaturated monocarboxylic acid. The monomer that derives the structural unit of formula (4-2) may be used alone or in combination of two or more kinds, and the unsaturated monocarboxylic acids to be reacted may be used alone or in combination of two or more kinds.

[0181] The ratio of the structural unit of formula (2) to all structural units of the (meth)acrylic resin (A) is preferably 0.1 to 40 mol%, more preferably 0.5 to 18 mol%, and even more preferably 1 to 15 mol%. When the structural unit of formula (2) is 0.1 mol% or more, the thermosetting property of the pressure-sensitive adhesive composition is sufficient. As a result, sufficient adhesive strength to the adherend and cohesive strength of the pressure-sensitive adhesive composition are obtained. When the structural unit of formula (2) is 40 mol% or less, a sufficient proportion of the structural unit of formula (1) can be ensured, and good adhesive strength can be obtained.

[0182] [Structural Unit of Formula (3)] The (meth)acrylic resin (A) contains a structural unit of the following formula (3): The two ethylenically unsaturated groups introduced into the side chains impart photocurability to the pressure-sensitive adhesive composition, thereby reducing the adhesive strength of the pressure-sensitive adhesive layer after UV irradiation and improving releasability from an adherend.

[0183] In formula (3), R ５ represents a hydrogen atom or a methyl group, R ６represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid. From the viewpoint of heat resistance, each carbon atom having a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid preferably has one or two hydrogen atoms. The structural unit of formula (3) does not have to be of one type. The R of each structural unit ５ may be different from each other, and R ６ may also be different.

[0184] R ６ Specific examples of the residue obtained by removing a hydrogen atom from the carboxy group of an unsaturated monocarboxylic acid constituting the formula (A) include residues obtained by removing a hydrogen atom from the carboxy group of unsaturated monocarboxylic acids such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, crotonic acid, propiolic acid, cinnamic acid, monomethyl maleate, monoethyl maleate, monoisopropyl maleate, monomethyl fumarate, and monoethyl itaconate. Among these, from the viewpoint of ease of synthesis of the (meth)acrylic resin (A), a residue obtained by removing a hydrogen atom from the carboxy group of (meth)acrylic acid, i.e., a (meth)acryloyloxy group, is preferred.

[0185] Specific examples of the structural unit of formula (3) include the structural unit of formula (3-1) below. (In formula (3-1), R ２５ represents a hydrogen atom or a methyl group, R ２６ represents a divalent linking group, R ２７ , R ２８ , R ３０ , R ３１ , R ３４ and R ３５ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R ２９ and R ３３ each independently represents a single bond or a divalent linking group, R ３２ and R ３６each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, —COOR (wherein R represents an alkyl group having 1 to 6 carbon atoms), or a phenyl group.

[0186] In formula (3-1), R ２６ ~R ３２ Specific and preferred examples of R in formula (2-1-1) １０ ~R １６ In formula (3-1), R ３３ ~R ３６ Specific and preferred examples of R in formula (2-1-1) １３ ~R １６ and the same respectively.

[0187] A specific method for deriving the structural unit of formula (3-1) includes reacting an unsaturated monocarboxylic acid anhydride with the hydroxy group of the structural unit of formula (2-1-1) or formula (2-1-2) to introduce a residue obtained by removing a hydrogen atom from the carboxy group of the unsaturated monocarboxylic acid. The unsaturated monocarboxylic acid anhydride to be reacted may be used alone or in combination of two or more. Examples of the unsaturated monocarboxylic acid anhydride include (meth)acrylic anhydride.

[0188] Specific examples of the structural unit of formula (3) include the structural unit of formula (3-2) below. (In formula (3-2), R ４４ represents a hydrogen atom or a methyl group, R ４５ represents a single bond or a divalent linking group, R ４６ , R ４８ , R ４９ , R ５２ and R ５３ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R ４７ and R ５１ each independently represents a single bond or a divalent linking group, R ５０ and R ５４ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, —COOR (wherein R represents an alkyl group having 1 to 6 carbon atoms), or a phenyl group, and X2 represents a saturated hydrocarbon ring.

[0189] In formula (3-2), R４５ ~R ５０ Specific and preferred examples of R in formula (2-2) ３８ ~R ４３ In formula (3-2), R ５１ ~R ５４ Specific and preferred examples of R in formula (2-2) ４０ ~R ４３ Specific examples and suitable examples of X2 in formula (3-2) are the same as those of X1 in formula (2-2).

[0190] A specific method for deriving the structural unit of formula (3-2) is to react an unsaturated monocarboxylic acid anhydride with the hydroxy group of the structural unit of formula (2-2) to introduce a residue obtained by removing a hydrogen atom from the carboxy group of the unsaturated monocarboxylic acid. The unsaturated monocarboxylic acid anhydride to be reacted may be used alone or in combination of two or more. Examples of the unsaturated monocarboxylic acid anhydride include (meth)acrylic anhydride.

[0191] The ratio of the structural unit of formula (3) to all structural units of the (meth)acrylic resin (A) is preferably 0.1 to 30 mol%, more preferably 0.2 to 28 mol%, and even more preferably 0.5 to 26 mol%. When the structural unit of formula (3) is 0.1 mol% or more, a sufficient effect of improving photocurability can be obtained. As a result, the adhesive strength of the pressure-sensitive adhesive layer can be sufficiently reduced upon UV irradiation, improving releasability from the adherend. When the structural unit of formula (3) is 30 mol% or less, adhesive strength is good.

[0192] [Structural Unit of Formula (4)] The (meth)acrylic resin (A) may contain a structural unit of the following formula (4). It is preferable to contain a certain amount of the structural unit of the following formula (4) from the viewpoint of reducing residual monomers remaining during the synthesis of the (meth)acrylic resin (A), i.e., residual unsaturated monocarboxylic acid and unsaturated monocarboxylic anhydride used to introduce the structural units of the formulae (2) and (3). On the other hand, it is preferable to reduce the content of the structural unit of formula (4) as much as possible from the viewpoint of reducing deterioration over time of the pressure-sensitive adhesive composition.

[0193] In formula (4), R７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group. The structural unit of formula (4) does not have to be of one type. ７ may be different from each other, and R ８ may also be different.

[0194] Specific examples of the structural unit of formula (4) include structural units of the following formulae (4-1) and (4-2): (In formula (4-1), R ６６ represents a hydrogen atom or a methyl group, R ６７ represents a divalent linking group, R ６８ and R ６９ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and in formula (4-2), R ７０ represents a hydrogen atom or a methyl group, R ７１ represents a single bond or a divalent linking group, R ７２ represents an alicyclic epoxy group.

[0195] In formula (4-1), R ６７ , R ６８ , and R ６９ Specific and preferred examples of R in formula (2-1-1) １０ , R １１ , and R １２ and the same respectively.

[0196] Specific examples of the monomer from which the structural unit of formula (4-1) is derived include glycidyl (meth)acrylate, hydroxybutyl (meth)acrylate glycidyl ether, etc. Glycidyl (meth)acrylate and hydroxybutyl (meth)acrylate glycidyl ether are preferred from the viewpoint of ease of reaction with unsaturated monocarboxylic acid when deriving the structural units of formula (2-1-1), formula (2-1-2), and formula (3-1).

[0197] The monomers which lead to the structural unit of formula (4-1) may be used alone or in combination of two or more.

[0198] In formula (4-2), R ７１ Specific and preferred examples of R in formula (2-2) ３８ is the same as:

[0199] In formula (4-2), R ７２ represents an alicyclic epoxy group, and specific examples thereof include a 3,4-epoxycyclohexyl group, an epoxycyclopentyl group, a 3,4-epoxytricyclo[5.2.1.0] group, ２，６ ] decanyl group and the like.

[0200] Specific examples of the monomer from which the structural unit of formula (4-2) is derived include 3,4-epoxycyclohexylmethyl(meth)acrylate (for example, Cyclomer A200 and M100, manufactured by Daicel Corporation), 3,4-epoxytricyclo[5.2.1.0 ２，６ ]decaneoxyethyl acrylate, (meth)acrylic acid esters of lactone adducts having a 3,4-epoxycyclohexyl group, mono(meth)acrylic acid esters of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, epoxidized products of dicyclopentenyl (meth)acrylate, and epoxidized products of dicyclopentenyloxyethyl (meth)acrylate. Among these, 3,4-epoxycyclohexylmethyl (meth)acrylate is preferred from the viewpoint of ease of reaction with unsaturated monocarboxylic acid when deriving structural units of formula (2-2) and formula (3-2). Monomers deriving structural units of formula (4-2) may be used alone or in combination of two or more.

[0201] The proportion of the structural units of formula (4) relative to all structural units of the (meth)acrylic resin (A) is preferably 0 to 10 mol %, more preferably 0 to 5 mol %, and even more preferably 0 to 1 mol %. When the structural units of formula (4) are 10 mol % or less, sufficient heat resistance and storage stability are obtained, and the adhesive strength is sufficiently reduced after UV irradiation, allowing peeling without contaminating the adherend.

[0202] Based on all structural units of the (meth)acrylic resin (A), the total proportion of structural units of formulas (2) to (4) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more. Based on all structural units of the (meth)acrylic resin (A), the total proportion of structural units of formulas (2) to (4) is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less. Based on all structural units of the (meth)acrylic resin (A), the total proportion of structural units of formulas (2) to (4) is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, and even more preferably 5 to 30 mol%. When the total proportion of structural units of formulas (2) to (4) is 1 mol% or more, sufficient photocurability and desired releasability after UV irradiation can be obtained. When the total proportion of structural units of formulas (2) to (4) is 50 mol% or less, the adhesive strength as a pressure-sensitive adhesive sheet is good.

[0203] The total proportion of the structural units of formulas (2) and (3) relative to the total of the structural units of formulas (2) to (4) is preferably 50 mol% or more, more preferably 55 mol% or more, and even more preferably 60 mol% or more. The total proportion of the structural units of formulas (2) and (3) relative to the total of the structural units of formulas (2) to (4) is preferably 100 mol% or less, more preferably 95 mol% or less, and even more preferably 90 mol% or less. The total proportion of the structural units of formulas (2) and (3) relative to the total of the structural units of formulas (2) to (4) is preferably 50 to 100 mol%, more preferably 55 to 95 mol%, and even more preferably 60 to 90 mol%. When the total proportion of the structural units of formulas (2) and (3) is 50 mol% or more, sufficient photocurability and desired releasability after UV irradiation can be obtained.

[0204] [Physical Properties of (Meth)acrylic Resin (A)] The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is preferably 350 g / mol or more, more preferably 400 g / mol or more, and even more preferably 450 g / mol or more. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is preferably 4000 g / mol or less, more preferably 3000 g / mol or less, and even more preferably 2000 g / mol or less. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is preferably 350 to 4000 g / mol, more preferably 400 to 3000 g / mol, and even more preferably 450 to 2000 g / mol. When the ethylenically unsaturated group equivalent is 350 g / mol or more, the adhesive strength as a pressure-sensitive adhesive sheet is good. When the ethylenically unsaturated group equivalent is 4000 g / mol or less, the adhesion before UV irradiation is good, sufficient photocurability, and desired releasability after UV irradiation can be obtained.

[0205] In this specification, the ethylenically unsaturated group equivalent of a (meth)acrylic resin is the mass (g / mol) of the (meth)acrylic resin per mole of ethylenically unsaturated bond. The ethylenically unsaturated group equivalent of a (meth)acrylic resin is calculated from the amount of halogen bonded to the (meth)acrylic resin. The amount of halogen bonded to the (meth)acrylic resin is evaluated in accordance with JIS K 0070:1992.

[0206] The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably −80° C. or higher, more preferably −70° C. or higher, and even more preferably −65° C. or higher. The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably 0° C. or lower, more preferably −10° C. or lower, and even more preferably −20° C. or lower. The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably −80° C. to 0° C., more preferably −70° C. to −10° C., and even more preferably −65° C. to −20° C. If the glass transition temperature is −80° C. or higher, the adhesive strength as a pressure-sensitive adhesive sheet is good. If the glass transition temperature is 0° C. or lower, the adhesion before UV irradiation is good.

[0207] In this specification, the term "glass transition temperature (Tg)" refers to the endothermic onset temperature due to glass transition observed when a 10 mg sample is collected and subjected to differential scanning calorimetry using a differential scanning calorimeter (DSC) while changing the temperature of the sample from -100°C to 200°C at a heating rate of 10°C / min. When two or more endothermic onset temperatures are observed, Tg is the simple average of the two or more endothermic onset temperatures.

[0208] The weight average molecular weight of the (meth)acrylic resin (A) is preferably 100,000 or more, more preferably 200,000 or more, and even more preferably 300,000 or more. The weight average molecular weight of the (meth)acrylic resin (A) is preferably 1,000,000 or less, more preferably 900,000 or less, and even more preferably 800,000 or less. The weight average molecular weight of the (meth)acrylic resin (A) is preferably 100,000 to 1,000,000, more preferably 200,000 to 900,000, and even more preferably 300,000 to 800,000. If the weight average molecular weight is 100,000 or more, the coagulation properties before UV irradiation are good. If the weight average molecular weight is 1,000,000 or less, the handleability during coating is good.

[0209] In this specification, the "weight average molecular weight" refers to a value measured using gel permeation chromatography (GPC) at room temperature (23°C) under the following conditions and determined using a standard polystyrene calibration curve: Apparatus: Shodex™ GPC-101 (Resonac Inc.) Column: Shodex™ LF-804 (Resonac Inc.) Column temperature: 40°C Sample: 0.2% by mass of sample in tetrahydrofuran Flow rate: 1 mL / min Eluent: tetrahydrofuran Detector: Shodex™ RI-71S (Resonac Inc.)

[0210] The hydroxyl value of the (meth)acrylic resin (A) is preferably 1 mgKOH / g or more, more preferably 2 mgKOH / g or more, and even more preferably 3 mgKOH / g or more. The hydroxyl value of the (meth)acrylic resin (A) is preferably 60 mgKOH / g or less, more preferably 50 mgKOH / g or less, and even more preferably 40 mgKOH / g or less. The hydroxyl value of the (meth)acrylic resin (A) is preferably 1 to 60 mgKOH / g, more preferably 2 to 50 mgKOH / g, and even more preferably 3 to 40 mgKOH / g. When the hydroxyl value is 1 mgKOH / g or more, the desired cohesive strength can be obtained when reacted with the crosslinking agent (C). When the hydroxyl value is 60 mgKOH / g or less, the peelability after UV irradiation is good.

[0211] In this specification, the hydroxyl value is the mass (mg) of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of resin is acetylated in accordance with JIS K 0070:1992.

[0212] [Method for producing (meth)acrylic resin (A)] The (meth)acrylic resin (A) can be obtained, for example, by the following steps: (i) polymerizing a monomer having an epoxy group with another monomer to obtain a copolymer; (ii) adding an unsaturated monocarboxylic acid to the epoxy group of the copolymer; and (iii) adding an unsaturated monocarboxylic anhydride to a hydroxy group formed by ring-opening of the epoxy group by the addition reaction of the step (ii), and simultaneously adding the unsaturated monocarboxylic acid derived from the liberated unsaturated monocarboxylic anhydride to the remaining epoxy group.

[0213] [Step (i) of polymerizing monomers to obtain a copolymer] As the polymerization method, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, an alternating copolymerization method, etc. Among these polymerization methods, in consideration of the addition reactions in steps (ii) and (iii), it is preferable to use a solution polymerization method in terms of ease of reaction.

[0214] As the monomer, alkyl (meth)acrylate, epoxy group-containing (meth)acrylate, and optionally other monomers can be used.

[0215] (Alkyl (meth)acrylate) The alkyl (meth)acrylate is not particularly limited as long as it is a monomer that leads to the structural unit of formula (1). Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, and the like. Among these, from the viewpoints of ease of synthesis of the (meth)acrylic resin (A), adhesive properties, and releasability after UV irradiation, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and from the viewpoint of releasability after UV irradiation, 2-ethylhexyl (meth)acrylate is more preferred. The alkyl (meth)acrylates may be used alone or in combination of two or more.

[0216] (Epoxy Group-Containing (Meth)acrylate) The epoxy group-containing (meth)acrylate is not particularly limited as long as it is a monomer that leads to the structural unit of formula (4). Specific examples thereof include glycidyl (meth)acrylate, hydroxybutyl (meth)acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl (meth)acrylate (e.g., Cyclomer A200 and M100, Daicel Corporation), 3,4-epoxytricyclo[5.2.1.0] ２，６ ]decaneoxyethyl acrylate, (meth)acrylic acid esters of lactone adducts having a 3,4-epoxycyclohexyl group, mono(meth)acrylic acid esters of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, epoxidized products of dicyclopentenyl (meth)acrylate, and epoxidized products of dicyclopentenyloxyethyl (meth)acrylate. Among these, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and hydroxybutyl (meth)acrylate glycidyl ether are preferred from the viewpoint of ease of reaction with unsaturated monocarboxylic acids. The epoxy group-containing (meth)acrylates may be used alone or in combination of two or more.

[0217] (Other Monomers) The other monomers are not particularly limited as long as they are monomers that do not have a carboxy group, that lead to structural units other than those of formulas (1) to (4), and that are copolymerizable with the alkyl (meth)acrylates and epoxy group-containing (meth)acrylates. Specific examples include alicyclic ring-containing (meth)acrylates, aromatic ring-containing (meth)acrylates, hydroxyl group-containing (meth)acrylates, and amide group-containing (meth)acrylates.

[0218] Examples of the alicyclic ring-containing (meth)acrylate include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, norbornyl (meth)acrylate, 5-ethylnorbornyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate.

[0219] Examples of aromatic ring-containing (meth)acrylates include benzyl (meth)acrylate, triphenylmethyl (meth)acrylate, phenyl (meth)acrylate, cumyl (meth)acrylate, 4-phenoxyphenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol mono(meth)acrylate, biphenyloxyethyl (meth)acrylate, naphthalene (meth)acrylate, and anthracene (meth)acrylate.

[0220] Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0221] Examples of the amide group-containing (meth)acrylate include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and anthracenyl(meth)acrylamide.

[0222] The content of alkyl (meth)acrylate in all monomers is preferably 50 to 99 mol %, more preferably 60 to 98 mol %, and even more preferably 70 to 95 mol %.

[0223] The content of the epoxy group-containing (meth)acrylate in all monomers is preferably 1 to 50 mol %, more preferably 2 to 40 mol %, and even more preferably 5 to 30 mol %.

[0224] (Radical Polymerization Initiator) The polymerization is preferably carried out in the presence of a radical polymerization initiator. Examples of the radical polymerization initiator include ordinary organic radical polymerization initiators, and specific examples thereof include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), and azo-based polymerization initiators such as dimethyl-2,2'-azobis(2-methylpropionate); and oil-soluble polymerization initiators such as peroxide-based polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane.

[0225] The radical polymerization initiators may be used alone or in combination of two or more.

[0226] The amount of the radical polymerization initiator used is preferably 0.001 to 5 parts by mass, more preferably 0.005 to 3 parts by mass, and even more preferably 0.01 to 1 part by mass, relative to 100 parts by mass of the total amount of the monomers.

[0227] (Solvent) As the solvent used in solution polymerization, a common solvent can be used. Examples of the solvent include esters such as ethyl acetate, propyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and benzene; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol, propylene glycol, and dipropylene glycol; glycol ethers such as methyl cellosolve, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether; and glycol esters such as ethylene glycol diacetate and propylene glycol monomethyl ether acetate. The solvents may be used alone or in combination of two or more.

[0228] (Reaction Conditions) The polymerization reaction temperature varies depending on the type of radical polymerization initiator used, but is usually 30° C. to 130° C., preferably 40° C. to 120° C., and more preferably 50° C. to 110° C. If the temperature during polymerization is 30° C. or higher, a sufficient reaction rate can be obtained.

[0229] The polymerization reaction time varies depending on the types of monomers and radical polymerization initiators used, but is usually 3 to 30 hours, preferably 4 to 20 hours, and more preferably 5 to 15 hours. When the reaction time is 3 hours or more, a copolymer can be produced from the monomers with an appropriate degree of polymerization, and when the reaction time is 30 hours or less, production can be carried out efficiently.

[0230] [Step (ii) of adding an unsaturated monocarboxylic acid to an epoxy group of the copolymer, and step (iii) of adding an unsaturated monocarboxylic acid anhydride] Steps (ii) and (iii) may be performed in this order or simultaneously. From the viewpoint of ease of operation, it is preferable to perform steps (ii) and (iii) simultaneously.

[0231] (Unsaturated Monocarboxylic Acid) The unsaturated monocarboxylic acid is not particularly limited as long as it is a monocarboxylic acid having an ethylenically unsaturated group. Specific examples thereof include (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, crotonic acid, propiolic acid, cinnamic acid, monomethyl maleate, monoethyl maleate, monoisopropyl maleate, monomethyl fumarate, and monoethyl itaconate. Among these, (meth)acrylic acid is preferred from the viewpoint of ease of synthesis of the (meth)acrylic resin (A). The unsaturated monocarboxylic acid may be used alone or in combination of two or more.

[0232] (Unsaturated monocarboxylic acid anhydride) The unsaturated monocarboxylic acid anhydride is not particularly limited as long as it is a monocarboxylic acid anhydride having an ethylenically unsaturated group. A specific example thereof is (meth)acrylic anhydride. The unsaturated monocarboxylic acid anhydride may be used alone or in combination of two or more kinds.

[0233] The addition rate of the unsaturated monocarboxylic acid relative to the epoxy groups derived from the epoxy group-containing (meth)acrylate present in the copolymer is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. If the addition rate is 50% or more, good releasability can be obtained after UV irradiation. From the viewpoint of heat resistance, a higher addition rate is preferable, and in one embodiment, the addition rate of the unsaturated monocarboxylic acid relative to the epoxy groups derived from the epoxy group-containing (meth)acrylate present in the copolymer is 100%. The upper limit of the addition rate may be, for example, 99% or 98%. The addition rate of the unsaturated monocarboxylic acid relative to the epoxy groups derived from the epoxy group-containing (meth)acrylate present in the copolymer is calculated from the charged amount.

[0234] The ratio of unsaturated monocarboxylic acid to unsaturated monocarboxylic anhydride is preferably 5 to 130 mol, more preferably 10 to 120 mol, and even more preferably 15 to 110 mol, of unsaturated monocarboxylic acid per 100 mol of unsaturated monocarboxylic anhydride. When the ratio of unsaturated monocarboxylic acid is 130 mol or less per 100 mol of unsaturated monocarboxylic anhydride, adhesion to an adherend is improved. When the ratio of unsaturated monocarboxylic acid is 5 mol or more per 100 mol of unsaturated monocarboxylic anhydride, releasability after UV irradiation is improved.

[0235] (Catalyst) In the addition reaction in steps (ii) and (iii), a known catalyst can be used as necessary. The catalyst can be any known catalyst, and is not particularly limited, but examples thereof include triphenylphosphine, tri(p-tolyl)phosphine, tris(2,6-dimethoxyphenyl)phosphine, etc. The catalyst may be used alone or in combination of two or more.

[0236] When a catalyst is used, the amount of catalyst used is preferably 2.5 to 10 mol, more preferably 3.0 to 9.0 mol, and even more preferably 3.5 to 8.0 mol, per 100 mol of the epoxy group-containing (meth)acrylate used in producing the copolymer. If the amount of catalyst used is 2.5 mol or more, the addition reaction can be promoted. On the other hand, if the amount of catalyst used is 10 mol or less, gelation during the addition reaction can be suppressed.

[0237] (Polymerization inhibitor) In the addition reaction in steps (ii) and (iii), a known polymerization inhibitor can be used as necessary. The polymerization inhibitor can be any known one, and is not particularly limited, but examples thereof include 4-methoxyphenol, hydroquinone, methoquinone, 2,6-di-t-butylphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), and phenothiazine. The polymerization inhibitor may be used alone or in combination of two or more.

[0238] When a polymerization inhibitor is used, the amount of the polymerization inhibitor used is preferably 0.005 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and even more preferably 0.05 to 1.5 parts by mass, relative to 100 parts by mass of the copolymer. When the amount of the polymerization inhibitor used is 0.005 parts by mass or more, gelation during the addition reaction can be prevented. On the other hand, when the amount of the polymerization inhibitor used is 5 parts by mass or less, sufficient exposure sensitivity of the (meth)acrylic resin (A) during UV irradiation can be obtained.

[0239] (Solvent) A common solvent can be used as the solvent. For example, the same solvent as that used in the solution polymerization in step (i) can be used. Toluene, which is likely to cause a chain transfer reaction, or an alcohol such as 1-methoxy-2-propanol may also be used. The solvent may be used alone or in combination of two or more.

[0240] (Reaction Conditions) The temperature of the addition reaction is preferably 25°C to 130°C, and particularly preferably 40°C to 120°C. When the temperature of the addition reaction is 25°C or higher, a sufficient reaction rate can be obtained. When the temperature of the addition reaction is 130°C or lower, crosslinking of double bonds due to thermal radical polymerization can be prevented, preventing the formation of gelled products. The time of the addition reaction is preferably 2 to 24 hours, and more preferably 2 to 12 hours.

[0241] During the addition reaction, a gas having a polymerization inhibitory effect may be introduced into the reaction system. By introducing a gas having a polymerization inhibitory effect into the reaction system, gelation during the addition reaction can be prevented.

[0242] Examples of gases that have a polymerization-inhibiting effect include gases that contain oxygen to an extent that does not fall within the explosive range of the substances in the system, such as air.

[0243] It is more preferable to use a gas having a polymerization inhibitor effect in combination with a polymerization inhibitor, since this allows the amount of polymerization inhibitor used to be reduced and the polymerization inhibitor effect to be enhanced.

[0244] (Photopolymerization Initiator (B)) Examples of the photopolymerization initiator (B) include benzophenone, benzil, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, 4,4′-dichlorobenzophenone, 4,4′-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, and benzoin isopropyl alcohol. butyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, 4'-dimethylaminoacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and other carbonyl-based photopolymerization initiators.

[0245] Examples of the photopolymerization initiator (B) include sulfide-based photopolymerization initiators such as diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, and tetramethylammonium monosulfide; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide; quinone-based photopolymerization initiators such as benzoquinone and anthraquinone; sulfochloride-based photopolymerization initiators; and thioxanthone-based photopolymerization initiators such as thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone.

[0246] Among these photopolymerization initiators (B), from the viewpoint of solubility in the pressure-sensitive adhesive composition, carbonyl-based photopolymerization initiators and acylphosphine oxides are preferred, and at least one selected from 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide is more preferred.

[0247] The photopolymerization initiator (B) may be used alone or in combination of two or more kinds.

[0248] The amount of the photopolymerization initiator (B) is preferably 0.1 to 5.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, per 100 parts by mass of the (meth)acrylic resin (A). When the content of the photopolymerization initiator (B) per 100 parts by mass of the (meth)acrylic resin (A) is 0.1 parts by mass or more, the ultraviolet-curable pressure-sensitive adhesive layer can be cured at a sufficiently fast curing rate upon UV irradiation, thereby making it possible to sufficiently reduce the adhesive strength of the pressure-sensitive adhesive layer after UV irradiation. When the content of the photopolymerization initiator (B) per 100 parts by mass of the (meth)acrylic resin (A) is 5.0 parts by mass or less, when a pressure-sensitive adhesive sheet having an ultraviolet-curable pressure-sensitive adhesive layer, which is a thermoset product of the pressure-sensitive adhesive composition, is attached to an adherend and then peeled off, the pressure-sensitive adhesive is less likely to remain on the adherend. Even if the content of the photopolymerization initiator (B) exceeds 5.0 parts by mass relative to 100 parts by mass of the (meth)acrylic resin (A), no effect commensurate with the content of the photopolymerization initiator (B) is observed. Therefore, by setting the content to 5.0 parts by mass or less, the pressure-sensitive adhesive composition can be produced economically.

[0249] <Crosslinking Agent (C)> The crosslinking agent (C) is a compound having no ethylenically unsaturated bond and having two or more functional groups that react with the hydroxyl groups contained in the (meth)acrylic resin (A). The crosslinking agent (C) provides a good balance between the adhesive strength before and after UV irradiation.

[0250] Examples of functional groups reactive with hydroxy groups include isocyanato groups, epoxy groups, carboxy groups, acid anhydride groups, and aziridinyl groups. From the viewpoint of reactivity, isocyanato groups and epoxy groups are preferred, with isocyanato groups being particularly preferred.

[0251] Examples of the crosslinking agent (C) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isocyanurate of hexamethylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, and tolylene of trimethylolpropane. Polyisocyanates such as diisocyanate adducts, xylylene diisocyanate adducts of trimethylolpropane, triphenylmethane triisocyanate, and methylenebis(4-phenylmethane)triisocyanate; 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, bisphenol A-epichlorohydrin type epoxy resins, N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], ethylene glycol diglycidyl ether, and polyethylene glycol diglycidyl polyepoxy compounds such as N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6 ... boxamide), aziridine compounds such as ethylene glycol-bis-[3-(2-aziridinyl)propionate], trimethylolpropane-tris[3-(2-aziridinyl)propionate], trimethylolpropane-tris[3-(1-aziridinyl)propionate], trimethylolpropane-tris[3-(2-methyl-1-aziridinyl)propionate], tetramethylolmethane-tris[3-(2-aziridinyl)propionate], and pentaerythritol-tris[3-(1-aziridinyl)propionate];and melamine compounds such as hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, and hexahexyloxymethylmelamine.

[0252] Among these crosslinking agents (C), it is preferable to use at least one selected from the group consisting of polyisocyanates and polyepoxy compounds, and it is more preferable to use polyisocyanates, because they have good reactivity with the (meth)acrylic resin (A).

[0253] The crosslinking agent (C) may be used alone or in combination of two or more kinds.

[0254] The content of the crosslinking agent (C) is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin (A). When the content of the crosslinking agent (C) per 100 parts by mass of the (meth)acrylic resin (A) is 0.1 parts by mass or more, a crosslinked structure with the (meth)acrylic resin (A) is sufficiently formed upon heating, and the strength of the ultraviolet-curable pressure-sensitive adhesive layer before UV irradiation is good. When the content of the crosslinking agent (C) per 100 parts by mass of the (meth)acrylic resin (A) is 30 parts by mass or less, the adhesive strength of the ultraviolet-curable pressure-sensitive adhesive layer before UV irradiation is good.

[0255] (Other Components) The pressure-sensitive adhesive composition may contain other components in addition to the (meth)acrylic resin (A), the photopolymerization initiator (B), and the crosslinking agent (C), as necessary. Examples of the other components include a tackifier, a solvent, and various additives.

[0256] (Tackifier) ​​Any conventionally known tackifier can be used without any particular limitation. Examples of tackifiers include terpene-based tackifier resins, phenol-based tackifier resins, rosin-based tackifier resins, aliphatic petroleum resins, aromatic petroleum resins, copolymer-based petroleum resins, alicyclic petroleum resins, xylene resins, epoxy-based tackifier resins, polyamide-based tackifier resins, ketone-based tackifier resins, and elastomer-based tackifier resins. These tackifiers may be used alone or in combination of two or more.

[0257] When a tackifier is used, its content is preferably 30 parts by mass or less, and more preferably 5 to 20 parts by mass, per 100 parts by mass of the (meth)acrylic resin (A).

[0258] (Solvent) A solvent can be used to dilute the PSA composition for the purpose of adjusting the viscosity of the PSA composition. For example, when the PSA composition is to be applied, the solvent can be used to adjust the viscosity of the PSA composition to an appropriate value.

[0259] Examples of the solvent include organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, propyl acetate, tetrahydrofuran, dioxane, cyclohexanone, hexane, toluene, xylene, n-propanol, isopropyl alcohol, etc. The solvents may be used alone or in combination of two or more.

[0260] (Additives) Examples of additives include plasticizers, surface lubricants, leveling agents, softeners, antioxidants, antiaging agents, light stabilizers such as benzotriazole-based ones, ultraviolet absorbers, polymerization inhibitors, phosphate ester-based and other flame retardants, surfactants, and antistatic agents.

[0261] [Method for Producing Pressure-Sensitive Adhesive Sheet] The pressure-sensitive adhesive sheet can be produced, for example, by the method described below.

[0262] First, a pressure-sensitive adhesive solution is prepared by dissolving or dispersing a pressure-sensitive adhesive composition in a solvent. The pressure-sensitive adhesive composition may be used as the pressure-sensitive adhesive solution as it is.

[0263] Next, the adhesive solution is applied to the substrate layer, and if a solvent is contained, the solution is heated and dried to remove the solvent, thereby forming a pre-thermal-curing ultraviolet-curable adhesive layer. Thereafter, a release sheet is attached to the pre-thermal-curing ultraviolet-curable adhesive layer as needed. Furthermore, the resulting sheet is cured in an oven for a certain period of time as needed to form a crosslinked structure, thereby obtaining an adhesive sheet.

[0264] The pressure-sensitive adhesive sheet can also be produced by the method described below. An adhesive solution is applied to a release sheet, and if a solvent is contained, the solution is heated and dried to remove the solvent, forming a pre-thermally cured ultraviolet-curable adhesive layer. The release sheet having the pre-thermally cured ultraviolet-curable adhesive layer is then placed on a substrate layer with the surface of the pre-thermally cured ultraviolet-curable adhesive layer facing the substrate layer, and the pre-thermally cured ultraviolet-curable adhesive layer is transferred onto the substrate layer. The resulting sheet is then cured in an oven for a certain period of time, if necessary, to form a crosslinked structure, thereby obtaining a pressure-sensitive adhesive sheet.

[0265] The pressure-sensitive adhesive solution can be applied to the substrate layer or the release sheet by any known method, specifically, by using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or a direct coater.

[0266] The conditions for heat-drying the applied pressure-sensitive adhesive solution are not particularly limited, but are typically 25 to 180°C, preferably 60 to 150°C, for 1 to 20 minutes, preferably 1 to 10 minutes. Heat-drying within the above ranges allows the solvent contained in the pressure-sensitive adhesive solution to be removed. The conditions for curing the heat-dried sheet in an oven for a certain period of time are not particularly limited, but are typically 25 to 100°C, preferably 30 to 80°C, for 1 to 30 days, preferably 1 to 14 days. Curing under the above conditions allows the (meth)acrylic resin (A) to be crosslinked by the crosslinking agent (C), thereby adjusting the gel fraction of the ultraviolet-curable pressure-sensitive adhesive layer to the desired range.

[0267] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0268] The raw materials used in the synthesis of the (meth)acrylic resins (A) and (cA) are as follows: methyl acrylate, Nippon Shokubai Co., Ltd.; n-butyl acrylate, Osaka Organic Chemical Industry Ltd.; 2-ethylhexyl acrylate, Osaka Organic Chemical Industry Ltd.; glycidyl methacrylate, NOF Corporation; 4-hydroxybutyl acrylate glycidyl ether, Mitsubishi Chemical Corporation; 3,4-epoxycyclohexylmethyl methacrylate, Daicel Corporation; 3,4-epoxytricyclo[5.2.1.0] ２，６ ] decaneoxyethyl acrylate, acrylic acid, Nippon Shokubai Co., Ltd., 2-hydroxyethyl acrylate, Nippon Shokubai Co., Ltd., methacrylic acid, Nippon Shokubai Co., Ltd., methacrylic anhydride, Evonik Japan Co., Ltd., Karenz (trademark) MOI, 2-isocyanatoethyl methacrylate, Resonac Co., Ltd., radical polymerization initiator: 2,2'-azobis(isobutyronitrile), Fujifilm Wako Pure Chemical Industries Co., Ltd., catalyst: triphenylphosphine, Hokko Chemical Industry Co., Ltd., dioctyltin dilaurate, Nitto Kasei Co., Ltd.,

[0269] Synthesis Example 1: A reactor equipped with a stirrer, temperature controller, reflux condenser, dropping funnel, and thermometer was charged with 32 parts by mass of propylene glycol monomethyl ether, and heating to reflux was initiated. 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of glycidyl methacrylate were mixed to prepare a monomer mixture. This monomer mixture, to which 0.10 parts by mass of 2,2'-azobis(isobutyronitrile) was added as a polymerization initiator, was added dropwise to the reactor. After completion of the dropwise addition, the mixture was maintained at 85°C for 4 hours. The reaction temperature was then raised to 120°C, and 3.00 parts by mass of methacrylic acid and 5.00 parts by mass of methacrylic anhydride were added along with 1.00 parts by mass of triphenylphosphine as a catalyst. The mixture was then maintained at 120°C for 4 hours, and the disappearance of the methacrylic acid was confirmed by acid value measurement. Propylene glycol monomethyl ether was added to the reaction liquid obtained by the above steps so that the components other than the solvent were 40% by mass, thereby obtaining a liquid (solid content 40% by mass) containing a (meth)acrylic resin (A1).

[0270] Synthesis Examples 2 to 4 Liquids (solid content 40% by mass) containing (meth)acrylic resins (A2) to (A4) were obtained in the same manner as in Synthesis Example 1, except that the compositions shown in Table 1 were used.

[0271] Comparative Synthesis Example 1: A reactor equipped with a stirrer, temperature controller, reflux condenser, dropping funnel, and thermometer was charged with 32 parts by mass of propylene glycol monomethyl ether, and heating under reflux was initiated. 20 parts by mass of n-butyl acrylate, 70 parts by mass of 2-ethylhexyl acrylate, and 10 parts by mass of acrylic acid were mixed to prepare a monomer mixture. This monomer mixture, to which 0.10 parts by mass of 2,2'-azobis(isobutyronitrile) was added as a polymerization initiator, was added dropwise to the reactor. After completion of the dropwise addition, the mixture was maintained at 85°C for 4 hours. The reaction temperature was then raised to 120°C, and 20.00 parts by mass of 3,4-epoxycyclohexylmethyl methacrylate was added along with 1.00 parts by mass of triphenylphosphine as a catalyst. The mixture was then maintained at 120°C for 4 hours. Propylene glycol monomethyl ether was added to the reaction liquid obtained by the above steps so that the components other than the solvent were 40% by mass, thereby obtaining a liquid (solid content 40% by mass) containing a (meth)acrylic resin (cA1).

[0272] Comparative Synthesis Example 2: A reactor equipped with a stirrer, temperature controller, reflux condenser, dropping funnel, and thermometer was charged with 32 parts by mass of ethyl acetate, and heating under reflux was initiated. 20 parts by mass of methyl acrylate, 12 parts by mass of n-butyl acrylate, 50 parts by mass of 2-ethylhexyl acrylate, and 18 parts by mass of 2-hydroxyethyl acrylate were mixed to prepare a monomer mixture. This monomer mixture, to which 0.10 parts by mass of 2,2'-azobis(isobutyronitrile) was added as a polymerization initiator, was added dropwise to the reactor. After completion of the dropwise addition, the mixture was heated under reflux for 4 hours. Next, the reaction temperature was lowered to 60°C, and a mixture of 20.00 parts by mass of 2-isocyanatoethyl methacrylate and 0.10 parts by mass of dioctyltin dilaurate as a urethanization catalyst was added dropwise. After completion of the dropwise addition, the reaction system was maintained at 60°C for 4 hours to eliminate the isocyanato groups. Ethyl acetate was added to the reaction liquid obtained by the above steps so that the components other than the solvent were 40% by mass, thereby obtaining a liquid (solid content 40% by mass) containing a (meth)acrylic resin (cA2).

[0273]

[0274] The raw materials used in preparing the pressure-sensitive adhesive composition are as follows: Photopolymerization initiator (B): TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BASF, trade name: Omnirad-TPO) Crosslinking agent (C) L-45E: tolylene diisocyanate adduct of trimethylolpropane (Tosoh Corporation, trade name: Coronate L-45E)

[0275] [Preparation of Pressure-Sensitive Adhesive Compositions] Ethyl acetate, a dilution solvent, was added to the liquids containing the (meth)acrylic resins (A1) to (A4) and (cA1) to (cA2) obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 and 2, respectively, so that the contents of the (meth)acrylic resins (A1) to (A4) and (cA1) to (cA2) were 30 mass %. Using these liquids, pressure-sensitive adhesive compositions were obtained by the method described below.

[0276] In a room shielded from actinic radiation, the (meth)acrylic resin (A), photopolymerization initiator (B), and crosslinking agent (C) shown in Table 2 were added to a plastic container in the amounts (parts by mass) shown in Table 2, and the mixture was stirred to obtain pressure-sensitive adhesive compositions (B1) to (B4) and (cB1) to (cB2). The numerical value for (meth)acrylic resin (A) in Table 2 is the amount (parts by mass) of the (meth)acrylic resin used.

[0277] [Production Example 1] Preparation of Pressure-Sensitive Adhesive Sheet A silicone-based light-release PET film (Toyobo Co., Ltd., product name: E7006, thickness 25 μm) was prepared as a release sheet. The pressure-sensitive adhesive composition (B1) was applied to the release-treated surface using an applicator so that the thickness after thermal curing was 20 μm. The film was then dried by heating at 100 ° C for 2 minutes to form a pre-thermal-curing ultraviolet-curable pressure-sensitive adhesive layer. Next, a 50 μm-thick polyethylene naphthalate resin film was prepared as a sheet-like substrate layer. The polyethylene naphthalate resin film was attached to the pre-thermal-curing ultraviolet-curable pressure-sensitive adhesive layer using a rubber roller so that the corona-treated surface of the polyethylene naphthalate resin film was adhered to the exposed surface of the pre-thermal-curing ultraviolet-curable pressure-sensitive adhesive layer. The film was then cured in an oven at 40 ° C for 3 days, and the pre-thermal-curing ultraviolet-curable pressure-sensitive adhesive layer was crosslinked and cured to obtain the pressure-sensitive adhesive sheet of Production Example 1.

[0278] [Production Examples 2 to 4 and Comparative Production Examples 1 and 2] Preparation of Pressure-Sensitive Adhesive Sheets Pressure-Sensitive Adhesive sheets of Production Examples 2 to 4 and Comparative Production Examples 1 and 2 were obtained in the same manner as in Production Example 1, except that the pressure-sensitive adhesive compositions shown in Table 2 were used instead of the pressure-sensitive adhesive composition (B1).

[0279] Reference Examples 1 to 4 and Comparative Reference Examples 1 and 2 Preparation of Insulating Sheet with Adhesive Sheet Glass cloth (NE-2116, Nitto Boseki Co., Ltd.) was impregnated with a thermosetting resin composition consisting of 100 parts by mass of epoxy resin (YX-4000, Mitsubishi Chemical Corporation), 30 parts by mass of phenol novolac resin (Shonoru BRG-557, Aica Kogyo Co., Ltd.), 0.5 parts by mass of 2-ethyl-4-methylimidazole (Curesol 2E4MZ, Shikoku Chemicals Corporation), and 20 parts by mass of styrene-ethylene-butylene-styrene (SEBS) (MD1653MO, Kraton Corporation) to prepare an insulating sheet having a width of 100 mm and a length of 200 mm. The adhesive sheets of Production Examples 1 to 4 and Comparative Production Examples 1 and 2 from which the light-release PET films had been peeled were laminated on the main surface of an insulating sheet so that the ultraviolet-curable adhesive layer was in contact with the main surface, and the sheets were pressed together at a temperature of 120°C under a pressure of 0.5 MPa to obtain insulating sheets with adhesive sheets.

[0280] <Evaluation of Adhesion Strength of Pressure-Sensitive Adhesive Sheet to Insulating Sheet> (1) Measurement of Adhesion Strength (180° Peel Strength) Before UV Irradiation The adhesion strength of the pressure-sensitive adhesive sheet to the insulating sheet was evaluated by measuring the 180° peel strength as follows. A sample measuring 25 mm wide and 100 mm long was cut from the insulating sheet with the pressure-sensitive adhesive sheet attached. The insulating sheet side of this sample was attached to a polycarbonate plate using double-sided tape. The peel strength of the pressure-sensitive adhesive sheet to the insulating sheet was measured using a tensile tester (VPA-H200, Kyowa Interface Science Co., Ltd.) and determined as the adhesion strength before UV irradiation. The measurement conditions were a peel angle of 180° and a tensile speed of 300 mm / min. The sample storage and peel strength measurement were performed in an environment of 23°C and 40% relative humidity. The results are shown in Table 2.

[0281] (2) Measurement of adhesive strength (180° peel strength) after UV irradiation: The insulating sheet with the adhesive sheet was irradiated with a dose of 300 mJ / cm from the surface of the base layer of the adhesive sheet. ２The adhesive sheet was irradiated with ultraviolet (UV) rays under the conditions of 100 mm x 25 mm, and a sample 25 mm wide and 100 mm long was cut out. A conveyor-type UV irradiation device (Eye Graphics Co., Ltd., 2 kW lamp, 80 W / cm) was used for UV irradiation. Using this sample, the peel strength of the adhesive sheet relative to the insulating sheet was measured using the same method as for measuring the adhesive strength (180° peel strength) before UV irradiation, and this was determined as the adhesive strength after UV irradiation. The results are shown in Table 2.

[0282] Reference Examples 5-8 and Comparative Reference Examples 3-4 Evaluation of Adhesion Strength of Pressure-Sensitive Adhesive Sheets to Copper Plates (1) Measurement of Adhesion Strength (180° Peel Strength) Before UV Irradiation The adhesion strength of the pressure-sensitive adhesive sheet to a copper plate was evaluated by measuring the 180° peel strength. A 10 μm thick electrolytic copper foil (3EC-M3-VLP-18, Mitsui Mining & Smelting Co., Ltd.) was attached to a polycarbonate plate using double-sided tape. Samples measuring 25 mm wide and 100 mm long were cut out from the pressure-sensitive adhesive sheets of Production Examples 1-4 and Comparative Production Examples 1-2. The light-release PET film of the pressure-sensitive adhesive sheet was peeled off, and the UV-curable adhesive layer was pressed against the electrolytic copper foil on the polycarbonate plate at a temperature of 120°C and a pressure of 0.5 MPa to obtain a sample for evaluating the adhesion strength of the pressure-sensitive adhesive sheet to a copper plate. The peel strength of the pressure-sensitive adhesive sheet to the copper plate was measured using a tensile tester (VPA-H200, Kyowa Interface Science Co., Ltd.) and determined as the adhesion strength before UV irradiation. The measurement conditions were a peel angle of 180° and a pulling speed of 300 mm / min. The samples were stored and the peel strength was measured in an environment of a temperature of 23°C and a relative humidity of 40%. The results are shown in Table 2.

[0283] (2) Measurement of adhesive strength (180° peel strength) after UV irradiation A sample for evaluating the adhesive strength of the adhesive sheet to the copper plate was irradiated with an amount of 300 mJ / cm from the surface of the substrate layer of the adhesive sheet. ２ The adhesive sheet was irradiated with ultraviolet (UV) rays under the following conditions. A conveyor-type UV irradiation device (Eye Graphics Co., Ltd., 2 kW lamp, 80 W / cm) was used for UV irradiation. The peel strength of the adhesive sheet against the copper plate was then measured using the same method as for measuring the adhesive strength (180° peel strength) before UV irradiation, and determined as the adhesive strength after UV irradiation. The results are shown in Table 2.

[0284] Examples 1 to 4 and Comparative Examples 1 and 2 Preparation of Transfer Sheet Evaluation Sample Glass cloth (NE-2116, Nitto Boseki Co., Ltd.) was impregnated with a thermosetting resin composition consisting of 100 parts by mass of epoxy resin (YX-4000, Mitsubishi Chemical Corporation), 30 parts by mass of phenol novolac resin (Shonoru BRG-557, Aica Kogyo Co., Ltd.), 0.5 parts by mass of 2-ethyl-4-methylimidazole (Curesol 2E4MZ, Shikoku Chemicals Corporation), and 20 parts by mass of styrene-ethylene-butylene-styrene (SEBS) (MD1653MO, Kraton Corporation) to prepare an insulating sheet having a width of 300 mm, a length of 500 mm, and a thickness of 100 μm. Next, the light release PET film was peeled off from the pressure-sensitive adhesive sheets of Production Examples 1 to 4 and Comparative Production Examples 1 and 2, and a 10 μm thick electrolytic copper foil (3EC-M3-VLP-18, Mitsui Mining & Smelting Co., Ltd.) was laminated on the ultraviolet-curable pressure-sensitive adhesive layer. The laminate was then wound into a roll and subjected to a pressure of 20° C. and 40 N / cm. ２ A sheet with a conductor layer was prepared by autoclaving for 30 minutes at a pressure of 100 psi. A photosensitive resist was applied to the copper foil surface, exposed through a photomask, and developed to form a circuit pattern. The sheet was then immersed in a ferric chloride solution to etch away the exposed copper foil, forming a circuit pattern of wiring conductors. The resist layer remaining on the wiring conductors was then removed using an aqueous sodium hydroxide solution to prepare a transfer sheet. The circuit pattern consisted of multiple 12 μm-wide strip-shaped wiring conductors arranged at 30 μm intervals. The transfer sheet was then placed on the main surface of an insulating sheet so that the wiring conductors of the transfer sheet were in contact with each other, and the sheet was pressed against the insulating sheet at a pressure of 0.5 MPa at a temperature of 120°C to obtain a transfer sheet evaluation sample.

[0285] <Evaluation of transfer sheet evaluation samples> (1) Evaluation of adhesive strength of transfer sheet to insulating sheet In the same manner as in the evaluation of the adhesive strength of the pressure-sensitive adhesive sheet to the insulating sheet, the adhesive strength before UV irradiation (180° peel strength) and the adhesive strength after UV irradiation (180° peel strength) were measured.

[0286] (2) Appearance Evaluation The transfer sheet evaluation sample was exposed to an irradiation dose of 300 mJ / cm from the surface of the base layer side of the transfer sheet. ２The insulating sheet was irradiated with ultraviolet light under the conditions of

[0043] , and the ultraviolet-curable adhesive layer was peeled off from the wiring conductor, transferring the wiring conductor onto the insulating sheet. The main surface of the insulating sheet to which the wiring conductor had been transferred was observed under a scanning electron microscope at 1000x magnification to check for damage to the insulating sheet surface, residual adhesive, and discoloration of the wiring conductor. Discoloration of the wiring conductor indicates penetration of the chemical solution. Cases in which no damage to the insulating sheet surface, residual adhesive, or discoloration of the wiring conductor was observed were rated as good, and cases in which such damage was observed were rated as bad. The results are shown in Table 2.

[0287] In Examples 1 to 4, the pressure-sensitive adhesive sheets could be peeled off without leaving any adhesive residue on the adherend surface, including the insulating region and the wiring conductor, which is the conductive region. This suggests that the pressure-sensitive adhesive sheets of Production Examples 1 to 4 can be peeled off from the electronic component without leaving any adhesive residue by irradiating them with UV light after being attached to the electronic component having an insulating region and a conductive region.

[0288] [Examples 5 to 8 and Comparative Examples 3 and 4] <Preparation of Samples for Wiring Board Evaluation> The transfer sheet evaluation sample was exposed to light from the surface of the base layer side of the transfer sheet at an irradiation dose of 300 mJ / cm ２ The insulating sheet was irradiated with ultraviolet light under the conditions of

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[0289] <Evaluation of Wiring Board Evaluation Samples> The wiring board evaluation samples were left in a high-temperature, high-humidity environment with a humidity of 85%, a temperature of 85°C, and a voltage of 5V for 1000 hours, and then the insulation resistance between adjacent wiring conductors in each wiring board evaluation sample was measured. The results are shown in Table 2. Note that when the insulation resistance value was 1×10 ６ Ω or more is considered good, and 1 × 10 ６ A resistance of less than Ω was determined to be poor. A poor result suggests that foreign matter remains on the surface of the insulating sheet to which the wiring conductor has been transferred, or that the surface has been damaged.

[0290]

[0291] REFERENCE SIGNS LIST 12 Base material layer 14 UV-curable adhesive layer 15 Adhesive sheet 16 Insulating region 18 Conductive region 20 Semiconductor chip 22 Sealing resin 24 Rewiring layer 26 Conductive post 28 Bump 30 Wiring 32 Substrate 34 Semiconductor element 36 Electronic element 38 Noise suppressing layer 40 Covering portion 41 Opening 42 Sealing portion 43 Recess 100, 110 Electronic component with adhesive sheet 200 Semiconductor element linked body 300 Semiconductor element 400 Electronic device 500 Sealed electronic component linked body 600 Sealed electronic component

Claims

1. An electronic component with an adhesive sheet, comprising: an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer; and an electronic component provided on the ultraviolet-curable adhesive layer of the adhesive sheet, wherein the surface of the electronic component in contact with the ultraviolet-curable adhesive layer has an insulating region and a conductive region, the ultraviolet-curable adhesive layer is a thermoset product of an adhesive composition, and the adhesive composition comprises a (meth)acrylic resin (A) containing structural units of the following formulas (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.

2. A transfer sheet comprising: an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer; and a wiring conductor partially provided on the ultraviolet-curable adhesive layer, wherein the ultraviolet-curable adhesive layer is a heat-cured product of an adhesive composition, and the adhesive composition comprises a (meth)acrylic resin (A) containing structural units of the following formulas (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.

3. A sheet with a conductor layer for transfer sheet, comprising: an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer; and a conductor layer provided on the ultraviolet-curable adhesive layer, wherein the ultraviolet-curable adhesive layer is a heat-cured product of an adhesive composition, and the adhesive composition contains a (meth)acrylic resin (A) containing structural units of the following formulas (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.

4. The electronic component with adhesive sheet, transfer sheet, or sheet with conductor layer for transfer sheet according to any one of claims 1 to 3, wherein the thickness of the base layer is 5 to 500 μm, and the thickness of the ultraviolet-curable adhesive layer is 1 to 300 μm.

5. A transfer sheet or a sheet with a conductor layer for a transfer sheet according to claim 2 or 3, wherein the thickness of the wiring conductor or the conductor layer is 0.5 to 100 μm, and is in the range of 0.01 to 1.20 times the thickness of the ultraviolet-curable adhesive layer.

6. The electronic component with a pressure-sensitive adhesive sheet, transfer sheet, or sheet with a conductor layer for a transfer sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive composition contains: the (meth)acrylic resin (A); a photopolymerization initiator (B); and a crosslinking agent (C).

7. A method for producing a sheet with a conductor layer for a transfer sheet according to claim 3, comprising the steps of: providing an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer; and providing a conductor layer on the exposed surface of the ultraviolet-curable adhesive layer.

8. A method for manufacturing a transfer sheet, comprising: a resist layer patterning step of providing a resist layer on the exposed surface of the conductor layer of the sheet with a conductor layer for transfer sheet described in claim 3, exposing the resist layer through a photomask, and developing the resist layer with a developer; an etching step of removing by etching the exposed area of ​​the conductor layer formed by the patterning step to form a wiring conductor; and a removal step of removing the resist layer on the wiring conductor formed by the etching step.

9. A method for manufacturing a wiring board, comprising a transfer step of contacting the surface of the transfer sheet according to claim 2 on which the wiring conductor is provided with an insulating sheet, and transferring the wiring conductor to the insulating sheet.

10. A method for manufacturing a wiring board, comprising providing a sealing layer on the surface of the transfer sheet according to claim 2 on which the wiring conductors are provided.

11. The method for manufacturing a wiring board according to claim 10, further comprising providing a conductive path that penetrates the sealing layer so that a portion of the wiring conductor is connected to the conductive path.

12. A method for manufacturing an electronic device, comprising: a preparation step of preparing a substrate having an insulating region and a conductive region on its surface; an attachment step of attaching an adhesive sheet having a base layer and an ultraviolet-curable adhesive layer provided on the base layer to the surface of the substrate; a processing step of processing the substrate to which the adhesive sheet has been attached; an ultraviolet irradiation step of irradiating the adhesive sheet with ultraviolet light to photo-cure the ultraviolet-curable adhesive layer; and a peeling step of peeling the adhesive sheet from the substrate, wherein the ultraviolet-curable adhesive layer is a thermoset product of an adhesive composition, and the adhesive composition comprises a (meth)acrylic resin (A) containing structural units of the following formulae (1) to (3), and optionally the following formula (4): (In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents an alkyl group having 1 to 20 carbon atoms, and in formula (2), R ３ represents a hydrogen atom or a methyl group, R ４ represents a group having a hydroxy group on a carbon atom and a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid on a carbon atom adjacent to the carbon atom; ５ represents a hydrogen atom or a methyl group, R ６ represents a group having, on a carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid, and, on a carbon atom adjacent to the carbon atom, a residue obtained by removing a hydrogen atom from a carboxy group of an unsaturated monocarboxylic acid; ７ represents a hydrogen atom or a methyl group, R ８ represents a group containing an epoxy group.

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