Adhesive sheet

Abstract

Provided is an adhesive sheet which is not susceptible to paste collapse and which has excellent bump followability. According to the present invention, provided is an adhesive sheet provided with a base material layer and an adhesive layer provided on the base material layer, the adhesive layer being formed from a (meth) acrylic resin composition containing a (meth) acrylic resin, the adhesive sheet having a tensile storage modulus at 40 DEG C of 300 MPa or less, and the adhesive layer being formed from a (meth) acrylic resin composition containing a (meth) acrylic resin. The adhesive layer has a shear storage modulus at 40 DEG C of 350 kPa or more.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet. Background Art

[0002] In the manufacturing process of semiconductor components, adhesive sheets are sometimes attached to adherends such as semiconductor wafers, semiconductor substrates, semiconductor devices, or various semiconductor packages, and then the adherends are processed. Examples of adhesive sheets used for such applications include back grinding tapes for grinding the backside of adherends and dicing tapes for dicing adherends (e.g., Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-13183 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Such adhesive sheets typically have a laminated structure consisting of a substrate layer and an adhesive layer thereon. The adhesive layer may be disposed over the entire area of ​​one principal surface of the substrate layer or only over a portion of the principal surface. In the latter case, alignment between the adherend and the adhesive layer is typically performed by detecting the edge of the adhesive layer using image recognition.

[0008] However, adhesive sheets are typically rolled into a roll while applying a certain degree of tension and distributed in this state. While the adhesive sheet is rolled into a roll, the adhesive layer is constantly subjected to the forces generated by the tension, which can cause "paste collapse," whereby the edges of the adhesive layer gradually round off due to these forces. If paste collapse occurs, edge detection of the adhesive layer is likely to fail.

[0009] Furthermore, a pressure-sensitive adhesive sheet may be attached to an adherend having bumps (projecting electrodes). In order to protect the bumps during processing of the adherend, it is desirable that the pressure-sensitive adhesive sheet follow the bumps.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive sheet that is less likely to cause paste collapse and has excellent bump followability.

[0011] Technical means to solve problems

[0012] According to the present invention, the following inventions are provided.

[0013] [1] An adhesive sheet comprising a substrate layer and an adhesive layer provided on the substrate layer, wherein the adhesive layer is formed from a (meth)acrylic resin composition, the (meth)acrylic resin composition containing a (meth)acrylic resin, the adhesive sheet having a tensile storage modulus of 300 MPa or less at 40°C, and the adhesive layer having a shear storage modulus of 350 kPa or more at 40°C.

[0014] [2] The adhesive sheet according to [1], wherein the substrate layer comprises an ionomer.

[0015] [3] The adhesive sheet according to [1] or [2], wherein the adhesive layer is configured so that the adhesive force is not reduced by irradiation with active energy rays.

[0016] [4] The adhesive sheet according to any one of [1] to [3], wherein the adhesive layer has an adhesive strength of 0.5 to 1.8 N / 20 mm or less at 23°C and 50% humidity.

[0017] [5] The adhesive sheet according to any one of [1] to [4], wherein the thickness of the adhesive layer is 30 μm or less.

[0018] [6] The adhesive sheet according to any one of [1] to [5], wherein the adhesive layer is provided only on a partial area of ​​one main surface of the substrate layer.

[0019] [7] The adhesive sheet according to any one of [1] to [6], wherein the thickness of the substrate layer is 50 to 400 μm.

[0020] [8] The adhesive sheet according to any one of [1] to [7], wherein the adhesive sheet is used for semiconductor processing.

[0021] Effects of the Invention

[0022] The present inventors have diligently studied and, as a result, have found that the adhesive sheet of the present invention is less likely to cause paste collapse and has excellent bump followability, thereby completing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The layer structure of the pressure-sensitive adhesive sheet 10 according to one embodiment of the present invention is shown.

[0024] Figure 2 The pressure-sensitive adhesive sheet 10 is shown in a state attached to the adherend 4 .

[0025] Figure 3 This is a plan view of the adhesive layer 2 used to evaluate the paste collapse resistance. DETAILED DESCRIPTION

[0026] The following describes embodiments of the present invention. The various features described in the embodiments shown below can be combined with each other. In addition, each feature independently establishes the invention. In this specification, "(meth)acrylic acid" refers to methacrylic acid or acrylic acid, and "(meth)acrylate" refers to methacrylate or acrylate.

[0027] 1. Adhesive sheet 10

[0028] like Figure 1 As shown, a pressure-sensitive adhesive sheet 10 according to one embodiment of the present invention includes a base material layer 1 and a pressure-sensitive adhesive layer 2 provided thereon.

[0029] 1-1. Base material layer 1

[0030] The substrate layer 1 may have any composition and thickness as long as it can support the adhesive layer 2. The substrate layer 1 preferably comprises a thermoplastic resin. The composition of the thermoplastic resin is not particularly limited, and examples thereof include: ionomer resins obtained by crosslinking the carboxyl groups of monomers and / or complexes such as ethylene-methacrylic acid-acrylate terpolymers, ethylene-methacrylic acid copolymers, and ethylene-acrylic acid copolymers with metal ions such as sodium ions, lithium ions, and magnesium ions; soft polypropylene resins obtained by blending styrene-butadiene copolymer rubber, styrene-butadiene-styrene block copolymer rubber, styrene-isoprene-styrene block copolymer rubber, and ethylene-propylene rubber into polypropylene resin; low-density polyethylene, ethylene-propylene block copolymers, ethylene-propylene random copolymers, ethylene-vinyl acetate copolymers, ethylene-methacrylic acid copolymers, ethylene-1-octene copolymers, and polybutene. Among these, ionomer resins are preferred.

[0031] The weight average molecular weight (Mw) of the thermoplastic resin is preferably 10,000 to 1,000,000, more preferably 50,000 to 500,000. The weight average molecular weight (Mw) refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0032] The thickness of the substrate layer is preferably 50 to 400 μm, more preferably 75 to 300 μm, and even more preferably 90 to 250 μm. Specifically, the thickness is, for example, 50, 60, 70, 75, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 350, or 400 μm, and may be within a range between any two of the values ​​exemplified here.

[0033] 1-2. Adhesive layer 2

[0034] The adhesive layer 2 is a layer for attaching the adhesive sheet 10 to the adherend 4. The adhesive layer 2 is formed from a (meth)acrylic resin composition. The (meth)acrylic resin composition contains a (meth)acrylic resin and may also contain other additives. The content of other additives is preferably 30% by mass or less, more preferably 20% by mass or less.

[0035] The adhesive layer 2 is preferably constructed so that the adhesive force will not decrease due to the irradiation of active energy rays. Therefore, the (meth) acrylic resin composition constituting the adhesive layer 2 is preferably not included in substances that produce polymerization activity such as free radicals, cations, anions, etc. due to light when used. In this case, since the adhesive force of the adhesive layer 2 cannot be reduced after the processing of the adherend 4 and before the adherend 4 is peeled off, the adhesive force of the adhesive layer 2 is preferably not too high. On the other hand, the adhesive layer 2 needs to have an adhesive force to the extent that the adherend 4 will not peel off when the adherend 4 is processed. Therefore, the adhesive force S1 of the adhesive layer 2 is preferably 0.5~1.8N / 20mm. The adhesive force S1 can be measured by the method shown in the examples.

[0036] S1 is, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8 N / 20 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0037] In addition, the shear storage modulus G' of the adhesive layer 2 at 40°C is 350 kPa or more. The shear storage modulus G' is an indicator of the hardness of the adhesive layer 2. The higher the shear storage modulus G', the less likely the adhesive layer 2 is to deform, and the higher the resistance to paste collapse. The shear storage modulus G' can be measured by the method shown in the examples. The shear storage modulus G' is, for example, 350 to 2000 kPa, for example, 350, 400, 450, 500, 550, 600, 700, 800, 900, 1000, 1500, 2000 kPa, and can also be within the range between any two of the values ​​exemplified here or any one or more.

[0038] The adhesive layer 2 is preferably provided only on a portion of one principal surface 1a of the substrate layer 1. In this case, it is important to detect the edge 2a of the adhesive layer 2 for alignment of the adherend 4, making the application of the present invention particularly significant. The ratio of the area of ​​the region where the adhesive layer 2 is formed to the area of ​​the principal surface 1a is, for example, 10 to 99%, preferably 50 to 95%. This ratio can be, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, or 99%, or can be within a range between any two of the values ​​exemplified here.

[0039] (Meth) acrylic resin is a polymer of a raw material mixture containing a (meth) acrylic acid compound. The ratio of the (meth) acrylic acid compound in the raw material mixture is, for example, 80 to 100% by mass, specifically, for example, 80, 85, 90, 95, or 100% by mass, and may also be within the range between any two of the values ​​exemplified here. The raw material mixture is preferably composed only of (meth) acrylic acid compounds, but may also contain other monomers. Examples of other monomers include olefins such as ethylene and propylene, aliphatic vinyls such as vinyl acetate, and aromatic vinyls such as styrene.

[0040] The (meth) acrylic acid compound is a compound having a (meth) acryloyl group, and examples thereof include (meth) acrylate, (meth) acrylic acid, (meth) acrylamide, and the like. The ratio of the (meth) acrylic acid ester in the (meth) acrylic acid compound is, for example, 80 to 100% by mass, specifically, for example, 80, 85, 90, 95, 100% by mass, or within the range between any two of the values ​​exemplified herein. The weight average molecular weight of the (meth) acrylic acid compound is preferably 50 to 100,000. The weight average molecular weight (Mw) is a polystyrene conversion value measured by gel permeation chromatography (GPC). The Mw is, for example, 50, 100, 200, 300, 400, 500, 1000, 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or 100,000, or within the range between any two of the values ​​exemplified herein.

[0041] Examples of (meth)acrylates include (meth)acrylic oligomers and (meth)acrylic monomers. Examples of (meth)acrylic oligomers include 1,2-polybutadiene-terminated urethane (meth)acrylate, the aforementioned hydrogenated products, 1,4-polybutadiene-terminated urethane (meth)acrylate, polyisoprene-terminated (meth)acrylate, polyester-based urethane (meth)acrylate, polyether-based urethane (meth)acrylate, polyester (meth)acrylate, and bisphenol A epoxy (meth)acrylate, wherein one or more (meth)acryloyl groups are introduced into the oligomer terminal or side chain. The ratio of the (meth)acrylic oligomer in the (meth)acrylate is preferably 10 to 90% by mass, more preferably 20 to 80% by mass. This ratio is, for example, 10, 20, 30, 40, 50, 60, 70, 80, or 90% by mass, and may also be within a range between any two of the values ​​exemplified herein. The Mw of the (meth)acrylic oligomer is preferably 5,000 to 100,000. Examples of the Mw include 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, and 100,000, and may be within a range between any two of the values ​​exemplified here.

[0042] Examples of the (meth)acrylic monomer include butyl (meth)acrylate, 2-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, bisphenol A type ethylene oxide-modified di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexaacrylate.

[0043] The raw material mixture preferably contains 2% by mass or more of (meth)acrylate containing allylic hydrogen. (Meth)acrylate containing allylic hydrogen is a compound having a (meth)acryloyl group and having allylic hydrogen in addition to the above-mentioned (meth)acryloyl group. By making the (meth)acrylic compound contain 2% by mass or more of (meth)acrylate containing allylic hydrogen, the shear storage modulus G' can be improved. As reasons why the shear storage modulus G' can be improved by formulating (meth)acrylate containing allylic hydrogen, it can be exemplified as follows: peroxy radicals generated by oxygen molecules present in the system have the property of hindering the growth reaction of free radical polymerization; peroxy radicals are consumed by depriving allylic hydrogen of (meth)acrylate containing allylic hydrogen; the activity of the growth reaction of free radical polymerization of carbon radicals generated by depriving allylic hydrogen is higher than that of peroxy radicals.

[0044] The ratio of the (meth)acrylate containing allylic hydrogen in the raw material mixture is, for example, 2 to 40% by mass, for example, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, or 40% by mass, and may be within a range between any two of the values ​​exemplified here, or any one or more thereof.

[0045] As a (meth)acrylate containing allylic hydrogen, a compound having a (meth)acryloyl group connected to the end of the polybutadiene chain via a urethane bond is preferred. The reason is that in this case, the increase in adhesive strength is particularly significantly suppressed. As an example of such a compound, two-terminal (meth)acrylic acid modified urethane bond type polybutadiene can be listed. In addition, as other (meth)acrylates containing allylic hydrogen, two-terminal (meth)acrylic acid modified polybutadiene, (meth)acrylate dicyclopentenyloxyethyl ester, (meth)acrylate dicyclopentenyl ester, (meth)acrylate isopentenyl ester can be listed.

[0046] (Meth) acrylic resin can be produced by polymerizing the above-mentioned raw material mixture by light irradiation or heating. When polymerization is performed by light irradiation, the raw material mixture preferably contains a photopolymerization initiator. A photopolymerization initiator refers to a compound that cuts the molecule and splits into two or more free radicals by irradiation with, for example, ultraviolet light or visible light (for example, a wavelength of 200 to 700 nm, preferably 250 to 500 nm, and more preferably 300 to 450 nm). As a photopolymerization initiator, a phenylalanone-based photopolymerization initiator such as 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, and 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butane-1-one is particularly preferred. The content of the photopolymerization initiator relative to 100 parts by mass of the raw material mixture is, for example, 0.1 to 10 parts by mass, for example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0047] The adhesive layer 2 can be formed by applying the adhesive onto the substrate layer 1 using a common coating method such as comma coating, gravure coating, roll coating, or screen coating, or by transferring an adhesive layer applied onto a release film to the substrate layer 1 .

[0048] The thickness of the adhesive layer 2 is preferably 40 μm or less, more preferably 30 μm or less. The thickness is, for example, 5 to 40 μm, preferably 15 to 22 μm, and for example, 5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, or 40 μm. The thickness may be within a range between any two of the values ​​exemplified herein, or less than any one of the values.

[0049] 1-3. Application and physical properties

[0050] The adhesive sheet 10 is preferably used for semiconductor processing. In the manufacturing process of semiconductor components, the adhesive sheet is sometimes attached to an adherend such as a semiconductor wafer, semiconductor substrate, semiconductor device, or various semiconductor packages, and then the adherend is processed. The adhesive sheet 10 is suitable for such applications.

[0051] The tensile storage modulus E' of the adhesive sheet 10 at 40°C is 300 MPa or less. In this case, the bump tracking property tends to be good. The tensile storage modulus E' can be measured by the method shown in the examples. The tensile storage modulus E' (MPa) is, for example, 30 to 300, for example, 30, 50, 100, 150, 200, 250, 300, or may be within a range between any two of the values ​​exemplified here or less than any one. From the viewpoint of making the bump tracking property even better, the thickness of the base layer 1 is preferably 120 μm or more, more preferably 150 μm or more, and even more preferably 200 μm or more.

[0052] 1-4. Method for Manufacturing Adhesive Sheet 10

[0053] In one example, the adhesive sheet 10 can be produced using a roll-to-roll method. More specifically, the adhesive sheet 10 can be produced by rewinding the substrate film forming the substrate layer 1 from a roll, forming the adhesive layer 2 on the rewound substrate film using the above-described method, and then winding the substrate film with the adhesive layer 2 formed thereon into a roll, optionally with a separator film disposed thereon. The winding tension in this process is, for example, 0.1 to 20 N / 100 mm, preferably 0.1 to 15 N / 100 mm, more preferably 0.1 to 10 N / 100 mm, and even more preferably 0.5 to 5 N / 100 mm. The winding tension is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 2, 3, 4, 5, 10, 15, or 20 N / 100 mm, and may be within a range between any two of the values ​​exemplified here.

[0054] This winding tension applies force to the adhesive layer 2, which easily causes adhesive collapse with rounded edges 2a. However, the adhesive layer 2 of the present invention has the aforementioned storage elastic modulus G', thereby suppressing the occurrence of adhesive collapse.

[0055] 2. Manufacturing methods of semiconductor components

[0056] A method for manufacturing a semiconductor component according to an embodiment of the present invention includes a bonding step, a processing step, and a peeling step. Each step will be described in detail below.

[0057] 2-1. Attachment steps

[0058] In the attaching step, Figure 2 As shown, the adhesive sheet 10 is attached to the adherend 4. Thus, a bonded body 11 can be obtained in which the adhesive sheet 10 is attached to the adherend 4. Examples of the adherend 4 include semiconductor wafers, semiconductor substrates, semiconductor devices, and various semiconductor packages.

[0059] In one example, the attaching step can be performed by detecting the edge 2a of the adhesive layer 2 using image recognition, and then attaching the adherend 4 to the adhesive layer 2 while being aligned with the adherend 4 based on the edge 2a. Image recognition failure is likely to occur if the adhesive sags, but the adhesive sheet 10 of this embodiment is less susceptible to adhesive sag, thus suppressing image recognition failure.

[0060] 2-2. Processing steps

[0061] During the processing step, the adherend 4 is processed while the adhesive sheet 10 is attached to the adherend 4. Examples of processing include grinding the back surface of the adherend 4 or dividing the adherend 4. The adhesive sheet 10 needs to hold the adherend 4 during the processing step and needs to have a degree of adhesive strength such that the adherend 4 does not peel off from the adhesive sheet 10 due to the force applied to the adherend 4 during the processing step.

[0062] 2-3. Peeling step

[0063] In the peeling step, the pressure-sensitive adhesive sheet 10 is peeled from the adherend 4 after the processing step.

[0064] Example

[0065] 1. Production of Adhesive Sheet 10

[0066] <Example 1>

[0067] In Example 1, the adhesive sheet 10 was produced by forming the adhesive layer 2 on the base material layer 1. A more detailed description is as follows.

[0068] Formation of adhesive layer 2

[0069] A raw material mixture having the composition shown in parts by mass in Table 1 was prepared, and the mixture was screen-printed on the substrate layer 1 shown in Table 1. The UV-LED light source was used at a cumulative irradiation dose of 3,500 mJ / cm 2 After UV irradiation, the adhesive layer 2 having the thickness shown in Table 1 was formed by aging at 40°C for 4 days.

[0070] [Table 1]

[0071]

[0072] The details of the raw materials used in Table 1 are as follows.

[0073] <Base layer>

[0074] Ionomer substrate 1 (thickness 250 μm): a substrate composed of a metal ion crosslinked product of an ethylene-methacrylic acid copolymer (HMD-250 manufactured by GUNZE).

[0075] Ionomer substrate 2 (thickness 150 μm): a substrate composed of a metal ion crosslinked product of an ethylene-methacrylic acid copolymer (HMD-150 manufactured by GUNZE).

[0076] Ionomer substrate 3 (thickness 100 μm): a substrate composed of a metal ion crosslinked product of an ethylene-methacrylic acid copolymer (HMD-100 manufactured by GUNZE).

[0077] PP-based substrate (thickness 180 μm): PP-based multilayer film, PL118 manufactured by DiaPlus Film

[0078] PET substrate (thickness 100 μm): HL-92W manufactured by Teijin

[0079] <Raw material mixture>

[0080] A mixture of acrylic oligomers and isodecyl acrylate: "Purple Light UV-3630ID80" manufactured by Mitsubishi Chemical

[0081] Isobornyl acrylate: "IBXA" manufactured by Osaka Organic Chemical Industry

[0082] Methacrylic acid-modified polybutadiene with urethane bonds at both ends: "TE2000" manufactured by Nippon Soda (a compound with (meth)acryloyl groups linked to the ends of the polybutadiene chain via urethane bonds)

[0083] Omnirad 379: 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butan-1-one, "Omnirad 379EG" manufactured by IGM Resins BV

[0084] <Examples 2 to 8 and Comparative Examples 1 to 3>

[0085] A pressure-sensitive adhesive sheet 10 was produced by the same method as in Example 1, except that the thicknesses of the base material layer, the raw material mixture, and the pressure-sensitive adhesive layer were changed as shown in Table 1.

[0086] 2. Determination of physical properties

[0087] <Measurement of Adhesive Strength S1>

[0088] Adhesion S1 is measured by the following method. A test piece 10 mm wide and 100 mm long is cut from the portion of the adhesive sheet 10 where the adhesive layer 2 is formed. Using this test piece, the adhesive strength measurement method of JIS Z0237 (2009) (Method 1: Test method for peeling the tape and sheet at 180° from a stainless steel test plate) is used for measurement. Specifically, a crimping device (roller weight 2 kg) is used to crimp the test piece to a cleaned adherend (Si wafer). The test piece is then peeled at 180° from the adherend using a universal tensile testing machine (Tensilon, model: RTG-1210, manufactured by ORIENTEC) at a temperature of 23°C and a humidity of 50%. The adhesive strength is measured under the following conditions when the test piece is peeled at 180° from the adherend. The measurement result is converted to a value for a width of 20 mm.

[0089] Measurement mode: Tensile

[0090] Tensile speed: 300mm / min

[0091] Distance between chucks: 50mm

[0092] Measurement sample width: 10mm

[0093] <Shear storage modulus G' of adhesive layer at 40°C>

[0094] The raw material mixture used in each example and comparative example was applied to the release-treated surface of the release-treated polyethylene terephthalate film to form a coating layer at a thickness of 100 μm, and then irradiated at a dose of 3500 mJ / cm 2 The coating layer was irradiated with UV light at a wavelength of 365 nm to initiate a UV curing reaction. The resulting adhesive layer was then peeled from the release-treated surface, overlapped to a thickness of 0.8 mm, and cut into 8 mm diameters to prepare a sample. Measurements were performed in shear mode using a viscoelasticity measuring instrument (MCR-301, manufactured by Anton Paar) under the following conditions, obtaining the shear storage modulus G' at 40°C.

[0095] Frequency: f = 1 Hz

[0096] Temperature: -50~150℃

[0097] Heating rate: 4℃ / min

[0098] Fixture: Parallel plate φ8mm

[0099] Load: 3N

[0100] Gap: 0.8mm

[0101] <Tensile Storage Modulus E' of Adhesive Sheet 10 at 40°C>

[0102] The adhesive sheet 10 prepared in each example and comparative example was cut into pieces with a width of 5 mm and a length of 50 mm and measured using a viscoelasticity measuring apparatus (RSA-III manufactured by TA Instruments) under the following conditions to obtain the tensile storage modulus E' at 40°C.

[0103] Frequency: f = 1 Hz

[0104] Temperature: -50~150℃

[0105] Heating rate: 5℃ / min

[0106] Chuck width: 10mm

[0107] Strain rate: 0.07%

[0108] 3. Evaluation of Adhesive Sheet 10

[0109] Various evaluations were performed on the produced pressure-sensitive adhesive sheet 10. The results are shown in Table 1.

[0110] As shown in Table 1, all Examples achieved good results in all evaluation items. On the other hand, all Comparative Examples were inferior to the Examples in at least one evaluation item.

[0111] The details of the evaluation method are as follows.

[0112] <Paste collapse resistance>

[0113] like Figure 3 As shown, an adhesive layer 2 is formed under the same conditions as in the above-mentioned embodiment and comparative example in such a manner as to form an opening 2b of φ3 mm. Next, a PET separator (RF2·PET50csSW (MD) manufactured by Im Co.) having a thickness of 50 μm is bonded to the adhesive layer 2 with the release surface facing the adhesive layer 2 side to prepare an adhesive sheet 10 for evaluation. The prepared adhesive sheet 10 is wound around an ABS (acrylonitrile-butadiene-styrene resin) core having an outer diameter of 84.2 mm at a winding tension of 1.1 N / 100 mm, and is wound (1) 50 m or (2) 100 m to prepare an adhesive sheet roll for evaluation, which is then aged at 40°C for 5 days. Thereafter, a sheet containing the adhesive sheet is cut out from the inner side of the roll of the adhesive sheet. Figure 3The shape of the adhesive layer 2 was identified using a CCD camera (sensor size: 1 / 2 inch, number of pixels: 768 (H) × 494 (V), field of view: 12 mm square (W / D 320 mm)) with the surface opposite to the separator bonding surface facing the camera. The paste collapse was determined based on whether or not the recognition was successful, and evaluation was performed according to the following criteria. The number of samples was 20.

[0114] ◎ (Excellent): Both (1) and (2) can be identified

[0115] ○ (Good): All of (1) are identifiable, and some of (2) are not identifiable

[0116] ×(Not possible): Parts of (1) and (2) cannot be identified.

[0117] <Bump followability>

[0118] The bump following property was evaluated by the method shown below.

[0119] Frame attachment steps

[0120] First, the pressure-sensitive adhesive sheet 10 is attached to the annular frame.

[0121] Wafer attachment step, heating step

[0122] Next, an adhesive sheet is attached to the semiconductor wafer on the surface of the semiconductor wafer provided with a convex portion in a reduced pressure chamber. As a semiconductor wafer, one having a diameter of 8 inches, a thickness of 725 μm and a bump (protruding electrode) with a height of 200 μm formed in an area other than 3.0 mm of the periphery is used. The interval between adjacent bumps is 400 μm. The pressure in the reduced pressure chamber is 100 Pa. Next, the adhesive sheet to which the semiconductor wafer is attached is taken out of the reduced pressure chamber and heated at 120°C for 1 minute from the back side of the wafer using a hot plate. Then, the adhesive sheet is cut along the periphery of the semiconductor wafer, and the annular frame is separated from the adhesive sheet 10.

[0123] After the above-described cutting step, the adhesive sheet 10 with the semiconductor wafer attached thereto was measured for the distance between the base layer 1 and the bumps, and the following rate (=the distance between the base layer 1 and the bumps / the height of the bumps) was calculated. The bump following property was evaluated based on the following criteria based on the following rate.

[0124] ◎(Excellent): Follow-up rate is above 90%

[0125] ○ (Good): Follow-up rate is 80% or higher and less than 90%

[0126] △(OK): Follow-up rate is 70% or higher and less than 80%

[0127] ×(Not allowed): Follow rate is less than 70%

[0128] Description of Reference Numerals

[0129] 1: Base material layer

[0130] 1a: One main surface

[0131] 2: Adhesive layer

[0132] 2a: Edge

[0133] 2b: Opening

[0134] 4: Adhesive

[0135] 10: Adhesive sheet

[0136] 11: Conjugate

Claims

1. An adhesive sheet comprising a substrate layer and an adhesive layer provided on the substrate layer, The adhesive layer is formed from a (meth)acrylic resin composition, The (meth)acrylic resin composition comprises a (meth)acrylic resin, The tensile storage modulus of the adhesive sheet at 40°C is 300 MPa or less, The adhesive layer has a shear storage modulus of 350 kPa or greater at 40°C.

2. The adhesive sheet according to claim 1, wherein The substrate layer comprises an ionomer.

3. The adhesive sheet according to claim 1, wherein The pressure-sensitive adhesive layer is configured so that its adhesive strength is not reduced by irradiation with active energy rays.

4. The adhesive sheet according to claim 1, wherein The adhesive layer has an adhesive strength of 0.5 to 1.8 N / 20 mm or less at 23° C. and 50% humidity.

5. The adhesive sheet according to claim 1, wherein The thickness of the adhesive layer is 30 μm or less.

6. The adhesive sheet according to claim 1, wherein The adhesive layer is provided only on a partial area of ​​one main surface of the base layer.

7. The adhesive sheet according to claim 1, wherein The thickness of the substrate layer is 50 to 400 μm.

8. The adhesive sheet according to any one of claims 1 to 7, wherein The adhesive sheet is used for semiconductor processing applications.

Images