Adhesive sheet

Abstract

The present application is an adhesive sheet comprising a resin composition, the resin composition having a thermosetting resin, and the resin composition after thermal curing has a parallel light transmittance of 80% or more at a wavelength of 350 nm for a 20-μm-thick sheet.

Description

Technical Field

[0001] This invention relates to adhesive sheets. Background Technology

[0002] Adhesive sheets containing epoxy resin and acrylic resin are used for bonding glass components to each other (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-140408 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, adhesive sheets are used when bonding the glass components in an ultraviolet sensor to other components, but depending on where the adhesive sheets are used, they can affect the sensitivity of the ultraviolet sensor.

[0008] Therefore, adhesive sheets with excellent UV transmittance are required.

[0009] Therefore, the objective of this invention is to provide an adhesive sheet with excellent ultraviolet transmittance after thermosetting.

[0010] Solution for solving the problem

[0011] The adhesive sheet of the present invention is an adhesive sheet comprising a resin composition.

[0012] The aforementioned resin composition is a thermosetting resin.

[0013] The heat-cured resin composition of the above-mentioned 20 μm thick sheet has a parallel light transmittance of more than 80% under light with a wavelength of 350 nm. Detailed Implementation

[0014] Hereinafter, one embodiment of the adhesive sheet of the present invention will be described.

[0015] The adhesive sheet in this embodiment is composed of a resin composition.

[0016] The aforementioned resin composition comprises an organic component including a thermosetting resin.

[0017] In addition, the adhesive sheet of this embodiment may contain inorganic components including inorganic fillers.

[0018] The adhesive sheet of this embodiment has a single-layer structure composed of a resin composition.

[0019] The aforementioned organic components are thermosetting resins.

[0020] In addition, the aforementioned organic components may contain antioxidants.

[0021] Furthermore, the aforementioned organic components may contain silane coupling agents.

[0022] In the adhesive sheet of this embodiment, it is important that the parallel light transmittance of the 20 μm thick sheet of the aforementioned resin composition after thermosetting is 80% or more under light with a wavelength of 350 nm, preferably 82% or more, more preferably 85% or more, and even more preferably 90% or more.

[0023] It should be noted that the upper limit for the transmittance of parallel light is 100%.

[0024] The aforementioned parallel light transmittance can be measured by determining the total light transmittance and diffusion transmittance, and calculated using the following formula.

[0025] Parallel light transmittance (%) = Total light transmittance (%) - Diffusion transmittance (%)

[0026] It should be noted that the total light transmittance and diffusion transmittance are values ​​obtained by measuring a 20 μm thick sheet of the aforementioned resin composition as a cured sample, based on JIS K7105 (old; now obsolete) (ISO13468-2:1999), and can be measured as follows.

[0027] That is, prepare the following device: set an inlet opening and an outlet opening on the integrating sphere to allow light to pass through, place the sample at the inlet opening, and install a reflector at the outlet opening, thereby using the integrating sphere to detect all light incident on the sample in the thickness direction and light emitted from the sample.

[0028] Next, the reflector at the outlet opening is removed, and the light incident on the sample along its thickness direction and emitted from the sample, excluding the direction of light propagation, is measured. Then, the ratio of the detected light intensity to the intensity of the incident light (incident light intensity) is calculated (detected light intensity / incident light intensity). This ratio (detected light intensity / incident light intensity) is used as the diffusion transmittance.

[0029] Furthermore, without removing the reflector at the outlet opening, all incident light rays and rays emitted from the sample along its thickness direction are measured. Next, the ratio of the detected light intensity to the intensity of the incident light (incident light intensity) is calculated (detected light intensity / incident light intensity). This ratio (detected light intensity / incident light intensity) is used as the total light transmittance.

[0030] For example, total light transmittance and diffusion transmittance can be measured using a V-670DS (manufactured by JASCO).

[0031] The aforementioned thermosetting resin preferably includes an acrylic resin having an epoxy group.

[0032] The aforementioned organic components preferably comprise 90-100% by mass, more preferably 95-100% by mass of the aforementioned acrylic resin.

[0033] The adhesive sheet of this embodiment has excellent ultraviolet transmittance after thermosetting because the aforementioned organic components contain more than 90% by mass of the aforementioned acrylic resin.

[0034] Furthermore, since the aforementioned acrylic resin has epoxy groups, the adhesive sheet of this embodiment can be cured by heating with epoxy groups, thus functioning as an adhesive sheet.

[0035] Furthermore, the adhesive sheet of this embodiment can function as an adhesive sheet even if it does not substantially possess a curing agent with an aromatic ring (e.g., phenolic resin, epoxy resin with an aromatic ring, etc.).

[0036] Aromatic rings reduce the transmittance of ultraviolet light. Therefore, based on this point, the adhesive sheet of this embodiment also has excellent ultraviolet transmittance after thermosetting.

[0037] The adhesive sheet of this embodiment preferably does not substantially contain a curing agent with an aromatic ring.

[0038] The aforementioned acrylic resins preferably contain monomers with epoxy groups as constituent units.

[0039] Examples of monomers containing epoxy groups include (meth)acrylates.

[0040] Examples of (meth)acrylates with epoxy groups include glycidyl methacrylate.

[0041] The epoxy equivalent of the aforementioned acrylic resin is preferably 300 to 1500, more preferably 300 to 1100.

[0042] The adhesive sheet of this embodiment improves adhesive strength by making the epoxy equivalent of the aforementioned acrylic resin 1500 or less.

[0043] Furthermore, the adhesive sheet of this embodiment exhibits good pre-curing shelf life by having the epoxy equivalent of the aforementioned acrylic resin be 300 or higher. Specifically, by having the epoxy equivalent of the aforementioned acrylic resin be 300 or higher, the adhesive sheet of this embodiment can suppress the reaction of epoxy groups before curing, thereby preventing changes in properties.

[0044] If the resin composition becomes too hard due to curing, it will exert local stress on the adhesive sheet under high temperature and humidity, which may cause the adhesive sheet to peel off from the adhered object.

[0045] However, by making the epoxy equivalent of the aforementioned acrylic resin 300 or more, the adhesive sheet of this embodiment can suppress the resin composition from becoming too hard due to curing, thereby suppressing peeling from the adhered object.

[0046] The epoxy equivalent of the aforementioned acrylic resin refers to "the mass of an acrylic resin containing 1 equivalent of epoxy groups".

[0047] The epoxy equivalent of the aforementioned acrylic resin can be determined based on the proportion of each epoxy-containing monomer contained in the aforementioned acrylic resin.

[0048] For example, if the monomers constituting an acrylic resin have only glycidyl methacrylate (GMA) (molecular weight: 142, number of epoxy groups in 1 molecule: 1) as the only monomer with an epoxy group, and the acrylic resin contains 42% by mass of glycidyl methacrylate (GMA), the epoxy equivalent of the aforementioned acrylic resin can be calculated as follows.

[0049] 142 / 1 / (42% by mass ÷ 100% by mass) = 338

[0050] The aforementioned acrylic resins preferably contain 10-50% by mass, more preferably 16-40% by mass, of epoxy-containing monomers.

[0051] The adhesive sheet of this embodiment improves adhesive strength by containing 10% or more of an epoxy group-containing monomer in the aforementioned acrylic resin.

[0052] Furthermore, the adhesive sheet of this embodiment exhibits good pre-curing shelf life by containing less than 50% by mass of epoxy-containing monomers in the aforementioned acrylic resin. Specifically, by containing less than 50% by mass of epoxy-containing monomers in the aforementioned acrylic resin, the adhesive sheet of this embodiment can suppress the reaction of epoxy groups and the resulting changes in properties before curing.

[0053] If the resin composition becomes too hard due to curing, it will exert local stress on the adhesive sheet under high temperature and humidity, which may cause the adhesive sheet to peel off from the adhered object.

[0054] However, the adhesive sheet of this embodiment contains less than 50% by mass of an epoxy group monomer in the aforementioned acrylic resin, thereby preventing the resin composition from becoming too hard due to curing, and as a result, preventing peeling from the adhered material.

[0055] Other constituent units in the aforementioned acrylic resins, besides monomers with epoxy groups, include (meth)acrylates containing hydrocarbon groups, monomers containing carboxyl groups, acid anhydride monomers, monomers containing hydroxyl groups, monomers containing sulfonic acid groups, and monomers containing phosphate groups. Additionally, acrylamide and acrylonitrile can also be listed.

[0056] Examples of the aforementioned hydrocarbon-containing (meth)acrylates include, for example, alkyl (meth)acrylates, cycloalkyl (meth)acrylates, and aryl (meth)acrylates.

[0057] Examples of alkyl groups used in the above-mentioned alkyl methacrylates include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, undecyl, dodecyl (lauryl), tridecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, etc.

[0058] Examples of "cycloalkyl" in the above-mentioned (meth)acrylate cycloalkyl esters include cyclopentyl and cyclohexyl.

[0059] For example, phenyl and benzyl groups can be listed as "aryl" in the above-mentioned aryl methacrylates.

[0060] Examples of the aforementioned carboxyl-containing monomers include acrylic acid, methacrylic acid, carboxyethyl methacrylate, carboxypentyl methacrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0061] Examples of the aforementioned anhydride monomers include maleic anhydride and itaconic anhydride.

[0062] Examples of hydroxyl-containing monomers mentioned above include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 12-hydroxylaurate methacrylate, and methyl methacrylate (4-hydroxymethylcyclohexyl)

[0063] Examples of the sulfonic acid-containing monomers mentioned above include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropane sulfonic acid, (meth)acrylamide propane sulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalene sulfonic acid.

[0064] Examples of the aforementioned phosphate-containing monomers include, for example, 2-hydroxyethylacryloyl phosphate.

[0065] The aforementioned acrylic resins may contain only one or more constituent units other than the epoxy-containing monomers mentioned above.

[0066] As constituent units other than monomers with epoxy groups included in the aforementioned acrylic resins, ethyl (meth)acrylate and butyl (meth)acrylate are preferred from the viewpoints of easy adjustment of the adhesive sheet's tackiness and the excellent UV transmittance of the adhesive sheet after thermosetting.

[0067] The aforementioned acrylic resins are preferably aliphatic resins.

[0068] It should be noted that in this specification, "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0069] In addition, "(meth)acrylate" is a concept that includes both acrylates and methacrylates.

[0070] The preferred mass-average molecular weight of the aforementioned acrylic resin is 2.0 × 10⁻⁶. 3 ~2.9×10 5 More preferably 1.0×10 4 ~2.0×10 5 .

[0071] The adhesive sheet in this embodiment has a mass-average molecular weight of 2.0 × 10⁻⁶. 3 ~2.9×10 5 This gives it the advantages of excellent wettability and adhesion.

[0072] Furthermore, the adhesive sheet of this embodiment has a mass-average molecular weight of 2.0 × 10⁻⁶. 3 ~2.9×10 5 This provides the advantage that, when bonded to the substrate in an embedded manner (e.g., when bonded to a recess in a substrate with a recessed surface), it can be fully embedded into the substrate (hereinafter also referred to as "excellent embeddability").

[0073] It should be noted that the mass-average molecular weight refers to the value obtained by gel permeation chromatography (GPC) and conversion to polystyrene.

[0074] For example, the mass-average molecular weight can be determined as follows: using the GPC "HLC-8320GPC" manufactured by Tosoh Corporation as the device, and the column as the column, and using the column "TSK Guard Column H" manufactured by Tosoh Corporation. H R (S)”, TSK GMH, manufactured by Tosoh Corporation HR -H(S)”, and the column “TSK GMH” manufactured by Tosoh Corporation. HRThe column consisted of three columns connected in series, with "TSK gel SuperH-RC" as the reference column and tetrahydrofuran as the eluent. GPC was measured at a column temperature of 40°C and a flow rate of 0.5 ml / min. The results were calculated and expressed as polystyrene equivalents.

[0075] From the perspectives of preservation and UV transmittance after thermosetting, the aforementioned thermosetting resin is preferably substantially free of substances with a mass-average molecular weight of 2 × 10⁻⁶. 3 The following resins.

[0076] Does the aforementioned thermosetting resin substantially not contain a mass-average molecular weight of 2×10⁻⁶? 3 The following resins can be identified using the same method as the method for determining mass-average molecular weight.

[0077] When the aforementioned resin composition contains inorganic fillers, from the viewpoint of improving the wettability of the inorganic fillers and consequently improving the adhesion, it is preferable to contain a silane coupling agent.

[0078] Examples of silane coupling agents include, for instance, silane coupling agents having epoxy groups.

[0079] From the viewpoint of excellent affinity with epoxy-based acrylic resins, epoxy-based silane coupling agents are preferred as the aforementioned silane coupling agents.

[0080] Examples of epoxy-containing silane coupling agents include, for example, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (e.g., “KBM-303” manufactured by Shin-Etsu Silicones), 3-epoxypropoxypropylmethyldimethoxysilane (e.g., “KBM-402” manufactured by Shin-Etsu Silicones), 3-epoxypropoxypropyltrimethoxysilane (e.g., “KBM-403” manufactured by Shin-Etsu Silicones), 3-epoxypropoxypropylmethyldiethoxysilane (e.g., “KBE-402” manufactured by Shin-Etsu Silicones), and 3-epoxypropoxypropyltriethoxysilane (e.g., “KBE-403” manufactured by Shin-Etsu Silicones).

[0081] When the aforementioned resin composition contains inorganic fillers, it preferably contains 0.1 to 5.0% by mass, more preferably 0.2 to 4.0% by mass, of a silane coupling agent.

[0082] The aforementioned resin composition contains more than 0.1% by mass of a silane coupling agent, thereby improving the wettability of the inorganic filler, which in turn improves the adhesion.

[0083] In addition, the aforementioned resin composition contains less than 5.0% by mass of silane coupling agent, thereby enabling it to contain a greater amount of acrylic resin, resulting in superior UV transmittance after thermosetting.

[0084] From the viewpoint of suppressing the reduction of ultraviolet transmittance of the adhesive sheet after thermosetting due to the oxidation of the aforementioned acrylic resin, the adhesive sheet of this embodiment preferably contains an antioxidant.

[0085] Examples of antioxidants mentioned above include hindered phenolic antioxidants and phosphorus-based antioxidants.

[0086] The aforementioned resin composition contains preferably 0.1 to 5% by mass, more preferably 0.1 to 2% by mass, of an antioxidant.

[0087] The aforementioned resin composition contains more than 0.1% by mass of antioxidant, thereby inhibiting the formation of carbon-carbon double bonds in acrylic resins due to oxidation of acrylic resins, and as a result, inhibiting the reduction of ultraviolet transmittance.

[0088] In addition, the aforementioned resin composition contains less than 5% by mass of antioxidant, thereby containing a greater amount of acrylic resin. As a result, the UV transmittance after thermosetting is superior, and the reduction in UV transmittance caused by the antioxidant itself can be suppressed.

[0089] From the viewpoint that the reactivity of the epoxy groups of acrylic resin can be improved by the functional groups possessed by the inorganic filler, it is preferable that the adhesive sheet of this embodiment contains an inorganic filler.

[0090] Examples of inorganic fillers mentioned above include silica particles, boron nitride particles, and alumina particles.

[0091] From the viewpoints of operability, adhesion and reliability, the aforementioned resin composition contains preferably 15 to 60% by mass, more preferably 20 to 50% by mass, of inorganic filler.

[0092] In the aforementioned resin composition, from the viewpoints of operability, adhesion, and reliability, the D50 of the aforementioned inorganic filler is preferably 5 to 30 nm, more preferably 5 to 20 nm.

[0093] The D50 of inorganic fillers refers to the particle size at which the cumulative volume of the bubbles is 50% in the cumulative frequency distribution curve of particle size plotted with the horizontal axis as the particle size and the vertical axis as the bubble volume.

[0094] It should be noted that the D50 of inorganic fillers can be measured using a laser diffraction particle size distribution measuring device.

[0095] The thickness of the adhesive sheet in this embodiment is preferably 5 to 200 μm, more preferably 5 to 180 μm.

[0096] From the viewpoint of suppressing adhesion so as to facilitate adhesion to the substrate (operability viewpoint), the tensile storage modulus of the adhesive sheet in this embodiment before thermosetting at 25°C is preferably 10MPa to 3,000MPa, more preferably 20MPa to 2,000MPa, and even more preferably 30MPa to 1,500MPa.

[0097] From the viewpoint of improving the adhesion after thermosetting, the tensile loss modulus of the adhesive sheet in this embodiment after thermosetting at 120°C is preferably 0.1MPa to 5MPa, more preferably 0.2MPa to 4MPa, and even more preferably 0.3MPa to 3MPa.

[0098] From the viewpoint of improving the adhesion after thermosetting, the tensile storage modulus of the adhesive sheet in this embodiment after thermosetting at 250°C is preferably 0.5MPa to 150MPa, more preferably 1MPa to 100MPa, and even more preferably 10MPa to 90MPa.

[0099] The tensile storage modulus and tensile loss modulus can be calculated as follows.

[0100] That is, the adhesive sheet is heat-cured, and a test piece (length: 40mm, width: 10mm) is cut from the heat-cured adhesive sheet.

[0101] Next, a dynamic viscoelasticity measuring device (trade name "RSA-III", manufactured by TA Instruments) was used to conduct a tensile test on the test object to determine the tensile storage modulus and tensile loss modulus.

[0102] The conditions for this tensile test are as follows.

[0103] Measurement mode: Tensile mode

[0104] Initial chuck spacing: 22.5mm

[0105] Measurement temperature range: 0℃~150℃

[0106] Heating rate: 10℃ / minute

[0107] Dynamic strain: ±0.5μm

[0108] Frequency: 10Hz

[0109] In addition, "after heat curing" in this embodiment means "after heating until the adhesive sheet is fully cured". For example, the heating temperature is 175°C.

[0110] The shear storage modulus of the adhesive sheet before thermosetting at 100°C in this embodiment is preferably 5 kPa to 800 kPa, more preferably 6 kPa to 600 kPa, and even more preferably 7 kPa to 400 kPa.

[0111] The adhesive sheet of this embodiment has the advantages of excellent wettability and embeddability by ensuring that the shear storage modulus at 100°C before thermosetting is within the above-mentioned range.

[0112] The shear storage modulus can be calculated as follows.

[0113] That is, the adhesive sheet is punched to make a cylindrical sample (Φ7.5mm×1mm).

[0114] Next, a shear vibration of 1 Hz was applied to one circular surface of the aforementioned sample at a temperature of 120°C, and the shear vibration transmitted to the other circular surface was measured and analyzed to determine the shear storage modulus.

[0115] The determination of shear vibration and the analysis of the measured values ​​can be performed using a viscoelastic measuring device (manufactured by HAAK E, model: Mars series).

[0116] From the viewpoint of improving the adhesion after thermosetting, the adhesion strength of the adhesive sheet of this embodiment to the Si wafer at 120°C after thermosetting is preferably 0.5 MPa or more, and more preferably 0.8 MPa or more.

[0117] It should be noted that the upper limit of the adhesion force to Si wafers at 120℃ after thermosetting is usually 5MPa.

[0118] The aforementioned adhesive force can be calculated as follows.

[0119] First, the cut strip, which has an adhesive layer and a substrate layer stacked on top, is placed with the adhesive layer facing up.

[0120] Next, an adhesive sheet is laminated on the adhesive layer of the dicing tape, and then a Si wafer (for example, a bare wafer can be used) (thickness: 500 μm) is placed on the adhesive sheet. The adhesive sheet and the Si wafer are heated at 60°C to perform a lamination process, thereby obtaining a Si wafer with an adhesive sheet.

[0121] Next, using a dicing device, a 5mm × 5mm Si chip with adhesive tabs is obtained from the Si wafer with adhesive tabs.

[0122] Next, the Si chip with the adhesive sheet is bonded to the Si wafer (for example, a bare wafer can be used) (thickness: 500 μm) at a temperature of 150°C on the adhesive sheet side, for 2 seconds per 500g of adhesive sheet (e.g., 4 seconds when the adhesive sheet is 1000g). The adhesive sheet is then fully cured by heating (150°C, 1 hour) to obtain the test sample.

[0123] Next, the adhesive strength is determined by a shear strength test based on 120°C. For example, Dega4000 can be used in the adhesive strength test.

[0124] In the determination of the aforementioned resin composition based on Fourier transform infrared absorption analysis (FT-IR), the ratio of the absorbance AbC6H6 derived from the aromatic ring to the absorbance AbCO derived from the carbonyl group (AbC6H6 / AbCO) is preferably 0.05 or less, more preferably 0.04 or less, and even more preferably 0.03 or less.

[0125] Aromatic rings reduce the transmittance of ultraviolet light. In the adhesive sheet of this embodiment, the AbC6H6 / AbCO ratio of the aforementioned resin composition is 0.05 or less, resulting in excellent ultraviolet transmittance after thermosetting.

[0126] In addition, the AbC6H6 / AbCO ratio is usually above 0.01.

[0127] The aforementioned AbC6H6 / AbCO can be calculated as follows.

[0128] First, the infrared absorption spectrum of the aforementioned resin composition was determined by Fourier transform infrared absorption analysis (FT-IR).

[0129] The measurement conditions are as follows.

[0130] ATR (Automatic Transmission Reflection) method

[0131] Wave number: 500–4000 cm -1

[0132] Total number of times: 32

[0133] As the measuring device, the "NICOLET380FT-R" manufactured by Thermo Fisher Scientific can be used.

[0134] Next, based on the obtained infrared absorption spectrum, the 1506 cm⁻¹ value was read. -1 The measuring point and 1522cm -1 When the straight line connecting the measurement points is used as the baseline, the distance is 1506–1522 cm. -1 The absorbance at the highest point of the peak in the wavenumber range is taken as AbC6H6.

[0135] In addition, based on the obtained infrared absorption spectrum, the 1650 cm⁻¹ value was read. -1 The measuring point and 1800 cm -1 When the straight line connecting the measurement points is used as the baseline, the distance is 1650–1800 cm. -1 The absorbance at the highest point of the peak within the wavenumber range is taken as AbCO.

[0136] The adhesive sheet of this embodiment is particularly suitable for use when the material to be bonded is glass or silicon.

[0137] The adhesive sheet of this embodiment can be used as a component of an ultraviolet sensor.

[0138] If we take an example of an ultraviolet sensor that can use the adhesive sheet of this embodiment, the following ultraviolet sensors can be listed.

[0139] The ultraviolet sensor of this embodiment includes: a light-receiving section having a light-receiving surface for receiving ultraviolet (UV) light, and a cover sheet that directly or indirectly covers the light-receiving section.

[0140] The cover sheet has a stacked structure of at least two layers, including a cover sheet body made of a glass plate or the like and an adhesive layer made of an adhesive sheet of this embodiment.

[0141] The ultraviolet sensor of this embodiment is configured such that ultraviolet light can pass through the aforementioned adhesive layer to reach the aforementioned light receiving part and be detected.

[0142] The aforementioned adhesive layer can be used to directly cover the aforementioned light receiving surface by bonding the aforementioned cover sheet body to the aforementioned light receiving surface or to a region further outward than the aforementioned light receiving portion. Alternatively, the aforementioned cover sheet can be used to indirectly cover the aforementioned light receiving portion by bonding the aforementioned cover sheet to a support member that is supported in a state separate from the aforementioned light receiving surface, thereby providing a space in the middle.

[0143] The matters disclosed in this specification include the following. (1)

[0145] An adhesive sheet comprising a resin composition,

[0146] The aforementioned resin composition is a thermosetting resin.

[0147] The heat-cured resin composition of the above-mentioned 20 μm thick sheet has a parallel light transmittance of more than 80% under light with a wavelength of 350 nm.

[0148] According to the aforementioned configuration, the adhesive sheet exhibits excellent ultraviolet transmittance. (2)

[0150] According to the adhesive sheet described in (1) above, its tensile storage modulus at 25°C before thermosetting is 10MPa to 3,000MPa.

[0151] According to the aforementioned configuration, the adhesiveness of the adhesive sheet is suppressed, thereby facilitating adhesion to the substrate. In other words, the aforementioned adhesive sheet offers excellent operability. (3)

[0153] According to the adhesive sheet described in (1) or (2) above, its shear storage modulus at 100°C before thermosetting is 5 kPa to 800 kPa.

[0154] According to the aforementioned configuration, the adhesive sheet exhibits excellent wettability and embeddability.

[0155] It should be noted that excellent embeddability means that, as described above, when the aforementioned adhesive piece is bonded to the substrate in an embedding manner (for example, when it is bonded to a recess of the substrate with a recess on its surface), the aforementioned adhesive piece can be fully embedded into the substrate. (4)

[0157] According to any one of (1) to (3) above, the adhesive sheet, wherein the aforementioned resin composition after heat curing has an adhesion force of 0.5 MPa or more to the Si wafer at 120°C.

[0158] According to the aforementioned configuration, the adhesive properties of the aforementioned adhesive sheet are improved after thermosetting. (5)

[0160] The adhesive sheet according to any one of (1) to (4) above has a tensile loss modulus of 0.1 MPa to 5 MPa at 120°C after thermosetting.

[0161] According to the aforementioned configuration, the adhesive properties of the aforementioned adhesive sheet are improved after thermosetting. (6)

[0163] The adhesive sheet according to any one of (1) to (5) above has a tensile storage modulus of 0.5 MPa to 150 MPa at 250°C after thermosetting.

[0164] According to the aforementioned configuration, the adhesive properties of the aforementioned adhesive sheet are improved after thermosetting.

[0165] It should be noted that the adhesive sheet of the present invention is not limited to the embodiments described above. Furthermore, the adhesive sheet of the present invention is not limited to the effects described above. Moreover, the adhesive sheet of the present invention can be modified in various ways without departing from the spirit of the present invention.

[0166] For example, the adhesive sheet of this embodiment has a single-layer structure made of a resin composition, but the adhesive sheet of the present invention may also be a laminate of layers made of the aforementioned resin composition and other layers.

[0167] [Example]

[0168] Next, the present invention will be described in more detail by way of examples and comparative examples.

[0169] The following embodiments are provided to illustrate the present invention in more detail, but do not limit the scope of the invention.

[0170] (Example 1)

[0171] Acrylic resin, inorganic filler, silane coupling agent, and antioxidant were dissolved in a solvent according to the mixing ratios shown in Table 1 below to prepare adhesive composition solution A (solid component concentration: 20% by mass).

[0172] It should be noted that the following substances are used as acrylic resins, inorganic fillers, silane coupling agents, and antioxidants.

[0173] Acrylic resins: Acrylic resins comprising 42% by mass of glycidyl methacrylate (GMA), 50% by mass of ethyl acrylate (EA), and 8% by mass of butyl methacrylate (BMA) as constituent units (weight average molecular weight: 240,000).

[0174] Inorganic filler: Silica particles (MEK-ST-40, manufactured by Nissan Chemical Co., Ltd.)

[0175] Silane coupling agent: 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM303, manufactured by Shin-EtsuSilicones)

[0176] Antioxidant: Hindered phenolic antioxidant (Irganox 1010, manufactured by BASF Japan Ltd.)

[0177] Solvent: Methyl ethyl ketone

[0178] In addition, a polyethylene terephthalate film (thickness: 50 μm) that has been treated with silicone for mold release is prepared as an insulator.

[0179] Next, the aforementioned adhesive composition solution A is applied to the surface of the aforementioned isolator (the side that has undergone demolding treatment), and then heated at 130°C for 2 minutes to dry it, thereby creating an adhesive sheet (thickness: 20 μm) on the isolator.

[0180] (Example 2)

[0181] Acrylic resin, inorganic filler, silane coupling agent, and antioxidant were dissolved in a solvent according to the mixing ratios shown in Table 1 below to prepare adhesive composition solution B (solid component concentration: 20% by mass).

[0182] It should be noted that, except for the materials described below, the same materials as in Example 1 are used.

[0183] Acrylic resins: Acrylic resins comprising 14% by mass of glycidyl methacrylate (GMA), 50% by mass of ethyl acrylate (EA), and 36% by mass of butyl methacrylate (BMA) as constituent units (weight average molecular weight: 20,000).

[0184] Inorganic filler: Silica particles (MEK-EC-2130Y, manufactured by Nissan Chemical Co., Ltd.)

[0185] Next, adhesive composition solution B was used instead of adhesive composition solution A, and otherwise the same procedure was followed as in Example 1 to prepare an adhesive sheet (thickness: 20 μm) on the separator.

[0186] (Example 3)

[0187] Acrylic resin, inorganic filler, silane coupling agent, and antioxidant were dissolved in a solvent according to the mixing ratios shown in Table 1 below to prepare adhesive composition solution C (solid component concentration: 20% by mass).

[0188] It should be noted that, except for the materials described below, the same materials as in Example 1 are used.

[0189] Acrylic resins: Acrylic resins comprising glycidyl methacrylate (GMA) 30% by mass, ethyl acrylate (EA) 42% by mass, and butyl methacrylate (BMA) 28% by mass as constituent units (weight average molecular weight: 100,000).

[0190] Inorganic filler: Silica particles (CHO-ST-M, manufactured by Nissan Chemical Co., Ltd.)

[0191] Next, adhesive composition solution C was used instead of adhesive composition solution A, and otherwise the same procedure was followed as in Example 1 to prepare an adhesive sheet (thickness: 20 μm) on the separator.

[0192] (Comparative Example 1)

[0193] Acrylic resin, phenolic resin as curing agent, inorganic filler, silane coupling agent, and antioxidant are dissolved in solvent according to the mixing ratios shown in Table 1 below to prepare adhesive composition solution D (solid component concentration: 20% by mass).

[0194] It should be noted that, except for the materials described below, the same materials as in Example 1 are used.

[0195] Acrylic resins: Acrylic resins comprising glycidyl methacrylate (GMA) 12% by mass, ethyl acrylate (EA) 52% by mass, and butyl methacrylate (BMA) 36% by mass as constituent units (weight average molecular weight: 300,000).

[0196] Phenolic resin: MEHC-7800H, manufactured by Meiwa Kasei Corporation

[0197] Inorganic filler: Silica particles (SC25R, manufactured by ADMATECHS CO.,LTD.)

[0198] Next, adhesive composition solution D was used instead of adhesive composition solution A, and otherwise the same procedure was followed as in Example 1 to prepare an adhesive sheet (thickness: 20 μm) on the separator.

[0199] (Comparative Example 2)

[0200] Acrylic resin, phenolic resin as curing agent, epoxy resin as curing agent, and inorganic filler are dissolved in a solvent according to the mixing ratios shown in Table 1 below to prepare adhesive composition solution E (solid component concentration: 20% by mass).

[0201] It should be noted that, except for the materials described below, the same materials as in Example 1 are used.

[0202] Acrylic resins: Acrylic resins comprising glycidyl methacrylate (GMA) 12% by mass, ethyl acrylate (EA) 52% by mass, and butyl methacrylate (BMA) 36% by mass as constituent units (weight average molecular weight: 300,000).

[0203] Phenolic resin: MEHC-7800H, manufactured by Meiwa Kasei Corporation

[0204] Epoxy resin: HP-7200, manufactured by DIC Corporation

[0205] Inorganic filler: Silica particles (MEK-ST-ZL, manufactured by Nissan Chemical Co., Ltd.)

[0206] Next, adhesive composition solution E was used instead of adhesive composition solution A, and otherwise the same procedure was followed as in Example 1 to prepare an adhesive sheet (thickness: 20 μm) on the separator.

[0207] The mass-average molecular weight of acrylic resins can be determined using the method described above.

[0208] The following parameters were determined using the methods described above: "average particle size of inorganic filler", "parallel light transmittance after thermosetting (350nm)", "tensile storage modulus at 25°C before thermosetting", "shear storage modulus at 100°C before thermosetting", "adhesion to Si wafer at 120°C after thermosetting", "tensile loss modulus at 120°C after thermosetting", "tensile storage modulus at 250°C after thermosetting", "AbCO", "AbC6H6", and "AbC6H6 / AbCO".

[0209] Their values ​​are shown in Table 1 below.

[0210] <Insertion Test Before Thermosetting>

[0211] The adhesive sheet is attached to one side of the glass plate.

[0212] Next, the glass plate with adhesive sheet is bonded to the substrate with concave and convex surfaces.

[0213] Next, in order to confirm the embedding of the adhesive sheet into the recess of the substrate, the adhesive sheet was photographed from the glass plate side using a microscope (within a 10mm square area) to obtain an image.

[0214] Next, the image is binarized using analytical software to calculate the ratio of the total area of ​​the adhesive piece embedded in the recess to the total area of ​​the recess ((total area of ​​the adhesive piece embedded in the recess / total area of ​​the recess) × 100) (%), and evaluated according to the following criteria.

[0215] 〇:More than 80%

[0216] ×: Less than 80%

[0217] The results are shown in Table 1 below.

[0218] <TCT-based peel test after thermosetting>

[0219] The adhesive sheet is attached to the mirror chip (9.5mm square) at 60°C.

[0220] Next, under the conditions of 120°C, 0.1MPa, and 2 seconds, the adhesive sheet with the mirror chip was bonded to the glass plate with the adhesive sheet side to obtain the sample.

[0221] Next, the sample was heated in a pressure furnace at 150°C and 0.7 MPa for 1 hour.

[0222] Then, using a TCT device (temperature cycling test device), the heat-treated sample was subjected to 1000 cycles of heating and cooling between -40°C and 125°C (1 cycle: 30 minutes).

[0223] Next, visually confirm whether the adhesive sheet has been peeled off from the mirror chip.

[0224] Next, the evaluation will be conducted according to the following criteria.

[0225] 〇: No peeling

[0226] ×: There is peeling

[0227] The results are shown in Table 1 below.

[0228] <Peel test during reflow soldering after thermosetting>

[0229] The adhesive sheet is attached to the mirror chip (9.5mm square) at 60°C.

[0230] Next, under the conditions of temperature 120℃, pressure 0.1MPa and time 2 seconds, the adhesive sheet with mirror chip was bonded to the glass plate with the adhesive sheet side to obtain the sample.

[0231] Next, the sample was heated in a pressure furnace at 150°C and 0.7 MPa for 1 hour.

[0232] Then, the heat-treated sample was placed at 30°C and 60%RH for 72 hours to allow it to absorb moisture.

[0233] Next, the aforementioned moisture-absorbing sample was passed through an IR reflow oven set to maintain a temperature above 260°C for 10 seconds.

[0234] Then, in each of the examples and comparative examples, the above test was performed on 9 samples. For each sample, it was visually confirmed whether the adhesive sheet was peeled off from the mirror chip, and the number of samples that peeled off was counted.

[0235] The results are shown in Table 1 below.

[0236] [Table 1]

[0237]

Claims

1. An adhesive sheet comprising a resin composition, The resin composition comprises a thermosetting resin and inorganic fillers. The thermosetting resin includes acrylic resins having epoxy groups. The content of the inorganic filler is 15-50% by mass. The inorganic filler has a D50 of 5~30nm. The heat-cured resin composition has a 20 μm thick sheet with a parallel light transmittance of over 80% under light at a wavelength of 350 nm, and the adhesive sheet has a tensile storage modulus of 10 MPa to 3,000 MPa at 25 °C before heat curing.

2. The adhesive sheet according to claim 1 has a shear storage modulus of 5 kPa to 800 kPa at 100°C before thermosetting.

3. The adhesive sheet according to claim 1, wherein, The thermosetting resin composition exhibits an adhesion strength of 0.5 MPa or higher to Si wafers at 120°C.

4. The adhesive sheet according to claim 1, wherein the tensile loss modulus at 120°C after thermosetting is 0.1 MPa to 5 MPa.

5. The adhesive sheet according to claim 1, wherein the tensile storage modulus at 250°C after thermosetting is 0.5MPa~150MPa.

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