Electronic material adhesive composition, adhesive sheet, and laminate

Abstract

Provided is an electronic material adhesive composition (13) including a thermosetting resin, wherein a sheet-like cured product formed from the electronic material adhesive composition is present in a phase-separated state in which a first phase is dispersed in a second phase.

Description

Adhesive composition for electronic materials, adhesive sheet and laminate

[0001] This application claims priority to Japanese Patent Application No. 2024-099035, filed on June 19, 2024, the contents of which are incorporated herein by reference.

[0002] Adhesive compositions are widely used in the assembly of electronic devices and the like that use electronic materials. For example, Patent Document 1 describes a pressure-sensitive adhesive sheet that is resistant to foaming and changes in optical properties even in high-temperature environments. Furthermore, Patent Document 2 describes a coverlay film that has excellent electrical properties in the high-frequency range.

[0003] JP 2023-46285 A JP 2011-68713 A

[0004] The present invention provides an adhesive composition for electronic materials, an adhesive sheet, and a laminate suitable for producing electronic materials that have excellent electrical properties and durability.

[0005] The present invention includes the following aspects. [1] An adhesive composition for electronic materials containing a thermosetting resin, wherein a sheet-shaped cured product formed from the adhesive composition for electronic materials exists in a phase-separated state in which a first phase is dispersed in a second phase. [2] The adhesive composition for electronic materials according to [1], wherein, in a cross section of the cured product in a direction perpendicular to the surface of the cured product, the ratio of the area occupied by the first phase to the cross-sectional area of ​​the cured product is 0.2% or more and less than 50.0%. [3] The adhesive composition for electronic materials according to [1] or [2], wherein the cured product in a thickness of 25 μm has a haze value of 10% or more and less than 80%. [4] The average cross-sectional area per first phase is 0.003 μm in a cross section of the cured product in a direction perpendicular to the surface of the cured product. ２ 1.000 μm or more ２[5] The adhesive composition for electronic materials according to any one of [1] to [4], wherein the adhesive composition for electronic materials has a melt viscosity at 130°C of 10,000 mPa·s or more and less than 150,000 mPa·s. [6] The adhesive composition for electronic materials according to any one of [1] to [5], wherein the sheet-like cured product has a glass transition point of less than 0°C. [7] The adhesive composition for electronic materials according to any one of [1] to [6], wherein the adhesive composition for electronic materials comprises the thermosetting resin and an elastomer. [8] The adhesive composition for electronic materials according to any one of [1] to [7], wherein the thermosetting resin comprises at least one of an epoxy resin, a phenolic resin, and a maleimide resin. [9] The adhesive composition for electronic materials according to any one of [1] to [8], wherein the adhesive composition for electronic materials comprises a thermoplastic elastomer.

[10] The adhesive composition for electronic materials according to any one of [1] to [9], wherein the thermosetting resin comprises an aromatic polyether compound having a reactive functional group.

[11] The adhesive composition for electronic materials according to any one of [1] to

[10] , wherein the adhesive composition for electronic materials contains an epoxy resin in an amount of 1.0 mass % or more and less than 10.0 mass %, relative to the total mass of the adhesive composition for electronic materials.

[12] The adhesive composition for electronic materials according to any one of [1] to

[11] , wherein the adhesive composition for electronic materials contains an epoxy resin having a number average molecular weight Mn of 400 or more and less than 3,000.

[13] An adhesive sheet comprising the adhesive composition for electronic materials according to any one of [1] to

[12] .

[14] A laminate comprising the adhesive sheet according to

[13] and protective materials on each of the upper and lower surfaces of the adhesive sheet, wherein the thickness of the protective material on the upper surface and the thickness of the protective material on the lower surface are different.

[15] The laminate according to

[14] , wherein the protective material contains polyethylene terephthalate (PET) or cellulose.

[0006] According to the present invention, it is possible to provide an adhesive composition for electronic materials, an adhesive sheet, and a laminate suitable for producing electronic materials having excellent electrical properties and durability.

[0007] FIG. 1 is a cross-sectional view showing an example of a laminate having protective materials on the upper and lower surfaces of an adhesive sheet.

[0008] The present invention will be described below based on preferred embodiments.

[0009] The adhesive composition for electronic materials of this embodiment is an adhesive composition for electronic materials that contains a thermosetting resin. A sheet-shaped cured product formed from the adhesive composition for electronic materials exists in a phase-separated state in which a first phase is dispersed in a second phase. Here, the first phase and the second phase are phases contained in the sheet-shaped cured product. When the adhesive composition for electronic materials that contains a thermosetting resin is thermally cured in a phase-separated state, the first phase exists as a dispersed phase and the second phase exists as a continuous phase.

[0010] In a cross section of the cured sheet material in a direction perpendicular to the surface of the cured sheet material, the ratio of the area occupied by the first phase to the cross-sectional area of ​​the cured sheet material is preferably 0.2% or more and less than 50.0%.

[0011] The haze value of the sheet-like cured product at a thickness of 25 μm is preferably 10% or more and less than 80%. By dispersing the first phase in the second phase, a relatively large haze value can be obtained.

[0012] Haze is an optical property used to understand the optical properties of polymeric materials such as plastic materials. It is measured as the ratio of light passing through a material such as a film to light scattered by 2.5° or more. Factors that cause light scattering in polymeric materials include the formation of an inhomogeneous state due to the inclusion of impurities, voids, etc. In an inhomogeneous state, an interface between two or more materials may exist in the optical path. Reflection and refraction of incident light at the interface scatters a portion of the incident light, which is observed as haze.

[0013] In the adhesive composition for electronic materials of this embodiment, the sheet-shaped cured product after curing has a first phase and a second phase, with the first phase dispersed in the second phase. In the sheet-shaped cured product after curing, the first phase and the second phase are separated and present non-uniformly, and an interface exists between the first phase and the second phase. The presence of this interface causes reflection and refraction of incident light, resulting in an increased haze value compared to a homogeneous adhesive composition. One factor that causes the increased haze value is that a difference in polarity or molecular weight between the first phase and the second phase induces a sea-island structure, resulting in the formation of a first phase and a second phase with different compositions, with the first phase dispersed in the second phase.

[0014] The difference in polarity and molecular weight between the first phase component and the second phase component affects the size, number, and interface clarity of the first phase, which can result in a change in the haze value. In other words, the haze value is one means of understanding the structure of an adhesive composition, and by controlling the haze value, the peel strength of the adhesive composition to a low-polarity adherend (e.g., a liquid crystal (LCP) film) can be made strong enough for practical use.

[0015] In a cross section of the sheet-like cured material in a direction perpendicular to the surface of the sheet-like cured material, the average cross-sectional area per one of the first phases is 0.003 μm ２ or more or 0.005 μm ２ 1.000 μm or more ２ Preferably, it is less than 0.020 μm ２ 0.700 μm or more ２ More preferably, it is less than 0.100 μm ２ 0.500 μm or more ２ When the cross-sectional area per first phase is in an appropriate range, the adhesive strength is improved, and an electronic material with high durability can be provided.

[0016] The adhesive composition for electronic materials preferably has a melt viscosity at 130°C of 10,000 mPa·s or more and less than 150,000 mPa·s. A melt viscosity within this appropriate range allows the adhesive composition to adequately conform to even minute irregularities on the adherend, contributing to improved adhesion of the cured sheet. This improves the durability of the electronic material.

[0017] The glass transition point of the sheet-shaped cured product is preferably lower than 0° C. A low glass transition point after thermal curing allows for a flexible cured product to be obtained, making it possible to provide an electronic material with high durability.

[0018] The adhesive composition for electronic materials preferably contains a thermosetting resin and an elastomer. By curing a composition containing two or more components, a phase-separated state in which a first phase is dispersed in a second phase is obtained.

[0019] The thermosetting resin is not particularly limited, but preferably contains at least one of epoxy resin, phenol resin, and maleimide resin, and more preferably contains maleimide resin. By containing maleimide resin, it is possible to achieve low dielectric constant while maintaining the adhesiveness of the sheet-shaped cured product, thereby improving the electrical properties of the electronic material. Epoxy resin is a thermosetting resin made of a compound having an epoxy group in its molecule. Phenol resin is a thermosetting resin made of a compound having a phenolic hydroxyl group and a compound having an aldehyde group. Maleimide resin is a thermosetting resin made of a compound having a maleimide group in its molecule. These thermosetting resins are suitable as base resins for adhesive compositions.

[0020] The adhesive composition for electronic materials preferably contains a thermoplastic elastomer. Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers. From the viewpoint of achieving both adhesiveness and durability, it is more preferable for the adhesive composition for electronic materials to contain a styrene-based thermoplastic elastomer or an ester-based thermoplastic elastomer, which improves the durability of the electronic material.

[0021] The thermosetting resin preferably contains an aromatic polyether compound having a reactive functional group. Examples of the aromatic polyether compound include polyphenylene ether resins. The polyphenylene ether resins may be oligomers such as oligophenylene ether. Examples of the reactive functional groups possessed by the polyphenylene ether resins include terminal vinyl groups such as styrene groups and allyl groups, and epoxy groups. From the viewpoint of low dielectric properties, terminal vinyl groups such as styrene groups and allyl groups are more preferred, which improves the electrical properties of the electronic material.

[0022] From the viewpoint of obtaining an adhesive composition with low dielectric constant and excellent adhesion and flexibility, it is preferable to contain a styrene-based thermoplastic elastomer and a phenylene ether resin having a terminal vinyl group. The styrene-based thermoplastic elastomer may be used alone or in combination with two or more types. The use of polyphenylene ether in combination with the styrene-based thermoplastic elastomer contributes to improving the thermosetting properties, heat resistance, and low dielectric properties of the adhesive composition.

[0023] Specific examples of styrene-based thermoplastic elastomers include at least one selected from styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-ethylene-propylene-styrene (SEPS) copolymer, styrene-butylene-styrene (SBS) copolymer, and styrene-isoprene-styrene (SIS) copolymer. The styrene-based elastomer mainly contributes to the low dielectric properties, heat resistance, improved adhesiveness of the adhesive composition, and improved flexibility of the cured sheet.

[0024] As the styrene-based thermoplastic elastomer, it is preferable to use an SEBS copolymer or an SEPS copolymer from the viewpoint of the low dielectric properties and heat resistance of the adhesive composition, and further, the combined use of two or more of these styrene-based thermoplastic elastomers contributes to improving the adhesive properties of the adhesive composition, thereby improving the electrical properties and durability of the electronic material.

[0025] The weight-average molecular weight (Mw) of the styrene-based thermoplastic elastomer is preferably 20,000 or more but less than 500,000, more preferably 50,000 or more but less than 300,000, and even more preferably 50,000 or more but less than 250,000. Adjusting the melt viscosity of the adhesive composition allows it to adequately conform to even the small irregularities of the adherend, contributing to improved adhesiveness of the sheet after curing. This improves the durability of the electronic material.

[0026] The maleimide resin is preferably a maleimide compound having two or more maleimide groups in the molecule, and may be a bismaleimide (BMI) compound having two maleimide groups in the molecule. Increasing the crosslink density of the resin can improve the heat resistance of the sheet after curing. Furthermore, the bismaleimide compound has high molecular symmetry, which contributes to a decrease in the dielectric constant of the sheet after curing. This improves the electrical properties of the electronic material.

[0027] Specific examples of epoxy resins include bisphenol-type epoxy resins, glycidyl ethers of polyhydric alcohol compounds or polyhydric phenol compounds, glycidyl esters of polycarboxylic acid compounds, glycidylamine-type epoxy resins, epoxidized polybutadiene, epoxidized soybean oil, novolac-type epoxy resins, alicyclic epoxy resins, polycyclic aromatic epoxy resins, brominated epoxy resins, and phosphorus-containing epoxy resins.

[0028] The adhesive composition for electronic materials preferably contains an epoxy resin in an amount of 1.0 mass % or more and less than 10.0 mass % relative to the total mass of the adhesive composition for electronic materials. The epoxy resin contained in an appropriate proportion can contribute to adhesiveness by adjusting the phase separation state and curability.

[0029] The adhesive composition for electronic materials preferably contains an epoxy resin having a number average molecular weight (Mn) of 400 or more and less than 3000. When the epoxy resin has an appropriate Mn, it can contribute to adhesiveness by adjusting the phase separation state and curability.

[0030] The weight average molecular weight (Mw) of the styrene-based thermoplastic elastomer and the number average molecular weight (Mn) of the epoxy resin can be measured using a gel permeation chromatography measurement device and converted into standard polystyrene.

[0031] The adhesive composition for electronic materials may contain a curing accelerator, such as a peroxide compound, an amine compound, an acid anhydride compound, an imidazole compound, or an organic phosphorus compound.

[0032] The content of the thermoplastic elastomer relative to the total mass of the adhesive composition for electronic materials is not particularly limited, but may be from 70% by mass to 90% by mass, which allows the sheet after curing to have both flexibility and durability, and also allows the adhesiveness to be improved by adjusting the phase separation state.

[0033] The content of the polyphenylene ether resin relative to the total mass of the adhesive composition for electronic materials is not particularly limited, but may be from 5% by mass to 20% by mass, which allows both the curability of the adhesive composition and the flexibility of the sheet after curing to be achieved.

[0034] The content of the maleimide resin relative to the total mass of the adhesive composition for electronic materials is not particularly limited, but may be from 1 mass % to 10 mass %, which allows both the curability of the adhesive composition and the durability of the sheet after curing to be achieved.

[0035] 1 is a cross-sectional view showing an example of a laminate 20 having protective materials 21 and 22 on an upper surface 11 and a lower surface 12, respectively, of an adhesive sheet 10. The adhesive sheet 10 is made of the adhesive composition for electronic materials 13 described above.

[0036] Examples of the protective materials 21 and 22 include layers containing polyethylene terephthalate (PET) or cellulose. More specifically, examples include polyester-based films such as PET resin films and cellulose-based resin films such as cellulose acetate. The protective materials 21 and 22 may also be release sheets or films. Specific examples include those in which a silicone release agent is coated on the surface of a PET resin film or polyethylene-laminated paper.

[0037] The thickness of the protective materials 21, 22 is not particularly limited, but is preferably 10 μm or more and less than 250 μm, more preferably 20 μm or more and less than 150 μm, even more preferably 25 μm or more and less than 100 μm, and particularly preferably 30 μm or more and less than 80 μm. The release sheet or release film is peeled and removed before the adhesive sheet 10 is heat-cured.

[0038] The thickness of the protective material 21 on the upper surface 11 of the adhesive sheet 10 and the thickness of the protective material 22 on the lower surface 12 may be the same, but it is preferable that the thicknesses of the protective materials 21 and 22 are different. By making the thicknesses of the protective materials 21 and 22 different, the adhesiveness of the adhesive sheet 10 to the adherend is improved and poor adhesion during processing can be suppressed, thereby improving the electrical properties and durability of the electronic material.

[0039] The adhesive composition before curing may be in an uncured state such as A-stage or a semi-cured state such as B-stage, and the sheet-shaped cured product after curing may be in a cured state such as C-stage.

[0040] The method for producing a sheet-like cured product from the adhesive sheet 10 is not particularly limited, and examples thereof include the following methods (1) and (2): (1) A method in which adhesive sheet 10 formed to a thickness of 25 μm is placed in a high-temperature incubator (STPH-102, manufactured by Espec Corporation) set at 30° C., the temperature is increased to 180° C. at a rate of 5° C. / min, the sheet is left to stand at 180° C. for 1 hour, and then the temperature is decreased to 30° C. at a rate of 5° C. / min to produce a sheet-like cured product. (2) Instead of using adhesive sheet 10 formed to a thickness of 25 μm, a sheet-like cured product is produced from an adhesive sheet formed to an arbitrary thickness greater than 25 μm in the same manner as in (1), and then the sheet is polished to a thickness of 25 μm to produce a sheet-like cured product.

[0041] The adhesive composition of the embodiment may be formed into a sheet by coating, drying, or the like from a liquid adhesive in which each component is dissolved or dispersed in a solvent. Examples of the solvent include, but are not limited to, hydrocarbon solvents such as toluene, glycol solvents, ether solvents such as tetrahydrofuran, ketone solvents such as acetone, ester solvents such as ethyl acetate, amide solvents such as dimethylformamide, sulfur-based solvents such as dimethyl sulfoxide, and chlorine-based solvents such as dichloromethane. The solvent may be a single solvent or a mixed solvent of two or more solvents.

[0042] Examples of electronic materials to which the adhesive composition of the embodiment can be applied include printed wiring boards and flexible wiring boards, and these electronic materials are particularly suitable for use in high-speed communication. The adhesive composition may be an adhesive composition for high-speed communication or a low-dielectric adhesive composition.

[0043] The present invention has been described above based on preferred embodiments, but the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention.

[0044] The present invention will be specifically described below with reference to examples.

[0045] Each component shown in Table 1 was dissolved in tetrahydrofuran to obtain a liquid adhesive. The liquid adhesive was applied to a release film so that the adhesive sheet would have a thickness of 25 μm after application and drying, and then dried for 2 minutes in a high-temperature incubator (STPH-102, manufactured by Espec Corporation) set to 130°C to obtain a laminate including an adhesive sheet. The laminate has a structure in which the adhesive sheet is laminated between an upper release film and a lower release film. Note that a 50 μm thick release film (SP2000CR, manufactured by Toyo Cross Co., Ltd.) was used for the upper release film, and a 38 μm thick release film (SPV022TGK, manufactured by Toyo Cross Co., Ltd.) was used for the lower release film.

[0046] SEBS-1 is a styrene-ethylene-butylene-styrene copolymer (trade name Tuftec (registered trademark) H1041) with a styrene content (St) of 30% by mass and a weight average molecular weight (Mw) of 100,000. SEBS-2 is a styrene-ethylene-butylene-styrene copolymer (trade name Tuftec (registered trademark) H1272) with a St of 35% by mass and a Mw of 140,000. SEBS-3 is a styrene-ethylene-butylene-styrene copolymer (trade name Tuftec (registered trademark) P1500) with a St of 30% by mass and a Mw of 100,000. SEPS-1 is a styrene-ethylene-propylene-styrene copolymer (trade name Septon (registered trademark) 2063) with a St of 13% by mass and a Mw of 180,000. SEPS-2 is a styrene-ethylene-propylene-styrene copolymer with St 30% by mass and Mw 100,000 (trade name Septon (registered trademark) 4033). The acrylic copolymer is Teisan Resin (registered trademark) SG-P3.

[0047] PPE-1 is a polyphenylene ether resin with the trade name OPE-2st-1200. BMI-1 is a bismaleimide resin with the trade name BMI-5100. BMI-2 is a bismaleimide resin with the trade name BMI-4000. Epoxy resin-1 is a reaction product (Mn 840) obtained by adding 10 g of epoxy resin with the trade name HP4032D (Mn 280) and 1.6 g of 1,3-bis(4-aminophenoxy)benzene, heating and mixing them at 120°C, and then heating and reacting them for 24 hours in a high-temperature incubator set at 60°C. Epoxy resin-2 is an epoxy resin with the trade name JER (registered trademark) 1004F (Mn 1500). Epoxy resin-3 is an epoxy resin with the trade name JER (registered trademark) 1007 (Mn 2900). The imidazole compound is the trade name C11Z-A. The peroxide compound has the trade name Perbutyl® P.

[0048]

[0049] (Total Light Transmittance and Haze) The total light transmittance and haze of the sheet-shaped cured product after heat curing were measured using a haze meter (NDH8000, manufactured by Nippon Denshoku Industries Co., Ltd.). The heat curing conditions were as follows: The adhesive sheet was placed in a high-temperature incubator (STPH-102, manufactured by Espec Corporation) set to 30°C, heated to 180°C at a heating rate of 5°C / min, and then left to stand at 180°C for 1 hour. Thereafter, the temperature was lowered to 30°C at a cooling rate of 5°C / min.

[0050] (130°C Melt Viscosity) The 130°C melt viscosity was calculated from the value obtained by laminating an adhesive sheet to a thickness of 1 mm and measuring the viscosity under specified measurement conditions (frequency 1 Hz, temperature rise rate 10°C / min) using a rheometer (manufactured by TA Instruments, product name "AR-G2").

[0051] (Cross-section observation) Cross-sections of the sheet-shaped cured product after heat curing were observed using a field emission scanning electron microscope (FE-SEM), and the following values ​​were calculated. "Area ratio of the first phase" represents the ratio of the area occupied by the first phase to the cross-sectional area of ​​the sheet-shaped cured product, and "average cross-sectional area per first phase" represents the average cross-sectional area per first phase in the cross section of the sheet-shaped cured product in the direction perpendicular to the surface of the sheet-shaped cured product.

[0052] (Glass Transition Temperature (Tg)) The glass transition temperature (Tg) was determined by laminating an adhesive sheet to a thickness of 100 μm, then heat-curing the resulting sample, and measuring the resulting sample using a DMA device (manufactured by Hitachi High-Technologies Corporation, product name "DMA6100") under specified measurement conditions (frequency 1 Hz, temperature rise rate 3° C. / min), and using the peak temperature of tan δ.

[0053] (Adhesion Strength to Liquid Crystal Polymer (LCP) Film) The adhesive strength to a liquid crystal polymer (LCP) film was measured by laminating the upper surface of the adhesive sheet to an LCP film (Panasonic: RF705S) at a temperature of 130°C, a pressure of 0.5 MPa, and a speed of 0.3 m / min. After heat curing, a peel test was performed using a universal testing machine (A&D Co., Ltd., Tensilon (registered trademark) universal testing machine) at a peel angle of 90° and a peel speed of 50 mm / min, and the obtained value was taken as the adhesive strength.

[0054] (Dielectric Constant and Dielectric Loss Tangent) The dielectric constant and dielectric loss tangent were measured at a frequency of 10 GHz by a cavity resonance method.

[0055] (Unevenness Tracking Ability) The unevenness tracking ability was evaluated as follows. First, a copper-clad laminate was prepared by laminating a 12 μm thick copper foil on an LCP film (manufactured by Panasonic: RF705S), and a wiring pattern of L / S = 0.2 mm / 0.2 mm was formed. The upper surface of the adhesive sheet was attached to the wiring pattern surface of the prepared copper-clad laminate under conditions of a temperature of 130 ° C, a pressure of 0.5 MPa, and a speed of 0.3 m / min to prepare a sample. Then, this sample was sandwiched between polytetrafluoroethylene sheets (thickness 100 μm) from above and below, and pressed in the vertical thickness direction for 2 minutes under conditions of a temperature of 160 ° C, a pressure of 0.5 MPa. This sample was cut along the thickness direction, and the obtained cross section was observed with a microscope (manufactured by Keyence Corporation, VHX-5000) to evaluate the unevenness tracking ability.

[0056]

[0057] Based on the measurement results shown in Table 2, the evaluation was divided into categories as shown in Table 3 below.

[0058]

[0059] The haze in Table 3 is categorized as follows based on the haze value after heat curing: A: 20% or more and less than 80% B: 15% or more and less than 20% C: 10% or more and less than 15% D: Less than 10%

[0060] The cross-sectional observations (area ratio of the first phase) in Table 3 were classified as follows: A: 0.70% or more and less than 50.0% B: 0.50% or more and less than 0.70% C: 0.30% or more and less than 0.50% D: Less than 0.30%

[0061] The cross-sectional observations in Table 3 (average cross-sectional area per first phase) were classified as follows: A: 0.003 μm ２ 1.000 μm or more ２ Less than B: 1.000 μm ２ or more C: 0.003μm ２ less than

[0062] The glass transition temperatures (Tg) in Table 3 are classified as follows: A: less than 0°C B: 0°C or higher

[0063] The adhesive strength (to LCP film) in Table 3 was classified as follows: A: 12 N / 10 mm or more B: 10 N / 10 mm or more and less than 12 N / 10 mm C: 8 N / 10 mm or more and less than 10 N / 10 mm D: Less than 8 N / 10 mm

[0064] The melt viscosity (130°C) in Table 3 is classified as follows: A: 50,000 mPa·s or more and less than 70,000 mPa·s B: 30,000 mPa·s or more and less than 50,000 mPa·s or 70,000 mPa·s or more and less than 90,000 mPa·s C: 10,000 mPa·s or more and less than 30,000 mPa·s or 90,000 mPa·s or more and less than 150,000 mPa·s D: Less than 10,000 mPa·s or 150,000 mPa·s or more

[0065] The dielectric constants (23°C) in Table 3 were classified as follows: A: less than 2.5 B: 2.5 or more and less than 2.8 C: 2.8 or more and less than 3.0 D: 3.0 or more

[0066] The dielectric loss tangent (23°C) in Table 3 was classified as follows: A: Less than 0.0023 B: 0.0023 or more and less than 0.0026 C: 0.0026 or more and less than 0.0030 D: 0.0030 or more

[0067] The conformability to unevenness in Table 3 was classified as follows: A: The adhesive sheet was filled in the stepped portion, and there were no voids. B: The adhesive sheet was filled in the recessed portion by 0.1 mm. ２ C: A void of less than 0.1 mm is observed in the recess. ２ The above voids are observed.

[0068] 10... adhesive sheet, 11... upper surface of adhesive sheet, 12... lower surface of adhesive sheet, 13... adhesive composition for electronic materials, 20... laminate, 21... upper surface protective material, 22... lower surface protective material.

[0069] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible within the scope of the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the appended claims.

Claims

1. An adhesive composition for electronic materials comprising a thermosetting resin, wherein a sheet-shaped cured product formed from the adhesive composition for electronic materials exists in a phase-separated state in which a first phase is dispersed in a second phase.

2. An adhesive composition for electronic materials according to claim 1, wherein in a cross section of the sheet-like cured material in a direction perpendicular to the surface of the sheet-like cured material, the ratio of the area occupied by the first phase to the cross-sectional area of ​​the sheet-like cured material is 0.2% or more and less than 50.0%.

3. The adhesive composition for electronic materials according to claim 1, wherein the haze value of the sheet-like cured product at a thickness of 25 μm is 10% or more and less than 80%.

4. In a cross section of the sheet-like cured material in a direction perpendicular to the surface of the sheet-like cured material, the average cross-sectional area per first phase is 0.003 μm ２ 1.000 μm or more ２ The adhesive composition for electronic materials according to claim 1 , wherein the viscosity of the adhesive composition for electronic materials is less than 1000 MPa.

5. The adhesive composition for electronic materials according to claim 1, wherein the melt viscosity of the adhesive composition for electronic materials at 130°C is 10,000 mPa·s or more and less than 150,000 mPa·s.

6. The adhesive composition for electronic materials according to claim 1, wherein the sheet-like cured product has a glass transition temperature of less than 0°C.

7. The adhesive composition for electronic materials according to claim 1, which comprises the thermosetting resin and an elastomer.

8. The adhesive composition for electronic materials according to claim 1, wherein the thermosetting resin includes at least one of an epoxy resin, a phenolic resin, and a maleimide resin.

9. The adhesive composition for electronic materials according to claim 1, wherein the adhesive composition for electronic materials contains a thermoplastic elastomer.

10. The adhesive composition for electronic materials according to claim 1, wherein the thermosetting resin contains an aromatic polyether compound having a reactive functional group.

11. The adhesive composition for electronic materials according to claim 1, wherein the adhesive composition for electronic materials contains an epoxy resin in an amount of 1.0 mass % or more and less than 10.0 mass % relative to the total mass of the adhesive composition for electronic materials.

12. The adhesive composition for electronic materials according to claim 1, which contains an epoxy resin having a number average molecular weight Mn of 400 or more and less than 3,000.

13. An adhesive sheet comprising the adhesive composition for electronic materials according to any one of claims 1 to 12.

14. A laminate comprising the adhesive sheet of claim 13 and protective materials on the upper and lower surfaces of said adhesive sheet, wherein the thickness of the protective material on the upper surface is different from the thickness of the protective material on the lower surface.

15. The laminate of claim 14, wherein the protective material comprises polyethylene terephthalate (PET) or cellulose.

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