Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
  • C08L71/08—Polyethers derived from hydroxy compounds or from their metallic derivatives
  • C08L71/10—Polyethers derived from hydroxy compounds or from their metallic derivatives from phenols
  • C08L71/12—Polyphenylene oxides
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/08—Macromolecular additives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J153/00—Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
  • C09J153/02—Vinyl aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J171/00—Adhesives based on polyethers obtained by reactions forming an ether link in the main chain; Adhesives based on derivatives of such polymers
  • C09J171/08—Polyethers derived from hydroxy compounds or from their metallic derivatives
  • C09J171/10—Polyethers derived from hydroxy compounds or from their metallic derivatives from phenols
  • C09J171/12—Polyphenylene oxides
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/35—Heat-activated
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/03—Use of materials for the substrate

Definitions

• the present invention relates to a thermosetting adhesive sheet and a printed wiring board.
• Heat-curable adhesive sheets with low dielectric constants and dielectric tangents have been proposed as a constituent material for flexible printed circuit boards (FPCs) used in high-speed communications (e.g., Patent Documents 1 and 2).
• JP 2019-135280 A International Publication No. 2021/024364
• thermosetting adhesive sheets disclosed in References 1 and 2 have a strong tack, and during the positioning work to check the application position of the thermosetting adhesive sheet, the thermosetting adhesive sheet may adhere too strongly to the component, making it difficult to reapply when it is desired to correct the application position. Furthermore, the thermosetting adhesive sheets disclosed in References 1 and 2 may cause swelling and flow in the cured product of the thermosetting adhesive sheet during the solder reflow process, and may not have sufficient reflow heat resistance.
• the present invention aims to provide a thermosetting adhesive sheet that has a low dielectric constant, is easy to position, and has excellent heat resistance, and a printed wiring board that includes a cured product of the thermosetting adhesive sheet.
• thermosetting adhesive sheet having an adhesive layer made of an adhesive composition, the adhesive layer containing 75 to 90 parts by mass of a styrene-based elastomer per 100 parts by mass of the adhesive composition, the styrene-based elastomer containing at least a styrene-based elastomer (A) having a styrene ratio of 30% or more, the adhesive layer containing a polyfunctional resin having at least two or more reactive functional groups in its structure, and a cured product of the thermosetting adhesive sheet has a dielectric constant of 1.0 to 3.0 at 23°C, 50% RH, and a frequency of 28 GHz.
• thermosetting adhesive sheet according to any one of [1] to [4], wherein the polyfunctional resin is a modified polyphenylene ether resin having a polymerizable group at its end, in an amount of 5 to 20 parts by mass per 100 parts by mass of the adhesive composition.
• the polyfunctional resin is a modified polyphenylene ether resin having a polymerizable group at its end, in an amount of 5 to 20 parts by mass per 100 parts by mass of the adhesive composition.
• thermosetting adhesive sheet according to any one of [1] to [5], wherein the polyfunctional resin contains an epoxy resin in a total amount of 1 to 15 parts by mass per 100 parts by mass of the adhesive composition.
• thermosetting adhesive sheet according to any one of [1] to [6], containing 0.1 to 10 parts by mass of an organic peroxide per 100 parts by mass of the adhesive composition.
• thermosetting adhesive sheet according to any one of [1] to [7], wherein the adhesive layer has a storage modulus E' at 30° C. of 1 ⁇ 10 6 to 1 ⁇ 10 9 Pa.
• thermosetting adhesive sheet according to any one of [1] to [8], wherein the initial adhesive strength of the thermosetting adhesive sheet to polyimide is 0.5 N/mm or less.
• thermosetting adhesive sheet according to any one of [1] to [9], in which the T-peel adhesive strength after the thermosetting adhesive sheet is applied to polyimide and cured is 0.25 N/mm or more.
• thermosetting adhesive sheet according to any one of [1] to [10] above, for use in a printed wiring board.
• thermosetting adhesive sheet described in any one of [1] to [11].
• the present invention provides a thermosetting adhesive sheet that has a low dielectric constant, low tack, is easy to position, and has excellent heat resistance.
• thermosetting adhesive sheet of the present invention will be described in more detail below based on its components.
• thermosetting adhesive sheet The thermosetting adhesive sheet of the present invention has an adhesive layer made of an adhesive composition.
• the adhesive layer made of the adhesive composition of the present invention contains 75 to 90 parts by mass of a styrene-based elastomer and a polyfunctional resin having at least two reactive functional groups in its structure, relative to 100 parts by mass of the adhesive composition, and the styrene-based elastomer contains at least a styrene-based elastomer (A) having a styrene ratio of 30% or more.
• A styrene-based elastomer
• the adhesive composition of the present invention contains, relative to 100 parts by mass of the adhesive composition, 75 to 90 parts by mass of a styrene-based elastomer and a polyfunctional resin having at least two reactive functional groups in its structure.
• the styrene elastomer is a copolymer of styrene and an olefin (e.g., a conjugated diene such as butadiene or isoprene) and/or a hydrogenated product thereof.
• the styrene elastomer is a block copolymer in which styrene is a hard segment and a conjugated diene is a soft segment.
• styrene elastomer examples include styrene AB type diblock copolymers such as styrene-ethylene-butylene copolymer (SEB); styrene-butadiene-styrene copolymer (SBS), hydrogenated products of SBS (styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-butylene-styrene copolymer (SBBS)), styrene-isoprene-styrene copolymer (SIS), hydrogenated products of SIS (styrene-ethylene-propylene-styrene copolymer (SEPS)), and styrene-isobutylene-styrene copolymer (SIBS); It is preferable to use styrene-based ABAB type tetrablock copolymers such as
• the styrene-based elastomer is at least one selected from the group consisting of hydrogenated SBS, maleic anhydride modified hydrogenated SBS, and terminal amine modified hydrogenated SBS, since this leads to a thermosetting adhesive sheet with weak tack and better heat resistance, and furthermore, the thermosetting adhesive sheet exhibits good low dielectric properties.
• the weight average molecular weight of the styrene-based elastomer is preferably 50,000 or more, more preferably 80,000 to 1,000,000. Setting the weight average molecular weight of the styrene-based elastomer within the above preferred range is preferable in that the thermosetting adhesive sheet has weak tack and better heat resistance.
• the weight average molecular weight of the styrene-based elastomer refers to the weight average molecular weight of each of the two or more types of styrene-based elastomers.
• the weight average molecular weight of the styrene-based elastomer is measured by the GPC method using a GPC apparatus (HLC-8329GPC, manufactured by Tosoh Corporation) and is a value converted into standard polystyrene.
• the measurement conditions are as follows: - Measurement conditions - Sample concentration: 0.5% by mass (tetrahydrofuran (THF) solution) Sample injection volume: 100 ⁇ L Eluent: THF ⁇ Flow rate: 1.0mL/min ⁇ Measurement temperature: 40°C Main column: TSKgel GMHHR-H (20) x 2 Guard column: TSKgel HXL-H ⁇ Detector: Differential refractometer ⁇ Standard polystyrene molecular weight: 10,000 to 20 million (manufactured by Tosoh Corporation)
• the adhesive composition of the present invention contains 75 to 90 parts by mass of the styrene-based elastomer per 100 parts by mass of the adhesive composition.
• the adhesive composition contains two or more types of styrene-based elastomers as the styrene-based elastomer
• the total content of the two or more types of styrene-based elastomers is in the above-mentioned range per 100 parts by mass of the adhesive composition.
• the content of the styrene-based elastomer is more preferably 80 to 90 parts by mass per 100 parts by mass of the adhesive composition.
• thermosetting adhesive sheet has weak tack and can have better heat resistance, and further, the thermosetting adhesive sheet can exhibit good low dielectric properties, which is preferable.
• the styrene-based elastomer contains at least a styrene-based elastomer (A) having a styrene ratio of 30% or more.
• the styrene ratio of the styrene-based elastomer (A) is preferably 30% or more, more preferably 30 to 80%, and particularly preferably 30 to 70%. This configuration makes it possible to achieve a low dielectric constant, weak tack, and better heat resistance.
• the content of the styrene-based elastomer (A) is preferably 5 parts by mass or more, more preferably 7 to 90 parts by mass, and even more preferably 9 to 50 parts by mass, per 100 parts by mass of the adhesive composition. If the content of the styrene-based elastomer (A) is within the above-mentioned preferred range, it is preferable in that the tack of the thermosetting adhesive sheet is weak and the adhesiveness after curing can be improved.
• the styrene-based elastomer may contain two or more types of styrene-based elastomers with different styrene ratios.
• the styrene-based elastomer contains two or more types of styrene-based elastomers with different styrene ratios, it is preferable that the styrene-based elastomer further contains, in addition to the styrene-based elastomer (A) with a styrene ratio of 30% or more, a styrene-based elastomer (B) with a styrene ratio different from that of the styrene-based elastomer (A).
• the styrene-based elastomer (B) is used in combination, the tack of the thermosetting adhesive sheet is weak, and the adhesiveness after curing can be strengthened.
• the styrene ratio of the styrene-based elastomer (B) is preferably less than 30%, more preferably 5 to 25%, even more preferably 7 to 20%, and particularly preferably 10 to 15%. If the styrene ratio of the styrene-based elastomer (B) is within the above range, the adhesiveness of the thermosetting adhesive sheet after curing can be improved.
• the content of the styrene-based elastomer (B) is preferably 35 parts by mass or more, more preferably 40 to 80 parts by mass, and even more preferably 50 to 75 parts by mass, per 100 parts by mass of the adhesive composition.
• the content of the styrene-based elastomer (B) is within the above-mentioned preferred range, it is preferable in that the tack of the thermosetting adhesive sheet is weak and the heat resistance and adhesion after curing can be improved.
• the mass ratio [(A)/(B)] is not particularly limited, but is preferably in the range of 10/73 to 48/35, more preferably in the range of 17/65 to 48/35, and even more preferably in the range of 28/55 to 48/35.
• a mass ratio in the above range is preferable in that it can weaken the tack of the thermosetting adhesive sheet, making it easier to position the thermosetting adhesive sheet when it is applied to the adherend.
• the adhesive composition of the present invention contains a multifunctional resin having at least two or more reactive functional groups in the structure.
• the reactive functional groups are not particularly limited as long as they do not impair the effects of the present invention, and examples thereof include hydroxyl groups, halogen groups, amino groups, carboxyl groups, epoxy groups, and functional groups containing ethylenic unsaturated bonds.
• a functional group containing an amino group, a carboxyl group, an epoxy group, or an ethylenic unsaturated bond from the viewpoint of heat resistance after curing of the thermosetting adhesive sheet, it is preferable to have a functional group containing an amino group, a carboxyl group, an epoxy group, or an ethylenic unsaturated bond.
• the multifunctional resin is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include modified polyphenylene ether resins and epoxy resins.
• the multifunctional resin may contain one or more types.
• the adhesive composition of the present invention may contain an organic peroxide as a polymerization initiator for the modified polyphenylene ether resin, and may contain an epoxy resin curing agent as a curing agent for the epoxy resin.
• the content of the polyfunctional resin is preferably 1 to 20 parts by mass, more preferably 2 to 20 parts by mass, even more preferably 5 to 20 parts by mass, and particularly preferably 10 to 20 parts by mass, relative to 100 parts by mass of the adhesive composition. Adjusting the content of the polyfunctional resin within the above-mentioned preferred range is preferable in that when the thermosetting adhesive sheet cures, the polyfunctional resin reacts to form a crosslinked structure, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and improving heat resistance.
• the adhesive composition may contain, for example, one or more modified polyphenylene ether resins as a polyfunctional resin having at least two or more reactive functional groups in the structure.
• the modified polyphenylene ether resin preferably has a polyphenylene ether chain in the molecule and a polymerizable group at the end.
• the modified polyphenylene ether resin preferably has at least two or more types of functional groups containing an epoxy group and an ethylenically unsaturated bond as polymerizable groups in one molecule.
• the modified polyphenylene ether resin preferably has at least one type of functional group containing an epoxy group and an ethylenically unsaturated bond at both ends.
• the functional group containing an ethylenically unsaturated bond include a (meth)acryloyl group and a vinylbenzyl group.
• modified polyphenylene ether resins having (meth)acryloyl groups at both ends are preferred because they improve the heat resistance of the thermosetting adhesive sheet after it has been cured and can impart excellent low dielectric properties.
• the number average molecular weight of the modified polyphenylene ether resin is preferably 1000 to 10000, and more preferably 1000 to 3000. Setting the number average molecular weight of the modified polyphenylene ether resin within the above-mentioned preferred range is preferable in that it improves the heat resistance and adhesion of the thermosetting adhesive sheet after curing, and also imparts excellent low dielectric properties.
• the number average molecular weight of the modified polyphenylene ether resin was measured using gel permeation chromatography (GPC) in terms of standard polystyrene. The measurement conditions were the same as those for the weight average molecular weight described above.
• the content of the modified polyphenylene ether resin is preferably 5 to 20 parts by mass, and particularly preferably 9 to 15 parts by mass, per 100 parts by mass of the adhesive composition. Setting the content of the modified polyphenylene ether resin within the above-mentioned preferred range is preferable in that it improves the heat resistance and adhesion of the thermosetting adhesive sheet after curing and can impart excellent low dielectric properties, and is particularly preferable in that when the thermosetting adhesive sheet cures, the modified polyphenylene ether resin reacts to form a crosslinked structure, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and improving heat resistance.
• the organic peroxide can be used as a polymerization initiator for the above-mentioned modified polyphenylene ether resin.
• the organic peroxide for example, dicumyl peroxide, di-tert-butyl peroxide, 2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlor
• dicumyl peroxide is preferred because it can improve the heat resistance and adhesiveness of the thermosetting adhesive sheet after it has hardened.
• the content of the organic peroxide is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, even more preferably 1 to 5 parts by mass, and particularly preferably 1.5 to 3 parts by mass, relative to 100 parts by mass of the adhesive composition.
• Setting the content of the organic peroxide within the above-mentioned preferred range is preferable in that it can improve the heat resistance and adhesion of the thermosetting adhesive sheet after curing, and is particularly preferable in that when the thermosetting adhesive sheet cures, the organic peroxide reacts to form a crosslinked structure, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and improving heat resistance.
• the adhesive composition may contain, for example, an epoxy resin as a polyfunctional resin having at least two or more reactive functional groups in the structure.
• an epoxy resin a compound having two or more epoxy groups in one molecule may be used.
• bisphenol type epoxy resins such as bisphenol A type epoxy resins and bisphenol F type epoxy resins and modified resins thereof, dicyclopentadiene type epoxy resins such as dicyclopentadiene-phenol addition reaction type epoxy resins, biphenyl type epoxy resins, tetramethylbiphenyl type epoxy resins, polyhydroxynaphthalene type epoxy resins, isocyanate modified epoxy resins, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, triphenylmethane ...methylmethane type epoxy resins, tetramethylbipheny
• dicyclopentadiene type epoxy resins such as dicyclopentadiene-phenol addition reaction type epoxy resins, biphenyl type epoxy resins, tetramethylbiphenyl type epoxy resins, and polyhydroxynaphthalene type epoxy resins, since these can improve the heat resistance and adhesiveness of the thermosetting adhesive sheet after it has been cured.
• the content of the epoxy resin is preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the adhesive composition.
• the content of the epoxy resin is within the above-mentioned preferred range, it is preferable in that the heat resistance of the thermosetting adhesive sheet after curing can be improved and excellent low dielectric properties can be imparted, and in particular, when the thermosetting adhesive sheet is cured, the epoxy resin reacts to form a crosslinked structure, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and improving heat resistance.
• the epoxy resin curing agent can be used as a catalyst to promote the curing reaction of the above-mentioned epoxy resin.
• the epoxy resin curing agent for example, an imidazole-based, phenol-based, amine-based, acid anhydride-based, organic peroxide-based, etc. can be used.
• the epoxy resin curing agent is preferably a latent curing agent from the viewpoint of the storage property of the adhesive composition at room temperature, and more preferably an encapsulated imidazole-based curing agent with latent property. By improving the storage property at room temperature, it is possible to more easily manage the supply and use of the adhesive composition.
• the epoxy resin curing agent a microcapsule-type latent curing agent formed by using a latent imidazole modified body as a core and coating the surface with polyurethane can be used.
• the epoxy resin curing agent may be used alone or in combination of two or more kinds.
• the content of the epoxy resin curing agent is preferably 1 to 10 parts by mass, more preferably 1 to 7 parts by mass, even more preferably 2 to 5 parts by mass, and particularly preferably 2 to 3 parts by mass, relative to 100 parts by mass of the adhesive composition.
• the content of the epoxy resin curing agent is within the above-mentioned preferred range, it is preferable in that it can improve the good curing property of the thermosetting adhesive sheet when heated and the heat resistance after curing, and in particular, it is preferable in that when the thermosetting adhesive sheet cures, the epoxy resin curing agent reacts to form a crosslinked structure, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and improving the heat resistance.
• the adhesive composition of the present invention may further contain other components within a range that does not impair the effects of the present invention.
• other components include tackifier resins; crosslinking agents, antiaging agents, ultraviolet absorbers, polymerization inhibitors, surface conditioners, antistatic agents, foaming agents, defoamers, viscosity adjusters, light resistance stabilizers, weather resistance stabilizers, heat resistance stabilizers, antioxidants, leveling agents, conductive particles, organic pigments, inorganic pigments, pigment dispersants, silica beads, organic beads, and other additives; silicon oxide, aluminum oxide, titanium oxide, zirconia, antimony pentoxide, and other fillers. These may be used alone or in combination of two or more. The contents of the other components can be appropriately selected within a range that does not impair the effects of the present invention.
• the adhesive layer in the present invention may have a single layer structure or a multi-layer structure having two or more layers.
• the thickness of the adhesive layer in the present invention is not particularly limited as long as it is within a range that does not impair the effects of the present invention, but is preferably 10 to 75 ⁇ m, more preferably 15 to 50 ⁇ m, and even more preferably 15 to 25 ⁇ m. Setting the thickness of the adhesive layer within the above-mentioned preferred range is preferable in that it allows parts containing the cured product of the thermosetting adhesive sheet, such as printed wiring boards, to be made thinner while maintaining good heat resistance and adhesiveness after curing the thermosetting adhesive sheet.
• the adhesive layer in the present invention preferably has a storage modulus E' at 30° C. of 1 ⁇ 10 6 to 1 ⁇ 10 9 Pa, more preferably 2 ⁇ 10 6 to 5 ⁇ 10 8 Pa, and even more preferably 1 ⁇ 10 7 to 5 ⁇ 10 8 Pa.
• the storage modulus E' of the adhesive layer is within the above-mentioned preferred range, the tack of the thermosetting adhesive sheet can be weakened, and the task of positioning the thermosetting adhesive sheet when bonding it to an adherend can be facilitated.
• the storage modulus E' of the adhesive layer at 30°C can be adjusted within the above-mentioned preferred range, for example, by adjusting the type, styrene ratio, and content of the styrene-based elastomer (A) and styrene-based elastomer (B) contained in the adhesive layer.
• the storage modulus E' of the adhesive layer can be measured by the following method.
• the adhesive layers of the present invention are stacked to prepare an adhesive layer having a thickness of 100 mm.
• the adhesive layer is punched out using a dumbbell cutter into the shape of a test piece type 5 of JIS K 7127 to prepare a test piece.
• a tensile viscoelasticity tester manufactured by Rheometrics, product name: RSA-II is used to measure under the following conditions.
• Load mode sine wave (load change frequency 3.5 Hz)
• Tensile strain 0.1% Heating rate: 5°C/min
• the cured product of the adhesive layer in the present invention preferably has a cure rate of 10 to 100%, more preferably 15 to 95%, and even more preferably 30 to 90% after heating the cured product of the adhesive layer at 290° C. for 10 minutes.
• the cure rate of the cured product of the adhesive layer after heating at 290° C. for 10 minutes is within the above-mentioned preferred range, the fluidity of the cured adhesive layer at high temperatures can be suppressed, and the heat resistance can be improved.
• the curing rate after heating the cured product of the adhesive layer at 290°C for 10 minutes can be adjusted to within the above-mentioned preferred range, for example, by adjusting the type and content of the multifunctional resin contained in the adhesive layer or the type and content of the organic peroxide.
• the dielectric constant (Dk) of the adhesive layer after curing is preferably 1.0 to 3.0, more preferably 1.0 to 2.8.
• the dielectric loss tangent (Df) of the adhesive layer after curing is preferably 0.01 or less, more preferably 0.0001 to 0.01, even more preferably 0.0001 to 0.005, and particularly preferably 0.0001 to 0.003.
• the dielectric constant (Dk) and dielectric tangent (Df) of the adhesive layer after curing can be adjusted to within the above-mentioned preferred ranges, for example, by adjusting the type, styrene ratio, and content of the styrene-based elastomer (A) and styrene-based elastomer (B) contained in the adhesive layer.
• the dielectric constant (Dk) and the dielectric loss tangent (Df) can be measured according to the following method.
• the adhesive layer is cut into a size of 35 mm x 50 mm, and an evaluation test piece is prepared by curing the cut piece for 1 hour at 180° C.
• the dielectric constant (Dk) and the dielectric loss tangent (Df) of this evaluation test piece are measured at a measurement temperature of 23° C. and a measurement frequency of 28 GHz using a dielectric constant measuring device (Keysight Corp., split cylinder resonator) in an environment of 50% RH.
• Keysight Corp., split cylinder resonator Keysight Corp., split cylinder resonator
• thermosetting adhesive sheet of the present invention has an adhesive layer made of the above-mentioned adhesive composition.
• the thermosetting adhesive sheet of the present invention may be one constituted by a single adhesive layer, or one constituted by a laminate of two or more adhesive layers, which may be the same or different.
• thermosetting adhesive sheet of the present invention may be a substrate-less adhesive sheet in which both sides of the adhesive layer are adhesive surfaces of the thermosetting adhesive sheet, or a substrate may be laminated to the adhesive layer.
• the thermosetting adhesive sheet of the present invention may be a single-sided adhesive sheet in which the adhesive layer is laminated to one side of the substrate, or a double-sided adhesive sheet in which the adhesive layer is laminated to both sides of the substrate.
• the substrate may be a resin film, a foam film, paper, cloth, metal foil, or a composite of these.
• resin films include polyolefin films such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymer; polyester films such as PET; vinyl chloride resin films; vinyl acetate resin films; polyimide resin films; polyamide resin films; fluororesin films; cellophane, and the like.
• PET polyethylene
• PP polypropylene
• polyester films such as PET
• vinyl chloride resin films vinyl acetate resin films
• polyimide resin films polyamide resin films
• fluororesin films cellophane, and the like.
• paper include Japanese paper, craft paper, glassine paper, wood-free paper, synthetic paper, and top-coated paper.
• cloth include woven fabrics and nonwoven fabrics made by spinning various fibrous materials alone or in combination.
• fibrous materials include cotton, staple fiber, Manila hemp, pulp, rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber, and polyolefin fiber.
• rubber sheets include natural rubber sheets and butyl rubber sheets.
• foam sheets include foamed polyurethane sheets and foamed polychloroprene rubber sheets.
• metal foils include aluminum foil and copper foil.
• thermosetting adhesive sheet of the present invention is not particularly limited in shape or size, and includes, for example, an adhesive sheet having a shape and size suitable for attachment to a specific adherend (e.g., an adhesive sheet in a state after punching processing), and a long sheet-like adhesive sheet (e.g., an adhesive sheet before being processed into a specific shape).
• a specific adherend e.g., an adhesive sheet in a state after punching processing
• a long sheet-like adhesive sheet e.g., an adhesive sheet before being processed into a specific shape
• the thickness of the thermosetting adhesive sheet of the present invention is not particularly limited as long as it is within a range that does not impair the effects of the present invention, but is preferably 10 to 150 ⁇ m, more preferably 10 to 100 ⁇ m, more preferably 10 to 75 ⁇ m, even more preferably 15 to 50 ⁇ m, and particularly preferably 15 to 25 ⁇ m. Setting the thickness of the thermosetting adhesive sheet within the above preferred range is preferable in that it allows the printed wiring board containing the cured product of the thermosetting adhesive sheet to be made thinner while maintaining good heat resistance and adhesiveness after curing of the thermosetting adhesive sheet.
• thermosetting adhesive sheet of the present invention can be firmly bonded to an adherend by being applied to the adherend and then cured. There are no particular restrictions on the curing conditions for the thermosetting adhesive sheet of the present invention, and they can be appropriately selected from among known methods.
• the curing conditions can be set appropriately depending on the type of adhesive composition, etc., and the curing temperature is, for example, preferably 100 to 220°C, more preferably 120 to 200°C, and even more preferably 150 to 180°C.
• the curing time is, for example, preferably 1 to 180 minutes, more preferably 15 to 120 minutes, and even more preferably 30 to 60 minutes. Setting the curing conditions in the above-mentioned preferred ranges is preferable in that strong adhesion to the adherend can be achieved after curing.
• the thermosetting adhesive sheet of the present invention preferably has a dielectric constant (Dk) after curing of 1.0 to 3.0, more preferably 1.0 to 2.8.
• Dk dielectric constant
• the thermosetting adhesive sheet after curing exhibits good low dielectric properties, and can exhibit good transmission characteristics when used in components for high frequency applications.
• the dielectric constant (Dk) of the thermosetting adhesive sheet after curing can be adjusted to within the above-mentioned preferred range, for example, by adjusting the type, styrene ratio, and content of the styrene-based elastomer (A) and styrene-based elastomer (B) contained in the adhesive layer.
• the thermosetting adhesive sheet of the present invention preferably has a dielectric loss tangent (Df) of 0.01 or less after curing, more preferably 0.0001 to 0.01, even more preferably 0.0001 to 0.005, and particularly preferably 0.0001 to 0.003.
• Df dielectric loss tangent
• the dielectric loss tangent (Df) of the thermosetting adhesive sheet after curing can be adjusted to within the above-mentioned preferred range, for example, by adjusting the type, styrene ratio, and content of the styrene-based elastomer (A) and styrene-based elastomer (B) contained in the adhesive layer.
• the dielectric constant (Dk) and the dielectric loss tangent (Df) can be measured according to the following method.
• the thermosetting adhesive sheet is cut into a size of 35 mm x 50 mm to prepare a test piece.
• the test piece is cured at 180°C for 1 hour to prepare an evaluation test piece.
• a dielectric constant measuring device Keysight, split cylinder resonator
• the dielectric constant (Dk) and the dielectric loss tangent (Df) are measured at a measurement frequency of 28 GHz under an environment of a measurement temperature of 23°C and 50% RH.
• thermosetting adhesive sheet of the present invention preferably has an initial adhesive strength to polyimide of 0.5 N/mm or less, more preferably 0.46 N/mm or less, even more preferably 0.1 N/mm or less, and particularly preferably 0.05 N/mm or less.
• the initial adhesive strength of the thermosetting adhesive sheet to the polyimide is within the above-mentioned preferred range, the tack is weak, making it easier to position the thermosetting adhesive sheet when it is applied to the adherend.
• the initial adhesive strength refers to the 90° peel adhesive strength of a thermosetting adhesive sheet before curing to polyimide, and can be measured according to the method described below. Both sides of the thermosetting adhesive sheet are bonded to a polyimide film (Toray DuPont, Kapton 100H, thickness 0.025 mm) under an environment of 23 ° C. and 50% RH to prepare a test piece. The test piece is cut into a size of 20 mm x 70 mm, pressed with a 2 kg roller once, and aged for 1 hour under an environment of 23 ° C. and 50% RH. The polyimide film on one side of the test piece is fixed to a SUS plate (30 mm x 130 mm).
• a polyimide film Toray DuPont, Kapton 100H, thickness 0.025 mm
• the end of the polyimide film of the test piece that is not fixed to the SUS plate is chucked using a tensile tester (A & D Co., Ltd. RTH-1310), and a tensile test is performed in the 90 degree direction at a test speed of 50 mm / min using the tensile tester.
• the value obtained at this time can be the initial adhesive strength of the thermosetting adhesive sheet.
• the thermosetting adhesive sheet of the present invention preferably has a T-peel adhesive strength of 0.25 N/mm or more after the thermosetting adhesive sheet of the present invention is applied to a polyimide and cured, and more preferably 0.25 to 4.00 N/mm, more preferably 0.35 to 4.00 N/mm, and even more preferably 0.50 to 4.00 N/mm.
• T-peel adhesive strength of the thermosetting adhesive sheet to the polyimide after curing is set within the above-mentioned preferred range, the adhesion between the cured thermosetting adhesive sheet and the adherend is good, and when used in components for high frequency applications, excellent adhesive performance can be achieved while exhibiting good transmission characteristics.
• the T-peel adhesive strength of the cured thermosetting adhesive sheet to the polyimide can be measured according to the method described below. Both sides of the thermosetting adhesive sheet are bonded to a polyimide film (Toray DuPont, Kapton 100H, thickness 0.025 mm) under an environment of 23 ° C. and 50% RH to prepare a test piece. The test piece is heated at 180 ° C. and pressurized at 4.0 MPa for 10 minutes using a heat press machine. The test piece is then cured by heating in a 180 ° C. dryer for 50 minutes to prepare an evaluation test piece.
• a polyimide film Toray DuPont, Kapton 100H, thickness 0.025 mm
• the evaluation test piece is cut to a size of 10 mm x 100 mm, and the ends of the polyimide film bonded to both sides of the evaluation test piece are chucked using a tensile tester (A & D Co., Ltd. RTH-1310), and a tensile test is performed in the T-shaped direction at a test speed of 300 mm / min using the tensile tester.
• the value obtained at this time can be the T-shaped peel adhesive strength after curing of the thermosetting adhesive sheet.
• thermosetting adhesive sheet In another embodiment of the thermosetting adhesive sheet of the present invention, the adhesive layer has a storage modulus E' at 30°C of 1 x 10 to 1 x 10 Pa, the initial adhesive strength of the thermosetting adhesive sheet to polyimide is 0.5 N/mm or less, and the cured product of the thermosetting adhesive sheet has a dielectric constant of 1.0 to 3.0 at 23°C, 50% RH, and a frequency of 28 GHz.
• the adhesive layer containing 75 to 90 parts by mass of styrene-based elastomer per 100 parts by mass of the adhesive composition may be referred to as an adhesive layer whose main component is a styrene-based elastomer.
• thermosetting adhesive sheet of this embodiment can be easily positioned when applied to an adherend, can be reapplied, and can be firmly bonded to the adherend by curing after application.
• thermosetting adhesive sheet of this embodiment has a low dielectric constant and can exhibit good transmission characteristics when used in components for high-frequency applications, and has excellent heat resistance, which can prevent defects such as swelling caused by exposure to high temperatures during the manufacturing process for the components, such as the reflow process.
• the storage modulus E' of the adhesive layer at 30°C can be set to the same preferred range as the storage modulus E' at 30°C of the adhesive layer whose main component is a styrene-based elastomer as already described.
• the adhesive composition constituting the adhesive layer in this embodiment is not particularly limited as long as it has a composition capable of exhibiting the desired physical properties, and is not limited to adhesive compositions whose main component is the above-mentioned styrene-based elastomer, and examples thereof include epoxy resins, olefin resins, polyester resins, etc.
• the initial adhesive strength of the thermosetting adhesive sheet of this embodiment to polyimide can be set to the same preferred range as the initial adhesive strength of the thermosetting adhesive sheet having an adhesive layer mainly composed of a styrene-based elastomer as already described.
• the dielectric constant of the cured product of the thermosetting adhesive sheet of this embodiment at 23°C, 50% RH, and a frequency of 28 GHz can be the same as the preferred range of the dielectric constant of the cured product of the thermosetting adhesive sheet having an adhesive layer mainly composed of a styrene-based elastomer as already described, at 23°C, 50% RH, and a frequency of 28 GHz.
• thermosetting adhesive sheet having an adhesive layer mainly composed of a styrene-based elastomer already described in this specification can also be applied to the thermosetting adhesive sheet of this embodiment.
• thermosetting adhesive sheet The method for producing the thermosetting adhesive sheet of the present invention is not particularly limited, and can be appropriately selected from among known methods.
• thermosetting adhesive sheet of the present invention can be produced, for example, by forming an adhesive layer made of the above-mentioned adhesive composition in a sheet shape on a release liner.
• the sheet-shaped adhesive layer can be produced, for example, by diluting the above-mentioned adhesive composition with a solvent, applying it to the surface of a release liner, and drying it.
• the thickness and physical properties of the thermosetting adhesive sheet described above do not include the thickness and physical properties of the release liner.
• the release liner is not particularly limited and can be appropriately selected depending on the purpose.
• Examples include paper such as kraft paper, glassine paper, and wood-free paper; resin films such as polyethylene, polypropylene (biaxially oriented polypropylene (OPP), uniaxially oriented polypropylene (CPP)), and polyethylene terephthalate (PET); laminated paper in which the above-mentioned paper and resin film are laminated together, and the above-mentioned paper that has been treated with clay, polyvinyl alcohol, or the like to be sealed; and those in which one or both sides have been treated with a release agent such as a silicone-based resin. These may be used alone or in combination of two or more types.
• thermosetting adhesive sheet of the present invention has a weak tack before curing, so that positioning is easy when attaching the thermosetting adhesive sheet to an adherend in the manufacturing process, and the cured product of the thermosetting adhesive sheet has a low dielectric constant and dielectric tangent and is excellent in heat resistance when exposed to very high temperatures, so that it can be used, for example, as an interlayer adhesive for printed wiring boards, or for bonding and fixing terminal parts of printed wiring boards to connecting substrates for backing them.
• the thermosetting adhesive sheet of the present invention can also be used for parts for high-frequency applications such as flexible flat cables and various high-speed communication compatible modules.
• the printed wiring board of the present invention can be produced by using the cured product of the thermosetting adhesive sheet.
• the printed wiring board may be a printed circuit board in which circuits are connected by circuit components such as printed parts and mounted components, or a printed wiring board having wiring before the circuit components are formed.
• the printed wiring board of the present invention may be a rigid printed wiring board having a hard insulating substrate, or a flexible printed wiring board having a flexible insulating substrate. Furthermore, it may be a flex-rigid printed wiring board in which the insulating substrate has a hard portion and a flexible portion.
• ⁇ Component B Modified polyphenylene ether resin>
• B-1 Modified polyphenylene ether resin having methacryloyl groups at both ends (NORYL SA9000, number average molecular weight 2300, glass transition temperature 160°C, manufactured by SABIC)
• ⁇ Component C Epoxy resin>
• C-1 Naphthalene type epoxy resin (HP4032D, epoxy equivalent 136 to 148 g/eq, liquid or crystalline, manufactured by DIC Corporation)
• thermosetting adhesive sheet The obtained adhesive composition was applied to a release liner so that the thickness after drying was 25 ⁇ m. Then, the adhesive composition was dried for 2 minutes in a dryer at 85° C. to obtain an adhesive layer having a thickness of 25 ⁇ m. Next, a release liner was laminated on the surface on which the adhesive layer was exposed to produce a thermosetting adhesive sheet.
• thermosetting adhesive sheet prepared using the above method were measured and evaluated according to the following methods. Unless otherwise specified, measurements using thermosetting adhesive sheets were performed after peeling off the laminated release liner.
• thermosetting adhesive sheets prepared in the examples and comparative examples were cut to a size of 35 mm x 50 mm and cured at 180 ° C for 1 hour to prepare evaluation test pieces.
• the dielectric constant (Dk) of the evaluation test pieces was measured at a measurement temperature of 23 ° C and a measurement frequency of 28 GHz using a dielectric constant measuring device (Keysight, split cylinder resonator) under an environment of 50% RH. The results are shown in Table 1.
• ⁇ Storage modulus E'> The adhesive layers prepared in the examples and comparative examples were stacked together to prepare an adhesive layer having a thickness of 100 mm. Next, the adhesive layer was punched out using a dumbbell cutter into the shape of a type 5 test piece of JIS K 7127 to prepare a test piece. The storage modulus E' of the obtained test piece was measured under the following conditions using a tensile viscoelasticity tester (manufactured by Rheometrics, product name: RSA-II). The results are shown in Table 1. Load mode: sine wave (load change frequency 3.5 Hz) Tensile strain: 0.1% Heating rate: 5°C/min
• thermosetting adhesive sheet prepared in the examples and comparative examples were attached to a polyimide film (Kapton 100H, manufactured by DuPont-Toray Co., Ltd.) in an environment of 23°C and 50% RH to prepare a test piece.
• the test piece was cut into a size of 20 mm x 70 mm, pressed once back and forth with a 2 kg roller, and aged for 1 hour in an environment of 23°C and 50% RH to prepare an evaluation test piece.
• the polyimide film on one side of the evaluation test piece was fixed to a SUS plate (30 mm x 130 mm).
• the end of the polyimide film on the side of the evaluation test piece that was not fixed to the SUS plate was chucked using a tensile tester (RTH-1310 manufactured by A&D Co., Ltd.), and a tensile test was performed in the 90 degree direction at a test speed of 50 mm/min using the tensile tester.
• the value obtained at this time was taken as the initial adhesive strength of the thermosetting adhesive sheet.
• Table 1 The results are shown in Table 1.
• thermosetting adhesive sheet prepared in the examples and comparative examples were attached to a polyimide film (Kapton 100H, manufactured by Toray DuPont Co., Ltd.) under an environment of 23°C and 50% RH to prepare a test piece.
• the test piece was pressurized at 4.0 MPa for 10 minutes while being heated at 180°C using a heat press machine.
• the test piece was then cured by heating in a dryer at 180°C for 50 minutes to prepare a test piece for evaluation.
• the test piece was cut to a size of 10 mm x 100 mm, and the ends of the polyimide film attached to both sides of the test piece were chucked in a tensile tester (RTH-1310 manufactured by A&D Co., Ltd.), and a tensile test was performed in the T-shape direction at a test speed of 300 mm/min using the tensile tester. The value obtained at this time was taken as the T-shape peel adhesive strength of the thermosetting adhesive sheet after curing. The results are shown in Table 1.
• the curing rate of the cured product of the adhesive layer produced in the examples and comparative examples is expressed as a gel fraction, and can be measured according to the following method.
• the adhesive layers prepared in the examples and comparative examples were heated at 180° C. for 60 minutes to obtain a cured product.
• the cured product was then heated at 290° C. for 10 minutes to obtain a test piece.
• the test piece was immersed in a toluene solution adjusted to 23° C. for 24 hours, and the mass of the test piece remaining in the solvent after drying and the mass of the test piece before immersion in toluene were used to calculate the value according to the following formula.
• thermosetting adhesive sheet prepared in the examples and comparative examples was peeled off and placed on a polyimide film.
• release liner laminated on one side of the thermosetting adhesive sheet whether the thermosetting adhesive sheet could be slid against the polyimide film or peeled off again to be positioned was evaluated according to the following criteria. The results are shown in Table 1.
• ⁇ The tape did not adhere to the polyimide film and could be slid, enabling positioning to be performed.
• ⁇ The tape adhered to the polyimide film and could not be slid, but no adhesive was left behind when peeled off, allowing positioning.
• x The tape was not able to be adhered to or slid onto the polyimide film, and adhesive residue was left when the tape was peeled off, so that the tape was not suitable for positioning.
• thermosetting adhesive sheet prepared in the examples and comparative examples were attached to polyimide or copper foil, and the sheets were heated at 180°C for 60 minutes to prepare a cured product. The cured product was then heated at 260°C or 290°C for 15 minutes to prepare a test piece. The appearance of the test piece was checked and visually evaluated according to the following criteria. The results are shown in Table 1. ⁇ : No change in the appearance of the test piece ⁇ : Blisters occurred in the test piece ⁇ : Resin flow occurred in the test piece
• the pass/fail of the reflow heat resistance was judged according to the following criteria. The results are shown in Table 1. Pass: No blistering or resin flow occurred in the test piece before and after heating at 260° C. and 290° C. Or, no blistering or resin flow occurred in the test piece before and after heating at 260° C., but blistering or resin flow occurred in the test piece after heating at 290° C. Failed: Blisters and resin flow occurred in the test piece before and after heating at 260°C and 290°C.
• thermosetting adhesive sheet of the embodiment had good positioning properties, and also good adhesion and reflow heat resistance after thermal curing.
• thermosetting adhesive sheet that does not contain a styrene-based elastomer (A) with a styrene ratio of 30% or more has high initial adhesive strength to polyimide and poor positioning ability.
• Comparative Example 2 show that in thermosetting adhesive sheets that do not contain polyfunctional resins, such as polyphenylene ether resins or epoxy resins, that have at least two reactive functional groups in their structure, the resin becomes highly fluid in high-temperature environments of 260°C or higher, making it difficult to maintain heat resistance.
• polyfunctional resins such as polyphenylene ether resins or epoxy resins

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