Classifications

• • 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
  • C09J109/00—Adhesives based on homopolymers or copolymers of conjugated diene hydrocarbons
  • C09J109/06—Copolymers with styrene
• • 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
  • C09J11/02—Non-macromolecular additives
  • C09J11/04—Non-macromolecular additives inorganic
• • 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
  • C09J125/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Adhesives based on derivatives of such polymers
  • C09J125/02—Homopolymers or copolymers of hydrocarbons
  • C09J125/04—Homopolymers or copolymers of styrene
  • C09J125/08—Copolymers of styrene
  • C09J125/10—Copolymers of styrene with 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
  • 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 containing the cured product of the thermosetting adhesive sheet.
• Patent Document 1 discloses an adhesive composition for electronic components, which contains a resin composition including a styrene-based elastomer and a specific inorganic filler in a predetermined amount, and the cured product has a relative dielectric constant and a dielectric loss tangent within a predetermined range.
• Patent Document 2 discloses a resin composition that contains a specified amount of an acid-modified styrene-based polymer, an inorganic filler having a specific particle size, which is silica or aluminum hydroxide, and a curing agent, and that has a specified light absorptance and haze in the form of a film.
• composition disclosed in Document 1 is said to be able to suppress resin flow during thermocompression bonding and to exhibit good electrical properties.
• the composition disclosed in Document 2 is said to be excellent in dielectric properties under high humidity, adhesion, and UV laser processability.
• heat-resistant resins such as polyimide and metal foils used in printed wiring boards.
• An object of the present invention is to provide a thermosetting adhesive sheet which, when cured, has excellent adhesive properties, dielectric properties and heat resistance.
• thermosetting adhesive sheet having an adhesive layer made of an adhesive composition containing the following Components A and B, wherein the cured product has a relative dielectric constant of 1.0 to 3.0 and a dielectric dissipation factor of 0.0001 to 0.01 at 23°C, 50% RH, and 28 GHz.
• Component A a resin composition containing more than 35 mass% of a styrene-based elastomer (a1) having a content of structural units derived from aromatic vinyl compounds of less than 30 mass%, and a resin (a2) having a plurality of reactive functional groups in its structure.
• Component B an inorganic filler
• the resin composition further contains a styrene-based elastomer having a content of structural units derived from an aromatic vinyl compound of 30 mass% or more.
• thermosetting adhesive sheet according to any one of [1] to [5], wherein the thermosetting adhesive sheet is attached to a polyimide film and has a 90° peel adhesive strength of 0.5 N/mm or more after curing.
• the resin (a2) has a plurality of reactive functional groups in its structure which are one or more selected from the group consisting of a hydroxyl group, a halogen group, an amino group, a carboxyl group, an epoxy group, or a functional group containing an ethylenically unsaturated bond.
• a printed wiring board comprising a cured product of the thermosetting adhesive sheet according to any one of [1] to [8].
• the present invention provides a thermosetting adhesive sheet whose cured product has excellent adhesion, a low dielectric constant and dielectric tangent, good dielectric properties, and excellent heat resistance. It also provides a printed wiring board that includes the cured product of such a thermosetting adhesive sheet.
• the present invention is a thermosetting adhesive sheet having an adhesive layer made of an adhesive composition containing the following Components A and B, wherein the cured product has a relative dielectric constant of 1.0 to 3.0 and a dielectric dissipation factor of 0.0001 to 0.01 at 23° C., 50% RH, and 28 GHz.
• Component A a resin composition containing more than 35 mass% of a styrene-based elastomer (a1) having a content of structural units derived from aromatic vinyl compounds of less than 30 mass%, and a resin (a2) having a plurality of reactive functional groups in its structure.
• Component B an inorganic filler.
• the thermosetting adhesive sheet of the present invention is also simply referred to as the "thermosetting adhesive sheet”.
• thermosetting adhesive sheet has excellent adhesion, a low dielectric constant and dielectric tangent, good dielectric properties, and excellent heat resistance. Furthermore, a printed wiring board including the cured product of the thermosetting adhesive sheet has good dielectric properties and excellent heat resistance.
• the configuration of the thermosetting adhesive sheet will be described below.
• the adhesive layer in the present thermosetting adhesive sheet has an adhesive layer made of an adhesive composition containing the following Components A and B.
• Component A A resin composition containing more than 35% by mass of a styrene-based elastomer (a1) having a content of structural units derived from an aromatic vinyl compound of less than 30% by mass, and a resin (a2) having a plurality of reactive functional groups in the structure.
• Component B An inorganic filler.
• styrene-based elastomer (a1) constituting the resin composition as component A and having a content of structural units derived from aromatic vinyl compounds of less than 30 mass%
• the content of structural units derived from aromatic vinyl compounds is preferably 25 mass% or less, more preferably 20 mass% or less.
• the content of structural units derived from such aromatic vinyl compounds is preferably 5 mass% or more, more preferably 7 mass% or more, and even more preferably 10 mass% or more.
• Examples of the styrene-based elastomer (a1) include a block copolymer having a polymer block (i) containing a structural unit derived from an aromatic vinyl compound and a polymer block (ii) containing a structural unit derived from a conjugated diene, or a hydrogenated product thereof; a random copolymer of an aromatic vinyl compound and a conjugated diene (styrene-butadiene rubber, etc.) or a hydrogenated product thereof obtained by hydrogenating the ethylenic double bond; and a block copolymer having a polymer block containing a structural unit derived from an aromatic vinyl compound and a structural unit derived from isobutylene (polystyrene-polyisobutylene-polystyrene copolymer (SIBS), etc.).
• SIBS polystyrene-polyisobutylene-polystyrene copolymer
• a block copolymer having the polymer block (i) and the polymer block (ii) or a hydrogenated product thereof is preferred.
• the polymer block (i) containing a structural unit derived from an aromatic vinyl compound in the block copolymer acts as a hard segment
• the polymer block (ii) containing a structural unit derived from a conjugated diene acts as a soft segment, respectively, and the heat resistance of the resin composition and adhesive composition as component A, and thus the adhesive layer, is improved, and the adhesiveness of the cured product is also likely to be improved.
• the content of the structural unit derived from an aromatic vinyl compound is within the preferred range, the elastic modulus of the adhesive layer is low and the wettability to the adherend is good, so that it is considered that the adhesiveness is likely to be improved.
• Aromatic vinyl compounds include, for example, styrene, ⁇ -methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, vinylanthracene, N,N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, and divinylbenzen
• Conjugated dienes include, for example, butadiene, isoprene, 2,3-dimethylbutadiene, 2-phenylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3,7-octatriene, 2-methyl-1,3-octadiene, myrcene, farnesene, 1,3-cyclohexadiene, and chloroprene.
• conjugated dienes may be used alone or in combination of two or more. Among these, butadiene and isoprene are preferred.
• styrene-based elastomer (a1) include diblock copolymers or hydrogenated products thereof, such as polystyrene-polybutadiene diblock copolymer (SB) and hydrogenated product of SB (polystyrene-poly(ethylene-butylene) diblock copolymer (SEB)), represented by (i)-(ii) when polymer block (i) containing a structural unit derived from an aromatic vinyl compound is represented by (i) and polymer block (ii) containing a structural unit derived from a conjugated diene is represented by (ii); Triblock copolymers or hydrogenated products thereof, such as polystyrene-polybutadiene-polystyrene triblock copolymer (SBS), hydrogenated products of SBS (polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer (SEBS)), polystyrene-
• SB
• the styrene-based elastomer (a1) may have a functional group, and examples thereof include a terminal amine-modified product obtained by modifying the terminal of the above-mentioned block copolymer with an amine; a maleic anhydride-modified product obtained by modifying a part of the above-mentioned copolymer with maleic anhydride; and the like.
• the styrene-based elastomer (a1) may be used alone or in combination of two or more kinds.
• As the styrene-based elastomer (a1) a commercially available product may be used.
• the styrene-based elastomer (a1) is more preferably polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer (SEBS), polystyrene-polybutadiene-polystyrene triblock copolymer (SBS), polystyrene-polyisoprene-polystyrene triblock copolymer (SIS), or polystyrene-poly(ethylene-propylene)-polystyrene triblock copolymer (SEPS).
• SEBS polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer
• SBS polystyrene-polybutadiene-polystyrene triblock copolymer
• SIS polystyrene-polyisoprene-polystyrene triblock copolymer
• SEPS poly
• the weight average molecular weight (Mw) of the styrene-based elastomer (a1) is preferably 50,000 or more, more preferably 80,000 to 1,000,000.
• Mw of each is within the above range.
• the Mw of the styrene-based elastomer (a1) is within the above range, the adhesiveness and heat resistance when the thermosetting adhesive sheet is cured can be further improved, and good low dielectric properties can be exhibited.
• the Mw of the styrene-based elastomer (a1) is a value calculated in terms of standard polystyrene measured by gel permeation chromatography (GPC), and the measurement conditions are as follows. ⁇ Measurement conditions> GPC device: HLC-8329GPC (manufactured by Tosoh Corporation) Sample concentration: 0.5% by mass tetrahydrofuran (THF) solution Sample injection volume: 100 ⁇ L Eluent and flow rate: THF, 1.0 mL/min Measurement temperature: 40°C Main column: TSKgel GMHHR-H (20) x 2 Guard column: TSKgel HXL-H Detector: Differential refractometer Standard polystyrene Mw: 10,000 to 20,000,000 (manufactured by Tosoh Corporation)
• the resin composition which is component A contains more than 35% by mass of the styrene-based elastomer (a1), preferably 45% by mass or more, more preferably 55% by mass or more, and even more preferably 70% by mass or more.
• the content of the styrene-based elastomer (a1) in the resin composition is preferably 95% by mass or less, more preferably 90% by mass or less.
• the resin composition which is component A contains two or more types of styrene-based elastomers (a1), it is preferable that the total content thereof is within the above range.
• the adhesiveness and heat resistance when the thermosetting adhesive sheet is cured can be further improved, and good low dielectric properties can be exhibited.
• Resin (a2) having a plurality of reactive functional groups in the structure contains a resin (a2) having a plurality of reactive functional groups in its structure (hereinafter also referred to simply as "resin (a2)").
• the reactive functional groups that the resin (a2) has in its structure are preferably one or more selected from the group consisting of hydroxyl groups, halogen groups, amino groups, carboxyl groups, epoxy groups, or functional groups containing ethylenic unsaturated bonds.
• thermosetting adhesive sheet after curing it is more preferable to select one or more selected from the group consisting of amino groups, carboxyl groups, epoxy groups, and functional groups containing ethylenic unsaturated bonds, because they have high polymerization reactivity and are easy to form a crosslinked structure.
• functional groups containing ethylenic unsaturated bonds include (meth)acrylic groups, (meth)acryloyl groups, and vinyl groups.
• (meth)acrylic is a term that collectively refers to acrylic, methacrylic, and both of them.
• (meth)acryloyl group” is a term that collectively refers to acryloyl groups, methacryloyl groups, and both of them.
• the content of resin (a2) is preferably in the range of 1 to 20% by mass, more preferably in the range of 2 to 20% by mass, even more preferably in the range of 5 to 20% by mass, and particularly preferably in the range of 10 to 20% by mass, based on the total resin composition.
• the resin (a2) forms a crosslinked structure when the thermosetting adhesive sheet is cured, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and further improving heat resistance. This is preferable.
• the resin (a2) include modified polyphenylene ether resins, epoxy resins, and bismaleimide resins. Among these, modified polyphenylene ether resins and epoxy resins are preferred.
• the modified polyphenylene ether resin preferably has a polyphenylene ether chain in the molecule and a reactive functional group at the end, and preferably has at least two or more types of functional groups containing epoxy groups and ethylenically unsaturated bonds as reactive functional groups in one molecule.
• the modified polyphenylene ether resin preferably has at least one type of functional group containing epoxy groups and ethylenically unsaturated bonds at both ends.
• the modified polyphenylene ether resin having (meth)acryloyl groups at both ends is preferred from the viewpoint of improving the adhesiveness and heat resistance of the thermosetting adhesive sheet after curing and imparting good dielectric properties.
• the number average molecular weight (Mn) of the modified polyphenylene ether resin is preferably 1000 to 10000, more preferably 1000 to 3000.
• Mn of the modified polyphenylene ether resin is a value calculated as standard polystyrene by GPC, and a value measured under the same conditions as the measurement conditions of the Mw of the above-mentioned styrene-based elastomer (a1) can be used.
• a modified polyphenylene ether resin When a modified polyphenylene ether resin is used as resin (a2), its content is preferably in the range of 5 to 20 mass %, more preferably in the range of 9 to 15 mass %, relative to the resin composition of component A. This range is presumably because the modified polyphenylene ether resin improves the storage modulus of the adhesive layer, and is preferable from the viewpoint that the cured product of this thermosetting adhesive sheet has better adhesion and heat resistance, and can be imparted with good dielectric properties. In particular, this is preferable from the viewpoint that the modified polyphenylene ether resin forms a crosslinked structure when curing this thermosetting adhesive sheet, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and further improving heat resistance.
• an organic peroxide may be further contained in the resin composition which is component A.
• the organic peroxide acts as a curing agent (polymerization initiator) for the modified polyphenylene ether resin.
• organic peroxides include 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-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide
• the organic peroxides may be used alone or in combination of two or more. Among them, dicumyl peroxide is preferred from the viewpoint of further improving the adhesiveness and heat resistance of the present thermosetting adhesive sheet after curing.
• the content is preferably in the range of 0.1 to 10 mass% of the entire resin composition, more preferably in the range of 0.5 to 7 mass%, even more preferably in the range of 1 to 5 mass%, and particularly preferably in the range of 1.5 to 3 mass%.
• the content of the organic peroxide is within the above range, it is preferable from the viewpoint of further improving the adhesiveness and heat resistance of the present thermosetting adhesive sheet after curing. In particular, it is preferable from the viewpoint of suppressing the fluidity of the adhesive layer after curing at high temperatures and further improving the heat resistance by promoting the formation of a crosslinked structure of the modified polyphenylene ether resin when curing the present thermosetting adhesive sheet.
• epoxy resin a compound having two or more epoxy groups in one molecule can 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 ...tetramethylbiphenyl type epoxy resins, polyhydroxynaphthalene type epoxy resins, isocyanate modified epoxy resins, tetramethylbiphenyl type epoxy resins, polyhydroxynaphthalene type
• the epoxy resin may be used alone or in combination of two or more kinds.
• 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 are preferred from the viewpoint of further improving the adhesiveness and heat resistance of the present thermosetting adhesive sheet after curing.
• an epoxy resin is used as resin (a2)
• its content is preferably in the range of 1 to 15% by mass, more preferably in the range of 2 to 10% by mass, relative to the resin composition of component A.
• This range is preferable from the viewpoint that the cured product of the present thermosetting adhesive sheet has better adhesion and heat resistance, and can be imparted with good dielectric properties.
• this is preferable from the viewpoint that the epoxy resin forms a crosslinked structure when the present thermosetting adhesive sheet is cured, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and further improving heat resistance.
• an epoxy resin curing agent may be further contained in the resin composition which is the component A.
• the epoxy resin curing agent acts as a catalyst for accelerating the curing reaction of the epoxy resin described above.
• examples of epoxy resin curing agents include imidazole-based, phenol-based, amine-based, and acid anhydride-based compounds, and the above-mentioned organic peroxides.
• the epoxy resin curing agent may be used alone or in combination of two or more. Among them, from the viewpoint of improving the storage stability of the resin composition, which is component A, at room temperature, a latent curing agent is preferred, and an imidazole-based curing agent that is encapsulated and has latent properties is more preferred.
• a microcapsule-type latent curing agent in which a latent imidazole modified body is used as a core and the surface is coated with polyurethane can be mentioned.
• the content is preferably in the range of 1 to 10 mass% relative to the entire resin composition, more preferably in the range of 1 to 7 mass%, even more preferably in the range of 2 to 5 mass%, and particularly preferably in the range of 2 to 3 mass%.
• the curing property of the present thermosetting adhesive sheet when heated can be improved, and the adhesiveness and heat resistance after curing can be further improved.
• the epoxy resin curing agent promotes the formation of a crosslinked structure of the epoxy resin, which suppresses the fluidity of the adhesive layer after curing at high temperatures and further improves the heat resistance.
• the resin composition of component A may further contain a styrene-based elastomer (a') having a content of structural units derived from an aromatic vinyl compound of 30 mass% or more.
• the content of structural units derived from an aromatic vinyl compound in the styrene-based elastomer (a') is preferably 30 to 80 mass%, more preferably 30 to 70 mass%.
• the content thereof is preferably within the range of 1 to 50 mass%, more preferably 1 to 35 mass%, and particularly preferably 1 to 25 mass%, based on the entire resin composition.
• the total content of the styrene-based elastomer (a1) and the styrene-based elastomer (a') is preferably in the range of 50 to 90 mass %, more preferably 70 to 90 mass %, based on the entire resin composition. Furthermore, the mass ratio [(a1)/(a')] of the styrene-based elastomer (a1) to the styrene-based elastomer (a') is preferably in the range of 99/1 to 42/58, more preferably in the range of 99/1 to 66/34, and particularly preferably in the range of 99/1 to 85/15.
• thermosetting adhesive sheet further contains a styrene-based elastomer (a') having a content of structural units derived from an aromatic vinyl compound within the above-mentioned range, the heat resistance of the cured product of the thermosetting adhesive sheet is improved while maintaining the adhesiveness, and the cured product is likely to exhibit good dielectric properties.
• a' styrene-based elastomer
• an inorganic filler having electrical insulation properties is preferable.
• the inorganic filler preferably has a flaky or plate-like shape.
• the aspect ratio of the inorganic filler is preferably 2 to 1000, more preferably 5 to 500.
• the aspect ratio of the inorganic filler is determined, for example, from a measured value observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).
• the average particle size of the inorganic filler is preferably 1 to 10 ⁇ m, and more preferably 2 to 8 ⁇ m.
• the average particle size of the inorganic filler can be calculated, for example, by a laser scattering method, and can be defined as the volume-based cumulative 50% diameter (D50).
• the specific gravity of the inorganic filler is preferably less than 5.
• the aspect ratio, average particle size, and specific gravity of the inorganic filler are within the above ranges, the inorganic filler is easily dispersed in the adhesive composition or adhesive layer, and the curing property of the thermosetting adhesive sheet is easily improved.
• the cured product has excellent adhesion and heat resistance while maintaining mechanical properties, and exhibits good dielectric properties, particularly low relative dielectric constant and dielectric loss tangent.
• the inorganic filler from the viewpoint of providing the cured product of the thermosetting adhesive sheet with excellent electrical insulation, heat resistance, and dielectric properties, mica, silicon-based inorganic fillers such as talc, boron nitride, and glass fiber are preferred, and at least one selected from boron nitride and mica is preferred.
• the inorganic filler may be used alone or in combination of two or more types.
• boron nitride hexagonal boron nitride is preferable from the viewpoint of excellent electrical insulation, thermal conductivity, heat resistance, corrosion resistance, etc.
• boron nitride products can also be used, and examples thereof include Denka Boron Nitride Powder “HGP”, “SP-3”, “GP”, “MGP” or “GHP” grades manufactured by Denka Corporation; CarboTherm “PCT-UFB”, “PCTP2”, and “PCTF5" manufactured by Saint-Gobain; and "PW02" manufactured by Johnnye Tech.
• the mica synthetic mica is preferable from the viewpoint of excellent electrical insulation, thermal conductivity, heat resistance, corrosion resistance, electrical insulation, etc.
• synthetic mica commercially available products can be used, for example, "MK-100” manufactured by Katakura Co-op Agri Co., Ltd., "NK-8G” and “NK-8G-SI” manufactured by Nihon Koken Co., Ltd., and "A11” manufactured by Yamaguchi Mica Co., Ltd.
• the content of the inorganic filler is preferably 1 to 50% by volume, and more preferably 5 to 40% by volume, based on the adhesive composition. On the other hand, the content of the inorganic filler is preferably 1 to 1000 parts by mass, and more preferably 5 to 500 parts by mass, per 100 parts by mass of the adhesive composition.
• the volumes of each are calculated and then summed.
• the volume of the adhesive composition is calculated by calculating the volume of each component contained in the adhesive composition and then summing them.
• the content of the inorganic filler is within the above range, the dispersibility of the inorganic filler in the adhesive composition or adhesive layer is easily maintained, and the curing property of the thermosetting adhesive sheet is easily improved.
• the cured product has excellent adhesion and heat resistance while maintaining mechanical properties, and exhibits good dielectric properties, particularly low relative dielectric constant and dielectric loss tangent.
• thermosetting adhesive sheet is made of an adhesive composition containing an inorganic filler (component B), so that the thermosetting adhesive sheet has a low dielectric constant and dielectric tangent after curing, and exhibits good dielectric properties.
• the adhesive layer of the present thermosetting adhesive sheet is made of an adhesive composition containing a resin composition as component A and an inorganic filler as component B.
• the adhesive composition contains 1 to 50 volume % of an inorganic filler that is at least one selected from boron nitride and mica relative to the adhesive composition.
• the adhesive composition may further contain other components, such as a tackifier resin; a crosslinking agent, an antiaging agent, an ultraviolet absorber, a polymerization inhibitor, a surface conditioner, an antistatic agent, a foaming agent, an antifoaming agent, a viscosity modifier, a light resistance stabilizer, a weather resistance stabilizer, a heat resistance stabilizer, an antioxidant, a leveling agent, an organic pigment, an inorganic pigment, and a pigment dispersant, provided the effects of the present invention are not impaired.
• a tackifier resin such as a tackifier resin; a crosslinking agent, an antiaging agent, an ultraviolet absorber, a polymerization inhibitor, a surface conditioner, an antistatic agent, a foaming agent, an antifoaming agent, a viscosity modifier, a light resistance stabilizer, a weather resistance stabilizer, a heat resistance stabilizer, an antioxidant, a leveling agent, an organic pigment, an inorganic pigment, and a pigment dis
• the adhesive layer of the thermosetting adhesive sheet is made of an adhesive composition containing the above-mentioned resin composition (component A) and inorganic filler (component B).
• the adhesive layer may be a single layer or a multilayer of two or more layers.
• There is no particular limit to the thickness of the adhesive layer but it is usually preferably 10 to 75 ⁇ m, more preferably 15 to 50 ⁇ m, and even more preferably 15 to 25 ⁇ m.
• the thickness of the adhesive layer is within the above range, it is preferable from the viewpoint of being able to thin parts containing the cured product of the thermosetting adhesive sheet, such as printed wiring boards, while maintaining the adhesiveness and heat resistance of the thermosetting adhesive sheet after curing.
• the storage modulus E' of the cured adhesive layer at 30°C is preferably in the range of 5.0x106 to 5.0x108 Pa, more preferably in the range of 8.0x106 to 5.0x108 Pa, even more preferably in the range of 8.0x106 to 1.0x108 Pa, and particularly preferably in the range of 9.0x106 to 1.0x108 Pa.
• the loss tangent (tan ⁇ ) of the cured adhesive layer at 30° C. is preferably in the range of 0.10 to 0.40. It is preferable that the storage modulus E' and tan ⁇ are within the above ranges from the viewpoint of further improving the adhesiveness of the present thermosetting adhesive sheet after curing.
• the storage modulus E' and tan ⁇ can be controlled, for example, by adjusting the type and content of the styrene-based elastomer (a1) in component A constituting the adhesive composition, or the content of the structural unit derived from the aromatic vinyl compound.
• the storage modulus E' and tan ⁇ were measured by overlapping the adhesive layers of this thermosetting adhesive sheet to a thickness of 100 ⁇ m, preparing a test piece with a gauge interval of 1.5 cm and a width of 0.5 cm, heating and curing it at 180°C for 60 minutes, and then using a tensile viscoelasticity tester (manufactured by Rheometrics, Inc., product name: RSA-II) under conditions of a sine wave load mode (load change frequency of 3 Hz), a tensile strain of 0.1%, and a heating rate of 5°C/min.
• a tensile viscoelasticity tester manufactured by Rheometrics, Inc., product name: RSA-II
• the cured product of the adhesive layer of the present thermosetting adhesive sheet in other words, the cured product of the present thermosetting adhesive sheet, has a relative dielectric constant of 1.0 to 3.0 and a dielectric dissipation factor of 0.0001 to 0.01 at 23° C., 50% RH and 28 GHz.
• the cured product of the adhesive layer of the present thermosetting adhesive sheet more preferably has a relative dielectric constant of 1.0 to 2.8 at 23° C., 50% RH and 28 GHz.
• the dielectric loss tangent of the cured product of the adhesive layer of the present thermosetting adhesive sheet at 23° C., 50% RH and 28 GHz is more preferably 0.0001 to 0.005, and even more preferably 0.0001 to 0.003.
• the cured product of the adhesive layer of the present thermosetting adhesive sheet in other words, the cured product of the present thermosetting adhesive sheet, has a relative dielectric constant and dielectric tangent within the above-mentioned ranges due to the adhesive layer containing the above-mentioned styrene-based elastomer (a1), resin (a2), and inorganic filler, and can exhibit good dielectric properties.
• the dielectric constant (Dk) and the dielectric loss tangent (Df) are values measured at 23°C, 50% RH, and 28 GHz using a dielectric constant measuring device (Keysight, split cylinder resonator) on the adhesive layer of this thermosetting adhesive sheet or on a test piece prepared by cutting this thermosetting adhesive sheet to 35 mm x 50 mm and curing it at 180°C for 1 hour.
• the gel fraction of the cured adhesive layer of the thermosetting adhesive sheet after further heating for 10 minutes at 290° C. is preferably 10 to 100%, more preferably 15 to 95%, and even more preferably 30 to 90%.
• the gel fraction can be adjusted, for example, by adjusting the type and content of the resin (a2) and the type and content of the organic peroxide contained in the adhesive layer.
• the gel fraction was calculated by heating the adhesive layer of the thermosetting adhesive sheet at 180° C. for 60 minutes to cure it, then further heating it at 290° C. for 10 minutes, cutting out a test piece from the resulting layer, and measuring its mass (M 0 ).
• the present thermosetting adhesive sheet has an adhesive layer made of the above-mentioned adhesive composition.
• the present thermosetting adhesive sheet may be composed of a single adhesive layer, or may be composed of two or more adhesive layers, which may be the same or different, laminated together.
• the thermosetting adhesive sheet 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 further laminated on the adhesive layer.
• the thermosetting adhesive sheet may be a single-sided adhesive sheet in which the adhesive layer is laminated on one side of the substrate, or a double-sided adhesive sheet in which the adhesive layer is laminated on both sides of the substrate.
• the substrate examples include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; polyester resins; vinyl chloride resins; vinyl acetate resins; polyimide resins; polyamide resins; fluorine-based resins; resin films made of resins such as cellophane; papers such as Japanese paper, craft paper, glassine paper, fine paper, synthetic paper, and topcoated paper; fabrics such as woven fabrics and nonwoven fabrics made by spinning alone or in combination various fibrous materials such as cotton, staple fiber, Manila hemp, pulp, rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber, and polyolefin fiber; natural rubber sheets, butyl rubber sheets; foam sheets such as foamed polyurethane sheets and foamed polychloroprene rubber sheets; metal foils such as aluminum foil and copper foil; and composites of these.
• polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers
• the shape and dimensions of the thermosetting adhesive sheet are not particularly limited, and examples thereof include adhesive sheets that have been subjected to a punching process or the like and have a shape and dimensions suitable for attachment to a specific adherend, and long adhesive sheets that have not yet been processed into a specific shape.
• the thickness of the thermosetting adhesive sheet is not particularly limited as long as it does not impair the effects of the present invention. Usually, it is preferably 10 to 150 ⁇ m, more preferably 10 to 100 ⁇ m, even more preferably 10 to 75 ⁇ m, even more preferably 15 to 50 ⁇ m, and particularly preferably 15 to 25 ⁇ m. If the thickness of the thermosetting adhesive sheet is within the above range, it is preferable from the viewpoint that the printed wiring board including the cured product of the thermosetting adhesive sheet can be made thin while maintaining the adhesiveness and heat resistance of the thermosetting adhesive sheet after curing.
• thermosetting adhesive sheet can be firmly bonded to an adherend by being applied to the adherend and then cured by heat.
• the curing conditions of the thermosetting adhesive sheet can be appropriately set depending on the types and contents of the styrene-based elastomer (a1) and resin (a2) contained in the adhesive composition constituting the adhesive layer.
• the curing temperature is, for example, preferably from 100 to 220°C, more preferably from 120 to 200°C, and even more preferably from 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.
• the thermosetting adhesive sheet preferably has a 90° peel adhesive strength of 0.5 N/mm or more after being applied to a polyimide film and cured.
• the 90° peel adhesive strength is more preferably 0.8 N/mm or more, and even more preferably 1.0 N/mm or more.
• the 90° peel adhesive strength is preferably 10 N/mm or less.
• the present thermosetting adhesive sheet is applied to a polyimide film, and the 90° peel adhesive strength after curing can be measured by the following method. That is, a polyimide film (manufactured by DuPont Toray, Kapton 100H, thickness 0.025 mm) is attached to one side of the thermosetting adhesive sheet, and a polyimide film (manufactured by DuPont Toray, Kapton 300H, thickness 0.075 mm) is attached to the other side under an environment of 23 ° C. and 50% RH to prepare a test piece. The test piece is pressed at 4.0 MPa for 10 minutes while being heated at 180 ° C. using a heat press machine, and then heated in a dryer at 180 ° C.
• a polyimide film manufactured by DuPont Toray, Kapton 100H, thickness 0.025 mm
• a polyimide film manufactured by DuPont Toray, Kapton 300H, thickness 0.075 mm
• test piece for evaluation is prepared.
• the test piece for evaluation is cut to 10 mm x 100 mm, and the 0.075 mm thick polyimide film side is fixed to a SUS plate (30 mm x 130 mm).
• the end of the polyimide film of the test piece that is not fixed to the SUS plate is clamped in a tensile tester ("RTH-1310" manufactured by A & D Co., Ltd.) and pulled in a 90° direction at 50 mm/min.
• the strength (N/mm) at the time of peeling is defined as the 90° peel adhesive strength.
• the adhesive composition constituting the adhesive layer of this thermosetting adhesive sheet can be produced by preparing a resin composition by supplying and stirring the above-mentioned styrene-based elastomer (a1), resin (a2), and, if necessary, styrene-based elastomer (a'), and various optional additive components using a conventional dispersing machine such as a bead mill or stirrer, and then supplying an inorganic filler.
• a resin composition by supplying and stirring the above-mentioned styrene-based elastomer (a1), resin (a2), and, if necessary, styrene-based elastomer (a'), and various optional additive components using a conventional dispersing machine such as a bead mill or stirrer, and then supplying an inorganic filler.
• a solvent capable of dissolving the styrene-based elastomer (a1), resin (a2), and, if necessary, the styrene-based elastomer (a'), such as toluene, may be present in the presence of the resin composition.
• the thermosetting adhesive sheet 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 a predetermined thickness on the surface of the release liner using a coater or the like, and drying it.
• the release liner is not particularly limited and can be appropriately selected depending on the purpose.
• the release liner 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; laminated paper in which the above-mentioned paper and resin film are laminated together, and the above-mentioned paper that has been subjected to a sealing treatment with clay, polyvinyl alcohol, or the like; and these paper sheets that have been subjected to a release treatment with silicone-based resin or the like on one or both sides.
• the release liners may be used alone or in combination of two or more kinds.
• the above-mentioned thickness and physical properties of the thermosetting adhesive sheet do not include the release liner.
• thermosetting adhesive sheet exhibits excellent adhesive properties in the cured product, has low relative dielectric constant and dielectric tangent, exhibits good dielectric properties, and further has excellent heat resistance, and therefore can be suitably used, for example, for interlayer bonding of printed wiring boards and for bonding and fixing terminal portions of printed wiring boards to connecting substrates that back the terminal portions.
• one embodiment of the present invention is a printed wiring board including a cured product of the present 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, a flexible printed wiring board having a flexible insulating substrate, or a flex-rigid printed wiring board in which the insulating substrate has a hard portion and a flexible portion.
• the present thermosetting adhesive sheet can also be suitably used for parts for high frequency applications, such as flexible flat cables and various high-speed communication compatible modules. The uses of the thermosetting adhesive sheet are not limited to those mentioned above, but it can be used to manufacture a variety of products that utilize its properties.
• thermosetting adhesive sheet ⁇ having an adhesive layer made of an adhesive composition containing the following Components A' and B, and having a cured product having a relative dielectric constant of 1.0 to 3.0 at 23°C, 50% RH, and 28 GHz.
• Component A' a resin composition containing a styrene-based elastomer and a modified polyphenylene ether resin, the content of the modified polyphenylene ether resin being 5 to 50 mass %.
• Component B an inorganic filler.
• the dielectric loss tangent of the thermosetting adhesive sheet ⁇ is preferably 0.0001 to 0.01.
• the adhesive composition constituting the adhesive layer of the thermosetting adhesive sheet ⁇ contains the above-mentioned Component A′ and Component B. Details of the styrene-based elastomer contained in Component A' are the same as those of the styrene-based elastomer (a1) in the present thermosetting adhesive sheet described above, except that there are no particular restrictions on the content of structural units derived from aromatic vinyl compounds.
• modified polyphenylene ether resin contained in Component A' are the same as those of the modified polyphenylene ether resin described for Resin (a2) in the present thermosetting adhesive sheet described above, and the same also applies in that an organic peroxide may also be contained.
• the content of the modified polyphenylene ether resin is 5 to 50% by mass, preferably 5 to 20% by mass, and more preferably 9 to 15% by mass, relative to the resin composition which is component A'.
• the storage modulus of the adhesive layer is improved by the modified polyphenylene ether resin, and the cured product of the thermosetting adhesive sheet ⁇ has better adhesion and heat resistance.
• the modified polyphenylene ether resin forms a crosslinked structure when the thermosetting adhesive sheet ⁇ is cured, thereby suppressing the fluidity of the cured adhesive layer at high temperatures and further improving heat resistance, and thus suppressing the occurrence of defects such as blistering caused by exposure to high temperatures in the manufacturing process of the part, such as the reflow process.
• Details of the inorganic filler (component B) are the same as those of component B in the present thermosetting adhesive sheet described above.
• thermosetting adhesive sheet ⁇ preferably has a 90° peel adhesive strength of 0.5 N/mm or more after being applied to a polyimide film and cured.
• thermosetting adhesive sheet ⁇ has low relative dielectric constant and dielectric loss tangent, and exhibits good dielectric properties, and can exhibit good transmission properties when used in high-frequency components such as printed wiring boards. Furthermore, printed wiring boards containing a cured product of the thermosetting adhesive sheet ⁇ have excellent heat resistance, and can suppress defects such as blistering caused by exposure to high temperatures during the manufacturing process for the components, such as the reflow process.
• thermosetting adhesive sheet and a printed wiring board including a cured product of the present thermosetting adhesive sheet
• present invention is not limited to the configuration of the above-mentioned embodiment.
• present thermosetting adhesive sheet may have any other configuration in addition to the configuration of the above-mentioned embodiment, or may be replaced with any configuration that produces a similar effect.
• Periodic filler decomposition temperature for half-life of 1 minute is 175°C, specific gravity is 1.1) ⁇ Inorganic filler>
• thermosetting adhesive sheets [Examples 1 to 9] A resin composition was prepared by uniformly dissolving the styrene-based elastomer, resin (a2), and organic peroxide shown in Table 1 in toluene in the amounts shown in Table 1 to a total amount of 25 mass %. An inorganic filler was added to the obtained resin composition in the amount shown in Table 1 and mixed uniformly to prepare an adhesive composition. The obtained adhesive composition was applied to the surface of a release liner ("50E-0010 ST-3" manufactured by Fujimori Kogyo Co., Ltd., thickness 50 ⁇ m) so that the thickness after drying was 25 ⁇ m, and dried for 2 minutes in a dryer at 85° C.
• a release liner (“50E-0010 ST-3" manufactured by Fujimori Kogyo Co., Ltd., thickness 50 ⁇ m)
• thermosetting adhesive sheet in which the release liner, adhesive layer, and release liner were laminated in this order.
• thermosetting adhesive sheets prepared in each example were subjected to the following evaluation of physical properties. 2-1. 90° peel adhesive strength after curing
• the release liner on one side of the thermosetting adhesive sheet prepared in each example was peeled off, and a polyimide film (manufactured by Toray DuPont Co., Ltd., Kapton 100H, thickness 0.025 mm) was attached under an environment of 23°C and 50% RH, and then the release liner on the other side was peeled off, and a polyimide film (manufactured by Toray DuPont Co., Ltd., Kapton 300H, thickness 0.075 mm) was attached under an environment of 23°C and 50% RH to prepare a test piece.
• This test piece was pressed at 4.0 MPa for 10 minutes while being heated at 180°C using a heat press machine, and then heated in a dryer at 180°C for 50 minutes to cure the test piece, and an evaluation test piece was prepared.
• the obtained test piece for evaluation was cut to 10 mm x 100 mm, and the 0.075 mm thick polyimide film side was fixed to a SUS plate (30 mm x 130 mm).
• the end of the polyimide film of the test piece that was not fixed to the SUS plate was clamped in a tensile tester ("RTH-1310" manufactured by A&D Co., Ltd.) and pulled in a 90° direction at 50 mm/min.
• the strength (N/mm) at the time of peeling was defined as the 90° peel adhesive strength.
• Dielectric constant (Dk) and dielectric loss tangent (Df) The thermosetting adhesive sheet prepared in each example was cut to 35 mm ⁇ 50 mm and cured for 1 hour at 180 ° C. to prepare a test piece.
• the relative dielectric constant (Dk) and dielectric loss tangent (Df) of this test piece were measured at 23 ° C., 50% RH, and 28 GHz using a dielectric constant measuring device (Keysight, split cylinder resonator).
• thermosetting adhesive sheets of Examples 1 to 4 have an adhesive layer made of a resin composition (component A) containing more than 35 mass% of a styrene-based elastomer (a1) having a content of structural units derived from aromatic vinyl compounds of less than 30 mass%, and a resin (a2) having a plurality of reactive functional groups in its structure, and an adhesive composition containing an inorganic filler (component B). Therefore, the cured product has excellent adhesion, and has low dielectric constants and dielectric tangents, exhibiting good dielectric properties.
• thermosetting adhesive sheet of Example 5 which does not contain an inorganic filler
• thermosetting adhesive sheets of Examples 6 and 7, in which the content of the styrene-based elastomer (a1) in the resin composition is 35 mass% or less or which does not contain any styrene-based elastomer (a1), have reduced adhesiveness of the cured product compared to the thermosetting adhesive sheets of Examples 1 to 4.
• thermosetting adhesive sheet of Example 8 has an adhesive layer containing a styrene-based elastomer with a content of structural units derived from aromatic vinyl compounds of 30 mass %, and the adhesiveness of the cured product is maintained due to the combined effects of the styrene-based elastomer constituting the resin composition being acid-modified and the inclusion of 5 to 50 mass % of a modified polyphenylene ether resin as resin (a2).
• the thermosetting adhesive sheet of Example 9 has a resin (a2), particularly a modified polyphenylene ether resin, content of 5 mass % or less, and therefore the adhesiveness of the cured product is reduced compared to the thermosetting adhesive sheets of Examples 1-4.
• thermosetting adhesive sheet of the present invention has excellent adhesion, exhibits good dielectric properties, and is excellent in various physical properties such as heat resistance, etc.
• the thermosetting adhesive sheet of the present invention is particularly useful for printed wiring boards, and can also be suitably used for parts for high-frequency applications such as flexible flat cables and various high-speed communication modules.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Laminated Bodies (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=94534216

Family Applications (1)

Country Status (5)

Citations (4)

• 2024
  • 2024-06-03 TW TW113120491A patent/TW202509166A/zh unknown
  • 2024-06-11 CN CN202480042342.1A patent/CN121399222A/zh active Pending
  • 2024-06-11 KR KR1020257043588A patent/KR20260049119A/ko active Pending
  • 2024-06-11 WO PCT/JP2024/021197 patent/WO2025032955A1/ja active Pending
  • 2024-06-11 JP JP2025539156A patent/JPWO2025032955A1/ja active Pending

Patent Citations (4)

Also Published As

Similar Documents

Legal Events