Adhesive composition and adhesive sheet, laminate, and printed wiring board comprising the same

Abstract

The present invention aims to provide an adhesive composition that exhibits good appearance, excellent adhesion, and excellent low dielectric properties even after a long-term heat resistance test at 125°C for 1000 hours, as well as adhesive sheets, laminates, and printed circuit boards comprising the present invention. An adhesive composition is characterized by comprising an acid-modified resin, an antioxidant (A), a heavy metal passivator (B), and an epoxy resin (C), wherein the content of the antioxidant (A) is 1.0 part by weight or less relative to 100 parts by weight of the acid-modified resin, and the content of the heavy metal passivator (B) is 1.0 part by weight or less.

Description

Technical Field

[0001] This invention relates to an adhesive composition. More specifically, it relates to an adhesive composition for bonding printed circuit boards to a substrate. Background Technology

[0002] In recent years, with the miniaturization, weight reduction, high density, and high power of electronic devices, the performance requirements for printed circuit boards (electronic circuit boards) have become increasingly stringent. In particular, to improve transmission speed, high-frequency signals are being used, thus increasing the demand for low dielectric properties (low dielectric constant, low dielectric loss tangent) of printed circuit boards in the high-frequency region. To achieve these low dielectric properties, new substrate and adhesive compositions for printed circuit boards are being developed.

[0003] For rigid substrate materials, there has been a shift from traditional FR-4 (Flame Retardant Type 4) to the use of low-dielectric resins such as fluoropolymers. Similarly, for flexible printed circuit boards (FPCs), films with low-dielectric properties such as liquid crystal polymers (LCPs) or fluoropolymers are increasingly replacing traditional polyimide films. As adhesive compositions for laminating these low-dielectric resins or copper-clad laminates (CCLs) containing them, adhesive compositions combining polypropylene-based resins and epoxy resins are being developed (Patent Document 1), as well as adhesive compositions containing styrene-based elastomers (Patent Document 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2022-164870

[0007] Patent Document 2: Japanese Patent Application Publication No. 2023-032287 Invention Summary

[0008] [The problem the invention aims to solve]

[0009] In recent years, the development of autonomous vehicles has become increasingly active. Millimeter-wave radar, one of the core sensors for autonomous driving, is known for its ability to measure distance, speed, and angle of distant objects. Because millimeter-wave radar antennas use high-frequency signals, the adhesive composition for printed circuit boards is required to have low dielectric properties to reduce transmission loss. Furthermore, in applications requiring high reliability, such as automotive millimeter-wave radar antennas, the adhesive composition must maintain its adhesion and low dielectric properties even after being placed in harsh environments such as high temperature (125°C) or high temperature and humidity (85°C, 85% RH) for more than 1000 hours.

[0010] In response, the inventors studied the adhesive compositions containing polypropylene-based resins or styrene-based elastomers disclosed in Patent Documents 1 and 2. The results showed that when these resins were placed in a high-temperature environment for a period of time, they underwent oxidation-induced degradation, leading to a significant decrease in the peel strength of the adhesive composition and various problems such as deterioration of dielectric properties (dielectric constant, etc.) due to the increase in highly polar groups. In particular, since the adhesive composition for printed circuit boards comes into contact with metal substrates such as copper foil, the resulting copper ions and other heavy metal ions promote resin oxidation-based degradation. Furthermore, compared to placing the composition in a high-temperature, high-humidity environment (85°C, 85% RH) for more than 1000 hours, the resin in the former environment is more prone to oxidation, representing a more stringent test for the adhesive composition. With the increasing demand for highly reliable electronic devices, there is a need for an adhesive composition that can withstand more stringent tests.

[0011] The present invention was made in view of the aforementioned problems in the prior art. That is, the object of the present invention is to provide an adhesive composition that exhibits good appearance and excellent adhesion and excellent low dielectric properties even after a long-term heat resistance test at 125°C for 1000 hours, as well as adhesive sheets, laminates and printed circuit boards containing the same.

[0012] Technical means to solve the problem

[0013] Through in-depth research, the inventors discovered that the above-mentioned problems can be solved by the following means, thus completing this invention. That is, this invention comprises the following components.

[0014] [1] An adhesive composition, characterized in that it comprises an acid-modified resin, an antioxidant (A), a heavy metal passivator (B) and an epoxy resin (C), wherein the content of the antioxidant (A) is 1.0 part by weight or less relative to 100 parts by weight of the acid-modified resin, and the content of the heavy metal passivator (B) is 1.0 part by weight or less.

[0015] [2] According to the adhesive composition of [1], wherein the acid-modified resin is one or more resins selected from acid-modified polystyrene resin, acid-modified cyclic olefin polymer and acid-modified polyolefin.

[0016] [3] The adhesive composition according to [1] or [2], wherein the heavy metal passivator (B) comprises at least one of hydrazine-based heavy metal passivator and phosphite-based heavy metal passivator.

[0017] [4] An adhesive composition according to any one of [1] to [3], wherein the heavy metal passivator (B) has an intramolecular chemical structure represented by formula (II).

[0018] 【Chemistry 1】

[0019]

[0020] In equation (II), * represents the bonding site, R 4 ~R 6 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.]

[0021] [5] The adhesive composition according to any one of [1] to [4], wherein the content of the heavy metal passivating agent (B) is 1 to 200 parts by weight relative to 100 parts by weight of the antioxidant (A).

[0022] [6] The adhesive composition according to any one of [1] to [5], wherein the content of the heavy metal passivating agent (B) is 0.01 parts by weight or more relative to 100 parts by weight of the acid-modified resin.

[0023] [7] The adhesive composition according to any one of [1] to [6], wherein the antioxidant (A) is selected from one or more of phenolic antioxidants, sulfur-based antioxidants, amine-based antioxidants and phosphorus-based antioxidants.

[0024] [8] An adhesive composition according to any one of [1] to [7], wherein the antioxidant (A) has an intramolecular chemical structure represented by formula (I).

[0025] 【Chemistry 2】

[0026]

[0027] In equation (I), * represents the bonding site, R 1 ~R 3 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.]

[0028] [9] An adhesive composition according to any one of [1] to [8], wherein the epoxy resin (C) is a multifunctional epoxy resin.

[0029]

[10] The adhesive composition according to any one of [1] to [9], wherein the epoxy resin (C) has an epoxy value of 5,000 to 12,000 equivalents / 10 6 g.

[0030]

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

[10] , wherein the epoxy resin (C) is selected from one or more glycidylamine type epoxy resins and isocyanuric acid containing glycidyl groups.

[0031]

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

[11] is used in a printed circuit board.

[0032]

[13] An adhesive sheet having an adhesive composition as described in any one of [1] to

[11] laminated on a release substrate.

[0033]

[14] A laminate having an adhesive composition as described in any one of [1] to

[11] laminated on a substrate, wherein the substrate is a resin substrate, a metal substrate, a paper substrate or an inorganic non-metallic substrate.

[0034]

[15] A printed circuit board comprising the laminate described in

[14] as a constituent element.

[0035] Invention Effects

[0036] According to the present invention, an adhesive composition exhibiting good appearance, excellent adhesion, and excellent low dielectric properties even after a long-term heat resistance test at 125°C for 1000 hours can be provided. Furthermore, the adhesive composition of the present invention also exhibits excellent solder heat resistance, adhesion, and initial low dielectric properties. Therefore, it is suitable for adhesive compositions for printed circuit boards in the high-frequency region, as well as adhesive sheets, laminates, and printed circuit boards comprising the present invention.

[0037] Methods of implementing the invention

[0038] <Adhesive Composition>

[0039] This invention relates to an adhesive composition comprising an acid-modified resin, an antioxidant (A), a heavy metal passivator (B), and an epoxy resin (C), wherein the content of the antioxidant (A) is 1.0 part by weight or less relative to 100 parts by weight of the acid-modified resin, and the content of the heavy metal passivator (B) is 1.0 part by weight or less. In this invention, by mixing the antioxidant (A) and the heavy metal passivator (B) in the adhesive composition and controlling their contents to below their respective specified amounts, the deterioration of the acid-modified resin due to oxidation can be suppressed, thereby providing an adhesive composition that exhibits good appearance, excellent adhesion, and excellent low dielectric properties even after a long-term heat resistance test at 125°C for 1000 hours.

[0040] <Acid-modified resin>

[0041] The acid-modified resin used in this invention is a resin modified with acid components. By using the acid-modified resin, excellent adhesion to metal substrates such as copper foil can be obtained, and by cross-linking with epoxy groups such as epoxy resin (C), an adhesive layer with excellent solder heat resistance can be formed.

[0042] The acid-modified resin used in this invention can be prepared, for example, by modifying the base resin with an unsaturated carboxylic acid component, or by copolymerizing the unsaturated carboxylic acid component during the polymerization of the base resin. The unsaturated carboxylic acid component is not particularly limited, but is preferably at least one of α,β-unsaturated carboxylic acids and their anhydrides, specifically including: acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, citraconic acid, maleic anhydride, itaconic anhydride, fumaric anhydride, citraconic anhydride, etc. Among these, maleic acid, itaconic acid, citraconic acid, and their anhydrides are preferred, more preferably anhydrides, and even more preferably maleic anhydride.

[0043] From the viewpoint of heat resistance and adhesion to resin or metal substrates, the lower limit of the acid value of the acid-modified resin used in this invention is preferably 10 equivalents / 10. 6 g or more, preferably 20 equivalents / 10 6 g or more, more preferably 30 equivalents / 10 6 g or higher. By setting the value to or above the lower limit mentioned above, compatibility with epoxy resins (C), etc., can be improved, bond strength can be increased, crosslinking density can be increased, and heat resistance can also be improved. The upper limit is preferably 1000 equivalents / 10 6 g or less, more preferably 700 equivalents / 10 6 g or less, more preferably 500 equivalents / 10 6 Below g. By setting it to a value below the above, better adhesion and low dielectric properties are achieved.

[0044] The weight-average molecular weight (Mw) of the acid-modified resin used in this invention is preferably in the range of 10,000 to 1,000,000. More preferably, it is in the range of 20,000 to 500,000; even more preferably, it is in the range of 40,000 to 200,000; and particularly preferably, it is in the range of 50,000 to 150,000. By setting it to the lower limit or above, good cohesion is achieved, and excellent adhesion is exhibited. Furthermore, by setting it to the upper limit or below, excellent flowability and good workability are achieved.

[0045] As the acid-modified resin used in this invention, from the perspective of good low dielectric properties, an acid-modified resin obtained by acid modification of a hydrocarbon-based resin is preferred. For example, a resin selected from one or more acid-modified polystyrene resins, acid-modified cyclic olefin polymers, and acid-modified polyolefins is preferred, and acid-modified polyolefins are more preferred. Furthermore, from the viewpoint of service life, acid-modified polystyrene resins and acid-modified cyclic olefin polymers are preferred. The acid-modified resin can be used alone or in combination of two or more.

[0046] The relative permittivity (εc) of the acid-modified resin of the present invention at a frequency of 80 GHz is preferably 2.7 or less. More preferably, it is 2.6 or less, and even more preferably, it is 2.3 or less. The lower limit is not particularly limited, but practically it is 2.0. In addition, the relative permittivity (εc) in the entire frequency range of 1 GHz to 80 GHz is preferably 2.7 or less, more preferably 2.6 or less, and even more preferably 2.3 or less.

[0047] The dielectric loss tangent (tanδ) of the acid-modified resin of the present invention at a frequency of 80 GHz is preferably 0.003 or less. More preferably, it is 0.0025 or less, and even more preferably, it is 0.002 or less. The lower limit is not particularly limited, but practically it is 0.0001 or more. In addition, the dielectric loss tangent (tanδ) in the entire frequency range of 1 GHz to 80 GHz is preferably 0.003 or less, more preferably 0.0025 or less, and even more preferably 0.002 or less.

[0048] Acid-modified resin is preferably included as the main component in the adhesive composition. In this specification, the main component in the adhesive composition specifically refers to the component with the highest content in the solid components of the adhesive composition. The content of acid-modified resin in the adhesive composition of the present invention is preferably 5% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, out of 100% by mass of the solid components of the adhesive composition. Furthermore, it is preferably 99.5% by mass or less, more preferably 99.0% by mass or less, and even more preferably 98.5% by mass or less. Within the above range, the adhesive properties and heat resistance are good, and therefore preferred.

[0049] <Acid-modified polyolefins>

[0050] In this invention, acid-modified polyolefins are preferably used as acid-modified resins. The acid-modified polyolefins used in this invention are not particularly limited, but are preferably obtained by grafting an unsaturated carboxylic acid component (preferably at least one of α,β-unsaturated carboxylic acids and their anhydrides) onto a polyolefin resin. Polyolefin resins refer to polymers with a hydrocarbon backbone, such as homopolymers of olefin monomers exemplified by ethylene, propylene, butene, butadiene, isoprene, etc., copolymers with other monomers, and hydrides or halides of the resulting polymers. Acid-modified polyolefins are preferably obtained by grafting at least one of α,β-unsaturated carboxylic acids and their anhydrides onto at least one of polyethylene, polypropylene, and propylene-α-olefin copolymers.

[0051] A propylene-α-olefin copolymer is a copolymer with propylene as the main component and α-olefins copolymerized thereon. Examples of α-olefins include ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, and vinyl acetate, which can be used alone or in combination of two or more. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of propylene to α-olefin in the propylene-α-olefin copolymer is not particularly limited, but a propylene content of 50 mol% or more is preferred, and more preferably 70 mol% or more. Furthermore, these raw materials can be not only petroleum-derived but also obtained using bio-naphtha or chemical recycling technologies from waste plastics.

[0052] As the unsaturated carboxylic acid component, at least one of α,β-unsaturated carboxylic acids and their anhydrides is preferred. Specific examples are as described above, such as maleic acid, itaconic acid, citraconic acid, and their anhydrides. Among these, anhydrides are preferred, and maleic anhydride is more preferred. That is, as the acid-modified polyolefin, specific examples include maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified propylene-ethylene-butene copolymer, etc., and these acid-modified polyolefins can be used alone or in combination of two or more.

[0053] From the viewpoint of heat resistance and adhesion to resin or metal substrates, the lower limit of the acid value of acid-modified polyolefins is preferably 89 equivalents / 10. 6 g or more, preferably 107 equivalents / 10 6 g or more, more preferably 125 equivalents / 10 6 g or higher. By setting it to the lower limit or higher, it exhibits good compatibility with epoxy resins, etc., and demonstrates excellent bond strength. Furthermore, it exhibits high crosslinking density and good solder heat resistance. The upper limit is preferably 713 equivalents / 10. 6 g or less, more preferably 534 equivalents / 10 6 g or less, more preferably 400 equivalents / 106 Below g. Good adhesion is achieved by setting the value below the aforementioned upper limit. Furthermore, the solution exhibits good viscosity and stability, demonstrating excellent pot life. Moreover, manufacturing efficiency is also improved.

[0054] The acid-modified polyolefin is preferably a crystalline acid-modified polyolefin. Crystallinity, as used in this invention, refers to the presence of a distinct melting peak during a temperature increase of 20°C / min from -100°C to 250°C using differential scanning calorimetry (DSC).

[0055] The melting point (Tm) of the acid-modified polyolefin is preferably in the range of 50°C to 120°C. More preferably, it is in the range of 60°C to 100°C, and most preferably, it is in the range of 70°C to 90°C. By setting it to the lower limit or above, the cohesive force from crystallization is good, resulting in excellent adhesion and solder heat resistance. In addition, by setting it to the upper limit or below, the solution stability and fluidity are excellent, and the workability during bonding is good.

[0056] The heat of fusion (ΔH) of the acid-modified polyolefin is preferably in the range of 5 J / g to 60 J / g. More preferably, it is in the range of 10 J / g to 50 J / g, and most preferably, it is in the range of 20 J / g to 40 J / g. By setting it to the lower limit or above, the cohesive force from crystallization is good, resulting in excellent adhesion and solder heat resistance. In addition, by setting it to the upper limit or below, the solution stability and fluidity are excellent, and the workability during bonding is good.

[0057] The weight-average molecular weight (Mw) of the acid-modified polyolefin is preferably in the range of 10,000 to 500,000. More preferably, it is in the range of 20,000 to 400,000; even more preferably, it is in the range of 40,000 to 200,000; and particularly preferably, it is in the range of 50,000 to 100,000. By setting it to the lower limit or above, good cohesiveness is achieved, and excellent adhesion is exhibited. Furthermore, by setting it to the upper limit or below, excellent flowability and good workability are achieved.

[0058] There are no particular limitations on the manufacturing method of acid-modified polyolefins. Examples include free radical grafting reaction (i.e., a reaction in which a free radical species is generated relative to the polymer as the main chain, and the unsaturated carboxylic acid component (preferably α,β-unsaturated carboxylic acid and its anhydride) is grafted onto the polymer using the free radical species as the polymerization starting point).

[0059] <Acid-modified polystyrene resin>

[0060] In this invention, acid-modified polystyrene resin is preferably used as the acid-modified resin. The acid-modified polystyrene resin is not particularly limited, but is preferably a resin modified with an unsaturated carboxylic acid component using copolymers and their hydrides, primarily composed of aromatic vinyl compounds alone or in a block and / or random structure of aromatic vinyl compounds and conjugated diene compounds. The aromatic vinyl compounds are not particularly limited, but examples include styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, p-tert-butylstyrene, etc. Conjugated diene compounds include, for example, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. Furthermore, these raw materials can be not only petroleum-derived but also obtained using bio-naphtha or chemical recycling technologies from waste plastics. Specific examples of copolymers of these aromatic vinyl compounds and conjugated diene compounds include: styrene-butadiene block copolymers, styrene-ethylene-butene-styrene block copolymers (SEBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), and styrene-ethylene-ethylene / propylene-styrene block copolymers (SEEPS). As the unsaturated carboxylic acid component, at least one of α,β-unsaturated carboxylic acids and their anhydrides is preferred. Specific examples are as described above, such as maleic acid, itaconic acid, citraconic acid, and their anhydrides. Among these, anhydrides are preferred, and maleic anhydride is more preferred.

[0061] From the viewpoint of heat resistance and adhesion to resin or metal substrates, the lower limit of the acid value of acid-modified polystyrene resin is preferably 10 equivalents / 10 6 g or more, preferably 20 equivalents / 10 6 g or more, more preferably 50 equivalents / 10 6 g or higher. By setting it to the lower limit or higher, compatibility with epoxy resins, etc., becomes good, and excellent bond strength can be exhibited. In addition, the crosslinking density becomes higher, and the heat resistance of the solder becomes better. The upper limit is preferably 500 equivalents / 10 6 Below g, more preferably 400 equivalents / 10 6 g or less, more preferably 300 equivalents / 10 6 Below g. By setting it below the aforementioned upper limit, adhesion becomes good. Furthermore, the viscosity and stability of the solution become good, exhibiting excellent pot life. Moreover, manufacturing efficiency is also improved.

[0062] <Acid-Modified Cycloolefin Polymers>

[0063] In this invention, an acid-modified cyclic olefin polymer is preferably used as the acid-modified resin. The acid-modified cyclic olefin polymer is a polymer obtained by modifying a cyclic olefin polymer with an unsaturated carboxylic acid component to introduce carboxyl groups. As the cyclic olefin polymer, either a homopolymer (COP) prepared from only one cyclic olefin monomer, or a copolymer (COC) composed of one or more cyclic olefin monomers and comonomers, can be used. Furthermore, as the unsaturated carboxylic acid component, at least one of α,β-unsaturated carboxylic acids and their anhydrides is preferred. Specific examples are as described above, such as maleic acid, itaconic acid, citraconic acid, and their anhydrides. Among these, anhydrides are preferred, and maleic anhydride is more preferred.

[0064] Examples of the cyclic olefin monomers include: dicyclic monomers such as norbornene and norbornadiene; tricyclic monomers such as dicyclopentadiene and dihydrodicyclopentadiene; tetracyclic monomers such as tetracyclododecene; pentacyclic monomers such as cyclopentadiene trimer; heptacyclic monomers such as tetracyclopentadiene; or alkyl (methyl, ethyl, propyl, butyl, etc.) substituted derivatives, alkenyl (vinyl, etc.) substituted derivatives, alkylene (ethylene, etc.) substituted derivatives, aryl (phenyl, tolyl, naphthyl, etc.) substituted derivatives of these polycyclic monomers. Among these, norbornene monomers selected from norbornene, tetracyclododecene, or their alkyl-substituted derivatives are particularly preferred. Furthermore, these raw materials can be not only petroleum-derived raw materials, but also raw materials obtained using chemical recycling technologies utilizing bio-naphtha or waste plastics.

[0065] Furthermore, any monomer capable of copolymerizing with the aforementioned cyclic olefin monomers is acceptable; olefin monomers are preferred, for example. Examples of olefin monomers include α-olefins such as ethylene, propylene, 1-butene, and 1-hexene, as well as isobutene. The olefin monomer can be linear or branched.

[0066] In the monomer components constituting the acid-modified cyclic olefin polymer, preferably 50% or more by mass is the cyclic olefin monomer, more preferably 60% or more by mass is the cyclic olefin monomer. When the cyclic olefin monomer accounts for more than 50% by mass of the total monomer components, the solder heat resistance becomes good. There are no particular restrictions on the polymerization method, polymerization conditions, etc., when polymerizing the monomer components; they can be appropriately set according to conventional methods.

[0067] The weight-average molecular weight (Mw) of the acid-modified cyclic olefin polymer is preferably in the range of 10,000 to 500,000. More preferably, it is in the range of 20,000 to 400,000; even more preferably, it is in the range of 40,000 to 200,000; and particularly preferably, it is in the range of 50,000 to 100,000. By setting it to the lower limit or above, the cohesive strength becomes good, and excellent adhesion can be exhibited. In addition, by setting it to the upper limit or below, the flowability is excellent, and the workability becomes good.

[0068] From the viewpoint of heat resistance and adhesion to resin or metal substrates, the lower limit of the acid value of acid-modified cyclic olefin polymers is preferably 89 equivalents / 10. 6 g or more, preferably 107 equivalents / 10 6 g or more, more preferably 125 equivalents / 10 6 g or higher. By setting the value to the lower limit or higher, the compatibility with epoxy resin becomes good, and excellent bond strength can be exhibited. Furthermore, the high crosslinking density results in good solder heat resistance. The upper limit is preferably 713 equivalents / 10 6 g or less, more preferably 534 equivalents / 10 6 g or less, more preferably 356 equivalents / 10 6 Below g. By setting it below the aforementioned upper limit, adhesion becomes good. Furthermore, the viscosity and stability of the solution become good, exhibiting excellent pot life. Moreover, manufacturing efficiency is also improved.

[0069] <Antioxidant (A)>

[0070] The adhesive composition of the present invention contains an antioxidant (A). By containing antioxidant (A), the thermal degradation of acid-modified resin can be suppressed even in high-temperature environments in the presence of oxygen, and changes in adhesiveness and low dielectric properties can be suppressed after long-term heat resistance tests.

[0071] As an antioxidant (A), there are no particular limitations as long as it can inhibit the thermal degradation of acid-modified resins. Examples include phenolic antioxidants, sulfur-based antioxidants, amine-based antioxidants, and phosphorus-based antioxidants. They can be used alone or in combination of two or more.

[0072] Examples of phenolic antioxidants include: 2,4,8,10-tetraoxazaspiro[5.5]undecane-3,9-diyl)bis(2-methylpropane-2,1-diyl)=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], 2,6-di-tert-butyl-p-cresol, 2,4,6-tri-tert-butylphenol, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene glycol bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate], 2,6-di-tert-butyl-4-hydroxymethylphenol, 2,5-di-tert-butylhydroquinone, 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl ... Methylbis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(4-methyl-6-nonylphenol), 4,4'-isopropylidenebisphenol, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenol), 1,1-bis-(4-hydroxy-phenyl)cyclohexane, 4,4'-methylenebis(2,6-di-tert-butylphenol), 2,6-bis(2'-hydroxy-3'-tert-butyl-5'-methylbenzyl)-4-methylphenol, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butyl-phenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetra[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc.

[0073] Examples of sulfur-based antioxidants include: pentaerythritol tetra(3-lauryl thiopropionate), dilauryl thiopropionate, dimyristyl thiopropionate, distearate thiopropionate, and bis(2-hydroxy-1-naphthyl) sulfides.

[0074] Examples of amine-based antioxidants include: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, aldol-α-naphthylamine, polymers of 2,2,4-trimethyl-1,2-dihydroquinoline, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline.

[0075] Examples of phosphorus-based antioxidants include: 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide, triphenyl phosphite, 2-ethylhexyl phosphate, dilauryl phosphite, triisooctyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, trilauryl phosphite, dithiotrilauryl phosphite, trithiotrilauryl phosphite, trinonylphenyl phosphite, distearate pentaerythritol diphosphite, tri(mononylphenyl) phosphite, tri(dinonylphenyl) phosphite, tri(octadecyl) phosphite, 1,1,3-tris(2-methyl-di-tetrazylphosphite-5-tert-butylphenyl)butane, and 4,4'-butylene-bis(3-methyl-6-tert-butylphenyl)phosphite. Butyl)tridecyl phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butyl-di-tridecyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, tetra(2,4-di-tert-butylphenyl)4,4'-biphenylene diphosphite, distearate pentaerythritol diphosphite, tridecyl phosphite, tristearate phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, sorbitol-tri-phosphite-distearate-mono-C30-diol ester, bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, etc.

[0076] From the viewpoint of long-term heat resistance, antioxidant (A) preferably includes at least one of phenolic antioxidants and sulfur-based antioxidants, and more preferably includes both phenolic antioxidants and sulfur-based antioxidants.

[0077] As an antioxidant (A) (preferably a phenolic antioxidant), it is preferable to have an antioxidant having a chemical structure represented by formula (I) within the molecule.

[0078] 【Transformation 3】

[0079]

[0080] In equation (I), * represents the bonding site, R 1 ~R 3 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.]

[0081] R 1 ~R 3 C in 1-10 Alkyl (-C) n H 2n+1 (where n represents an integer from 1 to 10) can be linear or branched, preferably C 1-6 Alkyl, more preferably C 1-4Alkyl groups, more preferably methyl, ethyl, or tert-butyl. From the viewpoint of suppressing the deterioration of acid-modified resins, in R... 1 ~R 3 In, R is preferred 1 ~R 2 For hydrogen atoms, R 3 C 1-10 Alkyl group.

[0082] The content of antioxidant (A) relative to 100 parts by weight of acid-modified resin is preferably 1.0 parts by weight or less, more preferably 0.9 parts by weight or less, even more preferably 0.8 parts by weight or less, and even more preferably 0.7 parts by weight or less. If the above upper limit is exceeded, the dielectric properties after long-term heat resistance testing may deteriorate. The content of antioxidant (A) relative to 100 parts by weight of acid-modified resin is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more. If it is above the above lower limit, the deterioration of acid-modified resin due to oxidation can be suppressed, and the adhesive composition can exhibit a good appearance even after long-term heat resistance testing, and perform excellent adhesion and excellent low dielectric properties.

[0083] <Heavy Metal Passivating Agent (B)>

[0084] The adhesive composition of the present invention contains a heavy metal passivator (B). In a high-temperature environment in the presence of oxygen, regardless of humidity conditions, heavy metal ions such as copper ions are generated from the metal substrate, such as copper foil, which comes into contact with the adhesive composition. These heavy metal ions promote the oxidation of the acid-modified resin, leading to its thermal degradation. Since the heavy metal passivator (B) can capture the generated copper ions, the thermal degradation of the acid-modified resin can be suppressed by mixing it with the adhesive.

[0085] As a heavy metal passivating agent (B), there are no particular limitations as long as it can capture heavy metal ions; for example, any substance that can form a chelate with heavy metal ions is acceptable. Examples of heavy metal passivating agents (B) include hydrazine-based, phosphite-based, diacid-based, amino acid-based, and triazole-based heavy metal passivating agents. They can be used alone or in combination of two or more.

[0086] Hydrazine-based heavy metal passivating agents refer to heavy metal passivating agents that have a hydrazine structure (*-NH-NH-*) within the molecule. Hydrazine-based heavy metal passivating agents include hydrazine derivatives and substances obtained by dehydration condensation of hydrazine derivatives with oxyacids. Specific examples include: N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, 1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine, bis(2-phenoxypropionylhydrazine) isophthalic acid, bis(salicylic acid hydrazine), dodecanoic acid disalicylic acid hydrazine, bis(2-phenoxypropionylhydrazine) isophthalic acid, N'1,N'12-bis(2-hydroxybenzoyl)dodecanoic acid hydrazine, dodecanoic acid-bis(N'-salicylic acid hydrazine), oxalic acid-bis(benzylidene hydrazine), thiodipropionate-bis(benzylidene hydrazine), isophthalic acid-bis(2-phenoxypropionylhydrazine), etc.

[0087] Examples of phosphite-based heavy metal passivating agents include: the reaction product of 2,2'-di-tert-butyl-5,5'-dimethyl-4,4'-thiodiphenol and phosphorus trichloride, bis[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'-tert-butylphenyl)-5-methylphenyl]-pentaerythritol diphosphite, tetra[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'-tert-butylphenyl)-5-methylphenyl]-1,6-hexamethylene-bis(N-hydroxyethyl-N-methylaminourea)-diphosphite, and tetra[2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5'-tert-butylphenyl)-5-methylphenyl]-N,N'-bis(hydroxyethyl)oxalamide-diphosphite, etc.

[0088] Examples of diacid-based heavy metal passivating agents include ethylenediaminetetraacetic acid (EDTA).

[0089] Examples of amino acid-based heavy metal passivating agents include: 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, N,N-diethyl-N',N'-diphenyloxamide, N,N'-diethyl-N,N'-diphenyloxamide, N,N'-bis[2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl]oxamide, 2,4,6-triamino-1,3,5-triazine, and 3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, etc.

[0090] Examples of triazole-based heavy metal passivating agents include benzotriazole and 3-salicylic acid-1,2,4-triazole.

[0091] From the viewpoint of low dielectric properties and long-term heat resistance, the heavy metal passivating agent (B) is more preferably composed of at least one of hydrazine-based heavy metal passivating agents and phosphite-based heavy metal passivating agents, and more preferably a hydrazine-based heavy metal passivating agent.

[0092] As a heavy metal passivating agent (B) (preferably a hydrazine-based heavy metal passivating agent), it is also preferred to have a passivating agent having a chemical structure represented by formula (II) within the molecule.

[0093] 【Chemistry 4】

[0094]

[0095] In equation (II), * represents the bonding site, R 4 ~R 6 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.]

[0096] R 4 ~R 6 C in 1-10 Alkyl (-C) n H 2n+1 (where n represents an integer from 1 to 10) can be linear or branched, preferably C 1-6 Alkyl, more preferably C 1-4 Alkyl groups, more preferably methyl, ethyl, or tert-butyl. From the viewpoint of suppressing the deterioration of acid-modified resins, in R... 4 ~R 6 In, R is preferred 4 It is a hydrogen atom, and R 5 ~R 6 Either of them is C 1-10 Alkyl groups, or hydrogen atoms in the other form.

[0097] The content of the heavy metal passivating agent (B) relative to 100 parts by weight of the acid-modified resin is preferably 1.0 parts by weight or less, more preferably 0.9 parts by weight or less, even more preferably 0.8 parts by weight or less, and even more preferably 0.7 parts by weight or less. If the above upper limit is exceeded, the dielectric properties after long-term heat resistance testing may deteriorate. The content of the heavy metal passivating agent (B) relative to 100 parts by weight of the acid-modified resin is preferably 0.01 parts by weight or more, more preferably 0.04 parts by weight or more, and even more preferably 0.08 parts by weight or more. If it is above the above lower limit, the degradation of the adhesive composition, especially the acid-modified resin, due to oxidation can be suppressed, and even after long-term heat resistance testing, it can exhibit a good appearance and excellent adhesion and excellent low dielectric properties.

[0098] The content of the heavy metal passivating agent (B) relative to 100 parts by weight of the antioxidant (A) is preferably 1 to 200 parts by weight, more preferably 5 to 100 parts by weight, further preferably 10 to 70 parts by weight, and even more preferably 13 to 50 parts by weight. By adjusting to the above range, the adhesive composition can exhibit excellent low dielectric properties even after long-term heat resistance testing.

[0099] <Epoxy Resin (C)>

[0100] The adhesive composition of the present invention contains an epoxy resin. As for the epoxy resin, there is no particular limitation as long as it is a multifunctional epoxy resin having two or more glycidyl groups within its molecule. By using the epoxy resin, the carboxyl groups of the acid-modified resin react with the glycidyl groups to form a cross-linked structure, thereby improving the solder heat resistance and adhesion of the adhesive composition.

[0101] From the viewpoint of heat resistance and adhesion to resin or metal substrates, the epoxy value of epoxy resin (C) is preferably 5,000 to 12,000 equivalents / 10. 6 g, more preferably 6,000 to 11,000 equivalents / 10 6 g, more preferably 7,000 to 10,000 equivalents / 10 6 g. By setting the value above the lower limit mentioned above, the bond strength is improved, the crosslinking density increases, and the heat resistance is also improved. By setting the value below the upper limit mentioned above, the adhesion and low dielectric properties become better. In addition, the epoxy value can be evaluated based on the specifications of JIS K7236 (the same applies below).

[0102] The epoxy resin (C) is not particularly limited, but examples include: biphenyl-type epoxy resin, naphthalene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, phenolic varnish-type epoxy resin, dicyclopentadiene-type epoxy resin, glycidyl amine-type epoxy resin, glycidyl ether-type epoxy resin, epoxy-modified polybutadiene, and isocyanuric acid containing glycidyl groups. These can be used alone or in combination of two or more. From the viewpoint of solder heat resistance and low dielectric properties, glycidyl amine-type epoxy resin and isocyanuric acid containing glycidyl groups are preferred, and glycidyl amine-type epoxy resin is more preferred.

[0103] Glycidylamine type epoxy resins specifically refer to epoxy resins containing glycidylamine groups within their molecules, wherein the glycidylamine group is formed by the combination of one or two glycidyl groups with an amino group. More preferably, the epoxy resins include at least one of the epoxy resins represented by formula (CA) (hereinafter, sometimes simply referred to as epoxy resin (CA)) and the epoxy resins represented by formula (CB) (hereinafter, sometimes simply referred to as epoxy resin (CB)). Since epoxy resins (CA) to (CB) have two or more epoxy groups, it is advantageous to form a high-density cross-linked structure. Furthermore, in epoxy resins (CA) to (CB), the number of carbon atoms between the nitrogen atom and the epoxy group indirectly bonded thereto is relatively small, thus epoxy resins (CA) to (CB) have greater steric hindrance and are structures with poor mobility. Such a sterically hindrance structure can suppress atomic movement, and is therefore most suitable for obtaining adhesive compositions with low dielectric loss tangents.

[0104] 【Transformation 5】

[0105]

[0106] In formula (CA), R 11 ~R 15 Each independently represents a hydrogen atom and a carbon atom. 1-10 Alkyl or glycidoxy.

[0107] 【Transformation 6】

[0108]

[0109] In formula (CB),

[0110] R 16 ~R 23 Each independently represents a hydrogen atom and a carbon atom. 1-10 Alkyl or glycidoxy.

[0111] R 24 ~R 25 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.]

[0112] R 11 ~R 25 C in 1-10 Alkyl (-C) n H 2n+1 , where n represents an integer from 1 to 10, can be linear or branched. The C 1-10 Alkyl groups are preferably C 1-6 Alkyl, more preferably C 1-3 Alkyl, more preferably methyl or ethyl.

[0113] In formula (CA), R is preferred.11 and R 15 At least one of them is C 1-10 Alkyl group. If R 11 and R 15 At least one of them is C 1-10 Alkyl groups, on the other hand, act as steric hindrances, hindering the movement of polar groups, and are therefore effective for obtaining adhesive compositions with low dielectric loss tangents. Additionally, in R... 11 ~R 15 In the middle, when R 11 and R 15 At least one of them is C 1-10 When alkyl, it is preferable to remove the C. 1-10 Groups other than alkyl groups are hydrogen atoms.

[0114] In equation (CB), R 16 ~R 23 Preferably, 3 or more are hydrogen atoms, more preferably 5 or more are hydrogen atoms, even more preferably 7 or more are hydrogen atoms, and most preferably all 8 are hydrogen atoms.

[0115] R 24 ~R 25 In the presence of hydrogen atoms, preferably at least one is a hydrogen atom, and more preferably both are hydrogen atoms.

[0116] Preferred glycidylamine type epoxy resins include: N,N-diglycidylaniline, N,N-(diglycidyl)-o-toluidine, N,N-(diglycidyl)-m-toluidine, N,N-(diglycidyl)-p-toluidine, N,N-diglycidyl-4-glycidoxyaniline, N,N-(diglycidyl)-4-glycidoxy-o-toluidine, and N,N-(diglycidyl)- 4-Glycidyloxy-m-toluidine, N,N-(diglycidyl)-4-glycidyloxy-p-toluidine, 4,4'-methylenebis(N,N-diglycidylaniline), more preferably N,N-(diglycidyl)-o-toluidine, N,N-(diglycidyl)-m-toluidine, N,N-(diglycidyl)-p-toluidine, 4,4'-methylenebis(N,N-diglycidylaniline).

[0117] The content of epoxy resin (C) relative to 100 parts by weight of acid-modified resin is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and even more preferably 1 part by weight or more. By setting it to the lower limit or above, sufficient curing effect can be obtained, and excellent adhesion and solder heat resistance can be exhibited. In addition, it is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and even more preferably 6 parts by weight or less. By setting it to the upper limit or below, pot life and low dielectric properties become good.

[0118] <Polycarbodiimide>

[0119] The adhesive composition of the present invention may contain polycarbodiimide. There are no particular limitations on the polycarbodiimide, as long as it has two or more carbodiimide bonds within its molecule. By using polycarbodiimide, the carboxyl groups of the acid-modified resin or the epoxy groups of the epoxy resin react with the carbodiimide bonds, thereby improving heat resistance and adhesion.

[0120] In the adhesive composition of the present invention, the content of polycarbodiimide is preferably 1 part by weight or more, more preferably 3 parts by weight or more, relative to 100 parts by weight of acid-modified resin. By setting it to the lower limit value or above, the crosslinking density can be increased, resulting in good solder heat resistance. Furthermore, it is preferably 20 parts by weight or less, more preferably 10 parts by weight or less. By setting it to the upper limit value or below, excellent solder heat resistance and low dielectric properties can be exhibited. That is, by setting it within the above range, an adhesive composition with excellent solder heat resistance and low dielectric properties can be obtained.

[0121] <Unsaturated hydrocarbons>

[0122] The adhesive composition of the present invention may contain unsaturated hydrocarbons having terminal unsaturated hydrocarbon groups and a 5% weight reduction temperature of 260°C or higher. By containing unsaturated hydrocarbons, since the unsaturated hydrocarbons have terminal unsaturated hydrocarbon groups, the crosslinking density can be increased and the heat resistance of the solder can be improved through a curing reaction based on free radicals generated using free radical initiators or the like. Furthermore, since no hydroxyl groups that would degrade dielectric properties are generated after the reaction, an adhesive with superior dielectric properties can be obtained. From the viewpoint of further improving the crosslinking density, it is preferable to have two or more terminal unsaturated hydrocarbon groups per molecule.

[0123] The 5% weight reduction temperature for unsaturated hydrocarbons needs to be 260°C or higher. Preferably, it is 270°C or higher, more preferably 280°C or higher, and even more preferably 290°C or higher. By setting the 5% weight reduction temperature to the above values ​​or higher, welding will not produce appearance defects even when performed at temperatures exceeding the solder melting point. There is no particular upper limit, but 500°C is a practical value.

[0124] The unsaturated hydrocarbon preferably has an aromatic ring structure or an alicyclic structure as its structural unit. Using an aromatic ring structure or an alicyclic structure as the structural unit improves the heat resistance of the solder and also provides excellent dielectric properties. Among these, an aromatic ring structure or an alicyclic structure is preferred as the backbone of the unsaturated hydrocarbon, and polyphenylene ether or cyclic olefin polymers are preferred. Specific examples of polyphenylene ethers with terminal unsaturated hydrocarbon groups include SABIC's SA-9000 and Mitsubishi Gas Chemical's OPE-2St. Furthermore, cyclic olefin polymers with terminal unsaturated hydrocarbon groups can be obtained by copolymerizing olefin monomers with unsaturated bonds and alicyclic olefin monomers.

[0125] The number average molecular weight of the unsaturated hydrocarbon is preferably 500 or more, more preferably 1000 or more. Furthermore, it is preferably 100,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less. Within the above ranges, it exhibits good solubility in solvents and is able to form a uniform adhesive coating.

[0126] The content of unsaturated hydrocarbons in the adhesive composition of the present invention is preferably 1 part by weight or more, more preferably 2 parts by weight or more, relative to 100 parts by weight of acid-modified resin. Furthermore, it is preferably 1000 parts by weight or less, more preferably 500 parts by weight or less, further preferably 200 parts by weight or less, and even more preferably 100 parts by weight or less. When a polyphenylene ether having terminal unsaturated hydrocarbon groups is used as the unsaturated hydrocarbon, it is preferably 200 parts by weight or less, more preferably 100 parts by weight or less, relative to 100 parts by weight of acid-modified resin. Within the above ranges, excellent adhesion, compatibility with organic solvents, and solder heat resistance can be achieved.

[0127] <Free radical initiators>

[0128] The adhesive composition of the present invention may contain a free radical initiator. The free radicals generated by the free radical initiator enable efficient reactions between the terminal unsaturated hydrocarbon groups of the unsaturated hydrocarbon, increasing the crosslinking density and thereby improving the heat resistance and dielectric properties of the solder. There are no particular limitations on the free radical initiator, but organic peroxides are preferred. Examples of organic peroxides include: di-tert-butyl phthalate peroxide, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypentanoate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauroyl peroxide, etc.; and azo nitrile compounds such as azobisisobutyronitrile and azobisisovalerate.

[0129] The half-life temperature of the free radical initiator used in this invention is preferably 140°C or higher. By setting it to 140°C or higher, the initiation of the free radical reaction can be prevented when the solvent in the adhesive composition varnish is evaporated to prepare the adhesive sheet, thereby enabling excellent adhesion.

[0130] The amount of the free radical initiator used in this invention is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of unsaturated hydrocarbons. Furthermore, it is preferably 50 parts by mass or less, more preferably 10 parts by mass or less. By setting it within the above range, an optimal crosslinking density can be obtained, achieving a balance between adhesion and solder heat resistance.

[0131] <Organic Solvents>

[0132] The adhesive composition of the present invention may further contain an organic solvent. The organic solvent used in the present invention is not particularly limited as long as it can dissolve the acid-modified resin, antioxidant (A), and heavy metal passivator (B). When the adhesive composition of the present invention contains an organic solvent, it is preferable that the acid-modified resin, antioxidant (A), and heavy metal passivator (B) are uniformly dissolved in the organic solvent.

[0133] Specific examples of organic solvents include: aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane; halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform; alcohol solvents such as methanol, ethanol, isopropanol, butanol, pentanol, hexanol, propylene glycol, and phenol; and acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanol, hexanone, cyclohexanone, and isobutyl ketone. Ketone solvents such as phenone and acetophenone; cellosolvers such as methyl and ethyl cellosolves; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and butyl formate; and glycol ether solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-isobutyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-isobutyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether, can be used alone or in combination of two or more. Especially considering the working environment and drying properties, methyl ethyl ketone, methyl cyclohexane, or toluene are preferred.

[0134] The organic solvent is preferably in the range of 100 to 1000 parts by weight relative to 100 parts by weight of the solid component of the adhesive composition. Setting it to the lower limit or above results in good liquid properties and pot life. Furthermore, setting it to the upper limit or below is advantageous in terms of manufacturing and transportation costs.

[0135] Furthermore, the adhesive composition of the present invention may further contain other components as needed. Specific examples of such components include: flame retardants, tackifiers, fillers, antioxidants, silane coupling agents, etc.

[0136] <Flame retardant>

[0137] The adhesive composition of the present invention can be formulated with flame retardants as needed. Examples of flame retardants include bromine-based, phosphorus-based, nitrogen-based, and metal hydroxides. Among these, phosphorus-based flame retardants are preferred, and phosphorus-based flame retardants such as phosphate esters, phosphates, and phosphine oxides can be used. They can be used alone or in combination of two or more. When containing flame retardants, it is preferable that the flame retardant is present in the range of 1 to 70% by mass of 100% by mass of the solid components of the adhesive composition, more preferably in the range of 5 to 60% by mass, and most preferably in the range of 10 to 50% by mass. By setting it within the above range, flame retardancy can be exhibited while maintaining adhesion, solder heat resistance, and electrical properties.

[0138] <Tackifier>

[0139] The adhesive composition of the present invention can be mixed with a tackifier as needed. Examples of tackifiers include polyterpene resins, rosin-based resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymer petroleum resins, styrene resins, and hydrogenated petroleum resins, which are used to improve adhesive strength. They can be used alone or in combination of two or more. When a tackifier is included, it is preferable that the tackifier is present in the range of 1 to 70% by mass of 100% by mass of the solid components of the adhesive composition, more preferably in the range of 5 to 60% by mass, and most preferably in the range of 10 to 50% by mass. By setting it within the above range, the effect of the tackifier can be achieved while maintaining adhesion, solder heat resistance, and electrical properties.

[0140] <Packaging>

[0141] The adhesive composition of the present invention can be mixed with fillers as needed. Examples of organic fillers include powders of heat-resistant resins such as polyimide, polyamide-imide, fluororesin, and liquid crystal polyester. Examples of inorganic fillers include, for instance, silica (SiO2), alumina (Al2O3), titanium dioxide (TiO2), tantalum oxide (Ta2O5), zirconium oxide (ZrO2), silicon nitride (Si3N4), boron nitride (BN), calcium carbonate (CaCO3), calcium sulfate (CaSO4), zinc oxide (ZnO), magnesium titanate (MgO·TiO2), barium sulfate (BaSO4), organobentonite, clay, mica, aluminum hydroxide, and magnesium hydroxide. Silica is preferred from the perspective of ease of dispersion and improved heat resistance.

[0142] As silica, hydrophobic silica and hydrophilic silica are generally known. Here, in order to impart moisture resistance, hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc., is preferred. When silica is mixed, its mixing amount is preferably 1 to 50% by mass of 100% by mass of the solid content of the adhesive composition, more preferably 30 to 50% by mass. By setting it to the lower limit or above, further heat resistance can be exhibited. In addition, by setting it to the upper limit or below, poor dispersion of silica or excessively high solution viscosity can be suppressed, resulting in good workability.

[0143] Furthermore, from the viewpoint of long-term heat resistance, it is preferable to have a low content of magnesium hydroxide. The content of magnesium hydroxide, relative to 100 parts by weight of acid-modified resin, is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, further preferably 3 parts by weight or less, even more preferably 0.5 parts by weight or less, and most preferably 0 parts by weight.

[0144] <Silane Coupling Agent>

[0145] The adhesive composition of the present invention can also be mixed with silane coupling agents as needed. The properties such as adhesion to metals and heat resistance are improved by mixing with silane coupling agents, making it highly preferred. There are no particular limitations on the silane coupling agent; examples include silane coupling agents having unsaturated groups, silane coupling agents having epoxy groups, and silane coupling agents having amino groups. From the viewpoint of heat resistance, silane coupling agents having epoxy groups, such as γ-epoxypropoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, are more preferred. When mixing with silane coupling agents, the mixing amount is preferably 0.5 to 20% by mass of the solid components of the adhesive composition. By setting it within the above range, the heat resistance and adhesion of the solder can be improved.

[0146] <Long-term heat resistance>

[0147] The adhesive composition of the present invention exhibits excellent low dielectric properties even after a long-term heat resistance test at 125°C for 1000 hours. For example, the cured product obtained by heating and curing the adhesive composition of the present invention at 180°C for 90 minutes, after being exposed to air at 125°C for 1000 hours, and then measured under conditions of 23°C, 50% humidity, and 80GHz, preferably has a dielectric loss tangent (tanδ) of 0.0015 or less, more preferably 0.0014 or less, and even more preferably 0.0013 or less. For details regarding the measurement method, please refer to the "(relative permittivity (ε)" section in the Examples column. r(and dielectric loss tangent (tanδ)). In this invention, due to the use of acid-modified resin, it is easier to maintain low dielectric properties after long-term heat resistance testing compared to adhesive compositions based on epoxy resin.

[0148] The adhesive composition of the present invention exhibits excellent adhesion even after a long-term heat resistance test at 125°C for 1000 hours. For example, the peel strength of the cured product obtained by heating and curing the adhesive composition of the present invention at 180°C for 90 minutes and then exposing it to air at 125°C for 1000 hours is preferably 0.5 N / mm or more, more preferably 1.0 N / mm or more, and even more preferably 1.2 N / mm or more, with no particular upper limit, but 5 N / mm. For details on the test method, please refer to the section "(High Temperature and High Humidity Resistance)" in the Examples section.

[0149] <Layered Body>

[0150] In this invention, a laminate refers to a laminate on a substrate in which the adhesive composition of this invention is laminated. Specifically, it is a laminate on a substrate (a two-layer laminate of substrate / adhesive layer), or a laminate further bonded to a substrate (a three-layer laminate of substrate / adhesive layer / substrate). Here, the adhesive layer refers to a layer of the adhesive composition after it has been applied to a substrate and dried. The laminate of this invention can be obtained by applying the adhesive composition of this invention to various substrates using conventional methods, drying it, and further laminating it with other substrates.

[0151] The laminates of the present invention include: laminates on a substrate of resin substrate, metal substrate, paper or inorganic non-metallic substrate (described later), on which the adhesive composition of the present invention is laminated; and laminates (adhesive sheets) on a release substrate on which the adhesive composition of the present invention is laminated. Examples of the laminates of the present invention include: copper-clad laminates (CCL), resin-coated metal foils, cover films, adhesive sheets, etc.

[0152] <Substrate>

[0153] The substrate used in this invention is not particularly limited as long as it can be coated with the adhesive composition of this invention, dried, and form an adhesive layer. Examples include: resin substrates such as film resins; metal substrates such as metal plates and metal foils; paper; inorganic non-metallic substrates; and release substrates.

[0154] Examples of resin substrate materials include: epoxy resin, polyester resin, polyamide resin, aramid resin, polyimide resin, polyamide-imide resin, liquid crystal polymer, polyphenylene sulfide, polyphenylene ether, polyethersulfone, polyetheretherketone, polycarbonate, polyarylate, syndiotactic polystyrene, polyolefin resin, fluorinated resin, etc. The form of the resin substrate is not particularly limited; examples include films made of the above resins and glass cloth (FR-4) impregnated with the above resins. The above resins may contain fillers such as silica.

[0155] As the metal substrate, any known conductive material suitable for circuit boards can be used. Examples of materials include various metals such as SUS, copper, aluminum, iron, stainless steel, zinc, and nickel, as well as their alloys, electroplated products, and metals treated with zinc or chromium compounds. Metal foil is preferred, and copper foil is more preferred. The thickness of the metal foil is not particularly limited, but it is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 10 μm or more. Furthermore, it is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit; on the other hand, if the thickness is too thick, the processing efficiency during circuit fabrication may be reduced. The metal foil is usually provided in roll form. The form of the metal foil used in manufacturing the printed circuit board of the present invention is not particularly limited. When using a strip-shaped metal foil, its length is not particularly limited. Furthermore, its width is not particularly limited, but it is preferably about 250 to 500 cm. The surface roughness of the substrate is not particularly limited, but it is preferably 3 μm or less, more preferably 2 μm or less, and even more preferably 1.5 μm or less. In addition, practically, it is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more.

[0156] Examples of paper products include: premium paper, kraft paper, roll paper, glassine paper, etc.

[0157] Examples of inorganic non-metallic substrates include glass and ceramics.

[0158] There are no particular limitations on the type of release material. Examples include: a release material consisting of a coating layer of clay, polyethylene, polypropylene, or other pore-filling agents applied to both sides of high-quality paper, kraft paper, roll paper, glassine paper, etc., and then coated with a silicone-based, fluorine-based, or alkyd-based release agent. Additionally, examples include: various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer, as well as release materials consisting of films such as polyethylene terephthalate coated with the aforementioned release agents.

[0159] In this invention, the method for coating the adhesive composition onto the substrate is not particularly limited, and examples include comma coating machines, reverse roller coating machines, and die-coating machines. Alternatively, depending on the requirements, the adhesive layer can be applied directly or by transfer onto rolled copper foil, which is a component material of the printed circuit board, or the aforementioned resin substrate. The thickness of the dried adhesive layer can be appropriately varied as needed, but is preferably in the range of 5 to 200 μm. By making the adhesive film thickness 5 μm or more, sufficient adhesive strength can be obtained. In addition, by making it 200 μm or less, the amount of residual solvent in the drying process is easily controlled, and bubbling is less likely to occur during pressing in the manufacturing of the printed circuit board. The drying conditions are not particularly limited, but the residual solvent rate after drying is preferably 1% by mass or less. By making it 1% by mass or less, residual solvent foaming during the pressing of the printed circuit board can be suppressed, and bubbling is less likely to occur.

[0160] <Copper Clad Laminates (CCL)>

[0161] In this invention, a copper-clad laminate (CCL) refers to a laminate in which the aforementioned metal foil is laminated on one or both sides of the aforementioned resin substrate. The aforementioned resin substrate and the aforementioned metal foil can be laminated using the adhesive composition of this invention, or they can be laminated by thermoforming without using the adhesive composition of this invention. Specific structures of copper-clad laminates (CCLs) include: metal foil layer / adhesive layer / resin substrate layer / adhesive layer / metal foil layer, etc. By etching the metal foil layer to form a circuit pattern, it can be used as a laminate material for printed circuit boards.

[0162] <Resin-coated metal foil>

[0163] In this invention, a resin-containing metal foil refers to a metal foil on one side of which an adhesive layer, which is a cured product of the adhesive composition of this invention, is laminated. Specific configurations include: metal foil layer / adhesive layer or metal foil layer / adhesive layer / release substrate, etc. The metal foil is preferably copper foil. Since the adhesive layer in the resin-containing metal foil can be laminated with the aforementioned resin substrate, the resin-containing metal foil can be used as a material in the manufacture of the aforementioned CCL.

[0164] <Covering film>

[0165] In this invention, the cover film refers to a laminate formed by laminating the above-mentioned resin substrate and the above-mentioned release substrate with the adhesive composition of this invention. As the resin substrate in the cover film, any existing insulating film known as an insulating film for printed circuit boards can be used. The resin constituting the resin substrate is preferably polyester resin, aramid resin, polyimide resin, polyamide-imide resin, liquid crystal polymer, polyphenylene sulfide, polyethersulfone, polyetheretherketone, polycarbonate, polyaryl ester, syndiotactic polystyrene, polyolefin resin, etc., and more preferably a film composed of polyimide resin, liquid crystal polymer, fluorinated resin, etc. The cover film can be manufactured by coating the adhesive composition of this invention onto the above-mentioned resin substrate, drying it, and then attaching the above-mentioned release substrate thereon.

[0166] <Adhesive Sheets>

[0167] In this invention, the adhesive sheet refers to a laminate formed by stacking the adhesive composition of this invention on the aforementioned release substrate. Specific configurations include: release substrate / adhesive layer / release substrate, or release substrate / adhesive layer / substrate (excluding the release substrate) / adhesive layer / release substrate, etc. By stacking the release substrate, it can function as a protective layer for the substrate. Furthermore, by using the release substrate, it can be peeled off from the adhesive sheet for further bonding between other substrates. From the viewpoint of visibility during printed circuit board manufacturing, it is preferable that at least one side of the release substrate stacked on the outermost layer of the adhesive sheet is opaque.

[0168] Printed Circuit Boards

[0169] The adhesive composition of the present invention is preferably used in printed circuit boards. The printed circuit board of the present invention comprises a laminate having the aforementioned metal substrate (metal foil) for forming conductive circuits and the aforementioned resin substrate as structural elements. The printed circuit board of the present invention is a general term for so-called rigid substrates, flexible printed circuit boards (FPCs), flat cables, tape-and-reel (TAB) circuit boards, etc.

[0170] The printed circuit board of the present invention can adopt any laminated structure that can be used as a printed circuit board. Preferably, the printed circuit board of the present invention comprises a laminated body formed by laminating the adhesive composition of the present invention onto a substrate of resin substrate, metal substrate, paper, or inorganic non-metallic substrate as a structural element. Depending on the need, a structure consisting of two or more of the above-mentioned printed circuit boards can also be adopted. Furthermore, depending on the need, a structure consisting of two or more layers other than the protective layer of the above-mentioned printed circuit board made of adhesive sheets, and a protective layer such as a cover film or solder resist is provided thereon, can also be adopted. For example, a printed circuit board consisting of four layers, such as a resin substrate layer / adhesive layer / metal foil layer / cover film layer, or a resin substrate layer / metal foil layer / adhesive layer / cover film layer, can be manufactured using the above-mentioned CCL laminated body. Alternatively, a printed circuit board consisting of five layers, such as a resin substrate layer / adhesive layer / metal foil layer / adhesive layer / cover film layer, can also be manufactured.

[0171] For circuit formation in a metal substrate (metal foil layer), known methods can be used. Both additive and subtractive methods can be used. Subtractive methods are preferred.

[0172] The printed circuit board of the present invention can be manufactured using any known process, except for the materials used in the aforementioned layers. For example, a circuit pattern is formed on a 3-layer CCL using adhesive or a 2-layer CCL without adhesive, and then bonded to another CCL using an adhesive sheet or prepreg, and laminated by thermosetting. After drilling, through-hole electroplating, copper foil pattern formation, etc., a protective layer such as a cover film or solder resist is formed on the outermost layer, and then surface treatment is performed to obtain a multilayer printed circuit board.

[0173] The adhesive composition of the present invention is suitable for use in the manufacture of printed circuit boards (PCBs), specifically for use in various adhesive layers of PCBs. In particular, when using the adhesive composition of the present invention as an adhesive, it can bond not only polyimide films, polyester films, and FR-4, which are traditional substrates constituting PCBs, but also difficult-to-bond substrates such as liquid crystal polymers and fluoropolymer-impregnated glass cloth, as well as low-roughness copper foil. Furthermore, due to its high adhesion to low-polarity resin substrates such as liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resins, solder reflow resistance can be obtained. Since the adhesive layer itself also has excellent low dielectric properties, PCBs with excellent high-frequency characteristics can be obtained.

[0174] This application claims priority based on Japanese Patent Application No. 2024-052225, filed on March 27, 2024. The entire contents of the description in Japanese Patent Application No. 2024-052225, filed on March 27, 2024, are incorporated herein by reference. Example

[0175] The present invention will be described in more detail below with examples, but the present invention is of course not limited to the following examples and can be implemented by appropriate modifications within the scope of the preceding and following text, all of which are included within the technical scope of the present invention. In addition, unless otherwise stated, "parts" means "parts by mass" and "%" means "% by mass".

[0176] <Physical Property Evaluation>

[0177] (Acid value determination)

[0178] The acid value (equivalent / 10) in this invention 6 g) is the value obtained by dissolving the acid-modified resin in toluene, titrating it with a methanol solution of sodium methoxide, and using phenolphthalein as an indicator.

[0179] (Weight-average molecular weight (Mw))

[0180] The weight-average molecular weight in this invention was measured using a gel permeation chromatograph (hereinafter referred to as GPC, standard material: polystyrene resin, mobile phase: tetrahydrofuran, chromatographic column: Shodex KF-802 + KF-804L + KF-806L, column temperature: 30°C, flow rate: 1.0 ml / min, detector: RI detector) manufactured by Shimadzu Corporation.

[0181] (Determination of melting point)

[0182] The melting point in this invention is the value measured by a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000) at a rate of 20°C / min to melt, cool and solidify, and then reheat to melt, at the peak temperature of the melt peak.

[0183] <Evaluation of Adhesive Compositions>

[0184] (relative permittivity (ε) r and dielectric loss tangent (tanδ)

[0185] The adhesive composition was applied to a 100 μm thick Teflon (registered trademark) sheet, which was dried to a thickness of 25 μm and then dried at 100°C for 2 minutes. Next, another Teflon sheet was placed over the surface coated with the adhesive composition, and the sheet was hot-pressed at 180°C for 90 minutes under a pressure of 2 MPa to cure it. The Teflon sheets on both sides were then peeled off to obtain the adhesive resin sheet. The resulting sheet was cut into 10 cm × 10 cm strips to obtain samples for initial characteristic evaluation.

[0186] In addition, after curing by hot pressing in the same manner as above, only one side of the Teflon sheet is peeled off to obtain an adhesive resin sheet with a Teflon sheet. The obtained sheet is left to stand in an oven at 125°C in air for 1000 hours, and then cut into short strips of 10cm × 10cm to obtain samples for long-term heat resistance evaluation.

[0187] Relative permittivity (ε) r The dielectric loss tangent (tanδ) and dielectric loss angle were measured using a network analyzer (manufactured by Keysight Technologies) and a split cylindrical resonator (manufactured by EM Labs) at a temperature of 23°C, humidity of 50%, and frequency of 80 GHz. The initial performance evaluation samples were measured under the same conditions as the long-term heat resistance evaluation samples.

[0188] <Evaluation Criteria for Relative Permittivity>

[0189] ○: Below 2.4

[0190] ×: 2.4 or above

[0191] <Evaluation Criteria for Dielectric Loss Tangent>

[0192] ○: 0.0015 or less

[0193] ×: Greater than 0.0015

[0194] (Peel strength (adhesion))

[0195] The adhesive composition was coated onto a 100 μm thick surface-treated PTFE film (manufactured by Yodogawa Hu-Tech Co., Ltd., Yodoflon (registered trademark)), and dried to a thickness of 25 μm. The film was then dried at 100°C for 2 minutes. The resulting adhesive film (Grade B) was then laminated onto an 18 μm thick electrolytic copper foil (manufactured by Fukuda Metal Foil Powder Co., Ltd., T9DA-SV-18). During lamination, the rough surface of the copper foil was brought into contact with the adhesive layer. The temperature was increased from 35°C to 180°C at a rate of 4°C per minute under a pressure of 2 MPa. After reaching 180°C, the film was heat-treated for 90 minutes to cure, yielding a sample for peel strength evaluation. Peel strength was measured under the following conditions: 25°C, film stretching, stretching speed of 50 mm / min, and 90° peel.

[0196] <Evaluation Criteria>

[0197] ○: 1.0 N / mm or higher

[0198] ×: Less than 1.0 N / mm

[0199] (Heat resistance of solder)

[0200] Evaluation samples were prepared using the same method as for peel strength testing. Sample pieces cut into 2.0cm × 2.0cm pieces were immersed in a solder bath, and the upper limit temperature at which no bubbling or other appearance changes were recorded was recorded.

[0201] <Evaluation Criteria>

[0202] ○: No change in appearance above 290℃

[0203] ×: Appearance changes occur below 290℃.

[0204] (High temperature and high humidity resistance)

[0205] Evaluation samples were prepared using the same method as those used for peel strength testing, and their appearance was observed after being placed in a high-temperature, high-humidity chamber at 85°C and 85% humidity for 1000 hours. The peel strength after the high-temperature, high-humidity test was measured using the same method as for peel strength testing.

[0206] <Evaluation Criteria>

[0207] ○: No visible abnormalities, peel strength ≥ 1.0 N / mm

[0208] △: Slight discoloration, peel strength less than 1.0 N / mm

[0209] ×: Substrate peeling and discoloration.

[0210] (Long-term heat resistance)

[0211] Evaluation samples were prepared using the same method as for the peel strength test, and their appearance was observed after being placed in an oven at 125°C for 1000 hours. The peel strength after the long-term heat resistance test was determined using the same method as for the peel strength test.

[0212] <Evaluation Criteria>

[0213] ○: No visible abnormalities, peel strength ≥ 1.0 N / mm

[0214] △: Discoloration occurs, peel strength is less than 1.0 N / mm

[0215] ×: Substrate peeling and discoloration.

[0216] <Preparation of Adhesive Compositions>

[0217] The following describes examples of the manufacture of adhesive compositions according to embodiments and comparative examples of the present invention.

[0218] Acid-modified resins are manufactured using the following method.

[0219] (Manufacturing Example 1)

[0220] In a 1L autoclave, 100 parts of propylene-butene copolymer (manufactured by Mitsui Chemicals Co., Ltd., "TAFMER (registered trademark) XM7080"), 150 parts of toluene, 19 parts of maleic anhydride, and 6 parts of di-tert-butyl peroxide were added. The mixture was heated to 140°C and stirred for 3 hours. The resulting reaction solution was then cooled and injected into a container containing a large amount of methyl ethyl ketone to precipitate the resin. The resin-containing liquid was then centrifuged to separate and purify the acid-modified propylene-butene copolymer grafted with maleic anhydride from the (poly)maleic anhydride and low molecular weight compounds. The resin was then dried under reduced pressure at 70°C for 5 hours to obtain maleic anhydride-modified propylene-butene copolymer (acid-modified resin 1, acid value 367 equivalents / 10). 6 g, weight-average molecular weight 60,000, Tm 80℃, ΔH 35J / g).

[0221] (Manufacturing Example 2)

[0222] In a 1L autoclave, 100 parts of a cyclic olefin polymer (ZEONEX RS420 manufactured by Zeon Corporation, Japan), 150 parts of toluene, 19 parts of maleic anhydride, and 6 parts of di-tert-butyl peroxide were added. The mixture was heated to 140°C and stirred for 3 hours. The resulting reaction solution was then cooled and injected into a container containing a large amount of methyl ethyl ketone, allowing the resin to precipitate. The acid-modified cyclic olefin polymer grafted with maleic anhydride was then separated and purified from (poly)maleic anhydride and low molecular weight compounds by centrifugation of the liquid containing the resin. The purified resin was then dried under reduced pressure at 70°C for 5 hours to obtain a maleic anhydride-modified cyclic olefin polymer (acid-modified resin 2, acid value 339 equivalents / 10). 6 g, relative permittivity at 80 GHz 2.0, dielectric loss tangent at 80 GHz 0.0008, weight-average molecular weight 90,000).

[0223] The following substances are used as other acid-modified resins.

[0224] (Acid-modified resin 3): Tuftec M1943 (manufactured by Asahi Kasei Corporation, a polymer produced by partially hydrogenating the double bonds of a block copolymer of styrene and butadiene and then modifying it with maleic anhydride, acid value 185 equivalents / 10). 6 g)

[0225] The following substances are used as epoxy resin (C).

[0226] N,N-(diglycidyl)-o-toluidine (manufactured by ADEKA, "ADEKA RESIN (registered trademark) EP-3980S", epoxy value 8696 equivalent / 10) 6 g)

[0227] The following substances are used as antioxidants (A).

[0228] a1: Phenolic antioxidant (SUMILIZER GA-80 manufactured by Sumitomo Chemical Co., Ltd., 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)bis(2-methylpropane-2,1-diyl)=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate])

[0229] a2: Sulfur-based antioxidant (SUMILIZER TP-D, manufactured by Sumitomo Chemical Co., Ltd., pentaerythritol tetra(3-lauryl thiopropionate)).

[0230] The following substance is used as a heavy metal passivating agent (B).

[0231] b1: Hydrazine-based heavy metal passivating agent (manufactured by ADEKA, "ADEKA STAB (registered trademark) CDA-10", N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine)

[0232] b2: Phosphite-based heavy metal passivating agent (HOSTANOX OSP1, manufactured by Clariant, a reaction product of 2,2'-di-tert-butyl-5,5'-dimethyl-4,4'-thiodiphenol and phosphorus trichloride)

[0233] <Example 1>

[0234] A mixture of 100 parts acid-modified resin, 2 parts epoxy resin, 0.09 parts antioxidant a1, 0.21 parts antioxidant a2, and 0.10 parts heavy metal passivator b1 was dissolved in toluene to a solids concentration of 25%, yielding adhesive composition (S1). Various evaluations of the obtained adhesive composition (S1) were performed. The results are shown in Table 1.

[0235] <Examples 2-6, Comparative Examples 1-7>

[0236] Except for changing the types and mixing amounts of each component of the adhesive composition as shown in Tables 1-2, adhesive compositions (S2) to (S13) were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Tables 1-2.

[0237] Table 1

[0238]

[0239] Table 2

[0240]

[0241] As shown in Examples 1-6, the adhesive composition containing a specified amount of antioxidant (A) and heavy metal passivator (B) exhibits good appearance and excellent adhesion even after a long-term heat resistance test at 125°C for 1000 hours. Furthermore, it also exhibits excellent low dielectric properties even after the long-term heat resistance test. Further, as shown in Examples 1-6, the adhesive composition containing a specified amount of antioxidant (A) and heavy metal passivator (B) also exhibits excellent solder heat resistance, adhesion, and initial low dielectric properties.

[0242] In particular, as shown in the comparison of Examples 1, 4-6, by changing the content ratio and type of heavy metal passivating agent (B), the appearance, adhesion, and dielectric properties after the long-term heat resistance test can be altered. Furthermore, a comparison of Examples 4 and 6 shows that using a hydrazine-based heavy metal passivating agent as heavy metal passivating agent (B) is effective in obtaining an adhesive composition with excellent appearance, adhesion, and dielectric properties after the long-term heat resistance test.

[0243] The adhesive compositions of Comparative Examples 1-3, lacking the heavy metal passivator (B), exhibited deterioration in appearance and adhesion after long-term heat resistance testing. Similarly, the adhesive composition of Comparative Example 4, lacking the antioxidant (A), also showed deterioration in appearance, adhesion, and dielectric properties after long-term heat resistance testing.

[0244] The adhesive compositions of Comparative Examples 5 and 6, due to their high content of antioxidants (A) or heavy metal passivators (B), exhibited deteriorated dielectric properties after long-term heat resistance testing. Furthermore, the solder heat resistance and initial dielectric properties of the adhesive compositions of Comparative Examples 5 and 6 were not adequately improved.

[0245] The adhesive composition of Comparative Example 7, lacking epoxy resin (C), underwent insufficient curing, resulting in deterioration of appearance and adhesion after long-term heat resistance testing. Furthermore, the adhesive composition of Comparative Example 7 also failed to achieve adequate performance in solder heat resistance, adhesion, and high-temperature and high-humidity resistance tests at 85°C and 85% for 1000 hours.

[0246] Furthermore, comparing Comparative Examples 1-6 with Comparative Examples 1-4, regardless of whether antioxidant (A) and heavy metal passivator (B) were mixed, the high-temperature and high-humidity resistance test at 85°C and 85% for 1000 hours was at a qualified level. However, the long-term heat resistance test at 125°C for 1000 hours did not reach a qualified level if antioxidant (A) and heavy metal passivator (B) were not present. Therefore, the adhesive composition of the present invention meets more stringent standards.

[0247] [Industry Applicability]

[0248] The adhesive composition of the present invention exhibits good appearance even after a long-term heat resistance test at 125°C for 1000 hours, and demonstrates excellent adhesion and low dielectric properties. Furthermore, the adhesive composition of the present invention also exhibits excellent solder heat resistance, adhesion, and initial low dielectric properties. Therefore, the adhesive composition of the present invention can be used as an adhesive composition for printed circuit boards in high-frequency regions, as well as for adhesive sheets, laminates, and printed circuit boards containing the present invention.

Claims

1. An adhesive composition, characterized in that, The product comprises an acid-modified resin, an antioxidant (A), a heavy metal passivator (B), and an epoxy resin (C). The content of the antioxidant (A) is less than 1.0 part by weight and the content of the heavy metal passivator (B) is less than 1.0 part by weight relative to 100 parts by weight of the acid-modified resin.

2. The adhesive composition according to claim 1, wherein, The acid-modified resin is selected from one or more of acid-modified polystyrene resins, acid-modified cyclic olefin polymers, and acid-modified polyolefins.

3. The adhesive composition according to claim 1, wherein, The heavy metal passivating agent (B) includes at least one of hydrazine-based heavy metal passivating agents and phosphite-based heavy metal passivating agents.

4. The adhesive composition according to claim 1, wherein, The heavy metal passivating agent (B) has an intramolecular chemical structure represented by formula (II). 【Chemistry 1】 In equation (II), * represents the bonding site, R 4 ~R 6 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.

5. The adhesive composition according to claim 1, wherein, The content of the heavy metal passivating agent (B) is 1 to 200 parts by mass relative to 100 parts by mass of the antioxidant (A).

6. The adhesive composition according to claim 1, wherein, The content of the heavy metal passivating agent (B) is 0.01 parts by mass or more relative to 100 parts by mass of the acid-modified resin.

7. The adhesive composition according to claim 1, wherein, The antioxidant (A) is selected from one or more of phenolic antioxidants, sulfur-based antioxidants, amine-based antioxidants, and phosphorus-based antioxidants.

8. The adhesive composition according to claim 1, wherein, The antioxidant (A) has an intramolecular chemical structure represented by formula (I). 【Chemistry 2】 In equation (I), * represents the bonding position, R 1 ~R 3 Each independently represents a hydrogen atom or a carbon atom. 1-10 alkyl.

9. The adhesive composition according to claim 1, wherein, The epoxy resin (C) is a multifunctional epoxy resin.

10. The adhesive composition according to claim 1, wherein, The epoxy value of the epoxy resin (C) is 5,000 to 12,000 equivalents / 10. 6 g.

11. The adhesive composition according to claim 1, wherein, The epoxy resin (C) is selected from one or more of glycidylamine type epoxy resins and isocyanuric acid containing glycidyl groups.

12. The adhesive composition according to any one of claims 1 to 11, used in printed circuit boards.

13. An adhesive sheet having the adhesive composition of any one of claims 1 to 11 laminated on a release substrate.

14. A laminate having the adhesive composition of any one of claims 1 to 11 laminated on a substrate, wherein the substrate is a resin substrate, a metal substrate, a paper substrate, or an inorganic non-metallic substrate.

15. A printed circuit board comprising the laminate of claim 14 as a constituent element.