Primer composition for electroless plating, laminate, and method for producing the same

Abstract

To provide a primer composition for electroless plating having excellent adhesion to a metal plating layer even when a highly gas-permeable insulating substrate is employed, and capable of maintaining the adhesion after exposure to high-temperature heating.SOLUTION: A primer composition for electroless plating of the present invention contains a phenoxy resin (A) having a Tg of 100°C or higher, a trifunctional or higher epoxy resin (B) having three or more epoxy groups in a molecule, and a melamine resin (C), the content of the trifunctional or higher epoxy resin (B) being 10-75 pts.mass per 100 pts.mass of the phenoxy resin (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a primer composition for electroless plating, a laminate, and a method for producing the same. [Background technology]

[0002] Flexible copper clad laminates (FCCLs), which are made by laminating an insulating film and a metal layer, are used as materials for printed wiring boards, etc. Flexible copper clad laminates are obtained through a process in which a metal layer is formed by plating on an insulating substrate.

[0003] To improve adhesion between the insulating substrate and the metal plating layer, etching (roughening) is sometimes performed to create fine irregularities on the surface of the insulating substrate. However, etching not only complicates the process, but also increases transmission loss due to the skin effect in high-frequency devices for 5G. Furthermore, the increased surface irregularities on the metal plating layer make it difficult to form fine wiring.

[0004] Therefore, methods for improving the adhesion between an insulating substrate and a metal plating layer without etching have been investigated. For example, a method is known in which a base layer (primer layer) containing an electroless plating catalyst is formed on the surface of the insulating substrate, and then a plating layer is formed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-209643 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, insulating substrates are made of polyethylene terephthalate (PET), liquid crystal polymers, etc. In recent years, polyimides and other materials have been used in view of their heat resistance to solder reflow temperatures and dimensional stability at high temperatures.

[0007] However, when a laminate in which a primer layer and a metal plating layer are laminated on an insulating substrate having high gas permeability, such as polyimide, is heated at high temperatures, the metal plating layer may peel off from the primer layer.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a primer composition for electroless plating, a laminate, and a method for producing the same, which have high adhesion to a metal plating layer even when an insulating substrate with high gas permeability is used, and which can maintain adhesion even after being heated at high temperatures. [Means for solving the problem]

[0009] The above problem can be solved by the following configuration. [1] A primer composition for electroless plating, comprising: a phenoxy resin (A) having a glass transition temperature (Tg) of 100°C or higher; a tri- or higher functional epoxy resin (B) having three or more epoxy groups in the molecule; and a melamine resin (C), wherein the content of the tri- or higher functional epoxy resin (B) is 10 to 75 parts by mass per 100 parts by mass of the phenoxy resin (A). [2] The primer composition for electroless plating according to [1], wherein the weight average molecular weight of the phenoxy resin (A) is 10,000 or more and less than 50,000. [3] The primer composition for electroless plating according to [1] or [2], further comprising a resol phenolic resin (D). [4] The primer composition for electroless plating according to [3], wherein the content of the resol phenolic resin (D) is 10 to 40 parts by mass per 150 parts by mass of the total of the phenoxy resin (A) and the tri- or higher functional epoxy resin (B). [5] The primer composition for electroless plating according to any one of [1] to [4], further comprising palladium particles (F). [6] The primer composition for electroless plating according to any one of [1] to [5], further comprising silica particles (G). [7] A laminate comprising an insulating substrate, a primer layer disposed on the insulating substrate and comprising a cured product of the electroless plating primer composition according to any one of [1] to [6], and a metal plating layer disposed on the primer layer. [8] The insulating substrate has an oxygen permeability of 50 (cc / m) at 25°C measured in accordance with JIS K 7126:2006. 2 24h / atm) or more. [9] The laminate according to [7] or [8], wherein the insulating substrate contains polyimide.

[10] A method for producing a laminate, comprising the steps of: applying the primer composition for electroless plating according to any one of [1] to [6] to the surface of an insulating substrate to form a layer of the primer composition; and forming a metal plating layer on the surface of the layer of the primer composition by electroless plating.

[11] The method for producing a laminate according to

[10] , further comprising a step of curing the primer composition on which the metal plating layer has been formed. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a primer composition for electroless plating, a laminate, and a method for producing the same, which have high adhesion to a metal plating layer even when an insulating substrate with high gas permeability is used, and which can maintain adhesion even after being heated at high temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present inventors have investigated the reason why the metal plating layer becomes easily peeled when a laminate in which a primer layer and a metal plating layer are laminated on a highly gas-permeable insulating base material is heated at high temperatures, and have found that gas that has permeated the insulating base material permeates the primer layer and oxidizes the metal plating layer, causing the metal plating layer to become easily peeled.

[0012] In contrast, by using a primer composition containing a phenoxy resin (A) having a Tg of 100°C or higher, a tri- or higher functional epoxy resin (B), and a melamine resin (C), particularly by combining a phenoxy resin (A) having a Tg of 100°C or higher with a tri- or higher functional epoxy resin (B) (preferably a tetra-functional epoxy resin), peeling of the metal plating layer when heated at high temperatures can be suppressed even when an insulating substrate with high gas permeability is used.

[0013] The reason for this is not clear, but is presumed to be as follows. The phenoxy resin (A) with a Tg of 100°C or higher has a highly heat-resistant skeleton, i.e., a rigid skeleton. Furthermore, the tri- or higher functional epoxy resin (B) contains three or more epoxy groups per molecule, resulting in a cured product with a high crosslink density. The combination of these components results in a cured product with a rigid and highly crosslinked structure that is resistant to gas permeation. This makes the metal plating layer less susceptible to oxidation by gases that have permeated the primer layer, making it less likely to peel off.

[0014] A primer composition according to one embodiment of the present invention and a laminate using the same will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0015] 1. Primer composition A primer composition according to one embodiment of the present invention contains a phenoxy resin (A) having a Tg of 100°C or higher (hereinafter also simply referred to as "phenoxy resin (A)"), a tri- or higher functional epoxy resin (B), and a melamine resin (C).

[0016] 1-1. Phenoxy resin (A) The phenoxy resin (A) is a polymer having a polyhydroxypolyether structure obtained by polyaddition reaction of a polyfunctional phenol and a polyfunctional glycidyl ether (preferably a bifunctional phenol and a bifunctional glycidyl ether).

[0017] The glass transition temperature (Tg) of the phenoxy resin (A) is 100°C or higher. Such a phenoxy resin (A) has a rigid structure, which reduces the gas permeability of the primer layer. This suppresses oxidation of the metal plating layer due to gas permeating through the primer layer, thereby preventing peeling. From the same perspective, the Tg of the phenoxy resin (A) is more preferably 130°C or higher. The upper limit of the Tg of the phenoxy resin (A) is not particularly limited, but is preferably 200°C or lower, for example, from the viewpoint of further improving solubility in solvents and compatibility with other components and further reducing pinholes in the resulting primer layer. The Tg of the phenoxy resin (A) can be measured at 10°C / min using a differential scanning calorimeter (DSC).

[0018] The phenoxy resin (A) is preferably a phenoxy resin having one or more skeletons selected from the group consisting of a bisphenol skeleton (such as a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, or a bisphenolacetophenone skeleton), a biphenol skeleton (such as a biphenol skeleton or a tetramethylbiphenol skeleton), or a fluorene skeleton. Of these, a phenoxy resin having one or more skeletons selected from the group consisting of a bisphenol S skeleton, a biphenol skeleton, or a fluorene skeleton is more preferred.

[0019] Examples of such phenoxy resins (A) include biphenol type (BP type), bisphenol S type (BPS type), bisphenol A type / bisphenol S type (BPA / BPS type), biphenol type / bisphenol S type (BP / BPS type), bisphenol AP type / tetramethylbiphenol type, biscresol fluorene-containing type, and biscresol fluorene skeleton / polyalkyleneoxy-containing type.

[0020] Commercially available phenoxy resins (A) include, for example, jER (registered trademark) YX6954BH30 (manufactured by Mitsubishi Chemical Corporation, phenoxy resin containing a bisphenol acetophenone skeleton, epoxy equivalent: 13,000 g / eq, Tg: 130°C), ERF-001M30 (manufactured by Nippon Steel Chemical & Material Co., Ltd., Tg: 146°C), and jER (registered trademark) Examples include YX8100BH30 (manufactured by Mitsubishi Chemical Corporation, bisphenol S skeleton / biphenol skeleton, epoxy equivalent: 10,000 to 20,000 g / eq, Tg: 150°C), YX7200 (manufactured by Mitsubishi Chemical Corporation, Tg: 150°C), YL7553BH30 (manufactured by Mitsubishi Chemical Corporation, special type, epoxy equivalent: 10,000 to 16,000 q / eq, FX280, FX293, and FX293S (manufactured by Nippon Steel Chemical & Material Co., Ltd., fluorene skeleton-containing phenoxy resins).

[0021] The weight-average molecular weight (Mw) of the phenoxy resin (A) is not particularly limited, but is preferably 10,000 or more and less than 50,000. When the Mw of the phenoxy resin (A) is 10,000 or more, the viscosity of the primer composition can be appropriately increased, thereby further increasing the film strength of the cured product. When the Mw of the phenoxy resin (A) is less than 50,000, the resulting cured product has a relatively rigid structure, thereby further reducing gas permeability. Furthermore, since compatibility with other components and solubility in solvents are less likely to be impaired, a cured product with fewer pinholes and a smoother surface can be obtained. From the same perspective, the Mw of the phenoxy resin (A) is more preferably 20,000 or more and 40,000 or less.

[0022] The Mw of the phenoxy resin (A) can be determined as a value converted into standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0023] The phenoxy resin (A) may have an epoxy group. When the phenoxy resin (A) has an epoxy group, the epoxy equivalent of the phenoxy resin (A) is preferably 5000 g / eq or more, more preferably 6500 g / eq or more. The epoxy equivalent can be measured in accordance with JIS K7236:2009.

[0024] As described above, the phenoxy resin (A) can be obtained, for example, by subjecting a difunctional phenol to a polyaddition reaction with a difunctional glycidyl ether. The bifunctional phenol is not particularly limited as long as it is a compound having two phenolic hydroxyl groups, and examples thereof include bisphenols such as bisphenol A, bisphenol F, bisphenol AP, and bisphenol S; dihydroxybiphenyls such as 4,4'-dihydroxybiphenyl (4,4'-biphenol); and 9,9-bis(4-hydroxyphenyl)fluorene. Examples of bifunctional glycidyl ethers include diglycidyl ethers of bisphenol, diglycidyl ethers of biphenol, and diglycidyl ethers of 2,2',6,6'-tetramethyl-4,4'-biphenol.

[0025] The content of the phenoxy resin (A) is preferably 20 to 65 mass % and more preferably 30 to 60 mass % based on the non-volatile components of the primer composition. The higher the content of the phenoxy resin (A), the easier the curing reaction with the melamine resin (C) becomes, and therefore the film strength and crosslink density of the obtained cured product can be further increased. In this specification, the non-volatile components refer to the components constituting the composition other than the solvent.

[0026] Epoxy resin with 1-2.3 or more functional groups (B) The tri- or higher functional epoxy resin (B) is an epoxy resin having three or more epoxy groups in the molecule. The tri- or higher functional epoxy resin (B) has many reaction sites with the resol phenolic resin (D) described below, and therefore can give a cured product with high crosslink density. In addition, the tri- or higher functional epoxy resin (B) also has many hydroxyl groups generated by ring-opening of the epoxy groups, which can improve the adhesiveness of the cured product. The tri- or higher functional epoxy resin (B) preferably contains a tri- or tetrafunctional epoxy resin, and more preferably contains a tetrafunctional epoxy resin.

[0027] The content of the tri- or higher functional epoxy resin (B) is 10 to 75 parts by mass per 100 parts by mass of the phenoxy resin (A). When the content of the tri- or higher functional epoxy resin (B) is 10 parts by mass or more, the crosslink density of the cured product of the primer composition can be further increased. This reduces the gas permeability of the cured product, thereby suppressing peeling of the metal plating layer. When the content of the tri- or higher functional epoxy resin (B) is 75 parts by mass or less, the cured product does not become too hard, making it less likely to lose adhesion. From the same perspective, the content of the tri- or higher functional epoxy resin (B) is preferably more than 40 parts by mass and not more than 75 parts by mass, more preferably 45 to 70 parts by mass, per 100 parts by mass of the phenoxy resin (A).

[0028] From the viewpoint of further improving adhesiveness after heat resistance, the tri- or higher functional epoxy resin (B) is preferably an epoxy resin having an aromatic ring (aromatic epoxy resin). Examples of such tri- or higher functional epoxy resin (B) include diaminodiphenylmethane type, diaminodiphenylsulfone type, metaxylenediamine type, tetraphenylolethane type, naphthalene type, biphenyl type, cresol novolac type, phenol novolac type, and dicyclopentadiene type epoxy resins.

[0029] For example, commercially available tri- or higher functional epoxy resins (B) include the following: Examples of trifunctional epoxy resins include VG3101L (Printec Co., Ltd.) and ELM100 (Sumitomo Chemical Co., Ltd.). Examples of tetrafunctional epoxy resins include the following: Examples of diaminodiphenylmethane epoxy resins include ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), Araldite MY720, MY721, MY9512, and MY9663 (manufactured by Huntsman Advanced Materials), and Epotohto YH-434 (manufactured by Nippon Steel Chemical & Material Co., Ltd.). An example of a diaminodiphenyl sulfone type epoxy resin is TG3DAS (manufactured by Mitsui Fine Chemicals, Inc.). An example of a metaxylenediamine type epoxy resin is TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.). An example of a tetraphenylolethane type epoxy resin is jER 1031S (manufactured by Mitsubishi Chemical Corporation). An example of the naphthalene-type epoxy resin is HP-4700 (manufactured by DIC Corporation, a tetrafunctional naphthalene-type epoxy resin). Examples of biphenyl type epoxy resins include NC-3000 (manufactured by Nippon Kayaku Co., Ltd.). Examples of cresol novolac epoxy resins include EOCN-1020 (manufactured by Nippon Kayaku Co., Ltd.) and EPICLON N-660 (manufactured by DIC Corporation). Examples of phenol novolac epoxy resins include DEN431 and DEN438 (both manufactured by The Dow Chemical Company) and jER 152 and 154 (both manufactured by Mitsubishi Chemical Corporation). Examples of dicyclopentadiene-type epoxy resins include HP-7200 (manufactured by DIC Corporation) and XD-1000 (manufactured by Nippon Kayaku Co., Ltd.).

[0030] The tri- or higher functional epoxy resin (B) may be a liquid epoxy resin or a solid epoxy resin. Liquid means that it is liquid at 20°C, and solid means that it is solid at 20°C.

[0031] The epoxy equivalent of the tri- or higher functional epoxy resin (B) is not particularly limited, but is preferably less than 5000 g / eq. On the other hand, the epoxy equivalent of the phenoxy resin (A) is preferably 5000 g / eq or more, as described above. As described above, the phenoxy resin (A) may also have epoxy groups like the tri- or higher functional epoxy resin (B), but in this specification, they can be distinguished by their epoxy equivalent. From the viewpoint of reactivity, the epoxy equivalent of the tri- or higher functional epoxy resin (B) is preferably 100 to 1000 g / eq, more preferably 140 to 300 g / eq.

[0032] The weight average molecular weight (Mw) of the tri- or higher functional epoxy resin (B) is not particularly limited, but is preferably not more than 1000. Mw is measured by the same method as above.

[0033] 1-3.Melamine resin (C) The melamine resin (C) can function as a curing agent that cures the phenoxy resin (A) by reacting with the hydroxyl groups of the phenoxy resin (A), thereby allowing the phenoxy resin (A) to form a high-density crosslinked structure with the melamine resin (C).

[0034] Such melamine resin (C) may be melamine, a methylolated melamine derivative obtained by condensing melamine with formaldehyde, a compound obtained by reacting methylolated melamine with a lower alcohol to partially or completely etherify it, or a mixture thereof. The melamine resin (C) may be either a monomer or a condensate of a dimer or higher polymer.

[0035] Examples of the melamine resin (C) include imino group-type methylated melamine resins, methylol group-type methylated melamine resins, methylol group-type methylated melamine resins, and fully alkylated methylated melamine resins, with methylolated melamine resins being preferred. Commercially available examples of the melamine resin (C) include Nikalac MW-100LM, Nikalac MW-30, Nikalac MW-30M, Nikalac MW-22, Nikalac MW-22A, Nikalac MS-11, and Nikalac MX-750 manufactured by Sanwa Chemical Co., Ltd.; Cymel 300, Cymel 301, and Cymel 350 manufactured by Mitsui Cyanamid Co., Ltd.; and U-VAN 703 manufactured by Mitsui Chemicals, Inc.

[0036] The melamine resin (C) not only undergoes self-condensation but also readily reacts (cures) with the hydroxyl groups of the phenoxy resin (A), thereby enabling the film strength and crosslink density of the cured product of the primer composition to be further increased.

[0037] The content of melamine resin (C) is not particularly limited, but is preferably 25 to 65 parts by mass per 100 parts by mass of phenoxy resin (A). When the content of melamine resin (C) is 25 parts by mass or more, the curing reaction with phenoxy resin (A) is more likely, and the crosslink density and film strength of the obtained cured product can be further increased. When the content of melamine resin (C) is 65 parts by mass or less, the cured product does not become too hard, and pinholes and the like can be further reduced. From the same viewpoint, the content of melamine resin (C) is more preferably 30 to 60 parts by mass, and even more preferably 35 to 55 parts by mass per 100 parts by mass of phenoxy resin (A).

[0038] 1-4.Other ingredients The primer composition may further contain other components in addition to those described above, as necessary, for example, epoxy resins other than the phenoxy resin (A) and the tri- or higher functional epoxy resin (B), curing agents, palladium particles, fillers, solvents, etc.

[0039] 1-4-1.Other epoxy resins The other epoxy resin may be, for example, a tri- or lower-functional epoxy resin. From the viewpoint of heat resistance, the tri- or lower-functional epoxy resin is preferably an aromatic epoxy resin. Examples of tri- or lower-functional epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, trisphenol epoxy resins, naphthol novolac epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, and naphthalene epoxy resins.

[0040] 1-4-2.Resol phenolic resin (D) The resol phenolic resin (D) can function as a polyaddition curing agent for the trifunctional or higher epoxy resin (B). That is, at least one of the phenolic hydroxyl group and methylol group contained in the resol phenolic resin (D) can undergo an addition reaction with the epoxy group of the trifunctional or higher epoxy resin (B). This not only cures the trifunctional or higher epoxy resin (B), but also generates hydroxyl groups during the reaction process (ring-opening reaction), thereby further improving adhesion to insulating substrates.

[0041] Examples of the resol phenolic resin (D) include phenol type, cresol type, alkyl type, bisphenol A type, and copolymers thereof. Examples of commercially available resol phenolic resin (C-2) include Phenolite TD-447 (manufactured by DIC Corporation, cresol type).

[0042] The total amount of the tri- or higher functional epoxy resin (B) and the resol phenolic resin (D) is preferably 25 to 85 parts by mass, more preferably 30 to 80 parts by mass, per 100 parts by mass of the phenoxy resin (A). The larger the total amount, the easier it is to improve the adhesion of the metal plating layer to the substrate.

[0043] The content of the resol phenolic resin (D) is preferably 10 to 40 parts by mass per 150 parts by mass of the total of the phenoxy resin (A) and the tri- or higher functional epoxy resin (B). When the content of the resol phenolic resin (D) is 10 parts by mass or more, the curing reaction of the tri- or higher functional epoxy resin (B) and the reaction between the phenoxy resin (A) and the tri- or higher functional epoxy resin (B) are more likely to occur, thereby improving the adhesiveness of the cured product. When the content of the resol phenolic resin (D) is 40 parts by mass or less, the crosslink density of the cured product does not become too high, thereby reducing pinholes. From the same perspective, the content of the resol phenolic resin (D) is more preferably 10 to 30 parts by mass per 100 parts by mass of the total of the phenoxy resin (A) and the epoxy resin (B).

[0044] 1-4-3. Other hardeners (E) The primer composition may further contain a curing agent (E) other than the melamine resin (C) and the resol phenolic resin (D).

[0045] The other curing agent (E) is a curing agent for epoxy resins, and may be a polyaddition type or a catalytic type. Examples of polyaddition type curing agents include polyamines, acid anhydrides, polyphenols, polymercaptans, etc. Examples of catalytic type curing agents include tertiary amines, imidazoles, Lewis acid complexes, etc. Among them, from the viewpoint of further improving the heat resistance and toughness of the cured product, amines are preferred as polyaddition type curing agents, and imidazoles are preferred as catalytic type curing agents.

[0046] The polyamines may be either aliphatic polyamines or aromatic polyamines. From the viewpoint of heat resistance, aromatic polyamines are preferred, and aromatic diamines are more preferred. Examples of aromatic diamines include phenylenediamine, diaminodiphenylmethane, diaminodiphenyl ether, diaminodiphenyl sulfone, 1,3-bis(3-aminophenoxy)benzene, diethyltoluenediamine, 2,2-bis[4-(4-aminophenoxyphenoxy)phenyl]propane (BAPP), etc.

[0047] Examples of the imidazoles include imidazole, 1-methylimidazole, 2-methylimidazole, 4(5)-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and the like.

[0048] The content of the other curing agent (E) is preferably 0.5 to 30 parts by mass, and more preferably 1 to 25 parts by mass, per 100 parts by mass of the epoxy resin (including the tri- or higher functional epoxy resin (B)) in the primer composition.

[0049] 1-4-4. Palladium particles (F) The palladium particles (F) can function as a nucleating agent for electroless plating. The palladium particles (F) may be dispersed in a dispersant.

[0050] The average particle diameter of the palladium particles (F) can be, for example, 2 to 20 nm. The average particle diameter of the palladium particles (F) can be calculated by measuring the diameters of any 10 particles using a transmission electron microscope and taking the number average (number-based average diameter).

[0051] The content of palladium particles (F) is, for example, preferably 1 to 30% by mass, more preferably 1 to 5% by mass, based on the non-volatile components of the primer composition. This facilitates increased reactivity between the palladium particles (F) and the electroless plating solution, and facilitates increased adhesion between the primer layer and the metal plating layer. When the content of palladium particles (F) is 30% by mass or less, the resin component content is not too low, so that adhesion between the primer layer and the substrate, and coatability and dispersion stability are not easily impaired.

[0052] 1-4-5. Silica particles (G) The silica particles (G) may have the function of, for example, increasing the dispersion stability of the palladium particles (F). The silica particles (G) may be untreated, or may be treated to be hydrophilic or hydrophobic. The shape of the silica particles is not limited, and may be spherical silica or crushed silica.

[0053] Silica particles (G) can be included in the primer composition depending on the type of phenoxy resin (A). For example, if the phenoxy resin (A) is a polyaddition product of bisphenol AP / tetramethylbiphenol-type glycidyl ether, it may have a higher hydrophobicity (or a bulkier structure) than a polyaddition product of bisphenol S / biphenol-type glycidyl ether, resulting in a slightly inferior dispersion stability of the palladium particles (F). In such cases, it is preferable to further include silica particles (G) from the viewpoint of better dispersing the palladium particles (F) in the phenoxy resin (A) and thereby facilitating the production of a cured product with fewer pinholes. In this case, it is preferable that the silica particles (G) be hydrophilically treated silica particles (e.g., colloidal silica).

[0054] The average particle diameter of the silica particles (G) is preferably 10 to 100 nm, more preferably 10 to 50 nm. The average particle diameter can be measured by the cumulant method using a dynamic light scattering measuring device. Alternatively, the average particle diameter can be measured using a transmission electron microscope in the same manner as above, and calculated as the number-based average diameter.

[0055] The content of the silica particles (G) is not particularly limited, but is preferably 1 to 30 mass % and more preferably 1 to 10 mass % relative to the non-volatile components of the primer composition, which can further enhance the dispersion stability of the palladium particles (F).

[0056] 1-4-6. Solvent (H) The primer composition may further contain a solvent (H) (dispersion medium) for dispersing the palladium particles (F). The solvent is preferably one capable of dispersing the palladium particles (F) or a dispersion thereof, and may be, for example, water or an aprotic polar solvent.

[0057] Aprotic polar solvents include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, γ-butyrolactone, and the like.

[0058] Other examples of the solvent may include alcohols such as methanol and ethanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; glycol ethers such as ethylene glycol monomethyl ether and ethylene glycol monobutyl ether; aromatic carboxylic acid esters such as methyl benzoate, ethyl benzoate and methyl salicylate; aromatic hydrocarbons such as toluene and xylene; glycol ether esters such as methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, methyl carbitol acetate, butyl carbitol acetate and propylene glycol monomethyl ether acetate; and alkanol esters such as ethyl acetate and butyl acetate.

[0059] 1-5. Method for preparing primer composition The primer composition can be prepared by any method, for example, by mixing the above components.

[0060] The palladium particles may be added in the form of particles as they are, or may be added in a state where they are dispersed in a dispersant (as a dispersion).

[0061] 2.Laminate A laminate according to one embodiment of the present invention includes an insulating substrate, a primer layer, and a metal plating layer.

[0062] 2-1.Insulating substrate The insulating substrate may be an inorganic substrate or a resin substrate. Examples of inorganic substrates include ceramics and glass. Examples of resin materials for the resin substrate include polyester, (meth)acrylic resin, polycarbonate, polystyrene, polyvinyl chloride, polyamide, polyimide (e.g., MPI), polyetherimide, polyacetal, polyetheretherketone (PEEK), cyclic polyolefin (COC), polyolefin, polyphenylene sulfide (PPS), polysulfone, phenolic resin, liquid crystal polymer (LCP), and fluororesin.

[0063] In particular, when the laminate is used as a material for a printed wiring board, particularly a printed wiring board used in a device compatible with high frequencies such as 5G, the insulating substrate is preferably a resin substrate with a low dielectric constant. Examples of resin materials contained in the resin substrate with a low dielectric constant include polyimide (e.g., MPI), polyether ether ketone (PEEK), cyclic polyolefin (COC), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), fluororesin, etc. Among these, polyimide and cyclic olefin resin (COC), etc. are preferred because of their high heat resistance.

[0064] On the other hand, resin substrates containing polyimide, COC, etc. are easily permeable to gas. For example, if the oxygen permeability at 25°C measured in accordance with JIS K 7126:2006 (or JIS K 7126-2:2006) is 50 (cc / m 2 When an insulating substrate with a gas permeability of 1000 kJ / cm2 or more is used, if the primer layer has high gas permeability, the metal plating layer will be oxidized by the permeated gas and become prone to peeling, as described above.

[0065] In contrast, the primer composition described above contains a phenoxy resin (A) with a Tg of 100°C or higher and a tri- or higher functional epoxy resin (B). Therefore, the cured product of the primer composition has a rigid structure and a high crosslink density. Therefore, gases are less likely to permeate the primer layer, which helps prevent peeling of the metal plating layer.

[0066] The thickness of the insulating base material is not particularly limited, but can be, for example, 12.5 to 50 μm.

[0067] 2-2. Primer layer The primer layer contains a cured product of the above-described primer composition.

[0068] The thickness of the primer layer is not particularly limited as long as it can ensure the adhesive strength between the metal plating layer and the insulating substrate, but it is preferably thinner than the metal plating layer. In particular, the cured product of the primer composition exhibits good adhesive strength, so the thickness of the primer layer can be made sufficiently thin. Specifically, the thickness of the primer layer can be, for example, 0.1 to 1.0 μm.

[0069] 2-3. Metal plating layer The metal plating layer is a layer obtained by contacting the surface of the primer layer with an electroless plating solution, and contains metals such as copper, platinum, gold, silver, nickel, chromium, cobalt, tin, etc. The metal plating layer preferably contains a metal selected from the group consisting of copper, platinum, gold, silver, and nickel, and more preferably contains copper or an alloy thereof.

[0070] The thickness of the metal plating layer can be appropriately set depending on the application, but when used for a printed wiring board, for example, it can be, for example, 0.01 to 50 μm, preferably 0.1 to 10 μm, more preferably 0.1 to 2 μm.

[0071] The metal plating layer may be patterned into a predetermined shape. The patterned metal plating layer can function as, for example, a wiring pattern for a printed wiring board.

[0072] 2-4.Applications The laminate can be used for any purpose, such as a circuit-forming substrate used in electronic circuits, integrated circuits, etc., a transparent electrode used in organic EL devices, organic transistors, flexible printed circuit boards, RFID, touch panels, etc., and an electromagnetic wave shielding material. In particular, it can be suitably used in applications requiring durability at high temperatures, such as applications commonly known as copper clad laminates (CCLs) used in the production of flexible printed circuit boards (FPCs), tape automated bonding (TAB), chip-on-films (COFs), printed wiring boards (PWBs), etc.

[0073] 3. Manufacturing method of laminate The laminate can be obtained through the steps of 1) applying the primer composition to the surface of an insulating substrate to form a primer composition layer, and 2) applying electroless plating to the surface of the primer composition layer to form a metal plating layer. In this embodiment, after step 2), it is preferable to further perform step 3) of curing the primer composition that has formed the metal plating layer.

[0074] Step 1) The above-described primer composition is applied to the surface of an insulating substrate.

[0075] The method for applying the primer composition is not particularly limited, and can be, for example, gravure printing, flexographic printing, inkjet printing, dipping, spraying, spin coating, roll coating, reverse coating, screen printing, or the like.

[0076] The applied primer composition is then dried to form a layer of the primer composition.

[0077] Drying may be carried out under conditions that remove at least the solvent component in the applied primer composition and result in a self-supporting film, for example, by heating. The heating temperature may be such that the solvent component can be removed and, if necessary, the curing reaction of the phenoxy resin (A) and the tri- or higher functional epoxy resin (B) in the primer composition can proceed, and may be, for example, about 60 to 400°C, preferably about 80 to 150°C. The heating time may vary depending on the heating temperature, but may be, for example, about 0.1 to 5 minutes.

[0078] Step 2) Next, electroless plating is carried out on the surface of the primer composition layer to form a metal plating layer.

[0079] From the viewpoint of efficiently performing electroless plating, it is preferable that palladium particles are present on the surface of the primer layer. As described above, the palladium particles may be contained in the primer composition beforehand, or may be further applied to the surface of the primer layer by contacting with a solution containing palladium particles, etc. From the viewpoint of effectively increasing the reactivity with the electroless plating solution, it is preferable that the palladium particles are contained in the primer composition beforehand.

[0080] The electroless plating solution may contain a metal, a reducing agent, and water and / or a water-soluble organic solvent. The type of metal may vary depending on the application of the laminate, but may include, for example, one or more metals selected from the group consisting of copper, platinum, gold, silver, nickel, chromium, cobalt, and tin. The metal plating layer preferably contains a metal selected from the group consisting of copper, platinum, gold, silver, and nickel, and more preferably contains copper or an alloy thereof.

[0081] The electroless plating conditions can be set depending on the composition of the electroless plating solution. For example, the temperature of the electroless copper plating bath is usually about 25 to 45°C. The treatment time varies depending on the application, but can be, for example, about 10 to 20 minutes when forming a metal plating layer with a thickness of about 0.3 to 0.4 µm.

[0082] The thickness of the metal plating layer depends on the application of the laminate, but when used in a printed wiring board, for example, it is preferably 0.01 to 50 μm, more preferably 0.1 to 10 μm, and even more preferably 0.1 to 2 μm.

[0083] The metal plating layer may be formed in a pattern, which can function as a wiring pattern for a printed wiring board, for example.

[0084] Step 3) Next, the primer composition is cured. Curing can be carried out by heating. The heating temperature may be any temperature that allows the curing reaction of the phenoxy resin (A) and the tri- or higher functional epoxy resin (B) in the primer composition to proceed sufficiently, and may be, for example, about 60 to 400°C, preferably about 80 to 150°C. The heating time may be, for example, about 20 to 60 minutes, depending on the heating temperature. In this embodiment, this step (the step of curing the primer composition) is carried out after step 2), but it may also be carried out together with drying in step 1).

[0085] 4) Other processes The method for producing the laminate may further include other steps as necessary. For example, when a primer composition containing palladium particles is used, a step of treating the surface of the primer layer to expose a portion of the palladium particles contained in the primer layer on the surface of the primer layer may be further carried out between steps 1) and 2). Such surface treatment may be carried out, for example, by alkali treatment, plasma ashing, mechanical polishing, or the like. [Example]

[0086] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited thereto.

[0087] 1. Materials for the primer composition 1-1.Thermosetting resin (1) Phenoxy resin Phenoxy resin (A-1): jER YX8100BH30 (manufactured by Mitsubishi Chemical Corporation, polyaddition product of bisphenol S / biphenyl diglycidyl ether, weight average molecular weight: 38,000, epoxy equivalent: 10,000-20,000 g / eq, Tg: 150°C) Phenoxy resin (A-2): jER YX6954BH30 (manufactured by Mitsubishi Chemical Corporation, polyaddition product of bisphenol AP / tetramethylbiphenyl diglycidyl ether, weight average molecular weight: 39,000, epoxy equivalent: 10,000-16,000 g / eq, Tg: 130°C) Phenoxy resin (A-3): jER YX7553BH30 (Mitsubishi Chemical Corporation, special type phenoxy resin, weight average molecular weight: 35,000, epoxy equivalent: 9,000-16,000 g / eq, Tg: 155°C) Phenoxy resin (a-1): jER 4250 (Mitsubishi Chemical Corporation, a mixture of bisphenol A phenoxy resin and bisphenol F phenoxy resin, epoxy equivalent: 7500-8900 g / eq, weight-average molecular weight: 60000, Tg: 78°C)

[0088] (Tg) The Tg of the phenoxy resin is a value measured by a differential scanning calorimeter (DSC) when the temperature is increased at a rate of 10°C / minute.

[0089] (Weight average molecular weight) The weight-average molecular weight of the phenoxy resin is determined by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and is calculated as a polystyrene equivalent.

[0090] (2) Epoxy resin (2.1) Trifunctional or higher epoxy resin (B) Epoxy resin (B-1): jER 1031S (Mitsubishi Chemical Corporation, tetraphenylethane type epoxy resin, epoxy equivalent: 200 g / eq, weight average molecular weight: 800) Epoxy resin (B-2): TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc., tetrafunctional xylenediamine type epoxy resin, epoxy equivalent: 90 g / eq, molecular weight: 360.4) Epoxy resin (B-3): HP-4700 (tetrafunctional naphthalene-type epoxy resin, epoxy equivalent: 170 g / eq, molecular weight: 556.6)

[0091] (2.2) Other epoxy resins Epoxy resin (b-1): jER YL983U (Mitsubishi Chemical Corporation, bisphenol F type epoxy resin, bifunctional) Epoxy resin (b-2): jER YL828 (Mitsubishi Chemical Corporation, bisphenol A epoxy resin, bifunctional) Epoxy resin (b-3): HP-4032D (DIC Corporation, naphthalene-type epoxy resin, bifunctional)

[0092] 1-2. Hardener (1) Melamine resin (C) U-VAN 703 (Mitsui Chemicals, melamine resin)

[0093] (2) Resol phenolic resin (D) Phenolite TD-447 (DIC Corporation, resol-type phenolic curing agent, cresol-modified type)

[0094] (3) Other hardeners (E) Hardener (E-1): 2E4MZ (2-ethyl-4-methylimidazole) Curing agent (E-2): BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]propane 4,4'-isopropylidenebis[(4-aminophenoxy)benzene])

[0095] 1-3.Other (1) Palladium particles (F) Pd nanopowder (ML-001N manufactured by Iox, average particle size 5 nm)

[0096] (2) Silica particles (G) MEC-EC-2140Y (Nissan Chemical Co., Ltd., colloidal silica, average particle size 12.5 nm)

[0097] 2. Preparation and evaluation of primer compositions [Examples 1 to 14, Comparative Examples 1 to 5] (1) Preparation of primer composition A primer composition with a solids concentration of 10% was prepared by mixing 100 parts by mass of phenoxy resin (A-1), 50 parts by mass of tri- or higher functional epoxy resin (B-1), 50 parts by mass of melamine resin (C), 25 parts by mass of resol phenolic resin (D), 5 parts by mass of palladium particles (F), and 900 parts by mass of cyclohexanone, 720 parts by mass of N-methyl-2-pyrrolidone, and 450 parts by mass of 2-methoxy-1-methylethyl acetate as solvents.

[0098] (2) Application of primer composition A 25 μm-thick polyimide film was prepared as an insulating substrate. The primer composition was applied to one side of this film using a bar coater and dried in a drying oven at 150° C. for 5 minutes to form a 0.5 μm-thick layer of the primer composition.

[0099] (3) Formation of metal plating layer The film on which the primer composition layer was formed was immersed in an electroless plating bath to perform electroless plating. The electroless copper plating bath used was Thru-Cup PTU (Cu concentration 3.5 to 4.5 g / L) manufactured by Uemura Industries Co., Ltd. The electroless plating was performed at 30°C for 10 minutes, so that the thickness of the metal plating layer became 0.2 μm.

[0100] (4) Curing of the primer composition The resulting laminate was immersed in an electrolytic plating bath to perform electroplating. A common copper sulfate plating solution was used as the electrolytic copper plating bath. The electrolytic plating was performed at room temperature for 20 minutes, so that the total thickness of the metal plating layer was 15 μm. The electrolytically plated laminate was then heated in an oven at 150°C for 30 minutes to cure the primer composition. This resulted in a sample for measuring the adhesive strength of a laminate including a polyimide film, a primer layer, and a metal plating layer.

[0101] [evaluation] The initial adhesion of the primer layer in the process of producing the laminate, the adhesion after heat resistance, and the number of pinholes were evaluated by the following methods.

[0102] (1) Initial adhesion The adhesiveness of the metal plating layer of the obtained laminate was measured by a 90° peel test. Specifically, the test was performed at room temperature at a peel rate of 25 mm / min. An adhesive strength of 7 N / cm or more was judged to be good.

[0103] (2) Adhesion after heat resistance The resulting laminate was stored in an atmospheric oven at 150°C for 168 hours. Thereafter, the adhesive strength of the metal plating layer was measured using the same method and criteria as above. An adhesive strength of 5 N / cm or more was determined to be good.

[0104] (3) Pinhole amount The surface of the resulting primer layer was visually observed using a backlight, and the number of pinholes visually observed within an area of ​​50 mm x 70 mm was counted and evaluated according to the following criteria. 3: Fewer than 20 pinholes 2: 21 to less than 50 pinholes 1: 50 or more pinholes

[0105] The evaluation results of the primer compositions of Examples 1 to 9 are shown in Table 1, and the evaluation results of the primer compositions of Examples 10 to 14 and Comparative Examples 1 to 5 are shown in Table 2.

[0106] [Table 1]

[0107] [Table 2]

[0108] As shown in Table 2, the primer compositions of Comparative Examples 1 to 3, which do not contain a tri- or higher functional epoxy resin (B), and the primer composition of Comparative Example 5, which does not contain a phenoxy resin (A) with a Tg of 100°C or higher, all have low adhesion after heat resistance. On the other hand, the primer composition of Comparative Example 4, which contains a large amount of a tri- or higher functional epoxy resin (B), has low initial adhesion.

[0109] In contrast, as shown in Tables 1 and 2, the primer compositions of Examples 1 to 14, which contain at least a phenoxy resin (A) with a Tg of 100°C or higher and a predetermined amount of a tri- or higher-functional epoxy resin (B), all maintain initial adhesion and exhibit good adhesion after heat resistance, even when using a polyimide film as the substrate.

[0110] These findings indicate that by containing a phenoxy resin (A) with a Tg of 100°C or higher and a tri- or higher functional epoxy resin (B), and by using a predetermined amount of the tri- or higher functional epoxy resin (B), it is possible to maintain the initial adhesiveness while further improving the adhesiveness after heat resistance.

[0111] In particular, it is clear that by setting the content of the resol phenolic resin (D) to a predetermined amount or more, the initial adhesiveness can be further improved (comparison with Examples 12 to 14).

[0112] It is also clear that by setting the content of the tri- or higher functional epoxy resin (B) to a predetermined amount or more, the adhesiveness after heat resistance can be further improved. [Industrial Applicability]

[0113] According to the present invention, a primer composition for electroless plating can be provided that has high adhesion to a metal plating layer even when an insulating substrate with high gas permeability is used, and that can maintain adhesion even after heating at high temperatures. Therefore, the primer composition is suitable for laminates for producing printed wiring boards, particularly printed wiring boards used in devices compatible with high frequencies such as 5G.

Claims

1. a phenoxy resin (A) having a glass transition temperature (Tg) of 100°C or higher; a tri- or higher functional epoxy resin (B) having three or more epoxy groups in the molecule; Melamine resin (C) and Including, The content of the tri- or higher functional epoxy resin (B) is 10 to 75 parts by mass per 100 parts by mass of the phenoxy resin (A). A primer composition for electroless plating.

2. The weight average molecular weight of the phenoxy resin (A) is 10,000 or more and less than 50,000. The primer composition for electroless plating according to claim 1.

3. Further comprising a resol phenolic resin (D), The primer composition for electroless plating according to claim 1.

4. The content of the resol phenolic resin (D) is 10 to 40 parts by mass relative to 150 parts by mass of the total of the phenoxy resin (A) and the tri- or higher functional epoxy resin (B). The primer composition for electroless plating according to claim 3.

5. Further comprising palladium particles (F); The primer composition for electroless plating according to claim 1.

6. Further containing silica particles (G), The primer composition for electroless plating according to claim 1.

7. an insulating substrate; a primer layer disposed on the insulating substrate, the primer layer comprising a cured product of the electroless plating primer composition according to any one of claims 1 to 6; a metal plating layer disposed on the primer layer; Including, Laminate.

8. The insulating substrate has an oxygen permeability of 50 (cc / m) at 25°C measured in accordance with JIS K 7126:2006. ２ ・24h / atm) or more, The laminate according to claim 7.

9. the insulating substrate contains polyimide; The laminate according to claim 7.

10. A step of applying the electroless plating primer composition according to any one of claims 1 to 6 to a surface of an insulating substrate to form a layer of the primer composition; forming a metal plating layer on the surface of the primer composition layer by electroless plating; Including, A method for manufacturing a laminate.

11. Further comprising a step of curing the primer composition on which the metal plating layer has been formed. The method for producing the laminate according to claim 10.

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