Copper foil with resin, copper clad laminate using the same, and printed wiring board

Abstract

To provide a copper foil with a resin comprising an uncured or semi-cured resin layer, and a copper foil of a low degree of roughness using a particular maleimide resin having low dielectric characteristics and high adhesive strength, and a copper-clad laminate, a printed wiring board using the same.SOLUTION: A copper foil with a resin comprises an uncured or semi-cured heat-curable resin layer, and a copper foil, where the heat-curable resin layer includes (A) a maleimide compound having one or more dimer acid skeleton-derived hydrocarbon groups in a molecule, and (B) a heat-curable resin composition containing one or more catalysts selected from a heat radical polymerization initiator, and an anion polymerization initiator, one or more of the maleimide compound of the constituent (A) is solid at 25°C, and the ten points average roughness (Rz) of a surface degree of roughness of a face contacting the heat-curable resin layer of the copper foil is 1.5 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin-coated copper foil, and a laminate and a printed wiring board using the same. [Background technology]

[0002] In recent years, the next-generation communication system known as 5G has become popular. Furthermore, development has begun on the next-generation communication system known as 6G, which goes beyond the sub-6 6GHz band and goes beyond the millimeter wave band of 26GHz to 80GHz. To achieve even faster speeds, larger capacity, and lower latency than current systems, materials for high-frequency bands are required, and reducing transmission loss as a noise countermeasure is essential.

[0003] Transmission loss is the sum of conductor loss and dielectric loss, and reducing conductor loss requires reducing the surface roughness of the metal foil used, especially copper foil. On the other hand, since dielectric loss is proportional to the product of the square root of the relative permittivity and the dielectric loss tangent, there is a demand for the development of insulating materials with excellent dielectric properties (low relative permittivity and low dielectric loss tangent).

[0004] Particularly at high frequencies, the conductor loss is significantly affected by the skin effect, making it essential to use a material with a small surface roughness, and it is particularly preferable to use copper foil with a small surface roughness.

[0005] To reduce dielectric loss, materials with low relative permittivity and dielectric dissipation factor have come to be used, such as reactive polyphenylene ether resin (PPE) as a thermosetting resin, and liquid crystal polymer (LCP), modified polyimide (MPI) with improved properties, and even polytetrafluoroethylene (PTFE) as a thermoplastic resin. However, the adhesive strength to copper foil with a low surface roughness is generally low, and these materials are no longer suitable for practical use with low-roughness copper foil for high frequencies.

[0006] In response to this, it has been reported that maleimide compounds (special maleimide compounds) essentially having a dimer diamine skeleton are used as the main resin for substrates (Patent Documents 1 and 2). Contrary to the properties of general maleimide resins, special maleimide compounds have a low glass transition temperature (Tg) and a high coefficient of thermal expansion (CTE), but they also have excellent dielectric properties and flexibility. In addition, they have many advantages, such as excellent adhesion to metals and the possibility of (high) multilayering because they are thermosetting resins, and are therefore being extensively researched and developed.

[0007] Methods for manufacturing multilayer boards using build-up films (Patent Documents 3 to 6) are already known. However, these materials have the problem of very low adhesion to low-roughness copper foil with an Rz (ten-point average height) of 1.5 μm or less. One approach to solving this problem is to use a highly adhesive bonding film. However, this method requires the introduction of a laminating device such as a vacuum laminator, making it difficult to apply to the press-based method commonly used to make laminates.

[0008] Against this background, another method for producing multilayer boards is to use resin-coated copper foil, which is then pressed under heat to harden, followed by repeated drilling and plating to create multiple layers. This method is not widely used these days, but when using low-roughness copper foil as mentioned above, the adhesive strength of the resin used in the prepreg is becoming insufficient. Therefore, there is a demand for resin-coated copper foil that uses a resin with high adhesiveness and excellent dielectric properties.

[0009] As a countermeasure, a document has been reported on resin-coated copper foil using the special maleimide compound (Patent Document 7). However, this mainly focuses on specifying the resin viscosity to reduce defects during pressing, and there is no mention of the use of low-roughness copper foil. Furthermore, the intended use is essentially limited to flexible printed wiring boards. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2016 / 114287 [Patent Document 2] Japanese Patent Application Publication No. 2018-201024 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-90236 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-90238 [Patent Document 5] Japanese Patent Application Laid-Open No. 2014-5464 [Patent Document 6] Japanese Patent Application Laid-Open No. 2015-101626 [Patent Document 7] International Publication No. 2017 / 017923 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made to solve the above problems, and aims to provide a resin-coated copper foil consisting of a copper foil with low roughness and an uncured or semi-cured resin layer using a special maleimide resin that has low dielectric properties and high adhesive strength, and a copper foil with low roughness, as well as a copper-clad laminate and a printed wiring board that use the same, which are highly reliable and useful for high-speed communication applications. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides a resin-coated copper foil comprising an uncured or semi-cured thermosetting resin layer and a copper foil, wherein the thermosetting resin layer is (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule; (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators; The present invention provides a resin-coated copper foil, characterized in that the resin-coated copper foil contains a thermosetting resin composition comprising: the maleimide compound of component (A) being one or more selected from the following formulae (1), (2), and (3), at least one of which is solid at 25°C; and the ten-point average roughness (Rz) of the surface roughness of the copper foil on the side in contact with the thermosetting resin layer is 1.5 µm or less. [ka] (In formula (1), A's are independently tetravalent organic groups having a cyclic structure; B's are independently divalent hydrocarbon groups having 6 to 60 carbon atoms, excluding groups having a dimer acid skeleton; D's are independently groups selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, and at least one of D's is a hydrocarbon group derived from a dimer acid skeleton; m1 is 1 to 100, and m2 is 1 to 200. The order of the repeating units bounded by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. [ka] (In formula (2), A and D are the same as above, and at least one D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100.) [ka] (In formula (3), D is the same as above.)

[0013] Such a resin-coated copper foil is a resin-coated copper foil using a resin that has high adhesion and excellent dielectric properties.

[0014] Furthermore, in the present invention, it is desirable that A in the formula (1) or (2) is any one of the tetravalent organic groups represented by the following formulas. [ka]

[0015] If such a maleimide compound containing a tetravalent organic group is used, the resin-coated copper foil will have even higher adhesion and even more excellent dielectric properties.

[0016] Furthermore, in the present invention, it is desirable that the component (C) contains an epoxy resin containing two or more epoxy groups in one molecule, and the component (B) is an anionic polymerization initiator.

[0017] Such components (B) and (C) can further accelerate the curing reaction of the thermosetting resin layer of the resin-coated copper foil.

[0018] Furthermore, in the present invention, it is desirable that the thermosetting resin layer contains a glass fiber woven fabric.

[0019] Such a thermosetting resin layer can increase the strength and rigidity of the cured product.

[0020] The present invention also provides a copper-clad laminate comprising the cured resin-coated copper foil.

[0021] Such a copper clad laminate has high adhesion and excellent dielectric properties.

[0022] The present invention also provides a printed wiring board comprising the above copper-clad laminate.

[0023] Such a printed wiring board is highly reliable and useful for high-speed communication applications. [Effects of the Invention]

[0024] As described above, according to the present invention, it is possible to provide a resin-coated copper foil comprising a copper foil with low roughness and an uncured or semi-cured resin layer using a special maleimide resin having low dielectric properties and high adhesive strength, and a copper foil with low roughness, as well as a copper-clad laminate and a printed wiring board using the same, which are highly reliable and useful for high-speed communication applications. DETAILED DESCRIPTION OF THE INVENTION

[0025] As described above, there has been a demand for the development of a resin-coated copper foil consisting of an uncured or semi-cured resin layer using a special maleimide resin with low dielectric properties and high adhesive strength and a copper foil with low roughness, as well as a copper-clad laminate and a printed wiring board using the same that are highly reliable and useful for high-speed communication applications.

[0026] As a result of extensive research into the above-mentioned problems, the present inventors have found that the following resin-coated copper foil can achieve the above-mentioned object, and have thus completed the present invention.

[0027] That is, the present invention provides a resin-coated copper foil comprising an uncured or semi-cured thermosetting resin layer and a copper foil, wherein the thermosetting resin layer is (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule; (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators; The thermosetting resin composition includes The resin-coated copper foil is characterized in that the maleimide compound of component (A) is one or more compounds selected from the following formulas (1), (2), and (3), at least one of which is solid at 25°C, and the surface roughness of the copper foil on the side in contact with the thermosetting resin layer has a ten-point average roughness (Rz) of 1.5 μm or less. [ka] (In formula (1), A's are independently tetravalent organic groups having a cyclic structure; B's are independently divalent hydrocarbon groups having 6 to 60 carbon atoms, excluding groups having a dimer acid skeleton; D's are independently groups selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, and at least one of D's is a hydrocarbon group derived from a dimer acid skeleton; m1 is 1 to 100, and m2 is 1 to 200. The order of the repeating units bounded by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. [ka] (In formula (2), A and D are the same as above, and at least one D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100.) [ka] (In formula (3), D is the same as above.)

[0028] The present invention will be described in detail below, but the present invention is not limited thereto.

[0029] copper foil The copper foil used in the resin-coated copper foil of the present invention has a ten-point average roughness (Rz) of 1.5 μm or less on the surface of the copper foil that is in contact with the uncured thermosetting resin layer described below, from the viewpoint of reducing conductor loss. A small Rz is preferred to reduce conductor loss, and is preferably 1.3 μm or less, more preferably 1.0 μm or less.

[0030] There is no particular restriction on the method for producing the copper foil used, but it is generally produced by electrolysis or rolling, and electrolytic copper foil produced by electrolysis is often used.

[0031] The copper foil used may be surface-treated to improve adhesive strength, heat resistance, chemical resistance, and the like.

[0032] There are no particular restrictions on the thickness of the copper foil, but foils in the range of 6 to 50 μm are commonly used. Thinner foils, called carrier-attached copper foils, are made thicker by attaching a carrier to improve handling, and the carrier is then peeled off in a later process. Any thickness can be used in the present invention, but it is preferable to use copper foils with a thickness in the range of 6 to 35 μm.

[0033] thermosetting resin layer The thermosetting resin layer used in the resin-coated copper foil of the present invention is a layer containing a thermosetting resin containing the following components (A) and (B) as essential components: (A) A maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule (B) One or more catalysts selected from thermal radical polymerization initiators and anionic polymerization initiators

[0034] This thermosetting resin is characterized by being in an uncured or semi-cured state. Here, the uncured state refers to a so-called A-stage state, which means either the thermosetting resin itself that has not been cured at all, or a thermosetting resin varnished with a solvent or the like, which is applied to form a film and the solvent has been evaporated. Here, the semi-cured state refers to a so-called B-stage state, which means the thermosetting resin has been cured to a degree that does not reach a completely cured state.

[0035] Each of the components of the thermosetting resin forming the thermosetting resin layer of the present invention will be described in detail below. (A) A maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule The component (A) of the present invention is a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton per molecule, as represented by the following formula (1), (2), or (3): Since the component (A) has a hydrocarbon group derived from a dimer acid skeleton, the cured product of a composition containing the component (A) has a low dielectric constant and dielectric dissipation factor, and also exhibits excellent film-forming properties and handleability after curing. Furthermore, since the component (A) has an imide group, the composition containing the component (A) has high insulating properties even when formed into a film (thin film).

[0036] The maleimide compound of component (A) contains at least one, preferably two or more, of the maleimide compounds represented by formulas (1), (2), and (3), and at least one of the maleimide compounds represented by formulas (1), (2), and (3) is solid at 25° C. By containing such a solid maleimide compound, the uncured resin layer has excellent film properties and reduced tackiness, thereby improving the handleability of the resin-coated copper foil. [ka] (In formula (1), A's are independently tetravalent organic groups having a cyclic structure; B's are independently divalent hydrocarbon groups having 6 to 60 carbon atoms, provided that they do not include groups having a dimer acid skeleton; D's are independently groups selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, and at least one of D's is a hydrocarbon group derived from a dimer acid skeleton; m1 is 1 to 100, and m2 is 1 to 200. The order of the repeating units bounded by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. [ka] (In formula (2), A and D are the same as above, and at least one D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100.) [ka] (3) (In formula (3), D is the same as above.)

[0037] In addition, it is preferable to use a dimer acid having a high purity, that is, a ratio of dimer acid to the skeleton derived from dimer acid and trimer acid of 95% by mass or more, because this has excellent dielectric properties, tends to reduce viscosity when heated, provides excellent moldability, and tends to be less affected by moisture absorption.

[0038] The dimer acid referred to here is a liquid dibasic acid primarily composed of a 36-carbon dicarboxylic acid, produced by dimerization of an 18-carbon unsaturated fatty acid derived from natural sources such as vegetable oils. Dimer acids do not have a single skeleton but rather have multiple structures, resulting in multiple isomers. Representative dimer acids are classified as linear (a), monocyclic (b), aromatic (c), and polycyclic (d). In this specification, the dimer acid skeleton refers to a group derived from a dimer diamine having a structure in which the carboxy groups of such a dimer acid are substituted with primary aminomethyl groups. In other words, the dimer acid skeleton of component (A) is preferably a group in which two carboxy groups in each of the dimer acids shown below (a) to (d) are substituted with methylene groups.

[0039] Furthermore, from the viewpoint of the heat resistance and reliability of the cured product, it is more preferable that the hydrocarbon group derived from the dimer acid skeleton in the maleimide compound of component (A) has a structure in which the carbon-carbon double bond in the hydrocarbon group derived from the dimer acid skeleton is reduced by a hydrogenation reaction.

[0040] [ka]

[0041] First, although the maleimide compound represented by the formula (1) has a high melt viscosity before curing, it has better dielectric properties than typical maleimide compounds containing many aromatic groups. Furthermore, it has high adhesion to copper foil, absorbs less moisture than typical thermosetting resins such as epoxy resins, and is less affected by moisture. Furthermore, it has a higher Tg and a smaller coefficient of thermal expansion (CTE) than the maleimide compound having a dimer acid skeleton represented by the formula (2) described below, resulting in a highly reliable composition.

[0042] Furthermore, trimer acid here is essentially a by-product generated during the synthesis of dimer acid. Trimer acid is a tribasic acid whose main component is a 54-carbon tricarboxylic acid, produced from the trimer of an 18-carbon unsaturated fatty acid derived from natural sources such as vegetable oils. Like dimer acid, trimer acid does not have a single skeleton but rather has multiple structures, resulting in the existence of multiple isomers.

[0043] In addition, in the formula (1), A independently represents a tetravalent organic group having a cyclic structure, and among these, it is preferable that A is any of the tetravalent organic groups represented by the following formulas. [ka]

[0044] In the formula (1), D's are independently selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, preferably 8 to 60 carbon atoms, and more preferably 10 to 55 carbon atoms. Among these, the divalent alicyclic hydrocarbon group is preferably a branched divalent alicyclic hydrocarbon group in which one or more hydrogen atoms are substituted with an alkyl or alkenyl group having 6 to 60 carbon atoms, preferably 8 to 60 carbon atoms, and more preferably 10 to 55 carbon atoms. The branched divalent alicyclic hydrocarbon group may be either a saturated aliphatic hydrocarbon group or an unsaturated hydrocarbon group, and may have an alicyclic structure or an aromatic ring structure in the middle of the molecular chain.

[0045] Specific examples of the group selected from the divalent aliphatic hydrocarbon group and the divalent aromatic hydrocarbon group include the divalent alicyclic hydrocarbon group derived from the diamine at both ends, called dimer diamine, and one or more hydrocarbon groups derived from this dimer acid skeleton are contained in one molecule.

[0046] In addition, in the formula (1), B's are independently divalent hydrocarbon groups having 6 to 60 carbon atoms. In particular, B's are independently divalent aliphatic hydrocarbon groups having 6 to 60 carbon atoms or aromatic hydrocarbon groups having 6 to 60 carbon atoms. Preferably, B's are divalent aliphatic hydrocarbon groups or aromatic hydrocarbon groups having 6 to 30 carbon atoms. The divalent hydrocarbon groups may have a cyclic structure or a branched structure, but do not include groups having a dimer acid skeleton such as those in D above. The divalent aromatic hydrocarbon groups may have a bond directly to the aromatic ring, or may be bonded to the aromatic ring via a linear or branched divalent aliphatic hydrocarbon group.

[0047] In the formula (1), m1 is 1 to 100, preferably 1 to 60, and more preferably 2 to 50. m2 is 1 to 200, preferably 1 to 100, more preferably 1 to 50, and even more preferably 1 to 40. In particular, it is preferable that m1+m2 is in the range of 2 to 40 from the viewpoints of the film properties, moldability, strength, etc. of the composition. On the other hand, if m1 or m2 is too large, the flowability may decrease, and moldability may be poor.

[0048] The order of the repeating units bounded by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. Among these, block bonding is preferred from the viewpoint of facilitating a high Tg.

[0049] Next, the maleimide compound represented by the formula (2) has superior dielectric properties compared to other common maleimide compounds containing many aromatic groups. In particular, it is effective in maintaining dielectric properties even at high frequencies, and also has stronger adhesion to copper foil and other resins than the compound represented by the formula (1), resulting in an excellent composition.

[0050] In the formula (2), A is the same as A in the formula (1), and independently represents a tetravalent organic group having a cyclic structure, and the preferred examples are also the same.

[0051] In the formula (2), n is 1 to 100, preferably 1 to 60, and more preferably 1 to 50. If n is too large, the solubility and flowability may decrease, and moldability may be poor.

[0052] Next, the use of the maleimide compound represented by formula (3) provides superior dielectric properties compared to other common maleimide compounds containing multiple aromatic groups. It is particularly effective in maintaining dielectric properties even at high frequencies. Furthermore, because it is a liquid at room temperature, it improves the moldability of the resin composition of the present invention and improves handling, such as film properties before curing.

[0053] Therefore, when using the maleimide compound represented by formula (3), it is preferable to use it in combination with one or more of the compounds represented by formula (1) and formula (2).

[0054] The viscosity of component (A) is preferably in the range of 1.0 to 5.0 Pa·s as measured at 25°C at 5 rpm using a cone-plate rotational viscometer in accordance with JIS Z 8803:2011.

[0055] The number average molecular weight of the maleimide compound of component (A) is not particularly limited, but from the viewpoint of the handleability of the composition, it is preferably 1,500 to 50,000, more preferably 2,000 to 30,000. Furthermore, component (A) may contain not only maleimide compounds of formula (1), (2), or (3) but also other maleimide compounds, and either one or more maleimide compounds may be used, but as mentioned above, when formula (3) is used, it is preferable that at least one of formula (1) or formula (2) is included.

[0056] The number average molecular weight referred to in the present invention refers to the number average molecular weight measured by gel permeation chromatography (GPC) under the following conditions using polystyrene as a standard substance.

[0057] [Measurement conditions] Developing solvent: tetrahydrofuran (THF) Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperHZ4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ2000 (4.6mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass THF solution)

[0058] (B) One or more catalysts selected from thermal radical polymerization initiators and anionic polymerization initiators Component (B) is a catalyst for accelerating the curing reaction of the thermosetting resin layer of the resin-coated copper foil of the present invention. It is added to initiate and accelerate the crosslinking reaction of the maleimide compound (component (A)) and the reaction between the maleimide group in component (A) and a reactive group that can react with the maleimide group. The catalyst is selected from the group consisting of thermal radical polymerization initiators and anionic polymerization initiators.

[0059] When it is desired to promote the reaction of component (A) alone, a thermal radical polymerization initiator is preferred. Furthermore, when component (E), which will be described later, is contained, and the reactive group is a group having a carbon-carbon double bond such as a maleimide group, an alkenyl group, or a (meth)acrylic group, a thermal radical polymerization initiator is also preferred.

[0060] Examples of thermal radical polymerization initiators include azo compounds, organic peroxides, and sulfates, with organic peroxides being preferred. Organic peroxides are classified into allyl peroxide, dialkyl peroxide, peroxide carbonate, hydroperoxide, and the like, but are not particularly limited. Specific examples include dicumyl peroxide, t-butyl peroxybenzoate, t-amyl peroxybenzoate, dibenzoyl peroxide, diuraroyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-di(t-butylperoxy)cyclohexane, di-t-butyl peroxide, and dibenzoyl peroxide.

[0061] Furthermore, when the reactive group capable of reacting with the maleimide group in component (E), which will be described later, is an epoxy group, a hydroxyl group, or an acid anhydride group, an anionic polymerization catalyst such as a basic compound such as imidazoles or tertiary amines, or an organic phosphorus compound is preferred. Although it is possible to use imidazoles or amines for the homopolymerization of the maleimide group, care must be taken, as imidazoles and phosphorus compounds require extremely high temperatures, and amines tend to have an extremely short pot life.

[0062] In particular, when the component (C) described below is contained, the component (B) acts as an anionic polymerization catalyst. Examples of the anionic polymerization catalyst include basic compounds such as the imidazoles and tertiary amines described above, and organic phosphorus compounds, with the imidazoles being particularly preferred.

[0063] The amount of component (B) is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of component (A). When other thermosetting resins, as described below, are incorporated into the composition, the amount is preferably 0.05 to 10 parts by mass, particularly 0.1 to 5 parts by mass, per 100 parts by mass of the total of component (A) and other thermosetting resin components. A content within the above range is preferred because the curing properties are stable during molding of the thermosetting resin film of the present invention. Furthermore, the resulting cured product has a good balance between heat resistance and moisture resistance, which is also preferred. The catalyst of component (B) may be used alone or in combination of two or more different types.

[0064] In the resin-coated copper foil of the present invention, the thickness of the uncured thermosetting resin layer to be laminated is not particularly specified, but is preferably in the range of 1 to 150 μm, more preferably 1 to 40 μm. Note that when a glass fiber woven fabric described later is included, its thickness must be taken into consideration, and it is preferably in the range of 40 to 125 μm.

[0065] Other additives The thermosetting resin layer of the present invention may further contain various additives as required, examples of which are listed below.

[0066] (C) Epoxy resin with two or more epoxy groups in one molecule When an anionic polymerization catalyst is used as component (B) in the thermosetting resin layer of the resin-coated copper foil of the present invention, an epoxy resin having two or more epoxy groups per molecule can be used as component (C). The epoxy groups in the epoxy resin react with the anionic polymerization catalyst in component (B) to generate active species, which then react with the maleimide groups in component (A) to initiate anionic polymerization.

[0067] Taking into consideration the reactivity with component (B), component (C) is preferably an epoxy resin having a glycidyl group.

[0068] Examples of component (C) include phenol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenol type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins, naphthol type epoxy resins, xylylene type epoxy resins, biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, triphenylmethane type epoxy resins, alicyclic type epoxy resins, glycidylamine type epoxy resins, dicyclopentadiene type epoxy resins, stilbene type epoxy resins, sulfur atom-containing epoxy resins, and phosphorus atom-containing epoxy resins. It is preferable to use component (C) that is liquid at room temperature (25°C) from the viewpoints of compatibility and wettability with the substrate.

[0069] The amount of component (C) blended is preferably 0.05 to 25 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the total thermosetting resin including component (A). Within the above range, the curing speed during molding becomes appropriate, which is preferable. Furthermore, the resulting cured product has a good balance between heat resistance and moisture resistance. The desired low dielectric properties are also achieved.

[0070] The epoxy resin of component (C) may be used alone or in combination of two or more different types.

[0071] (D) Inorganic filler The thermosetting resin layer of the present invention may further contain (D) an inorganic filler. The inorganic filler is blended for the purposes of increasing the strength and rigidity of the cured product of the thermosetting resin layer in the resin-coated copper foil of the present invention, or adjusting the thermal expansion coefficient and dimensional stability of the cured product. As the inorganic filler, those typically blended in epoxy resin compositions or silicone resin compositions can be used. However, silica particles such as spherical silica, fused silica, and crystalline silica, or boron nitride are preferred so as not to increase the dielectric constant of the entire composition.

[0072] The average particle size and shape of the inorganic filler are not particularly limited, but from the viewpoint of the processability of the substrate, spherical silica having an average particle size of 0.5 to 5 μm is preferably used. The average particle size is the mass average particle size D 50 (or median diameter).

[0073] Furthermore, in order to improve the properties of the inorganic filler, it is preferable that the surface of the filler is treated with a silane coupling agent having an organic group capable of reacting with a maleimide group, such as an epoxy group-containing alkoxysilane, an amino group-containing alkoxysilane, a (meth)acrylic group-containing alkoxysilane, or an alkenyl group-containing alkoxysilane.

[0074] As the silane coupling agent, a (meth)acrylic group- and / or amino group-containing alkoxysilane is preferably used, and specific examples thereof include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane.

[0075] The inorganic filler may be used alone or in combination of two or more. The amount of inorganic filler added is 0 to 500 parts by mass, preferably 0 to 400 parts by mass, per 100 parts by mass of component (A).

[0076] (E) A thermosetting resin having a reactive group capable of reacting with a maleimide group In the present invention, a thermosetting resin having a reactive group capable of reacting with a maleimide group may be further added to the thermosetting resin layer as component (E), although components corresponding to the aforementioned component (C) are not included in component (E).

[0077] There are no limitations on the type of component (E), and examples include various resins other than component (A), such as melamine resins, silicone resins, cyclic imide resins including maleimide compounds other than component (A), urea resins, thermosetting polyimide resins, modified polyphenylene ether resins, thermosetting acrylic resins, epoxy-silicone hybrid resins, etc. Furthermore, phenolic curing agents, amine curing agents, acid anhydride curing agents, and active ester curing agents used as curing agents for epoxy resins are also included here.

[0078] Examples of reactive groups that can react with a maleimide group include a maleimide group, a hydroxyl group, an acid anhydride group, an alkenyl group such as an allyl group or a vinyl group, a (meth)acrylic group, and a thiol group.

[0079] From the viewpoint of reactivity, the reactive group of component (E) is preferably selected from a maleimide group, a hydroxyl group, and an alkenyl group, and from the viewpoint of dielectric properties, an alkenyl group or a (meth)acrylic group is more preferred.

[0080] However, the blending amount of the component (E) is preferably 0 to 60 mass % of the total amount of the thermosetting resin (that is, the total amount of the components (A), (C), and (E)).

[0081] Glass fiber woven fabric In the present invention, the thermosetting resin layer may further contain a glass fiber woven fabric. In other words, the thermosetting resin layer alone may have the same configuration as a prepreg. Examples of glass fiber woven fabric include E-glass, low-dielectric glass, quartz glass, S-glass, T-glass, etc., and the type of glass used is not critical. However, quartz glass cloth, which has low dielectric properties, is preferred from the perspective of utilizing the properties of the thermosetting maleimide resin composition. Furthermore, the glass fiber woven fabric may be present either inside or on the surface of the thermosetting resin layer, but is preferably present inside the thermosetting resin layer from the perspectives of appearance, processability, etc. The thickness of commonly used glass fiber woven fabric is, for example, 10 μm or more and 100 μm or less.

[0082] others In addition to the above, non-functional silicone oil, reactive diluent, thermoplastic resin, thermoplastic elastomer, organic synthetic rubber, photosensitizer, light stabilizer, polymerization inhibitor, flame retardant, pigment, dye, adhesion aid, ion trapping material, etc. may be blended.

[0083] In addition, silane coupling agents such as epoxy group-containing alkoxysilanes, amino group-containing alkoxysilanes, (meth)acrylic group-containing alkoxysilanes, and alkenyl group-containing alkoxysilanes, which are used to surface treat the above-mentioned inorganic fillers, may be separately blended into the uncured or semi-cured thermosetting resin layer of the resin-coated copper foil of the present invention, or may be used to surface treat the copper foil. Specific examples of silane coupling agents include those mentioned above.

[0084] The method for producing the resin-coated copper foil of the present invention is not particularly limited, but examples thereof include the following.

[0085] First, the thermosetting resin is dissolved in an organic solvent to form a varnish, which is then directly applied to the surface of the copper foil and dried. When preparing the varnish, any organic solvent can be used as long as it dissolves the thermosetting resin having a reactive group capable of reacting with the maleimide group as component (A) or other additive. Examples include anisole, tetralin, mesitylene, xylene, toluene, tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone. However, aromatic organic solvents such as anisole, tetralin, mesitylene, xylene, and toluene are preferred. These may be used alone or in combination of two or more.

[0086] For example, after applying a thermosetting resin (varnish) dissolved in an organic solvent to the substrate, the organic solvent is removed by heating for 0.5 to 20 minutes at a temperature of typically 80°C or higher, preferably 100°C or higher. A temperature of 130°C or lower is preferred because it prevents oxidation of the copper foil.

[0087] The temperature in the drying step for removing the organic solvent may be constant, but the temperature may also be increased stepwise, which allows the organic solvent to be efficiently removed from the composition.

[0088] The method for applying the varnish includes, but is not particularly limited to, a gravure coater, a die coater, a spin coater, a slit coater, a spray coater, a dip coater, a bar coater, and the like.

[0089] Alternatively, similar to the above, a thermosetting resin may be dissolved in an organic solvent to form a varnish, which may then be applied to a release-treated polyethylene terephthalate (PET) film, the solvent may be dried to form a film, which may then be attached to copper foil, and the PET film may be peeled off to obtain a resin-coated copper foil. The lamination conditions are not particularly limited, but it is preferable to perform lamination while heating at a temperature of 80 to 130°C, at 0.1 to 1.0 MPa, and for 0.5 to 5 minutes.

[0090] As another method, the components may be premixed in advance and extruded into a film using a melt kneader, which can then be used as is (extrusion molding).

[0091] The resin-coated copper foil of the present invention can be used for copper-clad laminates and printed wiring boards. The printed wiring board is not limited to flexible boards, but can also be used for rigid boards.

[0092] The method for producing a copper-clad laminate is not particularly limited, but a typical method involves using a vacuum laminator to attach the resin surface of the resin-coated copper foil of the present invention to a prepreg, its cured product, or a polyimide or liquid crystal polymer (LCP) film such as is used in flexible printed wiring boards, and then pressing or laminating the laminate while heating, followed by curing the laminate in that state to produce a copper-clad laminate.

[0093] In this case, the lamination conditions are not particularly limited, but lamination is preferably performed while heating at a temperature of 80 to 130°C, at 0.1 to 1.0 MPa, and for 0.5 to 5 minutes. The pressing conditions are also not particularly limited, but pressing is preferably performed while heating at a temperature of 150 to 200°C, at 0.1 to 1.0 MPa, and for 0.5 to 2 hours. Even when heat curing is performed without pressing, the heating temperature and time are preferably within the above conditions.

[0094] The method for producing a printed wiring board is not particularly limited, but for example, a general method for producing a rigid board is to form a circuit on a copper-clad laminate produced by the above-mentioned method, such as a subtractive method, by pattern etching.A flexible board is also not particularly limited, but for example, a general method for producing a flexible board is to form a circuit on a copper-clad laminate produced by the above-mentioned method by pattern etching, and then thermocompression bonding a coverlay. [Example]

[0095] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0096] (A) Maleimide compound (A-1): A hydrocarbon group-containing bismaleimide compound derived from a dimer acid skeleton, represented by the following formula (SLK-2600, manufactured by Shin-Etsu Chemical Co., Ltd., solid at 25°C) [ka] -C 36 H 70 - indicates a structure derived from a dimer acid skeleton. m1≒5, m2≒1 (A-2): A hydrocarbon group-containing bismaleimide compound derived from a dimer acid skeleton, represented by the following formula (trade name: BMI-3000J, manufactured by Designer Molecules Inc., solid at 25°C) [ka] -C 36 H 70 - indicates a structure derived from a dimer acid skeleton. (A-3): A hydrocarbon group-containing bismaleimide compound derived from a dimer acid skeleton represented by the following formula (trade name: BMI-1500, manufactured by Designer Molecules Inc., syrup-like at 25°C) [ka] (A-4): A hydrocarbon group-containing bismaleimide compound derived from a dimer acid skeleton, represented by the following formula (trade name: BMI-689, manufactured by Designer Molecules Inc., liquid at 25°C) [ka]

[0097] Comparative Example Compound (A-5): 4,4'-diphenylmethane bismaleimide (trade name: BMI-1000, manufactured by Daiwa Chemical Industry Co., Ltd., solid at 25°C) (A-6): Aromatic bismaleimide compound represented by the following formula (trade name: SLK-6200, manufactured by Shin-Etsu Chemical Co., Ltd., solid at 25°C) [ka]

[0098] (B) One or more catalysts selected from thermal radical polymerization initiators and anionic polymerization initiators (B-1): Dicumyl peroxide (trade name: Percumyl D, manufactured by NOF Corporation) (B-2): 1-benzyl-2-phenylimidazole (trade name: 1B2PZ, manufactured by Shikoku Chemical Industries, Ltd.)

[0099] (C) Epoxy resin with two or more epoxy groups in one molecule (C-1): Bisphenol A liquid epoxy resin (trade name: jER-828, manufactured by Mitsubishi Chemical Corporation) (C-2): Multifunctional epoxy resin (product name: EPPN-501, manufactured by Nippon Kayaku Co., Ltd.)

[0100] (D) Inorganic filler (D-1): A slurry containing spherical silica particles with an average particle size of 0.5 μm and a solid concentration of 75% by mass, dispersed in toluene (product name: 5SV-CT1, manufactured by Admattex Co., Ltd.)

[0101] (E) A thermosetting resin having a reactive group capable of reacting with a maleimide group (E-1): Methacrylic-terminated polyphenylene ether resin (product name: SA-9000, manufactured by SABIC) (F) Material for comparison (F-1): Hydrogenated styrene-based thermoplastic elastomer (SEBS) (product name: Tuftec H1041, manufactured by Asahi Kasei Corporation) (F-2): Phenol novolac resin (trade name: Phenolite TD-2131, manufactured by DIC Corporation) (F-3): Low dielectric build-up film (thickness 15 μm, product name: GL-102, manufactured by Ajinomoto Co., Inc.) (F-4): Low dielectric prepreg (#1035, product name: Megtron7 R-5785(N), manufactured by Panasonic Industries Co., Ltd.)

[0102] copper foil Rz=1.0μm; Product name: CF-T4X-SV-18, thickness: 18μm, manufactured by Fukuda Metal Foil and Powder Co., Ltd. Rz=5.0μm; product name: 3EC-III, thickness: 18μm, manufactured by Mitsui Mining & Smelting Co., Ltd.

[0103] Glass fiber woven fabric Quartz glass cloth (#1035, product name: SQX); thickness 25 μm, manufactured by Shin-Etsu Chemical Co., Ltd.

[0104] Preparation of resin varnish The components shown in Tables 1 and 2 were added to a 500 mL four-neck flask equipped with a Dimroth condenser and a stirrer according to the formulations in Tables 1 and 2, stirred at 80°C for 4 hours, and filtered through a 100-mesh wire screen to obtain a varnish-like resin composition.

[0105] <Preparation of resin-coated copper foil without glass fiber woven fabric> The varnish-like resin composition prepared above was applied to the matte surface of the copper foil using a roller coater, and a resin-coated copper foil having a 5 μm thick uncured or semi-cured resin layer was produced under the conditions shown in Tables 1 and 2.

[0106] <Preparation of resin-coated copper foil with glass fiber woven fabric> The resin varnish prepared above was impregnated into a glass fiber woven fabric substrate at room temperature and dried under the conditions shown in Tables 1 and 2. The resin content (content of the resin composition) and thickness of the resulting prepreg are shown in Tables 1 and 2, respectively. The uncured resin or semi-cured prepreg thus obtained was laminated onto the matte surface of the above copper foil using a batch-type vacuum laminator (manufactured by Nikko Materials Co., Ltd.) at 100°C, 0.5 MPa pressure, and for 60 seconds to produce resin-coated copper foil with glass fiber woven fabric.

[0107] The comparative product (F-3) is not a prepreg but a film product, and the cover film was peeled off, the resin side was placed on the copper foil, and then laminated to the copper foil in the same manner as above under the same conditions to produce a resin-coated copper foil. In this case, the base film was peeled off before use.

[0108] As for the comparative example (F-4), since it was already a prepreg, the prepreg manufacturing process was omitted, and a resin-coated copper foil was produced by laminating it onto a copper foil in the same manner.

[0109] <Handling of resin-coated copper foil> The handleability of the resin-coated copper foils prepared as described above was checked. Those that could be wrapped around a 3-inch diameter ABS tube and used without any problems were marked as ○, those that cracked or peeled off the resin layer when wrapped around a 3-inch diameter ABS tube were marked as ×, and those that had severe tack in the thermosetting resin layer and became dirty during wrapping were marked as △. × and △ were not evaluated further.

[0110] <Peel strength> A 75mm long, 25mm wide, and 1.0mm thick SUS304 plate was prepared. One of the resin-coated copper foils prepared above was cut to a length of 150mm long and a width of 10mm, and the uncured or semi-cured resin layer was placed on top. The laminate was then laminated at 120°C, 0.8MPa pressure, and 60 seconds. After lamination, the laminate was cured by heating at 180°C for 2 hours in a nitrogen atmosphere to prevent copper oxidation, producing adhesive test specimens. To evaluate adhesiveness, the 90° peel strength (kN / m) of each adhesive test specimen was measured at 23°C and a pulling rate of 50mm / min according to JIS C6481:1996.

[0111] <Heat resistance test> Five test pieces were prepared for the peel test described above, and treated for one hour in a thermostatic chamber equipped with an air circulator set at 300°C. Test pieces that showed no abnormalities were rated as "○", and test pieces that showed "blistering" or "peeling" in one or more samples out of the five were rated as "×".

[0112] <Transmission loss measurement> Two sheets of low dielectric prepreg (#2016, product name: Megtron7 R-5785(N), manufactured by Panasonic Industries Co., Ltd.) were stacked together, and the 5 μm thick resin-coated copper foil prepared as described above was placed on both sides. The laminate was heated and pressed at a temperature of 200°C for 2 hours at a pressure of 3 MPa to obtain a copper-clad laminate for evaluation with a thickness of approximately 250 μm.

[0113] Next, one side of the double-sided board obtained above, both sides of which were resin-coated copper foil, was processed to a line width of 100 to 200 μm, and then the line width was finished by etching, and the characteristic impedance of the circuit was adjusted to 50 Ω.

[0114] The transmission loss of the resulting laminate was evaluated using a network analyzer (manufactured by Keysight Technologies) at a frequency of 40 GHz.

[0115] [Table 1] [Table 2] *Due to tack, exact values ​​could not be obtained.

[0116] From the above, the usefulness of the resin-coated copper foil of the present invention was confirmed from the viewpoints of adhesive strength and transmission loss.

[0117] This specification includes the following inventions.

[0118] [1]: A resin-coated copper foil consisting of an uncured or semi-cured thermosetting resin layer and a copper foil, The thermosetting resin layer (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule; (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators; The thermosetting resin composition includes The resin-coated copper foil is characterized in that the maleimide compound of the component (A) is one or more selected from the following formulas (1), (2), and (3), at least one of which is solid at 25°C, and the ten-point average roughness (Rz) of the surface roughness of the copper foil on the side in contact with the thermosetting resin layer is 1.5 μm or less. [ka] (In formula (1), A's are independently tetravalent organic groups having a cyclic structure; B's are independently divalent hydrocarbon groups having 6 to 60 carbon atoms, excluding groups having a dimer acid skeleton; D's are independently groups selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, and at least one of D's is a hydrocarbon group derived from a dimer acid skeleton; m1 is 1 to 100, and m2 is 1 to 200. The order of the repeating units bounded by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. [ka] (In formula (2), A and D are the same as above, and at least one D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100.) [ka] (In formula (3), D is the same as above.) [2]: The resin-coated copper foil according to [1], wherein A in the formula (1) or (2) is any one of tetravalent organic groups represented by the following formulas: [ka] [3]: The resin-coated copper foil according to [1] or [2], further comprising, as component (C), an epoxy resin containing two or more epoxy groups in one molecule, and the component (B) is an anionic polymerization initiator. [4]: The resin-coated copper foil according to any one of [1] to [3], wherein the thermosetting resin layer further comprises a glass fiber woven fabric. [5]: A copper-clad laminate comprising a cured product of the resin-coated copper foil according to any one of [1] to [4]. [6]: A printed wiring board comprising the copper clad laminate according to [5].

[0119] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A resin-coated copper foil consisting of an uncured or semi-cured thermosetting resin layer and a copper foil, The thermosetting resin layer (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule; (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators; The thermosetting resin composition includes The maleimide compound of the component (A) is one or more compounds selected from the following formulas (1), (2), and (3), at least one of which is solid at 25°C, and the surface roughness of the copper foil on the side in contact with the thermosetting resin layer has a ten-point average roughness (Rz) of 1.5 µm or less. [Chemical 1] (In formula (1), A's are independently tetravalent organic groups having a cyclic structure; B's are independently divalent hydrocarbon groups having 6 to 60 carbon atoms, excluding groups having a dimer acid skeleton; D's are independently groups selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, and at least one of D's is a hydrocarbon group derived from a dimer acid skeleton; m1 is 1 to 100, and m2 is 1 to 200. The order of the repeating units bounded by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. 【Chemistry 2】 (In formula (2), A and D are the same as above, and at least one D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100.) 【Chemistry 3】 (In formula (3), D is the same as above.)

2. 2. The resin-coated copper foil according to claim 1, wherein A in the formula (1) or (2) is any one of tetravalent organic groups represented by the following formulas: 【Chemistry 4】

3. 2. The resin-coated copper foil according to claim 1, further comprising an epoxy resin containing two or more epoxy groups in one molecule as component (C), and said component (B) being an anionic polymerization initiator.

4. 2. The resin-coated copper foil according to claim 1, wherein the thermosetting resin layer further comprises a glass fiber woven fabric.

5. A copper-clad laminate comprising the cured resin-coated copper foil according to any one of claims 1 to 4.

6. A printed wiring board comprising the copper clad laminate according to claim 5.

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