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

Abstract

The invention provides a copper foil with resin, and a copper-clad laminate and a printed wiring board using the copper foil with resin. The copper foil with resin is composed of an uncured or semi-cured resin layer and a copper foil with low roughness, wherein the uncured or semi-cured resin layer uses special maleimide resin with low dielectric characteristics and high adhesive force. The copper foil with resin is composed of an uncured or semi-cured thermosetting resin layer and a copper foil, and is characterized in that the thermosetting resin layer contains a thermosetting resin composition; the thermosetting resin composition contains (A) one or more maleimide compounds selected from the group consisting of formulas (1), (2) and (3), and (B) one or more catalysts selected from the group consisting of thermal radical polymerization initiators and anionic polymerization initiators, the one or more of the components (A) being solid at 25 DEG C, and the one or more of the components (B) being solid at 25 DEG C; the ten-point average roughness (Rz) of the surface roughness of the surface of the copper foil in contact with the thermosetting resin layer is 1.5 [mu] m or less. .

Description

Technical Field

[0001] The present invention relates to a copper foil with resin, and a laminate and a printed wiring board using the copper foil with resin. Background Art

[0002] In recent years, next-generation communication systems such as 5G have become increasingly popular. Furthermore, development of even higher-generation communication systems such as 6G is underway, extending beyond the 26GHz to 80GHz millimeter wave bands, using frequency bands below 6GHz, such as Sub-6. To achieve communications exceeding current high speeds, high capacity, and low latency, high-frequency band materials are required, and as a noise countermeasure, transmission loss must be reduced.

[0003] Transmission loss is the sum of conductor loss and dielectric loss. To reduce conductor loss, the surface roughening of the metal foil used, particularly copper foil, is necessary. Meanwhile, since dielectric loss is proportional to the product of the square root of the relative dielectric constant and the loss tangent, there is a demand for the development of insulating materials with excellent dielectric properties (low relative dielectric constant and low loss tangent).

[0004] In particular, at high frequencies, conductor loss is greatly affected by the skin effect, and a material with a small surface roughness is required. In particular, copper foil with a low surface roughness is preferably used.

[0005] To reduce dielectric loss, reactive polyphenylene ether resin (PPE), a thermosetting resin, liquid crystal polymer (LCP), a thermoplastic resin, modified polyimide (MPI), and polytetrafluoroethylene (PTFE) are used as materials with low relative dielectric constant and loss tangent. However, these materials generally have low adhesion to copper foil with low surface roughness and are not suitable for practical use in low-roughness copper foil for high-frequency applications.

[0006] In this regard, there are reports of using maleimide compounds (special maleimide compounds) essentially having a dimer diamine skeleton as a main resin for substrates (Patent Documents 1 and 2). In contrast to the properties of conventional maleimide resins, special maleimide compounds, while having a low glass transition temperature (Tg) and a high coefficient of thermal expansion (CTE), exhibit exceptionally excellent dielectric properties and possess flexible properties. Furthermore, due to their excellent adhesion to metals and their thermosetting nature, they offer numerous advantages, such as the potential for (high) multilayering, leading to extensive research and development.

[0007] As a method for producing multilayer substrates, methods using build-up films (Patent Documents 3 to 6) are known. However, these materials have a problem of very low adhesion to low-roughness copper foils, such as copper foils with an Rz (ten-point average roughness) of less than 1.5 μm. To address these problems, the use of highly adhesive adhesive films is being considered. However, this processing method requires the introduction of a laminating device such as a vacuum laminator, making it difficult to apply to processing methods using conventional presses used to produce laminates.

[0008] Against this backdrop, another method for processing multilayer substrates involves using a resin-coated copper foil, pressing it under heat to cure it, and then repeatedly performing processes such as drilling and plating to create multiple layers. This processing method has been less commonly used recently, but when using low-roughness copper foils such as those described above, the adhesion of the resin used in the prepreg has been insufficient. Therefore, there is a need for a resin-coated copper foil using a resin that exhibits high adhesion and excellent dielectric properties.

[0009] As a countermeasure, a document (Patent Document 7) reports on resin-coated copper foil using the aforementioned special maleimide compound. However, the document primarily regulates the viscosity of the resin to reduce defects during pressing and contains no description of the use of copper foil with low roughness. Furthermore, the proposed application is essentially limited to flexible printed wiring boards.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: International Publication No. 2016 / 114287

[0013] Patent Document 2: Japanese Patent Application Publication No. 2018-201024

[0014] Patent Document 3: Japanese Patent Application Laid-Open No. 2010-90236

[0015] Patent Document 4: Japanese Patent Application Laid-Open No. 2010-90238

[0016] Patent Document 5: Japanese Patent Application Laid-Open No. 2014-5464

[0017] Patent Document 6: Japanese Patent Application Laid-Open No. 2015-101626

[0018] Patent Document 7: International Publication No. 2017 / 017923 Summary of the Invention

[0019] (1) Technical issues to be resolved

[0020] The present invention has been made to solve the above-mentioned problems, and its object is to provide a copper foil with resin, and a copper-clad laminate and a printed wiring board using the copper foil with resin. The copper foil with resin is composed of an uncured or semi-cured resin layer and a copper foil with low roughness, and the uncured or semi-cured resin layer uses a special maleimide resin with low dielectric properties and high adhesion. The copper-clad laminate and printed wiring board have high reliability and are useful for high-speed communication applications.

[0021] (2) Technical solution

[0022] In order to solve the above problems, the present invention provides a copper foil with resin, which is composed of an uncured or semi-cured thermosetting resin layer and a copper foil, characterized in that:

[0023] The thermosetting resin layer contains a thermosetting resin composition, and the thermosetting resin composition includes:

[0024] (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule, and

[0025] (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators,

[0026] The maleimide compound of the component (A) is one or more selected from the group consisting of the following formulas (1), (2) and (3), and one or more of them is solid at 25°C.

[0027] The ten-point average roughness (Rz) of the surface roughness of the copper foil in contact with the thermosetting resin layer is 1.5 μm or less.

[0028]

[0029] In formula (1), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group having 6 to 60 carbon atoms, but does not include a group having a dimer acid skeleton, D is independently a group selected from divalent aliphatic hydrocarbon groups and divalent aromatic hydrocarbon groups having 6 to 60 carbon atoms, and at least one of D 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 bracketed by m1 and m2 is not limited, and the bonding method can be alternating, block, or random.

[0030]

[0031] In formula (2), A and D are the same as A and D in formula (1), and at least one of D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100,

[0032]

[0033] In formula (3), D is the same as D in the above formula (1).

[0034] Such a resin-coated copper foil is a copper foil using a resin having high adhesion and excellent dielectric properties.

[0035] 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 formulae.

[0036]

[0037] When a maleimide compound containing such a tetravalent organic group is used, the resin-attached copper foil has higher adhesion and is more excellent in dielectric properties.

[0038] Furthermore, in the present invention, it is preferred that an epoxy resin having two or more epoxy groups in one molecule is contained as the component (C), and the component (B) is an anionic polymerization initiator.

[0039] With such (B) component and (C) component, the curing reaction of the thermosetting resin layer of the copper foil with resin can be further accelerated.

[0040] Furthermore, in the present invention, it is desirable that the thermosetting resin layer include glass fiber woven fabric.

[0041] Such a thermosetting resin layer can enhance the strength and rigidity of the cured product.

[0042] Furthermore, the present invention provides a copper-clad laminate comprising a cured product of the above-mentioned copper foil with resin.

[0043] Such a copper-clad laminate has high adhesion and excellent dielectric properties.

[0044] Furthermore, the present invention provides a printed wiring board comprising the copper-clad laminate.

[0045] Such a printed wiring board has high reliability and is useful for high-speed communication applications.

[0046] (3) Beneficial effects

[0047] As described above, according to the present invention, there can be provided a copper foil with a resin, and a copper-clad laminate and a printed wiring board using the copper foil with a resin. The copper foil with a resin is composed of an uncured or semi-cured resin layer and a low-roughness copper foil, wherein the uncured or semi-cured resin layer uses a special maleimide resin having low dielectric properties and high adhesion. The copper-clad laminate and printed wiring board have high reliability and are useful for high-speed communication applications. DETAILED DESCRIPTION

[0048] As described above, there is a demand for the development of a copper foil with a resin, and a copper-clad laminate and a printed wiring board using the copper foil with a resin. The copper foil with a resin is composed of an uncured or semi-cured resin layer and a low-roughness copper foil, wherein the uncured or semi-cured resin layer uses a special maleimide resin having low dielectric properties and high adhesion, and the copper-clad laminate and printed wiring board have high reliability and are useful for high-speed communication applications.

[0049] The present inventors have conducted intensive studies on the above-mentioned problems and, as a result, have found that the following copper foil with resin can achieve the above-mentioned objects, thereby completing the present invention.

[0050] That is, the present invention is a copper foil with resin, which is composed of an uncured or semi-cured thermosetting resin layer and a copper foil, and is characterized in that:

[0051] The thermosetting resin layer contains a thermosetting resin composition, and the thermosetting resin composition includes:

[0052] (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule, and

[0053] (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators,

[0054] The maleimide compound of the component (A) is selected from one or more of the following formulas (1), (2) and (3), and one or more of them is solid at 25° C. The surface of the copper foil in contact with the thermosetting resin layer has a ten-point average roughness (Rz) of 1.5 μm or less.

[0055]

[0056] In formula (1), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group having 6 to 60 carbon atoms, but does not include a group having a dimer acid skeleton, D is independently a group selected from a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms, and at least one of D 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 bracketed by m1 and m2 is not limited, and the bonding method can be alternating, block, or random.

[0057]

[0058] In formula (2), A and D are the same as A and D in formula (1), and at least one of D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100,

[0059]

[0060] In formula (3), D is the same as D in the above formula (1).

[0061] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0062] copper foil

[0063] 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 in contact with the uncured thermosetting resin layer described below, from the perspective of reducing conductor loss. To reduce conductor loss, Rz is preferably smaller, preferably 1.3 μm or less, and more preferably 1.0 μm or less.

[0064] The production method of the copper foil used is not particularly limited, but copper foils produced by ordinary electrolysis and rolling are often used, and electrolytic copper foils produced by electrolysis are often used.

[0065] Furthermore, the copper foil used may be one that has been surface-treated in order to improve adhesive strength, heat resistance, chemical resistance, and the like.

[0066] The thickness of the copper foil is not particularly limited, but is generally used within the range of 6 to 50 μm. Thinner copper foils are known as carrier-attached copper foils, which have a carrier attached to improve handling and thickness, and are removed in subsequent steps. While any type of copper foil can be used in the present invention, copper foil with a thickness of 6 to 35 μm is preferred.

[0067] Thermosetting resin layer

[0068] The thermosetting resin layer used for the copper foil with resin of the present invention is a layer containing a thermosetting resin containing the components (A) and (B) as essential components.

[0069] (A) Maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule

[0070] (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators

[0071] This thermosetting resin is characterized by being in an uncured or semi-cured state. The uncured state refers to the so-called A-stage state, which is obtained by applying a completely uncured thermosetting resin itself or a varnish made from the thermosetting resin using a solvent, etc., into a film and then allowing the solvent to evaporate. Furthermore, the semi-cured state refers to the so-called B-stage state, which is a state in which the thermosetting resin has been cured to a degree that has not yet reached a fully cured state.

[0072] Hereinafter, each constituent component of the thermosetting resin forming the thermosetting resin layer of the present invention will be described in detail.

[0073] (A) Maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule

[0074] The component (A) of the present invention is a maleimide compound represented by the following formula (1), (2), or (3), having one or more hydrocarbon groups derived from a dimer acid backbone in one molecule. Because component (A) has a hydrocarbon group derived from a dimer acid backbone, a cured product of a composition containing component (A) has low relative dielectric constant and loss tangent, and the cured composition also exhibits excellent film properties and handleability. Furthermore, because component (A) has an imide group, even when the composition containing component (A) is formed into a film (thin film), it yields a highly insulating film.

[0075] The maleimide compound as component (A) comprises at least one, preferably two or more, of the maleimide compounds represented by formulae (1), (2), and (3), and at least one of the maleimide compounds represented by formulae (1), (2), and (3) is solid at 25° C. By including such a solid maleimide compound, the film properties of the uncured resin layer are excellent and the viscosity is reduced, thereby improving the handleability of the copper foil with resin.

[0076]

[0077] In formula (1), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group having 6 to 60 carbon atoms, but does not include a group having a dimer acid skeleton, D is independently a group selected from a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms, at least one of D 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 bracketed by m1 and m2 is not limited, and the bonding method may be alternating, block, or random.

[0078]

[0079] In formula (2), A and D are the same as A and D in formula (1), and at least one of D is a hydrocarbon group derived from a dimer acid skeleton. n is 1 to 100,

[0080]

[0081] In formula (3), D is the same as D in the above formula (1).

[0082] Furthermore, since dielectric properties are excellent, viscosity is easily reduced when heated, moldability is excellent, and the influence of moisture absorption tends to be small, it is preferable to use a compound with high dimer acid purity, such as a ratio of dimer acid in the skeleton derived from dimer acid and trimer acid of 95% by mass or more.

[0083] Here, the so-called dimer acid refers to a liquid dibasic acid with a carbon number of 36 as the main component, produced by dimerizing an unsaturated fatty acid with a carbon number of 18, which is derived from natural products such as vegetable oils. Dimer acids do not have a single skeleton, but rather have various structures and exist in various isomers. Representative dimer acids are classified as linear (a), monocyclic (b), aromatic ring (c), and polycyclic (d). In this specification, the dimer acid skeleton refers to a group derived from a diamine having a structure in which the carboxyl groups of the dimer acid are substituted with primary aminomethyl groups. That is, component (A) preferably has a dimer acid skeleton in which two carboxyl groups in each of the dimer acids represented by (a) to (d) below are substituted with methylene groups.

[0084] Furthermore, from the viewpoint of heat resistance and reliability of the cured product, the hydrocarbon group derived from the dimer acid skeleton in the maleimide compound of the component (A) preferably has a structure in which the carbon-carbon double bonds in the hydrocarbon group derived from the dimer acid skeleton are reduced by hydrogenation.

[0085]

[0086] First, although the maleimide compound represented by the formula (1) has a high melt viscosity before curing, its dielectric properties are superior to those of conventional maleimide compounds containing a large amount of aromatics. Furthermore, it has a high adhesion to copper foil and a low moisture absorption capacity compared to conventional thermosetting resins such as epoxy resins, resulting in a small effect of moisture. Furthermore, it can be formed into a composition having a higher Tg than the maleimide compound having a dimer acid skeleton represented by the formula (2) described later, a low coefficient of thermal expansion (CTE), and high reliability.

[0087] The trimer acid mentioned here is essentially a byproduct produced during the synthesis of dimer acid. Trimer acid is a tribasic acid composed primarily of tricarboxylic acid with 54 carbon atoms, produced from the trimerization of unsaturated fatty acids with 18 carbon atoms, derived from natural materials such as vegetable oils and fats. Like dimer acid, trimer acid does not have a single skeleton but rather has various structures and exists as a variety of isomers.

[0088] In the above formula (1), A independently represents a tetravalent organic group having a cyclic structure, and among them, any of the tetravalent organic groups represented by the following formulas is preferred.

[0089]

[0090] In the formula (1), D is independently a group selected from a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms, preferably 8 to 60 carbon atoms, and more preferably 10 to 55 carbon atoms. Among these, preferably, the divalent alicyclic hydrocarbon group is 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 any of a saturated aliphatic hydrocarbon group and an unsaturated hydrocarbon group, and may have an alicyclic structure or an aromatic ring structure in the molecular chain.

[0091] Specific examples of the group selected from the divalent aliphatic hydrocarbon group and the divalent aromatic hydrocarbon group include divalent alicyclic hydrocarbon groups derived from diamines at both ends of the so-called dimer diamine, wherein one or more hydrocarbon groups in one molecule have such hydrocarbon groups derived from a dimer acid skeleton.

[0092] In the formula (1), B is independently a divalent hydrocarbon group having 6 to 60 carbon atoms. In particular, it is independently a divalent aliphatic hydrocarbon group having 6 to 60 carbon atoms or an aromatic hydrocarbon group having 6 to 60 carbon atoms. Preferably, it is a divalent aliphatic hydrocarbon group or an aromatic hydrocarbon group having 6 to 30 carbon atoms. The divalent hydrocarbon group may include a cyclic structure or a branched structure, but does not include a group having a dimer acid skeleton as in D. The divalent aromatic hydrocarbon group may have a bond directly on the aromatic ring or may have a bond from the aromatic ring via a linear or branched divalent aliphatic hydrocarbon group.

[0093] 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, from the perspectives of film properties, moldability, and strength of the composition, the range of m1 + m2 is preferably 2 to 40. On the other hand, if m1 or m2 is too large, the fluidity may decrease, resulting in poor moldability.

[0094] The order of the repeating units enclosed by m1 and m2 is not limited, and the bonding pattern may be alternating, block, or random. Among them, block bonding is preferred because it tends to increase Tg.

[0095] Secondly, the use of the maleimide compound represented by formula (2) has excellent dielectric properties compared to other common maleimide compounds containing a large amount of aromatic groups. In particular, it is effective in maintaining dielectric properties even at high frequencies. Furthermore, it forms an excellent composition with stronger adhesion to copper foil and other resins than the composition represented by formula (1).

[0096] In the formula (2), A is the same as A in the formula (1), and represents a tetravalent organic group independently having a cyclic structure, and preferred A is also the same.

[0097] In the formula (2), n is 1 to 100, preferably 1 to 60, and more preferably 1 to 50. If n is too large, solubility and fluidity may be reduced, and moldability may be poor.

[0098] Secondly, when the maleimide compound represented by formula (3) is used, the dielectric properties are superior to other common maleimide compounds containing a large amount of aromatic groups. In particular, even when high frequencies are formed, the dielectric properties are effectively maintained. Furthermore, since it is liquid at room temperature, it has the effect of improving the moldability of the resin composition of the present invention or improving the operability such as film properties before curing.

[0099] Therefore, when the maleimide compound represented by the formula (3) is used, it is preferred to use at least one of the formula (1) and the formula (2) simultaneously.

[0100] The viscosity of the component (A) preferably falls within the range of 1.0 to 5.0 Pa·s as a value measured at 25° C. and 5 rpm using a cone-plate type rotational viscometer in accordance with JIS Z 8803:2011.

[0101] The number average molecular weight of the maleimide compound as component (A) is not particularly limited, but is preferably 1,500 to 50,000, more preferably 2,000 to 30,000, from the perspective of the handleability of the composition. Component (A) may contain not only the maleimide compound represented by formula (1), (2), or (3) but also other maleimide compounds. The maleimide compound may be used alone or in combination. However, when formula (3) is used as described above, it is preferred that at least one of formula (1) or formula (2) be included.

[0102] In addition, the number average molecular weight mentioned 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.

[0103] [Measurement conditions]

[0104] Developing solvent: tetrahydrofuran (THF)

[0105] Flow rate: 0.35mL / min

[0106] Detector: Differential refractive index detector (RI)

[0107] Chromatographic column: TSK Guardcolumn SuperH-L

[0108] TSKgel SuperHZ4000(4.6mm ID×15cm×1)

[0109] TSKgel SuperHZ3000(4.6mm ID×15cm×1)

[0110] TSKgel SuperHZ2000(4.6mm ID×15cm×2)

[0111] (Both manufactured by Tosoh Corporation)

[0112] Column temperature: 40°C

[0113] Sample injection volume: 5 μL (0.2 mass % THF solution)

[0114] (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators

[0115] 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 with the reactive groups reactive with the maleimide groups in component (A). The catalyst is selected from the group consisting of a thermal radical polymerization initiator or an anionic polymerization initiator.

[0116] When the reaction of component (A) alone is to be accelerated, a thermal radical polymerization initiator is preferred. Furthermore, when component (E) described below is included, a thermal radical polymerization initiator is also preferred when its reactive group is a group having a carbon-carbon double bond such as a maleimide group, an alkenyl group, or a (meth)acryloyl group.

[0117] As thermal radical polymerization initiators, azo compounds, organic peroxides, persulfates, etc. can be listed, among which organic peroxides are preferably used. Organic peroxides are classified into types such as allyl peroxides, dialkyl peroxides, peroxycarbonates, and hydroperoxides, but are not particularly limited. Specifically, dicumyl peroxide, tert-butyl peroxybenzoate, tert-amyl peroxybenzoate, dibenzoyl peroxide, dilauroyl peroxide, 2,5-dimethyl-2,5-di(tert-butyl peroxide)hexane, 1,1-di(tert-butyl peroxide)cyclohexane, di-tert-butyl peroxide, dibenzoyl peroxide, etc. can be listed.

[0118] When the reactive group reactive with the maleimide group of component (E) 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 an imidazole or a tertiary amine, or an organic phosphorus compound is preferred. While imidazoles or amines can be used for the polymerization of maleimide groups alone, very high temperatures are required when using imidazoles or phosphorus compounds, and caution should be exercised as amines tend to have a very short pot life.

[0119] In particular, when the component (C) described below is included, the component (B) functions as an anionic polymerization catalyst. Examples of anionic polymerization catalysts include basic compounds such as the above-mentioned imidazoles and tertiary amines, or organophosphorus compounds, with imidazoles being particularly preferred.

[0120] Relative to 100 parts by mass of component (A), it is preferred to blend 0.05 to 10 parts by mass of component (B), more preferably 0.1 to 5 parts by mass of component (B). In addition, when other thermosetting resins described later are blended into the composition, it is preferred to blend with 0.05 to 10 parts by mass, particularly preferably within the range of 0.1 to 5 parts by mass, relative to 100 parts by mass of the sum of component (A) and other thermosetting resin components. If within the above range, the thermosetting resin film of the present invention is formed, and the curing property is stable, so it is preferred. In addition, the heat resistance and moisture resistance of the obtained cured product are well balanced, so it is preferred.

[0121] The catalyst of the component (B) may be used alone or in combination of two or more.

[0122] In the resin-coated copper foil of the present invention, the thickness of the laminated uncured thermosetting resin layer is not particularly limited, but is preferably in the range of 1 to 150 μm, more preferably in the range of 1 to 40 μm. Furthermore, when the glass fiber woven fabric described below is included, its thickness needs to be taken into consideration, and is preferably in the range of 40 to 125 μm.

[0123] Other additives

[0124] The thermosetting resin layer of the present invention may further contain various additives as needed. Examples of other additives are shown below.

[0125] (C) Epoxy resins having two or more epoxy groups in one molecule

[0126] In the thermosetting resin layer of the resin-coated copper foil of the present invention, when an anionic polymerization catalyst is used as component (B), 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.

[0127] As the component (C), an epoxy resin having a glycidyl group is preferred in consideration of reactivity with the component (B).

[0128] Examples of the component (C) include phenol novolac epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, biphenyl diphenol epoxy resins, naphthalene epoxy resins, anthracene epoxy resins, naphthol epoxy resins, xylene epoxy resins, biphenyl epoxy resins, biphenyl aralkyl epoxy resins, triphenylmethane epoxy resins, alicyclic epoxy resins, glycidylamine epoxy resins, dicyclopentadiene epoxy resins, stilbene epoxy resins, sulfur atom-containing epoxy resins, and phosphorus atom-containing epoxy resins.

[0129] From the viewpoint of compatibility and wettability to the substrate, it is preferred to use a component (C) that is liquid at room temperature (25° C.).

[0130] Relative to 100 mass parts of the thermosetting resin comprising (A) component, as the admixture amount of (C) component, preferably admix 0.05~25 mass parts, more preferably admix 0.1~20 mass parts. If within the above range, then when shaping, curing speed becomes suitable, so preferably. In addition, the balance of the heat resistance and moisture resistance of the obtained cured product also becomes good. The low dielectric properties of target can also be obtained.

[0131] The epoxy resin of the component (C) may be used alone or in combination of two or more.

[0132] (D) Inorganic filling materials

[0133] The thermosetting resin layer of the present invention may further include (D) an inorganic filler. The purpose of adding the inorganic filler is to improve the strength and rigidity of the cured product of the thermosetting resin layer in the copper foil with resin of the present invention, or to adjust the thermal expansion coefficient and the dimensional stability of the cured product. As the inorganic filler, the inorganic filler usually added to the epoxy resin composition or the silicone resin composition can be used, but in order to prevent the relative dielectric constant of the entire composition from rising, preferably silicon dioxide particles or boron nitride such as spherical silica, fused silica and crystalline silica are used.

[0134] The average particle size and shape of the inorganic filler are not particularly limited, but from the perspective of substrate processability, spherical silica with an average particle size of 0.5 to 5 μm is particularly suitable. The average particle size is the mass average value D in the particle size distribution measurement obtained by laser diffraction. 50 (or median diameter) and is obtained by

[0135] Furthermore, in order to improve the properties, the inorganic filler is preferably surface-treated with a silane coupling agent having an organic group that can react with a maleimide group. Examples of such silane coupling agents include epoxy-containing alkoxysilanes, amino-containing alkoxysilanes, (meth)acryloyl-containing alkoxysilanes, and alkenyl-containing alkoxysilanes.

[0136] As the silane coupling agent, an alkoxysilane containing a (meth)acryloyl group and / or an amino group is preferably used. Specific examples thereof include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane.

[0137] The inorganic filler may be used alone or in combination of two or more. The amount of the inorganic filler added is 0 to 500 parts by mass, preferably 0 to 400 parts by mass, relative to 100 parts by mass of the component (A).

[0138] (E) Thermosetting resin having a reactive group reactive with a maleimide group

[0139] In the present invention, a thermosetting resin having a reactive group that can react with a maleimide group may be further added to the thermosetting resin layer as component (E). However, the substance belonging to component (C) is not included in component (E).

[0140] The type of component (E) is not limited. Examples thereof include various resins other than component (A), such as melamine resins, silicone resins, cyclic imide resins represented by maleimide compounds other than component (A), urea resins, thermosetting polyimide resins, modified polyphenylene ether resins, thermosetting acrylic resins, and epoxy-silicone hybrid resins. Furthermore, phenol curing agents, amine curing agents, acid anhydride curing agents, and active ester curing agents used as curing agents for epoxy resins are also included.

[0141] Examples of the reactive group capable of reacting 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)acryloyl group, and a thiol group.

[0142] From the viewpoint of reactivity, the reactive group of the component (E) is preferably selected from a maleimide group, a hydroxyl group, and an alkenyl group, and more preferably an alkenyl group or a (meth)acryloyl group from the viewpoint of dielectric properties.

[0143] The content of the component (E) is preferably 0 to 60% by mass in the total amount of the thermosetting resin (ie, the total amount of the components (A), (C), and (E).

[0144] Glass fiber fabric

[0145] In the present invention, glass fiber fabric can be further contained in the thermosetting resin layer. That is, if only for the thermosetting resin layer, it can be the same structure as the prepreg. Glass fiber fabric can list E glass, low dielectric glass, quartz glass, and further can list S glass, T glass, etc., no matter how the type of glass used, from the perspective of the characteristics of the thermosetting maleimide resin composition, preferably there is quartz glass cloth with low dielectric properties. In addition, glass fiber fabric can be located inside the thermosetting resin layer or on the surface, but from the perspectives of appearance, processability, etc., it is preferably located inside the thermosetting resin layer. In addition, the thickness of the glass fiber fabric commonly used is, for example, more than 10 μm and less than 100 μm.

[0146] other

[0147] In addition to the above, non-functional ketone oil, reactive diluent, thermoplastic resin, thermoplastic elastomer, organic synthetic rubber, photosensitizer, light stabilizer, polymerization inhibitor, flame retardant, pigment, dye, adhesion promoter, ion capture material, etc. may be blended.

[0148] Furthermore, silane coupling agents such as epoxy-containing alkoxysilanes, amino-containing alkoxysilanes, (meth)acryloyl-containing alkoxysilanes, and alkenyl-containing alkoxysilanes, which are used to surface-treat the inorganic filler, can be separately blended into the uncured or semi-cured thermosetting resin layer of the resin-coated copper foil of the present invention, and can also be used to further surface-treat the copper foil. Specific examples of the silane coupling agent include the same ones as those mentioned above.

[0149] The method for producing the copper foil with resin of the present invention is not particularly limited, and examples thereof include the following methods.

[0150] The method of preparing the varnish can be as follows: first, the above-mentioned thermosetting resin is dissolved in an organic solvent to form a varnish, which is directly applied to the surface of the copper foil and dried. When preparing the varnish, as for the organic solvent, as long as it is a solvent that dissolves the thermosetting resin having a reactive group that can react with a maleimide group as other additives, it can be used without restriction. For example, anisole, tetralin, mesitylene, xylene, toluene, tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, etc., are preferably aromatic organic solvents such as anisole, tetralin, mesitylene, xylene, toluene. In addition, these organic solvents can be used alone or in combination.

[0151] For example, after applying a thermosetting resin (varnish) dissolved in an organic solvent to a substrate, the organic solvent is removed by heating the substrate at a temperature of 80°C or higher, preferably 100°C or higher for 0.5 to 20 minutes. A temperature of 130°C or lower is preferred because the copper foil does not oxidize.

[0152] The temperature of the drying step for removing the organic solvent may be fixed or increased stepwise, thereby enabling the organic solvent to be effectively removed from the composition.

[0153] Examples of the coating method for the varnish include gravure coaters, die coaters, spin coaters, slit coaters, spray coating, dip coaters, and bar coaters, but are not particularly limited.

[0154] Similarly to the above, a thermosetting resin is dissolved in an organic solvent to form a varnish, which is then applied to a release-treated polyethylene terephthalate (PET) film. The solvent is dried to form a film, which is then attached to a copper foil. The PET film is then peeled off to obtain a copper foil with a resin. Lamination conditions are not particularly limited, but lamination is preferably performed while heating at a temperature of 80 to 130°C, at a pressure of 0.1 to 1.0 MPa, and for 0.5 to 5 minutes.

[0155] As another method, the components may be preliminarily mixed, extruded into a film using a melt kneader, and used directly (extrusion molding).

[0156] The resin-coated copper foil of the present invention can be used for copper-clad laminates and printed wiring boards. The printed wiring boards are not limited to flexible boards, but can also be used for rigid boards.

[0157] The method for producing a copper-clad laminate is not particularly limited. For example, as a general method, the resin surface of the resin-coated copper foil of the present invention can be brought into contact with a prepreg or its cured product, a polyimide or liquid crystal polymer (LCP) film used in a flexible printed circuit board, and then attached using a vacuum laminator. Then, after attaching by pressing or vacuum laminating while heating, the materials are directly cured to produce a copper-clad laminate.

[0158] In this case, lamination conditions are not particularly limited, but lamination is preferably performed while heating at a temperature of 80-130°C, 0.1-1.0 MPa, and 0.5-5 minutes. Pressing conditions are not particularly limited, but lamination is preferably performed while heating at a temperature of 150-200°C, 0.1-1.0 MPa, and 0.5-2 hours. When heat curing is performed without pressing, the heating temperature and time are preferably the above conditions.

[0159] The method for producing a printed wiring board is not particularly limited. For example, a conventional method for producing a rigid board is to form a circuit by pattern etching on a copper-clad laminate produced by the above method, such as by a subtractive method. A flexible board is also not particularly limited. For example, a conventional method for producing a flexible board is to form a circuit by pattern etching on a copper-clad laminate produced by the above method, and then thermally press-bonding the cover layer.

[0160] Example

[0161] Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0162] (A) Maleimide compounds

[0163] (A-1): A bismaleimide compound represented by the following formula containing a hydrocarbon group derived from a dimer acid skeleton (SLK-2600, manufactured by Shin-Etsu Chemical Co., Ltd., solid at 25°C)

[0164]

[0165] -C 36 H 70 - indicates a structure derived from a dimer acid backbone.

[0166] m1≈5, m2≈l

[0167] (A-2): A bismaleimide compound represented by the following formula containing a hydrocarbon group derived from a dimer acid skeleton (trade name: BMI-3000J, manufactured by Designer Molecules Inc., solid at 25°C)

[0168]

[0169] -C 36 H 70 - indicates a structure derived from a dimer acid backbone.

[0170] (A-3): A bismaleimide compound represented by the following formula containing a hydrocarbon group derived from a dimer acid skeleton (trade name: BMI-1500, manufactured by Designer Molecules Inc., in the form of a syrup at 25°C)

[0171]

[0172] (A-4): A bismaleimide compound represented by the following formula containing a hydrocarbon group derived from a dimer acid skeleton (trade name: BMI-689, manufactured by Designer Molecules Inc., liquid at 25°C)

[0173]

[0174] Comparative Example Compounds

[0175] (A-5): 4,4'-diphenylmethanebismaleimide (trade name: BMI-1000, manufactured by Daiwa Kasei Industrial Co., Ltd., solid at 25°C)

[0176] (A-6): An aromatic bismaleimide compound represented by the following formula (trade name: SLK-6200, manufactured by Shin-Etsu Chemical Co., Ltd., solid at 25°C)

[0177]

[0178] (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators

[0179] (B-1): Dicumyl peroxide (trade name: Percumyl D, manufactured by NOF CORPORATION)

[0180] (B-2): 1-benzyl-2-phenylimidazole (trade name: 1B2PZ, manufactured by SHIKOKU CHEMICALS CORPORATION)

[0181] (C) Epoxy resins having two or more epoxy groups in one molecule

[0182] (C-1): Bisphenol A type liquid epoxy resin (trade name: jER-828, manufactured by Mitsubishi Chemical Group Corporation)

[0183] (C-2): Multifunctional epoxy resin (trade name: EPPN-501, manufactured by NIPPON KAYAKU Co., Ltd.)

[0184] (D) Inorganic filling materials

[0185] (D-1): A slurry containing spherical silica having an average particle size of 0.5 μm and a solid concentration of 75% by mass and a toluene dispersion (trade name: 5SV-CT1, manufactured by Admatechs) was used.

[0186] (E) Thermosetting resin having a reactive group reactive with a maleimide group

[0187] (E-1): Terminal methacryloyl-modified polyphenylene ether resin (trade name: SA-9000, manufactured by SABIC)

[0188] (F) Comparative Materials

[0189] (F-1): Hydrogenated styrene-based thermoplastic elastomer (SEBS) (trade name: Tuftec H1041, manufactured by ASAHI KASEI CORPORATION)

[0190] (F-2): Phenol novolac resin (trade name: Phenolite TD-2131, manufactured by DIC Corporation)

[0191] (F-3): Low dielectric accumulation film (thickness 15 μm, trade name: GL-102, manufactured by Ajinomoto Co., Ltd.)

[0192] (F-4): Low dielectric prepreg (#1035, trade name: Megtron7 R-5785(N), manufactured by Panasonic Industry Co., Ltd.)

[0193] copper foil

[0194] Rz = 1.0 μm; trade name CF-T4X-SV-18, thickness 18 μm, manufactured by FUKUDA METAL FOIL & POWDER CO., LTD.

[0195] Rz = 5.0 μm; trade name 3EC-III, thickness 18 μm, manufactured by MITSUI MINING & SMELTING CO., LTD.

[0196] Glass fiber fabric

[0197] Quartz glass cloth (#1035, trade name: SQX); thickness 25 μm, manufactured by Shin-Etsu Chemical Co., Ltd.

[0198] Preparation of resin varnish

[0199] According to the ratios in Tables 1 and 2, the components shown in Tables 1 and 2 were added to a 500 mL four-necked flask equipped with a Dai condenser and a stirring device, stirred at 80°C for 4 hours, and filtered with a 100-mesh wire mesh to obtain a varnish-like resin composition.

[0200] <Production of Copper Foil with Glass-Free Woven Resin>

[0201] The varnish-like resin composition prepared above was applied to the frosted surface of the copper foil using a roll coater to produce a resin-coated copper foil having an uncured resin or semi-cured resin layer with a thickness of 5 μm under the conditions shown in Tables 1 and 2.

[0202] <Production of Resin Copper Foil with Glass Fiber Fabric>

[0203] The resin varnish prepared above was impregnated into a glass fiber woven fabric substrate at room temperature and dried under the conditions listed in Tables 1 and 2. The resin content (resin composition content) and thickness of the resulting prepreg are reported in Tables 1 and 2, respectively. The uncured resin or semi-cured prepreg obtained in this manner was laminated onto the frosted surface of the copper foil using a batch vacuum laminator (manufactured by Nikko Materials Co., Ltd.) at 100°C, a pressure of 0.5 MPa, and 60 seconds to produce a copper foil with a resin attached to a glass fiber woven fabric.

[0204] In addition, for comparison, (F-3) was not a prepreg but a film product. After removing the cover film and placing the resin surface on the copper foil, the copper foil was laminated using the same method under the above conditions to produce a resin-coated copper foil. In this case, the base film was removed before testing.

[0205] In addition, since (F-4) for comparison was already a prepreg, the prepreg production step was omitted, and the resin-attached copper foil was produced by laminating it on the copper foil in the same manner.

[0206] <Handling of Copper Foil with Resin>

[0207] The handleability of the resin-coated copper foil prepared above was evaluated. A score of ◯ was assigned if the foil could be wound around a 3-inch diameter ABS tube and used without any problems. A score of × was assigned if the resin layer cracked or peeled when wound around a 3-inch diameter ABS tube. A score of △ was assigned if the thermosetting resin layer had extremely strong adhesion, causing contamination during winding. Subsequent evaluations were omitted if the evaluations were × or △.

[0208] <Peel Strength>

[0209] A SUS304 plate with a length of 75 mm, a width of 25 mm, and a thickness of 1.0 mm was prepared. One of the resin-coated copper foils prepared above was cut into a length of 150 mm and a width of 10 mm. The uncured or semi-cured resin layer was placed on the plate and laminated at 120°C, a pressure of 0.8 MPa, and 60 seconds. After lamination, the plate was heated at 180°C for 2 hours under a nitrogen atmosphere to prevent copper oxidation, thereby curing the plate and producing an adhesion test piece. To evaluate adhesion, the 90° peel strength (kN / m) of each adhesion test piece was measured at a temperature of 23°C and a tensile rate of 50 mm / min in accordance with JIS C6481:1996 when the copper foil was peeled from the SUS plate.

[0210] <Heat resistance test>

[0211] Five test pieces prepared for the peel test were prepared and treated in a thermostatic chamber set at 300°C with an air circulation device for 1 hour. At this time, if there were no abnormalities in any of the five test pieces, it was judged as "○". If one or more of the five test pieces showed "bulging" or "peeling", it was judged as "×".

[0212] <Transmission loss measurement>

[0213] Two sheets of low-dielectric prepreg (#2016, trade name: Megtron7 R-5785 (N), manufactured by Panasonic Industry Co., Ltd.) were overlapped and laminated, and the prepared copper foil with a thickness of 5 μm with resin was overlapped on both sides. The copper foil was heated and pressed at a temperature of 200°C for 2 hours and a pressure of 3 MPa to obtain a copper-clad laminate for evaluation with a thickness of about 250 μm.

[0214] Next, one side of the double-sided board having the resin-coated copper foil was processed to a line width of 100 to 200 μm, and the line width was finalized by etching, and then the characteristic impedance of the circuit was adjusted to 50Ω.

[0215] Regarding transmission characteristics, the transmission loss of the obtained laminate was evaluated using a network analyzer (manufactured by Keysight Technologies) at a frequency of 40 GHz.

[0216] [Table 1]

[0217]

[0218] [Table 2]

[0219]

[0220] *Exact value cannot be obtained due to viscosity.

[0221] From the above, the usefulness of the copper foil with resin of the present invention was confirmed from the viewpoints of adhesive strength and transmission loss.

[0222] This specification includes the following inventions.

[0223] [1]: A copper foil with resin, which is composed of an uncured or semi-cured thermosetting resin layer and a copper foil, characterized in that:

[0224] The thermosetting resin layer contains a thermosetting resin composition, and the thermosetting resin composition includes:

[0225] (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule, and

[0226] (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators,

[0227] The maleimide compound of the component (A) is one or more selected from the group consisting of the following formulas (1), (2) and (3), and one or more of them is solid at 25°C.

[0228] The ten-point average roughness (Rz) of the surface roughness of the copper foil in contact with the thermosetting resin layer is 1.5 μm or less.

[0229]

[0230] In formula (1), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group having 6 to 60 carbon atoms, but does not include a group having a dimer acid skeleton, D is independently a group selected from a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms, and at least one of D 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 bracketed by m1 and m2 is not limited, and the bonding method can be optionally alternating, block, or random.

[0231]

[0232] In formula (2), A and D are the same as A and D in formula (1), at least one of D is a hydrocarbon group derived from a dimer acid skeleton, and n is 1 to 100.

[0233]

[0234] In formula (3), D is the same as D in the above formula (1).

[0235] [2]: The resin-coated copper foil according to [1], wherein A in the formula (1) or the formula (2) is any one of the tetravalent organic groups represented by the following formulas:

[0236] .

[0237] [3]: The resin-coated copper foil according to [1] or [2], characterized in that the component (C) further contains an epoxy resin having two or more epoxy groups in one molecule, and the component (B) is an anionic polymerization initiator.

[0238] [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.

[0239] [5]: A copper-clad laminate comprising a cured product of the resin-coated copper foil according to any one of [1] to [4].

[0240] [6]: A printed circuit board, characterized in that it comprises the copper-clad laminate described in [5].

[0241] The present invention is not limited to the above-described embodiments, which are merely examples, and any solution having substantially the same configuration and exhibiting the same effects as the technical concept described in the claims of the present invention is within the technical scope of the present invention.

Claims

1. A copper foil with resin, which is composed of an uncured or semi-cured thermosetting resin layer and a copper foil, characterized in that: The thermosetting resin layer contains a thermosetting resin composition, and the thermosetting resin composition includes: (A) a maleimide compound having one or more hydrocarbon groups derived from a dimer acid skeleton in one molecule, and (B) one or more catalysts selected from thermal radical polymerization initiators or anionic polymerization initiators, The maleimide compound of the component (A) is one or more selected from the group consisting of the following formulas (1), (2) and (3), and one or more of them is solid at 25°C. The ten-point average roughness (Rz) of the surface roughness of the copper foil in contact with the thermosetting resin layer is 1.5 μm or less. In formula (1), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group having 6 to 60 carbon atoms, but does not include a group having a dimer acid skeleton, D is independently a group selected from a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms, and at least one of D 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 bracketed by m1 and m2 is not limited, and the bonding method can be optionally alternating, block, or random. In formula (2), A and D are the same as A and D in formula (1), at least one of D is a hydrocarbon group derived from a dimer acid skeleton, and n is 1 to 100. In formula (3), D is the same as D in the above formula (1).

2. The copper foil with resin according to claim 1, wherein A in the formula (1) or the formula (2) is any one of the tetravalent organic groups represented by the following formulas: 。 3. The copper foil with resin according to claim 1, wherein The epoxy resin having two or more epoxy groups in one molecule is further contained as the component (C), and the component (B) is an anionic polymerization initiator.

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

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

6. A printed circuit board, characterized in that: The copper-clad laminate according to claim 5 is included.

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