Metal foil with resin, metal foil-clad laminate, and wiring board

Abstract

The purpose of the present invention is to provide a metal foil with a resin, which is capable of producing a wiring board having high adhesion between a resin layer and a metal layer, excellent laser processability, and reduced loss during signal transmission. [Solution] The present invention provides a metal foil with a resin, comprising: a resin layer comprising a resin composition or a semi-cured product of the resin composition; and a metal layer on at least one side surface of the resin layer, in which the resin composition contains: a polybutadiene compound having an epoxy group in a molecule; a polyphenylene ether compound having a carbon-carbon unsaturated bond; a styrenic block copolymer; and a curing agent, the metal layer having a copper foil in contact with the surface of the resin layer, the thickness of the copper foil being 5.0 [mu] m or less, the arithmetic average roughness (Ra) of the surface of the copper foil in contact with the resin layer being 0.6 [mu] m or less, and the ten-point average roughness (Rzjis) of the surface being 3.0 [mu] m or less.

Description

Technical Field

[0001] This invention relates to resin-coated metal foil, metal foil laminate, and wiring board. Background Technology

[0002] For various electronic devices, with the increasing volume of information processing, mounting technologies such as high integration of semiconductor devices, high-density wiring, and multi-layering are becoming increasingly advanced. Furthermore, wiring boards used in various electronic devices require high-frequency solutions, such as millimeter-wave radar substrates for automotive applications. For the substrate materials used to construct the insulating layers of wiring boards in various electronic devices, there is a need to improve signal transmission speed and reduce signal transmission losses. To reduce signal transmission losses, low dielectric constant and low dielectric loss factor are required.

[0003] Polyphenylene ether (PPE) is known to possess excellent low dielectric properties, such as a low dielectric constant and low dielectric loss factor. Furthermore, these low dielectric properties remain excellent even in the high-frequency range (from MHz to GHz). Therefore, the use of PPE as a molding material, for example, for high-frequency applications, has been investigated. More specifically, it is preferably used in substrate materials, which form the insulating layer of wiring boards in electronic devices utilizing high-frequency bands.

[0004] Here, the resin-coated metal foil and metal-clad laminate used in manufacturing wiring boards and the like not only have an insulating layer, but also have a metal foil (metal layer) on the insulating layer. Furthermore, the wiring board not only has an insulating layer, but also has wiring on the insulating layer. And, as examples of the wiring, the wiring formed by the metal layer in the metal-clad laminate and the like can be cited.

[0005] As wiring boards become thinner, the wiring becomes finer, requiring smaller wiring thickness. Therefore, it is further required that the wiring not peel off from the insulating layer. To this end, high adhesion between the wiring and the insulating layer is required, and high adhesion between the metal layer and the insulating layer is also required in metal foil laminates and resin-coated metal foils. Therefore, it is required that the substrate material used to form the insulating layer of the wiring board can produce a cured product with high adhesion to the metal layer.

[0006] Furthermore, in order to achieve impedance matching of the wiring board as the wiring thickness decreases, and to suppress the loss caused by the increase in resistance associated with wiring miniaturization, the insulating layer of the wiring board is required to have a low dielectric constant.

[0007] Patent Document 1 discloses a resin composition comprising a polyphenylene ether compound, a polybutadiene compound, a styrene-based block copolymer, and a curing agent. According to the technology described in Patent Document 1, a resin composition is disclosed that can provide a cured product with low dielectric properties and high adhesion to a metal layer.

[0008] In recent years, the design patterns of semiconductor packaging substrates have become more complex, requiring materials used in wiring boards to have high laser machinability in the via formation process. In particular, with the trend of wiring boards becoming thinner and using ultra-thin metal foils (e.g., less than 5 μm thick) to form circuits, the demand for laser processing in the via formation process for interlayer connections is increasing.

[0009] However, when the metal foil (metal layer) is thin, it is difficult to perform laser processing while maintaining the tightness between the insulating layer and the metal layer, making the improvement of laser processability a challenge. Regarding this point, the technology described in Patent Document 1 does not mention the laser processability of ultrathin metal foils.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: International Patent Publication No. 2021 / 010431 Summary of the Invention

[0013] The present invention was made in view of the above circumstances, and its object is to provide: a resin-coated metal foil capable of manufacturing a wiring board with high adhesion between the resin layer and the metal layer, excellent laser processability, and reduced signal transmission loss; a metal-clad laminate capable of manufacturing a wiring board with high adhesion between the insulating layer and the metal layer, excellent laser processability, and reduced signal transmission loss; and a wiring board with high adhesion between the insulating layer and the metal layer, excellent laser processability, and low signal transmission loss.

[0014] One aspect of the present invention relates to a resin-coated metal foil comprising: a resin layer containing a resin composition or a semi-cured form of the resin composition; and a metal layer located on at least one side surface of the resin layer, wherein the resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent, the metal layer having a copper foil in contact with the surface of the resin layer, the copper foil having a thickness of 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface of the copper foil in contact with the resin layer being 0.6 μm or less, and the ten-point mean roughness (Rzjis) of the surface being 3.0 μm or less. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view illustrating an example of a resin-coated metal foil according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic cross-sectional view illustrating another example of a resin-coated metal foil according to an embodiment of the present invention.

[0017] Figure 3 This is a schematic cross-sectional view illustrating an example of a metal foil laminate according to an embodiment of the present invention.

[0018] Figure 4 This is a schematic cross-sectional view illustrating an example of a wiring board according to an embodiment of the present invention. Detailed Implementation

[0019] The following describes the embodiments of the present invention, but the present invention is not limited to these embodiments.

[0020] The resin-coated metal foil of this embodiment includes: a resin layer containing a resin composition or a semi-cured product of the resin composition; and a metal layer located on at least one side surface of the resin layer, wherein the resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent, the metal layer having a copper foil in contact with the surface of the resin layer, the copper foil having a thickness of 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface of the copper foil in contact with the resin layer being 0.6 μm or less, and the ten-point mean roughness (Rzjis) of the surface being 3.0 μm or less.

[0021] According to this configuration, a resin-coated metal foil with high adhesion between the resin layer and the metal layer and excellent laser processability can be provided. Furthermore, the aforementioned resin-coated metal foil also exhibits excellent heat resistance. Moreover, when this resin-coated metal foil is used in a wiring board, signal transmission losses can be reduced.

[0022] It should be noted that, in this specification, laser machinability specifically refers to laser machinability related to the formation of vias. More specifically, excellent laser machinability means, for example, that even when the spacing between the formed vias is small, the metal layer is difficult to peel off from the insulating layer, and that vias can be formed even when forming vias with smaller apertures.

[0023] <Resin-coated metal foil>

[0024] Figure 1 , Figure 2This is a schematic cross-sectional view showing the structure of the resin-coated metal foil according to this embodiment. The resin-coated metal foil 1 has: a resin layer 2 containing a resin composition or a semi-cured product of the resin composition; and a metal layer 3. Figure 1 , Figure 2 In the diagram, the symbols represent: 1, 1': metal foil with resin, 2: resin layer, 3: metal layer, 4: the surface where the copper foil contacts the resin layer 2 (hereinafter also referred to as the contact surface).

[0025] It should be noted that the resin-coated metal foil 1 may also have a covering film, etc., as needed. By having a covering film, it is possible to prevent the introduction of foreign matter. There is no particular limitation on the covering film, and examples include polyolefin films, polyester films, polymethylpentene films, and films formed by providing a release agent layer on these films.

[0026] [Metallic layer]

[0027] The metal layer 3 is laminated onto at least one surface of the resin layer 2. The resin-coated metal foil 1 can be as follows: Figure 1 The structure shown can be configured such that the metal layer 3 is laminated only on one side of the surface of the resin layer 2, or it can be configured as follows: Figure 2 The metal foil 1' shown has a structure in which metal layers 3 are laminated on both sides of the resin layer 2. Furthermore, the metal layer 3 has a copper foil in contact with the surface of the resin layer 2. The copper foil can be as follows: Figure 1 As shown, it only contacts one side of the surface of resin layer 2, or it can be as shown... Figure 2 As shown, the copper foil is in contact with both sides of the resin layer 2.

[0028] In metal layer 3, the thickness of the copper foil is 5.0 μm or less. Even with such a small copper foil thickness, the resin layer of the resin-coated metal foil in this embodiment exhibits excellent adhesion to the metal layer and superior laser processability. The thickness of the copper foil is preferably 4.0 μm or less, more preferably 3.0 μm or less. Furthermore, the lower limit of the copper foil thickness is not particularly limited, but is preferably 0.2 μm or more, more preferably 0.5 μm or more.

[0029] Furthermore, the arithmetic mean roughness (Ra) of the surface (contact surface) 4 of the copper foil that contacts the resin layer 2 is 0.6 μm or less, and the ten-point average roughness (Rzjis) of this surface is 3.0 μm or less. When a wiring board is fabricated using this resin-coated metal foil, signal transmission losses during wiring can be reduced. Additionally, the arithmetic mean roughness (Ra) of the contact surface 4 is preferably 0.5 μm or less, more preferably 0.35 μm or less. The ten-point average roughness (Rzjis) of the contact surface 4 is preferably 2.5 μm or less, more preferably 2.0 μm or less.

[0030] The arithmetic mean roughness (Ra) of the contact surface 4 is preferably 0.03 μm or more. Furthermore, the ten-point average roughness (Rzjis) of the contact surface 4 is preferably 0.1 μm or more. By keeping the arithmetic mean roughness (Ra) and ten-point average roughness (Rzjis) of the contact surface 4 within the above ranges, the adhesion between the metal layer and the resin layer can be improved more reliably. Particularly when laser processing is performed on the wiring board using the resin-coated metal foil, it has the advantage that even when the spacing between the formed vias is small, the metal layer is difficult to peel off from the insulating layer. The arithmetic mean roughness (Ra) of the contact surface 4 is more preferably 0.04 μm or more, and even more preferably 0.05 μm or more. The ten-point average roughness (Rzjis) of the contact surface 4 is more preferably 0.3 μm or more, and even more preferably 0.4 μm or more.

[0031] It should be noted that the arithmetic mean roughness (Ra) is based on the arithmetic mean roughness standard of JIS B 0601-2001 and can be measured using a conventional arithmetic mean roughness measuring instrument. Specifically, for example, a laser microscope (VK-X1000 manufactured by Keyence Co., Ltd.) can be used for measurement. Similarly, the ten-point mean roughness (Rzjis) is based on the ten-point mean roughness standard of JIS B 0601-2001 and can be measured using a conventional ten-point mean roughness measuring instrument. Specifically, for example, a laser microscope (VK-X1000 manufactured by Keyence Co., Ltd.) can be used for measurement.

[0032] The copper foil may contain copper, for example, it may be formed from copper or a copper alloy. Examples of such copper alloys include those containing copper and at least one alloy selected from the group consisting of nickel, phosphorus, tungsten, arsenic, molybdenum, chromium, cobalt, and zinc. It should be noted that commercially available copper foil may also be used. Examples of commercially available copper foil include MT18FL [Ra: 0.2μm, Rzjis: 1.3μm] and MT18Ex [Ra: 0.3μm, Rzjis: 2.0μm] manufactured by Mitsui Metals Mining Co., Ltd.

[0033] Furthermore, the copper foil preferably undergoes surface treatment on at least one surface. That is, the copper foil may undergo surface treatment on both surfaces or on one surface. When one surface of the copper foil is surface treated, the copper foil is arranged such that the surface-treated surface contacts the resin layer 2. That is, the surface-treated surface becomes the contact surface 4.

[0034] Examples of surface treatments include silane coupling agent treatment, roughening treatment, heat-resistant treatment, and rust-preventive treatment. Preferably, the copper foil is surface-treated with a silane coupling agent. This surface treatment of the copper foil with a silane coupling agent improves the adhesion between the copper foil and the resin layer. It should be noted that the copper foil can be any one of the treatments performed, or it can be a combination of two or more treatments performed.

[0035] Regarding the surface treatment using the silane coupling agent, it can be a rust-prevention treatment commonly performed during the manufacture of copper foil, without particular limitation. Examples include, for instance, coating the surface of the copper foil to be treated with the silane coupling agent. As for the silane coupling agent treatment, it can be dried or heated after coating with the silane coupling agent.

[0036] Examples of silane coupling agents include silane coupling agents having at least one functional group selected from the group consisting of vinyl, styrene, methacryl, acryloyl, phenylamino, and glycidyl groups. Specifically, examples of such silane coupling agents include compounds having at least one reactive functional group selected from vinyl, styrene, methacryl, acryloyl, phenylamino, and glycidyl groups and having hydrolyzable groups such as methoxy or ethoxy groups.

[0037] Examples of silane coupling agents containing the vinyl group include vinyltriethoxysilane and vinyltrimethoxysilane. Examples of silane coupling agents containing the styrene group include p-styrenetrimethoxysilane and p-styrenetriethoxysilane. Examples of silane coupling agents containing the methacryloyl group include 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropylethyldiethoxysilane. Examples of silane coupling agents containing the acryloyl group include 3-acryloyloxypropyltrimethoxysilane and 3-acryloyloxypropyltriethoxysilane. Examples of silane coupling agents having the phenylamino group include N-phenyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltriethoxysilane. Examples of silane coupling agents having the glycidyl group include 3-glycidyl etheroxypropyltrimethoxysilane and 3-glycidyl etheroxypropyltriethoxysilane.

[0038] It should be noted that, as the silane coupling agent, only one exemplified silane coupling agent may be used, or two or more may be used.

[0039] Regarding the roughening treatment, it can be a roughening treatment commonly performed during the manufacture of copper foil, without particular limitation, and examples include treatments that form roughening particles on the surface of the copper foil or the like, which are the work being treated. Through this roughening treatment, the surface of the copper foil is covered with roughening particles formed of copper or a copper alloy.

[0040] Regarding the heat-resistant treatment, it can be a heat-resistant treatment that is usually performed when manufacturing copper foil, without particular limitation. Examples include treatments that form a heat-resistant layer containing elements or alloys of nickel, cobalt, copper, and zinc.

[0041] Regarding the aforementioned rust-preventive treatment, it can be any rust-preventive treatment commonly performed during the manufacture of copper foil, without particular limitation, but preferably a treatment that forms a rust-preventive layer containing nickel. Furthermore, examples of such rust-preventive treatments include chromate treatment.

[0042] Furthermore, metal layer 3 may only have the copper foil described above. In addition, as long as metal layer 3 has the copper foil described above, it may also have a metal foil that can be used as a resin-coated metal foil. Specifically, metal layer 3 may also have, for example, copper foil, aluminum foil, and nickel foil other than the copper foil described above. Furthermore, when the metal foil is thin, from the viewpoint of improving operability, a carrier-coated metal foil having a release layer and a carrier can be used as metal layer 3.

[0043] Furthermore, the thickness of the metal layer 3 is not particularly limited, but is preferably 0.5 to 5 μm, and more preferably 1.5 to 3.0 μm.

[0044] [Resin Layer]

[0045] Resin layer 2 may contain a semi-cured resin composition, or it may contain the uncured resin composition. That is, the resin-bearing metal foil 1 may be a resin-bearing metal foil comprising: a resin layer 2 containing a semi-cured resin composition (the resin composition of stage B); and a metal layer 3; or it may be a resin-bearing metal foil 1 comprising: a resin layer 2 containing a resin composition before curing (the resin composition of stage A); and a metal layer 3. Furthermore, the resin composition or the semi-cured resin composition may be a substance obtained by drying or heating the resin composition.

[0046] Furthermore, the thickness of the resin layer 2 varies depending on the required performance of the printed wiring board obtained using the resin-coated metal foil 1, and is not particularly limited. For example, the thickness of the resin layer 2 is preferably 5 μm or more and 200 μm or less. By keeping the thickness of the resin layer 2 within this range, resin extrusion can be suppressed during heating and pressurization. Furthermore, the thickness of the printed wiring board can be easily adjusted when it is finished.

[0047] Furthermore, as resin layer 2, it may or may not contain a fibrous substrate, as long as it contains a resin composition or a semi-cured product of the resin composition. Examples of fibrous substrates include, for instance, glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and lint paper. It should be noted that using glass cloth results in a resin layer with excellent mechanical strength, and glass cloth that has undergone a flattening process is particularly preferred. As a flattening process, examples include methods that continuously apply appropriate pressure to the glass cloth using pressure rollers to compress the yarn into a flat shape. It should be noted that the thickness of the fibrous substrate typically used is, for example, 0.01 mm or more and 0.3 mm or less.

[0048] As described above, resin layer 2 contains a resin composition or a semi-cured form of the resin composition. The components contained in this resin composition will be described below.

[0049] The resin composition comprises: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent.

[0050] First, it is believed that by curing the polyphenylene ether compound together with the curing agent, the resin composition can produce a cured product that maintains the excellent low dielectric properties of polyphenylene ether, even when containing the polybutadiene compound and the styrene-based block copolymer. Furthermore, since the resin composition contains both the styrene-based block copolymer and the polybutadiene compound with intramolecular epoxy groups, a cured product with high adhesion to the metal layer can be obtained.

[0051] For the reasons stated above, a resin-coated metal foil having a resin layer comprising the resin composition or a semi-cured product of the resin composition, after curing, exhibits low dielectric properties and excellent adhesion between the resin layer and the metal layer.

[0052] (Polybutadiene compound)

[0053] The polybutadiene compound is not particularly limited to any polybutadiene compound having an intramolecular epoxy group. By containing the polybutadiene compound in the resin composition, the adhesion between the resin layer and the metal layer can be improved after the resin layer is cured. More specifically, the presence of an intramolecular epoxy group in the polybutadiene compound improves the adhesion between the resin layer and the metal layer.

[0054] Examples of the polybutadiene compounds include: epoxidized polybutadiene, i.e., compounds in which at least a portion of the carbon-carbon double bonds contained in polybutadiene are epoxidized, thereby introducing epoxy groups into the molecule; and compounds in which the ends of polybutadiene are etherified with glycidyl ether. It should be noted that the epoxidation is carried out, for example, by adding an oxygen atom to the carbon-carbon double bond contained in polybutadiene (unepoxidized polybutadiene) using an epoxidizing agent to form a three-membered ring epoxy group. Furthermore, compounds in which the ends of polybutadiene are etherified with glycidyl ether can be obtained by adding epichlorohydrin to polybutadiene with hydroxyl groups at both ends.

[0055] The carbon-carbon double bond stereostructure of the polybutadiene (unepoxidized polybutadiene) can be any one of cis-1,4, trans-1,4, cis-1,2, and trans-1,2. Furthermore, their ratios are not particularly limited.

[0056] The epoxidizing agent is not particularly limited as long as it can epoxidize the carbon-carbon double bonds contained in polybutadiene. Examples of such epoxidizing agents include: peracetic acid, performic acid, perbenzoic acid, trifluoroperacetic acid, perpropionic acid and other peroxycarboxylic acids; organic hydroperoxides such as tert-butyl hydroperoxide and cumene hydroperoxide; and hydrogen peroxide, etc.

[0057] The oxirane oxygen concentration in the polybutadiene compound is preferably 1 to 10% by mass, more preferably 5 to 9% by mass. If the oxirane oxygen concentration is too low, the effects of adding the polybutadiene compound and improving the adhesion between the resin layer and the metal layer after curing may not be fully achieved. Furthermore, if the oxirane oxygen concentration is too high, there will be too many epoxy groups, which may deteriorate the low dielectric properties. By using the polybutadiene compound with an oxirane oxygen concentration within the above range, a resin-coated metal foil with low dielectric properties after curing and high adhesion between the resin layer and the metal layer can be obtained more reliably.

[0058] It should be noted that the oxygen concentration of ethylene oxide serves as an indicator of the content of epoxy groups in the polybutadiene compound, and can be determined, for example, by the hydrogen bromide-glacial acetic acid solution method.

[0059] (polyphenylene ether compound)

[0060] The polyphenylene ether compound is not particularly limited as long as it is a polyphenylene ether compound having carbon-carbon unsaturated bonds. Examples of such polyphenylene ether compounds include those having at least one of the groups shown in formula (1) and formula (2) in the molecule, and preferably those containing the groups shown in formula (2) in the molecule.

[0061] Specifically, as the polyphenylene ether compound, examples include polyphenylene ether compounds having at least one of the groups shown in formula (1) and formula (2) at the molecule's end. More specifically, examples include modified polyphenylene ether compounds whose ends are modified by at least one of the groups shown in formula (1) and formula (2).

[0062]

[0063] In formula (1), p represents 0 to 10, Z represents arylene, and R1 to R3 each independently represent a hydrogen atom or an alkyl group.

[0064]

[0065] In formula (2), R4 represents a hydrogen atom or an alkyl group.

[0066] In formula (1), p represents 0 to 10. Furthermore, Z represents an arylene group. Additionally, R1 to R3 are independent. That is, R1 to R3 can be the same group or different groups. Furthermore, R1 to R3 represent hydrogen atoms or alkyl groups.

[0067] It should be noted that in the above formula (1), when p is 0, it means that Z is directly bonded to the end of the polyphenylene ether.

[0068] The arylene group is not particularly limited. Examples of such arylene groups include monocyclic aromatic groups such as phenylene, and polycyclic aromatic groups such as naphthalene rings, which are not monocyclic. Furthermore, the arylene group may also include derivatives formed by substituting the hydrogen atoms bonded to the aromatic ring with functional groups such as alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specifically, examples include methyl, ethyl, propyl, hexyl, and decyl.

[0069] In formula (2), R4 represents a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specifically, examples include methyl, ethyl, propyl, hexyl, and decyl.

[0070] Preferred examples of the group represented by formula (1) include vinylbenzyl (ethylene benzyl) and vinylphenyl, as shown in formula (3) below. Furthermore, examples of the vinylbenzyl group include o-vinylbenzyl, p-vinylbenzyl, and meta-vinylbenzyl. Furthermore, examples of the group represented by formula (2) include acryloyl and methacryloyl.

[0071]

[0072] The polyphenylene ether compound has at least one of the groups shown in formula (1) and formula (2) within its molecule. These groups may be one or more. The polyphenylene ether compound may have, for example, any one of o-vinylbenzyl, p-vinylbenzyl, and m-vinylbenzyl, or two or three of them.

[0073] The polyphenylene ether compound has a polyphenylene ether chain in the molecule, preferably having a repeating unit as shown in formula (4) below.

[0074]

[0075] In formula (4), t represents 1 to 50. Furthermore, R5 to R8 are independent. That is, R5 to R8 can be the same group or different groups. Additionally, R5 to R8 represent hydrogen atoms, alkyl, alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. Preferably, hydrogen atoms and alkyl groups are used.

[0076] Among R5 to R8, the listed functional groups are specifically listed as follows.

[0077] The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specifically, examples include methyl, ethyl, propyl, hexyl, and decyl.

[0078] The alkenyl group is not particularly limited, but is preferably an alkenyl group with 2 to 18 carbon atoms, and more preferably an alkenyl group with 2 to 10 carbon atoms. Specifically, examples include vinyl, allyl, and 3-butenyl.

[0079] The alkynyl group is not particularly limited, but is preferably an alkynyl group with 2 to 18 carbon atoms, and more preferably an alkynyl group with 2 to 10 carbon atoms. Specifically, examples include ethynyl and prop-2-yn-1-yl (propynyl).

[0080] The alkyl carbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkyl group. For example, it is preferably an alkyl carbonyl group with 2 to 18 carbon atoms, and more preferably an alkyl carbonyl group with 2 to 10 carbon atoms. Specifically, examples include acetyl, propionyl, butyryl, isobutyryl, neopentyl, hexanoyl, octanoyl, and cyclohexyl carbonyl.

[0081] The alkenyl carbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkenyl group. For example, an alkenyl carbonyl group with 3 to 18 carbon atoms is preferred, and an alkenyl carbonyl group with 3 to 10 carbon atoms is more preferred. Specifically, examples include acryloyl, methacryl, and crotonyl groups.

[0082] The alkynyl carbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkynyl group. For example, an alkynyl carbonyl group with 3 to 18 carbon atoms is preferred, and an alkynyl carbonyl group with 3 to 10 carbon atoms is more preferred. Specifically, examples include propynyl groups, etc.

[0083] The weight-average molecular weight (Mw) of the polyphenylene ether compound is not particularly limited. Specifically, it is preferably 500 to 5000, more preferably 800 to 4000, and even more preferably 1000 to 3000. It should be noted that here, the weight-average molecular weight can be any value obtained by measuring the molecular weight using a conventional molecular weight determination method, such as the value obtained by gel permeation chromatography (GPC). Furthermore, when the polyphenylene ether compound has repeating units as shown in formula (4) within its molecule, t is preferably a value that makes the weight-average molecular weight of the polyphenylene ether compound fall within the above-mentioned range. Specifically, t is preferably 1 to 50.

[0084] If the weight-average molecular weight of the polyphenylene ether compound is within the above-mentioned range, the polyphenylene ether compound not only possesses the excellent low dielectric properties of polyphenylene ether, but also exhibits superior heat resistance and formability of the cured product. This is believed to be based on the following reasons. In typical polyphenylene ethers, if the weight-average molecular weight is within the above-mentioned range, the molecular weight is relatively low, thus tending to reduce the heat resistance of the cured product. Regarding this point, it is believed that when the polyphenylene ether compound has at least one of the groups shown in formula (1) and formula (2) within its molecule, the cured product can obtain sufficiently high heat resistance. Furthermore, it is believed that if the weight-average molecular weight of the polyphenylene ether compound is within the above-mentioned range, the formability is also excellent because the molecular weight is relatively low. Therefore, it is believed that the polyphenylene ether compound can achieve the effect of not only superior heat resistance of the cured product, but also excellent formability. Based on this reason, if the weight-average molecular weight of the polyphenylene ether compound is within the above-mentioned range, it is possible to more reliably obtain resin-coated metal foils with superior heat resistance and formability after curing.

[0085] The average number (number of terminal functional groups) of at least one of the groups represented by formula (1) and the groups represented by formula (2) in each molecule of the polyphenylene ether compound is not particularly limited. Specifically, the number of terminal functional groups is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1.5 to 3.

[0086] It should be noted that the number of terminal functional groups in a polyphenylene ether compound can be exemplified by a numerical value representing the average number of substituents in each molecule of all polyphenylene ether compounds present in 1 mole of the compound. This number of terminal functional groups can be determined, for example, by measuring the number of residual hydroxyl groups in the resulting polyphenylene ether compound and calculating the reduction in the number of hydroxyl groups compared to the polyphenylene ether before modification. This reduction in the number of hydroxyl groups compared to the polyphenylene ether before modification is the number of terminal functional groups. Furthermore, the number of residual hydroxyl groups in the polyphenylene ether compound can be determined by adding a quaternary ammonium salt (tetraethylammonium hydroxide) associated with hydroxyl groups to a solution of the polyphenylene ether compound and measuring the UV absorbance of the mixed solution.

[0087] Examples of the polyphenylene ether compounds include those shown in formula (5) and those shown in formula (6). Furthermore, these polyphenylene ether compounds can be used alone or in combination.

[0088]

[0089]

[0090] In equations (5) and (6), R9~R 16 and R 17 ~R 24 Each of the following groups independently represents a hydrogen atom, alkyl, alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. X1 and X2 each independently represent the group shown in formula (1) or formula (2) above. A and B represent the repeating units shown in formula (7) and formula (8) below, respectively. Furthermore, in formula (6), Y represents a straight-chain, branched, or cyclic hydrocarbon with 20 or fewer carbon atoms.

[0091]

[0092]

[0093] In equations (7) and (8), m and n represent 0 to 20, respectively. 25 ~R 28 and R 29 ~R 32Each can independently represent a hydrogen atom, alkyl, alkenyl, alkynyl, formyl, alkyl carbonyl, alkenyl carbonyl, or alkynyl carbonyl.

[0094] The polyphenylene ether compounds shown in formula (5) and formula (6) are not particularly limited as long as they satisfy the above-described composition. Specifically, in formulas (5) and (6), as described above, R9 to R 16 and R 17 ~R 24 Each is independent. That is, R9 to R 16 and R 17 ~R 24 They can be the same group or different groups. Furthermore, R9 to R... 16 and R 17 ~R 24 It represents a hydrogen atom, alkyl, alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. Among these, hydrogen atoms and alkyl groups are preferred.

[0095] In equations (7) and (8), m and n are preferably represented as 0 to 20, as described above. Furthermore, the sum of m and n is preferably represented as a value between 1 and 30. Therefore, more preferably, m represents 0 to 20, n represents 0 to 20, and the sum of m and n represents 1 to 30. Furthermore, R 25 ~R 28 and R 29 ~R 32 Each is independent. That is, R 25 ~R 28 and R 29 ~R 32 They can be the same group or different groups. Furthermore, R... 25 ~R 28 and R 29 ~R 32 It represents a hydrogen atom, alkyl, alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. Among them, hydrogen atom and alkyl are preferred.

[0096] R9~R 32 R5 to R8 are the same as those in equation (4) above.

[0097] In formula (6), as described above, Y is a straight-chain, branched, or cyclic hydrocarbon with 20 or fewer carbon atoms. Examples of Y include groups such as those shown in formula (9) below.

[0098]

[0099] In equation (9), R 33 and R 34Each can be represented independently as a hydrogen atom or an alkyl group. Examples of alkyl groups include methyl. In addition, examples of groups represented by formula (9) include methylene, methylmethylene and dimethylmethylene, among which dimethylmethylene is preferred.

[0100] In formulas (5) and (6), X1 and X2 are each independently a group represented by formula (1) or a group represented by formula (2). It should be noted that in the polyphenylene ether compound shown in formula (5) and the polyphenylene ether compound shown in formula (6), X1 and X2 can be the same group or different groups.

[0101] As a more specific example of the polyphenylene ether compound represented by formula (5), examples such as the polyphenylene ether compound represented by formula (10) below can be cited.

[0102]

[0103] As more specific examples of the polyphenylene ether compound represented by formula (6), examples include the polyphenylene ether compound represented by formula (11) below and the polyphenylene ether compound represented by formula (12) below.

[0104]

[0105]

[0106] In equations (10) to (12) above, m and n are the same as m and n in equations (7) and (8) above. Furthermore, in equations (10) and (11) above, R1 to R3, p and Z are the same as R1 to R3, p and Z in equation (1) above. Furthermore, in equations (11) and (12) above, Y is the same as Y in equation (6) above. Furthermore, in equation (12) above, R4 is the same as R1 in equation (2) above.

[0107] The method for synthesizing the polyphenylene ether compound that can be used in this embodiment is not particularly limited as long as it can synthesize a polyphenylene ether compound having carbon-carbon unsaturated bonds. Here, a method for synthesizing a modified polyphenylene ether compound whose end is modified by at least one of the groups shown in formula (1) and formula (2) can be described. As a method, specifically, a method of reacting polyphenylene ether with a compound having at least one of the groups shown in formula (1) and formula (2) and a halogen atom can be listed. As the halogen atom, specifically, chlorine atom, bromine atom, iodine atom and fluorine atom can be listed, with chlorine atom being preferred. As the compound having at least one of the groups shown in formula (1) and formula (2) and a halogen atom, more specifically, o-chloromethylstyrene, p-chloromethylstyrene, m-chloromethylstyrene, etc. The compound having at least one of the groups shown in formula (1) and formula (2) and a halogen atom can be used alone or in combination of two or more. For example, o-chloromethylstyrene, p-chloromethylstyrene, and m-chloromethylstyrene can be used alone, or two or three can be used in combination.

[0108] The polyphenylene ether used as a raw material is not particularly limited as long as it can ultimately synthesize the specified modified polyphenylene ether compound. Specifically, examples include compounds whose main component is a polyphenylene ether containing "2,6-dimethylphenol" and "at least one of bifunctional and trifunctional phenols," or poly(2,6-dimethyl-1,4-phenylene ether). Furthermore, a bifunctional phenol is a phenolic compound having two phenolic hydroxyl groups within its molecule, such as tetramethylbisphenol A. A trifunctional phenol is a phenolic compound having three phenolic hydroxyl groups within its molecule.

[0109] (Styrene-based block copolymer)

[0110] The styrene-based block copolymer is not particularly limited to any styrene-based block copolymer containing resins that can be used as insulating layers in resin compositions used to form resin layers in resin-coated metal foils, metal foil laminates, wiring boards, etc.

[0111] Examples of styrene-based block copolymers include, for example, substances comprising at least one selected from the group consisting of methylstyrene (ethylene / butene) methylstyrene copolymer, methylstyrene (ethylene-ethylene / propylene) methylstyrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene (ethylene / butene) styrene copolymer, styrene (ethylene-ethylene / propylene) styrene copolymer, styrene-butadiene-styrene copolymer, styrene (butadiene / butene) styrene copolymer, styrene-isobutylene-styrene copolymer, and their hydrides.

[0112] The styrene-based block copolymer preferably includes styrene-butadiene-styrene copolymer, styrene (ethylene / butene)-styrene copolymer, methylstyrene (ethylene / butene)-methylstyrene copolymer, and their hydrides. Furthermore, the styrene-based block copolymer can be used alone or in combination of two or more.

[0113] By including the styrene-based block copolymer in the resin composition, a resin-coated metal foil with excellent adhesion to the metal layer can be obtained after curing the resin layer.

[0114] (Curing agent)

[0115] The curing agent is a curing agent that can react with the polyphenylene ether compound to cure the resin composition containing the polyphenylene ether compound. Furthermore, the curing agent is not particularly limited as long as it can cure the resin composition containing the polyphenylene ether compound. Examples of such curing agents include: styrene, styrene derivatives, compounds having an acryloyl group in the molecule, compounds having a methacryloyl group in the molecule, compounds having a vinyl group in the molecule, compounds having an allyl group in the molecule, compounds having an acenaphthene structure in the molecule, compounds having a maleimide group in the molecule, and isocyanurate compounds having an isocyanurate group in the molecule.

[0116] Examples of styrene derivatives include bromostyrene and dibromostyrene.

[0117] The compound having an acryloyl group within its molecule is an acrylate compound. Examples of such acrylate compounds include monofunctional acrylate compounds having one acryloyl group within their molecule, and polyfunctional acrylate compounds having two or more acryloyl groups within their molecule. Examples of monofunctional acrylate compounds include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Examples of polyfunctional acrylate compounds include diacrylate compounds such as tricyclodecanediethanol diacrylate.

[0118] The compound having a methacryl group within its molecule is a methacrylate compound. Examples of such methacrylate compounds include monofunctional methacrylate compounds having one methacryl group within their molecule, and polyfunctional methacrylate compounds having two or more methacryl groups within their molecule. Examples of monofunctional methacrylate compounds include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. Examples of polyfunctional methacrylate compounds include dimethacrylate compounds such as tricyclodecanediethanol dimethacrylate, and trimethacrylate compounds such as trimethylolpropane trimethacrylate.

[0119] The compound having a vinyl group within its molecule is a vinyl compound. Examples of such vinyl compounds include monofunctional vinyl compounds having one vinyl group within their molecule (monofunctional vinyl compounds) and polyfunctional vinyl compounds having two or more vinyl groups within their molecule. Examples of such polyfunctional vinyl compounds include, for example, divinylbenzene and polybutadiene.

[0120] The compound having an allyl group within its molecule is an allyl compound. Examples of such allyl compounds include monofunctional allyl compounds having one allyl group within their molecule, and polyfunctional allyl compounds having two or more allyl groups within their molecule. Examples of such polyfunctional allyl compounds include, for example, triallyl isocyanurate compounds such as triallyl isocyanurate (TAIC), diallyl bisphenol compounds, and diallyl phthalate (DAP).

[0121] The compound having an intramolecular acenaphthene structure is an acenaphthene compound. Examples of such acenaphthene compounds include: acenaphthene, alkylacenaphthenes, haloacenaphthenes, and phenylacenaphthenes. Examples of such alkylacenaphthenes include: 1-methylacenaphthene, 3-methylacenaphthene, 4-methylacenaphthene, 5-methylacenaphthene, 1-ethylacenaphthene, 3-ethylacenaphthene, 4-ethylacenaphthene, 5-ethylacenaphthene, etc. Examples of such haloacenaphthenes include: 1-chloroacenaphthene, 3-chloroacenaphthene, 4-chloroacenaphthene, 5-chloroacenaphthene, 1-bromoacenaphthene, 3-bromoacenaphthene, 4-bromoacenaphthene, 5-bromoacenaphthene, etc. Examples of phenylacenaphthenes include 1-phenylacenaphthene, 3-phenylacenaphthene, 4-phenylacenaphthene, and 5-phenylacenaphthene. The acenaphthene compound can be a monofunctional acenaphthene compound having one acenaphthene structure within the molecule, as described above, or a polyfunctional acenaphthene compound having two or more acenaphthene structures within the molecule.

[0122] The compound having a maleimide group within its molecule is a maleimide compound. Examples of such maleimide compounds include: monofunctional maleimide compounds having one maleimide group within their molecule; polyfunctional maleimide compounds having two or more maleimide groups within their molecule; and modified maleimide compounds. Examples of such modified maleimide compounds include: modified maleimide compounds in which a portion of the molecule is modified by an amine compound; modified maleimide compounds in which a portion of the molecule is modified by an organosilicon compound; and modified maleimide compounds in which a portion of the molecule is modified by both an amine compound and an organosilicon compound.

[0123] The compound having an isocyanurate group within the molecule is an isocyanurate compound. Examples of such isocyanurate compounds include compounds that further have an alkenyl group within the molecule (alkenyl isocyanurate compounds), such as triallyl isocyanurate compounds (TAIC).

[0124] In the above, the curing agent preferably comprises, for example, an allyl compound having an allyl group in the molecule. As the allyl compound, an allyl isocyanurate compound having two or more allyl groups in the molecule is preferred, and triallyl isocyanurate (TAIC) is more preferred.

[0125] Regarding the curing agent, it can be used alone or in combination of two or more. The curing agent preferably comprises the allyl compound, and more preferably comprises an allyl isocyanurate compound having two or more allyl groups within its molecule.

[0126] (content)

[0127] Relative to the total mass (total weight) of the polybutadiene compound, the polyphenylene ether compound, and the curing agent, the content of the polybutadiene compound is preferably 5-38% by mass, more preferably 5-32% by mass, and even more preferably 5-15% by mass. Furthermore, relative to the total mass (total weight) of the polybutadiene compound, the polyphenylene ether compound, the styrene-based block copolymer, and the curing agent, the content of the polybutadiene compound is preferably 3-25% by mass, more preferably 3-20% by mass, and even more preferably 5-15% by mass. Furthermore, relative to the total mass (total weight) of the polybutadiene compound, the polyphenylene ether compound, the styrene-based block copolymer, and the curing agent, the content of the polyphenylene ether compound is preferably 10-70% by mass, more preferably 20-50% by mass. Furthermore, relative to the total mass (total weight) of the polybutadiene compound, the polyphenylene ether compound, the styrene-based block copolymer, and the curing agent, the content of the styrene-based block copolymer is preferably 5-60% by mass, more preferably 10-50% by mass. Furthermore, relative to the total mass (total amount) of the polybutadiene compound, the polyphenylene ether compound, the styrene-based block copolymer, and the curing agent, the content of the curing agent is preferably 3 to 30% by mass, more preferably 5 to 20% by mass. If the contents of each of the polybutadiene compound, the polyphenylene ether compound, the styrene-based block copolymer, and the curing agent are within the above ranges, a resin-coated metal foil that maintains excellent low dielectric properties after curing and exhibits higher adhesion between the resin layer and the metal layer can be obtained.

[0128] (Other ingredients)

[0129] The resin composition may, as needed and without impairing the effects of the present invention, contain components other than the polybutadiene compound, the polyphenylene ether compound, the styrene-based block copolymer, and the curing agent (other components). As other components contained in the resin composition, it may further contain additives such as silane coupling agents, flame retardants, initiators, curing accelerators, defoamers, antioxidants, polymerization inhibitors, polymerization retardants, dispersants, homogenizers, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes or pigments, lubricants, and fillers. Furthermore, in addition to the polyphenylene ether compound, the resin composition may also contain thermosetting resins such as epoxy resins, unsaturated polyester resins, and thermosetting polyimide resins.

[0130] As described above, the resin composition may also contain an initiator (reaction initiator). The resin composition can undergo a curing reaction even without a reaction initiator. However, depending on the process conditions, it may be difficult to raise the temperature until curing occurs, so a reaction initiator may be added. The reaction initiator is not particularly limited as long as it can promote the curing reaction between the polyphenylene ether compound and the curing agent. Specifically, examples include oxidants such as α,α'-bis(tert-butylperoxym-isopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, benzoyl peroxide, 3,3',5,5'-tetramethyl-1,4-diphenol benzoquinone, chloroquinone, 2,4,6-tritert-butylphenoxy, tert-butylperoxyisopropyl monocarbonate, and azobisisobutyronitrile. Furthermore, metal carboxylic acid salts may be used in combination as needed. This further promotes the curing reaction. α,α'-bis(tert-butylperoxym-isopropyl)benzene is preferred. Because α,α'-bis(tert-butylperoxym-isopropyl)benzene has a relatively high reaction initiation temperature, it can suppress the promotion of the curing reaction during prepreg drying and other times when curing is not required, thus preventing a decrease in the shelf life of the resin composition. Furthermore, due to its low volatility, α,α'-bis(tert-butylperoxym-isopropyl)benzene does not volatilize during prepreg drying and storage, exhibiting good stability. In addition, the reaction initiator can be used alone or in combination of two or more.

[0131] As described above, the resin composition may contain fillers such as inorganic fillers. Examples of fillers include materials added during the curing of the resin layer to improve heat resistance and flame retardancy, and there are no particular limitations. Furthermore, by containing fillers, heat resistance and flame retardancy can be further improved. Specifically, the filler preferably comprises at least one filler selected from the group consisting of silica such as spherical silica; metal oxides such as alumina, titanium dioxide, and mica; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; talc, aluminum borate, barium sulfate, and calcium carbonate. Furthermore, as a filler, it is more preferable to include at least one filler selected from the group consisting of silica, mica, and talc, and even more preferably to include a filler composed of spherical silica. Additionally, a single filler may be used, or two or more may be used in combination. Furthermore, the filler may be used directly, or a filler surface-treated with the silane coupling agent may be used. Furthermore, when the resin composition contains filler material, its content (filler content) is preferably 20 to 270 parts by weight, more preferably 30 to 250 parts by weight, relative to 100 parts by weight of the resin composition.

[0132] There are no particular limitations on the method for manufacturing the resin composition, and examples include: mixing the polybutadiene compound, the polyphenylene ether compound, the styrene block copolymer and the curing agent at specified amounts.

[0133] [Manufacturing Method]

[0134] The method for manufacturing resin-coated metal foil according to this embodiment is not particularly limited as long as it can manufacture resin-coated metal foils 1 and 1' as described above. For example, as a method for manufacturing such... Figure 1 The method of manufacturing a metal foil 1 with resin on one side of the resin layer 2, as shown, can be exemplified by preparing the above-mentioned resin composition in the form of a varnish, coating the varnish-like resin composition onto the contact surface 4 of the copper foil, and heating it.

[0135] A varnish-like resin composition (resin varnish) can be prepared, for example, as follows: First, the components soluble in an organic solvent are added to and dissolved in an organic solvent. Heating may be performed at this time, if necessary. Then, the components insoluble in the organic solvent, as needed, are added, and the mixture is dispersed to a specified dispersion state using a ball mill, bead mill, planetary mixer, roller mill, etc., thereby preparing a varnish-like composition. The organic solvent used herein is not particularly limited, as long as it can dissolve the components soluble in the organic solvent and does not hinder the curing reaction. Specifically, examples include toluene and methyl ethyl ketone (MEK).

[0136] For example, the varnish-like resin composition is applied to the contact surface 4 of the copper foil using a doctor blade coater. The applied resin composition is heated, for example, at a temperature of 40°C or higher and 180°C or lower, for a time of 0.1 minutes or higher and 10 minutes or lower. By heating, a resin layer 2 in a pre-cured (stage A) or semi-cured (stage B) state can be obtained. That is, the heated resin composition forms an uncured or semi-cured resin layer 2 on the contact surface 4 of the copper foil. It should be noted that by heating, the organic solvent is evaporated from the resin varnish, thereby reducing or removing the organic solvent.

[0137] In addition, as a manufacturer such as Figure 2 The method of contacting the copper foil with the resin-coated metal foil 1' on both sides of the resin layer 2 as shown can be exemplified by manufacturing, for example, by the method described above. Figure 1 The method involves manufacturing a resin-coated metal foil 1 by overlapping two resin-coated metal foils 1 together with resin layers 2 in contact with each other, and then heating them. The heating temperature is preferably 180°C or higher and 230°C or lower, and the heating time is preferably 60 minutes or higher and 150 minutes or lower.

[0138] The resin-coated metal foil described in this embodiment can be used in the manufacture of wiring boards that have a low dielectric property, a high degree of adhesion to wiring, excellent laser processability, and reduced signal transmission losses. Furthermore, for example, a multilayer wiring board can be manufactured by laminating the resin-coated metal foil onto the wiring board.

[0139] <Metal Foil Laminate>

[0140] Figure 3 This is a schematic cross-sectional view illustrating an example of a metal foil laminate 11 according to an embodiment of the present invention. Figure 3 In the diagram, the symbols represent: 11: metal foil laminate, 12: insulating layer, 13: metal layer, and 14: the surface where the copper foil contacts the insulating layer 12 (hereinafter also referred to as the contact surface).

[0141] like Figure 3 As shown, the metal foil laminate 11 includes: an insulating layer 12 comprising a cured resin composition; and a metal layer 13. It should be noted that, in Figure 3 In this configuration, the metal layer 13 is stacked on both sides of the insulating layer 12; however, it may also be stacked on only one side of the insulating layer 12. The metal layer 13 has a copper foil in contact with the surface of the insulating layer 12. The thickness of the copper foil is 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface (contact surface) 14 of the copper foil in contact with the insulating layer 12 is 0.6 μm or less, and the ten-point mean roughness (Rzjis) of this surface is 3.0 μm or less. The resin composition contains: a polybutadiene compound having an epoxy group in its molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent. The metal-clad laminate with this configuration has an insulating layer with low dielectric properties and high adhesion to the metal layer, and exhibits excellent laser processability, reducing signal transmission losses in the resulting wiring board. It should be noted that, regarding the resin composition and metal layer 13, since the same resin composition and metal layer as those in the resin-coated metal foil 1 and metal layer 3 can be used, specific details are omitted.

[0142] The insulating layer 12 can be formed from a cured resin composition or from a cured prepreg, as described later. Furthermore, the thickness of the insulating layer 12 is preferably 5 μm or more and 400 μm or less.

[0143] As for the method of manufacturing the metal foil laminate 11, there is no particular limitation as long as it is possible to manufacture the metal foil laminate 11. Specifically, methods can be listed as using a prepreg having a resin layer comprising the resin composition or a semi-cured product of the resin composition, and a fibrous substrate to manufacture the metal foil laminate 11.

[0144] The prepreg comprises: a resin layer containing the resin composition or a semi-cured product of the resin composition; and a fibrous substrate present in the resin layer. As the fibrous substrate, any fibrous substrate that can be used in the resin-coated metal foil 1 can be used without limitation.

[0145] In manufacturing the prepreg, in order to impregnate the substrate used to form the prepreg, i.e., the fibrous substrate, the resin composition is in most cases formulated as a varnish-like resin varnish as described above.

[0146] The method for manufacturing the prepreg is not particularly limited as long as it can produce the prepreg. Examples of methods for manufacturing the prepreg include impregnating the fibrous substrate with the aforementioned varnish-like resin composition and then drying it. Impregnation of the resin composition into the fibrous substrate is performed by impregnation and coating, etc. Impregnation can be repeated multiple times as needed. Furthermore, the final desired composition and impregnation amount can be adjusted by repeatedly impregnating with various resin compositions of different compositions and concentrations.

[0147] A fibrous substrate impregnated with the resin composition (resin varnish) is heated under desired heating conditions (e.g., heating at 80°C or higher and 180°C or lower for 1 minute or more and 10 minutes or less). Heating yields a prepreg in a pre-cured (Stage A) or semi-cured (Stage B) state. It should be noted that the heating causes the organic solvent to evaporate from the resin varnish, thus reducing or eliminating the organic solvent.

[0148] To produce the prepreg as described above, take one piece of the prepreg or overlap several pieces of the prepreg, and overlap a metal layer 13 on its upper and lower surfaces or one side surface in such a way that copper foil contacts the prepreg. Heat and press the metal layer 13 and the prepreg to form an integral laminate, thereby producing a laminate 11 with metal foil on both sides or one side surface.

[0149] That is, the metal-clad laminate 11 is obtained by laminating a metal layer 13 onto a prepreg and then heating and pressing it. Furthermore, the heating and pressing conditions can be appropriately set according to the thickness of the manufactured metal-clad laminate 11 or the type of prepreg composition. For example, the temperature can be set to 170–230°C, the pressure to 2–5 MPa, and the time to 60–150 minutes. Alternatively, the metal-clad laminate can also be manufactured without using a prepreg. Examples include methods such as coating a varnish-like resin composition onto the surface of a copper foil, forming a layer containing the resin composition on the surface of the copper foil, and then heating and pressing it.

[0150] <Wiring board>

[0151] Figure 4This is a schematic cross-sectional view illustrating an example of a wiring board 21 according to an embodiment of the present invention. Figure 4 In the diagram, the symbols represent: 21: wiring board, 23: first copper conductor layer, 24: the surface where the first copper conductor layer 23 contacts the insulating layer 12 (hereinafter also referred to as the contact surface), 25: second copper conductor layer, and 26: wiring.

[0152] like Figure 4 As shown, the wiring board 21 according to this embodiment includes: an insulating layer 12 comprising a cured resin composition; and wiring 26, wherein the wiring 26 is formed by partially removing a metal layer laminated on both sides or one side of the insulating layer 12, and plating the surface of the metal layer that is not in contact with the insulating layer 12. It should be noted that, regarding the metal layer, since the same metal layer as the metal layer 3 in the resin-coated metal foil 1 can be used, a detailed description is omitted.

[0153] The wiring board 21 comprises: an insulating layer 12 containing a cured resin composition; and wiring 26, wherein the resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent. The wiring 26 comprises: a first copper conductor layer 23 in contact with the surface of the insulating layer 12; and a second copper conductor layer 25 laminated on the first copper conductor layer 23. The thickness of the first copper conductor layer 23 is 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface 24 of the first copper conductor layer 23 in contact with the insulating layer 12 is 0.6 μm or less, and the ten-point mean roughness (Rzjis) of the surface is 3.0 μm or less. It should be noted that the wiring board 21 can be as follows: Figure 4 The wiring 26 can be formed on both sides of the insulating layer 12, or it can be formed on only one side of the insulating layer 12. Furthermore, regarding the resin composition, since the same resin composition as that used in the resin-bearing metal foil 1 can be used, specific details are omitted.

[0154] It should be noted that, regarding the first copper conductor layer 23, the same copper foil as the copper foil in the resin-coated metal foil 1 can be used. Furthermore, the second copper conductor layer 25 is formed, for example, by plating the surface of the first copper conductor layer 23 opposite to the contact surface 24. This plating process is not particularly limited, and examples include electroless copper plating and electrolytic copper plating. The thickness of the second copper conductor layer 25 is preferably 0.1 to 100 μm.

[0155] The wiring board with this configuration has an insulating layer with low dielectric properties and high adhesion to the wiring. Furthermore, this wiring board has the advantage that, for example, when forming circuits through micro-circuit fabrication using a semi-additive process (SAP) or a modified semi-additive process (MSAP), the wiring is difficult to peel off from the insulating layer when forming vias using laser processing. Moreover, it has the advantage of being able to form vias even with smaller apertures. Therefore, the wiring board exhibits excellent laser machinability. In addition, the wiring board is expected to reduce signal transmission losses, and for example, it can be suitable for use in electronic devices that transmit and receive electrical signals at high speeds.

[0156] The method for manufacturing the wiring board according to this embodiment is not particularly limited as long as it can manufacture the wiring board 21. Specifically, a method of using the prepreg to manufacture the wiring board 21 can be cited. As a method, for example, etching the metal foil 13 on the surface of the metal foil laminate 11 manufactured as described above, and then depositing a plating layer on the etched metal layer 13 to form wiring 26, thereby manufacturing a wiring board 21 with wiring 26 as a circuit on the surface of the insulating layer 12. In addition, as a method for forming the circuit, besides the method described above, methods for forming the circuit by means of a semi-additive process (SAP) or a modified semi-additive process (MSAP) can be cited.

[0157] This specification discloses various implementation techniques as described above, and the main techniques therein are summarized below.

[0158] The resin-coated metal foil of the first technical solution comprises: a resin layer containing a resin composition or a semi-cured form of the resin composition; and a metal layer located on at least one side surface of the resin layer, wherein the resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent, the metal layer having a copper foil in contact with the surface of the resin layer, the copper foil having a thickness of 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface of the copper foil in contact with the resin layer being 0.6 μm or less, and the ten-point mean roughness (Rzjis) of the surface being 3.0 μm or less.

[0159] The resin-coated metal foil of the second technical solution is in the resin-coated metal foil of the first technical solution, wherein the polyphenylene ether compound comprises a polyphenylene ether compound having at least one of the groups shown in formula (1) and formula (2) below in the molecule.

[0160]

[0161] In formula (1), p represents 0 to 10, Z represents arylene, and R1 to R3 each independently represent a hydrogen atom or an alkyl group.

[0162]

[0163] In formula (2), R4 represents a hydrogen atom or an alkyl group.

[0164] In the resin-coated metal foil of the third technical solution, the content of the polybutadiene compound is 5 to 38% by mass relative to the total amount of the polybutadiene compound, the polyphenylene ether compound, and the curing agent.

[0165] In the resin-coated metal foil of the fourth technical solution, the content of the polybutadiene compound is 3 to 25% by mass relative to the total amount of the polybutadiene compound, the polyphenylene ether compound, the styrene block copolymer and the curing agent.

[0166] The resin-coated metal foil of the fifth technical solution, in any one of the first to fourth technical solutions, wherein the curing agent comprises an allyl compound.

[0167] The resin-coated metal foil of the sixth technical solution is in the resin-coated metal foil of the fifth technical solution, wherein the allyl compound comprises an allyl isocyanurate compound having two or more allyl groups in the molecule.

[0168] In the resin-coated metal foil of any one of the first to sixth technical solutions, the ethylene oxide oxygen concentration in the polybutadiene compound is 1 to 10 by mass.

[0169] The resin-coated metal foil of the eighth technical solution, in any one of the resin-coated metal foils of the first to seventh technical solutions, comprises a styrene-based block copolymer comprising at least one selected from the group consisting of methylstyrene (ethylene / butene) methylstyrene copolymer, methylstyrene (ethylene-ethylene / propylene) methylstyrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene (ethylene / butene) styrene copolymer, styrene (ethylene-ethylene / propylene) styrene copolymer, styrene-butadiene-styrene copolymer, styrene (butadiene / butene) styrene copolymer, styrene-isobutylene-styrene copolymer, and their hydrides.

[0170] The resin-coated metal foil of the 9th technical solution is in the resin-coated metal foil of the 2nd technical solution, wherein the polyphenylene ether compound comprises a polyphenylene ether compound having a group represented by the formula (2) within the molecule.

[0171] The 10th technical solution's metal-clad laminate includes: an insulating layer, a cured product comprising a resin composition; and a metal layer located on at least one side surface of the insulating layer, wherein the resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent, the metal layer having a copper foil in contact with the surface of the insulating layer, the copper foil having a thickness of 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface of the copper foil in contact with the insulating layer being 0.6 μm or less, and the ten-point mean roughness (Rzjis) of the surface being 3.0 μm or less.

[0172] The wiring board of the 11th technical solution includes: an insulating layer, a cured product containing a resin composition; and wiring located on at least one side surface of the insulating layer, wherein the resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; a styrene-based block copolymer; and a curing agent, the wiring having: a first copper conductor layer in contact with the surface of the insulating layer; and a second copper conductor layer laminated on the first copper conductor layer, the thickness of the first copper conductor layer being 5.0 μm or less, the arithmetic mean roughness (Ra) of the surface of the first copper conductor layer in contact with the insulating layer being 0.6 μm or less, and the ten-point mean roughness (Rzjis) of the surface being 3.0 μm or less.

[0173] The present invention will be further described in detail below through embodiments; however, the scope of the present invention is not limited to these embodiments.

[0174] Example

[0175] [Examples 1-7 and Comparative Examples 1-4]

[0176] The components used in preparing the resin composition in this embodiment will be described.

[0177] (Contains epoxy-based polybutadiene)

[0178] Epoxy-containing polybutadiene: Polybutadiene compounds containing epoxy groups within the molecule (JP-100 manufactured by Nippon Soda Co., Ltd., ethylene oxide concentration: 7.7% by mass).

[0179] (Polyphenylene oxide compound: PPE)

[0180] Modified PPE: Polyphenylene ether compounds with methacryloyl groups at the ends (modified polyphenylene ethers with methacryloyl groups at the ends, represented by the above formula (12), and Y in formula (12) is dimethylmethylene (represented by formula (9) and R in formula (9) 33 and R 34 (A modified polyphenylene ether compound with methyl groups, SA9000 manufactured by SABIC Innovative Plastics, with a weight-average molecular weight of Mw2000 and 2 terminal functional groups)

[0181] (Styrene-based block copolymer)

[0182] Tuftec H1221: Hydrogenated styrene-based thermoplastic elastomer (SEBS) (H1221 manufactured by Asahi Kasei Corporation)

[0183] (Curing agent: allyl compound)

[0184] TAIC: Triallyl isocyanurate (TAIC manufactured by Nippon Chemical Co., Ltd.)

[0185] (other)

[0186] • Initiator: α,α'-Di(tert-butylperoxy)diisopropylbenzene (PERBUTYL P (PBP) manufactured by Nippon Oil Co., Ltd.)

[0187] • Filler material: Spherical silica filler (dry powder) SC2500SQ (manufactured by Yaduma Corporation, 2500SQ, average particle size 0.6μm)

[0188] [Preparation method of resin composition]

[0189] First, all components except the filler were added to toluene according to the composition (parts by mass) listed in Table 1 and mixed to achieve a solids concentration of 50% by mass. The mixture was stirred for 60 minutes. Then, the filler was added to the resulting liquid and dispersed using a bead mill. This process yielded a varnish-like resin composition (varnish).

[0190] [Method for making resin-coated metal foil]

[0191] Next, the obtained varnish is applied to any of the copper foils (copper foils 1 to 5) described below, to a thickness of 30 μm, and heated at 100°C for 1 minute, thereby producing a resin-coated metal foil with copper foil bonded to one side of the resin layer. It should be noted that Ra and Rzjis of copper foils 1 to 5 described below are the values ​​of Ra and Rzjis of the copper foil on the surface in contact with the resin layer.

[0192] (Metallic layer: copper foil)

[0193] Copper foil 1: MT18FL (manufactured by Mitsui Metals & Mining Co., Ltd., Ra: 0.2μm, Rzjis: 1.3μm)

[0194] • Copper foil 2: MT18Ex (manufactured by Mitsui Metals & Mining Co., Ltd., Ra: 0.3μm, Rzjis: 2.0μm)

[0195] Copper foil 3: GTH-MP (Furukawa Copper Foil Co., Ltd., Taiwan; Ra: 1.2μm; Rzjis: 6.5μm)

[0196] • Copper foil 4: 3EC-VLP (manufactured by Mitsui Metals & Mining Co., Ltd., Ra: 0.6μm, Rzjis: 3.5μm)

[0197] • Copper foil 5: TLC-V1 (manufactured by Nan Ya Plastics Industrial Co., Ltd., Ra: 0.2μm, Rzjis: 1.3μm)

[0198] [Method for manufacturing a cured resin-coated metal foil laminate]

[0199] Two resin-coated metal foils obtained above are overlapped with the resin layers in contact with each other, and heated and pressurized at 200°C and 3MPa for 100 minutes to produce a cured product of the resin-coated metal foil (metal foil laminate).

[0200] [evaluate]

[0201] The properties were evaluated using a resin-coated metal foil (evaluation substrate 1) and a cured resin-coated metal foil (evaluation substrate 2) prepared as described above, by the method shown below.

[0202] (Dielectric properties (relative permittivity and dielectric loss factor))

[0203] The copper foil was removed from the evaluation substrate 2 as a test piece, and the relative permittivity and dielectric loss factor at 10 GHz were determined using the resonant cavity perturbation method. Specifically, the relative permittivity and dielectric loss factor of the test piece at 10 GHz were determined using a network analyzer (N5230A manufactured by Agilent Technologies, Inc.).

[0204] (Copper foil peel strength)

[0205] The copper foil was peeled off from evaluation substrate 2, and the peel strength (copper foil peel strength) was measured according to JIS C 6481. Specifically, the copper foil was peeled off from evaluation substrate 2 using a tensile testing machine at a speed of 50 mm / min, and the peel strength (N / mm) was measured. The acceptance criterion in this test was ≥0.40 N / mm.

[0206] (Laser processability)

[0207] First, a test piece (4-layer board) for evaluating laser processability was obtained as follows. Evaluation substrate 1 was stacked on both sides of a core material (manufactured by Panasonic Machinery Co., Ltd., "R-1515A", thickness 0.4 mm, copper foil thickness 12 μm) with the copper foil of the core material in contact with a resin layer of resin-coated metal foil. The test piece (4-layer board) was then fabricated by heating and pressurizing at 200°C and 3 MPa for 100 minutes. The test piece (4-layer board) was evaluated using the method described below.

[0208] Copper foil peeling due to the formation of through-holes

[0209] A laser was irradiated onto a test substrate (4-layer board) to create multiple via openings with a spacing of 30 μm between them. Specifically, a Mitsubishi Electric ML605GTWV(-P)-5350U laser device was used, and processing was performed under the following conditions: mask: 0.8 mm, pulse width: 6 microseconds, energy: 2.2 millijoules, and single pulse. The laser-processed test substrate was then observed from directly above using a microscope to check for copper foil peeling between the vias. Specifically, this was observed using an optical microscope (Keyence VHX-7000).

[0210] • Diameter of the top of the through hole

[0211] A laser was applied to the test piece (4-layer plate). Specifically, a Mitsubishi Electric ML605GTWV(-P)-5350U laser device was used, and processing was performed under the following conditions: mask: 0.8 mm, pulse width: 6 microseconds, energy: 2.2 millijoules, single pulse. The aperture opening was observed from directly above using a microscope, and the aperture diameter was measured. Specifically, an MF-UJ4020D microscope manufactured by Mitutoyo Corporation was used for observation. The acceptable diameter in this test was 15 μm or larger.

[0212] (Transmission loss evaluation test)

[0213] The evaluation substrate 2 was processed on one side with a linewidth of 100–200 μm to obtain a test piece. The linewidth was adjusted so that the characteristic impedance of the fabricated circuit would be 50 Ω.

[0214] To evaluate transmission characteristics, the transmission loss (transmission loss) was measured on the obtained test piece using a network analyzer (Keysight Technologies N5222B). It should be noted that the evaluation frequency was 60 GHz. The pass / fail criterion in this test was an absolute transmission loss of less than 1.38 dB / inch.

[0215] The results of the above evaluations are shown in Table 1.

[0216]

[0217] [Inspection]

[0218] As shown in Table 1, in the resin composition containing the polyphenylene ether compound, the styrene-based block copolymer, and the cured product, the case containing an intramolecularly epoxy-containing polybutadiene compound (Examples 1-7) exhibits lower dielectric properties and higher copper foil peel strength compared to the case not containing an intramolecularly epoxy-containing polybutadiene compound (Comparative Example 1). Furthermore, in Examples 1-7, where laser processing was performed to form through-holes, no copper foil peeling occurred between through-holes, demonstrating excellent laser processability. Additionally, when using copper foil with a thickness of 5.0 μm or less (Examples 1-7), the top diameter of the through-hole was 15 μm or more. On the other hand, when using a thicker copper foil (Comparative Examples 2-4), the top diameter of the through-hole did not reach 15 μm or more. In other words, the case using copper foil with a thickness of 5.0 μm or less (Examples 1-7) demonstrates superior laser processability compared to the case using a thicker copper foil (Comparative Examples 2-4), enabling the formation of through-holes even when forming smaller apertures.

[0219] Furthermore, it is known that Examples 1-7, in which the arithmetic mean roughness (Ra) of the surface in contact with the resin layer in the copper foil is less than 0.6 μm and the ten-point average roughness (Rzjis) is less than 3.0 μm, have less transmission loss (smaller absolute value of transmission loss) compared to Comparative Examples 2-3, in which the arithmetic mean roughness (Ra) of the surface in contact with the resin layer is less than 0.6 μm and / or the ten-point average roughness (Rzjis) of the surface in contact with the resin layer is less than 3.0 μm.

[0220] This application is based on Japanese Patent Application No. 2023-170485, filed on September 29, 2023, the contents of which are incorporated herein by reference.

[0221] To illustrate the invention, it has been adequately and sufficiently described above with reference to the accompanying drawings and embodiments. However, it should be recognized that modifications and / or improvements to the above embodiments can be readily made by those skilled in the art. Therefore, any modified or improved embodiments implemented by those skilled in the art, as long as they do not depart from the scope of protection of the claims, are to be interpreted as being included within the scope of protection of the claims.

[0222] Industrial availability

[0223] According to the present invention, the following can be provided: a resin-coated metal foil capable of manufacturing a wiring board with high adhesion between the resin layer and the metal layer, excellent laser processability, and reduced signal transmission loss; a metal-clad laminate capable of manufacturing a wiring board with high adhesion between the insulating layer and the metal layer, excellent laser processability, and reduced signal transmission loss; and a wiring board with high adhesion between the insulating layer and the metal layer, excellent laser processability, and low signal transmission loss.

Claims

1. A resin-coated metal foil, characterized in that... include: A resin layer comprising a resin composition or a semi-cured product of the resin composition; as well as A metal layer is located on at least one side surface of the resin layer, wherein, The resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; and a styrene-based block copolymer; And curing agent, The metal layer has a copper foil in contact with the surface of the resin layer. The thickness of the copper foil is less than 5.0 μm. The arithmetic mean roughness (Ra) of the surface of the copper foil in contact with the resin layer is less than 0.6 μm, and the ten-point mean roughness (Rzjis) of the surface is less than 3.0 μm.

2. The resin-coated metal foil according to claim 1, characterized in that, The polyphenylene ether compound comprises a polyphenylene ether compound having at least one of the groups shown in formula (1) and formula (2) below within the molecule. In formula (1), p represents 0 to 10, Z represents arylene, and R1 to R3 each independently represent a hydrogen atom or an alkyl group. In formula (2), R4 represents a hydrogen atom or an alkyl group.

3. The resin-coated metal foil according to claim 1 or 2, characterized in that, The content of the polybutadiene compound is 5 to 38% by mass relative to the total amount of the polybutadiene compound, the polyphenylene ether compound, and the curing agent.

4. The resin-coated metal foil according to claim 1 or 2, characterized in that, The content of the polybutadiene compound is 3 to 25% by mass relative to the total amount of the polybutadiene compound, the polyphenylene ether compound, the styrene block copolymer and the curing agent.

5. The resin-coated metal foil according to claim 1 or 2, characterized in that, The curing agent contains an allyl compound.

6. The resin-coated metal foil according to claim 5, characterized in that, The allyl compound comprises an allyl isocyanurate compound having two or more allyl groups within the molecule.

7. The resin-coated metal foil according to claim 1 or 2, characterized in that, The ethylene oxide oxygen concentration in the polybutadiene compound is 1 to 10 by mass.

8. The resin-coated metal foil according to claim 1 or 2, characterized in that, The styrene-based block copolymer comprises at least one selected from the group consisting of methylstyrene (ethylene / butene) methylstyrene copolymer, methylstyrene (ethylene-ethylene / propylene) methylstyrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene (ethylene / butene) styrene copolymer, styrene (ethylene-ethylene / propylene) styrene copolymer, styrene-butadiene-styrene copolymer, styrene (butadiene / butene) styrene copolymer, styrene-isobutylene-styrene copolymer, and their hydrides.

9. The resin-coated metal foil according to claim 2, characterized in that, The polyphenylene ether compound comprises a polyphenylene ether compound having a group represented by formula (2) within the molecule.

10. A metal foil-coated laminate, characterized in that... include: An insulating layer comprising a cured resin composition; as well as A metal layer is located on at least one side surface of the insulating layer, wherein, The resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; and a styrene-based block copolymer; And curing agent, The metal layer has a copper foil in contact with the surface of the insulating layer. The thickness of the copper foil is less than 5.0 μm. The arithmetic mean roughness (Ra) of the surface of the copper foil in contact with the insulating layer is less than 0.6 μm, and the ten-point mean roughness (Rzjis) of the surface is less than 3.0 μm.

11. A wiring board, characterized in that... include: An insulating layer comprising a cured resin composition; as well as Wiring, located on at least one side surface of the insulating layer, wherein, The resin composition contains: a polybutadiene compound having an epoxy group in the molecule; a polyphenylene ether compound having carbon-carbon unsaturated bonds; and a styrene-based block copolymer; And curing agent, The wiring includes: a first copper conductor layer in contact with the surface of the insulating layer; and a second copper conductor layer laminated on the first copper conductor layer. The thickness of the first copper conductor layer is less than 5.0 μm. The arithmetic mean roughness (Ra) of the surface in the first copper conductor layer that contacts the insulating layer is less than 0.6 μm, and the ten-point mean roughness (Rzjis) of the surface is less than 3.0 μm.

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