Copper foil with resin layer, cured product, printed circuit board, and method for manufacturing the cured product.

Abstract

This invention provides a technology for copper foil with a resin layer that exhibits excellent adhesion to electroplated copper and superior reflow resistance. [Solution] The copper foil 10 with a resin layer has a copper foil 20 and a resin layer 30 laminated on the copper foil. The resin layer 30 contains polyphenylene ether. Preferably, the polyphenylene ether is a branched polyphenylene ether. Preferably, the surface roughness Rz of the surface of the copper foil on the resin layer side is 0.5 to 3.0 μm.

Description

Technical Field

[0001] The present invention relates to a copper foil with a resin layer, a cured product, a printed wiring board, and a method for producing a cured product.

Background Art

[0002] As an insulating material for forming electronic components such as printed wiring boards, a thermosetting resin composition containing an epoxy resin has been conventionally used. For example, Patent Document 1 discloses an epoxy resin composition containing an epoxy resin, an active ester compound and a triazine-containing phenolic resin as curing agents, a maleimide compound, and a phenoxy compound.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For a curable resin composition for forming an insulating layer of an electronic component, in addition to high adhesion to a plated conductor, it is also required to impart heat resistance in a reflow soldering process. In view of the above problems, the present invention aims to provide a technology related to a copper foil with a resin layer that is excellent in both adhesion to electrolytically plated copper and reflow resistance.

Means for Solving the Problems

[0005] One aspect of the present invention is a copper foil with a resin layer. The copper foil with a resin layer has a copper foil and a resin layer laminated on the copper foil, and the resin layer contains polyphenylene ether. In the copper foil with a resin layer according to the above embodiment, the polyphenylene ether may be a branched polyphenylene ether. The thickness of the copper foil may be 5 μm or less. The surface roughness Rz of the copper foil on the resin layer side may be 0.5 to 3.0 μm. The resin layer may contain a filler. The average particle size of the filler may be 0.1 to 1.0 μm. The average particle size of the filler may be smaller than the surface roughness Rz on the surface of the resin layer. The weight-average molecular weight of the polyphenylene ether may be between 20,000 and 60,000. The aforementioned resin layer may contain a cross-linking curing agent.

[0006] Another aspect of the present invention is a cured product. This cured product is obtained by curing the resin layer of the copper foil with the resin layer according to the above-described aspect. In the cured product according to the above-described embodiment, the peel strength obtained by the following measurement method may be 2.5 N / cm or more. (Method for measuring peel strength) Copper foil with a resin layer is laminated to both sides of a copper-clad laminate under the following conditions, and after heat curing at 200°C for 60 minutes, the copper layer thickness is reduced to 25 μm by electrolytic copper plating. The peel strength of the obtained sample is measured according to JIS C6481-1996, 5.7. Vacuum pressing conditions: Vacuuming for 30 seconds, pressurizing for 30 seconds Temperature: 90℃ Pressurization: 0.5 MPa

[0007] Yet another aspect of the present invention is a printed circuit board having a cured product according to the above-described aspect.

[0008] A further aspect of the present invention is a method for producing a cured product. The method for producing the cured product includes a first step of laminating a resin layer containing polyphenylene ether onto a copper foil to obtain a copper foil with a resin layer; a second step of laminating the resin layer of the copper foil with a resin layer onto a substrate; and a third step of curing the resin layer of the copper foil with a resin layer to obtain a cured product. In the method for manufacturing a cured product according to the above embodiment, the first step may be a step of pressing the resin layer and the copper foil together. The third step may be carried out in a non-oxygen atmosphere. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a technology relating to copper foil with a resin layer that exhibits excellent adhesion to electroplated copper and reflow resistance. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view of a copper foil with a resin layer according to an embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below. In this specification, unless otherwise specified, the notation "a~b" in the description of numerical ranges means a or greater and b or less.

[0012] (Copper foil with resin layer) Figure 1 is a schematic cross-sectional view of a copper foil 10 with a resin layer according to an embodiment. As shown in Figure 1, the copper foil 10 with a resin layer includes a copper foil 20 and a resin layer 30.

[0013] <Copper foil> The upper limit of the thickness of the copper foil 20 is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. By setting the upper limit of the thickness of the copper foil 20 to the above values, the copper foil 20 is more likely to act as a seed layer when electrolytic copper plating is applied to the copper foil 20. The lower limit of the thickness of the copper foil 20 is not particularly limited, but is preferably 0.5 μm or more, more preferably 0.6 μm or more, or even more preferably 0.7 μm or more. The copper foil 20 is sometimes called ultra-thin copper foil.

[0014] The method for forming the copper foil 20 is not particularly limited, and it can be formed by a wet film-forming method such as electroless copper plating or electrolytic copper plating, a dry film-forming method such as sputtering or chemical vapor deposition, or a combination thereof.

[0015] The surface roughness Rz on the surface of the copper foil 20 on the resin layer 30 side (hereinafter sometimes referred to as the surface roughness of the copper foil) is preferably 0.5 to 3.0 μm. According to this, the anchor effect generated between the resin layer 30 and the copper foil 20 described later can be sufficiently exerted, and thus the adhesion between the resin layer 30 and the copper foil 20 can be improved. The surface roughness of the copper foil 20 can be measured using a stylus profilometer.

[0016] A carrier film may be laminated on the surface of the copper foil 20 on the side opposite to the resin layer 30. Examples of the carrier film include copper foil, aluminum foil, stainless steel (SUS) foil, and resin films with a metal coating on the surface. Among these, it is preferable to use copper foil. The copper foil may be an electrolytic copper foil or a rolled copper foil. The thickness of the carrier film is usually 250 μm or less, preferably 9 to 200 μm. In addition, a release layer may be formed between the carrier film and the copper foil 20 as necessary.

[0017] <Resin layer> The resin layer 30 is laminated on one surface of the copper foil 10. The thickness of the resin layer 30 is preferably 10 to 100 μm, more preferably 20 to 90 μm, and even more preferably 30 to 80 μm. The resin layer 30 contains polyphenylene ether.

[0018] The resin layer 30 can be formed by applying and drying a resin composition on the copper foil. Hereinafter, the resin composition for forming the resin layer 30 will be described.

[0019] (Polyphenylene ether) The resin composition contains polyphenylene ether. The weight-average molecular weight of the polyphenylene ether is preferably 20,000 to 60,000. The weight-average molecular weight is the polystyrene-equivalent molecular weight, measured using GPC (gel permeation chromatography). It is preferable that the polyphenylene ether is a branched polyphenylene ether. By using a branched polyphenylene ether, the dispersibility of the filler described later can be improved in the resin layer 30.

[0020] Branched polyphenylene ethers are polyphenylene ethers produced from raw material phenols containing phenols having hydrogen atoms at the ortho and para positions. Because such phenols have hydrogen atoms at the ortho position, ether bonds can be formed not only at the ipso and para positions but also at the ortho position during oxidative polymerization with phenols. Therefore, polyphenylene ethers obtained using such phenols as raw material phenols can form a branched chain structure.

[0021] Such branched polyphenylene ethers exhibit excellent solubility in solvents, as well as superior compatibility and reactivity with other components in resin compositions.

[0022] The branched polyphenylene ether may be a conventionally known one containing functional groups having unsaturated carbon bonds, such as allyl groups or vinyl groups.

[0023] Examples of branched polyphenylene ethers containing unsaturated carbon bonds include the polyphenylene ether disclosed in International Publication No. 2020 / 017570.

[0024] The equivalent amount of functional groups containing unsaturated carbon bonds in polyphenylene ethers can be appropriately changed depending on the curability and intended use of the resin composition.

[0025] Unsaturated carbon bond-containing polyphenylene ether may be obtained by either of the following methods: (Method 1) a method of synthesizing polyphenylene ether using phenols containing functional groups having unsaturated carbon bonds as raw material phenols, or (Method 2) a method of synthesizing polyphenylene ether using phenols that do not contain functional groups having unsaturated carbon bonds as raw material phenols, and then modifying the obtained polyphenylene ether to introduce functional groups having unsaturated carbon bonds into the polyphenylene ether.

[0026] The unsaturated carbon bond-containing polyphenylene ether may be a mixture of two or more polyphenylene ethers of different types of raw material phenols.

[0027] (Inorganic filler) The resin composition and the resin layer 30 formed using the resin composition preferably contain an inorganic filler. Examples of inorganic fillers include nonmetallic fillers such as silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, talc, and organic bentonite, as well as metallic fillers such as copper, gold, silver, palladium, and silicone. Of these inorganic fillers, silica is preferably used. These inorganic fillers may be used individually or in combination of two or more.

[0028] The shape of the inorganic filler is not particularly limited and can be spherical, needle-shaped, plate-shaped, flake-shaped, hollow, irregularly shaped, hexagonal, cubic, or thin flake-shaped, but a spherical shape is preferred from the viewpoint of improving adhesion with the copper foil 20 mentioned above.

[0029] The average particle size of the inorganic filler is preferably 0.1 to 1.0 μm, more preferably 0.2 to 0.9 μm, and even more preferably 0.3 to 0.8 μm. By setting the average particle size of the inorganic filler within the above range, a portion of the inorganic filler can easily penetrate into the recessed areas on the surface of the copper foil 20 together with the polyphenylene ether, thereby enhancing the anchoring effect between the copper foil 20 and the resin layer 30, and consequently improving the adhesion between the copper foil 20 and the resin layer 30. The average particle size of the inorganic filler can be determined using a laser diffraction particle size distribution analyzer. In this disclosure, the average particle size is the median diameter D50 on a volume basis. Furthermore, the average particle size of the inorganic filler refers to the value measured as described above for the powdered material before the resin composition is prepared (pre-mixed and kneaded).

[0030] The average particle size of the inorganic filler is preferably smaller than the surface roughness Rz on the surface of the copper foil 20 facing the resin layer 30. For example, if the surface roughness Rz on the surface of the copper foil 20 facing the resin layer 30 is 1.0 μm, then the average particle size of the inorganic filler is preferably less than 1.0 μm. This allows a portion of the inorganic filler to penetrate more easily into the recessed areas of the copper foil 20 surface along with the polyphenylene ether, thereby further enhancing the anchoring effect between the copper foil 20 and the resin layer 30, and consequently further improving the adhesion between the copper foil 20 and the resin layer 30. As mentioned above, by using branched polyphenylene ether in the resin composition, the dispersibility of the inorganic filler is improved, and consequently, some of the inorganic filler, along with the branched polyphenylene ether, can more easily penetrate into the recessed areas on the surface of the copper foil 20, thereby further enhancing the adhesion between the copper foil 20 and the resin layer 30.

[0031] The lower limit of the amount of inorganic filler is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, when the polyphenylene ether solids in the resin layer 30 are 100 parts by mass. This allows for a reduction in the coefficient of linear expansion. The upper limit of the amount of inorganic filler is preferably 1000 parts by mass or less, more preferably 800 parts by mass or less, and even more preferably 600 parts by mass or less, when the polyphenylene ether solids in the resin layer 30 are 100 parts by mass. This allows for an increase in the toughness of the cured film obtained by curing the resin layer 30. In this specification, the solid content in the resin composition or resin layer 30 refers to the components excluding the organic solvent.

[0032] If the resin layer 30 contains a polyphenylene ether with functional groups including unsaturated carbon bonds, it is preferable to include a crosslinking curing agent. This can improve low dielectric properties and heat resistance. Examples of crosslinking curing agents include polyfunctional vinyl compounds such as divinylbenzene, divinylnaphthalene, and divinylbiphenyl; vinylbenzyl ether compounds synthesized from the reaction of phenol and vinylbenzyl chloride; styrene monomers such as diallyl phthalate and diallyl isophthalate; allyl ether compounds synthesized from the reaction of phenol and allyl chloride; and trialkenyl isocyanurates such as triallyl isocyanurate (hereinafter referred to as TAIC®) and triallyl cyanurate (hereinafter referred to as TAC). Among these, triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, and diallyl isophthalate are preferred because they have particularly good compatibility with polyphenylene ether. One type of crosslinking curing agent may be used, or two or more types may be used.

[0033] The resin layer 30 may contain an elastomer. The elastomer may be either a thermoplastic elastomer or a thermosetting elastomer. Examples of thermoplastic elastomers include olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers. Examples of thermosetting elastomers include diene-based synthetic rubbers such as polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber, nitrile rubber, and ethylene-propylene rubber; non-diene-based synthetic rubbers such as ethylene-propylene rubber, butyl rubber, acrylic rubber, polyurethane rubber, fluororubber, silicone rubber, and epichlorohydrin rubber; and natural rubber. These elastomers can be used individually or in combination of two or more types. The amount of elastomer added is preferably 5 to 60 parts by mass, and more preferably 10 to 55 parts by mass, when the polyphenylene ether solid content in the resin layer 30 is 100 parts by mass.

[0034] (Other ingredients) The resin composition for forming the resin layer may contain a peroxide as an initiator. Examples of peroxides include methyl ethyl ketone peroxide, methyl acetacetate peroxide, acetylacetone peroxide, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, and 2,5-di Examples include methyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-butene, acetyl peroxide, octanoyl peroxide, lauroyl peroxide, benzoyl peroxide, m-toluyl peroxide, diisopropyl peroxydicarbonate, t-butylene peroxybenzoate, di-t-butyl peroxide, t-butylperoxyisopropyl monocarbonate, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, etc. One peroxide may be used alone, or two or more may be used.

[0035] The peroxide content in the resin composition is preferably 0.1 to 10 parts by mass, or 1 to 5 parts by mass, per 100 parts by mass of polyphenylene ether in the resin composition. The above-mentioned peroxide may also be present in the resin layer 30 obtained from the resin composition.

[0036] The resin composition for forming the resin layer may contain an organic solvent. There are no particular restrictions on the organic solvent, but examples include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. More specifically, ketones such as methyl ethyl ketone, cyclohexanone, methyl butyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, isobutyl acetate, ethyl acetate, etc. Esters such as ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, 2-methoxypropanol, n-butanol, isobutyl alcohol, isopentyl alcohol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha; and other substances such as N,N-dimethylformamide (DMF), tetrachloroethylene, and turpentine oil. In addition, organic solvents such as Swazole 1000 and Swazole 1500 manufactured by Maruzen Petrochemical Co., Ltd., Solvent #100 and Solvent #150 manufactured by Sankyo Chemical Co., Ltd., Shellsol A100 and Shellsol A150 manufactured by Shell Chemicals Japan Co., Ltd., and Ipzole No. 100 and Ipzole No. 150 manufactured by Idemitsu Kosan Co., Ltd. may also be used. Organic solvents can be used individually or in combination of two or more types.

[0037] The resin composition for forming the resin layer may further, as needed, contain organic fillers such as silicone powder, fluorine powder, and nylon powder; conventionally known colorants such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, crystal violet, titanium dioxide, carbon black, and naphthalene black; conventionally known thickeners such as asbestos, olben, and benton; defoaming agents and / or leveling agents such as silicone-based, fluorine-based, and polymer-based agents; adhesion promoters such as thiazole-based, triazole-based, and silane coupling agents; and conventionally known additives such as titanate-based and aluminum-based agents.

[0038] As described above, with the copper foil 10 with a resin layer of this embodiment, the copper foil 20 acts as a seed layer, thereby improving adhesion to electroplated copper. Furthermore, by setting the surface roughness of the copper foil to 0.5 to 3.0 μm, the anchoring effect between the copper foil 20 and the resin layer 30 can be further enhanced. As a result, the adhesion between the copper foil 20 and the resin layer 30 is improved, which enhances reflow resistance and suppresses swelling of the copper foil 20 due to reflow. On the other hand, when directly forming a copper plating film on a resin layer without copper foil, the resin surface is usually roughened by desmear treatment before the copper plating film formation treatment is performed. A sufficient anchoring effect does not occur between the resin surface after desmear treatment and the copper plating film. Therefore, the adhesion between the resin layer and the copper plating film becomes insufficient.

[0039] (Method for producing copper foil with a resin layer) The copper foil with a resin layer according to the embodiment can be obtained by applying and drying the above-described resin composition onto the copper foil to form a resin layer. The resin composition for forming the resin layer may be used as a dry film or as a liquid. When used as a liquid, it may be a one-component or two-component or more-component composition.

[0040] (Dry film) The dry film according to the embodiment can be manufactured by applying the above-described resin composition onto a first film (e.g., a carrier film) and drying it to form a resin layer as a dry coating. A second film (e.g., a protective film) may be laminated onto the resin layer as needed.

[0041] Furthermore, when the resin composition is formed into a dry film, the amount of residual solvent in the resin layer is preferably 0.1 to 10.0% by mass. If the residual solvent is 10.0% by mass or less, bumping during thermal curing is suppressed, resulting in better surface flatness. Also, it is possible to prevent the resin from flowing due to excessively low melt viscosity, resulting in good flatness. If the residual solvent is 0.1% by mass or more, the fluidity during lamination is good, and consequently, the flatness and embedding properties are better.

[0042] The first film is a film that supports the resin layer of the dry film, and is coated with a resin composition when forming the resin layer. Examples of the first film include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamide-imide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, polystyrene films, and other thermoplastic resin films, as well as surface-treated paper. Among these, polyester films are particularly suitable from the viewpoint of heat resistance, mechanical strength, and handling. The thickness of the first film is not particularly limited, but is generally selected appropriately within the range of 10 to 150 μm depending on the application. The surface of the second film on which the resin layer is provided may be treated with a release agent. Furthermore, sputtering or copper foil may be formed on the surface of the first film on which the resin layer is provided.

[0043] The second film is provided on the side of the resin layer opposite the first film to the resin layer of the dry film, for the purpose of preventing dust and other particles from adhering to the surface of the resin layer and improving handling. As the second film, for example, a film made of the thermoplastic resin exemplified in the first film, and surface-treated paper can be used, but among these, polyester film, polyethylene film, and polypropylene film (biaxially oriented polypropylene film (OPP)) are preferred. The thickness of the second film is not particularly limited, but is generally in the range of 10 to 150 μm and can be appropriately selected depending on the application. The side of the second film on which the resin layer is provided may be treated with a release agent.

[0044] (cured product) The cured product according to the embodiment is obtained by curing the resin layer constituting the resin-coated copper foil. Alternatively, the cured product according to the embodiment can be obtained by curing the resin layer of the resin composition or dry film described above.

[0045] The method for curing the resin layer or resin composition is not particularly limited and can be cured by conventionally known methods, for example, by heating at 150 to 230°C.

[0046] In the cured product, it is preferable that the peel strength obtained by the following measurement method is 2.5 N / cm or higher. (Method for measuring peel strength) A copper foil with a resin layer is laminated to both main surfaces of a copper-clad laminate under the following conditions, and the resin layer is cured by heating at 200°C for 60 minutes to obtain a cured product. Subsequently, the thickness of the copper layer is reduced to 25 μm by electrolytic copper plating. The peel strength of the obtained sample is measured according to JIS C6481-1996. Vacuum pressing conditions: Vacuuming for 30 seconds, pressurizing for 30 seconds Temperature: 90℃ Pressurization: 0.5 MPa

[0047] (Printed circuit board) The printed circuit board according to the embodiment has the cured material described above. For example, when using a dry film with a three-layer structure in which a resin layer is sandwiched between the first and second films, a printed circuit board can be manufactured in the following manner: The second film is peeled off from the dry film, and an ultra-thin copper foil is laminated onto it. Next, the first film is peeled off from the dry film, heat-laminated onto the circuit board on which the circuit pattern is formed, and then heat-cured. Heat curing may be performed in an oven or by hot plate pressing. The curing atmosphere can be an oxygen-free atmosphere such as an air atmosphere or a nitrogen atmosphere. An oxygen-free atmosphere is preferred from the viewpoint of not inhibiting the radical reaction in the resin layer. Next, a printed circuit board can be manufactured by forming patterns and via holes at predetermined locations on the substrate where the circuit pattern is formed, using laser irradiation or a drill, thereby exposing the circuit wiring. In this process, if there are any remaining components (smear) on the circuit wiring within the patterns or via holes that could not be completely removed, a desmear treatment is performed.

[0048] Furthermore, when manufacturing printed circuit boards using copper foil with a resin layer, the resin layer may be laminated onto a circuit board with a circuit pattern formed on it, and the copper foil may be used as all or part of the wiring layer to form the circuit using a modified semi-additive process (MSAP) method to manufacture a build-up circuit board. Alternatively, a printed circuit board may be manufactured using a direct build-up-on-wafer method, in which the lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit. In addition, a coreless build-up method may be used in which resin layers and conductive layers are alternately laminated without using a core substrate.

[0049] (Method of manufacturing a cured product) The method for producing a cured product according to this embodiment includes the following steps 1 to 3. (Step 1) A resin layer containing polyphenylene ether is laminated onto copper foil to obtain copper foil with a resin layer. (Second step) The resin layer of the copper foil with the resin layer described above is laminated onto the substrate. (Third step) The resin layer of the copper foil with the resin layer described above is cured to obtain a cured product.

[0050] The first step is not particularly limited, but it may involve pressing the resin layer and the copper foil together. In this case, the pressing may be performed under vacuum and heating.

[0051] The second step is not particularly limited, but may include a step of pressing the resin-coated copper foil against the substrate. In this case, the pressing may be performed under vacuum and heating.

[0052] The third step is preferably carried out in a non-oxygen atmosphere. The curing of the resin layer in the third step involves a radical reaction. In this embodiment, the copper foil suppresses to some extent the penetration of oxygen, which inhibits the radical reaction, into the resin layer. Therefore, curing is possible even in an air atmosphere. However, by carrying out the third step in a non-oxygen atmosphere, the inhibition of the progression of the radical reaction is further suppressed, and the curing of the resin layer can be accelerated even more rapidly. Non-oxygen atmospheres include inert gas atmospheres such as nitrogen and argon. Of these, it is more preferable to perform the third step (curing step) under a nitrogen atmosphere from the viewpoint of accelerating the curing of the resin layer and reducing production costs.

[0053] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted. [Examples]

[0054] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0055] <Composition ingredients> The details of each ingredient (raw material) listed in Table 1 are as follows. Polyphenylene ether: Branched polyphenylene ether obtained by the following synthesis procedure. • Synthesis of branched polyphenylene ethers In a 500 mL separable flask, 19.8 g of 2,6-dimethylphenol and 2.42 g of 2-allylphenol were added, and the resulting mixture was dissolved in 261 g of toluene. Further preparations were made to contain 0.18 wt% di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 0.16 wt% tetramethylethylenediamine (TMEDA). The reaction mixture was stirred at a rate of 200 rpm using a four-bladed paddle while blowing dry air at a flow rate of 75 mL / min, and the mixture was reacted at 40°C for a predetermined time to obtain a reaction solution containing polyphenylene ether. After stopping the heating of the reaction solution and the blowing of dry air, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) was removed by filtration, reprecipitation was performed with a mixture of 1,200 mL of methanol, 4.0 mL of concentrated hydrochloric acid, and 7.0 mL of H2O2, and the solution was removed by vacuum filtration. After washing with methanol, the solution was dried at 80°C for 24 hours to obtain branched polyphenylene ether. The number-average molecular weight of the obtained branched polyphenylene ether was 13,000 and the weight-average molecular weight was 45,000. Crosslinking agent 1: Triallyl isocyanurate (manufactured by Mitsubishi Chemical Corporation, TAIC) Crosslinking agent 2: Diallyl phthalate (manufactured by Osaka Soda Co., Ltd., DAP) Elastomer: Manufactured by Asahi Kasei Corporation, ToughTec H1051 Inorganic filler: Spherical silica, manufactured by Admatex Co., Ltd., SC20500-HNF, average particle size 0.5 μm Initiator: Perbutyl P40, manufactured by NOF Corporation. Copper foil 1: Carrier-mounted copper foil, manufactured by Mitsui Mining & Smelting Co., Ltd., MT18Ex, copper foil thickness 3 μm, surface roughness (roughness) Rz 2.0 μm Copper foil 2: Carrier-mounted copper foil, manufactured by Mitsui Mining & Smelting Co., Ltd., MT18FL, copper foil thickness 3 μm, surface roughness (roughness) Rz 1.3 μm

[0056] <Preparation of resin composition> The polyphenylene ether and elastomer in the amounts shown in Table 1 were mixed with a solvent (cyclohexanone) and stirred at 60°C for 60 minutes until completely dissolved. The remaining components were added to the resulting PPE resin solution and mixed and stirred to prepare the resin compositions used in Examples 1-8 and Comparative Examples 1-2.

[0057] (Measurement of relative permittivity and dielectric loss tangent) • Preparation of test samples Using a film applicator, each resin composition was applied to the glossy surface of copper foil (F2-WS, manufactured by Furukawa Electric Co., Ltd., 18 μm thick). After drying in a hot air circulating drying oven at 90°C for 5 minutes, the mixture was cured at 200°C for 60 minutes. The copper foil was then peeled off to produce a cured film with a thickness of approximately 40 μm. The obtained cured film was cut into 80 mm long and 45 mm wide pieces and used as test samples. The relative permittivity Dk and dielectric loss tangent Df were measured using the SPDR (Split Post Dielectric Resonator) method. The measuring equipment used was a Keysight Technologies LLC E5071C vector network analyzer, an SPDR resonator, and a calculation program from QWED. The measurement conditions were as follows: Frequency: 10GHz Measurement temperature: 25℃

[0058] (Peel strength) • Fabrication of CZ-treated substrates A roughening treatment was performed on both sides of a substrate (copper-clad laminate, manufactured by Mitsubishi Gas Chemical Company, Inc., CCL-HL832NX, TYPE A Series, 0.4 mm thick) using a roughening agent (manufactured by MEC Corporation, CZ8100) under conditions that resulted in an etching amount of approximately 1 μm.

[0059] • Preparation of test samples 1 (Examples 1-6) The resin compositions of Examples 1 to 6, prepared in <Preparation of Resin Compositions>, were applied to PET film (Toray Industries, Inc., Lumirror 38R80, 38 μm thick) using a bar coater so that the resin layer thickness after drying was 35 μm. Then, they were dried in a hot air circulating drying oven at a temperature of 90°C for 5 minutes. Next, an OPP film (manufactured by Futamura Chemical Co., Ltd., FSA-010M) was attached to the side of the resin layer opposite to the PET film using a roll laminator set to a temperature of 50°C, thereby creating a dry film with a three-layer structure of PET film / resin layer / OPP film. After peeling the OPP film from the dry film mentioned above, the exposed resin layer was laminated using a vacuum press so that it was in contact with the copper foil surface of the carrier-attached copper foil, thereby producing a copper foil with a resin layer. The lamination conditions for the carrier-attached copper foil were as follows. Equipment: Laminator MVLP-500 manufactured by Meiki Seisakusho Co., Ltd. Vacuum pressing conditions: Vacuuming for 30 seconds, pressurizing for 30 seconds Temperature: 140℃ Pressurization: 0.5 MPa Next, after peeling the carrier film from the copper foil with the resin layer, the copper foil with the resin layer was laminated to both sides of the CZ-treated substrate obtained in the procedure described above, so that the resin layer side of the copper foil was in contact with each other, thereby obtaining a test specimen with a five-layer structure of copper foil / resin layer / CZ substrate / resin layer / copper foil. The lamination conditions for the CZ substrate were as follows. Equipment: Laminator MVLP-500 manufactured by Meiki Seisakusho Co., Ltd. Vacuum pressing conditions: Vacuuming for 30 seconds, pressurizing for 30 seconds Temperature: 90℃ Pressurization: 0.5 MPa Next, the obtained test specimens were cured in an inert oven (under a nitrogen atmosphere, indicated as "nitrogen" in Table 1 as the curing atmosphere) or a hot air circulating dry drying oven (under an air atmosphere, indicated as "air" in Table 1 as the curing atmosphere) at 200°C for 60 minutes. After curing, the carrier was removed from the carrier-attached copper foil, and the copper layer, including the copper foil, was thickened to approximately 25 μm by electrolytic copper plating. Details of the electrolytic copper plating are as follows. • Electrolytic copper plating The sample was immersed in a cleaning acid (Atotec Japan Co., Ltd., acidic cleaner) at 46°C for 5 minutes, then immersed in a 10% sulfuric acid aqueous solution at 25°C for 1 minute, and finally immersed in copper sulfate plating solution at 25°C for 60 minutes, resulting in an electrolytic density of 2 A / m². 2Electrolytic copper plating was performed under the specified conditions. Finally, as an annealing treatment, heat treatment was carried out at 190°C for 60 minutes in a hot air circulating dry drying oven. Test samples were obtained using the above manufacturing method.

[0060] • Preparation of test samples 2 (Examples 7, 8) A test sample was obtained under the same preparation conditions as for Peel Test Sample Preparation 1, except that a resin layer was applied to the copper foil surface of the carrier-attached copper foil prepared in Examples 7 and 8 using a film applicator, and then dried in a hot air circulating drying oven at 90°C for 5 minutes to obtain a copper foil with a resin layer thickness of approximately 30 μm.

[0061] • Preparation of test samples 3 (Comparative Examples 1 and 2) Without laminating the carrier-attached copper foil to the resin layer, the OPP film was peeled off the prepared dry film and laminated to both sides of the CZ-treated substrate under the following conditions so that the resin layer of the dry film was in contact with each other. A test specimen with a five-layer structure of first film / resin layer / CZ substrate / resin layer / first film was obtained, and after curing, a test sample was obtained under the same preparation conditions as for peel test sample preparation 1, except that electrolytic copper plating was directly applied to the resin layer. Equipment: Laminator MVLP-500 manufactured by Meiki Seisakusho Co., Ltd. Vacuum pressing conditions: Vacuuming for 30 seconds, pressurizing for 30 seconds Temperature: 90℃ Pressurization: 0.5 MPa

[0062] The peel strength of each test sample prepared was measured according to JIS C6481-1996, 5.7, and evaluated according to the peel strength evaluation criteria below. <Peel Strength Evaluation Criteria> A: 5N / cm or more B: 2.5 N / cm or more, less than 5 N / cm C: Less than 2.5 N / cm or not measurable (A and B are considered pass, C is considered fail)

[0063] (Reflow resistance) Each test sample prepared was subjected to a reflow test under the following conditions and evaluated according to the reflow resistance evaluation criteria below. • Reflow test conditions Reflow oven: N2 reflow oven NIS-20-82C, manufactured by Aitech Tectron Co., Ltd. Nitrogen generator: Manufactured by Taiyo Nippon Sanso Corporation, Nitrogen Generator (PSA) RA-15 Reflow temperature and number of passes: 265°C x 3 passes <Reflow Resistance Evaluation Criteria> A: No swelling C: Bulging (A is a pass, C is a fail)

[0064] [Table 1]

[0065] As shown in Table 1, both peel strength and reflow resistance were satisfactory in Examples 1 to 8. In particular, the peel strength in Examples 1 to 6 was 5 N / cm or higher.

[0066] Furthermore, comparisons between Examples 1 and 2, Examples 3 and 4, Examples 5 and 6, and Examples 7 and 8 confirmed that using a nitrogen atmosphere during curing resulted in higher peel strength compared to using an air atmosphere. [Explanation of symbols]

[0067] 10 copper foils with resin layer, 20 copper foils, 30 resin layer

Claims

1. It comprises a copper foil and a resin layer laminated on the copper foil, The resin layer contains polyphenylene ether. A copper foil with a resin layer, characterized by the above features.

2. The copper foil with a resin layer according to claim 1, wherein the polyphenylene ether is a branched polyphenylene ether.

3. The copper foil with a resin layer according to claim 1 or 2, wherein the thickness of the copper foil is 5 μm or less.

4. The copper foil with a resin layer according to claim 1 or 2, wherein the surface roughness Rz on the surface of the copper foil on the resin layer side is 0.5 to 3.0 μm.

5. The copper foil with a resin layer according to claim 1 or 2, wherein the resin layer contains an inorganic filler.

6. The copper foil with a resin layer according to claim 5, wherein the average particle size of the inorganic filler is 0.1 to 1.0 μm.

7. The copper foil with a resin layer according to claim 5, wherein the average particle size of the inorganic filler is smaller than the surface roughness Rz on the surface of the resin layer.

8. The copper foil with a resin layer according to claim 1 or 2, wherein the weight-average molecular weight of the polyphenylene ether is 20,000 to 60,000.

9. The resin layer comprises a crosslinking curing agent, as described in claim 1 or 2, for copper foil with a resin layer.

10. A cured product obtained by curing the resin layer of the copper foil with a resin layer according to claim 1 or 2.

11. The cured product according to claim 10, wherein the peel strength obtained by the measurement method described below is 2.5 N / cm or more. (Method for measuring peel strength) Copper foil with a resin layer is laminated to both sides of a copper-clad laminate under the following conditions, and after heat curing, the thickness of the copper layer is reduced to 25 μm by electrolytic copper plating. The peel strength of the obtained sample is measured according to JIS C6481-1996. Vacuum pressing conditions: Vacuuming for 30 seconds, pressurizing for 30 seconds Temperature: 90℃ Pressurization: 0.5 MPa

12. A printed circuit board having the cured product according to claim 10.

13. The first step involves laminating a resin layer containing polyphenylene ether onto copper foil to obtain a copper foil with a resin layer, A second step involves laminating the resin layer of the copper foil with the resin layer onto a substrate, A third step involves curing the resin layer of the copper foil with the resin layer to obtain a cured product, A method for producing a cured product, characterized by containing the following:

14. The method for manufacturing a cured product according to claim 14, wherein the first step is a step of pressing the resin layer and the copper foil together.

15. The method for producing a cured product according to claim 14, wherein the third step is carried out in a non-oxygen atmosphere.

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