Surface-treated copper foil, copper-clad laminates, and printed circuit boards

Abstract

Provided is a surface-treated copper foil that has a copper foil and a heteroaromatic compound layer formed on at least one surface of the copper foil. The heteroaromatic compound layer contains a heteroaromatic compound having a heterocyclic ring containing a nitrogen atom as a hetero atom and having Sp of 0.10-1.00 μm.

Description

[Technical Field]

[0001] This disclosure relates to surface-treated copper foil, copper-clad laminates, and printed circuit boards. [Background technology]

[0002] Copper-clad laminates are widely used in various applications, including flexible printed circuit boards. These flexible printed circuit boards are manufactured by etching the copper foil of the copper-clad laminate to form a conductor pattern (also called a "wiring pattern"), and then soldering electronic components onto the conductor pattern.

[0003] In recent years, with the increasing speed and capacity of communications in electronic devices such as personal computers and mobile terminals, electrical signals have become more high-frequency, creating a demand for flexible printed circuit boards that can handle this. In particular, as the frequency of electrical signals increases, the signal power loss (attenuation) becomes greater, making it easier for data to become unreadable, so there is a need to reduce signal power loss.

[0004] The causes of signal power loss (transmission loss) in electronic circuits can be broadly divided into two categories. The first is conductor loss, that is, loss due to copper foil, and the second is dielectric loss, that is, loss due to the resin substrate. Conductor loss occurs in the high-frequency range due to the skin effect, where current flows along the surface of the conductor. Therefore, if the copper foil surface is rough, the current will flow along a complex path. Consequently, to reduce conductor loss in high-frequency signals, it is desirable to reduce the surface roughness of the copper foil. Hereafter, in this specification, when "transmission loss" and "conductor loss" are simply referred to, they mainly mean "transmission loss of high-frequency signals" and "conductor loss of high-frequency signals."

[0005] Since dielectric loss depends on the type of resin substrate, it is desirable to use a resin substrate made from a low-dielectric material (e.g., liquid crystal polymer, low-dielectric polyimide) in circuit boards through which high-frequency signals flow. To ensure adhesion between copper foil and resin substrate, it has been proposed to form a surface treatment layer containing roughening particles on at least one surface of the copper foil. This aims to improve adhesion through an anchoring effect where the roughening particles bite into the resin substrate. For example, Patent Document 1 proposes a method in which a roughening treatment layer formed from roughening particles is provided on copper foil, and a rust-preventive treatment layer is formed on top of it. The rust-preventive treatment layer consists of a nickel-cobalt alloy plating layer, a zinc plating layer, a chromate treatment layer, and a silane coupling treatment layer. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-112009 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The surface-treated copper foil described in Patent Document 1 has the problem of increased manufacturing time and cost because it requires the formation of many layers on the copper foil. In addition, with some resin substrates, especially low-dielectric materials, sufficient adhesion cannot be ensured by the anchoring effect of roughened particles.

[0008] Embodiments of the present invention have been made to solve the above-mentioned problems, and in one aspect, aim to provide a surface-treated copper foil that can improve adhesion to resin substrates, particularly resin substrates suitable for high-frequency applications, while reducing the time and cost required for manufacturing. Furthermore, another aspect of the embodiments of the present invention aims to provide a copper-clad laminate with excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a surface-treated copper foil, while reducing the time and cost required for manufacturing. Furthermore, embodiments of the present invention also aim to provide a printed wiring board with excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a circuit pattern, while reducing the time and cost required for manufacturing. [Means for solving the problem]

[0009] The inventors conducted intensive research to solve the above problems and, surprisingly, discovered that certain heteroaromatic compounds have the function of improving adhesion to resin substrates. Based on this discovery, they found that the above problems can be solved by forming a heteroaromatic compound layer containing a specific heteroaromatic compound on at least one surface of a copper foil and controlling the Sp of that surface to a predetermined range, thus completing the embodiments of the present invention.

[0010] In other words, an embodiment of the present invention has, in one aspect, a copper foil and a heteroaromatic compound layer formed on at least one surface of the copper foil, wherein the heteroaromatic compound layer contains a heteroaromatic compound having a heterocycle containing a nitrogen atom as a heteroatom, and having an Sp of 0.10 to 1.00 μm. Furthermore, Vmp is 0.001~0.010μm 3 / μm 2 That is, Regarding surface-treated copper foil. Furthermore, embodiments of the present invention relate to a copper-clad laminate comprising the surface-treated copper foil and a resin substrate bonded to the heteroaromatic compound layer of the surface-treated copper foil. Furthermore, in another aspect, embodiments of the present invention relate to the surface-treated copper foil of the copper-clad laminate. Consists of This relates to a printed circuit board equipped with a circuit pattern. [Effects of the Invention]

[0011] According to embodiments of the present invention, in one respect, it is possible to provide a surface-treated copper foil that can improve adhesion to resin substrates, particularly resin substrates suitable for high-frequency applications, while reducing the time and cost required for manufacturing. Furthermore, according to embodiments of the present invention, in another aspect, it is possible to provide a copper-clad laminate with excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a surface-treated copper foil, while reducing the time and cost required for manufacturing. Further, according to an embodiment of the present invention, in another aspect, it is possible to provide a printed wiring board having excellent adhesion between a resin base material, particularly a resin base material suitable for high-frequency applications and a circuit pattern, while suppressing the time and cost required for manufacturing.

Brief Description of Drawings

[0012] [Figure 1] An example of the load curve of the complex aromatic compound layer.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, preferred embodiments of the present invention will be specifically described. However, the present invention should not be construed as being limited thereto, and various changes and improvements can be made based on the knowledge of those skilled in the art without departing from the gist of the present invention. A plurality of components disclosed in the following embodiments can form various inventions by appropriate combination. For example, some components may be deleted from all the components shown in the following embodiments, or components of different embodiments may be appropriately combined.

[0014] The surface-treated copper foil according to an embodiment of the present invention has a copper foil and a complex aromatic compound layer formed on at least one surface of the copper foil. The complex aromatic compound layer may be formed only on one surface of the copper foil or on both surfaces of the copper foil. When the complex aromatic compound layer is formed on both surfaces of the copper foil, the types of the complex aromatic compound layer may be the same or different.

[0015] The copper foil is not particularly limited and may be either an electrolytic copper foil or a rolled copper foil. High-purity copper such as tough pitch copper (JIS H3100 alloy number C1100), commonly used as circuit patterns in printed circuit boards, and oxygen-free copper (JIS H3100 alloy number C1020 or JIS H3510 alloy number C1011) can be used as the material for the copper foil. In addition, copper alloys such as Sn-containing copper, Ag-containing copper, copper alloys with added Cr, Zr, or Mg, and Corson-type copper alloys with added Ni and Si can also be used. In this specification, "copper foil" is a concept that includes copper alloy foils.

[0016] The thickness of the copper foil is not particularly limited, but can be, for example, 1 to 1000 μm, 1 to 500 μm, 1 to 300 μm, 3 to 100 μm, 5 to 70 μm, 6 to 35 μm, or 9 to 18 μm.

[0017] The heteroaromatic compound layer contains heteroaromatic compounds having a heterocycle containing a nitrogen atom as a heteroatom. The number of members in a complex ring is not particularly limited, but is, for example, 3 to 9, preferably 4 to 6, and more preferably 5. The heteroatoms in a heterocycle may consist solely of nitrogen atoms, or they may consist of nitrogen atoms and other atoms (for example, oxygen atoms, sulfur atoms, etc.). The number of heteroatoms in the heterocycle is determined according to the number of ring members, but is, for example, 1 to 5, preferably 1 to 4, and more preferably 1 to 3. A complex ring can be either a saturated ring or an unsaturated ring. Here, an unsaturated ring is a concept that includes a partially unsaturated ring.

[0018] Specific examples of heterocycles include allidine (an unsaturated three-membered ring containing one nitrogen atom), diazirine (an unsaturated three-membered ring containing two nitrogen atoms), azeto (an unsaturated four-membered ring containing one nitrogen atom), diazeto (an unsaturated four-membered ring containing two nitrogen atoms), pyrrole (an unsaturated five-membered ring containing one nitrogen atom), pyrrolidine (a saturated five-membered ring containing one nitrogen atom), imidazole and pyrazole (an unsaturated five-membered ring containing two nitrogen atoms), imidazolidine and pyrazolidine (two nitrogen atoms). (Saturated 5-membered ring containing an elementary atom), oxazole and isoxazole (unsaturated 5-membered ring containing one nitrogen atom and one oxygen atom), oxazolidine and isoxazolidine (saturated 5-membered ring containing one nitrogen atom and one oxygen atom), thiazole and isothiazole (unsaturated 5-membered ring containing one nitrogen atom and one sulfur atom), thiazolidin and isothiazolidine (saturated 5-membered ring containing one nitrogen atom and one oxygen atom), 1,2,3-triazole and 1,2,Triazoles such as 4-triazole (unsaturated 5-membered ring containing 3 nitrogen atoms), tetrazole (unsaturated 5-membered ring containing 4 nitrogen atoms), pentazole (unsaturated 5-membered ring containing 5 nitrogen atoms), furazanes and oxadiazoles (unsaturated 5-membered ring containing 2 nitrogen atoms and 1 oxygen atom), thiadiazoles (unsaturated 5-membered ring containing 2 nitrogen atoms and 1 sulfur atom), dixazoles (unsaturated 5-membered ring containing 1 nitrogen atom and 2 oxygen atoms), dithiazoles (unsaturated 5-membered ring containing 1 nitrogen atom and 2 sulfur atoms), oxatetrazole (unsaturated 5-membered ring containing 4 nitrogen atoms and 1 oxygen atom), thiatetrazole (unsaturated 5-membered ring containing 4 nitrogen atoms and 1 sulfur atom), pyridine (unsaturated 6-membered ring containing 1 nitrogen atom), piperidine (saturated 6-membered ring containing 1 nitrogen atom), diazines (unsaturated 6-membered ring containing 2 nitrogen atoms), piperazines (saturated 6-membered ring containing 2 nitrogen atoms) (Ring), oxazine (unsaturated 6-membered ring containing 1 nitrogen atom and 1 oxygen atom), morpholine (saturated 6-membered ring containing 1 nitrogen atom and 1 oxygen atom), thiaidine (unsaturated 6-membered ring containing 1 nitrogen atom and 1 sulfur atom), thiomorpholine (saturated 6-membered ring containing 1 nitrogen atom and 1 sulfur atom), triazine (unsaturated 6-membered ring containing 3 nitrogen atoms), tetrazine (unsaturated 6-membered ring containing 4 nitrogen atoms), pentazin (containing 5 nitrogen atoms) Examples include unsaturated 6-membered rings, azepines (unsaturated 7-membered rings containing 1 nitrogen atom), azepanes (saturated 7-membered rings containing 1 nitrogen atom), diazepines (unsaturated 7-membered rings containing 2 nitrogen atoms), diazepanes (saturated 7-membered rings containing 2 nitrogen atoms), azosine (unsaturated 8-membered rings containing 1 nitrogen atom), azocanes (saturated 8-membered rings containing 1 nitrogen atom), azonines (unsaturated 9-membered rings containing 1 nitrogen atom), and azonanes (saturated 9-membered rings containing 1 nitrogen atom). Among these, from the viewpoint of stably improving adhesion to resin substrates, the heterocycle is preferably a 5-membered ring containing 1 to 3 nitrogen atoms, and more preferably an unsaturated 5-membered ring containing 1 to 3 nitrogen atoms (pyrrole, imidazole, pyrazole, oxazole, isoxazole, thiazole, isothiazole, triazole).

[0019] Heteroaromatic compounds having heterocycles can be fused ring compounds of a benzene ring and a heterocycle, fused ring compounds of two or more heterocycles, or monocyclic compounds of a heterocycle. The fused ring compounds of a benzene ring and a heterocycle are not particularly limited, but examples include indole, indazole, isoindole, benzimidazole, benzotriazole, quinoline, isoquinoline, quinazoline, quinoxaline, cinnoline, acridine, and carbazole. The compound formed by the fusion of two or more heterocyclic rings is not particularly limited, but examples include triazolopyridine, purine, and pteridine. The heterocyclic monocyclic compounds are not particularly limited, and examples of heterocyclic compounds include those exemplified above. The above-mentioned fused ring compounds and monocyclic compounds may have substituents. The substituents are not particularly limited. Examples of substituents include alkyl groups such as methyl and ethyl groups, vinyl groups, and nitro groups.

[0020] The heteroaromatic compound layer is a layer containing the above-mentioned heteroaromatic compounds. The heteroaromatic compound layer may consist of a single type or two or more different types. Furthermore, the heteroaromatic compound layer may contain components other than heteroaromatic compounds, to the extent that they do not hinder the effects according to the embodiments of the present invention. Examples of such components include solvents and additives that are mixed in when forming the heteroaromatic compound layer.

[0021] The heteroaromatic compound layer has lower peaks (protrusions) compared to conventional surface treatment layers that include a roughening treatment layer. In other words, the heteroaromatic compound layer has high smoothness. This is because, while conventional surface treatment layers that include a roughening treatment layer improve adhesion between the surface treatment layer and the resin substrate through an anchoring effect, the heteroaromatic compound layer does not aim to improve adhesion through an anchoring effect. That is, the heteroaromatic compound layer improves adhesion between the surface-treated copper foil and the resin substrate through the adhesive properties of the heteroaromatic compound, so even if the peaks on the surface are low, the desired improvement in adhesion can be obtained. Furthermore, because the heteroaromatic compound layer has higher surface smoothness compared to conventional surface treatment layers that include a roughening treatment layer, transmission loss due to the skin effect can be reduced.

[0022] One indicator of surface smoothness can be used to represent Sp (maximum peak height). Sp represents the maximum height from the mean plane of the surface. Sp is a peak height parameter defined in ISO 25178-2:2012, and a surface with a small Sp can be said to be a smooth surface. The Sp of the heteroaromatic compound layer is 0.10 to 1.00 μm. Because the heteroaromatic compound layer with Sp controlled within this range is smooth, it is possible to improve the adhesion between the surface-treated copper foil and the resin substrate due to the adhesive properties of the heteroaromatic compound. Furthermore, it is possible to reduce transmission loss. From the viewpoint of stably obtaining the above effects, the Sp of the heteroaromatic compound layer is preferably 0.10 to 0.85 μm, more preferably 0.10 to 0.78 μm, and even more preferably 0.30 to 0.78 μm. Furthermore, the Sp of the heteroaromatic compound layer can be measured in accordance with ISO 25178-2:2012.

[0023] Compared to conventional surface treatment layers that include a roughening treatment layer, the heteroaromatic compound layer has fewer surface peaks because it does not contain roughening particles. As an index to represent the proportion of surface peaks in such a heteroaromatic compound layer, Vmp (physical volume of peaks) can be used. Vmp is a functional (volume) parameter specified in ISO 25178-2:2012 and represents the physical volume of the peaks in the heteroaromatic compound layer. Vmp can be identified by measuring surface roughness in accordance with ISO 25178-2:2012 and analyzing the load curve calculated from the measurement data. To explain the load curve, I will first explain the load area ratio. The load area ratio is the ratio obtained by dividing the area corresponding to the cross-section of a three-dimensional object to be measured, when cut at a certain height plane, by the area of ​​the measurement field of view. In this disclosure, the object to be measured is assumed to be copper foil or a complex aromatic compound layer of surface-treated copper foil. The load curve is a curve that represents the load area ratio at each height. The area around 0% load area ratio represents the height of the highest part of the object to be measured, and the area around 100% load area ratio represents the height of the lowest part of the object to be measured.

[0024] Next, Figure 1 shows an example of a load curve. The load curve can be used to represent the physical volume and spatial volume of the heteroaromatic compound layer. The physical volume corresponds to the volume of the physical object occupied within the measurement field of view, and the spatial volume corresponds to the volume occupied by the space between the physical parts within the measurement field of view. In the load curve, the load area ratio is divided into valleys, cores, and peaks, with boundaries at 10% and 80%. Referring to Figure 1, and corresponding to the heteroaromatic compound layer according to the embodiment of the present invention, Vvv represents the spatial volume in the valley of the heteroaromatic compound layer, Vvc represents the spatial volume in the core of the heteroaromatic compound layer, Vmp represents the physical volume in the peak of the heteroaromatic compound layer, and Vmc represents the physical volume in the core of the heteroaromatic compound layer. The peaks are the tallest parts of the object being measured. The valleys are the shortest parts of the object being measured. The core is the part of the object being measured that is not the peaks or valleys, i.e., the part with a height close to the average.

[0025] The physical volume Vmp in the peak portion is the physical volume in the peak portion, i.e., the taller part of the object being measured, and represents the physical volume in the particularly tall portion within the heteroaromatic compound layer. The Vmp of the heteroaromatic compound layer is preferably 0.001 to 0.010 μm. 3 / μm 2 More preferably 0.001 to 0.006 μm 3 / μm 2 Therefore, the fact that Vmp, which is the volume of the physical part in the particularly high-height portion, falls within this range means that the heteroaromatic compound layer is smooth. By controlling Vmp within this range, it is possible to obtain an improved adhesion effect between the surface-treated copper foil and the resin substrate due to the adhesive properties of the heteroaromatic compound. Furthermore, it is also possible to obtain an effect of reducing transmission loss. Furthermore, the Vmp of the heteroaromatic compound layer can be measured in accordance with ISO 25178-2:2012.

[0026] The heteroaromatic compound layer is smoother than conventional surface treatment layers that include a roughening treatment layer, because it does not contain roughening particles. Such a heteroaromatic compound layer also has shallower surface grooves. Sv (maximum groove depth) can be used as an index to represent the depth of the grooves. Sv is a height parameter defined in ISO 25178-2:2012 and represents the minimum height of the heteroaromatic compound layer from the mean plane of the surface. The Sv of the heteroaromatic compound layer is preferably 1.50 μm or less, more preferably 0.10 to 1.25 μm, and even more preferably 0.50 to 1.20 μm. By controlling Sv within this range, it is possible to improve the adhesion between the surface-treated copper foil and the resin substrate due to the adhesive properties of the heteroaromatic compound. Furthermore, it is also possible to reduce transmission loss. Furthermore, the Sv of the heteroaromatic compound layer can be measured in accordance with ISO 25178-2:2012.

[0027] In the surface-treated copper foil according to the embodiment of the present invention, it is preferable that the copper foil and the heteroaromatic compound layer are in direct contact. However, a functional layer may be provided between the copper foil and the heteroaromatic compound layer, to the extent that it does not hinder the effects of the embodiment of the present invention. Examples of functional layers include a heat-resistant treatment layer, a rust-preventive treatment layer, and a chromate treatment layer.

[0028] The method for manufacturing the surface-treated copper foil according to the embodiment of the present invention is not particularly limited, but for example, it can be manufactured by the following method. First, copper foil is manufactured by a method known in the art. For example, when using electrolytic copper foil, it can generally be manufactured by electrolytically elastorating copper from a copper sulfate plating bath onto a titanium or stainless steel drum. Alternatively, when using rolled copper foil, it can generally be manufactured by sequentially performing homogenization annealing, hot rolling, cold rolling, and annealing on a copper ingot. Or, since copper foil is commercially available, commercially available products may be used. However, when using commercially available copper foil, rust inhibitors or oils may be attached to the surface of the copper foil, so the copper foil should be degreased and pickled. This is because if various surface treatment layers are formed on the surface of the copper foil, it becomes difficult to form a heteroaromatic compound layer on the surface of the copper foil.

[0029] Next, a coating solution of the heteroaromatic compound is prepared. The coating solution may contain solvents such as water and additives. The concentration of the heteroaromatic compound in the coating solution is not particularly limited and can be adjusted according to the type of heteroaromatic compound used, but for example, it is 0.1 to 10% by mass. Next, a heteroaromatic compound coating solution is applied to the surface of the copper foil and dried to form a heteroaromatic compound layer. The coating method is not particularly limited, and various methods such as immersion, spray coating, curtain flow coating, roll coating, brush coating, and roller brush coating can be used. The drying method is also not particularly limited, and room temperature drying or heat drying can be selected depending on the type of solvent used. The coating and drying of the heteroaromatic compound solution only needs to be done once, but it may be done multiple times to form a heteroaromatic compound layer of the desired thickness. Furthermore, the Sp, Vmp, and Sv of the heteroaromatic compound layer can be controlled primarily by adjusting the surface roughness of the copper foil on which the heteroaromatic compound layer is formed. The roughness of the copper foil can be controlled by adjusting the manufacturing conditions of the copper foil, the degreasing conditions and pickling conditions before the formation of the heteroaromatic compound layer, etc.

[0030] The surface-treated copper foil according to the embodiment of the present invention has a heteroaromatic compound layer containing a specific heteroaromatic compound, and the Sp of the heteroaromatic compound layer is controlled to 0.10 to 1.00 μm. Therefore, it is possible to reduce the time and cost required for manufacturing while improving adhesion to resin substrates, especially resin substrates suitable for high-frequency applications.

[0031] A copper-clad laminate according to an embodiment of the present invention comprises the above-mentioned surface-treated copper foil and a resin substrate bonded to the complex aromatic compound layer of the surface-treated copper foil. This copper-clad laminate can be manufactured by bonding a resin substrate to the complex aromatic compound layer of the surface-treated copper foil described above. The resin substrate is not particularly limited, and any known in the art can be used. Examples of resin substrates include paper-based phenolic resin, paper-based epoxy resin, synthetic fiber cloth-based epoxy resin, glass cloth / paper composite-based epoxy resin, glass cloth / glass nonwoven fabric composite-based epoxy resin, glass cloth-based epoxy resin, polyester film, polyimide resin, liquid crystal polymer, and fluororesin. Among these, polyimide resin is preferred as the resin substrate. The resin substrate may also be formed from a low-dielectric material. Examples of low-dielectric materials include liquid crystal polymer and low-dielectric polyimide.

[0032] The method for bonding the surface-treated copper foil and the resin substrate is not particularly limited and can be carried out in accordance with methods known in the art. For example, the surface-treated copper foil and the resin substrate can be laminated and then heat-pressed together. The copper-clad laminate manufactured in the manner described above can be used in the manufacture of printed circuit boards.

[0033] Because the copper-clad laminate according to the embodiment of the present invention uses the above-mentioned surface-treated copper foil, it is possible to reduce the time and cost required for manufacturing while improving the adhesion between the resin substrate, particularly the resin substrate suitable for high-frequency applications, and the surface-treated copper foil.

[0034] A printed circuit board according to an embodiment of the present invention comprises a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate described above. This printed circuit board can be manufactured by etching the surface-treated copper foil of the copper-clad laminate described above to form a circuit pattern. The method for forming the circuit pattern is not particularly limited, and known methods such as the subtractive method and the semi-additive method can be used. Among these, the subtractive method is preferred for forming the circuit pattern.

[0035] When manufacturing printed circuit boards using the subtractive method, it is preferable to proceed as follows: First, a resist pattern is formed by applying a resist to the surface of the surface-treated copper foil of a copper-clad laminate, exposing it to light, and developing it. Next, the surface-treated copper foil in areas where the resist pattern is not formed (unnecessary areas) is removed by etching to form a circuit pattern. Finally, the resist pattern on the surface-treated copper foil is removed. Furthermore, the various conditions in this subtractive method are not particularly limited and can be carried out in accordance with conditions known in the relevant art.

[0036] Since the printed circuit board according to the embodiment of the present invention uses the above-mentioned copper-clad laminate, it is possible to reduce the time and cost required for manufacturing while improving the adhesion between the resin substrate, particularly the resin substrate suitable for high-frequency applications, and the circuit pattern. [Examples]

[0037] The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these embodiments.

[0038] (Example 1) A commercially available rolled copper foil (HA-V2, manufactured by JX Metals Corporation; 12 μm thick) was prepared as the copper foil, and both sides of the copper foil were degreased and pickled. Degreasing was performed in a 20 g / L aqueous solution of GN Cleaner 87 (JX Metals Trading Co., Ltd.) at a current density of 11.3 A / dm². 2 The process was carried out by electrolysis of the surface of the rolled copper foil under conditions of 8.6 seconds. Pickling was performed by immersion in a 20 g / L sulfuric acid aqueous solution for 30 seconds. Next, benzotriazole, represented by formula (1) below, was used as the heteroaromatic compound, and an aqueous solution of benzotriazole (coating solution) was prepared. The concentration of benzotriazole in the aqueous solution was 1% by mass.

[0039] [ka]

[0040] Next, the copper foil was immersed in an aqueous solution of benzotriazole for 30 seconds, then rinsed with water and dried with a hairdryer. In this way, a surface-treated copper foil was obtained in which a benzotriazole layer (heteroaromatic compound layer) was formed on the surface of the copper foil.

[0041] (Example 2) A surface-treated copper foil was obtained in which an indazole layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that indazole represented by the following formula (2) was used as the heteroaromatic compound.

[0042] [ka]

[0043] (Example 3) A surface-treated copper foil was obtained in which a benzimidazole layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that benzimidazole represented by the following formula (3) was used as the heteroaromatic compound.

[0044] [ka]

[0045] (Example 4) A surface-treated copper foil was obtained in which an indole layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that indole represented by the following formula (4) was used as the heteroaromatic compound.

[0046] [ka]

[0047] (Example 5) A surface-treated copper foil was obtained in which a triazolopyridine layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that triazolopyridine represented by the following formula (5) was used as the heteroaromatic compound.

[0048] [ka]

[0049] (Example 6) A surface-treated copper foil was obtained in which a 1-methylbenzotriazole layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that 1-methylbenzotriazole represented by the following formula (6) was used as the heteroaromatic compound.

[0050] [ka]

[0051] (Example 7) A surface-treated copper foil was obtained in which a 5-methylbenzotriazole layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that 5-methylbenzotriazole represented by the following formula (7) was used as the heteroaromatic compound.

[0052] [ka]

[0053] (Example 8) A surface-treated copper foil was obtained in which a 1,2,3-triazole layer (heteroaromatic compound layer) was formed on the surface of the copper foil, under the same conditions as in Example 1, except that 1,2,3-triazole represented by the following formula (8) was used as the heteroaromatic compound.

[0054] [ka]

[0055] (Comparative Example 1) A commercially available rolled copper foil (HA-V2 manufactured by JX Metals Co., Ltd.; thickness 12 μm) with both sides degreased and pickled (copper foil without a complex aromatic compound layer) was used as a comparative sample. The degreasing and pickling were carried out under the same conditions as in Example 1.

[0056] (Comparative Example 2) Both sides of a commercially available rolled copper foil (HA-V2 manufactured by JX Metals Co., Ltd.; thickness 12 μm) were degreased and pickled under the same conditions as in Example 1. Next, a surface-treated copper foil was obtained by sequentially forming a roughened layer, a rust-preventive layer, and a silane coupling treatment layer on the surface of the copper foil. The conditions for forming each layer were as follows.

[0057] <Roughened layer> The roughened layer was formed by electroplating. The electroplating was carried out in three steps. The plating solution composition and current density are basically values rounded to the first decimal place. (Conditions for the first step) Plating solution composition: 11 g / L of Cu, 50 g / L of sulfuric acid Plating solution temperature: 27 °C Electroplating conditions: Current density 40 A / dm 2 , time 1.4 seconds (Conditions for the second step) Plating solution composition: 20 g / L of Cu, 100 g / L of sulfuric acid Plating solution temperature: 50 °C Electroplating conditions: Current density 5 A / dm 2 , time 2.0 seconds (Conditions for the third step) Plating solution composition: 16 g / L of Cu, 8 g / L of Co, 10 g / L of Ni Plating solution pH: 2.4 Plating solution temperature: 36 °C Electroplating conditions: Current density 32 A / dm 2 , time 0.2 seconds

[0058] <Rust-preventive layer> The rust-preventive layer was formed by electroplating. The electroplating was carried out in three steps. (Condition for the first row) Plating solution composition: 3 g / L Co, 13 g / L Ni Plating solution pH: 2.0 Plating solution temperature: 50℃ Electroplating conditions: Current density 2A / dm 2 , time 0.8 seconds (Condition for the second row) Plating solution composition: 5 g / L Zn, 24 g / L Ni Plating solution pH: 3.6 Plating solution temperature: 40℃ Electroplating conditions: Current density 4A / dm 2 , time 0.4 seconds (Condition for the third level) Plating solution composition: 3 g / L K2Cr2O7, 0.3 g / L Zn Plating solution pH: 3.7 Plating solution temperature: 55℃ Electroplating conditions: Current density 3A / dm 2 , time 0.8 seconds

[0059] <Silane coupling treatment layer> A silane coupling treatment layer was formed by applying a 4.0 vol% aqueous solution (pH: 10.4) of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) and drying it.

[0060] (Comparative Example 3) Both sides of a commercially available rolled copper foil (HA-V2, manufactured by JX Metals Corporation; 12 μm thick) were degreased and pickled under the same conditions as in Example 1. Next, a surface-treated copper foil was obtained by sequentially forming a roughening layer, a heat-resistant layer, a chromate treatment layer, and a silane coupling treatment layer on the surface of the copper foil. The conditions for forming each layer were as follows.

[0061] <Roughened layer> A roughened layer was formed by electroplating. The electroplating was carried out in two stages. (Condition for the first row) Plating solution composition: 11 g / L Cu, 50 g / L sulfuric acid Plating solution temperature: 25°C Electroplating conditions: Current density 42.7 A / dm 2 , Time 1.4 seconds (Conditions for the second stage) Plating solution composition: 20 g / L of Cu, 100 g / L of sulfuric acid Plating solution temperature: 50°C Electroplating conditions: Current density 3.8 A / dm 2 , Time 2.8 seconds

[0062] <Heat-resistant layer> A heat-resistant layer was formed by electroplating. Plating solution composition: 23.5 g / L of Ni, 4.5 g / L of Zn Plating solution pH: 3.6 Plating solution temperature: 40°C Electroplating conditions: Current density 1.1 A / dm 2 , Time 0.7 seconds

[0063] <Chromate treatment layer> A chromate treatment layer was formed by electroplating. Plating solution composition: 3.0 g / L of K2Cr2O7, 0.33 g / L of Zn Plating solution pH: 3.6 Plating solution temperature: 50°C Electroplating conditions: Current density 2.1 A / dm 2 , Time 1.4 seconds

[0064] <Silane coupling treatment layer> A 1.2% by volume aqueous solution (pH: 10) of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (KBM603 manufactured by Shin-Etsu Chemical Co., Ltd.) was applied and dried to form a silane coupling treatment layer.

[0065] For the surface-treated copper foils or copper foils obtained in the above Examples and Comparative Examples, the following characteristic evaluations were performed. <Sp, Vmp and Sv> Images were captured using an Olympus Corporation laser microscope (LEXT OLS4000). The captured images were analyzed using analysis software for an Olympus Corporation laser microscope (LEXT OLS4100). Sp, Vmp, and Sv measurements were performed in accordance with ISO 25178-2:2012. The measurement results were calculated as the average of values ​​measured at three arbitrary locations. The measurement temperature was 23-25°C. The main settings for the laser microscope and analysis software are as follows. Objective lens: MPLAPON50XLEXT (Magnification: 50x, Numerical aperture: 0.95, Immersion type: Air, Mechanical tube length: ∞, Cover glass thickness: 0, Field of view: FN18) Optical zoom magnification: 1x Scanning mode: XYZ high precision (height resolution: 60nm, number of pixels in acquired data: 1024×1024) Captured image size [pixel count]: 257μm (width) x 258μm (height) [1024 x 1024] (Since the measurement is taken in the lateral direction, the evaluation length corresponds to 257 μm.) DIC: Off Multilayer: Off Laser intensity: 100 Offset: 0 Confocal level: 0 Beam diameter aperture: Off Image average: 1 time Noise reduction: On Brightness uniformity correction: On Optical noise filter: On Cutoff: λc = 200 μm, λs and λf are not specified. Filter: Gaussian filter Noise reduction: Pre-measurement processing Surface (tilt) correction: Implemented Brightness: Adjust to a range of 30-50. Brightness should be set appropriately depending on the color tone of the object being measured. The above settings are appropriate when measuring the surface of surface-treated copper foil with L* set to -69 to -10, a* set to 2 to 32, and b* set to 2 to 21.

[0066] <Measurement of the color tone of the object to be measured> A HunterLab MiniScan® EZ Model 4000L was used as the measuring instrument, and measurements of L*, a*, and b* in the CIE L*a*b* color system were performed in accordance with JIS Z8730:2009. Specifically, the surface-treated copper foil or the surface of the copper foil to be measured obtained in the above examples and comparative examples was pressed against the photosensitive part of the measuring instrument, and measurements were taken while preventing light from entering from the outside. In addition, the measurements of L*, a*, and b* were performed based on geometric condition C of JIS Z8722:2009. The main conditions of the measuring instrument are as follows. Optical system: d / 8°, Integrating sphere size: 63.5 mm, Observation light source: D65 Measurement method: reflection Light diameter: 25.4mm Measuring diameter: 20.0 mm Measurement wavelength / interval: 400~700nm / 10nm Light source: Pulsed xenon lamp, 1 emission / measurement Traceability standards: Calibration compliant with the National Institute of Standards and Technology (NIST), based on CIE 44 and ASTM E259. Standard observer: 10° Furthermore, the white tiles used as the measurement standard were those with the following object colors. When measured at D65 / 10°, the values ​​in the CIE XYZ color system were X: 81.90, Y: 87.02, and Z: 93.76.

[0067] <Peel strength> After bonding surface-treated copper foil to a resin substrate made from a low-dielectric material, a 3 mm wide circuit was formed in the MD direction (longitudinal direction of the rolled copper foil). The circuit was formed according to a standard method. Next, the strength (MD90° peel strength) when peeling the circuit (surface-treated copper foil) from the surface of the resin substrate at a speed of 50 mm / min in a 90° direction, i.e., vertically upward relative to the surface of the LCP substrate, was measured in accordance with JIS C6471:1995. Three measurements were taken, and the average value was used as the peel strength result. A peel strength of 0.50 kgf / cm or higher indicates good adhesion between the circuit (surface-treated copper foil) and the LCP substrate.

[0068] The results of the above characteristic evaluation are shown in Table 1.

[0069] [Table 1]

[0070] As shown in Table 1, the surface-treated copper foils of Examples 1 to 8, which had a heteroaromatic compound layer formed and whose Sp was in the range of 0.10 to 1.00 μm, had a peel strength comparable to that of the surface-treated copper foil of Comparative Example 2, which had a surface-treated layer such as a roughening layer formed on it, and exhibited good adhesion between the LCP substrate and the surface-treated copper foil. In contrast, the copper foil of Comparative Example 1, which did not have a heteroaromatic compound layer, had low peel strength. Furthermore, it is thought that Comparative Example 3 also had lower peel strength because it was less roughened compared to Comparative Example 2. The above results are surprising. As already mentioned, improving the adhesion between copper foil and resin substrates such as LCP substrates is generally achieved by forming a surface treatment layer containing roughened particles. In the embodiment of the present invention, sufficient adhesion to resin substrates such as LCP substrates is ensured by the presence of a heteroaromatic compound layer with a smooth surface.

[0071] As can be seen from the above results, according to embodiments of the present invention, it is possible to provide a surface-treated copper foil that can improve adhesion to a resin substrate, particularly a resin substrate suitable for high-frequency applications, while reducing the time and cost required for manufacturing. Furthermore, according to embodiments of the present invention, it is possible to provide a copper-clad laminate with excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and the surface-treated copper foil, while reducing the time and cost required for manufacturing. Moreover, according to embodiments of the present invention, it is possible to provide a printed wiring board with excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and the circuit pattern, while reducing the time and cost required for manufacturing.

[0072] Embodiments of the present invention may also take the following forms. <1> The device comprises a copper foil and a heteroaromatic compound layer formed on at least one surface of the copper foil. The aforementioned heteroaromatic compound layer comprises a heteroaromatic compound having a heterocycle containing a nitrogen atom as a heteroatom, and is a surface-treated copper foil with an Sp of 0.10 to 1.00 μm. <2> The aforementioned heterocycle is a five-membered ring containing 1 to 3 nitrogen atoms. <1> Surface-treated copper foil as described above. <3> The heteroaromatic compound is a fused ring compound of a benzene ring and the hetero ring, a fused ring compound of two or more of the hetero rings, or a monocyclic compound of the hetero ring. <1> or <2> Surface-treated copper foil as described above. <4> The heteroaromatic compound is one or more selected from the group consisting of benzotriazole, indazole, benzimidazole, indole, triazolopyridine, 1-methylbenzotriazole, 5-methylbenzotriazole, and 1,2,3-triazole. <1> ~ <3> Surface-treated copper foil as described in any one of the following. <5> The above Sp is 0.10 to 0.85 μm. <1> ~ <4> Surface-treated copper foil as described in any one of the following. <6> The above Sp is 0.10 to 0.78 μm. <5> Surface-treated copper foil as described above. <7> The above Sp is 0.30 to 0.78 μm. <5> Surface-treated copper foil as described above. <8> The aforementioned heteroaromatic compound layer has a Vmp of 0.001 to 0.010 μm. 3 / μm 2 The above <1> ~ <7> Surface-treated copper foil as described in any one of the following. <9> The Vmp is 0.001 to 0.006 μm 3 / μm 2 The above <8> Surface-treated copper foil as described above. <10> the above <1> ~ <9> A copper-clad laminate comprising a surface-treated copper foil as described in any one of the above, and a resin substrate bonded to the complex aromatic compound layer of the surface-treated copper foil. <11> the above <10> A printed wiring board having a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate described above.

Claims

1. The device comprises a copper foil and a heteroaromatic compound layer formed on at least one surface of the copper foil. The heteroaromatic compound layer comprises a heteroaromatic compound having a heterocycle containing a nitrogen atom as a heteroatom, with an Sp of 0.10 to 1.00 μm and a Vmp of 0.001 to 0.010 μm³ / μm², and is a surface-treated copper foil.

2. The surface-treated copper foil according to claim 1, wherein the heterocycle is a five-membered ring containing one to three nitrogen atoms.

3. The surface-treated copper foil according to claim 1, wherein the heteroaromatic compound is a fused ring compound of a benzene ring and the hetero ring, a fused ring compound of two or more of the hetero rings, or a monocyclic compound of the hetero ring.

4. The surface-treated copper foil according to claim 1, wherein the heteroaromatic compound is one or more selected from the group consisting of benzotriazole, indazole, benzimidazole, indole, triazolopyridine, 1-methylbenzotriazole, 5-methylbenzotriazole, and 1,2,3-triazole.

5. The surface-treated copper foil according to claim 3, wherein the Sp is 0.10 to 0.85 μm.

6. The surface-treated copper foil according to claim 3, wherein the Sp is 0.10 to 0.78 μm.

7. The surface-treated copper foil according to claim 3, wherein the Sp is 0.30 to 0.78 μm.

8. The Vmp is 0.001 to 0.006 μm 3 / μm 2 The surface-treated copper foil according to any one of claims 1 to 7.

9. A copper-clad laminate comprising a surface-treated copper foil according to any one of claims 1 to 7, and a resin substrate bonded to the complex aromatic compound layer of the surface-treated copper foil.

10. A printed wiring board comprising a circuit pattern made of the surface-treated copper foil of the copper-clad laminate according to claim 9.

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