Copper-clad laminate and method for manufacturing printed circuit board

Abstract

Provided is a method for producing a copper-clad laminate in which a copper foil and a resin are joined with high heat-resistant adhesion even if a fluororesin belonging to a low dielectric constant thermoplastic resin is used. The method includes a step of preparing a surface-treated copper foil having a copper foil and a zinc-containing layer provided on at least one side of the copper foil, and a step of obtaining a copper-clad laminate by attaching a sheet-shaped fluororesin to the zinc-containing layer side of the surface-treated copper foil, thereby obtaining a copper-clad laminate. The zinc-containing layer is composed of Zn and a transition element M having a melting point of 1200°C or higher. When the interface between the copper foil and the zinc-containing layer is subjected to elemental analysis by X-ray photoelectron spectroscopy (XPS), the content of Zn is 10% by weight or less, and the weight ratio of the content ratio of Zn to the content of the transition element M, i.e., Zn / M, is 0.2 or more and 0.6 or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a copper-clad laminate and a manufacturing method of a printed circuit board. BACKGROUND

[0002] With the high functionality of portable electronic devices and the like in recent years, in order to process a large amount of information at high speed, the high frequency of signals is advancing, and a printed circuit board suitable for high frequency applications such as base station antennas is required. For such a high frequency printed circuit board, in order to be able to transmit high frequency signals without reducing the quality, reduction of transmission loss is desired. The printed circuit board has a copper foil processed into a wiring pattern and an insulating resin base material, and the transmission loss is mainly caused by conductor loss due to the copper foil and dielectric loss due to the insulating resin base material. Therefore, in order to reduce the dielectric loss due to the insulating resin base material, it is ideal if a thermoplastic resin having a low dielectric constant can be used. However, unlike thermosetting resins, low dielectric constant thermoplastic resins typified by polytetrafluoroethylene (PTFE) and the like have low chemical activity, and therefore have low adhesion to copper foils. Therefore, a technology for improving the adhesion of copper foils to thermoplastic resins has been proposed.

[0003] For example, Patent Literature 1 (International Publication No. 2017 / 150043) discloses a scheme for ensuring adhesion to a fluororesin by using a copper foil having fine irregularities formed by oxidation treatment and reduction treatment.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2017 / 150043 SUMMARY

[0007] However, in the copper-clad laminate in which the copper foil disclosed in Patent Literature 1 is bonded to a fluororesin base material, the adhesion between the copper foil and the base material at high temperatures is still low, and further improvement in heat-resistant adhesion is required. In particular, printed circuit boards using fluororesins are sometimes exposed to harsh environments such as high temperatures, and it is desirable that the adhesion of the copper foil to the resin base material be high even after exposure to such harsh environments. In fact, printed circuit boards using fluororesins such as PTFE are sometimes used for aerospace and space applications, and from this point of view, further improvement in adhesion at high temperatures is also desired. That is, it is necessary to balance the adhesion and heat resistance between the copper foil and the fluororesin base material.

[0008] The present inventors have arrived at the following insight that by attaching a surface-treated copper foil having a zinc-containing layer having a prescribed interface composition to a fluororesin, a copper-clad laminate can be manufactured that not only has high adhesion, but also has excellent heat resistance in which the adhesion does not deteriorate at high temperatures, in other words, the copper foil and the fluororesin are joined with high heat-resistant adhesion.

[0009] Accordingly, an object of the present application is to produce a copper-clad laminate in which a copper foil is joined to a resin with high heat-resistant adhesion even if a fluororesin belonging to a low dielectric constant thermoplastic resin is used.

[0010] According to one embodiment of the present application, there is provided a method for producing a copper-clad laminate, comprising:

[0011] a step of preparing a surface-treated copper foil having a copper foil and a zinc-containing layer provided on at least one side of the copper foil; and

[0012] a step of obtaining a copper-clad laminate by attaching a sheet-shaped fluororesin to the zinc-containing layer side of the surface-treated copper foil, thereby obtaining a copper-clad laminate,

[0013] the zinc-containing layer is composed of Zn and a transition element M having a melting point of 1200°C or higher,

[0014] when the interface between the copper foil and the zinc-containing layer is subjected to elemental analysis by X-ray photoelectron spectroscopy (XPS), the content of Zn is 10% by weight or less, and the content ratio of Zn relative to the content of the transition element M, i.e., the weight ratio of Zn / M, is 0.2 or more and 0.6 or less.

[0015] According to another embodiment of the present application, there is provided a method for producing a printed circuit board, comprising:

[0016] a step of producing the copper-clad laminate by the above method; and

[0017] a step of forming a circuit on the copper-clad laminate, thereby producing a printed circuit board. DETAILED DESCRIPTION

[0018] Method for manufacturing a copper clad laminate

[0019] The present application relates to a manufacturing method of a copper-clad laminate. The method of the present application includes: (1) a step of preparing a surface-treated copper foil having a copper foil and a zinc-containing layer provided on at least one surface of the copper foil; and (2) a step of obtaining a copper-clad laminate by attaching a sheet-shaped fluororesin to the zinc-containing layer side of the surface-treated copper foil. The zinc-containing layer is composed of Zn and a transition element M having a melting point of 1200°C or higher. Furthermore, when the interface between the copper foil and the zinc-containing layer is analyzed by X-ray photoelectron spectroscopy (XPS), the content of Zn is 10% by weight or less, and the ratio of the content of Zn to the content of the transition element M, i.e., the weight ratio of Zn / M, is 0.2 or more and 0.6 or less. In this way, by attaching the surface-treated copper foil having the zinc-containing layer with the prescribed interface composition to the fluororesin, a copper-clad laminate can be manufactured which not only has high adhesion but also has excellent heat resistance in which the adhesion is difficult to deteriorate at high temperatures, in other words, the copper foil and the fluororesin are joined with high heat-resistant adhesion.

[0020] That is, as described above, unlike thermosetting resins, thermoplastic resins such as fluororesins typified by polytetrafluoroethylene (PTFE) have low chemical activity, and thus inherently have low adhesion to copper foils. Even the copper-clad laminate disclosed in Patent Literature 1, which addresses this problem, has a large decrease in adhesion between the copper foil and the substrate at high temperatures. In this regard, by the method of the present application, the interface having the Zn content and the Zn / M ratio within the above-described ranges is selectively used as the surface-treated copper foil having the zinc-containing layer, and is attached to the fluororesin, whereby a copper-clad laminate can be manufactured which not only has high adhesion between the copper foil and the fluororesin but also has excellent heat resistance in which the adhesion is difficult to deteriorate at high temperatures.

[0021] (1) Preparation of surface-treated copper foil

[0022] The surface-treated copper foil used in the method of the present application has a copper foil and a zinc-containing layer provided on at least one surface of the copper foil. The copper foil is preferably a roughened treated copper foil having roughened particles on at least one surface, and more preferably the surface on the zinc-containing layer side of the copper foil is a roughened treated surface. A publicly known roughened treated copper foil can be used. The thickness of the copper foil is not particularly limited, and is preferably 0.1 μm or more and 70 μm or less, and more preferably 0.5 μm or more and 18 μm or less.

[0023] The zinc-containing layer is not particularly limited in the manner in which it is formed, provided that it is composed of Zn and a transition element M having a melting point of 1200°C or higher, and is preferably an alloy of Zn and M, i.e., a zinc alloy. As a preferred example of the transition element M having a melting point of 1200°C or higher, Co, Fe, Ni, Mo, W, and combinations thereof can be given, more preferably Co, Ni, Mo, and combinations thereof can be given, further preferably Ni and / or Mo can be given, and particularly preferably Ni can be given. Thus, the zinc-containing layer is preferably composed of a Zn-Co alloy, a Zn-Fe alloy, a Zn-Ni alloy, a Zn-Mo alloy, a Zn-W alloy, a Zn-Ni-Mo alloy, or a combination thereof, more preferably composed of a Zn-Co alloy, a Zn-Ni alloy, a Zn-Mo alloy, a Zn-Ni-Mo alloy, further preferably composed of a Zn-Ni alloy, a Zn-Mo alloy, a Zn-Ni-Mo alloy, and particularly preferably composed of a Zn-Ni alloy.

[0024] As described above, the content of Zn is 10% by weight or less, preferably 1.0% by weight or more and 10.0% by weight or less, more preferably 2.0% by weight or more and 8.0% by weight or less, further preferably 2.1% by weight or more and 7.5% by weight or less, and particularly preferably 2.1% by weight or more and 7.0% by weight or less, when the interface between the copper foil and the zinc-containing layer is analyzed by XPS. The content of Zn within the above range is particularly effective in improving the adhesion between the copper foil and the substrate (particularly the normal peel strength). In addition, the ratio of the content of Zn to the content of the transition element M, i.e., the Zn / M weight ratio, is 0.2 or more and 0.6 or less, preferably 0.22 or more and 0.58 or less, and more preferably 0.25 or more and 0.55 or less, when the interface between the copper foil and the zinc-containing layer is analyzed by XPS. The Zn / M weight ratio within the above range is particularly effective in improving the heat resistance (particularly the property that the adhesion between the copper foil and the substrate is difficult to deteriorate at high temperatures).

[0025] In the present application, the content of Zn and the Zn / M weight ratio are determined at the interface between the copper foil and the zinc-containing layer, which refers to the portion of the zinc-containing layer directly above the copper foil. This portion is considered to be a region that is difficult to be affected by surface oxidation and the like and is important for imparting adhesion and heat resistance. The position (depth) of the interface between the copper foil and the zinc-containing layer is defined as follows: in the XPS-based elemental analysis performed in the depth direction from the zinc-containing layer toward the copper foil, it is defined in the form of an inflection point in the curve formed by the measurement depth (horizontal axis) and the amount of Cu (vertical axis). Specifically, it is determined using the following steps i) to vi).

[0026] i) The surface of the zinc-containing layer opposite the copper foil is set to a measurement depth D1 = 0 nm, and element analysis based on XPS is performed while digging down from the measurement depth D1 = 0 nm toward the depth direction of the copper foil by sputtering. Element analysis is performed at the measurement depth D1 = 0 nm at the same time as the start of the XPS-based measurement, and thereafter, element analysis is performed at the measurement depth D n (n represents the measurement point) at a prescribed sputtering time (for example, 20 seconds) from the start of the measurement. For example, measurement is performed at equal time intervals of 20 seconds after the start of the measurement at measurement point D2 and 40 seconds after the start of the measurement at measurement point D3. One example of the preferred measurement conditions for XPS is shown below (more specific measurement conditions are shown in the examples described later).

[0027] (Measurement conditions)

[0028] - Ion gun settings: Ar gas, 1 kV 2 mm x 2 mm

[0029] - Sputtering rate: 3.43 nm / min

[0030] ii) The content C n (n) of Cu at measurement point n is measured according to i) above.

[0031] iii) A graph is prepared with the measurement depth D n as the horizontal axis and the content C n of Cu as the vertical axis, and the slope S n = (C n+1 - C n ) / (D n+1 - D n ) of the tangent line at measurement point n is calculated for the resulting curve.

[0032] iv) The change rate AS n = S n - S n+1 of the slope of the tangent line is calculated from the resulting slope S n of the tangent line.

[0033] v) The curvature c n = AS n / (D n - D n+1 ) is calculated from the resulting change rate AS n of the slope of the tangent line.

[0034] vi) The measurement point at which the curvature c n = 0 is identified as the Cu inflection point, and the position of the measurement depth D n having this Cu inflection point is determined as the interface between the copper foil and the zinc-containing layer. Note that in order to avoid accidental curvatures c n caused by positive / negative changes in the curvature cn = 0, Cu inflection point using curvature c n Curvature c in the region where convergence to 0 is stably started n = 0. By using such a method, the interface of the copper foil and the zinc-containing layer can be determined without any doubt.

[0035] The surface-treated copper foil preferably has a chromate layer and / or a silane coupling agent layer on the side of the zinc-containing layer, and more preferably has both a chromate layer and a silane coupling agent layer. By further having a chromate layer and / or a silane coupling agent layer, not only rust resistance, humidity resistance, and chemical resistance are improved, but also adhesion to the fluororesin substrate can be improved by the combination with the zinc-containing layer.

[0036] (2) Attachment of fluororesin

[0037] A copper-clad laminate is obtained by attaching a sheet-like fluororesin to the zinc-containing layer side of the surface-treated copper foil. The attachment of the fluororesin to the surface-treated copper foil can be performed according to the known manufacturing steps of the copper-clad laminate, and is not particularly limited. Alternatively, a method for attaching a copper foil to an inner layer substrate by means of a fluororesin can be used, in which case it can be performed according to the known method such as the so-called build-up method. In summary, by the method of the present application, the surface-treated copper foil having a zinc-containing layer, which selectively has an interface having the Zn content and Zn / M ratio within the above-mentioned ranges, is attached to a fluororesin. Thereby, a copper-clad laminate having not only high adhesion between the copper foil and the fluororesin but also excellent heat resistance in which the adhesion is hardly deteriorated at high temperatures can be manufactured. The attachment of the fluororesin to the surface-treated copper foil is preferably performed by pressing while heating. The temperature at the time of pressing can be appropriately determined according to the characteristics of the fluororesin to be used, and is not particularly limited, and is preferably 150 to 500°C, and more preferably 180 to 400°C. The pressing pressure is also not particularly limited, and is preferably 1 to 10 MPa, and more preferably 2 to 5 MPa.

[0038] The sheet-like fluororesin can be a cut sheet or a long strip sheet drawn from a roll, and the mode is not particularly limited. As preferable examples of the fluororesin, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), and any combination thereof can be listed.

[0039] The surface-treated copper foil can be provided on one side of the sheet-shaped fluororesin, or on both sides. The sheet-shaped fluororesin can contain only the fluororesin, and can further contain other materials. Thus, the sheet-shaped fluororesin can also be a prepreg. The prepreg refers to a general term for a composite material in which a synthetic resin is impregnated in a base material such as a synthetic resin plate, a glass plate, a glass woven fabric, a glass nonwoven fabric, paper, or the like. In addition, from the viewpoint of improving the insulating properties and the like, the fluororesin can contain filler particles formed of various inorganic particles such as silica and alumina, or the like. The thickness of the sheet-shaped fluororesin is not particularly limited, and is preferably 1 to 1000 μm, more preferably 2 to 400 μm, and further preferably 3 to 200 μm. The fluororesin layer can also be composed of a plurality of layers.

[0040] Method for manufacturing a surface-treated copper foil

[0041] The surface-treated copper foil according to the present application can be produced by any method as long as a zinc-containing layer can be formed on the copper foil, and is preferably produced by zinc alloy plating. Hereinafter, an example of a preferred production method of the surface-treated copper foil according to the present application will be described. The preferred production method includes a step of preparing a copper foil, and a step of plating a zinc alloy on the surface.

[0042] (1) Preparation of Copper Foil

[0043] As the copper foil used in the production of the surface-treated copper foil, both electrolytic copper foil and rolled copper foil can be used, and electrolytic copper foil is more preferable. In addition, the copper foil is preferably subjected to roughening treatment, and for example, a roughened surface on which roughening particles are attached can be formed on the surface of the copper foil by electroplating using an aqueous solution containing sulfuric acid and copper sulfate. The maximum height Sz of the roughened surface, which is measured in accordance with ISO 25178, is preferably 3.0 μm or more and 15.0 μm or less, and more preferably 4.0 μm or more and 12.0 μm or less. When the copper foil is prepared in the form of a copper foil with a carrier, the copper foil can be formed by a wet film formation method such as electroless copper plating and electrolytic copper plating, a dry film formation method such as sputtering and chemical vapor deposition, or a combination thereof.

[0044] (2) Formation of Zinc-Containing Layer by Zinc Alloy Plating

[0045] The zinc-containing layer is preferably formed by plating a zinc alloy on the surface (e.g., the roughened surface) of the above-described copper foil. As examples of the zinc alloy plating, Zn-Co alloy plating, Zn-Fe alloy plating, Zn-Ni alloy plating, Zn-Mo alloy plating, Zn-W alloy plating, Zn-Ni-Mo alloy plating, and combinations thereof can be listed. The zinc alloy plating can be performed by preparing a plating solution in such a manner that a desired zinc alloy composition is obtained, and using a publicly known electroplating method. For example, when Zn-Ni alloy plating is performed, it is preferable to perform electroplating using an aqueous solution containing zinc oxide, nickel sulfate, and potassium diphosphate.

[0046] (3) Chromate treatment

[0047] The copper foil having the zinc-containing layer is preferably subjected to chromate treatment to form a chromate layer. The chromate treatment is preferably performed using a chromate treatment solution having a chromic acid concentration of 0.5 to 8 g / L and a pH of 1 to 13 at a current density of 0.1 to 10 A / dm 2 The electrolysis is preferably performed for 1 to 30 seconds.

[0048] (4) Silane coupling agent treatment

[0049] The copper foil is preferably subjected to silane coupling agent treatment to form a silane coupling agent layer. The silane coupling agent layer can be formed by diluting a silane coupling agent as appropriate and coating and drying it. Examples of the silane coupling agent include (i) epoxy-functional silane coupling agents such as 4-glycidoxybutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane; (ii) amino-functional silane coupling agents such as 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butyloxy)propyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; (iii) mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane; (iv) olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane; (v) acrylic-functional silane coupling agents such as 3-methacryloyloxypropyltrimethoxysilane; (vi) imidazole-functional silane coupling agents such as imidazolesilane; and (vii) triazine-functional silane coupling agents such as triazinesilane. Note that when both the chromate layer and the silane coupling agent layer are formed on the surface of the zinc-containing layer, the order of formation is not particularly limited.

[0050] Method for manufacturing a printed circuit board

[0051] The copper-clad laminate of the present application is preferably used for the production of a printed circuit board. That is, according to a preferred embodiment of the present application, there is provided a method for producing a printed circuit board, which comprises a step of producing the above-described copper-clad laminate; and a step of forming a circuit on the copper-clad laminate, thereby producing a printed circuit board. As specific examples relating to the printed circuit board, there can be mentioned a single-sided or double-sided printed circuit board on which a circuit is formed on the copper-clad laminate of the present application, a multilayer printed circuit board in which these are multilayered, and the like. The multilayer printed circuit board can be one in which a copper foil is attached to an inner layer substrate with a thermoplastic resin (e.g., a fluororesin) and a circuit is formed thereon, or one in which a build-up layer is further formed. In addition, the circuit formation method can be subtractive or semi-additive (MSAP method). The printed circuit board produced using the copper-clad laminate of the present application can be suitably used as a high-frequency substrate used in applications such as an antenna for a car, a base station antenna for a mobile phone, a high-performance server, a radar for collision avoidance, and the like, which are used at a high frequency of 10 GHz or more.

[0052] Example

[0053] The present application is further specifically described by the following examples.

[0054] Examples 1 to 7

[0055] (1) Preparation of surface-treated copper foil

[0056] Various surface-treated copper foils having a zinc-containing layer on the surface of a copper foil were prepared based on a known method. With respect to the surface-treated copper foils, the electrode surface of an electrolytic copper foil (thickness: 35 μm) was subjected to roughening treatment, Zn-Ni alloy plating (Examples 1 to 5) or Zn-Ni-Mo alloy plating (Examples 6 and 7), chromate treatment, and silane coupling treatment in this order using a known method. With respect to each of the surface-treated copper foils, elements were analyzed using XPS while digging from the depth direction of the zinc-containing layer toward the copper foil. In this element analysis, a scanning-type double-channel X-ray photoelectron spectrometer (XPS) (manufactured by ULVAC-PHI, Inc., PHI Quantes) was used, and the measurement conditions were as follows.

[0057] (Measurement conditions)

[0058] - Power: 50 W

[0059] - X-ray type: Monochromatic Al Kα line

[0060] - Ion gun setting: Ar gas, 1 kV (Examples 1 to 5) or 2 kV (Examples 6 and 7), 2 mm x 2 mm

[0061] - Sputtering rate (in terms of SiO2): 3.43 nm / min (Examples 1 to 5) or 12.3 nm / min (Examples 6 and 7)

[0062] - Measuring elements and orbit: C 1s, O 1s, Si 2p, Cr 3p, Ni 2p3, Cu 2p3, Zn 2p3, Mo 3d (only Examples 6 and 7)

[0063] - Measuring surface: from the zinc-containing layer to the interface

[0064] Based on the obtained elemental analysis results, the Cu inflection point was determined in accordance with the aforementioned definition and procedure, thereby determining the position (depth) of the interface between the copper foil and the zinc-containing layer. Although the copper foil was subjected to the roughening treatment, the roughened layer (roughened particles) was also regarded as being included in the copper foil when determining the position of the interface. Next, at the interface, the content ratio of the Zn element in the total weight of the measuring elements was calculated as the Zn content (wt%), and the content ratio of the transition elements M (here, Ni and Mo) in the total weight of the measuring elements was calculated as the M content (wt%). In addition, the Zn / M weight ratio was calculated using the obtained Zn content and M content. The results are shown in Table 1.

[0065] (2) Production of Copper-Clad Laminate

[0066] As the fluororesin substrate, a PTFE substrate (RO3003 Bondply, manufactured by ROGERS Corporation, thickness 125 μm, 1 ply) was prepared. On the PTFE substrate, the above surface-treated copper foil was laminated with the zinc-containing layer side of the copper foil in contact with the substrate, and using a vacuum press, the copper foil was pressed under conditions of a press pressure of 2.4 MPa, a temperature of 370°C, and a press time of 30 minutes, thereby producing a copper-clad laminate.

[0067] (3) Evaluation of Copper-Clad Laminate

[0068] The produced copper-clad laminate was subjected to various evaluations shown below.

[0069] <Normal peel strength with respect to fluororesin (PTFE)>

[0070] A 0.4 mm wide straight line circuit was formed on the copper-clad laminate by the subtractive method using a copper chloride etching solution, thereby obtaining a test substrate having a straight line circuit for peel strength measurement. The straight line circuit was peeled from the PTFE substrate in accordance with the A method (90° peeling) of JIS C 5016-1994, and the normal peel strength (kgf / cm) was measured. The measurement was performed using a table-top precision universal testing machine (AGS-50NX, manufactured by Shimadzu Corporation). The results are shown in Table 1.

[0071] <Heat-resistant peeling strength against fluororesin (PTFE)>

[0072] A test substrate having a 0.4 mm wide linear circuit for peeling strength measurement was loaded into an oven, heated at 150°C for 4 hours, floated in a solder bath at 288°C for 10 seconds, and otherwise, using the same procedure as the above normal peeling strength against PTFE, the heat-resistant peeling strength against PTFE (kgf / cm) was measured. The results are shown in Table 1.

[0073] <Heat-resistant deterioration rate>

[0074] The reduction rate (%) of the heat-resistant peeling strength against the normal peeling strength was calculated as the heat-resistant deterioration rate. The results are shown in Table 1.

[0075] [Table 1]

[0076] Table 1

[0077]

[0078] * indicates a comparative example.

[0079] From the results shown in Table 1, it is known that Examples 1, 2, 6 and 7, which satisfy the conditions of the present application of the Zn content being 10 wt% or less at the interface between the copper foil and the zinc-containing layer, and the weight ratio of Zn / M (here, Zn / (Ni+Mo)) being 0.2 or more and 0.6 or less, have higher peeling strength (i.e., higher adhesion) and significantly lower heat-resistant deterioration rate (i.e., excellent heat resistance) than the comparative examples of Examples 3 to 5, which do not satisfy the conditions.

Claims

1. A method for producing a copper-clad laminate, comprising: a step of preparing a surface-treated copper foil having a copper foil and a zinc-containing layer provided on at least one side of the copper foil; and a step of obtaining a copper-clad laminate by attaching a sheet-shaped fluororesin to the zinc-containing layer side of the surface-treated copper foil, thereby obtaining a copper-clad laminate, the zinc-containing layer is composed of Zn and a transition element M having a melting point of 1200°C or higher, when the interface between the copper foil and the zinc-containing layer is subjected to elemental analysis by X-ray photoelectron spectroscopy (XPS), the content of Zn is 10% by weight or less, and the content ratio of Zn to the content of the transition element M, i.e., the weight ratio of Zn / M, is 0.2 or more and 0.6 or less, the transition element M is at least one selected from the group consisting of Co, Fe, Ni, Mo, and W. the transition element M is Ni and / or Mo.

2. The method of producing a copper-clad laminate according to claim 1, wherein the content of Zn at the interface is 1.0% by weight or more and 10.0% by weight or less.

3. The method of producing a copper-clad laminate according to claim 1 or 2, wherein the content of Zn at the interface is 2.0% by weight or more and 8.0% by weight or less.

4. The method of producing a copper-clad laminate according to claim 1 or 2, wherein the weight ratio of Zn / M at the interface is 0.25 or more and 0.55 or less.

5. The method of producing a copper-clad laminate according to claim 1 or 2, wherein the fluororesin is at least one selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, and tetrafluoroethylene-ethylene copolymer.

6. The method of producing a copper-clad laminate according to claim 1 or 2, wherein the surface of the zinc-containing layer side of the copper foil is a roughened surface.

7. The method of producing a copper-clad laminate according to claim 1 or 2, wherein 8. A method for producing a printed circuit board, comprising: a step of producing the copper-clad laminate by the method according to any one of claims 1 to 7; and a step of forming a circuit on the copper-clad laminate, thereby producing a printed circuit board.

9. The method for producing a printed circuit board according to claim 8, wherein the copper-clad laminate is produced by the method according to any one of claims 1 to 7.

Images