Surface-treated copper foil, copper-clad laminate, and method for manufacturing printed wiring board

Abstract

This surface-treated copper foil 1 comprises: a copper foil 2; and a surface-treated layer 3 formed on at least one surface of the copper foil 2. The surface-treated layer 3 contains Ni, Zn, and Cr. In the surface-treated layer 3, the Zn adhesion amount is 100-500 μg / dm2, the Cr adhesion amount is 70-150 μg / dm2, and the ratio of the Cr adhesion amount to the total of the Ni adhesion amount, the Zn adhesion amount, and the Cr adhesion amount is 18.0-50.0%.

Description

Method for manufacturing surface-treated copper foil, copper-clad laminate, and printed wiring board

[0001] The present disclosure relates to a method for manufacturing a surface-treated copper foil, a copper-clad laminate, and a printed wiring board.

[0002] Copper-clad laminates are manufactured by laminating copper foil to a substrate composed of resin or other materials. Copper-clad laminates are widely used in various applications, such as flexible printed wiring boards. Flexible printed wiring boards are manufactured by etching the copper foil of a copper-clad laminate to form a circuit pattern (also called a "conductor pattern"), and then soldering and mounting electronic components onto the circuit pattern. Before mounting the electronic components, the circuit pattern is soft-etched to remove unnecessary materials from the copper foil surface and roughen the copper foil surface.

[0003] The elements contained and / or the shape of the surface of copper foil used in copper-clad laminates are controlled so as to satisfy required properties. For example, Patent Document 1 discloses a surface-treated copper foil that has excellent adhesion to resin, chemical resistance, and heat resistance, and is less likely to leave etching residues, and that includes a copper foil and a surface treatment layer (Zn—Ni—Mo layer) provided on at least one side of the copper foil and in which the Zn deposition amount, Ni deposition amount, and Mo deposition amount are controlled.

[0004] International Publication No. 2019 / 188837

[0005] The surface-treated copper foil described in Patent Document 1 sometimes suffers from undercuts during soft etching, resulting in reduced reliability of the circuit pattern (e.g., reduced adhesion strength between the substrate and the circuit pattern). The present invention has been made to solve the above-mentioned problems, and in one aspect, aims to provide a surface-treated copper foil and a copper-clad laminate that can suppress the occurrence of undercuts during soft etching. In another aspect, the present invention aims to provide a method for manufacturing a printed wiring board having a circuit pattern in which undercuts are suppressed.

[0006] As a result of extensive research into surface-treated copper foils, the present inventors have found that the above-mentioned problems can be solved by forming a surface treatment layer containing Ni, Zn, and Cr on at least one surface of a copper foil, and controlling the Zn coating weight, the Cr coating weight, and the ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight within a predetermined range, thereby completing an embodiment of the present invention.

[0007] That is, in one aspect, an embodiment of the present invention comprises a copper foil and a surface treatment layer formed on at least one surface of the copper foil, the surface treatment layer containing Ni, Zn, and Cr, and the Zn coating amount in the surface treatment layer is 100 to 500 μg / dm 2 The Cr deposition amount is 70 to 150 μg / dm 2 and the ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 18.0 to 50.0%.

[0008] In another aspect, an embodiment of the present invention relates to a copper-clad laminate comprising the surface-treated copper foil and a substrate provided on the surface treatment layer of the surface-treated copper foil.

[0009] Furthermore, in another aspect, an embodiment of the present invention relates to a method for producing a printed wiring board, in which the surface-treated copper foil of the copper-clad laminate is etched to form a circuit pattern, and then soft-etched.

[0010] According to an embodiment of the present invention, in one aspect, it is possible to provide a surface-treated copper foil and a copper-clad laminate that can suppress the occurrence of undercut during soft etching. Also, according to another aspect, it is possible to provide a method for manufacturing a printed wiring board having a circuit pattern in which undercut is suppressed.

[0011] Fig. 1 is a cross-sectional view showing an example of a copper-clad laminate comprising a surface-treated copper foil according to an embodiment of the present invention; Fig. 2 is a cross-sectional view showing an example of a state in which a circuit pattern is formed by etching the surface-treated copper foil of a copper-clad laminate comprising a surface-treated copper foil according to an embodiment of the present invention, and then soft-etching is performed; Fig. 3 is a cross-sectional view showing an example of a state in which a circuit pattern is formed by etching the surface-treated copper foil of a copper-clad laminate comprising a conventional surface-treated copper foil, and then soft-etching is performed; Fig. 4 is an example of an observed image of a circuit pattern in which undercuts have occurred;

[0012] Preferred embodiments of the present invention will be described in detail below, but the present invention should not be construed as being limited thereto, and various modifications and improvements can be made based on the knowledge of those skilled in the art without departing from the gist of the present invention. The multiple components disclosed in the following embodiments can be appropriately combined to form various inventions. For example, some components may be deleted from all the components shown in the following embodiments, or components from different embodiments may be appropriately combined.

[0013] The surface-treated copper foil according to an embodiment of the present invention comprises a copper foil and a surface treatment layer formed on at least one surface of the copper foil, the surface treatment layer containing Ni, Zn, and Cr, and the Zn coating amount in the surface treatment layer is 100 to 500 μg / dm 2 The Cr deposition amount is 70 to 150 μg / dm 2 The ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 18.0 to 50.0%. By adopting such a configuration, the surface-treated copper foil according to the embodiment of the present invention can suppress the occurrence of undercuts during soft etching.

[0014] Furthermore, a copper clad laminate according to an embodiment of the present invention includes the above-mentioned surface-treated copper foil and a substrate provided on the surface treatment layer of the above-mentioned surface-treated copper foil. By adopting such a configuration, the copper clad laminate according to an embodiment of the present invention can suppress the occurrence of undercuts when soft etching is performed after etching the surface-treated copper foil to form a circuit pattern.

[0015] Fig. 1 is a cross-sectional view showing an example of a copper-clad laminate including a surface-treated copper foil according to an embodiment of the present invention. As shown in Fig. 1, the surface-treated copper foil 1 includes a copper foil 2 and a surface treatment layer 3 formed on at least one surface of the copper foil 2. The copper-clad laminate 10 includes the surface-treated copper foil 1 and a substrate 11 provided on the surface treatment layer 3 of the surface-treated copper foil 1.

[0016] 2 is a cross-sectional view showing an example of a state in which a circuit pattern is formed by etching the surface-treated copper foil of a copper clad laminate having a surface-treated copper foil according to an embodiment of the present invention, followed by soft etching. As shown in FIG. 2, in the circuit pattern 20 formed using the copper clad laminate having a surface-treated copper foil according to an embodiment of the present invention, the surface treatment layer 3 in contact with the substrate 11 is not excessively eroded and removed compared to the copper foil 2, thereby suppressing the occurrence of undercuts.

[0017] 3 is a cross-sectional view showing an example of a state in which a circuit pattern is formed by etching the surface-treated copper foil of a copper-clad laminate having a conventional surface-treated copper foil, followed by soft etching. As shown in FIG. 3, in the circuit pattern 30 formed using a copper-clad laminate having a conventional surface-treated copper foil, the surface treatment layer 4 in contact with the substrate 11 is excessively eroded and removed compared to the copper foil 2, and undercuts 40 are likely to occur.

[0018] The surface treatment layer 3 used in the surface-treated copper foil 1 may be formed on only one side of the copper foil 2, or may be formed on both sides of the copper foil 2. When the surface treatment layer 3 is formed on both sides of the copper foil 2, the types of the surface treatment layers 3 may be the same or different.

[0019] The surface treatment layer 3 contains Ni, Zn, and Cr. The surface treatment layer 3 may further contain Co, but does not necessarily contain Co. Among the various elements contained in the surface treatment layer 3, in order to suppress the occurrence of undercut during soft etching, the Zn deposition amount is set to 100 to 500 μg / dm 2 , Cr deposition amount 70 to 150 μg / dm 2It is important to control the ratio of the Cr deposition weight to the total of the Ni deposition weight, Zn deposition weight, and Cr deposition weight (hereinafter abbreviated as "Cr ratio") to 18.0 to 50.0%. Furthermore, by controlling the Zn deposition weight within this range, it is possible to impart properties such as heat resistance and chemical resistance to the surface treatment layer 3, and by controlling the Cr deposition weight within this range, it is also possible to impart rust prevention effects. From the viewpoint of stably ensuring the effect of suppressing the occurrence of undercuts during soft etching, the Zn deposition weight is set to 151 to 394 μg / dm 2 It is preferable that the concentration is 151 to 331 μg / dm 2 From the same viewpoint, the Cr coating amount is more preferably 98 to 120 μg / dm 2 It is preferable that the concentration is 98 to 107 μg / dm 2 From the same viewpoint, the Cr content is preferably 20.0 to 40.0%, and more preferably 20.5 to 35.5%.

[0020] The amount of Ni attached in the surface treatment layer 3 is not particularly limited, but is preferably 10 to 100 μm / dm 2 It is preferable that the thickness is 27 to 72 μm / dm 2 By controlling the Ni deposition amount within this range, it is possible to enhance the effect of suppressing the occurrence of undercut during soft etching.

[0021] In the soft etching solution used for soft etching, Ni is a component that is difficult to dissolve, whereas Zn is a component that is easily soluble. Therefore, by controlling the balance between the Ni and Zn adhesion amounts in the surface treatment layer 3 within an appropriate range, the effect of suppressing the occurrence of undercuts during soft etching can be enhanced. From the viewpoint of achieving this effect, the ratio of the Ni adhesion amount to the total of the Ni adhesion amount and the Zn adhesion amount in the surface treatment layer 3 is preferably 10.0 to 20.0%, and more preferably 15.2 to 18.2%. From the same viewpoint, the total of the Ni adhesion amount and the Zn adhesion amount in the surface treatment layer 3 is preferably 100 μg / dm 2 500 μg / dm or more 2 It is preferable that the concentration is less than 178 to 466 μg / dm2 It is more preferable that the soft etching solution used for the soft etching is not particularly limited, and any solution known in the art can be used. A typical soft etching solution contains hydrogen peroxide and sulfuric acid as its main components.

[0022] When the surface treatment layer 3 contains Co, the Co deposition amount in the surface treatment layer 3 is 100 μg / dm 2 It is preferable that the concentration is 80 μg / dm or less. 2 It is more preferable that the Co coating amount is less than 0.1 μg / dm. By controlling the Co coating amount within this range, it is possible to ensure the effect of suppressing undercuts during soft etching. Furthermore, since Co is a magnetic metal, by controlling the Co coating amount within this range, it is possible to obtain a surface-treated copper foil 1 that can be used to fabricate printed wiring boards with excellent high-frequency characteristics. The lower limit of the Co coating amount is not particularly limited, but is typically 0.1 μg / dm. 2 , preferably 0.5 μg / dm 2 is.

[0023] The Zn deposition weight, Ni deposition weight, and Co deposition weight (if present) in the surface treatment layer 3 can be measured by dissolving the obtained surface-treated copper foil 1 in a nitric acid aqueous solution prepared by mixing nitric acid and water at a volume ratio of 1:2 and then performing ICP analysis. For the measurement, an inductively coupled plasma optical emission spectrometer (SPS3520UV, manufactured by Hitachi High-Tech Science Corporation) or an equivalent device can be used. For the measurement, the Cr deposition weight in the surface treatment layer 3 can be measured by boiling and dissolving the obtained surface-treated copper foil 1 in a hydrochloric acid aqueous solution prepared by mixing hydrochloric acid and water at a volume ratio of 1:4 and then performing quantitative analysis by atomic absorption spectrometry. For the measurement, an atomic absorption spectrophotometer (200 Series AA, manufactured by Agilent) or an equivalent device can be used.

[0024] The type of surface treatment layer 3 is not particularly limited as long as the amount of the predetermined element attached in the surface treatment layer 3 is controlled as described above, and layers formed by various surface treatments known in the art can be used. Examples of the surface treatment layer 3 include a roughening treatment layer, a chemical-resistant treatment layer, a heat-resistant treatment layer, a chromate treatment layer, and a silane coupling treatment layer. These layers can be used alone or in combination of two or more. Among these layers, it is preferable that the surface treatment layer 3 contains a roughening treatment layer to improve adhesion to the substrate 11 (especially a resin substrate). Herein, the term "roughening treatment layer" refers to a layer formed by a roughening treatment and containing roughening particles. In addition, in the roughening treatment, conventional copper plating or the like may be performed as a pretreatment, or conventional copper plating or the like may be performed as a finishing treatment to prevent the roughening particles from falling off. However, the term "roughening treatment layer" in this specification includes layers formed by these pretreatments and finishing treatments.

[0025] When the surface treatment layer 3 contains one or more layers selected from the group consisting of a chemical-resistant treatment layer, a heat-resistant treatment layer, a chromate treatment layer, and a silane coupling treatment layer, it is preferable that these layers are provided on the roughening treatment layer.

[0026] The roughening particles may be formed from, but are not limited to, any single element selected from the group consisting of copper, nickel, cobalt, phosphorus, tungsten, arsenic, molybdenum, chromium, and zinc, or an alloy containing at least one of these elements. The roughening particles may contain primary roughening particles and secondary roughening particles. The secondary roughening particles preferably have a different chemical composition from the primary roughening particles. The primary roughening particles may be formed from, for example, copper or a copper alloy, particularly copper. The secondary roughening particles may be formed from, for example, an alloy containing copper, cobalt, and nickel. A cover plating layer may be formed on at least a portion of the surface of the primary roughening particles. The cover plating layer may be formed from, but is not limited to, copper, silver, gold, nickel, cobalt, zinc, etc. Among these, the cover plating layer is preferably formed from copper.

[0027] The roughened layer can be formed, for example, by performing a primary roughening treatment to form primary roughening particles, followed by cover plating to form a cover plating layer, and then a secondary roughening treatment to form secondary roughening particles. By performing the roughening treatment in this manner, it becomes easier to form the surface treatment layer 3 having the above-mentioned characteristics.

[0028] The roughening particle layer can be formed by electroplating. The conditions for the roughening treatment are not particularly limited, but typical conditions are as follows. Electroplating may be performed once or in multiple steps. (Conditions for roughening treatment) Plating solution composition: 5 to 15 g / L of Cu, 40 to 100 g / L of sulfuric acid, 1 to 6 ppm of tungsten (derived from sodium tungstate dihydrate) Plating solution temperature: 20 to 50°C Electroplating conditions: current density 30 to 90 A / dm 2 , time 0.1 to 8 seconds (cover plating conditions) Plating solution composition: 10 to 30 g / L Cu, 70 to 130 g / L sulfuric acid Plating solution temperature: 30 to 60°C Electroplating conditions: current density 4.8 to 15 A / dm 2 , time 0.1 to 8 seconds

[0029] The chemical resistance treatment layer and the heat resistance treatment layer are not particularly limited and can be formed from materials known in the art. Because the chemical resistance treatment layer may also function as a heat resistance treatment layer, a single layer having both the functions of a chemical resistance treatment layer and a heat resistance treatment layer may be formed. The chemical resistance treatment layer and / or the heat resistance treatment layer may be a layer containing one or more elements (which may be in any form, such as metal, alloy, oxide, nitride, or sulfide) selected from the group consisting of nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, platinum group elements, iron, and tantalum. Among these, the chemical resistance treatment layer and the heat resistance treatment layer are preferably Ni—Zn layers.

[0030] The chemical-resistant treatment layer and the heat-resistant treatment layer can be formed by electroplating. The conditions for electroplating are not particularly limited. Typical conditions for chemical-resistant treatment and heat-resistant treatment using a general electroplating device are as follows. Note that each electroplating may be performed once or in multiple steps. (Conditions for forming the Ni-Zn layer) Plating solution composition: 1 to 30 g / L Ni, 1 to 30 g / L Zn Plating solution pH: 2 to 5 Plating solution temperature: 30 to 50°C Electroplating conditions: current density 0.1 to 10 A / dm 2 , time 0.1 to 5 seconds

[0031] The chromate-treated layer is not particularly limited and can be formed from materials known in the art. In this specification, the term "chromate-treated layer" refers to a layer formed from a solution containing chromic anhydride, chromic acid, dichromate, chromate salt, or dichromate salt. The chromate-treated layer can be a layer containing one or more elements (which may be in the form of metal, alloy, oxide, nitride, sulfide, etc.) selected from the group consisting of cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, and titanium. Examples of chromate-treated layers include chromate-treated layers treated with an aqueous solution of chromic anhydride or potassium dichromate, and chromate-treated layers treated with a treatment solution containing chromic anhydride or potassium dichromate and zinc.

[0032] The chromate treatment layer can be formed by a known method such as immersion chromate treatment or electrolytic chromate treatment. The conditions for the chromate treatment are not particularly limited. Typical conditions for general chromate treatment are as follows. The chromate treatment may be performed once or in multiple steps. Chromate solution composition: 1 to 10 g / L K2Cr2O7, 0.01 to 10 g / L Zn Chromate solution pH: 2 to 5 Chromate solution temperature: 30 to 55°C Electrolysis conditions: current density 0.1 to 10 A / dm 2 , time 0.1 to 5 seconds (in the case of electrolytic chromate treatment)

[0033] The silane coupling treatment layer is not particularly limited and can be formed from materials known in the art. In this specification, the term "silane coupling treatment layer" refers to a layer formed from a silane coupling agent. The silane coupling agent is not particularly limited and any known agent in the art can be used. Examples of silane coupling agents include amino-based silane coupling agents, epoxy-based silane coupling agents, mercapto-based silane coupling agents, methacryloxy-based silane coupling agents, vinyl-based silane coupling agents, imidazole-based silane coupling agents, and triazine-based silane coupling agents. Among these, amino-based silane coupling agents and epoxy-based silane coupling agents are preferred. Silane coupling agents may be used alone or in combination of two or more. A typical method for forming a silane coupling treatment layer includes applying a 1 to 3% by volume aqueous solution of the above-mentioned silane coupling agent and drying it to form a silane coupling treatment layer.

[0034] The copper foil 2 used in the surface-treated copper foil 1 is not particularly limited and may be either an electrolytic copper foil or a rolled copper foil. Electrolytic copper foil is produced, for example, by electrolytically depositing copper from a copper sulfate plating bath onto a drum made of titanium or stainless steel. Electrolytic copper foil has a flat S-side (shine side) formed on the drum side and an M-side (matte side) formed on the opposite side of the S-side.

[0035] The material of the copper foil 2 is not particularly limited. When the copper foil 2 is a rolled copper foil, high-purity copper such as tough pitch copper (JIS H3100 alloy number C1100) or oxygen-free copper (JIS H3100 alloy number C1020 or JIS H3510 alloy number C1011), which are commonly used for circuit patterns on printed wiring boards, can be used. Furthermore, copper alloys such as Sn-containing copper, Ag-containing copper, copper alloys containing Cr, Zr, or Mg, and Corson copper alloys containing Ni and Si can also be used. In this specification, the term "copper foil 2" is a concept that also includes copper alloy foils.

[0036] The thickness of the copper foil 2 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.

[0037] The surface-treated copper foil 1 comprising the copper foil 2 and the surface treatment layer 3 as described above can be produced in accordance with a method known in the art. The Ni deposition weight, Zn deposition weight, Cr deposition weight, and Co deposition weight (if present) in the surface treatment layer 3 can be controlled by adjusting the conditions for forming the surface treatment layer 3. Examples of the conditions for forming the surface treatment layer 3 include the magnitude of the current value, the surface treatment time, the concentration of each metal ion in the bath, the temperature and pH of the bath, etc.

[0038] As described above, the copper-clad laminate 10 according to the embodiment of the present invention includes a surface-treated copper foil 1 and a substrate 11 provided on the surface treatment layer 3 of the surface-treated copper foil 1. The copper-clad laminate 10 can be manufactured by bonding the substrate 11 to the surface treatment layer 3 of the surface-treated copper foil 1. The substrate 11 is not particularly limited and may be any known material in the art, but is preferably a resin substrate. Examples of resin substrates include substrates made of a paper substrate with a phenolic resin, a paper substrate with an epoxy resin, a synthetic fiber cloth substrate with an epoxy resin, a glass cloth / paper composite substrate with an epoxy resin, a glass cloth / glass nonwoven fabric composite substrate with an epoxy resin, a glass cloth substrate with an epoxy resin, a polyester film, a polyimide resin, a liquid crystal polymer, a fluororesin, or the like. Among these, a polyimide resin substrate is preferred.

[0039] The method for bonding the surface-treated copper foil 1 and the substrate 11 is not particularly limited and can be performed according to a method known in the art. For example, the surface-treated copper foil 1 and the substrate 11 may be laminated and thermocompression bonded. The copper-clad laminate 10 thus produced can be used to produce a printed wiring board.

[0040] The copper clad laminate 10 according to an embodiment of the present invention uses the above-mentioned surface-treated copper foil 1, and therefore can suppress the occurrence of undercuts when soft etching is performed after etching the surface-treated copper foil 1 to form the circuit pattern 20.

[0041] The method for manufacturing a printed wiring board according to an embodiment of the present invention involves etching the surface-treated copper foil 1 of the copper-clad laminate 10 to form a circuit pattern 20, followed by soft etching. The method for forming the circuit pattern 20 is not particularly limited, and known methods such as subtractive and semi-additive methods can be used. Among these, the subtractive method is preferred as the method for forming the circuit pattern 20.

[0042] When a printed wiring board is manufactured by the subtractive method, it is preferably carried out as follows. First, a resist is applied to the surface of the surface-treated copper foil 1 of the copper-clad laminate 10, and a predetermined resist pattern is formed by exposing and developing the resist. Next, the surface-treated copper foil 1 in the areas where the resist pattern is not formed (i.e., unnecessary areas) is removed by etching to form a circuit pattern 20. Finally, the resist pattern on the surface-treated copper foil 1 is removed, and soft etching is carried out. Note that the various conditions for this subtractive method are not particularly limited, and the method can be carried out in accordance with conditions known in the art.

[0043] The method for manufacturing a printed wiring board according to an embodiment of the present invention uses the above-mentioned copper-clad laminate 10, and therefore can form a circuit pattern 20 with reduced undercut, and the reliability of the circuit pattern 20 (e.g., the adhesion strength between the substrate 11 and the circuit pattern 20) is particularly good.

[0044] Hereinafter, the embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0045] Example 1 A rolled copper foil (HG foil manufactured by JX Nippon Mining & Metals Corporation) having a thickness of 12 μm was prepared. The surface of the copper foil was degreased and pickled, and then a roughening treatment layer, a heat-resistant and chemical-resistant treatment layer (Ni—Zn layer), a chromate treatment layer, and a silane coupling treatment layer were sequentially formed on one side as surface treatment layers to obtain a surface-treated copper foil. The conditions for forming each treatment layer were as follows:

[0046] (1) Roughened Layer <Conditions for Forming Roughening Particles> Plating solution composition: 12 g / L Cu, 50 g / L sulfuric acid, 5 ppm tungsten (derived from sodium tungstate dihydrate) Plating solution temperature: 27°C Number of plating treatments: 2 Electroplating conditions: Current density 49.8 A / dm 2 , time 0.81 seconds <Conditions for forming cover plating layer> Plating solution composition: 20 g / L Cu, 100 g / L sulfuric acid Plating solution temperature: 50°C Number of plating treatments: 2 times Electroplating conditions: current density 11.9 A / dm 2 , time 1.15 seconds

[0047] (2) Heat-resistant and chemical-resistant treatment layer <Conditions for forming Ni-Zn layer> Plating solution composition: 23.5 g / L Ni, 4.5 g / L Zn Plating solution pH: 3.6 Plating solution temperature: 40°C Electroplating conditions: current density 0.70 A / dm 2 , time 0.59 seconds Number of plating processes: 1

[0048] (3) Chromate Treatment Layer <Conditions for Forming Electrolytic Chromate Treatment Layer> Chromate solution composition: 3 g / L KCrO, 0.33 g / L Zn Chromate solution pH: 3.65 Chromate solution temperature: 55°C Electrolysis conditions: current density 1.9 A / dm 2 , time 0.59 seconds Number of chromate treatments: 2 times

[0049] (4) Silane Coupling Treatment Layer A 1.2% by volume aqueous solution of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane was applied and dried to form a silane coupling treatment layer.

[0050] (Example 2) In the formation conditions of the heat-resistant and chemical-resistant treatment layer (Ni—Zn layer), the electroplating conditions were a current density of 1.5 A / dm 2A surface-treated copper foil was obtained under the same conditions as in Example 1, except that the heating time was changed to 0.59 seconds.

[0051] (Example 3) In the formation conditions of the heat-resistant and chemical-resistant treatment layer (Ni—Zn layer), the electroplating conditions were a current density of 1.9 A / dm 2 A surface-treated copper foil was obtained under the same conditions as in Example 1, except that the heating time was changed to 0.59 seconds.

[0052] (Example 4) In the formation conditions of the heat-resistant and chemical-resistant treatment layer (Ni—Zn layer), the electroplating conditions were a current density of 2.2 A / dm 2 A surface-treated copper foil was obtained under the same conditions as in Example 1, except that the heating time was changed to 0.59 seconds.

[0053] (Comparative Example 1) (1) Roughened Layer <Conditions for Forming Roughening Particles> Plating solution composition: 11 g / L Cu, 50 g / L sulfuric acid Plating solution temperature: 27°C Number of plating treatments: 2 times Electroplating conditions: Current density 41.3 A / dm 2 , time 0.68 seconds <Conditions for forming cover plating layer> Plating solution composition: 20 g / L Cu, 100 g / L sulfuric acid Plating solution temperature: 50°C Number of plating treatments: 2 times Electroplating conditions: current density 8.2 A / dm 2 , time 0.77 seconds

[0054] (2) Heat-resistant and chemical-resistant treatment layer <Conditions for forming Ni-Zn layer> Plating solution composition: 23.5 g / L Ni, 4.5 g / L Zn Plating solution pH: 3.6 Plating solution temperature: 40°C Electroplating conditions: current density 3.42 A / dm 2 , Time 0.39 seconds Number of plating processes: 1

[0055] (3) Chromate Treatment Layer <Conditions for Forming Electrolytic Chromate Treatment Layer> Chromate solution composition: 3 g / L KCrO, 0.33 g / L Zn Chromate solution pH: 3.65 Chromate solution temperature: 55°C Electrolysis conditions: current density 2.7 A / dm 2 , time 0.39 seconds Number of chromate treatments: 2 times

[0056] (4) Silane Coupling Treatment Layer A 1.2% by volume aqueous solution of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane was applied and dried to form a silane coupling treatment layer.

[0057] The surface-treated copper foils obtained in Examples 1 to 4 and Comparative Example 1 were evaluated as follows. <Amount of each element in the surface-treated layer> The Zn and Ni deposition amounts in the surface-treated layer were measured by dissolving the obtained surface-treated copper foil in an aqueous nitric acid solution prepared by mixing nitric acid and water at a volume ratio of 1:2, followed by ICP analysis. For the measurement, an inductively coupled plasma optical emission spectrometer (SPS3520UV, manufactured by Hitachi High-Tech Science Corporation) was used. The Cr deposition amount in the surface-treated layer was measured by boiling and dissolving the obtained surface-treated copper foil in an aqueous hydrochloric acid solution prepared by mixing hydrochloric acid and water at a volume ratio of 1:4, followed by quantitative analysis by atomic absorption spectrometry. For the measurement, an atomic absorption spectrophotometer (200 Series AA, manufactured by Agilent) was used. The deposition amounts of Zn, Ni, and Cr were measured per unit area (dm ) of the respective surface-treated copper foils. 2 The results are expressed as the mass (μg) of Zn, Ni, and Cr attached per 1000 μm of Zn, Ni, and Cr. Based on the obtained elemental attachment masses, the ratio of the Ni attachment mass to the total of the Ni attachment mass and the Zn attachment mass (represented as the "Ni ratio"), and the ratio of the Cr attachment mass to the total of the Ni attachment mass, the Zn attachment mass, and the Cr attachment mass (represented as the "Cr ratio") were calculated.

[0058] <Undercut Width> After bonding the surface-treated copper foil to a 25 μm-thick polyimide film (Pixio (registered trademark) manufactured by Kaneka Corporation), the film was heated and pressed at 360°C for 30 minutes. This heating and pressing was performed at 2.5 kPa. Next, a circuit pattern was formed using an etching solution to a width of 200 μm. Next, this circuit pattern was soft-etched for 1 minute using a soft etching solution (Clean Etch CPE-750 manufactured by Mitsubishi Gas Chemical Company, Inc.) containing hydrogen peroxide and sulfuric acid as its main components. The undercut after soft etching was then observed with an optical microscope from the back side of the polyimide film. An example of an observation image of a circuit pattern in which undercuts occurred is shown in FIG. 4. Because the polyimide film is thin and transparent, it is possible to observe the undercut and measure the undercut widths W1 and W2 through the polyimide film. The undercut widths W1 and W2 were measured at three arbitrarily selected locations, and the average value was used as the undercut width result. The results of each of the above characteristic evaluations are shown in Table 1.

[0059]

[0060] As shown in Table 1, the surface treatment layer contains Ni, Zn, and Cr, and the Zn deposition amount in the surface treatment layer is 100 to 500 μg / dm 2 The Cr deposition amount is 70 to 150 μg / dm 2 The surface-treated copper foils of Examples 1 to 4, in which the Cr ratio was 18.0 to 50.0%, had smaller undercut widths than those of Comparative Example 1, in which the Cr deposition amount and Cr ratio of the surface treatment layer were outside the above ranges.

[0061] As can be seen from the above results, according to the embodiments of the present invention, it is possible to provide a surface-treated copper foil and a copper-clad laminate that can suppress the occurrence of undercuts when forming a circuit pattern by soft etching. Furthermore, according to the embodiments of the present invention, it is possible to provide a method for manufacturing a printed wiring board having a circuit pattern in which undercuts are suppressed.

[0062] Therefore, the present invention can be embodied as follows: [1] A copper foil having a surface treatment layer formed on at least one surface of the copper foil, the surface treatment layer containing Ni, Zn, and Cr, and the Zn coating amount in the surface treatment layer being 100 to 500 μg / dm 2 The Cr deposition amount is 70 to 150 μg / dm 2 and a ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 18.0 to 50.0%. [2] The surface treatment layer further contains Co, and in the surface treatment layer, the Co coating weight is 100 μg / dm 2 [3] The surface-treated copper foil according to [1], wherein the surface treatment layer does not contain Co. [4] The Zn coating amount is 151 to 394 μg / dm 2 [5] The surface-treated copper foil according to any one of [1] to [3], wherein the Zn coating amount is 151 to 331 μg / dm 2 [6] The surface-treated copper foil according to [4], wherein the Cr coating amount is 98 to 120 μg / dm 2 [7] The surface-treated copper foil according to any one of [1] to [5], wherein the Cr coating amount is 98 to 107 μg / dm 2 [8] The surface-treated copper foil according to [6], wherein the Ni deposition amount is 10 to 100 μg / dm 2 [9] The surface-treated copper foil according to any one of [1] to [7], wherein the Ni coating amount is 27 to 72 μg / dm 2

[10] The surface-treated copper foil according to any one of [1] to [9], wherein the ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 20.0 to 40.0%.

[11] The surface-treated copper foil according to

[10] , wherein the ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 20.5 to 35.5%.

[12] The surface-treated copper foil according to any one of [1] to

[11] , wherein the ratio of the Ni coating weight to the total of the Ni coating weight and the Zn coating weight is 10.0 to 20.0%.

[13] The surface-treated copper foil according to

[12] , wherein the ratio of the Ni coating weight to the total of the Ni coating weight and the Zn coating weight is 15.2 to 18.2%.

[14] The sum of the Ni coating weight and the Zn coating weight is 100 μg / dm 2 500 μg / dm or more 2

[15] The surface-treated copper foil according to any one of [1] to

[13] , wherein the total of the Ni coating weight and the Zn coating weight is 178 to 466 μg / dm 2

[16] The surface-treated copper foil according to any one of [1] to

[15] , wherein the surface treatment layer contains a roughening treatment layer.

[17] A copper-clad laminate comprising the surface-treated copper foil according to any one of [1] to

[16] and a substrate provided on the surface treatment layer of the surface-treated copper foil.

[18] A method for producing a printed wiring board, comprising etching the surface-treated copper foil of the copper-clad laminate according to

[17] to form a circuit pattern, and then soft-etching the surface-treated copper foil.

[0063] (Potential Contribution to SDGs) According to embodiments of the present invention, it is possible to provide a surface-treated copper foil and copper-clad laminate that can suppress the occurrence of undercut during soft etching, as well as a method for manufacturing a printed wiring board having a circuit pattern with suppressed undercut, which may improve product yield in the manufacture of electronic devices, etc. Improving product yield leads to a stable supply of products and reduced loss of metal raw materials, which are limited resources. Therefore, the above embodiments may contribute to Goal 9 "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation" and Goal 12 "Ensure sustainable consumption and production patterns" of the United Nations-led Sustainable Development Goals (SDGs).

[0064] REFERENCE SIGNS LIST 1 Surface-treated copper foil 2 Copper foil 3, 4 Surface-treated layer 10 Copper-clad laminate 11 Base material 20, 30 Circuit pattern 40 Undercut

Claims

1. A copper foil and a surface treatment layer formed on at least one surface of the copper foil, the surface treatment layer containing Ni, Zn and Cr, and the Zn coating amount in the surface treatment layer is 100 to 500 μg / dm 2 The Cr deposition amount is 70 to 150 μg / dm 2 and a ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 18.0 to 50.0%.

2. The surface treatment layer further contains Co, and the Co deposition amount in the surface treatment layer is 100 μg / dm 2 The surface-treated copper foil according to claim 1, wherein:

3. The surface-treated copper foil according to claim 1, wherein the surface treatment layer does not contain Co.

4. The amount of Zn attached is 151 to 394 μg / dm 2 The surface-treated copper foil according to any one of claims 1 to 3.

5. The amount of Zn attached is 151 to 331 μg / dm 2 The surface-treated copper foil according to claim 4 .

6. The amount of Cr attached is 98 to 120 μg / dm 2 The surface-treated copper foil according to any one of claims 1 to 5.

7. The amount of Cr attached is 98 to 107 μg / dm 2 The surface-treated copper foil according to claim 6 .

8. The amount of Ni attached is 10 to 100 μg / dm 2 The surface-treated copper foil according to any one of claims 1 to 7.

9. The amount of Ni attached is 27 to 72 μg / dm 2 The surface-treated copper foil according to claim 8 .

10. A surface-treated copper foil according to any one of claims 1 to 9, wherein the ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 20.0 to 40.0%.

11. The surface-treated copper foil according to claim 10, wherein the ratio of the Cr coating weight to the total of the Ni coating weight, the Zn coating weight, and the Cr coating weight is 20.5 to 35.5%.

12. The surface-treated copper foil according to any one of claims 1 to 11, wherein the ratio of the Ni deposition weight to the total of the Ni deposition weight and the Zn deposition weight is 10.0 to 20.0%.

13. The surface-treated copper foil according to claim 12, wherein the ratio of the Ni deposition weight to the total of the Ni deposition weight and the Zn deposition weight is 15.2 to 18.2%.

14. The total of the Ni deposition amount and the Zn deposition amount is 100 μg / dm 2 500 μg / dm or more 2 The surface-treated copper foil according to any one of claims 1 to 13, wherein the surface-treated copper foil has a viscosity of less than 1000 MPa.

15. The total of the Ni deposition amount and the Zn deposition amount is 178 to 466 μg / dm 2 The surface-treated copper foil according to claim 14 .

16. The surface-treated copper foil according to any one of claims 1 to 15, wherein the surface treatment layer includes a roughening treatment layer.

17. A copper-clad laminate comprising the surface-treated copper foil according to any one of claims 1 to 16 and a substrate provided on the surface treatment layer of the surface-treated copper foil.

18. A method for producing a printed wiring board, comprising etching the surface-treated copper foil of the copper-clad laminate according to claim 17 to form a circuit pattern, and then soft etching the same.

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