Surface-treated copper foil and copper-clad laminate

Abstract

Provided is a surface-treated copper foil comprising a copper foil and a surface-treated layer provided on at least one surface of the copper foil. The surface-treated layer contains Zn, and the adhesion amount of Zn is 300-1000 μg / dm2. The semi-softening temperature of the surface-treated copper foil is 145°C or less.

Description

Surface-treated copper foil and copper-clad laminates

[0001] This disclosure relates to surface-treated copper foil and copper-clad laminates.

[0002] Copper-clad laminates consist of copper foil and a resin layer on the surface of the copper foil, and are widely used in various applications such as flexible printed circuit boards. Flexible printed circuit boards are manufactured by chemically etching the copper foil of a copper-clad laminate to form circuits (also called "conductor patterns"), and then soldering electronic components onto these circuits.

[0003] In recent years, flexible printed circuit boards have been used not only in electronic devices such as personal computers and mobile terminals, but also in automotive equipment.

[0004] Japanese Patent Publication No. 2012-112009

[0005] Flexible printed circuit boards used in automotive equipment tend to get hot due to the high currents that flow through them. Conventional surface-treated copper foils, when exposed to high temperatures, experience a decrease in adhesion between the resin layer and the circuit (copper foil), making it easy for the circuit to peel off the resin layer.

[0006] 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 has excellent adhesion to a resin layer and can suppress a decrease in adhesion to the resin layer even when exposed to high temperatures for a long time. Furthermore, embodiments of the present invention also aim to provide a copper-clad laminate that has excellent adhesion to a resin layer and can suppress a decrease in adhesion to the resin layer even when exposed to high temperatures for a long time.

[0007] The inventors of the present invention conducted intensive research on surface-treated copper foil in order to solve the above problems. As a result, they discovered that by providing a surface treatment layer containing a predetermined amount of Zn on at least one surface of the copper foil, and controlling the semi-softening temperature of the surface-treated copper foil to a predetermined temperature, the adhesion to the resin layer is improved, and the adhesion to the resin layer does not deteriorate easily even when exposed to high temperatures for a long time. This led to the completion of the embodiments of the present invention.

[0008] In other words, an embodiment of the present invention is a surface-treated copper foil comprising a copper foil and a surface treatment layer provided on at least one surface of the copper foil, wherein the surface treatment layer contains Zn, and the amount of Zn deposited in the surface treatment layer is 300 to 1000 μg / dm 2 The present invention relates to a surface-treated copper foil in which the semi-softening temperature of the surface-treated copper foil is 145°C or lower.

[0009] Furthermore, embodiments of the present invention relate to a copper-clad laminate comprising a surface-treated copper foil and a resin layer provided on the surface of the surface-treated layer of the surface-treated copper foil.

[0010] According to embodiments of the present invention, in one respect, it is possible to provide a surface-treated copper foil that has excellent adhesion to a resin layer and can suppress a decrease in adhesion to the resin layer even when exposed to high temperatures for a long time. Furthermore, according to embodiments of the present invention, in another respect, it is possible to provide a copper-clad laminate that has excellent adhesion to a resin layer and can suppress a decrease in adhesion to the resin layer even when exposed to high temperatures for a long time.

[0011] Preferred embodiments of the present invention will be described 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 spirit of the invention. The multiple components disclosed in the following embodiments can be combined in appropriate ways to form various inventions. For example, some components may be removed from all the components shown in the following embodiments, or components from different embodiments may be combined in appropriate ways.

[0012] In this specification, a numerical range expressed using "~" means a range that includes the numbers before and after "~" as the lower and upper limits, unless otherwise specified. Also, in this specification, a numerical range that includes "greater than" or "less than" means a range that does not include the number as the lower or upper limit. For numerical ranges described in steps in this specification, the upper limit of one step may be replaced with the upper limit of another step described numerical range or the value shown in the example. Also, for numerical ranges described in steps in this specification, the lower limit of one step may be replaced with the lower limit of another step described numerical range or the value shown in the example.

[0013] The surface-treated copper foil according to an embodiment of the present invention comprises a copper foil and a surface treatment layer provided on at least one surface of the copper foil. The surface treatment layer contains Zn, and the amount of Zn deposited in the surface treatment layer is 300 to 1000 μg / dm 2 Furthermore, the semi-softening temperature of the surface-treated copper foil is 145°C or lower. By having such a configuration, the surface-treated copper foil according to the embodiment of the present invention has excellent adhesion to the resin layer, and even when exposed to high temperatures for a long period of time (for example, 100 to 225°C for 50 to 500 hours), a decrease in adhesion to the resin layer can be suppressed.

[0014] The surface treatment layer may be provided on only one surface of the copper foil, or it may be formed on both surfaces of the copper foil. If the surface treatment layer is formed on both surfaces of the copper foil, the types of surface treatment layers may be the same or different. If the surface treatment layer is formed on both surfaces of the copper foil, only one surface treatment layer may satisfy the above conditions, or both surface treatment layers may satisfy the above conditions.

[0015] Surface-treated copper foil exhibits improved heat resistance due to the inclusion of Zn in the surface treatment layer. Therefore, even when exposed to high temperatures for extended periods, the adhesion to the resin layer is less likely to deteriorate. To ensure this effect, the amount of Zn adhering to the surface treatment layer should be 300 to 1000 μg / dm². 2 Preferably 400 to 950 μg / dm 2 , more preferably 489 to 935 μg / dm 2More preferably 688 to 935 μg / dm 2 That is the case.

[0016] Because the semi-softening temperature of the surface-treated copper foil is low, the copper foil can recrystallize even at relatively low temperatures. Therefore, even when a copper-clad laminate is manufactured by laminating it with a resin that has a relatively low processing temperature (for example, PEN resin), the flexibility required for flexible printed circuit boards can be achieved. From the viewpoint of ensuring this effect, the semi-softening temperature of the surface-treated copper foil is 145°C or lower, preferably 80 to 140°C, more preferably 100 to 135°C, and even more preferably 110 to 126°C. To lower the semi-softening temperature of the surface-treated copper foil, for example, copper foil having a low semi-softening temperature can be used. As copper foil having a low semi-softening temperature, copper foil with few impurities and added elements can be used. Rolled copper foil can also be used as copper foil having a low semi-softening temperature. In the manufacturing process of rolled copper foil, the semi-softening temperature of the rolled copper foil can be reduced by performing recrystallization annealing at a relatively low temperature before the final cold rolling, or by not performing recrystallization annealing.

[0017] Here, the half-softening temperature of the surface-treated copper foil is measured by the following method. A sample for evaluation is prepared from the surface-treated copper foil in accordance with IPC-TM-650 (2.4.18, Revision B) using a precision cutter so that the sample has a width of 12.7 mm and a length of 100 mm. Herein, the width direction is the transverse direction, and the length direction is the longitudinal direction. For example, when the surface-treated copper foil comprises a rolled copper foil, the rolling direction of the rolled copper foil (i.e., the MD direction) is set to be the longitudinal direction. Next, after the sample for evaluation is subjected to convection heating in the atmosphere at a predetermined temperature for 30 minutes, the sample is allowed to cool, and a tensile test is performed immediately after the temperature returns to room temperature to determine the tensile strength. The predetermined temperatures are 100°C, 120°C, 140°C, 160°C, 180°C, and 200°C. A tensile test is also performed on an unheated sample for evaluation to determine the tensile strength. For the tensile test, a precision universal testing machine (AGS-X series) manufactured by Shimadzu Corporation or an equivalent apparatus is used. The gauge length between the pneumatic flat grips is set to 50.8 mm, and adjustment is performed so that the central axes and orientations of the upper and lower pneumatic flat grips are aligned. Five evaluation samples are prepared for each temperature, measurement is performed on each, and the average value is taken as the measurement value. If a sample breaks within the grip, re-measurement is performed. Further, the half-softening temperature is calculated using the following formula, and the result is rounded to the nearest integer. The surface-treated copper foil is completely softened by heating at 200°C for 30 minutes.

[0018]

[0019] In the above formula, Px is the average tensile strength (MPa) of the unheated sample for evaluation and the sample for evaluation heated at 200°C. After calculating Px, among the measurement points consisting of heating temperature and tensile strength, among two consecutive measurement points that do not have any other measurement point interposed therebetween with respect to heating temperature, a two-point set is selected in which the tensile strength of one measurement point is higher than Px and the tensile strength of the other measurement point is lower than Px. Provided that any measurement point that coincides with Px is deemed not to exist.  P1: Tensile strength value (MPa) of data with tensile strength higher than Px among the two selected points  P2: Tensile strength value (MPa) of data with tensile strength lower than Px among the two selected points  T1: Temperature (°C) at which the result for P1 is obtained  T2: Temperature (°C) at which the result for P2 is obtained

[0020] The surface treatment layer may further contain Ni. When the surface treatment layer contains Ni, the adhesiveness with the resin layer can be stably improved. In addition, the chemical resistance and heat resistance of the surface-treated copper foil are also improved. From the viewpoint of ensuring these effects, the adhered amount of Ni in the surface treatment layer is preferably 700 to 1500 μg / dm 2 , more preferably 800 to 1400 μg / dm 2 , still more preferably 900 to 1300 μg / dm 2 , and particularly preferably 999 to 1262 μg / dm 2 .

[0021] The surface treatment layer may further contain Co. When the surface treatment layer contains Co, the adhesiveness with the resin layer can be stably improved. In addition, the chemical resistance and heat resistance of the surface-treated copper foil are also improved. From the viewpoint of ensuring these effects, the adhered amount of Co in the surface treatment layer is preferably 1800 to 2200 μg / dm 2 , more preferably 1850 to 2100 μg / dm 2 , still more preferably 1900 to 2050 μg / dm 2 , and particularly preferably 1935 to 1998 μg / dm 2 .

[0022] The surface treatment layer may further contain Cr. When the surface treatment layer contains Cr, the adhesiveness with the resin layer can be stably improved. From the viewpoint of ensuring this effect, the adhered amount of Cr in the surface treatment layer is preferably 10 to 100 μg / dm 2 , more preferably 30 to 90 μg / dm 2 , still more preferably 50 to 80 μg / dm 2 , and particularly preferably 63 to 69 μg / dm 2 .

[0023] In the surface treatment layer, a ratio R of the adhered amount of Zn to the total adhered amount of Ni, Zn, Co and Cr Zn is preferably 0.110 to 0.250, more preferably 0.120 to 0.240, still more preferably 0.130 to 0.230, and still more preferably 0.138 to 0.223. When the ratio R is within such a range ZnBy controlling this, the adhesion to the resin layer can be stably improved.

[0024] The amount of each of the above elements (excluding Cr) deposited in the surface treatment layer can be measured by dissolving the surface-treated copper foil in an aqueous nitric acid solution prepared by mixing nitric acid and water in a volume ratio of 1:2, and performing ICP analysis. For measurement, an inductively coupled plasma emission spectrometer (Hitachi High-Tech Science Corporation, SPS3520UV) or an equivalent device can be used. The amount of Cr deposited in the surface treatment layer can be measured by boiling and dissolving the obtained surface-treated copper foil in an aqueous hydrochloric acid solution prepared by mixing hydrochloric acid and water in a volume ratio of 1:4, and performing quantitative analysis by atomic absorption spectrometry. For measurement, an atomic absorption spectrophotometer (Agilent, 200 Series AA) or an equivalent device can be used.

[0025] The surface treatment layer has an expanded interface area ratio Sdr preferably of 5.0 to 25.0%, more preferably of 10.0 to 20.0%. By controlling the expanded interface area ratio Sdr within this range, the adhesion to the resin layer can be stably improved. The expanded interface area ratio Sdr is a composite parameter defined in ISO 25178-2:2012 and represents the increase in surface area. In other words, it represents the increase in the actual surface area relative to the area when the surface of the surface treatment layer is viewed from above. Therefore, the expanded interface area ratio Sdr tends to be high when the surface of the surface treatment layer has many irregularities, and low when the surface of the surface treatment layer has few irregularities. The expanded interface area ratio Sdr of the surface treatment layer can be measured in accordance with ISO 25178-2:2012. Specifically, the expanded interface area ratio Sdr of the surface treatment layer can be measured under the following conditions.

[0026] Images of the surface of the surface-treated layer will be captured using an Olympus Corporation laser microscope (LEXT OLS5100). The captured images will be analyzed using the analysis software for the Olympus Corporation laser microscope (LEXT OLS5100). The Sdr of the unfolded interface area ratio of the surface-treated layer will be measured in accordance with ISO 25178-2:2012. The measurement result will be the average value of the values ​​measured at 10 arbitrary locations. The temperature during measurement will be 23 to 25°C. The main settings for the laser microscope and analysis software will be as follows. If the device operation software or data analysis software is updated, the software will be operated and set to be equivalent to the conditions described in this specification. • System name: OLS5100-SAF • Objective lens: MPLAPON50xLEXT (magnification 50x, numerical aperture 0.95, working distance 0.35mm, depth of field 0.44μm, focusing spot diameter 0.52μm) • Optical zoom magnification: 1x • Scanning mode: 3D accuracy priority + color • Image size: 257μm x 256μm, 1024 x 1024 pixels • Laser intensity: 100 • Offset: 0 • Confocal level: 0 • Beam diameter aperture: Off • Brightness uniformity correction: On • Optical noise filter: On • Cutoff: No filter, no F calculation • Filter: Gaussian • Auto gain: On • Brightness: Automatic adjustment • Noise reduction: Yes • Tilt correction: Yes Brightness: Adjust to be in the range of 30 to 50. The brightness should be set appropriately depending on the color tone of the object being measured.

[0027] The surface treatment layer may contain one or more layers selected from a roughening treatment layer, a chemical-resistant treatment layer, a heat-resistant treatment layer, a chromate treatment layer, and a silane coupling treatment layer. Of these, the surface treatment layer is preferably a roughening treatment layer from the viewpoint of adhesion to the resin layer. When the surface treatment layer contains one or more layers selected from a chemical-resistant treatment layer, a heat-resistant treatment layer, a chromate treatment layer, and a silane coupling treatment layer, these layers are preferably provided on top of the roughening treatment layer.

[0028] The roughened layer contains roughened particles. The roughened particles may include primary and secondary roughened particles. The secondary roughened particles may have a different chemical composition from the primary roughened particles. Preferably, an overlay plating layer is formed on at least a portion of the surface of the primary roughened particles.

[0029] The roughened particles are not particularly limited, but can be formed from a single element selected from the group consisting of Cu, Ni, Co, P, W, As, Mo, Cr, and Zn, or from an alloy containing two or more of these elements. The primary roughened particles are preferably formed from Cu or a Cu alloy, particularly Cu. The secondary roughened particles are preferably formed from an alloy containing Cu, Co, and Ni. The overlay plating layer is not particularly limited, but can be formed from Cu, Ag, Au, Ni, Co, Zn, etc. Among these, the overlay plating layer is preferably formed from Cu.

[0030] The roughened layer can be formed, for example, by performing a primary roughening treatment to form primary roughened particles, followed by overlay plating to form an overlay plating layer, and then a secondary roughening treatment to form secondary roughened particles. Each particle and layer can be formed by electroplating. Specifically, the primary roughened particles, the overlay plating layer, and the secondary roughened particles can be formed by electroplating using a plating solution containing predetermined components.

[0031] The electroplating conditions for forming the roughened layer are not particularly limited and can be adjusted according to the electroplating equipment used, but typical conditions are as follows. Each electroplating step may be performed once or multiple times.

[0032] (Conditions for the formation of roughened particles) Plating solution composition: 10-20 g / L Cu, 1-10 g / L Co, 1-15 g / L Ni Plating solution pH: 1-4 Plating solution temperature: 30-50°C Electroplating conditions: Current density 20-50 A / dm 2 , time 0.3 to 2 seconds

[0033] The chemical-resistant layer and the heat-resistant layer are not particularly limited and can be formed from materials known in the art. Since the chemical-resistant layer may also function as a heat-resistant layer, a single layer having both chemical-resistant and heat-resistant functions may be formed as the chemical-resistant layer and / or heat-resistant layer. The chemical-resistant layer and / or heat-resistant layer may be a layer containing one or more elements selected from the group consisting of Ni, Zn, Sn, Co, Mo, Cu, W, P, As, Cr, V, Ti, Al, Au, Ag, Pt, Fe, and Ta (which may be in any form such as metal, alloy, oxide, nitride, or sulfide). Among these, the chemical-resistant layer and / or heat-resistant layer are preferably Co-Ni layers and Zn-Ni layers. A Co-Ni layer refers to a layer made of Co and Ni, and a Zn-Ni layer refers to a layer made of Zn and Ni.

[0034] Chemical-resistant and heat-resistant layers can be formed by electroplating. The conditions are not particularly limited and can be adjusted according to the electroplating equipment used, but the conditions for forming the Co-Ni layer and Zn-Ni layer using a general electroplating equipment are as follows.

[0035] (Conditions for forming the Co-Ni layer) Plating solution composition: 1-8 g / L of Co, 5-20 g / L of Ni Plating solution pH: 2-4 Plating solution temperature: 40-60°C Electroplating conditions: Current density 1-30 A / dm 2 , time 0.1 to 1 second

[0036] (Conditions for forming the Zn-Ni layer) Plating solution composition: 1-30 g / L of Zn, 5-40 g / L of Ni Plating solution pH: 2-5 Plating solution temperature: 30-50°C Electroplating conditions: Current density 3.7-10 A / dm 2 Time: 0.1 to 3 seconds, Number of electroplating processes: 1. Alternatively, set the current density to 3.5 A / dm 2 The size can be made even smaller, and the electroplating process can be performed multiple times.

[0037] The chromate-treated layer is not particularly limited and can be formed from materials known in the art. Hereinafter, "chromate-treated layer" means a layer formed with chromic anhydride, chromic acid, dichromate, chromate, or a solution containing a dichromate. The chromate-treated layer may be a layer containing one or more elements selected from the group consisting of Co, Fe, Ni, Mo, Zn, Ta, Cu, Al, P, W, Sn, As, and Ti (which may be in any form such as metal, alloy, oxide, nitride, or sulfide). Examples of chromate-treated layers include a chromate-treated layer treated with an aqueous solution of chromic anhydride or potassium dichromate, and a chromate-treated layer treated with a treatment solution containing chromic anhydride or potassium dichromate and zinc.

[0038] The chromate-treated layer can be formed by known methods such as immersion chromate treatment and electrolytic chromate treatment. While the conditions are not particularly limited, the following are typical conditions for forming a general chromate-treated layer. Note that the chromate treatment may be performed once or multiple times. Chromate solution composition: 1-10 g / L of K2Cr2O7, 0.01-10 g / L of Zn. Chromate solution pH: 2-5. Chromate solution temperature: 30-55°C. Electrolytic conditions: Current density 0.1-10 A / dm². 2 Time: 0.1 to 5 seconds (in the case of electrolytic chromate treatment)

[0039] The silane coupling treatment layer is not particularly limited and can be formed from materials known in the art. Here, in this specification, "silane coupling treatment layer" means a layer formed with a silane coupling agent. The silane coupling agent is not particularly limited and can be any known in the art. Examples of silane coupling agents include amino silane coupling agents, epoxy silane coupling agents, mercapto silane coupling agents, methacryloxy silane coupling agents, vinyl silane coupling agents, imidazole silane coupling agents, and triazine silane coupling agents. Among these, amino silane coupling agents and epoxy silane coupling agents are preferred. The above silane coupling agents can be used alone or in combination of two or more. A typical method for forming a silane coupling treatment layer is to apply a 1 to 3 volume percent aqueous solution of the above silane coupling agent and dry it to form the silane coupling treatment layer.

[0040] The copper foil is not particularly limited and may be either electrolytic copper foil or rolled copper foil. Electrolytic copper foil is generally manufactured by electrolytically elastorating copper from a copper sulfate plating bath onto a titanium or stainless steel drum, and has a flat S-surface (shine surface) formed on the rotating drum side and an M-surface (matte surface) formed on the opposite side of the S-surface. The M-surface of the electrolytic copper foil generally has minute irregularities. The S-surface of the electrolytic copper foil also has minute irregularities because polishing marks from the rotating drum formed during polishing are transferred to it. The chromate layer may be provided on either the S-surface or the M-surface of the electrolytic copper foil.

[0041] While there are no particular limitations on the material of the copper foil, if the copper foil is 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 as circuit patterns for printed circuit boards, can be used. In addition, copper alloys such as Sn-containing copper, Ag-containing copper, copper alloys with added Cr, Zr, or Mg, or Corson-type copper alloys with added Ni and Si can also be used. In this specification, "copper foil" is a concept that also includes copper alloy foils.

[0042] The thickness of the copper foil is not particularly limited, but from the viewpoint of suppressing heat generation, it is preferably 1 to 1000 μm, more preferably 18 to 150 μm, and even more preferably 35 to 150 μm. Furthermore, the thickness of the surface-treated copper foil is not particularly limited, but from the viewpoint of improving heat resistance, it is preferably 1 to 1000 μm, more preferably 18 to 150 μm, and even more preferably 35 to 150 μm.

[0043] A copper-clad laminate according to an embodiment of the present invention comprises the above-mentioned surface-treated copper foil and a resin layer provided on the surface of the surface-treated layer of the surface-treated copper foil. This copper-clad laminate can be manufactured by bonding a resin substrate, which will be the resin layer, to the surface-treated layer of the above-mentioned surface-treated copper foil. 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, fluororesin such as PTFE, polyolefin resin, PEN resin, and the like.

[0044] The resin layer is preferably made of a resin having a melting point of 320°C or lower. Using a resin with such a melting point allows the resin layer to be formed at a relatively low temperature, thus reducing the manufacturing cost of the copper-clad laminate. Examples of resins with such melting points include PEN resin and polyimide resin.

[0045] The method for bonding the surface-treated copper foil to 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 this manner can be used in the manufacture of printed circuit boards. The copper-clad laminate according to the embodiment of the present invention has excellent adhesion to the resin layer because it uses the surface-treated copper foil described above.

[0046] A copper-clad laminate according to an embodiment of the present invention can be made into a printed circuit board by chemically etching the surface-treated copper foil of the copper-clad laminate to form circuits. The method for forming the circuits 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 circuits.

[0047] When manufacturing printed circuit boards by the subtractive method, it is preferable to do so 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 (i.e., unwanted areas) is removed by chemical etching to form a circuit. Finally, the resist pattern on the surface-treated copper foil is removed. The various conditions in this subtractive method are not particularly limited and can be carried out in accordance with conditions known in the art. Since the printed circuit board obtained in this way uses the above-mentioned copper-clad laminate, it has excellent adhesion to the resin layer and can suppress the deterioration of adhesion between the resin layer and the circuit even when exposed to high temperatures for a long time.

[0048] 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.

[0049] (Example 1) A rolled copper foil with a thickness of 70 μm (HA-V2 foil manufactured by JX Metals Corporation) was prepared. After electrolytically degreasing one surface of the copper foil, a surface-treated copper foil (thickness 70 μm) was obtained by sequentially forming a roughening treatment layer, a heat-resistant treatment layer (Co-Ni layer), a heat-resistant treatment layer (Zn-Ni layer), an immersion chromate treatment layer, and a silane coupling treatment layer as surface treatment layers on the electrolytically degreased surface. The formation conditions for each treatment layer were as follows.

[0050] <Conditions for the formation of roughened particles> Plating solution composition: 15.5 g / L Cu, 7.5 g / L Co, 9.5 g / L Ni Plating solution temperature: 50°C Electroplating conditions 1: Current density 30-31 A / dm 2 Time 0.45 seconds, number of electroplating treatments under these conditions: 2. Electroplating condition 2: Current density 43-44 A / dm 2 Time: 0.30 seconds, Number of electroplating treatments under these conditions: 2 (Electroplating treatment was performed twice under electroplating condition 1, followed by two more electroplating treatments under electroplating condition 2.)

[0051] (2) Heat-resistant treatment layer <Conditions for forming the Co-Ni layer> Plating solution composition: 3 g / L Co, 13 g / L Ni Plating solution pH: 2 Plating solution temperature: 50°C Electroplating conditions 1: Current density 10-11 A / dm 2 Time 0.21 seconds, number of electroplating treatments under these conditions: 1. Electroplating condition 2: Current density 22-23 A / dm 2 Time: 0.21 seconds, Number of electroplating treatments under these conditions: 1 (Electroplating treatment was performed once under electroplating condition 1, followed by one electroplating treatment under electroplating condition 2.)

[0052] <Conditions for Forming the Zn-Ni Layer> Plating solution composition: 4.5 g / L Zn, 23.5 g / L Ni Plating solution pH: 3.65 Plating solution temperature: 40°C Electroplating conditions: Current density 3.2 A / dm 2 Time: 0.4 seconds, Number of electroplating treatments: 2

[0053] <Conditions for forming the chromate-treated layer> Chromate solution composition: 3 g / L K2Cr2O7, 0.33 g / L Zn Chromate solution pH: 3.65 Chromate solution temperature: 55°C

[0054] <Silane Coupling Treatment Layer> A silane coupling treatment layer was formed by applying a 1.2 vol% aqueous solution of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and drying it.

[0055] (Example 2) Current density of 3.7 A / dm² for the formation of the Zn-Ni layer 2 Except for the change made, a surface-treated copper foil (thickness 70 μm) was obtained under the same conditions as in Example 1.

[0056] (Example 3) Conditions for forming the Zn-Ni layer: current density 4.1 A / dm 2 Except for the change made, a surface-treated copper foil (thickness 70 μm) was obtained under the same conditions as in Example 1.

[0057] (Example 4) Formation conditions for the Zn-Ni layer: current density 4.6 A / dm 2 Except for the change made, a surface-treated copper foil (thickness 70 μm) was obtained under the same conditions as in Example 1.

[0058] (Example 5) Conditions for forming the Zn-Ni layer: current density 5.1 A / dm 2 Except for the change made, a surface-treated copper foil (thickness 70 μm) was obtained under the same conditions as in Example 1.

[0059] (Example 6) Formation conditions for the Zn-Ni layer: current density 5.5 A / dm 2 Except for the change made, a surface-treated copper foil (thickness 70 μm) was obtained under the same conditions as in Example 1.

[0060] (Example 7) Conditions for forming the Zn-Ni layer: current density 6.0 A / dm 2 Except for the change made, a surface-treated copper foil (thickness 70 m) was obtained under the same conditions as in Example 1.

[0061] (Comparative Example 1) Conditions for forming the Zn-Ni layer: current density 3.5 A / dm 2 Except for changing the number of electroplating treatments to one, a surface-treated copper foil (thickness 70 μm) was obtained under the same conditions as in Example 1.

[0062] (Comparative Example 2) A rolled copper foil with a thickness of 12 μm (HA-V2 foil manufactured by JX Metals Corporation) was used, and the formation conditions for the Zn-Ni layer were set to a current density of 3.5 A / dm 2Except for changing the number of electroplating treatments to one, a surface-treated copper foil (thickness 12 μm) was obtained under the same conditions as in Example 1.

[0063] (Comparative Example 3) A surface-treated copper foil (12 μm thick) was obtained under the same conditions as in Example 2, except that a rolled copper foil (HA-V2 foil manufactured by JX Metals Corporation) with a thickness of 12 μm was used.

[0064] (Comparative Example 4) A surface-treated copper foil (12 μm thick) was obtained under the same conditions as in Example 5, except that a rolled copper foil (HA-V2 foil manufactured by JX Metals Corporation) with a thickness of 12 μm was used.

[0065] The surface-treated copper foils obtained in the above examples and comparative examples were evaluated as follows.

[0066] <Half-softening temperature of surface-treated copper foil> The half-softening temperature of surface-treated copper foil was measured by the method described above. Specifically, it was carried out as follows: First, an evaluation sample was prepared using a precision cutter to have a width of 12.7 mm and a length of 100 mm, in accordance with IPC-TM-650 (2.4.18, Revision B). At this time, the rolling direction of the rolled copper foil (i.e., the MD direction) was aligned with the longitudinal direction. Next, to prevent oxidation, a 33 μm thick copper foil was folded and wrapped around the evaluation sample, and then convection heating was performed in a heating furnace in an atmospheric environment at a predetermined temperature for 30 minutes. After cooling to room temperature, a tensile test was immediately performed to determine the tensile strength. The predetermined temperatures were 100°C, 120°C, 140°C, 160°C, 180°C, and 200°C. Tensile tests were also performed on evaluation samples that had not been heated, and the tensile strength was determined. A precision universal testing machine (AGS-X series) manufactured by Shimadzu Corporation was used for the tensile tests. The gauge length between the pneumatic flat grips was set to 50.8 mm, and the central axes and orientations of the upper and lower pneumatic flat grips were adjusted to be in a straight line. Five evaluation samples were prepared at each temperature and measured, and the average value was used as the measurement value. If a sample fractured within the grip, it was measured again. The semi-softening temperature was then calculated using the formula described above. The surface-treated copper foil heated at 200°C for 30 minutes was completely softened.

[0067] <Evaluation of Ni, Zn, Co, and Cr deposition amounts in the surface treatment layer> The deposition amounts of Ni, Zn, and Co were measured by dissolving the obtained surface-treated copper foil in a nitric acid aqueous solution prepared by mixing nitric acid and water in a volume ratio of 1:2, and then performing ICP analysis. An inductively coupled plasma emission spectrometer (Hitachi High-Tech Science Corporation, SPS3520UV) was used for the measurement. The deposition amount of Cr in the surface treatment layer was measured by boiling and dissolving the obtained surface-treated copper foil in a hydrochloric acid aqueous solution prepared by mixing hydrochloric acid and water in a volume ratio of 1:4, and then performing quantitative analysis by atomic absorption spectrometry. An atomic absorption spectrophotometer (Agilent, 200 Series AA) was used for the measurement. The deposition amounts of each element described above were measured per unit area (dm²) of the respective surface-treated copper foil. 2 The amount of each element attached per unit area is expressed as the attached mass (μg). Furthermore, based on the obtained results for the attached amounts of each element, the ratio of the attached amount of Zn to the total attached amounts of Ni, Zn, Co, and Cr is R. Zn (Hereafter referred to as "Ratio R") Zn The following was calculated (sometimes abbreviated as ""):

[0068] <Evaluation of the Sdr ratio of the unfolded interface area of ​​the surface treatment layer> Images were captured using a laser microscope (LEXT OLS4000) manufactured by Olympus Corporation. The captured images were analyzed using analysis software for a laser microscope (LEXT OLS4100) manufactured by Olympus Corporation. Sdr measurements were performed in accordance with ISO 25178-2:2012. The measurement results were calculated by taking the average of values ​​measured at three arbitrary locations. The temperature during measurement was 23-25°C. The settings for the laser microscope and analysis software were as described above.

[0069] <Fabrication of Copper-Clad Laminates and Evaluation of Peel Strength> Using polyimide (PIXIO®, manufactured by Kaneka Corporation) as the resin substrate, copper-clad laminates were fabricated by laminating the surface-treated copper foil obtained in the above examples and comparative examples in the order of polyimide, and then performing vacuum hot pressing. At this time, the surface-treated layer side of the surface-treated copper foil obtained in the above examples and comparative examples was made to face the polyimide. The vacuum hot pressing was performed under the conditions of a temperature of 360 degrees Celsius, a pressure of 11.5 MPa, a pressing time of 30 minutes, and a cooling time of approximately 1 hour. The surface-treated copper foil obtained in the above examples and comparative examples on the copper-clad laminate was chemically etched to form a circuit with a width of 1 mm in the MD direction (longitudinal direction of the rolled copper foil). The circuit formation was carried out according to the usual method. The etched circuit was then bonded to a rigid substrate and cut to a predetermined size to be used as a test piece for measurement. Next, the strength (TD90° peel strength) was measured when peeling the circuit (surface-treated copper foil) of this test specimen from the polyimide surface at a 90° angle, i.e., perpendicularly upward relative to the surface of the resin substrate. The pulling speed was set to 50 mm / min. The measurement was performed four times, and the average value was used as the peel strength result. The peel strength was measured before and after heating the test specimen in air at 225°C for 120 hours.

[0070] The results of each of the above evaluations are shown in Table 1.

[0071]

[0072] As shown in Table 1, the surface-treated copper foils of Examples 1 to 7 showed higher peel strength before heating and maintained a high peel strength after heating compared to the surface-treated copper foils of Comparative Examples 1 to 4. They also exhibited excellent adhesion to the resin layer (circuit) and were found to suppress the deterioration of adhesion to the resin layer (circuit) even when exposed to high temperatures for extended periods.

[0073] 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 that has excellent adhesion to the resin layer and can suppress a decrease in adhesion to the resin layer even when exposed to high temperatures for a long time. Furthermore, according to the embodiments of the present invention, it is possible to provide a copper-clad laminate that has excellent adhesion to the resin layer and can suppress a decrease in adhesion to the resin layer even when exposed to high temperatures for a long time.

[0074] Accordingly, embodiments of the present invention can be as follows: [1] A surface-treated copper foil comprising a copper foil and a surface treatment layer provided on at least one surface of the copper foil, wherein the surface treatment layer contains Zn, and the amount of Zn deposited in the surface treatment layer is 300 to 1000 μg / dm 2 [1] Surface-treated copper foil wherein the semi-softening temperature of the surface-treated copper foil is 145°C or lower. [2] The surface-treated copper foil according to [1], wherein the semi-softening temperature of the surface-treated copper foil is 80 to 140°C. [3] The surface-treated copper foil according to [2], wherein the semi-softening temperature of the surface-treated copper foil is 100 to 135°C. [4] In the surface-treated layer, the amount of Zn deposited is 489 to 935 μg / dm 2 The surface-treated copper foil according to any one of [1] to [3]. [5] In the surface treatment layer, the amount of Zn deposited is 688 to 935 μg / dm 2 The surface-treated copper foil described in [4]. [6] The surface treatment layer further contains Ni, wherein the amount of Ni deposited in the surface treatment layer is 700 to 1500 μg / dm 2 The surface-treated copper foil according to any one of [1] to [5]. [7] In the surface treatment layer, the amount of Ni deposited is 999 to 1262 μg / dm 2 The surface-treated copper foil described in [6]. [8] The surface treatment layer further contains Co, and the amount of Co deposited in the surface treatment layer is 1800 to 2200 μg / dm 2 The surface-treated copper foil described in any one of [1] to [7]. [9] In the surface treatment layer, the amount of Co deposited is 1935 to 1998 μg / dm 2The surface-treated copper foil described in [8].

[10] The surface treatment layer further contains Cr, wherein the amount of Cr deposited in the surface treatment layer is 10 to 100 μg / dm 2 The surface-treated copper foil according to any one of [1] to [9].

[11] In the surface treatment layer, the amount of Cr deposited is 63 to 69 μg / dm 2 The surface-treated copper foil described in

[10] .

[12] In the surface treatment layer, the ratio of the amount of Zn to the total amount of Ni, Zn, Co and Cr is R Zn

[13] A surface-treated copper foil according to any one of [1] to

[11] , wherein the ratio of the surface-treated layer to the surface-treated layer is 0.110 to 0.250.

[14] A surface-treated copper foil according to any one of [1] to

[13] , wherein the thickness of the copper foil is 18 to 150 μm.

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

[14] and a resin layer provided on the surface of the surface-treated layer of the surface-treated copper foil.

[16] The copper-clad laminate according to

[15] , wherein the resin layer is made of a resin having a melting point of 320°C or lower.

Claims

1. A surface-treated copper foil comprising a copper foil and a surface treatment layer provided on at least one surface of the copper foil, wherein the surface treatment layer contains Zn, and the amount of Zn deposited in the surface treatment layer is 300 to 1000 μg / dm 2 A surface-treated copper foil wherein the semi-softening temperature of the surface-treated copper foil is 145°C or lower.

2. The surface-treated copper foil according to claim 1, wherein the semi-softening temperature of the surface-treated copper foil is 80 to 140°C.

3. The surface-treated copper foil according to claim 2, wherein the semi-softening temperature of the surface-treated copper foil is 100 to 135°C.

4. In the surface treatment layer, the amount of Zn deposited is 489 to 935 μg / dm 2 The surface-treated copper foil according to claim 1.

5. In the surface treatment layer, the amount of Zn deposited is 688 to 935 μg / dm 2 The surface-treated copper foil according to claim 4.

6. The surface treatment layer further contains Ni, and the amount of Ni deposited in the surface treatment layer is 700 to 1500 μg / dm 2 The surface-treated copper foil according to claim 1.

7. In the surface treatment layer, the amount of Ni deposited is 999 to 1262 μg / dm 2 The surface-treated copper foil according to claim 6.

8. The surface treatment layer further contains Co, and the amount of Co deposited in the surface treatment layer is 1800 to 2200 μg / dm 2 The surface-treated copper foil according to claim 1.

9. In the surface treatment layer, the amount of Co deposited is 1935 to 1998 μg / dm 2 The surface-treated copper foil according to claim 8.

10. The surface treatment layer further contains Cr, and the amount of Cr deposited in the surface treatment layer is 10 to 100 μg / dm 2 The surface-treated copper foil according to claim 1.

11. The coating weight of Cr in said surface treatment layer is 63 to 69 µg / dm 2 , the surface-treated copper foil according to claim 10.

12. In the surface treatment layer, the ratio R of the amount of Zn deposited to the total amount of Ni, Zn, Co, and Cr deposited. Zn The surface-treated copper foil according to claim 1, wherein the coefficient is 0.110 to 0.

250.

13. The surface-treated copper foil according to claim 1, wherein the unfolded interface area ratio Sdr of the surface-treated layer is 5.0 to 25.0%.

14. The surface-treated copper foil according to claim 1, wherein the thickness of the copper foil is 18 to 150 μm.

15. A copper-clad laminate comprising a surface-treated copper foil according to any one of claims 1 to 14, and a resin layer provided on the surface of the surface-treated layer of the surface-treated copper foil.

16. The copper-clad laminate according to claim 15, wherein the resin layer is made of a resin having a melting point of 320°C or lower.

Images