Coarse copper foil, copper-clad laminated panels, and printed circuit boards.

Abstract

DEPCT67 This invention involves the preparation of coarse copper foil which can be made to possess both the characteristics of Excellent transmission and high peel resistance when used for copper-clad laminated materials. Or, such a coarse copper foil printed circuit board consists of a rough surface on at least one area. One side of the rough surface has a tantheta roughness slope equal to 0.58 or less, as specified. Calculated based on the mean height Rc (micrometers) and mean width. RSm (micrometers) of the lateral cross-sectional element by the formula Rc / (0.5xRSm) and the projected area. Small RcxRSm molecules have dimensions of 0.45 sq µm or larger and 2.00 sq µm or less. This is the product of the mean height Rc (micrometers) and the mean width Rsm. The (micrometers) of the cross-sectional components Rc and Rsm are values ​​measured according to the JIS B0601- standard. 2013, provided that there is no deduction by lambda deduction values ​​s and lambda deduction value c;

Description

Roughened copper foil, copper-clad laminates and printed wiring boards

[0001] The present invention relates to a roughened copper foil, a copper-clad laminate, and a printed wiring board.

[0002] In the manufacturing process of printed wiring boards, copper foil is widely used in the form of a copper-clad laminate in which it is laminated with an insulating resin substrate. In this regard, in order to prevent peeling of wiring during the manufacturing of printed wiring boards, it is desirable for the copper foil and the insulating resin substrate to have high adhesion. Therefore, in the case of copper foil for manufacturing conventional printed wiring boards, the bonding surface of the copper foil is roughened to form irregularities consisting of fine copper particles, and these irregularities are pressed into the insulating resin substrate to exert an anchor effect, thereby improving adhesion.

[0003]

[0003] Meanwhile, with the recent advancement in the functionality of portable electronic devices and the like, signals, whether digital or analog, are increasingly being transmitted at higher frequencies in order to process large volumes of data at high speed, and printed wiring boards suitable for high-frequency applications are in demand. Such high-frequency printed wiring boards are required to have reduced transmission loss so that high-frequency signals can be transmitted without degradation. Printed wiring boards include copper foil processed into a wiring pattern and an insulating substrate, and the main transmission losses include conductor loss due to the copper foil and dielectric loss due to the insulating substrate.

[0004] Conductor loss can increase due to the skin effect of copper foil, which becomes more pronounced at higher frequencies. Therefore, to suppress transmission loss in high-frequency applications, it is necessary to reduce the roughening particles to reduce the skin effect of the copper foil. As an example of a copper foil having such fine roughening particles, Patent Document 1 (WO 2014 / 133164) discloses a surface-treated copper foil having a black roughened surface roughened by the adhesion of copper particles (e.g., substantially spherical copper particles) having a particle size of 10 nm to 250 nm. Furthermore, Patent Document 2 (JP 2011-168887 A) discloses a roughened copper foil having a roughened surface with a surface roughness Rz of 1.1 μm or less after roughening treatment, as a copper foil with excellent transmission characteristics in the high-frequency range.

[0005] International Publication No. 2014 / 133164 Japanese Patent Application Laid-Open No. 2011-168887

[0006] As mentioned above, attempts have been made to finely roughen the bonding surface of the copper foil with the insulating resin substrate in order to improve transmission characteristics (high-frequency characteristics). However, when copper foil that has been subjected to a fine roughening treatment is simply used to process a copper-clad laminate or manufacture a printed wiring board, the peel strength between the copper foil and the substrate is generally low, and problems such as poor heat resistance reliability (heat-resistant peel strength) can arise.

[0007] The present inventors have now discovered that by controlling the roughness slope tanθ and the micro-roughening projected area, which are calculated based on the average height Rc and the average length RSm of the contour curve element, respectively, on the surface of a roughened copper foil within a predetermined range, it is possible to achieve both excellent transmission characteristics and high peel strength in a copper-clad laminate or printed wiring board manufactured using this.

[0008] Therefore, an object of the present invention is to provide a roughened copper foil that can achieve both excellent transmission properties and high peel strength when used in copper-clad laminates or printed wiring boards.

[0009] According to one aspect of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side, wherein the roughened surface has a roughness gradient tanθ of 0.58 or less, calculated from the formula Rc / (0.5×RSm) based on an average height Rc (μm) and an average length RSm (μm) of a profile element, and a micro-roughening projected area Rc×RSm, which is the product of the average height Rc (μm) and the average length RSm (μm) of the profile element, of 0.45 μm. ２ 2.00 μm or more ２ The Rc and RSm are values ​​measured under conditions in which cutoff is not performed using the cutoff value λs and the cutoff value λc in accordance with JIS B0601-2013.

[0010] According to another aspect of the present invention, there is provided a copper-clad laminate comprising the above-described roughened copper foil.

[0011] According to yet another aspect of the present invention, there is provided a printed wiring board comprising the above-described roughened copper foil.

[0012] FIG. 10 is a diagram for explaining a roughness gradient tan θ calculated by a trigonometric function.

[0013] DEFINITIONS The following are definitions of terms or parameters used to define the present invention.

[0014] In this specification, the term "average height Rc" or "Rc" refers to a parameter that represents the average height of a profile element in a reference length, measured in accordance with JIS B0601-2013.

[0015] In this specification, the term "average length RSm" or "RSm" refers to a parameter that represents the average length of the profile curve elements in a reference length, measured in accordance with JIS B0601-2013. The average length RSm is a parameter that evaluates the lateral size of streaks or particles, rather than the height of the surface irregularities.

[0016] With respect to Rc and RSm, the peaks and valleys that make up the profile curve elements have specified minimum heights and lengths, and any peaks or valleys whose height is 10% or less of the maximum height Rz or whose length is 1% or less of the reference length are regarded as noise and are treated as part of the valleys or peaks that follow before and after.

[0017] In this specification, the term "roughness slope tan θ" refers to a parameter calculated by the formula Rc / (0.5×RSm) based on the average height Rc (μm) and the average length RSm (μm) of the profile elements. Also, in this specification, the term "small projected area (SPA)" refers to a parameter calculated by the product of the average height Rc (μm) and the average length RSm (μm) of the profile elements (i.e., Rc×RSm).

[0018] In this specification, "interface developed area ratio Sdr" is a parameter measured in accordance with ISO 25178, which expresses as a percentage the degree to which the developed area (surface area) of a defined region has increased relative to the area of ​​the defined region. The smaller this value, the closer the surface shape is to being flat, and a completely flat surface has an Sdr of 0%. On the other hand, the larger this value, the more irregular the surface shape is.

[0019] In this specification, the term "arithmetic mean height Sa" or "Sa" refers to a parameter that represents the average of the absolute values ​​of the height differences at each point relative to the average plane of the surface, measured in accordance with ISO 25178. In other words, it corresponds to a parameter that expands the arithmetic mean height Ra of the profile curve to a plane.

[0020] In this specification, the "root mean square height Sq" or "Sq" is a parameter equivalent to the standard deviation of the distance from the mean plane measured in accordance with ISO 25178. In other words, it is equivalent to a parameter obtained by expanding the root mean square height Rq of the profile curve to a plane.

[0021] RSm and Rc can be calculated by measuring the surface profile of a predetermined measurement length on the roughened surface using a commercially available laser microscope. Furthermore, Sdr, Sa, and Sq can be calculated by measuring the surface profile of a predetermined measurement area on the roughened surface using a commercially available laser microscope. In this specification, the parameters Sdr, Sa, and Sq are measured without cutoff by the S filter and L filter, and the parameters RSm and Rc are measured without cutoff by the cutoff values ​​λs and λc. Other preferred measurement and analysis conditions for the surface profile using a laser microscope are shown in the examples below.

[0022] In this specification, the "electrode surface" of the electrolytic copper foil refers to the surface that was in contact with the cathode during the production of the electrolytic copper foil.

[0023] In this specification, the "deposit side" of an electrolytic copper foil refers to the side on which electrolytic copper is deposited during the production of the electrolytic copper foil, i.e., the side not in contact with the cathode.

[0024] The copper foil of the present invention is a roughened copper foil. This roughened copper foil has a roughened surface on at least one side. This roughened surface has a roughness gradient tanθ of 0.58 or less, calculated by the formula Rc / (0.5×RSm) based on the average height Rc (μm) and the average length RSm (μm) of the profile curve elements. Furthermore, the roughened surface has a micro-roughened projected area Rc×RSm, which is the product of the average height Rc (μm) and the average length RSm (μm) of the profile curve elements, of 0.45 μm. ２ 2.00 μm or more ２ In this way, by controlling the roughness slope tan θ and the micro-roughening projected area, which are calculated based on the average height Rc and the average length RSm of the profile curve element, respectively, on the surface of the roughened copper foil within a predetermined range, it is possible to achieve both excellent transmission characteristics and high peel strength in a copper-clad laminate or printed wiring board manufactured using the same.

[0025] As mentioned above, attempts have been made to finely roughen the bonding surface of the copper foil with the insulating resin substrate in order to improve transmission characteristics (high-frequency characteristics). However, when copper foil that has been subjected to a fine roughening treatment is simply used to process a copper-clad laminate or manufacture a printed wiring board, the peel strength between the copper foil and the substrate is generally low, and problems such as poor heat resistance reliability (heat-resistant peel strength) can arise.

[0026] As a result of the inventors' investigation into this issue, they found that the transmission characteristics are related to the roughness slope tan θ of the roughened surface, and that the peel strength (particularly the heat-resistant peel strength) between the copper foil and the substrate is related to the microscopic roughness projected area (SPA) of the roughened surface. While the mechanisms behind these findings are not entirely clear, they are thought to be as follows. Figure 1 shows the roughness slope tan θ calculated using trigonometric functions. As shown in Figure 1, the roughness slope tan θ is calculated using the formula Rc / (0.5 × RSm), which corresponds to the angle of the peaks or valleys on the roughened surface. In other words, the smaller the roughness slope tan θ, the smaller this angle (i.e., the gentler the peaks or valleys), resulting in a smoother current flow. Conversely, the larger the roughness slope tan θ, the larger this angle, resulting in a higher resistance (i.e., a higher current resistance). Therefore, it is believed that excellent transmission characteristics can be achieved by controlling the roughness slope tan θ to a small value of 0.58 or less. Furthermore, SPA represents the size (projected area) of the bumps on the roughened surface, and by increasing this value, the anchoring effect with the substrate (i.e., the effect of improving physical adhesion by utilizing the unevenness of the copper foil surface) can be enhanced. On the other hand, if the SPA on the roughened surface is too large, the bumps will become coarse, which will tend to result in poor transmission characteristics. For this reason, it is recommended to set the SPA to 0.45 μm. ２ 2.00 μm or more ２ By controlling the following, it is possible to ensure high adhesion reliability with the substrate while maintaining fine nodules, which are advantageous from the viewpoint of transmission characteristics. As a result, the roughened copper foil of the present invention makes it possible to achieve both excellent transmission characteristics and adhesion reliability due to high peel strength (especially heat-resistant peel strength) in a copper-clad laminate or printed wiring board manufactured using the same.

[0027] Therefore, the roughened surface of the roughened copper foil has a roughness gradient tanθ of 0.58 or less and a micro roughness projected area (SPA) of 0.45 μm ２ 2.00 μm or more ２ Preferably, the roughened surface has a roughness gradient tan θ of 0.30 or less and a micro-roughened projected area of ​​0.45 μm or less. ２1.00 μm or more ２ More preferably, the roughness gradient tanθ is 0.25 or less, and the micro-roughening projected area is 0.47 μm ２ 0.80 μm or more ２ More preferably, the roughness gradient tanθ is 0.05 or more and 0.20 or less, and the micro-roughening projected area is 0.47 μm ２ 0.80 μm or more ２ More preferably, the roughness gradient tanθ is 0.10 or more and 0.15 or less, and the micro-roughening projected area is 0.50 μm or less. ２ 0.60 μm or more ２ The following is the result.

[0028] The roughened copper foil preferably has an interface developed area ratio Sdr of 60% or less on the roughened surface, more preferably 1% to 40%, even more preferably 2% to 30%, particularly preferably 3% to 20%, and most preferably 5% to 15%. With Sdr within the above range, the roughened surface has an irregular shape that is favorable for realizing high adhesion reliability while maintaining excellent transmission characteristics.

[0029] The roughened copper foil preferably has an average height Rc of 0.15 μm or more and 0.80 μm or less on the roughened surface, more preferably 0.16 μm or more and 0.60 μm or less, even more preferably 0.16 μm or more and 0.50 μm or less, still more preferably 0.17 μm or more and 0.40 μm or less, particularly preferably 0.17 μm or more and 0.30 μm or less, and most preferably 0.18 μm or more and 0.25 μm or less. When Rc is within the above range, it becomes easier to control the roughness slope tan θ and SPA within the above range, and more excellent transmission characteristics can be achieved while ensuring high adhesion reliability.

[0030] The roughened copper foil preferably has an arithmetic mean height Sa of 0.30 μm or less on the roughened surface, more preferably 0.01 μm or more and 0.25 μm or less, even more preferably 0.02 μm or more and 0.22 μm or less, particularly preferably 0.03 μm or more and 0.17 μm or less, and most preferably 0.05 μm or more and 0.14 μm or less. When Sa is within the above range, better transmission characteristics can be achieved.

[0031] The roughened copper foil preferably has a root mean square height Sq of 0.35 μm or less on the roughened surface, more preferably 0.02 μm or more and 0.30 μm or less, even more preferably 0.02 μm or more and 0.25 μm or less, particularly preferably 0.03 μm or more and 0.20 μm or less, and most preferably 0.03 μm or more and 0.17 μm or less. With an Sq within the above range, better transmission characteristics can be achieved.

[0032] The roughened copper foil preferably has an average length RSm of the profile curve element on the roughened surface of 2.40 μm to 3.50 μm, more preferably 2.60 μm to 3.50 μm, and even more preferably 2.60 μm to 3.30 μm. When RSm is within the above range, it is easy to control the roughness slope tanθ and SPA within the above range, and the shape of the peaks or valleys on the roughened surface becomes sufficiently gentle while ensuring high adhesion reliability, thereby achieving better transmission characteristics.

[0033] The thickness of the roughened copper foil is not particularly limited, but is preferably 0.1 μm or more and 210 μm or less, more preferably 0.5 μm or more and 70 μm or less. The roughened copper foil of the present invention is not limited to ordinary copper foil whose surface has been roughened, but may also be a carrier-attached copper foil whose surface has been roughened or finely roughened.

[0034] The roughened copper foil of the present invention can be preferably produced by roughening a smooth copper foil surface (e.g., the deposit surface of an electrolytic copper foil (smooth foil)) under desired low-roughening conditions to form fine roughening particles. Therefore, according to a preferred embodiment of the present invention, the roughened copper foil is an electrolytic copper foil, and the roughened surface is located on the deposit side of the electrolytic copper foil. The roughened copper foil may have roughened surfaces on both sides or only one side. The roughened surface typically comprises a plurality of roughening particles, each of which is preferably copper particles. The copper particles may be metallic copper or a copper alloy.

[0035] The roughening treatment to form a roughened surface can be preferably carried out by forming roughening particles of copper or a copper alloy on a copper foil. The copper foil before the roughening treatment may be an unroughened copper foil or may have been subjected to preliminary roughening. The surface of the copper foil to be roughened preferably has a ten-point average roughness Rz measured in accordance with JIS B0601-1994 of 0.10 μm or more and 1.20 μm or less, more preferably 0.30 μm or more and 1.00 μm or less. Within the above range, it is easy to impart the surface profile required for the roughened copper foil of the present invention to the roughened surface.

[0036] The roughening treatment may be carried out, for example, in a copper sulfate solution containing a copper concentration of 3 g / L to 20 g / L and a sulfuric acid concentration of 50 g / L to 200 g / L at a temperature of 20° C. to 40° C. under a pressure of 10 A / dm ２ More than 200A / dm ２ It is preferable to carry out the electrolytic deposition as follows. The electrolytic deposition is preferably carried out for 0.2 seconds to 30 seconds, more preferably 0.2 seconds to 15 seconds, and even more preferably 0.5 seconds to 10 seconds. During the electrolytic deposition, the following formula: F Ｃｕ =F ＣｕＳＯ４ ×C Ｃｕ / S (in the formula, F Ｃｕ is the amount of copper supplied between electrodes [(g m) / (min L)], F ＣｕＳＯ４ is the flow rate of the copper sulfate solution (m ３ / min), C Ｃｕ is the copper concentration of the copper sulfate solution (g / L), S is the cross-sectional area between the anode and cathode (m ２ ) is preferably set to 0.1 [(g m) / (min L)] or more and 15.0 [(g m) / (min L)] or less. By doing so, it becomes easier to impart the surface profile required for the roughened copper foil of the present invention to the surface of the roughened copper foil. However, the roughened copper foil of the present invention is not limited to the above method and may be produced by any method.

[0037] If desired, the roughening treatment may further include a second roughening treatment in which electrolytic deposition is performed under predetermined conditions on the surface after the above roughening treatment (first roughening treatment), and a third roughening treatment in which electrolytic deposition is performed under predetermined conditions on the surface after the second roughening treatment. The preferred conditions for the second roughening treatment are the same as those described above for the first roughening treatment.

[0038] On the other hand, the third roughening treatment is carried out in a copper sulfate solution containing, for example, a copper concentration of 65 g / L or more and 80 g / L or less and a sulfuric acid concentration of 200 g / L or more and 280 g / L or less, at a temperature of 45° C. or more and 55° C. or less, at 1 A / dm ２ 5A / dm or more ２ It is preferable to perform electrolytic deposition for 25 seconds or more and 35 seconds or less, and more preferably 27 seconds or more and 32 seconds or less. Furthermore, during electrolytic deposition, it is preferable to set the inter-electrode copper supply rate to 50 [(g m) / (min L)] or more and 200 [(g m) / (min L)] or less.

[0039] If desired, the roughened copper foil may be subjected to a rust-preventive treatment to form a rust-preventive treatment layer. The rust-preventive treatment preferably includes a plating treatment using zinc. The zinc-based plating treatment may be either a zinc plating treatment or a zinc alloy plating treatment, with a zinc-nickel alloy plating treatment being particularly preferred. The zinc-nickel alloy treatment may be a plating treatment containing at least Ni and Zn, and may further contain other elements such as Sn, Cr, Co, and Mo. For example, if the rust-preventive treatment layer further contains Mo in addition to Ni and Zn, the treated surface of the roughened copper foil will have better adhesion to resin, chemical resistance, and heat resistance, and will be less likely to leave etching residues. The Ni / Zn deposition ratio in the zinc-nickel alloy plating is preferably 1.2 to 10, more preferably 2 to 7, and even more preferably 2.7 to 4, by mass. Furthermore, it is preferable that the rust prevention treatment further includes a chromate treatment, and more preferably, this chromate treatment is performed on the surface of the zinc-containing plating after the zinc plating treatment. This can further improve rust prevention. A particularly preferable rust prevention treatment is a combination of a zinc-nickel alloy plating treatment followed by a chromate treatment.

[0040] If desired, the surface of the roughened copper foil may be treated with a silane coupling agent to form a silane coupling agent layer. This can improve moisture resistance, chemical resistance, and adhesion to adhesives, etc. The silane coupling agent layer can be formed by applying an appropriately diluted silane coupling agent and drying it. Examples of the silane coupling agent include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane, amino-functional silane coupling agents such as 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane, mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane, olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane, acrylic-functional silane coupling agents such as 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane, imidazole-functional silane coupling agents such as imidazole silane, and triazine-functional silane coupling agents such as triazine silane.

[0041] For the reasons described above, the roughened copper foil preferably further comprises a rust-proofing layer and / or a silane coupling agent layer on the roughened surface, and more preferably comprises both a rust-proofing layer and a silane coupling agent layer. The rust-proofing layer and the silane coupling agent layer may be formed not only on the roughened surface side of the roughened copper foil but also on the side where the roughened surface is not formed.

[0042] Copper-clad laminate The roughened copper foil of the present invention is preferably used in the production of a copper-clad laminate for printed wiring boards. That is, according to a preferred embodiment of the present invention, a copper-clad laminate including the above-mentioned roughened copper foil is provided. By using the roughened copper foil of the present invention, the copper-clad laminate can achieve both excellent transmission characteristics and high reliability. This copper-clad laminate comprises the roughened copper foil of the present invention and a resin layer provided in close contact with the roughened surface of the roughened copper foil. The roughened copper foil may be provided on one or both sides of the resin layer. The resin layer comprises a resin, preferably an insulating resin. The resin layer is preferably a prepreg and / or a resin sheet. Prepreg is a general term for a composite material in which a substrate such as a synthetic resin plate, glass plate, woven glass fabric, nonwoven glass fabric, or paper is impregnated with a synthetic resin. Preferred examples of insulating resins include epoxy resins, cyanate resins, bismaleimide triazine resins (BT resins), polyphenylene ether resins, and phenolic resins. Examples of insulating resins constituting the resin sheet include insulating resins such as epoxy resins, polyimide resins, and polyester resins. Furthermore, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina to improve insulation. The thickness of the resin layer is not particularly limited, but is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and even more preferably 3 μm or more and 200 μm or less. The resin layer may be composed of multiple layers. A resin layer such as a prepreg and / or a resin sheet may be provided on a roughened copper foil via a primer resin layer previously applied to the copper foil surface.

[0043] Printed Wiring Boards The roughened copper foil of the present invention is preferably used in the manufacture of printed wiring boards. That is, according to a preferred embodiment of the present invention, a printed wiring board including the above-mentioned roughened copper foil is provided. By using the roughened copper foil of the present invention, the printed wiring board can achieve both excellent transmission characteristics and high reliability. The printed wiring board according to this embodiment comprises a layer structure in which a resin layer and a copper layer are laminated. The copper layer is a layer derived from the roughened copper foil of the present invention. The resin layer is as described above for the copper-clad laminate. In either case, a known layer structure can be adopted for the printed wiring board. Specific examples of printed wiring boards include single-sided or double-sided printed wiring boards in which the roughened copper foil of the present invention is bonded to one or both sides of a prepreg to form a cured laminate and then a circuit is formed, and multilayer printed wiring boards in which these are multilayered. Other specific examples include flexible printed wiring boards, COFs, TAB tapes, etc. in which a circuit is formed by forming the roughened copper foil of the present invention on a resin film. Further specific examples include build-up wiring boards in which a resin-coated copper foil (RCC) is formed by applying the above-mentioned resin layer to the roughened copper foil of the present invention, and the resin layer is laminated on the above-mentioned printed circuit board as an insulating adhesive layer, and then a circuit is formed by using the roughened copper foil as all or part of the wiring layer using a modified semi-additive method (MSAP), a subtractive method, or the like; build-up wiring boards in which the roughened copper foil is removed and a circuit is formed by the semi-additive method (SAP); and direct build-up on wafers in which lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit.

[0044] The present invention is further illustrated by the following examples.

[0045] Examples 1 to 9 The roughened copper foil of the present invention was produced as follows.

[0046] (1) Production of Electrodeposited Copper Foils In Examples 1 to 6 and 9, a copper electrolytic solution having the following composition was used as the copper electrolytic solution, a titanium electrode was used as the cathode, and a DSA (dimensionally stable anode) was used as the anode, and the temperature of the solution was 45°C, the current density was 55 A / dm ２to obtain electrolytic copper foils (smooth foils) with the thicknesses shown in Table 1. At this time, an electrode whose surface had been polished with a #1000 buff to adjust the surface roughness was used as the cathode. <Composition of sulfuric acid acid copper sulfate solution> - Copper concentration: 80 g / L - Sulfuric acid concentration: 260 g / L - Bis(3-sulfopropyl)disulfide concentration: 30 mg / L - Diallyldimethylammonium chloride polymer concentration: 50 mg / L - Chlorine concentration: 40 mg / L

[0047] In Examples 7 and 8, a sulfuric acid acidic copper sulfate solution having the composition shown below was used as the copper electrolyte to obtain electrolytic copper foils (general foils) having the thicknesses shown in Table 1. At this time, the conditions other than the composition of the sulfuric acid acidic copper sulfate solution were the same as in Examples 1 to 6 and 9. <Composition of sulfuric acid acidic copper sulfate solution> - Copper concentration: 80 g / L - Sulfuric acid concentration: 300 g / L - Glue concentration: 5 mg / L - Chlorine concentration: 30 mg / L

[0048] (2) Roughening Treatment Of the electrode surface and deposit surface of the above-mentioned electrodeposited copper foils, a roughening treatment was performed on the deposit surface side in Examples 1 to 6 and 9, and on the electrode surface side in Examples 7 and 8. The ten-point average roughness Rz of the deposit surfaces of the electrodeposited copper foils used in Examples 1 to 6 and 9 and the electrode surfaces of the electrodeposited copper foils used in Examples 7 and 8, measured in accordance with JIS B0601-1994 using a contact surface roughness meter, was as shown in Table 1.

[0049] The following roughening treatment (first roughening treatment) was carried out for Examples 1, 2, and 9. This roughening treatment was carried out by electrolysis in a copper electrolytic solution for roughening treatment (copper concentration: 3 g / L to 20 g / L, sulfuric acid concentration: 50 g / L to 200 g / L, solution temperature: 30°C) under the conditions of the current density, time, and inter-electrode copper supply amount shown in Table 1 for each example, followed by rinsing with water.

[0050] For Examples 3 to 8, the first roughening treatment, second roughening treatment, and third roughening treatment shown below were performed in this order. - The first roughening treatment was performed by electrolysis in a copper electrolytic solution for roughening treatment (copper concentration: 3 g / L to 20 g / L, sulfuric acid concentration: 50 g / L to 200 g / L, solution temperature: 30°C) under the conditions of the current density, time, and inter-electrode copper supply amount shown in Table 1 for each Example, followed by rinsing with water. - The second roughening treatment was performed by electrolysis in a copper electrolytic solution for roughening treatment having the same composition as the first roughening treatment, under the conditions of the current density, time, and inter-electrode copper supply amount shown in Table 1 for each Example, followed by rinsing with water. The third roughening treatment was carried out by electrolysis in a copper electrolytic solution for roughening treatment (copper concentration: 65 g / L or more and 80 g / L or less, sulfuric acid concentration: 200 g / L or more and 280 g / L or less, solution temperature: 45°C) under the conditions of the current density, time and inter-electrode copper supply amount shown in Table 1 for each example, followed by rinsing with water.

[0051] (3) Rust Prevention Treatment The roughened electrodeposited copper foil was subjected to the rust prevention treatment shown in Table 1. As the rust prevention treatment, in Examples 2 and 4 to 9, both sides of the electrodeposited copper foil were treated with a pyrophosphate bath containing potassium pyrophosphate at a concentration of 80 g / L, zinc at a concentration of 0.2 g / L, and nickel at a solution temperature of 40°C, and a current density of 0.5 A / dm ２ On the other hand, in Examples 1 and 3, the roughened surface of the electrolytic copper foil was subjected to a zinc-nickel based rust prevention treatment using a solution containing potassium pyrophosphate at a concentration of 100 g / L, zinc at a concentration of 1 g / L, nickel at a concentration of 2 g / L, molybdenum at a concentration of 1 g / L, a solution temperature of 40°C, and a current density of 0.5 A / dm ２ The surfaces of the electrodeposited copper foils of Examples 1 and 3 that had not been subjected to the roughening treatment were subjected to a zinc-nickel-based rust-proofing treatment under the same conditions as in Examples 2 and 4 to 9.

[0052] (4) Chromate Treatment Chromate treatment was performed on both sides of the electrolytic copper foil that had been subjected to the above rust prevention treatment, to form a chromate layer on the rust prevention treatment layer. This chromate treatment was performed under the conditions of a chromic acid concentration of 1 g / L, pH 11, a liquid temperature of 25°C, and a current density of 1 A / dm ２ The experiment was carried out under the following conditions.

[0053] (5) Silane Coupling Agent Treatment The chromate-treated copper foil was washed with water and immediately treated with a silane coupling agent to adsorb the silane coupling agent onto the chromate layer on the roughened surface. This silane coupling agent treatment was performed by showering a solution of the silane coupling agent in pure water onto the roughened surface to allow adsorption. As the silane coupling agent, 3-aminopropyltrimethoxysilane was used in Examples 1 to 3 and 9, 3-acryloxypropyltrimethoxysilane in Example 4, and 3-glycidoxypropyltrimethoxysilane in Examples 5 to 8. The concentration of the silane coupling agent was 3 g / L in each case. After adsorption of the silane coupling agent, the water was finally evaporated using an electric heater to obtain a roughened copper foil of the desired thickness.

[0054]

[0055] Evaluation The produced roughened copper foils were subjected to the following various evaluations.

[0056] (a) Surface Property Parameters of Roughened Surface The roughened surface of the roughened copper foil was measured by surface roughness analysis using a laser microscope in accordance with ISO 25178 or JIS B0601-2013. Specific measurement conditions were as shown in Table 2. The surface profile of the obtained roughened surface was analyzed according to the conditions shown in Table 2, and RSm, Rc, Sdr, Sa, and Sq were calculated. In addition, the roughness slope tan θ (= Rc / (0.5 × RSm)) and the microscopic roughness projected area (SPA) (= Rc × RSm) were calculated based on the obtained RSm and Rc values. The results were as shown in Table 3.

[0057]

[0058] (b) Peel Strength Between Copper Foil and Substrate In order to evaluate the adhesion of the roughened copper foil to the insulating substrate in the normal state and after heat loading, the normal peel strength and heat-resistant peel strength were measured as follows.

[0059] (b-1) Normal peel strength Two sheets of prepreg (thickness: 100 μm) mainly composed of polyphenylene ether, triallyl isocyanurate, and bismaleimide resin were prepared as insulating substrates and stacked. The surface-treated copper foil thus produced was laminated on the stacked prepreg so that its roughened surface was in contact with the prepreg. A peel strength of 32 kgf / cm was obtained. ２ , and pressed at 205°C for 120 minutes to produce a copper-clad laminate. Next, a circuit was formed on this copper-clad laminate by etching, to produce a test board with a 3 mm wide linear circuit. In Example 7, prior to circuit formation, copper plating was performed on the copper foil side surface of the copper-clad laminate until the copper foil thickness reached 18 μm. The linear circuit thus obtained was peeled from the insulating substrate in accordance with Method A (90° peel) of JIS C 5016-1994, and the normal peel strength (kgf / cm) was measured. The normal peel strength obtained was evaluated according to the following criteria. The results are shown in Table 3. <Normal Peel Strength Evaluation Criteria> - Good: Normal peel strength of 0.54 kgf / cm or more - Poor: Normal peel strength of less than 0.54 kgf / cm

[0060] (b-2) Heat-resistant peel strength The heat-resistant peel strength (kgf / cm) was measured in the same manner as for the normal peel strength described above, except that prior to measuring the peel strength, the test board equipped with a linear circuit was floated in a solder bath at 288°C for 300 seconds. The obtained heat-resistant peel strength was evaluated according to the following criteria. The results are shown in Table 3. <Heat-resistant peel strength evaluation criteria> - Good: Heat-resistant peel strength of 0.54 kgf / cm or more - Poor: Heat-resistant peel strength of less than 0.54 kgf / cm

[0061] (c) Transmission Characteristics A high-frequency substrate (MEGTRON6N, manufactured by Panasonic) was prepared as an insulating resin substrate. Roughened copper foil was laminated on both sides of this insulating resin substrate so that the roughened surface abutted against the insulating resin substrate, and the laminate was laminated using a vacuum press under conditions of a temperature of 190 ° C and a pressing time of 120 minutes to obtain a copper-clad laminate with an insulation thickness of 136 μm. The copper-clad laminate was then etched to obtain a transmission loss measurement substrate on which a microstrip line was formed so that the characteristic impedance was 50 Ω. The transmission loss (dB / cm) at 50 GHz was measured using a network analyzer (N5225B, manufactured by Keysight Technologies) for the obtained transmission loss measurement substrate. The obtained transmission loss was rated and evaluated according to the following criteria. The results are shown in Table 3. <Transmission loss evaluation criteria> - Evaluation A (best): Transmission loss of -0.57 dB / cm or more - Evaluation B (good): Transmission loss of -0.63 dB / cm or more but less than -0.57 dB / cm - Evaluation C (poor): Transmission loss less than -0.63 dB / cm

[0062]

Claims

DEPCT671. Coarse copper foil incorporating a coarse surface on at least one side, where the coarse surface has a tantheta slope of 0.58 or less, calculated based on the mean height Rc (µm) and mean width RSm (µm) of the lateral cross-sectional element by the formula Rc / (0.5xRSm), and where the coarse surface has a microprojected area RcxRSm of 0.45 sq µm or larger and 2.00 sq µm or smaller, which is the product of the coarse surfaces. The mean height Rc (micrometers) and mean width RSm (micrometers) of the side cross-sectional element, where Rc and RSm are values ​​measured according to JIS B0601-2013 under the condition that no cut-off is performed by lambda cut-off values ​​s and c.

2. Coarse copper foil according to claim 1, where the coarse surface has a tantheta coarseness slope of 0.30 or less and the microprojected area RcxRSm is 0.45 sq. micrometers or more and 1.00 sq. micrometers or less. 3.Coarse copper foil according to claim 1 or 2, where the rough surface has a apparent interface area ratio (Sdr) of 60% or less, where Sdr is the value measured according to ISO 25178 under the condition that no elimination is done by S filter and L filter circuits.

4. Coarse copper foil according to any one of claims 1 to 3, where the rough surface has a mean height (Rc) of 0.15 micrometers or more and 0.80 micrometers or less.

5. Coarse copper foil according to any one of claims 1 to 3. Requisitions 1 through 4 apply where the surface roughness has an arithmetic mean height Sa equal to 0.30 micrometers or less, where Sa is the value measured according to ISO 25178, under the condition that no truncation is performed using the S filter and the L filter.

6. Coarse copper foil according to any one of Requisitions 1 through 5 applies where the surface roughness has a root mean square height Sq equal to 0.35 micrometers or less, where Sq is the value measured according to ISO 25178, under the condition that no truncation is performed using the S filter and the L filter. 7.Coarse copper foil as defined by any one of Claims 1 through 6 where the rough surface has a mean RSm width of the cross-sectional element of 2.40 µm or more and 3.50 µm or less; 8. Coarse copper foil as defined by any one of Claims 1 through 7 which also incorporates an anti-corrosion layer and / or a silane interfacing layer on the rough surface; 9. Coarse copper foil as defined by any one of Claims 1 through 8 where the coarse copper foil is an electrically coated copper foil and the rough surface appears on the coated side of the electrically coated copper foil; 10. Copper cladding material incorporating coarse copper foil as defined by any one of Claims 1 through 9; 11. Printed circuit board incorporating coarse copper foil as defined by any one of Claims 1 through 9.