WO2023182178A1 - Roughened copper foil, copper foil equipped with carrier, copper-clad laminate, and printed wiring board - Google Patents

Abstract

Provided is a roughened copper foil capable of achieving both high adhesiveness to a thermoplastic resin and exceptional high-frequency characteristics. The roughened copper foil has a roughened surface on at least one side thereof. The roughened surface has a skewness Ssk greater than 0.35 and a summit density Sds ranging from 1.57 μm–2 to 2.64 μm–2 inclusive. Ssk is a value measured with a cutoff wavelength of 1.0 μm by an L filter and without cutoff by an S filter in accordance with JIS B0681-2:2018. Sds is a value measured without cutoff by the S filter or the L filter in accordance with EUR15178N.

Description

Roughened copper foil, copper foil with carrier, copper clad laminates and printed wiring boards

The present invention relates to a roughened copper foil, a copper foil with a carrier, a copper-clad laminate, and a printed wiring board.

With the increasing functionality of portable electronic devices in recent years, the frequency of signals is increasing in order to process large amounts of information at high speed, and printed wiring boards are suitable for high frequency applications such as 5G, millimeter waves, and base station antennas. is required. Such a high frequency printed wiring board is desired to reduce transmission loss in order to be able to transmit high frequency signals without deteriorating quality. A printed wiring board is equipped with copper foil processed into a wiring pattern and an insulating resin base material, but transmission loss is caused by conductor loss due to the copper foil and dielectric loss due to the insulating resin base material. becomes the main character. Therefore, it would be advantageous if a thermoplastic resin with a low dielectric constant could be used in order to reduce the dielectric loss caused by the insulating resin base material. However, unlike thermosetting resins, thermoplastic resins with a low dielectric constant, such as fluororesins and liquid crystal polymers (LCP), have low chemical activity and therefore have low adhesion to copper foil.

Therefore, techniques have been proposed to improve the adhesion between copper foil and thermoplastic resin. For example, in Patent Document 1 (International Publication No. 2016/174998), the roughening particles have a ten-point average roughness Rzjis of 0.6 μm or more and 1.7 μm or less, and the half-width in the frequency distribution of the height of the roughening particles. A copper foil having a roughened surface having a roughness of 0.9 μm or less is disclosed. According to such a copper foil, it is possible to exhibit high peel strength even to an insulating resin base material, such as a liquid crystal polymer film, to which chemical adhesion cannot be expected.

On the other hand, conductor loss can increase due to the skin effect of copper foil, which becomes more pronounced as the frequency increases. Therefore, in order to suppress transmission loss in high frequency applications, it is required to make the roughening particles finer in order to reduce the skin effect of copper foil. As a copper foil having such fine roughening particles, for example, Patent Document 2 (International Publication No. 2014/133164) discloses a copper foil having a particle size of 10 nm or more and 250 nm or less (for example, approximately spherical copper particles) attached to the copper foil to make it rough. A surface-treated copper foil is disclosed that has a black, roughened surface.

International Publication No. 2016/174998 International Publication No. 2014/133164

Copper foils for high frequency applications are required to have finer roughening particles as described above, but such copper foils tend to have poor adhesion to resins (particularly thermoplastic resins). In this regard, existing copper foils are not necessarily sufficient in terms of both high adhesion with thermoplastic resins and excellent high frequency properties, and there is room for improvement.

The present inventors have recently discovered that by controlling the skewness Ssk and the peak density Sds within predetermined ranges on the surface of a roughened copper foil, the surface has high adhesion to thermoplastic resin and excellent high frequency properties. We found that it is possible to achieve both.

Therefore, an object of the present invention is to provide a roughened copper foil that is capable of achieving both high adhesion to a thermoplastic resin and excellent high frequency properties.

According to the present invention, the following aspects are provided.
[Aspect 1]
A roughened copper foil having a roughened surface on at least one side,
The roughened surface has a skewness Ssk greater than 0.35 and a peak density Sds of 1.57 μm ⁻² or more and 2.64 μm ^{−2 or} less,
The Ssk is a value measured in accordance with JIS B0681-2:2018 without cutoff with an S filter and with a cutoff wavelength of 1.0 μm using an L filter,
The above-mentioned Sds is a value measured in accordance with EUR15178N without cutoff using an S filter and an L filter, and is a roughened copper foil.
[Aspect 2]
The roughened surface has a plurality of roughened particles, and the volume of the roughened particles per 1 μm ² is 0.11 μm ³ or more and 0.25 μm ³ or less,
The roughening method according to aspect 1, wherein the volume of the roughened particles per 1 μm ² is a value calculated by three-dimensional analysis of an image obtained using FIB-SEM for the roughened surface. Treated copper foil.
[Aspect 3]
The roughened surface has a kurtosis Sku of 2.70 or more and 4.90 or less,
The roughened copper foil according to aspect 1 or 2, wherein the Sku is a value measured in accordance with JIS B0681-2:2018 without cutoff by an S filter and an L filter.
[Aspect 4]
The roughened surface has a load area ratio Smr1 of 11.2% or more that separates the protruding peak portion and the core portion,
The Smr1 is a value measured according to JIS B0681-2:2018 without cutoff with an S filter and with a cutoff wavelength of 1.0 μm using an L filter. The roughened copper foil described in .
[Aspect 5]
The roughened copper foil according to any one of aspects 1 to 4, further comprising a rust prevention treatment layer and/or a silane coupling agent layer on the roughened surface.
[Aspect 6]
A carrier, a release layer provided on the carrier, and the roughened copper foil according to any one of aspects 1 to 5 provided on the release layer with the roughened surface facing outward. Copper foil with carrier.
[Aspect 7]
A copper-clad laminate comprising the roughened copper foil according to any one of aspects 1 to 5.
[Aspect 8]
A printed wiring board comprising the roughened copper foil according to any one of aspects 1 to 5.

FIG. 3 is a diagram for explaining the skewness Ssk measured in accordance with JIS B0681-2:2018, and is a diagram showing the surface and its height distribution when Ssk<0. FIG. 3 is a diagram for explaining the skewness Ssk measured in accordance with JIS B0681-2:2018, and is a diagram showing the surface and its height distribution when Ssk>0. It is a diagram for explaining the peak density Sds measured in accordance with EUR15178N, and is a diagram showing an example of the surface and the peak in the case of Sds=5 μm ⁻² . It is a diagram for explaining the peak density Sds measured in accordance with EUR15178N, and is a diagram showing an example of the surface and the peak when Sds=1 μm ⁻² . FIG. 2 is a diagram for explaining a load curve and a load area ratio determined in accordance with JIS B0681-2:2018. FIG. 3 is a diagram for explaining the load area ratio Smr1 that separates the protruding peak portion and the core portion, which is measured in accordance with JIS B0681-2:2018. This is a resin replica image after binarization obtained in Example 3. FIG. 4 is a diagram showing the x-axis, y-axis, z-axis, and slice plane S in FIB-SEM observation and three-dimensional image analysis in relation to the roughened copper foil. It is a slice image of the roughened copper foil of Example 9 after forming markings and a protective film. This is an image for explaining material assignment in three-dimensional image analysis. This is the first inference image generated by machine learning the image in FIG. This is an example of a slice image in which the roughened bottom surface of the roughened copper foil and the roughened particles are continuous. This is an example of a slice image in which the roughened bottom surface of the roughened copper foil and the roughened particles are discontinuous.

Definitions Definitions of terms and parameters used to specify the present invention are shown below.

In this specification, "skewness Ssk" or "Ssk" is a parameter representing the symmetry of height distribution, measured in accordance with JIS B0681-2:2018. When this value is 0, it indicates that the height distribution is vertically symmetrical, in other words, it indicates that bumps (roughening particles, etc.) of uniform size are arranged on the surface. Further, as shown in FIG. 1A, if this value is smaller than 0, it indicates that the surface has many small valleys, or in other words, that thick rounded bumps are lined up on the surface. On the other hand, as shown in FIG. 1B, if this value is greater than 0, it indicates that the surface has many fine mountains, or in other words, that the surface is dotted with elongated bumps.

In this specification, "mountain peak density Sds" or "Sds" is a parameter representing the number of peaks per unit area, measured in accordance with EUR15178N. As shown in FIGS. 2A and 2B, in calculating Sds, a point higher than the eight neighboring points N is regarded as the mountaintop S. The larger this value is, the denser the bumps are (see FIG. 2A). On the other hand, the smaller this value is, the more sparsely the bumps are present (see FIG. 2B).

In this specification, "surface load curve" (hereinafter simply referred to as "load curve") refers to the height at which the load area ratio is from 0% to 100%, determined in accordance with JIS B0681-2:2018. A curve that represents As shown in FIG. 3, the load area ratio is a parameter representing the area of a region having a certain height c or more. The load area ratio at height c corresponds to Smr(c) in FIG. As shown in Figure 4, the secant line of the load curve drawn from the load area ratio of 0% along the load curve with the difference in the load area ratio of 40% is moved from the load area ratio of 0%, and the secant line The position where the slope of is the gentlest is called the center of the surface load curve. The straight line that minimizes the sum of squares of deviations in the vertical axis direction with respect to this central part is called an equivalent straight line. The portion included in the height range of 0% to 100% of the load area ratio of the equivalent straight line is called the core portion. The portion higher than the core portion is called a protruding peak portion, and the portion lower than the core portion is called a protruding trough portion.

In this specification, "load area ratio Smr1 that separates the protruding mountain part and the core part" or "Smr1" refers to the core part measured in accordance with JIS B0681-2:2018, as shown in FIG. This is a parameter that represents the load area ratio at the intersection of the upper height of the surface and the surface load curve (i.e., the load area ratio that separates the core portion from the protruding peak portion).

In this specification, "kurtosis Sku" is a parameter representing the sharpness of the height distribution, which is measured in accordance with JIS B0681-2:2018, and is also referred to as kurtosis. Sku=3 means that the height distribution is a normal distribution, in other words, it shows that bumps of uniform size are lined up on the surface. When Sku>3, there are many sharp peaks and valleys on the surface, in other words, there are many fine bumps standing on the surface. Sku<3 means that the surface is flat, in other words, thick rounded bumps are arranged on the surface.

Ssk, Sds, Smr1 and Sku can be calculated by measuring the surface profile of a predetermined measurement area (for example, a two-dimensional area of 64.397 μm x 64.463 μm) on the roughened surface using a commercially available laser microscope. can. In this specification, it is assumed that Ssk and Smr1 are measured under conditions of a cutoff wavelength of 1.0 μm using an L filter and no cutoff using an S filter. On the other hand, it is assumed that Sds and Sku are measured under conditions where no cutoff is performed using the S filter and the L filter. Other preferable measurement conditions and analysis conditions for the surface profile using a laser microscope will be shown in Examples below.

In this specification, "volume of roughened particles per 1 μm ² " is a value calculated by three-dimensional analysis of an image obtained using FIB-SEM of a roughened surface. This three-dimensional analysis can be preferably performed by the following procedure using commercially available three-dimensional image processing software (for example, Dragonfly (version 2022.1.0.1259) manufactured by Object Research System).
(1) Read the slice image of the roughened copper foil obtained by FIB-SEM and perform alignment.
(2) Perform trimming of the slice image.
(3) Machine learning is performed to extract the Cu portion originating from the roughened copper foil, and a segmentation model is created.
(4) Apply the segmentation model to the slice image and extract the Cu portion.
(5) Extract the roughened particles from the Cu portion based on the root diameter of the roughened particles.
(6) Trim a predetermined analysis area (for example, 4.5 μm x 4.5 μm) and calculate the volume of roughened particles per 1 μm ² .

Preferred measurement conditions and sample preparation methods for FIB-SEM, details of the analysis method using the above-mentioned three-dimensional image processing software, and a specific method for calculating the root diameter of the roughening particles are shown in the Examples below. do.

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

As used herein, the "deposition surface" of an electrolytic copper foil refers to the surface on which electrolytic copper is deposited during production of the electrolytic copper foil, that is, the surface that is not in contact with the cathode.

Roughened Copper Foil The copper foil according to 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 skewness Ssk greater than 0.35. Further, this roughened surface has a peak density Sds of 1.57 μm ⁻² or more and 2.64 μm ⁻² or less. By controlling the skewness Ssk and the peak density Sds within predetermined ranges on the surface of the roughened copper foil in this way, it is possible to achieve both high adhesion with the thermoplastic resin and excellent high frequency characteristics.

As mentioned above, in order to suppress transmission loss in high frequency applications, it is required to make the roughening particles finer in order to reduce the skin effect of copper foil. However, copper foil with such fine roughening particles has poor adhesion with resin as a result of a reduced anchoring effect with the resin base material (i.e., the effect of improving physical adhesion using the unevenness of the surface of the copper foil). It's easy to become a thing. In particular, thermoplastic resins with a low dielectric constant, such as fluororesins and liquid crystal polymers (LCP), have low chemical activity and therefore have low adhesion to copper foil, unlike thermosetting resins. As described above, copper foil with low roughness, which is advantageous in terms of high frequency characteristics, tends to inherently have poor adhesion to resin. On the other hand, according to the roughened copper foil of the present invention, it is possible to unexpectedly achieve both high adhesion with the thermoplastic resin and excellent high frequency characteristics (for example, reduction of skin effect).

Although the mechanism that makes it possible to achieve both high adhesion with resin and excellent high frequency properties is not necessarily clear, it is thought to be, for example, as follows. That is, the larger the value of Ssk of the roughened surface, the more fine peaks there are, that is, the more elongated roughening particles are scattered. Therefore, if the Ssk of the roughened surface is larger than 0.35, the roughened particles will have a fine vertically elongated shape. As a result, compared to conventional approximately spherical roughening particles (Ssk = about 0.2 to 0.3) and uniform roughening particles with extremely low height (Ssk = about 0 to 0.1), It can exhibit a high anchoring effect with thermoplastic resin base materials. Furthermore, the skin effect can be reduced compared to roughening particles that are thick and large in shape (Ssk<0). Furthermore, the roughened surface with a peak density Sds of 1.57 μm ⁻² or more and 2.64 μm ⁻² or less has a moderate density of bumps, and has high adhesion with thermoplastic resin and excellent high frequency characteristics. It can be achieved in a well-balanced manner. That is, the peak density Sds is a parameter representing the number of peaks per unit area as described above, and in other words, it can be said to be a parameter related to the size of the roughened particles on the roughened surface. In this regard, by controlling the peak density Sds of the roughened surface to 1.57 μm ⁻² or more, the size of the roughened particles becomes fine, resulting in a surface shape that is effective in reducing the skin effect. On the other hand, by controlling the peak density Sds of the roughened surface to 2.64 μm ^-2 or less, the size of the roughened particles becomes appropriate, and the surface can exhibit a high anchoring effect with the thermoplastic resin base material. It becomes a shape. As a result, it is thought that it becomes possible to achieve both high adhesion with the thermoplastic resin and excellent high frequency properties.

Therefore, in the roughened copper foil, the Ssk of the roughened surface is greater than 0.35, preferably greater than 0.35 and less than or equal to 0.79, and more preferably greater than or equal to 0.36 and less than or equal to 0.57.

In addition, the roughened copper foil has an Sds of 1.57 μm ⁻² or more and 2.64 μm ⁻² or less, preferably 1.57 μm ⁻² or more and 2.57 μm ⁻² or less, and more preferably 1. .62μm ^-2 or more and 2.57μm ^-2 or less.

It is preferable that the roughened copper foil has a plurality of roughened particles on the roughened surface. In this case, the volume of the roughened particles per 1 μm ² of the roughened surface is preferably 0.11 μm ³ or more and 0.25 μm ³ or less, more preferably 0.11 μm ³ or more and 0.18 μm ³ or less, and even more preferably 0.11 μm ³ or more and 0.16 μm ³ or less. When the volume of the roughened particles per ¹ μm2 is within the above range, the surface shape will have fine roughened particles that are effective in reducing the skin effect, and while ensuring high adhesion with the thermoplastic resin, Even better high frequency characteristics can be achieved.

The roughened copper foil preferably has a Sku of 2.70 or more and 4.90 or less, more preferably 3.00 or more and 4.00 or less, and even more preferably 3.00 or more and 3.60. It is as follows. When Sku is within the above range, high adhesion to the thermoplastic resin and excellent high frequency properties can be achieved in a better balance.

The roughened copper foil preferably has an Smr1 of 11.2% or more on the roughened surface, more preferably 11.2% or more and 13.4% or less, and even more preferably 11.3% or more and 12.4%. % or less. When Smr1 is within the above range, high adhesion to the thermoplastic resin and excellent high frequency properties can be achieved in a better balance.

The thickness of the roughened copper foil is not particularly limited, but is preferably 0.1 μm or more and 35 μm or less, more preferably 0.5 μm or more and 5.0 μm or less, and even more preferably 1.0 μm or more and 3.0 μm or less. Note that the roughened copper foil is not limited to one in which the surface of a normal copper foil is roughened, but may be one in which the surface of a copper foil with a carrier is roughened. Here, the thickness of the roughened copper foil is the thickness that does not include the height of the roughening particles formed on the surface of the roughened surface (the thickness of the copper foil itself that constitutes the roughened copper foil) It is.

The roughened copper foil has a roughened surface on at least one side. That is, the roughened copper foil may have a roughened surface on both sides, or may have a roughened surface only on one side. As described above, the roughened surface preferably includes a plurality of roughened particles (preferably vertically elongated roughened particles), and each of these plurality of roughened particles is more preferably made of copper particles. The copper particles may be made of metallic copper or may be made of a copper alloy.

The roughening treatment for forming the roughened surface can be preferably performed by forming roughening particles of copper or copper alloy on the copper foil. This roughening treatment is preferably performed according to a plating method that involves a two-step plating process. In this case, in the first step plating process, the copper concentration is 5 g/L or more and 9 g/L or less (more preferably 7 g/L or more and 9 g/L or less), and the sulfuric acid concentration is 100 g/L or more and 150 g/L or less (more preferably 100 g/L or more and 150 g/L or less). Electrodeposition is preferably performed using a copper sulfate solution with a tungsten concentration of 5 mg/L or more and 20 mg/L or less (more preferably 10 mg/L or more and 20 mg/L or less). This electrodeposition is carried out at a liquid temperature of 20°C or more and 50°C or less (more preferably 30°C or more and 50°C or less) and a current density of 10 A/ ^dm2 or more and 40 A/dm2 or ^less (more preferably 20 A/ ^dm2 or more and 40 A/dm2 ^{or less)} . (below) and an electrical quantity of 50 A·s to 200 A·s (more preferably 50 A·s to 150 A·s). In particular, in the first step plating process, fine vertically shaped roughened particles are treated by using a copper sulfate solution that has a lower copper concentration than conventional methods and contains inorganic additives within the above concentration range. It becomes easier to form on the surface. In the second plating step, the copper concentration is 40 g/L or more and 70 g/L or less (more preferably 50 g/L or more and 70 g/L or less), and the sulfuric acid concentration is 100 g/L or more and 300 g/L or less (more preferably 150 g/L). Electrodeposition is preferably performed using a copper sulfate solution (250 g/L or less). This electrodeposition is performed at a liquid temperature of 30°C or more and 60°C or less (more preferably 40°C or more and 50°C or less) and a current density of 10 A/ ^dm2 or more and 40 A/dm2 ^{or less} (more preferably 20 A/dm2 or ^more and 40 A/dm2 ^{or less)} . (below), and the plating conditions are preferably 10 A·s or more and 250 A·s or less (more preferably 10 A·s or more and 150 A·s or less). By going through such a plating step, roughened particles convenient for satisfying the above-mentioned surface parameters can be easily formed on the treated surface.

If desired, the roughened copper foil may be subjected to rust prevention treatment and may have a rust prevention treatment layer formed thereon. Preferably, the rust prevention treatment includes plating treatment using zinc. The plating treatment using zinc may be either a zinc plating treatment or a zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably a zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment that contains at least Ni and Zn, and may further contain other elements such as Sn, Cr, and Co. The Ni/Zn adhesion ratio in zinc-nickel alloy plating is preferably 1.2 or more and 10 or less, more preferably 2 or more and 7 or less, and even more preferably 2.7 or more and 4 or less, in terms of mass ratio. Moreover, it is preferable that the rust prevention treatment further includes chromate treatment, and it is more preferable that this chromate treatment is performed on the surface of the plating containing zinc after the plating treatment using zinc. By doing so, the rust prevention properties can be further improved. A particularly preferred anticorrosion treatment is a combination of zinc-nickel alloy plating treatment followed by chromate treatment.

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 makes it possible to improve moisture resistance, chemical resistance, adhesion to adhesives, and the like. The silane coupling agent layer can be formed by appropriately diluting a silane coupling agent, applying it, and drying it. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltrimethoxysilane, N-(2- aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. Amino-functional silane coupling agents, or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane, or olefin-functional silane coupling agents such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacrylic Examples include acrylic-functional silane coupling agents such as roxypropyltrimethoxysilane, or imidazole-functional silane coupling agents such as imidazole silane, or triazine-functional silane coupling agents such as triazine silane.

For the reasons mentioned above, it is preferable that the roughened copper foil further includes a rust prevention treatment layer and/or a silane coupling agent layer on the roughening treatment surface, and more preferably, a rust prevention treatment layer and/or a silane coupling agent layer. Have both. When a rust prevention treatment layer and/or a silane coupling agent layer are formed on the roughening treatment surface, the numerical values of various parameters of the roughening treatment surface in this specification are based on the rust prevention treatment layer and/or the silane coupling agent layer. It means the numerical value obtained by measuring and analyzing the roughened copper foil after the treatment layer has been formed. The rust prevention 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.

Copper Foil with Carrier As mentioned above, the roughened copper foil of the present invention may be provided in the form of a copper foil with a carrier. That is, according to a preferred embodiment of the present invention, the method includes a carrier, a release layer provided on the carrier, and the roughened copper foil provided on the release layer with the roughened surface facing outward. A copper foil with a carrier is provided. However, the carrier-attached copper foil may have any known layer structure, except for using the roughened copper foil of the present invention.

The carrier is a support for supporting the roughened copper foil to improve its handling properties, and a typical carrier includes a metal layer. Examples of such carriers include aluminum foil, copper foil, stainless steel (SUS) foil, resin films whose surfaces are metal-coated with copper or the like, glass, and the like, with copper foil being preferred. The copper foil may be either a rolled copper foil or an electrolytic copper foil, but preferably an electrolytic copper foil. The thickness of the carrier is typically 250 μm or less, preferably 9 μm or more and 200 μm or less.

The peeling layer is a layer that has the function of weakening the peeling strength of the carrier, ensuring the stability of this strength, and further suppressing mutual diffusion that may occur between the carrier and the copper foil during press molding at high temperatures. . Although the release layer is generally formed on one side of the carrier, it may be formed on both sides. The release layer may be either an organic release layer or an inorganic release layer. Examples of organic components used in the organic release layer include nitrogen-containing organic compounds, sulfur-containing organic compounds, carboxylic acids, and the like. Examples of the nitrogen-containing organic compound include triazole compounds, imidazole compounds, etc. Among them, triazole compounds are preferred because they have easy releasability. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N',N'-bis(benzotriazolylmethyl)urea, 1H-1,2,4-triazole and 3-amino- Examples include 1H-1,2,4-triazole. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiocyanuric acid, 2-benzimidazolethiol, and the like. Examples of carboxylic acids include monocarboxylic acids, dicarboxylic acids, and the like. On the other hand, examples of inorganic components used in the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and a chromate-treated film. The release layer may be formed by, for example, bringing a release layer component-containing solution into contact with at least one surface of the carrier to fix the release layer component on the surface of the carrier. When the carrier is brought into contact with the release layer component-containing solution, this contact may be carried out by dipping the carrier in the release layer component-containing solution, spraying the release layer component-containing solution, flowing down the release layer component-containing solution, or the like. In addition, it is also possible to adopt a method of forming a film with the release layer component by a vapor phase method such as vapor deposition or sputtering. Further, the release layer component may be fixed to the carrier surface by adsorption or drying of a solution containing the release layer component, or by electrodeposition of the release layer component in the solution containing the release layer component. The thickness of the release layer is typically 1 nm or more and 1 μm or less, preferably 5 nm or more and 500 nm or less.

If desired, other functional layers may be provided between the release layer and the carrier and/or the roughened copper foil. Examples of such other functional layers include auxiliary metal layers. Preferably, the auxiliary metal layer consists of nickel and/or cobalt. By forming such an auxiliary metal layer on the surface side of the carrier and/or the surface side of the roughened copper foil, it is possible to reduce the risk of problems occurring between the carrier and the roughened copper foil during hot press forming at high temperatures or for long periods of time. Mutual diffusion can be suppressed and the stability of carrier peel strength can be ensured. The thickness of the auxiliary metal layer is preferably 0.001 μm or more and 3 μm or less.

Copper-clad laminate The roughened copper foil of the present invention is preferably used for producing 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 roughened copper foil is provided. By using the roughened copper foil of the present invention, it is possible to achieve both high adhesion to the thermoplastic resin base material and excellent high frequency characteristics in the processing of copper-clad laminates. This copper-clad laminate includes 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 side or both sides of the resin layer. The resin layer contains a resin, preferably an insulating resin. Preferably, the resin layer is a prepreg and/or a resin sheet. Prepreg is a general term for composite materials in which a base material such as a synthetic resin plate, glass plate, glass woven fabric, glass nonwoven fabric, or paper is impregnated with synthetic resin. Further, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation properties. 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 the roughened copper foil via a primer resin layer that is previously applied to the surface of the copper foil.

From the viewpoint of providing a copper-clad laminate suitable for high frequency applications, the resin layer preferably contains a thermoplastic resin, and more preferably most (for example, 50% by weight or more) or most ( For example, 80% by weight or more or 90% by weight or more) is thermoplastic resin. Preferred examples of thermoplastic resins include polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), liquid crystal polymer (LCP), polyetheretherketone (PEEK), and thermoplastic polyimide (PI). , polyamideimide (PAI), fluororesin, polyamide (PA), nylon, polyacetal (POM), modified polyphenylene ether (m-PPE), polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), cycloolefin (COP), and any combination thereof. From the viewpoint of desirable dielectric loss tangent and excellent heat resistance, more preferable examples of thermoplastic resins include polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), liquid crystal polymer (LCP), and polysulfone. Examples include etheretherketone (PEEK), thermoplastic polyimide (PI), polyamideimide (PAI), fluororesin, and any combination thereof. From the viewpoint of low dielectric constant, particularly preferred thermoplastic resins are liquid crystal polymers (LCP) and/or fluororesins. Preferred examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene/hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene. copolymers (ETFE), and any combination thereof. In addition, it is preferable to attach the insulating resin base material to the roughened copper foil by pressing while heating.This softens the thermoplastic resin and allows it to penetrate into the fine irregularities of the roughened surface. can be set. As a result, the adhesion between the copper foil and the resin can be ensured due to the anchor effect caused by the fine irregularities (particularly the vertically elongated roughened particles) biting into the resin.

Printed Wiring Board The roughened copper foil of the present invention is preferably used for producing printed wiring boards. That is, according to a preferred embodiment of the present invention, a printed wiring board including the roughened copper foil is provided. By using the roughened copper foil of the present invention, it is possible to achieve both excellent high frequency characteristics and high circuit adhesion in the manufacture of printed wiring boards. The printed wiring board according to this embodiment includes a layered 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. Further, the resin layer is as described above regarding the copper-clad laminate. In any case, the printed wiring board may have a known layer structure, except for using the roughened copper foil of the present invention. 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 adhered to one or both sides of prepreg to form a cured laminate, and circuits are formed on the cured laminate, and multilayered versions of these. Examples include multilayer printed wiring boards. Further, other specific examples include flexible printed wiring boards, COF, TAB tapes, etc. in which a circuit is formed by forming the roughened copper foil of the present invention on a resin film. As another specific example, 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. After that, build-up wiring boards in which circuits are formed using methods such as modified semi-additive method (MSAP) or subtractive method using the roughened copper foil as all or part of the wiring layer, and the roughened copper foil are removed. Examples include a build-up wiring board in which a circuit is formed using a semi-additive method (SAP), and a direct build-up on wafer in which lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit. More advanced examples include antenna elements in which the resin-coated copper foil is laminated onto a base material to form a circuit, electronic materials for panels and displays, and windows in which patterns are formed by laminating the resin-coated copper foil onto glass or resin film via an adhesive layer. Examples include electronic materials for glass, electromagnetic shielding films made by applying a conductive adhesive to the roughened copper foil of the present invention, and the like. In particular, printed wiring boards equipped with the roughened copper foil of the present invention can be used in applications such as automotive antennas, mobile phone base station antennas, high-performance servers, and collision prevention radars used in high frequency bands of signal frequencies of 10 GHz or higher. It is suitably used as a high frequency substrate.

The present invention will be explained in more detail with reference to the following examples.

Examples 1 to 11
The roughened copper foil of the present invention was manufactured as follows.

(1) Preparation of electrolytic copper foil A sulfuric acid copper sulfate solution with the composition shown below is used as the copper electrolyte, a titanium electrode with a surface roughness Ra of 0.20 μm is used as the cathode, and a DSA (dimensions: Using a stable anode), electrolysis was carried out at a solution temperature of 45° C. and a current density of 55 A/dm ² to obtain an electrolytic copper foil with a thickness of 18 μm.
<Composition of sulfuric acid acidic copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 260g/L
- Bis(3-sulfopropyl) disulfide concentration: 30mg/L
- Diallyldimethylammonium chloride polymer concentration: 50mg/L
- Chlorine concentration: 40mg/L

(2) Roughening treatment The deposition surface of the obtained electrolytic copper foil was subjected to a roughening treatment. As shown in Table 1, this roughening treatment is a two-stage roughening treatment (first roughening treatment and second roughening treatment) for Examples 1 to 6 and 8 to 11, and a one-stage roughening treatment for Example 7. A roughening treatment (first roughening treatment) was performed. At this time, by appropriately changing the composition of the acidic copper sulfate solution and the electrodeposition conditions as shown in Table 1, various samples with different characteristics of the roughened surface were prepared.

Specifically, the conditions for the roughening treatment at each stage were as follows.
- In the first roughening treatment, sulfuric acid, copper sulfate, and optionally sodium tungstate as an inorganic additive (Examples 1 to 6, 8, and 9 Electroplating was carried out using an acidic copper sulfate solution containing ) under the electrodeposition conditions (liquid temperature, current density, and quantity of electricity) shown in Table 1.
- In the second roughening treatment, an acidic copper sulfate solution containing sulfuric acid and copper sulfate was used under the electrodeposition conditions (liquid temperature, current Electroplating was carried out at the following density and electrical charge).

(3) Rust prevention treatment The roughened surface of the electrolytic copper foil was subjected to rust prevention treatment consisting of zinc-nickel alloy plating treatment and chromate treatment. First, a zinc-nickel alloy plating treatment was performed using a solution containing a zinc concentration of 1 g/L, a nickel concentration of 2 g/L, and a potassium pyrophosphate concentration of 80 g/L under conditions of a liquid temperature of 40°C and a current density of 0.5 A/ ^dm2 . I did it. Next, the surface subjected to the zinc-nickel alloy plating treatment was subjected to chromate treatment using an aqueous solution containing 1 g/L of chromic acid under conditions of pH 12 and current density of 1 A/dm ² .

(4) Silane coupling agent treatment An aqueous solution of 3-aminopropyltrimethoxysilane with a concentration of 6 g/L is adsorbed on the roughened surface of the electrolytic copper foil, and the water is evaporated with an electric heater to form a silane cup. Ring agent treatment was performed. At this time, the silane coupling agent treatment was not performed on the surface of the electrolytic copper foil that had not been subjected to the roughening treatment.

The roughened copper foils produced in Evaluation Examples 1 to 11 were subjected to various evaluations as shown below.

<Surface quality 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 JIS B0681-2:2018 (Ssk, Sku and Smr1) or EUR15178N (Sds). The 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 Ssk, Sku, and Smr1 were calculated. For each example, the above parameters were calculated in 10 different visual fields, and the average value in all the visual fields was adopted as the surface texture parameter of the roughened surface of the sample. The results were as shown in Table 3.

On the other hand, Sds was calculated as follows. First, the measurement data obtained with the laser microscope described above is loaded into the analysis software (Olympus Corporation, "OLS5100 LEXT (version 2.1.2.215)"), and the unprocessed data is converted to the LEXT file format. Output was performed. This LEXT file was read and analyzed using another analysis software (Digital Surf, "MountainsMap (version 9.0.9878)") (analysis area: 64.397 μm x 64.463 μm). Specifically, the "parameter table" and "default settings" were selected in this order from the analysis target tab to display the parameter analysis screen. On the parameter analysis screen, we selected "EUR15178N" as the standard, "linear surface" as the wavelength processing, "least squares surface" as the F operation for shape removal, and "Sds" and "Sa" as the parameters. . On the other hand, in this screen, the S filter and the L filter were not selected (that is, there was no cutoff by the S filter and the L filter). Thereafter, "Export analysis results" was selected to save the analysis results, and the mountaintop density Sds and arithmetic mean height Sa were read from the analysis results, respectively. For each example, the above parameters were calculated in 10 different fields of view. To remove noise, out of the 10 visual fields, we excluded two visual fields, one visual field where the arithmetic average height Sa was the maximum value, and one visual field where the arithmetic average height Sa was the minimum value, and the remaining 8 visual fields. The average value of Sds in the visual field was adopted as the Sds of the roughened surface of the sample. The results were as shown in Table 3.

<Root diameter of roughening particles>
The root diameter of the roughening particles used in the three-dimensional analysis of slice images to be described later was calculated as follows. First, prepreg (manufactured by Panasonic Corporation, R-5670NF, 45 μm thick x 2 sheets) was prepared as a resin film. The obtained roughened copper foils were laminated so that their roughened surfaces were in contact with the resin film, and using a vacuum press machine, they were pressed at a pressure of 3.0 MPa, a temperature of 190°C, and a pressing time of 90 minutes. Pressing was performed to produce a copper-clad laminate. The roughened copper foil was removed from this copper-clad laminate using a cupric chloride etching solution. In this way, a resin film (hereinafter referred to as "resin replica") having a surface onto which the surface shape of the roughened surface was transferred was obtained. Thereafter, using a Schottky field emission scanning electron microscope (FE-SEM, manufactured by JEOL Ltd., JSM-7900F), the transfer surface of the resin replica was Observation was performed from the vertical direction (Tilt: 0°), and a resin replica image (image size: 1280 pixels x 1024 pixels) was obtained.

Image analysis was performed on the obtained resin replica image using image analysis software (manufactured by Nireco Co., Ltd., "LUZEX (version 1.60.8.2)") as follows. In this image analysis, an area of 1260 pixels x 940 pixels (=10.25 μm ² ) excluding the imaging information area from the obtained resin replica image was targeted for analysis. First, a binarization process was performed on the resin replica image under the condition of a threshold value of 125. For reference, the resin replica image after binarization obtained in Example 3 is shown in FIG. As shown in FIG. 5, in the resin replica image after binarization, the area displayed in black was regarded as the root portion R of the transferred roughening particles. Next, the following filtering processes (1) to (5) were performed in this order on the binarized resin replica image.
(1) Snowball filter DILATE strength 2
(2) Logical filter SHRINK strength 1
(3) Logical filter FILLHOLES
(4) Logical filter THIN strength 1
(5) Logical filter CIRCLE strength 3

In the resin replica image after filter processing, among the root portions R of the roughened particles, those having an equivalent circle diameter of less than 0.05 μm were removed as noise. The above operation was performed in three different fields of view, and a boxplot of equivalent circle diameters at the root portions R of all the observed roughened particles excluding the noise was created. In this boxplot, the maximum value (the edge of the whiskers) after excluding outliers was taken as the root diameter of the roughened particles. Note that an outlier in a boxplot is defined as Q, where Q ₁ is the first quartile, Q ₃ is the third quartile, and IQR is the interquartile range (=Q ₃ - _{Q 1} ). It is defined as a number greater than ₃ + 1.5 x IQR or less than Q ₁ - 1.5 x IQR.

<Acquisition of slice images>
Slice images were acquired under the following measurement conditions using a FIB-SEM device (Carl Zeiss, Crossbeam 540, SEM and FIB simultaneous control: Atlas Engine v5.5.3). This slice image is acquired by defining the x-axis and z-axis as in-plane directions of the roughened copper foil 10, and the y-axis as the thickness direction of the roughened copper foil 10, as shown in FIG. Then, by acquiring a cross-sectional image of the roughened copper foil 10 at a slice plane S parallel to the xy plane, and acquiring a cross-sectional image while translating this slice plane by 10 nm in the z-axis direction. went. The observation area was x:y:z=19.5μm:19.5μm:9.5μm.

(FIB processing conditions)
- Acceleration voltage: 30kV
- Slice thickness: 10 nm (distance between slice surfaces S)
(SEM observation conditions)
- Accelerating voltage: 1.0kV
- Working distance: 5mm
- Tilt: 54° (with SEM image tilt correction)
- Pixel size: 5nm x 5nm
- Detector: INLENSE detector

In addition, in the three-dimensional image analysis described below, from the viewpoint of facilitating alignment for reconstructing slice images into three-dimensional images, the following processing is performed on the roughened copper foil 10 before acquiring the slice images. I did it. For reference, FIG. 7 shows an example of a slice image of the roughened copper foil of Example 9 in which the treatment was performed. First, a thermosetting resin 14 (epoxy (G-2), manufactured by Gatan, Inc.) was applied to the roughened surface of the roughened copper foil 10 so that the roughened particles 12 were completely buried ( Coating thickness: 2.0 μm or more and 4.5 μm or less). The thermosetting resin 14 was cured by heating the roughened copper foil 10 coated with the resin at 120° C. for 20 minutes under vacuum, and then cooled to room temperature. The roughened copper foil 10 after cooling is put into the above-mentioned FIB-SEM device, and using the deposition function of the FIB, a platinum film 16 (thickness 1 .0 μm or more and 1.5 μm or less). Then, using the etching function of the FIB, the surface (xz plane) of the platinum film 16 is etched in the z-axis direction so that the same markings (three wedge shapes) can be visually recognized in each slice image. Processing was performed along the line to form a marking M. At this time, the machining depth in the y-axis direction was set to two-thirds or less of the thickness of the formed platinum film 16. Thereafter, in order to protect the formed markings M, a carbon film 18 (about 1 μm thick) was formed on the surface of the platinum film 16 using the FIB deposition function. Hereinafter, the platinum film 16 and the carbon film 18 will be collectively referred to as the "protective film 20."

<Three-dimensional analysis of slice images>
Using the three-dimensional image processing software "Dragonfly (version 2022.1.0.1259)" (manufactured by Object Research System), three-dimensionally analyzed the slice image data of the roughened copper foil obtained by FIB-SEM, The volume of roughened particles per 1 μm ² was calculated. At this time, the analysis area was set to x:z=4.5 μm:4.5 μm, and y was set to be arbitrary (depending on the size of the roughened particles). In addition, the number of fields of view for analysis was set to 1. In this three-dimensional analysis, the following steps (1) to (6) were performed in this order, as detailed below.
(1) Loading and aligning slice images (2) Trimming slice images (3) Creating a segmentation model using machine learning (4) Extracting the Cu portion from roughened copper foil (5) Extracting roughened particles ( 6) Trimming the analysis area and calculating the volume of roughening particles

(1) Reading and positioning of slice images The slice image data of the roughened copper foil obtained by FIB-SEM was read into the three-dimensional image processing software. At this time, "X:Y:Z=0.005:0.005:0.01" was input as the voxel size in "Image Spacing (in μm)".

In order to perform positioning for three-dimensional reconstruction, "Slice Registration" was selected on the loaded image data. Then, "Template Matching" of the "Registration method" was selected, and the template range was specified so as to include only the portion where the marking M of the protective film 20 was formed (the broken line portion in FIG. 7). After selecting "Apply" and automatically aligning, all images were checked, and only those areas where the positions were significantly shifted were manually aligned. Manual alignment was performed by changing the above-mentioned "Registration method" to "Manual" and then moving the next slice image displayed in red toward the displayed slice image data.

(2) Trimming of slice image In order to shorten processing time, the portion of the protective film 20 that is unnecessary for calculating the volume of the roughened particles 12 was removed by trimming. This trimming is performed by selecting "Crop..." under "Modify and Transform" and then removing the protective film 20 from the frame of the displayed XY section and YZ section in the three-dimensional reconstructed image. This was done by moving like this. By selecting the "Create new" checkbox and selecting "Apply" and "Close" in this order, deletion of the unnecessary portion was completed.

(3) Creating a segmentation model using machine learning In order to extract the Cu portion derived from the roughened copper foil, which will be described later, a segmentation model was created using machine learning as described below. Note that, as described later, this creation of a segmentation model using machine learning may be performed for a representative sample among the samples to be analyzed.

(3-1) Assigning materials Select "Segmentation Wizard" and "Continue" in order on the image data after trimming, and select the roughened copper foil 10, roughened particles 12, and other parts (thermosetting resin 14, etc.). ) The slice image was enlarged to show part of the image. From "Add new frame", the enlarged image was selected as the target area for machine learning. In "Classes and labels", enter "Cu" as the name of the area where the material is copper (roughened copper foil 10 and roughened particles 12), and enter the name of the area where the material is other than copper (for example, resin). ``Resin'' was input as ``Resin''. Note that in order to easily distinguish each region, different colors (for example, pink and green) were specified for the "Cu" region and the "Resin" region.

(3-2) Machine learning Machine learning was performed for each material area as follows. For reference, an example of the display screen after material assignment is shown in FIG. First, "Round Brush" was selected from "2D view tools". At this time, "Brush type" was set to "Full". In order to have the software recognize the "Resin" region, a rough range was designated with ○ marks ("14a" in FIG. 8) so as not to deviate from the thermosetting resin 14. Next, in order to make the software recognize the "Cu" region, a rough range was designated with ○ marks ("10a" in FIG. 8) so as not to deviate from the roughened copper foil 10 or the roughened particles 12. Note that in this step, as long as the range is specified so as not to deviate from the area of each material, the thickness of "Brush" (the size of the circle mark) will not affect machine learning. Then, "Train" was selected to start machine learning. In the displayed "Model Generation Strategy", "High Accuracy" was selected. Three types of segmentation models for image processing were selected: "Random Forest,""U-net," and "Sensor 3D.""Continue" was selected to generate the first inference image. Note that "U-net" and "Sensor 3D" are skipped in the first inference image generation.

(3-3) Creation of teacher images The inference images of "Cu" and "Resin" generated by "Random Forest" were selected. For reference, an example of the first inference image is shown in FIG. This inferred image and the original slice image were compared, and the areas where the "Cu" and "Resin" areas were misaligned were enlarged until 1 pixel could be confirmed. A teacher image was then created by manually correcting the area. This correction method is similar to the range specification method for the "Cu" and "Resin" regions, but this time correction was performed accurately in units of 1 pixel. After that, we selected "Train" and performed machine learning again using three types of segmentation models: "Random Forest,""U-net," and "Sensor 3D."

(3-4) Creating a segmentation model Check the “Score” on the “Models” tab and select the inference image with the highest “Score” from among “Random Forest”, “U-net” and “Sensor 3D”. . This inference image was compared with the original slice image, and the locations where the "Cu" and "Resin" regions were misaligned were enlarged until 1 pixel could be confirmed. A new teacher image was then created by manually correcting the area again. After that, after moving to another slice image and enlarging the slice image so that a part of the roughened copper foil 10, roughened particles 12, and other parts (thermosetting resin 14, etc.) are displayed, From "Add new frame", the enlarged image was selected as the target area for machine learning. Then, "Predict" was selected, and an inference image was generated by reflecting the results of the new teacher image described above. A segmentation model was created by repeating the above operations until the "Score" of the inference image became 0.98 or higher. This time, as shown in FIG. 10A, a slice image in which the roughened bottom surface B of the roughened copper foil 10 and the roughened particles 12 are continuous (connected), and as shown in FIG. 10B, the roughened bottom surface B and the roughened particles 12 are A segmentation model was created using a slice image in which the roughened bottom surface B of the treated copper foil 10 and the roughened particles 12 are discontinuous (not connected). Then, as the segmentation model that is the final inference image, the one with the highest "Score" out of "U-net" and "Sensor 3D" was adopted.

(4) Extraction of Cu portion derived from roughened copper foil The “Cu” region derived from roughened copper foil 10 and roughened particles 12 was extracted as follows. The created segmentation model and slice image data reflecting the segmentation model were selected. "Preview" was selected to confirm whether the "Cu" region and "Resin" region of the generated image were properly identified. Thereafter, "All Slices" was selected from "Segment" to apply the segmentation model to all slice image data. Note that when the segmentation model is appropriate, the "Cu" region and the "Resin" region are colored with specified different colors (for example, pink and green). If the segmentation model is inappropriate, a segmentation model is created again for the image data of the sample in the same manner as in (3) above. This time, segmentation models were created for Examples 1, 5, 7, and 11.

The three-dimensionally reconstructed image was checked, and if there was a part in the "Resin" area that was incorrectly recognized as "Cu", it was manually identified as a "Resin" area. The method for identifying this area is the same as the range specification method for the "Cu" area and "Resin" area in (3-1) above, but this time identification was performed in units of 1 pixel. Thereafter, "Resin" was selected from "Classes and labels" in "2D view tools" and "Resin" was deleted by "Remove". In "Data Properties and Settings", "New ROI" was selected on the image from which "Resin" was deleted, and "ROI" was generated by extracting only the "Cu" portion. Here, "ROI" means "a partial region of interest in an image" to which filter processing or recognition processing is applied. If there are cavities (uncolored areas) in "Cu", the roughening particles 12 cannot be extracted accurately, so select the generated "ROI" and select "Fill inner areas: 3D" in "ROI tools". ” and clicked “Apply” to perform the process of filling the cavity.

(5) Extraction of roughened particles "ROI" that filled the cavities in "Cu" was selected. By selecting "Invert" from "ROI Tools" in the "Segment" tab and inverting the measurement target from the "Cu" part to the spatial part, "Air" (other than "Cu" excluding "Resin") A "ROI" of the spatial part) was generated. On the generated "ROI" of "Air", "Fill Connected Pores with a Diameter Smaller Than..." in "Refine Region of Interest" was selected. The root diameter of the roughened particles 12 described above was entered as a threshold value in the displayed window, and the roughened bottom surface B of the roughened copper foil 10 and the roughened particles 12 were separated. In this way, an "ROI" of roughened particles 12 containing "Air" was generated. In addition, if the above-mentioned threshold value is too large, the roughened particles 12 will be cut into pieces including the roughened bottom surface B of the roughened copper foil 10, which is not appropriate. On the other hand, if the threshold value is too small, the portion to be cut will penetrate into the roughening particles 12, which is not appropriate. Therefore, as described above, the maximum value excluding outliers in the boxplot was adopted as the root diameter of the roughening particles 12. In order to fill the cavity of the "ROI" of the generated roughening particles 12 containing "Air", "Apply" of "Fill inner areas: 3D" was selected.

Only the roughened particles 12 were extracted from the roughened particles 12 containing "Air" as follows. "Erode" of "Morphological operations" was selected from "ROI Tools" in the "Segment" tab, and fine adjustments were made to the separation of the roughened particles 12 and the roughened bottom surface B. At this time, the conditions were as follows.
(Separation conditions)
- Dimensionality: 2D (Z)
- Shape: Square
- Range: Not input - Kernel size: 3
Note that "2D (Z)" in the above conditions means that the selected "ROI" is processed along the z-axis.

After the above segmentation, "Apply" of "Fill inner areas: 3D" was selected to fill the cavity of 1 pixel. The above cutting operation and cavity filling operation were repeated, and the roughening particles 12 and the roughening bottom surface B were finely adjusted twice in total. This fine-tuning was always done a total of two times for each example. Select the "ROI" generated after the adjustment as "(A)", select the "ROI" of "Air" as "(B)", and then select "A-B" to roughly An "ROI" was created by extracting only 12 portions of the particles.

(6) Trimming of analysis region and calculation of volume of roughened particles In "ROI" where only 12 portions of roughened particles were extracted, "Crop..." in "Modify and Transform" was selected. Then, enter the values in "Min" and "Max" so that "Size" of "X" becomes 900 (=4.5 μm) and "Size" of "Z" becomes 450 (=4.5 μm). , an analysis area (X:Z=4.5 μm:4.5 μm) was determined. At this time, "Min" and "Max" were set so that the analysis region did not include the edges. After selecting the "Create new" checkbox, "Apply" was selected to trim the analysis area. Then, the value (μm ³ ) displayed in “Volume (Labeled voxels)” in “Statistical properties” was read as the total volume V of the roughening particles. The volume of the roughened particles per 1 μm ² was calculated by dividing the total volume V of the roughened particles by the area A (=20.25 μm ² ) of the analysis region (=V/A). The results were as shown in Table 3.

<Peel strength against thermoplastic resin (liquid crystal polymer)>
A liquid crystal polymer (LCP) film (manufactured by Kuraray Co., Ltd., Vector CT-Q, thickness 50 μm x 1 sheet) was prepared as a thermoplastic resin base material. The obtained roughened copper foil was laminated on this thermoplastic resin base material so that its roughened surface was in contact with the resin base material, and using a vacuum press machine, press pressure was 4 MPa, temperature was 330°C, Pressing was performed under conditions of a pressing time of 10 minutes to produce a copper-clad laminate. A circuit was formed on this copper-clad laminate by a subtractive method using a cupric chloride etching solution to produce a test board having a linear circuit with a width of 3 mm. The formed test board was tested using a tabletop precision universal testing machine (AGS-50NX, manufactured by Shimadzu Corporation) in accordance with JIS C 5016-1994 method A (90° peeling). The film was peeled off from the thermoplastic resin base material to measure normal peel strength (kgf/cm). When this peel strength was 0.60 kgf/cm or more, it was determined to be acceptable. The results were as shown in Table 3.

<Evaluation of transmission characteristics>
High-frequency base materials (MEGTRON6N, manufactured by Panasonic Corporation, 45 μm thick x 2 sheets) were prepared as insulating resin base materials. The obtained roughened copper foil was laminated on both sides of this insulating resin base material so that the roughened surface was in contact with the insulating resin base material, and a vacuum press was used to press the foil at a pressure of 3 MPa and a temperature of 190°C. Pressing was performed under the conditions of 90 minutes of pressing time to obtain a copper-clad laminate. Thereafter, a circuit was formed on the copper-clad laminate by a subtractive method (circuit height: 18 μm, circuit width: 300 μm, circuit length: 300 mm) using a cupric chloride etching solution. In this way, a substrate for transmission loss measurement was obtained in which a microstrip line was formed so that the characteristic impedance was 50Ω±2Ω. The obtained transmission loss measurement board was measured using a network analyzer (manufactured by Keysight Technologies, N5225B) under the following setting conditions, and the transmission loss L ₁ (dB) at 50 GHz was measured. Then, the rate of increase in transmission loss L ₁ (=L ₁ /L ₀ ) with respect to transmission loss L ₀ (dB) at 50 GHz in Example 7 (comparative example) was calculated. When this transmission loss increase rate was 1.10 or less, it was determined to be acceptable. The results were as shown in Table 3.
(Setting conditions)
-IF Bandwidth: 100Hz
-Frequency: 10MHz ~ 50GHz
-Data points: 501 points
- Average: Off
- Calibration method: SOLT (e-cal)

Claims (8)

A roughened copper foil having a roughened surface on at least one side,
The roughened surface has a skewness Ssk greater than 0.35 and a peak density Sds of 1.57 μm ⁻² or more and 2.64 μm ^{−2 or} less,
The Ssk is a value measured in accordance with JIS B0681-2:2018 without cutoff with an S filter and with a cutoff wavelength of 1.0 μm using an L filter,
The above-mentioned Sds is a value measured in accordance with EUR15178N without cutoff using an S filter and an L filter, and is a roughened copper foil. The roughened surface has a plurality of roughened particles, and the volume of the roughened particles per 1 μm ² is 0.11 μm ³ or more and 0.25 μm ³ or less,
The roughening particle according to claim 1, wherein the volume of the roughened particles per 1 μm ² is a value calculated by three-dimensional analysis of an image obtained using FIB-SEM of the roughened surface. Chemically treated copper foil. The roughened surface has a kurtosis Sku of 2.70 or more and 4.90 or less,
The roughened copper foil according to claim 1 or 2, wherein the Sku is a value measured in accordance with JIS B0681-2:2018 without cutoff by an S filter and an L filter. The roughened surface has a load area ratio Smr1 of 11.2% or more that separates the protruding peak portion and the core portion,
The Smr1 according to claim 1 or 2 is a value measured under conditions of a cutoff wavelength of 1.0 μm using an L filter and no cutoff using an S filter in accordance with JIS B0681-2:2018. Roughened copper foil. The roughened copper foil according to claim 1 or 2, further comprising a rust prevention treatment layer and/or a silane coupling agent layer on the roughened surface. A carrier comprising a carrier, a release layer provided on the carrier, and the roughened copper foil according to claim 1 or 2, provided on the release layer with the roughened surface facing outward. With copper foil. A copper-clad laminate comprising the roughened copper foil according to claim 1 or 2. A printed wiring board comprising the roughened copper foil according to claim 1 or 2.

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