WO2023190833A1

WO2023190833A1 - Surface-treated copper foil, copper-clad laminate plate, and printed wiring board

Info

Publication number: WO2023190833A1
Application number: PCT/JP2023/013104
Authority: WO
Inventors: 周介片平; 淳篠崎; 正靖笠原
Original assignee: 古河電気工業株式会社
Priority date: 2022-03-30
Filing date: 2023-03-30
Publication date: 2023-10-05
Also published as: JPWO2023190833A1; TW202407162A

Abstract

Provided is a surface-treated copper foil in which circuit workability is excellent and transmission loss and generation of foreign matter are less likely to occur. When the optical roughness of the surface (20a) of a surface treatment layer (20) of the surface-treated copper foil (30) is measured according to the method stipulated in ISO25178, the arithmetic mean roughness Sa is 0.04-0.30 μm inclusive. A resin member (40) is affixed onto the surface treatment layer (20) of the surface-treated copper foil (30) and then the surface-treated copper foil (30) is removed by etching, and a measurement of the distilled water contact angle θ1 is carried out according to the sessile drop method stipulated in JIS R3257:1999 on a transfer surface (40a) of the remaining resin member (40), which is the surface to which the surface-treated copper foil (30) was affixed. A measurement of the distilled water contact angle θ0 is carried out on a non-transfer surface of the resin member (40) yet to be affixed onto the surface-treated copper foil (30), the non-transfer surface being the surface onto which the surface-treated copper foil (30) is to be subsequently affixed. The difference θ0-θ1 between the contact angles θ0 and θ1 is 5-35° inclusive.

Description

Surface-treated copper foil, copper-clad laminates, and printed wiring boards

The present invention relates to a surface-treated copper foil that can be suitably used for manufacturing printed wiring boards and the like, as well as a copper-clad laminate and a printed wiring board using the surface-treated copper foil.

In recent years, signals have become increasingly high-frequency, and high-frequency signals are increasingly being transmitted to printed wiring boards mounted on electronic devices. Therefore, with regard to surface-treated copper foil used as a material for printed wiring boards, in order to reduce the transmission loss of high-frequency signals, it is being considered to reduce the roughness of the surface (see, for example, Patent Document 1).
Furthermore, as printed wiring boards become more densely packaged and multifunctional, circuits are becoming increasingly finely wired. A surface-treated copper foil with good circuit workability is required for forming fine wiring, and in order to improve circuit workability, it is being considered to reduce the roughness of the surface (for example, Patent Document 2) ). In addition, there are other factors such as improvements in the metal surface treatment of copper foil (see, for example, Patent Document 3) and improvements in the shape of the unevenness transferred to the resin surface (see, for example, Patent Documents 4 and 5). It is being considered.

Japanese Patent Publication No. 210521, 2019 Japanese Patent Publication No. 20117, 2017 Japanese Patent Publication No. 81913, 2019 Japanese Patent Publication No. 6945523 International Publication No. 2020/105289

However, even if the surface roughness of the surface-treated copper foil is reduced, the desired fine wiring may not be obtained in some cases. Traditionally, the etching factor determined from the bottom width, top width, and height of the circuit has been widely used as an index to express circuit processability, but in addition to this, the angle of the tangent at the bottom edge of the circuit is also important. I've come to understand. In other words, even if the etching factor is a value conventionally evaluated as good, the angle of the tangent at the bottom edge of the circuit is small (i.e., the bottom width is larger than the top width of the circuit, and the cross section of the circuit is When viewed from a microscopic perspective, migration may occur, which is expected to be caused by poor etching at the interface at the edge of the circuit, resulting in a widened shape, and the angle of the tangent at the bottom edge of the circuit may occur. The smaller the value, the more likely migration was to occur.

Furthermore, in our study, we reduced the surface roughness of the surface-treated copper foil, and after etching and removing the surface-treated copper foil of the copper-clad laminate, we laminated a resin base material and printed wiring. In the process of manufacturing the board, a new problem has become clear: foreign matter is likely to occur between the resin base material that makes up the copper-clad laminate and the resin base material that is later laminated.
An object of the present invention is to provide a surface-treated copper foil, a copper-clad laminate, and a printed wiring board that have excellent circuit workability and are less likely to generate transmission loss or foreign matter.

A surface-treated copper foil according to one embodiment of the present invention is a surface-treated copper foil having a copper foil base and a surface treatment layer formed on at least one surface of the copper foil base, wherein the surface treatment layer is rough. Consisting of one or both of a chemical treatment layer and a rust prevention treatment layer, when the optical roughness of the surface of the surface treatment layer is measured in accordance with the method specified in ISO 25178, the arithmetic mean roughness Sa is 0.04 μm or more 0.30 μm or less, and after laminating the resin member on the surface treatment layer of the surface-treated copper foil, the surface-treated copper foil is removed by etching, and the surface-treated copper foil of the remaining resin member is pasted. The contact angle θ ₁ of distilled water was measured in accordance with the sessile drop method specified in JIS R3257:1999 on the transfer surface, which is a surface treated with surface treated copper foil. When the contact angle θ ₀ of distilled water is measured according to the sessile drop method on the non-transfer surface to which the foil is later bonded, the difference between the contact angle θ ₀ and the contact angle θ ₁ is θ ₀ - θ The gist is that ₁ is between 5° and 35°.

The gist is that a copper-clad laminate according to another aspect of the present invention includes the surface-treated copper foil according to the above-mentioned one aspect and a resin base material laminated on the surface-treated layer of the surface-treated copper foil. do.
A printed wiring board according to yet another aspect of the present invention includes the surface-treated copper foil according to the other aspect.

According to the present invention, the circuit processability is excellent, and transmission loss and foreign matter are less likely to occur.

1 is a cross-sectional view illustrating the configuration of a surface-treated copper foil according to an embodiment of the present invention. It is a figure explaining the wettability of the transfer surface of a resin base material. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a method for manufacturing a copper-clad laminate and a printed wiring board according to an embodiment of the present invention.

An embodiment of the present invention will be described. Note that the embodiment described below shows an example of the present invention. Further, various changes or improvements can be made to this embodiment, and forms with such changes or improvements can also be included in the present invention.
In order to solve the above problems, the present inventors focused on the wettability of the surface of a resin base material used in manufacturing copper-clad laminates and printed wiring boards, and conducted extensive research. This will be explained in detail below with reference to FIGS. 1, 2 and 3.

During the manufacturing process of the printed wiring board 60, there is a bonding process in which the surface-treated copper foil 30 and the resin base material 40 are bonded together to produce the copper-clad laminate 50 (see (b) in FIG. 3), and There is an etching process (see FIG. 3C) in which unnecessary portions of the surface-treated copper foil 30 of the stretched laminate 50 other than the portions that will become the circuits 31 are removed by etching using an etching solution. In the bonding step, the resin base material 40 is bonded onto the surface-treated layer 20 of the surface-treated copper foil 30 (see (a) in FIG. 3).

At this time, among the surfaces of the resin base material 40 remaining after etching, the surface to which the surface-treated copper foil 30 was bonded has the shape of the surface 20a of the surface-treated layer 20 of the surface-treated copper foil 30 that had been bonded. is transcribed. That is, the surface of the resin base material 40 to which the surface-treated copper foil 30 was bonded serves as a transfer surface (replica) 40a of the surface of the surface-treated copper foil 30 that was bonded.

According to studies by the present inventors, as the surface roughness of the surface-treated copper foil 30 decreases, the surface roughness of the transfer surface 40a of the resin base material 40 also decreases, and the wettability of the transfer surface 40a decreases. It became clear that this would happen. If the wettability of the surface of the resin base material 40 is low, the ends of the circuits 31 (surface-treated copper foil 30 remaining after etching) on the resin base material 40 during etching (the ends of the circuits 31 in the wiring width direction) Since it becomes difficult for the etching solution to reach all the areas, it is thought that circuit workability deteriorates. Whether the etching solution reaches the end of the circuit 31 depends particularly on the workability of the bottom end 31b of the circuit 31 (the part of the end of the circuit 31 adjacent to the resin base material 40 (see FIG. 2)). It is an important element for

Further, during the manufacturing process of the printed wiring board 60, after the etching process, there is a cleaning process in which the resin base material 40 having the circuit 31 is cleaned with a cleaning liquid, but the surface wettability of the resin base material 40 is low. Since it is difficult for the cleaning liquid to spread over the entire surface of the resin base material 40, there is a possibility that the foreign matter 100 present on the resin base material 40 and the circuit 31 cannot be sufficiently cleaned with the cleaning liquid ((c) in FIG. 3). ). After the cleaning process, another resin base material 41 is bonded to the surface of the resin base material 40 having the circuit 31 on which the circuit 31 is formed to manufacture the printed wiring board 60. If cleaning of the resin substrate 100 is insufficient, the foreign matter 100 will remain between the two bonded resin base materials 40 and 41 (see (d) in FIG. 3).

That is, studies by the present inventors have revealed that when the surface wettability of the resin base material 40 is low, foreign matter 100 is likely to be formed on the printed wiring board 60. Note that the foreign matter 100 includes deposits that had adhered to the surface-treated copper foil 30 or the resin base material 40 before bonding, solidified salts contained in the etching solution, and the like.

As described above, the present inventors have found that the wettability of the transfer surface 40a of the resin base material 40 after the etching process is a very important factor in manufacturing the printed wiring board 60. The present invention also shows that the wettability of the transfer surface 40a of the resin base material 40 after the etching process can be evaluated by the contact angle of distilled water measured in accordance with the sessile drop method specified in JIS R3257:1999. They found out.

That is, the surface-treated copper foil 30 according to the present embodiment is a surface-treated copper foil 30 having a copper foil base 10 and a surface treatment layer 20 formed on at least one surface of the copper foil base 10, The surface treatment layer 20 consists of one or both of a roughening treatment layer 21 and a rust prevention treatment layer 22 (see FIG. 1). In addition, in FIG. 1, the surface treatment layer 20 is formed only on one side of the copper foil base 10, and the surface treatment layer 20 is a surface treated copper consisting of both the roughening treatment layer 21 and the rust prevention treatment layer 22. An example of foil 30 is shown.
When the optical roughness of the surface 20a of the surface treatment layer 20 of the surface treated copper foil 30 is measured in accordance with the method specified in ISO25178, the arithmetic mean roughness Sa is 0.04 μm or more and 0.30 μm or less. be.

Further, on the surface treatment layer 20 of the surface treated copper foil 30, a resin base material 40 (a "resin member" which is a component of the present invention) used when manufacturing the copper clad laminate 50 or the printed wiring board 60 is added. After bonding the surface-treated copper foil ₃₀ (corresponding to The contact angle of distilled water on the transfer surface (also referred to as θ ₁ ) is measured. The transfer surface 40a of the resin base material 40 is the surface of the resin base material 40 to which the surface-treated copper foil 30 was bonded.

Furthermore, the contact angle of distilled water θ ₀ (hereinafter referred to as "contact angle of distilled water on the non-transfer surface before bonding the copper foil θ ₀ ”) is measured. The non-transfer surface of the resin substrate 40 is the surface of the resin substrate 40 before being bonded to the surface-treated copper foil 30, to which the surface-treated copper foil 30 will be bonded later.

The contact angles θ ₀ and θ ₁ of distilled water are measured according to the sessile drop method specified in JIS R3257:1999. In this case, in the surface-treated copper foil 30 according to the present embodiment, the difference θ ₀ −θ ₁ between the contact angle θ ₀ and the contact angle θ ₁ is 5° or more and 35° or less. The difference θ ₀ −θ ₁ between the contact angle θ ₀ and the contact angle θ ₁ is a measure of how much the wettability of the surface of the resin has changed due to bonding with the copper foil.

If a copper-clad laminate 50 or a printed wiring board 60 is manufactured using such surface-treated copper foil 30, the transfer surface 40a of the resin base material 40 used for manufacturing the copper-clad laminate 50 or printed wiring board 60 will be wettability increases. Therefore, the obtained copper-clad laminate 50 and printed wiring board 60 have excellent circuit processability in addition to being less likely to cause transmission loss. 40 and another resin base material 41 laminated later for manufacturing the printed wiring board 60, foreign matter is less likely to occur.

That is, by setting the contact angle difference θ ₀ −θ ₁ within the above numerical range, the wettability of the surface of the resin base material 40 is maintained well, so that the circuit 31 on the resin base material 40 during etching is The etching liquid easily spreads to the bottom end 31b of the resin base material 40, and the cleaning liquid easily spreads over the entire surface of the resin base material 40 in the cleaning process after the etching process. As a result, it is possible to manufacture a copper-clad laminate 50 and a printed wiring board 60 that have both excellent circuit workability and suppression of foreign matter, and are less likely to cause transmission loss.

As described above, the surface-treated copper foil 30 according to this embodiment can be suitably used for manufacturing copper-clad laminates, printed wiring boards, and the like. That is, the copper-clad laminate 50 according to the present embodiment includes the surface-treated copper foil 30 according to the present embodiment and the resin base material 40 bonded on the surface-treated layer 20 of the surface-treated copper foil 30. Be prepared. Moreover, the printed wiring board 60 according to this embodiment includes the copper-clad laminate 50 according to this embodiment.

Below, the surface-treated copper foil 30, the copper-clad laminate 50, and the printed wiring board 60 according to this embodiment will be explained in more detail.
(A) About the surface-treated copper foil The copper foil base 10, which is the raw material for the surface-treated copper foil 30 according to the present embodiment, has two surfaces with ten points before being subjected to a treatment such as roughening treatment on the surface. It is preferable that the average roughness Rzjis is 2 μm or less in all cases. This ten-point average roughness Rzjis can be measured using a contact surface roughness measuring machine according to the method specified in JIS B0601:2001. If the ten-point average roughness Rzjis of the surface is 2 μm or less, the adhesion to the resin base material 40 tends to be good.
Further, the thickness of the copper foil base 10 before performing a treatment such as roughening treatment is 5 μm or more and 40 μm or less, although it depends on the target value of the thickness of the copper foil base 10 after the roughening treatment. It is preferable.

At least one surface of the copper foil base 10, which is a raw material, is subjected to surface treatment to form the surface treatment layer 20, and the surface treated copper foil 30 according to the present embodiment is manufactured. As the surface treatment, one or both of a roughening treatment to roughen the surface and a rust prevention treatment are performed. That is, the surface treatment layer 20 consists of one or both of a roughening treatment layer 21 formed by a roughening treatment and a rust prevention treatment layer 22 formed by a rust prevention treatment. When the surface treatment layer 20 consists of both the roughening treatment layer 21 and the rust prevention treatment layer 22, the roughening treatment layer 21 is formed on the surface of the copper foil base 10, and the rust prevention treatment layer 22 is formed on it. Form. Furthermore, after the rust prevention treatment, a chemical adhesive treatment using a chemical adhesive such as a silane coupling agent is performed to form a chemical adhesive layer such as a silane coupling agent layer on the rust prevention treatment layer 22. It's okay. These surface treatments will be detailed later.

When manufacturing the surface-treated copper foil 30 according to the present embodiment, at least one surface of the copper foil base 10 is treated before or after the general roughening treatment for the purpose of improving the above-mentioned wettability. Perform unevenness forming treatment. Then, a roughened layer 21 is formed by these general roughening treatments and unevenness forming treatments. This unevenness forming process is a process of forming minute unevenness on the surface of the copper foil base 10 to the extent that it does not affect transmission loss. Examples of this unevenness forming treatment include capsule plating treatment and etching unevenness treatment.

First, an example of capsule plating processing will be explained. Capsule plating treatment is performed before general roughening treatment. Fine unevenness is formed on the surface of the copper foil base 10 by applying smooth copper plating (capsule plating) to the surface of the copper foil base 10 using a mesh cathode shielding plate. By using a mesh cathode shielding plate, it is possible to form an uneven shape with uniform variations on the surface of the copper foil base 10.

At this time, by controlling the plating conditions such as the aperture ratio of the mesh-like cathode shielding plate, current density, and current application time, a fine uneven shape that does not affect transmission loss is created on the surface of the copper foil substrate 10. can be formed. As a result, the wettability of the transfer surface 40a of the resin base material 40 can be well controlled.

As the plating solution, a commonly used copper sulfate plating solution can be used. The material for forming the cathode shielding plate is preferably a material having chemical resistance and insulation properties, such as resins such as vinyl chloride, polyethylene, and polybutylene terephthalate. The opening area of the mesh portion is preferably 1 μm ² or more and 100 μm ² or less, more preferably 10 μm ² or more and 100 μm ² or less. Further, the aperture ratio of the mesh portion is preferably 5% or more and 15% or less. If the aperture area and aperture ratio are within the above numerical ranges, it is possible to form a fine uneven shape on the surface of the copper foil base 10 that does not affect transmission loss, and the transfer surface of the resin base 40 can be formed on the surface of the copper foil base 10. The wettability of 40a is improved.

Next, an example of etching unevenness treatment will be explained. The etching unevenness treatment is performed after the general roughening treatment and before the rust prevention treatment. After the roughening treatment, chemically resistant rust-preventing metals such as nickel (Ni) and cobalt (Co) are electrodeposited under conditions of high current density and extremely short time, and then immersed in an etching solution for a short time. By etching, fine irregularities are formed on the surface of the copper foil base 10.
For electrodeposition of nickel, a general electrolytic bath containing nickel sulfate, nickel sulfamate, etc. can be used. Further, the current density can be, for example, 1.0 A/dm ² or more, and the current application time can be, for example, 0.5 seconds or more and 2.0 seconds or less.

By electrodepositing the rust preventive metal at high current density and in a short time, the rust preventive metal is electrodeposited only on the tops of the roughened particles formed by general roughening treatment. Therefore, a region of the surface of the copper foil base 10 other than the tops of the roughened particles is etched, and a fine uneven shape is formed in a region of the surface of the copper foil base 10 other than the tops of the roughened particles.
Furthermore, by controlling conditions such as the immersion time in the etching solution, it is possible to form a fine uneven shape on the surface of the copper foil base 10 that does not affect transmission loss. As a result, the wettability of the transfer surface 40a of the resin base material 40 can be well controlled.

As the etching solution, for example, a common copper etching solution such as a mixture of sulfuric acid and hydrogen peroxide or hydrochloric acid can be used. The immersion time in the etching solution can be, for example, 2 seconds or more and 10 seconds or less. If the immersion time in the etching solution is within the above numerical range, it is possible to form a fine uneven shape on the surface of the copper foil substrate 10 that does not affect transmission loss, and transfer the resin substrate 40. In addition to improving the wettability of the surface 40a, the surface of the copper foil substrate 10 can be uniformly treated in the subsequent rust prevention treatment and chemical adhesive treatment process, resulting in good adhesion and Can provide corrosion resistance.

By the above-described unevenness forming process, a copper foil base 10 having a surface that improves the wettability of the transfer surface 40a of the bonded resin base material 40 can be obtained. As mentioned above, the wettability of the transfer surface 40a of the resin base material 40 can be evaluated by the contact angle of distilled water measured according to the sessile drop method. The difference θ ₀ −θ 1 between the distilled water contact angle θ ₀ and the distilled water contact angle _{θ 1} _of the transfer surface 40a after copper foil etching must be 5° or more and 35° or less.

However, when the optical roughness of the transfer surface 40a is measured according to the method specified in ISO25178, the arithmetic mean roughness Sa is 0.020 μm or more and 0.070 μm or less, and the volume of the space in the core portion Vvc is It is preferably 0.030 mL/m ² or more and 0.110 mL/m ² or less. As long as the arithmetic mean roughness Sa of the transfer surface 40a and the volume Vvc of the space in the core portion are within the above numerical ranges, even if the surface roughness of the surface treatment layer 20 of the surface treated copper foil 30 is small, the transfer surface 40a will not become wet. In addition to better properties, the processed shape of the circuit can be maintained even better. The reason for this is not clear, but it is thought that it is because the amount of etching at the resin-copper foil interface can be well controlled.

Furthermore, when the optical roughness of the transfer surface 40a is measured according to the method specified in ISO25178, the arithmetic mean roughness Sa is 0.020 μm or more and 0.051 μm or less, and the volume of the space in the core portion Vvc is More preferably, it is 0.030 mL/m ² or more and 0.071 mL/m ² or less. If the arithmetic mean roughness Sa of the transfer surface 40a and the volume Vvc of the space in the core portion are within the above numerical ranges, the generation of foreign matter can be further suppressed. Although the reason for this is not clear, it is thought that it is possible to limit the gap into which foreign matter can enter.

As described above, by subjecting at least one surface of the copper foil substrate 10 to an unevenness forming process and a general roughening process for the purpose of improving wettability, the surface-treated copper according to the present embodiment is A foil 30 is obtained. The surface roughness of the surface treated layer 20 of the obtained surface treated copper foil 30 needs to be as follows. That is, when the optical roughness of the surface 20a of the surface treatment layer 20 is measured according to the method specified in ISO25178, the arithmetic mean roughness Sa needs to be 0.04 μm or more and 0.30 μm or less. In order to further reduce transmission loss, the arithmetic mean roughness Sa of the surface 20a of the surface treatment layer 20 is preferably 0.04 μm or more and 0.20 μm or less, and 0.04 μm or more and 0.150 μm or less. is more preferable.

Next, a method for manufacturing the surface-treated copper foil 30 according to the present embodiment will be described. The surface-treated copper foil 30 according to the present embodiment can be manufactured by performing the following steps (1) to (5) in the order described. When manufacturing the surface-treated copper foil 30, an unevenness forming process is performed for the purpose of improving wettability, but there are two specific examples: an example using a capsule plating process and an example using an etching unevenness process as an uneven forming process. Let me explain with an example.

[Example using capsule plating process]
(1) Manufacture of copper foil base In manufacturing the surface-treated copper foil 30 according to the present embodiment, electrolytic copper foil or rolled copper foil having a smooth and glossy surface without coarse irregularities is used as the copper foil base 10. It is preferable to use it as Among these, it is preferable to use an electrolytic copper foil from the viewpoint of productivity and cost, and it is particularly preferable to use an electrolytic copper foil that is smooth on both sides and is commonly referred to as a "double-sided glossy foil."

In ordinary electrolytic copper foil, the smooth and shiny surface is the shiny surface (S surface). In double-sided glossy foils, the smooth and glossy surfaces are both the shiny side and the matte side (M side), but the smoother and glossier side is the matte side. In this embodiment, when any electrolytic copper foil is used, it is preferable to perform the roughening treatment described below on the smoother and more glossy surface.

(2) Capsule plating treatment Capsule plating treatment is performed for the purpose of improving wettability, and a fine uneven shape is formed on at least one surface of the copper foil base 10. The contents of the capsule plating process are as described above, but by using a mesh cathode shielding plate, the surface of the copper foil base 10 can be partially plated with copper (capsule plating).
Specific examples of the composition of the plating solution and plating conditions are shown below. By appropriately setting the current density, smooth copper plating (capsule plating) is applied only to the openings of the mesh portion. As a result, fine irregularities can be formed without changing the surface roughness of the entire surface of the copper foil.

<Composition of plating solution>
Concentration of copper sulfate pentahydrate...50 to 65 g/L in terms of copper (atoms)
Concentration of sulfuric acid...80-170g/L
<Conditions for plating treatment>
Processing speed: 5 to 18 m/min Current density: 1 to 5 A/dm ²

(3) Formation of Roughening Treatment Layer As the roughening treatment, it is preferable to perform, for example, a two-step plating treatment as shown below. Note that, if necessary, the second-stage fixed plating process may not be performed.
The first step of the roughening plating process is a process of forming roughening particles on the surface of the copper foil base 10 that has been subjected to the capsule plating process. The first step of roughening plating treatment can be performed, for example, by plating treatment using a copper sulfate bath. Specific examples of the composition of the plating solution and plating conditions are shown below.

The copper sulfate bath contains molybdenum (Mo), arsenic (As), antimony (Sb), bismuth (Bi), selenium (Se), tellurium ( Additives containing Te), tungsten (W), etc. may be added, and it is particularly preferable to add additives containing molybdenum.

<Composition of plating solution>
Concentration of copper sulfate pentahydrate...5 to 15 g/L in terms of copper (atoms)
Concentration of sulfuric acid...120-250g/L
Concentration of ammonium molybdate...500 to 1000 mg/L in terms of molybdenum (atoms)

<Conditions for plating treatment>
Processing speed: 8 to 22 m/min Current density: 15 to 55 A/dm ²
Processing time...0.5-5.0 seconds Bath temperature...8-20℃

The second-stage fixed plating process is a process in which smooth cover plating is performed on the copper foil base 10 that has been subjected to the first-stage roughening plating process. As a result, a roughened layer 21 is formed on the surface of the copper foil base 10. The second-stage fixed plating treatment can be performed, for example, by plating treatment using a copper sulfate bath. Specific examples of the composition of the plating solution and plating conditions are shown below.

Usually, this fixed plating treatment is performed to prevent the roughening particles from falling off, that is, to fix the roughening particles. For example, in the production of copper-clad laminates, when combining a flexible substrate made of hard resin such as polyimide resin with the surface-treated copper foil 30 according to the present embodiment, fixed plating treatment is applied to the roughened surface. , it is possible to prevent the roughening particles from falling off.

<Composition of plating solution>
Concentration of copper sulfate pentahydrate...50 to 65 g/L in terms of copper (atoms)
Concentration of sulfuric acid...90-160g/L
<Conditions for plating treatment>
Processing speed: 5-20 m/min Current density: 1-7 A/dm ²

(4) Formation of Rust Prevention Treatment Layer A silane coupling agent layer may be further formed on the roughening treatment layer 21 directly or via an intermediate layer. Examples of the intermediate layer include a base layer containing nickel, a heat-resistant treated layer containing zinc (Zn), and an anti-corrosion treated layer 22 containing chromium (Cr). Note that since the intermediate layer and the silane coupling agent layer are very thin, they do not affect the particle shape of the roughened particles on the roughened surface of the surface-treated copper foil 30. The particle shape of the roughened particles on the roughened surface of the surface-treated copper foil 30 is substantially determined by the particle shape of the roughened particles on the surface of the roughened layer 21 corresponding to the roughened surface.

For example, in the case where copper (Cu) in the copper foil base 10 or the roughening treatment layer 21 diffuses to the resin base material 40 side, causing copper damage and reducing adhesion, It is preferable to form it between the roughening treatment layer 21 and the silane coupling agent layer. The base layer is preferably formed of at least one selected from nickel, nickel-phosphorus (P), nickel-zinc, and nickel-molybdenum.

The heat-resistant treatment layer is preferably formed when it is necessary to improve the heat resistance of the surface-treated copper foil 30. The heat-resistant treatment layer is preferably formed of, for example, zinc or an alloy containing zinc. Examples of alloys containing zinc include zinc-tin (Sn) alloy, zinc-nickel alloy, zinc-cobalt alloy, zinc-copper alloy, zinc-molybdenum alloy, zinc-chromium alloy, and zinc-vanadium (V) alloy. It will be done.

It is preferable to form the anticorrosion treatment layer 22 when it is necessary to further improve corrosion resistance. Examples of the antirust layer 22 include a chromium layer formed by chromium plating and a chromate layer formed by chromate treatment.
When forming all three layers, the base layer, the heat-resistant treatment layer, and the rust prevention treatment layer 22, it is preferable to form them on the roughening treatment layer 21 in this order. Further, depending on the use and desired characteristics, only one or two of the base layer, heat-resistant treatment layer, and rust-prevention treatment layer 22 may be formed.

(5) Formation of silane coupling agent layer As a method for forming the silane coupling agent layer, for example, silane coupling is performed on the uneven surface of the roughening treatment layer 21 of the surface-treated copper foil 30 directly or through an intermediate layer. After applying a solution of the agent, air drying (natural drying) or heating drying may be used. When the water in the applied coupling agent solution evaporates, a silane coupling agent layer is formed. Drying by heating at a temperature of 50 to 180°C is preferable because the reaction between the silane coupling agent and the copper foil is accelerated.

The silane coupling agent layer includes an epoxy silane coupling agent, an amino silane coupling agent, a vinyl silane coupling agent, a methacrylic silane coupling agent, an acrylic silane coupling agent, an azole silane coupling agent, and a styryl silane coupling agent. It is preferable to contain at least one of a silane coupling agent, a ureide silane coupling agent, a mercapto silane coupling agent, a sulfide silane coupling agent, and an isocyanate silane coupling agent.

[Example using etching unevenness treatment]
(1) Manufacture of copper foil substrate This is the same as in the case of using capsule plating treatment.
(2) Formation of roughening treatment layer This is the same as in the case of using capsule plating treatment.

(3) Etching unevenness treatment For the purpose of improving wettability, etching unevenness treatment is performed to form fine unevenness on the surface of the copper foil base 10. The contents of the etching unevenness treatment are as described above, but the treatment conditions and the like will be explained in more detail. Electrodeposition was carried out using an electrolytic bath containing nickel sulfate and having a nickel concentration of 30 to 150 g/L, with a current density of 1.0 to 4.0 A/dm ² and a current application time of 0.5 to 2.0 seconds. By performing etching by immersing it in an etching solution for a short time and then etching it, it is possible to form a fine uneven shape on the surface of the copper foil base 10 that does not affect transmission loss.

This etching unevenness process forms unevenness on the surface of the roughened particles formed by the roughening process, but other etching methods include etching in a solution containing an inorganic acid such as hydrochloric acid, sulfuric acid, or phosphoric acid. An example is immersion treatment. By immersing the copper foil substrate 10 in an aqueous inorganic acid solution of a predetermined concentration for about several seconds to several tens of seconds, fine irregularities are formed on the surface of the roughened particles. For example, in the case of using hydrochloric acid, fine irregularities are formed on the surface of the roughened particles by immersing them in hydrochloric acid with a concentration of 5 to 20% by volume for 2 seconds or more.

Other etching methods include, in addition to the above-mentioned immersion treatment in a solution containing an inorganic acid, immersion treatment in a solution containing an organic acid such as acetic acid or formic acid, or a solution containing iron chloride or copper chloride. It is also possible to use immersion treatment and electrolytic etching treatment using anodic oxidation. These methods may be used in combination of two or more.

(4) Formation of antirust treatment layer This is the same as in the case of using capsule plating treatment.
(5) Formation of silane coupling agent layer This is the same as in the case of using capsule plating treatment.

(B) Regarding the wettability of the transfer surface Next, a method for evaluating the wettability of the transfer surface 40a will be described. The wettability of the transfer surface 40a of the resin base material 40 bonded to the surface-treated copper foil 30 when manufacturing the copper-clad laminate 50 or the printed wiring board 60 is based on the sessile drop method specified in JIS R3257:1999. It can be evaluated by the contact angle of distilled water measured as follows.

Among the surfaces of the resin base material 40 before being bonded to the surface-treated copper foil 30, the contact angle θ ₀ of distilled water is measured on the surface to which the surface-treated copper foil 30 is bonded later based on the sessile drop method described above. do. The surface on which the distilled water contact angle θ ₀ of the non-transfer surface before the copper foil bonding was measured is the non-transfer surface to which the shape of the surface of the surface-treated copper foil 30 has not been transferred.

Further, after bonding the resin base material 40 on the surface treatment layer 20 of the surface-treated copper foil 30, the surface-treated copper foil 30 is removed by etching, and the surface-treated part of the surface of the remaining resin base material 40 is Regarding the surface to which the copper foil 30 was bonded, the contact angle θ ₁ of distilled water is measured according to the sessile drop method described above. The surface on which the distilled water contact angle θ ₁ of the transfer surface after copper foil etching was measured is the transfer surface 40a to which the shape of the surface of the bonded surface-treated copper foil 30 is transferred.
Then, the wettability of the transfer surface 40a of the resin base material 40 is evaluated based on the difference θ ₀ −θ ₁ between the contact angle θ ₀ and the contact angle θ ₁ . If the difference θ ₀ −θ ₁ between the contact angle θ ₀ and the contact angle θ ₁ is 5° or more and 35° or less, the wettability of the transfer surface 40a is good.

The resin member used when measuring the contact angle θ ₀ and the contact angle θ ₁ is of the same type as the resin base material 40 used when manufacturing the copper-clad laminate 50 and the printed wiring board 60, as described above. However, different ones may be used to measure the contact angle θ ₀ and the contact angle θ ₁ . That is, a member having a different resin type, shape, size, etc. from the resin base material 40 used when manufacturing the copper-clad laminate 50 or the printed wiring board 60 may be used as the resin member.

The type of resin forming the resin member used when measuring the contact angle θ ₀ and the contact angle θ ₁ may be a curable resin such as a thermosetting resin, or a thermoplastic resin. In the case of a curable resin, the contact angle θ ₀ and the contact angle θ ₁ are measured after the resin member is cured. That is, in the case of a contact angle θ ₁ , the uncured resin member is bonded onto the surface treated layer 20 of the surface treated copper foil 30, and after the resin member is cured, the surface treated copper foil 30 is removed by etching. do. Then, the contact angle θ ₁ of distilled water is measured on the transfer surface of the resin member according to the sessile drop method described above.

(C) Regarding the copper-clad laminate The structure of the copper-clad laminate 50 according to the present embodiment is not particularly limited, but includes a surface-treated copper foil 30 and a resin base material 40. The resin base material 40 is bonded onto the surface treated layer 20 of the surface treated copper foil 30. This copper-clad laminate 50 can be used, for example, to manufacture a printed wiring board 60.
Note that examples of the resin forming the resin base material 40 include epoxy resin, polyphenylene ether, phenol resin, bis(phenoxyphenoxy)benzene, polyimide, liquid crystal polymer, and fluororesin (eg, polytetrafluoroethylene).

(D) About the printed wiring board Although the configuration of the printed wiring board 60 according to the present embodiment is not particularly limited, it includes the copper-clad laminate 50 according to the present embodiment. For example, after etching the surface-treated copper foil 30 of the copper-clad laminate 50 to form the circuit 31, the printed wiring board 60 can be obtained by bonding another resin base material 41 to cover the circuit 31. (See Figure 3(d)). The resin base material 41 bonded together to cover the circuit 31 may be of the same type as the resin base material 40 of the copper-clad laminate 50, or may be of a different type.

〔Example〕
The present invention will be explained in more detail by showing Examples and Comparative Examples below. First, the surface-treated copper foil of Comparative Example 7 was manufactured by the manufacturing method described in Patent Document 1. Similarly, the surface-treated copper foil of Comparative Example 8 was manufactured by the manufacturing method described in Patent Document 2, and the surface-treated copper foil of Comparative Example 9 was manufactured by the manufacturing method described in Patent Document 3. The surface-treated copper foil of Comparative Example 10 was manufactured by the manufacturing method described in Patent Document 4, and the surface-treated copper foil of Comparative Example 11 was manufactured by the manufacturing method described in Patent Document 5. It is something.

Next, the surface-treated copper foils of Examples 1 to 23 and Comparative Examples 1 to 6 and 12 to 14 were manufactured by the procedure described below.
(A) Copper foil substrate A roll-shaped electrolytic copper foil (18 μm thick A double-sided glossy foil) was produced. The cathode used to produce the electrolytic copper foil was a titanium rotating drum whose surface roughness was adjusted by buffing to #1000 to #2000, and the anode was a dimensionally stable anode DSA (registered trademark). The composition of the electrolytic solution and electrolytic conditions are shown below.

<Composition of electrolyte>
Copper: 75g/L
Sulfuric acid: 65g/L
Chlorine: 20mg/L
Sodium 3-mercapto-1-propanesulfonate: 2mg/L
Hydroxyethylcellulose: 10mg/L
Low molecular weight glue (molecular weight 3000): 50mg/L
<Electrolysis conditions>
Bath temperature: 50℃
Current density: 45A/dm ²

Next, the copper foil substrate produced as described above was subjected to the general roughening treatment described above and an unevenness forming treatment for the purpose of improving wettability. In Examples 1 to 8, 17 to 23 and Comparative Examples 2, 3, and 6, the copper foil substrate was subjected to capsule plating treatment, which is an unevenness forming treatment for the purpose of improving wettability. A roughening treatment was applied. For Examples 9 to 16 and Comparative Examples 4 and 5, the copper foil substrate was subjected to a general roughening treatment, and then subjected to an etching unevenness treatment, which is an unevenness forming treatment for the purpose of improving wettability. did. General roughening treatment, capsule plating treatment, and etching unevenness treatment will be explained below.

(B) General roughening treatment The matte surface of the copper foil substrate was roughened using a roll-to-roll method. This roughening process is a two-step electroplating process. The composition of the plating solution and plating conditions for the first-stage electroplating process are shown below. In addition, the composition of the plating solution and plating conditions for the two-stage electroplating process (fixed plating process) are shown below. As shown in Tables 1 and 2, roughening particles having different heights and shapes were formed on the surface of the copper foil by changing the current density and energization time of the first-stage electroplating process.

<Composition of the plating solution for the first stage electroplating process>
Concentration of copper sulfate pentahydrate...10g/L in terms of copper (atoms)
Concentration of sulfuric acid...150g/L
Concentration of ammonium molybdate...600mg/L in terms of molybdenum (atoms)
<Conditions for first stage electroplating treatment>
Processing speed: 15 m/min Current density: 15 to 55 A/dm ²
Bath temperature...15℃
Energization time...4 to 6 seconds

<Composition of plating solution for second stage electroplating process>
Concentration of copper sulfate pentahydrate...55g/L in terms of copper (atoms)
Concentration of sulfuric acid...120g/L
<Conditions for second-stage electroplating treatment>
Processing speed: 15m/min Current density: 2A/dm ²
Energization time: 3 seconds

(c) Capsule plating treatment Capsule plating treatment, which is an unevenness forming treatment, was performed on the copper foil substrate using a roll-to-roll method. A mesh cathode shielding plate with an opening area of 50 μm ² and an opening ratio of 5 to 15% was installed near the copper foil substrate in an electrolytic bath, and electroplating was performed under the following plating conditions using a plating solution with the following composition. Ta. As shown in Tables 1 and 2, copper foil substrates having different surface irregularities were obtained by changing the aperture ratio of the cathode shielding plate, the current density of electroplating, and the current application time.

<Composition of plating solution>
Concentration of copper sulfate pentahydrate...60g/L in terms of copper (atoms)
Concentration of sulfuric acid...150g/L
<Conditions for plating treatment>
Processing speed...18m/min

(d) Etching unevenness treatment Etching unevenness treatment, which is an unevenness forming process, was performed on the roughened surface of the copper foil substrate that had been subjected to the roughening treatment. The etching unevenness process is a process in which nickel is electrodeposited and then immersed in an etching solution for etching.The composition of the electrolytic solution used for electrodeposition, conditions for electrodeposition, and conditions for etching are shown below. As shown in Tables 1 and 2, copper foil substrates having different surface irregularities were obtained by changing the current density and current application time of electrodeposition, and the processing time of etching.

<Composition of electrolyte>
Nickel concentration...60g/L
Concentration of boric acid (H ₃ BO ₃ )...15g/L
Bath temperature...20℃
pH...3.5

<Conditions for electrodeposition>
Current density...1-2.5A/dm ²
Current application time: 1 to 3 seconds <Etching conditions>
Etching solution: Hydrochloric acid with a concentration of 10% by volume Bath temperature: 30°C
Processing time...0.5-2 seconds

(E) Rust prevention treatment Subsequently, the surface of the copper foil substrate that had been subjected to the roughening treatment and unevenness forming treatment as described above was subjected to rust prevention treatment to form a rust prevention treatment layer. The rust prevention treatment is a treatment in which nickel plating, zinc plating, and chrome plating are applied in this order. Conditions for nickel plating, zinc plating, and chrome plating are shown.

<Composition of nickel plating solution>
Nickel concentration...45g/L
Concentration of boric acid...20g/L
Bath temperature...20℃
pH...3.5
<Nickel plating conditions>
Current density: 0.4A/dm ²
Processing time: 8 seconds

<Composition of zinc plating solution>
Zinc concentration...2.5g/L
Concentration of sodium hydroxide (NaOH)...25g/L
Bath temperature...20℃
<Conditions for zinc plating>
Current density: 0.7A/dm ²
Processing time: 4 seconds

<Composition of chrome plating solution>
Chromium concentration...8g/L
Bath temperature...30℃
pH...2.4
<Chrome plating conditions>
Current density: 5A/ ^dm2
Processing time: 4 seconds

(f) Silane coupling agent treatment Finally, silane coupling agent treatment was performed to form a silane coupling agent layer on the outermost chromium plating layer of the rust prevention treatment layer. The silane coupling agent layer was formed by applying a 3-aminopropyltrimethoxysilane aqueous solution having a concentration of 0.2% by mass and drying at 100°C.

Various evaluations were performed on the surface-treated copper foils of Examples 1 to 23 and Comparative Examples 1 to 14 obtained as described above. The evaluation items and evaluation method are explained below. Moreover, the evaluation results are shown in Tables 1 and 2.
<Contact angle of distilled water>
A resin member was laminated onto the surface treatment layer (ie, silane coupling agent layer) of the surface-treated copper foil to obtain a copper-clad laminate. The following resin members were used. That is, for Examples 1 to 20 and Comparative Examples 1 to 11, a low dielectric polyphenylene ether resin base film (MEGTRON7N, an ultra-low transmission loss and high heat-resistant multilayer board material manufactured by Panasonic Corporation, thickness 60 μm) was used.

Further, for Example 21 and Comparative Example 12, ThunderClad 3+ manufactured by Taiwan Union Corporation was used, and for Example 22 and Comparative Example 13, Espanex (registered trademark) manufactured by Nippon Steel Chemical & Materials Co., Ltd. was used. For Example 23 and Comparative Example 14, liquid crystal polymer film Vector (registered trademark) manufactured by Kuraray Co., Ltd. was used.
Note that the surface-treated copper foil and the resin member were bonded together under conditions that conformed to the process guidelines for each resin.

This copper-clad laminate was etched using a mixed solution of cupric chloride and hydrochloric acid as an etching solution to remove all the surface-treated copper foil. After thoroughly washing the remaining resin member with water, the contact angle θ ₁ of distilled water was measured using the sessile drop method specified in JIS R3257:1999 on the surface of the resin member to which the surface-treated copper foil was bonded (transfer surface). Measured according to.

On the other hand, a resin member of the same type as the resin member bonded on the surface treatment layer of the surface-treated copper foil is separately prepared, and the surface-treated copper foil is not bonded to the other resin member. An operation similar to the above procedure for producing a stretched laminate was performed, and the contact angle θ ₀ of distilled water on the surface (non-transfer surface) was measured according to the sessile drop method described above. Then, the difference θ ₀ −θ ₁ between the contact angle θ ₀ and the contact angle θ ₁ was calculated.

<Arithmetic mean roughness Sa of the surface-treated copper foil, arithmetic mean roughness Sa of the resin member, volume Vvc of the space in the core part>
Transfer surface of a resin member where the arithmetic mean roughness Sa of the surface treatment layer (i.e. silane coupling agent layer) of the surface treated copper foil and the distilled water contact angle θ ₁ of the transfer surface after copper foil etching were measured. The arithmetic mean roughness Sa and core space volume Vvc were measured using confocal laser microscopes VK-X1050 and VK-X1000 manufactured by Keyence Corporation in accordance with ISO25178.

The magnification of the objective lens of the confocal laser microscope is 100 times, the scan mode is laser confocal, the measurement size is 2048 x 1536, the measurement quality is High Precision, and the pitch is 0.08 μm.
Further, calculations of the arithmetic mean roughness Sa and the volume Vvc of the space in the core portion were performed under the filter processing and calculation conditions shown below.

Image processing: Smoothing processing, 3×3, median S filter: None F-operation: Plane tilt correction L filter: 0.025 μm
Area to be calculated: 100μm x 100μm
Load area ratio in load curve: 10% and 90%

<Circuit processability>
A resist pattern with an L&S of 50/50 μm was placed on a surface-treated copper foil of a copper-clad laminate similar to the one prepared to measure the distilled water contact angle θ ₁ of the transfer surface after copper foil etching using the subtractive method. It was formed by The surface-treated copper foil was then etched to form a circuit having a wiring pattern. A dry resist film was used as the resist, and a mixed solution containing copper chloride and hydrochloric acid was used as the etching solution.

Then, the etching factor (Ef) of the obtained circuit was measured. The etching factor is expressed by the formula Ef=2H/(B-T), where H is the thickness of the copper foil, B is the bottom width of the formed circuit, and T is the top width of the formed circuit. It is a value.
The copper-clad laminate on which the circuit was formed was cut to obtain a cross section perpendicular to the surface of the resin member, and the cross section of the circuit was observed using a scanning electron microscope. Then, angles X and Y on the cross section shown in FIG. 2 were measured. The angle X is the angle between the straight line connecting the top end 31a and bottom end 31b of the circuit 31 and the surface of the resin member. The angle Y is the angle between the tangent to the bottom end 31b of the circuit 31 and the surface of the resin member.

The tangent to the bottom end 31b of the circuit 31 will be defined in more detail. Draw a straight line parallel to the surface of the resin member at a height of 1.5 μm from the bottom surface of the resin member, and connect the intersection 31c of the straight line with the side surface of the circuit 31 to the bottom end 31b. A straight line is defined as "a tangent to the bottom end 31b of the circuit 31", and an angle between this tangent and the surface of the resin member is defined as an angle Y.

Five arbitrary cross sections were observed for one circuit, and angles X and Y were measured for each. Then, for both the angle X and the angle Y, the average value of the five measured values was calculated. The results are shown in Tables 1 and 2. In Tables 1 and 2, when Ef is 2.5 or more and the angle Y is larger than the angle Those larger than X were labeled as "B", and the others were labeled as "C". Note that (a) in FIG. 2 is a diagram showing an example of a circuit 31 in which the angle Y is smaller than the angle X, and (b) in FIG. 2 is a diagram showing an example of the circuit 31 in which the angle Y is larger than the angle X. It is a diagram.

<Transmission loss>
A printed wiring board with a strip line formed thereon was fabricated using a copper-clad laminate similar to the one fabricated to measure the distilled water contact angle θ ₁ on the transfer surface after copper foil etching, and the transmission characteristics were evaluated. . The circuit width of the strip line formed on this printed wiring board was 140 μm, and the circuit length was 76 mm.

A high frequency signal was transmitted to the circuit formed on this printed wiring board using a network analyzer N5291A manufactured by Keysight Technologies, and the transmission loss was measured. The characteristic impedance was 50Ω. The smaller the absolute value of the measured value of transmission loss, the lower the transmission loss (that is, the higher the frequency signal can be transmitted). The results are shown in Tables 1 and 2. In Tables 1 and 2, if the absolute value of transmission loss at 40 GHz is less than 3.0 dB/76 mm, it is "A", if it is 3.0 dB/76 mm or more and less than 3.6 dB/76 mm, it is "B", and 3 If it is .6dB/76mm or more, it is indicated as "C".

<Occurrence of foreign matter>
A copper-clad laminate similar to the one prepared to measure the distilled water contact angle θ ₁ of the transfer surface after copper foil etching was etched using a mixture of cupric chloride and hydrochloric acid as the etching solution. All treated copper foil was removed. After thoroughly washing the remaining resin member with water, apply a resin member of the same type as that used to make the above-mentioned copper-clad laminate to the surface of the resin member to which the surface-treated copper foil was bonded (transfer surface). and the surface-treated copper foil were laminated in this order and then etched in the same manner as above to remove all the surface-treated copper foil. As a result, a resin sample made of two resin members bonded together was obtained.

Next, the obtained resin sample was cut into a square shape of 5 cm on each side. Then, the cut resin sample was observed with a microscope at a magnification of 35 times, and the number of black spots with a diameter of 1 mm or more was measured. These black spots are caused by foreign matter generated between the two resin members bonded together. Observation using a microscope was performed by viewing the transfer surface of the resin member that originally constituted the copper-clad laminate from the side of the resin member that was later bonded. The results are shown in Tables 1 and 2. In Tables 1 and 2, if the number of black dots per cut resin sample is 2 or less, it is marked "A", if it is 3 or more and 5 or less, it is marked "B", and if it is more than 5, it is marked "B". is indicated as "C".

As can be seen from Tables 1 and 2, in the surface-treated copper foils of Examples 1 to 23, the arithmetic mean roughness Sa of the surface of the surface treatment layer was controlled within a range of 0.04 μm to 0.30 μm. Regardless, the difference θ ₀ - θ ₁ between the contact angle θ ₀ and the contact angle θ ₁ , which represents the wettability of the transfer surface of the resin base material, is well controlled, resulting in excellent circuit processability and low transmission loss and Foreign matter was less likely to occur.

Moreover, among these, the surface-treated copper foils of Examples 1 to 4, 10 to 14, 17, 18, and 21 to 23 have the arithmetic mean roughness Sa of the transfer surface of the resin base material and the volume of the space in the core part Vvc. Since it was well controlled, the circuit processability was even better and the generation of foreign matter was further reduced.
On the other hand, the surface-treated copper foils of Comparative Examples 1 to 14 have low wettability on the transfer surface of the resin base material, and therefore have poor circuit processability, transmission loss, and generation of foreign matter. That was enough.

DESCRIPTION OF SYMBOLS 10... Copper foil base 20... Surface treatment layer 20a... Surface of surface treatment layer 21... Roughening treatment layer 22... Rust prevention treatment layer 30... Surface treatment copper foil 31... -Circuit 31a...Top end 31b...Bottom end 40...Resin base material (resin member)
40a... Transfer surface 41... Resin base material 50... Copper clad laminate 60... Printed wiring board 100... Foreign matter

Claims

A surface-treated copper foil comprising a copper foil base and a surface treatment layer formed on at least one surface of the copper foil base,
The surface treatment layer consists of one or both of a roughening treatment layer and a rust prevention treatment layer,
When the optical roughness of the surface of the surface treatment layer is measured according to the method specified in ISO 25178, the arithmetic mean roughness Sa is 0.04 μm or more and 0.30 μm or less,
After laminating a resin member on the surface-treated layer of the surface-treated copper foil, the surface-treated copper foil is removed by etching, and the surface of the remaining resin member to which the surface-treated copper foil was laminated. For the transfer surface, the contact angle θ 1 of distilled water was measured according to the sessile drop method specified in JIS R3257:1999, and the surface treatment of the resin member before bonding to the surface-treated copper foil was measured. The difference between the contact angle θ 0 and the contact angle θ 1 when the contact angle θ 0 of distilled water is measured according to the sessile drop method on the non-transfer surface to which the copper foil is later bonded. A surface-treated copper foil in which θ 0 - θ 1 is 5° or more and 35° or less.
When the optical roughness of the transfer surface is measured according to the method specified in ISO 25178, the arithmetic mean roughness Sa is 0.020 μm or more and 0.070 μm or less, and the volume Vvc of the space in the core portion is 0.020 μm or more and 0.070 μm or less. The surface-treated copper foil according to claim 1, wherein the surface-treated copper foil has a concentration of 0.030 mL/m 2 or more and 0.110 mL/m 2 or less.
When the optical roughness of the transfer surface is measured according to the method specified in ISO 25178, the arithmetic mean roughness Sa is 0.020 μm or more and 0.051 μm or less, and the volume Vvc of the space in the core portion is 0.020 μm or more and 0.051 μm or less. The surface-treated copper foil according to claim 1, wherein the surface-treated copper foil has a concentration of 0.030 mL/m 2 or more and 0.071 mL/m 2 or less.
A copper-clad laminate comprising the surface-treated copper foil according to any one of claims 1 to 3 and a resin base material laminated on the surface-treated layer of the surface-treated copper foil.
A printed wiring board comprising the copper-clad laminate according to claim 4.