Surface-treated copper foil, carrier-attached copper foil, copper-clad laminate, and printed wiring board

Abstract

The present disclosure provides a surface-treated copper foil that includes: copper foil; and a surface section that is disposed on one surface of the copper foil and that contains selenium. The area ratio of the surface section to the one surface of the copper foil is 30.0% or more and less than 100.0%.

Description

Surface-treated copper foil, copper foil with carrier, copper-clad laminate, and printed wiring board

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

[0002] In printed wiring boards, copper foil is preferably used as a wiring material (for example, see Patent Document 1). In printed wiring boards, it is desirable to improve the adhesion between the resin layer and the copper foil in order to ensure reliability.

[0003] International Publication No. 2019 / 188837

[0004] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a surface-treated copper foil having good adhesion to a resin layer.

[0005] One embodiment of the present disclosure provides a surface-treated copper foil having a copper foil and a surface portion containing selenium, the surface portion being disposed on one side of the copper foil, wherein the area ratio of the surface portion to the one side of the copper foil is 30.0% or more and less than 100.0%.

[0006] Another embodiment of the present disclosure provides a copper foil with a carrier, comprising a carrier substrate and the above-mentioned surface-treated copper foil disposed on one surface of the carrier substrate, wherein the surface-treated copper foil is disposed so that the copper foil side faces the carrier substrate.

[0007] Another embodiment of the present disclosure provides a copper-clad laminate comprising a resin layer and the above-described surface-treated copper foil disposed on one or both sides of the resin layer, the surface-treated copper foil being disposed so that the surface on the surface portion side faces the resin layer.

[0008] Another embodiment of the present disclosure provides a printed wiring board comprising: a resin layer; and a patterned surface-treated copper foil disposed on one or both sides of the resin layer, wherein the surface-treated copper foil comprises copper foil and a surface portion containing selenium disposed on one side of the copper foil, the surface-treated copper foil being disposed such that the surface of the surface portion faces the resin layer, and the area ratio of the surface portion to the one side of the copper foil is 30.0% or more and less than 100.0%.

[0009] The present disclosure has the effect of providing a surface-treated copper foil having good adhesion to a resin layer.

[0010] FIG. 1 is a schematic cross-sectional view illustrating a surface-treated copper foil according to the present disclosure. FIG. 2 is a schematic cross-sectional view illustrating a carrier-attached copper foil according to the present disclosure. FIG. 3 is a process diagram illustrating a method for transferring a carrier-attached copper foil according to the present disclosure. FIG. 4 is a schematic cross-sectional view illustrating a carrier-attached copper foil according to the present disclosure. FIG. 5 is a schematic cross-sectional view illustrating a copper-clad laminate according to the present disclosure. FIG. 6 is a schematic cross-sectional view illustrating a printed wiring board according to the present disclosure. Images X, Y, and Z in Examples 1 to 3. Images X, Y, and Z in Comparative Examples 1 to 3.

[0011] Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual form, but these are merely examples and do not limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0012] In this specification, when describing a mode in which another component is placed on a certain component, the term "above" or "below" is used, unless otherwise specified, to include both a case in which another component is placed directly above or below a certain component so as to be in contact with the component, and a case in which another component is placed above or below a certain component with another component interposed therebetween. Also, in this specification, when describing a mode in which another component is placed on the surface of a certain component, the term "on the surface side" or "on the surface" is used, unless otherwise specified, to include both a case in which another component is placed directly above or below a certain component so as to be in contact with the component, and a case in which another component is placed above or below a certain component with another component interposed therebetween.

[0013] In this specification, the term "film" also includes a member called a "sheet."

[0014] The surface-treated copper foil, the copper foil with a carrier, the copper-clad laminate, and the printed wiring board according to the present disclosure will be described in detail below.

[0015] A. Surface-Treated Copper Foil The surface-treated copper foil according to the present disclosure comprises a copper foil and a surface portion containing selenium, the surface portion being disposed on one side of the copper foil, and the area ratio of the surface portion to the one side of the copper foil is 30.0% or more and less than 100.0%.

[0016] Fig. 1 is a schematic cross-sectional view illustrating a surface-treated copper foil according to the present disclosure. The surface-treated copper foil 1 in Fig. 1 has a copper foil 1a and a surface portion 1b containing selenium disposed on one side A1 of the copper foil 1a. The area ratio of the surface portion 1b to the one side A1 of the copper foil 1a is within a predetermined range.

[0017] According to the present disclosure, by disposing a surface portion containing selenium on one side of the copper foil so as to have a predetermined area ratio, it is possible to improve the adhesion between the surface-treated copper foil and the resin layer.

[0018] The surface-treated copper foil of the present disclosure has a surface portion containing selenium. The inventors of the present application have found that surface treatment of copper foil using selenium results in better adhesion to a resin layer than surface treatment using other metals such as zirconium, nickel, or silver. Conventionally, surface treatment using organic substances such as silane coupling agents has been known for copper foil surface treatment. However, organic substances tend to have poor heat resistance, and surface treatment using organic substances raises concerns about reduced adhesion to a resin layer in high-temperature, high-humidity environments. In contrast, surface treatment using selenium is an inorganic surface treatment, which can improve heat resistance and maintain adhesion to a resin layer even in high-temperature, high-humidity environments. While surface treatment using other metals such as tin is also considered, selenium has a lower environmental impact than tin. Selenium also has the advantage that it can form a film on the copper surface at a low temperature of about 40° C. in a short time, and that it is an element of the same group as sulfur and can have oxidation numbers from −2 to +6, resulting in high chemical surface reactivity. Therefore, in the present disclosure, it is important that the surface portion contains selenium.

[0019] Hereinafter, each component of the surface-treated copper foil according to the present disclosure will be described.

[0020] 1. Layer Structure of Surface-Treated Copper Foil The surface-treated copper foil of the present disclosure has a copper foil and a surface portion that is disposed on one side of the copper foil and contains selenium.

[0021] (1) Copper Foil The copper foil includes copper or a copper alloy. The copper alloy is not particularly limited as long as it can be used to produce copper foil.

[0022] The thickness of the copper foil is appropriately selected depending on the application and manufacturing method of the surface-treated copper foil. As will be described later, when the surface-treated copper foil is obtained from a copper foil with a carrier, the thickness of the copper foil is, for example, 0.4 μm to 35 μm, 0.6 μm to 18 μm, 0.8 μm to 12 μm, or 1 μm to 5 μm. When the copper foil has a thin thickness within the above range, it is suitable for forming fine wiring. On the other hand, when the surface-treated copper foil has self-supporting properties, the thickness of the copper foil is, for example, 5 μm to 35 μm, 6 μm to 18 μm, or 8 μm to 12 μm.

[0023] As the copper foil, for example, rolled copper foil or electrolytic copper foil can be used.

[0024] (2) Surface portion The surface portion is disposed on one side of the copper foil and contains selenium. The presence of selenium in the surface portion is determined by X-ray photoelectron spectroscopy (XPS). The measurement conditions are described in the Examples below.

[0025] In the present disclosure, the area ratio of the surface portion to one side of the copper foil is 30.0% or more, preferably 32.0% or more, and more preferably 34.0% or more. Having the area ratio of the surface portion within the above range improves adhesion to the resin layer. On the other hand, the area ratio of the surface portion to one side of the copper foil is less than 100.0%, preferably 60.0% or less, and more preferably 50.0% or less. If the area ratio of the surface portion is too high, the surface portion will be excessively formed. Therefore, the surface portion may be prone to peeling, and adhesion to the resin layer may be reduced. Specifically, the area ratio of the surface portion to one side of the copper foil is 30.0% or more and less than 100.0%, preferably 32.0% or more and 60.0% or less, and more preferably 34.0% or more and 50.0% or less.

[0026] The area ratio of the surface portion to one side of the copper foil can be adjusted, for example, by adjusting the concentration of the selenium compound in the room-temperature blackening agent described below, the treatment time, etc. Specifically, a shorter treatment time reduces the area ratio of the surface portion, while a longer treatment time increases the area ratio of the surface portion. Furthermore, a lower concentration of the selenium compound in the room-temperature blackening agent reduces the area ratio of the surface portion, while a higher concentration of the selenium compound in the room-temperature blackening agent increases the area ratio of the surface portion.

[0027] The area ratio of the surface portion to one side of the copper foil is determined by the following method. First, an image is obtained from the surface portion side of the surface-treated copper foil using a scanning electron microscope (SEM). Next, using image analysis software, the image is trimmed to include a relatively flat area, and a trimmed image is obtained. Next, the trimmed image is binarized into a surface portion and other portions, and a binarized image is obtained. Next, the surface portion is selected from the binarized image, and the area ratio of the surface portion to the analysis area is calculated. The image acquisition conditions, image analysis conditions, and calculation method are described in the Examples below.

[0028] The surface portions are preferably arranged partially on one side of the copper foil, more specifically, the surface portions are preferably scattered on one side of the copper foil.

[0029] The surface portion preferably contains a plurality of particles containing selenium. The number of particles containing selenium on one side of the copper foil is 1500 particles / μm. ２ Preferably, 1000 particles / μm or less ２ More preferably, the average size of the selenium-containing particles is 400 nm. ２ More than 500 nm is preferable. ２ The above is more preferable. When the number and average size of the particles are within the above ranges, the adhesion to the resin layer is improved. On the other hand, the number of selenium-containing particles on one side of the copper foil is, for example, 300 particles / μm ２ or more, and ２ The average size of the selenium-containing particles may be, for example, 700 nm or more. ２The number and average size of the particles are calculated from the binarized image described above.

[0030] The surface portion can be formed by subjecting the copper foil to a surface treatment, such as plating, e.g., electrolytic plating or electroless plating, chemical conversion treatment, or PVD, e.g., vacuum deposition or sputtering.

[0031] Among these, chemical conversion treatment is preferred, and in the case of chemical conversion treatment, room temperature blackening treatment is desirable. Room temperature blackening treatment can form a surface portion in a short time by applying a blackening agent to the copper foil, immersing the copper foil in the blackening agent, or spray coating.

[0032] In the case of chemical conversion treatment at room temperature, it is preferable to use a room temperature blackening agent containing a selenium compound. The room temperature blackening agent containing a selenium compound can easily form a surface portion containing selenium by immersion or spray application. As the selenium compound, for example, selenious acid (H ２ SeO ３ ) are listed.

[0033] Furthermore, the surface-treated copper foil preferably does not have a surface treatment layer made of an organic substance such as a coupling agent on one side of the copper foil. Surface treatment layers made of organic substances contain a large amount of carbon components, resulting in poor moist heat resistance. The absence of a surface treatment layer made of an organic substance in the surface-treated copper foil allows the foil to exhibit excellent adhesion to the resin layer even in a moist and hot environment. Furthermore, since the surface-treated copper foil preferably does not have a surface treatment layer made of an organic substance such as a coupling agent on one side of the copper foil, the surface portion containing selenium is preferably located on the outermost surface of the surface-treated copper foil.

[0034] 2. Surface Properties of Surface-Treated Copper Foil In the present disclosure, the maximum height roughness Rz of the surface of the surface portion side of the surface-treated copper foil is, for example, preferably 0.6 μm or more, more preferably 0.7 μm or more, and even more preferably 0.8 μm or more. By having the Rz in the above range, the adhesion between the surface-treated copper foil and the resin layer can be further improved. On the other hand, the upper limit of the Rz is not particularly limited as long as the formation is possible, and is, for example, 2.3 μm or less. In particular, the Rz is preferably 1.20 μm or less, more preferably 1.18 μm or less, and even more preferably 1.15 μm or less. By having the Rz in the above range, transmission loss can be suppressed. Specifically, the Rz is 0.6 μm or more and 2.3 μm or less, preferably 0.6 μm or more and 1.20 μm or less, more preferably 0.7 μm or more and 1.18 μm or less, and even more preferably 0.8 μm or more and 1.15 μm or less.

[0035] Generally, copper foils are required to have a low surface roughness in order to suppress transmission loss. Copper foils with low surface roughness tend to have insufficient adhesion to a resin layer. In the present disclosure, even if the surface Rz of the surface-treated copper foil is small and has a low roughness within the above range, the adhesion to the resin layer can be improved by setting the area ratio of the surface portion containing selenium within a predetermined range. In other words, both adhesion to the resin layer and suppression of transmission loss can be achieved.

[0036] The Rz can be adjusted by adjusting the method and conditions of the roughening treatment of the copper foil. For example, by using etching as the roughening treatment, the Rz can be made relatively small.

[0037] The maximum height roughness Rz is a value obtained by a method conforming to JIS B0601:2013. The maximum height roughness Rz is one of the parameters of the peaks and heights of a profile curve, and is the sum of the height of the highest peak and the depth of the deepest valley among the profile curves in a reference length. The larger the value of the maximum height roughness Rz, the more convex portions with larger (higher) shapes are present as viewed from the valleys (concave portions), and this is an indicator that there tends to be a large number of such convex portions.

[0038] The cutoff value for measuring the maximum height roughness Rz is 0.8 mm, and the maximum height roughness Rz is the average value of measurements taken at any five locations.

[0039] Furthermore, the "surface on the surface portion side of the surface-treated copper foil" refers to the surface S2 of the surface-treated copper foil 1, which is located on the surface portion 1b side of the copper foil 1a, as shown in FIG. 1 . Hereinafter, the surface on the surface portion side of the surface-treated copper foil may be referred to as the "second surface." The surface-treated copper foil 1 also has a first surface S1 opposite to the second surface S2.

[0040] Furthermore, the arithmetic mean height Ra of the surface of the surface-treated copper foil on the surface portion side is preferably 0.105 μm or more, more preferably 0.110 μm or more. By having the Ra in the above range, the adhesion between the surface-treated copper foil and the resin layer can be improved. On the other hand, the Ra is preferably 0.165 μm or less, more preferably 0.160 μm or less. By having the Ra in the above range, transmission loss can be suppressed. Specifically, the Ra is preferably 0.105 μm or more and 0.165 μm or less, more preferably 0.110 μm or more and 0.160 μm or less.

[0041] The arithmetic mean height Ra is a value obtained by a method conforming to JIS B0601:2013. The arithmetic mean height Ra is one of the parameters in the height direction of the profile curve, and is the average value of the height difference from the mean plane on the profile curve over a reference length. The cutoff value for measuring the arithmetic mean height Ra is 0.8 mm. The arithmetic mean height Ra is the average value of measurements taken at any five locations. The method for adjusting Ra is the same as the method for adjusting Rz described above.

[0042] Furthermore, the maximum peak height Rp on the surface of the surface-treated copper foil on the surface portion side is preferably 0.20 μm or more, more preferably 0.25 μm or more. By having the Rp in this range, the adhesion between the surface-treated copper foil and the resin layer can be improved. On the other hand, the Rp is preferably 0.55 μm or less, more preferably 0.50 μm or less. By having the Rp in this range, transmission loss can be suppressed. Specifically, the Rp is preferably 0.20 μm or more and 0.55 μm or less, more preferably 0.25 μm or more and 0.50 μm or less.

[0043] The maximum peak height Rp is a value obtained by a method conforming to JIS B0601:2013. The cutoff value for measuring the maximum peak height Rp is 0.8 mm. The maximum peak height Rp is the average value of measurements taken at any five locations. The method for adjusting Rp is the same as the method for adjusting Rz described above.

[0044] B. Copper Foil with Carrier The copper foil with carrier in the present disclosure has a carrier base and the above-mentioned surface-treated copper foil arranged on one surface of the carrier base, and the surface of the surface-treated copper foil is arranged so that the surface of the copper foil faces the carrier base.

[0045] The copper foil with a carrier according to the present disclosure is used for transferring a surface-treated copper foil. For example, after laminating a copper foil with a carrier and a resin layer, the carrier substrate is peeled off from the copper foil with a carrier, thereby transferring the surface-treated copper foil to one side of the resin layer. The copper foil with a carrier according to the present disclosure can improve the adhesion between the surface-treated copper foil and the resin layer by having the above-mentioned surface-treated copper foil.

[0046] Hereinafter, each component of the surface-treated copper foil according to the present disclosure will be described.

[0047] 1. Surface-treated copper foil The surface-treated copper foil is the same as the surface-treated copper foil described above in "A. Surface-treated copper foil." The surface-treated copper foil is arranged so that the copper foil side faces the carrier substrate.

[0048] 2. Carrier Substrate The carrier substrate is a member that supports the surface-treated copper foil. The carrier substrate is not particularly limited as long as it can support the surface-treated copper foil, and has at least a substrate layer. Examples of the substrate layer include a metal substrate, a resin substrate, a glass substrate, a ceramic substrate, and a silicon wafer. The substrate layer may be rigid or flexible.

[0049] The layer structure of the carrier substrate is not particularly limited. For example, the carrier substrate may have, in order from the surface-treated copper foil side, an adhesive layer and a base layer, or may have a release layer and a base layer. Hereinafter, as specific examples, a case where the carrier substrate has, in order from the surface-treated copper foil side, an adhesive layer and a resin base material, and a case where the carrier substrate has, in order from the surface-treated copper foil side, a release layer and a carrier copper foil will be described.

[0050] (1) First Aspect The carrier substrate of this aspect has, in this order from the surface-treated copper foil side, an adhesive layer and a resin substrate.

[0051] Fig. 2 is a schematic cross-sectional view illustrating an example of a carrier-attached copper foil according to the present disclosure. The carrier-attached copper foil 10 in Fig. 2 includes a resin substrate 2, a carrier substrate 11 having an adhesive layer 3 disposed on one surface of the resin substrate 2, and the above-described surface-treated copper foil 1 disposed on the adhesive layer 3 side of the carrier substrate 11. The surface-treated copper foil 1 is disposed so that the copper foil 1a side surface S1 faces the adhesive layer 3.

[0052] In this embodiment, by using a resin substrate as the carrier substrate, it is possible to reduce costs compared to when a carrier copper foil is used. In particular, by using an inexpensive resin substrate, costs can be significantly reduced.

[0053] In this embodiment, the carrier substrate can be made transparent by using a resin substrate as the carrier substrate. When the carrier substrate is transparent, the copper foil with a carrier can be inspected for defects on the carrier substrate side of the surface-treated copper foil. Therefore, the yield can be increased.

[0054] When a carrier copper foil is used as the carrier substrate, it is difficult to check for defects on the surface of the surface-treated copper foil facing the carrier substrate.

[0055] As described above, the carrier-attached copper foil of the present disclosure is used for transferring a surface-treated copper foil. For example, as shown in Figures 3(a) and 3(b), after laminating a carrier-attached copper foil 10 and a resin layer 21, the carrier substrate 11 is peeled off from the carrier-attached copper foil 10, thereby transferring the surface-treated copper foil 1 to one side of the resin layer 21. As described above, the presence of the surface-treated copper foil in the carrier-attached copper foil can improve the adhesion between the surface-treated copper foil and the resin layer.

[0056] (a) Resin substrate The resin substrate is a member that supports the adhesive layer and the surface-treated copper foil. The resin constituting the resin substrate is not particularly limited, and examples thereof include polyester resin, polyimide resin, polyamide resin, polyamideimide resin, polybenzoxazole resin, aramid resin, polystyrene resin, polyetheretherketone resin, polyphenylene sulfide resin, polyethersulfone resin, and polyarylate resin. Examples of polyester resins include polyethylene terephthalate and polyethylene naphthalate.

[0057] In particular, the resin substrate preferably has heat resistance. When the surface-treated copper foil of the present disclosure is transferred to the resin layer using the copper foil with a carrier, the copper foil with a carrier and the resin layer may be heated. The heat resistance of the resin substrate makes the heating process possible.

[0058] When the resin substrate has heat resistance, examples of the resin constituting the resin substrate include polyimide resin, polyamide resin, polyamideimide resin, polybenzoxazole resin, aramid resin, syndiotactic polystyrene resin, polyether ether ketone resin, polyphenylene sulfide resin, polyether sulfone resin, and polyarylate resin.

[0059] The resin substrate is preferably transparent. When the resin substrate is transparent, the copper foil with a carrier can be inspected for defects on the surface of the surface-treated copper foil facing the resin substrate by observing the copper foil from the resin substrate side. This can increase the yield.

[0060] When the resin substrate has transparency, the total light transmittance of the resin substrate is, for example, preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The total light transmittance of the resin substrate is measured in accordance with JIS K7361-1:1997.

[0061] The thickness of the resin substrate is, for example, preferably 12.5 μm or more and 250 μm or less, more preferably 12.5 μm or more and 100 μm or less, and even more preferably 12.5 μm or more and 50 μm or less. If the thickness of the resin substrate is too thin, the handleability of the carrier-attached copper foil may be impaired, or it may be difficult to peel the carrier substrate from the carrier-attached copper foil. If the thickness of the resin substrate is too thick, it may be difficult to peel the carrier substrate from the carrier-attached copper foil. Furthermore, if the thickness of the resin substrate is too thick, the transparency of the resin substrate may be reduced.

[0062] (b) Adhesive layer The adhesive layer is a member disposed between the resin substrate and the surface-treated copper foil. When the surface-treated copper foil is transferred to the resin layer using the copper foil with a carrier according to the present disclosure, the adhesive layer peels off at the interface between the adhesive layer and the surface-treated copper foil.

[0063] The adhesive layer is not particularly limited as long as it can adhere the resin substrate and the copper foil and is removable. Examples of adhesives used in the adhesive layer include acrylic adhesives, urethane adhesives, and silicone adhesives.

[0064] In particular, the adhesive layer preferably has heat resistance. When the surface-treated copper foil of the present disclosure is transferred to the resin layer using the copper foil with a carrier, the copper foil with a carrier and the resin layer may be heated. The heat resistance of the adhesive layer makes the heating process possible.

[0065] As the adhesive used in the adhesive layer, an acrylic adhesive is preferably used from the viewpoints of removability, heat resistance, transparency, etc. The acrylic adhesive can be appropriately selected from known acrylic adhesives and used. For example, the adhesive layer may contain a crosslinked product of an adhesive composition containing an acrylic polymer as a main component and a crosslinking agent.

[0066] The thickness of the adhesive layer is, for example, preferably 3 μm or more and 20 μm or less, more preferably 4 μm or more and 15 μm or less, and even more preferably 5 μm or more and 10 μm or less. If the thickness of the adhesive layer is too thin, the adhesion between the resin substrate and the surface-treated copper foil may be reduced. On the other hand, if the thickness of the adhesive layer is too thick, the removability may be reduced.

[0067] (c) Physical Properties of Carrier Substrate The carrier substrate of this embodiment is preferably transparent. When the carrier substrate is transparent, the copper foil with a carrier can be inspected for defects on the carrier substrate side of the surface-treated copper foil. This can increase the yield.

[0068] When the carrier substrate is transparent, the total light transmittance of the carrier substrate is, for example, preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The total light transmittance of the carrier substrate is measured in accordance with JIS K7361-1:1997.

[0069] (d) Manufacturing Method of Carrier-Attached Copper Foil When the carrier-attached copper foil of the present disclosure has the carrier substrate of this embodiment, the manufacturing method of the carrier-attached copper foil can include, for example, a placement step of placing a copper foil on the adhesive layer side of the carrier substrate, an etching step of thinning the copper foil by etching, and a surface portion forming step of forming a surface portion containing selenium on the side of the copper foil opposite the carrier substrate. By thinning the copper foil thickness by etching, the copper foil can be made to a thickness suitable for forming fine wiring. Furthermore, the Rz, Ra, and Rp on the side of the copper foil opposite the carrier substrate can be set within a predetermined range.

[0070] In the placement step, the carrier substrate and the copper foil can be bonded together by the adhesive layer, and the copper foil can be a thick electrolytic copper foil or a rolled copper foil.

[0071] In the etching step, a general copper foil etching method can be used as the copper foil etching method.

[0072] After the etching step, a roughening treatment step may be further performed to roughen the copper foil by etching. This allows the Rz, Ra, and Rp of the copper foil on the side opposite to the carrier substrate to be within a predetermined range. In the roughening treatment step, a general copper foil etching method can be used as the copper foil etching method. For example, the surface properties can be controlled by adjusting the concentration and temperature of the etching solution.

[0073] The method for forming the surface portion in the surface portion forming step is as described above.

[0074] (2) Second Aspect The carrier substrate of this aspect has, in order from the surface-treated copper foil side, a release layer and a carrier copper foil.

[0075] Fig. 4 is a schematic cross-sectional view illustrating a carrier-attached copper foil according to the present disclosure. The carrier-attached copper foil 10 in Fig. 4 includes a carrier copper foil 4 as a metal foil, a carrier substrate 11 having a release layer 5 disposed on one side of the carrier copper foil 4, and the above-described surface-treated copper foil 1 disposed on the side of the carrier substrate 11 facing the release layer 5. The surface-treated copper foil 1 is disposed so that the surface S1 on the copper foil 1a side faces the release layer 5.

[0076] (a) Carrier copper foil The carrier copper foil is a member that supports the release layer and the surface-treated copper foil. From the viewpoint of good handleability, the thickness of the carrier copper foil is, for example, preferably 5 μm or more and 30 μm or less, more preferably 10 μm or more and 20 μm or less. Either electrolytic copper foil or rolled copper foil can be used as the carrier foil.

[0077] The carrier copper foil may be a foil made of a single metal, copper, or an alloy of copper with other metals, such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, and titanium.

[0078] (b) Release Layer The release layer is a member provided for the purpose of facilitating the release of the copper foil from the carrier copper or for the purpose of imparting weak adhesion. There are no particular limitations on the release layer, and a release layer generally used in carrier-attached copper foils can be applied. The release layer may be a single layer or multiple layers.

[0079] C. Copper-Clad Laminate The copper-clad laminate of the present disclosure comprises a resin layer and the above-described surface-treated copper foil disposed on one or both sides of the resin layer, with the surface of the surface-treated copper foil disposed so that the surface on the surface portion side faces the resin layer.

[0080] 5( a) and 5(b) are schematic cross-sectional views illustrating copper-clad laminates according to the present disclosure. The copper-clad laminate 30 shown in Fig. 5(a) has a resin layer 31 and a surface-treated copper foil 1 disposed on one side of the resin layer 31. The copper-clad laminate 30 shown in Fig. 5(b) has a resin layer 31 and surface-treated copper foils 1 disposed on both sides of the resin layer 31. The surface-treated copper foil 1 is disposed so that the surface S2 of the surface portion 1b faces the resin layer 31.

[0081] The copper-clad laminate of the present disclosure has the above-described surface-treated copper foil, thereby enabling the adhesion between the surface-treated copper foil and the resin layer to be improved.

[0082] Hereinafter, each configuration of the copper-clad laminate according to the present disclosure will be described.

[0083] 1. Surface-Treated Copper Foil The surface-treated copper foil in the present disclosure is the same as that described in detail above in "A. Surface-Treated Copper Foil." The surface-treated copper foil may be disposed on one side of the resin layer or on both sides of the resin layer. It is preferable that the surface-treated copper foil is in contact with the resin layer.

[0084] When measuring the area ratio of the surface portion to one side of a surface-treated copper foil, the surface-treated copper foil is first peeled from a copper-clad laminate. The peeling method for the surface-treated copper foil involves holding the surface (first side of the surface-treated copper foil) opposite to the surface of the surface-treated copper foil to be measured (second side of the surface-treated copper foil) with a pressure-sensitive adhesive or adhesive that is sufficiently resistant to peeling, creating a trigger at the interface between the surface-treated copper foil and the resin layer, and pulling the surface-treated copper foil to expose the second side of the surface-treated copper foil.

[0085] 2. Resin Layer The resin layer contains a resin component and a fibrous base material. A laminate formed by laminating multiple prepregs can be used as the resin layer. Prepregs are composite materials in which a fibrous base material is impregnated with a resin component. Prepregs generally used in copper-clad laminates can be used as the prepregs.

[0086] 3. Copper-Clad Laminate The copper-clad laminate of the present disclosure may have a resin layer and the above-described surface-treated copper foil disposed on one or both sides of the resin layer, and any known layer structure may be used as the layer structure of the copper-clad laminate.

[0087] The copper clad laminate is appropriately selected depending on the layer structure of the copper clad laminate. For example, the above-mentioned carrier-attached copper foil is placed on both sides or one side of a laminate formed by stacking a plurality of the above-mentioned prepregs, and heated and pressed as necessary, thereby transferring the surface-treated copper foil to one or both sides of the resin layer that is the prepreg laminate, thereby producing a copper clad laminate. The heating and pressing conditions can be appropriately set depending on the thickness of the copper clad laminate, the type of resin layer, etc.

[0088] D. Printed Wiring Board The printed wiring board according to the present disclosure comprises a resin layer and a patterned surface-treated copper foil disposed on one or both sides of the resin layer, the surface-treated copper foil comprising copper foil and a surface portion containing selenium disposed on one side of the copper foil, the surface portion occupying an area ratio of 30.0% or more to less than 100.0% of the one side of the copper foil, and the surface-treated copper foil is disposed such that the surface of the surface portion faces the resin layer.

[0089] 6( a) and 6(b) are schematic cross-sectional views illustrating printed wiring boards according to the present disclosure. The printed wiring board 50 shown in Fig. 6(a) has a resin layer 51 and a patterned surface-treated copper foil 1 disposed on one side of the resin layer 51. The printed wiring board 50 shown in Fig. 6(b) has a resin layer 51 and patterned surface-treated copper foils 1 disposed on both sides of the resin layer 51. The surface-treated copper foil 1 has, in order from the side opposite the resin layer 51, a copper foil 1a and a surface portion 1b containing selenium, and the area ratio of the surface portion 1b to one side of the copper foil 1a is 30.0% or more and less than 100.0%.

[0090] In the printed wiring board of the present disclosure, as described above in the section "A. Surface-treated copper foil," the surface-treated copper foil has a surface portion containing selenium with a predetermined area ratio on the surface facing the resin layer, thereby improving the adhesion between the surface-treated copper foil and the resin layer.

[0091] Hereinafter, each configuration of the printed wiring board according to the present disclosure will be described.

[0092] 1. Surface-Treated Copper Foil The surface-treated copper foil according to the present disclosure is patterned. The surface-treated copper foil has, in order from the side opposite the resin layer, a copper foil and a surface portion containing selenium. Furthermore, the area ratio of the surface portion to one side of the copper foil is 30.0% or more and less than 100.0%.

[0093] The surface-treated copper foil is the same as that described above in "A. Surface-treated copper foil."

[0094] The surface-treated copper foil may be disposed on one side of the resin layer or on both sides of the resin layer, and is preferably in contact with the resin layer.

[0095] When measuring the area ratio of the surface portion to one side of the surface-treated copper foil, the surface-treated copper foil is first peeled off from the printed wiring board in the same manner as the method for peeling off the resin layer described in the above section "C. Copper-clad laminate."

[0096] 2. Resin Layer The resin layer is the same as the resin layer in the copper-clad laminate.

[0097] 3. Printed Wiring Board The printed wiring board of the present disclosure may have a resin layer and a patterned surface-treated copper foil disposed on one or both sides of the resin layer, and any known layer configuration may be used as the layer configuration of the printed wiring board.

[0098] Examples of the printed wiring board include a single-sided or double-sided printed wiring board, a multilayer printed wiring board, a flexible printed wiring board, a flexible printed wiring board, etc. The printed wiring board may also be a build-up wiring board.

[0099] The method for manufacturing the printed wiring board is appropriately selected depending on the layer structure of the printed wiring board.

[0100] For example, using the above-mentioned copper foil with a carrier, a surface-treated copper foil is transferred to one or both sides of a resin layer, which is a prepreg, to produce a copper-clad laminate, and then the surface-treated copper foil is patterned to form a circuit, thereby producing a single-sided or double-sided printed wiring board.

[0101] Furthermore, by multi-layering the above single-sided or double-sided printed wiring board, a multi-layer printed wiring board can be produced.

[0102] Furthermore, for example, a flexible printed wiring board can be produced by using the above-mentioned copper foil with a carrier to transfer a surface-treated copper foil to one side of a resin film, and then patterning the surface-treated copper foil to form a circuit.

[0103] The manufacturing method of the build-up wiring board is not particularly limited, but is preferably a defined semi-additive (MSAP) method, which is suitable for forming fine wiring.

[0104] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure.

[0105] The present disclosure will be described in more detail below with reference to examples and comparative examples.

[0106] Example 1: A carrier substrate was used, which consisted of a 12.5 μm thick polyimide film (Kapton manufactured by DuPont-Toray Co., Ltd.), a 6 μm thick acrylic adhesive layer, and a release film (Somare's "Somatack EXP12.5PI1-200 (6 μm)"). An 8 μm thick copper foil (Furukawa Electric Co., Ltd.'s "NC-WS") was laminated onto the adhesive layer of the carrier substrate. The copper foil was then etched using a ferric chloride-based etching solution until its thickness was reduced to 3 μm. The copper foil was then roughened using a ferric chloride solution with a specific gravity of 14 Bh and a temperature of 35°C. After the copper foil roughening treatment, it was subjected to a black oxide treatment by spraying. For the black dyeing process, a black dyeing agent "Blacky CN-20" manufactured by Tobi Chemical Co., Ltd. was used, diluted with pure water to a concentration of 5.0% by volume (i.e., diluted 20 times). Blacky CN-20 is a room-temperature black dyeing agent containing selenious acid, zinc sulfate, zinc chloride, zinc phosphate, and purified water. A copper foil with a carrier was produced using this.

[0107] [Example 2] A copper foil with a carrier was produced in the same manner as in Example 1, except that in the black dyeing treatment, a black dyeing agent "Blacky CN-20" manufactured by Tobi Chemical Industry Co., Ltd. was diluted with pure water to 10% by volume (i.e., diluted 10 times).

[0108] [Example 3] A copper foil with a carrier was produced in the same manner as in Example 1, except that in the black dyeing treatment, a black dyeing agent "Blacky CN-20" manufactured by Tobi Chemical Industry Co., Ltd. was diluted with pure water to 15% by volume (i.e., diluted approximately 6.7 times).

[0109] [Comparative Example 1] A copper foil with a carrier was produced in the same manner as in Example 1, except that in the black dyeing treatment, a black dyeing agent "Blacky CN-20" manufactured by Tobi Chemical Industry Co., Ltd. was diluted with pure water to 1% by volume (i.e., diluted 100 times).

[0110] [Comparative Example 2] A copper foil with a carrier was produced in the same manner as in Example 1, except that in the black dyeing treatment, a black dyeing agent "Blacky CN-20" manufactured by Tobi Chemical Industry Co., Ltd. was diluted with pure water to 2.5% by volume (i.e., diluted approximately 40 times).

[0111] [Comparative Example 3] A copper foil with a carrier was produced in the same manner as in Example 1, except that in the black dyeing treatment, a black dyeing agent "Blacky CN-20" manufactured by Tobi Chemical Industry Co., Ltd. was diluted with pure water to 17.5% by volume (i.e., diluted approximately 5.7 times).

[0112] [Comparative Example 4] A copper foil with a carrier was produced in the same manner as in Example 1, except that after the roughening treatment of the copper foil, surface treatment was carried out using an inorganic treatment agent containing Zr instead of the black dyeing treatment. As the inorganic treatment agent containing Zr, "New Dain Silver TN (manufactured by Daiwa Chemical Industry Co., Ltd.)" diluted with pure water to 5.0% by volume (i.e., diluted 20 times) was used.

[0113] Comparative Example 5 A copper foil with a carrier was produced in the same manner as in Example 1, except that after the roughening treatment of the copper foil, surface treatment was carried out using an inorganic treatment agent containing Ni instead of blackening treatment. As the inorganic treatment agent containing Ni, "S-680 (manufactured by Nippon Kanigen)" diluted with pure water to 10% by volume (i.e., diluted 10 times) was used.

[0114] Comparative Example 6 A copper foil with a carrier was produced in the same manner as in Example 1, except that after the roughening treatment of the copper foil, surface treatment was carried out using an inorganic treatment agent containing Ag instead of blackening treatment. As the inorganic treatment agent containing Ag, "VERZONE NP-1 (manufactured by Daiwa Chemical Industry Co., Ltd.)" diluted with pure water to 10% by volume (i.e., diluted 10 times) was used.

[0115] Comparative Example 7 A carrier-attached copper foil was produced in the same manner as in Example 1, except that after the copper foil roughening treatment, a surface treatment was carried out using a silane coupling agent-type treatment agent instead of the black dye treatment. As the silane coupling agent-type treatment agent, a silane coupling agent-type functional copper tarnish inhibitor "IS-1" manufactured by JX Nippon Mining & Metals Corporation was used, diluted with pure water to 5.0% by volume (i.e., diluted 20 times).

[0116] [Example 4] After preparing a copper foil with a carrier in the same manner as in Example 1, a surface treatment was further carried out using a silane coupling agent-type functional copper tarnish inhibitor "IS-1" manufactured by JX Nippon Mining & Metals Corporation diluted with pure water to a concentration of 5.0% by volume (i.e., diluted 20 times).

[0117] [Example 5] After preparing a copper foil with a carrier in the same manner as in Example 2, a surface treatment was further carried out using a silane coupling agent-type functional copper tarnish inhibitor "IS-1" manufactured by JX Nippon Mining & Metals Corporation diluted with pure water to a concentration of 5.0% by volume (i.e., diluted 20 times).

[0118] [Example 6] After preparing a copper foil with a carrier in the same manner as in Example 3, a surface treatment was further carried out using a silane coupling agent-type functional copper tarnish inhibitor "IS-1" manufactured by JX Nippon Mining & Metals Corporation diluted with pure water to a concentration of 5.0% by volume (i.e., diluted 20 times).

[0119] [Evaluation] (1) Composition Analysis The surface of the carrier-attached copper foils of the examples and comparative examples opposite to the carrier substrate was subjected to X-ray photoelectron spectroscopy (XPS) analysis to confirm the presence of selenium. XPS was performed using a Quantax Q400 (attached to an ULTRA55 manufactured by ZEISS) under the conditions of monochromated Al-Kα radiation, an output of 5 kV, and a TOA of 45° in a range of 200 μmφ.

[0120] (2) Area Ratio of Surface Portion For the carrier-attached copper foils of the Examples and Comparative Examples, a scanning electron microscope (ZEISS "ULTRA55") was used to photograph the surface of the surface-treated copper foil at a magnification of 500,000 times to obtain image X. Next, using image analysis software ImageJ (National Institutes of Health, USA), a 0.781 μm × 0.781 μm (350 × 350 pixels) area was trimmed to include a relatively flat area, and a trimmed image Y was obtained. This trimmed image Y was binarized under the following conditions into the surface portion containing selenium (white portion) and the other portion (black portion, i.e., copper foil surface portion), and a binarized image Z was obtained.

[0121] The size of the surface area (selenium) attached to the copper foil surface is detected by drawing a line around the outer diameter of the surface area. The average surface area is calculated by dividing the total area of ​​each detected surface area by the number of surface areas. The total surface area is calculated by multiplying the average surface area by the number of surface areas. The percentage of the surface area is calculated from (total surface area / area of ​​cropped image Y). This surface area includes both selenium particles and composites of selenium particles.

[0122] The Count, Average Size, Total Area, and % Area were calculated for the entire region of this binarized image using the following calculation method. Count is the number of particles, Average Size is the average size of the particles, Total Area is the total area of ​​the particles, and % Area is the ratio of the total area of ​​the particles to the entire region of the binarized image. % Area was taken as the area ratio of the surface portion. This procedure was repeated five times, and the arithmetic average value was used. The results are shown in Table 1. Images X, Y, and Z of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Figures 7 and 8.

[0123] <Image analysis conditions> Image analysis software: ImageJ Settings Brightness: No adjustment Contrast: No adjustment Threshold: 70-100 (255 gradations) Analysis area: 0.781 μm × 0.781 μm (350 × 350 pixels)

[0124] <Calculation method> Calculation method: Calculated using Analyze Particles Calculation conditions: Size (^2): 0-Infinity Circularity: 0.00-1.00 Include holes: The outer diameter of the surface is detected by encircling it with a line

[0125] (3) Rz A small surface roughness measuring instrument ("SURFCOM SJ-210" manufactured by Mitutoyo Corporation) was used as a surface roughness measuring instrument, and the Rz of the surface opposite to the carrier substrate of the copper foils with carriers of the examples and comparative examples was measured under the above-mentioned measuring conditions.

[0126] (4) Adhesion The peel strength between the copper foil and the prepreg was measured as an index of adhesion between the copper foil and the resin layer. The prepreg used was "GHPL-830 SQ73" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0127] The carrier-attached copper foil and prepreg of each of the examples and comparative examples were stacked together and subjected to vacuum hot pressing. The carrier substrate was then peeled off from the laminate of the carrier-attached copper foil and prepreg, transferring the copper foil to one side of the prepreg. Next, a photosensitive resin (dry film) was attached, exposed to light, developed, and the copper foil was etched. The photosensitive resin was then peeled off to form a 1 cm wide pattern. Next, the copper foil was plated up to a thickness of 12 μm by electroplating. This resulted in a test specimen.

[0128] A peel test was performed using a force gauge (Imada Co., Ltd. "ZTS-50N"), an electric test stand (Imada Co., Ltd. "MX2-500N"), and a 90-degree peel test jig (Imada Co., Ltd. "P900-200N") at a peel speed of 300 mm / sec, a peel angle of 90°, and a peel length of 80 mm. A time-load curve was obtained using Imada Co., Ltd.'s "Force Recorder Standard" software, and the peel strength between the copper foil and the prepreg was measured from the average value of the stable portion of the time-load curve.

[0129] (5) Moisture and Heat Resistance The copper foils with carriers of the Examples and Comparative Examples were subjected to a moisture and heat resistance test at 130°C and 85% humidity for 100 hours. After the moisture and heat resistance test, the peel strength between the copper foil and the prepreg was measured using the same method as in (4) Adhesion.

[0130]

[0131] As can be seen from Table 1, Examples 1 to 6, in which the area ratio of the surface portion containing selenium was within a predetermined range, exhibited a high peel strength between the copper foil and the prepreg. On the other hand, it was confirmed that the copper foils of Comparative Examples 1 to 3, in which the area ratio of the surface portion containing selenium was small, and Comparative Examples 4 to 7, which had no surface portion containing selenium, exhibited a low peel strength between the copper foil and the prepreg.

[0132] In Examples 1 to 3, the peel strength between the copper foil and the prepreg was maintained at 3.0 N / cm or more even after the moist heat resistance test. On the other hand, in Examples 4 to 6, which were treated with a silane coupling agent, the peel strength between the copper foil and the prepreg decreased after the moist heat resistance test.

[0133] The present disclosure provides the following inventions. [1] A surface-treated copper foil comprising a copper foil and a surface portion containing selenium, the surface portion being disposed on one side of the copper foil, wherein the area ratio of the surface portion to the one side of the copper foil is 30.0% or more and less than 100.0%. [2] The surface-treated copper foil according to [1], wherein the roughness in maximum height Rz of the surface on the surface portion side is 0.6 μm or more and 1.2 μm or less. [3] A carrier-attached copper foil comprising a carrier substrate and the surface-treated copper foil according to [1] or [2], disposed on one side of the carrier substrate, the copper foil-side surface of the surface-treated copper foil being disposed on the carrier substrate side. [4] The carrier-attached copper foil according to [3], wherein the carrier substrate comprises, in order from the surface-treated copper foil side, an adhesive layer and a resin substrate. [5] The carrier-attached copper foil according to [3], wherein the carrier substrate comprises, in order from the surface-treated copper foil side, a release layer and a metal foil. [6] A copper-clad laminate comprising: a resin layer; and the surface-treated copper foil according to [1] or [2], disposed on one or both sides of the resin layer, wherein the surface-treated copper foil is disposed so that the surface of the surface portion faces the resin layer. [7] A printed wiring board comprising: a resin layer; and a patterned surface-treated copper foil disposed on one or both sides of the resin layer, wherein the surface-treated copper foil has copper foil and a surface portion containing selenium, disposed on one side of the copper foil, wherein the surface-treated copper foil is disposed so that the surface of the surface portion faces the resin layer, and wherein the area ratio of the surface portion to the one side of the copper foil is 30.0% or more and less than 100.0%.

[0134] REFERENCE SIGNS LIST 1... surface-treated copper foil 1a... copper foil 1b... surface portion 2... resin substrate 3... adhesive layer 4... carrier copper 5... release layer 10, 20... carrier-attached copper foil 11... carrier substrate 21, 31, 41... resin layer 30... copper-clad laminate 50... printed wiring board

Claims

1. A surface-treated copper foil comprising a copper foil and a surface portion containing selenium arranged on one side of the copper foil, the surface portion having an area ratio of 30.0% or more to less than 100.0% of the area of ​​the one side of the copper foil.

2. The surface-treated copper foil according to claim 1, wherein the maximum height roughness Rz of the surface on the surface portion side is 0.6 μm or more and 1.2 μm or less.

3. A copper foil with a carrier, comprising: a carrier substrate; and a surface-treated copper foil according to claim 1 or claim 2, disposed on one side of the carrier substrate, wherein the surface-treated copper foil is disposed so that the copper foil side faces the carrier substrate.

4. The copper foil with a carrier according to claim 3, wherein the carrier substrate has, in this order from the surface-treated copper foil side, an adhesive layer and a resin substrate.

5. The copper foil with a carrier according to claim 3, wherein the carrier base material has, in this order from the surface-treated copper foil side, a release layer and a metal foil.

6. A copper-clad laminate comprising a resin layer and the surface-treated copper foil according to claim 1 or 2 disposed on one or both sides of the resin layer, the surface-treated copper foil being disposed so that the surface portion side faces the resin layer.

7. A printed wiring board comprising: a resin layer; and a patterned surface-treated copper foil disposed on one or both sides of the resin layer, wherein the surface-treated copper foil comprises copper foil and a surface portion containing selenium disposed on one side of the copper foil, the surface-treated copper foil is disposed so that the surface portion side faces the resin layer, and the area ratio of the surface portion to the one side of the copper foil is 30.0% or more and less than 100.0%.

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