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

Abstract

This disclosure provides a surface-treated copper foil having a copper foil and a selenium-containing surface portion 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%.

Description

Technical Field

[0001] This disclosure relates to surface-treated copper foil, copper foil with a carrier, copper-clad laminate, and printed wiring substrate. Background Technology

[0002] In printed wiring substrates, copper foil is preferably used as the wiring material (e.g., Patent Document 1). In printed wiring substrates, to ensure reliability, it is desirable to improve the adhesion between the resin layer and the copper foil.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 188837 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] This disclosure was made in view of the above-mentioned circumstances, and its main purpose is to provide a surface-treated copper foil with good adhesion to the resin layer.

[0008] Methods for solving problems

[0009] One embodiment of this disclosure provides a surface-treated copper foil comprising: a copper foil; and a selenium-containing surface portion 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%.

[0010] Another embodiment of this disclosure provides a copper foil with a carrier, comprising: a carrier substrate; and the aforementioned surface-treated copper foil disposed on one side of the carrier substrate, wherein the surface-treated copper foil is disposed such that the copper foil side is on the carrier substrate side.

[0011] Another embodiment of this disclosure provides a copper-clad laminate having: a resin layer; and the aforementioned surface-treated copper foil disposed on one or both sides of the resin layer, wherein the surface-treated copper foil is disposed such that the surface portion side is on the resin layer side.

[0012] Another embodiment of this disclosure provides a printed wiring substrate having: 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 having: a copper foil; and a selenium-containing surface portion disposed on one side of the copper foil, the surface-treated copper foil being disposed such that the surface portion side is located on the resin layer side, and the area ratio of the surface portion relative to the one side of the copper foil is 30.0% or more and less than 100.0%.

[0013] Invention Effects

[0014] In this disclosure, a surface-treated copper foil that provides good adhesion to the resin layer can be achieved. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view illustrating the surface-treated copper foil in this disclosure.

[0016] Figure 2 This is a schematic cross-sectional view illustrating a copper foil with a carrier in this disclosure.

[0017] Figure 3 This is a process diagram illustrating the transfer method of copper foil with a carrier in this disclosure.

[0018] Figure 4 This is a schematic cross-sectional view illustrating a copper foil with a carrier in this disclosure.

[0019] Figure 5 This is a schematic cross-sectional view illustrating the copper-clad laminate in this disclosure.

[0020] Figure 6 This is a schematic cross-sectional view illustrating the printed wiring substrate in this disclosure.

[0021] Figure 7 These are images X, Y, and Z from Examples 1 to 3.

[0022] Figure 8 The images are X, Y, and Z from Comparative Examples 1 to 3. Detailed Implementation

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure can be implemented in many different ways and is not limited to the description of the embodiments illustrated below. Furthermore, regarding the drawings, to make the description clearer, the width, thickness, shape, etc., of each part are sometimes schematically shown compared to the actual form; however, this is merely an example and does not limit the interpretation of the present disclosure. Additionally, in this specification and the drawings, the same reference numerals are sometimes used for elements that are the same as those described with respect to previously shown figures, and detailed descriptions are appropriately omitted.

[0024] In this specification, when describing the configuration of other components mounted on a component, the use of only "on" or "below" includes, unless otherwise specified, both cases where the other component is mounted directly above or below the component in contact with it, and cases where another component is mounted above or below the component, separated by another component. Similarly, when describing the configuration of other components mounted on the surface of a component, the use of only "on the side of" or "on the surface" includes, unless otherwise specified, both cases where the other component is mounted directly above or below the component in contact with it, and cases where another component is mounted above or below the component, further via another component.

[0025] In addition, in this specification, "membrane" also includes components referred to as "sheet".

[0026] The following provides a detailed description of the surface-treated copper foil, the carrier-supported copper foil, the copper-clad laminate, and the printed wiring substrate in this disclosure.

[0027] A. Surface-treated copper foil

[0028] The surface-treated copper foil of this disclosure comprises: a copper foil; and a selenium-containing surface portion 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%.

[0029] Figure 1 This is a schematic cross-sectional view illustrating the surface-treated copper foil in this disclosure. Figure 1 The surface-treated copper foil 1 has a copper foil 1a and a selenium-containing surface portion 1b disposed on one side A1 of the copper foil 1a. The area ratio of the surface portion 1b to one side A1 of the copper foil 1a is within a specified range.

[0030] According to this disclosure, by arranging a selenium-containing surface portion on one side of a copper foil in a manner that constitutes a predetermined area ratio, it is possible to achieve good adhesion between the surface-treated copper foil and the resin layer.

[0031] Furthermore, the surface-treated copper foil in this disclosure has a selenium-containing surface portion. The inventors of this application conducted research and found that when surface-treating copper foil with selenium, the adhesion to the resin layer becomes better compared to surface treatment with other metals such as zirconium, nickel, and silver. In addition, conventional surface treatments for copper foil based on organic materials such as silane coupling agents are known. However, organic materials tend to have poor heat resistance, and there is a concern that surface treatments based on organic materials reduce adhesion to the resin layer under high temperature and humidity conditions. In contrast, surface treatment using selenium is based on inorganic materials, thus improving heat resistance and maintaining adhesion to the resin layer even under high temperature and humidity conditions. Furthermore, while surface treatment using other metals such as tin can be considered, selenium has fewer negative environmental impacts compared to tin. In addition, selenium has the following advantages: it can form a coating on the copper surface at a low temperature of around 40°C and in a short time; and, as an element in the same group as sulfur, it can obtain oxidation states of -2 to +6, thus exhibiting high chemical surface reactivity. Therefore, in this disclosure, it is important that the surface portion contains selenium.

[0032] The components of the surface-treated copper foil in this disclosure will be described below.

[0033] 1. Layer structure of surface-treated copper foil

[0034] The surface-treated copper foil of this disclosure has a copper foil and a selenium-containing surface portion disposed on one side of the copper foil.

[0035] (1) Copper foil

[0036] Copper foil contains copper or copper alloys. As for copper alloys, there are no particular limitations as long as they can be used to make copper foil.

[0037] The thickness of the copper foil is appropriately selected based on the intended use and manufacturing method of the surface-treated copper foil. As described below, 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 or more and 35 μm or less, or 0.6 μm or more and 18 μm or less, or 0.8 μm or more and 12 μm or less, or 1 μm or more and 5 μm or less. When the thickness of the copper foil is as thin as described above, 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 or more and 35 μm or less, or 6 μm or more and 18 μm or less, or 8 μm or more and 12 μm or less.

[0038] As copper foil, rolled copper foil or electrolytic copper foil can be used, for example.

[0039] (2) Surface part

[0040] The surface portion is disposed on one side of the aforementioned copper foil and contains selenium. The selenium content of the surface portion was analyzed by X-ray photoelectron spectroscopy (XPS). The measurement conditions are described in the embodiments described later.

[0041] In this disclosure, the area ratio of the surface portion relative to one side of the copper foil is 30.0% or more, preferably 32.0% or more, and more preferably 34.0% or more. By setting the area ratio of the surface portion within the above range, the adhesion to the resin layer is improved. On the other hand, the area ratio of the surface portion relative 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, it results in an excessive formation of the surface portion. Therefore, the surface portion is easily peeled off, and the adhesion to the resin layer decreases. Specifically, the area ratio of the surface portion relative 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.

[0042] The area ratio of the surface portion relative to one side of the copper foil can be adjusted, for example, by adjusting the concentration of selenium compounds in the room-temperature black dye (described later) and the processing time. Specifically, a shorter processing time results in a smaller area ratio of the surface portion, while a longer processing time results in a larger area ratio. Furthermore, a lower concentration of selenium compounds in the room-temperature black dye results in a smaller area ratio of the surface portion, while a higher concentration results in a larger area ratio.

[0043] The area ratio of the surface portion relative to one side of the copper foil is determined by the following method. First, an image is acquired from the surface portion side of the surface-treated copper foil using a scanning electron microscope (SEM). Next, an image is obtained by cropping the image to include relatively flat areas using image analysis software. Then, the cropped image is binarized into the surface portion and other portions to obtain a binarized image. Next, the surface portion is selected from the binarized image, and the area ratio of the surface portion in the resolved area is calculated. The image acquisition conditions, image analysis conditions, and calculation methods are described in the embodiments described later.

[0044] The surface portion is preferably partially disposed on one side of the copper foil. More specifically, the surface portion is preferably distributed on one side of the copper foil.

[0045] The surface portion preferably has multiple selenium-containing particles. The number of selenium-containing particles per μm on one side of the copper foil is preferably 1500 particles / μm. 2 Below, 1000 per μm is preferred. 2 The average size of the selenium-containing particles is preferably 400 nm. 2The above, preferably 500nm 2 The above describes the improvement in adhesion to the resin layer by setting the number and average size of the particles within the aforementioned range. On the other hand, the number of selenium-containing particles in one side of the copper foil is, for example, 300 particles / μm. 2 The above can also be 500 per μm. 2 That's all. Additionally, the average size of the selenium-containing particles is, for example, 700 nm. 2 The following should be noted: the number of particles and their average size are calculated from the binarized image.

[0046] Methods for forming the surface portion include surface treatment of copper foil. Examples of surface treatment methods include electroplating, electroless plating, chemical conversion treatment, vacuum evaporation, sputtering, and PVD.

[0047] Among these methods, chemical conversion treatment is preferred, and in the case of chemical conversion treatment, room temperature black dyeing treatment is preferred. In room temperature black dyeing treatment, the surface can be formed in a short time by coating the copper foil with black dye, immersing the copper foil in black dye, or spraying.

[0048] In the case of chemical conversion treatment at room temperature, room-temperature black dye containing selenium compounds is preferred. With room-temperature black dye containing selenium compounds, a selenium-containing surface layer can be easily formed by impregnation or spraying. Examples of selenium compounds include selenite (H₂SeO₃).

[0049] Furthermore, the surface-treated copper foil preferably does not have a surface treatment layer formed of organic matter such as coupling agents on one side of the copper foil. Surface treatment layers formed of organic matter have poor resistance to damp heat due to their high carbon content. By eliminating the organic surface treatment layer from the surface-treated copper foil, excellent adhesion to the resin layer can be maintained even in humid and hot environments. Additionally, since the surface-treated copper foil preferably does not have a surface treatment layer formed of organic matter such as coupling agents on one side of the copper foil, the selenium-containing surface portion is preferably located at the outermost surface of the surface-treated copper foil.

[0050] 2. Surface properties of surface-treated copper foil

[0051] In this disclosure, the maximum height roughness Rz of the surface portion of the surface-treated copper foil is preferably 0.6 μm or more, more preferably 0.7 μm or more, and even more preferably 0.8 μm or more. By setting Rz within the above range, the adhesion between the surface-treated copper foil and the resin layer can be further improved. On the other hand, there is no particular limitation on the upper limit of Rz, as long as it can be formed, for example, it is 2.3 μm or less. Among these, 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 setting Rz within the above range, transmission loss can be suppressed. Specifically, 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.

[0052] Generally, low surface roughness is required for copper foil to suppress transmission loss. However, the adhesion between copper foil with low surface roughness and the resin layer can easily become insufficient. In this disclosure, the surface roughness Rz of the surface-treated copper foil is as small as described above. Even with low roughness, the adhesion to the resin layer can be improved by keeping the area ratio of the selenium-containing surface portion within a specified range. That is, both good adhesion to the resin layer and suppression of transmission loss can be achieved.

[0053] The aforementioned Rz can be adjusted, for example, by changing the method or conditions of the roughening treatment of the copper foil. For instance, by using etching as a roughening treatment, Rz can be made smaller.

[0054] The maximum height roughness Rz is a value obtained based on the method in JIS B0601:2013. The maximum height roughness Rz is one of the peak and height parameters of the profile curve; it is the sum of the height of the highest peak and the depth of the deepest valley in the profile curve over a reference length. A larger maximum height roughness Rz value indicates a greater number of convex features when viewed from the valley (concave area), thus serving as an indicator of the prevalence of such convex features.

[0055] Furthermore, when measuring the maximum height roughness Rz, the cutoff value was set to 0.8 mm. Additionally, the maximum height roughness Rz is the average of measurements taken at any 5 locations.

[0056] Additionally, the term "surface side of surface-treated copper foil" refers to, for example, the surface side of the copper foil. Figure 1 As shown, the surface S2 of the surface-treated copper foil 1 is located on the surface portion 1b side, with copper foil 1a as a reference. Hereinafter, the surface portion side of the surface-treated copper foil is sometimes referred to as the second surface. In addition, the surface-treated copper foil 1 has a first surface S1 opposite to the second surface S2.

[0057] Furthermore, the arithmetic mean height Ra of the surface portion of the surface-treated copper foil is preferably 0.105 μm or more, more preferably 0.110 μm or more. By setting Ra within this range, good adhesion between the surface-treated copper foil and the resin layer can be achieved. On the other hand, Ra is preferably 0.165 μm or less, more preferably 0.160 μm or less. By setting Ra within this range, transmission loss can be suppressed. Specifically, 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.

[0058] The arithmetic mean height Ra is a value obtained according to the method in JIS B0601:2013. The arithmetic mean height Ra is one of the parameters in the height direction of the profile curve, and it is the average of the height differences from the mean surface in the profile curve along the reference length. Furthermore, the cutoff value is set to 0.8 mm when measuring the arithmetic mean height Ra. Additionally, the arithmetic mean height Ra is the average of the measurements taken at any 5 points. The adjustment method for Ra is the same as the adjustment method for Rz described above.

[0059] Furthermore, the maximum peak height Rp on the surface of the surface-treated copper foil is preferably 0.20 μm or more, more preferably 0.25 μm or more. By setting Rp within this range, good adhesion between the surface-treated copper foil and the resin layer can be achieved. On the other hand, Rp is preferably 0.55 μm or less, more preferably 0.50 μm or less. By setting Rp within this range, transmission loss can be suppressed. Specifically, 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.

[0060] The maximum peak height Rp is obtained according to the method in JIS B0601:2013. Furthermore, the cutoff value for measuring the maximum peak height Rp is set to 0.8 mm. The maximum peak height Rp is also the average of five measurements taken at any given location. The adjustment method for Rp is the same as that for Rz described above.

[0061] B. Copper foil with carrier

[0062] The copper foil with a carrier disclosed herein includes: a carrier substrate; and the aforementioned surface-treated copper foil disposed on one side of the carrier substrate, wherein the surface-treated copper foil is disposed such that the copper foil side is on the carrier substrate side.

[0063] The carrier-bearing copper foil of this disclosure is used for the transfer of surface-treated copper foil. For example, after laminating the carrier-bearing copper foil with a resin layer, the carrier substrate is peeled off from the carrier-bearing copper foil, thereby transferring the surface-treated copper foil onto one side of the resin layer. The carrier-bearing copper foil of this disclosure, by having the above-described surface-treated copper foil, can improve the adhesion between the surface-treated copper foil and the resin layer.

[0064] The components of the surface-treated copper foil in this disclosure will be described below.

[0065] 1. Surface-treated copper foil

[0066] The surface-treated copper foil is the same as the surface-treated copper foil described in "A. Surface-treated copper foil" above. The surface-treated copper foil is arranged such that the copper foil side is facing the carrier substrate side.

[0067] 2. Carrier substrate

[0068] The carrier substrate is the component that supports the surface-treated copper foil described above. There are no particular limitations on the carrier substrate as long as it can support the surface-treated copper foil, but it must have at least a substrate layer. For example, a metal substrate, resin substrate, glass substrate, ceramic substrate, or silicon wafer can be used as the substrate layer. Furthermore, the substrate layer can be rigid or flexible.

[0069] The layer structure of the carrier substrate is not particularly limited. For example, the carrier substrate may have an adhesive layer and a substrate layer sequentially from the surface-treated copper foil side, or it may have a release layer and a substrate layer. Hereinafter, as specific examples, we will describe the case where the carrier substrate has an adhesive layer and a resin substrate sequentially from the surface-treated copper foil side, and the case where the carrier substrate has a release layer and a carrier copper foil sequentially from the surface-treated copper foil side.

[0070] (1) First method

[0071] The carrier substrate of this method has an adhesive layer and a resin substrate sequentially from the copper foil side.

[0072] Figure 2 This is a schematic cross-sectional view illustrating a copper foil with a carrier in this disclosure. Figure 2 The copper foil 10 with a carrier has: a carrier substrate 11 having a resin substrate 2 and an adhesive layer 3 disposed on one side of the resin substrate 2; and the aforementioned surface-treated copper foil 1 disposed on the side of the adhesive layer 3 of the carrier substrate 11. The surface-treated copper foil 1 is disposed such that the side S1 of the copper foil 1a is on the side of the adhesive layer 3.

[0073] In this method, by using a resin substrate as the carrier substrate, costs can be reduced compared to using a copper foil carrier. In particular, by using an inexpensive resin substrate, costs can be significantly reduced.

[0074] Furthermore, in this method, by using a resin substrate for the carrier substrate, the carrier substrate can also be made transparent. When the carrier substrate is transparent, defects on the carrier substrate side of the surface-treated copper foil can be inspected by observing it from the carrier substrate side. Therefore, the yield rate can be improved.

[0075] Furthermore, when using carrier copper foil on the carrier substrate, it is difficult to identify defects on the carrier substrate side of the surface-treated copper foil.

[0076] As described above, the carrier-bearing copper foil in this disclosure is used for the transfer of surface-treated copper foil. For example, as Figure 3 (a) ~ Figure 3 As shown in (b), after the copper foil 10 with a carrier is laminated with the resin layer 21, the carrier substrate 11 is peeled off from the copper foil 10 with a carrier, thereby transferring the surface-treated copper foil 1 onto one surface of the resin layer 21. As described above, by giving the copper foil with a carrier the aforementioned surface-treated copper foil, the adhesion between the surface-treated copper foil and the resin layer can be improved.

[0077] (a) Resin substrate

[0078] The resin substrate is a component that supports the adhesive layer and the surface-treated copper foil. There are no particular limitations on the resin constituting the resin substrate; examples include polyester resin, polyimide resin, polyamide resin, polyamide-imide resin, polybenzoxazole resin, aromatic polyamide resin, polystyrene resin, polyetheretherketone resin, polyphenylene sulfide resin, polyethersulfone resin, and polyarylate resin. Examples of polyester resins include polyethylene terephthalate and polyethylene naphthalate.

[0079] Preferably, the resin substrate has heat resistance. When transferring surface-treated copper foil to the resin layer using the carrier-bearing copper foil of this disclosure, the carrier-bearing copper foil and the resin layer are sometimes heated. By making the resin substrate heat-resistant, the heating process can be performed.

[0080] When the resin substrate has heat resistance, the resin constituting the resin substrate may include, for example, polyimide resin, polyamide resin, polyamide-imide resin, polybenzoxazole resin, aromatic polyamide resin, syndiotactic polystyrene resin, polyetheretherketone resin, polyphenylene sulfide resin, polyethersulfone resin, and polyarylate resin.

[0081] The resin substrate is preferably transparent. When the resin substrate is transparent, defects on the resin substrate side of the surface-treated copper foil can be inspected by observing it from the resin substrate side. Therefore, the yield can be improved.

[0082] When the resin substrate is transparent, the total light transmittance of the resin substrate is 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 according to JIS K7361-1:1997.

[0083] The thickness of the resin substrate is 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 resin substrate is too thin, the operability of the copper foil with the carrier may be impaired, or it may be difficult to peel the carrier substrate from the copper foil with the carrier. In addition, even if the resin substrate is too thick, it may be difficult to peel the carrier substrate from the copper foil with the carrier. Furthermore, if the resin substrate is too thick, the transparency of the resin substrate may be reduced.

[0084] (b) Adhesive layer

[0085] The adhesive layer is a component disposed between the resin substrate and the surface-treated copper foil. When transferring the surface-treated copper foil to the resin layer using the carrier-bearing copper foil of this disclosure, peeling is performed at the interface between the adhesive layer and the surface-treated copper foil.

[0086] There are no particular limitations on the adhesive layer, as long as it can tightly bond the resin substrate and the copper foil and has re-peelability. Examples of adhesives used in the adhesive layer include acrylic adhesives, urethane adhesives, and silicone adhesives.

[0087] Preferably, the adhesive layer has heat resistance. When transferring surface-treated copper foil to a resin layer using the carrier-bearing copper foil of this disclosure, the carrier-bearing copper foil and the resin layer are sometimes heated. By making the adhesive layer heat-resistant, the heating process can be performed.

[0088] From the viewpoints of peelability, heat resistance, and transparency, acrylic adhesives are preferred as adhesives used in adhesive layers. As an acrylic adhesive, a suitable selection can be made from known acrylic adhesives. For example, the adhesive layer may contain a crosslinked adhesive composition containing an acrylic polymer as a main agent and a crosslinking agent.

[0089] The thickness of the adhesive layer is 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. In addition, if the thickness of the adhesive layer is too thick, the re-peelability may be reduced.

[0090] (c) Properties of the carrier substrate

[0091] The carrier substrate in this method is preferably transparent. When the carrier substrate is transparent, defects on the carrier substrate side of the surface-treated copper foil can be inspected by observing it from the carrier substrate side. Therefore, the yield can be improved.

[0092] When the carrier substrate is transparent, the total light transmittance of the carrier substrate is 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 according to JIS K7361-1:1997.

[0093] (d) Method for manufacturing copper foil with a carrier

[0094] When the copper foil with a carrier in this disclosure has the carrier substrate of this type, the manufacturing method of the copper foil with a carrier may include, for example, a placement step, in which copper foil is placed on the adhesive layer side of the carrier substrate; an etching step, in which the thickness of the copper foil is reduced by etching; and a surface portion forming step, in which a selenium-containing surface portion is formed on the side of the copper foil opposite to the carrier substrate. By reducing the thickness of the copper foil by etching, the thickness of the copper foil can be made suitable for forming fine wiring. Furthermore, Rz, Ra, and Rp in the side of the copper foil opposite to the carrier substrate can be set within a specific range.

[0095] In the fabrication process, an adhesive layer can be used to bond the carrier substrate to the copper foil. At this time, thick electrolytic copper foil or rolled copper foil can be used as the copper foil.

[0096] In the etching process, the etching method for copper foil can be the same as that used for general copper foil etching.

[0097] Furthermore, after the etching process, a roughening process based on etching can be performed on the copper foil. This allows the Rz, Ra, and Rp values ​​on the side of the copper foil opposite to the substrate to be within a specified range. In the roughening process, a general copper foil etching method can be used. For example, the surface properties can be controlled by adjusting the concentration or temperature of the etching solution.

[0098] The surface formation method in the surface formation process is as described above.

[0099] (2) Second method

[0100] In this method, the carrier substrate has a release layer and a carrier copper foil sequentially from the surface-treated copper foil side.

[0101] Figure 4 This is a schematic cross-sectional view illustrating a copper foil with a carrier in this disclosure. Figure 4The copper foil 10 with a carrier has: a carrier substrate 11 having a carrier copper foil 4 as a metal foil and a release layer 5 disposed on one side of the carrier copper foil 4; and the aforementioned surface-treated copper foil 1 disposed on the side of the release layer 5 of the carrier substrate 11. The surface-treated copper foil 1 is disposed such that the surface S1 of the copper foil 1a side is on the side of the release layer 5.

[0102] (a) Carrier copper foil

[0103] The carrier copper foil is a component that supports the release layer and the surface-treated copper foil. From the perspective of good operability, the thickness of the carrier copper foil is preferably 5 μm or more and 30 μm or less, more preferably 10 μm or more and 20 μm or less. Electrolytic copper foil or rolled copper foil can be used as the carrier copper foil.

[0104] The carrier copper foil can be made of copper as a single metal or an alloy of copper with other metals. Examples of other metals include tin, chromium, silver, magnesium, nickel, zirconium, silicon, and titanium.

[0105] (b) Peel layer

[0106] A release layer is a component designed to facilitate the separation of copper foil from a carrier copper foil or to impart weak adhesion. There are no particular limitations on the release layer; release layers commonly used for carrier copper foil can be applied. The release layer can be a single layer or multiple layers.

[0107] C. Copper-clad laminate

[0108] The copper-clad laminate disclosed herein has a resin layer and the aforementioned surface-treated copper foil disposed on one or both sides of the resin layer, wherein the surface-treated copper foil is disposed such that the surface portion side is on the resin layer side.

[0109] Figure 5 (a) and Figure 5 (b) is a schematic cross-sectional view illustrating a copper-clad laminate in this disclosure. Figure 5 The copper-clad laminate 30 shown in (a) has a resin layer 31 and a surface-treated copper foil 1 disposed on one side of the resin layer 31. Figure 5 The copper-clad laminate 30 shown in (b) has a resin layer 31 and surface-treated copper foil 1 disposed on both sides of the resin layer 31. The surface-treated copper foil 1 is disposed such that the surface S2 on the surface portion 1b side is on the resin layer 31 side.

[0110] The copper-clad laminate in this disclosure improves the adhesion between the surface-treated copper foil and the resin layer by having the aforementioned surface-treated copper foil.

[0111] The following describes the various components of the copper-clad laminate in this disclosure.

[0112] 1. Surface-treated copper foil

[0113] The surface-treated copper foil in this disclosure is identical to that detailed in "A. Surface-treated Copper Foil" above. The surface-treated copper foil may be disposed on one side or both sides of the resin layer. Preferably, the surface-treated copper foil is in contact with the resin layer.

[0114] In surface-treated copper foil, when measuring the area ratio of the surface portion relative to one side of the copper foil, the surface-treated copper foil is pre-peeled from the copper-clad laminate. As a peeling method for the surface-treated copper foil, the side of the surface-treated copper foil to be measured (the second side of the surface-treated copper foil) and the opposite side (the first side of the surface-treated copper foil) are held together with an adhesive or bonding agent that can sufficiently withstand the peeling of the surface-treated copper foil. A starting point is made at the interface between the surface-treated copper foil and the resin layer, and the surface-treated copper foil is stretched, thereby exposing the second side of the surface-treated copper foil.

[0115] 2. Resin layer

[0116] The resin layer comprises a resin component and a fiber substrate. As the resin layer, a laminate formed by stacking multiple prepregs can be used. A prepreg is a composite material formed by impregnating a fiber substrate with a resin component. Prepregs commonly used in copper-clad laminates can be used as the prepreg.

[0117] 3. Copper-clad laminate

[0118] The copper-clad laminate disclosed herein only needs to have a resin layer and the aforementioned surface-treated copper foil disposed on one or both sides of the resin layer. As the layer structure of the copper-clad laminate, a known layer structure can be used.

[0119] For copper-clad laminates, the appropriate selection can be made based on the layer structure of the copper-clad laminate. For example, the aforementioned carrier-bearing copper foil is overlapped on one or both sides of a laminate formed by overlapping multiple sheets of the aforementioned prepreg, and then heated and pressurized as needed. This transfers the surface-treated copper foil onto one or both sides of the resin layer of the prepreg laminate, thereby manufacturing a copper-clad laminate. The heating and pressurizing conditions can be appropriately set according to the thickness of the copper-clad laminate, the type of resin layer, etc.

[0120] D. Printed wiring substrate

[0121] The printed wiring substrate of this disclosure has 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 has a copper foil and a selenium-containing surface portion disposed on one side of the copper foil. 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%. The surface-treated copper foil is disposed such that the surface portion side is on the resin layer side.

[0122] Figure 6 (a) and Figure 6 (b) is a schematic cross-sectional view illustrating the printed wiring substrate in this disclosure. Figure 6 The printed wiring substrate 50 shown in (a) has a resin layer 51 and a patterned surface-treated copper foil 1 disposed on one side of the resin layer 51. Figure 6 The printed wiring substrate 50 shown in (b) has a resin layer 51 and a patterned surface-treated copper foil 1 disposed on both sides of the resin layer 51. The surface-treated copper foil 1 has a copper foil 1a and a selenium-containing surface portion 1b sequentially from the side opposite to the resin layer 51, 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%.

[0123] In the printed wiring substrate disclosed herein, as described in the above-mentioned item "A. Surface-treated copper foil", the surface-treated copper foil has a selenium-containing surface portion on the resin layer side, and the surface portion has a predetermined area ratio, thereby enabling good adhesion between the surface-treated copper foil and the resin layer.

[0124] The following describes the various components of the printed wiring substrate disclosed herein.

[0125] 1. Surface-treated copper foil

[0126] The surface-treated copper foil in this disclosure is patterned. Furthermore, the surface-treated copper foil has, sequentially, copper foil and a selenium-containing surface portion from the side opposite to the resin layer. Moreover, regarding the copper foil, the area ratio of the surface portion to one side of the copper foil is 30.0% or more and less than 100.0%.

[0127] Regarding surface-treated copper foil, the same content is described in "A. Surface-treated copper foil" above.

[0128] The surface-treated copper foil can be disposed on one side or both sides of the resin layer. Preferably, the surface-treated copper foil is in contact with the resin layer.

[0129] In surface-treated copper foil, the surface-treated copper foil is pre-peeled from the printed wiring substrate when measuring the area ratio of the surface portion relative to one side of the copper foil. The peeling method for the surface-treated copper foil is the same as the peeling method for the resin layer described in the above-mentioned "C. Copper-clad laminate".

[0130] 2. Resin layer

[0131] The resin layer is the same as the resin layer in the copper-clad laminate described above.

[0132] 3. Printed wiring substrate

[0133] The printed wiring substrate disclosed herein only needs to have a resin layer and a patterned surface-treated copper foil disposed on one or both sides of the resin layer. As the layer structure of the printed wiring substrate, a known layer structure can be used.

[0134] Printed wiring substrates can be categorized into single-sided or double-sided printed wiring substrates, multilayer printed wiring substrates, and flexible printed wiring substrates. Additionally, printed wiring substrates can also be multilayer wiring substrates.

[0135] The manufacturing method of printed wiring substrate is appropriately selected based on the layer structure of the printed wiring substrate.

[0136] For example, after transferring surface-treated copper foil onto one or both sides of a resin layer as a prepreg to produce a copper-clad laminate, the surface-treated copper foil is patterned to form a circuit, thereby enabling the manufacture of single-sided or double-sided printed wiring substrates.

[0137] Furthermore, by multiplying the aforementioned single-sided or double-sided printed wiring substrates, it is possible to manufacture multilayer printed wiring substrates.

[0138] Alternatively, for example, by using the aforementioned carrier copper foil, after transferring a surface-treated copper foil onto one side of a resin film, the surface-treated copper foil is patterned to form a circuit, thereby enabling the manufacture of a flexible printed wiring substrate.

[0139] Furthermore, there are no particular limitations on the manufacturing method of the multilayer wiring substrate, but the modified semi-additive process (MSAP) is preferred. The MSAP method is suitable for forming fine wiring.

[0140] Furthermore, this disclosure is not limited to the embodiments described above. The embodiments described above are illustrative examples, and any embodiments having a substantially the same structure as the technical concept described in the claims of this disclosure and performing the same effects are included within the technical scope of this disclosure.

[0141] Example

[0142] The following examples and comparative examples further illustrate this disclosure in detail.

[0143] [Example 1]

[0144] As the carrier substrate, an adhesive film consisting of a 12.5 μm thick polyimide film (Toray DuPont Kapton), a 6 μm thick acrylic adhesive layer, and a release film (Somar "SOMATACEXP12.5PI1-200 (6 μm)") was used. An 8 μm thick copper foil (Furukawa Electric Corporation "NC-WS") was then bonded to the adhesive layer of the carrier substrate. Next, the copper foil was etched using a ferric chloride-based etching solution until its thickness reached 3 μm. Then, the copper foil was roughened using a ferric chloride solution with a specific gravity of 14 Bh and a temperature of 35°C. After roughening, the copper foil underwent a black dyeing process via spraying. In this black dyeing process, a black dye prepared by diluting Tomi Chemical Co., Ltd.'s black dye "Blacky CN-20" with pure water to 5.0% by volume (i.e., diluted 20 times) was used. The black dye "Blacky CN-20" is a room-temperature black dye containing selenite, zinc sulfate, zinc chloride, zinc phosphate, and purified water. This is used to produce copper foil with a carrier.

[0145] [Example 2]

[0146] In the black dyeing process, a black dyeing agent prepared by diluting the black dyeing agent "Blacky CN-20" manufactured by Tomi Chemical Co., Ltd. with pure water to 10% by volume (i.e., diluted to 10 times) was used. Otherwise, a copper foil with a carrier was prepared in the same manner as in Example 1.

[0147] [Example 3]

[0148] In the black dyeing process, a black dyeing agent prepared by diluting the black dyeing agent "Blacky CN-20" manufactured by Tomi Chemical Co., Ltd. with pure water to 15% by volume (i.e., diluted to about 6.7 times) was used. Otherwise, a copper foil with a carrier was prepared in the same manner as in Example 1.

[0149] [Comparative Example 1]

[0150] In the black dyeing process, a black dyeing agent prepared by diluting the black dyeing agent "Blacky CN-20" manufactured by Tomi Chemical Co., Ltd. with pure water to 1% by volume (i.e., diluted to 100 times) was used. Otherwise, a copper foil with a carrier was prepared in the same manner as in Example 1.

[0151] [Comparative Example 2]

[0152] In the black dyeing process, a black dyeing agent prepared by diluting the black dyeing agent "Blacky CN-20" manufactured by Tomi Chemical Co., Ltd. with pure water to 2.5% by volume (i.e., diluted to about 40 times) was used. Otherwise, a copper foil with a carrier was prepared in the same manner as in Example 1.

[0153] [Comparative Example 3]

[0154] In the black dyeing process, a black dyeing agent prepared by diluting the black dyeing agent "Blacky CN-20" manufactured by Tomi Chemical Co., Ltd. with pure water to 17.5% by volume (i.e., diluted to about 5.7 times) was used. Otherwise, a copper foil with a carrier was prepared in the same manner as in Example 1.

[0155] [Comparative Example 4]

[0156] After the roughening treatment of the copper foil, a surface treatment using an inorganic treatment agent containing Zr was performed instead of the black dyeing treatment. Otherwise, the copper foil with a carrier was made in the same manner as in Example 1. Zr was used as the inorganic treatment agent, which was an inorganic treatment agent in which "New Dain Silver TN (Yamato Kasei Corporation)" was diluted with pure water to 5.0% by volume (i.e., diluted 20 times).

[0157] [Comparative Example 5]

[0158] After the roughening treatment of the copper foil, a surface treatment using a Ni-containing inorganic treatment agent was performed instead of the black dyeing treatment. Otherwise, the copper foil with a carrier was produced in the same manner as in Example 1. As the Ni-containing inorganic treatment agent, an inorganic treatment agent prepared by diluting "S-680 (manufactured by KANIGEN, Japan)" with pure water to 10% by volume (i.e., diluted 10 times) was used.

[0159] [Comparative Example 6]

[0160] After the roughening treatment of the copper foil, a surface treatment with an Ag-containing inorganic treatment agent was performed instead of the black dyeing treatment. Otherwise, the copper foil with the carrier was made in the same manner as in Example 1. As the Ag-containing inorganic treatment agent, an inorganic treatment agent prepared by diluting "VERZONE NP-1 (Yamato Kasei)" with pure water to 10% by volume (i.e., diluted 10 times) was used.

[0161] [Comparative Example 7]

[0162] After the roughening treatment of the copper foil, a surface treatment using a silane coupling agent was performed instead of a blackening treatment. Otherwise, the copper foil with a carrier was prepared in the same manner as in Example 1. As the silane coupling agent, a treatment agent prepared by diluting JX Metals' functional copper discoloration inhibitor "IS-1" (a silane coupling agent) to 5.0% by volume (i.e., diluted 20 times) with pure water was used.

[0163] [Example 4]

[0164] After preparing a copper foil with a carrier in the same manner as in Example 1, a solution of a functional copper discoloration inhibitor "IS-1" of silane coupling agent manufactured by JX Metals Co., Ltd., diluted with pure water to 5.0% by volume (i.e., diluted to 20 times), was used for further surface treatment.

[0165] [Example 5]

[0166] After preparing the copper foil with the carrier in the same manner as in Example 2, the surface was further treated with a solution prepared by diluting the functional copper discoloration inhibitor "IS-1" of silane coupling agent manufactured by JX Metals Co., Ltd. to 5.0% by volume (i.e., diluted to 20 times) with pure water.

[0167] [Example 6]

[0168] After preparing the copper foil with the carrier in the same manner as in Example 3, the surface was further treated with a solution prepared by diluting the functional copper discoloration inhibitor "IS-1" of silane coupling agent manufactured by JX Metals Co., Ltd. to 5.0% by volume (i.e., diluted to 20 times) with pure water.

[0169] [evaluate]

[0170] (1) Composition analysis

[0171] X-ray photoelectron spectroscopy (XPS) analysis was performed on the side of the copper foil with a carrier in the examples and comparative examples opposite to the carrier substrate, confirming the presence of selenium. XPS was performed using a Quantax Q400 (within the ULTRA55 of ZEISS Corporation) under the conditions of Al-Kα monochromatic radiation, output of 5 kV, and TOA of 45°, within a range of 200 μm Φ.

[0172] (2) Area ratio of the surface portion

[0173] For the carrier-supported copper foils of the embodiments and comparative examples, the surface of the surface-treated copper foil was photographed at 500,000x magnification using a scanning electron microscope (ZEISS "ULTRA55"). Image X was then obtained. Next, using ImageJ (National Institutes of Health) image analysis software, a cropped image Y was obtained by cropping a 0.781μm × 0.781μm (350 × 350 pixels) area to include a relatively flat region. Under the following conditions, the cropped image Y was binarized, taking the selenium-containing surface portion (white portion) and other portions (black portion, i.e., the copper foil surface portion), to obtain a binarized image Z.

[0174] The dimensions of the surface portion (selenium) attached to the copper foil surface are measured by enclosing the outer diameter of the surface portion with a line. The total area of ​​each measured surface portion is divided by the number of surface portions, and the result is taken as the average surface portion size. The average surface portion size is multiplied by the number of surface portions to obtain the total surface portion area. The percentage (%) of the surface portion area is calculated from (total surface portion area / cropped image Y area). This surface portion includes cases where selenium particles are present, and cases where selenium particles are compounded.

[0175] For the entire region of the binarized image, Count, Average Size, Total Area, and %Area were calculated using the following 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 proportion of the total area of ​​the particles relative to the entire region of the binarized image. %Area is used as the area proportion of the surface portion. This step was performed 5 times, and the arithmetic mean was used. The results are shown in Table 1. Additionally, images X, Y, and Z of Examples 1-3 and Comparative Examples 1-3 are shown in... Figure 7 and Figure 8 .

[0176] <Image parsing conditions>

[0177] Image analysis software: ImageJ

[0178] Brightness setting: No adjustment

[0179] Contrast: No adjustment

[0180] Threshold: 70-100 (255 gray levels)

[0181] Resolution area: 0.781μm × 0.781μm (350 × 350 pixels)

[0182] <Calculation Method>

[0183] Calculation method: Calculated using Analyze Particles

[0184] Calculation condition: Size (^2): 0 - Infinity

[0185] Circularity: 0.00-1.00

[0186] Include holes: This refers to the measurement of the outer diameter of the surface area enclosed by a wire.

[0187] (3) Rz

[0188] As a surface roughness measuring instrument, a small surface roughness measuring instrument (SURFCOM SJ-210 manufactured by Mitutoyo Corporation) was used to measure the Rz of the side opposite to the carrier substrate of the copper foil with carrier in the examples and comparative examples under the above measurement conditions.

[0189] (4)Tightness

[0190] The peel strength between the copper foil and the prepreg was measured as an indicator of the adhesion between the copper foil and the resin layer. The prepreg used was "GHPL-830 SQ73" manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0191] The copper foil with a carrier and the prepreg of the examples and comparative examples were overlapped and vacuum hot-pressed. Then, the carrier substrate was peeled off from the laminate of the copper foil with carrier and prepreg, thereby transferring the copper foil onto one side of the prepreg. Next, a photosensitive resin (dry film) was laminated, exposed and developed, and the copper foil was etched. Then, the photosensitive resin was peeled off to form a 1 cm wide pattern. Next, the copper foil was electroplated to a thickness of 12 μm. This yielded the test piece.

[0192] Peel tests were conducted using a force gauge (IMADA ZTS-50N), an electric measuring table (IMADA MX2-500N), and a 90-degree peel test fixture (IMADA P900-200N) at a peel speed of 300 mm / sec, a peel angle of 90°, and a peel length of 80 mm. Time-load curves were obtained using IMADA'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.

[0193] (5) Resistance to damp heat

[0194] For the carrier-supported copper foils of the examples and comparative examples, a damp heat resistance test was conducted for 100 hours at 130°C and 85%. For the carrier-supported copper foils after the damp heat resistance test, the peel strength between the copper foil and the prepreg was measured using the same method as described in (4) above for adhesion.

[0195] [Table 1]

[0196] According to Table 1, in Examples 1 to 6 where the area ratio of the selenium-containing surface portion was within a specified range, the peel strength between the copper foil and the prepreg increased. On the other hand, it was confirmed that the copper foils of Comparative Examples 1 to 3 with a small area ratio of the selenium-containing surface portion and Comparative Examples 4 to 7 without a selenium-containing surface portion had low peel strength between the copper foil and the prepreg.

[0197] In Examples 1-3, the peel strength between the copper foil and the prepreg remained above 3.0 N / cm even after the damp heat resistance test. On the other hand, in Examples 4-6, which were treated with silane coupling agent, the peel strength between the copper foil and the prepreg decreased after the damp heat resistance test.

[0198] This disclosure provides the following invention. [1]

[0200] A surface-treated copper foil, comprising: Copper foil; and A selenium-containing surface portion is disposed on one side of the copper foil. The area ratio of the surface portion relative to the one side of the copper foil is 30.0% or more and less than 100.0%. [2]

[0202] According to the surface-treated copper foil described in [1], the maximum height roughness Rz of the surface portion side is 0.6 μm or more and 1.2 μm or less. [3]

[0204] A copper foil with a carrier, which has the following characteristics: Carrier substrate; and The surface-treated copper foil described in [1] or [2] is disposed on one side of the carrier substrate. The surface-treated copper foil is arranged such that the copper foil side faces the carrier substrate side. [4]

[0206] According to the copper foil with a carrier described in [3], the carrier substrate has an adhesive layer and a resin substrate in sequence from the side of the surface-treated copper foil. [5]

[0208] According to the copper foil with a carrier described in [3], the carrier substrate has a release layer and a metal foil in sequence from the side of the surface-treated copper foil. [6]

[0210] A copper-clad laminate, comprising: Resin layer; and The surface-treated copper foil described in [1] or [2] is disposed on one or both sides of the resin layer. The surface-treated copper foil is arranged such that the surface side is on the resin layer side. [7]

[0212] A printed wiring substrate, comprising: Resin layer; and Patterned surface-treated copper foil, disposed on one or both sides of the resin layer. The surface-treated copper foil comprises: a copper foil; and a selenium-containing surface portion disposed on one side of the copper foil. The surface-treated copper foil is arranged such that the surface portion is on the resin layer side, and the area ratio of the surface portion to the area of ​​one side of the copper foil is 30.0% or more and less than 100.0%.

[0213] Label Explanation

[0214] 1…Surface-treated copper foil

[0215] 1a…copper foil

[0216] 1b…Surface part

[0217] 2…Resin substrate

[0218] 3…Adhesive layer

[0219] 4…Carrier copper foil

[0220] 5… Peel-off layer

[0221] 10, 20… Copper foil with carrier

[0222] 11…Carrier substrate

[0223] 21, 31, 41… resin layers

[0224] 30… Copper-clad laminate

[0225] 50…Printed Wiring Board

Claims

1. A surface-treated copper foil, comprising: Copper foil; and A selenium-containing surface portion is disposed on one side of the copper foil. The area ratio of the surface portion relative 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 claim 1, wherein, The maximum height roughness Rz of the surface side is 0.6 μm or more and 1.2 μm or less.

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

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

5. The copper foil with a carrier according to claim 3, wherein, The carrier substrate has a release layer and a metal foil sequentially from the copper foil side of the surface treatment.

6. A copper-clad laminate, comprising: Resin layer; and The surface-treated copper foil according to claim 1 or 2 is disposed on one or both sides of the resin layer. The surface-treated copper foil is arranged such that the surface side is on the resin layer side.

7. A printed wiring substrate, comprising: Resin layer; and Patterned surface-treated copper foil, disposed on one or both sides of the resin layer. The surface-treated copper foil comprises: a copper foil; and a selenium-containing surface portion disposed on one side of the copper foil. The surface-treated copper foil is arranged such that the surface portion is on the resin layer side, and the area ratio of the surface portion to the area of ​​one side of the copper foil is 30.0% or more and less than 100.0%.

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