TWI749827B - Surface treatment copper foil, copper clad laminate and printed wiring board - Google Patents

Abstract

The present invention is a surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one side of the copper foil. The surface-treated copper foil has a load area ratio SMr1 that separates the protruding peak portion and the center portion of the surface-treated layer from 16 to 28%.

Description

Surface treatment copper foil, copper clad laminate and printed wiring board

The invention relates to a surface-treated copper foil, a copper clad laminate and a printed wiring board.

Copper clad laminates are widely used in various applications such as flexible printed wiring boards. The flexible printed wiring board is manufactured by the following method: the copper foil of the copper clad laminate is etched to form a conductor pattern (also called "wiring pattern"), and the electronic parts are connected and mounted on the conductor pattern by solder.

In recent years, in electronic equipment such as computers and mobile terminals, with the increase in communication speed and capacity, and the high frequency of electrical signals, there is a need for a flexible printed wiring board that can cope with this trend. In particular, the higher the frequency of the electrical signal, the greater the loss (attenuation) of the signal power, and the more easily it becomes impossible to read data. Therefore, it is required to reduce the loss of signal power.

There are two main types of signal power loss (transmission loss) in electronic circuits. One is conductor loss, that is, the loss caused by copper foil, and the other is dielectric loss, that is, the loss caused by the resin substrate. The conductor loss has a skin effect in the high-frequency region, and the current has the characteristic of flowing through the surface of the conductor. Therefore, if the surface of the copper foil is rough, it means that the current will flow along a complicated path. Therefore, in order to reduce the conductor loss of high-frequency signals, it is ideal to reduce the surface roughness of the copper foil. Hereinafter, when only "transmission loss" and "conductor loss" are described in this manual, they mainly refer to "high-frequency signal transmission loss" and "high-frequency signal conductor loss".

On the other hand, since the dielectric loss depends on the type of resin base material, it is ideal to use low-dielectric constant materials (such as liquid crystal polymer, low-dielectric constant polyimide) in the circuit board for circulating high-frequency signals. The formed resin substrate. In addition, the dielectric loss is also affected by the adhesive that bonds the copper foil and the resin base material. Therefore, it is desirable to bond the copper foil and the resin base material without using an adhesive. In this regard, in order to bond between the copper foil and the resin substrate without using an adhesive, a method of forming a surface treatment layer on at least one surface of the copper foil has been proposed. For example, Patent Document 1 proposes a method of providing a roughening treatment layer formed of roughened particles on a copper foil, and forming a silane coupling treatment layer on the outermost layer. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2012-112009 A

[The problem to be solved by the invention]

Although the roughening treatment layer can improve the adhesion between the copper foil and the resin substrate by the anchoring effect of the roughening particles, the skin effect may increase the conductor loss. Therefore, it is ideal to reduce the electrodeposition on the copper Roughened particles on the foil surface. On the other hand, if the roughened particles electrodeposited on the surface of the copper foil are reduced, the anchoring effect of the roughened particles will be reduced, so that the adhesion between the copper foil and the resin substrate cannot be sufficiently obtained. In particular, compared with conventional resin substrates, resin substrates made of low-dielectric constant materials such as liquid crystal polymer and low-dielectric constant polyimide are difficult to bond with copper foil. Therefore, it is desired to develop improved copper foils. The method of adhesion to the resin substrate. In addition, although the silane coupling treatment layer has the effect of improving the adhesion between the copper foil and the resin substrate, the effect of improving the adhesion may be insufficient depending on the type.

The embodiment of the present invention was completed in order to solve the above-mentioned problems, and its purpose is to provide a surface-treated copper foil that can improve the adhesion to a resin substrate, especially a resin substrate suitable for high-frequency applications. In addition, an object of the embodiments of the present invention is to provide a copper-clad laminate having excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a surface-treated copper foil. Furthermore, an object of an embodiment of the present invention is to provide a printed wiring board whose resin substrate, particularly suitable for high-frequency applications, has excellent adhesion between the resin substrate and the circuit pattern. [Technical means to solve the problem]

In order to solve the above-mentioned problems, the inventors have conducted intensive research on surface-treated copper foil. As a result, they have found that among the various indicators of surface roughness of the surface-treated layer, the load area ratio SMr1, which separates the protrusion peak from the center part, is the protrusion area ratio SMr1. The peak height Spk and the level difference Sk at the center are closely related to the adhesion between the surface-treated copper foil and the resin substrate. Based on the above findings, by controlling SMr1, Spk or Sk within a specific range, the surface treatment can be improved The adhesiveness between the copper foil and the resin substrate completes the embodiment of the present invention.

That is, the embodiment of the present invention relates to a surface-treated copper foil having a copper foil and a surface-treated layer formed on at least one side of the copper foil, and the load area ratio of separating the protruding peak portion and the center portion of the surface-treated layer SMr1 is 16-28%. In addition, the embodiment of the present invention relates to a surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one side of the copper foil, and the protrusion peak height Spk of the surface-treated layer is 1.2-2.5 μm. In addition, the embodiment of the present invention relates to a surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one side of the copper foil, and the level difference Sk at the center of the surface-treated layer is 1.0 to 2.0 μm. In addition, an embodiment of the present invention relates to a copper-clad laminated board provided with the above-mentioned surface-treated copper foil and a resin substrate bonded to the surface-treated layer of the above-mentioned surface-treated copper foil. Furthermore, the embodiment of this invention relates to a printed wiring board provided with the circuit pattern formed by etching the said surface-treated copper foil of the said copper clad laminated board. [Effects of the invention]

According to the embodiment of the present invention, a surface-treated copper foil can be provided, which can improve the adhesion to a resin substrate, especially a resin substrate suitable for high-frequency applications. Furthermore, according to the embodiment of the present invention, it is possible to provide a copper-clad laminate having excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a surface-treated copper foil. Furthermore, according to the embodiment of the present invention, it is possible to provide a printed wiring board whose resin substrate, particularly suitable for high-frequency applications, has excellent adhesion between the resin substrate and the circuit pattern.

Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not to be interpreted in such a limited manner, and various changes and improvements can be made based on the knowledge of the industry without departing from the scope of the present invention. A plurality of constituent elements disclosed in the following embodiments can be appropriately combined to form various inventions. For example, several constituent elements may be deleted from all the constituent elements shown in the following embodiments, or constituent elements of different embodiments may be appropriately combined.

(Embodiment 1) The first embodiment of the present invention relates to a surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one side of the copper foil, and the load area ratio SMr1 that separates the protruding peak portion and the center portion of the surface-treated layer is 16 ~28%. In addition, the first embodiment of the present invention relates to a copper-clad laminate including the above-mentioned surface-treated copper foil and a resin substrate bonded to the surface-treated layer of the above-mentioned surface-treated copper foil. Furthermore, Embodiment 1 of this invention relates to a printed wiring board provided with the circuit pattern formed by etching the surface-treated copper foil of the said copper clad laminated board.

The surface treatment layer of the surface-treated copper foil of the first embodiment of the present invention may be formed on only one side of the copper foil, or may be formed on both sides of the copper foil. In addition, when the surface treatment layer is formed on both sides of the copper foil, the type of the surface treatment layer may be the same or different.

The load area ratio SMr1 that separates the protruding peak portion from the center portion represents the ratio of the protruding peak portion located above the center portion. The greater the ratio of the protruding peak portion, the greater the value of SMr1. SMr1 is measured in accordance with ISO 25178. When the surface treatment layer of the surface treatment copper foil is attached to the resin substrate, if the ratio of the protruding peaks of the surface treatment layer is small, the force when peeling the resin substrate from the surface treatment layer (hereinafter referred to as "peeling force") ) Concentrated on the surface of the center. In this regard, by setting the SMr1 of the surface treatment layer to 16% or more (increasing the ratio of the protruding peaks), the peeling force can be easily dispersed in the height direction of the protruding peaks due to the existence of the protruding peaks. As a result, the adhesion between the surface-treated copper foil and the resin substrate becomes higher. On the other hand, by setting the SMr1 of the surface treatment layer to 28% or less, the increase in transmission loss caused by the skin effect can be suppressed.

The height Spk of the protruding peak of the surface treatment layer is preferably 1.2~2.5 μm. Here, the protrusion height Spk is measured in accordance with ISO 25178. When the surface treatment layer of the surface treatment copper foil is connected to the resin substrate, if the protruding peak of the surface treatment layer is low, the peeling force will be concentrated on the surface of the center part. In this regard, by setting the Spk of the surface treatment layer to 1.2 μm or more (to increase the height of the protruding peak), the peeling force can be easily dispersed in the height direction of the protruding peak due to the existence of the protruding peak. As a result, the adhesion between the surface-treated copper foil and the resin substrate becomes higher. On the other hand, by setting the Spk of the surface treatment layer to 2.5 μm or less, the increase in transmission loss caused by the skin effect can be suppressed.

In the surface treatment layer, the level difference Sk at the center of the surface treatment layer is preferably 1.0 to 2.0 μm. Here, the level difference Sk of the center part of the surface treatment layer represents the degree of the height difference of the part (central part) excluding the protrusion peak part and the protrusion valley part, and is measured in accordance with ISO 25178. When the surface treatment layer of the surface-treated copper foil is connected to the resin substrate, if the height difference of the center part is small, the center part becomes approximately flat, and the peeling force is concentrated on the upper surface. In this regard, by setting the Sk of the surface treatment layer to 1.0 μm or more (increasing the height difference of the center part), the upper surface of the center part is made convex and concave, so that the peeling force can be easily dispersed in the height direction of the center part. . As a result, the adhesion between the surface-treated copper foil and the resin substrate becomes higher. On the other hand, by setting the Sk of the surface treatment layer to 2.0 μm or less, the increase in transmission loss caused by the skin effect can be suppressed.

The type of surface treatment layer is not particularly limited, and various surface treatment layers known in the technical field can be used. As an example of a surface treatment layer, a roughening treatment layer, a heat-resistant treatment layer, a rust-preventing treatment layer, a chromate treatment layer, a silane coupling treatment layer, etc. are mentioned. These layers can be used alone or in combination of two or more kinds. Among them, from the viewpoint of adhesion to the resin substrate, the surface treatment layer preferably has a roughening treatment layer. In addition, when the surface treatment layer has one or more layers selected from the group consisting of a heat-resistant treatment layer, an anti-rust treatment layer, a chromate treatment layer, and a silane coupling treatment layer, the layers are preferably provided on Coarse the treatment layer.

Here, as an example, a cross-sectional schematic diagram of a surface-treated copper foil having a roughening treatment layer on one surface of the copper foil is shown in FIG. 1. As shown in FIG. 1, the roughening treatment layer formed on one surface of the copper foil 10 includes: primary roughening particles 20, a covering plating layer 30 covering the primary roughening particles 20, and two of them formed on the covering plating layer 30 Sub-roughened particles 40. Preferably, the primary roughening particles 20 covered by the covering plating layer 30 are substantially spherical, and the secondary roughening particles 40 are formed in a dendritic manner. With such a structure, it is easy to control SMr1, Spk, and Sk of the surface treatment layer within the above-mentioned range.

The primary roughening particles 20 are not particularly limited, and may be formed of an element selected from the group consisting of copper, nickel, cobalt, phosphorus, tungsten, arsenic, molybdenum, chromium, and zinc, or an alloy containing two or more elements. Among them, the primary roughening particles 20 are preferably formed of copper or copper alloy, and particularly preferably formed of copper. The covering plating layer 30 is not particularly limited, and may be formed of copper, silver, gold, nickel, cobalt, zinc, or the like. The secondary roughening particles 40 are not particularly limited, and may be formed of a metal selected from the group consisting of nickel, cobalt, copper, and zinc, or an alloy containing two or more metals. Among them, the secondary roughening particles 40 are preferably formed of a copper alloy, and particularly preferably formed of a Cu-Co-Ni alloy.

The roughening treatment layer can be formed by electroplating. The conditions are not particularly limited and can be adjusted according to the electroplating equipment used. Typical conditions are shown below. (Formation condition R1 of primary coarsening particles 20) Composition of plating solution: 5~15 g/L Cu, 40~100 g/L sulfuric acid plating solution temperature: 20~50℃ Electroplating conditions: current density 30~60 A/dm ² , Coulomb amount 40~100 As/dm ²

(Formation condition R2 of covering plating layer 30) Composition of plating solution: 10~30 g/L Cu, 70~130 g/L sulfuric acid plating solution temperature: 30~60℃ Electroplating conditions: current density 4.8~15 A/dm ² , Coulomb amount 10~35 As/dm ²

(Condition Y for the formation of secondary coarsening particles 40) Composition of plating solution: 10-20 g/L Cu, 5-15 g/L Co, 5-15 g/L Ni pH: 2～3 Plating Liquid temperature: 30~40℃ Electroplating conditions: current density 15~45 A/dm ² , coulomb amount 15~55 As/dm ²

In the formation condition R1 of the primary roughened particles 20, the smaller the Coulomb amount, the more the primary roughened particles 20 will be inhibited from growing in the Z direction (the direction perpendicular to the copper foil 10). In addition, in the formation condition R2 of the covering plating layer 30, the larger the Coulomb amount, the more uniformly and thicker the layer grows in the XYZ direction. Therefore, by controlling the coulomb amount (R1)/coulomb amount (R2) below 6.0, preferably below 4.0, the shape of the primary coarsening particles 20 covered by the coating layer 30 can be controlled to be approximately spherical ~Roughly hemispherical shape. In addition, the primary roughened particles 20 covered by the coating layer 30 are controlled to have a roughly spherical to roughly hemispherical shape, and then the secondary roughened particles 40 are formed, thereby making it easy to form the secondary roughened particles 40 into The way of dendritic expansion is formed on the covering plating layer 30. Furthermore, if the Coulomb amount (R1)/Coulomb amount (R2) exceeds 6.0, the growth of the primary roughened particles 20 in the Z direction becomes larger, so the shape of the primary roughened particles 20 covered by the coating layer 30 becomes Roughly ellipsoidal ~ roughly semi-ellipsoidal shape. Therefore, it becomes difficult for the secondary roughening particles 40 formed on the covering plating layer 30 to spread in a dendritic shape.

The heat-resistant treatment layer and the anti-rust treatment layer are not particularly limited, and they can be formed of materials known in the technical field. Furthermore, the heat-resistant treatment layer sometimes also functions as an anti-rust treatment layer, so it is also possible to form a layer having both functions of the heat-resistant treatment layer and the anti-rust treatment layer as the heat-resistant treatment layer and the anti-rust treatment layer. As the heat-resistant treatment layer and/or the anti-rust treatment layer, it may contain elements selected from the group consisting of nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, and platinum group elements A layer of more than one element (metal, alloy, oxide, nitride, sulfide, etc.) from the group consisting of, iron, and tantalum. Among them, it is preferable that the heat-resistant treatment layer and/or the anti-rust treatment layer is a Ni-Zn layer or a Zn layer. In particular, if it is a Ni-Zn layer with a Ni content less than a Zn content, or a Zn layer without Ni, the conductor loss can be reduced without greatly reducing the heat-resistance effect and the rust-preventing effect, so it is preferable.

The heat-resistant treatment layer and the anti-rust treatment layer can be formed by electroplating. The conditions are not particularly limited, and can be adjusted according to the electroplating device used. The conditions for forming the heat-resistant layer (Ni-Zn layer) using a common electroplating device are as follows. Plating bath composition: 1~30 g/L Ni, 1~30 g/L Zn Plating bath pH: 2~5 Plating bath temperature: 30~50℃ Electroplating conditions: current density 1~10 A/dm ^2. Time 0.1~5 seconds

The chromate treatment layer is not particularly limited, and can be formed of materials known in the technical field. Here, the "chromate treatment layer" in this specification refers to a layer formed of a liquid containing chromic anhydride, chromic acid, dichromic acid, chromate, or dichromate. The chromate treatment layer may contain elements such as cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, titanium, etc. (may be metals, alloys, oxides, nitrides, sulfides) And so on any form) layer. Examples of the chromate treatment layer include: chromate treatment layer treated with chromic anhydride or potassium dichromate aqueous solution, chromate treatment layer treated with a treatment solution containing chromic anhydride or potassium dichromate and zinc Wait.

The chromate treatment layer can be formed by a known method such as immersion chromate treatment and electrolytic chromate treatment. These conditions are not particularly limited. For example, the conditions for forming a normal immersion chromate treatment layer are as follows. Chromate solution composition: 1~10 g/L K ₂ Cr ₂ O ₇ , 0.01~10 g/L Zn Chromate solution pH: 2~5 Chromate solution temperature: 30~55℃

系矽烷偶合劑等。其中，較佳為胺基系矽烷偶合劑、環氧系矽烷偶合劑。上述矽烷偶合劑可單獨使用或將2種以上組合使用。 作為代表性之矽烷偶合處理層之形成方法，可列舉藉由塗佈N-2-(胺基乙基)-3-胺基丙基三甲氧基矽烷（信越化學工業股份有限公司製造之KBM603）之1.2體積%水溶液（pH：10）並使其乾燥而形成矽烷偶合處理層之方法。The silane coupling treatment layer is not particularly limited, and can be formed of materials known in the art. Here, the "silane coupling treatment layer" in this specification refers to a layer formed of a silane coupling agent. The silane coupling agent is not particularly limited, and silane coupling agents known in the art can be used. Examples of silane coupling agents include: amino-based silane coupling agents, epoxy-based silane coupling agents, mercapto-based silane coupling agents, methacryloxy-based silane coupling agents, vinyl-based silane coupling agents, and imidazole-based silane coupling agents. Silane coupling agent, three

Department of silane coupling agent and so on. Among them, amine-based silane coupling agents and epoxy-based silane coupling agents are preferred. The above-mentioned silane coupling agent can be used alone or in combination of two or more kinds. As a representative method for forming the silane coupling treatment layer, it can be exemplified by coating N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (KBM603 manufactured by Shin-Etsu Chemical Co., Ltd.) The 1.2 volume% aqueous solution (pH: 10) and drying to form a silane coupling treatment layer.

It does not specifically limit as a copper foil, It may be either electrolytic copper foil or rolled copper foil. Electrolytic copper foil is usually produced by electrolysis of copper from a copper sulfate plating bath on a titanium drum or stainless steel drum, and has a flat S surface (polished surface) formed on the drum side and formed on the side opposite to the S surface The M surface (frosted surface). Normally, the M surface of the electrolytic copper foil has unevenness, so a surface treatment layer is formed on the M surface of the electrolytic copper foil to bond the surface treatment layer to the resin substrate, thereby improving the adhesion between the surface treatment layer and the resin substrate sex.

The material of copper foil is not particularly limited. When the copper foil is rolled copper foil, refined copper (JIS H3100 alloy number C1100) and oxygen-free copper (JIS High-purity copper such as H3100 alloy number C1020 or JIS H3510 alloy number C1011). In addition, for example, copper alloys such as copper containing Sn, copper containing Ag, copper alloys containing Cr, Zr, or Mg, and Carson-based copper alloys containing Ni, Si, and the like can also be used. Furthermore, "copper foil" in this specification also includes the concept of copper alloy foil.

The thickness of the copper foil is not particularly limited. For example, it can be set to 1~1000 μm, or 1 to 500 μm, or 1 to 300 μm, or 3 to 100 μm, or 5 to 70 μm, or 6 to 35 μm, or 9 ~18 μm.

The surface-treated copper foil having the above-mentioned structure can be manufactured according to a method known in the art. Here, the SMr1, Spk, and Sk of the surface treatment layer can be controlled by adjusting the formation conditions of the surface treatment layer, especially the formation conditions of the roughening treatment layer.

The surface-treated copper foil of the first embodiment of the present invention controls the load area ratio SMr1, which separates the protruding peak portion from the center portion of the surface-treated layer, to 16-28%, so the surface-treated layer of the surface-treated copper foil is connected to the resin substrate In this case, due to the existence of the protruding peak, the peeling force can be easily dispersed in the height direction of the protruding peak. Therefore, the surface-treated copper foil can improve adhesion to resin substrates, especially resin substrates suitable for high-frequency applications.

The copper-clad laminated board of the first embodiment of the present invention can be manufactured by bonding the surface treatment layer of the above-mentioned surface-treated copper foil to a resin substrate. The resin substrate is not particularly limited, and resin substrates known in this technical field can be used. Examples of resin substrates include: paper-based phenol resin, paper-based epoxy resin, synthetic fiber cloth-based epoxy resin, glass cloth-paper composite substrate epoxy resin, glass cloth-glass nonwoven composite Base material epoxy resin, glass cloth base material epoxy resin, polyester film, polyimide film, liquid crystal polymer, fluororesin, etc.

The bonding method of the surface-treated copper foil and the resin substrate is not particularly limited, and it can be performed according to a method known in the technical field. For example, what is necessary is just to laminate a surface-treated copper foil and a resin base material, and to perform thermocompression bonding. The copper clad laminated board manufactured as shown above can be used to manufacture printed wiring boards.

The copper-clad laminated board of the first embodiment of the present invention uses the above-mentioned surface-treated copper foil, and therefore can improve the adhesiveness with a resin substrate, especially a resin substrate suitable for high-frequency applications.

The printed wiring board of Embodiment 1 of the present invention can be manufactured by etching the surface-treated copper foil of the above-mentioned copper-clad laminated board to form a circuit pattern. The method of forming the circuit pattern is not particularly limited, and known methods such as a subtractive method and a semi-additive method can be used. Among them, the method of forming the circuit pattern is preferably a subtractive method.

In the case of manufacturing a printed wiring board by a subtractive method, it is preferably performed as follows. First, a resist is applied to the surface of the surface-treated copper foil of the copper-clad laminate, and exposed and developed to form a specific resist pattern. Secondly, the surface-treated copper foil of the portion where the resist pattern is not formed (unnecessary portion) is removed by etching to form a circuit pattern. Finally, remove the resist pattern on the surface-treated copper foil. Furthermore, the various conditions in the subtractive method are not particularly limited, and can be performed according to conditions known in the technical field.

The printed wiring board according to the first embodiment of the present invention uses the above-mentioned copper-clad laminate, so the resin substrate, especially suitable for high-frequency applications, has excellent adhesion between the resin substrate and the circuit pattern.

(Embodiment 2) The second embodiment of the present invention relates to a surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one surface of the copper foil, and the protrusion peak height Spk of the surface-treated layer is 1.2~2.5 μm. In addition, the second embodiment of the present invention relates to a copper-clad laminate including the above-mentioned surface-treated copper foil and a resin substrate bonded to the surface-treated layer of the above-mentioned surface-treated copper foil. Furthermore, Embodiment 2 of this invention relates to a printed wiring board provided with the circuit pattern formed by etching the surface-treated copper foil of the said copper clad laminated board. Furthermore, in the description of the second embodiment of the present invention, the description of the same features as those of the first embodiment of the present invention will be omitted.

In the surface-treated copper foil of the second embodiment of the present invention, by setting the Spk of the surface-treated layer to 1.2 μm or more, the peeling force can be easily dispersed in the height direction of the protruding peak due to the existence of the protruding peak. The adhesion between the surface-treated copper foil and the resin substrate becomes higher. On the other hand, by setting the Spk of the surface treatment layer to 2.5 μm or less, the increase in transmission loss caused by the skin effect can be suppressed.

In the surface treatment layer, the level difference Sk at the center of the surface treatment layer is preferably 1.0 to 2.0 μm. By setting the Sk of the surface treatment layer to 1.0 μm or more, the upper surface of the center part is made convex and concave, and the peeling force can be easily dispersed in the height direction of the center part. Therefore, the adhesion of the surface treatment copper foil to the resin substrate Becomes high. On the other hand, by setting the Sk of the surface treatment layer to 2.0 μm, the increase in transmission loss caused by the skin effect can be suppressed.

The surface-treated copper foil of Embodiment 2 of the present invention can be manufactured according to a method known in the art. Here, the Spk and Sk of the surface treatment layer can be controlled by adjusting the formation conditions of the surface treatment layer, especially the formation conditions of the above-mentioned roughening treatment layer.

In the surface-treated copper foil of the second embodiment of the present invention, the protrusion peak height Spk of the surface treatment layer is controlled to 1.2~2.5 μm, so the peeling force can be easily dispersed in the height direction of the protrusion peak due to the existence of the protrusion peak. Therefore, the surface-treated copper foil can improve adhesion to resin substrates, especially resin substrates suitable for high-frequency applications.

The copper-clad laminated board of the second embodiment of the present invention can be manufactured by bonding the surface treatment layer of the above-mentioned surface-treated copper foil to a resin substrate. The copper-clad laminated board of the second embodiment of the present invention uses the above-mentioned surface-treated copper foil, and therefore can improve the adhesion with the resin substrate, especially the resin substrate suitable for high-frequency applications.

The printed wiring board of the second embodiment of the present invention can be manufactured by etching the surface-treated copper foil of the above-mentioned copper clad laminate to form a circuit pattern. The printed wiring board of the second embodiment of the present invention uses the above-mentioned copper-clad laminate, and therefore has excellent adhesion between the resin base material, especially the resin base material suitable for high-frequency applications, and the circuit pattern.

(Embodiment 3) The third embodiment of the present invention relates to a surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one side of the copper foil, and the level difference Sk at the center of the surface-treated layer is 1.0 to 2.0 μm. In addition, the third embodiment of the present invention relates to a copper-clad laminate including the above-mentioned surface-treated copper foil and a resin substrate bonded to the surface-treated layer of the above-mentioned surface-treated copper foil. Furthermore, Embodiment 3 of this invention relates to a printed wiring board provided with the circuit pattern formed by etching the surface-treated copper foil of the said copper clad laminated board. In addition, in the description of the third embodiment of the present invention, the same features as those of the first embodiment of the present invention are omitted.

In the surface-treated copper foil of the third embodiment of the present invention, by setting the Sk of the surface-treated layer to 1.0 μm or more, the upper surface of the center part is made convex and concave, and the peeling force can be easily directed toward the height direction of the center part. Disperse, so the adhesion between the surface-treated copper foil and the resin substrate becomes higher. On the other hand, by setting the Sk of the surface treatment layer to 2.0 μm or less, the increase in transmission loss caused by the skin effect can be suppressed.

The surface-treated copper foil of Embodiment 3 of the present invention can be manufactured according to a method known in the art. Here, the Sk of the surface treatment layer can be controlled by adjusting the formation conditions of the surface treatment layer, especially the formation conditions of the above-mentioned roughening treatment layer.

The surface treatment copper foil of the third embodiment of the present invention controls the level difference Sk of the center part of the surface treatment layer to 1.0~2.0 μm, so the upper surface of the center part is made convex and concave, and the peeling force can be easily directed toward the center part. Dispersion in height direction. Therefore, the surface-treated copper foil can improve adhesion to resin substrates, especially resin substrates suitable for high-frequency applications.

The copper-clad laminated board of the third embodiment of the present invention can be manufactured by bonding the surface treatment layer of the above-mentioned surface-treated copper foil to a resin substrate. The copper clad laminated board of the third embodiment of the present invention uses the above-mentioned surface-treated copper foil, and therefore can improve the adhesion to the resin substrate, especially the resin substrate suitable for high-frequency applications.

The printed wiring board of Embodiment 3 of the present invention can be manufactured by etching the surface-treated copper foil of the above-mentioned copper-clad laminated board to form a circuit pattern. The printed wiring board of the third embodiment of the present invention uses the above-mentioned copper-clad laminate, and therefore has excellent adhesion between the resin base material, especially the resin base material suitable for high-frequency applications, and the circuit pattern. [Example]

Hereinafter, the embodiments of the present invention will be described in further detail with examples, but the present invention is not limited in any way by these examples.

(Example 1) Prepare rolled copper foil A (Young's modulus after recrystallization is 120 GPa, thickness is 12 μm), one side is degreased and pickled, and a roughening treatment layer is formed as the surface treatment layer. Thereby, a surface-treated copper foil is obtained. The formation conditions of the roughened layer are as follows. ＜Formation condition R1 of primary coarsening particles＞ Plating bath composition: 11 g/L Cu, 50 g/L sulfuric acid Plating bath temperature: 25℃ Plating conditions: current density 35.6 A/dm ² , coulomb amount 72.7 As /dm ²

(Formation condition R2 of covering coating layer) Composition of plating solution: 20 g/L Cu, 100 g/L sulfuric acid plating temperature: 50℃ Electroplating conditions: current density 9.9 A/dm ² , coulomb amount 30.3 As /dm ²

(Formation condition Y of secondary coarsening particles 40) Composition of plating solution: 15.5 g/L Cu, 7.5 g/L Co, 9.5 g/L Ni pH: 2.4 Plating bath temperature: 36℃ Plating conditions: Current density 33.1 A/dm ² , Coulomb amount 44.8 As/dm ²

(Examples 2-14, and Comparative Example 1) Except changing at least one of the type of rolled copper foil, the current density of R1, R2, and Y, and the amount of coulomb as shown in Table 1, it carried out similarly to Example 1, and obtained the surface-treated copper foil. Furthermore, in Table 1, rolled copper foil B is a rolled copper foil with a Young's modulus of 85 GPa after recrystallization and a thickness of 12 μm.

[Table 1] Types of rolled copper foil Current density (A/dm ² ) Coulomb amount (As/dm ² ) R1 R2 Y R1 R2 Y R1/R2 Example 1 A 35.6 9.9 33.1 72.7 30.3 44.8 2.4 Example 2 A 35.6 9.9 36.0 72.7 30.3 47.1 2.4 Example 3 A 35.6 9.9 37.8 72.7 30.3 49.4 2.4 Example 4 A 31.1 9.9 31.0 47.5 22.7 30.5 2.1 Example 5 A 39.3 4.9 30.9 80.3 15.2 40.4 5.3 Example 6 A 59.9 9.9 41.2 91.6 22.7 40.4 4.0 Example 7 A 51.6 9.9 41.2 78.9 22.7 40.4 3.5 Example 8 A 34.2 9.9 31.0 69.5 22.7 40.4 3.1 Example 9 A 34.2 9.9 29.3 69.5 22.7 36.9 3.1 Example 10 A 31.1 13.2 31.4 63.2 30.3 40.4 2.1 Example 11 B 41.9 6.6 31.0 85.3 15.2 40.4 5.6 Example 12 B 45.0 9.9 25.1 91.6 22.7 32.8 4.0 Example 13 B 45.0 9.9 19.3 91.6 22.7 18.0 4.0 Example 14 B 51.6 9.9 41.2 78.9 22.7 40.4 3.5 Comparative example 1 B 45.3 4.7 30.1 61.5 7.2 26.9 8.6

For the surface-treated copper foil obtained in the above-mentioned examples and comparative examples, the surface state of the surface-treated layer was observed using a scanning electron microscope (SEM). As a result, many roughened particles (especially secondary roughened particles) were confirmed to have a dendritic structure in Examples 1-14. In contrast, in Comparative Example 1, this structure was hardly confirmed. As a representative example, SEM photographs (20,000 times, 40° inclination) of the surface treatment layer (roughening treatment layer) of the surface treatment copper foil of Example 1 and Comparative Example 1 are shown in FIG. 2.

Next, the following property evaluations were performed on the surface-treated copper foils obtained in the above-mentioned Examples and Comparative Examples. ＜SMr1, Spk, Sk of surface treatment layer＞ A laser microscope (LEXT OLS4000) manufactured by Olympus Co., Ltd. was used for image photography. Use the analysis software of the laser microscope (LEXT OLS4100) manufactured by Olympus Co., Ltd. to analyze the captured images. The measurement of SMr1, Spk and Sk is carried out in accordance with ISO 25178, respectively. In addition, the measurement result is the average of the values measured at any three places as the measurement result. Furthermore, the temperature at the time of measurement is set to 23-25°C. In addition, the main setting conditions of the laser microscope and analysis software are as follows. Objective: MPLAPON50XLEXT (magnification: 50 times, numerical aperture: 0.95, liquid immersion type: air, mechanical lens barrel length: ∞, cover glass thickness: 0, number of fields of view: FN18) Optical zoom magnification: 1 times Scanning mode: XYZ high precision (height resolution: 10 nm, number of pixels for reading data: 1024×1024) Read image size [number of pixels]: 257 μm horizontal × 258 μm vertical [1024×1024] (Measured in the horizontal direction, so it is equivalent to an evaluation length of 257 μm) DIC: Off Multi-layer: Off Laser intensity: 100 Offset: 0 Confocal level: 0 Beam path diaphragm: off Image average: 1 time Noise reduction: On Uneven brightness correction: On Optical noise filter: On Cut-off: None (none of λc, λs, λf) Filter: Gaussian filter Noise removal: processing before measurement Surface (slope) correction: implementation

＜Peel strength＞ Make surface treatment of copper foil and resin substrate [LCP: Liquid crystal polymer resin (copolymer of hydroxybenzoic acid (ester) and hydroxynaphthoic acid (ester)) film (Vecstar (registered trademark) CTQ manufactured by Kuraray Co., Ltd.; The thickness is 50 μm or 100 μm)] After bonding, a circuit with a width of 3 mm is formed in the TD direction (the width direction of the rolled copper foil). Then, in accordance with JIS C6471: 1995, the strength (TD180° peel strength) when the circuit (surface-treated copper foil) is peeled off the surface of the resin substrate at a speed of 50 mm/min in the TD180° direction is measured. The measurement was performed 3 times, and the average value was used as the result of the peel strength. If the peel strength is 0.50 kgf/cm or more, it can be said that the adhesion between the circuit (surface-treated copper foil) and the resin substrate is good. Furthermore, the circuit width is adjusted by the usual subtractive etching method using copper chloride etching solution.

The results of the above-mentioned characteristic evaluation are shown in Table 2.

[Table 2] SMr1 (%) Spk (μm) Sk (μm) Peel strength (kgf/cm) Thickness of resin substrate (μm) Example 1 22.1 2.14 1.12 0.85 100 Example 2 24.8 2.09 1.69 0.82 100 Example 3 26.4 2.32 1.35 0.84 100 Example 4 20.8 1.73 1.13 0.84 100 Example 5 23.0 1.56 0.30 0.69 100 Example 6 23.9 2.08 1.57 0.73 50 Example 7 22.9 1.91 1.56 0.74 50 Example 8 21.1 1.69 1.29 0.79 50 Example 9 19.4 1.54 1.15 0.63 50 Example 10 19.8 1.52 0.30 0.78 50 Example 11 22.7 1.81 1.78 0.61 50 Example 12 15.2 1.27 1.27 0.55 50 Example 13 16.3 1.28 1.50 0.58 50 Example 14 21.8 1.77 1.50 0.73 50 Comparative example 1 15.1 0.9 0.93 0.47 50

As shown in Table 1, the surface-treated copper foils of Examples 1 to 14 in which the SMr1, Spk, and/or Sk of the surface treatment layer are within a specific range have higher peel strength. On the other hand, the surface-treated copper foil of Comparative Example 1 in which SMr1, Spk, and Sk of the surface-treated layer were outside the specified range had a low peel strength.

From the above results, it can be seen that according to the embodiments of the present invention, it is possible to provide a surface-treated copper foil capable of improving the adhesion to a resin substrate, especially a resin substrate suitable for high-frequency applications. Furthermore, according to the embodiment of the present invention, it is possible to provide a copper-clad laminate having excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a surface-treated copper foil. Furthermore, according to the embodiment of the present invention, it is possible to provide a printed wiring board having excellent adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a circuit pattern.

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[Figure 1] is a schematic cross-sectional view of a surface-treated copper foil with a roughening treatment layer on one side of the copper foil. [Figure 2] is an SEM photograph of the surface treatment layer of the surface treatment copper foil of Example 1 and Comparative Example 1.

Claims (11)

A surface-treated copper foil, which has a copper foil and a surface treatment layer formed on at least one surface of the above-mentioned copper foil, and the load area ratio SMr1 that separates the protruding peak part and the center part of the above-mentioned surface treatment layer is 16-28%, and the above-mentioned surface The height Spk of the protruding peak of the treatment layer is 1.2~2.5μm. Such as the surface treatment copper foil of claim 1, wherein the level difference Sk of the center part of the surface treatment layer is 1.0~2.0μm. A surface-treated copper foil, which has a copper foil and a surface treatment layer formed on at least one side of the copper foil, and the protrusion peak height Spk of the surface treatment layer is 1.2-2.5 μm. Such as the surface treatment copper foil of claim 3, wherein the level difference Sk of the center part of the surface treatment layer is 1.0~2.0μm. A surface-treated copper foil, which has a copper foil and a surface treatment layer formed on at least one side of the above-mentioned copper foil, the level difference Sk of the center part of the above-mentioned surface treatment layer is 1.0~2.0μm, and the protruding peak part of the above-mentioned surface treatment layer The load area ratio SMr1 separated from the center is 16~28%. The surface-treated copper foil according to any one of claims 1 to 5, wherein the surface-treated layer has a roughening treatment layer. The surface-treated copper foil of claim 6, wherein the roughening treatment layer includes: primary roughening particles, a covering plating layer covering the primary roughening particles, and a secondary roughening formed on the covering plating layer particle. The surface treatment copper foil of claim 6, wherein the surface treatment layer further has a heat-resistant treatment layer, an anti-rust treatment layer, a chromate treatment layer, and a silane coupling treatment layer on the roughening treatment layer One or more of the layers. The surface-treated copper foil according to any one of claims 1 to 5, wherein the above-mentioned copper foil is a rolled copper foil. A copper-clad laminated board is provided with the surface-treated copper foil of any one of claims 1 to 9 and a resin substrate bonded to the surface-treated layer of the above-mentioned surface-treated copper foil. A printed wiring board provided with a circuit pattern formed by etching the above-mentioned surface-treated copper foil of the copper-clad laminated board of claim 10.

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