JP7300976B2 - Surface treated copper foil, copper clad laminate and printed wiring board - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to surface-treated copper foils, copper-clad laminates, and printed wiring boards.

Copper clad laminates are widely used in various applications such as flexible printed wiring boards. This flexible printed wiring board is made by etching the copper foil of a copper-clad laminate to form a conductor pattern (also called a "wiring pattern"), and mounting electronic components on the conductor pattern by connecting them with solder. manufactured.

2. Description of the Related Art In recent years, in electronic devices such as personal computers and mobile terminals, the frequency of electrical signals has been increasing along with the increase in communication speed and capacity. In particular, the higher the frequency of an electrical signal, the greater the loss (attenuation) of signal power, making it more likely that data cannot be read. Therefore, it is desired to reduce the loss of signal power.

Signal power loss (transmission loss) in an electronic circuit can be roughly divided into two types. The first is conductor loss, that is, loss due to copper foil, and the second is dielectric loss, that is, loss due to resin substrate.
Conductor loss has a skin effect in a high frequency range, and current has the property of flowing on the surface of the conductor. Therefore, in order to reduce the conductor loss of high frequency signals, it is desirable to reduce the surface roughness of the copper foil. Hereinafter, the terms "transmission loss" and "conductor loss" in this specification mainly mean "transmission loss of high-frequency signals" and "conductor loss of high-frequency signals".

On the other hand, since the dielectric loss depends on the type of resin base material, it is possible to use a resin base material made of a low dielectric material (eg, liquid crystal polymer, low dielectric polyimide) in a circuit board through which high frequency signals flow. desirable. In addition, since the dielectric loss is also affected by the adhesive that bonds the copper foil and the resin substrate together, it is desirable to bond the copper foil and the resin substrate without using an adhesive.
Therefore, it has been proposed to form a surface treatment layer on at least one surface of the copper foil in order to bond the copper foil and the resin substrate without using an adhesive. For example, Patent Literature 1 proposes a method of providing a roughening treatment layer formed of roughening particles on a copper foil and forming a silane coupling treatment layer on the outermost layer.

Japanese Unexamined Patent Application Publication No. 2012-112009

The roughening treatment layer can increase the adhesiveness between the copper foil and the resin base material due to the anchoring effect of the roughening particles, but it may increase the conductor loss due to the skin effect. It is desirable to electrodeposit less roughening particles. On the other hand, when the number of roughening particles to be electrodeposited on the copper foil surface is reduced, the anchoring effect of the roughening particles is reduced, and sufficient adhesiveness between the copper foil and the resin substrate cannot be obtained. In particular, resin substrates made from low-dielectric materials such as liquid crystal polymers and low-dielectric polyimides are more difficult to adhere to copper foils than conventional resin substrates. It is desired to develop a method to increase the
In addition, although the silane coupling treatment layer has the effect of improving the adhesion between the copper foil and the resin base material, the effect of improving the adhesion may not be sufficient depending on the type.

An embodiment of the present invention has been made to solve the above problems, and a surface-treated copper foil capable of improving adhesion to a resin substrate, particularly a resin substrate suitable for high frequency applications. intended to provide
Another object of an embodiment 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.
A further object of the present invention is 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.

As a result of intensive research on surface-treated copper foils to solve the above problems, the present inventors have found that among the various indices of surface roughness of the surface-treated layer, the load area ratio that separates the protruding peak portion and the core portion is SMr1, Spk or Sk is specified based on the knowledge that SMr1, the protruding peak height Spk and the level difference Sk of the core are closely related to the adhesion between the surface-treated copper foil and the resin substrate. The inventors have found that the adhesiveness between the surface-treated copper foil and the resin base material can be enhanced by controlling the range of .

That is, an embodiment of the present invention has a copper foil and a surface treatment layer formed on at least one surface of the copper foil, and the load area ratio separating the protruding mountain portion and the core portion of the surface treatment layer SMr1 is 16 to 28%, the height Spk of the protruded peak portion of the surface treatment layer is 1.2 to 2.5 μm, and the level difference Sk of the core portion of the surface treatment layer is 1.0 to 2.0 μm. It relates to a surface-treated copper foil , which is 0 μm .
Further , an embodiment of the present invention relates to a copper-clad laminate comprising the surface-treated copper foil and a resin substrate adhered to the surface treatment layer of the surface-treated copper foil.
Furthermore, an embodiment of the present invention relates to a printed wiring board provided with a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate.

According to an embodiment of the present invention, it is possible to provide a surface-treated copper foil capable of enhancing adhesiveness to a resin substrate, particularly to a resin substrate suitable for high frequency applications.
Further, 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 the surface-treated copper foil.
Furthermore, according to the embodiment of the present invention, it is possible to provide a printed wiring board having excellent adhesiveness between a resin substrate, particularly a resin substrate suitable for high frequency applications, and a circuit pattern.

It is a cross-sectional schematic diagram of the surface-treated copper foil which has a roughening process layer in one side of copper foil. 1 is SEM photographs of surface treatment layers in surface treated copper foils of Example 1 and Comparative Example 1. FIG.

Hereinafter, preferred embodiments of the present invention will be specifically described, but the present invention should not be construed as being limited to these, and as long as it does not depart from the gist of the present invention, based on the knowledge of those skilled in the art , various modifications, improvements, etc. may be made. A plurality of constituent elements disclosed in the following embodiments can be combined appropriately to form various inventions. For example, some constituent elements may be deleted from all the constituent elements shown in the following embodiments, or constituent elements of different embodiments may be combined as appropriate.

(Embodiment 1)
Embodiment 1 of the present invention has a copper foil and a surface treatment layer formed on at least one surface of the copper foil, and has a load area ratio SMr1 of 16 that separates the protruding peaks and the core of the surface treatment layer. It relates to a surface treated copper foil that is ∼28%.
Further, Embodiment 1 of the present invention relates to a copper-clad laminate comprising the above-described surface-treated copper foil and a resin substrate adhered to the surface-treated layer of the above-described surface-treated copper foil.
Furthermore, Embodiment 1 of the present invention relates to a printed wiring board provided with a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate.

The surface treatment layer of the surface-treated copper foil according to Embodiment 1 of the present invention may be formed only on one surface of the copper foil, or may be formed on both surfaces of the copper foil. Moreover, when surface treatment layers are formed on both surfaces of the copper foil, the types of the surface treatment layers may be the same or different.

A load area ratio SMr1 that separates the protruding peak portion and the core portion represents the ratio of the protruding peak portion above the core portion, and the larger the ratio of the protruding peak portion, the larger the value of SMr1. SMr1 is measured according to ISO 25178. When a resin base material is adhered to the surface treatment layer of the surface-treated copper foil, if the proportion of protruding peaks in the surface treatment layer is small, the force required to peel the resin base material from the surface treatment layer (hereinafter referred to as "peeling force" ) concentrates on the surface of the core. Therefore, by setting the SMr1 of the surface treatment layer to 16% or more (increasing the ratio of the protruding peaks), the presence of the protruding peaks makes it easier to disperse the peeling force in the height direction of the protruding peaks. can. As a result, the adhesive strength between the surface-treated copper foil and the resin substrate is increased. On the other hand, by setting SMr1 of the surface treatment layer to 28% or less, it is possible to suppress an increase in transmission loss due to the skin effect.

The surface treatment layer preferably has a peak height Spk of 1.2 to 2.5 μm.
Here, the peak height Spk is measured according to ISO 25178. When a resin substrate is adhered to the surface-treated layer of the surface-treated copper foil, if the protruding peaks of the surface-treated layer are low, the peel force concentrates on the surface of the core portion. Therefore, by setting the Spk of the surface treatment layer to 1.2 μm or more (increasing the height of the protruding peaks), the presence of the protruding peaks makes it possible to easily disperse the peeling force in the height direction of the protruding peaks. . As a result, the adhesive strength between the surface-treated copper foil and the resin substrate is increased. On the other hand, by setting the Spk of the surface treatment layer to 2.5 μm or less, it is possible to suppress an increase in transmission loss due to the skin effect.

The surface treatment layer preferably has a level difference Sk of the core portion of the surface treatment layer of 1.0 to 2.0 μm.
Here, the level difference Sk of the core portion of the surface treatment layer represents the degree of variation in the height of the portion (core portion) excluding the protruding peaks and protruding valleys, and is measured according to ISO 25178. When a resin substrate is adhered to the surface-treated layer of the surface-treated copper foil, if the height of the core portion is small, the core portion becomes substantially planar, and the peeling force concentrates on the upper surface thereof. Therefore, by setting the Sk of the surface treatment layer to 1.0 μm or more (increasing the variation in the height of the core portion), the upper surface of the core portion is made uneven, and the peeling force is increased in the height direction of the core portion. Dispersion can be facilitated. As a result, the adhesive strength between the surface-treated copper foil and the resin substrate is increased. On the other hand, by setting the Sk of the surface treatment layer to 2.0 μm or less, it is possible to suppress an increase in transmission loss due to the skin effect.

The type of surface treatment layer is not particularly limited, and various surface treatment layers known in the art can be used.
Examples of surface treatment layers include roughening treatment layers, heat resistance treatment layers, rust prevention treatment layers, chromate treatment layers, silane coupling treatment layers, and the like. These layers can be used singly or in combination of two or more. Among them, the surface treatment layer preferably has a roughening treatment layer from the viewpoint of adhesion to the resin substrate.
In addition, when the surface treatment layer has one or more layers selected from the group consisting of a heat-resistant treatment layer, an antirust treatment layer, a chromate treatment layer and a silane coupling treatment layer, these layers are on the roughening treatment layer. is preferably provided in

Here, as an example, FIG. 1 shows a schematic cross-sectional view of a surface-treated copper foil having a roughened layer on one surface of the copper foil.
As shown in FIG. 1, the roughening treatment layer formed on one surface of the copper foil 10 includes primary roughening particles 20, a cover plating layer 30 covering the primary roughening particles 20, and a cover plating layer 30 and secondary roughening particles 40 formed thereon. It is preferable that the primary roughened particles 20 coated with the covering plating layer 30 are substantially spherical, and the secondary roughened particles 40 are formed so as to spread like a tree. With such a structure, SMr1, Spk and Sk of the surface treatment layer can be easily controlled within the above ranges.

The primary roughening particles 20 are not particularly limited, but are formed from 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. be able to. Among them, the primary roughening particles 20 are preferably made of copper or a copper alloy, particularly copper.
The covering plating layer 30 is not particularly limited, but can be made of copper, silver, gold, nickel, cobalt, zinc, or the like.
The secondary roughening particles 40 are not particularly limited, but can be made 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 made of a copper alloy, particularly a Cu--Co--Ni alloy.

The roughened layer can be formed by electroplating. The conditions are not particularly limited as long as they are adjusted according to the electroplating apparatus to be used, but typical conditions are as follows.
(Condition R1 for forming primary roughened particles 20)
Plating solution composition: 5-15 g/L Cu, 40-100 g/L sulfuric acid Plating solution temperature: 20-50°C
Electroplating conditions: current density 30-60 A/dm ² , coulomb amount 40-100 As/dm ²

(Formation condition R2 of cover plating layer 30)
Plating solution composition: 10-30 g/L Cu, 70-130 g/L sulfuric acid Plating solution temperature: 30-60°C
Electroplating conditions: current density 4.8-15 A/dm ² , coulomb amount 10-35 As/dm ²

(Formation condition Y of secondary roughened particles 40)
Plating solution composition: 10-20 g/L Cu, 5-15 g/L Co, 5-15 g/L Ni
pH: 2-3
Plating solution temperature: 30-40°C
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 growth of the primary roughened particles 20 in the Z direction (the direction perpendicular to the copper foil 10) is suppressed. In addition, under the formation condition R2 of the covering plating layer 30, the layer grows uniformly thicker in the XYZ directions as the amount of coulombs increases. Therefore, by controlling the coulomb amount (R1)/coulomb amount (R2) to be 6.0 or less, preferably 4.0 or less, the shape of the primary roughened particles 20 coated with the cover plating layer 30 is substantially spherical. ∼ can be controlled to a substantially hemispherical shape. Then, the secondary roughening particles 40 are formed on the covering plating layer 30 by controlling the primary roughening particles 20 coated with the covering plating layer 30 to have a substantially spherical to substantially semispherical shape. It becomes easier for the particles 40 to be formed so as to spread like a tree.
In addition, when the coulomb amount (R1)/coulomb amount (R2) exceeds 6.0, the growth of the primary roughened particles 20 in the Z direction increases. The shape is approximately ellipsoid to approximately semi-ellipsoid. Therefore, the secondary roughening particles 40 formed on the covering plating layer 30 are less likely to spread in a dendritic manner.

The heat-resistant layer and the rust-proof layer are not particularly limited, and can be formed from materials known in the art. In addition, since the heat-resistant treatment layer may also function as a rust-preventive treatment layer, a single layer having the functions of both the heat-resistant treatment layer and the rust-preventive treatment layer is formed as the heat-resistant treatment layer and the rust-preventive treatment layer. good too.
As the heat-resistant layer and/or rust-proof layer, nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, platinum group elements, iron, tantalum It can be a layer containing one or more elements selected from the group of (any form of metal, alloy, oxide, nitride, sulfide, etc.). Among them, the heat-resistant layer and/or the rust-proof layer is preferably a Ni--Zn layer or a Zn layer. In particular, if the Ni-Zn layer contains less Ni than the Zn content, or if the Zn layer does not contain Ni, the conductor loss can be reduced without significantly reducing the heat resistance and rust prevention effects. It is preferable because it becomes

The heat-resistant layer and the rust-proof layer can be formed by electroplating. The conditions may be adjusted according to the electroplating apparatus to be used, and are not particularly limited, but the conditions for forming the heat-resistant layer (Ni—Zn layer) using a general electroplating apparatus are as follows. be.
Plating solution composition: 1 to 30 g/L Ni, 1 to 30 g/L Zn
Plating solution pH: 2-5
Plating solution temperature: 30-50°C
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 from materials known in the technical field.
As used herein, the term "chromate treatment layer" means a layer formed of a liquid containing chromic anhydride, chromic acid, dichromic acid, chromate, or dichromate. The chromating layer contains elements such as cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, titanium, etc. (any metal, alloy, oxide, nitride, sulfide, etc.) morphology). Examples of the chromate-treated layer include a chromate-treated layer treated with an aqueous solution of chromic acid anhydride or potassium dichromate, a chromate-treated layer treated with a treatment liquid containing chromic anhydride or potassium dichromate and zinc, and the like.

The chromate treatment layer can be formed by known methods such as immersion chromate treatment and electrolytic chromate treatment. Although these conditions are not particularly limited, for example, the conditions for forming a general immersion chromate treatment layer are as follows.
Chromate liquid composition: 1-10 g/L K ₂ Cr ₂ O ₇ , 0.01-10 g/L Zn
Chromate solution pH: 2-5
Chromate liquid temperature: 30-55°C

The silane coupling-treated layer is not particularly limited, and can be formed from materials known in the art.
Here, the term "silane coupling treated layer" as used herein means a layer formed with a silane coupling agent.
The silane coupling agent is not particularly limited, and those 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. , triazine-based silane coupling agents, and the like. Among these, amino-based silane coupling agents and epoxy-based silane coupling agents are preferred. The above-mentioned silane coupling agents can be used alone or in combination of two or more.
As a typical method for forming a silane coupling treatment layer, a 1.2% by volume aqueous solution (pH: 10 ) and dried to form a silane coupling-treated layer.

The copper foil is not particularly limited, and may be either an electrolytic copper foil or a rolled copper foil. Electrodeposited copper foil is generally produced by electrolytically depositing copper from a copper sulfate plating bath onto a titanium or stainless steel drum. It has an M surface (matte surface) formed on the opposite side. In general, since the M side of the electrolytic copper foil has unevenness, a surface treatment layer is formed on the M side of the electrodeposited copper foil, and this surface treatment layer is adhered to the resin base material, whereby the surface treatment layer and the resin Adhesion to the substrate can be enhanced.

The material of the copper foil is not particularly limited. High purity copper such as C1020 or JIS H3510 alloy number C1011) can be used. Copper alloys such as Sn-containing copper, Ag-containing copper, copper alloys containing Cr, Zr, Mg, etc., and Corson copper alloys containing Ni, Si, etc. can also be used. In this specification, "copper foil" is a concept including copper alloy foil.

The thickness of the copper foil is not particularly limited. .

The surface-treated copper foil having the configuration as described above can be produced according to a method known in the art. Here, SMr1, Spk and Sk of the surface treatment layer can be controlled by adjusting the conditions for forming the surface treatment layer, particularly the conditions for forming the roughening treatment layer described above.

In the surface-treated copper foil according to Embodiment 1 of the present invention, the load area ratio SMr1 that separates the protruding peaks and the core portion of the surface-treated layer is controlled to 16 to 28%, so the surface treatment of the surface-treated copper foil When the resin base material is adhered to the layer, the presence of the protruding peaks makes it easy to distribute the peeling force in the height direction of the protruding peaks. Therefore, this surface-treated copper foil can improve adhesiveness to resin substrates, particularly resin substrates suitable for high frequency applications.

The copper-clad laminate according to Embodiment 1 of the present invention can be produced by adhering a resin base material to the surface-treated layer of the surface-treated copper foil.
The resin substrate is not particularly limited, and those known in the art can be used. Examples of resin base materials include paper base phenol resin, paper base epoxy resin, synthetic fiber cloth base epoxy resin, glass cloth/paper composite base epoxy resin, glass cloth/glass nonwoven cloth composite base epoxy resin, glass Examples include cloth-based epoxy resins, polyester films, polyimide films, liquid crystal polymers, and fluorine resins.

The method for bonding the surface-treated copper foil and the resin substrate is not particularly limited, and can be performed according to a method known in the art. For example, a surface-treated copper foil and a resin base material may be laminated and thermocompression bonded.
The copper-clad laminate manufactured as described above can be used for manufacturing a printed wiring board.

Since the copper-clad laminate according to Embodiment 1 of the present invention uses the above surface-treated copper foil, it is possible to improve adhesion to a resin substrate, particularly a resin substrate suitable for high-frequency applications.

The printed wiring board according to Embodiment 1 of the present invention can be manufactured by etching the surface-treated copper foil of the copper-clad laminate to form a circuit pattern. A method for forming a 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 subtractive method is preferable as the method of forming the circuit pattern.

When manufacturing a printed wiring board by a subtractive method, it is preferable to carry out as follows. First, a predetermined resist pattern is formed by applying a resist to the surface of the surface-treated copper foil of the copper clad laminate, exposing and developing the resist. Next, the circuit pattern is formed by removing the surface-treated copper foil from the portion where the resist pattern is not formed (unnecessary portion) by etching. Finally, the resist pattern on the surface-treated copper foil is removed.
Various conditions in this subtractive method are not particularly limited, and can be carried out according to conditions known in the technical field.

Since the printed wiring board according to Embodiment 1 of the present invention uses the above copper-clad laminate, it has excellent adhesiveness between the resin substrate, particularly the resin substrate suitable for high frequency applications, and the circuit pattern. there is

(Embodiment 2)
Embodiment 2 of the present invention has a copper foil and a surface treatment layer formed on at least one surface of the copper foil, and the protruding peak height Spk of the surface treatment layer is 1.2 to 2.5 μm. It relates to a certain surface-treated copper foil.
Further, Embodiment 2 of the present invention relates to a copper-clad laminate comprising the above-described surface-treated copper foil and a resin substrate adhered to the surface-treated layer of the above-described surface-treated copper foil.
Further, Embodiment 2 of the present invention relates to a printed wiring board provided with a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate.
In addition, in the description of Embodiment 2 of the present invention, the description of features similar to those of Embodiment 1 of the present invention will be omitted.

In the surface-treated copper foil according to Embodiment 2 of the present invention, by setting the Spk of the surface treatment layer to 1.2 μm or more, the presence of the protruding peaks makes it easy to disperse the peeling force in the height direction of the protruding peaks. Therefore, the adhesive strength between the surface-treated copper foil and the resin substrate is increased. On the other hand, by setting the Spk of the surface treatment layer to 2.5 μm or less, it is possible to suppress an increase in transmission loss due to the skin effect.

The surface treatment layer preferably has a level difference Sk of the core portion of the surface treatment layer of 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 core portion can be made uneven, and the peeling force can be easily dispersed in the height direction of the core portion. Adhesive strength to the base material is increased. On the other hand, by setting the Sk of the surface treatment layer to 2.0 μm, it is possible to suppress an increase in transmission loss due to the skin effect.

The surface-treated copper foil according to Embodiment 2 of the present invention can be produced according to a method known in the technical field. Here, the Spk and Sk of the surface treatment layer can be controlled by adjusting the conditions for forming the surface treatment layer, particularly the conditions for forming the roughening treatment layer described above.

In the surface-treated copper foil according to Embodiment 2 of the present invention, the protruding peak height Spk of the surface treatment layer is controlled to 1.2 to 2.5 μm. It can be made easy to disperse in the height direction of the part. Therefore, this surface-treated copper foil can improve adhesiveness to resin substrates, particularly resin substrates suitable for high frequency applications.

A copper-clad laminate according to Embodiment 2 of the present invention can be produced by adhering a resin substrate to the surface-treated layer of the surface-treated copper foil.
Since the copper-clad laminate according to Embodiment 2 of the present invention uses the above surface-treated copper foil, it is possible to improve the adhesiveness to resin substrates, particularly resin substrates suitable for high-frequency applications.

A printed wiring board according to Embodiment 2 of the present invention can be manufactured by etching the surface-treated copper foil of the copper-clad laminate to form a circuit pattern.
Since the printed wiring board according to Embodiment 2 of the present invention uses the above copper-clad laminate, it has excellent adhesiveness between the resin base material, particularly the resin base material suitable for high frequency applications, and the circuit pattern. there is

(Embodiment 3)
Embodiment 3 of the present invention has a copper foil and a surface treatment layer formed on at least one surface of the copper foil, and the level difference Sk of the core portion of the surface treatment layer is 1.0 to 2.0 μm. It relates to a certain surface-treated copper foil.
Further, Embodiment 3 of the present invention relates to a copper-clad laminate comprising the above-described surface-treated copper foil and a resin substrate adhered to the surface-treated layer of the above-described surface-treated copper foil.
Furthermore, Embodiment 3 of the present invention relates to a printed wiring board provided with a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate.
In addition, in the description of Embodiment 3 of the present invention, the description of features similar to those of Embodiment 1 of the present invention will be omitted.

In the surface-treated copper foil according to Embodiment 3 of the present invention, by setting the Sk of the surface treatment layer to 1.0 μm or more, the upper surface of the core portion is made uneven, and the peeling force is dispersed in the height direction of the core portion. Therefore, the adhesive strength between the surface-treated copper foil and the resin substrate is increased. On the other hand, by setting the Sk of the surface treatment layer to 2.0 μm or less, it is possible to suppress an increase in transmission loss due to the skin effect.

The surface-treated copper foil according to Embodiment 3 of the present invention can be produced according to a method known in the technical field. Here, the Sk of the surface treatment layer can be controlled by adjusting the conditions for forming the surface treatment layer, particularly the conditions for forming the roughening treatment layer described above.

In the surface-treated copper foil according to Embodiment 3 of the present invention, since the level difference Sk of the core portion of the surface treatment layer is controlled to 1.0 to 2.0 μm, the upper surface of the core portion is made uneven and peeled. The force can be easily distributed in the height direction of the core portion. Therefore, this surface-treated copper foil can improve adhesiveness to resin substrates, particularly resin substrates suitable for high frequency applications.

A copper-clad laminate according to Embodiment 3 of the present invention can be produced by adhering a resin substrate to the surface-treated layer of the surface-treated copper foil.
Since the copper-clad laminate according to Embodiment 3 of the present invention uses the surface-treated copper foil described above, it is possible to improve adhesion to a resin substrate, particularly a resin substrate suitable for high-frequency applications.

A printed wiring board according to Embodiment 3 of the present invention can be produced by etching the surface-treated copper foil of the copper-clad laminate to form a circuit pattern.
Since the printed wiring board according to Embodiment 3 of the present invention uses the above copper-clad laminate, it has excellent adhesiveness between the resin substrate, particularly the resin substrate suitable for high frequency applications, and the circuit pattern. there is

EXAMPLES The embodiments of the present invention will be described in more detail below with reference to Examples, but the present invention is not limited by these Examples. Examples 5, 10 and 12 are reference examples.

(Example 1)
A rolled copper foil A (with a Young's modulus after recrystallization of 120 GPa and a thickness of 12 μm) is prepared, one surface is degreased and pickled, and then a roughening treatment layer is formed as a surface treatment layer. got the foil. The conditions for forming the roughened layer were as follows.
<Condition R1 for forming primary roughened particles>
Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid Plating solution temperature: 25°C
Electroplating conditions: current density 35.6 A/dm ² , coulomb amount 72.7 As/dm ²

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

(Formation condition Y of secondary roughened particles 40)
Plating solution composition: 15.5 g/L Cu, 7.5 g/L Co, 9.5 g/L Ni
pH: 2.4
Plating solution temperature: 36°C
Electroplating conditions: current density 33.1 A/dm ² , coulomb amount 44.8 As/dm ²

(Examples 2 to 14 and Comparative Example 1)
A surface-treated copper foil was obtained in the same manner as in Example 1 except that at least one of the type of rolled copper foil, the current density in R1, R2 and Y and the amount of coulombs was changed as shown in Table 1. In Table 1, the rolled copper foil B is a rolled copper foil having a Young's modulus of 85 GPa and a thickness of 12 μm after recrystallization.

For the surface-treated copper foils obtained in the above examples and comparative examples, the surface state of the surface-treated layer was observed using a scanning electron microscope (SEM). As a result, in Examples 1 to 14, many structures in which the roughened particles (especially secondary roughened particles) spread in a dendritic manner were confirmed, whereas in Comparative Example 1, almost no such structure was confirmed. As a typical example, FIG. 2 shows SEM photographs (20,000×, 40° tilt) of the surface treated layers (roughened layers) of the surface treated copper foils of Example 1 and Comparative Example 1. FIG.

Next, the following property evaluations were performed on the surface-treated copper foils obtained in the above examples and comparative examples.
<SMr1, Spk, and Sk of surface treatment layer>
Images were captured using a laser microscope (LEXT OLS4000) manufactured by Olympus Corporation. The captured images were analyzed using analysis software for a laser microscope (LEXT OLS4100) manufactured by Olympus Corporation. Measurements of SMr1, Spk and Sk were performed according to ISO 25178, respectively. Moreover, these measurement results were the average values of the values measured at arbitrary three locations. The temperature during the measurement was 23 to 25°C. Main setting conditions for the laser microscope and analysis software are as follows.
Objective lens: MPLAPON50XLEXT (magnification: 50x, numerical aperture: 0.95, liquid immersion type: air, mechanical barrel length: ∞, cover glass thickness: 0, field number: FN18)
Optical zoom magnification: 1x Scanning mode: XYZ high precision (height resolution: 10 nm, number of pixels of captured data: 1024 x 1024)
Captured image size [Number of pixels]: Horizontal 257 μm × Vertical 258 μm [1024 × 1024]
(Since it is measured in the horizontal direction, it corresponds to 257 μm as an evaluation length)
DIC: Off Multilayer: Off Laser intensity: 100
Offset: 0
Confocal level: 0
Beam diameter aperture: OFF Image average: 1 time Noise reduction: ON Brightness unevenness correction: ON Optical noise filter: ON Cutoff: None (λc, λs, λf none)
Filter: Gaussian filter Noise removal: Pre-measurement processing Surface (tilt) correction: Implemented

<Peel strength>
A surface-treated copper foil is coated with a 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.; thickness 50 μm or 100 μm)], a circuit with a width of 3 mm was formed in the TD direction (the width direction of the rolled copper foil). Next, the strength (TD180° peel strength) when the circuit (surface-treated copper foil) is peeled off from the surface of the resin base material at a speed of 50 mm/min in the TD180° direction is measured according to JIS C6471:1995. measured by The measurement was performed three times, and the average value was taken 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.
The circuit width was adjusted by a normal subtractive etching method using a copper chloride etchant.

Table 2 shows the results of the above characterization.

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

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

Claims (7)

Having a copper foil and a surface treatment layer formed on at least one surface of the copper foil,
The load area ratio SMr1 separating the protruding mountain portion and the core portion of the surface treatment layer is 16 to 28%,
The protruding peak height Spk of the surface treatment layer is 1.2 to 2.5 μm,
A surface-treated copper foil, wherein the level difference Sk of the core portion of the surface-treated layer is 1.0 to 2.0 μm . The surface-treated copper foil according to claim 1 , wherein the surface treatment layer has a roughening treatment layer. The roughening treatment layer includes primary roughening particles, a covering plating layer covering the primary roughening particles, and secondary roughening particles formed on the covering plating layer, according to claim 2 Surface treated copper foil. 4. The surface treatment layer further has one or more layers selected from the group consisting of a heat-resistant treatment layer, an anticorrosion treatment layer, a chromate treatment layer and a silane coupling treatment layer on the roughening treatment layer. The surface-treated copper foil according to 2 or 3 . The surface-treated copper foil according to any one of claims 1 to 4 , wherein the copper foil is a rolled copper foil. A copper-clad laminate comprising the surface-treated copper foil according to any one of claims 1 to 5 and a resin substrate adhered to the surface-treated layer of the surface-treated copper foil. A printed wiring board comprising a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate according to claim 6 .

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