TWI747088B - Surface treatment copper foil, copper clad laminate and printed wiring board - Google Patents

Abstract

The surface-treated copper foil of the present invention has a copper foil and a surface-treated layer formed on at least one surface of the copper foil. The root mean square slope RΔq of the surface treatment layer of the surface treatment copper foil is 37-70°. In addition, the copper-clad laminated board of the present invention is provided with a surface-treated copper foil and a resin base material that is followed by a surface-treated layer of the surface-treated copper foil.

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 etching the copper foil of a copper clad laminate to form a conductor pattern (also called a "wiring pattern"), and then connect the electronic parts on the conductor pattern by soldering and mounting.

In recent years, in electronic devices such as personal computers and mobile terminals, with the increase in communication speed and capacity, and the increase in high frequency of electrical signals, there is a demand for flexible printed wiring boards that can cope with this. In particular, the higher the frequency of the electrical signal, the greater the loss (attenuation) of the signal power, and the easier it is to be unable to read the data. Therefore, it is required to reduce the loss of signal power.

Signal power loss (transmission loss) in electronic circuits can be roughly divided into two types. One is the conductor loss, that is, the loss caused by the copper foil, and the second is the dielectric loss, that is, the loss caused by the resin substrate.

The conductor loss has a skin effect in the high frequency domain, and has the characteristic of current flowing through the surface of the conductor. Therefore, if the surface of the copper foil is rough, the current flows through 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, in this manual, when only “transmission loss” and “conductor loss” are described, it mainly means “transmission loss of high-frequency signal” and “conductor loss of high-frequency signal”.

On the other hand, the loss of the dielectric body depends on the type of resin substrate, so it is In the circuit substrate through which the signal flows, it is desirable to use a resin substrate formed of a low-dielectric material (for example, liquid crystal polymer, low-dielectric polyimide). In addition, the loss of the dielectric body is also affected by the adhesive bonding between the copper foil and the resin substrate. Therefore, it is ideal for bonding between the copper foil and the resin substrate without using an adhesive.

Therefore, in order to bond between the copper foil and the resin substrate without using an adhesive, it is proposed to form a surface treatment layer on at least one surface of the copper foil. For example, Patent Document 1 proposes a method in which a roughening treatment layer formed of roughened particles is provided on a copper foil, and a silane coupling treatment layer is formed on the outermost layer.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2012-112009 A

The roughening treatment layer can improve the adhesion between the copper foil and the resin substrate by the anchoring effect produced by the roughening particles, but there is a situation that the conductor loss is increased due to the skin effect, so it is ideal to reduce the electrodeposition on the Roughened particles on the surface of copper foil. On the other hand, if the roughened particles electrodeposited on the surface of the copper foil are reduced, the anchoring effect produced by the roughened particles is reduced, and the adhesion between the copper foil and the resin substrate cannot be sufficiently obtained. In particular, resin substrates made of low-dielectric materials such as liquid crystal polymer and low-dielectric polyimide are also difficult to bond with copper foil compared to conventional resin substrates. Therefore, it is desired to develop and improve the gap between copper foil and resin substrate. The method of coherence.

In addition, the silane coupling treatment layer has the effect of improving the adhesiveness between the copper foil and the resin substrate, but depending on the type, the adhesiveness improvement effect may be insufficient.

The embodiment of the present invention was completed in order to solve the above-mentioned problems, and its object 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 having excellent adhesiveness between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a circuit pattern.

The inventors of the present invention conducted intensive research to solve the above problems. As a result, they found that the root mean square slope R△q of the surface treatment layer based on the surface treatment copper foil and the adhesion between the surface treatment copper foil and the resin substrate are close. Related insights, by controlling the root-mean-square slope R△q of the surface-treated layer of the surface-treated copper foil within a specific range, the adhesion between the surface-treated copper foil and the resin substrate can be improved, thereby completing this The implementation form of the invention.

That is, 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 above-mentioned copper foil, and the root-mean-square slope RΔq of the above-mentioned surface-treated layer is 37~ 70°.

In addition, an embodiment of the present invention is 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 is 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.

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, 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 adhesiveness between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a circuit pattern.

Hereinafter, suitable embodiments of the present invention will be specifically described, but the present invention should not be limited to these explanations, and various changes, improvements, etc. can be made based on the knowledge of the industry as long as it does not deviate from the gist of the present invention. The various components disclosed in this embodiment can form various inventions by appropriately combining them. For example, some constituent elements may be deleted from all the constituent elements shown in this embodiment, or constituent elements of different embodiments may be appropriately combined.

The surface-treated copper foil of the embodiment of the present invention has a copper foil and a surface-treated layer formed on at least one surface of the copper foil. That is, the surface treatment layer may be formed only on 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 root mean square slope R△q of the surface treatment layer is 37~70°.

Here, the root mean square slope R△q represents the root mean square of the local slope dz/dx of the reference length of the roughness curve, measured in accordance with JIS B0601:2013. The R△q of the surface treatment layer is an index indicating the slope of the unevenness of the surface of the surface treatment layer. The R△q of the surface treatment layer increases when the z-direction growth of the surface treatment layer (especially the roughened particles of the roughening treatment layer) is larger, and it is easy to perform when the surface treatment copper foil is attached to the resin substrate. Appropriate anchoring effect, on the other hand, the transmission loss becomes larger due to the skin effect. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, the RΔq of the surface treatment layer is controlled to 37 to 70°, preferably 45 to 65°.

The surface treatment layer preferably has an arithmetic average roughness Ra of 0.25 to 0.40 μm.

Here, the arithmetic average roughness Ra represents the average of Z(x) of the reference length of the roughness curve, according to Measured according to JIS B0601:2013. The Ra of the surface treatment layer is an index indicating the average roughness of the surface of the surface treatment layer. If the Ra of the surface treatment layer is large, the surface of the surface treatment layer becomes rough, so when the surface treatment copper foil is attached to the resin substrate, it is easy to exert the anchoring effect. On the other hand, the transmission loss due to the skin effect Get bigger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the Ra of the surface treatment layer to 0.25 to 0.40 μm, and more preferably to 0.28 to 0.35 μm.

The surface treatment layer preferably has an arithmetic average height Sa of 0.25 to 0.40 μm.

Here, the arithmetic average height Sa is a parameter that extends the two-dimensional parameter Ra to three-dimensional, and is measured in accordance with ISO 25178. The Sa of the surface treatment layer and Ra are the same indexes indicating the average roughness of the surface of the surface treatment layer. If the Sa of the surface treatment layer is large, the surface of the surface treatment layer becomes rough, so when the surface treatment copper foil is attached to the resin substrate, it is easy to exert the anchoring effect. On the other hand, the transmission loss due to the skin effect Get bigger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the Sa of the surface treatment layer to 0.25 to 0.40 μm, and more preferably to 0.30 to 0.40 μm.

The surface treatment layer preferably has a maximum height roughness Rz of 2.3 to 5.1 μm.

Here, the maximum height roughness Rz represents the sum of the maximum value of the peak height and the maximum value of the valley depth of the profile curve of the reference length, and is measured in accordance with JIS B0601:2013. The Rz of the surface treatment layer is an index indicating whether there are protrusions (peaks and valleys) on the surface of the surface treatment layer. If the Rz of the surface treatment layer is large, there will be protruding irregularities on the surface of the surface treatment layer. Therefore, it is easy to exert an anchoring effect when the surface treatment copper foil is attached to the resin substrate. On the other hand, due to the skin effect And the transmission loss becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the Rz of the surface treatment layer to 2.3 to 5.1 μm, and more preferably to 2.5 to 3.5 μm.

The surface treatment layer preferably has a maximum height Sz of 4.4 to 7.4 μm.

Here, the maximum height Sz is the expansion of the two-dimensional parameter Rz to the three-dimensional parameter, according to ISO 25178 Determination. The Sz and Rz of the surface treatment layer are the same indexes that indicate whether the surface of the surface treatment layer has protruding irregularities. If the Sz of the surface treatment layer is large, there will be protruding irregularities on the surface of the surface treatment layer, so it is easy to exert the anchoring effect when the surface treatment copper foil is attached to the resin substrate. On the other hand, due to the skin effect And the transmission loss becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the Sz of the surface treatment layer to 4.4 to 7.4 μm, and more preferably to 5.0 to 6.5 μm.

The surface treatment layer preferably has a root mean square height Sq of 0.33 to 0.55 μm.

Here, the root mean square height Sq represents a parameter equivalent to the standard deviation of the distance from the average surface (standard deviation of height), measured in accordance with ISO 25178. The Sq of the surface treatment layer is an index indicating the unevenness of the height of the protrusions on the surface of the surface treatment layer. If the Sq of the surface treatment layer is large, the unevenness of the height of the convex part of the surface of the surface treatment layer becomes larger, and it is easy to exert an anchoring effect when the surface treatment copper foil is attached to the resin substrate. However, if Sq is too large (the unevenness of the height of the convex portion is too large), it may become a problem from the viewpoint of quality control as an industrial product. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the viewpoint of quality management, it is preferable to control the Sq of the surface treatment layer to 0.33 to 0.55 μm, and more preferably to 0.40 to 0.55 μm.

The surface treatment layer preferably has a minimum autocorrelation length Sal of 1.2 to 1.7 μm.

Here, the minimum autocorrelation length Sal represents the distance from the surface autocorrelation attenuation to the nearest lateral distance of the correlation value s (0≦s<1), measured in accordance with ISO 25178. The Sal of the surface treatment layer is an index indicating whether there is a sharp change in the height of the convex portion on the surface of the surface treatment layer. The Sal of the surface treatment layer is larger if the surface of the surface treatment layer is flatter, and the more convex parts are, the smaller. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the Sal of the surface treatment layer to 1.2 to 1.7 μm, and more preferably to 1.3 to 1.7 μm.

The surface treatment layer preferably has a load area ratio SMr1 separating the protruding peak portion and the core portion of 11.5 to 16.0%.

Here, the load area ratio SMr1 that separates the protruding peak portion and the core portion represents the number of protruding peak portions, and is measured in accordance with ISO 25178. If the SMr1 of the surface treatment layer is larger, the protruding peaks of the surface treatment layer will increase. Therefore, it is easy to exert the anchoring effect when the surface treatment copper foil is attached to the resin substrate. On the other hand, due to the skin effect The transmission loss becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the SMr1 of the surface treatment layer to 11.5~16.0%, more preferably 12.0~15.5%.

The surface treatment layer preferably has a load area ratio SMr2 separating the protruding valley portion and the core portion of 86.5-91.0%.

Here, the load area ratio SMr2 that separates the protruding valley portion and the core portion represents the number of protruding valley portions, and is measured in accordance with ISO 25178. If the SMr2 of the surface treatment layer is larger, the protruding valleys of the surface treatment layer will increase, so it is easy to exert the anchoring effect when the surface treatment copper foil is attached to the resin substrate. On the other hand, due to the skin effect The transmission loss becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the SMr2 of the surface treatment layer to 86.5-91.0%, more preferably 88.0-91.0%.

The surface treatment layer preferably has a protrusion peak height Spk of 0.41 to 1.03 μm.

Here, the protrusion height Spk is measured in accordance with ISO 25178. If the Spk of the surface treatment layer is larger, the height of the protruding peak of the surface treatment layer is larger, so it is easy to exert an anchoring effect when the surface treatment copper foil is attached to the resin substrate. On the other hand, due to the skin Effect and the transmission loss becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the Spk of the surface treatment layer to 0.41 to 1.03 μm, and more preferably to 0.55 to 1.00 μm.

The surface treatment layer preferably has an average length RSm of 3.3 to 5.2 μm.

Here, the average length RSm represents the average length of the contour curve elements of the reference length (that is, the average interval of the uneven shape on the surface), and is measured in accordance with JIS B0601:2013. The RSm of the surface treatment layer represents the density of the uneven shape of the surface treatment layer (especially the density of the roughened particles in the roughened particle layer) index. The smaller the RSm of the surface treatment layer, the higher the density of the uneven shape of the surface treatment layer. Therefore, it can be expected that the anchor effect will be easily exerted when the surface treatment copper foil is adhered to the resin substrate. However, if the RSm is too small (the density of the uneven shape of the surface treatment layer is significantly increased), the possibility of increased transmission loss cannot be denied. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, it is preferable to control the RSm of the surface treatment layer to 3.3-5.2 μm, more preferably 3.3 μm or more and less than 5.0 μm.

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.

Here, in this specification, the "roughened layer" refers to a layer containing roughened particles, and the "roughened particle" refers to particles of various shapes such as spherical, elliptical, rod-shaped, and dendritic. The formation of roughened particles is referred to as roughening treatment, which is usually performed by performing electroplating, especially so-called scorch plating. In addition, in the roughening treatment, there are cases where ordinary copper plating is performed as a pretreatment, or ordinary copper plating is performed as a final treatment in order to prevent the falling off of the roughened particles. In this manual, the "roughening treatment layer" Contains layers formed by these pre-treatments and final treatments.

The roughened particles are not particularly limited, and may be formed of any simple substance selected from the group consisting of copper, nickel, cobalt, phosphorus, tungsten, arsenic, molybdenum, chromium, and zinc, or an alloy containing any one or more of them. In addition, after the roughened particles are formed, a roughening treatment in which secondary particles and tertiary particles are provided by a simple substance or alloy of nickel, cobalt, copper, zinc, or the like may be further performed.

The roughening treatment layer can be formed by electroplating. The conditions are not particularly limited as long as they are adjusted according to the electroplating equipment used, and typical conditions are as follows. In addition, electroplating can also be performed in two stages. In addition, please note that the following conditions are that a cylindrical cathode wound with copper foil is placed in the center. The conditions in the beaker test where anodes are set at regular intervals around it and electroplating is performed.

Composition of plating solution: 11~30g/L Cu, 50~150g/L sulfuric acid

Plating bath temperature: 25~50℃

Electroplating conditions: current density 38.4~48.5A/dm ² , time 1~10 seconds

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, there are cases where the heat-resistant treatment layer also functions as a rust-preventing treatment layer, so one layer having the functions of both the heat-resistant treatment layer and the rust-preventing treatment layer can be formed as the heat-resistant treatment layer and the rust-preventing 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 A layer of one or more elements from the group of, iron, and tantalum (may be any form of metal, alloy, oxide, nitride, sulfide, etc.). Among them, the heat-resistant treatment layer and/or the anti-rust treatment layer are preferably 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, it is possible to reduce the conductor loss without greatly reducing the heat resistance and rust prevention effects.

The heat-resistant treatment layer and the anti-rust treatment layer can be formed by electroplating. The conditions are not particularly limited as long as they are adjusted according to the electroplating apparatus used. The conditions for forming the heat-resistant layer (Ni-Zn layer) using a general electroplating apparatus are as follows.

Composition of plating solution: 1~30g/L of Ni, 1~30g/L of Zn

Plating bath pH: 2~5

Temperature of plating solution: 30~50℃

Electroplating conditions: current density 1~10A/dm ² , time 0.1~5 seconds

In particular, if the Ni-Zn layer is formed under the following conditions, it is possible to reduce the conductor loss without greatly reducing the heat resistance effect and the rust preventive effect, which is preferable.

Composition of plating solution: 23.5g/L of Ni, 4.5g/L of Zn

Plating bath pH: 3.6

Plating bath temperature: 40℃

Electroplating conditions: current density 1.1A/dm ² , time 0.7 seconds

The chromate treatment layer is not particularly limited, and can be formed of materials known in the technical field.

Here, in this specification, "chromate treatment layer" means a layer formed from 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, etc.) And so on any form) layer. Examples of the chromate treatment layer include: a chromate treatment layer treated with chromic anhydride or potassium dichromate aqueous solution, and a treatment solution containing chromic anhydride or potassium dichromate and zinc. The chromate treatment layer and so on.

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 general immersion chromate treatment layer are as follows.

Chromate solution composition: 1~10g/L of K ₂ Cr ₂ O ₇ , 0.01~10g/L of Zn

PH of chromate solution: 2~5

Chromate liquid temperature: 30~55℃

The silane coupling treatment layer is not particularly limited, and can be formed of materials known in the technical field.

Here, in this specification, the "silane coupling treatment layer" means a layer formed of a silane coupling agent.

系矽烷偶合劑等。該等之中，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組合2種以上使用。 The silane coupling agent is not particularly limited, and those known in the technical field 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, ethylene-based silane coupling agents, and imidazole-based silanes Coupling agent, three

Department of silane coupling agent and so on. Among them, an amine-based silane coupling agent and an epoxy-based silane coupling agent are preferred. The above-mentioned silane coupling agents can be used singly 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 manufactured by electrolytically extracting copper from a copper sulfate plating bath on a rotating drum of titanium or stainless steel. It has a flat S surface (glossy surface) formed on the drum side and a surface formed on the opposite side of the S surface. M side (matte side). Generally, since the M surface of the electrolytic copper foil has unevenness, the surface treatment layer is formed on the M surface of the electrolytic copper foil to bond the surface treatment layer to the resin substrate, which can improve 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 H3100) commonly used as circuit patterns of printed wiring boards can be used. High-purity copper such as alloy number C1020 or JIS H3510 alloy number C1011). In addition, copper alloys such as copper doped with Sn, copper doped with Ag, copper alloys added with Cr, Zr, or Mg, and copper alloys such as Carson-based copper alloys added with Ni and Si can also be used. Furthermore, in this specification, "copper foil" 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 to 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 to 18 μm.

The surface-treated copper foil having the above-mentioned constitution can be manufactured according to a method known in the technical field. Here, the R△q, Ra, Sa, Rz, Sz, Sq, Sal, SMr1, SMr2, Spk, and RSm of the surface treatment layer can be determined by the formation conditions of the surface treatment layer, especially the roughening treatment layer. Wait for adjustment and control.

Copper clad laminates can be surface treated by adhering the resin substrate to the surface treatment copper foil Layered and manufactured.

It does not specifically limit as a resin base material, A well-known thing in this technical field can be used. Examples of resin substrates include: paper substrate phenol resin, paper substrate epoxy resin, synthetic fiber cloth substrate epoxy resin, glass cloth-paper composite substrate epoxy resin, glass cloth-glass nonwoven composite substrate Material epoxy resin, glass cloth base 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 laminates manufactured as described above can be used for the manufacture of printed wiring boards. The manufacturing method of a printed wiring board is not specifically limited, A well-known method, such as a subtractive method and a semi-additive method, can be used. Among them, the copper clad laminated board of the embodiment of the present invention is most suitable for the subtractive method.

In the case of manufacturing a printed wiring board by a subtractive method, it is preferably performed as follows. First, a photoresist is applied to the surface of the surface-treated copper foil of the copper-clad laminate, and then exposed and developed to form a specific photoresist pattern. Secondly, the surface-treated copper foil of the part (unused part) where the photoresist pattern is not formed is removed by etching. Finally, the photoresist pattern 20 on the surface-treated copper foil 1 is removed.

Furthermore, the various conditions in the subtractive method are not particularly limited, and can be carried out according to the conditions known in the technical field.

[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 a rolled copper foil (HA-V2 foil manufactured by JX Metal Company) with a thickness of 12μm. After degreasing and pickling one side, a roughening treatment layer and a chromate treatment layer as the surface treatment layer are sequentially formed to obtain Surface treatment copper foil. The conditions for forming each layer are as follows.

<Roughening treatment layer>

A cylindrical cathode formed by winding copper foil is arranged at the center, and anodes are arranged at certain intervals around the cathode to form a roughening treatment layer. The plating conditions are as follows.

Composition of plating solution: 11g/L Cu, 50g/L sulfuric acid

Temperature of plating solution: 25℃

Electroplating conditions: current density 48.5A/dm ² , time 1 second × 2 times

<Chromate treatment layer>

The chromate treatment layer is formed by the following immersion chromate treatment or electrolytic chromate treatment. That is, the chromate treatment layer was formed by the chromate immersion treatment when a sample for measuring the peel strength was prepared as follows. On the other hand, in the following preparation of a sample for measuring transmission loss, the chromate treatment layer was formed by electrolytic chromate treatment.

(Dip chromate treatment)

Chromate solution composition: 3.0g/L of K ₂ Cr ₂ O ₇ , 0.33g/L of Zn

Chromate solution pH: 3.65

Chromate liquid temperature: 55℃

(Electrolytic chromate treatment)

Chromate solution composition: 3.0g/L of K ₂ Cr ₂ O ₇ , 0.33g/L of Zn

Chromate solution pH: 3.65

Chromate liquid temperature: 55℃

Electroplating conditions: current density 2.1A/dm ² , time 1.4 seconds

(Example 2)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 15 g/L Cu and 75 g/L sulfuric acid. Except for this, the surface treatment copper foil was obtained under the same conditions as in Example 1.

(Example 3)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20g/L Cu, 100g/L sulfuric acid, and the current density was changed to 38.4A/dm ² , except that it was the same as in Example 1. The conditions to obtain the surface-treated copper foil.

(Example 4)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20 g/L Cu and 100 g/L sulfuric acid. Except for this, the surface treatment copper foil was obtained under the same conditions as in Example 1.

(Example 5)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20g/L Cu, 100g/L sulfuric acid, the plating solution temperature was changed to 35°C, and the current density was changed to 38.4A/dm ² , Otherwise, the surface-treated copper foil was obtained under the same conditions as in Example 1.

(Example 6)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20g/L of Cu, 100g/L of sulfuric acid, and the temperature of the plating solution was changed to 35°C. Other than that, the same as in Example 1 Conditions to obtain surface-treated copper foil.

(Example 7)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20g/L Cu, 100g/L sulfuric acid, the plating solution temperature was changed to 50°C, and the current density was changed to 38.4A/dm ² , Otherwise, the surface-treated copper foil was obtained under the same conditions as in Example 1.

(Example 8)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20g/L Cu, 100g/L sulfuric acid, and the plating solution temperature was changed to 50°C. Other than that, the same as in Example 1 Conditions to obtain surface-treated copper foil.

(Example 9)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 30g/L Cu, 150g/L Except that the temperature of the plating solution was changed to 35°C with sulfuric acid, the surface-treated copper foil was obtained under the same conditions as in Example 1.

(Comparative example 1)

In the formation conditions of the roughening treatment layer, except for changing the current density to 33.3 A/dm ² , the surface treatment copper foil was obtained under the same conditions as in Example 1.

(Comparative example 2)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20g/L Cu, 100g/L sulfuric acid, and the current density was changed to 33.3A/dm ² , except for this, the same as in Example 1 The conditions to obtain the surface-treated copper foil.

(Comparative example 3)

In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 40 g/L Cu and 200 g/L sulfuric acid. Except for this, the surface treatment copper foil was obtained under the same conditions as in Example 1.

The following evaluations were performed on the surface-treated copper foils obtained in the above-mentioned Examples and Comparative Examples.

<R△q, Ra, Sa, Rz, Sz, Sq, Sal, SMr1, SMr2, Spk, RSm of the surface treatment layer>

A laser microscope (LEXT OLS4000) manufactured by Olympus Co., Ltd. was used for image shooting. Furthermore, the analysis of the captured images was performed using the analysis software of the laser microscope (LEXT OLS 4100) manufactured by Olympus Co., Ltd. The measurement of R△q, Ra, Rz, and RSm is performed in accordance with JIS B0601:2013, and the measurement of Sa, Sz, Sq, Sal, SMr1, SMr2, and Spk is performed in accordance with ISO 25178. In addition, regarding these measurement results, the average value of the values measured at three arbitrary locations is used as the measurement result. Furthermore, the temperature at the time of measurement is set to 23~25°C. In addition, the main setting conditions in 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: 10nm, number of pixels of scanned data: 1024×1024)

Scanned image size [number of pixels]: 257μm wide x 258μm long [1024×1024]

(Because it is measured in the horizontal direction, the evaluation length is equivalent to 257μm)

DIC: closed

Multi-layer: closed

Laser intensity: 100

Compensation: 0

Confocal level: 0

Beam diameter reduction: 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: pre-measurement processing

Surface (tilt) correction: implemented

Recognition value of minimum height: 10% relative to the ratio of Rz

Cut-off level difference: Rmr1 20% Rmr2 80%

Relative load length rate

RMr: Cut-off level C ₀ : 1μm lower than the highest point

Cut-off level difference: lower than the cut-off level C ₀ 1μm

<Peel strength>

The 90 degree peel strength is measured in accordance with JIS C6471: 1995. Specifically, the width of the circuit (surface-treated copper foil) is set to 3mm, and the commercially available resin substrate (LCP: liquid crystal polymer resin (hydroxybenzoic acid (ester) The strength of the film (Vecstar (registered trademark) CTZ made by Kuraray Co., Ltd.; thickness 50μm)) and surface-treated copper foil when peeled off. The measurement was performed twice, and the average value was taken as the result of the peel strength. If the peel strength is 0.5 kgf/cm or more, it can be said that the adhesion between the circuit and the resin substrate is good.

Furthermore, the circuit width is adjusted by the usual subtractive etching method using copper chloride etching solution.

<Transmission loss>

The surface-treated copper foil and resin substrate (LCP: liquid crystal polymer resin (copolymer of hydroxybenzoic acid (ester) and hydroxynaphthoic acid (ester)) film (Vecstar (registered trademark) CTZ manufactured by Kuraray Co., Ltd.; thickness 50μm)) After bonding, the microwave transmission strip line is formed by etching so that the characteristic impedance becomes 50Ω, and the penetration coefficient is measured using a network analyzer N5247A manufactured by Agilent Technologies Co., Ltd. (now Keysight Technologies Co., Ltd.). The output frequency is 30GHz transmission loss. If the transmission loss is within -6.0dB/10cm, it can be said to be good.

The above evaluation results are shown in Table 1.

As shown in Table 1, the surface-treated copper foils of Examples 1 to 9 in which the RΔq of the surface treatment layer is 37-70° have higher peel strength and lower transmission loss.

On the other hand, the surface-treated copper foils of Comparative Examples 1 to 3 in which the RΔq of the surface-treated layer did not reach 37° had less transmission loss, but lower peel strength.

Furthermore, in the above-mentioned embodiment, if a heat-resistant treatment layer such as a Zn-Ni layer and/or an anti-rust treatment layer are provided, it can be expected that the heat resistance and or the resistance to rust will be improved. In this case, the heat-resistant treatment layer and/or the anti-rust treatment layer are preferably formed by smooth plating. In addition, if a silane coupling treatment layer is provided, it can be expected that the bonding strength with the resin substrate will be improved.

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 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 adhesiveness between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a circuit pattern.

Claims (16)

A surface-treated copper foil, which has a copper foil and a surface-treated layer formed on at least one side of the above-mentioned copper foil, and the root-mean-square slope RΔq of the above-mentioned surface-treated layer is 37-70°. The surface-treated copper foil according to claim 1, wherein the arithmetic average roughness Ra of the surface-treated layer is 0.25 to 0.40 μm. The surface-treated copper foil according to claim 1 or 2, wherein the arithmetic average height Sa of the surface-treated layer is 0.25 to 0.40 μm. The surface-treated copper foil according to claim 1 or 2, wherein the maximum height roughness Rz of the surface-treated layer is 2.3 to 5.1 μm. The surface-treated copper foil according to claim 1 or 2, wherein the maximum height Sz of the surface-treated layer is 4.4 to 7.4 μm. The surface-treated copper foil according to claim 1 or 2, wherein the root-mean-square height Sq of the surface-treated layer is 0.33 to 0.55 μm. The surface-treated copper foil according to claim 1 or 2, wherein the minimum autocorrelation length Sal of the surface-treated layer is 1.2 to 1.7 μm. The surface-treated copper foil according to claim 1 or 2, wherein the load area ratio SMr1 of the separated protrusion peak portion and the core portion of the surface-treated layer is 11.5 to 16.0%. The surface-treated copper foil according to claim 1 or 2, wherein the load area ratio SMr2 of the separated protrusion valley portion and the core portion of the surface-treated layer is 86.5-91.0%. The surface-treated copper foil according to claim 1 or 2, wherein the protrusion peak height Spk of the surface-treated layer is 0.41 to 1.03 μm. The surface-treated copper foil according to claim 1, wherein the average length RSm of the surface-treated layer is 3.3 to 5.2 μm. The surface-treated copper foil according to claim 1 or 2, wherein the surface-treated layer is selected from the group consisting of a roughening treatment layer, a heat-resistant treatment layer, an anti-rust treatment layer, a chromate treatment layer, and a silane coupling treatment layer More than one layer in the group. The surface-treated copper foil according to claim 1 or 2, wherein the copper foil has a roughening treatment layer, the roughening treatment layer has a Ni-Zn layer, and the Ni-Zn layer has a chromate treatment layer , The chromate treatment layer has a silane coupling treatment layer. The surface-treated copper foil according to claim 1 or 2, 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 14 and a resin substrate followed by a surface-treated layer of the 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 described in claim 15.