TWI716210B - Surface treatment copper foil, copper clad laminate and printed wiring board - Google Patents

Abstract

The present invention is a surface-treated copper foil having copper foil and a surface-treated layer formed on at least one side of the copper foil. The average length RSm of the surface treatment layer of the surface treatment copper foil is 3.3~5.2 μm. Moreover, this invention is a copper clad laminated board provided with the resin base material of the surface treatment layer of the surface-treated copper foil and this 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 conductive pattern (also called a "wiring pattern"), and using solder to connect and construct electronic parts on the conductive pattern.

In recent years, in electronic equipment such as computers and mobile terminals, with the increase in communication speed and capacity, the high frequency of telecommunications signals has continued to develop, and flexible printed wiring boards that can respond to them are required. 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 fail to read data. Therefore, it is required to reduce the loss of signal power.

The loss of signal power (transmission loss) in electronic circuits can be roughly divided into two types. One is conductor loss, that is, loss caused by copper foil, and the other is dielectric loss, that is, loss caused by resin substrate. Conductor loss due to the skin effect in the high-frequency region, has the characteristics of current flowing through the surface of the conductor, so if the surface of the copper foil is rough, 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, 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 dielectric loss depends on the type of resin base material. Therefore, it is ideal to use low-dielectric materials (such as liquid crystal polymer, low-dielectric polyimide) in circuit substrates that circulate high-frequency signals. The formed resin substrate. In addition, the loss of the dielectric body is also affected by the bonding agent between the copper foil and the resin substrate. Therefore, it is desirable to bond the copper foil and the resin substrate without using an adhesive. Therefore, it is proposed to form a surface treatment layer on at least one surface of the copper foil in order to bond between the copper foil and the resin substrate without using an adhesive. For example, in Patent Document 1, 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 is proposed. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2012-112009 A

[The problem to be solved by the invention]

The roughening treatment layer can improve the adhesion between the copper foil and the resin substrate by using the anchoring effect produced by the roughening particles. However, the skin effect may increase the conductor loss, so it is ideal Reduce the roughened particles electrodeposited on the surface of the copper foil. On the other hand, if the roughened particles electrodeposited on the surface of the copper foil are reduced, the anchoring effect generated 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 formed of low-dielectric materials such as liquid crystal polymer and low-dielectric polyimide are more difficult to bond with copper foil than conventional resin substrates. Therefore, development and improvement of the adhesion between copper foil and resin substrate are required. Sexual approach. In addition, although the silane coupling treatment layer has the effect of improving the adhesion between the copper foil and the resin substrate, depending on the type, the adhesion enhancement effect may be insufficient.

The embodiments of the present invention are made to solve the above-mentioned problems, and the 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 adhesion between a resin substrate, particularly a resin substrate suitable for high-frequency applications, and a circuit pattern. [Technical means to solve the problem]

After intensive research to solve the above problems, the inventors found that the average length RSm of the surface treatment layer of the surface treatment copper foil is closely related to the adhesion between the surface treatment copper foil and the resin substrate. The average length RSm of the surface treatment layer of the surface treatment copper foil is controlled to a specific range, and the adhesion between the surface treatment copper foil and the resin substrate can be improved, thereby completing 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 average length RSm of the surface-treated layer is 3.3-5.2 μm. In addition, an embodiment of the present invention is a copper-clad laminate comprising the above-mentioned surface-treated copper foil and a resin substrate followed by a 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. [Effects of Invention]

According to the embodiment of the present invention, it is possible 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. Furthermore, according to the embodiment of the present invention, it is possible to provide a copper-clad laminate with excellent adhesion between a resin substrate, especially 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.

Hereinafter, the more suitable embodiments of the present invention will be described in detail, but the present invention should not be limited to these interpretations, and various changes and improvements can be made based on the knowledge of the industry without departing from the scope of the spirit of the present invention. The plurality of constituent elements disclosed in this embodiment can be appropriately combined to form various inventions. 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 forming surface treatment layers on both sides of the copper foil, the types of the surface treatment layers may be the same or different.

The average length RSm of the surface treatment layer is 3.3~5.2 μm. Here, the average length RSm represents the average of the length of the contour curve elements under the reference length (ie, the average distance between the surface irregularities), and can be measured in accordance with JIS B0601:2013. The RSm of the surface treatment layer is an index indicating the density of the uneven shape of the surface treatment layer (especially the density of the roughened particles in the roughened particle layer). The smaller the RSm of the surface treatment layer, the higher the density of the uneven shape of the surface treatment layer, and it can be expected that the anchor effect will be more easily exhibited when the surface treatment copper foil is bonded to the resin substrate. However, if the RSm is too small (the density of the uneven shape of the surface treatment layer becomes very large), 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, the RSm of the surface treatment layer is controlled to be 3.3˜5.2 μm, preferably 3.3 μm or more and less than 5.0 μm.

The surface treatment layer preferably has a root mean square height Sq of 0.33˜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), which can be measured in accordance with ISO 25178. The Sq of the surface treatment layer is an index indicating the difference in the height of the protrusions on the surface of the surface treatment layer. If the Sq of the surface treatment layer is large, the difference in the height of the protrusions on the surface of the surface treatment layer is greater, and it is easier to exert an anchoring effect when the surface treatment copper foil is bonded to the resin substrate. However, if Sq is too large (the difference in height of the protrusions 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 anchoring effect and the viewpoint of quality management, the Sq of the surface treatment layer is preferably controlled to 0.33 to 0.55 μm, and more preferably to 0.40 to 0.55 μm.

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) under the reference length of the roughness curve, and can be measured in accordance with 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 is rough, so it is easy to exert the anchoring effect when the surface treatment copper foil is bonded to the resin substrate, but on the other hand, the transmission loss will be caused by 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, the Ra of the surface treatment layer is preferably controlled 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 two-dimensional parameter Ra extended to a three-dimensional parameter, which can be measured in accordance with ISO 25178. The Sa of the surface treatment layer, like Ra, is an index 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 is rough, so it is easy to exert the anchoring effect when the surface treatment copper foil is bonded to the resin substrate, but on the other hand, the transmission loss will be caused by 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, the Sa of the surface treatment layer is preferably controlled to be 0.25 to 0.40 μm, and more preferably to be controlled 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 peak height and the maximum valley depth of the profile curve under the reference length, and can be 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, the surface of the surface treatment layer has protruding irregularities, so it is easy to exert an anchoring effect when the surface-treated copper foil is bonded to the resin substrate, but on the other hand, the transmission loss will be caused by skin The effect becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, the Rz of the surface treatment layer is preferably controlled to be 2.3 to 5.1 μm, and more preferably to be controlled 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 a two-dimensional parameter Rz extended to a three-dimensional parameter, which can be measured in accordance with ISO 25178. The Sz of the surface treatment layer, like Rz, is an index indicating the presence or absence of protrusions on the surface of the surface treatment layer. If the Sz of the surface treatment layer is large, the surface of the surface treatment layer will have protruding irregularities. Therefore, it is easy to exert an anchoring effect when the surface treatment copper foil is connected to the resin substrate. However, on the other hand, the transmission loss will be caused by the skin The effect becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, the Sz of the surface treatment layer is preferably controlled to 4.4 to 7.4 μm, more preferably to 5.0 to 6.5 μm.

The surface treatment layer preferably has a minimum autocorrelation length Sal of 1.2˜1.7 μm. Here, the minimum autocorrelation length Sal represents the minimum lateral distance from the surface autocorrelation attenuation to the correlation value s (0≦s<1), which can be 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 flatter the surface of the surface treatment layer, the greater the Sal of the surface treatment layer, and the more protrusions, the smaller the Sal of the surface treatment layer. 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, more preferably to 1.3 to 1.7 μm.

The surface treatment layer preferably has a load area ratio SMr1 that separates the protruding peak portion from the core portion of 11.5 to 16.0%. Here, the load area ratio SMr1 that separates the protruding peak portion from the core portion represents the number of protruding peak portions, and can be measured in accordance with ISO 25178. If the SMr1 of the surface treatment layer is large, the surface treatment layer has many protruding peaks, so it is easy to exert an anchoring effect when the surface treatment copper foil is connected to the resin substrate. However, on the other hand, the transmission loss will be caused by the skin The effect becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, the SMr1 of the surface treatment layer is preferably controlled to 11.5 to 16.0%, and more preferably to 12.0 to 15.5 μm.

The surface treatment layer preferably has a load area ratio SMr2 that separates the protruding valley portion from the core portion of 86.5-91.0%. Here, the load area ratio SMr2 that separates the protruding valley portion from the core portion represents the number of protruding valley portions, and can be measured in accordance with ISO 25178. If the SMr2 of the surface treatment layer is large, the surface treatment layer has many protruding valleys, so it is easy to exert an anchoring effect when the surface treatment copper foil is bonded to the resin substrate. On the other hand, the transmission loss will be caused by the skin The effect 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 better to control the SMr2 of the surface treatment layer to 86.5-91.0%, more preferably to 88.0-91.0 μm.

The surface treatment layer preferably has a protrusion peak height Spk of 0.41˜1.03 μm. Here, the height of the protruding peak Spk can be measured in accordance with ISO 25178. If the Spk of the surface treatment layer is large, the height of the protruding peak of the surface treatment layer is large, so it is easy to exert an anchoring effect when the surface treatment copper foil is bonded to the resin substrate. However, on the other hand, the transmission loss will be caused by The skin effect becomes larger. Therefore, from the viewpoint of ensuring the balance between the securing of the anchoring effect and the suppression of the transmission loss, the Spk of the surface treatment layer is preferably controlled to 0.41 to 1.03 μm, and more preferably to 0.55 to 1.00 μm.

The surface treatment layer preferably has a root mean square slope RΔq of 37 to 70°. Here, the root mean square slope RΔq represents the root mean square of the local slope dz/dx under the reference length of the roughness curve, and can be measured in accordance with JIS B0601:2013. The RΔq of the surface treatment layer is an index indicating the gradient of the unevenness on the surface of the surface treatment layer. If the growth of the surface treatment layer (especially the roughened particles of the roughening treatment layer) in the z direction is large, the RΔq of the surface treatment layer will increase, and it is easy to play an anchor when the surface treatment copper foil is bonded to the resin substrate. However, on the other hand, the transmission loss will increase due to the skin effect. Therefore, from the viewpoint of ensuring the proper balance between the securing of the anchoring effect and the suppression of the transmission loss, the RΔq of the surface treatment layer is preferably controlled to 37~70°, and more preferably 45~65°.

The type of surface treatment layer is not particularly limited, and various surface treatment layers known in the technical field can be used. Examples of the surface treatment layer include a roughening treatment layer, a heat-resistant treatment layer, a rust-preventing treatment layer, a chromate treatment layer, a silane coupling treatment layer, and the like. 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. Generally, this roughening treatment is performed by performing electroplating, which is so-called burning plating. In addition, in the roughening treatment, the usual copper plating etc. may be carried out as a pretreatment, or the usual copper plating etc. to prevent the roughening particles from falling off as a final treatment. However, the "roughening treatment" in this manual "Layer" includes the layer formed by these pre-processing and final processing.

There are no particular restrictions on the roughened particles, and they 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 using simple substances or alloys of nickel, cobalt, copper, and zinc 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. Typical conditions are as follows. Furthermore, electroplating can be performed in two stages. In addition, pay attention to the following points: The following conditions are the conditions in the beaker test in which a cylindrical cathode wound with copper foil is placed in the center, and anodes are set at a fixed distance around it. Plating bath composition: 11~30 g/L Cu, 50~150 g/L sulfuric acid plating bath temperature: 25~50℃ Plating condition: current density 38.4~48.5 A/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 an anti-rust treatment layer, so a layer having both functions of the heat-resistant treatment layer and the anti-rust treatment layer can be formed 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 A layer of more than one element (metal, alloy, oxide, nitride, sulfide, etc.) from the group of iron, tantalum. Among them, the heat-resistant treatment layer and/or the anti-rust treatment layer are preferably Ni-Zn layers or Zn layers. 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 prevention effect, which is preferable.

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 when forming the heat-resistant layer (Ni-Zn layer) using a general electroplating apparatus 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

In particular, as long as the Ni-Zn layer is formed under the following conditions, the conductor loss can be reduced without greatly reducing the heat resistance effect and the rust prevention effect, which is preferable. Plating bath composition: 23.5 g/L Ni, 4.5 g/L Zn Plating bath pH: 3.6 Plating bath temperature: 40℃ Electroplating conditions: current density 1.1 A/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 using a liquid containing chromic anhydride, chromic acid, dichromic acid, chromate, or dichromate. The chromate treatment layer may contain cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, titanium and other elements (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 treated with treatment liquid containing chromic anhydride or potassium dichromate and zinc Processing layer, etc.

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: 1~10 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。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。 作為代表的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，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 technical field. Here, in this specification, the "silane coupling treatment layer" means a layer formed using a silane coupling agent. 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, vinyl-based silane coupling agents, and imidazole-based Silane coupling agent, three

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

There is no restriction|limiting in particular as a copper foil, It may be either electrolytic copper foil or rolled copper foil. Electrolytic copper foil is generally manufactured by electrolysis of copper from a copper sulfate plating bath to a drum of titanium or stainless steel. It has a flat S surface (polished surface) formed on the drum side and formed on the opposite side of the S surface The M side (matte side). Generally speaking, the M surface of the electrolytic copper foil has unevenness, so the surface treatment layer is formed on the M surface of the electrolytic copper foil, and the surface treatment layer is bonded to the resin substrate, thereby improving the surface treatment layer and the resin substrate. Subsequent.

The material of copper foil is not particularly limited. When the copper foil is rolled copper foil, refined copper (JIS H3100 alloy number C1100), oxygen-free copper (JIS H3100), which is usually used as circuit pattern 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, Mg, etc., and Carson-based copper alloys added with Ni, Si, etc. can also be used. Furthermore, in this specification, the concept of "copper foil" also includes 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 ~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 RΔq, Ra, Sa, Rz, Sz, Sq, Sal, SMr1, SMr2, Spk, and RSm of the surface treatment layer can be adjusted by adjusting the formation conditions of the surface treatment layer, especially the roughening treatment layer formation conditions, etc. control.

The copper clad laminated board can be manufactured by adhering the surface treatment layer of the surface-treated copper foil and the resin base material. The resin substrate is not particularly limited, and those known in the 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 substrate epoxy resin, polyester film, polyimide film, liquid crystal polymer, fluororesin, etc.

There is no particular limitation as to the bonding method of the surface-treated copper foil and the resin substrate, 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 thermocompression-bond.

The copper clad laminates manufactured as described above can be used for the manufacture of printed wiring boards. The manufacturing method of the printed wiring board is not particularly limited, and known methods 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 subtractive use.

In the case of manufacturing a printed wiring board by a subtractive method, it is preferably performed as follows. First, by coating a resist on the surface of the copper foil surface treated with a copper clad laminate, exposing and developing, a specific resist pattern is formed. Secondly, the surface-treated copper foil of the part (unused part) where the resist pattern is not formed is removed by etching. Finally, the resist 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 performed according to the conditions known in the technical field. [Example]

Hereinafter, the embodiments of the present invention will be explained in detail through examples, but the present invention is not limited by these examples.

(Example 1) Prepare 12 μm thick rolled copper foil (made by JX Metal Co., HA-V2 foil). After degreasing and pickling one side, a roughening treatment layer and a chromate treatment layer are sequentially formed as the surface treatment layer. , Obtain surface treatment copper foil. The conditions for forming each layer are as follows.

<Roughening treatment layer> A cylindrical cathode wound with copper foil is arranged in the center, and anodes are installed around it at a fixed interval to form a roughening treatment layer. The plating conditions are as follows. Plating bath composition: 11 g/L Cu, 50 g/L sulfuric acid Plating bath temperature: 25℃ Electroplating conditions: current density 48.5 A/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, when a sample for measuring the peel strength described later is produced, a chromate treatment layer is formed by immersion chromate treatment. On the other hand, when a sample for measuring transmission loss described later is produced, a chromate treatment layer is formed by electrolytic chromate treatment. (Dip chromate treatment) Chromate solution composition: 3.0 g/L of K ₂ Cr ₂ O ₇ , 0.33 g/L of Zn Chromate solution pH: 3.65 Chromate solution temperature: 55℃ (electrolytic chromic acid Salt treatment) Chromate solution composition: 3.0 g/L of K ₂ Cr ₂ O ₇ , 0.33 g/L of Zn Chromate solution pH: 3.65 Chromate solution temperature: 55 ℃ Electroplating conditions: current density 2.1 A/ 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 that the same conditions as in Example 1 were used to obtain a surface-treated copper foil.

(Example 3) In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 20 g/L Cu, 100 g/L sulfuric acid, and the current density was changed to 38.4 A/dm ² . , The surface-treated copper foil was obtained under the same conditions as in Example 1.

(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 treated 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 20 g/L Cu and 100 g/L sulfuric acid, the temperature of the plating solution was changed to 35°C, and the current density was changed to Except for 38.4 A/dm ² , 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 20 g/L Cu, 100 g/L sulfuric acid, and the plating solution temperature was changed to 35°C. Otherwise, the same as in Example 1 The surface treated copper foil is obtained under the same conditions.

(Example 7) 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, the temperature of the plating solution was changed to 50°C, and the current density was changed to Except for 38.4 A/dm ² , 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 20 g/L Cu, 100 g/L sulfuric acid, and the plating solution temperature was changed to 50°C. Otherwise, the same as in Example 1 The surface treated copper foil is obtained under the same conditions.

(Example 9) In the formation conditions of the roughening treatment layer, the composition of the plating solution was changed to 30 g/L Cu, 150 g/L sulfuric acid, and the plating solution temperature was changed to 35°C. Other than that, follow the example 1 Obtain surface treated copper foil under the same conditions.

(Comparative Example 1) In the formation conditions of the roughening treatment layer, except that the current density was changed 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 20 g/L Cu, 100 g/L sulfuric acid, and the current density was changed to 33.3 A/dm ² . , The surface-treated copper foil was obtained under the same conditions as in Example 1.

(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 evaluation was performed on the surface-treated copper foil obtained in the above-mentioned Examples and Comparative Examples. <RΔq, Ra, Sa, Rz, Sz, Sq, Sal, SMr1, SMr2, Spk, RSm of the surface treatment layer> Use the laser microscope (LEXT OLS4000) manufactured by Olympus Co., Ltd. to take the image. Furthermore, the analysis of the captured image is performed using the analysis software of the laser microscope (LEXT OLS 4100) manufactured by Olympus Co., Ltd. The measurement of RΔq, 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, these measurement results are the average of the values measured at any three locations 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: FN18) Optical zoom magnification: 1 times Scanning mode: XYZ high precision (Height resolution: 10 nm, number of pixels for reading data: 1024×1024) Reading image size [number of pixels]: 257 μm horizontal × 258 μm vertical [1024×1024] (As measured in horizontal, it is evaluated Length is equivalent to 257 μm) DIC: Off Multilayer: Off Laser intensity: 100 Offset: 0 Confocal level: 0 Beam diameter reduction: Off Image average: 1 time Noise reduction: Bright spot correction: On optical noise filter : Open cut-off: None (none of λc, λs, λf) Filter: Gaussian filter Noise removal: Measurement of pre-processing surface (tilt) correction: Implementation of the minimum height of the recognition value: relative to the ratio of Rz 10% cut-off level Poor: Rmr1 20% Rmr2 80% Relative load length ratio RMr: Cut-off level C ₀ : 1 μm below the highest point Cut-off level difference: 1 μm below the cut-off level C ₀

＜Peel strength＞ The 90 degree peel strength is measured according to JIS C6471:1995. Specifically, the width of the circuit (surface-treated copper foil) is set to 3 mm, and the measurement is made by measuring a commercially available resin substrate (LCP: liquid crystal polymer resin (hydroxybenzoic acid) at a speed of 50 mm/min at an angle of 90 degrees). (Ester) and hydroxynaphthoic acid (ester) copolymer) film (Vecstar (registered trademark) CTZ manufactured by Kuraray Co., Ltd.; thickness 50 μm)) and the strength when peeling off the surface-treated copper foil. The measurement was performed twice, and the average value was used 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.; thick 50 μm)) After bonding, the microstrip line is formed by etching so that the characteristic impedance becomes 50 Ω, and the transmission coefficient is measured using the network analyzer N5247A manufactured by Agilent Technologies Co., Ltd. (now Keysight Technology Co., Ltd.) , Find the transmission loss at a frequency of 30 GHz. If the transmission loss is within -6.0 dB/10 cm, it is considered good.

Table 1 shows the above evaluation results.

[Table 1] Example Comparative example 1 2 3 4 5 6 7 8 9 1 2 3 RSm[μm] 3.3 3.3 4.3 4.8 3.8 3.6 3.5 4.0 5.2 5.6 6.5 10.4 Sq[μm] 0.51 0.49 0.38 0.54 0.40 0.54 0.39 0.48 0.34 0.32 0.24 0.21 Ra[μm] 0.40 0.36 0.30 0.39 0.29 0.34 0.27 0.34 0.25 0.26 0.20 0.17 Sa[μm] 0.38 0.37 0.28 0.38 0.30 0.39 0.29 0.36 0.25 0.25 0.18 0.16 Rz[μm] 3.1 2.8 2.7 5.0 2.9 3.4 2.6 3.2 2.3 2.3 1.6 1.4 Sz[μm] 6.2 4.4 5.5 7.2 5.1 6.4 4.8 4.8 4.6 4.4 3.1 2.8 Sal[μm] 1.3 1.3 1.7 1.3 1.7 1.3 1.5 1.5 1.6 1.8 2.2 2.4 SMr1[%] 14.6 15.9 12.1 15.8 12.2 15.2 14.2 13.8 11.5 10.2 9.2 7.6 SMr2[%] 89.6 89.8 87.8 89.6 88.5 90.4 88.8 90.9 86.6 85.8 83.7 81.6 Spk[μm] 0.84 0.77 0.53 1.03 0.57 0.96 0.52 0.72 0.41 0.38 0.23 0.14 RΔq[°] 67 65 44 70 50 60 45 54 37 34 twenty two 14 Peel strength [Kgf/cm] 0.58 0.72 0.53 0.73 1.14 1.16 0.83 0.79 0.56 0.36 0.29 0.21 Transmission loss [dB/10 cm] -4.93 -4.91 -4.94 -5.02 -4.95 -4.96 -4.82 -4.96 -4.98 -4.84 -4.90 -5.10

As shown in Table 1, the surface-treated copper foils of Examples 1-9 in which the RSm of the surface treatment layer is 3.3-5.2 μm have high peel strength and low transmission loss. On the other hand, the surface-treated copper foils of Comparative Examples 1 to 3 in which the RSm of the surface-treated layer exceeds 5.2 μm have low transmission loss, but low 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 is provided, it is 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 is 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 that 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 with excellent adhesion between a resin substrate, especially 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.

no

no

Claims (15)

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, the average length RSm of the surface treatment layer is 3.3~5.2μm, and the arithmetic average roughness Ra of the surface treatment layer is 0.25 ~0.40μm. The surface-treated copper foil according to claim 1, wherein the root-mean-square height Sq of the surface-treated layer is 0.33~0.55 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 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 that separates the protruding 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 that separates the protruding 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 or 2, wherein the root-mean-square slope RΔq of the surface-treated layer is 37 to 70°. The surface-treated copper foil according to claim 1 or 2, wherein the surface-treated layer has There are more than one layer 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. 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 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 13 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 surface-treated copper foil of the copper-clad laminated board described in claim 14.