WO2013065831A1

WO2013065831A1 - Copper foil for printed circuit

Info

Publication number: WO2013065831A1
Application number: PCT/JP2012/078509
Authority: WO
Inventors: 新井　英太; 敦史三木
Original assignee: Jx日鉱日石金属株式会社
Priority date: 2011-11-04
Filing date: 2012-11-02
Publication date: 2013-05-10
Also published as: TW201509246A; TW201325336A; TWI590719B; JP2013096003A; JP5985812B2

Abstract

Provided is a roughened copper foil that has a black surface and good etching properties. This copper foil for a printed circuit has a non-black roughened layer and a nickel-tungsten alloy plating layer formed in this order on at least one of the surfaces of the copper foil, and the amount of nickel in the nickel-tungsten alloy plating layer is 2,000 µg/dm² or more.

Description

Copper foil for printed circuit

The present invention relates to a copper foil for a printed circuit, for example, a copper foil for a printed circuit suitable for a fine pattern printed circuit and a magnetic head FPC (Flexible Circuit).

Copper and copper alloy foils (hereinafter referred to as copper foils) have greatly contributed to the development of electrical and electronic industries, and are indispensable particularly as printed circuit materials. Copper foil for printed circuit is generally used to produce a copper-clad laminate by laminating and bonding to an insulating substrate such as a synthetic resin board or film through an adhesive or under high temperature and high pressure without using an adhesive. In order to form a circuit, a necessary circuit is printed through a resist coating and exposure process, and then an etching process for removing unnecessary portions is performed.
Finally, the required elements are soldered to form various printed circuit boards for the electronic device.

In copper-clad laminates, the adhesion between the insulating substrate and the conductive material is one of the important characteristics. In order to improve the adhesion to the insulating substrate, a surface treatment called roughening treatment that forms irregularities on the copper foil surface is performed. It is generally done. For example, by using a copper sulfate acidic plating bath on the M surface (rough surface) of the electrolytic copper foil, a large number of copper is electrodeposited in a dendritic or small spherical shape to form fine irregularities, and the adhesion is improved by the anchoring effect. There is.

Further, as a technique developed from the roughening treatment by copper electrodeposition grains, for example, as described in JP-A-4-96395 (Patent Document 1) and JP-A-10-18075 (Patent Document 2), A technique is known in which the surface of a copper foil is subjected to a roughening treatment by copper-cobalt-nickel alloy plating.

Japanese Patent Laid-Open No. 4-96395 JP-A-10-18075

Another important characteristic required for printed circuit copper foil is that it is black. First, black has the advantage of high alignment accuracy and high heat absorption. In the process of creating a printed circuit board, components such as an IC, a resistor, and a capacitor are mounted in an automatic process, and chip mounting is performed while reading a circuit with a sensor. At this time, the roughened surface may be aligned through a film such as Kapton. This also applies to positioning when forming a through hole. And the closer the processing surface is to black, the better the light absorption, and the higher the positioning accuracy.
Secondly, when a printed circuit board is manufactured, the copper foil and the insulating substrate are often cured and bonded while applying heat. At this time, when heating is performed by using long waves such as far infrared rays and infrared rays, the heating efficiency is improved when the color tone of the treated surface is black.

This point is inconvenient because the surface is reddish in the traditional roughening process using copper electrodeposited grains. Further, although the black surface is obtained by the roughening treatment by the copper-cobalt-nickel alloy plating described in Patent Document 1 or Patent Document 2, it is composed of the copper-cobalt-nickel alloy plating formed on the surface of the copper foil. Since the shape of the roughened particles is dendritic, it peels off from the upper part or the root of the tree branch, and there is a problem generally called a powder-off phenomenon. This powder-off phenomenon is a troublesome problem, and the roughened layer of copper-cobalt-nickel alloy plating is characterized by excellent adhesion to the resin layer and excellent heat resistance. Nevertheless, the particles easily fall off due to an external force, and peeling due to “rubbing” during processing, contamination of the roll with peeling powder, and etching residue due to peeling powder are generated.

Furthermore, from the viewpoint of fine pattern formation, it is also required that there is no etching residue after etching.

Therefore, the object of the present invention is to provide a roughened copper foil having a black surface and good etching properties, and preferably to provide a roughened copper foil with further improved powder-off problem. is there. Moreover, the further subject of this invention is providing the copper clad laminated board provided with such a roughening process copper foil.

In one aspect of the present invention, a non-black roughening layer and a nickel-tungsten alloy plating layer are formed in this order on at least one surface of the copper foil, and the nickel of the nickel-tungsten alloy plating layer It is a copper foil for printed circuits whose amount is 2000 μg / dm ² or more.

In one embodiment of the copper foil for printed circuit according to the present invention, the nickel amount of the nickel-tungsten alloy plating layer is 2000 to 5000 μg / dm ² .

In another embodiment of the copper foil for printed circuit according to the present invention, a heat-resistant layer is formed on the nickel-tungsten alloy plating layer.

In yet another embodiment of the copper foil for printed circuits according to the present invention, on the nickel-tungsten alloy plating layer or on the heat-resistant layer formed on the nickel-tungsten alloy plating layer, A rust prevention layer is formed.

In still another embodiment of the copper foil for printed circuit according to the present invention, after the roughening layer forms a primary particle layer of copper, a copper-cobalt-nickel alloy is formed on the primary particle layer. The secondary particle layer is formed.

In still another embodiment of the copper foil for printed circuit according to the present invention, the primary particle layer of the copper has an average particle diameter of 0.25 to 0.45 μm, and is a secondary made of a copper-cobalt-nickel alloy. The average particle size of the particle layer is 0.05 to 0.25 μm.

In yet another embodiment of the copper foil for printed circuit according to the present invention, the primary particle layer and the secondary particle layer are electroplated layers.

In another aspect, the present invention is a copper clad laminate provided with the printed circuit copper foil according to the present invention.

In yet another aspect, the present invention is a printed circuit board made of the copper clad laminate according to the present invention.

According to the present invention, it is possible to provide a roughened copper foil that has a black surface and good etching properties, and preferably provides a roughened copper foil that further improves the problem of powder falling. be able to.

It is a conceptual explanatory view showing a state of powder falling when a roughening treatment comprising copper-cobalt-nickel alloy plating is performed on a conventional copper foil. FIG. 3 is a conceptual explanatory diagram of a roughening treatment layer formed by previously forming a primary particle layer of copper on a copper foil and forming a secondary particle layer made of copper-cobalt-nickel alloy plating on the primary particle layer. It is the microscope picture of the surface at the time of performing the roughening process which consists of copper-cobalt-nickel alloy plating on copper foil. FIG. 5 is a photomicrograph of a copper foil treated surface layer without powder falling, in which a primary particle layer is formed in advance on a copper foil, and a secondary particle layer made of copper-cobalt-nickel alloy plating is formed on the primary particle layer. .

In one embodiment of the copper foil for printed circuit according to the present invention, a roughening treatment layer and a nickel-tungsten alloy plating layer are formed in this order on at least one surface of the copper foil. For example, a black surface can be obtained by forming a nickel-tungsten alloy plating layer on a roughened layer that is not black.

<Roughening treatment layer>
The copper foil used in the present invention may be either an electrolytic copper foil or a rolled copper foil. In general, the surface of the copper foil that adheres to an insulating substrate such as a resin, that is, the roughened surface, is coated with a “detergent” on the surface of the copper foil after degreasing for the purpose of improving the peel strength of the copper foil after lamination. A roughening treatment is performed for electrodeposition in the form of a hump. Although the M surface of the electrolytic copper foil has irregularities at the time of manufacture, the irregularities are further increased by enhancing the convex portions of the electrolytic copper foil by roughening treatment.

The processing contents may be somewhat different between rolled copper foil and electrolytic copper foil. In the present invention, including such pretreatment and finishing treatment, a known treatment related to copper foil roughening is included as necessary, and is referred to as “roughening treatment”.

Examples of the roughening treatment include a method of forming an electrodeposited copper particle layer on the surface of the copper foil. A preferred method for increasing the peel strength is a method of forming a copper-cobalt-nickel alloy plating layer on the surface of the copper foil. However, if the copper-cobalt-nickel alloy plating layer is used alone, the problem of powder falling remains. Therefore, the present inventor has found that a method of forming an electrodeposited copper particle layer as a primary particle layer and forming a secondary particle layer of copper-cobalt-nickel alloy plating thereon is preferable. According to this preferred method, peeling due to “rubbing” during processing, dirt on the roll due to peeling powder, etching residue due to peeling powder can be eliminated, that is, a phenomenon called powder falling and processing unevenness can be suppressed, and peel strength can be suppressed. The copper foil for printed circuits which can improve heat resistance and can improve heat resistance can be obtained.

A roughening treatment layer obtained by forming an electrodeposited copper particle layer as a primary particle layer and forming a secondary particle layer of copper-cobalt-nickel alloy plating thereon will be described in detail.
If the copper-cobalt-nickel alloy plating layer is simply formed on the copper foil, it becomes dendritic, and thus the problem of powder falling occurs as described above.
FIG. 3 shows a photomicrograph of the surface of the copper foil in which a copper-cobalt-nickel alloy plating layer is formed on the copper foil. As shown in FIG. 3, fine particles developed in a dendritic shape can be seen. In general, the fine particles developed in a dendritic shape shown in FIG. 3 are produced at a high current density.
When processed at such a high current density, particle nucleation during initial electrodeposition is suppressed, and new particle nuclei are formed at the tip of the particle. Will grow.

FIG. 1 is a conceptual explanatory diagram showing the state of powder falling when a copper-cobalt-nickel alloy plating layer as shown in FIG. 3 is formed. The cause of this powder fall is that fine particles are formed in a dendritic shape on the copper foil as described above. However, the dendritic particles are easily broken by an external force and fall off from the root. The fine dendritic particles cause peeling due to “rubbing” during the process, contamination of the roll with peeling powder, and etching residue due to peeling powder.

On the other hand, in the case of a roughened layer obtained by forming an electrodeposited copper particle layer as a primary particle layer and forming a secondary particle layer of copper-cobalt-nickel alloy plating thereon, as shown in FIG. Since the secondary particle layer having a smaller particle diameter than this is formed on the large primary particle layer, it is possible to ensure both peel strength and prevention of powder falling. FIG. 4 shows a micrograph in this case. From the viewpoint of preventing powder falling, it is desirable that the average particle size of the primary particle layer is larger than the average particle size of the secondary particle layer. The primary particle layer has an average particle size of 0.25 to 0.45 μm, and the secondary particle layer made of a copper-cobalt-nickel alloy has an average particle size of 0.05 to 0.25 μm, typically 0. 1 to 0.25 μm is the optimum condition for preventing powder falling, as is apparent from the examples shown below.
The primary particle layer and the secondary particle layer are formed by an electroplating layer. The secondary particles are characterized by one or more dendritic particles grown on the primary particles.
As described above, the average particle size of the secondary particle layer is as small as 0.05 to 0.25 μm, but this particle size can also be called the particle height. That is, it can be said that one of the features of the present invention is that the height of the secondary particles is suppressed and the separation (powder off) of the particles is suppressed.

The copper foil for a printed circuit having the roughened layer composed of the primary particle layer and the secondary particle layer formed on the surface thereof has an adhesive strength of 0.80 kg / cm or more with the insulating substrate, and further has an adhesive strength of 0. .90 kg / cm or more can be achieved.

(Copper primary particle plating conditions)
An example of the plating conditions for the primary particles of copper is as follows.
In addition, this plating condition shows a suitable example to the last, and the average particle diameter formed on copper foil plays the role of powder omission prevention in the primary particle of copper. Therefore, as long as the average particle diameter falls within the scope of the present invention, the plating conditions other than those indicated below are not disturbed. The present invention includes these.
Liquid composition: Copper 10-20 g / L, sulfuric acid 50-100 g / L
Liquid temperature: 25-50 ° C
Current density: 1 to 58 A / dm ²
Coulomb amount: 4 to 81 As / dm ²

(Plating conditions for secondary particles)
As described above, this plating condition is merely a suitable example, the secondary particles are formed on the primary particles, and the average particle diameter plays a role in preventing powder falling. is there. Therefore, as long as the average particle diameter falls within the scope of the present invention, the plating conditions other than those indicated below are not disturbed. The present invention includes these.
Liquid composition: Copper 10-20 g / L, Nickel 5-15 g / L, Cobalt 5-15 g / L
pH: 2-3
Liquid temperature: 30-50 ° C
Current density: 24 to 50 A / dm ²
Coulomb amount: 34 to 48 As / dm ²

When the Ni adhesion amount is less than 50 μg / dm ² , the heat resistance deteriorates. On the other hand, when the Ni adhesion amount exceeds 500 μg / dm ² , the etching property is lowered. That is, although it is not at a level where etching remains and etching cannot be performed, it becomes difficult to form a fine pattern. Preferred Co deposition amount is 500 ~ 2000μg / dm ^2, and preferably nickel coating weight is 50 ~ 300μg / dm ^2.
From the above, copper - cobalt - deposition of nickel alloy plating, it may be desirable is 10 ~ 30mg / dm ² of copper -100 ~ 3000μg / dm ² of cobalt -50 ~ 500μg / dm ² of nickel. Each adhesion amount of the ternary alloy layer is a desirable condition, and a range exceeding this amount is not denied.

<Blackening layer>
A nickel-tungsten alloy plating layer is formed on the roughening treatment layer and contributes to blackening of the copper foil surface. For example, the roughening treatment layer composed of the primary particle layer made of copper and the secondary particle layer made of a copper-cobalt-nickel alloy is gray. However, a black color can be obtained by forming a nickel-tungsten alloy layer on the surface of the roughened layer. The reason why the binary alloy plating of nickel and tungsten is used is that the blackening effect can be obtained by nickel and the etching property can be secured by tungsten. The nickel - tungsten alloy plating layer is preferably from the viewpoint of blackening and the adhesion amount of nickel 2000 [mu] g / dm ² or more, and more preferably, 3000μg / dm ² or more. The nickel-tungsten alloy plating layer does not need to have an upper limit for the amount of nickel deposited from the viewpoint of blackening, but the economy is reduced even if the amount of deposited is excessively increased. For example, 15000 μg / dm ² or less, Alternatively 10000 / dm ² or less, or 8000μg / dm ² or less, or may be a 7000μg / dm ² or less. Also, nickel - if tungsten alloy plating layer deposition amount of nickel is too large, because the peel strength begins to decrease, it is preferable to be 5500μg / dm ² or less, and more preferably, 5000 [mu] g / dm ² or less. Tungsten may be present in the alloy plating layer.

(Plating conditions for forming the blackened layer)
Typical plating bath compositions and plating conditions are as follows.
Liquid composition: nickel 10-40 g / L, tungsten 10-30 mg / L
pH: 3-4
Liquid temperature: 35-45 ° C
Current density: 2 to 3 A / dm ²
Coulomb amount: 15-25 As / dm ²

<Heat resistant layer>
A heat-resistant layer, particularly a zinc-nickel alloy plated layer may be formed on the nickel-tungsten alloy plated layer. The processing performed in the manufacturing process of the printed circuit becomes much higher, and there is heat generation during use of the device after it has become a product. For example, in a so-called two-layer material in which a copper foil is bonded to a resin by thermocompression bonding, the resin receives heat of 300 ° C. or higher. Even in such a situation, it is necessary to prevent a decrease in bonding force between the copper foil and the resin base material, and this zinc-nickel alloy plating is effective.

The total amount of the zinc-nickel alloy plating layer is preferably 150 to 500 μg / dm ² and the nickel ratio is preferably 16 to 40% by mass. As a result, it has a role as a heat-resistant rust-proof layer and suppresses penetration of an etching agent used in soft etching (eg, etching solution of H ₂ SO ₄ : 10 wt%, H ₂ O ₂ : 2 wt%), It can have the effect that the weakening of the joint strength of the circuit can be prevented due to corrosion. Zinc - The total amount is less than 150 [mu] g / dm ² of nickel alloy plating layer, it is difficult to play a role as a heat-resistant layer resistant force is reduced, when the total amount is more than 500 [mu] g / dm ^2, the hydrochloric acid resistance will deteriorate Tend. Moreover, if the lower limit of the nickel ratio in the alloy layer is less than 16% by mass, the amount of penetration at the time of soft etching exceeds 9 μm, which is not preferable. The upper limit value of 40% by mass of the nickel ratio is a technical limit value at which a zinc-nickel alloy plating layer can be formed.

(Plating conditions for forming a heat-resistant layer)
Typical plating bath compositions and plating conditions are as follows.
Liquid composition: Nickel 2-30 g / L, Zinc 2-30 g / L
pH: 3-4
Liquid temperature: 30-50 ° C
Current density: 1 to 2 A / dm ²
Coulomb amount: 1 to ^{2 As} / dm ²

<Rust prevention layer>
Further, a rust prevention layer, particularly a rust prevention layer of a chromate layer may be formed on the nickel-tungsten alloy plating layer or a heat-resistant layer formed on the nickel-tungsten alloy plating layer. . In the present invention, a preferable antirust treatment is a coating treatment of chromium oxide alone or a mixture coating treatment of chromium oxide and zinc / zinc oxide. Chromium oxide and zinc / zinc oxide mixture film treatment is a method of forming zinc or zinc oxide comprising zinc oxide and chromium oxide by electroplating using a plating bath containing zinc salt or zinc oxide and chromate. It is the process which coat | covers the antirust layer of a chromium group mixture.

As the plating bath, typically, at least one kind of dichromate such as K ₂ Cr ₂ O ₇ and Na ₂ Cr ₂ O ₇ and CrO ₃ and a water-soluble zinc salt such as ZnO 2, ZnSO ₄ · 7H are used. A mixed aqueous solution of at least one kind of ₂ O and an alkali hydroxide is used. A typical plating bath composition and electrolysis conditions are as follows. In the following, conditions for the immersion chromate treatment are shown, but electrolytic chromate treatment may be used.

(Plating conditions for forming a rust prevention layer)
Liquid composition: potassium dichromate 1-10 g / L, zinc 0-5 g / L
pH: 3-4
Liquid temperature: 50-60 ° C
Current density: 0-2A / dm ² (for immersion chromate treatment)
Coulomb amount: 0 to ^{2 As} / dm ² (for immersion chromate treatment)

<Silane treatment>
Finally, if necessary, a silane treatment for applying a silane coupling agent to at least the roughened surface on the rust-preventing layer may be performed mainly for the purpose of improving the adhesive force between the copper foil and the resin substrate. Examples of the silane coupling agent used for the silane treatment include olefin silane, epoxy silane, acrylic silane, amino silane, and mercapto silane, which can be appropriately selected and used. .
The application method may be any of spraying a silane coupling agent solution by spraying, coating with a coater, dipping, pouring and the like. For example, Japanese Patent Publication No. 60-15654 describes that the adhesion between a copper foil and a resin substrate is improved by subjecting the rough surface of the copper foil to a chromate treatment followed by a silane coupling agent treatment. . Refer to this for details. Thereafter, if necessary, an annealing treatment may be performed for the purpose of improving the ductility of the copper foil.

The copper foil thus obtained has excellent heat resistance peel strength, oxidation resistance and hydrochloric acid resistance. In addition, a printed circuit having a pitch of 150 μm or less can be etched with a CuCl ₂ etching solution, and alkali etching can be performed. In addition, penetration into the circuit edge portion during soft etching can be suppressed.
As the soft etching solution, an aqueous solution of H ₂ SO ₄ : 10 wt% and H ₂ O ₂ : 2 wt% can be used. Processing time and temperature can be adjusted arbitrarily.
As the alkaline etching solution, for example, NH ₄ OH: 6 mol / liter, NH ₄ Cl: 5 mol / liter, CuCl ₂ : 2 mol / liter (temperature: 50 ° C.) and the like are known.

Hereinafter, description will be made based on examples and comparative examples. In addition, a present Example is an example to the last, and is not restrict | limited only to this example. That is, it includes other aspects or modifications included in the present invention. In addition, standard rolled copper foil TPC was used for the raw foil of the following examples.

Example 1
A primary particle layer (Cu) and a secondary particle layer (copper-cobalt-nickel alloy plating) were formed on the rolled copper foil under the conditions shown below. As a result, the primary particle system was 0.40 μm, and the secondary particle size was 0.15 μm. The average particle diameter of the primary particle layer and the secondary particle layer was measured from the SEM image using a cutting method. The average particle diameter of the primary particle layer was measured before forming the secondary particle layer.
The bath composition and plating conditions used are as follows.
[Bath composition and plating conditions]

(A) Formation of primary particle layer (Cu plating)
Liquid composition: Copper 15g / L, sulfuric acid 75g / L
Liquid temperature: 35 ° C
Current density: 2 to 58 A / dm ²
Coulomb amount: 8 to 81 As / dm ²
(B) Formation of secondary particle layer (Cu—Co—Ni alloy plating)
Liquid composition: Copper 15g / L, nickel 8g / L, cobalt 8g / L
pH: 2
Liquid temperature: 40 ° C
Current density: 24-31 A / dm ²
Coulomb amount: 34 to 44 As / dm ²

Next, a nickel-tungsten alloy plating layer was further formed on the secondary particle layer (after the roughening treatment) under the following conditions.
(Plating conditions for forming nickel-tungsten alloy plating layer)
Liquid composition: nickel 25 g / L, tungsten 20 mg / L
pH: 3.6
Liquid temperature: 40 ° C
The current density and coulomb amount are shown in Table 1.
The results are shown in Table 1. In the case where the nickel content of the nickel-tungsten alloy plating layer was 2000 μg / dm ² or more, a black color was obtained and the etching property was good.
When the nickel plating layer was formed on the secondary particle layer under the above conditions as a liquid composition not containing tungsten (No. A), it was black, but compared with the case where the nickel-tungsten alloy plating layer was formed. As a result, the etching property was inferior.

-Determination of whether it was black was performed using the color sample.
Peel strength was measured with a FR-4 substrate 10 mm circuit test piece.
-The amount of Ni deposited on the nickel-tungsten alloy plating layer was measured by ICP of the plating layer solution.
・ Evaluation of powder omission was performed by the tape transfer method. ◎ indicates that there is no transfer of rough particles on the tape, and ○ indicates that there is local, coarse transfer of coarse particles. The case where the transfer was observed (when it was slight, the entire surface) was marked with x.
-Etching property was evaluated by the presence or absence of residue when dissolved in an alkaline etching solution.

(Example 2)
Next, a primary particle layer (Cu) and a secondary particle layer (copper-cobalt-nickel alloy plating) were formed under the same conditions as in Example 1. Further, as shown in Table 2, nickel-tungsten alloy plating layers were formed by changing the current density and the amount of coulomb.
The results are shown in Table 2. In an example where the nickel adhesion amount of the nickel-tungsten alloy plating layer exceeds 5000 μg / dm ² , the peel strength is reduced.

Example 3
A primary particle layer (Cu) and a secondary particle layer (copper-cobalt-nickel alloy plating) were formed on the rolled copper foil under the conditions shown below. The bath composition and plating conditions used were as follows, and the primary particle current conditions and secondary particle current conditions are shown in Table 3. However, no. 14 (Cu layer), No. 14 15 (copper-cobalt-nickel alloy plating layer) is a reference example of a conventional roughening treatment.

[Bath composition and plating conditions]
(A) Formation of primary particle layer (Cu plating)
Liquid composition: Copper 15g / L, sulfuric acid 75g / L
Liquid temperature: 35 ° C
(B) Formation of secondary particle layer (Cu—Co—Ni alloy plating)
Liquid composition: Copper 15g / L, nickel 8g / L, cobalt 8g / L
pH: 2
Liquid temperature: 40 ° C

A nickel-tungsten alloy plating layer on the secondary particle layer (after the roughening treatment) was formed under the following conditions.
(Plating conditions for forming nickel-tungsten alloy plating layer)
Liquid composition: nickel 25 g / L, tungsten 20 mg / L
pH: 3.6
Liquid temperature: 40 ° C
Current density: 2 A / dm ²
Coulomb amount: 20 As / dm ²
In addition, No. For 14, 15, and 16, not a nickel-tungsten alloy plating layer but a Co—Ni alloy plating layer was formed.
The results are shown in Table 3. A black surface can be obtained by forming a nickel-tungsten alloy plating layer. On the other hand, No. 1 having a Co—Ni alloy plating layer. 16 had a gray surface. Moreover, the secondary particle layer is too large. Nos. 17, 18, and 19 are not preferable because they fall off.

As described above, when forming a secondary particle layer (roughening treatment) composed of copper-cobalt-nickel alloy plating, the roughened particles formed in a dendritic shape peel off from the surface of the copper foil, It has an excellent effect of being able to suppress the so-called phenomenon.

Claims

A non-black roughening layer and a nickel-tungsten alloy plating layer are formed in this order on at least one surface of the copper foil, and the nickel amount of the nickel-tungsten alloy plating layer is 2000 μg / dm 2 or more. A copper foil for printed circuit.
Said nickel - printed circuit copper foil according to claim 1, wherein the nickel content is 2000 ~ 5000μg / dm 2 of the tungsten alloy plating layer.
3. The copper foil for printed circuit according to claim 1, wherein a heat-resistant layer is formed on the nickel-tungsten alloy plating layer.
The rust preventive layer is formed on the nickel-tungsten alloy plating layer or on the heat-resistant layer formed on the nickel-tungsten alloy plating layer. Copper foil for printed circuits.
5. The roughening treatment layer is obtained by forming a primary particle layer of copper and then forming a secondary particle layer of a copper-cobalt-nickel alloy on the primary particle layer. The copper foil for printed circuits of description.
The average particle size of the primary particle layer of copper is 0.25 to 0.45 μm, and the average particle size of the secondary particle layer made of a copper-cobalt-nickel alloy is 0.05 to 0.25 μm. The copper foil for printed circuits of description.
The copper foil for printed circuit according to claim 5 or 6, wherein the primary particle layer and the secondary particle layer are electroplating layers.
A copper-clad laminate comprising the printed circuit copper foil according to any one of claims 1 to 7.
A printed circuit board made of the copper clad laminate according to claim 8.