JP7251927B2 - Surface treated copper foil, copper clad laminate and printed wiring board - Google Patents

Description

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

In recent years, with the increasing needs for smaller size and higher performance of electronic devices, there is a demand for finer pitch (miniaturization) of circuit patterns (also called "conductor patterns") for printed wiring boards mounted on electronic devices. ing.
Various methods such as a subtractive method and a semi-additive method are known as methods for manufacturing printed wiring boards. Among them, in the subtractive method, after forming a copper clad laminate by bonding an insulating base material to a copper foil, a resist is applied to the surface of the copper foil and exposed to light to form a predetermined resist pattern, and the resist pattern is formed. A circuit pattern is formed by removing the unfilled portion (unnecessary portion) by etching.

In response to the above demand for finer pitches, for example, Patent Document 1 discloses that the surface of a copper foil is subjected to a roughening treatment by copper-cobalt-nickel alloy plating, and then a cobalt-nickel alloy plating layer is formed. It is described that a surface-treated copper foil capable of forming a fine-pitched circuit pattern can be obtained by forming a zinc-nickel alloy plating layer.

Japanese Patent No. 2849059

However, in conventional surface-treated copper foils, the etching speed of the surface treatment layer (plating layer) is slower than the etching speed of copper foil, so the copper foil surface (top) spreads from the copper foil surface (top) toward the insulating substrate (bottom) side. There is a problem that the etching factor of the circuit pattern is lowered. Further, when the etching factor of the circuit pattern is low, it is necessary to widen the space between adjacent circuits, which makes it difficult to achieve a finer pitch of the circuit pattern.

In addition, circuit patterns are generally required to be difficult to peel off from the insulating base material. Therefore, it is necessary to improve the adhesiveness between the circuit pattern and the insulating base material.

The embodiments of the present invention have been made to solve the above-described problems, and are capable of forming a circuit pattern with excellent adhesion to an insulating substrate and a high etching factor suitable for fine pitching. An object of the present invention is to provide a surface-treated copper foil and a copper-clad laminate capable of
Another object of the embodiments of the present invention is to provide a printed wiring board having a circuit pattern with a high etching factor and excellent adhesion to an insulating substrate.

The present inventors have made intensive studies to solve the above problems, and found that the average length of the roughness curve element based on JIS B0601:2013 RSm is controlled within a specific range, both the adhesion of the circuit pattern to the insulating substrate and the etching factor of the circuit pattern can be enhanced, leading to an embodiment of the present invention.

That is, an embodiment of the present invention has a copper foil and a first surface treatment layer formed on one surface of the copper foil, and the first surface treatment layer has a Ni adhesion amount of 20 to 200 μg/ dm ² , Zn deposition amount of 20 to 1000 μg/dm ² , average length RSm of roughness curve element based on JIS B0601:2013 of 6.65 to 10 μm, and CIE L ^* a ^* b ^* color system a ^* of 5.0 to 28.0.
Further, an embodiment of the present invention relates to a copper-clad laminate comprising a surface-treated copper foil and an insulating base material adhered to the first surface treatment layer of the surface-treated copper foil.
Furthermore, an embodiment of the present invention relates to a printed wiring board comprising a circuit pattern formed from the surface-treated copper foil of the copper-clad laminate.

According to an embodiment of the present invention, a surface-treated copper foil and a copper-clad laminate are provided that are excellent in adhesion to an insulating substrate and capable of forming a circuit pattern with a high etching factor suitable for fine pitching. can do.
Moreover, according to the embodiment of the present invention, it is possible to provide a printed wiring board having a circuit pattern with a high etching factor and excellent adhesiveness to an insulating substrate.

1 is a cross-sectional view of a copper-clad laminate using a surface-treated copper foil according to an embodiment of the present invention; FIG. 1 is a cross-sectional view of a copper-clad laminate using a surface-treated copper foil according to an embodiment of the present invention, which further has a second surface treatment layer. FIG. It is sectional drawing for demonstrating the manufacturing method of a printed wiring board by a subtractive method.

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

FIG. 1 is a cross-sectional view of a copper-clad laminate using a surface-treated copper foil according to an embodiment of the present invention.
The surface-treated copper foil 1 has a copper foil 2 and a first surface treatment layer 3 formed on one surface of the copper foil 2 . Moreover, the copper-clad laminate 10 has the surface-treated copper foil 1 and the insulating base material 11 adhered to the first surface treatment layer 3 of the surface-treated copper foil 1 .

The first surface treatment layer 3 has an average length RSm of roughness curve elements based on JIS B0601:2013 of 5 to 10 μm.
Here, RSm is an index representing the average spacing of the unevenness on the surface. In general, as the size of the particles forming the first surface treatment layer 3 increases, RSm increases because the intervals between surface irregularities increase. As RSm increases, the adhesive strength of the surface-treated copper foil 1 to the insulating base material increases, but portions that remain undissolved during the etching process tend to occur. That is, the etching process tends to form a trapezoidal circuit pattern in which the bottom part is tapered, and the etching factor tends to decrease. On the other hand, when the size of the particles forming the first surface treatment layer 3 becomes small, the opposite tendency to the above tends to occur. That is, although the etching factor is improved, the adhesion of the surface-treated copper foil 1 to the insulating substrate tends to be lowered.
Therefore, in order to achieve both an improvement in adhesion to the insulating substrate and an improvement in etching properties, the RSm of the first surface treatment layer 3 is controlled within the above range. By controlling RSm in this way, the surface of the first surface treatment layer 3 can have a surface shape suitable for achieving both improved adhesion to the insulating substrate and improved etchability. Specifically, since the irregularities on the surface of the first surface treatment layer 3 are formed with an appropriate balance, the etching factor of the circuit pattern and the adhesiveness to the insulating substrate can be increased. From the viewpoint of stably obtaining such effects, it is preferable to control RSm to 5 to 9 μm.

The first surface treatment layer 3 has a* in the CIE L ^* a ^* b ^* color system measured based on the geometric condition C ^of JIS Z8730:2009 (hereinafter also referred to as “a ^* ”) of 3.0 to 28.0 is preferred. a ^* is a value expressing red color, and copper presents a color close to red. Therefore, by controlling a ^* within the above range, the amount of copper in the first surface treatment layer 3 can be adjusted to a range in which the solubility in the etchant is good. factor can be increased. From the viewpoint of stably obtaining such effects, it is preferable to control a ^* to 5.0 to 23.0.

The first surface treatment layer 3 is C, N, O, Zn, Cr, Ni, Co, Si when sputtering is performed for 7 minutes at a sputtering rate of 2.5 nm / minute (in terms of SiO ₂ ) in the XPS depth profile. It is preferable that the concentration of Cu with respect to the total amount of elements of Cu and Cu is 80 to 100 atm % (atomic %). By controlling the copper concentration within this range, the solubility in the etchant can be adjusted, so that the etching factor of the circuit pattern can be increased. From the viewpoint of stably obtaining such effects, it is preferable to control the Cu concentration to 85 to 100 atm %.

Preferably, the first surface treatment layer 3 contains at least Ni and Zn as attachment elements.
Since Ni is a component that is difficult to dissolve in the etchant, the first surface treatment layer 3 can be easily dissolved in the etchant by controlling the Ni adhesion amount of the first surface treatment layer 3 to 200 μg/dm ² or less. As a result, it becomes possible to increase the etching factor of the circuit pattern. From the viewpoint of stably increasing this etching factor, the Ni deposition amount of the first surface treatment layer 3 is controlled to preferably 180 μg/dm ² or less, more preferably 100 μg/dm ² or less. On the other hand, from the viewpoint of ensuring a predetermined effect (for example, heat resistance) of the first surface treatment layer 3, the Ni adhesion amount of the first surface treatment layer 3 is controlled to 20 μg/dm ² or more.
In addition, after the circuit pattern is formed, surface treatment such as gold plating is sometimes performed. However, as a pretreatment, soft etching is performed to remove unnecessary substances from the surface of the circuit pattern. The soft etchant may penetrate. Ni has the effect of suppressing penetration of the soft etching solution. From the viewpoint of sufficiently ensuring this effect, the Ni adhesion amount of the first surface treatment layer 3 is preferably controlled to 30 μg/dm ² or more, more preferably 40 μg/dm ² or more.

Zn is more easily dissolved in an etchant than Ni, and can be deposited in relatively large amounts. Therefore, by controlling the amount of Zn attached to the first surface treatment layer 3 to 1000 μg/dm ² or less, the first surface treatment layer 3 becomes easier to dissolve, and as a result, it becomes possible to increase the etching factor of the circuit pattern. From the viewpoint of stably increasing this etching factor, the Zn deposition amount of the first surface treatment layer 3 is preferably controlled to 700 μg/dm ² or less, more preferably 600 μg/dm ² or less. On the other hand, from the viewpoint of ensuring the predetermined effects (for example, heat resistance, chemical resistance, etc.) of the first surface treatment layer 3, the Zn adhesion amount of the first surface treatment layer 3 is 20 μg/dm ² or more, preferably 100 μg/dm 2 or more. dm ² or more, more preferably 300 μg/dm ² or more. For example, Zn has a barrier effect to prevent thermal diffusion of copper, so it can suppress the roughening particles and copper in the copper foil from coming out to the surface layer due to thermal diffusion. As a result, copper is less likely to come into direct contact with a chemical solution such as a soft etchant, so that it is possible to prevent the soft etchant from penetrating the edges of the circuit pattern.

The first surface treatment layer 3 can further contain elements such as Co and Cr in addition to Ni and Zn as attachment elements.
The Co adhesion amount of the first surface treatment layer 3 is not particularly limited because it depends on the type of the first surface treatment layer 3, but is preferably 1500 μg/dm ² or less, more preferably 500 μg/dm ² or less, and still more preferably 100 μg. /dm ² or less, particularly preferably 30 μg/dm ² or less. By setting the Co deposition amount of the first surface treatment layer 3 within the above range, the etching factor of the circuit pattern can be stably increased. Although the lower limit of the Co adhesion amount is not particularly limited, it is typically 0.1 μg/dm ² , preferably 0.5 μg/dm ² .
Further, since Co is a magnetic metal, printed wiring with excellent high-frequency characteristics can be obtained by suppressing the Co adhesion amount of the first surface treatment layer 3 to 100 μg/dm ² or less, preferably 0.5 to 100 μg/dm ² . A surface-treated copper foil 1 from which a plate can be produced can be obtained.

The Cr adhesion amount of the first surface treatment layer 3 is not particularly limited because it depends on the type of the first surface treatment layer 3, but is preferably 500 μg/dm ² or less, more preferably 0.5 to 300 μg/dm ² , and It is preferably 1 to 100 μg/dm ² . By setting the amount of Cr adhered to the first surface treatment layer 3 within the above range, it is possible to obtain an antirust effect and stably increase the etching factor of the circuit pattern.

The type of the first surface treatment layer 3 is not particularly limited, and various surface treatment layers known in the technical field can be used. Examples of the surface treatment layer used for the first surface treatment layer 3 include a roughening treatment layer, a heat-resistant layer, an antirust layer, a chromate treatment layer, a silane coupling treatment layer, and the like. These layers can be used singly or in combination of two or more. Among them, the first surface treatment layer 3 preferably has a roughening treatment layer from the viewpoint of adhesion to the insulating base material 11 .
Here, the term "roughened layer" as used herein means a layer formed by roughening treatment, and includes a layer of roughened particles. In addition, in the roughening treatment, ordinary copper plating or the like may be performed as a pretreatment, or ordinary copper plating or the like may be performed as a finishing treatment to prevent the roughening particles from falling off. The "roughened layer" in the book includes layers formed by these pretreatments and finishing treatments.

The roughening particles are not particularly limited, but are formed from an alloy containing any one or more selected from the group consisting of copper, nickel, cobalt, phosphorus, tungsten, arsenic, molybdenum, chromium and zinc. can do. Further, after the roughened particles are formed, a roughening treatment can be performed to form secondary particles and tertiary particles of nickel, cobalt, copper, zinc or the like.

The roughened layer can be formed by electroplating. The conditions are not particularly limited, but typical conditions are as follows. Also, the electroplating may be performed in two steps.
Plating solution composition: 10-20 g/L Cu, 50-100 g/L sulfuric acid Plating solution temperature: 25-50°C
Electroplating conditions: current density 1-60 A/dm ² , time 1-10 seconds

The heat-resistant layer and the antirust layer are not particularly limited, and can be formed from materials known in the art. In addition, since the heat-resistant layer may also function as a rust-preventive layer, one layer having the functions of both the heat-resistant layer and the rust-preventive layer may be formed as the heat-resistant layer and the rust-preventive layer.
As a heat-resistant layer and/or an antirust layer, the group of nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, platinum group elements, iron, and tantalum It can be a layer containing one or more elements (in any form of metals, alloys, oxides, nitrides, sulfides, etc.) selected from. Examples of heat-resistant and/or rust-resistant layers include layers comprising nickel-zinc alloys.

The heat-resistant layer and the antirust layer can be formed by electroplating. The conditions are not particularly limited, but typical conditions for the heat-resistant layer (Ni--Zn layer) are as follows.
Plating solution composition: 1 to 30 g/L Ni, 1 to 30 g/L Zn
Plating solution pH: 2-5
Plating solution temperature: 30-50°C
Electroplating conditions: current density 1-10 A/dm ² , time 0.1-5 seconds

The chromate treatment layer is not particularly limited, and can be formed from materials known in the technical field.
As used herein, the term "chromate treatment layer" means a layer formed of a liquid containing chromic anhydride, chromic acid, dichromic acid, chromate, or dichromate. The chromating layer contains elements such as cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, titanium, etc. (any metal, alloy, oxide, nitride, sulfide, etc.) morphology). Examples of the chromate-treated layer include a chromate-treated layer treated with an aqueous solution of chromic acid anhydride or potassium dichromate, a chromate-treated layer treated with a treatment liquid containing chromic anhydride or potassium dichromate and zinc, and the like.

The chromate treatment layer can be formed by immersion chromate treatment. The conditions are not particularly limited, but typical conditions for the chromate treatment layer are as follows.
Plating solution composition: 1-10 g/L K ₂ Cr ₂ O ₇ , 0.01-10 g/L Zn
Plating solution pH: 2-5
Plating solution temperature: 30-50°C

The silane coupling-treated layer is not particularly limited, and can be formed from materials known in the art.
Here, the term "silane coupling treated layer" as used herein means a layer formed with a silane coupling agent.
The silane coupling agent is not particularly limited, and those known in the art can be used. Examples of silane coupling agents include amino-based silane coupling agents, epoxy-based silane coupling agents, and mercapto-based silane coupling agents. These can be used singly or in combination of two or more.

Moreover, the surface-treated copper foil 1 can further have a second surface-treated layer 4 formed on the other surface of the copper foil 2, as shown in FIG.
The type of the second surface treatment layer 4 is not particularly limited, and like the first surface treatment layer 3, various surface treatment layers known in the art can be used. Moreover, the type of the second surface treatment layer 4 may be the same as or different from that of the first surface treatment layer 3 .

The second surface treatment layer 4 can contain elements such as Ni, Zn, and Cr as attachment elements.
The ratio of the Ni deposition amount of the first surface treatment layer 3 to the Ni deposition amount of the second surface treatment layer 4 is preferably 0.01 to 2.5, more preferably 0.6 to 2.2. Since Ni is a component that is difficult to dissolve in the etching solution, by setting the ratio of the Ni adhesion amount within the above range, when etching the copper-clad laminate 10, the first surface treatment layer that becomes the bottom side of the circuit pattern 3 can be promoted, and dissolution of the second surface treatment layer 4, which is the top side of the circuit pattern, can be suppressed. Therefore, it is possible to obtain a circuit pattern with a small difference between the top width and the bottom width and a high etching factor.

The Ni adhesion amount of the second surface treatment layer 4 is not particularly limited because it depends on the type of the second surface treatment layer 4, but is preferably 0.1 to 500 μg/dm ² , more preferably 0.5 to 200 μg/dm. ² , more preferably 1 to 100 μg/dm ² . By setting the Ni adhesion amount of the second surface treatment layer 4 within the above range, the etching factor of the circuit pattern can be stably increased.

The amount of Zn attached to the second surface treatment layer 4 is not particularly limited because it depends on the type of the second surface treatment layer 4, but when the second surface treatment layer 4 contains Zn, it is preferably 10 to 1000 μg/dm. ² , more preferably 50 to 500 μg/dm ² , still more preferably 100 to 300 μg/dm ² . By setting the amount of Zn attached to the second surface treatment layer 4 within the above range, the effect of heat resistance and chemical resistance can be obtained, and the etching factor of the circuit pattern can be stably increased.

The amount of Cr deposited on the second surface treatment layer 4 is not particularly limited because it depends on the type of the second surface treatment layer 4, but when the second surface treatment layer 4 contains Cr, it preferably exceeds 0 μg/dm ² 500 μg/dm ² or less, more preferably 0.1 to 100 μg/dm ² , still more preferably 1 to 50 μg/dm ² . By setting the amount of Cr adhered to the second surface treatment layer 4 within the above range, it is possible to obtain an anticorrosive effect and stably increase the etching factor of the circuit pattern.

The copper foil 2 is not particularly limited, and may be either an electrolytic copper foil or a rolled copper foil. Electrodeposited copper foil is generally manufactured by electrolytically depositing copper from a copper sulfate plating bath onto a titanium or stainless steel drum. It has an M surface (matte surface) formed on the opposite side. In general, since the M surface of the electrolytic copper foil has unevenness, by forming the first surface treatment layer 3 on the M surface of the electrolytic copper foil and the second surface treatment layer 4 on the S surface of the electrolytic copper foil, Adhesion between the first surface treatment layer 3 and the insulating base material 11 can be enhanced.

The material of the copper foil 2 is not particularly limited. High purity copper such as alloy number C1020 or JIS H3510 alloy number C1011) can be used. Copper alloys such as Sn-containing copper, Ag-containing copper, copper alloys containing Cr, Zr, Mg, etc., and Corson copper alloys containing Ni, Si, etc. can also be used. In addition, in this specification, the "copper foil 2" is a concept including a copper alloy foil.

The thickness of the copper foil 2 is not particularly limited. can.

The surface-treated copper foil 1 having the configuration as described above can be manufactured according to a method known in the art. Here, the Ni deposition amount of the first surface treatment layer 3 and the second surface treatment layer 4 and the ratio of the Ni deposition amount can be controlled by changing the type and thickness of the surface treatment layers to be formed, for example. Also, the Rz of the first surface treatment layer 3 can be controlled by adjusting the formation conditions of the first surface treatment layer 3, for example.

The copper clad laminate 10 can be produced by adhering the insulating substrate 11 to the first surface treatment layer 3 of the surface treatment copper foil 1 .
The insulating base material 11 is not particularly limited, and one known in the art can be used. Examples of the insulating base material 11 include paper base phenol resin, paper base epoxy resin, synthetic fiber cloth base epoxy resin, glass cloth/paper composite base epoxy resin, glass cloth/glass nonwoven cloth composite base epoxy resin, Glass cloth substrate epoxy resin, polyester film, polyimide film, liquid crystal polymer, fluororesin, and the like.

The method of adhering the surface-treated copper foil 1 and the insulating base material 11 is not particularly limited, and can be carried out according to a method known in the technical field. For example, the surface-treated copper foil 1 and the insulating base material 11 may be laminated and thermocompression bonded.

The copper-clad laminate 10 manufactured as described above can be used for manufacturing a printed wiring board. The method for manufacturing the printed wiring board is not particularly limited, and known methods such as the subtractive method and the semi-additive method can be used. Among them, the copper-clad laminate 10 is most suitable for use in the subtractive method.

FIG. 3 is a cross-sectional view for explaining a method of manufacturing a printed wiring board by a subtractive method.
In FIG. 3, first, a predetermined resist pattern 20 is formed by applying a resist to the surface of the surface-treated copper foil 1 of the copper-clad laminate 10, exposing it, and developing it (step (a)). Next, the portion (unnecessary portion) of the surface-treated copper foil 1 where the resist pattern 20 is not formed is removed by etching (step (b)). Finally, the resist pattern 20 on the surface-treated copper foil 1 is removed (step (c)).
Various conditions in this subtractive method are not particularly limited, and can be carried out according to conditions known in the technical field.

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

(Example 1)
A rolled copper foil (HA-V2 foil manufactured by JX Metals Co., Ltd.) with a thickness of 12 μm is prepared, and a roughening treatment layer, a heat-resistant layer and a chromate treatment layer are sequentially formed as a first surface treatment layer on one surface, and the other surface is A surface-treated copper foil was obtained by successively forming a heat-resistant layer and a chromate-treated layer as a second surface-treated layer on the surface. The conditions for forming each layer are as follows.

<Roughening treatment layer of the first surface treatment layer>
A roughened layer was formed by electroplating. Electroplating was performed in two stages.
(Conditions for the first stage)
Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid
Plating solution temperature: 25°C
Electroplating conditions: current density 42.7 A/dm ² , time 1.4 seconds (second stage conditions)
Plating solution composition: 20 g/L Cu, 100 g/L sulfuric acid
Plating solution temperature: 50°C
Electroplating conditions: current density 3.8 A/dm ² , time 2.8 seconds

<Heat-resistant layer of the first surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 1.1 A/dm ² , time 0.7 seconds

<Chromate treatment layer of the first surface treatment layer>
A chromate treatment layer was formed by electroplating.
Plating _solution composition: 3.0 g/L _K2Cr2O7 , 0.33 g/ _L Zn
Plating solution pH: 3.6
Plating solution temperature: 50°C
Electroplating conditions: current density 2.1 A/dm ² , time 1.4 seconds

<Heat-resistant layer of the second surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 2.8 A/dm ² , time 0.7 seconds

<Chromate treatment layer of the second surface treatment layer>
A chromate treatment layer was formed by immersion chromate treatment.
Chromate _liquid composition: 3.0 g/L _K2Cr2O7 , 0.33 g _/ L Zn
Chromate solution pH: 3.6
Chromate liquid temperature: 50°C

(Example 2)
A surface-treated copper foil was obtained in the same manner as in Example 1, except that the conditions for forming the heat-resistant layer of the first surface treatment layer were changed as follows.
<Heat-resistant layer of the first surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 2.6 A/dm ² , time 0.7 seconds

(Example 3)
A surface-treated copper foil was obtained in the same manner as in Example 1, except that the conditions for forming the heat-resistant layer of the first surface treatment layer were changed as follows.
<Heat-resistant layer of the first surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 3.7 A/dm ² , time 0.7 seconds

(Example 4)
A surface-treated copper foil was obtained in the same manner as in Example 1, except that the conditions for forming the heat-resistant layer of the first surface treatment layer were changed as follows.
<Heat-resistant layer of the first surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 4.2 A/dm ² , time 0.7 seconds

(Example 5)
A surface-treated copper foil was obtained in the same manner as in Example 1, except that the conditions for forming the heat-resistant layers of the first surface treatment layer and the second surface treatment layer were changed as follows.
<Heat-resistant layer of the first surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 2.1 A/dm ² , time 0.7 seconds <Heat resistant layer of second surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 1.7 A/dm ² , time 0.7 seconds

(Comparative example 1)
A rolled copper foil (HA-V2 foil manufactured by JX Metals Co., Ltd.) with a thickness of 12 μm is prepared, and a roughening treatment layer, a heat-resistant layer and a chromate treatment layer are sequentially formed as a first surface treatment layer on one surface, and the other surface is A surface-treated copper foil was obtained by successively forming a heat-resistant layer and a chromate-treated layer as a second surface-treated layer on the surface. The conditions for forming each layer are as follows.
<Roughening treatment layer of the first surface treatment layer>
A roughened layer was formed by electroplating.
Plating solution composition: 15 g/L Cu, 7.5 g/L Co, 9.5 g/L Ni
Plating solution pH: 2.4
Plating solution temperature: 36°C
Electroplating conditions: current density 31.5 A/dm ² , time 1.8 seconds

<Heat-resistant layer (1) of the first surface treatment layer>
A heat-resistant layer (1) was formed by electroplating.
Plating solution composition: 3 g/L Co, 13 g/L Ni
Plating solution pH: 2.0
Plating solution temperature: 50°C
Electroplating conditions: current density 19.1 A/dm ² , time 0.4 seconds

<Heat-resistant layer (2) of the first surface treatment layer>
A heat-resistant layer (2) was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 3.5 A/dm ² , time 0.4 seconds

<Chromate treatment layer of the first surface treatment layer>
A chromate treatment layer was formed by immersion chromate treatment.
Chromate _liquid composition: 3 g/ _{L K2Cr2O7} , 0.33 g/L Zn
Chromate solution pH: 3.6
Chromate liquid temperature: 50°C

<Heat-resistant layer of the second surface treatment layer>
A heat-resistant layer was formed by electroplating.
Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn
Plating solution pH: 3.6
Plating solution temperature: 40°C
Electroplating conditions: current density 4.1 A/dm ² , time 0.4 seconds

<Chromate treatment layer of the second surface treatment layer>
A chromate treatment layer was formed by immersion chromate treatment.
Chromate _liquid composition: 3 g/ _{L K2Cr2O7} , 0.33 g/L Zn
Chromate solution pH: 3.6
Chromate liquid temperature: 50°C

The surface-treated copper foils obtained in the above examples and comparative examples were evaluated as follows.
<Measurement of adhesion amount of each element in first surface treatment layer and second surface treatment layer>
The amount of Ni, Zn and Co deposited is determined by dissolving each surface treatment layer in nitric acid having a concentration of 20% by mass and performing quantitative analysis by atomic absorption spectrophotometry using an atomic absorption spectrophotometer (model: AA240FS) manufactured by VARIAN. measured by The Cr deposition amount was measured by dissolving each surface treatment layer in hydrochloric acid having a concentration of 7% by mass and performing quantitative analysis by atomic absorption spectrometry in the same manner as described above.

<Measurement of average length RSm of roughness curve element of first surface treatment layer of surface-treated copper foil>
Based on JIS B0601:2013, RSm was measured using a laser microscope (LEXT OLS4100) manufactured by Olympus Corporation. For RSm, the average value of values measured at arbitrary 10 locations was used as the measurement result. The temperature during the measurement was 23 to 25°C. Also, the main setting conditions in the laser microscope are as follows.
Objective lens: MPLAPONLEXT50 (x50x)
Scanning mode: XYZ high precision Captured image size [Number of pixels]: Horizontal 257 μm × Vertical 258 μm [1024 × 1024]
(Since it is measured in the horizontal direction, it corresponds to 257 μm as an evaluation length)
Cutoff: none (no λc, λs, λf)
Filter: Gaussian filter Noise removal and tilt correction: Implemented

<Measurement of a ^* of first surface treatment layer of surface-treated copper foil>
Using HunterLab's MiniScan (registered trademark) EZ Model 4000L as a measuring instrument, a ^* in the CIE L ^* a ^* b ^* color system was measured according to JIS Z8730:2009. Specifically, the first surface treatment layer of the surface-treated copper foil obtained in the above examples and comparative examples was pressed against the photosensitive part of the measuring instrument, and a ^* was measured while preventing light from entering from the outside. . Moreover, the measurement of a ^* was performed based on the geometric condition C of JIS Z8722. The main conditions of the measuring instrument are as follows.
Optical system d/8°, Integrating sphere size: 63.5mm, Observation light source D65
Measurement method Reflection Illumination diameter 25.4mm
Measurement diameter 20.0mm
Measurement wavelength/interval 400-700nm/10nm
Light source Pulsed xenon lamp, 1 light emission/measurement Traceability standards Based on CIE 44 and ASTM E259, US National Institute of Standards and Technology (NIST) compliant calibration Standard observer 10°
In addition, the following object colors were used for the white tiles used as the measurement standard.
When measured at D65/10°, the values in the CIE XYZ color system are X: 81.90, Y: 87.02, Z: 93.76 (this is the CIE L ^* a ^* b ^* color system Converting the numerical values to the system, L ^* : 94.8, a ^* : -1.6, b ^* : 0.7).

<Measurement of Copper Concentration in XPS Depth Profile of First Surface Treated Layer of Surface Treated Copper Foil>
XPS analysis was performed in the depth direction on the first surface-treated layer of the surface-treated copper foil, and the Cu concentration was measured when sputtering was performed for 7 minutes at a sputtering rate of 2.5 nm/min (in terms of SiO ₂ ). Other conditions were as follows.
Device: 5600MC manufactured by ULVAC-Phi, Inc.
Ultimate degree of vacuum: 5.7×10 ⁻⁷ Pa
Excitation source: monochromatic MgKα
Output: 400W
Detection area: 800 μmφ
Incident angle: 81°
Take-off angle: 45°
No neutralization gun Elements to be measured: C, N, O, Zn, Cr, Ni, Co, Si and Cu
<Sputtering conditions>
Ion species: Ar+
Accelerating voltage: 3 kV
Sweep area: 3mm x 3mm

<Evaluation of etching factor>
A copper-clad laminate was produced by laminating a polyimide substrate on the first surface-treated layer of the surface-treated copper foil, followed by heating at 300° C. for 1 hour and pressure bonding. Next, a resist pattern having a width of L/S=29 μm/21 μm was formed by applying a photosensitive resist onto the second surface treatment layer of the surface treatment copper foil, exposing and developing the resist. Thereafter, the exposed portion (unnecessary portion) of the surface-treated copper foil was removed by etching to obtain a printed wiring board having a copper circuit pattern of L/S=25 μm/25 μm width. The width of L and S of the circuit pattern is the width of the bottom surface of the circuit, that is, the width of the surface in contact with the polyimide substrate. Etching was performed under the following conditions using spray etching.
Etching solution: Copper chloride etching solution (400 g/L of copper (II) chloride dihydrate, 200 ml/L as 35% hydrochloric acid)
Liquid temperature: 45°C
Spray pressure: 0.18MPa
Next, the formed circuit pattern was observed with an SEM, and the etching factor (EF) was obtained based on the following formula.
EF=circuit height/{(circuit bottom width−circuit top width)/2}
The etching factor means that the larger the numerical value, the larger the inclination angle of the side surface of the circuit.
Table 1 shows the above evaluation results.
The EF value is the average value of the results of 5 experiments for each example and comparative example.

<Evaluation of peel strength>
The 90-degree peel strength was measured according to JIS C6471:1995. Specifically, the width of the circuit (surface-treated copper foil) was 3 mm, and the substrate (FR-4 prepreg) on the market and the surface-treated copper foil were peeled off at an angle of 90 degrees at a rate of 50 mm/min. The strength was measured when 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 conductor and the substrate is good.
The circuit width was adjusted by a normal subtractive etching method using a copper chloride etchant. The peel strength was evaluated under two conditions, the initial stage (immediately after etching) and the thermal history (260° C., 20 seconds) corresponding to solder reflow.

The above evaluation results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, Examples 1 to 5 in which RSm of the first surface treatment layer was 5 to 10 μm had high etching factors and peel strengths, whereas RSm of the first surface treatment layer was Comparative Example 1 with a thickness of less than 5 μm had a low etching factor. In Examples 1 to 5, the peel strength was high not only at the initial stage but also after thermal history.

As can be seen from the above results, according to the embodiment of the present invention, the surface-treated copper that has excellent adhesion to the insulating substrate and can form a circuit pattern with a high etching factor suitable for fine pitch. Foils and copper clad laminates can be provided. Moreover, according to the embodiment of the present invention, it is possible to provide a printed wiring board having a circuit pattern with a high etching factor and excellent adhesiveness to an insulating substrate.

Reference Signs List 1 surface-treated copper foil 2 copper foil 3 first surface-treated layer 4 second surface-treated layer 10 copper-clad laminate 11 insulating substrate 20 resist pattern

Claims (7)

Having a copper foil and a first surface treatment layer formed on one surface of the copper foil,
The first surface treatment layer has a Ni adhesion amount of 20 to 200 μg/dm ² , a Zn adhesion amount of 20 to 1000 μg/dm ² , and an average length RSm of roughness curve elements based on JIS B0601:2013 of 6.65 to 10 μm, and a surface-treated copper foil having a ^* of 5.0 to 28.0 in the CIE L ^* a ^* b ^* color system. The surface-treated copper foil according to claim 1, wherein said RSm is 6.65 to 9 µm. The surface-treated copper foil according to claim 1 or 2, wherein said a ^* is 5.0 to 23.0. The first surface treatment layer is C, N, O, Zn, Cr, Ni, Co, Si when sputtering is performed for 7 minutes at a sputtering rate of 2.5 nm / min (in terms of SiO ₂ ) in the XPS depth profile. 4. The surface-treated copper foil according to any one of claims 1 to 3 , wherein the concentration of Cu is 80 to 100 atm% with respect to the total amount of elements of Cu and Cu. The surface-treated copper foil according to any one of claims 1 to 4 , wherein the copper foil is a rolled copper foil. A copper-clad laminate comprising the surface-treated copper foil according to any one of claims 1 to 5 and an insulating substrate adhered to the first surface treatment layer of the surface-treated copper foil. A printed wiring board comprising a circuit pattern formed from the surface-treated copper foil of the copper-clad laminate according to claim 6 .

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