JP7107190B2 - Method for manufacturing copper-clad laminate - Google Patents

Description

The present invention relates to a method for manufacturing a copper-clad laminate. More particularly, the present invention relates to a method of manufacturing a copper- clad laminate used for manufacturing flexible printed circuit boards (FPC) and the like.

A flexible printed wiring board having a wiring pattern formed on the surface of a resin film is used for liquid crystal panels, laptop computers, digital cameras, mobile phones, and the like. A flexible printed wiring board is manufactured, for example, from a copper-clad laminate.

A metallizing method is known as a method of manufacturing a copper-clad laminate. A copper-clad laminate is manufactured by the metallizing method, for example, in the following procedure. First, a base metal layer made of a nickel-chromium alloy is formed on the surface of a resin film. Next, a copper thin film layer is formed on the base metal layer. Next, a copper plating film is formed on the copper thin film layer. By copper plating, the conductor layer is thickened to a thickness suitable for forming a wiring pattern. A copper-clad laminate of a type called a two-layer substrate, in which a conductor layer is directly formed on a resin film, is obtained by the metallizing method.

A semi-additive method is known as a method of manufacturing a flexible printed wiring board using this kind of copper-clad laminate. A flexible printed wiring board is manufactured by the semi-additive method according to the following procedure (see Patent Document 1). First, a resist layer is formed on the surface of the copper plating film of the copper-clad laminate. Next, an opening is formed in a portion of the resist layer where the wiring pattern is to be formed. Next, electrolytic plating is performed using the copper plating film exposed from the opening of the resist layer as a cathode to form a wiring portion. Next, the resist layer is removed, and the conductor layer other than the wiring portion is removed by flash etching or the like. A flexible printed wiring board is thus obtained.

In the semi-additive method, a dry film resist is sometimes used to form a resist layer on the surface of the copper plating film. In this case, after chemically polishing the surface of the copper plating film, a dry film resist is applied. By chemically polishing the surface of the copper-plated film with fine unevenness, the adhesion of the dry film resist is enhanced by the anchor effect. However, if the unevenness on the surface of the copper plating film is excessive, the adhesion of the dry film resist may rather deteriorate.

JP 2006-278950 A

The surface roughness of the copper plating film after chemical polishing is affected by the grain size of the copper plating film. There is a tendency that the smaller the crystal grains, the smoother the surface of the copper plating film after chemical polishing, and the larger the crystal grains, the rougher the surface of the copper plating film after chemical polishing.

The crystal grains of the copper plating film gradually become larger as recrystallization progresses after plating. When chemical polishing is performed on a copper plating film in progress of recrystallization, the surface roughness of the copper plating film after chemical polishing changes depending on the elapsed time from the plating treatment at the time of chemical polishing. Therefore, process control in wiring processing becomes difficult. In addition, since the crystal grains of the recrystallized copper plating film are large, the surface roughness after chemical polishing may be excessive. Therefore, the copper plating film of the copper-clad laminate is sometimes required to progress recrystallization slowly.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a copper- clad laminate having a copper-plated film in which recrystallization progresses slowly.

In the method for producing a copper-clad laminate of the first invention, the substrate is conveyed by roll-to-roll in a plating bath in which a copper plating solution containing a brightener component containing sulfur is stored, and the substrate is electroplated. In obtaining a copper clad laminate by forming a copper plating film on the surface of the material, electrolysis is performed by energizing between the anode and the base material in the plating tank along the conveying direction of the base material. It is characterized in that an electrolysis zone for electrolysis and a spraying zone for spraying the copper plating solution onto the plating surface in a non-energized state are provided alternately.
A method for producing a copper-clad laminate according to a second invention is characterized in that, in the first invention, the copper plating solution ejected from a slit nozzle is sprayed onto the plating surface, and the discharge flow rate of the slit nozzle is 2 to 30 L per 100 mm of slit length. /min.
A method for producing a copper-clad laminate according to a third aspect of the invention is characterized in that, in the method of the first or second aspect, the concentration of the brightener component in the copper plating solution is 1-30 mg/L.

According to the present invention, the copper plating film has a structure in which high sulfur concentration layers and low sulfur concentration layers are alternately laminated. Since recrystallization is inhibited by sulfur in the copper plating film, progress of recrystallization of the copper plating film can be slowed down.

1 is a cross-sectional view of a copper-clad laminate according to one embodiment of the present invention; FIG. 1 is a perspective view of a plating apparatus; FIG. It is a top view of a plating bath. 4 is a graph showing the relationship between the discharge flow rate of the slit nozzle and the glossiness of the surface of the copper plating film in the glossiness measurement test.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a copper-clad laminate 1 according to one embodiment of the present invention comprises a substrate 10 and a copper plating film 20 formed on the surface of the substrate 10 . The copper plating film 20 may be formed only on one side of the substrate 10 as shown in FIG.

The copper plating film 20 is deposited by electrolytic plating. Therefore, the substrate 10 may be any material as long as it has conductivity on the surface on which the copper plating film 20 is formed. For example, the substrate 10 is formed by forming a metal layer 12 on the surface of an insulating base film 11 . A resin film such as a polyimide film can be used as the base film 11 . The metal layer 12 is formed by sputtering, for example. The metal layer 12 consists of a base metal layer 13 and a copper thin film layer 14 . The underlying metal layer 13 and the copper thin film layer 14 are laminated in this order on the surface of the base film 11 . Underlying metal layer 13 is generally comprised of nickel, chromium, or a nickel-chromium alloy. Although not particularly limited, the thickness of the base metal layer 13 is generally 5 to 50 nm, and the thickness of the copper thin film layer 14 is generally 50 to 400 nm.

A copper plating film 20 is formed on the surface of the metal layer 12 . Although not particularly limited, the thickness of the copper plating film 20 is generally 1 to 3 μm. The metal layer 12 and the copper plating film 20 are collectively referred to as a "conductor layer".

The copper plating film 20 is formed by the plating apparatus 3 shown in FIG. 2, although not particularly limited.
The plating apparatus 3 is an apparatus that performs electrolytic plating on the base material 10 while transporting the base material 10 in the form of a long strip by roll-to-roll. The plating apparatus 3 has a supply device 31 that feeds out the base material 10 wound into a roll, and a winding device 32 that winds up the base material 10 (copper-clad laminate 1) after plating into a roll.

The plating apparatus 3 also has a pair of upper and lower endless belts 33 (the lower endless belt 33 is not shown) for conveying the substrate 10 . Each endless belt 33 is provided with a plurality of clamps 34 for gripping the substrate 10 . The base material 10 delivered from the supply device 31 is in a suspended position with its width direction along the vertical direction, and both edges are gripped by the upper and lower clamps 34 . After the substrate 10 is circulated inside the plating device 3 by driving the endless belt 33 , the substrate 10 is released from the clamp 34 and wound up by the winding device 32 .

A pretreatment bath 35 , a plating bath 40 , and a posttreatment bath 36 are arranged along the transport path of the base material 10 . While the base material 10 is conveyed in the plating tank 40, a copper plating film 20 is formed on its surface by electroplating. Thus, a long belt-shaped copper-clad laminate 1 is obtained.

As shown in FIG. 3, the plating tank 40 is a horizontally long single tank along the conveying direction of the substrate 10 . The substrate 10 is transported along the center of the plating bath 40 . A plating bath 40 stores a copper plating solution. The base material 10 conveyed in the plating bath 40 is entirely immersed in the copper plating solution.

A copper plating solution contains a water-soluble copper salt. Any water-soluble copper salt generally used in copper plating solutions can be used without particular limitation. Examples of water-soluble copper salts include inorganic copper salts, alkanesulfonate copper salts, alkanol sulfonate copper salts, and organic acid copper salts. Inorganic copper salts include copper sulfate, copper oxide, copper chloride, copper carbonate, and the like. Copper alkanesulfonates include copper methanesulfonate and copper propanesulfonate. Alkanol sulfonic acid copper salts include copper isethionate and copper propanol sulfonate. Organic acid copper salts include copper acetate, copper citrate, copper tartrate and the like.

As the water-soluble copper salt used in the copper plating solution, one selected from inorganic copper salts, alkanesulfonic acid copper salts, alkanol sulfonic acid copper salts, organic acid copper salts, etc. may be used alone, or two or more types may be used. may be used in combination. For example, two or more different types in one category selected from inorganic copper salts, alkanesulfonic acid copper salts, alkanol sulfonic acid copper salts, organic acid copper salts, etc., as in the case of combining copper sulfate and copper chloride. They may be used in combination. However, from the viewpoint of managing the copper plating solution, it is preferable to use one type of water-soluble copper salt alone.

The copper plating solution may contain sulfuric acid. By adjusting the amount of sulfuric acid added, the pH and sulfate ion concentration of the copper plating solution can be adjusted.

Copper plating solutions generally contain additives that are added to the plating solution. Additives include brightener components, leveler components, polymer components, chlorine components, and the like. The copper plating solution contains at least a brightener component. Moreover, the copper plating solution may contain one selected from a leveler component, a polymer component, a chlorine component, or the like, or may contain two or more components.

The brightener component contains sulfur. The brightener component is not particularly limited, but one or two selected from bis(3-sulfopropyl)disulfide (abbreviated as SPS), 3-mercaptopropane-1-sulfonic acid (abbreviated as MPS), etc. It is preferable to use a combination of the above. The leveler component is composed of a nitrogen-containing amine or the like. Examples of leveler components include diallyldimethylammonium chloride, Janus Green B, and the like. The polymer component is not particularly limited, but it is preferable to use one selected from polyethylene glycol, polypropylene glycol, and polyethylene glycol-polypropylene glycol copolymer alone or in combination of two or more. The chlorine component is not particularly limited, but it is preferable to use one selected from hydrochloric acid, sodium chloride, etc. alone or in combination of two or more.

The content of each component of the copper plating solution can be selected arbitrarily. However, the copper plating solution preferably contains 15 to 70 g/L of copper and 20 to 250 g/L of sulfuric acid. Then, the copper plating film 20 can be formed at a sufficient speed. The copper plating solution preferably contains 1 to 30 mg/L of brightener component. By doing so, the precipitated crystals can be made finer and the surface of the copper plating film 20 can be smoothed. The copper plating solution preferably contains 0.5 to 50 mg/L of leveler component. By doing so, a flat copper plating film 20 can be formed by suppressing protrusions. The copper plating solution preferably contains 10 to 1,500 mg/L of polymer component. By doing so, it is possible to reduce current concentration at the edge of the substrate 10 and form a uniform copper plating film 20 . The copper plating solution preferably contains 20 to 80 mg/L of chlorine component. Then, abnormal precipitation can be suppressed.

The temperature of the copper plating solution is preferably 23-38°C. Moreover, it is preferable to stir the copper plating solution in the plating tank 40 . The means for stirring the copper plating solution is not particularly limited, but means using a jet flow can be used. For example, the copper plating solution can be agitated by spraying the copper plating solution ejected from a nozzle onto the substrate 10 .

A plurality of anodes 41 are arranged inside the plating bath 40 along the transport direction of the substrate 10 . The material and structure of the anode 41 are not particularly limited, but may be, for example, a mesh-like insoluble electrode obtained by coating titanium with iridium oxide. Also, the clamp 34 that grips the substrate 10 is grounded. When a current is passed between the anode 41 and the substrate 10, electrolysis is performed using the substrate 10 as a cathode. By performing electrolysis, the copper plating film 20 can be formed on the surface of the base material 10 .

Anodes 41 are arranged on both front and back sides of the substrate 10 in the plating bath 40 shown in FIG. Therefore, if the substrate 10 having the metal layers 12 formed on both sides of the base film 11 is used, the copper plating films 20 can be formed on both sides of the substrate 10 .

A rectifier is connected to each of the plurality of anodes 41 arranged inside the plating tank 40 . Therefore, each anode 41 can be set to have a different current density. It is preferable to set the current density to 0.3 to 10 A/dm ² . Moreover, it is preferable to set the current density so as to increase stepwise toward the downstream side in the conveying direction of the substrate 10 .

A slit nozzle 42 is arranged between the adjacent anodes 41 , 41 . The slit nozzle 42 is a nozzle having a slit-shaped ejection port. The liquid ejected from the slit nozzle 42 forms a film-like liquid flow. A copper plating solution is ejected from the slit nozzle 42 . Therefore, a film-like jet can be formed in the plating solution stored in the plating bath 40 .

The slit nozzle 42 is arranged so that the discharge port faces the substrate 10 . Also, the slit nozzle 42 is arranged so that the longitudinal direction of the discharge port is along the vertical direction (the direction perpendicular to the paper surface in FIG. 3). In other words, the slit nozzles 42 are arranged so that the longitudinal direction of the ejection port is along the direction orthogonal to the conveying direction of the substrate 10 . The longitudinal dimension of the ejection port of the slit nozzle 42 is set equal to or longer than the width dimension of the substrate 10 . Therefore, the jet of the copper plating solution formed by the slit nozzle 42 is sprayed over the entire plating surface (the surface of the copper plating film 20 being formed).

The discharge flow rate of the slit nozzle 42 is preferably 2 to 30 L/min per 100 mm of the slit length (longitudinal length of the discharge port).

The slit nozzle 42 is surrounded by a U-shaped shielding plate 43 that shields the current. The opening of the shielding plate 43 faces the base material 10 . Since the current between the anode 41 and the base material 10 is shielded by the shielding plate 43, the portion of the base material 10 facing the opening of the shielding plate 43 is in a non-energized state (current density is substantially 0). It has become. Therefore, the copper plating solution can be sprayed onto the plating surface in a non-energized state. Hereinafter, spraying a copper plating solution onto a plating surface in a non-energized state may be simply referred to as "spraying".

Inside the plating bath 40, a plurality of anodes 41 and a plurality of slit nozzles 42 are alternately arranged along the conveying direction of the substrate 10. As shown in FIG. Also, each of the plurality of slit nozzles 42 is surrounded by a shielding plate 43 . Therefore, the substrate 10 alternately passes through the area facing the anode 41 and the area facing the slit nozzle 42 and the shielding plate 43 .

The area of the plating tank 40 where the anodes 41 are arranged is called an "electrolysis area EZ". In the electrolysis zone EZ, electricity is passed between the anode 41 and the substrate 10 to perform electrolysis. Also, the area of the plating bath 40 where the slit nozzle 42 and the shielding plate 43 are arranged is referred to as a "spraying area SZ". In the spray zone SZ, the copper plating solution is sprayed onto the plating surface in a non-energized state.

The anodes 41 and the slit nozzles 42 are alternately arranged along the conveying direction of the substrate 10 . Therefore, the electrolysis zone EZ and the spraying zone SZ are alternately provided in the plating bath 40 along the conveying direction of the substrate 10 .

The number of electrolysis zones EZ is usually two or more. The number of spraying zones SZ may be one or plural. The most upstream zone and the most downstream zone with respect to the conveying direction of the substrate 10 are usually the electrolysis zone EZ.

The substrate 10 is electroplated while alternately passing through the electrolysis zone EZ and the spray zone SZ. That is, in the plating tank 40, the base material 10 is alternately electrolyzed and sprayed repeatedly. Thereby, a copper plating film 20 is formed.

The copper plating film 20 formed by such a method contains sulfur as an impurity. Further, as shown in FIG. 1, the copper plating film 20 has a structure in which high sulfur concentration layers 21 and low sulfur concentration layers 22 are alternately laminated in the thickness direction. Here, the high sulfur concentration layer 21 is a layer with a relatively high sulfur concentration, and the low sulfur concentration layer 22 is a layer with a relatively low sulfur concentration.

The reason why the high sulfur concentration layer 21 and the low sulfur concentration layer 22 are laminated in this way is considered as follows.
Additives (brightener component, leveler component and polymer component) are adsorbed on the surface of the copper plating film 20 during electrolysis. Here, the leveler component and the polymer component are adsorbed on the surface of the copper plating film 20 by an electrical action caused by electrolysis. On the other hand, the brightener component is adsorbed on the surface of the copper plating film 20 regardless of electrolysis.

After the electrolysis, when the copper plating solution is sprayed on the plating surface in a non-energized state, the leveler component and the polymer component adsorbed on the surface of the copper plating film 20 fall off. This is because there is no adsorption due to electrical action, and the physical action of liquid flow works. On the other hand, the brightener component remains adsorbed on the surface of the copper plating film 20 . In addition, the new brightener component may be adsorbed to the portion where the leveler component and polymer component have fallen off. As a result, the surface of the copper plating film 20 is in a state in which a relatively large amount of the brightener component is adsorbed.

When the next electrolysis is performed in this state, a large amount of the brightener component is taken in when new copper is laminated on the copper plating film 20 at the initial stage of the electrolysis. As a result, a layer having a relatively high concentration of the brightener component is formed. Since the brightener component contains sulfur, the layer rich in the brightener component becomes the high sulfur concentration layer 21 .

In conventional electroplating, the plating solution is also sprayed onto the substrate. However, this is intended to agitate the plating solution and to supply metal ions, and is carried out in an energized state. On the other hand, in this embodiment, the copper plating solution is sprayed onto the plating surface in a non-energized state. Thus, the high sulfur concentration layer 21 can be formed for the first time.

The arrangement of the high sulfur concentration layer 21 and the low sulfur concentration layer 22 depends on the arrangement of the electrolysis zone EZ and the spraying zone SZ in the plating bath 40 . The number of low sulfur concentration layers 22 is usually two or more. The number of high sulfur concentration layers 21 may be one or plural. A layer directly laminated on the surface of the substrate 10 (surface of the metal layer 12 ) and a layer appearing on the surface of the copper plating film 20 (the surface opposite to the substrate 10 ) are usually the low sulfur concentration layer 22 .

The copper plating film 20 having such a structure has the property that recrystallization progresses slowly. Although the reason for this is unclear, it is generally believed to be as follows.
The copper plating film 20 has a structure in which a layer having a high sulfur concentration (high sulfur concentration layer 21) and a layer having a low sulfur concentration (low sulfur concentration layer 22) derived from the brightener component of the copper plating solution are alternately laminated. Since recrystallization is inhibited by sulfur in the copper plating film 20, progress of recrystallization of the copper plating film 20 is slowed down.

The concentration of impurities contained in the copper plating film 20 can be measured by secondary ion mass spectrometry (SIMS). The sulfur concentration of the high sulfur concentration layer 21 measured by secondary ion mass spectrometry is preferably 5×10 ¹⁸ atoms/cm ³ or more. The sulfur concentration of the low sulfur concentration layer 22 measured by secondary ion mass spectrometry is preferably less than 5×10 ¹⁸ atoms/cm ³ . If the sulfur concentration is as described above, the progress of recrystallization can be sufficiently slowed down.

Moreover, it is preferable that the copper plating film 20 includes six or more high sulfur concentration layers 21 . If so, the progress of recrystallization can be sufficiently slowed down.

The copper plating film 20 may contain impurities other than sulfur, such as chlorine, carbon, and oxygen derived from additives of the copper plating solution.

Next, an example will be described.
(Recrystallization time measurement test)
First, a recrystallization time measurement test was performed.
A substrate was prepared by the following procedure. A polyimide film (Upilex-35SGAV1 manufactured by Ube Industries, Ltd.) having a thickness of 35 μm was prepared as a base film. The base film was set in a magnetron sputtering device. A nickel-chromium alloy target and a copper target are installed in the magnetron sputtering apparatus. The composition of the nickel-chromium alloy target is 20% by mass of Cr and 80% by mass of Ni. In a vacuum atmosphere, a base metal layer made of a nickel-chromium alloy with a thickness of 25 nm was formed on one side of the base film, and a copper thin film layer with a thickness of 150 nm was formed thereon.

Next, a copper plating solution was prepared. The copper plating solution contains 120 g/L of copper sulfate, 70 g/L of sulfuric acid, 16 mg/L of brightener component, 20 mg/L of leveler component, 1,100 mg/L of polymer component, and 50 mg/L of chlorine component. Bis(3-sulfopropyl)disulfide (reagent manufactured by RASCHIG GmbH) was used as a brightener component. A diallyldimethylammonium chloride-sulfur dioxide copolymer (PAS-A-5 manufactured by Nittobo Medical Co., Ltd.) was used as a leveler component. A polyethylene glycol-polypropylene glycol copolymer (Unilube 50MB-11 manufactured by NOF Corporation) was used as the polymer component. Hydrochloric acid (35% hydrochloric acid manufactured by Wako Pure Chemical Industries, Ltd.) was used as the chlorine component.

A base material was supplied to a plating tank in which the copper plating solution was stored. A copper-plated film having a thickness of 2.0 μm was formed on one side of the substrate by electrolytic plating to obtain a copper-clad laminate. Here, the temperature of the copper plating solution was set at 31°C.

In electroplating, electrolysis and spraying were alternately performed. Here, electrolysis was performed 7 times and spraying was performed 6 times. The current density in the electrolysis was changed as follows. From the start of plating, 0.4 A/dm ² for 40 seconds, 0.4 A/dm ² for 40 seconds, 1.5 A/dm ² for 20 seconds, 3.0 A/dm ² for 45 seconds, 3.0 A/dm ² for 45 seconds, 3.0 A/dm ² for 45 seconds, 3.0 A/dm ² for 45 seconds. The non-energization period between electrolysis is 2 seconds. The copper plating solution was sprayed during this non-energization period. Since the jet of the copper plating solution linearly contacts the plating surface, the time during which the jet contacts a specific portion of the plating surface is shorter than the non-energization period.

The above operation was performed eight times while changing the discharge flow rate of the slit nozzle to 0, 1, 2, 5, 10, 20, 30, and 35 L/min per 100 mm of slit length. The eight copper-clad laminates obtained are referred to as samples 1-8, respectively.

The recrystallization time of the copper plating film was measured for the obtained samples 1 to 8. The recrystallization time was measured by observing the change in resistivity of the copper plating film by the four-probe method. As the recrystallization of the copper plating film progresses, the grain size increases and the resistivity changes. When the resistivity becomes constant, it is determined that the recrystallization is completed. The recrystallization time was defined as the elapsed time from plating to completion of recrystallization. As a resistivity measuring instrument, Loresta AX MCP-T370 manufactured by Mitsubishi Chemical Analytics was used.

Table 1 shows the results.

From Table 1, it can be seen that when spraying is performed (Samples 2 to 8), progress of recrystallization of the copper plating film is slower than when spraying is not performed (Sample 1). Further, it can be seen that the recrystallization time is sufficiently long by setting the discharge flow rate of the slit nozzle to 2 to 30 L/min per 100 mm of slit length.

(Gloss measurement test)
Next, samples 1 to 8 were subjected to a gloss measurement test.
For each of Samples 1 to 8, the glossiness of the surface of the copper plating film immediately after plating was measured. In addition, chemical polishing was performed on each of Samples 1 to 8 one week after the plating treatment, and the glossiness of the surface of the copper plating film after chemical polishing was measured. Furthermore, each of Samples 1 to 8 two weeks after the plating treatment was subjected to chemical polishing, and the glossiness of the surface of the copper plating film after chemical polishing was measured. As a glossiness measuring instrument, VSR400 manufactured by Nippon Denshoku Industries Co., Ltd. was used.

The results are shown in the graph of FIG. The horizontal axis of the graph in FIG. 4 represents the discharge flow rate per 100 mm slit length of the slit nozzle. The vertical axis is the glossiness of the surface of the copper plating film. Glossiness can be used as an index of the surface roughness of the copper plating film. The higher the gloss, the smoother, and the lower the gloss, the rougher.

From the graph in FIG. 4, if the discharge flow rate of the slit nozzle is in the range of 2 to 30 L/min per 100 mm of slit length, the glossiness of 0.8 or more can be maintained even two weeks after plating, and the copper after chemical polishing can be maintained. It was confirmed that the surface of the plating film could be made smooth.

REFERENCE SIGNS LIST 1 copper-clad laminate 10 substrate 11 base film 12 metal layer 13 underlying metal layer 14 copper thin film layer 20 copper plating film 21 high sulfur concentration layer 22 low sulfur concentration layer

Claims (3)

A copper plating film is formed on the surface of the base material by electrolytic plating while conveying the base material by roll-to-roll in a plating bath in which a copper plating solution containing a brightener component containing sulfur is stored. In obtaining a clad laminate,
In the plating bath, an electrolysis zone is provided in which an electric current is passed between the anode and the base material in the direction in which the base material is conveyed to perform electrolysis, and a spraying area is provided in which the copper plating solution is sprayed onto the plating surface in a non-energized state. A method for producing a copper-clad laminate, characterized in that and are alternately provided. Spraying the copper plating solution ejected from a slit nozzle onto the plating surface,
2. The method for manufacturing a copper-clad laminate according to claim 1 , wherein the discharge flow rate of said slit nozzle is 2 to 30 L/min per 100 mm of slit length. 3. The method for producing a copper-clad laminate according to claim 1, wherein the concentration of the brightener component in the copper plating solution is 1-30 mg/L.

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