JP7103006B2 - Copper-clad laminate - Google Patents

Description

The present invention relates to a copper-clad laminate. More specifically, the present invention relates to a copper-clad laminate used in the manufacture of flexible printed wiring boards (FPCs) and the like.

For liquid crystal panels, notebook computers, digital cameras, mobile phones, etc., flexible printed wiring boards having a wiring pattern formed on the surface of a resin film are used. The flexible printed wiring board is manufactured from, for example, a copper-clad laminate.

The metallizing method is known as a method for manufacturing a copper-clad laminate. The production of the copper-clad laminate by the metallizing method is performed, for example, by the following procedure. First, a base metal layer made of a nickel-chromium alloy is formed on the surface of the 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 until the film thickness is suitable for forming the wiring pattern. By the metallizing method, a copper-clad laminate of a type called a so-called two-layer substrate in which a conductor layer is directly formed on a resin film can be obtained.

The semi-additive method is known as a method for manufacturing a flexible printed wiring board using this type of copper-clad laminate. The 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 that forms a wiring pattern. 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. As a result, a flexible printed wiring board can be obtained.

In the semi-additive method, a dry film resist may be used to form a resist layer on the surface of the copper plating film. In this case, after the surface of the copper plating film is chemically polished, a dry film resist is attached. By making fine irregularities on the surface of the copper plating film by chemical polishing, the adhesion of the dry film resist due to the anchor effect is improved. However, if the surface of the copper plating film is excessively uneven, the adhesion of the dry film resist may be deteriorated.

Japanese Unexamined Patent Publication No. 2006-278950

The surface roughness of the copper plating film after chemical polishing is affected by the size of the crystal grains of the copper plating film. 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.

In view of the above circumstances, an object of the present invention is to provide a copper-clad laminate capable of smoothing the surface of a copper-plated coating after chemical polishing.

The copper-clad laminate of the present invention is formed on the surface of the base film, the metal layer formed on the surface of the base film, and the surface of the metal layer, and the chlorine concentration measured by the secondary ion mass analysis method is 1 × 10. A copper-plated coating having a layer of ¹⁹ atoms / cm ³ or more is provided, and the average particle size of the crystal grains of the copper-plated coating is 300 nm or less .

According to the present invention, since the particle size of the crystal grains of the copper plating film is 300 nm or less, the crystal grains are sufficiently small and the surface of the copper plating film after chemical polishing can be smoothed.

It is sectional drawing of the copper-clad laminate which concerns on one Embodiment of this invention. It is a perspective view of a plating apparatus. It is a top view of a plating tank. FIG. (A) is a graph showing the chlorine concentration distribution of the copper plating film in Example 1. FIG. (B) is a graph showing the chlorine concentration distribution of the copper plating film in Example 2. FIG. (A) is a graph showing the chlorine concentration distribution of the copper plating film in Comparative Example 1. FIG. (B) is a graph showing the chlorine concentration distribution of the copper plating film in Comparative Example 1. FIG. (A) is an SEM image of a cross section of the copper-clad laminate in Example 1. FIG. (B) is an SEM image of a cross section of the copper-clad laminate in Example 2. FIG. (A) is an SEM image of a cross section of the copper-clad laminate in Comparative Example 1. FIG. (B) is an SEM image of a cross section of the copper-clad laminate in Comparative Example 2. FIG. (A) is an SEM image of the surface of the copper plating film after chemical polishing in Example 1. FIG. (B) is an SEM image of the surface of the copper plating film after chemical polishing in Example 2. FIG. (A) is an SEM image of the surface of the copper plating film after chemical polishing in Comparative Example 1. FIG. (B) is an SEM image of the surface of the copper plating film after chemical polishing in Comparative Example 1.

Next, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the copper-clad laminate 1 according to the embodiment of the present invention comprises a base material 10 and a copper plating film 20 formed on the surface of the base material 10. As shown in FIG. 1, the copper plating film 20 may be formed on only one side of the base material 10, or the copper plating film 20 may be formed on both sides of the base material 10.

The base material 10 has a metal layer 12 formed 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, for example, a sputtering method. The metal layer 12 is composed of a base metal layer 13 and a copper thin film layer 14. The base metal layer 13 and the copper thin film layer 14 are laminated in this order on the surface of the base film 11. Generally, the base metal layer 13 is made 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.

The 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-plated coating 20 has an average particle size of 300 nm or less. Since the crystal grains are sufficiently small, the surface of the copper plating film 20 after chemical polishing can be smoothed. The surface roughness of the copper plating film 20 after chemical polishing is affected by the size of the crystal grains of the copper plating film 20. The smaller the crystal grains, the smoother the surface of the copper plating film 20 after chemical polishing, and the larger the crystal grains, the rougher the surface of the copper plating film 20 after chemical polishing. The reason for this is unknown, but it is thought to be as follows. Etching is less likely to proceed at the grain boundaries than within the crystal grains. Therefore, the size of the crystal grains is reflected in the surface roughness of the copper plating film 20 after chemical polishing. As a result, the smaller the crystal grains, the smoother the surface of the copper plating film 20 after chemical polishing.

The average particle size of the crystal grains of the copper plating film 20 is preferably 100 nm or more. Generally, in the coating film formed by copper plating, the crystal grains gradually increase as the recrystallization progresses. Therefore, it is difficult to maintain fine crystal grains having an average particle diameter of less than 100 nm. A copper-plated coating 20 composed of crystal grains having an average particle diameter of 100 nm or more can be stably produced.

The copper plating film 20 is formed by electrolytic plating. The copper plating film 20 is not particularly limited, but is formed by the plating apparatus 3 shown in FIG.
The plating device 3 is a device that performs electrolytic plating on the base material 10 while transporting the long strip-shaped base material 10 by roll-to-roll. The plating device 3 includes a supply device 31 for feeding out the base material 10 wound in a roll shape, and a winding device 32 for winding up the base material 10 (copper-clad laminate 1) after plating in a roll shape.

Further, the plating apparatus 3 has a pair of upper and lower endless belts 33 (the lower endless belt 33 is not shown) that conveys the base material 10. Each endless belt 33 is provided with a plurality of clamps 34 for gripping the base material 10. The base material 10 unwound from the supply device 31 is in a suspended posture in the width direction along the vertical direction, and both edges are gripped by the upper and lower clamps 34. The base material 10 circulates in the plating device 3 by driving the endless belt 33, is released from the clamp 34, and is wound by the winding device 32.

A pretreatment tank 35, a plating tank 40, and a posttreatment tank 36 are arranged in 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 the surface of the base material 10 by electrolytic plating. As a result, a long strip-shaped copper-clad laminate 1 can be obtained.

As shown in FIG. 3, the plating tank 40 is a single horizontally long tank along the transport direction of the base material 10. The base material 10 is conveyed along the center of the plating tank 40. A copper plating solution is stored in the plating tank 40. The entire base material 10 conveyed in the plating tank 40 is immersed in a copper plating solution.

The copper plating solution contains a water-soluble copper salt. Any water-soluble copper salt generally used in the copper plating solution is used without particular limitation. Examples of the water-soluble copper salt include an inorganic copper salt, an alkane sulfonic acid copper salt, an alkanol sulfonic acid copper salt, and an organic acid copper salt. Examples of the inorganic copper salt include copper sulfate, copper oxide, copper chloride, and copper carbonate. Examples of the alkane sulfonic acid copper salt include copper methanesulfonate and copper propanesulfonate. Examples of the alkanol sulfonate copper salt include copper isethionic acid and copper propanol sulfonate. Examples of the organic acid copper salt include copper acetate, copper citrate, and copper tartrate.

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

The copper plating solution contains additives that are generally added to the plating solution. Examples of the additive include a leveler component, a polymer component, a brightener component, a chlorine component and the like. As the additive, one type selected from a leveler component, a polymer component, a brightener component, a chlorine component and the like may be used alone, or two or more types may be used in combination.

The leveler component is composed of nitrogen-containing amines and the like. Examples of the leveler component include diallyldimethylammonium chloride and Janus Green B. 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 Brightener component is not particularly limited, but one type selected from bis (3-sulfopropyl) disulfide (abbreviated as SPS), 3-mercaptopropane-1-sulfonic acid (abbreviated as MPS), etc. may be used alone or as two types. It is preferable to use the above in combination. The chlorine component is not particularly limited, but it is preferable to use one selected from hydrochloric acid, sodium chloride and the like alone or in combination of two or more.

The content of each component of the copper plating solution can be arbitrarily selected. However, the copper plating solution preferably contains 60 to 280 g / L of copper sulfate 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 a leveler component of 0.5 to 50 mg / L. Then, the protrusions can be suppressed and the flat copper plating film 20 can be formed. The copper plating solution preferably contains a polymer component of 10 to 1,500 mg / L. Then, the current concentration on the end portion of the base material 10 can be relaxed and a uniform copper plating film 20 can be formed. The copper plating solution preferably contains a Brightener component of 0.2 to 16 mg / L. Then, 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 a chlorine component of 20 to 80 mg / L. Then, abnormal precipitation can be suppressed. Further, since the copper plating solution contains a chlorine component, the formed copper plating film 20 contains chlorine as an impurity.

The temperature of the copper plating solution is preferably 20 to 35 ° C. Further, 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 a means using a jet can be used. For example, the copper plating solution can be agitated by spraying the copper plating solution ejected from the nozzle onto the base material 10.

Inside the plating tank 40, a plurality of anodes 41 are arranged along the transport direction of the base material 10. Further, the clamp 34 that grips the base material 10 also has a function as a cathode. By passing an electric current between the anode 41 and the clamp 34 (cathode), the copper plating film 20 can be formed on the surface of the base material 10.

In the plating tank 40 shown in FIG. 3, anodes 41 are arranged on both the front and back sides of the base material 10. Therefore, if the base material 10 having the metal layers 12 formed on both sides of the base film 11 is used, the copper plating film 20 can be formed on both sides of the base film 10.

A rectifier is connected to each of the plurality of anodes 41 arranged inside the plating tank 40. Therefore, the current density can be set to be different for each anode 41. In the present embodiment, the inside of the plating tank 40 is divided into a plurality of areas along the transport direction of the base material 10. Each area corresponds to an area in which one or more contiguous anodes 41 are located.

Each zone is a low current density zone LZ or a high current density zone HZ. In the low current density area LZ, the current density is set to zero or a relatively low "low current density", and the base material 10 is electrolytically plated at a low current density. In the high current density area HZ, the current density is set to "high current density", which is higher than the low current density, and the base material 10 is electrolytically plated at a high current density.

Here, it is preferable to set the current density (low current density) in the low current density area LZ to 0 to 0.29 A / dm ² . Further, it is preferable to set the current density (high current density) in the high current density area HZ to 0.3 to 10 A / dm ² .

The low current density area LZ and the high current density area HZ are alternately provided along the transport direction of the base material 10. The number of low current density areas LZ may be one or plural. The number of high current density areas HZ may be one or plural. The most upstream area may be the low current density area LZ or the high current density area HZ with reference to the transport direction of the base material 10. Further, the most downstream area may be a low current density area LZ or a high current density area HZ.

When a plurality of low current density areas LZ are arranged in the plating tank 40, the current densities in the plurality of low current density areas LZ may be the same or different. Further, when a plurality of high current density areas HZ are arranged in the plating tank 40, the current densities in the plurality of high current density areas HZ may be the same or different. However, it is preferable that the current density in the high current density area HZ is set so as to gradually increase toward the downstream side in the transport direction of the base material 10.

The base material 10 is electroplated while alternately passing through the low current density area LZ and the high current density area HZ. That is, in the plating tank 40, electrolytic plating at a low current density and electrolytic plating at a high current density are alternately and repeatedly performed on the base material 10. As a result, the copper plating film 20 is formed.

As shown in FIG. 1, the copper plating film 20 formed by such a method has a structure in which a plurality of layers formed by electrolytic plating at different current densities are laminated. Specifically, the copper plating film 20 has a structure in which high chlorine concentration layers 21 and low chlorine concentration layers 22 are alternately laminated in the thickness direction. Here, the high chlorine concentration layer 21 is formed by electrolytic plating at a low current density, and has a relatively high chlorine concentration. Further, the low chlorine concentration layer 22 is formed by electrolytic plating at a high current density, and the chlorine concentration is relatively low. It is presumed that this is because the lower the current density in electrolytic plating, the easier it is for the additive of the copper plating solution to be incorporated into the plating film.

The arrangement of the high chlorine concentration layer 21 and the low chlorine concentration layer 22 depends on the arrangement of the low current density area LZ and the high current density area HZ in the plating tank 40. The number of high chlorine concentration layers 21 may be one or plural. The number of low chlorine concentration layers 22 may be one or plural. The layer directly laminated on the surface of the base material 10 (the surface of the metal layer 12) may be the high chlorine concentration layer 21 or the low chlorine concentration layer 22. Further, the layer appearing on the surface of the copper plating film 20 (the surface opposite to the base material 10) may be the high chlorine concentration layer 21 or the low chlorine concentration layer 22.

The concentration of impurities contained in the copper plating film 20 can be measured by secondary ion mass spectrometry (SIMS). The chlorine concentration measured by the secondary ion mass spectrometry of the high chlorine concentration layer 21 is preferably 1 × 10 ¹⁹ atoms / cm ³ or more. The chlorine concentration measured by the secondary ion mass spectrometry of the low chlorine concentration layer 22 is preferably less than 1 × 10 ¹⁹ atoms / cm ³ .

In general, the crystal grains of the copper plating film 20 gradually increase in size as the recrystallization progresses after the plating treatment. On the other hand, in the copper plating film 20 of the present embodiment, stress relaxation is divided by the high chlorine concentration layer 21, and the progress of recrystallization is suppressed. Therefore, the crystal grains of the copper plating film 20 can be maintained as fine. Specifically, the average particle size of the crystal grains can be maintained at 300 nm or less.

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

Next, an embodiment will be described.
(Example 1)
The substrate was prepared by the following procedure. As a base film, a polyimide film having a thickness of 35 μm (Upilex-35SGAV1 manufactured by Ube Corporation) was prepared. The base film was set in the magnetron sputtering apparatus. 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. Under a vacuum atmosphere, a base metal layer made of a nickel-chromium alloy having a thickness of 25 nm was formed on one side of the base film, and a copper thin film layer having a thickness of 100 nm was formed on the base metal layer.

Next, the copper plating solution was adjusted. The copper plating solution contains 120 g / L of copper sulfate, 70 g / L of sulfuric acid, 20 mg / L of leveler component, 1,100 mg / L of polymer component, 16 mg / L of Brightener component, and 50 mg / L of chlorine 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 a polymer component. Bis (3-sulfopropyl) disulfide (reagent manufactured by RASCHIG GmbH) was used as the Brightener component. Hydrochloric acid (35% hydrochloric acid manufactured by Wako Pure Chemical Industries, Ltd.) was used as the chlorine component.

The base material was supplied to the plating tank in which the copper plating solution was stored. A copper plating film having a thickness of 2.0 μm was formed on one side of the base material by electrolytic plating to obtain a copper-clad laminate. Here, the temperature of the copper plating solution was set to 31 ° C. Further, during the electrolytic plating, the copper plating solution ejected from the nozzle was sprayed substantially perpendicular to the surface of the base material to stir the copper plating solution.

In electroplating, the current density was changed so that the idle feeding period was included 11 times. Here, the airborne period means a period during which electrolytic plating is performed at a low current density, specifically 0.0 A / dm ² . The current density (high current density) other than the airborne period was set to 1.2 A / dm ² .

(Example 2)
A copper-clad laminate was obtained in the same procedure as in Example 1. However, in electrolytic plating, the current density was changed so that the idle feeding period was included 7 times. The other conditions are the same as in Example 1.

(Comparative Example 1)
A copper-clad laminate was obtained in the same procedure as in Example 1. However, in electrolytic plating, the current density was set to 3.2 A / dm ² , and no airborne period was provided. The other conditions are the same as in Example 1.

(Comparative Example 2)
A copper-clad laminate was obtained in the same procedure as in Example 1. However, in electrolytic plating, the current density was set to 0.33 A / dm ² , and no airborne period was provided. The other conditions are the same as in Example 1.

(Chlorine concentration measurement)
The chlorine concentration of the copper plating film was measured with respect to the copper-clad laminates obtained in Examples 1 and 2 and Comparative Examples 1 and 2. The measurement was performed by secondary ion mass spectrometry. A quadrupole secondary ion mass spectrometer (PHI ADEPT-1010) manufactured by ULVAC FI Co., Ltd. was used as the measuring device. The measurement conditions were Cs ⁺ for the primary ion species, 5.0 kV for the primary acceleration voltage, and 96 × 96 μm for the detection region. The chlorine concentration value in the present specification is based on the value measured under the above conditions.

FIG. 4A shows the measurement results of the copper-clad laminate obtained in Example 1. FIG. 4B shows the measurement results of the copper-clad laminate obtained in Example 2. FIG. 5A shows the measurement results of the copper-clad laminate obtained in Comparative Example 1. FIG. 5B shows the measurement results of the copper-clad laminate obtained in Comparative Example 2. The horizontal axis of each graph is the position in the thickness direction of the copper plating film. 0.0 μm is the surface on the copper thin film layer side, and 2.0 μm is the surface. The vertical axis is the chlorine concentration.

As can be seen from the graph of FIG. 4A, in Example 1, the chlorine concentration distribution in the thickness direction of the copper plating film is a distribution having 10 periodic peaks. The peak around 0.2 μm corresponds to the first two airborne periods. The remaining nine peaks correspond to the subsequent nine airborne periods. The chlorine concentration of each peak is 1 × 10 ¹⁹ atoms / cm ³ or more. The lower limit between peaks is less than 1 × 10 ¹⁹ atoms / cm ³ . Therefore, it can be said that this copper plating film has a structure in which high chlorine concentration layers and low chlorine concentration layers are alternately laminated. Further, it can be said that this copper plating film contains 10 layers having a high chlorine concentration.

As can be seen from the graph of FIG. 4B, in Example 2, the chlorine concentration distribution in the thickness direction of the copper plating film has six periodic peaks. The peak around 0.2 μm corresponds to the first two airborne periods. The remaining 5 peaks correspond to the following 5 airborne periods. The chlorine concentration of each peak is 1 × 10 ¹⁹ atoms / cm ³ or more. The lower limit between peaks is less than 1 × 10 ¹⁹ atoms / cm ³ . Therefore, it can be said that this copper plating film has a structure in which high chlorine concentration layers and low chlorine concentration layers are alternately laminated. Further, it can be said that this copper plating film contains 6 layers having a high chlorine concentration.

As can be seen from the graph of FIG. 5A, in Comparative Example 1, the chlorine concentration is low over the entire thickness direction of the copper plating film. Specifically, the chlorine concentration is less than 1 × 10 ¹⁹ atoms / cm ³ overall. Therefore, this copper plating film does not have a structure in which high chlorine concentration layers and low chlorine concentration layers are alternately laminated.

As can be seen from the graph of FIG. 5B, in Comparative Example 2, the chlorine concentration is higher in the entire thickness direction of the copper plating film than in Comparative Example 1. This copper plating film does not have a structure in which high chlorine concentration layers and low chlorine concentration layers are alternately laminated, but contains chlorine in a high concentration as a whole.

(Crystal grains)
The cross sections of the copper-clad laminates obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were observed 7 days after the plating treatment. FIG. 6A shows an SEM image of the cross section of Example 1. FIG. 6B shows an SEM image of the cross section of Example 2. FIG. 7A shows an SEM image of the cross section of Comparative Example 1. FIG. 7B shows an SEM image of the cross section of Comparative Example 2. From these SEM images, it can be seen that the crystal grains of the copper plating film in Examples 1 and 2 are finer than those in Comparative Examples 1 and 2.

Using each SEM image, the average particle size of the crystal grains of the copper plating film was determined. The procedure is as follows. First, the SEM image is image-processed to identify each of the crystal grains contained in the copper plating film. Next, the diameter equivalent to a circle is obtained from the area of each crystal grain. Next, the calculated frequency distribution of the diameter is obtained. Here, the series is divided in increments of 10 nm, and the number frequency in each series is obtained. Next, the diameter of each class is converted into an area, and the area is multiplied by the number frequency to obtain the area frequency. The average particle size is obtained from the obtained area frequency.

The results are shown in Table 1. It was confirmed that the average particle size of the crystal grains in Examples 1 and 2 was smaller than that in Comparative Examples 1 and 2. It is considered that the reason why the crystal grains are small in Examples 1 and 2 is that the copper plating film has a structure in which high chlorine concentration layers and low chlorine concentration layers are alternately laminated. It is presumed that the inclusion of the high chlorine concentration layer in the copper plating film suppresses the progress of recrystallization and keeps the crystal grains fine.

In Example 1, the average particle size of the crystal grains is smaller than that in Example 2. The copper plating film of Example 1 contains 10 high chlorine concentration layers, and the copper plating film of Example 2 contains 6 high chlorine concentration layers. From this, it can be said that the larger the number of high chlorine concentration layers contained in the copper plating film, the smaller the average particle size of the crystal grains.

(Surface roughness)
The surface roughness of the copper-plated coating before chemical polishing was measured with respect to the copper-clad laminates obtained in Examples 1 and 2 and Comparative Examples 1 and 2. Here, a laser microscope VK-9510 manufactured by KEYENCE was used for measuring the surface area ratio. The surface area ratio was determined from the measured surface area of the measurement area of 70 × 93 μm.

The results are shown in Table 1. The surface roughness before chemical polishing is almost the same in Examples 1 and 2 and Comparative Example 1. The surface of Comparative Example 2 is slightly rougher than that of Examples 1 and 2 and Comparative Example 1.

Next, each copper-clad laminate was chemically polished. As the chemical polishing solution, a solution containing sulfuric acid and hydrogen peroxide as main components (a solution obtained by diluting CPE-750 manufactured by Mitsubishi Gas Chemical Company, Inc. 10-fold) was used. The copper plating film having a thickness of 2 μm was reduced to 0.5 μm. After chemical polishing, the surface roughness of the copper plating film was measured.

The results are shown in Table 1. It can be seen that in Examples 1 and 2, there is almost no change in the surface roughness before and after the chemical polishing. On the other hand, in Comparative Examples 1 and 2, it can be seen that the surface of the copper plating film after chemical polishing is rough. It can be confirmed that in Examples 1 and 2, the surface of the copper plating film after chemical polishing is smoother than that in Comparative Examples 1 and 2.

The surface of the copper-plated coating after chemical polishing was observed for each copper-clad laminate. FIG. 8A is an SEM image of Example 1. FIG. 8B is an SEM image of Example 2. FIG. 9A is an SEM image of Comparative Example 1. FIG. 9B is an SEM image of Comparative Example 2. From these SEM images, it can be seen that the surface of the copper plating film after chemical polishing is smoother in Examples 1 and 2 than in Comparative Examples 1 and 2.

As can be seen from Table 1, in Example 2 in which the average particle size of the crystal grains of the copper plating film is 251 nm, it can be said that the surface of the copper plating film after chemical polishing is smooth. On the other hand, in Comparative Example 2 in which the average particle size of the crystal grains of the copper plating film is 376 nm, the surface of the copper plating film after chemical polishing is rough. From this, it is considered that if the average particle size of the crystal grains of the copper plating film is 300 nm or less, the surface of the copper plating film after chemical polishing can be smoothed.

1 Copper-clad laminate 10 Base film 11 Base film 12 Metal layer 13 Base metal layer 14 Copper thin film layer 20 Copper plating film 21 High chlorine concentration layer 22 Low chlorine concentration layer

Claims (2)

With the base film
The metal layer formed on the surface of the base film and
A copper plating film formed on the surface of the metal layer and having a layer having a chlorine concentration of 1 × 10 ¹⁹ atoms / cm ³ or more measured by secondary ion mass spectrometry is provided.
A copper-clad laminate characterized in that the average particle size of the crystal grains of the copper plating film is 300 nm or less. The copper plating film has a high chlorine concentration layer having a chlorine concentration of 1 × 10 ¹⁹ atoms / cm ³ or more measured by the secondary ion mass analysis method and a chlorine concentration of 1 × 10 measured by the secondary ion mass analysis method. The copper-clad laminate according to claim 1, wherein low chlorine concentration layers having a concentration of less than ¹⁹ atoms / cm ³ are alternately laminated.

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