JP6225467B2 - Copper foil for printed wiring board, method for producing the same, and printed wiring board using the copper foil - Google Patents

Description

  The present invention relates to a copper foil for a printed wiring board, and more particularly to a copper foil for a printed wiring board used for an electronic device or the like, a method for producing the same, and a printed wiring board using the copper foil.

  In recent years, miniaturization of the wiring pattern of a printed wiring board is strongly demanded as electronic devices become smaller, lighter, and more functional. The printed wiring board is used for, for example, a semiconductor mounting board, a motherboard board, and the like.

  Conventionally, a subtractive method and a semi-additive method are known as methods for forming a copper wiring pattern on a printed wiring board.

  In the subtractive method, first, a copper foil is laminated on the surface of an insulating substrate. Next, a resist layer is formed on the surface of the copper foil, and a pattern is formed on the resist layer by photolithography. Next, a copper wiring pattern is formed by removing a portion of the copper foil not covered with the resist layer by etching.

  In the semi-additive method, first, a thin metal layer called a seed layer is formed on the surface of an insulating substrate. Next, a resist layer is formed on the surface of the seed layer, and a pattern is formed on the resist layer by photolithography. Next, a copper wiring pattern is formed by performing electrolytic copper plating on a portion of the seed layer not covered with the resist layer. The portion of the seed layer that has not been plated with copper is removed by etching.

  In the semi-additive method, when the seed layer is formed of an electrolytic copper foil or a rolled copper foil, a roughening treatment is performed on one surface of the copper foil (the surface on the side in contact with the insulating substrate). When the surface of the copper foil is roughened, fine convex portions are formed on the surface of the copper foil. When this convex part enters the inside of an insulating base material, a physical anchor effect is exhibited and copper foil is firmly adhere | attached on the surface of an insulating base material.

  However, the conventional printed wiring board has the following problems. In the semi-additive method, when the degree of roughening of the surface of the copper foil is large, the convex portion on the surface of the copper foil penetrates deeply into the insulating base material. In this case, the etching time required to remove the copper foil (seed layer) from the surface of the insulating base becomes long. Further, as a result of the longer etching time, the amount of reduction in the line width of the copper wiring pattern becomes larger, so that it becomes difficult to form a fine copper wiring pattern.

  On the other hand, when the degree of roughening of the surface of the copper foil (seed layer) is too small, the adhesion between the copper foil and the insulating base material is deteriorated, so that the copper foil is easily peeled off from the surface of the insulating base material. It becomes difficult to form a copper wiring pattern.

  The following techniques are known as conventional techniques related to the surface roughness of copper foil. Patent Document 1 describes a copper foil having a surface roughness of 1 to 3 μm. The surface of this copper foil is provided with a minute tear-drop-shaped hump having a length of 0.6 to 1.0 μm and a maximum diameter of 0.2 to 0.8 μm. Patent Document 2 includes a roughening treatment layer made of spherical fine particles having a surface roughness (Rz: 10-point average roughness) of 2.5 μm or less and a diameter of 0.05 to 1.0 μm. A copper foil having a rust-preventing layer composed of at least one of Mo, Ni, W, P, Co, and Ge on the chemical treatment layer and having a silane coupling layer is described. Patent Document 3 describes a copper foil having a surface roughness (Rz) of 2.5 μm or less, a minimum peak-to-peak distance of the ground mountain of 5 μm or more, and crystal grains having an average grain size of 2 μm or less on the surface. Has been. Patent Document 4 describes a copper foil containing fine copper particles having a protrusion shape with a vertex angle θ of 85 degrees or less. In Patent Document 5, the arithmetic average roughness based on a surface magnified 1000 times by an electron beam three-dimensional roughness analyzer is 0.05 to 0.8 μm, and the surface area alternative value is 1.005 to 1.5. A copper or copper alloy material of 08 is described.

Japanese Patent Laid-Open No. 07-231152 JP 2006-210689 A JP 2004-263300 A JP 2010-236058 A Japanese Patent Laid-Open No. 10-265872

  However, when the copper foils disclosed in Patent Documents 1 to 5 are bonded to an insulating base material, the present inventors remove the copper foil because the convex portions on the surface of the copper foil penetrate deeply into the insulating base material. It has been found that the etching time required for this is increased. As a result, since the amount of reduction in the line width of the copper wiring pattern becomes large, it is difficult to form a fine copper wiring pattern.

  The present invention provides a copper foil for a printed wiring board that has good adhesion to an insulating base material and can be easily removed from the surface of the insulating base material by etching, and a printed wiring board using the copper foil. The purpose is to provide.

The present invention is as follows.
1. At least one surface has the following formula (1):
E = surface area of copper foil / ten-point average roughness of copper foil surface (1)
(The surface area of the copper foil is the surface area per unit area of 1 μm length × 1 μm width of the copper foil, and the surface area of the copper foil is a value obtained when the surface of the copper foil is observed with a scanning tunneling microscope. )
The copper foil for printed wiring boards whose value of the adhesion improvement coefficient E represented by is 2.5-8.
2. 2. The copper foil for printed wiring board according to 1 above, wherein the surface of the copper foil is etched.
3. The following formula (2):
Etching amount [μm] = (mass of copper foil before etching−mass of copper foil after etching) / (etching area × copper density) (2)
(Wherein the density of copper is 8.96 g / cm ³ )
The copper foil for printed wiring boards according to 2 above, wherein the etching amount of the surface of the copper foil represented by 2 is 1 μm or less.
4). 4. The copper foil for printed wiring boards according to 2 or 3 above, wherein the liquid composition used for the etching treatment contains one or more selected from the group consisting of hydrogen peroxide, sulfuric acid, halogen ions, and tetrazoles.
5. The copper foil for printed wiring boards according to any one of 1 to 4 above, wherein the surface of the copper foil is not treated with a metal other than copper, a silane coupling agent, or an adhesive.
6). An insulating substrate;
The copper foil for a printed wiring board according to any one of the above 1 to 5, laminated on the surface of the insulating substrate,
A copper-clad laminate comprising:
7). A printed wiring board comprising the copper-clad laminate as described in 6 above.
8). 8. The printed wiring board as described in 7 above, wherein a wiring pattern is formed by a semi-additive method.
9. 8. The printed wiring board as described in 7 above, wherein a wiring pattern is formed by a subtractive method.
10. 10. The printed wiring board according to 8 or 9 above, wherein a line width of the wiring pattern is 20 μm or less.
11. At least one surface of the copper foil has the following formula (1):
E = surface area of copper foil / ten-point average roughness of copper foil surface (1)
(The surface area of the copper foil is the surface area per unit area of 1 μm length × 1 μm width of the copper foil, and the surface area of the copper foil is a value obtained when the surface of the copper foil is observed with a scanning tunneling microscope. )
The manufacturing method of the copper foil for printed wiring boards which etches until the value of the contact | adherence improvement coefficient E represented by becomes 2.5-8.
12 12. The method for producing a copper foil for a printed wiring board according to 11 above, wherein the liquid composition used for the etching treatment contains one or more selected from the group consisting of hydrogen peroxide, sulfuric acid, halogen ions, and tetrazoles. .
13. The etching liquid composition comprises
0.2 to 1.5 mass% hydrogen peroxide,
0.5-3.0% by weight sulfuric acid,
0.3 to 3 ppm of halogen ions;
13. The method for producing a copper foil for printed wiring board according to the above 12, comprising 0.01 to 0.3% by mass of tetrazole.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness with an insulating base material is favorable, and the copper foil for printed wiring boards which can be easily removed from the surface of an insulating base material by etching, and the printed wiring using the copper foil Board can be provided.

The three-dimensional image (x30000) of the copper foil surface of Example 1. FIG. The three-dimensional image (x30000) of the copper foil surface of the comparative example 1. The electron microscope image (* 2000) of the wiring cross section of Example 1. FIG. The electron microscope image (* 2000) of the wiring cross section of the comparative example 1. FIG.

  Generally, a printed wiring board used for an electronic device or the like includes a copper-clad laminate in which a copper foil is laminated on the surface of an insulating base material.

  As the insulating base material, for example, a base material obtained by impregnating glass fiber with an epoxy resin or a base material obtained by impregnating a paper base material with a phenol resin is used. These substrates are sometimes referred to as prepregs. A prepreg refers to a semi-cured base material obtained by impregnating glass fiber or the like with an epoxy resin (varnish).

  As the copper foil, electrolytic copper foil, rolled copper foil or the like is used. Electrolytic copper foil is a copper cathode electrolyte flowed between a drum-shaped rotating cathode and an anode disposed along the rotating cathode, and then copper is electrolytically deposited on the surface of the rotating cathode. It is a copper foil produced by continuously peeling the copper from the rotating cathode. On the other hand, the rolled copper foil is a copper foil produced by rolling a lump of copper obtained by casting or the like.

  In the copper foil for printed wiring board of the present invention, the surface on the side in contact with the insulating base material is densely roughened by etching. The liquid composition used for the etching process (etching liquid composition) preferably contains one or more selected from the group consisting of hydrogen peroxide, sulfuric acid, halogen ions, and tetrazoles, and further contains water. Is preferred.

  The concentration of hydrogen peroxide in the etching liquid composition is preferably 0.2 to 1.5% by mass, more preferably 0.3 to 1.2% by mass, and further 0.4 to 1.0% by mass. 0.5 to 0.8% by mass is preferable. An etching liquid composition prepared so that the concentration of hydrogen peroxide is in such a range has a high copper dissolution rate and is economically excellent.

  The concentration of sulfuric acid in the etching liquid composition is preferably 0.5 to 3.0% by mass, more preferably 0.5 to 2.5% by mass, further preferably 0.7 to 2.0% by mass, 1.0-1.8 mass% is the most preferable. The liquid composition for etching prepared so that the concentration of sulfuric acid is in such a range has a high dissolution rate of copper and is economically excellent.

  Halogen ions have the effect of roughening the surface of the copper foil. By roughening the surface of the copper foil using a liquid composition for etching containing halogen ions, the adhesion of the copper foil to the insulating substrate can be enhanced.

  As the halogen ions, one or more selected from the group consisting of fluorine ions, chloride ions, bromine ions, and iodine ions can be used. Among these, a chloride ion or a bromine ion is preferable.

  The concentration of halogen ions in the etching liquid composition is preferably 0.3 to 3 ppm, more preferably 0.5 to 2.5 ppm, and most preferably 0.7 to 2 ppm.

  Tetrazoles have the effect of roughening the surface of the copper foil densely when used in combination with halogen ions. Therefore, the adhesiveness of the copper foil to the insulating substrate can be further increased by roughening the surface of the copper foil using the etching liquid composition containing tetrazole.

  Tetrazoles contained in the etching liquid composition are 1H-tetrazole, 1-methyltetrazole, 1-ethyltetrazole, 5-methyltetrazole, 5-ethyltetrazole, 5-aminotetrazole, 5-n-propyltetrazole, 5- Mercaptotetrazole, 5-mercapto-1-methyltetrazole, 1,5-dimethyltetrazole, 1,5-diethyltetrazole, 1-methyl-5-ethyltetrazole, 1-ethyl-5-methyltetrazole, 1-isopropyl-5- It is preferably at least one selected from the group consisting of methyltetrazole and 1-cyclohexyl-5-methyltetrazole. More preferably, 1H-tetrazole, 5-methyltetrazole, 5-ethyltetrazole, 5-mercapto-1-methyltetrazole, 1,5-dimethyltetrazole, 1,5-diethyltetrazole, and 1-ethyl-5-methyltetrazole It is 1 or more types selected from the group which consists of.

  The concentration of tetrazole in the etching liquid composition is preferably 0.01 to 0.3% by mass, more preferably 0.05 to 0.25% by mass, and most preferably 0.1 to 0.2% by mass. .

  The surface of the copper foil is etched using the etching liquid composition described above. The etching method is not particularly limited, and for example, a known method such as a spray method or an immersion method can be used.

The etching amount of the copper foil is preferably 1 μm or less, more preferably 0.1 to 1 μm, further preferably 0.2 to 0.9 μm, and 0.3 to 0.7 μm. Most preferred. If the etching amount is within the above range, the amount of the copper foil that sinks into the insulating base material when the insulating base material and the etched copper foil are laminated can be reduced. It becomes easy to remove by etching in a later process. The etching amount of the copper foil is a value represented by the following formula (2).
Etching amount [μm] = (mass of copper foil before etching−mass of copper foil after etching) / (etching area × copper density) (2)
(In the formula, the density of copper is 8.96 g / cm ^3. )
The “etching amount” in the present invention refers to the average depth of the entire etched copper foil surface, not the depth of individual portions of the etched copper foil.

  The thickness of the copper foil is not particularly limited, but is preferably 3 to 35 μm, and more preferably 5 to 30 μm. When the thickness of the copper foil is within this range, the handleability of the copper foil is good.

  The surface of the copper foil that is in contact with the insulating base material is preferably not treated with a metal other than copper, a silane coupling agent, or an adhesive (primer). The surface of the copper foil of the present invention is densely roughened. For this reason, the copper foil of the present invention can be firmly bonded to the insulating base material without being surface-treated with a metal other than copper, a silane coupling agent, an adhesive, or the like.

In the copper foil for printed wiring board of the present invention, the value of the adhesion improvement coefficient E of the surface in contact with the insulating substrate is 2.5-8. The adhesion improvement coefficient E is preferably 2.7 to 7.5, more preferably 2.9 to 7, and most preferably 3 to 6.5. If the adhesion improvement coefficient E is in the above range, fine irregularities are formed on the surface of the copper foil, and the adhesion to the insulating substrate can be improved. The adhesion improvement coefficient E is a value represented by the following formula (1).
E = surface area C of the copper foil / ten-point average roughness D of the surface of the copper foil D (1)
(The surface area C of the copper foil is a surface area per unit region of 1 μm length × 1 μm width of the copper foil, and the surface area of the copper foil is a value obtained when the surface of the copper foil is observed with a scanning tunneling microscope. )

The surface area C [μm ² ] of the copper foil is equal to a value obtained by dividing the surface area when the unevenness in a predetermined area on the surface of the copper foil is taken into account by the surface area when the area is assumed to be flat. For example, the surface area C [μm ² ] of the copper foil is the surface area when the unevenness in the region of 5 μm length × 5 μm width of the copper foil surface is considered, and the surface area when the region is assumed to be flat (that is, It is equal to the value divided by 5 × 5 = 25).

  The ten-point average roughness D [μm] of the surface of the copper foil is defined as a ten-point average roughness Rzjis in JIS B 0601. Ten-point average roughness Rzjis means that only the reference length is extracted from the roughness curve in the direction of the average line, and measured from the average line of this extracted portion in the direction of the vertical magnification, from the highest peak to the fifth peak. The sum of the average value of the absolute values of the altitude (Yp) and the average value of the absolute values of the altitudes (Yv) of the bottom valley from the lowest valley bottom to the fifth, and this value is expressed in micrometers. .

The surface area C [μm ² ] of the copper foil in the above formula (1) is a surface area in consideration of unevenness on the surface of the copper foil. Therefore, as the surface of the copper foil is denser, the surface area C of the copper foil tends to increase. Here, “dense” refers to a state in which each of the convex portions on the surface of the copper foil is minute and the convex portions are densely packed.

The surface area C [μm ² ] of the copper foil is preferably a value calculated on the basis of the three-dimensional shape data after obtaining the three-dimensional shape data by observing the surface of the copper foil with a scanning tunneling microscope. . The surface area C [μm ² ] of the copper foil is preferably a value obtained when the surface of the copper foil is enlarged 30000 times with a scanning tunneling microscope.

  The scanning tunnel microscope is a type of microscope that detects a tunnel current flowing between a metal probe and a sample. When a metal probe such as platinum or tungsten having a sharp tip is brought close to the sample and a minute bias voltage is applied between them, a tunnel current flows due to the tunnel effect. By scanning the probe so as to keep the tunnel current constant, the surface shape of the sample can be observed at the atomic level.

In the method for producing a copper foil for printed wiring board of the present invention, at least one surface of the copper foil is represented by the following formula (1):
E = surface area of copper foil / ten-point average roughness of copper foil surface (1)
(The surface area of the copper foil is the surface area per unit area of 1 μm length × 1 μm width of the copper foil, and the surface area of the copper foil is a value obtained when the surface of the copper foil is observed with a scanning tunneling microscope. )
Etching is performed until the value of the adhesion improvement coefficient E expressed by The liquid composition used for the etching treatment is as described above.

  The copper foil of this invention is laminated | stacked on an insulating base material using well-known methods, such as thermocompression bonding. The laminated board (copper-clad laminated board) thus obtained is used for forming a wiring pattern of a printed wiring board.

  When the wiring pattern of the printed wiring board is formed by a subtractive method, the copper foil of the present invention can be used for the conductive layer of the printed wiring board.

  When the wiring pattern of the printed wiring board is formed by a semi-additive method, the copper foil of the present invention can be used for the seed layer of the printed wiring board.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness with an insulating base material is favorable, and the copper foil for printed wiring boards which can be easily removed from the surface of an insulating base material by etching, and the printed wiring using the copper foil A board can be obtained.

[Example 1]
In Example 1, first, an electrolytic copper foil having a thickness of 12 μm and a size of 150 mm × 150 mm was prepared. Next, the shiny surface of the prepared electrolytic copper foil was etched. The composition of the etching liquid composition and the etching conditions are as follows. The shiny surface is the surface of the electrolytic copper foil that is in contact with the drum-shaped cathode.
-Composition of the liquid composition for etching Hydrogen peroxide: 0.5% by mass
Sulfuric acid: 2% by mass
1H-tetrazole: 0.1% by mass
Chloride ion: 0.5ppm
-Etching conditions Temperature of the etching liquid composition: 30 ° C
Spray pressure: 0.1 MPa
Spray time: 1 minute

  Next, the surface of the copper foil after etching was observed with a scanning tunneling microscope at a magnification of 30000 times. FIG. 1 is a three-dimensional image of the copper foil surface observed at this time.

The surface area of the etched copper foil surface in a region of 5 μm length × 5 μm width was measured. As a result, the surface area of the copper foil was 45.4 [μm ² ]. The following apparatus was used for the measurement.
Scanning tunneling microscope (SII Nano Technology, L-traceII / NanoNaviII station)

The surface roughness (Rzjis: 10-point average roughness) of the copper foil after etching was measured. As a result, the surface roughness of the copper foil was 0.55 [μm]. The following apparatus was used for the measurement.
・ Laser microscope (Keyence, VK-9700II, using 408 nm violet laser)

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 3.30. The calculation formula is as follows.
E = {45.4 / (5 × 5)} / 0.55 = 3.30

  The etching amount of the copper foil surface was calculated based on the above formula (2). As a result, the etching amount of the copper foil surface was 0.5 μm.

  The etched copper foil was laminated on a prepreg (Mitsubishi Gas Chemical Co., Ltd., trade name: HL832NS) by vacuum hot pressing. Thereby, the copper clad laminated board which consists of a prepreg and copper foil was produced. In this copper clad laminate, the etched surface of the copper foil is in close contact with the prepreg.

  Using the copper clad laminate thus obtained, the peel strength (peel strength) of the copper foil was measured. The peel strength was measured according to the method defined in JIS C 6481. As a result, the peel strength of the copper foil was 1.05 kgf / cm.

Next, the surface of the copper clad laminate was etched. The composition of the etching liquid composition and the etching conditions are as follows.
-Composition of the liquid composition for etching Hydrogen peroxide: 3% by mass
Sulfuric acid: 7% by mass
Product name: Mitsubishi Gas Chemical Co., Ltd., CPE-770
-Etching conditions Temperature of the etching liquid composition: 35 ° C
Spray pressure: 0.2 MPa
Spray time: 1 minute

Next, the thickness of the copper foil of the copper clad laminate after etching was measured. As a result, the average thickness of 10-point measurement was 2.5 μm. The following apparatus was used for the measurement.
・ Eddy current type copper film thickness gauge (FISCHERSCOPE MMS, manufactured by FISCHER)

  In order to form a wiring pattern on the copper foil, the following treatment was performed. First, electroless copper plating 0.5 μm was applied on the copper foil of the copper clad laminate after etching. Next, a dry film resist was laminated on the copper foil on which electroless copper plating was applied. Next, a resist pattern was formed on the resist layer through exposure and development processes. Next, electrolytic copper plating was applied to the copper foil on which the resist pattern was formed. Finally, the resist on the copper foil was removed using a resist stripping solution. The processing conditions for removing the resist are as follows.

・ Resist stripping solution Monoethanolamine: 5% by mass
Product name: Mitsubishi Gas Chemical Co., Ltd., R-100M
・ Processing conditions Temperature of resist stripping solution: 50 ℃
Spray pressure: 0.1 MPa

  The dimension of the wiring pattern formed on the copper foil was measured using a metal microscope (manufactured by Olympus Corporation, MX61L). As a result, the dimension of the wiring pattern was line / space = 20 μm / 10 μm.

  Next, the seed layer (copper foil) was removed from the top of the substrate using the etching liquid composition. As a result, it took 1 minute to completely remove the seed layer. The processing conditions for removing the seed layer are as follows.

-Composition of the liquid composition for etching Hydrogen peroxide: 2% by mass
Sulfuric acid: 6% by mass
Product name: Mitsubishi Gas Chemical Co., Ltd., CPE-800
-Processing conditions Temperature of the liquid composition for etching: 30 ° C
Spray pressure: 0.2 MPa

  The amount of reduction in the line width of the wiring pattern after removing the seed layer (copper foil) was measured using a metal microscope (manufactured by Olympus Corporation, MX61L). As a result, the reduction amount of the line width was 5.0 μm. FIG. 3 is a cross-sectional photograph of wiring using an electron microscope.

[Example 2]
In Example 2, the same test as in Example 1 was performed except that the liquid composition used for the etching treatment of the shiny surface of the electrolytic copper foil was changed as follows.
-Composition of the liquid composition for etching Hydrogen peroxide: 0.5% by mass
Sulfuric acid: 2% by mass
5-methyltetrazole: 0.1% by mass
Chloride ion: 1ppm

The surface area of the etched copper foil surface in a region of 5 μm length × 5 μm width was measured. As a result, the surface area of the copper foil was 44.7 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil after etching was measured. As a result, the surface roughness of the copper foil was 0.5 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 3.58. The calculation formula is as follows.
E = {44.7 / (5 × 5)} / 0.5 = 3.58

  The etching amount of the copper foil surface was calculated based on the above formula (2). As a result, the etching amount on the copper foil surface was 0.4 μm.

  The peel strength of the copper foil was 1.00 kgf / cm.

  The amount of reduction in the line width of the wiring pattern after removing the seed layer was 5.0 μm.

[Example 3]
In Example 3, the same test as in Example 1 was performed except that the liquid composition used for the etching treatment of the shiny surface of the electrolytic copper foil was changed as follows.
-Composition of etching liquid composition Hydrogen peroxide: 1% by mass
Sulfuric acid: 2.5% by mass
5-methyltetrazole: 0.05% by mass
1,5-dimethyltetrazole: 0.05% by mass
Chloride ion: 1ppm

The surface area of the etched copper foil surface in a region of 5 μm length × 5 μm width was measured. As a result, the surface area of the copper foil was 38 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil after etching was measured. As a result, the surface roughness of the copper foil was 0.25 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 5.60. The calculation formula is as follows.
E = {38 / (5 × 5)} / 0.25 = 6.08

  The etching amount of the copper foil surface was calculated based on the above formula (2). As a result, the etching amount on the surface of the copper foil was 0.3 μm.

  The peel strength of the copper foil was 0.9 kgf / cm.

  The amount of reduction in the line width of the wiring pattern after removing the seed layer was 4.5 μm.

[Example 4]
In Example 4, the same test as in Example 3 was performed, except that the etching conditions for the etching treatment of the shiny surface of the electrolytic copper foil were changed as follows.
-Etching conditions Temperature of the etching liquid composition: 35 ° C
Spray pressure: 0.2 MPa
Spray time: 1 minute

The surface area of the etched copper foil surface in a region of 5 μm length × 5 μm width was measured. As a result, the surface area of the copper foil was 45 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil after etching was measured. As a result, the surface roughness of the copper foil was 0.45 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 3.70. The calculation formula is as follows.
E = {45 / (5 × 5)} / 0.45 = 4.0

  The etching amount of the copper foil surface was calculated based on the above formula (2). As a result, the etching amount of the copper foil surface was 0.65 μm.

  The peel strength of the copper foil was 0.95 kgf / cm.

  The amount of reduction in the line width of the wiring pattern after removing the seed layer was 5.0 μm.

[Comparative Example 1]
In Comparative Example 1, the same test as in Example 1 was performed except that the following electrolytic copper foil whose one surface was previously roughened was used.
・ Electrolytic copper foil Thickness: 12μm
Product name: 3EC-VLP manufactured by Mitsui Mining & Smelting Co., Ltd.

  The surface of the electrolytic copper foil was observed with a scanning tunneling microscope at a magnification of 30000 times. FIG. 2 is a three-dimensional image of the copper foil surface observed at this time.

The surface area in the region of 5 μm long × 5 μm wide on the surface of the copper foil was measured. As a result, the surface area of the copper foil was 36.2 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil was measured. As a result, the surface roughness of the copper foil was 3.65 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 0.40. The calculation formula is as follows.
E = {36.2 / (5 × 5)} / 3.65 = 0.40

  The peel strength of the copper foil was 0.90 kgf / cm.

  The amount of decrease in the line width of the wiring pattern after removing the seed layer was 9.8 μm. FIG. 4 is a cross-sectional photograph of wiring using an electron microscope.

[Comparative Example 2]
In Comparative Example 2, the same test as in Example 1 was performed except that the following electrolytic copper foil whose one surface was previously roughened was used.
・ Electrolytic copper foil Thickness: 12μm
Product name: FV-WS, manufactured by Furukawa Electric Co., Ltd.

The surface area in the region of 5 μm long × 5 μm wide on the surface of the copper foil was measured. As a result, the surface area of the copper foil was 33.8 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil was measured. As a result, the surface roughness of the copper foil was 2.20 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 0.61. The calculation formula is as follows.
E = {33.8 / (5 × 5)} / 2.20 = 0.61

  The peel strength of the copper foil was 0.85 kgf / cm.

  The reduction amount of the line width of the wiring pattern after removing the seed layer was 9.5 μm.

[Comparative Example 3]
In Comparative Example 3, the same test as in Example 1 was performed except that the following electrolytic copper foil whose one surface was previously roughened was used.
・ Electrolytic copper foil Thickness: 12μm
Product Name: HLPLC, manufactured by JX Nippon Mining & Metals

The surface area in the region of 5 μm long × 5 μm wide on the surface of the copper foil was measured. As a result, the surface area of the copper foil was 32.2 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil was measured. As a result, the surface roughness of the copper foil was 2.05 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 0.63. The calculation formula is as follows.
E = {32.2 / (5 × 5)} / 2.05 = 0.63

  The peel strength of the copper foil was 0.85 kgf / cm.

  The amount of reduction in the line width of the wiring pattern after removing the seed layer was 9.3 μm.

[Comparative Example 4]
In Comparative Example 4, the same test as in Example 1 was performed except that the following electrolytic copper foil whose one surface was previously roughened was used.
・ Electrolytic copper foil Thickness: 12μm
Product name: Fukuda Metal Foil Powder Co., Ltd., SV

The surface area in the region of 5 μm long × 5 μm wide on the surface of the copper foil was measured. As a result, the surface area of the copper foil was 31.3 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil was measured. As a result, the surface roughness of the copper foil was 1.85 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 0.68. The calculation formula is as follows.
E = {31.3 / (5 × 5)} / 1.85 = 0.68

  The peel strength of the copper foil was 0.70 kgf / cm.

  The amount of decrease in the line width of the wiring pattern after removing the seed layer was 9.0 μm.

[Comparative Example 5]
In Comparative Example 5, the same test as in Example 1 was performed except that the liquid composition used for the etching treatment of the shiny surface of the electrolytic copper foil was changed as follows.
-Composition of the liquid composition for etching Hydrogen peroxide: 1.3% by mass
Sulfuric acid: 5% by mass
5-aminotetrazole: 0.35% by mass
Product name: CPE-900 manufactured by Mitsubishi Gas Chemical Company, Inc.

The surface area of the etched copper foil surface in a region of 5 μm length × 5 μm width was measured. As a result, the surface area of the copper foil was 36 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil after etching was measured. As a result, the surface roughness of the copper foil was 0.75 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 5.60. The calculation formula is as follows.
E = {36 / (5 × 5)} / 0.75 = 1.92

  The etching amount of the copper foil surface was calculated based on the above formula (2). As a result, the etching amount of the copper foil surface was 1.5 μm.

  The peel strength of the copper foil was 0.50 kgf / cm.

  The amount of reduction in the line width of the wiring pattern after removing the seed layer was 6.5 μm.

[Comparative Example 6]
In Comparative Example 6, the same test as in Example 1 was performed except that the shiny surface of the electrolytic copper foil was not etched.

The surface area in the region of 5 μm length × 5 μm width on the copper foil surface (untreated) was set to 25 [μm ² ].

  The surface roughness (Rzjis: 10-point average roughness) of the copper foil (untreated) was measured. As a result, the surface roughness of the copper foil was 0.1 [μm].

The adhesion improvement coefficient E was calculated based on the above formula (1). As a result, the adhesion improvement coefficient E was 5.60. The calculation formula is as follows.
E = {25 / (5 × 5)} / 0.1 = 10

  The peel strength of the copper foil was 0.20 kgf / cm.

  The amount of reduction in the line width of the wiring pattern after removing the seed layer was 4.5 μm.

  The results of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 1 below.

In Examples 1 to 4, the adhesion improvement coefficient E was larger than those of Comparative Examples 1 to 5.
In Examples 1, 2, and 4, the peel strength of the copper foil was larger than those of Comparative Examples 1-6.
In Example 3, the peel strength was equivalent to that of Comparative Example 1, and the peel strength of the copper foil was larger than those of Comparative Examples 2-6.
In Examples 1 to 4, the line width reduction amount of the wiring pattern was smaller than those of Comparative Examples 1 to 5.
In Examples 1 to 4, the etching amount was smaller than that in Comparative Example 5.

The copper foil of the present invention had good adhesion to the insulating substrate.
The copper foil of the present invention can form a fine wiring pattern because the amount of reduction in the line width of the wiring pattern is small.
The copper foil of the present invention can be preferably applied to a printed wiring board having a wiring pattern line width of 20 μm or less.

Claims (8)

At least one surface of the copper foil has the following formula (1):
E = surface area of copper foil / ten-point average roughness of copper foil surface (1)
(The surface area of the copper foil is the surface area per unit area of 1 μm length × 1 μm width of the copper foil, and the surface area of the copper foil is a value obtained when the surface of the copper foil is observed with a scanning tunneling microscope. )
Etching treatment until the value of adhesion improvement coefficient E represented by 2.5 to 8 is a method for producing a copper foil for printed wiring board ,
For the etching process,
0.2 to 1.5 mass% hydrogen peroxide,
0.5-3.0% by weight sulfuric acid,
0.3 to 3 ppm of halogen ions;
0.01 to 0.3% by weight of tetrazole and
Using a liquid composition (except for those containing silver ions) . The following formula (2):
Etching amount [μm] = (mass of copper foil before etching−mass of copper foil after etching) / (etching area × copper density) (2)
(Wherein the density of copper is 8.96 g / cm ³ Is)
The etching amount of the surface of the said copper foil represented by these is 1 micrometer or less, The method of Claim 1. The method according to claim 1 or 2, wherein the surface of the copper foil is not treated with a metal other than copper, a silane coupling agent, or an adhesive. A method for producing a copper clad laminate comprising an insulating substrate and a copper foil for a printed wiring board laminated on the surface of the insulating substrate,
The method for manufacturing the said copper foil for printed wiring boards by the method as described in any one of Claims 1-3. A method of manufacturing a printed wiring board comprising a copper clad laminate,
The method of manufacturing the said copper clad laminated board by the method of Claim 4. The method according to claim 5, wherein the wiring pattern is formed by a semi-additive method. The method according to claim 5, wherein the wiring pattern is formed by a subtractive method. The method according to claim 6, wherein a line width of the wiring pattern is 20 μm or less.