JP7247015B2 - Electrolytic copper foil, surface-treated copper foil using the electrolytic copper foil, and copper-clad laminate and printed wiring board using the surface-treated copper foil - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrolytic copper foil, a surface-treated copper foil using the electrolytic copper foil, and a copper-clad laminate and a printed wiring board using the surface-treated copper foil.

A printed wiring board is generally manufactured by the following method. First, a thin copper foil for surface circuit formation is placed on the surface of an electrically insulating resin substrate made of glass epoxy resin, polyimide resin, or the like, and then heated and pressed to produce a copper-clad laminate. Next, the copper-clad laminate is subjected to through-hole drilling and through-hole plating in sequence, and then the copper foil of the copper-clad laminate is subjected to an etching treatment to provide a desired line width and a desired line-to-line pitch. forming a wiring pattern. Finally, solder resist application, exposure, through-hole plating, or other finishing processes such as removal of uncured solder resist with caustic soda or the like are performed to expose the plating of the connections of electronic components.

The copper foil used in the manufacture of such printed wiring boards is generally electrolytic copper foil obtained by peeling the copper foil 101 deposited on the drum 102 using the electrolytic deposition apparatus shown in FIG. be done. The electrolytic deposition start surface (shiny surface, hereinafter referred to as the “S surface”) separated from the drum 102 is relatively smooth, and the opposite surface, the electrolytic deposition end surface (matte surface, hereinafter referred to as the “M surface”). ) generally has unevenness. Usually, the M surface is roughened to improve the adhesiveness to the resin substrate.

In recent years, an adhesive resin such as an epoxy resin is attached in advance to the roughened surface of the copper foil, and the resin-coated copper foil is used as an insulating resin layer in a semi-cured state (B stage). A printed wiring board is manufactured by using it as a copper foil for formation and thermocompression bonding the side of the insulating resin layer to a resin substrate. In particular, for build-up wiring boards, which are a type of printed wiring board, there is a demand for high-level integration of various electronic components. There is a growing demand for a printed wiring board with a wiring pattern of fine pitch, that is, a so-called fine pattern. For example, multi-layer boards used for servers, routers, communication base stations, in-vehicle boards, etc., and multi-layer boards for smartphones have printed wiring boards with high-density ultra-fine wiring (hereinafter referred to as "high-density wiring boards"). requested.

In realizing such fine wiring, a high etching factor (Ef) is required for fine pattern formation, and it is important that the copper foil used is smooth. In addition, from the viewpoint of preventing disconnection, it is also important to reduce the size and number of pinholes.

Regarding the reduction of such pinholes, for example, Patent Document 1 discloses a method of reducing pinholes by using an intermediate layer having a low resistance during electroplating, such as a zinc chromate treatment layer, on a carrier. Proposed. However, with such a copper foil with a carrier, there is a concern that pinholes may occur when the copper layer is peeled off. There is also concern that handling is poor because of

On the other hand, Patent Document 2 discloses a technique for reducing the number of pinholes with a major diameter of 30 μm or more existing on the surface of the electrolytic copper foil to ²⁰ or less per square meter by adopting a cathodic reduction process for removing the oxide film on the drum. Proposed. According to such a technique, relatively large pinholes can be effectively suppressed.

JP 2015-47795 A WO2018/181061

However, in recent years, in the manufacture of printed wiring boards, it has been desired to achieve further reduction in layer thickness, further improvement in smoothness, and reduction in pinholes.

As described above, recently, carrier-attached copper foils have been used as extremely thin foils, but their use requires a step of peeling the copper foil from the carrier, which increases costs and decreases productivity.

Further, in the manufacture of printed wiring boards, there is a demand for a higher density wiring pattern, and a higher etching factor (Ef) for fine pattern formation and a lower disconnection rate are required. Therefore, as a copper foil for use in such printed wiring boards, there is a demand for the development of an electrolytic copper foil that is thin, has excellent smoothness, and has further reduced the size and number of pinholes.

Therefore, the present invention is not a copper foil with a carrier, but is thin, has few pinholes, has excellent smoothness, an electrolytic copper foil, a surface-treated copper foil using the electrolytic copper foil, and the surface-treated copper foil An object of the present invention is to provide a copper-clad laminate and a printed wiring board.

As a result of intensive studies by the present inventors, it was found that, excluding a copper foil with a carrier, an electrolytic copper foil having a thickness of 9 μm or less, and having a pinhole having a longitudinal dimension of 2 to 10 μm, the existence density of the electrolytic copper foil was The ^present inventors have found that a thin electrolytic copper foil with 800 or less pinholes per square meter and excellent smoothness is particularly suitable for high-density wiring circuits, and have completed the present invention.

That is, the gist and configuration of the present invention are as follows.
[1] An electrolytic copper foil having a thickness of 9 μm or less, excluding a copper foil with a carrier,
An electrolytic copper foil, wherein the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is 800 or less per 1 m ² of the electrolytic copper foil.
[2] The electrolytic copper foil according to [1] above, wherein the density of pinholes having a longitudinal dimension of 2 to 30 μm is 800 or less per 1 m ² of the electrolytic copper foil.
[3] The electrolytic copper foil according to [1] or [2] above, which is substantially free of pinholes having a longitudinal dimension of more than 30 μm.
[4] The electrolytic copper foil according to any one of the above [1] to [3], which is substantially free of pinholes having a longitudinal dimension of more than 10 μm.
[5] The surface roughness Rz measured with a white interference microscope is 1.5 to 3.0 μm on the glossy surface (S surface) and 2.0 to 6.0 μm on the rough surface (M surface). The electrolytic copper foil according to any one of [1] to [4] above.
[6] The electrolytic copper foil according to any one of [1] to [5] above, which has a thickness of 6 μm or less.
[7] Tensile strength in normal state is 400 to 650 MPa,
Tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour is 300 MPa or more,
The electrolytic copper foil according to any one of [1] to [6] above, which has an elongation of 2.5% or more in a normal state.
[8] The electrolytic copper foil according to any one of [1] to [7] above, which is used for manufacturing a printed wiring board.
[9] A surface-treated copper foil comprising a copper foil substrate and a surface-treated film containing a roughening treatment layer formed by forming roughening particles on one surface of the copper foil substrate,
The copper foil substrate is the electrolytic copper foil according to any one of [1] to [7] above,
A surface-treated copper foil, wherein the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is 800 or less per 1 m ² of the surface-treated copper foil.
[10] The surface-treated copper foil according to [9] above, wherein the surface opposite to the surface treatment film has a surface roughness Rz of 1.5 to 6.0 μm as measured by the white interference microscope.
[11] A copper-clad laminate comprising the surface-treated copper foil according to [9] or [10] above, and a resin substrate laminated on the roughened surface of the surface-treated copper foil.
[12] A printed wiring board comprising the copper-clad laminate according to [11] above.

According to the present invention, a thin electrolytic copper foil with few pinholes and excellent smoothness, a surface-treated copper foil using the electrolytic copper foil, and a copper-clad laminate and print using the surface-treated copper foil A wiring board can be provided.

FIG. 1 is a schematic diagram showing a conventional electrolytic copper foil deposition apparatus. FIG. 2 is a schematic diagram showing an electrolytic copper foil deposition apparatus having a cathodic reduction process.

Embodiments of an electrolytic copper foil according to the present invention, a surface-treated copper foil using the electrolytic copper foil, and a copper-clad laminate and a printed wiring board using the surface-treated copper foil are described in detail below.

(electrolytic copper foil)
The electrolytic copper foil of the present invention, excluding the copper foil with a carrier, is an electrolytic copper foil having a thickness of 9 μm or less, and the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is less than 1 m of the electrolytic copper foil. 800 or less per ² .

Such an electrolytic copper foil is thin, has few pinholes, and is excellent in smoothness, and can be suitably used for manufacturing a printed wiring board forming a high-density wiring circuit.

In this specification, "electrolytic copper foil" refers to a copper foil produced by electrolytic treatment, and refers to an untreated copper foil that has not undergone surface treatment after foil production. Therefore, it is distinguished from a "surface-treated copper foil" obtained by using an electrolytic copper foil as a copper foil substrate and applying a surface treatment to one surface thereof, as described later.

Moreover, the electrolytic copper foil of the present invention is an electrolytic copper foil other than the copper foil with a carrier.
Here, the "copper foil with a carrier" is a copper foil having a structure in which a release layer is formed on a support (carrier foil) and an ultra-thin copper foil is formed thereon.
A copper foil with a carrier can be said to be excellent from the viewpoint of making the copper foil thinner, but when such a copper foil is used in the production of printed wiring boards, a step of removing the copper foil from the carrier is required. , which increases costs and decreases productivity. Also, when the copper foil is peeled off, pinholes may occur, and the formation of the metal layers used for the carrier and the intermediate layer is costly and time-consuming.
Therefore, in the present invention, it is aimed to realize thinning and improvement of smoothness in a normal electrodeposited copper foil, which is not a carrier-attached copper foil as described above.

The foil thickness of the electrolytic copper foil of the present invention is 9 μm or less, preferably 6 μm or less, more preferably 5 μm or less. From the viewpoint of the demand for thinner copper foil, the thinner the electrodeposited copper foil, the better.

In the electrolytic copper foil of the present invention, the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is 800 or less, preferably 600 or less, more preferably 400 per 1 m ² of the electrolytic copper foil. or less, more preferably 200 or less, still more preferably 100 or less, even more preferably 50 or less, and even more preferably 20 or less. Since the existence density of pinholes with a longitudinal dimension of 2 to 10 μm correlates with the surface roughness on the surface of the electrolytic copper foil, by controlling it within the above range, the electrolytic A copper foil is obtained.

Conventionally, as pinholes in electrolytic copper foil, attention has been paid to large pinholes (for example, those having a longitudinal dimension exceeding 30 μm) that cause disconnection of wiring when printed wiring boards are formed. However, as a result of repeated investigations by the present inventors, it was found that, for example, in fine wiring with L&S=30/30 μm or less, a pinhole with a longitudinal dimension of 30 μm or less may also cause wiring breakage. .

Furthermore, as a result of research, it was found that reducing the size and number of pinholes on the surface of the electrolytic copper foil is effective in reducing the surface roughness of the electrolytic copper foil. This is because copper foil with many pinholes has many areas where it is difficult for copper to be plated on the surface of the titanium drum during the manufacturing process, especially in the initial process of copper plating. , simply referred to as "subsequent copper plating process".), it remains on the copper foil surface as a portion with greater unevenness than the surroundings, increasing the surface roughness of the copper foil. In order to prevent an increase in surface roughness due to the remnants of such pinholes, it is effective to set the existence density of pinholes having a longitudinal dimension of 2 to 10 μm to 800 or less per 1 m ² of the electrolytic copper foil. I found that

In addition, in such an electrolytic copper foil, the number of small pinholes with a longitudinal dimension of about 2 to 10 μm is also suppressed to a small number. can be suppressed to the extent that it does not exist in

The reason why the lower limit of the longitudinal dimension of the pinhole to be focused on is set to 2 μm is that a pinhole whose longitudinal dimension is smaller than 2 μm does not affect the surface roughness.

With such an electrodeposited copper foil, the surface roughness can be reduced, and when a printed wiring board is produced using the electrodeposited copper foil, it is possible to prevent disconnection in fine wiring, and fine patterns can be formed by improving the etching factor. formation can be achieved. Moreover, such an electrolytic copper foil is excellent in tensile strength and elongation of the copper foil itself, and is also excellent in heat resistance.

On the other hand, when the existence density of pinholes having a longitudinal dimension of 2 to 10 μm exceeds 800 per 1 m ² of the electrolytic copper foil, the surface roughness of the electrolytic copper foil tends to increase. In the manufacturing process of such an electrolytic copper foil, there tends to be many parts that are difficult to be copper-plated on the surface of the titanium drum in the initial process of copper plating in the manufacturing process. However, more than 800 pinholes with a longitudinal dimension of 2 to 10 μm remain, and the buried portion has larger irregularities than the surrounding area, and the surface roughness tends to increase. Therefore, a printed wiring board produced using such an electrolytic copper foil tends to have a lower etching factor. In addition, such an electrolytic copper foil tends to have pinholes as large as 30 μm or more, and a printed wiring board produced using the electrolytic copper foil is likely to have disconnection.

The density of pinholes with a longitudinal dimension of 2 to 10 μm is preferably as small as possible, but from a practical point of view, the lower limit may be, for example, 5 per 1 m ² of the electrolytic copper foil, or 10. good too.

The size (dimension) and existence density of the pinholes are values measured by the method described in Examples below. The same applies to the size and existence density of pinholes described below.

In the electrolytic copper foil of the present invention, the existence density of pinholes having a longitudinal dimension of 2 to 30 μm is preferably 800 or less, more preferably 600 or less, and still more preferably 1 m ² of the electrolytic copper foil. is 400 or less, more preferably 200 or less, even more preferably 100 or less, even more preferably 50 or less, and even more preferably 20 or less. By controlling the content within the above range, the surface roughness of the electrolytic copper foil can be further reduced.

The electrodeposited copper foil of the present invention is preferably substantially free of pinholes having a longitudinal dimension greater than 30 μm. Such an electrodeposited copper foil has excellent smoothness, and when used in the production of a printed wiring board, can effectively reduce the disconnection rate and achieve a high etching factor.
Here, "there are substantially no pinholes with a longitudinal dimension of more than 30 µm" means that an arbitrary 200 mm × 200 mm region is observed at one place by the measurement method described in the examples described later. In addition, no pinholes with a longitudinal dimension greater than 30 μm are observed. Therefore, even if the observation area is changed several times and the measurement is repeated until a pinhole with a longitudinal dimension of more than 30 μm is observed, it does not mean that no pinhole with a longitudinal dimension of more than 30 μm is observed.

The electrodeposited copper foil of the present invention is preferably substantially free of pinholes having a longitudinal dimension greater than 10 μm. Such an electrodeposited copper foil is more excellent in smoothness, and when used for producing a printed wiring board, it can effectively reduce the disconnection rate and realize a high etching factor.
The meaning of "substantially no pinholes having a longitudinal dimension of more than 10 μm" is the same as in the case of pinholes having a longitudinal dimension of more than 30 μm.

In addition, the surface roughness of the electrodeposited copper foil is correlated with the number and size of pinholes in the electrodeposited copper foil. In particular, the smaller the density of pinholes with a longitudinal dimension of 2 to 10 μm, the smaller the surface roughness.

The electrolytic copper foil of the present invention preferably has a surface roughness Rz of 1.3 to 3.0 μm, more preferably 1.5 to 3.0 μm on the glossy side (S side) as measured by a white interference microscope. 0 μm, more preferably 1.5 to 2.5 μm, still more preferably 1.5 to 2.0 μm, and preferably 2.0 to 6.0 μm on the rough surface (M surface) , more preferably 2.0 to 4.0 μm, still more preferably 2.0 to 3.0 μm. By setting it to the above range, the smoothness of the non-roughened surface can be improved when a surface-treated copper foil is produced using an electrolytic copper foil, and a printed wiring board is produced using the surface-treated copper foil. In some cases, a high etching factor can be realized. This is because the non-roughened surface of the surface-treated copper foil reflects the surface condition of the copper foil substrate as it is, and the surface roughness of the non-roughened surface correlates with the etching factor. is.

The electrodeposited copper foil of the present invention preferably has a tensile strength of 400 to 650 MPa, more preferably 400 to 550 MPa, still more preferably 400 to 500 MPa in a normal state. By setting it as the said range, handling property and etching property become favorable.
Here, the “normal state” means that the electrodeposited copper foil is in an unheated state as it is manufactured and has no heat history accompanied by heating above 60 ° C., for example, normal temperature (15 to 30 ° C., below The same applies in the following).

The electrodeposited copper foil of the present invention preferably has a tensile strength of 300 MPa or more, more preferably 320 MPa or more, and still more preferably 350 MPa or more at room temperature after heat treatment at 300° C. for 1 hour. By setting the content within the above range, the copper foil has excellent heat resistance, fine crystal grains, and good etchability even after being laminated with a resin substrate and heated.
The tensile strength at normal temperature after heat treatment at 300° C. for 1 hour is preferably as high as possible, but the upper limit may be, for example, 400 MPa.
Here, "tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour" means that the copper foil is heat treated at 300 ° C. for 1 hour, for example, after cooling to room temperature. It refers to the tensile strength that has been applied (same below).

The electrodeposited copper foil of the present invention has an elongation in a normal state of preferably 2.5% or more, more preferably 3.2% or more, and still more preferably 4.0% or more. By setting it as the said range, handling property becomes favorable.
In addition, although the elongation in the normal state is preferably as high as possible, the upper limit may be 5.0%, for example.

The above tensile strength and elongation are values measured by the methods described in the examples below. The same applies to the following tensile strength and elongation.

<Method for producing electrolytic copper foil>
Next, a preferred method for producing the electrolytic copper foil of the present invention will be described.
The electrolytic copper foil of the present invention comprises, for example, a sulfuric acid-copper sulfate aqueous solution as an electrolytic solution, an insoluble anode made of titanium coated with a platinum group element or an oxide element thereof, and a titanium cathode provided facing the anode. The electrolytic solution is supplied between the drum and the cathode drum, and while the cathode drum is rotated at a constant speed, a direct current is applied between both electrodes to deposit copper on the surface of the cathode drum, and the deposited copper is removed from the surface of the cathode drum. Manufactured by a method of peeling and winding continuously. It should be noted that such a manufacturing method is an example.

As a result of further research by the present inventors regarding the production of such an electrolytic copper foil, it was found that at least one of PR (Periodic Reverse) electrolysis and cathode reduction step was performed when copper was plated on the cathode drum. , can reduce the number and size of pinholes.

It is generally known that PR electrolysis results in denser nucleation of the metal to be plated than in normal constant current electrolysis. This is thought to be because metal deposition and dissolution on the surface of the cathode occur alternately, metal ions are accumulated near the interface between the electrode and the electrolyte, and ion depletion is less likely to occur. As a result, dense plating is possible from the initial layer of copper, it is difficult to form a portion with a small amount of plating that can cause pinholes on the cathode drum, and it is possible to prevent unevenness on the surface of the copper foil due to the remnants of pinholes. is considered possible.

In such PR electrolysis, it is preferable to equalize the current densities of forward electrolysis and reverse electrolysis. Here, the forward current is the cathodic reaction in which the copper foil surface is plated, and the reverse current is the anodic reaction in which it is dissolved. At the timing when the copper ions in the vicinity of the interface between the electrode and the electrolyte are about to become deficient in forward electrolysis, copper ions are depleted by dissolving the copper foil in reverse electrolysis and supplying copper ions from the bulk layer of the electrolyte. It is presumed that it becomes difficult and a dense film is formed.

In the production of the electrodeposited copper foil of the present invention, it is preferable to manufacture the electrodeposited copper foil so that the deposition potential of copper on the surface of the cathode drum is uniform without variation. For that purpose, for example, there is a method of producing foil in a state where no oxide film exists on the surface of the titanium drum.

If a thick oxide film is formed on the cathode, that portion has a high resistance to nucleation of the deposited metal and is difficult to plate, resulting in non-uniform plating on the drum. As a result, in the copper foil to be manufactured, pinholes are likely to occur in the initial layer of copper, and even if the pinholes in the initial layer are filled in the subsequent plating process, areas with greater unevenness than the surrounding area will occur. It is conceivable to put away.
In order to solve such problems, a process of removing at least part of the oxide film on the titanium drum and making the surface of the titanium drum uniform is required.

In a conventional method for producing an electrolytic copper foil, for example, as shown in FIG. 1, an electrolytic drum 102 serving as a cathode is polished with a buff 103 to remove an oxide film formed on the surface of the drum.

On the other hand, in the present invention, it is preferable to employ a cathodic reduction step. The cathodic reduction step is a step of removing the oxide film with the electrolytic solution 106 of the cathodic reduction device 105 as shown in FIG. In such a cathode reduction process, instead of the buff 103 of the conventional electrodeposited copper foil manufacturing apparatus, the oxide film is removed by the electrolytic solution 106 of the cathode reduction apparatus 105, so that the initial deposition of copper is reduced to the electrolytic drum 102. It is expected that the size and number of pinholes in the resulting copper foil will be reduced.

As the electrolytic solution 106 of such a cathode reduction device 105, it is preferable to mix sulfuric acid, hydrochloric acid, oxalic acid, etc. For example, sulfuric acid concentration is 50 to 70 g/L, hydrochloric acid concentration is 0 to 5 g/L, A mixed solution having an acid concentration of 0 to 10 g/L can be preferably used. The temperature of the electrolytic solution is preferably 60-70° C., the current density is preferably 10-15 A/dm ² , which is relatively low, and the treatment time is preferably 5-20 minutes. Through such a cathodic reduction process, the oxide film can be efficiently removed while suppressing roughening of the electrode surface, and the occurrence of small pinholes of about 2 to 10 μm can be effectively suppressed.

As the electrolytic solution 104 for foil production, for example, a sulfuric acid-copper sulfate aqueous solution having a copper concentration of 50 to 150 g/L and a sulfuric acid concentration of 20 to 200 g/L can be preferably used.

At least one organic or inorganic additive may be added to the electrolytic solution 104 from the viewpoint of increasing the strength of the copper foil. By adding these, the tensile strength in the normal state and the tensile strength after heating can be increased, and the strength itself and the heat resistance can be improved.
Examples of organic additives that can be used include ethylenethiourea, polyethylene glycol, and glue.
Inorganic additives such as NaCl and HCl can be used as sources of chloride ions.

The electrolytic solution 104 preferably contains 10 to 30 ppm by mass of chloride ion (chlorine) as an inorganic additive, and 3 to 20 ppm by mass of ethylene thiourea, polyethylene glycol, and glue as organic additives. addition is preferred.

Moreover, as electrolysis conditions, it is preferable that electrodeposition is performed under the following conditions.
Bath temperature: 18-67°C
<Constant current electrolysis>
Current density: 3 to 67 A/dm ²
<PR pulse electrolysis>
Positive pulse (forward electrolysis) current density: 3 to 67 A/dm ²
Positive pulse (forward electrolysis) energization time: 0.3 to 10 milliseconds (ms)
Negative pulse (reverse electrolysis) current density: 3 to 67 A/dm ²
Negative pulse (reverse electrolysis) energization time: 0.01 to 1 millisecond (ms)

Incidentally, as shown in FIG. 2, the copper deposited on the surface of the cathode drum 102 is finally peeled off in the direction of the arrow, and the copper foil 101 is manufactured.
In the electrodeposited copper foil manufactured by the method described above, the number and size of pinholes are effectively suppressed.

(Surface treated copper foil)
The surface-treated copper foil of the present invention has a copper foil substrate and a surface-treated film including a roughening layer formed by forming roughening particles on one surface of the copper foil substrate. Here, the copper foil substrate is the electrolytic copper foil of the present invention. Moreover, the surface of the surface treatment film is a roughened surface having a fine uneven surface shape reflecting the formation state and particle shape of the roughening particles formed on one surface of the copper foil substrate. The surface of such a surface treatment film (hereinafter referred to as "roughened surface") may be, for example, the surface of a roughened layer formed on a copper foil substrate, or the roughened layer The surface of the silane coupling agent layer directly formed thereon, or an intermediate layer such as a nickel-containing underlayer, a zinc-containing heat-resistant layer, and a chromium-containing rust-preventing layer on this roughened layer It may be the surface of the silane coupling agent layer formed through the layer. Further, when the surface-treated copper foil of the present invention is used, for example, in a conductive circuit of a printed wiring board, the roughened surface serves as a surface (adhering surface) for laminating a resin substrate. .

In the surface-treated copper foil of the present invention, the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is preferably 800 or less, more preferably 600 or less per 1 m ² of the surface-treated copper foil, It is more preferably 400 or less, still more preferably 200 or less, still more preferably 100 or less, even more preferably 50 or less, and even more preferably 20 or less. In a printed wiring board produced using such a surface-treated copper foil, it is possible to form a fine pattern by improving the etching factor. In addition, in such an electrolytic copper foil, for example, large pinholes with a longitudinal dimension exceeding 30 μm are suppressed to the extent that they do not exist substantially, so prints made using the surface-treated copper foil Disconnection can also be effectively suppressed in the wiring board.

The density of pinholes with a longitudinal dimension of 2 to 10 μm is preferably as small as possible, but from a practical point of view, the lower limit may be, for example, 5 per 1 m ² of the electrolytic copper foil, or 10. good too.

The surface-treated copper foil of the present invention preferably has a surface roughness Rz of 1.5 to 6.0 μm, more preferably 1.5 μm to 6.0 μm, as measured by a white interference microscope on the side opposite to the surface treatment film. It is 5 to 4.5 μm, more preferably 1.5 to 3.0 μm, still more preferably 1.5 to 2.4 μm. Within the above range, a high etching factor can be achieved in a printed wiring board produced using the surface-treated copper foil.

In addition, the surface-treated copper foil of the present invention is excellent in tensile strength and elongation under normal conditions, and is also excellent in heat resistance. Since the surface treatment film is usually very thin, it hardly affects the mechanical properties of the copper foil substrate. Therefore, the physical properties as described above are generally the same as those of the copper foil substrate used, and the preferred range is also the same as in the case of the electrodeposited copper foil described above.

<Method for producing surface-treated copper foil>
Next, an example of a preferred method for producing the surface-treated copper foil of the present invention will be described. In the present invention, it is preferable to subject the surface of the copper foil substrate to roughening treatment for forming roughening particles. By performing the roughening treatment, it is possible to improve the adhesion to the resin substrate when producing the copper-clad laminate.

The electrolytic copper foil of the present invention is used as the copper foil substrate. By using such a copper foil, the number and size of pinholes can be reduced, and a surface-treated copper foil having high tensile strength and elongation in normal conditions and excellent heat resistance can be obtained.

(roughening treatment)
For the roughening treatment, it is preferable to perform a roughening plating treatment as shown below, for example. Moreover, you may combine a fixed plating process as needed.
The method of plating is preferably a roll-to-roll method, for example, from the viewpoint of mass production and production cost.

- Roughening Plating Treatment Roughening plating treatment is a treatment for forming roughening particles on one surface of the copper foil substrate. Specifically, plating is performed in a copper sulfate bath. Molybdenum (Mo) or nickel (Ni) may be added to such a copper sulfate bath (roughening plating solution basic bath) from the viewpoint of enhancing the etching property when producing a printed wiring board.

An example of the composition and electrolysis conditions of the plating solution for roughening plating is shown below. The following conditions are a preferable example, and the types and amounts of additives and electrolysis conditions can be appropriately changed and adjusted as necessary within a range that does not impair the effects of the present invention.

<Conditions for roughening plating>
Copper sulfate pentahydrate: 3 to 72 g/L in terms of copper (atoms)
Sulfuric acid: 26 to 150g/L
(NH ₄ ) ₆ Mo ₇ O _{24.4H 2} O: 1 to 20 g/L in terms of molybdenum (atom)
NiCl _{2.6H 2} O: 1 to 20 g/L in terms of nickel (atoms)
Current density: 3 to 67 A/dm ²
Treatment time: 1 second to 1 minute 55 seconds Bath temperature: 25 to 70°C

Fixed Plating Treatment The fixed plating treatment is a treatment for performing smooth covering plating on the copper foil substrate surface-treated by the roughening plating treatment. Specifically, plating is performed in a copper sulfate bath. Usually, this treatment is performed to prevent roughening particles from falling off, that is, to fix roughening particles.
Incidentally, the composition of the plating solution and the electrolysis conditions may be appropriately adjusted under known conditions.

Furthermore, the surface-treated copper foil of the present invention contains a base layer containing nickel (Ni), a heat-resistant layer containing zinc (Zn), and chromium (Cr) directly or on the roughened layer. A silane coupling agent layer may be further formed via an intermediate layer such as an antirust treatment layer.
Further, when the silane coupling agent layer is formed, the surface of the surface-treated copper foil (the surface on the bonding side with the resin substrate) is provided with a functional group having a strong affinity for the resin substrate, so that the surface-treated copper foil and the resin It is preferable because the bonding strength with the substrate is further improved, and the rust resistance and moisture absorption heat resistance of the copper foil are further improved.

As a method for forming the silane coupling agent layer, for example, a silane coupling agent solution is applied directly or via an intermediate layer on the uneven surface of the roughened layer of the surface-treated copper foil, and then air-dried (naturally drying) or drying by heating. When the water in the applied coupling agent solution evaporates, a silane coupling agent layer is formed, so that the effects of the present invention can be fully exhibited. Drying by heating at 50 to 180° C. is preferable because it promotes the reaction between the silane coupling agent and the copper foil.

Silane coupling agents include vinyl-based silanes, epoxy-based silanes, styryl-based silanes, methacryloxy-based silanes, acryloxy-based silanes, amino-based silanes, ureido-based silanes, chloropropyl-based silanes, mercapto-based silanes, sulfide-based silanes, and isocyanate-based silanes. It can be appropriately selected from silanes. These silane coupling agents can usually be used as an aqueous solution of 0.001 to 5 mass %.
The same effect can be obtained by using a titanate-based or zirconate-based coupling agent instead of the silane coupling agent.

In addition, the surface-treated copper foil of the present invention has a base layer containing Ni, a heat-resistant layer containing Zn, and an anticorrosive layer containing Cr, which are interposed between the roughening layer and the silane coupling agent layer. It is preferred to have at least one intermediate layer selected from among.

Underlayers containing Ni are used when, for example, copper (Cu) in a copper foil substrate or a roughening treatment layer diffuses to the resin substrate side and copper damage occurs, resulting in a decrease in adhesion, or when Zn is removed. In the case of forming a heat-resistant layer containing It is preferably formed between the agent layer. Diffusion of copper and zinc can be prevented by forming an underlying layer containing Ni. The Ni-containing underlayer is preferably made of at least one selected from nickel (Ni), nickel (Ni)-phosphorus (P), and nickel (Ni)-zinc (Zn). The underlayer containing Ni can be formed by applying a known electroplating method or electroless plating method.

A heat-resistant layer containing Zn is preferably formed when it is necessary to further improve heat resistance. In particular, when the thin copper foil and the resin substrate are thermocompression bonded, the resin substrate is prevented from deteriorating due to the reaction between the copper foil and the resin substrate, and the surface oxidation of the thin copper foil is prevented from being oxidized. , to increase the bonding strength between the copper foil and the resin substrate. The Zn-containing heat-resistant layer is, for example, zinc or a zinc-containing alloy such as zinc (Zn)-tin (Sn), zinc (Zn)-nickel (Ni), zinc (Zn)-cobalt (Co). , zinc (Zn)-copper (Cu), zinc (Zn)-chromium (Cr) and zinc (Zn)-vanadium (V). preferable. The heat-resistant layer containing Zn can be formed by applying a known electroplating method or electroless plating method.

It is preferable to form the anticorrosive layer (antioxidant layer) containing Cr when it is necessary to further improve the corrosion resistance. Examples of the antirust layer include a chromium layer formed by chromium plating and a chromate layer formed by chromate treatment. A suitable chromate treatment may be performed according to a known method, such as the method disclosed in JP-A-60-86894. Specifically, by adhering 0.01 to 0.3 mg/dm ² of chromium oxide and its hydrate in terms of Cr amount, the copper foil is provided with excellent rust prevention ability. can be done.

When forming all three layers, the base layer, the heat-resistant layer and the rust-proof layer are preferably formed on the roughening layer in this order. Either one layer or only two layers may be formed depending on the desired properties.

[Preparation of surface-treated copper foil]
The method for producing the surface-treated copper foil of the present invention is summarized below.
In the present invention, it is preferable to produce a surface-treated copper foil according to the following forming steps (S1) to (S5).
(S1) Step of Forming Roughened Layer A roughened layer having a fine uneven surface is formed on a copper foil substrate by electrodeposition of roughening particles.
(S2) Step of Forming Underlayer An underlayer containing Ni is formed on the roughened layer, if necessary.
(S3) Step of Forming Heat-Resistant Layer A heat-resistant layer containing Zn is formed on the roughened layer or the underlying layer, if necessary.
(S4) Step of Forming Rust-Preventing Layer A rust-preventing layer containing Cr is formed, if necessary, on the roughening-treated layer, or on the base layer and/or the heat-resistant layer formed on the roughening-treated layer, if necessary. do.
(S5) Step of Forming Silane Coupling Agent Layer An intermediate layer in which a silane coupling agent layer is formed directly on the roughening treatment layer, or at least one of a base layer, a heat treatment layer and an antirust treatment layer is formed on the roughening treatment layer. to form a silane coupling agent layer.

(Copper clad laminate and printed wiring board)
The surface-treated copper foil produced using the electrolytic copper foil of the present invention can be suitably used for producing copper-clad laminates. Such a copper-clad laminate is suitable for use as a printed wiring board for forming high-density fine wiring.

A copper-clad laminate preferably comprises the surface-treated copper foil of the present invention and a resin substrate laminated on the roughened surface of the surface-treated copper foil. Such a copper-clad laminate can be formed by a known method using the copper foil of the present invention. For example, a copper-clad laminate is prepared by placing a surface-treated copper foil having a roughened surface and an electrically insulating resin substrate (insulating substrate) such that the roughened surface (bonding surface) faces the resin substrate. , manufactured by laminating and pasting. Examples of resin substrates include flexible resin substrates and rigid resin substrates, and the copper foil of the present invention is particularly suitable in combination with rigid resin substrates.

In the case of manufacturing a copper-clad laminate, it may be manufactured by bonding a surface-treated copper foil having a silane coupling agent layer and a resin substrate together by hot pressing. The resin substrate is coated with a silane coupling agent, and the resin substrate coated with the silane coupling agent and a surface-treated copper foil having an anticorrosive layer on the outermost surface are bonded together by a hot press. A copper clad laminate also has the same effects as the present invention.

Moreover, it is preferable that the printed wiring board includes the copper-clad laminate. Such a printed wiring board can be formed by a known method using the copper-clad laminate. The electrodeposited copper foil and surface-treated copper foil of the present invention are thin, have few pinholes, and are excellent in smoothness, so they are suitable for use as printed wiring boards that form high-density fine wiring. .

(Other uses)
The electrolytic copper foil and surface-treated copper foil of the present invention are thin, have few pinholes, and are excellent in smoothness. Such electrolytic copper foils and surface-treated copper foils can also be suitably used, for example, as negative electrode current collectors for lithium ion secondary batteries and the like.

Although the embodiment of the present invention has been described above, the above embodiment is merely an example of the present invention. The present invention includes all aspects included in the concept and claims of the present invention, and can be variously modified within the scope of the present invention.

EXAMPLES The present invention will be described in more detail below based on examples, which are examples of the present invention.

(Examples 1 to 16 and Comparative Examples 1 to 5)
Using the following cathode and anode, an electrolytic solution having the composition shown in Table 1, and electrolysis conditions, a rolled electrolytic copper foil was produced. In addition, the foil thickness of Table 1 is the value measured by the evaluation method mentioned later.

<Cathode>
A rotary drum made of titanium was used for the cathode.

The cathodic reduction was performed by removing the oxide film on the surface of the rotating drum made of titanium under the following conditions using the cathode reduction apparatus as shown in FIG. 2 and the electrolytic solution having the composition shown in Table 1. .
・Cathode reduction conditions Bath temperature: 65°C
Current density: 12A/ ^dm2
Processing time: 10 minutes

In Table 1, "-" means that cathodic reduction was not performed, and in this case, the surface of the rotating drum made of titanium was polished by #1000 to #2000 buffing as in the past. to remove the oxide film.

<Anode>
A dimensionally stable anode DSA (registered trademark) was used as the anode.

<Electrolyte>
In the electrolytic solutions shown in Table 1, copper sulfate pentahydrate was used as the copper source, and hydrochloric acid was used as the chlorine source.

<Electrolysis conditions>
Copper was deposited under the conditions shown in Table 1 by constant current electrolysis or PR electrolysis. In Table 1, "-" means that constant current electrolysis or PR electrolysis was not performed.
In PR electrolysis in Table 1, for example, when the current density (forward electrolysis 0.5 ms/reverse electrolysis 0.05 ms) is described as 45/45 (A/dm ² ), forward electrolysis is performed at 45 A/dm ² . Immediately after performing 0.5 ms, reverse electrolysis was performed at 45 A / dm ² for 0.05 ms, and this forward electrolysis and reverse electrolysis were alternately repeated (PR electrolysis is “45/45” in Table 1). Other cases are interpreted in the same way).

[Evaluation (1)]
The following characteristic evaluations were performed on the electrodeposited copper foils according to the above examples and comparative examples. The evaluation conditions for each property are as follows, and each measurement was performed at room temperature unless otherwise specified. Table 2 shows the results.

[Foil thickness]
The thickness of the electrolytic copper foil was measured as a mass thickness with an electronic balance. Table 1 shows the results.

[Number density of pinholes]
First, an electrolytic copper foil was cut into a size of 200 mm×200 mm to prepare a sample for measurement.
Next, using the measurement sample, pinholes were marked by a light transmission method, and the number of pinholes was counted for each dimension. Based on the number of pinholes counted, the number density of pinholes was calculated as the number of pinholes per unit area (1 m ² ).
In addition, the pinhole dimensions were measured using a digital microscope (VHX-100, manufactured by KEYENCE CORPORATION). As the pinhole shape, the dimension of the longest portion of the shape was measured, and this was estimated as the longitudinal dimension. The LIGHTCONTROL value of the irradiated backlight was Max.

[Surface roughness Rz]
The surface roughness Rz is measured by measuring the surface shape using a white light interference optical microscope (Wyko Contour GT-K, manufactured by BRUKER) using a normal electrolytic copper foil as a measurement object, and further analyzing the shape. gone. The shape analysis uses a high-resolution CCD camera in the VSI measurement method, the light source is white light, the measurement magnification is 10 times, the measurement range is 477 μm × 357.8 μm, the lateral sampling is 0.38 μm, the speed is 1, the backscan is 10 μm, Length is 10 μm, Threshold is 3%. Filtering is performed with TermsRemoval (Cylinder and Tilt), DataRestore (Method: legacy, iterations 5), StatisticFilter (FilterSize: 3, FilterType: Median), and then data is processed. did.
The measurement is performed at arbitrary five points on each of the S and M surfaces of the electrolytic copper foil, and the average value calculated from the measured values (N = 5 for each) is the surface roughness Rz of the S and M surfaces. bottom.
In this example, the case where the surface roughness Rz of the S surface was 3.00 μm or less and the surface roughness Rz of the M surface was 6.00 μm or less was evaluated as good.

[Tensile strength and elongation]
First, the electrodeposited copper foil was cut into a size of 12.7 mm×130 mm, and 10 samples for each measurement were prepared.
Next, five of the measurement samples were heated at 300° C. for 1 hour, naturally cooled to room temperature, and heat-treated at 300° C. for 1 hour to obtain measurement samples.
A tensile tester (1122 type, manufactured by Instron) was used for each of five measurement samples in a normal state without heat treatment and five measurement samples in a state after heat treatment at 300 ° C. for 1 hour. Then, a tensile test was performed according to the provisions of IPC-TM-650.
In the tensile test, the distance between chucks was 70 mm and the tensile speed was 50 mm/min, and the tensile strength and elongation were measured. In addition, about elongation, the elongation in a normal state was measured. Also, the elongation refers to the elongation rate when the test piece breaks.
The average values calculated from the obtained measured values (N=5 for each) were taken as the tensile strength and elongation of each electrodeposited copper foil.

As shown in Table 2, in the electrodeposited copper foils produced in Examples 1 to 16, the existence density of pinholes having a longitudinal dimension of 2 to 10 μm was controlled to 800 or less per 1 m ² of the electrodeposited copper foil. ing. In such an electrolytic copper foil, the existence density of pinholes having a longitudinal dimension of 2 to 10 μm on both the S surface and the M surface is not controlled to 800 or less per 1 m ² of the electrolytic copper foil Comparative Example 1 It was confirmed that the surface roughness Rz was smaller than that of the electrodeposited copper foil of No. 1 to No. 5, and that the surface was very smooth.

Furthermore, in the electrodeposited copper foils of Examples 1 to 16, the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is controlled to 800 or less per 1 m ² of the electrodeposited copper foil, so the longitudinal dimension is 30 μm. No pinholes exceeding .

In addition, the electrodeposited copper foils of Examples 1 to 16 are superior to the electrodeposited copper foils of Comparative Examples 1 to 16 in tensile strength and elongation in a normal state, and even after heat treatment at 300 ° C. for 1 hour, the tensile strength is It was confirmed that the heat resistance was maintained high and the heat resistance was also excellent.

(Example 21)
[1] Formation of roughening treatment layer The electrolytic copper foil produced in Example 1 is used as a copper foil substrate, and the S surface of the copper foil substrate is subjected to roughening plating treatment by a roll-to-roll method, and the thickness is A roughened layer of 1 μm was formed. The roughening plating treatment was performed using the electrolytic solution having the composition shown in Table 3 under the following electrolysis conditions.

<Electrolyte>
In the electrolytic solutions shown in Table 3, copper sulfate pentahydrate was used as the copper source, (NH ₄ ) ₆ Mo ₇ O _{24.4H 2} O was used as the molybdenum source, and NiCl _{2.6H 2} O was used as the nickel source.

<Conditions for roughening plating>
Current density: 30A/ ^dm2
Treatment time: 1 minute Bath temperature: Shown in Table 3.

[2] Formation of metal treatment layer Subsequently, the surface of the roughening treatment layer formed in [1] above is plated with Ni, Zn, and Cr in this order under the following conditions to form a metal treatment layer (intermediate layer). formed.

<Ni plating conditions>
Nickel sulfate: 5.0 g/L in terms of Ni
Ammonium persulfate: 25.0g/L
Boric acid: 30.5g/L
Bath temperature: 28.5°C
pH: 4.0
Current density: 1.5A/ ^dm2
Processing time: 2 seconds

<Zn plating conditions>
Zinc sulfate heptahydrate: 30 g/L in terms of Zn
Sodium hydroxide: 200g/L
Bath temperature: 60°C
Current density: 10A/ ^dm2
Processing time: 1 minute

<Cr plating conditions>
Chromic anhydride CrO ₃ : 2.5 g/L in terms of Cr
Bath temperature: 45°C
pH: 2.5
Current density: 0.5A/ ^dm2
Processing time: 2 minutes

[3] Formation of Silane Coupling Agent Layer Further, the treatment shown below was performed to form a silane coupling agent layer on the chromate treatment layer. That is, methanol or ethanol was added to an aqueous solution of a silane coupling agent to adjust the pH to a predetermined value, thereby obtaining a treatment liquid. A silane coupling agent layer was formed by applying this treatment liquid to the chromate treatment layer of the surface-treated copper foil, holding it for a predetermined time, and then drying it with hot air. As the silane coupling agent, 3-mercaptopropyltrimethoxysilane (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) was used, and an aqueous solution of the silane coupling agent was prepared under the conditions of a concentration of 1.0% and a pH of 4.0. .

(Examples 22-39 and Comparative Examples 21-24)
Examples 22 to 39 and Comparative Examples 21 to 24 are the same as Example 21, except that in the step [1] of forming the roughened layer, the conditions for the roughening plating treatment were as described in Table 3 above. A surface-treated copper foil was obtained by the method of

[Evaluation (2)]
The following characteristic evaluations were performed on the surface-treated copper foils according to the above examples and comparative examples. The evaluation conditions for each property are as follows, and each measurement was performed at room temperature unless otherwise specified. Table 4 shows the results.

The pinhole number density, surface roughness Rz, tensile strength and elongation were measured under the same conditions as in the above evaluation (1). For the surface roughness Rz, the surface roughness Rz of the non-roughened surface of the surface-treated copper foil opposite to the surface on which the roughened layer is formed was measured.

[Circuit characteristics]
Circuit characteristics were evaluated by forming a circuit on the roughened surface of the surface-treated copper foil by the subtractive method according to the following procedure, and measuring the breakage rate and the etching factor.

(circuit formation)
First, the surface-treated copper foil is attached as a resin substrate to an insulating resin (RA550 (W), manufactured by Panasonic Corporation), etched using a dry resist film, and L & S = 30 μm / 30 μm line width / A line-to-line pitch resist pattern was formed. As an etchant, a mixed solution of copper chloride and hydrochloric acid was used.

<Disconnection rate>
For the above circuit, 100 wiring patterns obtained were observed, and the number of wiring patterns in which disconnection was confirmed was counted. Observation was performed using a digital microscope (same as above). Based on the observation results, the disconnection rate (%) was estimated as the number of disconnected wiring patterns out of 100 observed wiring patterns.
In this example, the wire breakage rate of 0% was evaluated as acceptable.

<Etching factor (Ef)>
The etching factor (Ef) of the wiring pattern obtained for the above circuit was measured.
The etching factor is defined by the following formula, where H is the thickness (μm) of the copper foil, B is the bottom width (μm) of the formed wiring pattern, and T is the top width (μm) of the formed wiring pattern. is a value indicated by The foil thickness H of the copper foil was the thickness of the surface-treated copper foil. In addition, each dimension of the bottom width B and the top width T was measured with a digital microscope (same as above) for the wiring pattern when the just-etched position (the position of the edge of the resist and the position of the bottom of the wiring pattern are aligned). Observation was performed using a stencil, and each dimension was measured. The measurements were made on arbitrary five wiring patterns, and the average value calculated from the measured values (N=5) was taken as the etching factor of the circuit.
Ef = 2H/(BT)
In this example, the case where the value of Ef was 2.5 or more was evaluated as acceptable. If the value of Ef is small, the perpendicularity of the side walls of the wiring pattern is lost, and there is a risk of disconnection when forming a fine wiring pattern with a narrow line width.

As shown in Table 4, the surface-treated copper foils (Examples 21 to 39) using the electrolytic copper foil of the example of the present invention as a copper foil substrate have pinholes with a longitudinal dimension of 2 to 10 μm. The density can be 800 or less per 1 m ² of electrolytic copper foil. Therefore, it was confirmed that when a printed wiring board was produced using such a surface-treated copper foil, the disconnection rate could be effectively suppressed.

Moreover, it was confirmed that such a surface-treated copper foil can achieve excellent smoothness on the non-roughened surface on which the surface state of the copper foil substrate is likely to be reflected. Therefore, it was confirmed that a high etching factor can be realized when a printed wiring board is produced using such a surface-treated copper foil.

Furthermore, since the electrodeposited copper foils of the examples of the present invention already have high tensile strength and elongation and excellent heat resistance by themselves, surface-treated copper foils using the electrodeposited copper foil as a copper foil base are also possible. It was confirmed that high tensile strength and elongation as well as excellent heat resistance can be achieved.

On the other hand, in the surface-treated copper foils (Comparative Examples 21 to 24) using the electrolytic copper foil of the comparative example of the present invention as a copper foil substrate, the existence density of pinholes having a longitudinal dimension of 2 to 10 μm was It cannot be 800 or less per 1 m ² of copper foil. Therefore, it was confirmed that disconnection occurs when a printed wiring board is produced using such a surface-treated copper foil.

In addition, it was confirmed that such a surface-treated copper foil cannot achieve excellent smoothness on the non-roughened surface because the smoothness of the copper foil substrate is inferior. Therefore, when a printed wiring board was produced using such a surface-treated copper foil, disconnection occurred, and it was confirmed that the etching factor was lower than that of the surface-treated copper foils of the examples of the present invention. .

Furthermore, the electrodeposited copper foil of the comparative example of the present invention is inferior to the electrodeposited copper foil of the example of the present invention in terms of tensile strength, elongation, and heat resistance of itself, so the tensile strength of the surface-treated copper foil obtained is It was confirmed that the strength, elongation and heat resistance were inferior to those of the surface-treated copper foils of the examples of the present invention.

101 Deposited Copper Foil 102 Drum 103 Buffing Device 104 Electrolyte Solution 105 Cathode Reduction Device 106 Electrolyte Solution

Claims (9)

An electrolytic copper foil having a thickness of 9 μm or less, excluding a copper foil with a carrier,
The existence density of pinholes having a longitudinal dimension of 2 to 10 μm is 800 or less per 1 m ² of the electrolytic copper foil,
The existence density of pinholes having a longitudinal dimension of 2 to 30 μm is 800 or less per 1 m ² of the electrolytic copper foil,
An electrolytic copper foil having a surface roughness Rz measured with a white interference microscope of 1.5 to 3.0 μm on the glossy surface (S surface) and 2.0 to 6.0 μm on the rough surface (M surface). . The existence density of pinholes having a longitudinal dimension of 2 to 10 μm is 100 or less per 1 m ² of the electrolytic copper foil,
2. The electrolytic copper foil according to claim 1, wherein the density of pinholes having a longitudinal dimension of 2 to 30 μm is 100 or less per 1 m ² of the electrolytic copper foil. The electrolytic copper foil according to claim 1 or 2, having a thickness of 6 µm or less. Tensile strength in normal state is 400 to 650 MPa,
Tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour is 300 MPa or more,
The electrolytic copper foil according to any one of claims 1 to 3, which has an elongation of 2.5% or more in a normal state. The electrolytic copper foil according to any one of claims 1 to 4, which is used for manufacturing a printed wiring board. A method for producing a surface-treated copper foil having a surface-treated film containing a roughened layer by forming roughened particles on one surface of a copper foil substrate, comprising:
The copper foil substrate is the electrolytic copper foil according to any one of claims 1 to 4,
A method for producing a surface-treated copper foil, wherein the existence density of pinholes having a longitudinal dimension of 2 to 10 μm is 800 or less per 1 m ² of the surface-treated copper foil. The surface-treated copper according to claim 6, wherein the surface of the surface-treated copper foil opposite to the surface-treated film has a surface roughness Rz of 1.5 to 6.0 µm as measured by the white interference microscope. Foil manufacturing method . A method for producing a copper-clad laminate , comprising laminating a resin substrate on the roughened surface of the surface-treated copper foil obtained by the production method according to claim 6 or 7. A method for manufacturing a printed wiring board using the copper-clad laminate obtained by the manufacturing method according to claim 8 .

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