JP7051988B1 - Roughened copper foil, copper-clad laminate, and printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roughened copper foil capable of manufacturing a printed wiring board or the like which has excellent adhesion to a resin, has a small transmission loss, and is less likely to cause a short circuit due to migration. SOLUTION: A roughened copper foil has a roughened surface on which a plurality of roughened particles 1 are formed on at least one surface, and irregularities are formed on the surface of the roughened particles 1. The developed area ratio Sdr of the interface of the roughened surface measured using a three-dimensional white light interference type microscope is 1000% or more and 5000% or less, and the arithmetic mean roughness Sa of the roughened surface is 0. It is 04 μm or more and 0.6 μm or less. [Selection diagram] Fig. 1

Description

The present invention relates to a roughened copper foil that can be suitably used for manufacturing a printed wiring board or the like, and a copper-clad laminated board and a printed wiring board using the roughened copper foil.

The copper-clad laminate is manufactured by crimping a copper foil and a resin substrate, and is roughened by forming roughened particles on the surface of the copper foil and roughening the surface of the copper foil. By crimping the resin substrate to the roughened surface, the adhesion between the copper foil and the resin substrate is improved.

The height of the roughened particles (that is, between the surface of the copper foil before the roughening treatment and the tip of the roughened particles formed so as to protrude from the surface of the copper foil before the roughening treatment. If the distance is increased, which is also referred to as “roughening height” hereafter), the adhesion between the copper foil and the resin substrate can be further improved. However, when a printed wiring board is manufactured using a copper foil having a large roughened height, there is a problem that a transmission loss becomes large due to the skin effect. That is, there was a trade-off relationship between the adhesion between the copper foil and the resin substrate and the transmission loss.

On the other hand, as the printed wiring board becomes more compatible with high frequencies in recent years, if the coarsening height is reduced in order to reduce the transmission loss, migration is likely to occur when the printed wiring board is used, and a short circuit occurs in the circuit of the printed wiring board. A new problem has emerged that is more likely to occur.

Patent Document 1 discloses a copper foil having high adhesion to a resin substrate, and Patent Document 2 discloses a copper foil capable of manufacturing a printed wiring board having a small transmission loss. .. However, the copper foil disclosed in Patent Documents 1 and 2 may not be able to satisfy both the characteristics of adhesion and transmission loss at the same time. In addition, there is a risk that it will not be possible to manufacture a printed wiring board that is unlikely to cause migration.

Patent No. 6332739 Patent No. 6462961

An object of the present invention is to provide a roughened copper foil and a copper-clad laminate capable of producing a printed wiring board or the like having excellent adhesion to a resin, small transmission loss, and less likely to cause a short circuit due to migration. do. Another object of the present invention is to provide a printed wiring board which has excellent adhesion to a resin, has a small transmission loss, and is less likely to cause a short circuit due to migration.

The roughened copper foil according to one aspect of the present invention is a roughened copper foil having a roughened surface on which a plurality of roughened particles are formed on at least one surface, and is formed on the surface of the roughened particles. Unevenness is formed, the developed area ratio Sdr of the interface of the roughened surface measured using a three-dimensional white light interference type microscope is 1000% or more and 5000% or less, and the arithmetic mean coarseness of the roughened surface is The gist is that Sa is 0.04 μm or more and 0.6 μm or less.

Further, it is a gist that the copper-clad laminate according to another aspect of the present invention includes the roughened copper foil according to the above aspect.
Further, it is a gist that the printed wiring board according to another aspect of the present invention includes the roughened copper foil according to the above aspect.

In the prior arts International Publication No. 2019/188712 and Patent No. 6430092, protrusions called substantially spherical protrusions are formed on the surface of the roughened particles of copper foil by electroplating to form the surface of the roughened particles. A copper foil having irregularities is disclosed. These prior arts disclose that the unevenness of the surface of the roughened particles allows the roughened particles to have small but large mechanical strength.

However, when the substantially spherical protrusions are formed by electrolytic plating, it is considered that the plating is concentrated on the apex of the roughened particles in which the current is concentrated. As a result, the height of the roughened particles as a whole may be partially increased, and the transmission characteristics may be deteriorated.
Further, since International Publication No. 2019/188712 and Patent No. 6430092 do not describe the transmission characteristics and the migration caused by the interface length of the contact surface between the copper foil and the resin, can the problem of the present invention be solved? I can't confirm.

On the other hand, in the roughened copper foil according to one aspect of the present invention, since the formation of irregularities on the surface of the roughened particles can be performed by etching treatment in a solution as described later, the roughened particles can be formed. Unevenness can be formed on the surface of the roughened particles without increasing the height.
That is, as compared with the copper foil disclosed in the above two prior arts, the roughened copper foil according to one aspect of the present invention can improve the adhesion to the resin while keeping the transmission characteristics small. Further, since the surface area of the roughened particles is increased by forming irregularities on the entire surface or a part of the surface of the roughened particles, it is possible to manufacture a printed wiring board or the like in which short circuits due to migration are unlikely to occur.

The roughened copper foil and the copper-clad laminate of the present invention can manufacture a printed wiring board or the like which has excellent adhesion to a resin, has a small transmission loss, and is less likely to cause a short circuit due to migration. The printed wiring board of the present invention has excellent adhesion to the resin, has a small transmission loss, and is less likely to cause a short circuit due to migration.

It is a schematic cross-sectional view explaining the shape and the roughening height of the roughened particles formed on the roughened surface of the roughened copper foil of this embodiment. It is a figure explaining the method of manufacturing the electrolytic copper foil using the electrolytic precipitation apparatus. It is a figure explaining the manufacturing method of the roughened copper foil of this embodiment, and is the scanning electron microscope image which shows the shape of the roughened particles formed by the roughened plating treatment. It is a figure explaining the manufacturing method of the roughened copper foil of this embodiment, and is the scanning electron microscope image which shows the unevenness formed on the surface of the roughened particle.

An embodiment of the present invention will be described. The embodiments described below show an example of the present invention. In addition, various changes or improvements can be added to the present embodiment, and the embodiment to which such changes or improvements are added can also be included in the present invention.

The roughened copper foil according to an embodiment of the present invention is a roughened copper foil having a roughened surface on which a plurality of roughened particles are formed on at least one surface, and is formed on the surface of the roughened particles. Has irregularities, and the developed area ratio Sdr of the interface of the roughened surface measured using a three-dimensional white light interference type microscope is 1000% or more and 5000% or less, and the arithmetic mean of the roughened surface. The roughness Sa is 0.04 μm or more and 0.6 μm or less.

From such a configuration, the roughened copper foil of the present embodiment can manufacture a printed wiring board or the like which has excellent adhesion to a resin, has a small transmission loss, and is less likely to cause a short circuit due to migration. Therefore, the roughened copper foil according to the present embodiment can be suitably used for manufacturing a copper-clad laminated board or a printed wiring board.

That is, the copper-clad laminate of the present embodiment includes the roughened copper foil of the present embodiment. By using the roughened copper foil of the present embodiment, it is possible to manufacture a copper-clad laminate having excellent adhesion to a resin. Further, the printed wiring board of the present embodiment includes the copper-clad laminated board of the present embodiment. By using the roughened copper foil and the copper-clad laminate of the present embodiment, it is possible to manufacture a printed wiring board which has excellent adhesion to a resin, has a small transmission loss, and is less likely to cause a short circuit due to migration.

Hereinafter, the roughened copper foil of the present embodiment will be described in more detail with reference to the drawings.
The roughened copper foil of the present embodiment has a roughened surface roughened by the roughening treatment on at least one surface thereof. This roughening treatment is a treatment for forming a plurality of roughened particles 1 on the surface 3 of a copper foil (hereinafter, also referred to as “raw material copper foil”) which is a raw material of the roughened copper foil. A roughened surface is formed on the surface of the roughened copper foil by the roughening treatment.

As shown in FIG. 1, the roughened particles 1 are formed so as to protrude from the surface 3 of the raw material copper foil. The distance H between the surface 3 of the raw material copper foil and the tip of the roughened particles 1 is the roughened height. Then, irregularities are formed on the surface of the roughened particles 1. In the roughened copper foil of FIG. 1, a part of the surface of the roughened particles 1 is removed by etching or the like, and as a result, a plurality of convex portions 1a are formed on the surface of the roughened particles 1, resulting in unevenness. It is formed.

The roughened particles 1 are preferably formed of metallic copper or a copper alloy. Examples of the shape of the roughened particles 1 include a convex shape having a sharp tip, and specific examples thereof include a cone shape, a triangular pyramid shape, a quadrangular pyramid shape, an elliptical shape, and a hemispherical shape. Alternatively, a portion other than the tip portion may have a cylindrical or prismatic shape, and the tip portion may have a conical shape, a triangular pyramid shape, a quadrangular pyramid shape, an elliptical shape, or a hemispherical shape.

The roughening height can be expressed by the arithmetic mean roughness Sa specified in ISO25178. The roughened copper foil of the present embodiment has a small roughening height because the arithmetic mean roughness Sa of the roughened surface is 0.04 μm or more and 0.6 μm or less. When a printed wiring board is manufactured using a copper foil having a large roughened height, a transmission loss increases due to the skin effect, but the roughened copper foil of the present embodiment has a small roughened height on the roughened surface. If a printed wiring board is manufactured using the roughened copper foil of the present embodiment, the transmission loss is small even when a high-frequency signal is transmitted to the circuit of the obtained printed wiring board. Therefore, the roughened copper foil of the present embodiment can be suitably used for manufacturing a printed wiring board having a high frequency circuit.

In order to further reduce the transmission loss of the printed wiring board, the arithmetic mean roughness Sa of the roughened surface of the roughened copper foil of the present embodiment is preferably 0.04 μm or more and 0.45 μm or less, and is 0. It is more preferably 4.04 μm or more and 0.35 μm or less, further preferably 0.04 μm or more and 0.3 μm or less, and particularly preferably 0.1 μm or more and 0.3 μm or less.

Further, since the surface of the roughened particles 1 has irregularities, the surface area of the roughened surface becomes large. The size of the surface area can be expressed by the developed area ratio Sdr of the interface defined in ISO25178, and the developed area ratio Sdr of the interface can be measured by using a three-dimensional white light interference type microscope. The developed area ratio Sdr of the interface of the roughened surface measured by using a three-dimensional white light interference type microscope needs to be 1000% or more and 5000% or less.

When the developed area ratio Sdr of the interface is within the above range, the surface area of the roughened treated surface is large. Therefore, when the resin is laminated on the roughened treated surface of the roughened treated copper foil of the present embodiment, the roughening height is high. Although the surface area is small, a sufficiently large anchor effect can be obtained, and the adhesion between the roughened copper foil and the resin is excellent.

In addition, as a result of diligent studies by the present inventors, it was found that the surface area of the roughened copper foil at the interface when the roughened copper foil and the resin are bonded is related to migration, and the surface of the roughened surface is roughened. It was found that migration is unlikely to occur if the arithmetic mean roughness Sa and the developed area ratio Sdr of the interface are within the above ranges. That is, if the roughened height is small, migration is likely to occur when the printed wiring board is used, and a short circuit is likely to occur in the circuit of the printed wiring board. Since the surface area of the chemical treatment surface is large, migration is less likely to occur, and a short circuit is less likely to occur in the circuit of the printed wiring board.

The short circuit of the printed wiring board circuit due to migration will be described in more detail as follows.
When a resin substrate is laminated on the roughened surface of the roughened copper foil when manufacturing a copper-clad laminate, the roughened particles on the roughened surface are embedded in the resin, so the roughened copper foil is etched. After being removed by such means, the surface of the resin substrate facing the removed roughened copper foil has a replica shape to which the uneven shape of the roughened surface is transferred.

In the printed wiring board manufactured by using the above-mentioned copper-clad laminated board, migration proceeds along the adhesion interface between the resin having the replica shape of the roughened surface and the roughened copper. If the roughening height of the roughened surface of the foil is small, the migration progress path leading to the short circuit becomes short, so that a short circuit due to migration is likely to occur.

Further, if the roughened height of the roughened surface of the roughened copper foil is small, the anchor effect is reduced, so that the adhesion between the resin having the replica shape of the roughened surface and the resin is weakened, and voids are formed. It becomes easy to be formed. If there is a gap between the resin and the resin, moisture and ions enter into the gap, and the copper in the circuit wiring is easily eluted as ions, and the migration is facilitated.

If a copper-clad laminated board or a printed wiring board is manufactured using the roughened-treated copper foil of the present embodiment, unevenness is formed on the surface of the roughened particles of the roughened-treated copper foil, so that the roughened surface of the roughened-treated surface can be manufactured. The surface shape of the resin having the replica shape is also the same as the roughened surface of the roughened copper foil. Therefore, even though the roughened height of the roughened surface of the roughened copper foil is small, the migration progress path leading to the short circuit becomes dramatically longer.

Further, since unevenness is formed on the surface of the roughened particles of the roughened copper foil and the surface area of the roughened surface is large, the surface area of the resin having a replica shape of the roughened surface is also large. Therefore, although the roughened height of the roughened surface of the roughened copper foil is small, the adhesion between the resin having the replica shape of the roughened surface becomes stronger and the voids are less likely to be formed. , Migration becomes difficult to proceed.

As described above, if a copper-clad laminated board or a printed wiring board is manufactured using the roughened copper foil of the present embodiment, unevenness is formed on the surface of the roughened particles of the roughened copper foil. Despite the small roughening height of the roughened surface of the roughened copper foil, the progress path of migration leading to a short circuit is dramatically lengthened, and the resin has a replica shape of the roughened surface. Adhesion with the resin becomes stronger. As a result, short circuits in the printed wiring board circuit due to migration are less likely to occur.

In order to strengthen the adhesion between the roughened copper foil and the resin and to make it more difficult for the circuit of the printed wiring board to be short-circuited due to migration, the roughened surface of the roughened copper foil of the present embodiment is used. The developed area ratio Sdr of the interface is preferably 2000% or more and 5000% or less, and more preferably 3000% or more and 5000% or less.

The developed area ratio Sdr and the arithmetic average roughness Sa of the interface of the roughened surface of the roughened copper foil of the present embodiment are a three-dimensional white light interference type microscope, a scanning electron microscope, and an electron beam three-dimensional roughness analyzer. It can be obtained by measuring and evaluating the unevenness difference of the roughened surface by using the above.

As described above, the roughened copper foil of the present embodiment has a small roughened height on the roughened surface and a large surface area on the roughened surface, so that it has excellent adhesion to the resin and is transmitted. It is possible to manufacture a printed wiring board or the like that simultaneously satisfies the three characteristics of low loss and less likely to cause a short circuit due to migration.

The ten-point average roughness Rz of the roughened surface is preferably 0.6 μm or more and 1.4 μm or less. If the ten-point average roughness Rz of the roughened surface is within the above range, the transmission loss can be surely reduced, and the adhesion between the roughened copper foil and the resin can be surely strengthened. The ten-point average roughness Rz of the roughened surface can be measured using a contact type surface roughness measuring machine according to the method specified in JIS B0601: 2001.

Further, in the roughened copper foil of the present embodiment, a rust-preventive treatment layer may be laminated on the roughened-treated surface, and a chemical adhesion agent layer may be further laminated on the rust-preventive treatment layer. With such a configuration, the rust-preventive layer enhances the rust-preventive property of the roughened surface, and the chemical adhesive layer further enhances the adhesion between the roughened surface and the resin.

Next, an example of the method for manufacturing the roughened copper foil of the present embodiment will be described.
(1) Method for manufacturing electrolytic copper foil As the raw material copper foil used for producing the roughened copper foil of the present embodiment, an electrolytic copper foil having a smooth and glossy surface without coarse irregularities and rolling. Copper foil is preferred. Among these copper foils, electrolytic copper foil is more preferable from the viewpoint of productivity and cost, and electrolytic copper foil having smooth both sides, which is generally called "double-sided glossy foil", is particularly preferable.

Since the roughened copper foil of the present embodiment can be produced using an electrolytic copper foil as a raw material copper foil, a method for producing the electrolytic copper foil will first be described with reference to FIG.
The electrolytic copper foil can be produced, for example, by using an electrolytic precipitation device as shown in FIG. The electrolytic precipitation device of FIG. 2 includes an insoluble electrode 12 made of titanium coated with a platinum group element or an oxide thereof, and a titanium rotating electrode 11 provided facing the insoluble electrode 12.

Copper plating is performed using an electrolytic precipitation device, copper is deposited on the surface (columnar surface) of the columnar rotating electrode 11 to form a copper foil, and the copper foil is peeled off from the surface of the rotating electrode 11. Electrolytic copper foil can be manufactured. More specifically, when copper plating is performed, a current is applied using the rotating electrode 11 as a cathode and the insoluble electrode 12 as an anode. As the insoluble electrode 12, for example, a DSE (Dimensionally Stable Electrode) electrode (registered trademark) can be used. Further, as the electrolytic solution 13, for example, an aqueous solution containing sulfuric acid and copper sulfate can be used. Additives such as organic additives and inorganic additives may be added to the electrolytic solution 13. One type of additive may be used alone, or two or more types may be used in combination.

While supplying the electrolytic solution 13 from the electrolytic solution supply unit (not shown) between the rotating electrode 11 and the insoluble electrode 12 (see the white arrow) and rotating the rotating electrode 11 in the direction indicated by the dotted arrow at a constant speed, When a DC current is applied between the rotating electrode 11 and the insoluble electrode 12, copper is deposited on the surface of the rotating electrode 11. The electrolytic copper foil 14 is obtained by peeling the precipitated copper from the surface of the rotating electrode 11, pulling it up as shown by the solid arrow in FIG. 2, and continuously winding it.

(2) Roughing treatment At least one of both sides of the raw material copper foil is roughened to form a roughened surface on which a plurality of roughened particles are formed. As shown in FIG. 3, a plurality of roughened particles are formed on the surface of the raw material copper foil. At this time, no unevenness is formed on the surface of the roughened particles, and the surface is relatively smooth.

The electric field precipitation start surface (shiny surface) of a normal electrolytic copper foil is relatively smooth and glossy, and the electrolytic precipitation end surface (matte surface), which is the opposite surface, generally has irregularities. Further, in the double-sided glossy foil, both the electric field precipitation start surface and the electrolytic precipitation end surface are relatively smooth and glossy, but the electrolytic precipitation end surface is smoother and glossy. The roughening treatment may be applied to either side of both sides of the electrolytic copper foil, but even if either ordinary electrolytic copper foil or double-sided glossy foil is used, the roughening treatment is smoother and glossier. It is preferable to perform a roughening treatment on one side.
The roughening treatment can be performed, for example, by a two-step plating treatment as shown below. It is not necessary to perform the second-stage fixed plating process.

(First stage: roughened plating)
The first-stage roughening plating treatment is a treatment for forming roughened particles on at least one surface of the raw material copper foil. Specifically, it is a process of performing copper plating in a copper sulfate bath. In the copper sulfate bath (basic bath for roughened plating), molybdenum (Mo), arsenic (As), and antimony (Sb) are used for the purpose of suppressing the shedding of roughened particles from the surface of the raw material copper foil, that is, "powder falling". ), Bismuth (Bi), selenium (Se), tellurium (Te), tungsten (W) and the like may be added as an additive, and molybdenum is particularly preferable.

An example of the conditions for the rough plating process is shown below.
Concentration of copper sulfate pentahydrate in copper sulfate bath: 5 to 15 g / L in terms of copper (atom)
Concentration of sulfuric acid in copper sulfate bath: 120-250 g / L
Concentration of ammonium molybdate in copper sulfate bath: 500-1000 mg / L in terms of molybdenum (atom)
Copper sulfate bath temperature: 15-20 ° C
Processing speed: 8 to 20 m / min Current density: 5 to 55 A / dm ²
Processing time: 0.5-5.0 seconds

(Second stage: fixed plating)
The second-stage fixed plating treatment is a treatment in which a smooth covering plating is applied to the roughened surface formed by the roughening plating treatment described above. Specifically, it is a process of performing copper plating in a copper sulfate bath. Usually, this fixed plating process is performed in order to suppress the shedding of the roughened particles, that is, to immobilize the roughened particles.

In the roughened copper foil of the present embodiment, the fixed plating treatment is not essential and can be performed as needed. For example, in the production of a copper-clad laminate, when it is combined with a flexible resin substrate using a hard resin such as polyimide resin, the roughened surface is subjected to a fixed plating treatment to prevent the roughened particles from falling off. Therefore, it is preferable to perform a fixed plating process.

An example of the conditions for the fixed plating process is shown below.
Concentration of copper sulfate pentahydrate in copper sulfate bath: 50-65 g / L in terms of copper (atom)
Concentration of sulfuric acid in copper sulfate bath: 80-170 g / L
Processing speed: 5 to 20 m / min Current density: 1 to 7 A / dm ²

(3) Pretreatment Before the treatment for forming irregularities on the surface of the roughened particles, a pretreatment for promoting the formation of the irregularities may be performed on the roughened surface. Examples of this pretreatment include electrogalvanization.

When the roughened surface is slightly electrozinc-plated, a uniform galvanized layer is not formed on the surface of the copper foil, but a non-uniform galvanized layer depending on the shape of the roughened particles is formed. Further, it is considered that copper and zinc are easily alloyed to brass, and the alloy composition thereof is also non-uniform as in the non-uniform galvanized layer. That is, when the outermost surface of the copper foil is viewed from a microscopic point of view, there are places where zinc is exposed, places where brass is exposed, and places where brass with different composition ratios is exposed. Become. Since each of these locations is etched with an acid differently, as a result, unevenness is likely to be efficiently formed on the surface of the roughened particles by the subsequent treatment for forming unevenness.

Electrozinc plating can be performed using, for example, an alkaline zinc plating solution. The concentration of zinc in the alkaline galvanizing solution is preferably 2 to 8 g / L. When the zinc concentration of the alkaline zinc plating solution is within the above range, the current efficiency of zinc is suitable, so that effective zinc plating can be easily obtained, and precipitation is less likely to occur in the alkaline zinc plating solution, so that the alkali is alkaline. The stability of the zinc plating solution is excellent.

The alkaline zinc plating solution preferably contains sodium hydroxide (NaOH), and the concentration thereof is preferably 20 to 45 g / L. When the concentration of sodium hydroxide in the alkaline zinc plating solution is within the above range, the conductivity of the alkaline zinc plating solution is suitable, so that an effective zinc plating amount can be easily obtained and the plated zinc is alkaline. Difficult to re-dissolve in zinc plating solution. When the plated zinc is redissolved in the alkaline zinc plating solution, there is a possibility that the surface of the roughened particles may have insufficient formation of irregularities in the subsequent treatment for forming irregularities.
The current density during electrozinc plating is preferably 0.1 to 1 A / dm ² , and the processing time is preferably 1 to 5 seconds.

Another pretreatment includes, for example, an oxidation treatment such as natural oxidation. By slightly oxidizing the surface of the roughened particles on the roughened surface, the subsequent treatment for forming irregularities facilitates the efficient formation of irregularities on the surface of the roughened particles.

An example of the method of natural oxidation is shown. After the copper foil is dried, it can be slightly oxidized on the surface of the copper foil by leaving it in the air for 12 to 48 hours. Also in this case, since the parts that are easily naturally oxidized differ depending on the surface of the roughened particles of the copper foil, the parts having different thicknesses of the oxide film are formed from a microscopic point of view. Since each of these parts is etched with an acid differently, as a result, it is considered that unevenness is likely to be formed on the surface of the roughened particles by the subsequent treatment for forming unevenness.

If the treatment time for natural oxidation is within the above range, an oxide film having a suitable average thickness can be obtained, so that inconvenience is unlikely to occur in the subsequent treatment. For example, if oxidation is performed for more than 48 hours, the oxidation proceeds too much. Therefore, when the roughened copper foil is subjected to the rust preventive treatment by electrolytic plating, a rust preventive treatment layer having a sufficient amount of adhesion can be obtained. There is no risk.

(4) Treatment for forming irregularities on the surface of roughened particles Examples of the treatment for forming irregularities on the surface of roughened particles include etching with chemical agents such as inorganic acids and organic acids, and etching with anodic oxidation. A concave portion is formed by removing a part of the surface of the roughened particles by etching, and the portion where the amount of removal is small becomes a convex portion (convex portion 1a of the roughened particles 1 in FIG. 1), so that the roughened particles are roughened. Unevenness is formed on the surface of the particles.

Etching with a chemical agent includes, for example, a treatment of immersing a copper foil in an inorganic acid such as hydrochloric acid, sulfuric acid, or phosphoric acid. By immersing the copper foil in an aqueous solution of an inorganic acid having a predetermined concentration for several seconds to several tens of seconds, a plurality of fine irregularities are formed on the surface of the roughened particles.
For example, when hydrochloric acid is used as the inorganic acid, fine irregularities can be formed on the surface of the roughened particles by immersing the copper foil in hydrochloric acid having a concentration of 5 to 20% by volume for 2 seconds or longer. The surface area of the roughened surface can be sufficiently increased.

Etching other than the dipping treatment in the inorganic acid includes, for example, a dipping treatment in an organic acid such as acetic acid and formic acid, a dipping treatment in a solution containing iron chloride and copper chloride, and a dipping treatment in a commercially available microetching agent. , Electrolytic etching treatment by anodic oxidation can be mentioned. These etchings may be performed individually by 1 type or in combination of a plurality of types.

FIG. 4 shows an example of the roughened surface of the roughened copper foil in which irregularities are formed on the surface of the roughened particles by such etching. It can be seen that the roughened particles shown in FIG. 4 have a large number of irregularities formed on the surface thereof as compared with the roughened particles shown in FIG. Then, it can be seen that the surface area of the roughened particles is increased due to these irregularities.

(5) Surface Treatment The roughened surface of the roughened copper foil produced as described above may be surface-treated, if desired. Examples of the surface treatment include a treatment of forming the following surface treatment layer on the roughened surface. That is, when manufacturing a copper-clad laminated plate, the copper in the roughened copper foil diffuses on the resin substrate laminated on the roughened surface of the roughened copper foil, causing copper damage and roughening. The base layer for suppressing the deterioration of the adhesion between the treated copper foil and the resin substrate, the heat-resistant treated layer for improving the heat resistance of the roughened treated copper foil, and the rust resistance of the roughened treated copper foil are improved. Examples thereof include a treatment for forming a surface treatment layer such as a rust-preventive treatment layer for making the copper foil roughened and a chemical adhesion agent layer for improving the adhesion between the roughened copper foil and the resin substrate. These surface-treated layers may be laminated alone on the roughened surface of the roughened copper foil, or may be laminated in combination of two or more.

Since the thickness of the intermediate layer including the heat-resistant treatment layer and the rust-preventive treatment layer and the chemical adhesion agent layer is very small, the roughened particles formed on the roughened surface of the roughened copper foil It does not affect the particle shape. The particle shape of the roughened particles is substantially determined by the particle shape of the roughened particles at the stage formed by the roughening treatment.

Further, as the base layer, the heat-resistant treatment layer, and the rust-preventive treatment layer, all of these three layers may be formed on the roughening-treated surface of the roughened-treated copper foil, and if desired, any one of these three layers may be formed. Only one layer or two layers may be formed, but when all three layers are formed, it is preferable to stack the base layer, the heat resistant treatment layer, and the rust preventive treatment layer in this order from the roughening treatment surface side. ..

Further, when the chemical adhesion agent layer is laminated on the roughened copper foil, at least one of a base layer, a heat resistant treatment layer, and a rust prevention treatment layer is interposed between the roughened copper foil and the chemical adhesion agent layer. It may or may not be intervened (that is, the chemical adhesion layer may be formed directly on the roughened surface of the roughened copper foil).

In the base layer, the copper in the roughened copper foil diffuses to the resin substrate laminated on the roughened surface of the roughened copper foil when the copper-clad laminated plate is manufactured, causing copper damage. When there is a risk that the adhesion between the roughened copper foil and the resin substrate may decrease, it is preferable to form the roughened copper foil between the roughened copper foil and the chemical adhesion layer. The underlayer preferably contains nickel (Ni), and is preferably formed by plating with at least one selected from, for example, nickel, nickel-phosphorus (P), and nickel-zinc (Zn). ..

The heat-resistant layer is preferably formed when it is necessary to improve the heat resistance of the roughened copper foil. The heat-resistant treatment layer preferably contains zinc, and is preferably formed by plating with at least one selected from, for example, zinc and an alloy containing zinc. Examples of zinc-containing alloys include zinc-tin (Sn) alloys, zinc-nickel alloys, zinc-cobalt (Co) alloys, zinc-copper (Cu) alloys, zinc-chromium (Cr) alloys, and zinc-vanadium. (V) Alloy can be mentioned.

The rust-preventive layer is preferably formed when it is necessary to improve the rust-preventive property of the roughened copper foil. The rust-preventive treatment layer preferably contains chromium, and examples thereof include a chromium layer formed by chrome plating and a chromate layer formed by chromate treatment.

The chemical adhesive layer is preferably formed when it is necessary to improve the adhesion between the roughened copper foil and the resin substrate. The chemical adhesion agent layer can be formed by a chemical adhesion agent treatment using a chemical adhesion agent such as a silane coupling agent. For example, it can be formed by applying a chemical adhesion agent solution directly or via an intermediate layer on the roughened surface of the roughened copper foil, and then air-drying (naturally drying) or heat-drying.

When a solvent such as water in the applied chemical adhesion agent solution evaporates, a chemical adhesion agent layer is formed, and the effect of improving the adhesion between the roughened copper foil and the resin substrate is achieved. Heating and drying at a temperature of 50 to 180 ° C. is suitable because the reaction between the chemical adhesion agent and the roughened copper foil is promoted.

Examples of the silane coupling agent include epoxy-based silane coupling agents, amino-based silane coupling agents, vinyl-based silane coupling agents, methacrylic-based silane coupling agents, acrylic-based silane coupling agents, azole-based silane coupling agents, and styryl. It is preferable to use one or more of a silane coupling agent, a ureido-based silane coupling agent, a mercapto-based silane coupling agent, a sulfide-based silane coupling agent, and an isocyanate-based silane coupling agent.

〔Example〕
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
(A-1) Electrolytic Copper Foil Electrolyzed copper foil was produced as a raw material copper foil for producing the roughened copper foil of Examples 1 to 17 and Comparative Examples 1 to 10. Using the same device as in FIG. 2, copper plating was performed by the same operation as described above to deposit copper on the surface of the rotating electrode. Then, the precipitated copper was peeled off from the surface of the rotating electrode and continuously wound to produce an electrolytic copper foil (double-sided glossy foil) having a thickness of 18 μm.

As the rotating electrode as the cathode, a titanium rotating drum whose surface (cylindrical surface) roughness was adjusted by buffing # 1000 to # 2000 was used. A dimensional stability anode DSA (registered trademark) was used as the insoluble electrode as the anode.
As the electrolytic solution, copper having a concentration of 75 g / L, sulfuric acid having a concentration of 65 g / L, chlorine having a concentration of 20 mg / L, sodium 3-mercapto-1-propanesulfonate having a concentration of 2 mg / L, and hydroxyethyl cellulose having a concentration of 10 mg / L. And a copper sulfate aqueous solution containing a low molecular weight glue (molecular weight 3000) having a concentration of 50 mg / L was used. The temperature of the electrolytic solution at the time of copper plating is 50 ° C., and the current density is 45 A / dm ² .

(A-2) Rolled Copper Foil Rolled copper foil C1020R-H manufactured by Takeuchi Metal Foil Powder Industry Co., Ltd. was used as a raw material copper foil for producing the roughened copper foil of Example 18 and Comparative Example 11. The thickness of this rolled copper foil is 20 μm.

(B) Roughening Treatment Next, one surface of the electrolytic precipitation end surface (matte surface) and the rolled copper foil of the electrolytic copper foil manufactured as described above is subjected to roughening treatment to roughen the surface. And said. This roughening treatment was carried out by performing a two-step electroplating treatment in a roll-to-roll method.

The roughening plating treatment, which is the first stage electroplating treatment, is an electroplating treatment using a roughening plating basic bath at 15 ° C. having the following composition, and has a current density and treatment time shown in Table 1 and is 15 m. By performing the electroplating treatment at a treatment rate of / min, roughened particles having different roughening heights and shapes were formed on the electrolytic precipitation end surface of the electrolytic copper foil.
Concentration of copper sulfate pentahydrate in rough plating basic bath: 10 g / L in terms of copper (atom)
Concentration of sulfuric acid in rough plating basic bath: 150 g / L
Concentration of ammonium molybdate in the roughened plating basic bath: 600 mg / L in terms of molybdenum (atom)

The second-stage electroplating process, the fixed plating process, is an electroplating process using a fixed plating basic bath having the following composition, with the current density and processing time shown in Table 1, and a processing speed of 15 m / min. By performing the electroplating treatment in the above, smooth covering plating was applied to the surface of the electrolytic precipitation end surface which had been subjected to the roughening plating treatment, and the roughened particles were immobilized.
Concentration of copper sulfate pentahydrate in fixed plating basic bath: 55 g / L in terms of copper (atom)
Concentration of sulfuric acid in the fixed plating basic bath: 120 g / L
In Comparative Example 9, the roughening treatment was not performed.

(C) Pretreatment Pretreatment for promoting the formation of unevenness on the surface of the electrolytic copper foil that has been roughened before the treatment for forming unevenness on the surface of the roughened particles. Was done. For Examples 1 to 14 and 18 and Comparative Examples 7 to 10, electrozinc plating under the following conditions was performed as a pretreatment.
Zinc concentration in the plating bath: 2.5 g / L
Concentration of sodium hydroxide in the plating bath: 35 g / L
Plating bath temperature: 20 ° C
Current density: 0.5A / dm ²
Processing time: 1 second

Further, for Examples 15 to 17, natural oxidation under the following conditions was performed as a pretreatment.
Temperature: 23 ° C
Humidity: 50% RH
Treatment time: 12 hours In Comparative Examples 1 to 7 and 11, no pretreatment was performed.

(D) Treatment for forming irregularities on the surface of roughened particles For Examples 1 to 18 and Comparative Examples 8 to 10 which were subjected to the pretreatment, the concentration was 10% by volume (only Example 3 was 11% by volume) and the temperature was 30 ° C. By immersing the particles in hydrochloric acid, the surface of the roughened particles was treated to form irregularities. The immersion treatment time is as shown in Table 1. By such a treatment, roughened copper foils having different surface areas on the roughened surface were produced.

Although the details will be described later, in Comparative Examples 1 to 6 and 11, the treatment for forming irregularities on the surface of the roughened particles was not performed. Further, in Comparative Example 7, electrolytic plating was performed in a copper sulfate plating bath containing 9-phenylacridine (C ₁₉ H ₁₃ N) to form protrusions on the surface of the roughened particles, thereby coarsening the particles. Unevenness was formed on the surface of the chemical particles.

(E) Formation of Underlayer and Intermediate Layer Subsequently, the underlayer, the heat-resistant treatment layer, and the rust-preventive treatment layer were laminated in this order on the roughening-treated surface having irregularities formed on the surface of the roughened particles. The underlayer was formed by nickel plating under the following conditions, the heat resistant layer was formed by zinc plating under the following conditions, and the rust preventive layer was formed by chrome plating under the following conditions. ..

<Conditions for nickel plating>
Nickel concentration in the plating bath: 45 g / L
Concentration of boric acid (H ₃ BO ₃ ) in the plating bath: 4 g / L
Plating bath temperature: 20 ° C
Plating bath pH: 3.5
Current density: 0.2A / dm ²
Processing time: 8 seconds

<Conditions for galvanization>
Zinc concentration in the plating bath: 2.5 g / L
Concentration of sodium hydroxide in the plating bath: 35 g / L
Plating bath temperature: 20 ° C
Current density: 0.5A / dm ²
Processing time: 4 seconds

<Chromium plating conditions>
Chromium concentration in the plating bath: 6 g / L
Plating bath temperature: 30 ° C
Plating bath pH: 2.3
Current density: 5A / dm ²
Processing time: 3 seconds

(F) Formation of chemical adhesion agent layer Finally, the chemical adhesion agent layer was laminated on the rust preventive treatment layer. More specifically, an aqueous solution of 3-aminopropyltrimethoxysilane (C ₆ H ₁₇ NO ₃ Si) having a concentration of 0.2% by mass is applied to the rust preventive layer and dried at 100 ° C. to form a silane coupling agent layer. bottom.

(G) Explanation of Comparative Examples Here, Comparative Examples 1 to 11 will be collectively described.
Comparative Examples 1 to 3 are examples in which the surface of the roughened particles is not treated to form irregularities, and the surface of the roughened particles is not formed with irregularities. Comparative Examples 4 to 6 are for the roughened particles after forming the roughened particles according to the methods disclosed in Examples of Japanese Patent No. 6332739, Japanese Patent No. 6462961, or International Publication No. 2020/031721, respectively. This is an example in which the surface is not treated to form irregularities and the surface of the roughened particles is not formed with irregularities.

Comparative Example 7 is an example in which unevenness is formed on the surface of the roughened particles by performing electrolytic plating to form protrusions on the surface of the roughened particles. Comparative Example 8 is an example in which the roughened height of the roughened surface is too large. Comparative Example 9 is an example in which the roughening treatment is not performed and the roughened particles are not formed on the electrolytic precipitation end surface of the copper foil. Comparative Example 10 is an example in which the surface area of the roughened surface is too large. Comparative Example 11 is an example in which, after the rolled copper foil is roughened, the surface of the roughened particles is not treated to form irregularities, and the surface of the roughened particles is not irregularized.

Here, the method for producing the roughened copper foil of Comparative Example 7 will be described in detail. In Comparative Example 7, roughened particles were formed on the electrolytic precipitation end surface of the electrolytic copper foil by two-step electroplating. Then, the third step of electrolytic plating was further performed to form irregularities on the surface of the roughened particles. Subsequently, a base layer, a heat-resistant treatment layer, a rust-preventive treatment layer, and a chemical adhesion agent layer were laminated in the same manner as in the examples to obtain a roughened copper foil.

The method for producing the roughened copper foil of Comparative Example 7 is based on the method disclosed in Examples of International Publication No. 2019/188712, and is substantially spherical on the surface of the roughened particles in the third stage electroplating. By forming the protrusions of the above, irregularities are formed on the surface of the roughened particles.
In the three-step electrolytic plating, a copper sulfate solution having the following copper concentration, sulfuric acid concentration, chlorine concentration, and 9-phenylacridin (9PA) concentration was used as the plating bath. The conditions for the three stages of electrolytic plating are as follows.

<Conditions for first-stage electroplating>
Concentration of copper sulfate pentahydrate in plating bath: 8 g / L in terms of copper (atom)
Concentration of sulfuric acid in the plating bath: 100 g / L
Chlorine concentration in the plating bath: 50ppm
Concentration of 9PA in plating bath: 60ppm
Plating bath temperature: 30 ° C
Processing speed: 15 m / min Processing direction Polar flow velocity: 15 m / min Current density: 9.2 A / dm ²
Processing time: 4.4 seconds

<Conditions for second stage electroplating>
Concentration of copper sulfate pentahydrate in plating bath: 69 g / L in terms of copper (atom)
Concentration of sulfuric acid in the plating bath: 240 g / L
Chlorine concentration in the plating bath: 0 ppm
Concentration of 9PA in plating bath: 0 ppm
Plating bath temperature: 52 ° C
Processing speed: 15 m / min Processing direction Polar flow velocity: 15 m / min Current density: 2.1 A / dm ²
Processing time: 4.4 seconds

<Conditions for electroplating in the third stage>
Concentration of copper sulfate pentahydrate in plating bath: 13 g / L in terms of copper (atom)
Concentration of sulfuric acid in the plating bath: 75 g / L
Chlorine concentration in the plating bath: 35ppm
Concentration of 9PA in plating bath: 139ppm
Plating bath temperature: 28 ° C
Processing speed: 15 m / min Processing direction Polar flow velocity: 15 m / min Current density: 33.6 A / dm ²
Processing time: 0.6 seconds

(H) Evaluation Various evaluations were performed on the copper foils of Examples 1 to 18 and Comparative Examples 1 to 11 manufactured as described above.
[Expanded area ratio Sdr and arithmetic mean roughness Sa of the interface of the roughened surface]
The developed area ratio Sdr and the arithmetic mean roughness Sa of the interface of the roughened surface are determined by using a three-dimensional white light interference type microscope, a scanning electron microscope, an electron beam three-dimensional roughness analyzer, etc. according to the method specified in ISO25178. Can be measured using. For the copper foils of Examples 1 to 18 and Comparative Examples 1 to 11, the surface shape of the roughened surface was measured and shape-analyzed using a three-dimensional white light interference type microscope WykoContourGT-K manufactured by Bruker. The developed area ratio Sdr and the arithmetic mean roughness Sa of the interface of the roughened surface were obtained.

The surface shape was measured at any 5 points on each copper foil, and shape analysis was performed at each of the 5 points to obtain the developed area ratio Sdr and the arithmetic mean roughness Sa of the interface at each of the 5 points. Then, the average value of the results of the obtained five places was taken as the developed area ratio Sdr at the interface of each copper foil and the arithmetic mean roughness Sa.

The shape analysis was performed by a VSI measurement method (vertical scanning interferometry) using a high resolution CCD camera (resolution 1280 × 960 pixels). The conditions were that the light source was white light, the measurement magnification was 50 times, the measurement range was 96.1 μm × 72.1 μm, the threshold was 3%, and the Terms Removal (Cylinder and Tilt) and Data Restore (Metado: legacy, iterations 5). After the filtering process, the Foiler Filter process was performed.

For the Fourier Filter treatment, High Freq Pass was used as the Fourier filtering, Gaussian was used as the Fourier Filter Window, and the Low Frequency was set to 62.5 mm ^-1 by the Frequency Cutoff.

The developed area ratio Sdr of the interface was calculated by using S-parameters-hybrid analysis with Remove Tilt as True. Arithmetic mean roughness Sa was calculated with Remove Tilt as True by S-parameters-height analysis. The results are shown in Table 2.

[10-point average roughness Rz of the roughened surface]
For the roughened surfaces of the copper foils of Examples 1 to 18 and Comparative Examples 1 to 11, the ten-point average roughness Rzjis (μm) was measured according to the provisions of JIS B 0601: 2001. As a measuring device, a contact type surface roughness measuring machine surfcoder SE1700 manufactured by Kosaka Laboratory Co., Ltd. was used. In addition, the measurement was performed along a direction orthogonal to the length direction of the copper foil. The results are shown in Table 2. The above-mentioned "length direction" means MD (Machine Direction) of the electrolytic copper foil. For example, when the electrolytic copper foil is manufactured, a rotating electrode is used to form a copper foil on the surface of the rotating electrode by plating. If so, it means the rotation direction of the rotating electrode.

[Adhesion strength]
A normal peel test was performed based on the method specified in JIS C6481: 1996. A resin substrate was joined to the roughened surface of the copper foil to form a copper-clad laminate. As the resin substrate, two low-dielectric polyphenylene ether-based resin films (multilayer substrate material MEGTRON7 manufactured by Panasonic Corporation, thickness 60 μm) were laminated and bonded together. For the copper foils of Examples 1 to 6 and Comparative Examples 1 to 3, copper-clad laminates were produced without surface polishing or micro-etching before joining the resin substrates.

A masking tape was attached to the copper-clad laminate to perform copper chloride etching, and then the masking tape was removed to prepare a printed wiring board having a circuit wiring having a width of 10 mm.
Next, in a room temperature environment, using a Tencilon tester manufactured by Toyo Seiki Seisakusho Co., Ltd., pull the circuit wiring part (copper foil part) of the printed wiring board in the 90 degree direction at a speed of 50 mm / min from the resin substrate. After peeling, the normal peel strength was measured and used as the adhesion strength. The results are shown in Table 2. In Table 2, when the adhesion strength is 0.7 N / mm or more, it is “A”, when it is 0.55 N / mm or more and less than 0.7 N / mm, it is “B”, and it is less than 0.55 N / mm. The case is indicated by "C".

[Transmission loss]
A strip line using the copper foils of Examples 1 to 18 and Comparative Examples 1 to 11 and a low-dielectric polyphenylene ether-based resin film (multilayer substrate material MEGTRON7 manufactured by Panasonic Corporation, thickness 60 μm) which is a resin substrate. A printed wiring board was prepared and the transmission characteristics were evaluated. The circuit width of the strip line formed on the printed wiring board was 140 μm, and the circuit length was 760 mm.

A high-frequency signal was transmitted to the circuit formed on the copper foil of the printed wiring board using a network analyzer N5291A manufactured by Keysight Technologies, and the transmission loss was measured. The characteristic impedance was set to 50Ω. The measured value of the transmission loss means that the smaller the absolute value, the smaller the transmission loss, that is, the higher frequency signal can be transmitted satisfactorily. The results are shown in Table 2. In Table 2, when the absolute value of the transmission loss at 30 GHz is less than 28 dB / 760 mm, it is “A”, when it is 28 dB / 760 mm or more and less than 31 dB / 760 mm, it is “B”, and when it is 31 dB / 760 mm or more, it is “A”. It is shown as "C".

[Migration resistance test]
The copper foils of Examples 1 to 18 and Comparative Examples 1 to 11 and a low-dielectric polyphenylene ether-based resin film (multilayer substrate material MEGTRON7 manufactured by Panasonic Corporation, thickness 60 μm), which is a resin substrate, are bonded and pressed. A sample was prepared. Next, a comb-shaped circuit conforming to the IPC-B-25A standard was formed on this press sample to produce a printed wiring board. The line width of this comb-shaped circuit is 0.318 mm, the space width is 0.318 mm, and the circuit length is 22 mm.

The printed wiring board thus produced was subjected to a migration resistance test based on the method specified in IPC-650-TM2.5.3 using the migration measuring machine MIG-8600B manufactured by IMV, and the resistance between wiring patterns was performed. The migration property was evaluated. That is, after measuring the initial resistance value of the printed wiring board in a room temperature environment (23 ° C., 50% RH), a DC voltage of 100 V was applied for 168 hours (7 days) in a constant temperature and high humidity bath at 50 ° C. and 90% RH. Applied.

Then, the printed wiring board was taken out from the constant temperature and high humidity bath, and the resistance value was measured within 1 hour. The results are shown in Table 2. In Table 2, if the resistance value measured after taking out from the constant temperature and high humidity bath is less than 50% of the initial resistance value, it is "A", and if it is 50% or more and less than 60%, it is "B", 60%. If it is the above, it is indicated as "C".

As can be seen from Table 2, the roughened copper foils of Examples 1 to 18 have a developed area ratio Sdr of 1000% or more and 5000% or less at the interface of the roughened surface, and the arithmetic mean of the roughened surface. Since the roughness Sa is 0.04 μm or more and 0.6 μm or less, the printed wiring board produced by using the roughened copper foil has excellent adhesion between the resin and the roughened copper foil, and the transmission loss is small. Moreover, short circuits due to migration are unlikely to occur.

On the other hand, in the copper foils of Comparative Examples 1 to 11, at least one of the developed area ratio Sdr and the arithmetic mean roughness Sa at the interface of the roughened surface does not satisfy the above requirements. Therefore, the printed wiring board produced using the copper foil has at least one of the adhesion between the resin and the copper foil, the transmission loss, and the susceptibility to short circuit due to migration, and the roughened copper foil of Examples 1 to 18 It was inferior to the case of.

In Comparative Example 7, since the surface of the roughened particles is uneven by forming protrusions on the surface of the roughened particles by electroplating, the particles are concentrated in the vicinity of the tip of the roughened particles. It is believed that protrusions are formed. Therefore, it is considered that roughened particles whose height has increased due to electrolytic plating are partially generated, and the transmission loss has increased.

Since the roughened copper foils of Examples 1 to 18 form irregularities on the surface of the roughened particles by etching, the roughened height does not increase, and the entire surface of the roughened particles is covered. The unevenness is uniformly formed. Therefore, it is considered that the adhesion between the resin and the copper foil can be improved while the transmission loss can be kept low, and the short circuit due to migration can be suppressed.

1 ... Roughened particles 1a ... Convex part 3 ... Surface of raw copper foil 11 ... Rotating electrode 12 ... Insoluble electrode 13 ... Electrolyte solution 14 ... Electrolytic copper foil

Claims (8)

A roughened copper foil having a roughened surface on which a plurality of roughened particles are formed on at least one surface. The surface of the roughened particles has irregularities, and is a three-dimensional white light interference type. The developed area ratio Sdr of the interface of the roughened surface measured using a microscope is 1000% or more and 5000% or less, and the arithmetic mean roughness Sa of the roughened surface is 0.04 μm or more and 0.6 μm or less. The roughened copper foil that is. The roughened copper foil according to claim 1, wherein the developed area ratio Sdr of the interface of the roughened surface is 2000% or more and 5000% or less. The roughened copper foil according to claim 1, wherein the developed area ratio Sdr of the interface of the roughened surface is 3000% or more and 5000% or less. The roughened copper foil according to any one of claims 1 to 3, wherein the arithmetic mean roughness Sa of the roughened surface is 0.04 μm or more and 0.35 μm or less. The roughening according to any one of claims 1 to 4, wherein the ten-point average roughness Rz of the roughened surface measured by using a contact type surface roughness measuring machine is 0.6 μm or more and 1.4 μm or less. Treated copper foil. The roughened copper foil according to any one of claims 1 to 5, wherein the rust-preventive treatment layer is laminated on the roughening-treated surface, and the chemical adhesion agent layer is further laminated on the rust-preventive treatment layer. A copper-clad laminate comprising the roughened copper foil according to any one of claims 1 to 6. A printed wiring board provided with the roughened copper foil according to any one of claims 1 to 6.

Images