JP2008127618A - Method for treating surface of copper foil through feeding alternating current - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such a surface treatment method as to impart sufficient adhesiveness with an industrial plastic film or thermosetting resin to a copper foil, while generally retaining a specific thickness of the thin copper foil, by efficiently forming a rough shape having fine unevenness along crystal grain boundaries on at least one side of the thin copper foil. <P>SOLUTION: The surface treatment method for the copper foil includes finely roughening the surface of the copper foil by electrolyzing at least one side of the copper foil having a crystal structure constituted by fine crystal grains with the use of an alternating current, while using a bath containing only sulfuric acid or a bath containing sulfuric acid and a compound of a heavy metal dissolved therein, as an electrolytic solution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface treatment method for a copper foil mainly used for wiring such as a printed wiring board, and particularly suitable for a flexible printed wiring board.

  In recent years, a thin copper foil of 18 μm or less is frequently used for a printed wiring board, and in particular, an electrolytic copper foil having a thickness of 12 μm is also commonly used for the outermost layer of a rigid multilayer board. In particular, with the miniaturization of communication devices and terminal devices, the use of flexible printed wiring has increased dramatically. In particular, since a folding design has been adopted in cellular phone devices with the spread of cellular phones, a wiring circuit called a hinge of the folded portion has become a product that cannot be realized without employing flexible printed wiring.

  Copper foil used for flexible printed wiring, when used in the hinge part of the mobile phone device, is generally required to have a characteristic that is excellent in bending resistance. A rolled copper foil having excellent properties and elongation properties has been employed. However, in recent years, significant technical improvements have also been made in electrolytic copper foil, and at the stage of the foil production process, for example, by refining the crystal structure, the electrodeposited surface side can be smoothed as much as rolled foil, and further glossy. Electrolytic copper that has the same or better properties than the rolled copper foil, but also has the same or better bending and elongation properties. Foil has been on the market.

  In recent years, the demand for thin copper foil has been increasing in the market for copper foil in the field of rigid boards and flexible boards. Copper foil is an indispensable material for increasing the density. Although the supply of thin copper foil is possible with either rolled copper foil or electrolytic copper foil, the rolled copper foil turns into a thin copper foil through many rolling processes, whereas in the case of electrolytic copper foil, Since it has the merit which can set and manufacture the target thickness in the process, the electrolytic copper foil has prevailed in terms of manufacturing cost. Recently, not only a wide variety of thickness as a flexible material, but also roughening of the interface part of the copper foil, which affects the adhesion when coating industrial plastic films and thermosetting resins that are laminated or bonded together. Electrolytic copper foil has been widely used at home and abroad because of its wide variety of shapes.

  For example, when producing a copper-clad flexible film for flexible printed wiring, a laminating method in which an industrial plastic film and a copper foil are laminated while being heated and pressed, or a thermosetting resin is applied to one surface of the copper foil For example, a casting method in which the resin is cured while heating is common. In both methods, the adhesiveness between the copper foil and the film and between the copper foil and the resin is important in forming a flexible printed wiring in order to produce a flexible film. As one of the techniques for improving the adhesion, a method of roughening the surface of the copper foil is used.

  One of the conventional surface roughening treatment methods is a method of electrodepositing fine copper particles on the surface of the copper foil using a metallic copper burn plating method and smooth plating of the metallic copper on the copper foil so as not to drop off. It has been adopted. The copper foil obtained by this processing method is reliably improved in adhesion with a film or resin due to the anchoring effect of the plated shape of the metal copper particles. However, on the other hand, since this treatment method deposits copper particles on the cathode electrolytic treatment, the thickness of the copper foil increases and the unit weight also increases. This increase in thickness and unit weight not only reduces the etching rate during etching in the thin wire circuit pattern creation process, but also rarely occurs in some cases when adopting thin copper foil for the purpose of forming high-density circuits. There is also a concern that the residue of copper particles may cause problems such as migration and short circuit.

In addition, the copper foil roughening treatment by the cathodic electrolysis treatment includes at least two electrolysis processes: a burn plating process for forming copper particles, and a smooth capsule plating process for preventing the copper particles attached in the burn plating process from falling off. A processing step is required. In each processing step, copper foil is used as a cathode, and power is supplied to the copper foil via a power supply contact roll. However, as the copper foil becomes thinner, heat generation of the copper foil becomes more noticeable and the appearance increases. Inconveniences such as generation of wrinkles may occur, which is one of the major causes of reducing the productivity in the roughening process of thin copper foil.
Therefore, an epoch-making roughening technology including handling of thin copper foil has been demanded.

In addition to the above-described cathodic electrolytic treatment methods, as conventional techniques for roughening the copper foil surface, electrolytic treatment methods such as alternating current electrolytic treatment and pulse electrolytic treatment, oxidation-reduction treatment with chemicals, and chemical etching treatment are known. ing. However, the electrolytic copper foils to be surface-treated have a columnar crystal structure in which the crystal structure grows in a columnar shape, although the copper foil surface shape on the liquid surface side at the time of manufacture varies depending on the foil production conditions. All of them already have a concavo-convex shape, and development has been promoted for the purpose of improving the anchoring effect by more efficiently roughening the surface.
On the other hand, since the surface of the rolled copper foil is in a smooth mirror surface, the process is complicated to form an uneven shape on the surface by plating, and the resulting roughened surface is brittle. In general, a roughening process by plating is not often used, and a technique using an oxidation-reduction process or a chemical etching process has been mainly employed. However, there is a concern that a roughened shape obtained by this method cannot provide sufficient adhesion. In addition, the method of obtaining a rough surface by chemical etching using a chemical agent, for example, in the case of roughening only one surface of a thin copper foil, the processing equipment becomes complicated, and the concentration management of the chemical agent is costly. It is not widely adopted now.

  With the recent increase in demand for flexible printed wiring, the quality and technical requirements for the wiring circuit are also increasing, and the design is made such that the distance between the wiring width and the circuit is 30 μm or less. In order to form a fine printed circuit of flexible printed wiring, the copper foil used as a material is a thin copper foil (12 μm to 9 μm thick) with excellent bending resistance, and the circuit is sharp and cut linearly. For this, it is essential that the etching rate of the copper foil is large. In order to satisfy these requirements, the crystal grain boundary on the surface of the copper foil is required to be fine, in other words, the crystal structure is required to be fine. In addition, it is an essential requirement to have a rough surface with a certain degree of unevenness in order to generate an appropriate adhesion strength, and a copper foil material that satisfies all these requirements has been demanded.

JP-A-8-158100 JP 10-130897 A

  The use of rolled copper foil is common for copper foil for flexible printed wiring. This was due to the good elongation characteristics and excellent flex resistance of the rolled copper foil. One of the reasons why electrolytic copper foil has not been used for flexible printed circuit boards in the past is that conventional electrolytic copper foil has a columnar crystal in the quality test that repeats practical bending. In the electrolytic copper foil having the crystal structure, it has been confirmed that it breaks along the crystal grain boundary regardless of its thickness, and the concern that it breaks under actual use conditions cannot be wiped out. there were.

  However, in recent years, it has become possible to produce an electrolytic copper foil having a fine crystal structure by improving the foil production method even for an electrolytic copper foil, and the grain boundary fracture due to bending has been remarkably improved. Yes. For example, the rolled copper foil undergoes plastic deformation after aging under a heating condition of about 130 ° C. to 160 ° C., and changes to a crystal structure having a somewhat larger grain boundary. Under this condition, not only does it have a property of maintaining a fine crystal structure without significantly changing even under thermal conditions exceeding 300 ° C., but it is comparable to a rolled copper foil in terms of elongation properties and bending resistance. Those with characteristics are on the market.

In recent years, a copper foil for flexible printed wiring has been used, and technical requirements have been increased while cost reduction has been demanded. In particular, there is a demand for the appearance of an electrolytic copper foil whose manufacturing cost is lower than that of a rolled copper foil, including COF applications that require a thin copper foil with a thickness of 9 μm.
The present invention combines an electrolytic copper foil having a fine crystal structure with an electrolytic treatment by indirect power feeding using alternating current, thereby maintaining at least one surface of the grain boundary while substantially maintaining the inherent thickness of the thin copper foil. It provides a surface treatment method that efficiently forms a rough shape having fine irregularities along the surface, and that the surface has a sufficient shape to obtain adhesion to an industrial plastic film or a thermosetting resin. is there.

  The surface treatment method for copper foil by AC power feeding of the present invention uses a sulfuric acid single bath or an electrolytic bath in which a heavy metal compound is added to sulfuric acid, and performs electrolytic treatment by alternating current on at least one surface of the copper foil made of granular crystals. The surface of the copper foil is roughened.

Preferably, the copper foil has a structure composed of fine granular crystals, the surface roughness of one surface thereof is at least 2.5 μm or less in terms of Rz value, and the thickness of the copper foil is 160 g / unit in terms of unit weight. m ² or less.

  The heavy metal added to the sulfuric acid is selected from at least one of the group consisting of nickel, cobalt, molybdenum, tungsten, antimony, vanadium, and silver.

Preferably, the copper foil is a copper foil having a thickness of 45 g / m ² or less in terms of unit weight, which can be easily peeled off, and the thickness of the support metal foil having a thickness of 130 g / m ² or more in terms of unit weight. It is a copper foil with a carrier formed by plating on at least one surface.

According to the surface treatment method for copper foil by AC power feeding of the present invention, the surface of the thin copper foil made of fine granular crystals can be subjected to AC electrolytic roughening treatment, whereby the surface roughened state can be uniformly and efficiently treated and produced. The quality and quality can be improved.
In addition, it is possible to form a throwing effect that cannot be obtained on a glossy surface in a mirror surface state with the characteristics of a conventional copper foil surface, as a fine uneven surface roughened shape, and an industrial plastic film laminated with the foil or the Adhesion with the thermosetting resin cast directly on the surface can be improved, and the thickness of the film or casting resin to be bonded to the copper foil can be reduced.
Furthermore, by adding a single or a plurality of heavy metal elements that chemically increase the tight bonding strength to the electrolytic bath, surface roughening and simultaneous heavy metal plating can be achieved, so that the industrial plastic film to be bonded to the foil In addition, it is possible to further improve the adhesion to the thermosetting resin cast directly on the surface, and to reduce the thickness of the film and casting resin to be bonded to the copper foil.
The surface treatment method for copper foil by AC power feeding according to the present invention can simplify the surface treatment process, is inexpensive, and can provide an electrolytic copper foil that substantially maintains the inherent thickness of a thin copper foil.

Hereinafter, an embodiment of the present invention will be described.
The present invention is a method of subjecting at least one surface of a copper foil made of granular crystals to direct or indirect electrolytic treatment by alternating current, for example, commercial alternating current, and roughening the surface of the copper foil, comprising an electrolytic solution A bath containing a heavy metal or a heavy metal compound that can be dissolved in a sulfuric acid single bath or a sulfuric acid bath is used.

The surface-treated copper foil may be either a rolled copper foil or an electrolytic copper foil, but in order to sufficiently bring out the effect of the roughening treatment with a thin copper foil, the copper foil is a crystal composed of fine granular crystals. It has a structure, and the surface roughness is such that the Rz value conforming to the measuring method specified in JIS-C-6515 is 2.5 μm or less on at least one surface, and the thickness of the copper foil is nominally 18 μm or less. A copper foil of 160 g / m ² or less in terms of unit weight is used.

As the electrolytic bath, a sulfuric acid single bath or a bath to which a heavy metal or a heavy metal compound that can be dissolved in the sulfuric acid bath is added is used.
The heavy metal added to the sulfuric acid single bath and the heavy metal element as the heavy metal compound can be selected from at least one of nickel, cobalt, molybdenum, tungsten, antimony, vanadium, and silver dissolved in sulfuric acid. The concentration of the metal element to be added is preferably 5.0 g / l or less. In addition, it is preferable that the metal amount which adheres to the copper foil surface-treated with surface roughening shall be 0.1 mg / dm < ² > or less as each single metal element. This is because if it adheres more than this, not only the etching property is deteriorated, but there is a concern that an unexpected defect may occur as an etching residue.

  As an auxiliary additive for stabilizing the electrolytic bath, boric acid, ammonium sulfate, oxalic acid, and hypophosphorous acid may be appropriately added. When a bath to which these additives are added is used, there is an effect of simplifying the surface treatment process by adding not only a roughening treatment but also a surface treatment effect. (The ability to reduce the number of manufacturing and processing steps in the electroplating manufacturing industry is very preferable as a consideration of the global environment in a broad sense.)

It is preferable to subject the treated surface to a rust prevention treatment after the surface treatment by alternating current.
As the antirust treatment, for example, an organic antirust agent typified by a benzotriazole compound is applied to the surface of the surface-treated copper foil. The thickness of the anticorrosive film by the antirust treatment is preferably in the range of 500 to 1000 nm as the theoretical film thickness obtained by measuring the electric double layer capacity and converting the measured value.
Or when performing a chromate rust prevention treatment using chromium compound is dissolved bath, a quantity to be analyzed as metallic chromium is preferably 0.050 mg / dm ² ranges from 0.015.

Furthermore, for the purpose of improving the adhesiveness mainly with an industrial plastic film bonded to the copper foil or a thermosetting resin directly cast on the copper foil surface, at least one surface of the copper foil has an amino group. It is preferable to perform surface treatment using one kind of silane coupling agent selected from epoxy, vinyl, and chloroxy. In this case, the coupling agent attached to the surface is preferably attached in the range of 0.001 to 0.015 mg / dm ² as the amount of silicon.

The present invention is a method of subjecting at least one surface of a copper foil to an electrolytic treatment by alternating current to roughen the surface of the copper foil, wherein a sulfuric acid single bath or a bath obtained by adding a heavy metal compound to sulfuric acid is used as an electrolytic solution. .
According to the AC electrolytic treatment, the surface of the copper foil instantaneously repeats the anode and cathode forms. When the copper foil surface is the anode, the copper foil is dissolved, while at the cathode, the copper dissolved in the sulfuric acid bath is dissolved. The ion is again electrodeposited on the copper foil surface. In addition, when one or more kinds of heavy metal compounds are dissolved, the heavy metals that have become metal ions are electrodeposited together with copper ions. According to the alternating current electrolysis treatment, the etching action, which is anodic dissolution along the grain boundary, proceeds on the copper foil surface by selecting the current condition, while the action of depositing the reduced metal on the surface very uniformly proceeds. In addition, the copper foil surface can be uniformly roughened with almost no change in thickness.

As a power supply method for this AC electrolysis treatment, a copper foil itself is used as an electrode, and an AC electrolysis treatment by direct power supply using an insoluble electrode such as carbon graphite as a counter electrode, and a copper phenomenon is used by using a bipolar phenomenon. Either of the methods of passing through the gap and performing AC electrolytic treatment by indirect power feeding can be adopted, but when one surface of the copper foil is selectively treated or the copper foil is rarely generated by contact with the contact feeding roll It is preferable to adopt an indirect power supply method using a bipolar phenomenon that contributes to an improvement in production quality because an effect of avoiding damage to the copper foil surface due to the above is expected.
Moreover, a commercial alternating current power supply can be used as the power supply used for the electrolytic treatment, and it is not necessary to provide a special power supply facility except for a special surface treatment.

  In the present invention, the copper foil to be treated may be a rolled copper foil or an electrolytic copper foil, but in order to maximize the effect of the present invention, the nominal thickness of the crystal grains consisting of fine granular crystals is 18 μm or less. The electrolytic copper foil is preferable. In recent years, a technology for refining the granular crystal structure of electrolytic copper foil has been established, and the conventional crystal structure of electrolytic copper foil is composed of columnar crystals with large grain boundaries, such as frost columns, and fine granular crystals with small grain boundaries. Electrolytic copper foil is on the market.

Moreover, an ultra-thin copper foil with a carrier can also be employed as the copper foil to be treated. With an ultrathin copper foil with a carrier, a copper foil with a thickness of 9 μm or less that is not easily handled can be easily separated via a release layer on at least one surface of a metal foil generally called a carrier with a thickness of 18 μm or more. It is laminated in a state.
The ultra-thin copper foil with a carrier as the copper foil to be treated is a granular crystal with fine grain of initial electrodeposition by electrolytic plating using a region with high current density in the manufacturing process of the ultra-thin copper foil. Since it reaches the liquid surface side as it is, it is possible to produce a granular crystal ultrathin electrolytic copper foil. By using the commercial alternating current roughening method of this embodiment on the copper foil surface of the carrier-attached ultrathin copper foil, for example, even if the ultrathin copper foil having a thickness of 3 μm before the surface treatment is surface treated, the unit weight Surface treatment can be performed while maintaining a thickness of about 27 g / m ² (about 3 μm). For this reason, not only the thickness defect in quality can be solved, but also the partial roughness variation can be alleviated and the effect of quality improvement can be achieved.
In the ultrathin copper foil with a carrier, the copper foil has a thickness of 45 g / m ² or less in terms of unit weight, and the carrier foil (support metal foil) has a thickness of 130 g / m ² or more in terms of unit weight. preferable.
In the conventional surface roughening method by cathodic electrolysis, the amount of metal copper deposited by copper plating increases from 10% to 20% with respect to the original foil, and the thickness also increases accordingly, resulting in a quality thickness defect. .

In the present invention, the preferable sulfuric acid concentration of the sulfuric acid single bath used as the electrolytic solution is sulfuric acid concentration of 30 to 200 g / l.
It is.
When using a bath in which heavy metal elements are added to sulfuric acid,
Sulfuric acid concentration 30 ~ 200g / l
Heavy metal element concentration: 0.5-5 g / l as dissolved metal concentration
In the case where a plurality of heavy metal elements are dissolved and added, the total concentration of dissolved metals is preferably in the range of 0.5 to 5 g / l. When a plurality of metals are added, the addition ratio Need not be prescribed equally.
When the sulfuric acid concentration is 30 g / l or less in the bath composition, electrodeposition tends to be extremely non-uniform even when the direct and indirect power feeding methods are used, the liquid resistance of the electrolytic solution increases, and the voltage rises, which is not effective. Even if the sulfuric acid concentration is 200 g / l or more, the object of the present invention can be sufficiently achieved, but it is not necessary to make the sulfuric acid concentration 200 g / l or more from an economical viewpoint.
On the other hand, when using a sulfuric acid bath to which a heavy metal element is added, the upper limit of the total concentration of one or more heavy metals is set to 5 g / l because the electrodeposited eutectoid at 5 g / l or more is smoothed. Etching roughening along sound crystal grain boundaries can be achieved by anodic dissolution, but since the treatment effect covering the surface is given priority during electrodeposition, it is excellent in the original intended fine and anchoring effect The surface shape may not be obtained. In addition, the lower limit of 0.5 g / l is considered in consideration of the ease of managing the bath composition during production, and if the concentration is lower than this concentration, there is a concern about processing exceeding the limit current density of the heavy metal to be added, exceeding the limit current density. This is because the heavy metal floats in the state of reduced metal powder in the treatment bath, and there is a risk that the suspended heavy metal may adhere to the surface of the copper foil, resulting in a quality defect.

  Moreover, although bath temperature is not specifically limited, When a sulfuric acid single bath is used, the range of normal temperature to 80 degreeC is preferable. On the other hand, when a bath to which sulfuric acid and heavy metal elements are added is used, the bath temperature is preferably set in the range of 40 to 60 ° C. It is preferable to use carbon graphite in that the material itself does not dissolve in the electrode material for surface roughening treatment by AC electrolysis. However, if there is another economically preferable insoluble material, the material can be adopted.

The current density during the alternating current electrolytic treatment in the present invention is preferably in the range of about 10 to 50 A / dm ² even when a single bath of sulfuric acid or a heavy metal element is dissolved and added, and the treatment time varies depending on the current density used. A range of 15 to 90 seconds is preferable for both conditions. However, the appropriate current condition and the treatment time vary depending on the bath temperature, the presence / absence of an added metal, the treatment time, and the bath composition conditions, and therefore this range is not limited.

The copper foil that has been subjected to AC electrolytic roughening treatment is preferably further subjected to rust prevention treatment or chromate rust prevention treatment with an organic rust inhibitor to impart corrosion resistance. For example, the degree of the rust-preventing film in the rust-preventing treatment with an organic rust inhibitor represented by a benzotriazole compound is 500 nm to 1000 nm as a theoretical film thickness obtained by measuring the electric double layer capacity and converting the measured value. The range is preferable, or when performing chromate rust prevention treatment using a bath in which a chromium compound is dissolved, the amount analyzed as metallic chromium has an adhesion amount in the range of 0.015 to 0.050 mg / dm ^2. It is preferable.

For the purpose of further adding chemical adhesion to the rust-prevented copper foil, at least one surface of the copper foil is selected from commercially available amino-based, epoxy-based, vinyl-based and chloroxy-based ones. A treatment to the extent that a single film is formed using various types of silane coupling agents is performed, and the amount of silicon adhering to the surface is adhered in the range of 0.001 to 0.015 mg / dm ² . It is preferable.

Hereinafter, the present invention will be specifically described with reference to Examples.
<Example 1>
An example of the indirect AC power feeding method employed in this embodiment is shown in FIG. An electrolytic copper foil (WS copper foil manufactured by Furukawa Circuit Foil Co., Ltd.) having a fine grain boundary with a nominal thickness of 12 μm made by an electrolytic manufacturing method is unrolled (bobbin) of the surface treatment apparatus shown in FIG. 1, a shielding plate 22 is arranged between the counter electrodes 21, 21 in the roughening treatment tank 2 in which the carbon graphite anode (counter electrode) 21 is arranged so as to face the carbon graphite anode (counter electrode) 21. The copper foil was guided, and the surface roughening treatment was performed by an indirect power feeding method on the copper foil surface that was on the liquid surface side during electrolytic foil formation under the following bath composition and indirect AC electrolysis conditions.

Bath composition (single sulfuric acid bath)
Sulfuric acid 100g / l
Electrolysis conditions Bath temperature 40 ± 3 ℃
Commercial AC electrolytic current density 25A / dm ²
Processing time 15 seconds

Subsequently, after the surface-roughened copper foil was guided to the water rinsing tank 3 shown in FIG. 1 and the surface of the copper foil was sufficiently washed, the copper foil was guided to the rustproofing tank 4, and chromium trioxide: 3 After immersing and passing through a normal temperature aqueous solution containing 0.0 g / l and subjecting the copper foil surface to a chromate rust prevention treatment, the copper foil is guided to a water rinsing tank 5 and the copper foil surface is thoroughly washed. The copper foil is introduced into the silane coupling treatment tank 6 so that a commercially available amino-based coupling agent: 0.5 wt% aqueous solution at room temperature uniformly comes into contact with the surface-treated surface, and then the copper foil is dried. After passing through the device 7, the copper foil was continuously wound up by the winding unit 8.
In FIG. 1, reference numeral 41 denotes a SUS anode set in the rust prevention treatment tank 4, 42 denotes a power supply roll for feeding power to the copper foil, and 61 denotes a silane coupling liquid filled in the silane coupling treatment tank 6.
The obtained copper foil was evaluated for the following items.

<Evaluation items>
Increase or decrease of copper foil thickness;
The unit weight value of the copper foil cut into a size of 10 cm × 10 cm is measured with an electronic balance capable of measuring the increase / decrease change of the copper foil thickness to 0.1 mg below the decimal point. The results are shown in Table 1.

Surface roughness;
The roughness of the surface subjected to the electrolytic roughening treatment was determined in accordance with the measurement method defined in JIS-C-6515 using a stylus type surface roughness measuring device, and the Rz value was measured before and after the roughening treatment. It was measured. The results are shown in Table 1.

Adhesion strength;
After the surface-treated copper foil rough surface and a commercially available polyimide resin base material are pressed for 60 minutes under a heating and pressing condition of a lamination temperature of 220 ° C. and a surface pressure of 25 kg / cm ² , the copper-clad laminate is insoluble in the etching solution. After bonding to the support, a 10 mm wide pattern was formed, and the adhesion strength between the roughened surface and the polyimide resin was measured with a peeling strength measuring instrument. The results are shown in Table 1.

<Example 2>
The copper foil used in Example 1 was surface roughened under the following conditions.
Bath composition (single sulfuric acid bath)
Sulfuric acid 150g / l
Electrolysis conditions Bath temperature 25 ± 3 ° C
Commercial AC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment were performed under the same conditions as in Example 1.
The characteristics of the surface-treated copper foil were measured in the same manner as in Example 1 for the same items as in Example 1, and the results are also shown in Table 1.

<Example 3>
The copper foil used in Example 1 was surface roughened under the following conditions.
Bath composition Sulfuric acid 150g / l
3g / l as molybdenum in sodium molybdate
Electrolysis conditions Bath temperature 25 ± 3 ° C
Commercial AC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment were performed under the same conditions as in Example 1.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.

<Example 4>
The copper foil used in Example 1 was surface roughened under the following conditions.
Bath composition Sulfuric acid 150g / l
3g / l as nickel sulfate nickel
Electrolysis conditions Bath temperature 25 ± 3 ° C
Commercial AC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment were performed under the same conditions as in Example 1.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.

<Example 5>
The copper foil used in Example 1 was surface roughened under the following conditions.
Bath composition Sulfuric acid 150g / l
1.5 g / l of cobalt sulfate
1.5 g / l as tungsten in sodium tungstate
Electrolysis conditions Bath temperature 25 ± 3 ° C
Commercial AC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment were performed under the same conditions as in Example 1.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.

<Example 6>
The copper foil used in Example 1 was surface roughened under the following conditions.
Bath composition (single sulfuric acid bath)
Sulfuric acid 150g / l
1.5g / l as nickel sulfate nickel
1.5g / l as molybdenum in sodium molybdate
Electrolysis conditions Bath temperature 25 ± 3 ° C
Commercial AC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment were performed under the same conditions as in Example 1.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.

<Comparative Example 1>
An electrolytic copper foil having a grain boundary with a columnar structure having a nominal thickness of 12 μm by a cathodic electrolytic foil method in the copper foil electrolytic manufacturing apparatus shown in FIG. 1 (MP copper foil manufactured by Furukawa Circuit Foil Co., Ltd., Rz: 3.6 μm) The surface on the liquid surface side (commonly referred to as the matte surface) during foil production was subjected to a surface roughening treatment using the following direct current electrolytic treatment conditions.
Bath composition (single sulfuric acid bath)
Sulfuric acid 150g / l
Electrolysis conditions Bath temperature 25 ± 3 ° C
DC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the original foil and the surface roughening treatment conditions, the water washing, chromate rust prevention treatment, water washing and silane coupling treatment shown in FIG.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.

<Comparative example 2>
Using the same copper foil as that in Comparative Example 1, the surface on the liquid surface side (commonly referred to as a matte surface) at the time of foil production was subjected to a surface roughening treatment using the following AC electrolytic treatment conditions.
Bath composition (single sulfuric acid bath)
Sulfuric acid 150g / l
Electrolysis conditions Bath temperature 25 ± 3 ° C
Commercial AC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the original foil and surface roughening treatment conditions, the chromate rust prevention treatment, water washing and silane coupling treatment were performed in the same manner as in Example 1.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.

<Comparative Example 3>
An electrolytic copper foil having a grain boundary with a columnar structure having a nominal thickness of 12 μm by a cathode electrolytic foil manufacturing method using the copper foil electrolytic manufacturing apparatus shown in FIG. 1 (MP copper foil manufactured by Furukawa Circuit Foil Co., Ltd., Rz: 1.8 μm) Using the copper foil used in Example 1, the surface on the liquid surface side (commonly referred to as the matte surface) during foil production was subjected to a surface roughening treatment using the following direct current electrolytic treatment conditions.
Bath composition (single sulfuric acid bath)
Sulfuric acid 150g / l
Electrolysis conditions Bath temperature 25 ± 3 ° C
DC electrolytic current density 20A / dm ²
Treatment time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment shown in FIG.
The characteristics of the surface-treated copper foil were measured by the same method as in Example 1, and the results are also shown in Table 1.

<Comparative Example 4>
The copper foil used in Comparative Example 3 was passed through the following roughening tank without electrolytic treatment (by electroless treatment).
Bath composition (single sulfuric acid bath)
Sulfuric acid 150g / l
Treatment conditions Bath temperature 25 ± 3 ℃
Passing time 15 seconds Except for the surface roughening treatment conditions, water washing, chromate rust prevention treatment, water washing and silane coupling treatment shown in FIG.
The characteristics of the surface-treated copper foil were measured for the same items as in Example 1 by the same method as in Example 1. The results are also shown in Table 1.
Except for Example 1, surface roughening treatment was carried out with Example 1.

According to the above example, a fine roughened shape was easily obtained without significantly changing the thickness of the thin copper foil (Example 3 increased by about 3% at the maximum).
In addition, the adhesion strength after the roughening treatment has sufficient strength even for polymide-based resins that are frequently used in recent years, and in particular, by using a bath formulation to which a specific heavy metal is added, further adhesion strength can be obtained. An improvement was obtained. In addition, as a result of obtaining adhesion strength without having a noticeable uneven shape, it is possible to provide an optimum material required by the FPC market.
According to the surface treatment method of the copper foil by AC power feeding of the present invention, the surface roughening state is obtained by performing the AC electrolytic roughening treatment indirectly on the surface treatment of the thin copper foil made of fine granular crystals that are not easy to handle. Can be processed uniformly and efficiently, improving productivity and quality.
Moreover, although not shown in Table 1, the copper foil obtained by surface treatment in a bath in which heavy metal elements are tempered has improved heat resistance effect, and has high temperature adhesion to industrial plastic films and thermosetting resins. The improvement was remarkable.

  As described above, the surface treatment method of the present invention improves the anchoring effect by exhibiting a fine rough surface roughened shape on a mirror-like glossy surface, and is mainly used for an industrial plastic film bonded to the copper foil or the surface. Adhesion with the thermosetting resin cast directly on the film can be improved, and the thickness of the film or casting resin to be bonded to the copper foil can be reduced. In addition, by adding a single or multiple heavy metal elements that chemically enhance the tight bond strength to the electrolytic bath, surface treatment can be performed simultaneously with heavy metal plating, so the surface treatment process can be simplified and inexpensive. It is possible to provide an electrolytic copper foil that substantially maintains the inherent thickness of the thin copper foil.

It is process drawing explaining the surface treatment process of copper foil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Unwinding part 2 Roughening processing tank 3 Flushing tank 4 Rust prevention processing tank 5 Flushing tank 6 Silane coupling processing tank 7 Drying device 8 Winding part

Claims (8)

  Using a sulfuric acid single bath or an electrolytic bath obtained by adding a heavy metal compound to sulfuric acid, at least one surface of a copper foil made of granular crystals is subjected to electrolytic treatment by alternating current, and the surface of the copper foil is roughened. A method for surface treatment of copper foil by AC power feeding.   2. The surface treatment method for copper foil by AC power feeding according to claim 1, wherein the electrolytic treatment by AC power feeding is performed by a commercial AC indirect power feeding method. The copper foil has a structure composed of fine granular crystals, the surface roughness of one surface thereof is at least Rz value of 2.5 μm or less, and the thickness of the copper foil is 160 g / m in terms of unit weight. The surface treatment method for a copper foil by AC power feeding according to claim 1 or 2 which is ² or less.   4. The electrolytic bath according to claim 1, wherein the electrolytic bath is an electrolytic bath in which at least one selected from the group of heavy metals consisting of nickel, cobalt, molybdenum, tungsten, antimony, vanadium, and silver is added to sulfuric acid. Surface treatment method of copper foil by AC power supply.   The surface treatment method of the copper foil by alternating current power supply in any one of Claim 1 to 4 which performs the rust prevention process by an organic type antirust agent or the chromate rust prevention process following the said alternating current power supply process.   The surface treatment method for a copper foil by AC power feeding according to any one of claims 1 to 5, wherein a surface treatment with a silane coupling agent is performed on at least one surface of the copper foil following the rust prevention treatment.   The copper foil surface treatment method according to claim 6, wherein the silane coupling agent is selected from an amino group, an epoxy group, a vinyl group, and a acryloxy group.   The copper foil surface treatment method according to claim 1 or 2, wherein the copper foil is a copper foil formed by plating on at least one surface of a support metal foil that can be easily peeled off.

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