TW201638346A - Electrolytic copper foil for printed wiring board and copper-clad laminate using the electrolytic copper foil - Google Patents

Abstract

The present invention discloses an electrolytic copper foil for printed wiring board and copper-clad laminate using the electrolytic copper foil. The mentioned electrolytic copper foil for printed wiring board will utilize the glossy surface of electrolytic copper foil continuously precipitated and produced from the drum-shaped rotational cathode surface as the adhesion surface with the insulated resin substrate. The glossiness of mirror surface at the incidence angle of 60 DEG in the TD direction of the mentioned glossy surface is below 220, while the summation of glossiness of mirror surface at the incidence angle of 60 DEG in the TD and MD directions of the mentioned glossy surface is above 350. The present invention is aimed at providing the electrolytic copper foil with high extension rate, bending tolerance, and fewer irregular bumps on the side of rough surface after thermal treatment. The present invention can be suitable for low haze-value flexible printed wiring board under the situation of copper-clad laminate produced from the electrolytic copper foil.

Description

Electrolytic copper foil for printed wiring board and copper clad laminate using the same Field of invention

The present invention relates to an electrolytic copper foil for a printed wiring board, and more particularly to an electrolytic copper foil which can be applied to a flexible printed wiring board.

Background of the invention

In recent years, electronic devices have become more compact, lighter, and more functional. In response to these demands, flexible printed wiring boards that can be placed in extremely small gaps in electronic devices or can be arranged in a three-dimensional manner, and flexible printed wirings are widely used. The high density of electronic components on the board is also progressing.

One of methods for mounting an electronic component at a high density on a flexible printed wiring board is a method of using an anisotropic conductive film. In this method, an anisotropic conductive film is inserted between a printed circuit board and a flexible printed wiring board, and is press-fitted by heating and pressurization to obtain a conduction with respect to the vertical direction.

In order to obtain the conduction between the upper and lower sides, the positions of the printed circuit board and the printed wiring board need to be correctly aligned. Therefore, the positioning marks are respectively marked on the printed circuit board and the flexible printed wiring board, and these marks are recognized by the CCD camera. Perform the alignment.

The alignment using a CCD camera is taken from the back of the circuit. Therefore, the insulating resin substrate (hereinafter referred to as "resin substrate") exposed after etching and removing the copper foil has low transparency, and when blurred, the mark cannot be recognized, and accurate alignment cannot be performed.

Therefore, it can be said that the haze of the exposed resin substrate (hereinafter referred to as "HAZE" value) is preferably as low as possible, and the HAZE value is required to be 80% or less in order to accurately align.

The HAZE value is affected by the uneven shape of the surface of the resin substrate. If the uneven shape of the surface is large, the reflected light is scattered and the transparency is lowered, so the HAZE value becomes high.

The uneven shape on the surface of the resin substrate is a replica in which the bonding surface of the copper foil and the resin substrate is copied as it is. Therefore, if the uneven shape of the bonding surface of the copper foil is large, the resin base serving as a replica The uneven shape of the surface of the material is also large, and the HAZE value becomes high. Therefore, in order to lower the HAZE value, it is necessary to reduce the roughness of the copper foil bonding surface and reduce the uneven shape. Further, if the uneven shape is small, the specular gloss is high, and therefore, increasing the specular glossiness is also a major factor for lowering the HAZE value.

The surface of the electrodeposited copper foil on the circumferential surface of the drum-shaped rotating cathode (hereinafter referred to as "gloss surface") and the electrodeposition end surface (hereinafter referred to as "rough surface") are different in shape.

Both the rough surface and the shiny surface can be used as the bonding surface with the resin substrate, but in the case of using a rough surface, in order to lower the HAZE value, it is necessary to reduce the roughness.

In addition, it is necessary to increase the specular gloss regardless of which surface of the rough surface or the glossy surface is used.

In the electrolytic copper foil manufactured by using a drum-shaped rotating cathode, in order to reduce the roughness of the rough surface or to increase the specular gloss, various additives are usually added to the electrolyte, and as the additive, various water-soluble polymer materials and various surfaces are appropriately selected. Additives such as active agents and various organic sulfur compounds.

However, it is known that when various organic ionic compounds which are indispensable for reducing roughness or improving specular gloss or a nitrogen-containing compound called a leveling agent are used, the flexibility and resistance of the electrolytic copper foil are improved. The foldability will decrease. Therefore, when an additive is added for the purpose of lowering the HAZE value, the flexibility and folding endurance for the flexible printed wiring board may not be ensured.

In the electrolytic copper foil produced by using the drum-shaped rotating cathode, if the shiny surface is used as the bonding surface of the resin substrate, the cathode surface can be rotated by a drum without adding an additive which affects flexibility and folding resistance. Polishing to reduce the roughness of the shiny side and improve the specular gloss.

However, since the polishing streaks on the surface of the drum-shaped rotating cathode become the starting point of the nucleus of copper generated during electrolysis, if the polishing strip marks are made thin, the core of copper cannot be sufficiently generated, and a large amount of abnormal precipitation occurs on the rough surface side (hereinafter referred to as As "abnormal protrusion").

When a large number of abnormal protrusions are present on the rough surface side, there is a problem that creases occur when the electrolytic copper foil is taken up, and thus the appearance may be poor, and the roughening treatment may be performed to impart heat resistance and chemical resistance. The mechanical mobility of the various surface treatment processes of the rust preventive force is deteriorated.

In addition, there are problems in that, when forming a flexible printed wiring board, the flexible printed wiring board and the surface for protection are adhered. Air bubbles and the like are entered between the cover layers.

Therefore, it is desired to develop an electrolytic copper foil having a low roughness on the bonding surface with a resin substrate, high specular gloss, flexibility, and folding resistance, and less irregular protrusions on the rough side, and appearance and work efficiency. In the case of producing a copper clad laminate, it can be suitably used for a flexible printed wiring board having a low HAZE value of a resin substrate exposed after etching.

Prior art literature

Patent literature

Patent Document 1: Japan Special Open 2008-118163

Patent Document 1 discloses an electrolytic copper foil for a flexible printed wiring board, in which the bonding surface with the insulating layer is a glossy surface, and the specular gloss at an incident angle of 60° of the glossy surface is 250 or more, and is exposed. The insulating layer has a high light transmittance.

However, in the electrolytic copper foil disclosed in Patent Document 1, in order to prevent a decrease in the specular gloss of the glossy surface, precipitation is performed using a drum-shaped rotating cathode which is polished so as not to cause polishing streaks as much as possible. Therefore, there is a problem in that the nucleus of copper at the time of electrolysis is insufficient, and a large number of abnormal protrusions are generated on the rough surface side.

Summary of invention

The present inventors have solved the above problems as a technical problem, and have repeatedly conducted a lot of trial-and-error trials and experiments, and as a result, the following remarkable findings have been obtained, and the above-mentioned technical problems have been attained. The present invention overcomes the existing Insufficient in the art, an electrolytic copper foil is provided. If the drum-shaped rotating cathode is used to form a glossy surface, the specular gloss of the incident angle of 60° in the drum width direction (hereinafter referred to as "TD direction") is 220 or less, and the TD direction and along the glossy surface The electrolytic copper foil having a mirror gloss of 60° or more at an incident angle of 60° in the longitudinal direction of the drum circumferential surface (hereinafter referred to as “MD direction”) can be low roughness and specular gloss without adding an additive. A high-gloss surface, an electrolytic copper foil having a very small number of abnormal protrusions on the rough surface side, and a copper-clad laminate, the HAZE value of the exposed resin substrate after etching removal is lowered.

In order to solve the above technical problems, the present invention is achieved by the following technical solutions.

The present invention provides an electrodeposited copper foil for a printed wiring board, wherein a shiny surface of an electrolytic copper foil produced by continuously depositing a surface of a drum-shaped rotating cathode is used as a bonding surface with an insulating resin substrate, wherein the TD of the glossy surface The specular gloss of the incident angle of 60° in the direction is 220 or less, and the sum of the specular gloss of the incident angle of 60° in the TD direction of the glossy surface and the MD direction is 350 or more (first aspect).

The electrolytic copper foil for a printed wiring board according to the first aspect of the invention, wherein the surface roughness Rzjis94 of the shiny surface of the electrolytic copper foil is 1.5 μm or less (second aspect).

Further, the present invention provides a treatment layer for copper foil, which is provided with a treatment layer of 1 or 2 or more on the shiny surface of the electrolytic copper foil for a printed wiring board according to the first or second aspect (third aspect).

In addition, the present invention provides a copper clad laminate which will be the first~ The copper foil according to any one of the third aspects is formed by adhering to an insulating resin substrate (fourth aspect).

The copper clad laminate according to the fourth or fifth aspect, wherein the HAZE value is 80% or less.

Further, the present invention provides a printed wiring board formed using the copper clad laminate according to the fourth or fifth aspect.

Compared with the prior art, the present invention has the beneficial effects of using a drum-shaped rotating cathode polished to a low roughness and a specular gloss of an incident angle of 60° in the TD direction of the shiny side of the electrolytic copper foil according to the present invention. When the sum is 220 or less, and the sum of the specular gloss of the incident angle of 60° in the TD direction and the MD direction is 350 or more, the occurrence of abnormal protrusions on the rough surface side can be suppressed, and the occurrence of the copper foil deposited during the winding can be suppressed. Since it is eroded, it is an electrolytic copper foil which is excellent in appearance, and when it is set as a copper-clad laminate, HAZE value is 80 % or less.

In addition, even if the electrolyte does not use an additive that affects flexibility and folding resistance, it can be an electrolytic copper foil having a low roughness and a glossy surface having a high specular gloss. Therefore, it is possible to maintain the elongation after heat treatment or The folding end rate is high and can be suitably applied to an electrolytic copper foil of a flexible printed wiring board.

In addition, since the abnormal protrusions on the rough surface side are extremely small, the mechanical mobility in the various surface treatment steps is good, and when the adhesion to the protective sheet or the like is performed, the bubbles are hard to enter, and thus the electrolytic copper having excellent work efficiency is obtained. Foil.

Fig. 1 is a view showing an abnormal protrusion having a rough surface side of 3 μm or more in Examples and Comparative Examples of the present invention.

detailed description

The invention will be further described in detail below with reference to the drawings and specific embodiments. The electrodeposited copper foil of the present invention is produced by immersing a drum-shaped rotating cathode in a sulfuric acid-copper sulfate aqueous solution, depositing copper on a drum-shaped rotating cathode using an insoluble anode, and continuously peeling and winding.

The drum-shaped rotating cathode is not particularly limited, but a titanium drum-shaped rotating cathode is preferably used.

The polishing of the drum-shaped rotating cathode is preferably performed by uniformly bonding a cylindrical polishing wheel impregnated with polishing abrasive grains such as alumina or tantalum carbide on a nylon nonwoven fabric or the like.

As the cylindrical polishing wheel, No. 1200 and No. 1500 (manufactured by Kure Grinding Wheel Co., Ltd.) can be suitably used.

At the time of polishing, the cylindrical polishing wheel is rotated while rotating the rotating cathode to achieve a desired roughness of the drum-shaped rotating cathode.

In order to make the specular gloss at an incident angle of 60° 220 or less in the TD direction and 350 or more in the TD direction and the MD direction, it is preferable that the rotational speed of the rotating cathode is 60 to 200 mm/sec. The speed is 250~600 laps/min., and the amplitude is 20~25mm.

In the present invention, in order to make the roughness of the surface of the drum-shaped rotating cathode reach the roughness of the bonding surface of the electrolytic copper foil and the resin substrate, it is preferable to have a drum shape. The roughness Rzjis94 of the rotating cathode is set to 1.5 μm or less, and more preferably 1.3 μm or less.

If the Rzjis 94 of the electrolytic copper foil is larger than 1.5 μm, the HAZE value of the resin substrate exposed by etching may exceed 80%.

Preferably, the electrolysis conditions are: a current density of 30 to 60 A/dm ² and a liquid temperature of 35 to 45 °C.

The insoluble anode is not particularly limited, but a titanium plate coated with a platinum group element or an oxide element thereof can be suitably used.

In the electrolytic solution, an additive which does not reduce the elongation and the folding resistance after the heat treatment of the electrolytic copper foil can be added. Examples of the additive which can be added include chlorine and a water-soluble polymer.

The thickness of the electrolytic copper foil is preferably 9 μm to 18 μm. If it is thicker than 18 μm, it cannot be used for a flexible printed board. If it is thinner than 9 μm, pinholes are likely to occur, which is not preferable.

In the electrolytic copper foil of the present invention, various treatment layers can be provided as needed within a range that does not affect the HAZE value at the time of producing the copper clad laminate.

Example

Embodiments of the invention are shown below, but the invention is not limited thereto.

<Example 1>

A cylindrical polishing wheel made of titanium was used, and a cylindrical polishing wheel of No. 1500 (manufactured by Kaneka Co., Ltd., the same applies hereinafter) using ruthenium carbide as the abrasive grains was subjected to finish polishing to make the surface roughness Rzjis94 of the cathode 1.5 μm or less.

Thereafter, an electrolytic copper foil having a thickness of 12 μm was produced in accordance with the conditions of Table 1.

<Examples 2 and 3>

The drum-shaped rotating cathode made of titanium was subjected to finish polishing using a cylindrical polishing wheel of No. 1200 using cerium carbide as abrasive grains, and the surface roughness Rzjis94 of the cathode was 1.5 μm or less.

Thereafter, an electrolytic copper foil having a thickness of 12 μm was produced in accordance with the conditions of Table 1.

<Comparative Example 1>

The drum-shaped rotating cathode made of titanium was subjected to finish polishing using a cylindrical polishing wheel of No. 2000 having cerium carbide as abrasive grains, and the surface roughness Rzjis94 of the cathode was 1.5 μm or less.

Thereafter, an electrolytic copper foil having a thickness of 12 μm was produced in accordance with the conditions of Table 1.

<Comparative Example 2>

The drum-shaped rotating cathode made of titanium is polished using a cylindrical polishing wheel of No. 1200 using cerium carbide as abrasive grains, and then polished using a sheet-like polishing pad of No. 2000, and finish polishing to make the surface roughness of the cathode Rzjis94 is 1.5 μm or less.

Thereafter, an electrolytic copper foil having a thickness of 12 μm was produced in accordance with the conditions of Table 1.

<Comparative Example 3>

Titanium drum-shaped rotating cathode using 1000-gauge with niobium carbide as abrasive The cylindrical polishing wheel is subjected to finish polishing to have a surface roughness Rzjis94 of the cathode of 1.5 μm or less.

Thereafter, an electrolytic copper foil having a thickness of 12 μm was produced in accordance with the conditions of Table 1.

<Comparative Example 4>

The drum-shaped rotating cathode made of titanium was subjected to finish polishing using a cylindrical polishing wheel of No. 1500 using cerium carbide as abrasive grains, and the surface roughness Rzjis94 of the cathode was more than 1.5 μm.

Thereafter, an electrolytic copper foil having a thickness of 12 μm was produced in accordance with the conditions of Table 1.

<Comparative Example 5>

Using a titanium drum-shaped rotating cathode used in Comparative Example 4, polyethylene glycol (molecular weight: 20,000) 20 mg/L, polyethyleneimine was added to an electrolytic solution of 280 g/L of copper sulfate pentahydrate and 80 g/L of sulfuric acid. Derivative (trade name: Epomin <registered trademark> PP-061: weight average molecular weight 1200: manufactured by Nippon Shokubai Co., Ltd.) 20.0 mg/L, sodium 3-mercapto-1-propanesulfonate 6.0 μmol/L, chloride ion 20 mg/L was electrolyzed at a current density of 40 A/dm ² and a liquid temperature of 40 ° C to produce an electrolytic copper foil having a thickness of 12 μm.

Each of the produced electrolytic copper foils was measured by the following method.

[roughness]

Based on JIS B0601, the shiny surface of each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 4 and the rough surface of the electrolytic copper foil obtained in Comparative Example 5 were measured using Surfcorder SE1700α ( manufactured by Kosei Research Co., Ltd.). Surface roughness Rzjis94.

[Mirror gloss]

Each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 4 The glossiness of the glossy surface and the rough surface of the electrolytic copper foil obtained in Comparative Example 5 were based on JIS Z8741, using a gloss meter GM-268 (manufactured by Konica Minolta Co., Ltd.) in both the TD direction and the MD direction. The specular gloss (Gs (60°)) of the incident angle of 60° was measured in one direction.

[Elongation after heat treatment]

Each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 5 was held at 200 °C for 10 minutes, and then an IM20 type tensile tester (manufactured by INTESCO Co., Ltd.) was used based on IPC-TM-650. ) The elongation at 25 ° C was measured.

[number of bends]

Each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 5 was cut out of a test piece having a width direction of 1/2 inch and a longitudinal direction of 2 cm, and was held at 200 ° C for 10 minutes, and then the rough surface side was used. The inner side is folded in a manner perpendicular to the longitudinal direction, and a load of 2 kg is placed on the bent portion for 10 seconds. The bent test piece is opened and the load is placed to flatten it, and then the bending is performed again, and the measurement is continued until the test. The number of times the piece has completely broken.

[HAZE value]

Each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 5 was used as a cathode, and a copper plate was used as an anode, and an electrolytic solution of 40 g/L of copper sulfate pentahydrate and tetrasodium ethylenediaminetetraacetate 100 g/L was prepared. After the pH was 5.5, the roughening treatment was carried out under the electrolytic conditions of a liquid temperature of 35 ° C and a current density of 2 A/dm ² for 25 seconds.

Further, Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to roughening treatment on the glossy side, and Comparative Example 5 was subjected to roughening treatment on the rough surface side.

After the roughening treatment, the water was washed for 5 seconds. Next, the electrolytic copper foil was used as a cathode, platinum was used as an anode, and an electrolyte solution of 10 g/L of sodium dichromate dihydrate was adjusted to pH 4.5, and electrolysis was carried out at a liquid temperature of 32 ° C and a current density of 0.5 A/dm ² . In seconds, chromate gloss treatment is performed. The chromate gloss treatment is performed to prevent oxidation of the electrolytic copper foil.

In addition, various surface treatments have no effect on the HAZE value.

The electrolytic copper foil subjected to the chromate gloss treatment was washed with water for 5 seconds, and then naturally dried to obtain a surface-treated copper foil. Using the obtained surface-treated copper foil and polyimine PIXEO BP <registered trademark> (manufactured by Kaneka Corporation), a double-sided two-layer copper-clad laminate was formed, and the double-sided electrolytic copper foil was etched and used. HAZE METER NDH7000 (manufactured by Nippon Denshoku Industries Co., Ltd.), and the HAZE value was measured based on JIS K 7136.

The results of each measurement are shown in Table 2.

[Number of rough side protrusions]

The height of the rough surface of the electrolytic copper foil was measured using a color 3D laser microscope VK-9700 (manufactured by Keyence Corporation). The height image obtained in the range of 211.692 μm × 282.348 μm is performed 2 For the value processing, the threshold is set with a scale of 3.0 μm to 0.5 μm, and the number of protrusions of respective sizes is counted. The number of samples is 3.

Table 3 shows the number of protrusions of each example. In addition, FIG. 1 is a view showing the binarization processing of Example 1 and Comparative Example 1.

According to Tables 2 and 3, it was confirmed that the electrolytic copper foil of the present invention has high elongation after heat treatment, high folding resistance, flexibility, and extremely small irregularities on the rough surface side, and is formed into a copper clad laminate. In the case of the resin substrate exposed after the etching, the HAZE value is 80% or less.

Industrial availability

The electrolytic copper foil of the present invention has high elongation and folding resistance after heat treatment, and has flexibility, and is an electrolytic copper foil having a very small number of abnormal protrusions on the rough surface side, and is exposed after etching in the case of forming a copper-clad laminate. Since the resin substrate has a low HAZE value, it is an electrolytic copper foil which can be suitably used for a flexible printed wiring board.

Therefore, the present invention is an industrially available invention with high availability.

Claims (6)

An electrolytic copper foil for a printed wiring board, which has a glossy surface of an electrolytic copper foil produced by continuously depositing a surface of a drum-shaped rotating cathode as an adhesive surface to an insulating resin substrate, wherein the gloss surface is incident in the TD direction The mirror gloss of the angle of 60° is 220 or less, and the sum of the specular gloss of the TD direction of the gloss surface and the incident angle of 60° in the MD direction is 350 or more. The electrodeposited copper foil for a printed wiring board according to claim 1, wherein the surface roughness Rzjis94 of the shiny surface of the electrodeposited copper foil is 1.5 μm or less. A copper foil for processing, wherein one or two or more treatment layers are provided on the shiny surface of the electrolytic copper foil for a printed wiring board according to claim 1 or 2. A copper-clad laminate obtained by adhering a copper foil according to any one of claims 1 to 3 to an insulating resin substrate. The copper clad laminate according to claim 4, wherein the haze value (HAZE value) is 80% or less. A printed wiring board formed using the copper clad laminate described in claim 4 or 5.