KR102492019B1 - Electrolytic copper foil for printed circuit board and copper-clad laminated board using the same - Google Patents

Abstract

(Problem) An electrodeposited copper foil having high elongation after heat treatment and having fold resistance and having few abnormal projections on the rough surface side, which can be suitably used for a flexible printed wiring board having a low HAZE value when used as a copper-clad laminate. to provide.
(Solution) An electrodeposited copper foil for a printed wiring board in which a glossy surface of an electrodeposited copper foil produced by continuously depositing on the surface of a drum-shaped rotating cathode is an adhesive surface with an insulating resin substrate, wherein the shiny surface has an incident angle of 60° in the TD direction. The electrolytic copper foil for a printed wiring board, wherein the specular gloss of is 220 or less, and the sum of the specular gloss of the glossy surface at an incident angle of 60° in the TD direction and the MD direction is 350 or more.

Description

Electrolytic copper foil for printed wiring board and copper-clad laminate using the same

The present invention relates to an electrodeposited copper foil used for a printed wiring board, particularly preferably used for a flexible printed wiring board.

In recent years, the size and weight reduction and high functionality of electronic devices have been remarkable, and to cope with this, flexible printed wiring boards that can be placed in small gaps or three-dimensionally arranged in electronic devices are widely used, and the density of electronic components on the flexible printed wiring boards is also increased. is also in progress.

As one of the methods of mounting electronic components on a flexible printed wiring board at a high density, a method using an anisotropic conductive film is exemplified. This is a method of obtaining conduction in the vertical direction by sandwiching an anisotropic conductive film between a printed circuit board and a flexible printed wiring board, and then crimping with a method of heating and pressurizing the film.

In order to obtain conduction between the top and bottom, it is necessary to accurately align the printed circuit board and the printed wiring board. Therefore, marks for positioning are marked on each of the printed circuit board and the flexible printed wiring board, and alignment is performed while recognizing them with a CCD camera. Conduct.

Since alignment using a CCD camera is performed by taking pictures from the back of the circuit, the transparency of the exposed insulating resin substrate (hereinafter referred to as “resin substrate”) after the copper foil has been etched away is low, and if it is cloudy, the display cannot be recognized. Accurate positioning cannot be performed.

Therefore, it is considered that the haze of the exposed resin substrate (hereinafter referred to as "HAZE" value) should be as low as possible, and that a HAZE value of 80% or less is necessary for accurate alignment.

The HAZE value is influenced by the concavo-convex shape of the surface of the resin substrate. When the uneven shape of the surface is large, the reflected light is scattered and the transparency is lowered, so the HAZE value is increased.

Since the concavo-convex shape on the surface of the resin substrate is a replica that directly simulates the adhesive surface of the copper foil with the resin substrate, the larger the concavo-convex shape of the adhesive surface of the copper foil, the larger the concavo-convex shape on the surface of the replica resin substrate. The HAZE value increases. Therefore, in order to lower the HAZE value, it is necessary to reduce the roughness of the copper foil bonding surface and to reduce the concavo-convex shape. In addition, since the specular gloss increases when the concavo-convex shape is small, increasing the specular gloss also becomes a factor in lowering the HAZE value.

In an electrodeposited copper foil using a drum-shaped rotating cathode, the electrodeposited surface (hereinafter referred to as "glossy surface") and the electrodeposited surface (hereinafter referred to as "rough surface") of the peripheral surface of the drum-shaped rotating cathode are different in shape.

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

Also, when using either a rough surface or a glossy surface, it is necessary to increase the specular gloss.

In an electrolytic copper foil produced using a drum-shaped rotating cathode, additives such as various water-soluble polymers, various surfactants, and various organic sulfur-based compounds are appropriately selected for the electrolyte solution in order to reduce the roughness of the rough surface or increase the specular gloss. Addition is often practiced.

However, it is known that when various organic sulfur-based compounds indispensable as additives for lowering the roughness or increasing the specular gloss or nitrogen-containing compounds called levelers are used, the flexibility and folding resistance of the electrodeposited copper foil are poor. Therefore, if additives are added to reduce the HAZE value and manufactured, there is a risk that flexibility and folding resistance for use in flexible printed wiring boards cannot be secured.

In an electrodeposited copper foil produced using a drum-shaped rotating cathode, if the glossy surface is the adhesive surface of the resin substrate, the polishing of the drum-shaped rotating cathode surface, without adding additives affecting flexibility and fold resistance, It is possible to increase the specular gloss while lowering the roughness of the surface.

However, since the polished fringes on the surface of the drum-shaped rotating cathode serve as the origin of copper nuclei during electrolysis, when the polished fringes are made fine, copper nuclei are not sufficiently generated and abnormal precipitation on the rough surface side (hereinafter referred to as " Abnormal projections”) occur frequently.

If there are a large number of abnormal protrusions on the rough surface side, they become bite marks when winding the electrodeposited copper foil, resulting in poor appearance or poor running performance of the machine in roughening treatment or various surface treatment processes that impart heat resistance, chemical resistance, and rust prevention. Problems arise, such as

Moreover, when a flexible printed wiring board is formed, problems, such as entrapment of air bubbles between the coverlays affixed for surface protection of the flexible printed wiring board, arise.

Therefore, the adhesive surface with the resin substrate has low roughness and high mirror gloss, has flexibility and fold resistance, has few abnormal protrusions on the rough surface side, and has excellent appearance and work efficiency, resulting in a copper clad laminate. In this case, development of an electrodeposited copper foil that can be preferably used for a flexible printed wiring board having a low HAZE value of an exposed resin substrate after etching has been demanded.

Japanese Unexamined Patent Publication No. 2008-118163

In Patent Document 1, an electrodeposited copper foil used for a flexible printed wiring board in which the adhesive surface with the insulating layer is a glossy surface, the mirror gloss at an incident angle of 60° is 250 or more, and the light transmittance of the exposed insulating layer is high. This is disclosed.

However, since the electrodeposited copper foil disclosed in Patent Document 1 is deposited using a drum-shaped rotating cathode polished so as not to generate polished stripes as much as possible in order to avoid a decrease in the specular gloss of the glossy surface, during electrolysis There is a problem that generation of copper nuclei in the surface becomes insufficient, and a large number of abnormal protrusions are generated on the rough surface side.

The inventors of the present invention made it a technical problem to solve the above problems, and as a result of repeating numerous trial and error trials and experiments, using a drum-shaped rotating cathode, the drum width direction of the polished surface (hereinafter referred to as "TD direction”) at an angle of incidence of 60° is 220 or less, and the TD direction of the glossy surface and the longitudinal direction along the drum circumference (hereinafter referred to as “MD direction”) at an angle of incidence of 60° If the electrodeposited copper foil has a sum of specular gloss of 350 or more, it is an electrodeposited copper foil with very few abnormal protrusions on the rough surface side, as a glossy surface with low illumination and high specular gloss even without adding additives, and also as a copper clad laminate, The remarkable knowledge that the HAZE value of the exposed resin substrate after removal by etching is lowered was obtained, and the above technical problem was achieved.

The above technical problem can be solved by the present invention as follows.

The present invention is an electrodeposited copper foil for a printed wiring board in which the glossy surface of an electrolytic copper foil produced by continuously depositing on the surface of a drum-shaped rotating cathode is used as an adhesive surface with an insulating resin substrate, wherein the shiny surface has an incident angle of 60° in the TD direction. An electrodeposited copper foil for a printed wiring board having a specular gloss of 220 or less and a sum of the specular gloss of the glossy surface at an incident angle of 60° in the TD direction and the MD direction of 350 or more (claim 1).

Moreover, this invention is the electrodeposited copper foil for printed wiring boards as described in Claim 1 whose surface roughness Rz _JIS94 of the said electrolytic copper foil glossy surface is 1.5 micrometers or less (Claim 2).

Moreover, this invention is the process copper foil in which one or two or more process layers were formed on the glossy surface of the electrolytic copper foil for printed wiring boards of Claim 1 or 2 (claim 3).

Moreover, this invention is a copper clad laminated board in which the copper foil of any one of Claims 1-3 was stuck to the insulating resin base material (Claim 4).

Moreover, this invention is the copper clad laminated board of Claim 4 whose HAZE value is 80 % or less (Claim 5).

Moreover, this invention is a printed wiring board formed using the copper clad laminated board of Claim 4 or 5 (Claim 6).

According to the present invention, a drum-shaped rotating cathode polished at a low intensity level is used, and the specular gloss at an angle of incidence of 60° in the TD direction on the polished surface side of the electrolytic copper foil is 220 or less, and the angle of incidence in the TD direction and the MD direction is 60°. Since the sum of the specular gloss of is 350 or more, it is possible to suppress the occurrence of abnormal protrusions on the rough surface side and to suppress the biting flaws that occur during winding of the precipitated copper foil, resulting in an electrodeposited copper foil with excellent appearance and coated with copper. In the case of a laminated sheet, the HAZE value is 80% or less.

In addition, since an electrolytic copper foil having a glossy surface with high specular gloss at low light intensity is obtained without using additives affecting flexibility and folding resistance in the electrolyte, the elongation rate and the bending resistance rate after heat treatment can be maintained high, and the flexible printed wiring board It becomes the electrodeposited copper foil which can be used preferably.

In addition, since there are very few abnormal protrusions on the rough surface side, machine runability in various surface treatment steps is good, and air bubbles are difficult to enter when attaching to a protective sheet or the like, resulting in an electrodeposited copper foil with excellent work efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing abnormal protrusions of 3 µm or more on the rough surface side of Examples and Comparative Examples of the present invention.

The electrodeposited copper foil in the present invention is produced by immersing a drum-shaped rotating cathode in a sulfuric acid-copper sulfate aqueous solution, using an insoluble anode, depositing copper on the drum-shaped rotating cathode, and continuously peeling and winding.

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

For polishing of the drum-shaped rotating cathode, it is preferable to use a cylindrical polishing buff in which a nylon nonwoven fabric or the like is uniformly adhered and impregnated with polishing abrasive grains such as aluminum oxide and silicon carbide.

Cylindrical polishing buffs of No. 1200 and No. 1500 (manufactured by Kretoish Co., Ltd.) can be preferably used.

The polishing is performed by rotating a cylindrical polishing buff while rotating a rotating cathode to give a desired roughness to the drum-like rotating cathode.

In order for the specular gloss at an angle of incidence of 60° to be 220 or less in the TD direction and 350 or more in the sum of the TD and MD directions, the rotational speed of the rotating cathode is 60 to 200 mm/sec., of the cylindrical polishing buff. The number of revolutions is preferably 250 to 600 times/min., and the amplitude is preferably 20 to 25 mm.

In the present invention, since the roughness of the surface of the drum-shaped rotating cathode is the roughness of the adhesive surface of the electrodeposited copper foil with the resin substrate, the roughness Rz _JIS94 of the drum-shaped rotating cathode is preferably 1.5 μm or less, more preferably 1.3 μm. less than μm.

It is because there exists a possibility that the HAZE value of the resin base material exposed by etching may exceed 80 % when Rz _JIS94 of an electrolytic copper foil is larger than 1.5 micrometer.

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

Although the insoluble anode is not particularly limited, a titanium plate coated with a platinum group element or an oxide element thereof can be preferably used.

Any additive that does not reduce the elongation rate and the bending resistance after heat treatment of the electrolytic copper foil can be added to the electrolyte solution, and chlorine, water-soluble polymers, and the like can be exemplified as additives that can be added.

The thickness of the electrodeposited copper foil is preferably 9 μm to 18 μm. This is because if it is thicker than 18 μm, it cannot be used for a flexible printed board, and if it is thinner than 9 μm, pinholes tend to occur, neither of which is preferable.

In the electrolytic copper foil in this invention, various process layers can be formed as needed in the range which does not affect the HAZE value at the time of manufacturing a copper clad laminated board.

(Example)

Although the Example of this invention is shown below, this invention is not limited to this.

<Example 1>

Using a drum-shaped rotary cathode made of titanium and using a No. 1500 cylindrical polishing buff made of silicon carbide as an abrasive grain (manufactured by Cretoish Co., Ltd.), polishing finish so that the surface roughness Rz _JIS94 of the cathode is 1.5 μm or less did

Thereafter, an electrodeposited copper foil having a thickness of 12 μm was manufactured under the conditions of Table 1.

<Examples 2 and 3>

The drum-shaped rotary cathode made of titanium was polished using a No. 1200 cylindrical polishing buff made of silicon carbide as an abrasive grain so that the cathode had a surface roughness Rz _JIS94 of 1.5 µm or less.

Thereafter, an electrodeposited copper foil having a thickness of 12 μm was manufactured under the conditions of Table 1.

<Comparative Example 1>

The drum-shaped rotary cathode made of titanium was polished using a No. 2000 cylindrical polishing buff made of silicon carbide as an abrasive grain so that the cathode had a surface roughness Rz _JIS94 of 1.5 µm or less.

Thereafter, an electrodeposited copper foil having a thickness of 12 μm was manufactured under the conditions of Table 1.

<Comparative Example 2>

The drum-shaped rotary cathode made of titanium was buffed using a No. 1200 cylindrical polishing buff containing silicon carbide as an abrasive grain, and further polished using a No. 2000 sheet-shaped polishing pad, and the surface roughness of the cathode was Polishing was performed so that Rz _JIS94 would be 1.5 μm or less.

Thereafter, an electrodeposited copper foil having a thickness of 12 μm was manufactured under the conditions of Table 1.

<Comparative Example 3>

The drum-shaped rotary cathode made of titanium was polished using a No. 1000 cylindrical polishing buff made of silicon carbide as an abrasive grain so that the cathode had a surface roughness Rz _JIS94 of 1.5 µm or less.

Thereafter, an electrodeposited copper foil having a thickness of 12 μm was manufactured under the conditions of Table 1.

<Comparative Example 4>

The drum-shaped rotary cathode made of titanium was polished with a No. 1500 cylindrical polishing buff made of silicon carbide as an abrasive grain so that the surface roughness Rz _JIS94 of the cathode was greater than 1.5 μm.

Thereafter, an electrodeposited copper foil having a thickness of 12 μm was manufactured under the conditions of Table 1.

<Comparative Example 5>

Using the drum-shaped rotary cathode made of titanium used in Comparative Example 4, 20 mg/L of polyethylene glycol (molecular weight: 20,000) and a polyethyleneimine derivative (trade name: E Formin <registered trademark> PP-061: Weight average molecular weight 1200: Nippon Catalyst Co., Ltd.) 20.0 mg/L, 3-mercapto-1-propanesulfonate sodium 6.0 μmol/L, chlorine ion 20 mg/L were added, and the current Electrolysis was performed at a density of 40 A/dm 2 and a liquid temperature of 40°C to produce an electrodeposited copper foil having a thickness of 12 μm.

Each manufactured electrodeposited copper foil was measured by the following method.

[Illuminance]

Based on JIS B 0601, the surface roughness Rz _JIS94 of the glossy surface of each electrodeposited copper foil obtained in Examples 1 to 3 and Comparative Examples 1 to 4 and the rough surface of the electrodeposited copper foil obtained in Comparative Example 5 was obtained by using a surf coder SE1700α (manufactured by Kosaka Laboratory Co., Ltd.) ) was measured using.

[Mirror Gloss]

Based on JIS Z 8741, the mirror gloss of the glossy surface of each electrodeposited copper foil obtained in Examples 1 to 3 and Comparative Examples 1 to 4 and the rough surface of the electrodeposited copper foil obtained in Comparative Example 5 was determined by gloss meter GM-268 (Konica Minolta Co., Ltd.) production) was used, and the specular gloss (Gs (60°)) at an incident angle of 60° was measured in two directions, the TD direction and the MD direction.

[Elongation after heat treatment]

After holding each electrodeposited copper foil obtained in Examples 1 to 3 and Comparative Examples 1 to 5 at 200 degrees for 10 minutes, the elongation at 25 ° C. was measured based on IPC-TM-650 using an IM20 type tensile tester (manufactured by Intesco Co., Ltd.) was measured using

[Number of seams]

A test piece of 1/2 inch in the width direction and 2 cm in the length direction was cut out from each electrodeposited copper foil obtained in Examples 1 to 3 and Comparative Examples 1 to 5, and after holding at 200 ° C. for 10 minutes, the rough surface side was turned inside Bend it in half so that it is perpendicular to the length direction, put a load of 2 kg on the bent part and hold it for 10 seconds, unfold the bent test piece, apply the load and elongate it flat, then bend it again, and when the test piece is completely broken The number of times until was measured.

[HAZE value]

Using each electrodeposited copper foil obtained in Examples 1 to 3 and Comparative Examples 1 to 5 as a negative electrode and using a copper plate as an anode, an electrolytic solution containing 40 g/L of copper sulfate pentahydrate and 100 g/L of ethylenediamine tetrasodium tetraacetate was prepared at pH 5.5. After preparing with, the roughening process was performed on the electrolytic conditions of 35 degreeC of liquid temperature, 2 A/dm<2> of current density, and 25 second.

In addition, the roughening treatment was performed on the glossy surface side in Examples 1 to 3 and Comparative Examples 1 to 4, and on the rough surface side in Comparative Example 5.

After performing the roughening process, it washed with water for 5 second. Next, using the electrodeposited copper foil as a cathode and platinum as an anode, an electrolyte solution containing 10 g/L of sodium dichromate dihydrate was prepared at a pH of 4.5, and electrolysis was performed at a solution temperature of 32°C and a current density of 0.5 A/dm for 2 seconds, Chromate treatment was performed. Chromate treatment is performed to prevent oxidation of the electrodeposited copper foil.

Moreover, there is no influence on the HAZE value by various surface treatments.

The electrolytic copper foil subjected to the chromate 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 polyimide PIXEO BP <registered trademark> (manufactured by Kaneka Co., Ltd.), a double-sided two-layer copper-clad laminate was molded, and after etching the electrolytic copper foil on both sides, HAZE METER NDH7000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) HAZE value was measured based on JIS K 7136 using

Each measurement result is shown in Table 2.

[Number of protrusions on rough surface]

The height of the rough surface of the electrodeposited copper foil was measured using a color 3D laser microscope VK-9700 (manufactured by Keyence Corporation). A height image obtained in the range of 211.692 μm × 282.348 μm was binarized, threshold values were set at intervals of 3.0 μm to 0.5 μm, and the number of protrusions of each size was counted. The number of samples is 3.

Table 3 shows the number of protrusions in each case. Fig. 1 shows a drawing of Example 1 and Comparative Example 1 subjected to binarization.

From Tables 2 and 3, the electrodeposited copper foil in the present invention is an electrodeposited copper foil having a high elongation rate after heat treatment, a high bending resistance rate, flexibility, and very few abnormal protrusions on the rough surface side, when used as a copper clad laminate. , it was confirmed that the HAZE value of the exposed resin substrate after etching was 80% or less.

The electrodeposited copper foil in the present invention is an electrodeposited copper foil having high elongation and bending resistance after heat treatment, flexibility, and very few abnormal protrusions on the rough surface side. Since the value is low, it is an electrodeposited copper foil that can be preferably used for a flexible printed wiring board.

Therefore, the present invention is an invention with high industrial applicability.

Claims (10)

An electrodeposited copper foil for a printed wiring board produced by continuously depositing on the surface of a drum-shaped rotating cathode, wherein the glossy surface of the electrodeposited copper foil has a specular gloss of 220 or less at an incident angle of 60° in the TD direction, and the TD of the glossy surface is The sum of the specular gloss at an angle of incidence of 60° in the direction and the MD direction is 350 or more, the glossy surface is an adhesive surface with an insulating resin substrate, and the electrolytic bath of the electrolytic copper foil is added with an organic sulfur-based compound and a nitrogen-containing compound as additives. An electrolytic copper foil for a printed wiring board, which is an electrolytic bath not to be applied. An electrodeposited copper foil for a printed wiring board produced by continuously depositing on the surface of a drum-shaped rotating cathode, wherein the glossy surface of the electrodeposited copper foil has a specular gloss of 220 or less at an incident angle of 60° in the TD direction, and the TD of the glossy surface is The sum of the specular gloss of the direction and the MD direction at an angle of incidence of 60 ° is 350 or more, the glossy surface is an adhesive surface with an insulating resin substrate, and the electrodeposited copper foil having a thickness of 12 μm After heating at 200 ° C. for 10 minutes The electrodeposited copper foil for printed wiring boards whose elongation rate is 20 % or more. According to claim 1 or 2,
An electrodeposited copper foil for a printed wiring board, wherein the rough surface of the electrodeposited copper foil has no projections of 6.0 μm or more. According to claim 1 or 2,
An electrodeposited copper foil for a printed wiring board, wherein the surface roughness Rz _jis94 of the glossy surface of the electrodeposited copper foil is 1.5 μm or less. The treated electrodeposited copper foil in which one or two or more treated layers were formed on the glossy surface of the electrolytic copper foil for a printed wiring board according to claim 1 or 2. A copper-clad laminate formed by attaching an electrolytic copper foil produced by continuously depositing on the surface of a drum-shaped rotating cathode and an insulating resin substrate, wherein the electrolytic copper foil has a specular gloss of 220 or less at an incident angle of 60 ° in the TD direction of the glossy surface, In addition, the sum of the specular gloss of the glossy surface at an incident angle of 60° in the TD direction and the MD direction is 350 or more, and the copper-clad laminate formed by adhering the insulating resin substrate to the glossy surface. The copper clad laminated board formed by sticking the said insulating resin base material to the glossy surface of the electrolytic copper foil for printed wiring boards of Claim 1 or 2. According to claim 6,
A copper-clad laminate formed by adhering the glossy surface on which one or two or more processing layers are formed and the insulating resin substrate. According to claim 7,
A copper-clad laminate formed by adhering the glossy surface on which one or two or more processing layers are formed and the insulating resin substrate. According to claim 6,
A copper clad laminate having a HAZE value of 80% or less.

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