TWI761298B - Electrodeposited copper foil for printed wiring board and copper clad laminate using the same - Google Patents

Abstract

The invention discloses an electrolytic copper foil for a printed wiring board and a copper-clad laminate using the electrolytic copper foil. The glossy surface serves as the adhesive surface with the insulating resin substrate, the specular glossiness of the glossy surface at an incident angle of 60° in the TD direction is 220 or less, and the glossy surface has an incidence angle of 60° in the TD direction and the MD direction. The sum of the specular gloss of ° is 350 or more. The present invention aims to provide an electrolytic copper foil with high elongation after heat treatment, folding resistance, and less abnormal protrusions on the rough surface side, which can be applied to fogging when the electrolytic copper foil is used as a copper clad laminate. A flexible printed wiring board with a low degree value (HAZE value).

Description

Electrodeposited 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, in particular to an electrolytic copper foil that can be applied to a flexible printed wiring board.

Background of the Invention

In recent years, electronic equipment has become significantly smaller, lighter, and more functional. In response to these requirements, flexible printed wiring boards that can be placed in an extremely small gap in the electronic equipment or can be placed three-dimensionally are widely used. In addition, flexible printed wiring Densification of electronic parts on the board is also progressing.

As one of the methods of mounting electronic components in a high density on a flexible printed wiring board, the method of using an anisotropic conductive film is mentioned. In this method, an anisotropic conductive film is inserted between a printed wiring board and a flexible printed wiring board, and is press-fitted by a method of heating and pressing to obtain conduction in the vertical direction.

In order to obtain conduction between the upper and lower sides, it is necessary to align the positions of the printed circuit board and the printed wiring board correctly. Therefore, marks for positioning are marked on the printed circuit board and the flexible printed wiring board respectively, and the marks are identified with a CCD camera. Align.

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

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

The HAZE value is affected by the uneven shape of the surface of the resin substrate. When the unevenness of the surface is large, the reflected light is scattered and the transparency is lowered, so that the HAZE value is increased.

The concavo-convex shape on the surface of the resin base material is a replica made by copying the adhesive surface of the copper foil and the resin base material as it is. The uneven shape of the surface of the material is also large, and the HAZE value is high. Therefore, in order to reduce the HAZE value, it is necessary to reduce the roughness of the copper foil bonding surface and reduce the uneven shape. In addition, if the concavo-convex shape is small, the specular gloss becomes high, and therefore, increasing the specular gloss is also a major factor for reducing the HAZE value.

Electrodeposited copper foil using a drum-shaped rotary cathode has a different shape on the peripheral surface of the drum-shaped rotary cathode where electrodeposition starts (hereinafter referred to as "glossy surface") and the electrodeposition finish surface (hereinafter referred to as "rough surface").

Both the rough surface and the glossy surface can be used as the bonding surface to the resin substrate, but when the rough surface is used, it is necessary to reduce the roughness in order to reduce the HAZE value.

In addition, it is necessary to improve the specular gloss regardless of whether a rough surface or a glossy surface is used.

In order to reduce the roughness of the rough surface or improve the specular gloss of the electrolytic copper foil produced by using the drum-shaped rotating cathode, various additives are usually added to the electrolyte. As the additives, various water-soluble polymer substances, various surface Active agents, various organic sulfur compounds and other additives.

However, it is known that when various organic ionic compounds or nitrogen-containing compounds called levelers, which are indispensable as additives for reducing roughness or improving specular gloss, are used, the flexibility and durability of electrolytic copper foil are improved. Foldability will decrease. Therefore, when an additive is added in order to lower the HAZE value and it is manufactured, there exists a possibility that the flexibility and folding endurance for a flexible printed wiring board cannot be ensured.

In the electrolytic copper foil produced by using the drum-shaped rotating cathode, if the glossy surface is used as the adhesive surface of the resin substrate, even if no additives that affect the flexibility and folding resistance are added, the surface of the drum-shaped rotating cathode can pass through. polishing to reduce the roughness of the glossy surface and improve the specular gloss.

However, since the polishing streak on the surface of the drum-shaped rotating cathode serves as the starting point for the generation of copper nuclei during electrolysis, if the polishing streak is made thinner, the copper nucleation cannot be sufficiently generated, and a large amount of abnormal precipitation occurs on the rough surface side (hereinafter referred to as referred to as "abnormal protrusions").

When a large number of abnormal protrusions are present on the rough surface side, creases are generated when the electrolytic copper foil is wound up, which may cause poor appearance, and may cause problems in roughening treatment or imparting heat resistance, chemical resistance and chemical resistance. The mobility of the machine in various surface treatment steps of rust-proof power is deteriorated.

In addition, when forming a flexible printed wiring board, there arises a problem that the flexible printed wiring board and the surface-protected surface are attached. Air bubbles etc. enter between the covering layers.

Therefore, it is desired to develop an electrolytic copper foil which has low roughness on the bonding surface with the resin substrate, high specular gloss, flexibility and folding resistance, and less abnormal protrusions on the rough surface side, appearance and work efficiency It is excellent, and when used as a copper-clad laminate, it can be suitably used for a flexible printed wiring board having a low HAZE value of a resin base material exposed after etching.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2008-118163

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

However, the disadvantage is that, in the electrolytic copper foil disclosed in Patent Document 1, in order to avoid a drop in the specular gloss of the glossy surface, the precipitation is carried out using a drum-shaped rotating cathode that has been polished so as not to generate polishing streaks as much as possible. Therefore, there is a problem that the nucleation of copper during electrolysis is insufficient, and a large number of abnormal protrusions are generated on the rough surface side.

Summary of Invention

The inventors of the present invention made the solution of the above-mentioned problems as a technical problem, and as a result of repeated exploratory trial production and experiments, the following remarkable findings were obtained, and the above-mentioned technical problem was achieved. The present invention overcomes the existing For the deficiencies in the technology, an electrolytic copper foil is provided. If the specular glossiness at an incident angle of 60° in the drum width direction (hereinafter referred to as "TD direction") of the glossy surface is 220 or less using a drum-shaped rotating cathode, and the TD direction of the glossy surface and along the Electrodeposited copper foil with a sum of specular gloss at an incident angle of 60° in the longitudinal direction of the drum peripheral surface (hereinafter referred to as "MD direction") of 350 or more can have low roughness and specular gloss even without adding additives A high glossy surface, an electrolytic copper foil with very few abnormal protrusions on the rough surface side, and a copper clad laminate, the HAZE value of the exposed resin base material after etching removal becomes low.

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

The present invention provides an electrolytic copper foil for a printed wiring board, wherein the glossy surface of the electrolytic copper foil produced by continuous precipitation on the 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 is The specular gloss at an incident angle of 60° in the direction is 220 or less, and the sum of the specular gloss at an incident angle of 60° in the TD and MD directions of the glossy surface is 350 or more (first aspect).

In addition, the present invention may include the electrolytic copper foil for a printed wiring board according to the first aspect, wherein the surface roughness Rzjis94 of the glossy surface of the electrolytic copper foil is 1.5 μm or less (second aspect).

Further, the present invention provides a treated copper foil in which 1 or 2 or more treated layers are provided on the glossy surface of the electrolytic copper foil for a printed wiring board of the first or second aspect (third aspect).

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

In addition, the present invention may further include: 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 beneficial effects of the present invention are: according to the present invention, due to the use of a drum-shaped rotating cathode polished to a low roughness, and the specular glossiness of the incident angle in the TD direction of the glossy surface side of the electrolytic copper foil is 60° It is 220 or less, and the sum of the specular glossiness at an incident angle of 60° in the TD direction and the MD direction is 350 or more, so the occurrence of abnormal protrusions on the rough surface side can be suppressed, and the generation of the deposited copper foil can be suppressed. Erosion, therefore, it becomes an electrolytic copper foil excellent in appearance, and when used as a copper-clad laminate, the HAZE value is 80% or less.

In addition, even if additives that affect flexibility and folding endurance are not used in the electrolyte solution, it is possible to obtain an electrolytic copper foil with low roughness and a glossy surface with high specular gloss, so that the elongation after heat treatment can be maintained or It has a high bending resistance and can be suitably applied to the electrolytic copper foil of a flexible printed wiring board.

In addition, since there are very few abnormal protrusions on the rough surface side, mechanical mobility in various surface treatment steps is good, and air bubbles are difficult to enter when bonding with a protective sheet, etc., so it is an electrolytic copper with excellent work efficiency. foil.

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.

Detailed ways

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

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

For the polishing of the drum-shaped rotating cathode, it is preferable to use a cylindrical polishing wheel impregnated with polishing abrasive grains such as alumina and silicon carbide uniformly bonded to a nylon non-woven fabric or the like.

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

During polishing, while rotating the rotating cathode, the cylindrical buffing wheel is rotated so that the drum-shaped rotating cathode has a desired roughness.

In order to make the specular gloss under the incident angle of 60° be 220 or less in the TD direction, and the sum of the TD direction and the MD direction is 350 or more, the rotation speed of the rotating cathode is preferably 60~200mm/sec. The rotational speed is 250~600 revolutions/min., and the amplitude is 20~25mm.

In the present invention, in order to make the surface roughness of the drum-shaped rotating cathode equal to the roughness of the bonding surface of the electrolytic copper foil and the resin base material, it is preferable that the drum-shaped rotating cathode be The roughness Rzjis94 of the rotating cathode is set to 1.5 μm or less, more preferably 1.3 μm or less.

When the Rzjis94 of the electrolytic copper foil is larger than 1.5 μm, the HAZE value of the resin base material exposed by etching may exceed 80%.

The preferred electrolysis conditions are: current density of 30-60 A/dm ² and liquid temperature of 35-45°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 appropriately used.

In the electrolytic solution, any additives may be added as long as they do not reduce the elongation and bending resistance after the heat treatment of the electrolytic copper foil. Examples of additives that can be added include chlorine, water-soluble polymers, and the like.

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, and if it is thinner than 9 μm, pinholes are likely to be generated, so both are not preferable.

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

Example

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

<Example 1>

A drum-shaped rotating cathode made of titanium was used, and a cylindrical polishing wheel of No. 1500 (manufactured by Kure Grinding Wheel Co., Ltd., the same below) using silicon carbide as abrasive grains was used for fine polishing, so that the surface roughness of the cathode was Rzjis94. 1.5μm or less.

Then, according to the conditions of Table 1, the electrolytic copper foil of thickness 12 micrometers was manufactured.

〔Table 1〕

<Examples 2 and 3>

The titanium drum-shaped rotating cathode was finely polished using a 1200-size cylindrical polishing wheel using silicon carbide as abrasive grains so that the surface roughness Rzjis94 of the cathode was 1.5 μm or less.

Then, according to the conditions of Table 1, the electrolytic copper foil of thickness 12 micrometers was manufactured.

<Comparative Example 1>

The titanium drum-shaped rotating cathode was finely polished using a 2000-size cylindrical polishing wheel using silicon carbide as abrasive grains so that the surface roughness Rzjis94 of the cathode was 1.5 μm or less.

Then, according to the conditions of Table 1, the electrolytic copper foil of thickness 12 micrometers was manufactured.

<Comparative Example 2>

The titanium drum-shaped rotating cathode is polished with a 1200-gauge cylindrical polishing wheel using silicon carbide as abrasive grains, and then polished with a 2000-gauge sheet polishing pad, and finely polished to make the surface roughness of the cathode. Rzjis94 becomes 1.5 μm or less.

Then, according to the conditions of Table 1, the electrolytic copper foil of thickness 12 micrometers was manufactured.

<Comparative Example 3>

Titanium drum-shaped rotating cathode uses 1000 No. 1000 silicon carbide abrasive particles The cylindrical buffing wheel was finely polished so that the surface roughness Rzjis94 of the cathode was 1.5 μm or less.

Then, according to the conditions of Table 1, the electrolytic copper foil of thickness 12 micrometers was manufactured.

<Comparative Example 4>

The drum-shaped rotating cathode made of titanium was finely polished with a cylindrical polishing wheel of No. 1500 with silicon carbide as abrasive grains, so that the surface roughness Rzjis94 of the cathode was greater than 1.5 μm.

Then, according to the conditions of Table 1, the electrolytic copper foil of thickness 12 micrometers was manufactured.

<Comparative Example 5>

Using the titanium drum-shaped rotating cathode used in Comparative Example 4, to the electrolyte solution of 280 g/L of copper sulfate pentahydrate and 80 g/L of sulfuric acid, 20 mg/L of polyethylene glycol (molecular weight: 20,000) and polyethylene imine were added. 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, electrolysis was performed at a current density of 40 A/dm ² and a liquid temperature of 40° C. to produce an electrolytic copper foil with a thickness of 12 μm.

Each produced electrolytic copper foil was measured by the following method.

[Roughness]

Based on JISB0601, the glossy surface of each electrolytic copper foil 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 Kosaka Laboratory Co., Ltd.). The surface roughness Rzjis94.

[Specular gloss]

For each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 4 The specular glossiness of the glossy surface and the rough surface of the electrolytic copper foil obtained in Comparative Example 5 was based on JISZ8741, using a gloss meter GM-268 (manufactured by Konica Minolta Co., Ltd.), in both the TD direction and the MD direction. Specular gloss (Gs(60°)) at an incident angle of 60° was measured in each direction.

[Elongation after heat treatment]

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

[Number of bends]

From each of the electrolytic copper foils obtained in Examples 1 to 3 and Comparative Examples 1 to 5, test pieces of 1/2 inch in the width direction and 2 cm in the longitudinal direction were cut out and held at 200° C. for 10 minutes, and the rough surface side was used as the The inside is folded in half so that it is perpendicular to the longitudinal direction, and a load of 2 kg is placed on the folded part and held for 10 seconds. The number of times the sheet breaks completely.

[HAZE value]

Each electrolytic copper foil 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 electrolyte solution of 40 g/L of copper sulfate pentahydrate and 100 g/L of tetrasodium EDTA was prepared. After reaching pH 5.5, roughening treatment was performed under the electrolytic conditions of liquid temperature 35° C., current density 2 A/dm ² , and 25 seconds.

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

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

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

After washing with water for 5 seconds, the electrolytic copper foil subjected to the chromate gloss treatment was 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 Corporation), a double-sided two-layer copper-clad laminate was formed, and the double-sided electrolytic copper foil was etched, and then used HAZE METER NDH7000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.), the HAZE value was measured based on JIS K 7136.

Table 2 shows each measurement result.

〔Table 2〕

[Number of protrusions on the rough side]

The height of the rough surface of the electrolytic copper foil was measured with 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 For the quantification process, a threshold value was set in a scale 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 example. In addition, FIG. 1 shows the figures after the binarization processing of Example 1 and Comparative Example 1. As shown in FIG.

〔table 3〕

From Table 2 and Table 3, it was confirmed that the electrolytic copper foil of the present invention has high elongation after heat treatment, high bending resistance, flexibility, and very few abnormal protrusions on the rough surface side, and can be used as a copper clad laminate. In the case of , the HAZE value of the resin substrate exposed after etching is 80% or less.

Industrial Availability

The electrolytic copper foil of the present invention has high elongation and bending resistance after heat treatment, has flexibility, and is an electrolytic copper foil with very few abnormal protrusions on the rough surface side. The HAZE value of the resin base material is low, so it is an electrolytic copper foil that can be suitably used for flexible printed wiring boards.

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

Claims (8)

A treated copper foil of electrolytic copper foil for printed wiring boards, wherein one or more treated layers are provided on the glossy surface of electrolytic copper foil for printed wiring boards produced by continuous precipitation on the surface of a drum-shaped rotating cathode; wherein the aforementioned treatment The layer contains at least a roughening treatment layer; the specular gloss of the aforementioned glossy surface with an incident angle of 60° in the TD direction is 220 or less, and the sum of the specular gloss of the aforementioned glossy surface with an incidence angle of 60° in the TD and MD directions 350 or more; the glossy surface provided with the above-mentioned treatment layer is the bonding surface with the insulating resin substrate. The treated copper foil of the electrolytic copper foil for a printed wiring board according to claim 1, wherein the electrolytic copper foil for a printed wiring board having a thickness of 9 μm or more and 18 μm or less has an elongation of 21.6% or more after heating at 200° C. for 10 minutes. The processed copper foil of the electrolytic copper foil for printed wiring boards according to claim 1, wherein the rough surface of the electrolytic copper foil for printed wiring boards has no protrusions of 6.0 μm or more. The treated copper foil of the electrolytic copper foil for printed wiring boards according to claim 1, wherein the surface roughness Rz _JIS94 of the glossy surface is 1.5 μm or less. A copper-clad laminate formed by adhering an insulating resin base material to the glossy surface of the electrolytic copper foil for a printed wiring board of claim 1 on which the treatment layer is provided. A copper clad laminate, which is formed by pasting an electrolytic copper foil and an insulating resin base material, the electrolytic copper foil is produced by continuous precipitation on the surface of a drum-shaped rotating cathode; the TD direction of the glossy surface of the electrolytic copper foil is the incident The specular gloss at an angle of 60° is less than 220, and the sum of the specular gloss at an incident angle of 60° in the TD direction and the MD direction of the aforementioned glossy surface is more than 350; the copper clad laminate is attached to the aforementioned glossy surface. Made of insulating resin base. The copper clad laminate according to claim 6, wherein the haze value (HAZE value) is 80% or less. A printed wiring board formed using the copper clad laminate described in claim 6.

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