TW202226909A - Copper clad laminate and method for producing copper clad laminate capable of reducing the defect rate of a wiring pattern formed by a semi-additive method - Google Patents

Abstract

An object of the present invention is to provide a copper clad laminate and a method for producing the copper clad laminate which can reduce the defect rate of a wiring pattern formed by a semi-additive process. The copper-clad laminate (1) of the present invention has a conductor layer (20) containing a copper-plated film (22) and formed on the surface of the base film (10). The thickness of the conductor layer (20) is 0.4 to 3.0 [mu]m, and the number of pinholes having a diameter of 5 [mu]m or more is 0.04 pieces/cm 2 or less. By using a plating apparatus, a copper-plated film (22) on the surface of the base material is formed by electrolytic plating while the base material is conveyed by roll-to-roll, and a copper-clad laminate (1) having a conductor layer (20) with a thickness of 0.4 to 3.0 [mu]m is obtained. The surface roughness Rmax of the conveyance surfaces of all the rollers in contact with the plated surfaces of the substrate in the plating apparatus is 0.1 [mu]m or less.

Description

Copper clad laminate and manufacturing method of copper clad laminate

The present invention relates to a copper-clad laminate and a manufacturing method of the copper-clad laminate. More specifically, the present invention relates to a copper clad laminate used for the manufacture of flexible printed wiring boards, chip clad films, and the like, and a method of manufacturing the copper clad laminate.

In electronic devices such as liquid crystal panels, notebook computers, digital cameras, and mobile phones, flexible printed wiring boards (FPCs) in which wiring patterns are formed on the surface of resin films are used, and semiconductor chips are mounted on the flexible printed wiring boards. chip-on-film (COF).

A flexible printed wiring board is obtained by forming a wiring pattern on a copper-clad laminate by a semi-additive process, a subtractive process, or the like. In particular, when the formation of fine wiring and high-precision wiring size are required, the semi-additive method is used (for example, Patent Document 1).

In the semi-additive method, unnecessary portions of the conductor layers of the copper clad laminate are removed by etching. When the conductor layer is too thick, the etching time becomes long, and the wiring portion is also etched, so that the cross-sectional shape of the wiring becomes difficult to be rectangular. Therefore, the conductor layer of the copper clad laminate processed by the semi-additive method is preferably a thinner conductor layer. Therefore, as a copper clad laminate processed by a semi-additive method, a copper clad laminate having a conductor layer having a thickness of 0.2 to 3.0 μm is often used.

The chip on film is manufactured by sequentially processing the copper clad laminate by the wiring pattern maker and the assembler. The wiring pattern manufacturer forms a long strip-shaped flexible printed wiring board in a state where the long strip-shaped copper-clad laminate will be formed into a plurality of single-piece wiring patterns, and will maintain the long strip-shaped flexible printed wiring board. The flexible printed wiring board is sent to the assembler. Here, among the plurality of wiring patterns, a mark indicating a defect is attached to a wiring pattern in which a defect such as a disconnection or a chipping of the wiring occurs. The assembler mounts the semiconductor wafer on each wiring pattern. At this time, when the defective rate of the flexible printed wiring board (the ratio of defective wiring patterns among a plurality of wiring patterns formed on the flexible printed wiring board) is high, the productivity of the mounting decreases. Therefore, many flexible printed wiring boards delivered to assemblers specify the allowable defect rate of the wiring pattern. Although specifications vary by assembler, the allowable defect rate is generally set at 30%. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2010-108964

[The problem to be solved by the invention]

In view of the above-mentioned circumstances, the present invention aims to provide a copper clad laminate and a method for producing the copper clad laminate which can reduce the defective rate of a wiring pattern formed by a semi-additive method. [means to solve the problem]

The copper-clad laminate of the present invention is characterized in that it has a conductor layer containing a copper-plated film formed on the surface of the base film, the conductor layer has a thickness of 0.4 to 3.0 μm, and the conductor layer has a diameter of 5 μm. The above pinholes are 0.04 pieces/cm ² or less. The method for producing a copper-clad laminate of the present invention is characterized by forming a copper-plated film on the surface of the base material by electrolytic plating while conveying the base material by roll-to-roll using a plating apparatus to obtain a A copper-clad laminate having a conductor layer having a thickness of 0.4 to 3.0 μm, when a copper-clad laminate is obtained using a plating apparatus, the conveying surfaces of all the rollers in contact with the plating surface of the base material in the plating apparatus The surface roughness Rmax is 0.1 μm or less. [Effect of invention]

In the copper-clad laminate of the present invention, since the number of pinholes having a diameter of 5 μm or more in the conductor layer is 0.04/cm ² or less, the defect rate of the wiring pattern formed by the semi-additive method can be suppressed to 30% the following. According to the method for producing a copper-clad laminate of the present invention, a copper-clad laminate having a conductor layer with pinholes having a diameter of 5 μm or more and a conductor layer of 0.04 pieces/cm ² or less can be produced.

[Form for carrying out the invention]

Next, embodiments of the present invention will be described based on the drawings. (Copper Clad Laminate) As shown in FIG. 1 , a copper-clad laminate 1 according to an embodiment of the present invention includes a base film 10 and a conductor layer 20 formed on the surface of the base film 10 . The conductor layer 20 may be formed only on one side of the base film 10 as shown in FIG. 1 , or the conductor layer 20 may be formed on both sides of the base film 10 .

As the base film 10, a resin film such as a polyimide film and a liquid crystal polymer (LCP) film can be used. The conductor layer 20 is composed of a metal layer 21 formed by a dry film-forming method such as sputtering, and a copper-plated film 22 formed by electrolytic plating. On the surface of the base film 10 , the metal layer 21 and the copper plating film 22 are stacked in this order.

The metal layer 21 is composed of a base metal layer 21a and a copper thin film layer 21b. The base metal layer 21 a and the copper thin film layer 21 b are laminated in this order on the surface of the base film 10 . Typically, the base metal layer 21a is composed of nickel, chromium, or nichrome. There may be no base metal layer 21a. The copper thin film layer 21b may be formed on the surface of the base film 10 via the base metal layer 21a, or may be directly formed on the surface of the base film 10 without the base metal layer 21a.

Although not particularly limited, the thickness of the base film 10 is usually 10 to 100 μm. The thickness of the base metal layer 21a is usually 5 to 50 nm, and the thickness of the copper thin film layer 21b is usually 50 to 400 nm. In the case of the copper-clad laminate 1 processed by the semi-additive method, the thickness of the conductor layer 20 is usually 0.4 to 3.0 μm.

By processing the copper-clad laminate 1 by the semi-additive method, a flexible printed wiring board can be produced. Manufacturing a flexible printed wiring board by a semi-additive method is performed according to the following procedure. First, a resist layer is formed on the surface of the copper-plated film 22 of the copper-clad laminate 1 . Next, openings are formed in portions of the resist layer where the wiring patterns are formed. Next, the copper plating film 22 exposed from the opening of the resist layer is electrolytically plated as a cathode, thereby forming a wiring portion. Next, the resist layer is removed, and the conductor layer 20 other than the wiring portion is removed by flash etching or the like. Thus, a flexible printed wiring board was obtained.

Since the copper-plated film 22 of the copper-clad laminate 1 processed by the semi-additive method is thin, pinholes are likely to be generated when the copper-plated film 22 is formed by electrolytic plating. In the semi-additive method, copper plating of the wiring pattern is laminated on the copper plating film 22 by electrolytic plating. At this time, if there are pinholes in the copper plating film 22, the growth of the laminated copper plating is inhibited, and defects such as disconnection and chipping of the wiring may occur. In particular, in the case of manufacturing a chip-on-film, since it is necessary to form fine wiring with a wiring width of 15 μm or less, wiring defects due to pinholes tend to occur.

The smaller the number of pinholes in the conductor layer 20, the less likely it is to cause defects in the wiring, and the defect rate of the wiring pattern can be suppressed. In the conductor layer 20 of the copper-clad laminate 1 of the present embodiment, the number of pinholes having a diameter of 5 μm or more is 0.04/cm ² or less. In this way, since the number of pinholes in the conductor layer 20 is small, the defective rate of the wiring pattern formed by the semi-additive method can be suppressed to 30% or less.

(Manufacturing method of copper clad laminate) Next, the manufacturing method of the copper clad laminated board which concerns on one Embodiment of this invention is demonstrated. Using a roll-to-roll sputtering apparatus, the metal layer 21 can be formed on the surface of the long strip-shaped base film 10 . Hereinafter, the article in which the metal layer 21 is formed on the surface of the base film 10 is referred to as a base material. The copper plating film 22 can be formed on the surface of the long strip-shaped base material by using the plating apparatus of the roll-to-roll method. Thereby, the long strip-shaped copper-clad laminate 1 is obtained.

The plating apparatus is an apparatus for electroplating the base material while conveying the long strip-shaped base material by roll-to-roll. The plating apparatus has a supply device that sends out the base material wound in a roll shape, and a winding device that winds the plated base material (copper clad laminate 1 ) into a roll shape. A pre-processing tank, a plating tank, and a post-processing tank are arranged on the conveyance path between the supply device and the coiling device. Electrolytic plating is performed in a plating tank. The copper plating film 22 is formed on the surface of the base material by electrolytic plating while the base material is conveyed into the plating tank.

The copper plating solution is stored in the plating tank. The copper plating solution contains a water-soluble copper salt. As long as it is a water-soluble copper salt generally used for a copper plating solution, it can be used without particular limitation. The copper plating solution may contain sulfuric acid. By adjusting the amount of sulfuric acid added, the pH and sulfuric acid ion concentration of the copper plating solution can be adjusted. The copper plating solution may contain additives that are usually added to the plating solution. As an additive, 1 type selected from a brightener component, a leveler component, a polymer component, a chlorine component, etc. may be used individually, and 2 or more types may be used together.

The content of each component of the copper plating solution can be arbitrarily selected. However, the copper plating solution preferably contains 15 to 70 g/L of copper and 20 to 250 g/L of sulfuric acid. In this way, the copper plating film 22 can be formed at a sufficient speed. The copper plating solution preferably contains a brightener component of 1 to 50 mg/L. In this way, the precipitated crystals can be refined and the surface of the copper plating film 22 can be smoothed. The copper plating solution preferably contains a leveling agent component of 1 to 300 mg/L. In this way, the protrusions can be suppressed and the flat copper-plated film 22 can be formed. The copper plating solution preferably contains a polymer component of 10 to 1500 mg/L. In this way, the concentration of the current to the end of the base material can be alleviated, and the uniform copper-plated film 22 can be formed. The copper plating solution preferably contains a chlorine component of 20 to 80 mg/L. In this way, abnormal precipitation can be suppressed.

The temperature of the copper plating solution is preferably 20 to 35°C. In addition, it is preferable to stir the copper plating liquid in the plating tank. For example, the copper plating liquid can be stirred by spraying the copper plating liquid discharged from the nozzle to the base material.

The thickness of the copper plating film 22 can be adjusted by the current density and the plating time in electrolytic plating. For example, the thickness of the copper plating film 22 is adjusted so that the thickness of the conductor layer 20 is 0.4 to 3.0 μm.

The plating apparatus has various rolls for conveying the base material. Among the rolls included in the plating apparatus, the surface roughness (Rmax) of the conveyance surface (region in contact with the plating surface of the base material in the outer peripheral surface of the roll) was used as all the rolls in contact with the plating surface of the base material. A roll of 0.1 μm or less. In this way, pinholes are less likely to be generated when the copper-plated film 22 is formed by electrolytic plating. Therefore, it is possible to manufacture the copper-clad laminate 1 having the conductor layers 20 with pinholes of 5 μm or more in diameter and 0.04 pieces/cm ² or less. [Example]

(common conditions) As the base film, a strip-shaped polyimide film (manufactured by Ube Industries, Ltd., Upilex) having a width of 570 mm and a thickness of 34 μm was prepared. The base film was set in a magnetron sputtering apparatus. A nickel-chromium alloy target and a copper target are set in the magnetron sputtering device. The composition of the nichrome target was 20 mass % of Cr and 80 mass % of Ni. In a vacuum environment, a base metal layer composed of a nickel-chromium alloy with a thickness of 25 nm was formed on one side of the base film, and a copper thin film layer with a thickness of 100 nm was formed thereon.

A copper-plated film was formed on one side of the substrate using a roll-to-roll plating apparatus to obtain a copper-clad laminate. The copper plating solution stored in the plating tank contains 120g/L copper sulfate, 70g/L sulfuric acid, 16mg/L brightener component, 20mg/L leveler component, 1100mg/L polymer component and 50mg/L The chlorine content of L. As a brightener component, bis(3-sulfopropyl)disulfide (a reagent manufactured by RASCHIG GmbH) was used. As a leveler component, a diallyldimethylammonium chloride-sulfur dioxide copolymer (manufactured by Nittobo Medical Co., Ltd., PAS-A-5) was used. As a polymer component, a polyethylene glycol-polypropylene glycol copolymer (manufactured by NOF Corporation, Unilube 50MB-11) was used. As the chlorine component, hydrochloric acid (35% hydrochloric acid manufactured by Wako Pure Chemical Industries, Ltd.) was used.

(Example 1) Among the rolls included in the plating apparatus, as all the rolls in contact with the plating surface of the substrate, a roll having a surface roughness (Rmax) of a conveying surface of 0.068 to 0.074 μm was used. The thickness of the copper plating film was adjusted so that the thickness of the conductor layer was 0.4 μm.

(Example 2) Among the rolls included in the plating apparatus, as all the rolls in contact with the plating surface of the substrate, a roll having a surface roughness (Rmax) of a conveying surface of 0.068 to 0.074 μm was used. The thickness of the copper plating film was adjusted so that the thickness of the conductor layer was 2.0 μm.

(Example 3) Among the rolls included in the plating apparatus, as all the rolls in contact with the plating surface of the substrate, a roll having a surface roughness (Rmax) of a conveying surface of 0.068 to 0.074 μm was used. The thickness of the copper plating film was adjusted so that the thickness of the conductor layer was 3.0 μm.

(Comparative Example 1) Among the rolls included in the plating apparatus, as all the rolls in contact with the plating surface of the substrate, a roll having a surface roughness (Rmax) of a conveying surface of 4.003 to 4.218 μm was used. The thickness of the copper plating film was adjusted so that the thickness of the conductor layer was 3.0 μm.

(Comparative Example 2) Among the rolls included in the plating apparatus, as all the rolls in contact with the plating surface of the substrate, a roll having a surface roughness (Rmax) of a conveying surface of 7.101 to 7.129 μm was used. The thickness of the copper plating film was adjusted so that the thickness of the conductor layer was 0.5 μm.

Samples of 250×160 mm were cut out from the copper-clad laminates obtained in Examples 1 to 3 and Comparative Examples 1 and 2. Each sample was examined using backlight illumination using a halogen lamp as a light source, and the number of pinholes having a diameter of 5 μm or more was counted. Visual inspection was performed while comparing with a sample with a pinhole of 5 μm in diameter prepared in advance. The results are shown in Table 1.

In Examples 1 to 3 using a roller having a surface roughness (Rmax) of 0.068 to 0.074 μm, the number of pinholes was all 0.04 pieces/cm ² or less. On the other hand, in Comparative Examples 1 and 2 using a roller having a surface roughness (Rmax) of 4.003 to 4.218 μm or 7.101 to 7.129 μm, the number of pinholes exceeded 0.04/cm ² . From this, it was confirmed that a copper-clad laminate having a conductor layer having a pinhole diameter of 5 μm or more and a conductor layer of 0.04/cm ² or less can be produced when a roller having a surface roughness (Rmax) of 0.1 μm or less is used.

Next, each copper-clad laminate obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was processed to manufacture a flexible printed wiring board. Manufacture of a flexible printed wiring board is performed according to the following procedure. A dry film resist is laminated on the surface of the copper-plated film of the copper-clad laminate to form a resist mask in which a plurality of wiring patterns are arranged. The size of each wiring pattern was about 70×40 mm, the minimum pitch was 20 μm, and the wiring width was 10 μm. Next, the copper plating film exposed from the opening of the resist mask was electrolytically plated as a cathode, and the copper plating was laminated so that the total thickness with the conductor layer of the copper-clad laminate was 8 μm.

The laminated copper plating (wiring pattern) exposed from the opening of the resist mask was observed with a microscope. A wiring pattern with a size of not less than one third of the wiring width or a disconnection was judged to be defective, and the defective rate of the wiring pattern was obtained. The results are shown in Table 1.

It was confirmed that in Examples 1 to 3 in which the number of pinholes in the conductor layer was 0.04 pieces/cm ² or less, the defect rates were all 30% or less, which was within the allowable range. On the other hand, in Comparative Examples 1 and 2 in which the number of pinholes in the conductor layer was 0.07 pieces/cm ² and 0.10 pieces/cm ² , the defective rate exceeded 30%. From this, it was confirmed that when the number of pinholes in the conductor layer was 0.04 pieces/cm ² or less, the defective rate of the wiring pattern formed by the semi-additive method was 30% or less.

In addition, it can be seen from Table 1 that the smaller the number of pinholes in the conductor layer, the lower the defective rate of the wiring pattern. When the number of pinholes is 0.04 pieces/cm ² or less, the defective rate can be 27% or less. When the number of pinholes is 0.02 pieces/cm ² or less, the defective rate can be 21% or less. When the number of pinholes is 0.01/cm ² or less, the defective rate can be 18% or less.

[Table 1] Surface roughness of roll (Rmax) [μm] Conductor layer thickness [μm] Number of pinholes [pieces/cm ² ] Defective rate [%] Example 1 0.068～0.074 0.4 0.04 27 Example 2 2.0 0.02 twenty one Example 3 3.0 0.01 18 Comparative Example 1 4.003～4.218 2.0 0.10 39 Comparative Example 2 7.101～7.129 0.5 0.07 33

1: Copper clad laminate 10: base film 20: Conductor layer 21: Metal layer 21a: base metal layer 21b: Copper thin film layer 22: Copper coating film

1 is a cross-sectional view of a copper clad laminate according to an embodiment of the present invention.

1: Copper clad laminate

10: base film

20: Conductor layer

21: Metal layer

21a: base metal layer

21b: Copper thin film layer

22: Copper coating film

Claims (4)

A copper-clad laminate, characterized in that the copper-clad laminate has a conductor layer formed on a surface of a base film containing a copper-plated film, the conductor layer has a thickness of 0.4 to 3.0 μm, and the conductor layer has a diameter of 5 μm The above pinholes are 0.04 pieces/cm ² or less. The copper-clad laminate according to claim 1, wherein the number of pinholes with a diameter of 5 μm or more in the conductor layer is 0.02/cm ² or less. The copper-clad laminate according to claim 2, wherein the number of pinholes with a diameter of 5 μm or more in the conductor layer is 0.01/cm ² or less. A method for manufacturing a copper-clad laminate, characterized in that: A copper-clad laminate having a conductor layer having a thickness of 0.4 to 3.0 μm was obtained by forming a copper-plated film on the surface of the base material by electrolytic plating while conveying the base material by roll-to-roll using a plating apparatus, When the copper-clad laminate is obtained using the plating apparatus, the surface roughness Rmax of the conveyance surfaces of all the rolls in contact with the plating surface of the substrate in the plating apparatus is 0.1 μm or less.

Images