TWI818380B - Copper-clad laminated boards and manufacturing methods of copper-clad laminated boards - Google Patents

Abstract

An object of the present invention is to provide a copper-clad laminated board and a method for manufacturing the copper-clad laminated board that can reduce the defective rate of wiring patterns formed by a semi-additive process. The solution of the present invention is a copper-clad laminate (1) having a conductor layer (20) including a copper-plated film (22) formed on the surface of a base film (10). The thickness of the conductor layer (20) is 0.4 to 3.0 μm, and the number of pinholes with a diameter of 5 μm or more is 0.04/cm ² or less. Using a plating device, while conveying the base material from roll to roll, a copper plated film (22) on the surface of the base material is formed by electrolytic plating to obtain a conductor layer (20) having a thickness of 0.4 to 3.0 μm. Copper clad laminate(1). The surface roughness Rmax of the conveyance surfaces of all rollers in contact with the plated surface of the base material in the plating device is 0.1 μm or less.

Description

Copper-clad laminated boards and manufacturing methods of copper-clad laminated boards

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

Electronic devices such as liquid crystal panels, notebook computers, digital cameras, and mobile phones use flexible printed wiring boards (FPCs) with wiring patterns formed on the surface of resin films. Semiconductor wafers 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 using a semi-additive process, a subtractive process, or the like. Especially 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 parts of the conductor layer of the copper-clad laminate are removed by etching. When the conductor layer is too thick, the etching time becomes longer and even the wiring portion is etched, making it difficult for the cross-sectional shape of the wiring to be rectangular. Therefore, the conductor layer of the copper-clad laminate processed by the semi-additive method is preferably a thin conductor layer. Therefore, as a copper-clad laminated board processed by a semi-additive method, a copper-clad laminated board having a conductor layer with a thickness of 0.2 to 3.0 μm is often used.

Chip-on-chip films are manufactured by sequentially processing copper-clad laminates by wiring pattern manufacturers and assembly manufacturers. The wiring pattern manufacturer forms a long strip-shaped flexible printed wiring board by arranging a plurality of wiring patterns that will become a plurality of single pieces on a long strip-shaped copper-clad laminate, and maintains the long strip shape. The flexible printed wiring board is sent to the assembly manufacturer. Here, among the plurality of wiring patterns, a defective mark is given to a wiring pattern in which defects such as disconnection or missing wiring occur. The assembler mounts the semiconductor wafers on each wiring pattern. At this time, when the defective rate of the flexible printed wiring board (the ratio of defective wiring patterns among the plurality of wiring patterns formed on the flexible printed wiring board) is high, the productivity of mounting decreases. Therefore, the allowable defective rate of wiring patterns is often specified for flexible printed wiring boards delivered to assembly manufacturers. Although specifications vary among assembly manufacturers, the allowable defective rate is mostly set at 30%. [Prior technical literature] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2010-108964

[Problem to be solved by the invention]

In view of the above circumstances, an object of the present invention is to provide a copper-clad laminated board and a method for manufacturing the copper-clad laminated board that can reduce the defective rate of wiring patterns formed by a semi-additive method. [Means used to solve problems]

The copper-clad laminated board of the present invention is characterized in that it has a conductor layer containing a copper-plated film formed on the surface of a base film, the thickness of the conductor layer is 0.4 to 3.0 μm, and the diameter of the conductor layer is 5 μm The number of pinholes above is 0.04/ ^cm2 or less. The manufacturing method of a copper-clad laminated board of the present invention is characterized by using a plating device to transport the base material from roll to roll and at the same time forming a copper-plated film on the surface of the base material by electrolytic plating to obtain a copper-plated film having When a copper-clad laminated board with a conductor layer having a thickness of 0.4 to 3.0 μm is obtained using a plating device, the conveying surfaces of all rollers in the plating device that are in contact with the plated surface of the base material The surface roughness Rmax is below 0.1μm. [Effects of the invention]

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

[Form used to implement 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 laminated board 1 according to an embodiment of the present invention is composed of a base film 10 and a conductor layer 20 formed directly on the surface of the base film 10 . The conductor layer 20 may be formed on only 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 or a liquid crystal polymer (LCP) film can be used. The conductor layer 20 is composed of a metal layer 21 directly formed on the base film 10 by a dry film formation method such as sputtering, and a copper plating film 22 directly formed on the metal layer 21 by electrolytic plating. A metal layer 21 and a copper-plated film 22 are laminated on the surface of the base film 10 in this order.

The metal layer 21 is composed of a base metal layer 21a and a copper thin film layer 21b. A base metal layer 21a and a copper thin film layer 21b are laminated on the surface of the base film 10 in this order. Typically, the base metal layer 21a is composed of nickel, chromium or nickel-chromium alloy. The base metal layer 21a may be omitted. 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 interposing the base metal layer 21a.

There is no particular limitation, but the thickness of the base film 10 is usually 10 to 100 μm. The thickness of the base metal layer 21a is usually 5~50nm, and the thickness of the copper thin film layer 21b is usually 50~400nm. In the case of the copper-clad laminate 1 processed by the semi-additive method, the thickness of the conductor layer 20 is usually 0.4~3.0 μm.

By processing the copper-clad laminated board 1 by the semi-additive method, a flexible printed wiring board can be manufactured. To manufacture flexible printed wiring boards by the semi-additive method, follow the following steps. First, a resist layer is formed on the surface of the copper plating film 22 of the copper-clad laminated board 1 . Next, an opening is formed in a portion of the resist layer where the wiring pattern is formed. Next, the copper-plated 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 is obtained.

Since the copper-plated film 22 of the copper-clad laminate 1 processed by the semi-additive method is thin, pinholes are easily generated when the copper-plated film 22 is formed by electrolytic plating. In the semi-additive method, copper plating in which a wiring pattern is laminated on the copper plating film 22 is performed by electrolytic plating. At this time, if there are pinholes in the copper plating film 22, the growth of the stacked copper plating will be hindered, and defects such as disconnection and missing wiring may occur. Especially when manufacturing a chip-on-chip film, it is necessary to form fine wiring with a wiring width of 15 μm or less, so wiring defects caused by pinholes are likely to occur.

The smaller the number of pinholes in the conductor layer 20 is, the less likely it is that wiring defects will occur, and the defective rate of wiring patterns can be suppressed. In the conductor layer 20 of the copper-clad laminated board 1 of this 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 conductor layer 20 has few pinholes, 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, a method for manufacturing a copper-clad laminated board according to one embodiment of the present invention will be described. The metal layer 21 can be formed on the surface of the long strip-shaped base film 10 using a roll-to-roll sputtering device. Hereinafter, the article in which the metal layer 21 is formed on the surface of the base film 10 is called a base material. The copper plating film 22 can be formed on the surface of a long strip-shaped base material using a roll-to-roll type plating apparatus. Thus, the long strip-shaped copper-clad laminated board 1 is obtained.

The plating device is a device that performs electrolytic plating on the base material while transporting the long strip-shaped base material from roll to roll. The plating device includes a supply device that feeds out the base material wound into a roll shape, and a winding device that winds the plated base material (copper-clad laminated board 1 ) into a roll shape. On the conveyance path between the supply device and the winding device, a pre-treatment tank, a plating tank, and a post-treatment tank are arranged. Electrolytic plating is performed in a plating bath. While the base material is transported into the plating bath, the copper plating film 22 is formed on the surface by electrolytic plating.

The copper plating liquid is stored in the plating tank. Copper plating solutions contain water-soluble copper salts. Any water-soluble copper salt commonly used in copper plating solutions 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 sulfate ion concentration of the copper plating solution can be adjusted. The copper plating solution may contain additives commonly added to plating solutions. As the additive, one selected from a brightener component, a leveling agent component, a polymer component, a chlorine component, etc. may be used alone, or two or more may be used in combination.

The content of each component of the copper plating solution can be selected arbitrarily. 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 made fine 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 plating 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 electric current on the edge portion of the base material can be alleviated and a uniform copper plating 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 liquid 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 toward the base material.

The thickness of the copper plating film 22 can be adjusted by the current density and plating time during 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 rollers for conveying the base material. Among the rollers included in the plating apparatus, the surface roughness (Rmax) of the conveying surface (the area on the outer peripheral surface of the roller that is in contact with the plated surface of the base material) is used as all the rollers in contact with the plated surface of the base material. It is a roller below 0.1μm. In this way, pinholes are less likely to occur when the copper plated film 22 is formed by electrolytic plating. Therefore, it is possible to manufacture the copper-clad laminated board 1 having the conductor layer 20 having a pinhole diameter of 5 μm or more and 0.04/cm ² or less. [Example]

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

A copper-plated film is formed on one side of the base material using a roll-to-roll plating device to obtain a copper-clad laminate. The copper plating liquid 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. Chlorine content of L. As a brightener component, bis(3-sulfopropyl) disulfide (reagent manufactured by RASCHIG GmbH) was used. As a leveling agent component, diallyldimethylammonium chloride-sulfur dioxide copolymer (manufactured by Nittobo Medical Co., Ltd., PAS-A-5) was used. As the polymer component, polyethylene glycol-polypropylene glycol copolymer (Unilube 50MB-11, manufactured by NOF Co., Ltd.) was used. As the chlorine component, hydrochloric acid (35% hydrochloric acid manufactured by Wako Pure Chemical Industries, Ltd.) was used.

(Example 1) Among the rollers included in the plating apparatus, rollers having a conveying surface surface roughness (Rmax) of 0.068 to 0.074 μm are used as all rollers that come into contact with the plated surface of the base material. 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 rollers included in the plating apparatus, rollers having a conveying surface surface roughness (Rmax) of 0.068 to 0.074 μm are used as all rollers that come into contact with the plated surface of the base material. 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 rollers included in the plating apparatus, rollers having a conveying surface surface roughness (Rmax) of 0.068 to 0.074 μm are used as all rollers that come into contact with the plated surface of the base material. 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 rollers included in the plating apparatus, rollers having a conveyance surface surface roughness (Rmax) of 4.003 to 4.218 μm are used as all rollers that come into contact with the plated surface of the base material. 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 rollers included in the plating apparatus, rollers having a conveyance surface surface roughness (Rmax) of 7.101 to 7.129 μm are used as all rollers that come into contact with the plated surface of the base material. The thickness of the copper plating film was adjusted so that the thickness of the conductor layer was 0.5 μm.

A 250×160 mm sample was cut out from each of the copper-clad laminated boards obtained in Examples 1 to 3 and Comparative Examples 1 and 2. Use backlighting with a halogen lamp as the light source to inspect each sample and count the number of pinholes with a diameter of 5 μm or more. A visual inspection was performed while comparing it with a previously prepared sample of a pinhole having a diameter of 5 μm. The results are shown in Table 1.

In Examples 1 to 3 using rollers with a surface roughness (Rmax) of 0.068 to 0.074 μm, the number of pinholes was all 0.04/cm ² or less. On the other hand, in Comparative Examples 1 and 2 using rollers with 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 in both cases. From this, it was confirmed that when a roller with a surface roughness (Rmax) of 0.1 μm or less is used, a copper-clad laminated board having a conductor layer with a pinhole diameter of 5 μm or more and 0.04/cm ² or less can be manufactured.

Next, each of the copper-clad laminated boards obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was processed to produce a flexible printed wiring board. Follow the steps below to manufacture a flexible printed wiring board. 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 is approximately 70×40mm, the minimum pitch is 20μm, and the wiring width is 10μm. 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 of the copper plating and 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. Wiring patterns with defects or disconnections that are one-third or more of the wiring width are determined to be defective, and the defective rate of the wiring patterns is calculated. 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/cm ² or less, the defective 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 pinholes/cm ² and 0.10 pinholes/cm ² , the defective rates exceeded 30%. From this, it was confirmed that when the number of pinholes in the conductor layer is 0.04/cm ² or less, the defective rate of the wiring pattern formed by the semi-additive method is 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/cm ^or less, the defective rate can be less than 27%. When the number of pinholes is 0.02/cm ^or less, the defective rate can be less than 21%. When the number of pinholes is 0.01/ ^cm2 or less, the defective rate can be less than 18%.

[Table 1] Roller surface roughness (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: Basement membrane 20: Conductor layer 21:Metal layer 21a: Base metal layer 21b: Copper film layer 22: Copper coating

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

1: Copper clad laminate

10: Basement membrane

20: Conductor layer

21:Metal layer

21a: Base metal layer

21b: Copper film layer

22: Copper coating

Claims (2)

A copper-clad laminate, characterized in that the copper-clad laminate has a conductor layer directly formed on the surface of a base film, and the conductor layer has: a metal layer directly formed on the base film by a dry film forming method. , and a copper-plated film directly formed on the metal layer by electrolytic plating, the thickness of the conductor layer is 0.4~3.0μm, and the number of pinholes in the conductor layer with a diameter of 5μm or more is 0.01/ ^cm2 or less. A method for manufacturing a copper-clad laminated board, characterized by using a plating device to transport a base material in which a metal layer is formed on a surface of a base film by roll-to-roll roll-to-roll transport, and at the same time forming the base material by electrolytic plating. The copper-plated film on the surface of the material is used to obtain a copper-clad laminate having a conductor layer with a thickness of 0.4 to 3.0 μm and a pinhole diameter of 5 μm or more and a pinhole count of 0.01/cm ^or less, and the copper-clad laminate is obtained using the plating device. When the plate is used, the surface roughness Rmax of the conveying surfaces of all the rollers in contact with the plated surface of the base material in the plating device is 0.1 μm or less, and the conductor layer is directly formed on the surface of the base film, and the conductor layer The layer includes a metal layer directly formed on the base film by a dry film forming method, and a copper plating film directly formed on the metal layer by electrolytic plating.