Method for manufacturing copper-clad laminate

Abstract

To provide a method for manufacturing a copper-clad laminate capable of thickening the copper-plated film at the other end even if the copper-plated film is formed by supplying power only from one end of a base material.SOLUTION: The method for manufacturing a copper-clad laminate comprises a dry film formation step in which a metal thin film layer 21 is formed only in a main region A1 excluding a non-film formation region A2, which is the region of a first width from a second edge E of a base film 10, by a dry film formation method to obtain a base material 11, an electrolytic plating step in which a copper-plated film 24 is formed on the main region A1 by electrolytic plating, by supplying power only from the end of the first edge E1 side of the base material 11, to obtain a copper-clad laminate intermediate product 12, and a cutting step in which a removal region A3, which is the region of a second width from a second edge E2 of the copper-clad laminate intermediate product 12, is cut and removed to obtain a copper-clad laminate final product.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for producing a copper-clad laminate. More specifically, the present invention relates to a method for producing a copper-clad laminate that is particularly suitable for producing flexible printed circuit boards (FPCs) by a semi-additive process. [Background technology]

[0002] Flexible printed wiring boards, in which wiring patterns are formed on the surface of a resin film, are used in electronic devices such as liquid crystal panels, notebook computers, digital cameras, and mobile phones. Flexible printed wiring boards are manufactured from copper-clad laminates, in which copper foil is laminated on a resin film.

[0003] The metallizing method is known as a method for manufacturing copper-clad laminates. The manufacture of copper-clad laminates by the metallizing method is carried out, for example, in the following procedure. First, a base metal layer and a thin copper layer are formed on the surface of a resin film by a dry film formation method. Next, a copper plating film is formed on the thin copper layer by an electrolytic plating method. The conductor layer is thickened by electrolytic plating until it has a thickness suitable for forming a wiring pattern. The metallizing method produces a type of copper-clad laminate in which a conductor layer is formed directly on a resin film, so-called a two-layer board.

[0004] Regarding the formation of a copper plating film, Patent Document 1 discloses an electrolytic plating apparatus that performs electrolytic plating on a long strip-shaped substrate while transporting the substrate by roll-to-roll. This electrolytic plating apparatus has a pair of upper and lower endless belts to which multiple clamps are attached. The substrate is suspended with its width direction aligned vertically, and is transported while its upper and lower ends are held by the upper and lower clamps. The upper clamp also functions as a power supply terminal. In a plating tank, power is supplied to the substrate only from the upper clamp, and a copper plating film is formed on the surface of the substrate.

[0005] Flexible printed wiring boards are obtained by forming wiring patterns on copper-clad laminates by semi-additive methods, subtractive methods, etc. In particular, the semi-additive method is used when the formation of fine wiring or highly accurate wiring dimensions is required.

[0006] The manufacturing of flexible printed wiring boards using the semi-additive method is carried out in the following procedure. First, a resist layer is formed on the surface of the conductor layer of the copper-clad laminate. Next, openings are formed in the resist layer in the areas where the wiring pattern is to be formed. Next, electrode terminals are connected to the ends of the conductor layer and electrolytic plating is performed, and a plating layer is laminated on the areas of the conductor layer exposed from the openings in the resist layer. Next, the resist layer is removed, and the conductor layer other than the wiring areas is removed by flash etching or the like. This results in a flexible printed wiring board.

[0007] In the semi-additive process, unnecessary parts of the conductor layer of the copper-clad laminate are removed by etching. If the conductor layer is too thick, the etching time will be long and the etching of the wiring portion will also progress, making it difficult to make the cross-sectional shape of the wiring rectangular. Therefore, from the viewpoint of making the cross-sectional shape of the wiring rectangular, it is preferable that the conductor layer of the copper-clad laminate is thin.

[0008] However, if the conductor layer is thin, problems may occur when forming wiring parts by electrolytic plating. That is, if the conductor layer to which the electrode terminal is connected is thin, it is difficult to pass a sufficient current because of high electrical resistance. In addition, the part of the conductor layer that contacts the electrode terminal may become high voltage, causing dissolution or abnormal deposition of the conductor layer, which may cause an interruption in the current supply. To prevent such problems, it is necessary to lower the current, but if the current is too low, productivity will decrease.

[0009] Therefore, the thickness of the copper plating film of the copper-clad laminate is set as thin as possible so that no problems arise when forming wiring portions by electrolytic plating in the semi-additive process. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2020-105579 A Summary of the Invention [Problem to be solved by the invention]

[0011] However, it is difficult to form a copper plating film with a uniform thickness over the entire substrate. In the electrolytic plating apparatus disclosed in Patent Document 1, power is supplied only from the upper end of the substrate, so the copper plating film gradually becomes thinner from the upper edge to the lower edge. As a result, the lower end of the copper plating film becomes thinner than the other parts.

[0012] When a copper-clad laminate having such a copper plating film is cut lengthwise in the center of its width with a slitter to produce two products, the product that was placed on the top during electrolytic plating will have a thicker copper plating film at one end (the upper end during electrolytic plating). If an electrode terminal is connected to this thicker end during wiring formation using the semi-additive method, a relatively high current can be supplied. On the other hand, the product that was placed on the bottom during electrolytic plating will have a thinner copper plating film at one end (the lower end during electrolytic plating). If an electrode terminal is connected to this thinner end during wiring formation using the semi-additive method, the current must be lowered to prevent dissolution of the conductor layer.

[0013] In this way, if the copper plating film at the end farthest from the power supply terminal during electrolytic plating is thin, problems arise such as the need to adjust plating conditions in the manufacturing process for flexible printed wiring boards.

[0014] In view of the above circumstances, the present invention aims to provide a method for manufacturing a copper-clad laminate that can thicken the copper plating film at one end of a substrate even if power is supplied to the other end of the substrate to form a copper plating film. [Means for solving the problem]

[0015] The method for manufacturing a copper-clad laminate of the present invention is characterized by comprising: a dry film formation process in which a long, strip-shaped base film having a first edge and a second edge along the longitudinal direction is transported by a roll-to-roll method, and a metal thin film layer is formed only in a main region excluding a non-film-formed region, which is a region of a first width from the second edge of the base film, to obtain a base material; an electrolytic plating process in which, while transporting the base material by a roll-to-roll method, power is supplied only from the end portion of the base material on the first edge side, and a copper plating film is formed in the main region by electrolytic plating to obtain a copper-clad laminate intermediate product; and a cutting process in which a removal region, which is a region of a second width wider than the first width from the second edge of the copper-clad laminate intermediate product, is cut and removed to obtain a final copper-clad laminate product. Effect of the Invention

[0016] According to the present invention, even if a copper plating film is formed by supplying power only to the end portion on the first edge side of the substrate, the portion of the copper plating film formed in the main region adjacent to the non-film-formed region becomes thicker due to current concentration, and a final copper-clad laminate can be obtained with the end portion having the thick copper plating film. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a partially enlarged cross-sectional view of a copper-clad laminate according to one embodiment. [Diagram 2] Figure (A) is a plan view of the base film, and Figure (B) is a cross-sectional view of the same base film. [Diagram 3] FIG. 2 is an explanatory diagram showing a manufacturing procedure of a copper-clad laminate. [Figure 4] Fig. 1A is an explanatory diagram of a sputtering device, and Fig. 1B is an explanatory diagram of the positional relationship with the shielding plate in the width direction of the base film. [Diagram 5] FIG. 1 is a perspective view of an electrolytic plating apparatus. [Figure 6] Figure (A) is a graph showing the thickness of the copper plating film over the entire width of the final copper-clad laminate obtained in Example 1. Figure (B) is a graph showing the thickness of the copper plating film at one end of the final copper-clad laminate. [Figure 7]Figure (A) is a graph showing the thickness of the copper plating film over the entire width of the final copper-clad laminate obtained in Comparative Example 1. Figure (B) is a graph showing the thickness of the copper plating film at one end of the final copper-clad laminate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Next, an embodiment of the present invention will be described with reference to the drawings. (Copper-clad laminate) As shown in Fig. 1, a copper-clad laminate 1 produced by a method according to one embodiment of the present invention comprises a base film 10 and a conductor layer 20 formed on the surface of the base film 10. In the example shown in Fig. 1, the conductor layer 20 is formed on both sides of the base film 10. However, the conductor layer 20 may be formed on only one side of the base film 10.

[0019] The base film 10 may be a resin film such as a polyimide film or a liquid crystal polymer (LCP) film.

[0020] The conductor layer 20 has a metal thin film layer 21 formed by a dry film formation method. The metal thin film layer 21 is composed of an underlying metal layer 22 and a copper thin film layer 23. The underlying metal layer 22 and the copper thin film layer 23 are laminated in this order on the surface of the base film 10. In general, the underlying metal layer 22 is composed of nickel, chromium, or a nickel-chromium alloy. The underlying metal layer 22 may be omitted. The copper thin film layer 23 may be formed on the surface of the base film 10 via the underlying metal layer 22, or may be formed directly on the surface of the base film 10 without the underlying metal layer 22.

[0021] The conductor layer 20 has a copper plating film 24 formed by electrolytic plating. The metal thin film layer 21 and the copper plating film 24 are laminated in this order on the surface of the base film 10.

[0022] Although not particularly limited, the thickness of the base film 10 is generally 10 to 100 μm. The thickness of the underlying metal layer 22 is generally 5 to 50 nm, and the thickness of the copper thin film layer 23 is generally 50 to 400 nm. In the case of a copper-clad laminate 1 processed by a semi-additive method, the thickness of the copper plating film 24 is generally 0.1 to 5 μm.

[0023] (Manufacturing method) Next, a method for producing the copper clad laminate 1 according to one embodiment of the present invention will be described. As shown in Figures 2(A) and (B), a long strip-shaped base film 10 is used to manufacture a copper-clad laminate 1. The base film 10 has two edges along the longitudinal direction. Hereinafter, one edge of the base film 10 is referred to as a first edge E1, and the other edge is referred to as a second edge E2. In this specification, an "edge" refers to a part located around or on the boundary of an object, and is a concept without width. Also, an "end" refers to an area of ​​a specified width from an edge.

[0024] The main surface of the base film 10 has a main region A1 and a non-film-formed region A2. As described below, the conductor layer 20 is formed only in the main region A1, and is not formed in the non-film-formed region A2. The main region A1 is a strip-shaped region along the longitudinal direction including a first edge E1. The non-film-formed region A2 is a strip-shaped region along the longitudinal direction including a second edge E2. The main region A1 and the non-film-formed region A2 are adjacent to each other. Therefore, the region of the main surface of the base film 10 excluding the non-film-formed region A2 is the main region A1.

[0025] Although not particularly limited, the width of the base film 10 is generally 550 to 600 mm. The width of the non-film-forming area A2 is defined as a first width W1. The first width W1 is preferably 1 to 3% of the width of the base film 10, or 4 to 15 mm.

[0026] As shown in FIG. 3, in this embodiment, a copper-clad laminate 1 is manufactured by carrying out (1) a dry film formation step, (2) an electrolytic plating step, and (3) a cutting step in this order.

[0027] (1)Dry film formation process In the dry film formation step, a metal thin film layer 21 is formed on the surface of the base film 10 by a dry film formation method. Hereinafter, the base film 10 on which the metal thin film layer 21 is formed is referred to as a substrate 11. Examples of dry film formation methods include sputtering, vacuum deposition, and ion plating. Among these, sputtering is preferred. The metal thin film layer 21 may be formed on both sides of the base film 10, or only on one side. The metal thin film layer 21 is formed over the entire main region A1 of the base film 10. Moreover, the metal thin film layer 21 is formed only in the main region A1, and is not formed in the non-film formation region A2.

[0028] By using a roll-to-roll type dry film forming apparatus, the metal thin film layer 21 can be continuously formed on the surface of the base film 10 while the long strip-shaped base film 10 is transported by roll-to-roll.

[0029] 4(A) shows an example of a sputtering apparatus 3. The illustrated sputtering apparatus 3 is an apparatus that transports a long strip-shaped coated article D1 by roll-to-roll and continuously produces a coated article D2 by forming a film on one side of the coated article D1 by sputtering. If the coated article D1 is a base film 10, the coated article D2 is a substrate 11 having a metal thin film layer 21 formed on one side.

[0030] The sputtering device 3 has a vacuum chamber 30. An unwinding section 31 and a winding section 33 are arranged inside the vacuum chamber 30. The unwinding section 31 unwinds the film-coated product D1 from a film-coated product roll in which the film-coated product D1 is wound in a roll shape. The winding section 33 winds up the film-coated product D2 to form a film-coated product roll.

[0031] The film-formed product D1 is transported from the unwinding section 31 to the winding section 33. Inside the vacuum chamber 30, various rolls are provided that define the transport path of the film-formed product D1. Examples of such rolls include a free roll, a tension sensor roll, and a feed roll. The film-formed product D1 is wound around these rolls and transported. In addition, a can roll 32 is arranged on the transport path of the film-formed product D1.

[0032] A plurality of sputtering cathodes 41-44 (four in the example shown in FIG. 4) are provided along the transport path of the film-formed article D1 at positions facing the outer circumferential surface of the can roll 32. A target (film-formation material) is attached to each of the sputtering cathodes 41-44 on the surface facing the outer circumferential surface of the can roll 32. Sputtered particles slammed off from the target are deposited on the surface of the film-formed article D1, thereby forming a film.

[0033] A target of a metal or alloy having the same composition as the underlying metal layer 22 is attached to the sputtering cathode 41 disposed at the most upstream side of the transport path. When depositing the underlying metal layer 22 of a nickel-chromium alloy, a nickel-chromium alloy target is used.

[0034] Copper targets are attached to sputtering cathodes 42 to 44, which are arranged downstream of the most upstream sputtering cathode 41. The copper thin film layer 23 can be formed by using these targets.

[0035] A shielding plate 45 is provided between each of the sputtering cathodes 41-44 and the can roll 32. The shielding plate 45 prevents the scattering of sputtered particles into the non-film-forming area A2. A metal plate material that can withstand the heat during sputtering can be used as the shielding plate 45. If a plate material such as stainless steel is used as the shielding plate 45, the metal deposited on the shielding plate 45 can be dissolved by chemical treatment and reused.

[0036] 4(B), the shielding plate 45 has a width dimension equal to or wider than that of the non-film-forming region A2, and is disposed at a position facing the non-film-forming region A2. In this manner, by disposing the shielding plate 45 between the non-film-forming region A2 of the base film 10 and the film-forming material, it is possible to inhibit the formation of the metal thin film layer 21 in the non-film-forming region A2, and it is possible to form the metal thin film layer 21 only in the main region A1.

[0037] A two-stage operation is sufficient to form the metal thin film layer 21 on both sides of the base film 10 using a sputtering apparatus 3 of a single-sided film formation type as shown in Fig. 4(A). That is, first, the base film 10 is set in the sputtering apparatus 3 as the film-formed article D1, and the metal thin film layer 21 is formed on one side of the base film 10. The intermediate product thus obtained is set again in the sputtering apparatus 3 as the film-formed article D1, and the metal thin film layer 21 is formed on the other side of the base film 10. If a double-sided film formation type sputtering apparatus is used, the metal thin film layer 21 can be formed on both sides of the base film 10 in a single operation.

[0038] (2) Electrolytic plating process 3(2), in the electrolytic plating step, a copper plating film 24 is formed on the surface of the substrate 11 by electrolytic plating. Hereinafter, the substrate 11 having the copper plating film 24 formed on its surface is referred to as a copper-clad laminate intermediate product 12. The copper plating film 24 may be formed on both sides of the substrate 11, or only on one side. The copper plating film 24 is formed only on the main region A1 of the substrate 11, and is not formed on the non-film-formation region A2.

[0039] By using a roll-to-roll electrolytic plating apparatus, the copper plating film 24 can be continuously formed on the surface of the long strip of the substrate 11 while the substrate 11 is transported by roll-to-roll. This results in a long strip of the copper-clad laminate intermediate product 12.

[0040] 5 shows an example of an electrolytic plating apparatus 5. The illustrated electrolytic plating apparatus 5 is an apparatus that performs electrolytic plating on a long strip-shaped substrate 11 while transporting the substrate 11 by roll-to-roll.

[0041] The electrolytic plating apparatus 5 has a supplying device 51 that pays out the substrate 11 wound in a roll, and a winding device 52 that winds up the plated product (copper-clad laminate intermediate product 12) in a roll. The electrolytic plating apparatus 5 also has a pair of upper and lower endless belts 53A, 53B that transport the substrate 11. The endless belts 53A, 53B rotate along a path defined by various rollers. The endless belts 53A, 53B are provided with a plurality of clamps 54A, 54B that grip the substrate 11, respectively.

[0042] The base material 11 fed from the supply device 51 is suspended with its width direction aligned vertically, and both ends are held by upper and lower clamps 54A and 54B. The upper end of the base material 11 is held by the upper clamp 54A with a first edge E1 as the upper edge, and the lower end is held by the lower clamp 54B with a second edge E2 as the lower edge.

[0043] The substrate 11 is transported by the endless belts 53A and 53B and travels around the electrolytic plating apparatus 5. After that, the substrate 11 is released from the clamps 54A and 54B and taken up by the take-up device 52.

[0044] A pre-treatment tank 55, a plating tank 56, and a post-treatment tank 57 are arranged on the transport path of the substrate 11. While the substrate 11 is transported through the plating tank 56, a copper plating film 24 is formed on the surface of the substrate 11 by electrolytic plating. In this way, a long strip-shaped copper-clad laminate intermediate product 12 is obtained.

[0045] The plating tank 56 is a single tank that is long horizontally along the transport direction of the substrate 11. A copper plating solution is stored in the plating tank 56. The substrate 11 transported in the plating tank 56 is entirely immersed in the copper plating solution.

[0046] The copper plating solution contains a water-soluble copper salt. Any water-soluble copper salt that is generally used in copper plating solutions may be used without any particular limitation. The copper plating solution may contain sulfuric acid. The pH and sulfate ion concentration of the copper plating solution can be adjusted by adjusting the amount of sulfuric acid added. The copper plating solution may contain additives that are generally added to plating solutions. As the additive, one selected from a brightener component, a leveler component, a polymer component, a chlorine component, etc. may be used alone, or two or more types may be used in combination.

[0047] The content of each component in 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 24 can be formed at a sufficient speed. The copper plating solution preferably contains 1 to 50 mg / L of a brightener component. In this way, the precipitated crystals can be made fine and the surface of the copper plating film 24 can be made smooth. The copper plating solution preferably contains 1 to 300 mg / L of a leveller component. In this way, protrusions can be suppressed and a flat copper plating film 24 can be formed. The copper plating solution preferably contains 10 to 1,500 mg / L of a polymer component. In this way, current concentration on the end of the substrate 11 can be alleviated and a relatively uniform copper plating film 24 can be formed. The copper plating solution preferably contains 20 to 80 mg / L of a chlorine component. In this way, abnormal deposition can be suppressed.

[0048] The temperature of the copper plating solution is preferably 20 to 35° C. In addition, it is preferable to stir the copper plating solution in plating tank 56. For example, the copper plating solution can be stirred by spraying the copper plating solution from a nozzle onto substrate 11.

[0049] An anode is disposed inside the plating tank 56 at a position facing the substrate 11. The upper clamp 54A that holds the substrate 11 also functions as a power supply terminal that supplies current to the substrate 11. By passing a current between the substrate 11 and the anode, a copper plating film 24 can be formed on the surface of the substrate 11. The lower clamp 54B does not function as a power supply terminal. Therefore, power is supplied to the substrate 11 only from the end on the first edge E1 (upper edge) side.

[0050] If a plating layer is formed on the edge of the substrate 11, the plating may peel off from the edge. Therefore, a shielding plate may be used to suppress the formation of the copper plating film 24 on the end of the substrate 11. The shielding plate is disposed between the end of the substrate 11 and the anode. The shielding plate is an insulating plate. There are no particular limitations on the material of the shielding plate, but resins, ceramics, and the like that have insulating properties and are not easily corroded by the copper plating solution are suitable.

[0051] Electricity is supplied to the substrate 11 only from the end portion on the first edge E1 (upper edge) side, and the copper plating film 24 is formed. Therefore, as shown in Fig. 3 (2), the copper plating film 24 tends to be thicker near the first edge E1 than at the center portion in the width direction. In this embodiment, the metal thin film layer 21 is not formed on the end portion (non-film-formed region A2) on the second edge E2 side of the base film 10, so that the portion of the copper plating film 24 formed on the main region A1 adjacent to the non-film-formed region A2 becomes thicker due to current concentration.

[0052] That is, generally, the copper plating film 24 tends to be thinner in the portion farther from the power supply terminal. However, because the edge of the plated surface is located away from the second edge E2, current is concentrated near this edge. This current concentration can thicken the copper plating film 24. Therefore, the copper plating film 24 formed in the main region A1 is thicker at both ends than at the center.

[0053] (3) Cutting process 3(3) and (4), in the cutting process, the intermediate copper-clad laminate 12 is cut in the longitudinal direction by a slitter to obtain the final copper-clad laminate 1. In this specification, the final copper-clad laminate 1 is synonymous with the copper-clad laminate 1.

[0054] The region of the copper-clad laminate intermediate product 12 from the second edge E2 to the second width W2 is defined as the removal region A3. The removal region A3 is wider than the non-film-formed region A2. That is, the second width W2 is wider than the first width W1. In order to remove the non-film-formed region A2 and leave the portion of the main region A1 where the copper plating film 24 has become thicker, it is preferable that the second width W2 is 10 to 20 mm wider than the first width W1. In the cutting process, at least the removal region A3 is cut and removed. By cutting and removing the removal region A3, the non-film-formed region A2 is also removed, and the portion where the copper plating film 24 has become thicker due to current concentration becomes the end of the final copper-clad laminate product 1.

[0055] Usually, the end of the copper-clad laminate intermediate product 12 on the first edge E1 side is also cut and removed. This end includes the portion where the upper clamp 54A was in contact. In addition, if a shielding plate is provided in the plating tank 56, this end also includes the portion where the formation of the copper plating film 24 is suppressed by the shielding plate. Therefore, by cutting and removing the end on the first edge E1 side, a copper-clad laminate final product 1 without these influences can be obtained. The copper plating film 24 tends to be thicker in the vicinity of the first edge E1 to which the power supply terminal is connected. The new end that appears after the end on the first edge E1 side is cut and removed also has a thick copper plating film 24. The width dimensions of both ends of the copper-clad laminate intermediate product 12 (one end is the removal area A3) may be the same or different.

[0056] The intermediate copper-clad laminate 12 may be cut longitudinally at the center in the width direction to obtain two final copper-clad laminates 1, 1. Hereinafter, the final copper-clad laminate 1 that is closer to the power supply terminal (placed on the upper side) during electrolytic plating will be referred to as copper-clad laminate 1A, and the final copper-clad laminate 1 that is farther from the power supply terminal (placed on the lower side) during electrolytic plating will be referred to as copper-clad laminate 1B.

[0057] As shown in Fig. 3(4), the copper-clad laminate 1A has a thicker copper-plated coating 24 at one end. Furthermore, of the ends of the copper-clad laminate 1B, end A4, which was adjacent to the removal area A3, has a thicker copper-plated coating 24 than the other parts. This is because end A4 contains a portion where the copper-plated coating 24 has become thicker due to current concentration in the electrolytic plating. Thus, in both copper-clad laminates 1A and 1B, one end of the copper-plated coating 24 is thicker than the other parts.

[0058] It is not necessary to cut the copper-clad laminate intermediate product 12 in the longitudinal direction at the center in the width direction. In this case, the copper plating film 24 of the copper-clad laminate 1 is thicker at both ends than at the center.

[0059] (Manufacture of flexible printed circuit boards) A flexible printed wiring board can be manufactured by processing the copper-clad laminate 1 by the semi-additive method. In the semi-additive method, electrode terminals are connected to the ends of the copper-clad laminate 1, and electrolytic plating is performed to laminate a plating layer on the conductor layer 20. In the copper-clad laminate 1 obtained in this embodiment, the ends of the conductor layer 20 are thicker than other parts, so that the electrical resistance is not high and a sufficient current can flow. In addition, the parts in contact with the electrode terminals are unlikely to become high voltage, and current supply abnormalities such as dissolution and abnormal precipitation of the conductor layer 20 are unlikely to occur.

[0060] In electrolytic plating in the semi-additive method, an electrode terminal is usually connected to an end of the copper-clad laminate 1, in a region about 5 mm wide. If the conductor layer 20 in this region is thin, dissolution or abnormal deposition occurs in the portion in contact with the electrode terminal. However, in the copper-clad laminate 1 obtained in this embodiment, even the end A4 far from the power supply terminal during electrolytic plating in the manufacturing process has a thicker copper plating film 24 than other portions. For example, the average thickness of the end A4 (5 mm wide) of the copper plating film 24 is 105 to 115% of the average thickness of the entire width. If an electrode terminal is connected to this end A4 when forming wiring by the semi-additive method, a relatively high current can be supplied. EXAMPLES

[0061] Example 1 A polyimide film (Upilex-35SGAV1 manufactured by Ube Industries) having a thickness of 35 μm, a width of 570 mm, and a length of 800 m was prepared as the base film 10. The base film 10 was set in a magnetron sputtering device. A nickel-chromium alloy target and a copper target were installed in the magnetron sputtering device. The composition of the nickel-chromium alloy target was 20 mass % Cr and 80 mass % Ni. Under a vacuum atmosphere, a base metal layer 22 made of a nickel-chromium alloy having a thickness of 25 nm was formed on both sides of the base film 10, and a copper thin film layer 23 having a thickness of 100 nm was formed thereon.

[0062] Here, a stainless steel shielding plate was provided between each target and the base film 10, and the base metal layer 22 and the copper thin film layer 23 were formed only in the main region A1 of the base film 10, and not in the non-film-formation region A2. The width of the main region A1 was 560 mm, and the width of the non-film-formation region A2 was 10 mm.

[0063] Next, a copper plating film 24 was formed on both sides of the substrate 11 using an electrolytic plating apparatus 5 shown in FIG. 5 to obtain a copper-clad laminate intermediate product 12. The substrate 11 was suspended with its width direction aligned vertically, and both ends were held by upper and lower clamps 54A and 54B. The substrate 11 was held at its upper end by the upper clamp 54A with the first edge E1 as the upper edge, and at its lower end by the lower clamp 54B with the second edge E2 as the lower edge. Electricity was supplied only from the end of the substrate 11 on the first edge E1 side to perform electrolytic plating. The current density and the transport speed of the substrate 11 were set so that the set thickness of the copper plating film 24 was 2.1 μm.

[0064] The copper plating solution stored in the plating tank contains 120g / L copper sulfate, 70g / L sulfuric acid, 16mg / L brightener, 20mg / L leveler, 1,100mg / L polymer, and 50mg / L chlorine. Bis(3-sulfopropyl)disulfide (a reagent manufactured by RASCHIG GmbH) was used as the brightener. Diallyldimethylammonium chloride-sulfur dioxide copolymer (PAS-A-5 manufactured by Nittobo Medical Co., Ltd.) was used as the leveler. Polyethylene glycol-polypropylene glycol copolymer (UNILUBE 50MB-11 manufactured by NOF Corporation) was used as the polymer. Hydrochloric acid (35% hydrochloric acid manufactured by Wako Pure Chemical Industries, Ltd.) was used as the chlorine.

[0065] Both ends (25 mm on each side, 50 mm in total) of the obtained intermediate copper-clad laminate 12 were cut and removed with a slitter to obtain a final copper-clad laminate 1 having a width of 520 mm.

[0066] The thickness of the copper plating film 24 on both sides of the final copper-clad laminate 1 was measured. One side of the final copper-clad laminate 1 is called the first side, and the other side is called the second side. A fluorescent X-ray thickness gauge was used for the measurements. The results are shown in Figures 6(A) and (B). The horizontal axis of the graphs in Figures 6(A) and (B) indicates the position in the width direction of the final copper-clad laminate 1. 0 mm is the edge that was located on the upper side in the electrolytic plating, and 520 mm is the edge that was located on the lower side in the electrolytic plating. The vertical axis indicates the thickness of the copper plating film 24. Figure 6(A) shows the entire width (0 to 520 mm) of the final copper-clad laminate 1, and Figure 6(B) shows the end portion at 400 to 520 mm.

[0067] As can be seen from FIG. 6(A), both ends of the copper plating film 24 are thicker than the center. Also, both ends of the copper plating film 24 are about the same thickness. In particular, as can be seen from FIG. 6(B), the copper plating film 24 is thicker even at the end that was far from the power supply terminal during electrolytic plating than the center. Specifically, the average thickness of the end (515-520 mm) of the copper plating film 24 on the first surface is 108% of the average thickness of the entire width (0-520 mm). Also, the average thickness of the end (515-520 mm) of the copper plating film 24 on the second surface is 109% of the average thickness of the entire width (0-520 mm).

[0068] Comparative Example 1 A substrate was prepared in the same manner as in Example 1. However, no shielding plate was provided between the target and base film 10, and a base metal layer 22 and a copper thin film layer 23 were formed on the entire surfaces of the base film 10. In addition, electrolytic plating was performed under the same conditions as in Example 1, and a copper plating film 24 was formed on the entire surfaces of the substrate. Both ends (25 mm on each side, 50 mm in total) of the obtained intermediate copper-clad laminate were cut and removed with a slitter to obtain a final copper-clad laminate with a width of 520 mm.

[0069] The thickness of the copper plating film 24 on both sides of the final copper-clad laminate was measured. One side of the final copper-clad laminate was called the first side, and the other side was called the second side. The results are shown in Figs. 7(A) and 7(B). As can be seen from Fig. 7(A), the copper plating film 24 gradually becomes thinner from the upper edge to the lower edge during electrolytic plating. In particular, as can be seen from Fig. 7(B), the copper plating film 24 becomes particularly thin at the end that was far from the power supply terminal during electrolytic plating. Specifically, the average thickness of the end (515-520 mm) of the copper plating film 24 on the first side was 93% of the average thickness of the entire width (0-520 mm). Moreover, the average thickness of the end (515-520 mm) of the copper plating film 24 on the second side was 97% of the average thickness of the entire width (0-520 mm).

[0070] From the above, it was confirmed that if the metal thin film layer 21 is formed only on the main region A1 of the base film 10, the copper plating film 24 at the end portion farther from the power supply terminal can be made thicker. [Explanation of symbols]

[0071] 1 Copper-clad laminate 10 Base film 20 Conductor layer 21 Metal thin film layer 22 Undercoat metal layer 23 Copper thin film layer 24 Copper plating film 11 Base material 12 Copper-clad laminate intermediate product E1 First Edge E2 Second Edge A1 Main area A2 Non-film forming area A3 removal area

Claims

1. a dry film-forming process in which a long strip-shaped base film having a first edge and a second edge along a longitudinal direction is transported by a roll-to-roll method, and a metal thin film layer is formed only in a main region of the base film, excluding a non-film-formed region that is a region of a first width from the second edge, by a dry film-forming method, to obtain a substrate; an electrolytic plating process in which, while transporting the base material by a roll-to-roll method, power is supplied only from an end portion of the base material on the first edge side to form a copper plating film on the main region by electrolytic plating to obtain a copper-clad laminate intermediate product; a cutting process for cutting and removing a removal region, which is a region having a second width wider than the first width, from the second edge of the intermediate copper-clad laminate to obtain a final copper-clad laminate. A method for producing a copper-clad laminate comprising the steps of:

2. The second width is 10 to 20 mm wider than the first width. The method for producing a copper-clad laminate according to claim 1 .

3. The first width is 1 to 3% of the width dimension of the base film, or 4 to 15 mm. The method for producing a copper-clad laminate according to claim 1 .

4. In the dry film-forming step, a shielding plate is disposed between the non-film-forming area of ​​the base film and a film-forming material to inhibit the formation of the metal thin film layer in the non-film-forming area. The method for producing a copper-clad laminate according to claim 1 .

5. In the cutting step, the intermediate copper-clad laminate is cut at the center in the width direction to obtain two final copper-clad laminates. The method for producing a copper-clad laminate according to claim 1 .

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