Method for manufacturing a wiring board

Abstract

To provide a manufacturing method of a wiring board that can suppress oxidation of a formed metal film.SOLUTION: A manufacturing method of a wiring board 1 includes a pressurizing step of pressurizing a base material 10 with a seed layer by a solid electrolyte membrane 22 in contact with a plating solution S, a film forming step of forming a metal film derived from metal ions contained in the solid electrolyte membrane 22 on a metal film formation area of the base material 10 with a seed layer by applying a voltage while the base material 10 with a seed layer is pressurized, and a cleaning step of cleaning the base material 10 with a seed layer after film formation. In the pressurizing step, before pressurizing the base material 10 with a seed layer with the solid electrolyte membrane 22, a liquid film 15 covering the metal film formation area is formed in advance on the surface of the base material 10 with a seed layer.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a wiring board, and more particularly to a method for manufacturing a wiring board using a solid phase electrodeposition method. [Background technology]

[0002] The solid-phase electrodeposition method is a method in which a workpiece is pressurized with a solid electrolyte film in contact with a plating solution containing metal ions, and a voltage is applied between the workpiece (anode) and the cathode, forming a metal film derived from the metal ions contained in the solid electrolyte film on the surface of the workpiece. A known method for manufacturing a wiring board using this solid-phase electrodeposition method is to form a wiring layer by depositing a metal film in a metal film formation area corresponding to a wiring pattern, as described in Patent Document 1 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-048210 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described method for manufacturing a wiring board, after a metal film is formed, the wiring board is transported to a cleaning process to clean off any remaining plating solution. However, while the wiring board is being transported to the cleaning process, the remaining plating solution remains on the surface of the formed metal film, and oxygen in the air diffuses into or dissolves in the plating solution. This can cause the formed metal film to oxidize and discolor.

[0005] The present invention has been made to solve such technical problems, and has an object to provide a method for manufacturing a wiring board that can suppress oxidation of the formed metal film. [Means for solving the problem]

[0006] The method for manufacturing a wiring board according to the present invention is a method for manufacturing a wiring board by forming a metal film on a metal film formation area of ​​a substrate by a solid-phase electrodeposition method, and includes a pressurizing step of pressurizing the substrate with a solid electrolyte film in contact with a plating solution, a film formation step of forming a metal film derived from metal ions contained in the solid electrolyte film on the metal film formation area by applying a voltage while the substrate is pressurized, and a cleaning step of cleaning the substrate after the film formation, wherein in the pressurizing step, a liquid film covering at least the metal film formation area is formed on the surface of the substrate before the substrate is pressed with the solid electrolyte film.

[0007] In the method for manufacturing a wiring board according to the present invention, a liquid film covering at least the area where the metal film is to be formed is formed on the surface of the substrate before the substrate is pressed with the solid electrolyte film, so that the entire metal film formed in the subsequent film-forming step is covered with the liquid film.The formed metal film is then covered with this liquid film while the substrate after film formation is transported to the cleaning step, so that oxidation of the formed metal film can be suppressed.

[0008] In the method for manufacturing a wiring board according to the present invention, it is preferable that the pressurizing step forms a continuous liquid film so as to cover the metal film formation area and a portion of the non-metal film formation area adjacent to the metal film formation area. The portion of the liquid film corresponding to the edge of the metal film is relatively thin, making oxidation more likely to occur at the edge. By forming a continuous liquid film so as to cover the metal film formation area and a portion of the non-metal film formation area adjacent to the metal film formation area, the portion of the liquid film corresponding to the edge of the metal film can be thickened, thereby reliably preventing oxidation of the edge of the metal film.

[0009] In the method for manufacturing a wiring board according to the present invention, it is preferable that in the pressurizing step, the liquid film is formed inside an annular damming portion removably provided on the peripheral edge portion of the base material, whereby outflow of the liquid in the liquid film can be prevented, thereby maintaining the shape of the liquid film. [Effects of the Invention]

[0010] According to the present invention, oxidation of the formed metal film can be suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] 5 is a flow chart for explaining a method for manufacturing a wiring substrate according to an embodiment. FIG. [Figure 2] FIG. 2 is a cross-sectional view showing the structure of a wiring board. [Figure 3] 1 is a cross-sectional view showing the structure of a film forming apparatus used in manufacturing a wiring substrate. [Figure 4] FIG. 10 is a cross-sectional view illustrating the formation of a liquid film. [Figure 5] FIG. 10 is a cross-sectional view illustrating a blocking portion. [Figure 6] 1A to 1C are cross-sectional views for explaining examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of a method for manufacturing a wiring board according to the present invention will be described with reference to the drawings. Before describing the method for manufacturing a wiring board, a brief description will be given of a wiring board 1 and a film forming apparatus 20 used in the manufacturing.

[0013] 2, wiring board 1 includes, for example, an insulating substrate 11 and a wiring layer 2 having a predetermined wiring pattern provided on the surface of insulating substrate 11. Wiring layer 2 includes a conductive base layer 12 formed on the surface of insulating substrate 11, a metal seed layer 13 formed on the surface of base layer 12, and a metal layer 14 formed on the surface of metal seed layer 13. However, wiring layer 2 is not limited to this, and may further include, for example, a diffusion layer formed between base layer 12 and metal seed layer 13.

[0014] The film formation apparatus 20 is a plating apparatus that uses solid-phase electrodeposition to form a metal layer 14 by depositing a metal film in a metal film formation area corresponding to a wiring pattern. As shown in Fig. 3, the film formation apparatus 20 includes a metal anode 21, a solid electrolyte film 22 disposed between the anode 21 and a metal seed layer 13 serving as a cathode, and a power supply unit 24 that applies a voltage between the anode 21 and the base layer 12. Because the base layer 12 and the metal seed layer 13 are conductive, applying a voltage between the anode 21 and the base layer 12 causes a current to flow between the anode 21 and the metal seed layer 13 during film formation.

[0015] The film forming apparatus 20 also includes a housing 23. The housing 23 contains an anode 21 and a plating solution S containing ions of a metal (e.g., Cu) that is the material of the metal layer 14. More specifically, a space for containing the plating solution S is formed between the anode 21 and the solid electrolyte membrane 22. The anode 21 has a plate shape, is disposed opposite the solid electrolyte membrane 22, and is built into the housing 23. The anode 21 may be either a soluble anode made of the same material as the metal layer 14 (e.g., Cu), or an anode made of a material insoluble in the plating solution S (e.g., Ti).

[0016] The solid electrolyte membrane 22 is also called a porous membrane or a porous resin membrane, and is formed of a resin membrane having a certain degree of flexibility. When the solid electrolyte membrane 22 is brought into contact with the plating solution S, it is impregnated (contains) metal ions contained in the plating solution S. When a voltage is applied, metal derived from the metal ions is deposited on the surface of the metal seed layer 13, which serves as the cathode. The thickness of the solid electrolyte membrane 22 is, for example, about 5 μm to about 200 μm.

[0017] The solid electrolyte membrane 22 is not particularly limited as long as it can be impregnated with metal ions by contacting with the plating solution S and can precipitate metal derived from the metal ions on the surface of the cathode (metal seed layer 13) when a voltage is applied. Examples of materials for the solid electrolyte membrane 22 include fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont, hydrocarbon-based resins, polyamic acid resins, and resins with cation exchange properties such as Selemion (CMV, CMD, CMF series) manufactured by Asahi Glass Co., Ltd.

[0018] The plating solution S is a solution containing the metal of the metal layer 14 in an ionic state, and examples of such metals include Cu, Ni, Ag, and Au. The plating solution S is prepared by dissolving (ionizing) these metals in an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, or pyrophosphoric acid.

[0019] Furthermore, the film forming apparatus 20 of this embodiment includes an elevator 25 that is disposed above the housing 23 and raises and lowers the housing 23. The elevator 25 may be any device that can raise and lower the housing 23, and may be configured, for example, by a hydraulic or pneumatic cylinder, an electric actuator, a linear guide, a motor, or the like.

[0020] The housing 23 is also provided with a supply port 23a through which the plating solution S is supplied and a discharge port 23b through which the plating solution S is discharged. The supply port 23a and the discharge port 23b are connected to a tank 31 via piping. The plating solution S is pumped from the tank 31 by a pump 32, flows into the housing 23 from the supply port 23a, and is discharged from the discharge port 23b and returned to the tank 31. A pressure regulating valve 33 is provided downstream of the discharge port 23b, and the plating solution S in the housing 23 can be pressurized to a predetermined pressure by the pressure regulating valve 33 and the pump 32.

[0021] The film forming apparatus 20 further includes a mounting table 26 on which a substrate 10 with a seed layer (described later) is placed. The mounting table 26 is made of a conductive material and is disposed below the housing 23 so that the substrate 10 with a seed layer placed thereon faces the solid electrolyte membrane 22. The mounting table 26 is electrically connected (conductive) to the negative electrode of the power supply unit 24. The positive electrode of the power supply unit 24 is electrically connected (conductive) to the anode 21 built into the housing 23.

[0022] A conductive member 27 is provided on the mounting table 26. The conductive member 27 is formed, for example, by bending a metal plate into a Z-shaped cross section. One end (the lower end in FIG. 3) of the conductive member 27 contacts the mounting table 26, and the other end (the upper end in FIG. 3) contacts the upper surface of the seed layer-equipped substrate 10 (i.e., the upper surface of the underlayer 12). This establishes electrical continuity between the mounting table 26 and the underlayer 12 via the conductive member 27. The conductive member 27 is detachable from the seed layer-equipped substrate 10.

[0023] The method for manufacturing a wiring substrate according to this embodiment will be described below. As shown in Figure 1, the method for manufacturing a wiring substrate according to this embodiment includes a preparation step S1, a pressure step S2, a film formation step S3, a liquid drainage step S4, a cleaning step S5, and a wiring layer formation step S6.

[0024] First, in the preparation step S1, a conductive underlayer 12 and a metal seed layer 13 corresponding to a predetermined wiring pattern are sequentially formed on the surface of an insulating substrate 11 to prepare a base material 10 with a seed layer. A well-known technique (for example, the technique disclosed in Patent Document 1) can be used as a method for sequentially forming the underlayer 12 and the metal seed layer 13 on the surface of the insulating substrate 11. A detailed description thereof will be omitted here.

[0025] The insulating substrate 11 is not particularly limited as long as it has insulating properties, but it is preferable to use, for example, a substrate made of glass epoxy resin, a substrate made of baked glass epoxy resin, a flexible film-like substrate such as polyimide resin, or a substrate made of glass.

[0026] The underlayer 12 is a layer for passing a current through the metal seed layer 13 when the metal layer 14 is formed. As shown in FIG. 3 , in the seed layer-attached substrate 10, the underlayer 12 is formed over the entire surface of the insulating substrate 11. The underlayer 12 is a layer containing an oxide. The oxide may be an oxide derived from the metal constituting the underlayer 12, or may be an oxide attached to the main body of the underlayer 12. This oxide prevents the metal derived from the metal layer 14 from depositing on the surface of the exposed portion 12a of the underlayer 12 (in other words, the portion of the surface of the underlayer 12 on which the metal seed layer 13 is not formed) even when the solid electrolyte membrane 22 comes into contact with the surface, in other words, the portion of the surface of the underlayer 12 on which the metal seed layer 13 is not formed) in the subsequent film-forming step S3. This allows the metal to be selectively deposited on the metal seed layer 13.

[0027] The metal seed layer 13 is formed to correspond to the wiring pattern of the wiring board 1, and is formed, for example, to have a plurality of independent wiring patterns. In the seed layer-attached substrate 10, the independent wiring patterns are electrically connected to each other via the underlayer 12. Therefore, in the film-forming step S3 described below, it is not necessary to form a lead wire for applying a voltage to each wiring pattern, and the metal layer 14 can be formed simultaneously on each wiring pattern. The metal seed layer 13 is, for example, at least one selected from the group consisting of silver, copper, gold, palladium, and platinum.

[0028] In the seed layer-attached substrate 10 having such a structure, the surface of the metal seed layer 13 having multiple wiring patterns is the area where a metal film is formed in the subsequent film-forming step S3, and is the metal film formation area of ​​the seed layer-attached substrate 10, which corresponds to the "metal film formation area of ​​the substrate" set forth in the claims. The remaining portions excluding the surface of the metal seed layer 13 having multiple wiring patterns (for example, the surface of the exposed portion 12a of the underlayer 12) are the non-metal film formation area of ​​the seed layer-attached substrate 10, which corresponds to the "non-metal film formation area of ​​the substrate" set forth in the claims.

[0029] In the pressurizing step S2 following the preparation step S1, the solid electrolyte membrane 22 in contact with the plating solution S is pressed against the seed layer-equipped substrate 10. Specifically, first, the seed layer-equipped substrate 10 is placed at a predetermined position on the mounting table 26, and the mounting table 26 and the upper surface of the underlayer 12 of the seed layer-equipped substrate 10 are electrically connected by the conductive member 27.

[0030] 4, a liquid film 15 is formed on the surface of the seed layer-attached substrate 10 to cover the area where the metal film is to be formed. Specifically, a liquid film 15 is formed on the surface of the underlayer 12 of the seed layer-attached substrate 10 to cover the metal seed layer 13. Covering the metal seed layer 13 means that not only the surface of the metal seed layer 13 but also all of the side surfaces of the metal seed layer 13 are covered with the liquid film 15.

[0031] At this time, it is preferable to form a continuous liquid film 15 so as to cover the metal film formation area and a part of the non-metal film formation area adjacent to the metal film formation area. Specifically, as shown in Fig. 4, the liquid film 15 is formed not only on the entire metal seed layer 13 constituting the wiring pattern, but also on a part of the surface of the exposed part 12a of the base layer 12 adjacent to the metal seed layer 13. The liquid film 15 is one continuous film.

[0032] The liquid film 15 can be made of plating solution S or pure water. The thickness of the liquid film 15, based on the surface of the base layer 12, is preferably in the range of 5 μm to the maximum thickness of the metal film to be formed, for the following reasons: If the liquid film 15 is thinner than 5 μm, the metal film may be oxidized due to drying before being washed. On the other hand, if the liquid film 15 exceeds the maximum thickness of the metal film to be formed, the concentration of the plating solution after film formation decreases, making it impossible to reuse the plating solution and resulting in an increase in the amount of diluted waste liquid.

[0033] Next, the lifting device 25 lowers the housing 23, bringing the solid electrolyte membrane 22 arranged at the lower end of the housing 23 into contact with the surface of the metal seed layer 13 of the seed layer-formed substrate 10 and the surface of the exposed portion 12a of the underlayer 12. Next, the pump 32 is driven to supply the plating solution S stored in the tank 31 to the housing 23. As a result, the plating solution S stored in the tank 31 flows into the housing 23 from the supply port 23a. Then, the liquid pressure of the plating solution S allows the solid electrolyte membrane 22 to uniformly pressurize the surface of the metal seed layer 13 and the surface of the exposed portion 12a of the underlayer 12. The applied pressure can be adjusted using, for example, a pressure regulating valve 33.

[0034] In the film-forming step S3 following the pressurizing step S2, a metal film is formed on the metal film formation area of ​​the seed layer-attached substrate 10 by applying a voltage while the seed layer-attached substrate 10 is pressurized by the solid electrolyte membrane 22. Specifically, a voltage is applied between the anode 21 and the underlayer 12 using the power supply unit 24, and metal ions contained in the solid electrolyte membrane 22 are reduced, resulting in the deposition of metal derived from the metal ions on the surface of the metal seed layer 13 (i.e., the metal film formation area). Furthermore, as a result of the application of the voltage, the metal ions of the plating solution S in the housing 23 continue to be reduced at the cathode, so that a metal film is formed on the surface of the metal seed layer 13. The formed metal film becomes the metal layer 14 described above.

[0035] Here, if the base layer 12 contains an oxide, such as a natural oxide film or an oxide film formed by surface treatment, on the surface of its exposed portion 12a (i.e., the non-metallic film formation area), as described above, the insulating properties of the surface of the exposed portion 12a are enhanced. Therefore, when the solid electrolyte film 22 is in close contact with the surface of the metal seed layer 13 and the surface of the exposed portion 12a of the base layer 12, current flows only through the surface of the metal seed layer 13. As a result, metal ions (e.g., Cu ions) contained in the solid electrolyte film 22 are reduced on the surface of the metal seed layer 13, and metal (e.g., Cu) is precipitated. As a result, metal precipitation on the surface of the exposed portion 12a of the base layer 12 is prevented, and the metal layer 14 is selectively formed on the surface of the metal seed layer 13. Note that the solid electrolyte film 22 may be in contact only with the metal seed layer 13. In this case, metal is not precipitated on the surface of the exposed portion 12a of the base layer 12, and the metal layer 14 is formed only on the surface of the metal seed layer 13.

[0036] In the draining process S4 following the film forming process S3, the plating solution S inside the housing 23 is discharged from the housing 23. Specifically, when the metal layer 14 is formed to a predetermined thickness, the voltage application between the anode 21 and the base layer 12 is terminated. Next, for example, compressed air is supplied into the housing 23, and the plating solution S inside the housing 23 is discharged from the discharge port 23b using the compressed air. The discharged plating solution S is returned to the tank 31. Next, the lifting device 25 raises the housing 23 to a predetermined height, and the solid electrolyte membrane 22 is separated from the seed layer-equipped substrate 10 on whose surface the metal film (i.e., the metal layer 14) is formed.

[0037] In the cleaning step S5 following the draining step S4, the seed layer-equipped substrate 10 after film formation is cleaned. Specifically, the seed layer-equipped substrate 10 on which the metal layer 14 has been formed is removed from the mounting table 26, transported to a water washing tank, and placed in the water washing tank for cleaning. After cleaning, the seed layer-equipped substrate 10 on which the metal layer 14 has been formed is dried.

[0038] In the wiring layer forming step S6 following the cleaning step S5, the exposed portion 12a of the base layer 12 exposed from the metal seed layer 13 is removed to form the wiring layer 2 on the surface of the insulating substrate 11. The method for removing the base layer 12 is not particularly limited, but may be, for example, plasma etching, sputtering, chemical etching, or the like.

[0039] By removing exposed portion 12a of base layer 12, as shown in Fig. 2, wiring layer 2 including, in this order, the portion of base layer 12 other than exposed portion 12a, metal seed layer 13, and metal layer 14 is formed on the surface of insulating substrate 11. In this way, wiring board 1 is manufactured.

[0040] According to the method for manufacturing a wiring board according to this embodiment, before the substrate 10 with the seed layer is pressed by the solid electrolyte film 22, a liquid film 15 covering the metal film formation area is formed in advance on the surface of the substrate 10 with the seed layer, so that the entire metal film (i.e., metal layer 14) formed in the subsequent film-forming step S3 is covered with the liquid film 15. Then, while the substrate 10 with the seed layer after film formation is transported to the cleaning step S5, the formed metal film is covered with this liquid film 15, so that oxidation of the formed metal film can be suppressed.

[0041] Furthermore, when forming the liquid film 15, a continuous liquid film 15 is formed so as to cover the metal film formation area and a portion of the non-metal film formation area adjacent to the metal film formation area. The portion of the liquid film 15 corresponding to the edge of the metal film is relatively thin, making it relatively easy for an oxidation reaction to occur at this edge. By forming a continuous liquid film 15 so as to cover the metal film formation area and a portion of the non-metal film formation area adjacent to the metal film formation area, the portion of the liquid film corresponding to the edge of the metal film can be made thicker, thereby reliably preventing oxidation of the edge of the metal film.

[0042] In order to maintain the shape of the liquid film 15, a removable blocking portion 16 may be provided on the peripheral edge of the seed layer-attached substrate 10, as shown in Fig. 5. The blocking portion 16 is formed in a ring shape using, for example, masking tape, a resist material, or a plating-resistant resin material. The height of the blocking portion 16 is 5 µm to 100 µm from the surface of the underlayer 12.

[0043] For example, in the pressurizing step S2, the seed layer-attached substrate 10 is placed on the mounting table 26, and then a ring-shaped damming portion 16 is formed by applying masking tape to the peripheral edge of the underlayer 12 so as to surround the liquid film 15 to be formed. Next, the liquid film 15 is formed inside the damming portion 16, for example, so as to fill the area surrounded by the damming portion 16. In this way, the damming portion 16 can prevent the liquid of the liquid film 15 from flowing out, so that the shape of the liquid film 15 can be maintained. Then, after the cleaning step S5 is completed, the damming portion 16 can be removed by peeling off the masking tape.

[0044] The present embodiment will be described below with reference to examples, but the present invention is not limited to these examples.

[0045] [Examples and Comparative Examples] In the examples and comparative examples, first, a Cu substrate having a thickness of 3 mm was prepared and pre-treated under the same conditions. The metal film area on the Cu substrate was 2 cm × 1 cm. 2 Next, the Cu substrate was subjected to cathodic electrolytic degreasing using an alkaline electrolytic cleaning solution (manufactured by JCU Corporation, product name IC-200RM) at 55°C for 1 minute, and then washed with pure water for 1 minute. Subsequently, the Cu substrate was further immersed in dilute sulfuric acid (concentration 10%) at room temperature for 1 minute, and then washed with pure water for 1 minute.

[0046] Next, without drying the Cu substrate, two types of liquid films were formed under pure water droplets as shown in Figures 6(a) and 6(b). Of Figures 6, Figure 6(a) shows the working example, and Figure 6(b) shows the comparative example. In Figures 6(a) and 6(b), the area between the two dashed lines shows the metal film formation area, and the areas on either side of that show the non-metal film formation area. In the comparative example shown in Figure 6(b), a blocking portion made of masking tape was provided around the periphery of the Cu substrate. On the other hand, in the working example shown in Figure 6(a), no blocking portion was provided.

[0047] Next, under pure water droplets, a continuous liquid film was formed on the surface of the Cu substrate of the example so as to cover the metal film formation area and a portion of the non-metal film formation area adjacent to the metal film formation area, and a liquid film smaller than the metal film formation area was formed on the surface of the Cu substrate of the comparative example.

[0048] Next, a 10 μm thick metal film was formed on each of the Cu substrates of the example and the comparative example by solid-phase electrodeposition. An oxygen-free copper plate was used as the anode, and a solution containing 1 mol / L copper sulfate and 0.2 mol / L sulfuric acid was used as the plating solution. The distance between the anode and cathode (i.e., the Cu substrate) was 2 mm, the film formation temperature was 70°C, the current was 100 mA, and the pressure was 1 kN.

[0049] The Cu substrates after film formation were then left at room temperature for a certain period of time and then washed with pure water. After washing, they were immediately dried with an air blower to prevent discoloration. Thereafter, the Cu substrates of the example and the comparative example were checked for discoloration (in other words, for the presence or absence of oxidation).

[0050] As a result, in the example, no discoloration was observed even after leaving the Cu substrate after film formation for 300 seconds. On the other hand, in the comparative example, discoloration occurred in the formed metal film after leaving it for 10 seconds. This is thought to be because the liquid film was formed smaller than the metal film formation area, and there were thin spots in the formed metal film, which caused the metal film to oxidize. Furthermore, it was shown that oxidation of the formed metal film can be prevented by forming a continuous liquid film so as to cover the metal film formation area and a part of the non-metal film formation area adjacent to the metal film formation area, as in the example.

[0051] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as set forth in the claims. [Explanation of symbols]

[0052] 1: wiring substrate, 10: base material with seed layer, 11: insulating substrate, 12: underlayer, 12a: exposed portion, 13: metal seed layer, 14: metal layer, 15: liquid film, 16: damming portion, 20: film forming device, 21: anode, 22: solid electrolyte film, 23: housing, 23a: supply port, 23b: discharge port, 24: power supply unit, 25: lifting device, 26: mounting table, 27: conductive member, 31: tank, 32: pump, 33: pressure regulating valve

Claims

[Claim 1] A method for manufacturing a wiring board by forming a metal film on a metal film formation area of ​​a substrate by a solid phase electrodeposition method, a pressurizing step of pressing the substrate with a solid electrolyte membrane in contact with a plating solution; a film formation step of forming a metal film derived from metal ions contained in the solid electrolyte film on the metal film formation area by applying a voltage while the base material is pressurized; a cleaning step of cleaning the substrate after film formation; Including, In the pressurizing step, before the substrate is pressed with the solid electrolyte membrane, a liquid film covering at least the metal coating formation area is formed on the surface of the substrate in advance; In the pressurizing step, a continuous liquid film is formed so as to cover the metal film formation area and a part of the non-metal film formation area adjacent to the metal film formation area; In the pressurizing step, the liquid film is formed inside an annular blocking portion removably provided on the peripheral edge of the substrate.

Images