JP7746966B2 - Wiring board manufacturing apparatus and manufacturing method - Google Patents

Description

The present invention relates to a wiring board manufacturing apparatus and manufacturing method, and in particular to a wiring board manufacturing apparatus and manufacturing method using solid-phase electrodeposition.

Solid-phase electrodeposition is a method in which a voltage is applied between the anode and cathode of the workpiece while the workpiece is pressurized with a solid electrolyte film in contact with a plating solution containing metal ions, and a metal film derived from the metal ions contained in the solid electrolyte film is formed on the surface of the workpiece. A known method for manufacturing wiring boards 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 the wiring pattern, as described in Patent Document 1 below, for example.

Japanese Patent Application Laid-Open No. 2021-048210

In the above-mentioned wiring board manufacturing method, after the metal film is formed, the wiring board is transported to a cleaning process to wash away any plating solution remaining on the wiring board. 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 this plating solution. This can cause the formed metal film to oxidize and discolor.

The present invention was made to solve these technical problems, and aims to provide a wiring board manufacturing device and manufacturing method that can suppress oxidation of the formed metal film.

The wiring board manufacturing apparatus of the present invention manufactures wiring boards by forming a metal film on the surface of a substrate using a solid-phase electrodeposition method. It includes: an anode; a solid electrolyte membrane disposed between the anode and the substrate (which serves as a cathode); a mounting table disposed opposite the solid electrolyte membrane and having a substrate mounting area on which the substrate is mounted; a container containing the anode and plating solution, the opening of which facing the mounting table is blocked by the solid electrolyte membrane; and a power supply unit that applies voltage between the anode and the substrate. Outside the substrate mounting area of the mounting table, a nozzle is provided for forming a liquid film on the surface of the substrate that covers the formed metal film and a portion of the surface of the substrate adjacent to the metal film. An annular damming unit that dams up the liquid film is provided outside the substrate mounting area of the mounting table, closer to the substrate than the nozzle, or on the peripheral edge of the substrate being mounted.

In the wiring board manufacturing device according to the present invention, a nozzle is provided outside the substrate placement area of the placement table for forming a liquid film on the surface of the substrate that covers the formed metal film and a portion of the substrate surface adjacent to the metal film. By using the nozzle to form a liquid film that covers the formed metal film, the entire formed metal film is covered with the liquid film. Therefore, the formed metal film is covered with this liquid film until the substrate is cleaned after film formation, thereby suppressing oxidation of the formed metal film. Furthermore, an annular damming portion that blocks the liquid film is provided outside the substrate placement area of the placement table, closer to the substrate than the nozzle, or on the peripheral edge of the placed substrate. This damming portion prevents the liquid film from flowing out, maintaining the shape of the liquid film. This reliably suppresses oxidation of the formed metal film.

In the wiring board manufacturing apparatus according to the present invention, it is preferable that a plurality of the nozzles are provided surrounding the substrate placement area of the placement table, and each nozzle is inclined toward the center of the substrate placement area. In this way, by using a plurality of nozzles provided surrounding the substrate placement area to supply solution to the substrate and form a liquid film, the time required to form the liquid film can be shortened compared to, for example, when the nozzles supply solution to the substrate from only one direction, and the pressure of the supplied solution can be reduced, thereby reducing damage to the formed metal coating. Furthermore, because each nozzle is inclined toward the center of the substrate placement area, the solution supplied from the nozzles is prevented from directly hitting the solid electrolyte film, thereby minimizing damage to the solid electrolyte film.

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 the surface of a substrate by solid-phase electrodeposition, and includes the following steps: a pressurizing step in which, with the opening of a container sealed with a solid electrolyte film, the solid electrolyte film is brought into contact with the substrate placed on a mounting table facing the solid electrolyte film, and then a plating solution is supplied to the container and the substrate is pressed with the solid electrolyte film in contact with the plating solution; a film forming step in which, while the substrate is pressurized, a metal film derived from metal ions contained in the solid electrolyte film is formed on the surface of the substrate by applying a voltage; a separating step in which the plating solution is discharged from the container and the solid electrolyte film is separated from the substrate; a liquid film forming step in which a liquid film is formed on the surface of the substrate, covering the formed metal film and a portion of the surface of the substrate adjacent to the metal film; and a cleaning step in which the substrate on which the liquid film has been formed is removed from the mounting table and cleaned.

In the wiring board manufacturing method according to the present invention, after film formation, the solid electrolyte film is separated from the substrate, and a liquid film is formed on the surface of the substrate, covering the formed metal film and a portion of the surface of the substrate adjacent to the metal film. This results in the entire formed metal film being covered by the liquid film. Therefore, the formed metal film is covered by this liquid film until the substrate is washed after film formation, thereby preventing oxidation of the formed metal film.

The present invention makes it possible to suppress oxidation of the formed metal coating.

1 is a cross-sectional view showing the structure of a wiring substrate manufacturing apparatus according to an embodiment. FIG. 2 is a schematic plan view showing a mounting table and a substrate with a seed layer mounted thereon. FIG. 10 is a cross-sectional view illustrating the formation of a liquid film. FIG. 2 is a cross-sectional view showing the structure of a wiring board. 5 is a flow chart for explaining a method for manufacturing a wiring substrate according to an embodiment. FIG.

Embodiments of a wiring board manufacturing apparatus and manufacturing method according to the present invention will be described below with reference to the drawings. Before describing these, the structure of the wiring board 1 will be briefly explained.

As shown in FIG. 4, the 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 the insulating substrate 11. The wiring layer 2 includes a conductive base layer 12 formed on the surface of the insulating substrate 11, a metal seed layer 13 formed on the surface of the base layer 12, and a metal layer 14 formed on the surface of the metal seed layer 13. However, the wiring layer 2 is not limited to this, and may further include, for example, a diffusion layer formed between the base layer 12 and the metal seed layer 13.

[Wiring board manufacturing device]
1 , the wiring substrate manufacturing apparatus 20, also referred to as a film formation apparatus, 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. The wiring substrate manufacturing apparatus 20 includes a metal anode 21, a solid electrolyte membrane 22 disposed between the anode 21 and a cathode (a substrate 10 with a seed layer, described later), a container 23 that contains the anode 21 and a plating solution S, and a power supply unit 24 that applies a voltage between the anode 21 and the base layer 12 of the substrate 10 with a seed layer. Because the base layer 12 and the metal seed layer 13 are electrically 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.

The anode 21 is plate-shaped, positioned opposite the solid electrolyte membrane 22, and embedded in the top plate of the container 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).

The container 23 is made of a material insoluble in the plating solution S and is formed to have a space therein for containing the plating solution S. The container 23 has an opening 23c formed in the bottom. The opening 23c opens downward from the container 23 and is closed by the solid electrolyte membrane 22. In the container 23, the above-mentioned space for containing the plating solution S is formed between the anode 21 and the solid electrolyte membrane 22.

The container 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 the tank 31 via piping. The plating solution S is pumped from the tank 31 by the pump 32, flows into the container 23 through the supply port 23a, and is discharged from the discharge port 23b before returning to the tank 31. A pressure adjustment valve 33 is provided downstream of the discharge port 23b, and the plating solution S in the container 23 can be pressurized to a predetermined pressure by the pressure adjustment valve 33 and the pump 32.

The solid electrolyte membrane 22, also known as a porous membrane or porous resin membrane, is formed from a resin membrane with a certain degree of flexibility. When this solid electrolyte membrane 22 comes into contact with the plating solution S, it becomes impregnated (contains) the 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, approximately 5 μm to approximately 200 μm.

The solid electrolyte membrane 22 is not particularly limited as long as it can be impregnated with metal ions by contacting it 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 fluororesins such as DuPont's Nafion (registered trademark), hydrocarbon resins, polyamic acid resins, and resins with cation exchange functionality such as Asahi Glass's Selemion (CMV, CMD, CMF series).

Plating solution S is a solution containing the metal of metal layer 14 in an ionic state. Examples of such metals include Cu, Ni, Ag, and Au. 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.

Furthermore, the wiring board manufacturing apparatus 20 of this embodiment is equipped with an elevator device 25 that is disposed above the container 23 and raises and lowers the container 23. The elevator device 25 may be any device that can raise and lower the container 23, and may be configured, for example, by a hydraulic or pneumatic cylinder, an electric actuator, a linear guide, a motor, etc.

The wiring substrate manufacturing apparatus 20 further includes a mounting table 26 on which the seed layer-equipped substrate 10 is placed. The mounting table 26 is made of a conductive material and is disposed below the container 23 so that the seed layer-equipped substrate 10 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 container 23.

As shown in Figures 1 and 2, a substrate placement area 27 for placing the seed layer-equipped substrate 10 is provided in the center of the placement table 26. The substrate placement area 27 consists of a rectangular parallelepiped recess into which the seed layer-equipped substrate 10 can be fitted, and has a depth such that, for example, the surface of the base layer 12 of the seed layer-equipped substrate 10 when placed is flush with the surface 26a of the placement table 26.

Furthermore, multiple nozzles 34 (32 in this example) are provided outside the substrate placement area 27 of the placement table 26. These nozzles 34 are arranged eight per group along the four periphery of the substrate placement area 27 so as to surround the substrate placement area 27 (see Figure 2). The nozzles 34 are provided to form a liquid film 15 on the surface of the base layer 12 of the seed layer-covered substrate 10, covering the metal coating formed on the seed layer-covered substrate 10 and a portion of the surface of the seed layer-covered substrate 10 adjacent to the metal coating (more specifically, the surface of the base layer 12 of the seed layer-covered substrate 10). Each nozzle 34 is arranged so as to be inclined toward the center of the substrate placement area 27. More specifically, the nozzles 34 are inclined toward the center of the substrate placement area 27 so that the solution sprayed from the nozzles 34 does not directly hit the solid electrolyte membrane 22.

In addition, to avoid affecting the contact between the solid electrolyte membrane 22 and the seed layer-attached substrate 10, each nozzle 34 is embedded in the mounting table 26 so as not to protrude from the surface 26a of the mounting table 26. Each nozzle 34 is connected to a tank 35 via piping. A liquid supply pump 36 is disposed in the piping. The rotation speed of the liquid supply pump 36 is adjustable to reduce damage to the formed metal film. In other words, by adjusting the rotation speed of the liquid supply pump 36, the pressure of the solution sprayed from the nozzle 34 can be controlled, thereby reducing damage to the metal film caused by the sprayed solution. A pressure adjustment valve may also be disposed in the piping. The solution sprayed from the nozzle 34 can be pure water or plating solution S.

Although not shown, the mounting table 26 is further provided with a conductive member that provides electrical continuity between the mounting table 26 and the seed layer-equipped substrate 10. The conductive member is formed, for example, by bending a metal plate into a Z-shaped cross section. One end of the conductive member contacts the mounting table 26, and the other end contacts the top surface of the seed layer-equipped substrate 10 (i.e., the top surface of the base layer 12). This establishes electrical continuity between the mounting table 26 and the base layer 12 via the conductive member. The conductive member is detachable from the seed layer-equipped substrate 10.

A removable blocking portion 16 is provided on the peripheral edge of the seed layer-attached substrate 10. The blocking portion 16 is formed in a ring shape using, for example, masking tape, resist material, or a plating-resistant resin material. The height of the blocking portion 16 is, for example, 5 μm to 100 μm from the surface of the base layer 12.

When a removable damming portion 16 is used, for example, the substrate 10 with the seed layer is placed on the mounting table 26, and then masking tape is applied to the peripheral edge of the base layer 12 so as to surround the liquid film 15 to be formed, thereby forming a ring-shaped damming portion 16. When forming the liquid film 15, a solution is sprayed onto the inside of the damming portion 16 using a nozzle 34, and the liquid film 15 is formed so as to fill the area surrounded by the damming portion 16. Then, after the seed layer-attached substrate 10 has been washed, the damming portion 16 is removed by peeling off the masking tape.

The damming portion 16 does not necessarily have to be provided on the peripheral edge of the seed layer-bearing substrate 10; for example, it may be provided outside the substrate mounting area 27 of the mounting table 26, closer to the seed layer-bearing substrate 10 than the nozzle 34. In this case, the damming portion 16 does not have to be removable.

In the wiring substrate manufacturing apparatus 20 configured as described above, a nozzle 34 is provided outside the substrate mounting area 27 of the mounting table 26 for forming a liquid film 15 on the surface of the seed layer-equipped substrate 10 to cover the formed metal film. By using this nozzle 34 to form a liquid film 15 that covers the formed metal film and a portion of the surface of the base layer 12 of the seed layer-equipped substrate 10 adjacent to the metal film, the entire formed metal film is covered with the liquid film 15. Therefore, the formed metal film is covered with this liquid film 15 until the seed layer-equipped substrate 10 is cleaned after film formation, thereby suppressing oxidation of the formed metal film.

Furthermore, since multiple nozzles 34 are provided surrounding the substrate placement area 27 of the placement table 26, these nozzles can be used to spray the solution onto the seed layer-formed substrate 10 to form the liquid film 15. This reduces the time it takes to form the liquid film compared to, for example, when the nozzle sprays the solution from only one direction, and also reduces the pressure of the sprayed solution, thereby reducing damage to the formed metal coating.

Furthermore, each nozzle 34 is inclined toward the center of the substrate placement area 27, preventing the solution sprayed from the nozzle 34 from directly hitting the solid electrolyte membrane 22 and minimizing damage to the solid electrolyte membrane 22. In other words, the load on the solid electrolyte membrane 22 caused by the sprayed solution can be reduced.

Furthermore, an annular damming portion 16 that blocks the liquid film 15 is provided around the periphery of the seed layer-attached substrate 10 placed on the mounting table 26. This damming portion 16 prevents the solution in the liquid film 15 from flowing out, thereby maintaining the shape of the liquid film 15. As a result, oxidation of the formed metal film can be reliably suppressed.

[Method of manufacturing a wiring board]
5, 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 separation step S4, a liquid film formation step S5, a cleaning step S6, and a wiring layer formation step S7.

First, in the preparation step S1, a conductive base layer 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 seed layer-attached substrate 10. Well-known techniques (such as those disclosed in Patent Document 1) can be used to sequentially form the base layer 12 and metal seed layer 13 on the surface of the insulating substrate 11. A detailed description of these techniques will be omitted here.

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.

The underlayer 12 is a layer for passing current through the metal seed layer 13 during the formation of the metal layer 14. As shown in FIG. 1 , 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 that constitutes the underlayer 12, or it 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) in the subsequent film-forming step S3, even if the solid electrolyte membrane 22 comes into contact with 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), and allows the metal to be selectively deposited on the metal seed layer 13.

The metal seed layer 13 is formed to correspond to the wiring pattern of the wiring substrate 1, for example, to have multiple independent wiring patterns. In the seed layer-attached substrate 10, the independent wiring patterns are electrically connected to each other via the underlayer 12. This eliminates the need to form lead wires for applying voltage to each wiring pattern in the film-forming step S3 described below, and allows the metal layer 14 to be formed simultaneously on each wiring pattern. The metal seed layer 13 is made of at least one metal selected from the group consisting of silver, copper, gold, palladium, and platinum, for example.

In a seed layer-equipped 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, i.e., the metal film formation area of the seed layer-equipped substrate 10. The remaining portions of the seed layer-equipped substrate 10 excluding the surface of the metal seed layer 13 (for example, the surface of the exposed portion 12a of the underlayer 12) are the non-metal film formation area of the seed layer-equipped substrate 10.

In the pressure application 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, the seed layer-equipped substrate 10 is first placed on the substrate placement area 27 of the placement table 26, and the placement table 26 and the upper surface of the base layer 12 of the seed layer-equipped substrate 10 are electrically connected using the conductive member described above. Next, a ring-shaped damming portion 16 is formed around the periphery of the base layer 12 of the seed layer-equipped substrate 10, for example by applying masking tape, so as to surround the liquid film 15 to be formed.

The solid electrolyte membrane 22 is then attached to the lower end of the container 23 so that it blocks the opening 23c formed in the bottom of the container 23. Then, with the opening 23c of the container 23 blocked by the solid electrolyte membrane 22, the container 23 is lowered by the lifting device 25, bringing the solid electrolyte membrane 22 into contact with the surface of the metal seed layer 13 of the seed layer-attached substrate 10 and the surface of the exposed portion 12a of the underlayer 12.

Then, the pump 32 is driven to supply the plating solution S stored in the tank 31 to the container 23. This causes the plating solution S stored in the tank 31 to flow into the container 23 from the supply port 23a. The liquid pressure of the plating solution S then uniformly pressurizes the surface of the metal seed layer 13 and the surface of the exposed portion 12a of the base layer 12 of the solid electrolyte membrane 22. The applied pressure can be adjusted using, for example, the pressure adjustment valve 33.

In the film-forming process S3 following the pressurizing process S2, a metal film is formed in 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 24, reducing the metal ions contained in the solid electrolyte membrane 22, 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 the voltage is applied, the metal ions of the plating solution S in the container 23 continue to be reduced at the cathode, forming a metal film on the surface of the metal seed layer 13. The formed metal film becomes the metal layer 14 described above (see Figure 3).

Here, if the surface of the exposed portion 12a of the base layer 12 (i.e., the non-metallic film formation area) contains an oxide, such as a natural oxide film or an oxide film formed by surface treatment, 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, causing metal (e.g., Cu) to precipitate. 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.

In the separation process S4 following the film formation process S3, the solid electrolyte membrane 22 is separated from the seed layer-attached substrate 10 after film formation. Specifically, once the metal layer 14 has been formed to a predetermined thickness, the application of voltage between the anode 21 and the base layer 12 is terminated. Next, for example, compressed air is supplied to the interior of the container 23, and the plating solution S inside the container 23 is discharged from the outlet 23b using the compressed air. The discharged plating solution S is returned to the tank 31. Next, the container 23 is raised to a predetermined height by the lifting device 25, and the solid electrolyte membrane 22 is separated from the seed layer-attached substrate 10 on which the metal coating (i.e., the metal layer 14) has been formed.

In the liquid film formation process S5 following the separation process S4, a liquid film 15 is formed on the surface of the seed layer-attached substrate 10 after film formation. The liquid film 15 covers the formed metal film and a portion of the surface of the base layer 12 of the seed layer-attached substrate 10 adjacent to the metal film. Specifically, the liquid supply pump 36 is driven to supply pure water stored in the tank 35 to the nozzle 34. As a result, as shown in FIG. 3 , the pure water stored in the tank 35 is sprayed from the nozzle 34 onto the surface of the seed layer-attached substrate 10 after film formation, forming a liquid film 15 that covers the metal layer 14 and a portion of the surface of the base layer 12 adjacent to the metal layer 14 (e.g., a portion of the surface of the exposed portion 12a). Note that "covering the metal layer 14" means that not only the surface of the metal layer 14 but also all of the side surfaces of the metal layer 14 are covered with the liquid film 15. Furthermore, because the metal layer 14 is formed on the surface of the metal seed layer 13, all of the side surfaces of the metal seed layer 13 are also covered with the liquid film 15.

As a result, a liquid film 15 is formed not only on the entire metal layer 14, but also on part of the surface of the exposed portion 12a of the base layer 12 adjacent to the metal layer 14 (see Figure 3). The liquid film 15 is a single, continuous film. To maintain the shape of the liquid film 15, the liquid film 15 is formed inside an annular damming portion 16 provided on the periphery of the seed layer-attached substrate 10. For example, the liquid film 15 is formed inside the damming portion 16 so as to fill the area surrounded by the damming portion 16.

For the following reasons, 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. That is, if the liquid film 15 is thinner than 5 μm, there is a possibility that the formed metal film will oxidize due to drying before cleaning. On the other hand, if the liquid film 15 exceeds the maximum thickness of the formed metal film, the concentration of the plating solution after film formation will decrease, making it impossible to reuse the plating solution and resulting in an increase in the amount of diluted waste liquid.

In the cleaning process S6 following the liquid film formation process S5, the seed layer-equipped substrate 10 on which the liquid film 15 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, and the masking tape is removed to remove the damming portion 16. Note that the damming portion 16 may be removed before placing it in the water washing tank.

In the wiring layer formation process S7 following the cleaning process S6, 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.

By removing the exposed portion 12a of the base layer 12, as shown in Figure 4, a wiring layer 2 is formed on the surface of the insulating substrate 11. The wiring layer 2 includes, in this order, the portion of the base layer 12 other than the exposed portion 12a, the metal seed layer 13, and the metal layer 14. This completes the wiring substrate 1.

In the wiring board manufacturing method according to this embodiment, the solid electrolyte film 22 is separated from the seed layer-attached substrate 10 after film formation, and a liquid film 15 is formed on the surface of the seed layer-attached substrate 10, covering the formed metal film (i.e., the metal layer 14) and a portion of the surface of the base layer 12 adjacent to the metal film. This results in the entire formed metal film being covered by the liquid film 15. Therefore, by the time the seed layer-attached substrate 10 is cleaned after film formation, the formed metal film is covered by this liquid film 15, thereby suppressing oxidation of the formed metal film.

The portion of the liquid film 15 corresponding to the edge of the metal coating is relatively thin, making it relatively susceptible to oxidation reactions at this edge. By forming a continuous liquid film 15 on the surface of the seed layer-attached substrate 10 so as to cover the formed metal coating and a portion of the surface of the underlayer 12 adjacent to the metal coating, the portion of the liquid film corresponding to the edge of the metal coating can be made thicker, thereby reliably preventing oxidation of the edge of the metal coating.

The present embodiment will be described below using examples, but the present invention is not limited to these examples.

[Examples and Comparative Examples]
In the examples and comparative examples, first, a 3 mm thick Cu substrate was prepared and pretreated under the same conditions. The metal film area on both Cu substrates was 2 cm x 1 cm, i.e., the film formation area on both Cu substrates was 2 ^cm² . 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. Next, 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.

Next, a 10 μm-thick metal film was formed on the Cu substrate using 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 42°C, the current was 100 mA, and the pressure was 1 kN.

The solid electrolyte film was then separated from the Cu substrate, and a continuous liquid film was formed on the surface of the Cu substrate after film formation by spraying pure water, covering the metal film and a portion of the surface of the Cu substrate adjacent to the metal film. This was used as the example sample. A comparative example sample was also prepared without the liquid film.

Then, both the example sample and the comparative example sample were left for 30 seconds. After that, the example sample and the comparative example sample were each washed with pure water and immediately dried with an air blower to prevent discoloration after washing. After that, the example sample and the comparative example sample were each checked for discoloration (in other words, for the presence or absence of oxidation).

As a result, in the case of the example sample, there was no discoloration of the formed metal film. In contrast, in the case of the comparative example sample, there was discoloration of the formed metal film. This demonstrates that oxidation of the formed metal film can be prevented by forming a liquid film that covers the formed metal film and a portion of the surface of the substrate adjacent to the metal film.

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.

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: wiring substrate manufacturing apparatus, 21: anode, 22: solid electrolyte film, 23: container, 23a: supply port, 23b: discharge port, 23c: opening, 24: power supply unit, 25: lifting device, 26: mounting table, 26a: surface, 27: base material mounting area, 31: tank, 32: pump, 33: pressure regulating valve, 34: nozzle, 35: tank, 36: liquid supply pump

Claims (3)

A wiring board manufacturing apparatus for manufacturing a wiring board by forming a metal film on a surface of a substrate by a solid phase electrodeposition method,
an anode;
a solid electrolyte membrane disposed between the anode and the substrate serving as a cathode;
a mounting table disposed opposite the solid electrolyte membrane and having a substrate mounting area on which the substrate is mounted;
a container having an opening on the mounting table side and closed by the solid electrolyte membrane, the container containing the anode and the plating solution;
a power supply unit that applies a voltage between the anode and the substrate;
Equipped with
a nozzle is provided outside the substrate mounting area of the mounting table to form a liquid film on the surface of the substrate, the liquid film covering the formed metal coating and a portion of the surface of the substrate adjacent to the metal coating;
A wiring substrate manufacturing apparatus characterized in that a ring-shaped damming portion for damming the liquid film is provided outside the substrate mounting area of the mounting table, closer to the substrate than the nozzle, or on the peripheral portion of the substrate to be mounted. a plurality of the nozzles are provided so as to surround the substrate placement area of the placement table,
The wiring substrate manufacturing apparatus according to claim 1 , wherein each nozzle is inclined toward the center of the substrate placement area. A method for manufacturing a wiring board by forming a metal film on a surface of a substrate by a solid phase electrodeposition method,
a pressurizing step of bringing the solid electrolyte membrane into contact with the substrate placed on a mounting table facing the solid electrolyte membrane while the opening of the container is closed with the solid electrolyte membrane, supplying a plating solution to the container, and pressing the substrate with the solid electrolyte membrane in contact with the plating solution;
a film-forming step of forming a metal coating derived from metal ions contained in the solid electrolyte membrane on the surface of the substrate by applying a voltage while the substrate is pressurized;
a separating step of separating the solid electrolyte membrane from the substrate after the plating solution is discharged from the container;
a liquid film forming step of forming a liquid film on the surface of the substrate to cover the formed metal coating and a portion of the surface of the substrate adjacent to the metal coating;
a cleaning step of removing the substrate on which the liquid film has been formed from the mounting table and cleaning the substrate;
A method for manufacturing a wiring substrate, comprising: