JP2023112533A - Manufacturing method of wiring board - Google Patents

Abstract

To provide a manufacturing method of a wiring board capable of suppressing reduction in durability of a solid electrolyte film.SOLUTION: A manufacturing method of a wiring board 80 includes the steps of: preparing an insulative base material B containing resin; roughening a surface B2 of a portion where a wiring layer C is provided; depositing metal particles M onto a surface of the base material, thereby forming a seed layer 20 containing the metal on the base material; disposing an electrolyte film 13 between a positive electrode 11 and the seed layer which is a negative electrode, bringing the electrolyte film into contact with the seed layer, applying a voltage between the positive electrode and the seed layer, and reducing metal ions contained in the electrolyte film, thereby depositing a metal film F on the seed layer; forming a cut from a surface of the metal film to a boundary between the roughened portion and a non-roughened portion on the surface of the base material; and physically removing, from the base material, portions which are positioned in the non-roughened portion on the base material of the metal film and the seed layer.SELECTED DRAWING: Figure 1A

Description

The present invention relates to a method for manufacturing a wiring board.

Conventionally, when manufacturing an electronic circuit board or the like, a metal film is formed on the surface of a substrate in order to form a metal circuit pattern (for example, Patent Document 1). Patent Literature 1 discloses a technique of depositing metal by reducing metal ions and forming a metal film made of the deposited metal on the surface of a conductor pattern layer of a resin substrate.

In the technique disclosed in Patent Document 1, in a state in which a solid electrolyte membrane (hereinafter also referred to as an electrolyte membrane) is pressed against the surface of a conductor pattern layer of a resin base material, a conductor pattern serving as an anode and a cathode is formed using a power supply unit. A voltage is applied between the layers. Metal ions contained in the electrolyte membrane are reduced on the surface of the conductive pattern layer by the application of voltage from the power source. Therefore, the metal is deposited on the surface of the conductor pattern layer, and a metal film can be formed on the surface of the conductor pattern layer.

JP 2016-125087 A

By the way, since the portion of the surface of the resin substrate on which the conductive pattern layer is not formed cannot serve as a cathode, the metal film is not formed on this portion. Therefore, when a voltage is applied between the anode and the conductor pattern layer, a step occurs between the portion where the metal film is formed and the portion where the metal film is not formed. Since the electrolyte membrane is pressed against the surface of the conductor pattern layer of the resin base material, the electrolyte membrane deforms so as to follow the steps. As the metal film on the surface of the conductor pattern layer grows, the steps also increase. Therefore, the electrolyte membrane may undergo local plastic deformation when following the steps, and the durability of the electrolyte membrane decreases. I was afraid.

The present invention has been made in view of the above points, and an object thereof is to provide a method of manufacturing a wiring substrate that can suppress deterioration in durability of a solid electrolyte film.

In view of the above problems, a method for manufacturing a wiring board according to the present invention is a method for manufacturing a wiring board including a base material and a wiring layer having a predetermined wiring pattern provided on the surface of the base material. a step of preparing an insulating base material containing a resin as the base material; a step of roughening the surface of a portion of the surface of the base material on which the wiring layer is to be provided; forming a metal-containing seed layer on the surface of the base material by depositing metal particles on the surface of the base material; and disposing a solid electrolyte membrane between the seed layer, which is an anode and a cathode. Then, the solid electrolyte membrane is brought into contact with the seed layer, and a voltage is applied between the anode and the seed layer to reduce the metal ions contained in the solid electrolyte membrane, thereby a step of forming a metal film, with respect to the metal film and the seed layer, from the surface of the metal film toward the boundary between the roughened portion and the non-roughened portion on the surface of the base material; a step of forming a cut, and physically removing a portion of the metal film and the seed layer in which the cut is formed that is located on a portion that is not roughened on the base material from the base material. and removing.

In the method for manufacturing a wiring board according to the present invention, the surface of the portion on which the wiring layer is provided is roughened among the surfaces of the base material. is formed to be rougher than the surface roughness of the portion. That is, unevenness is formed in the roughened portion, and the surface area of the roughened portion becomes larger than the surface area of the other portions. In the method, after roughening the surface of the substrate, the metal particles generated by the target source are deposited on the surface of the substrate, thereby forming a flat surface seed layer on the surface of the substrate. . At this time, the seed layer enters into the recesses of the roughened portion of the surface of the substrate, and contacts the substrate over a larger surface area in this portion than in other portions. Therefore, the adhesion strength between the portion of the substrate provided with the wiring layer and the seed layer is higher than the adhesion strength between the portion of the substrate provided with no wiring layer and the seed layer. In this method, since the metal film is formed on the seed layer by bringing the solid electrolyte membrane into contact with the flat seed layer, local deformation of the solid electrolyte membrane can be suppressed, and the solid electrolyte membrane can be improved. A decrease in durability can be suppressed. Finally, of the metal film and the seed layer, by physically removing the portion located in the non-roughened portion of the base material from the base material, wiring of a predetermined wiring pattern on the surface of the base material is performed. Layers can be formed.

As a preferred mode, in the roughening step, the surface of the portion where the wiring layer is provided is roughened by a laser.

According to this aspect, since the surface of the portion where the wiring layer is to be provided is roughened by a laser, a finer wiring pattern can be realized than when roughening is performed using a chemical such as permanganate. can be done. In addition, since heat is applied to the resin of the base material by the laser in the air, functional groups of the oxide of the resin are generated, and the functional groups adhere to the surface of the roughened portion of the base material. . Since the metal particles generated by the target source are bonded to the functional groups generated from the resin of the base material, the adhesion strength between the roughened portion of the surface of the base material and the seed layer can be increased.

A preferred embodiment includes the step of irradiating the surface of the base material with oxygen plasma after the step of roughening and before the step of forming the seed layer.

Since the surface area of the roughened portion on the surface of the substrate is larger than the surface area of the other portions, according to this aspect, the oxygen-containing functional group is attached to the surface of the roughened portion of the substrate, more attached. Since the metal particles generated by the target source bind to the functional groups attached to the surface of the substrate, the adhesion strength between the surface of the roughened portion of the substrate and the seed layer can be increased.

As a preferred embodiment, in the step of forming the seed layer, copper is used as the target source, and copper particles as the metal particles are deposited on the surface of the base material by sputtering, so that the surface of the base material is After the step of forming a copper-containing seed layer and forming the metal film, heat is applied to the base material, the seed layer, and the metal film until the resin of the base material softens. A step of heat treatment is included.

Since the surface area of the roughened portion on the surface of the substrate is larger than the surface area of the other portions, according to this aspect, the copper particles flying from the target source are scattered on the surface of the roughened portion on the substrate. , more is evaporated. When the copper particles are deposited on the surface of the substrate by sputtering, gaps are formed between the copper particles and the surface of the substrate. According to this aspect, since heat treatment is performed by applying heat to the base material, the seed layer, and the metal film until the resin of the base material is softened, the resin softened by the heat treatment is placed between the copper particles and the surface of the base material. enter the gap formed in the Since more copper particles are deposited on the surface of the roughened portion of the substrate, the contact area between the copper particles and the softened resin increases, and the surface of the roughened portion of the substrate increases. and the seed layer.

As a preferred embodiment, the step of forming the cut and the step of removing are performed after the step of performing the heat treatment.

According to this aspect, after the heat treatment, the metal film and the seed layer are treated from the surface of the metal film toward the boundary between the roughened portion and the non-roughened portion on the surface of the base material. , forming an incision. In this way, the notch is formed in the metal film and the seed layer in a state in which the adhesion strength between the surface of the roughened portion of the base material and the seed layer is increased by the heat treatment, so that the notch is formed. During the process, the seed layer can be prevented from peeling off from the surface of the roughened portion of the substrate. Since the seed layer strongly adheres to the surface of the roughened portion of the base material, the portion of the metal film and the seed layer where the cut is formed is located on the unroughened portion of the surface of the base material. Only the portion that does so can be removed from the substrate.

ADVANTAGE OF THE INVENTION According to this invention, durability fall of a solid electrolyte membrane can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing explaining the process of manufacturing the wiring board which concerns on 1st Embodiment of this invention, (a) shows the process of preparing a base material, (b) shows the process of roughening, ( c) shows the step of forming a seed layer. FIG. 4A is a cross-sectional view illustrating the steps of manufacturing the wiring board according to the first embodiment of the present invention, in which (d) shows the step of forming a metal film, and (e) shows the step of forming a cut; , (f) indicates the step of removing. It is sectional drawing explaining the process of manufacturing the wiring board which concerns on 1st Embodiment of this invention, (g) shows the manufactured wiring board. FIG. 4 is a cross-sectional view showing the film forming apparatus used for manufacturing the wiring board according to the first embodiment, showing a state in which the solid electrolyte film is separated from the seed layer. FIG. 2 is a cross-sectional view showing a film forming apparatus used for manufacturing the wiring board according to the first embodiment, showing a state in which a solid electrolyte film is in contact with a seed layer; FIG. 4A is a cross-sectional view illustrating a process of manufacturing a wiring board according to a second embodiment of the present invention; b-1) shows the step of irradiating oxygen plasma. FIG. 4C is a cross-sectional view illustrating steps of manufacturing a wiring board according to a second embodiment of the present invention, where (c) shows a step of forming a seed layer, and (d) shows a step of forming a metal film; and (e) shows a step of forming a cut. It is sectional drawing explaining the process of manufacturing the wiring board which concerns on 2nd Embodiment of this invention, (f) shows the process of removing, (g) shows the manufactured wiring board. FIG. 10A is a cross-sectional view illustrating steps for manufacturing a wiring board according to a third embodiment of the present invention, in which (a) shows a step of preparing a base material, (b) shows a step of roughening, ( b-1) shows the step of irradiating oxygen plasma. FIG. 10A is a cross-sectional view illustrating steps of manufacturing a wiring board according to a third embodiment of the present invention, where (c) shows a step of forming a seed layer, and (d) shows a step of forming a metal film; and (d-1) indicates the step of heat treatment. FIG. 10A is a cross-sectional view illustrating steps of manufacturing a wiring board according to a third embodiment of the present invention, in which (e) shows a step of forming cuts, (f) shows a step of removing, and (g) indicates a manufactured wiring board. 1 illustrates an example of the present invention, and shows the peel strength of each test piece manufactured under different manufacturing conditions for a wiring board. 1 illustrates an example of the present invention, and shows the peel strength ratio of each test piece manufactured by changing the type of plasma irradiated to the substrate as the manufacturing condition of the wiring board. Description of Examples of the present invention, (a) shows a plan photograph of a test body, and (b) is each produced by changing the order of the heat treatment step and the cut formation step. It shows the peel strength of the specimen.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
A method for manufacturing the wiring board 80 according to the first embodiment will be described with reference to FIGS. 1A to 3 . The manufacturing method of the present embodiment, as shown in FIG. It can be applied in manufacturing.

[Preparation process]
As shown in FIG. 1A(a), in the method of manufacturing the wiring board 80 of the present embodiment, a step of preparing an insulating base material B containing resin as the base material B is performed. Examples of resins constituting the base material B include epoxy resins, ABS resins, AS resins, AAS resins, PS resins, EVA resins, PMMA resins, PBT resins, PET resins, PPS resins, PA resins, POM resins, PC resins, Thermoplastic resins such as PP resin, PE resin, PI resin (polyimide), polymer alloy resin containing elastomer and PP, modified PPO resin, PTFE resin, and ETFE resin are preferably used. As the base material B, for example, a base material made of glass epoxy resin, a flexible film-like base material such as polyimide resin, or the like can be used.

[Process of roughening]
Next, as shown in FIG. 1A(b), in the manufacturing method according to the present embodiment, a step of roughening the surface B2 of the surface B1 of the substrate B where the wiring layer C is to be provided is performed. Specifically, in this step, the substrate B is placed in a laser irradiation device (not shown), and a laser beam is emitted from a laser light source (not shown) provided in the laser irradiation device toward the surface B1 of the substrate B. , irradiate the laser 30 . The surface B2 of the portion where the wiring layer C is provided is irradiated with a laser 30 to roughen the surface B2 so that a predetermined pattern corresponding to the wiring pattern of the wiring board 80 is formed on the surface B1 of the base material B. . As a result, unevenness is formed on the surface B2 of the roughened portion of the surface B1 of the base material B. As shown in FIG. It is preferable to roughen the surface B2 of the portion of the base material B on which the wiring layer C is provided so that the arithmetic mean roughness Ra is 0.1 μm to 0.5 μm. This is because, as the Ra increases, the adhesion strength between the base material B and the metal particles (e.g., copper particles) described later increases, but on the other hand, the metal particles (e.g., copper particles) present on the surface B2 of the base material B This is because the transmission loss increases because the surface area increases and the conduction path lengthens. Communication such as 5G and 6G requires a lower transmission loss, so in this case, it is more preferable to roughen the surface B2 so that the arithmetic mean roughness Ra is 0.1 μm to 0.2 μm. In this step, for example, a mask member (not shown) having a shape corresponding to the wiring pattern of the wiring board 80 is placed on the surface B1 of the base material B, and a chemical solution such as permanganate is applied to the surface of the base material B. B1 may be roughened. When the surface B1 of the base material B is roughened by the laser 30, a finer wiring pattern can be realized than when the surface is roughened by using a chemical such as permanganate. Further, when heat is applied to the resin of the base material B by the laser 30 in the air, the functional groups of the oxide of the resin are generated, and the surface B2 of the roughened portion of the surface B1 of the base material B , the functional group is attached. The functional group is generated when heat is applied to the resin of the base material B by the laser 30 in the atmosphere, particularly in an oxygen atmosphere. groups (--COOH) and aldehyde groups (--COH).

[Step of Forming Seed Layer]
Next, as shown in FIG. 1A(c), metal particles M generated by a target source (not shown) are vapor-deposited on the surface B1 of the substrate B, so that the surface B1 of the substrate B contains a metal. Then, a step of forming the seed layer 20 is performed. Specifically, in this step, the substrate B manufactured through the roughening step is attached to a transport device (not shown), and the surface B1 of the substrate B faces a target source (not shown). The base material B is conveyed. Thereafter, in this step, metal particles M (for example, copper particles) generated by the target source are vapor-deposited on the surface B2 of the roughened portion and the surface B3 of the unroughened portion of the substrate B. Specifically, on the surface B2 of the roughened portion of the substrate B, the metal particles M flying from the target source enter the recesses formed on the surface B2, and after the recesses are filled with the metal particles M, The metal particles M are deposited so as to cover the protrusions formed on the surface B2. On the other hand, on the surface B3 of the portion of the substrate B that is not roughened, the metal particles M flying from the target source are uniformly deposited. In this way, the metal particles M are deposited on the surface B1 of the base material B (that is, the surface B2 of the roughened portion and the surface B3 of the unroughened portion of the base material B) to a predetermined thickness. A thin seed layer 20 is formed. Seed layer 20 has a planar surface 21 facing the target source. Methods for forming the seed layer 20 include physical vapor deposition (PVD) such as sputtering, vacuum deposition, or ion plating. The material of the seed layer 20 is preferably a material that can bond with the functional groups generated in the roughening step described above. , silver, nickel, etc. may be used. When the seed layer 20 is formed by laminating a plurality of metals, titanium may be used on the base material B side, and copper may be used on the metal film F side, which will be described later. When copper is selected as the material for the seed layer 20, it is preferable to form the seed layer 20 so that the crystal grain size of copper is in the range of 1 nm to 1 μm. The crystal grain size of copper can be measured by cross-sectional observation of a copper film using a transmission electron microscope (TEM).

As described above, in the manufacturing method according to the present embodiment, of the surface B1 of the base material B, the surface B2 of the portion where the wiring layer C is provided is roughened, so the base material B is provided with the wiring layer C. The surface roughness of the portion is formed to be rougher than the surface roughness of the other portions. That is, the surface area of the surface B2 of the roughened portion of the base material B is larger than the surface area of the other portions. The metal particles M generated by the target source enter the recesses of the roughened portion of the surface B1 of the substrate B. As shown in FIG. Therefore, the seed layer 20 is in contact with the base material B over a larger surface area than the surface B3 of the other portions on the surface B2 of the roughened portion of the base material B. As shown in FIG. As a result, the adhesion strength between the surface B2 of the portion of the substrate B where the wiring layer C is provided and the seed layer 20 can be made higher than the adhesion strength between the surface B3 of the other portion and the seed layer 20. Furthermore, the metal particles M generated by the target source are bound to the functional groups generated from the resin of the substrate B by colliding with the surface B1 of the substrate B. As shown in FIG. Therefore, the adhesion strength between the surface B2 of the roughened portion of the base material B and the seed layer 20 can be made higher than the adhesion strength between the surface B3 of the other portion and the seed layer 20. .

[Step of forming a metal film]
Then, as shown in FIG. 1B(d), a step of forming a metal film F is performed. In this step, a metal film F is formed on the surface 21 of the seed layer 20 using the film forming apparatus 1 shown in FIGS. The metal film F is formed with a thickness of, for example, 1 μm or more and 100 μm or less.

First, the structure of the film-forming apparatus 1 is demonstrated. The film forming apparatus 1 is a film forming apparatus (plating apparatus) for forming a metal film F by a solid-phase electrodeposition method, and is used when forming the metal film F on the surface 21 of the seed layer 20 . In this embodiment, for convenience of explanation, it is assumed that the solid electrolyte membrane 13 (hereinafter also referred to as the electrolyte membrane) is arranged below the anode 11 and the substrate B is arranged below it. The positional relationship of one component is specified. However, if the metal film F can be formed on the surface 21 of the seed layer 20 formed on the substrate B, the positional relationship is not limited to this. may be upside down.

As shown in FIG. 2, the film deposition apparatus 1 includes a metal anode 11, an electrolyte membrane 13 disposed between the anode 11 and a seed layer 20 which is a cathode, and a and a power supply unit 14 that applies a voltage to the .

In this embodiment, the film forming apparatus 1 further includes a container 15. The container 15 contains the anode 11 and a solution L (hereinafter referred to as , referred to as a metal solution L). Specifically, an accommodation space 15 c for accommodating the metal solution L is formed between the anode 11 and the electrolyte membrane 13 , and the accommodated metal solution L flows from one side of the container 15 to the other side.

As shown in FIG. 2, when the anode 11 and the electrolyte membrane 13 are spaced apart, the anode 11 is plate-shaped and made of the same material as the metal film F (for example, Cu). , or an anode made of a material that is insoluble in the metal solution L (eg, Ti). On the other hand, although not shown, when the anode 11 and the electrolyte membrane 13 are in contact, the anode 11 is formed from a porous body through which the metal solution L permeates and supplies metal ions to the electrolyte membrane 13. A different anode may be used.

The electrolyte membrane 13 can be impregnated (contained) with metal ions by bringing it into contact with the metal solution L described above. There is no particular limitation as long as the metal can be deposited. The thickness of the electrolyte membrane 13 is, for example, approximately 5 μm to approximately 200 μm. Materials for the electrolyte membrane 13 include, for example, fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont, hydrocarbon-based resins, polyamic acid resins, and cations such as Celemion (CMV, CMD, CMF series) manufactured by Asahi Glass Co., Ltd. A resin having an exchange function can be mentioned.

The metal solution L is a liquid containing the metal of the metal film F in the form of ions. Examples of the metal include Cu, Ni, Ag, and Au. It is obtained by dissolving (ionizing) a metal with an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, or pyrophosphoric acid.

Furthermore, the film forming apparatus 1 of the present embodiment includes an elevating device 70 for raising and lowering the container 15 above the container 15 . The elevating device 70 may be any device that can elevate the container 15, and can be configured by, for example, a hydraulic or pneumatic cylinder, an electric actuator, a linear guide, a motor, or the like.

Further, the container 15 is provided with a supply port 15a through which the metal solution L is supplied and a discharge port 15b through which the metal solution L is discharged. The supply port 15a and the discharge port 15b are connected to the tank T via pipes 50 and 52, respectively. The metal solution L sent out from the tank T by the pump P flows into the container 15 from the supply port 15a, is discharged from the discharge port 15b, and returns to the tank T. As shown in FIG. A pressure regulating valve 54 is provided on the downstream side of the discharge port 15b, and the pressure regulating valve 54 and the pump P can pressurize the metal solution L in the container 15 at a predetermined pressure. Therefore, the electrolyte membrane 13 presses the surface 21 of the seed layer 20 due to the liquid pressure of the metal solution L during film formation. Thereby, the metal film F can be formed on the seed layer 20 while uniformly pressing the surface 21 of the seed layer 20 with the electrolyte film 13 .

The film forming apparatus 1 of this embodiment includes a metal pedestal 110 on which the base material B having the seed layer 20 is placed. . A positive electrode of the power supply unit 14 is electrically connected to the anode 11 built in the container 15 . Specifically, the film forming apparatus 1 is configured such that the negative electrode of the power source section 14 and the seed layer 20 are electrically connected to a portion (specifically, an end portion) of the seed layer 20 during the film formation of the metal film F. A contacting conductive member 56 is provided. The conductive member 56 is a metal plate that partially covers the edge of the seed layer 20 , and is partially bent to contact the metal pedestal 110 . Thereby, the metal pedestal 110 is electrically connected to the seed layer 20 via the conductive member 56 . In addition, the conductive member 56 can be detached from the base material B on which the seed layer 20 is formed.

Next, the process of forming the metal film F using the film forming apparatus 1 will be described. In this step, the electrolyte membrane 13 is placed between the anode 11 and the seed layer 20 which is the cathode, the electrolyte membrane 13 is brought into contact with the seed layer 20, and a voltage is applied between the anode 11 and the seed layer 20. , the metal film F is formed on the seed layer 20 by reducing the metal ions contained in the electrolyte film 13 .

First, in the film forming process, as shown in FIG. 2, the base material B on which the seed layer 20 is formed and the conductive member 56 are placed at predetermined positions on the metal pedestal 110 . Then, as shown in FIG. 3, the container 15 is lowered to a predetermined height by the lifting device 70 .

When the metal solution L is pressurized by the pump P, the electrolyte membrane 13 is pressed against the surface 21 of the seed layer 20, and the pressure control valve 54 maintains the metal solution L in the container 15 at a set constant pressure. become. That is, the electrolyte membrane 13 can uniformly press the surface 21 of the seed layer 20 with the regulated liquid pressure of the metal solution L in the container 15 .

In this pressed state, a voltage is applied between the anode 11 and the seed layer 20 to reduce the metal ions contained in the electrolyte membrane 13, thereby depositing metal derived from the metal ions on the surface 21 of the seed layer 20. do. Further, the application of voltage continues to reduce the metal ions of the metal solution L in the container 15 at the cathode, so that the metal film F is formed on the surface 21 of the seed layer 20 .

When the metal film F is formed to have a predetermined thickness, the voltage application between the anode 11 and the seed layer 20 is stopped, and the pressurization of the metal solution L by the pump P is stopped. Then, using the lifting device 70, the container 15 is lifted to a predetermined height (see FIG. 2), and the substrate B with the metal film F formed thereon as shown in FIG. Remove.

[Step of forming cuts]
Next, as shown in FIG. 1B (e), the metal film F and the seed layer 20 are roughened from the surface F1 of the metal film F to the surface B2 of the roughened portion of the surface B1 of the base material B. A step of forming a cut 24 toward or near the boundary B4 with the surface B3 of the portion where there is no surface is carried out. Specifically, in this step, the base material B on which the seed layer 20 and the metal film F are formed is placed in a laser irradiation device (not shown), and a laser light source (not shown) provided in the laser irradiation device. ), the laser 32 is irradiated toward the surface F1 of the metal film F. As shown in FIG. The laser 32 forms a cut 24 in the metal film F and the seed layer 20 from the surface F1 of the metal film F to the surface B1 of the substrate B or its vicinity. The cut 24 preferably reaches the surface B1 of the substrate B, but the second seed layer portion 20B and the second metal film portion FB may be removed from the substrate B in the removing step described later. If possible, it does not have to reach the surface B1 of the base material B.

In the step of forming the cuts 24, when both the material of the metal film F and the seed layer 20 are copper, the cuts are formed in the metal film F and the seed layer 20, while the resin of the base material B is not melted. It is preferable to subject the metal film F and the seed layer 20 to laser processing with short to ultra-short pulses and non-thermal processing with little thermal effect. The number of times of laser irradiation is determined according to the thicknesses of the metal film F and the seed layer 20. As the thickness increases, the number of times of laser irradiation needs to be increased. For example, when the thickness of the metal film F such as copper and the seed layer 20 is 20 μm, as an example, laser irradiation is performed under the conditions of green laser (wavelength 532 nm), output 1 W, pulse width 20 ps (picoseconds), and frequency 30 kHz. conduct. By forming the cuts 24, the seed layer 20 is formed on the first seed layer portion 20A located on the surface B2 of the roughened portion of the base material B and on the surface B3 of the non-roughened portion on the base material B. The second seed layer portion 20B located at the second seed layer portion 20B is separated. Also, the metal film F is separated into a first metal film portion FA positioned on the first seed layer portion 20A and a second metal film portion FB positioned on the second seed layer portion 20B. The formation of the cuts 24 is not limited to the laser, and a physical cutting tool (cutting machine) such as a rotary blade cutter or a straight blade cutter may be used.

[Step of removing]
Next, as shown in FIG. 1B(f), of the portions of the metal film F and the seed layer 20 in which the cuts 24 are formed, the portions located on the non-roughened portion of the base material B are removed from the base material B. Perform a physical removal step. That is, in this step, the second metal film portion FB and the second seed layer portion 20B of the metal film F and the seed layer 20 are physically removed from the surface B3 of the non-roughened portion of the base material B. . As a method for removing, a physical method may be mentioned. For example, a peeling member such as an adhesive tape 90, film, or magnet may be used, or a compressible gas such as compressed air (not shown) may be used. may Here, as described above, the seed layer 20 is in contact with the base material B on the surface B2 of the roughened portion of the base material B with a larger surface area than the surface B3 of the other portion, so that the surface B2 is roughened. The adhesion strength between the surface B2 of the cut portion and the seed layer 20 is higher than the adhesion strength between the surface B3 of the other portion and the seed layer 20 . Furthermore, the metal particles M generated by the target source collide with the surface B1 of the substrate B and bond with the functional groups generated from the resin of the substrate B, so that the roughened portion of the substrate B The adhesion strength between the surface B2 and the seed layer 20 is even higher than the adhesion strength between the surface B3 and the seed layer 20 in other portions. For this reason, as shown in the figure, an adhesive tape 90 is attached to the surface F1 of the metal film F, and then the tape 90 is pulled up to remove the second surface from the surface B3 of the non-roughened portion of the base material B. Only the metal film portion FB and the second seed layer portion 20B are removed. On the other hand, the first metal film portion FA and the first seed layer portion 20A remain on the surface B2 of the roughened portion of the base material B to form the wiring layer C. As shown in FIG. As a result, as shown in FIG. 1B(g), a wiring board 80 having a wiring layer C having a predetermined wiring pattern formed on the surface B1 of the base material B can be obtained.

As described above, according to the manufacturing method according to the present embodiment, the seed layer 20 having the flat surface 21 is formed on the surface B1 of the substrate B. Therefore, the electrolyte membrane 13 is formed on the flat surface 21. , the metal film F can be formed on the surface 21 of the seed layer 20, and local deformation of the electrolyte membrane 13 can be suppressed. Therefore, even when the metal film F is formed repeatedly, deterioration in the durability of the electrolyte membrane 13 can be suppressed.

<Second embodiment>
Next, a method for manufacturing the wiring board 80 according to the second embodiment will be described with reference to FIGS. 4A and 4B. In the manufacturing method according to the second embodiment, after the step of roughening the base material B (FIG. 4A(b)) and before the step of forming the seed layer 20 (FIG. 4A(c)), the base material The manufacturing method according to the first embodiment differs from the manufacturing method according to the first embodiment in that it includes a step of irradiating the surface B1 of B with oxygen plasma 40 . Hereinafter, differences will be mainly described, and the same members and portions as those of the above-described embodiment will be assigned the same reference numerals, and detailed description thereof will be omitted.

[Step of irradiating oxygen plasma]
As shown in FIG. 4A(b-1), in the present embodiment, after the step of roughening the substrate B (FIG. 4A(b)), the surface B1 of the substrate B (that is, the substrate B is roughened Oxygen plasma 40 is applied to the surface B2 of the roughened portion and the surface B3) of the non-roughened portion. Specifically, in this step, the substrate B manufactured through the roughening step is attached to a transport device (not shown), and the surface B1 of the substrate B faces the oxygen plasma generation source (not shown). , the substrate B is conveyed. Thereafter, in this step, the surface B2 of the roughened portion and the surface B3 of the non-roughened portion of the substrate B are irradiated with oxygen plasma 40 generated by the oxygen plasma generation source, and the surface of the substrate B A functional group containing oxygen (eg, hydroxyl group (--OH), carboxyl group (--COOH), aldehyde group (--COH)) is attached to B1. Since the surface area of the surface B2 of the roughened portion on the surface B1 of the substrate B is larger than the surface area of the surface B3 of the other portion, the functional group containing oxygen is More adheres to surface B2. As described above, heat is applied to the resin of the base material B by the laser 30 in the atmosphere to generate the functional groups of the oxide of the resin. Functional groups containing oxygen can be attached.

After that, the step of forming the seed layer 20 described above is performed. By colliding with the surface B1 of the substrate B, the metal particles M generated by the target source collide with the surface B1 of the substrate B (that is, the surface B2 of the roughened portion of the substrate B and the unroughened portion It binds to the functional groups attached to the surface B3) of the part. Therefore, the adhesion strength between the surface B2 of the roughened portion of the base material B and the seed layer 20 can be made higher than the adhesion strength between the surface B3 of the other portion and the seed layer 20.

<Third Embodiment>
Next, a method for manufacturing the wiring board 80 according to the third embodiment will be described with reference to FIGS. 5A to 5C. In the manufacturing method according to the third embodiment, after the step of forming the metal film F (FIG. 5B (d)), the step of performing heat treatment (FIG. 5B (d-1) is included, and the cut is formed The difference from the manufacturing method according to the second embodiment is that the process and the removing process are performed after the heat treatment process.Hereinafter, the differences will be mainly described, and the same members and parts as those in the above-described embodiment will be described. are given the same reference numerals and their detailed description is omitted.

[Step of performing heat treatment]
In this embodiment, the step of forming the seed layer 20 is performed prior to the step of heat treatment, as shown in FIG. 5A(c). In this step, copper is used as a target source, and copper particles as the metal particles M are deposited on the surface B1 of the substrate B by sputtering, thereby forming a seed layer 20 containing copper on the surface B1 of the substrate B. Form. Next, as shown in FIG. 5B(d), using the film forming apparatus 1, a step of forming a metal film F on the surface 21 of the seed layer 20 is performed. Since the process of forming the seed layer 20 and the process of forming the metal film F have been described in the first embodiment, the description of these processes is omitted in this embodiment.

As shown in FIG. 5B (d-1), in the present embodiment, after the step of forming the metal film F, the substrate B, the seed layer 20, and the metal film are removed until the resin of the substrate B softens. A step of heat-treating F is performed. Specifically, in this step, the base material B on which the seed layer 20 and the metal film F are formed is attached to a conveying apparatus (not shown), and the base material B is placed inside a heating apparatus 100 such as an electric furnace. do. After that, for example, in an oxygen atmosphere, the substrate is heated for a certain period of time at a temperature at which the resin of the base material B is softened but the copper, which is the material of the seed layer 20 and the metal film F, is not softened. As the temperature at which the resin applied to the base material B softens, it is preferable to perform heat treatment in the range of 120 ° C. to 350 ° C. in accordance with the Tg (glass transition temperature) of the resin. is selected, the temperature at which the epoxy resin softens is preferably in the range of 120°C to 200°C. Here, when the copper particles are vapor-deposited on the surface B1 of the base material B by sputtering, gaps are formed between the copper particles and the surface B1 of the base material B. According to the present embodiment, heat treatment is performed by applying heat to the base material B, the seed layer 20, and the metal film F until the resin of the base material B is softened. It enters the gap formed between B and surface B1. Since more copper particles are vapor-deposited on the surface B2 of the roughened portion of the base material B, the contact area between the copper particles and the softened resin increases. Therefore, the adhesion strength between the surface B2 of the roughened portion of the substrate B and the seed layer 20 is defined as the adhesion strength between the surface B3 of the non-roughened portion of the substrate B and the seed layer 20. can be made higher. Further, when the material of the metal film F is copper, the substrate B on which the seed layer 20 and the metal film F are formed is heat-treated at a temperature of 120° C. to 200° C. for a certain period of time to increase the adhesion strength. At the same time, the internal stress of the metal film F generated when forming the metal film F can also be relaxed.

In this embodiment, the case where heat treatment is performed by arranging the base material B on which the seed layer 20 and the metal film F are formed inside the heating device 100 such as an electric furnace has been described. However, the heat treatment may be performed using a laser irradiation device (not shown). Specifically, the base material B on which the seed layer 20 and the metal film F are formed is placed in a laser irradiation device (not shown), and from a laser light source (not shown) provided in the laser irradiation device, A laser is irradiated toward the surface F1 of the metal film F. More specifically, of the surface F1 of the metal film F, the surface of the first metal film portion FA that will become the wiring layer C is irradiated with the laser. The heat applied by the laser is transmitted through the first metal film portion FA and the first seed layer portion 20A and reaches the surface B2 of the roughened portion of the base material B. As shown in FIG. As a result, the resin on the surface B2 of the roughened portion of the base material B can be softened. When heat treatment is performed using a laser irradiation device (not shown), compared to the case where heat treatment is performed using a heating device 100 such as an electric furnace, to the surface B3 of the portion that is not roughened in the base material B, It can suppress heat transfer. Therefore, the adhesion strength between the surface B2 of the roughened portion of the base material B and the seed layer 20 and the adhesion strength between the surface B3 of the non-roughened portion of the base material B and the seed layer 20 and the difference can be made larger. Therefore, in the subsequent removing step, the second metal film portion FB and the second seed layer portion 20B can be easily peeled off from the surface B3 of the portion of the base material B that is not roughened.

In the manufacturing method according to the present embodiment, the step of forming the cut (FIG. 5B (e)) and the step of removing (FIG. 5B (f)) are performed after the step of performing heat treatment (FIG. 5 (d-1)). . Therefore, the adhesion strength between the surface B2 of the roughened portion of the base material B and the seed layer 20 is increased by the heat treatment between the surface B3 of the unroughened portion of the base material B and the seed layer 20. Incisions 24 can be formed in the metal film F and the seed layer 20 in a state in which the adhesion strength is higher than that of . Therefore, when the cut 24 is formed, the seed layer 20 (that is, the first seed layer portion 20A) can be prevented from peeling off from the surface B2 of the roughened portion of the base material B. Since the first seed layer portion 20A is strongly adhered to the surface B2 of the roughened portion of the base material B, the second metal film is Only portion FB and second seed layer portion 20B can be removed from the substrate.

The invention is illustrated by the following examples.

[Example 1]
As a substrate for film formation, a glass epoxy substrate (ABF substrate manufactured by Ajinomoto Co., Ltd.) was prepared by impregnating an epoxy resin into a layer of cloth made of glass fiber. Then, the roughening step described above was performed by irradiating the prepared base material with a laser in the air. In this process, a device called LodeStone manufactured by Esi is used, and a laser beam is emitted under the conditions of a wavelength of 515 nm, a pulse width of 0.8 ps, a beam diameter of φ10 μm, an output of 0.15 W, a repetition frequency of 100 kHz, a scanning speed of 500 mm/s, and an overlap of 5 μm. irradiated. As a result, a substrate having an arithmetic mean roughness Ra of 0.20 μm was obtained, while the surface of the substrate before roughening had an arithmetic mean roughness Ra of 0.05 μm.

Next, the step of irradiating the above-described plasma was performed on the roughened base material. In this process, a high-speed sputtering device manufactured by Shimadzu Corporation was used, and Ar/H ₂ plasma: RF1750W×60sec. , _O2 plasma: RF2100W×180sec. The plasma was irradiated under the conditions of After that, the step of forming the above-described seed layer was performed on the substrate irradiated with the plasma. In this step, a high-speed sputtering apparatus manufactured by Shimadzu Corporation was used, copper was selected as the target source, and a copper seed layer with a thickness of 600 nm was formed.

Next, a copper film was formed using the film forming apparatus 1 (FIGS. 2 and 3) according to the first embodiment. CuSO ₄ (1M)/H ₂ SO ₄ (0.2M) was used as the metal solution, and a Cu plate was used as the anode. As film formation conditions, the temperature of the metal solution was set to 42° C., the solid electrolyte film was brought into close contact with the substrate, and the pressure of the metal solution was 1 kN, the film formation rate was 1.5 μm/min, and a copper film having a thickness of 10 μm was formed. A film was formed.

Next, the step of performing the heat treatment described above was performed on the base material on which the copper seed layer and the copper film were formed. In this step, an electric furnace was used and heat treatment was performed under conditions of 200° C.×60 min in an oxygen atmosphere. Next, the step of forming the above-described cuts was performed on the base material on which the copper seed layer and the copper film were formed, which had been heat-treated. In this step, a laser irradiation device is used to irradiate the copper film and the copper seed layer from the surface of the copper film to the surface of the roughened portion and the surface of the unroughened portion on the surface of the base material. A laser was applied toward the boundary to form a notch. Finally, the removal step described above was performed. In this step, an adhesive tape was attached to the surface of the copper film, and the tape was peeled off to prepare a wiring substrate as a test piece. Width of the wiring board as a test body is 5 mm.

[Example 2]
The test piece according to Example 2 differs from the test piece of Example 1 in that it was manufactured by performing a heat treatment step using a laser irradiation apparatus. In this step, the surface of the first metal film portion serving as the wiring layer was irradiated with the laser among the surfaces of the copper film. Specifically, the conditions are an output of 20 W, a scanning speed of 50 mm/s, a wavelength of 532 nm, a pulse width of 15 ps (picoseconds), a beam diameter of about φ19 μm (after defocusing, a beam diameter of about φ5 mm), and a pulse frequency of 200 KHz (step of 0.25 μm). Then, the laser was irradiated for 1 minute. Other manufacturing conditions are the same as in Example 1.

[Example 3]
The specimen according to Example 3 differs from the specimen of Example 1 in that the step of irradiating the roughened substrate with plasma was omitted. Other manufacturing conditions are the same as in Example 1.

[Example 4]
The specimen according to Example 4 differs from the specimen of Example 2 in that the step of irradiating the roughened substrate with plasma was omitted. Other manufacturing conditions are the same as in Example 2.

[Example 5]
The specimen according to Example 5 differs from the specimen according to Example 1 in that the roughened base material was irradiated with oxygen plasma in the plasma irradiation step. Other manufacturing conditions are the same as in Example 1.

[Comparative Example 1]
The specimen of Comparative Example 1 differs from the specimen of Example 1 in that the copper seed layer was formed by electroless plating in the step of forming the seed layer on the substrate. Other manufacturing conditions are the same as in Example 1.

[Comparative Example 2]
The specimen of Comparative Example 2 differs from the specimen of Example 2 in that a copper seed layer was formed by electroless plating in the step of forming the seed layer on the substrate. Other manufacturing conditions are the same as in Example 2.

[Comparative Example 3]
The specimen of Comparative Example 3 differs from the specimen of Example 1 in that the roughened base material was irradiated with hydrogen plasma in the step of irradiating plasma. Other manufacturing conditions are the same as in Example 1.

[Comparative Example 4]
The test piece according to Comparative Example 4 differs from the test piece of Example 1 in that the step of forming and removing the notch was followed by the step of heat treatment. Other manufacturing conditions are the same as in Example 1.

[Comparative Example 5]
The test piece according to Comparative Example 4 differs from the test piece of Example 1 in that a step of heat treatment was performed after performing the step of forming and removing the cuts, and the prepared test piece 1 mm was cut at both ends to prepare a 3 mm wide specimen. Other manufacturing conditions are the same as in Example 1.

[Confirmation of film formation]
The adhesion of the seed layer to the base material of the wiring board manufactured as described above was measured by a peel test (EZ test manufactured by Shimadzu Corporation). In the measurement of peel strength, the base material of the specimen was attached to a fixing plate, and the copper seed layer and copper film of the specimen chucked by the apparatus were peeled off from the base material in the direction of 90°. Specifically, the copper film was pulled while sliding the fixing plate. Here, if the adhesion of the copper film to the base material of the specimen is 0.5 kN / m or less, it is determined that the adhesion strength is insufficient, and if the adhesion strength is greater than 0.5 kN / m, it is good. I decided there was. The above 0.5 kN/m is a value generally used as the threshold value of the adhesion strength of the wiring board. The results are shown in FIGS. 6-8.

[Results/Discussion]
FIG. 6 illustrates an example of the present invention, and shows the peel strength of each test piece manufactured under different manufacturing conditions for a wiring board. FIG. 6 shows the manufacturing conditions of Examples 1 to 4 and Comparative Examples 1 and 2, and the peel strength of each specimen. As is clear from FIG. 6, the test pieces according to Examples 1 to 4 all obtained peel strength exceeding the threshold value of 0.5 kN/m, which was a good result. Regarding the specimens of Examples 3 and 4, the copper particles generated by the target source collided with the surface of the substrate, bonded with the functional groups generated from the resin of the substrate, and were roughened on the substrate. This is presumably because the adhesion strength between the surface of the portion where the film was formed and the seed layer increased. Regarding the specimens of Examples 1 and 2, more oxygen-containing functional groups were attached to the surface of the roughened portion of the substrate, and the surface of the roughened portion of the substrate and the seed layer This is probably because the adhesion strength between the layers became higher. Regarding the specimens of Comparative Examples 1 and 2, since the copper seed layer was formed by electroless plating, when the seed layer was formed, copper ions entered the inside of the base resin. It is thought that high peel strength was obtained in In this case, although the peel strength between the base material and the seed layer exceeds the threshold value (0.5 kN/m), the copper ions remain inside the resin, which unfavorably lowers the insulating properties of the base material.

FIG. 7 explains an embodiment of the present invention, and shows the peel strength ratio of each test piece manufactured by changing the type of plasma irradiated to the base material as the manufacturing condition of the wiring board. be. As is clear from FIG. 7, when the roughened substrate was irradiated with H ₂ +O ₂ plasma (Example 1) and O ₂ plasma (Example 5), when the substrate was not irradiated with plasma A higher peel strength could be obtained. On the other hand, when the roughened substrate was irradiated with H ₂ plasma (Comparative Example 3), a lower peel strength was obtained than when the substrate was not irradiated with plasma. Regarding the specimens of Examples 1 and 5, more oxygen-containing functional groups were attached to the surface of the roughened portion of the substrate, and the surface of the roughened portion of the substrate and the seed layer This is probably because the adhesion strength between the layers became higher. On the other hand, for the specimen of Comparative Example 3, by irradiating the surface of the roughened substrate with H ₂ plasma, the oxygen atoms of the functional groups generated from the resin of the substrate reacted, and the surface of the substrate This is probably because the functional group attached to the was removed from the surface of the base material.

FIG. 8 illustrates an embodiment of the present invention, in which (a) shows a photograph of a plan view of a test piece, and (b) shows a manufacturing process in which the order of the heat treatment step and the cut formation step are reversed. It shows the peel strength of each specimen. As shown in FIG. 8(b), the test piece (5 mm width) according to Example 1 obtained a peel strength exceeding the threshold of 0.5 kN/m, which was a good result. On the other hand, in the test piece (5 mm width) according to Comparative Example 4, the peel strength is below the threshold of 0.5 kN/m. On the other hand, the test piece (3 mm width) according to Comparative Example 5 obtained a peel strength equivalent to that of the test piece of Example 1. From Comparative Examples 4 and 5, the test pieces prepared by performing the heat treatment step after performing the step of forming and removing the cuts had the peel strength of both ends (1 mm width) lower than that of the center It is considered that the peel strength is lower than the peel strength of the part (3 mm width). This is because the cuts are formed in the copper film and the copper seed layer before the heat treatment is performed (that is, before the adhesion strength between the seed layer and the resin is increased). The reason for this is thought to be that both ends (1 mm width) of the are floating (separated) from the base material. On the other hand, in Example 1, the cuts are formed in the copper film and the seed layer while the adhesion strength between the surface of the roughened portion of the base material and the seed layer is increased by the heat treatment. It is believed that the seed layer did not separate from the surface of the roughened portion of the substrate when the cut was formed.

11: Anode, 13: Solid electrolyte film, 20: Seed layer, 24: Notch, 30: Laser, 40: Oxygen plasma, 80: Wiring substrate, B: Base material, B1: Surface, B2: Portion where wiring layer is provided surface, B4: boundary, C: wiring layer, M: metal particles, F: metal film, F1: surface

Claims (5)

A method for manufacturing a wiring board comprising a base material and a wiring layer having a predetermined wiring pattern provided on the surface of the base material, the method comprising:
A step of preparing an insulating base material containing a resin as the base material;
a step of roughening the surface of a portion of the surface of the base material where the wiring layer is to be provided;
forming a metal-containing seed layer on the surface of the substrate by depositing metal particles generated by a target source onto the surface of the substrate;
A solid electrolyte membrane is arranged between an anode and the seed layer that is a cathode, the solid electrolyte membrane is brought into contact with the seed layer, and a voltage is applied between the anode and the seed layer to remove the solid electrolyte. forming a metal film on the seed layer by reducing metal ions contained in the film;
forming a cut in the metal coating and the seed layer from the surface of the metal coating toward the boundary between the roughened portion and the non-roughened portion on the surface of the substrate;
and physically removing, from the substrate, those portions of the metal coating and the seed layer in which the cuts are formed that are located in the non-roughened portions of the substrate. A method of manufacturing a wiring board characterized by: 2. The method of manufacturing a wiring substrate according to claim 1, wherein in said roughening step, the surface of the portion where said wiring layer is provided is roughened by a laser. 3. The wiring board according to claim 2, further comprising a step of irradiating the surface of the base material with oxygen plasma after the step of roughening and before the step of forming the seed layer. Production method. In the step of forming the seed layer, copper is used as the target source, and copper particles as the metal particles are deposited on the surface of the base material by sputtering, so that copper is contained on the surface of the base material. forming a seed layer,
After the step of forming the metal film, the step of heat-treating the base material, the seed layer, and the metal film by applying heat until the resin of the base material is softened. 4. The method for manufacturing a wiring board according to claim 3. 5. The method of manufacturing a wiring board according to claim 4, wherein the step of forming the cut and the step of removing are performed after the step of performing the heat treatment.

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