Conductive member and method for manufacturing same

Abstract

Provided is a conductive member comprising an Al substrate (conductor) coated with a good insulating film having excellent adhesiveness, uniformity, and the like. The present invention pertains to a conductive member comprising an aluminum substrate (Al substrate) that is at least partially coated with an insulating film. The insulating film is provided with: an anodic oxide film formed on the Al substrate; and a resin film formed on the anodic oxide film. The anodic oxide film comprises: a barrier layer on the Al substrate side; and a porous layer formed on the barrier layer. The porous layer has a substantially straight tube-shaped cylindrical part that is open on the upper surface, and a branch part located on the bottom side of the cylindrical part. The porous layer preferably has an opening diameter of 70-1000 nm on the upper surface side, and the barrier layer preferably has a thickness of 5-60 nm. Such an anodic oxide film is obtained by, for example, a voltage drop treatment in which low voltage energization is performed at the final stage of an anodic oxidation treatment (electrolysis step).

Description

Conductive Member and Method for Manufacturing the Same

[0001] The present invention relates to a conductive member and the like formed of an insulation-coated Al base material.

[0002] In order to reduce the weight of electromagnetic equipment (including motors such as generators), secure stable resources and recycle resources, aluminum (Al) is used as a base material for conductors (coils, wiring, etc.) instead of copper (Cu).

[0003] When a conductor made of an Al base material is insulation-coated with a resin film, an anodized film is provided on the underlayer to improve adhesion and the like. Unlike a plating film, an anodized film is formed by oxidation of the Al base material itself (generation of alumina), and is usually composed of a dense and thin barrier layer (active layer) and a porous layer (growth layer) grown thereon. The porous layer, which accounts for most of the anodized film, is composed of substantially straight tubular micropores opened on the surface side (upper side), so the anodized film is suitable as an underlayer for a resin film.

[0004] Descriptions of a member provided with a resin film on an anodized film (underlayer) formed on an Al base material are found, for example, in the following patent documents.

[0005] JP-A-9-3693, JP-A-2004-59997, JP-A-2013-136836, JP-A-2024-111338

[0006] Patent Document 1 relates not to a conductive member but to a building material, and performs cationic electrodeposition coating after anodizing treatment on a 6000-series aluminum alloy having low electrical conductivity but high corrosion resistance. Furthermore, after anodizing treatment with a low voltage (14 to 17 V) applied in a sulfuric acid bath (before electrodeposition coating), hot water washing accompanied by generation of hydrate (sealing treatment) is also performed.

[0007] Patent Document 2 proposes a composite coating product in which a cationic polyimide precursor solution is electrodeposited on an alumite coating provided on 1000-series aluminum, and then heated to 300°C to form a polyimide coating. However, there is no specific description at all regarding the anodizing treatment conditions according to the examples.

[0008] Patent Document 3 also describes an anionic electrodeposition coating applied to a 6000 series aluminum alloy anodic oxide film (film thickness 2-5 μm) formed using a phosphoric acid bath or oxalic acid bath, in order to improve the impact resistance and water resistance of building materials (aluminum sashes, etc.). The anodic oxide film is subjected to general constant current current (1-1.5 A / dm). ２ It is merely something that was formed in 600 to 1200 seconds.

[0009] Patent Document 4 describes a method for forming a resin layer by spray-coating a polyimide varnish onto an anodic oxide film formed by applying a constant current to pure aluminum (A1050) immersed in a phosphoric acid bath or oxalic acid bath. This anodic oxide film has main pores extending in a roughly straight tubular shape and secondary pores opening in its side walls, exhibiting an excellent anchoring effect on the resin layer (polyimide). However, the porous layer of this anodic oxide film consists of fine pores in the shape of a bottomed cylindrical body with a typical arc-shaped cross-section. Furthermore, Patent Document 4 does not describe the relationship between the thickness of the barrier layer and the opening diameter of the porous layer, nor does it describe electrodeposition coating or the like.

[0010] This invention has been made in view of these circumstances, and aims to provide a conductive member and the like having a new form of insulating film.

[0011] Through diligent research, the inventors discovered a new form of anodic oxide film suitable as a substrate for resin films, and realized a conductive member coated with an insulating film made of these films. By further developing this result, the present invention described below was completed.

[0012] <Conductive Member> (1) The present invention relates to a conductive member made of an aluminum substrate ("Al substrate") which is at least partially covered with an insulating film, wherein the insulating film comprises an anodic oxide film formed on the Al substrate and a resin film formed on the anodic oxide film, the anodic oxide film comprises a barrier layer on the Al substrate side and a porous layer formed on the barrier layer, and the porous layer is a conductive member having a substantially straight tubular portion that opens at the top and a branched portion at the bottom of the tubular portion.

[0013] The conductive member of the present invention has a branched bottom (branched portion) in the porous layer of the anodic oxide film, which serves as the base for the resin film. A large anchoring effect acts on the resin that penetrates to this branched portion, improving the retention and adhesion of the resin film. As a result, the conductive member of the present invention can exhibit stable insulation even under high voltage environments. Furthermore, the stress relaxation effect of the branched portion is expected to improve the crack resistance of the anodic oxide film.

[0014] (2) The present invention also relates to a conductive member made of an Al substrate coated with an insulating film, wherein the insulating film comprises an anodic oxide film formed on the Al substrate and a resin film formed on the anodic oxide film, the anodic oxide film comprises a barrier layer on the Al substrate side and a porous layer formed on the barrier layer, the porous layer having an aperture diameter of 70 to 1000 nm on its upper surface, and the barrier layer having a thickness of 5 to 60 nm.

[0015] In the conductive member of the present invention, the upper surface opening of the porous layer that serves as the base for the resin film is large, allowing the resin constituting the resin film to easily penetrate into the porous layer and reach deep into it. Furthermore, the barrier layer is thin in proportion to the size of the upper surface opening of the porous layer. As a result, electrodeposition coating and the like can be easily performed on the anodic oxide film without applying a high voltage, and the resin constituting the resin film can be easily drawn into the interior of the porous layer. Thus, even in the conductive member of the present invention, it is possible to improve the retention and adhesion of the resin film and, consequently, ensure excellent insulation properties.

[0016] 《Method for Manufacturing Conductive Members》 The present invention can also be understood as a method for manufacturing conductive members. For example, the present invention may be a method for manufacturing conductive members comprising an electrolytic step of forming an anodic oxide film on an Al substrate and a coating step of forming a resin film on the anodic oxide film. The electrolytic step may include, for example, a voltage drop process that ends by reducing the voltage applied to the Al substrate.

[0017] 《Other》 (1) In this specification, in a conductive member consisting of an Al substrate and an insulating film, the Al substrate side is referred to as the lower side or downward, and the insulating film side as the upper side or upward. With respect to the anodic oxide film or resin film constituting the insulating film, the upper surface is simply referred to as the "upper surface".

[0018] (2) In this specification, "x to y" includes the lower limit x and the upper limit y unless otherwise specified. Any numerical value included in the various numerical values ​​or ranges described in this specification may be used to create new lower or upper limits, such as a range "a to b". In this specification, "α to βμm" means αμm to βμm unless otherwise specified. The same applies to other unit systems (nm, etc.).

[0019] These are SEM images of the top surface and longitudinal section of the anodic oxide film for samples 11-13. These are SEM images of the top surface and longitudinal section of the anodic oxide film for samples 21-23. This is a schematic diagram illustrating the cross-sectional structure of an insulating film.

[0020] The contents described herein may apply to methods as well as objects, as appropriate. One or more components arbitrarily selected from this specification may be added to the components of the present invention. Which embodiment is best depends on the subject, required performance, etc.

[0021] 《Al Substrate》 An Al substrate (conductor) with excellent conductivity is preferably pure Al (JIS A1000 series, etc.) containing 98% or more by mass, 98.5% or more by mass, 99% or more by mass, or even 99.6% or more by mass. The less components (Si, Mg, etc.) that inhibit the homogeneous formation of the anodic oxide film, the better.

[0022] The conductivity of the Al substrate should preferably be, for example, 50% IACS (International Annealed Copper Standard) or higher, 55% IACS or higher, or even 60% IACS or higher. "% IACS" refers to the volume resistivity of annealed standard soft copper (1.7241 × 10⁻¹⁶). -８ This is a relative index (ratio) of conductivity (Ωm) to conductivity (100% IACS). The Al substrate may be a molten material (wrought or cast material) or a sintered material.

[0023] Anodized film: An anodized film has a barrier layer (active layer) formed on an Al substrate and a porous layer (growth layer) formed on the barrier layer.

[0024] The porous layer has a roughly straight, tubular section that opens at the top (upper surface). The size of this opening (referred to as the "opening diameter" regardless of its shape) is, for example, 70-1000 nm, 85-500 nm, 100-250 nm, or 115-200 nm. The larger the opening diameter, the easier it is for the resin to penetrate, improving the adhesion and retention of the resin film. However, if the applied voltage during anodizing is increased to enlarge the opening diameter, the barrier layer becomes thicker, and the applied voltage required during electrodeposition coating increases.

[0025] The porous layer may have branched sections at the bottom (underside) of its cylindrical portion. Because the branched sections have complex voids, they can enhance the anchoring effect on the invading resin and further improve the adhesion of the resin film.

[0026] Such branched sections have thicknesses (heights) of, for example, 0.1–5 μm, 0.2–3 μm, or 0.5–2 μm. As the branched sections become thinner, the anchoring effect on the resin also decreases. As the branched sections become thicker, the anchoring effect increases, but the time required for the electrolytic process increases.

[0027] The barrier layer has thicknesses of, for example, 5-60 nm, 10-55 nm, 15-45 nm, or 20-35 nm. As the barrier layer thickness increases, the applied voltage during electrodeposition coating also increases. If the barrier layer thickness is too small, the anodic oxide film may peel off from the Al substrate.

[0028] The overall thickness of the anodic oxide film is, for example, 1–20 μm, 2–10 μm, or 3–7 μm. The anodic oxide film only needs to be thick enough to stably hold the resin film, which primarily ensures insulation.

[0029] The aperture diameter as used herein is determined by image analysis of a microscopic image of the upper surface of the anodic oxide film (porous layer) using software (e.g., ImageJ). For example, it can be determined as the average arithmetic value of the maximum diameter (maximum length) of pores within the field of view of the observed image. The field of view (evaluation range) of the observed image is not specified, but for example, it is between 5 × 4 μm and 12.7 × 8.8 μm.

[0030] In this specification, since precise determination of each thickness (film thickness) is difficult, the average thickness measured by a film thickness gauge will be adopted as the standard. However, if necessary, the integral average of the height (width) obtained by analyzing the observed image (cross-section) of the film or layer will be used as the thickness.

[0031] 《Resin Film》 The resin constituting the resin film may be either a thermoplastic resin or a thermosetting resin. Its main components are, for example, polyimide, polyamide-imide, polyester-imide, epoxy, polyvinyl fomal, polyurethane, or polyester.

[0032] The thickness of the resin film is, for example, 1 to 150 μm, 3 to 100 μm, 7 to 50 μm, or 10 to 30 μm. For example, if the resin film is thin, the insulation resistance decreases. If the resin film is thick, the volume occupied by the Al substrate in the conductive member decreases. The type of resin, film thickness, etc. are appropriately selected according to the specifications of the conductive member. Both the resin film and the anodic oxide film have insulating properties, but it is generally preferable to make the resin film thicker than the anodic oxide film.

[0033] The resin film is, for example, a coating made of an electrical insulating paint (varnish). Depending on the type of resin, it may be heat-dried or heat-cured as appropriate. An electrodeposited coating in which the resin penetrates deep into the anodic oxide film (even into the branched parts) can exhibit high adhesion.

[0034] 《Electrolytic Process / Anodizing Treatment》 The anodic oxide film is obtained by applying an anodic oxidation treatment to an Al substrate (electrolytic process). By performing the anodic oxidation treatment on the Al substrate after it has been molded and processed into the desired shape, cracks in the anodic oxide film are suppressed. Details of the anodic oxidation treatment are as follows.

[0035] (1) The composition of the electrolyte is not limited as long as an anodic oxide film of the desired form is formed. The electrolyte may be an inorganic acid solution (such as an aqueous solution of phosphoric acid, an aqueous solution of sulfuric acid, or an aqueous solution of chromic acid) or an organic acid solution (such as an aqueous solution of oxalic acid).

[0036] The electrolyte concentration may be, for example, 1-30%, 2-20%, or 3-10%. Unless otherwise specified, the electrolyte concentration referred to herein is the mass percentage of the total electrolyte. The electrolyte temperature (bath temperature) may be, for example, 10-60°C or 25-40°C. If the concentration or bath temperature is too low, the film deposition rate will be insufficient. If the concentration or bath temperature is too high, film deposition will become difficult due to the dissolution of the anodic oxide film itself.

[0037] (2) The electrolysis process is carried out by applying current to an Al substrate (anode) which is at least partially immersed in the electrolyte. The electrolysis process may be carried out with direct current, alternating current, or by AC-DC superposition current, which is a combination of AC and DC components. The waveform of the AC current may be a sine wave, a square wave, a pulse wave, etc. The counter electrode (cathode) provided in the electrolyte is not limited, but may be stainless steel, platinum, graphite, etc.

[0038] The electrolysis process may be carried out by constant current or constant voltage current application, but the applied voltage and current (density) may be intentionally changed (fluctuated) during the process. For example, slope current application may be performed, in which the voltage, etc., is continuously or stepwise changed from the beginning to the middle or end of the electrolysis process.

[0039] Furthermore, after the main energization (referred to as "main energization"), a voltage drop process (also called "VD process") may be performed to reduce the applied voltage and complete the electrolysis process. This allows the barrier layer, which would normally thicken in proportion to the applied voltage during main energization, to be thinned, making it possible to achieve both securing the aperture diameter of the porous layer and thinning the barrier layer. In addition, the voltage drop process can also be used to form branched sections at the bottom of the porous layer. The thickness of the branched sections can also be controlled by adjusting the voltage drop rate during the voltage drop process. For example, it is possible to thicken the branched sections by slowing down the voltage drop rate.

[0040] Furthermore, after applying a high voltage and performing anodic oxidation, Al ２ O ３If pore widening treatment that chemically dissolves the anodic oxide film containing as a main component is performed, it is possible to thin the barrier layer while securing the opening diameter of the porous layer. The voltage drop treatment promotes the chemical dissolution by an electric field, so the barrier layer can be thinned in a shorter time than by pore widening treatment.

[0041] It should be noted that the drop of the applied voltage involves temporary or instantaneous interruption of energization, but energization is resumed as the barrier layer becomes thinner (current recovery phenomenon). When the fluctuation range of the voltage is large, reducing the applied voltage stepwise or continuously allows the barrier layer to be thinned efficiently.

[0042] The applied voltage or initial voltage for main energization may be adjusted according to the electrolyte (type, concentration, temperature, etc.). For example, when a phosphoric acid solution is used, a high voltage of about 70 to 250 V, 85 to 200 V, or 100 to 150 V may be applied to the Al base material as the applied voltage (Vi) during direct current energization. When an oxalic acid solution is used, for example, a voltage of about 25 to 125 V, 35 to 100 V, or 45 to 75 V may be applied to the Al base material as the applied voltage (Vi) during direct current energization.

[0043] The voltage (Vf) applied in the voltage drop treatment (at the final stage of the electrolysis step) may be constant or gradually reduced as long as it is lower than the voltage (Vi) applied in main energization. The range of the voltage (Vf) is, for example, 5 to 40 V, 10 to 30 V, or 15 to 25 V.

[0044] The energization time is preferably adjusted according to the desired thickness of the anodic oxide film (porous layer, barrier layer). For main energization, for example, it is performed for 1 to 30 minutes, 2 to 20 minutes, or 3 to 15 minutes. The voltage drop treatment may be performed for about 0.3 to 5 minutes, 0.5 to 3 minutes, or 1 to 2 minutes, for example.

[0045] (3) Washing After the electrolysis step, the anodic oxide film is preferably washed to remove the residual electrolyte before the coating step. The washing may be water washing with normal temperature water, or hot water washing with heated water (for example, 70 to 100°C or 75 to 90°C).

[0046] When a phosphoric acid solution is used as the electrolyte, a phosphate film (e.g., Al-P-O compounds, Al-P-O-H compounds) is formed on the inner surface of the porous layer (pores), preventing pore sealing by hydrates even when washed with hot water.

[0047] 《Painting Process》 The resin film can be formed by a painting process in which an insulating resin coating is applied almost uniformly onto the anodic oxide film. The painting process can be carried out by spray coating, dipping, electrodeposition, etc. Depending on the type of resin, heating drying or heat curing may be performed as appropriate.

[0048] When the coating process is performed by electrodeposition coating, a resin film with excellent adhesion and retention to the anodic oxide film can be uniformly formed (electrodeposition process). The voltage applied to the Al substrate (anodic oxide film) during electrodeposition coating is, for example, 20 to 400V, 30 to 300V, or 50 to 200V. This applied voltage should be higher than the final voltage applied in the anodic oxidation process (electrolytic process).

[0049] The temperature of the electrodeposition coating can be, for example, 10 to 50°C or 20 to 40°C. The coating time is adjusted according to the desired thickness of the resin film and the applied voltage, but can be, for example, 0.5 to 10 minutes or 1 to 3 minutes.

[0050] Electrodeposition coating may be performed using either anionic or cationic paints. Electrodeposition coating using anionic paint with an Al substrate (anodic oxide film) as the anode makes it easier to avoid peeling or erosion of the anodic oxide film. The resin film obtained using anionic paint is appropriately referred to as an anionic electrodeposition coating film.

[0051] 《Conductive Materials》 The specific use and form (shape or size) of conductive materials are not specified. Conductive materials are used, for example, in various wiring and coils. Coils may be formed from continuous conductive materials or from divided conductive materials. Using divided conductive materials can improve the degree of freedom in coil shape and the space utilization rate. One example of this is a segment conductor that is fitted into the slots of a core (e.g., a stator core or rotor core). Segment conductors are used, for example, in the armature (especially the stator) of high-power motors such as electric vehicles (including hybrid vehicles).

[0052] Various samples were fabricated by forming an insulating film on the surface of an Al substrate (conductor), and their structures were evaluated. The present invention will be explained in more detail with reference to such specific examples.

[0053] 《Preparation of Samples》 (1) Test Piece A flat plate made of pure aluminum (JIS A1070) (100 mm × 50 mm × 2 mm thick / Al base material) was used as the test piece. A portion of the plate was masked to the surface to be treated (60 mm × 25 mm = 15 cm) ２ )

[0054] The treated surface was subjected to anodizing (electrolytic process) and electrodeposition coating (coating process) under the conditions shown in Table 1 to obtain samples 11-13 and 21-23. The details are as follows.

[0055] (2) The anodized specimen and the stainless steel piece (JIS SUS304) were immersed in an electrolytic cell, with the specimen as the anode and the stainless steel piece as the cathode, and direct current was applied while stirring the electrolyte. An aqueous solution of phosphoric acid or oxalic acid was used as the electrolyte. The concentrations shown in Table 1 are the mass percentage (mass%) of phosphoric acid or oxalic acid relative to the total aqueous solution.

[0056] As shown in Table 1, direct current flow involved two processes: main current flow (slope current flow), in which the applied voltage between electrodes was linearly reduced from an initial voltage (Vi) to a final voltage (Vf) over a predetermined period of time; and voltage drop (VD) processing, in which the final voltage (constant) was maintained for a predetermined period of time after reaching the final voltage. Samples 13 and 23 underwent only main current flow and did not undergo VD processing.

[0057] (3) After the cleaning and anodizing treatment, the specimens were washed with water and thoroughly dried in the air. The specimens of sample 12 and sample 22 shown in Table 1 were further washed by immersion in 80°C pure water for 5 minutes before electrodeposition coating.

[0058] (4) Electrodeposition coating: Using an anionic epoxy-modified resin electrodeposition coating, the test specimens (surfaces to be treated) after anodizing were subjected to the electrodeposition coating shown in Table 1. In this process, the test specimen was used as the anode and the stainless steel piece described above was used as the cathode.

[0059] After electrodeposition coating, the test specimens were thoroughly washed with water and dried in an air atmosphere by heating in a furnace (100°C for 15 minutes). Then, the electrodeposited coating was further cured by heating in an air atmosphere in a furnace (180°C for 30 minutes). In this way, a resin film was formed on the anodic oxide film.

[0060] 《Film Thickness Measurement》 The film thickness of the treated surface was measured using an eddy current film thickness gauge (SWT-9200, manufactured by Sanko Electronics Laboratory Co., Ltd.) after anodizing and electrodeposition coating. The measurement after anodizing was defined as the film thickness of the anodized film, and the difference between the measurement after electrodeposition coating and the measurement after anodizing was defined as the film thickness of the resin film. The respective film thicknesses obtained in this way are shown in Table 1.

[0061] 《Surface Observation》 (1) Anodized Film The surface (top surface) of each anodized film was observed using a scanning electron microscope (SEM / Hitachi High-Tech Corporation S-5500). The SEM images of each surface were analyzed using ImageJ (free software) to determine the size of the openings (aperture diameter) on the surface of the anodized film. Specifically, first, the maximum diameter (maximum length) of about 10 randomly selected holes was measured, and their arithmetic mean was calculated. Next, this operation was performed for 5 fields of view, and the average value of the 5 fields of view was taken as the aperture diameter. The aperture diameters of each sample are shown in Table 1.

[0062] (2) The surface of each resin film was observed using an optical microscope (OM / MVX10 manufactured by Olympus Corporation) to evaluate the quality of the appearance of the resin film (electrodeposited coating) (presence or absence of defects such as pinholes). The results are also shown in Table 1.

[0063] 《Cross-sectional observation》 The longitudinal cross-section of the anodic oxide film was observed using the SEM described above. In all cases, a porous layer and a barrier layer were confirmed. The porous layer mainly consisted of a nearly straight tubular section. In the anodic oxide film treated with VD, branched sections were formed between the porous layer and the barrier layer.

[0064] Each SEM image was analyzed using ImageJ (free software) to determine the thickness of the branched regions and barrier layer. Specifically, the thickness was measured at five arbitrarily selected locations, and the arithmetic mean of these measurements was used as the overall thickness. These results are shown in Table 1.

[0065] SEM images of the top surface (surface of the porous layer) and longitudinal sections (upper and lower) of each anodic oxide film are shown in Figures 1A and 1B (collectively referred to as "Figure 1").

[0066] 《Evaluation》 (1) As can be seen from Table 1 and Figure 1, the resin film formed on an anodized film with a large opening on the surface (e.g., aperture diameter ≥ 70 nm) and a sufficiently thin barrier layer (e.g., thickness ≤ 60 nm) had sufficient thickness (e.g., film thickness ≥ 10 μm) and was in good condition without defects.

[0067] On the other hand, in anodic oxide films with thick barrier layers, such as those in sample 13 and sample 23, the electrical resistance was high, making current flow difficult, and thus electrodeposition coating was practically impossible. Furthermore, in the anodic oxide film of sample 21, even though the barrier layer was thin, the openings in the porous layer were small, making it difficult for the electrodeposition paint to penetrate the porous layer. This resulted in high electrical resistance, and a resin film of sufficient thickness could not be obtained.

[0068] (2) In sample 12, where a phosphoric acid solution was used as the electrolyte, the hydration reaction was suppressed by the insoluble phosphorus-based film formed on the surface of the anodic oxide film. As a result, the porous layer was not sealed by hydrates even after washing with hot water, and a good resin film was formed on the anodic oxide film.

[0069] On the other hand, in sample 22, where oxalic acid solution was used as the electrolyte, the porous layer of the anodic oxide film was sealed by hydrate, and therefore a good resin film could not be formed.

[0070] 《Discussion》 Figure 2 schematically shows an anodic oxide film having a branched portion at the bottom (below) of the porous layer, as in sample 11 and sample 12. It is thought that such a branched portion was formed by the voltage drop treatment described above.

[0071] Furthermore, by performing a main current application with a high initial voltage (Vi) and a voltage drop process with a low final voltage (Vf), it is believed that a high level of balance was achieved between expanding the openings in the porous layer and thinning the barrier layer.

[0072]

Claims

1. A conductive member made of an aluminum substrate ("Al substrate") which is at least partially covered with an insulating film, wherein the insulating film comprises an anodic oxide film formed on the Al substrate and a resin film formed on the anodic oxide film, the anodic oxide film comprises a barrier layer on the Al substrate side and a porous layer formed on the barrier layer, and the porous layer has a substantially straight tubular portion with an opening at the top and a branched portion at the bottom of the tubular portion.

2. The conductive member according to claim 1, wherein the branched portion has a thickness of 0.1 to 5 μm.

3. A conductive member comprising an Al substrate coated at least partially with an insulating film, wherein the insulating film comprises an anodic oxide film formed on the Al substrate and a resin film formed on the anodic oxide film, the anodic oxide film comprising a barrier layer on the Al substrate side and a porous layer formed on the barrier layer, the porous layer having an aperture diameter of 70 to 1000 nm on its upper surface, and the barrier layer having a thickness of 5 to 60 nm.

4. The conductive member according to claim 3, wherein the resin film is an electrodeposited coating film.

5. The conductive member according to any one of claims 1 to 4, wherein the anodic oxide film has a thickness of 1 to 20 μm.

6. The conductive member according to any one of claims 1 to 4, wherein the Al substrate contains 98% by mass or more of Al in its entirety.

7. A manufacturing method for obtaining a conductive member according to any one of claims 1 to 4, comprising an electrolytic step of forming an anodic oxide film on an Al substrate and a coating step of forming a resin film on the anodic oxide film, wherein the electrolytic step includes a voltage drop process that ends by reducing the voltage applied to the Al substrate.

8. The method for manufacturing a conductive member according to claim 7, wherein the electrolysis step is performed using a phosphoric acid solution.

9. The method for manufacturing a conductive member according to claim 8, wherein the anodic oxide film is washed with hot water before the painting step.

10. The method for manufacturing a conductive member according to claim 7, wherein the painting step is an electrodeposition step in which electrodeposition coating is performed.

11. The method for manufacturing a conductive member according to claim 10, wherein the electrodeposition step is performed using an anionic paint.

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