Electrical wiring component and manufacturing method thereof

Abstract

To provide an electrical wiring component that reliably ensures high insulation properties.SOLUTION: The present invention is an electrical wiring component comprising a conductor made of an Al substrate and an insulating film covering at least a portion of the conductor. The insulating film has a first layer on the surface side and a second layer on the Al substrate side relative to the first layer. The first layer has a main hole extending from the Al substrate side toward the surface side and an auxiliary hole opening into a portion of the side wall of the main hole. The second layer is thicker than the first layer. For example, the thickness of the first layer is 0.1 to 20 μm, and the thickness of the second layer is 20 to 200 μm. For example, the first layer is an anodic oxide layer obtained by electrolysis in a phosphoric acid solution, and the second layer is an anodic oxide layer obtained by electrolysis in an oxalic acid or sulfuric acid solution.SELECTED DRAWING: Figure 2C

Description

[Technical Field]

[0001] The present invention relates to an electric wiring member or the like made of an insulating coated Al-based conductor. [Background technology]

[0002] A typical example of an electromagnetic device that has an armature and a field is an electric motor (including a generator). There are various types of electric motors that have a rotor and a stator, such as rotating armature types and rotating field types. There are also inner rotor types in which the rotor rotates on the inner periphery of the stator, and outer rotor types in which the rotor rotates on the outer periphery of the stator. All electric motors have in common the fact that they have at least one coil (one application example of an electrical wiring member) built into a core.

[0003] The coils of electric motors mounted on moving bodies such as vehicles are subjected to high voltages and high currents, while also being required to be lightweight and highly efficient (low loss). To achieve these, for example, coils in which an aluminum-based conductor is insulated and coated with an anodized film are being considered. Related disclosures can be found, for example, in the following patent documents: [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2000-349320 [Patent Document 2] Patent Publication No. 2014-98200 [Patent Document 3] Patent Publication No. 2017-122271 [Patent Document 4] Patent Publication No. 2021-75763 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, an Al alloy is insulated with an anodized film having pores and a plurality of voids extending in a direction substantially perpendicular to the pores. Patent Document 1 merely uses an anodized film (insulating layer) as an insulating layer on a substrate for a thin-film solar cell (A3004 or A6061), and does not at all consider coils or the like in which the substrate itself is a conductor. Incidentally, in Patent Document 1, the anodized film that achieves the highest withstand voltage is Sample 1, which was formed using an A3004 substrate, an oxalic acid aqueous solution as the electrolyte, and an applied voltage of 80 V, and has an insulating layer thickness of 50 μm (Table 1 in Patent Document 1).

[0006] In Patent Document 2, an aluminum conductor is insulated with an anodized coating having an inner layer with a large specific surface area and an outer layer with a small specific surface area. The outer layer is provided to ensure high abrasion resistance. Incidentally, the outer and inner layers are formed by applying a high first voltage (V1: 16 to 40 V) to an aluminum substrate immersed in an aqueous sulfuric acid solution, followed by a low second voltage (V2: 3 to 14 V) (see

[0042] of Patent Document 2). Although the inner and outer layers have different pore sizes, they are considered to be composed of porous layers with basically the same morphology.

[0007] Patent Document 3 proposes an anodized coating having a first coating formed in an electrolyte containing chromic acid and a second coating formed thereafter in an electrolyte containing sulfuric acid. This anodized coating is not an insulating film but a heat insulating film provided on the piston top (substrate). For this reason, in Patent Document 3, after the anodized coating is formed, the pores in the second coating (substrate side / underlying side) are enlarged with an acidic solution, and then the pores in the first coating (surface side) are sealed.

[0008] Patent Document 4 proposes an anodic oxide film having a first oxide film formed in an electrolyte containing phosphoric acid and a second oxide film subsequently formed in an electrolyte containing sulfuric acid. This anodic oxide film is not an insulating film, but merely a base formed on the surface of an aluminum alloy molded product (A5052) to ensure bonding strength (anchor effect) with a resin (sheet). For this reason, the first oxide film is a very thin film (0.6 μm thick) formed by applying 15 V in a phosphoric acid aqueous solution, and the second oxide film is also a thin film (7.1 μm thick) formed by applying 12.5 V in a sulfuric acid aqueous solution (Example 1 of Patent Document 4).

[0009] The present invention has been made in view of the above circumstances, and has an object to provide a new electrical wiring member or the like made of an Al-based conductor. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above-mentioned problems, the inventors have discovered a new, distinctive anodic oxide film with excellent insulating properties as an example of an insulating film to be provided on an electrical wiring member. By expanding on this finding, the inventors have completed the present invention, which will be described below.

[0011] Electrical wiring components The electrical wiring member of the present invention is an electrical wiring member comprising a conductor made of an aluminum base material (referred to as "Al base material") and an insulating film covering at least a portion of the conductor, wherein the insulating film has the first layer on the surface side and the second layer on the Al base side of the first layer, the first layer having a main hole extending toward the surface side of the insulating film and a sub-hole opening into a portion of the side wall of the main hole, and the second layer is an electrical wiring member formed to be thicker than the first layer.

[0012] The insulating film of the present invention can exhibit stable insulating properties even under high-load environments (high voltage, high temperature, etc.) due to the synergistic effect of the thick second layer and the flexible first layer having main holes and sub-holes.

[0013] <<Method for manufacturing electrical wiring components, etc.>> The present invention can also be understood as a method for manufacturing an electrical wiring member. For example, when the first layer and the second layer are anodized layers (i.e., when the insulating film has a first anodized layer and a second anodized layer), the present invention may be a method for manufacturing an electrical wiring member, comprising a first electrolysis step of forming the first layer using a phosphoric acid solution, and a second electrolysis step of forming the second layer using an oxalic acid solution or a sulfuric acid solution after the first electrolysis step.

[0014] 《Electromagnetic equipment, etc.》 One application example of an electrical wiring member is a coil member. The present invention can also be understood as a coil (assembly of coil members) manufactured using the coil member, an electromagnetic device (e.g., an electric motor) equipped with the coil, or a component thereof (e.g., an armature). A specific example is an armature in which the above-mentioned coil member (e.g., a segment conductor) is inserted into a slot in a core.

[0015] The armature referred to in this specification is not limited to that used in an electric motor (including a generator). If the armature is used in an electric motor, the armature may be a stator, a rotor, or both. The electric motor may be a DC motor or an AC motor. The electric motor may also be a synchronous machine or an asynchronous machine (such as an induction machine). For example, the electrical wiring member (coil member) of the present invention may be used in the rotor of an induction machine. The induction machine may be either a squirrel-cage type or a wound type.

[0016] "others" Unless otherwise specified, "x to y" in this specification includes a lower limit value x and an upper limit value y. Any numerical value included in the various numerical values ​​or numerical ranges described in this specification may be used as a new lower limit or upper limit value to create a new range such as "a to b." Furthermore, "α to β μm" in this specification also means α μm to β μm unless otherwise specified. The same applies to other unit systems (nm, etc.). [Brief explanation of the drawings]

[0017] [Figure 1] This is an SEM image of the surface (top surface) of an insulating film (anodic oxide film). [Figure 2A] This is an SEM image of the longitudinal cross section (surface region) of the insulating film. [Figure 2B] This is an SEM image of a vertical cross section near the boundary between the first anodized layer and the second anodized layer. [Figure 2C] This is an SEM image of the longitudinal cross section (entire) of the insulating film. [Figure 3] FIG. 1 is a schematic diagram showing a cross-sectional structure of a coil member and an insulating film; DETAILED DESCRIPTION OF THE INVENTION

[0018] The contents described in this specification may apply not only to the product of the present invention but also to the method, 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 target, required performance, etc.

[0019] "conductor" The conductor is made of an Al base material with excellent electrical conductivity. Such an Al base material is, for example, pure Al (JIS A1000 series, etc.) containing 98 mass % or more, 98.5 mass % or more, 99 mass % or more, or even 99.6 mass % or more of Al. When the first layer or second layer is made of an anodized film, the Al base material should preferably contain as few components (such as Si) that interfere with the desired film morphology as possible.

[0020] The conductivity of the Al substrate is preferably, for example, 50% IACS (International Annealed Copper Standard) or more, 55% IACS or more, or even 60% IACS or more. "% IACS" refers to the electrical conductivity of annealed standard soft copper (volume resistivity: 1.7241 × 10 -8 It is a relative index (ratio) to the conductivity (100% IACS) of Ωm. The Al substrate may be a sintered material as well as an ingot material (wrought material or cast material).

[0021] 《1st and 2nd layers》 The insulating film has a first layer on the surface side and a second layer on the Al base side. The insulating film is not limited to two layers, but may have three or more layers. For convenience, this specification will explain the case where the first and second layers are made of a two-layer anodic oxide film.

[0022] (1)First layer The first layer is located on the second layer and has main pores extending to the surface and sub-pores opening on its side walls (pore walls). Because the first layer has sub-pores in addition to the main pores, it also has a high porosity. This first layer has excellent flexibility and is less likely to crack even when exposed to high-temperature environments.

[0023] The main pores are tubular (cylindrical) extending almost straight from the Al substrate side to the surface side, and the pore diameter (maximum width in the horizontal direction as seen in the vertical cross section) or opening diameter (maximum length as seen on the surface side) is, for example, 50 to 1000 nm or 150 to 350 nm.

[0024] The sub-holes have openings in the side walls of the main holes and extend in the horizontal direction (a direction substantially perpendicular to the side walls). At least some of the sub-holes may penetrate the side walls of the main holes (connecting adjacent main holes). The distribution of the sub-holes may be uniform or non-uniform along the longitudinal direction of the main holes.

[0025] At least one sub-pore may be observed within the field of view of the longitudinal cross section (side surface) of the first layer. For example, one or more, three or more, or even five or more sub-pores may be observed in the surface region (depth 1 μm × width 10 μm). Since the first layer has main pores and sub-pores at least in the surface region, its porosity is, for example, 20 to 75% or 35 to 50%.

[0026] The porosity, pore size, opening size, etc. referred to in this specification are determined by image analysis of a microscopic image of each layer (membrane) using software (e.g., Image J). For example, the porosity is determined as the ratio of the pore area (total value) to the total area within the field of view of the surface (top surface) observation image. The opening size (pore size) is determined as the average arithmetic value of the circle-equivalent diameter of each pore within the same field of view.

[0027] The field of view (evaluation range) of the observation image is not limited, but is, for example, 5 x 4 μm to 12.7 x 8.8 μm (same below). The presence (number) and shape of sub-holes may be determined by visually checking the observation image. The first layer only needs to have main holes and sub-holes in at least the surface region (for example, a region 10 μm deep from the outermost surface).

[0028] The thickness of the first layer is, for example, 0.1 to 20 μm, 1 to 16 μm, or 5 to 13 μm. The thickness of the first layer is the distance (height) from its surface to the interface with the second layer. Because it is difficult to precisely identify the interface, the thickness (film thickness) referred to in this specification is the average thickness measured with a film thickness meter unless otherwise specified. If necessary, the thickness may be determined based on an observation image or the like (the same applies hereinafter).

[0029] The first layer is, for example, an anodized layer (referred to as a first anodized layer) made mainly of aluminum oxide (Al2O3). The anodized layer may contain components or compounds (salts) derived from the composition of the electrolyte. For example, if the first anodized layer is formed using a phosphoric acid solution, a phosphate (e.g., Al-PO-based compound, Al-POH-based compound) coating may be formed on the inner surfaces of the main holes and sub-holes.

[0030] In this specification, for convenience, the surface side of the first layer (the side where the main holes are open) is also referred to as the upper side, and the opposite side (the Al substrate side) is also referred to as the lower side or bottom side. The thickness direction of the layer (film) is also referred to as the vertical direction, and the direction approximately perpendicular to that is also referred to as the horizontal direction.

[0031] (2)Second layer The second layer is formed on the Al substrate and is thicker than the first layer, ensuring high insulation.

[0032] The second layer is, for example, an anodized layer (referred to as a second anodized layer) having a dense and thin barrier layer (active layer) and a porous layer (growth layer) grown thereon. The porous layer has a regular arrangement of approximately straight micropores. The pores are usually cylindrical with the barrier layer at the bottom, and do not have small pores (sub-pores) in the pore walls. The pore diameter (maximum width in the horizontal direction as seen in the vertical cross section) is, for example, about 10 to 100 nm, or 30 to 85 nm.

[0033] The thickness of the second layer (including the thickness of the barrier layer if it is an anodized layer) is, for example, 20 to 200 μm, 25 to 150 μm, or 30 to 120 μm. The thickness of the second layer is the distance (height) from the interface with the Al substrate (barrier layer) to the interface with the first layer, and can be measured with a film thickness meter, as described above. The thickness of the barrier layer is usually about 10 to 100 nm.

[0034] (3) Interface Near the interface between the first and second layers, at least some of the main pores of the first layer may be connected to the pores of the second layer (columnar pores extending in a substantially straight tube shape from the Al substrate side). Furthermore, at least some of the pores of the second layer may extend continuously from the main pores of the first layer. Such an insulating film consisting of the first and second layers is less susceptible to cracks or the like at the interface. Furthermore, if the first and second layers are anodized layers, sealing of the second layer can be easily performed from the first layer side.

[0035] At least one interconnected or continuously elongated main pore (vertical pore of the first layer) should be present in the observation image near the interface. The proportion of such main pores should be 50% or more, 75% or more, or even 90% or more of the total number of main pores observed. The total number may be within a range that can be arbitrarily extracted in the observation image, but should be, for example, 100 or more.

[0036] (4) Sealing treatment The second layer may be subjected to a sealing treatment. This can improve the corrosion resistance and insulating properties of the insulating film. The sealing treatment may be performed depending on the type and form of the second layer (and the first layer). The second anodized layer may be sealed using a metal salt (nickel acetate, cobalt acetate, etc.), or, taking into account costs, the environment, etc., it may be sealed using heated water (or boiling water), pressurized steam, etc. When sealing is performed using boiling water, etc., the second anodized layer (pores) will contain hydrates due to a hydration reaction.

[0037] 《Third layer》 The insulating film may further have a third layer. The third layer may be the same or different from the first or second layer. When the first and second layers are anodized layers, the third layer is, for example, a resin layer formed on the first layer. The resin layer covering the first layer contributes to improving and stabilizing the insulating properties. For convenience, the present specification will be described by exemplifying the case where the third layer is a resin layer.

[0038] The resin constituting the third layer may be a thermoplastic resin or a thermosetting resin, such as polyimide, polyamideimide, polyesterimide, epoxy, polyvinylformal, polyurethane, or polyester.

[0039] The resin layer may be thinner than the first layer (and even the second layer). There are no specific restrictions on the thickness, but it may be, for example, 1 to 35 μm, 5 to 30 μm, or 10 to 20 μm. The resin may penetrate deep into the first layer, but sufficient adhesion (anchor effect) can be obtained even if it only engages with the main pores and sub-pores in the surface layer region. The resin layer (resin coating) is formed after the second layer is formed or after the sealing treatment (sealing treatment) thereof.

[0040] The resin layer is formed, for example, by applying an electrical insulating paint (varnish) to the first layer by coating, spraying, dipping, electrodeposition, etc. Depending on the type of resin, heat drying or heat curing may be carried out as appropriate.

[0041] Anodizing When the first and second layers are anodized layers (films), the anodization treatment of the Al base material is preferably performed in at least two steps. Hereinafter, an example will be explained in which the first layer (first anodized layer) is formed in the first electrolysis step (first anodized treatment) and the second layer (second anodized layer) is formed in the second electrolysis step (first anodized treatment).

[0042] (1) First electrolysis process The electrolytic solution is, for example, a phosphoric acid solution. The solution is, for example, an aqueous solution (the same applies to the second electrolysis step). The phosphoric acid concentration is, for example, 1 to 30%, 2 to 15%, or 3 to 10%. The concentration of the electrolytic solution referred to in this specification is a mass ratio to the whole unless otherwise specified. The temperature of the electrolytic solution (bath temperature) is, for example, 10 to 50°C, 20 to 40°C, or 25 to 35°C. If the concentration or bath temperature is too low, the film formation rate will be insufficient. If the concentration or bath temperature is too high, the anodized layer itself will dissolve, making film formation difficult (the same applies to the second electrolysis step).

[0043] During the energization, the current (density) or applied voltage may be constant or may vary (fluctuate). The energization may be direct current, alternating current, or superimposed AC / DC current, which is a combination of an AC component and a DC component. The waveform of the alternating current may be, for example, a sine wave, a square wave, a pulse wave, or the like. A platinum electrode, a graphite electrode, or the like is usually used as the counter electrode. This also applies to the second electrolysis step.

[0044] When the electrolysis step is performed using direct current, it is advisable to apply a high voltage of about 50 to 250 V, 75 to 200 V, or even 100 to 175 V to the Al substrate at least temporarily (in the initial or middle stages). If the applied voltage is too low throughout the entire step, it becomes difficult to form main holes and sub-holes and ensure the film formation rate, while if the applied voltage is too high, burning may occur or a non-uniform anodic oxide layer may be formed (the same applies to the second electrolysis step).

[0045] (2)Second electrolysis process The electrolyte is, for example, an oxalic acid solution or a sulfuric acid solution. Using an oxalic acid solution inhibits dissolution of the already formed first layer. In the case of an oxalic acid solution, the oxalic acid concentration is, for example, 1 to 30%, 2 to 15%, or 3 to 10%. The bath temperature is, for example, 0 to 50°C, 10 to 40°C, or 15 to 35°C. The voltage applied during direct current is, for example, about 10 to 100V, 30 to 85V, or 45 to 75V.

[0046] (3) Voltage drop treatment When transitioning from the first electrolysis step, in which a high voltage is applied to the Al substrate, to the second electrolysis step, in which a lower voltage is applied, it is advisable to terminate the first electrolysis step by lowering the applied voltage. This voltage drop treatment (also called "VD treatment") allows the barrier layer, which thickens depending on the applied voltage, to be thinned before transitioning to the second electrolysis step. This allows the initial voltage of the second electrolysis step to fall within an appropriate range, resulting in the formation of a uniform or homogeneous second layer.

[0047] When the applied voltage is reduced, the current flow is temporarily or instantaneously cut off and resumes once the barrier layer becomes thinner. This phenomenon is known as the current recovery phenomenon. A sudden voltage drop increases the time required for the current flow to be restored. Therefore, when the voltage drop is large, it is recommended to reduce the applied voltage stepwise or continuously.

[0048] When the applied voltage is decreased stepwise, the voltage step width and holding time may be uniform or non-uniform. The voltage drop width per step is, for example, about 1 to 20 V, or about 3 to 10 V. The voltage holding time per step is, for example, about 10 to 120 seconds, or about 20 to 60 seconds.

[0049] The pore size (cell size) corresponds (approximately proportional) to the applied voltage during the electrolysis process. 1f ) and the starting voltage of the second electrolysis step (V 2s ) is almost the same as (V 1f ≒V 2s ), the pore diameters of the first and second layers can be made approximately equal. In other words, it becomes possible to extend the pores of the second layer continuously from the main pores of the first layer.

[0050] For example, the voltage (V 1f ) is applied to the Al substrate at the beginning of the second electrolysis process (V 2s ) 0.8 to 1.5 times (0.8≦V 1f / V 2s ≦1.5), 0.9 to 1.3 times, or 1 to 1.1 times, the first and second layers can be smoothly connected near the boundary.

[0051] Electrical wiring components The electrical wiring member of the present invention can be of any specific form (shape or size) or purpose. One example thereof is a coil member shown in Fig. 3. In this specification, the coil member will be described by way of example where appropriate.

[0052] The electrical wiring member may be a continuous conductor or a divided conductor. The use of divided conductors improves the degree of freedom in the shape of the electrical wiring member and the space factor. One example of a divided conductor is a segment conductor (coil member) that is inserted into a slot in a core (e.g., a stator core or a rotor core). A segment conductor is connected to another segment conductor at its adjacent ends to form a coil. The ends of such a segment conductor may not have an insulating coating. Ends without an insulating film are joined (connected) by, for example, welding or deposition. The cross-sectional shape of the segment conductor may be (elliptical) circular, but a rectangular shape (particularly a roughly rectangular shape) improves the space factor.

[0053] Such segment conductors are used, for example, in armatures (particularly stators) of high-power motors for electric vehicles (including hybrid vehicles) and the like. [Example]

[0054] Assuming that segment conductors (SC) to be incorporated into the stators of motors are an example of electrical wiring members, various samples were fabricated in which an insulating film was formed on the surface of a flat plate of an Al base material (conductive material), and their insulating properties were evaluated. The present invention will be described in more detail with reference to such specific examples.

[0055] <<Sample Preparation>> (1) Test piece For samples 1 to 5 and C3 shown in Table 1, flat plates (100 mm × 50 mm × 2 mm thick) made of pure aluminum (JIS A1070) were used as test pieces (Al-based conductors), and for samples C1 and C2, flat plates (50 mm square × 2 mm thick) made of pure aluminum (JIS A1050) were used as test pieces (Al-based conductors).

[0056] Each specimen was subjected to the treatments shown in Table 1. Specimens 1 to 5 were subjected to the first anodizing treatment (first electrolysis step) and the second anodizing treatment (second electrolysis step). Specimens C1 and C2 were not subjected to the first anodizing treatment, but were subjected to only the second anodizing treatment. Specimen C3 was not subjected to either anodizing treatment, but was only resin coated.

[0057] Samples 2 to 4 and C2 were also subjected to a sealing treatment after the anodizing treatment. Furthermore, samples 3 and 4 were also subjected to a resin coating treatment (resin layer forming step) after the sealing treatment. The specific details of each treatment are as follows:

[0058] (2) Anodizing The test piece was immersed entirely in an electrolytic bath and used as the anode, and a piece of stainless steel (JIS SUS304) as the cathode. Direct current was applied while stirring the electrolytic solution. The treatment conditions are summarized in Table 1.

[0059] The concentration of the electrolyte is the mass ratio (mass%) of phosphoric acid or oxalic acid to the entire aqueous solution. The current density was measured by measuring the applied current to the treated area (15 cm2) of the masked test piece. 2 ) is the value obtained by dividing the current value (constant) passed by the

[0060] The anodizing treatment was basically carried out by constant current (density) electrolysis. Samples 1 to 4 were also subjected to a voltage drop (VD) treatment at the end of the first anodizing treatment. That is, after the current application time (12 minutes) shown in Table 1 had elapsed, the voltage was dropped from approximately 130 V to 60 V at a rate of 5 V / 30 seconds, and then held at 60 V for 1 minute. Including the VD treatment (approximately 8 minutes = 7 minutes + 1 minute), the total time for the first anodizing treatment was approximately 20 minutes. For reference, the applied voltage (final voltage V 1f ) and the applied voltage immediately after the start of the second anodizing treatment (start voltage V 2s ) are also shown in Table 1.

[0061] After the anodizing treatment, the test piece was washed with tap water and thoroughly dried in the air before being subjected to the next step.

[0062] (3) Post-processing The sealing treatment was carried out by immersing the anodized test piece for 30 minutes in ultrapure water heated to 90°C. Specifically, a beaker filled with ultrapure water was heated in a water bath with a built-in stirrer, and the test piece was placed in the beaker for the sealing treatment.

[0063] The resin coating (formation of the resin layer) was performed by spraying a photosensitive polyimide varnish (Photoneece, manufactured by Toray Industries, Inc.) onto the anodized film or the surface of the substrate, and then thermally curing the varnish by heating in an oven (200°C x 1 hour).

[0064] In this way, test pieces were obtained as Samples 1 to 5 and Samples C1 to C3 shown in Table 1. Each test piece was subjected to the following measurements, observations and tests.

[0065] <Film thickness measurement> The thickness of the first anodized layer, the second anodized layer, and the resin layer of each sample was measured using an eddy current film thickness meter (SWT-9200, manufactured by Sanko Electronics Laboratory Co., Ltd.). Measurements were taken for each treatment, and the difference was taken as the thickness of each layer. The results are shown in Table 1.

[0066] Surface Observation The surfaces of sample 1 and sample C1 were observed using a scanning electron microscope (SEM / S-5500 manufactured by Hitachi High-Technologies Corporation). The SEM images are shown in Figure 1.

[0067] The SEM images were analyzed using ImageJ (free software) to determine the size (aperture diameter) of the pores on the surface of the anodized layer. First, the maximum diameter (maximum length) of 10 randomly selected pores was measured, and the arithmetic mean value was calculated. Next, this procedure was repeated for five fields of view, and the average value for the five fields of view was taken as the aperture diameter. The aperture diameter was 160 nm for Sample 1 and 26 nm for Sample C1.

[0068] Cross-sectional observation (1) Presence or absence of sub-holes Cross sections (depth 1 μm × width 10 μm) of the surface layers of sample 1 and sample C1 were observed using an SEM. Some of the SEM images are shown together in Figure 2A. As is clear from Figure 2A, sample 1 had a thick main hole extending in a roughly straight tube shape from the Al substrate side, and thin sub-holes that penetrated into the side walls of the main hole and opened (even penetrated) the main hole. On the other hand, no such sub-holes were observed in sample C1.

[0069] (2) Anodized layer interface The cross sections of Sample 1 and Sample 5 were observed using an SEM. SEM images of the area near the boundary (interface) between the first and second anodized layers are shown together in Figure 2B. As is clear from Figure 2B, in both Sample 1 and Sample 5, the vertical pores (main pores) in the first anodized layer were connected to the vertical pores (pores) in the second anodized layer.

[0070] In particular, VD-treated sample 1 (V 1f / V 2s In ≒1), each pore in the first anodized layer was connected to each pore in the second anodized layer. In other words, each pore in the second anodized layer extended from each pore in the first anodized layer.

[0071] On the other hand, sample 5 (V 1f / V 2s In ≒2), one pore in the first anodized layer was connected to two pores in the second anodized layer. This shows that VD treatment almost completely eliminates the difference in applied voltage between anodized treatments, allowing for a smooth transition from the first anodized treatment to the second anodized treatment while the barrier layer is thin.

[0072] (3) Resin layer and hydrate The cross section of Sample 3 was observed using an SEM. SEM images of the surface and bottom layers (on the substrate side) are shown together in Figure 2C. As is clear from Figure 2C, the resin layer formed on the first anodized layer penetrated and became entangled not only in the main pores of the first anodized layer but also in the sub-pores, adhering closely to and holding the first anodized layer.

[0073] Furthermore, many hydrates were observed in the pores of the second anodized layer. On the other hand, no hydrates were observed in the first anodized layer. This is thought to be because the surface of the first anodized layer is covered with an insoluble phosphorus-based film, which inhibits the hydration reaction.

[0074] Since the main pores of the first anodized layer were not sealed even after the sealing treatment, it was possible to form a highly adhesive resin layer on the first anodized layer after the sealing treatment.

[0075] <Crack resistance> Visual inspection of the surfaces after the sealing treatment revealed no cracks in Sample 2, but cracks were found in Sample C2. Thick anodic oxide films are inherently prone to cracking due to heating during the sealing treatment. However, it is believed that the flexible first anodic oxide layer with its main and sub-holes prevented cracks from occurring even when the anodic oxide film was made thicker.

[0076] <Insulating properties> (1) Breakdown voltage A dielectric breakdown test was conducted to measure the breakdown voltage of each sample. An ultra-high voltage withstand voltage tester (7473 manufactured by Keisoku Giken Co., Ltd.) was used for the measurements. The measurement environment was a temperature of 25°C and a relative humidity of 50% RH. The test conditions were a sinusoidal AC applied voltage (50 Hz), a voltage rise rate of 50 V / s, and a breaking current of 10 mA. A 6 mm diameter hemispherical electrode was used for the high-voltage side. The dielectric breakdown test was conducted five times, and the arithmetic mean value of the voltages (n = 5) that exceeded the breaking current was taken as the breakdown voltage and is also shown in Table 1. Note that creeping discharge occurred when voltages above 4.0 kV were applied, and the breakdown voltage of such samples was indicated as "≧4.0 (kV)."

[0077] As can be seen from Table 1, insulating films having a first anodized layer and a second anodized layer exhibited a large breakdown voltage. Also, insulating films with a thick second anodized layer and insulating films that were sealed or resin-coated exhibited a larger breakdown voltage.

[0078] (2) Partial discharge inception voltage A partial discharge test was conducted to measure the partial discharge inception voltage of each sample. A partial discharge measuring device (DAC-PD-7 manufactured by Soken Denki Co., Ltd.) was used for the measurements. The measurement environment was a temperature of 24°C and a relative humidity of 33%RH. The test conditions were: applied voltage: sine wave AC (60Hz), voltage rise rate: 50V / s, and threshold discharge charge: 100pC. A φ6mm hemispherical electrode was used for the high-voltage side electrode. The partial discharge test was conducted five times, and the arithmetic mean value of the voltages (n=5) at which the discharge charge exceeded the threshold was taken as the partial discharge inception voltage. The high and low partial discharge inception voltages are also shown in Table 1, with a threshold of 1.4kV.

[0079] As can be seen from Table 1, insulating films having a first anodized layer and a second anodized layer exhibited a large partial discharge inception voltage. In particular, insulating films with a thick second anodized layer exhibited a larger partial discharge inception voltage.

[0080] From the above, it has been confirmed that the present invention can provide an electrical wiring member that stably ensures high insulation properties.

[0081] [Table 1]

Claims

1. An electrical wiring member comprising a conductor made of an aluminum base material (referred to as an "Al base material") and an insulating film covering at least a portion of the conductor, the insulating film has the first layer on the surface side and the second layer on the Al base side of the first layer, the first layer has a main hole extending toward the surface side of the insulating film and a sub-hole opening in a part of a side wall of the main hole; The second layer is thicker than the first layer.

2. 2. The electrical wiring member according to claim 1, wherein the first layer has a thickness of 0.1 to 20 μm, and the second layer has a thickness of 20 to 200 μm.

3. The electrical wiring member according to claim 1 , wherein at least a portion of the sub-hole penetrates a side wall of the main hole.

4. the second layer has pores extending in a substantially straight pipe shape from the Al base side, 2. The electrical wiring member according to claim 1, wherein at least a portion of the main holes of the first layer communicate with the pores.

5. The electrical wiring member according to claim 4 , wherein at least a portion of the pore extends continuously from the main hole.

6. The electrical wiring member according to claim 1 , wherein the insulating film further comprises a third layer.

7. 2. The electrical wiring member according to claim 1, which is a coil member.

8. 8. The electrical wiring member according to claim 7, wherein the coil member is a segment conductor inserted into a slot in a core.

9. 2. The electrical wiring member according to claim 1, wherein the Al base is pure aluminum containing 98 mass % or more of Al based on the entire Al base.

10. 10. The electrical wiring member according to claim 1, wherein the first layer and the second layer are anodized layers.

11. The electrical wiring member according to claim 10 , wherein the second layer contains a hydrate.

12. The electrical wiring member according to claim 6 , wherein the third layer is a resin layer.

13. A manufacturing method for obtaining the electrical wiring member according to claim 10, comprising the steps of: a first electrolysis step of forming the first layer using a phosphoric acid solution; a second electrolysis step of forming the second layer using an oxalic acid solution or a sulfuric acid solution after the first electrolysis step; A method for manufacturing an electrical wiring member comprising:

14. The method for manufacturing an electric wiring member according to claim 13 , wherein the first electrolysis step includes a voltage drop treatment that ends by dropping the voltage applied to the Al base.

15. The voltage (V) applied to the Al base material at the end of the first electrolysis step １ｆ )teeth, The voltage (V) applied to the Al base material at the beginning of the second electrolysis step ２ｓ ) or less than 1.5 times (V １ｆ / V ２ｓ 15. The method for producing an electrical wiring member according to claim 14, wherein the tensile strength is 1.5 or less.

16. The method for producing an electric wiring member according to claim 13, wherein a sealing treatment for the second layer and / or a coating treatment for the first layer is performed after the second electrolysis step.

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