Flat conductive plate with insulating film and its manufacturing method

Abstract

To provide an insulative coating-attached flat conductive plate covered with an insulative coating which is low in specific dielectric constant and high in hardness, and a manufacturing method thereof.SOLUTION: An insulative coating-attached flat conductive plate comprises: a flat conductive plate composed of a punched product; and an insulative coating that covers at least part of the flat conductive plate. The insulative coating is an electrodeposited film. The insulative coating contains a polyamide-imide resin and a fluorine resin, in which a content of the fluorine resin to a total content of the polyamide-imide resin and the fluorine resin is within a range of 72 mass% or more and 95 mass% or less, and of which the specific dielectric constant at 25°C is within a range of 2.2 or more and 2.8 or less, and the average film thickness is within a range of 5 μm or more and 100 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flat conductive plate with an insulating coating and a method for producing the same. [Background technology]

[0002] The flat conductive plates obtained by punching are used as motor parts such as coils, inductors, etc. The flat conductive plates used in these motor parts are usually covered with an insulating film.

[0003] An electrodeposited film is used as the insulating film (Patent Document 1). An electrodeposited film is a film formed by an electrodeposition method. The electrodeposition method is a method in which a flat conductive plate and an electrode are immersed in an electrodeposition solution in which electrically charged insulating resin particles are dispersed, and a direct current voltage is applied between the flat conductive plate and the electrode to adhere the insulating resin particles to the surface of the flat conductive plate to form an insulating film. Polyimide-based resins, which have excellent heat resistance, are widely used as materials for electrodeposited films for flat conductive plates. Patent Document 1 describes a flat conductive plate with an insulating film, which uses an electrodeposited film of a block copolymer polyimide that contains a siloxane bond in the main chain of polyimide and has an anionic group in the molecule as the insulating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-228984 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to miniaturize coils and inductors and increase their output, it has been considered to narrow the gap between flat conductive plates with insulating coating and increase the number of flat conductive plates per unit length. In order to narrow the gap between flat conductive plates with insulating coating, it is necessary to lower the relative dielectric constant of the insulating coating and increase the partial discharge inception voltage between the flat conductive plates. In addition, by lowering the relative dielectric constant of the insulating coating and increasing its hardness so that it can withstand the assembly process, it becomes possible to make the thickness of the insulating coating thinner while maintaining a predetermined partial discharge inception voltage, and it is expected that the coil volume can be reduced. However, with the polyimide-based resin used in conventional flat conductive plates with insulating coating, only insulating coatings with a relative dielectric constant exceeding 3 can be obtained.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a flat conductive plate with an insulating film that is covered with an insulating film having a low dielectric constant and high hardness, and a method for manufacturing the same. [Means for solving the problem]

[0007] As a result of extensive investigations to solve the above problems, the inventors have found that an electrodeposited film formed by electrodeposition on the surface of a punched flat conductive plate using an electrodeposition solution containing polyamideimide resin particles and fluororesin particles has a low relative dielectric constant, and in particular, an electrodeposited film having a fluororesin content in the range of 72 mass% or more and 95 mass% or less has a low relative dielectric constant of 2.8 or less and exhibits high hardness even when the average film thickness is in the range of 5 μm or more and 100 μm or less.

[0008] Therefore, the flat conductive plate with an insulating film of the present invention is a flat conductive plate with an insulating film, which has a flat conductive plate that is a punched product, and an insulating film that covers at least a part of the flat conductive plate, wherein the insulating film is an electrodeposited film, the insulating film contains a polyamideimide resin and a fluorine-based resin, the content of the fluorine-based resin relative to the total content of the polyamideimide resin and the fluorine-based resin is in the range of 72 mass% or more and 95 mass% or less, the relative dielectric constant at 25°C is in the range of 2.2 or more and 2.8 or less, and the average film thickness is in the range of 5 μm or more and 100 μm or less.The hardness of the insulating film is within a range of 2B to 4H in pencil hardness. It is characterized by:

[0009] According to the flat conductive plate with an insulating coating of the present invention, the insulating coating is an electrodeposited film and has a fluororesin content in the range of 72 mass % or more and 95 mass % or less. Therefore, the relative dielectric constant at 25°C is low, in the range of 2.2 or more and 2.8 or less, and further, even if the average film thickness is in the range of 5 μm or more and 100 μm or less, it exhibits high hardness.

[0010] Also, Because the pencil hardness of the insulating film is within the range of 2B to 4H, it can be used for motor parts such as coils and inductors even when the average film thickness is thin, at 100 μm or less.

[0011] In the flat conductive plate with an insulating coating of the present invention, the main component element of the flat conductive plate may be copper or aluminum. In this case, since the main component of the flat conductive plate is copper or aluminum, the adhesion between the flat conductive plate and the insulating film is high, and therefore the hardness of the insulating film is increased.

[0012] In addition, in the flat conductive plate with an insulating coating of the present invention, the flat conductive plate may be configured as a ring-shaped body having an opening in the center when viewed in a plane and one open portion connecting the opening to the outer periphery. In this case, since the flat conductive plate is an annular body having an opening in the center when viewed in a plane and one open portion connecting the opening to the outer periphery, it can be advantageously used as a motor component such as a coil or inductor.

[0013] The method for producing a flat conductive plate with an insulating film of the present invention is A method for producing a flat conductive plate with an insulating film, comprising the steps of:The method is characterized by comprising an electrodeposition step of electrodepositing an electrodeposition liquid containing polyamideimide resin particles and fluororesin particles on the surface of a punched flat conductor, the content of the fluororesin particles being in the range of 72% by mass or more and 95% by mass or less relative to the total content of the polyamideimide resin particles and the fluororesin particles, to obtain a flat conductor with an electrodeposition layer, and a baking step of heating the flat conductor with the electrodeposition layer at a temperature of 260°C or more and 350°C or less to bake the electrodeposition layer onto the flat conductor.

[0014] According to the manufacturing method of the present invention for a flat conductive plate with an insulating coating, an insulating coating is formed by electrodeposition using an electrodeposition solution in which the content of fluororesin particles relative to the total content of polyamideimide resin particles and fluororesin particles is in the range of 72 mass% or more and 95 mass% or less, so that it is possible to manufacture a flat conductive plate with an insulating coating that is covered with an insulating coating having a low dielectric constant and high hardness. Effect of the Invention

[0015] It is possible to provide a flat conductive plate with an insulating film that is coated with an insulating film having a low relative dielectric constant and high hardness, and a method for producing the same. [Brief description of the drawings]

[0016] [Figure 1] 1 is a plan view of a flat conductive plate with an insulating coating according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a flat conductive plate with an insulating coating and a method for producing the same according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0018] Fig. 1 is a plan view of a flat conductive plate with an insulating coating according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in FIG. 1, a flat conductive plate 1 with an insulating coating includes a flat conductive plate 10 and an insulating coating 20 that covers the flat conductive plate 10 .

[0019] The flat conductive plate 10 is a stamped product formed by stamping a metal plate. It is an annular body having an opening 11 in the center in a plan view and one open portion 12 that connects the opening 11 to the outer periphery. The flat conductive plate 10 has extensions 13a and 13b that extend to sandwich the open portion 12. The extensions 13a and 13b can be used as terminals when incorporated into a coil or inductor. For this reason, the tips of the extensions 13a and 13b do not need to be covered with the insulating coating 20.

[0020] The flat conductive plate 10 may be copper, a copper alloy, aluminum, or an aluminum alloy. The copper alloy is, for example, an alloy containing 50% or more by mass of copper. The aluminum alloy is, for example, an alloy containing 50% or more by mass of aluminum. Copper and aluminum have high adhesion to the polyamideimide resin contained in the insulating film 20. Therefore, when the main component element of the flat conductive plate 10 is copper or aluminum, the adhesion between the flat conductive plate 10 and the insulating film 20 is high.

[0021] The insulating film 20 is an electrodeposition film. An electrodeposition film is a film formed by an electrodeposition method. The electrodeposition method is a method of forming an insulating film by immersing a flat conductive plate and an electrode in an electrodeposition solution in which electrically charged insulating resin particles are dispersed, and applying a direct current voltage between the flat conductive plate and the electrode to adhere the insulating resin particles to the surface of the flat conductive plate.

[0022] The insulating film 20 contains polyamide-imide resin and fluororesin. Polyamide-imide resin has the properties of both polyamide resin and polyimide resin, and is excellent in heat resistance and has high hardness. Fluorine-based resin is a resin with high electrical insulation and low relative dielectric constant. Examples of fluorine-based resin include polytetrafluoroethylene (PTFE), perfluoroalkoxy fluorine resin (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The content of the fluorine-based resin in the insulating film 20 is within a range of 72% by mass to 95% by mass as the content of the fluorine-based resin relative to the total content of the polyamide-imide resin and the fluorine-based resin. If the content of the fluorine-based resin in the insulating film 20 is too low, the relative dielectric constant of the insulating film 20 may be high. On the other hand, if the content of the fluorine-based resin in the insulating film 20 is too high, the adhesion to the flat conductive plate 10 decreases, making it difficult to maintain the shape of the insulating film 20. From the viewpoint of the relative dielectric constant of the insulating coating 20, the fluororesin content of the insulating coating 20 is preferably 75 mass % or more, and particularly preferably 80 mass % or more. On the other hand, from the viewpoint of the stability of the shape of the insulating coating, the fluororesin content of the insulating coating 20 is preferably 93 mass % or less.

[0023] The dielectric constant of the insulating coating 20 is set to be within the range of 2.2 to 2.8. If the dielectric constant of the insulating coating 20 is too high, the insulating properties of the insulating coating 20 may decrease, and partial discharge may easily occur when the insulating coating 20 is incorporated into a coil or inductor. The dielectric constant of the insulating coating 20 is preferably 2.7 or less, and more preferably 2.6 or less. On the other hand, in order to make the dielectric constant of the insulating coating 20 2.2 or less, it is necessary to include a fluorine-based resin in an amount exceeding 95 mass%, which may decrease the stability of the shape of the insulating coating 20.

[0024] The insulating coating 20 has an average thickness within a range of 5 μm or more and 100 μm or less. When the average thickness of the insulating coating 20 is within this range, the dielectric constant can be reduced while maintaining the hardness of the insulating coating 20 at a high level. From the viewpoint of increasing the number of sheets per unit length when incorporated into a coil or inductor, the average thickness of the insulating coating 20 is preferably 90 μm or less, and more preferably 70 μm or less. On the other hand, from the viewpoint of the hardness of the insulating coating 20, the average thickness of the insulating coating 20 is preferably 10 μm or more, and more preferably 30 μm or more. In addition, the hardness of the insulating coating 20 is preferably within a range of 2B or more and 4H or less in pencil hardness.

[0025] Next, a method for manufacturing the insulating-coated flat conductive plate 1 of this embodiment will be described. The method for producing the flat conductive plate 1 with an insulating coating of this embodiment includes an electrodeposition step and a baking step.

[0026] The electrodeposition step is a step of electrodepositing an electrodeposition liquid containing polyamideimide resin particles and fluororesin particles on the surface of a flat conductor, which is a punched product, to obtain a flat conductor with an electrodeposition layer. The content of polyamideimide resin particles in the electrodeposition liquid is, for example, in the range of 0.5% by mass to 5% by mass, and preferably in the range of 1.0% by mass to 2.5% by mass. The content of fluororesin particles in the electrodeposition liquid is in the range of 72% by mass to 95% by mass as the content of fluororesin particles relative to the total content of polyamideimide resin particles and fluororesin particles. The content of fluororesin relative to the total content of polyamideimide resin particles and fluororesin particles is preferably 75% by mass or more, and particularly preferably 80% by mass or more. In addition, the content of fluororesin relative to the total content of polyamideimide resin particles and fluororesin particles is preferably 90% by mass or less.

[0027] The median diameter of the polyamideimide resin particles is preferably in the range of 150 nm to 300 nm. The median diameter of the fluororesin particles is preferably in the range of 150 nm to 300 nm. If the median diameter of the fluororesin particles exceeds 300 nm, the hardness of the insulating coating tends to decrease. The median diameter of the polyamideimide resin particles and the median diameter of the fluororesin particles are volume-based average particle diameters measured using a dynamic light scattering particle size distribution measuring device (LB-550, manufactured by Horiba, Ltd.).

[0028] The electrodeposition liquid can be prepared by mixing a dispersion of polyamideimide resin particles and a dispersion of fluorine-based resin particles. The dispersion of polyamideimide resin particles can be obtained, for example, by adding a hydrophobic base and water, which is a poor solvent for polyamideimide resin, to a polyamideimide resin varnish prepared by mixing a polyamideimide resin with an organic solvent capable of dissolving the polyamideimide resin. As the organic solvent, for example, a polar solvent such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), 1,3 dimethylimidazolidinone, dimethylsulfoxide (DMSO), or γ-butyrolactone (γ-BL) can be used. These polar solvents may be used alone or in combination of two or more. In addition, it is preferable that the hydrophobic base has an affinity for the organic solvent. Examples of hydrophobic bases include tri-n-propylamine, tri-n-butylamine, dibenzylamine, decylamine, octylamine, hexylamine, diamylamine, dihexylamine, dioctylamine triamylamine, trihexylamine, trioctylamine, tribenzylamine, and aniline. These hydrophobic bases may be used alone or in combination of two or more. The content of the organic solvent relative to the total amount of the organic solvent and water is, for example, in the range of 70% by mass to 87% by mass. The content of the hydrophobic base is, for example, in the range of 0.02% by mass to 0.1% by mass relative to the electrodeposition liquid. As the dispersion of fluororesin particles, a commercially available dispersion of fluororesin particles can be used. The polyamide resin is a negatively charged anionic resin, and from the viewpoint of dispersibility, it is preferable to use an anionic charged fluororesin.

[0029] As a method for electrodepositing an electrodeposition solution on the surface of a flat conductor to obtain an electrodeposition film, for example, a method of applying a DC voltage between the flat conductor and the electrode while the flat conductor and the electrode are immersed in the electrodeposition solution can be used. The DC voltage applied is preferably in the range of 1 V to 600 V. This causes the polyamideimide resin particles and fluorine-based resin particles in the electrodeposition solution to be electrodeposited onto the surface of the flat conductor to produce an electrodeposition film.

[0030] In the baking process, the flat conductor with the electrodeposition layer is heated to bake the electrodeposition layer onto the flat conductor. The baking temperature is set to be within the range of 260° C. to 350° C. The heating atmosphere is not particularly limited and may be an air atmosphere or an inert atmosphere.

[0031] In this manner, the flat conductive plate 1 with an insulating coating of the present embodiment can be manufactured. The obtained flat conductive plate 1 with an insulating coating can be used as a motor part such as a coil or inductor.

[0032] According to the flat conductive plate with an insulating coating 1 of this embodiment configured as described above, the insulating coating 20 is an electrodeposited film having a fluororesin content in the range of 72 mass % or more and 95 mass % or less, and therefore has a low relative dielectric constant of 2.2 or more and 2.8 or less at 25°C, and further exhibits high hardness even when the average film thickness is in the range of 5 μm or more and 100 μm or less.

[0033] Furthermore, in the flat conductive plate 1 with an insulating coating of this embodiment, when the main component element of the flat conductive plate 10 is copper or aluminum, copper and aluminum have high adhesion to the polyamideimide resin contained in the insulating coating 20, so that the adhesion between the flat conductive plate 10 and the insulating coating 20 is high. Therefore, the hardness of the insulating coating 20 becomes higher.

[0034] Furthermore, in the flat conductive plate 1 with an insulating coating of this embodiment, when the flat conductive plate 10 is an annular body having an opening 11 in the center when viewed in a plane and one open portion 12 connecting the opening 11 to the outer periphery, it can be advantageously used as a motor component such as a coil or inductor.

[0035] Furthermore, according to the manufacturing method of the flat conductive plate with an insulating coating of this embodiment, an insulating coating is formed by electrodeposition using an electrodeposition solution in which the content of fluororesin particles relative to the total content of polyamideimide resin particles and fluororesin particles is in the range of 72 mass% or more and 95 mass% or less, so that it is possible to manufacture a flat conductive plate with an insulating coating 1 that is covered with an insulating coating that has a low dielectric constant and high hardness.

[0036] Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical concept of the invention. EXAMPLES

[0037] [Example 1] (1) Preparation of polyamide-imide resin particle dispersion In a 2L four-neck flask equipped with a stirrer, a cooling tube, a nitrogen inlet tube and a thermometer, 747g of N-methyl-2-pyrrolidone (polar solvent), 298g (1.19 mol) of diphenylmethane-4,4'-diisocyanate (MDI, isocyanate component), and 227g (1.18 mol) of trimellitic anhydride (TMA, acid component) were added and heated to 130°C. Then, the mixture was reacted at a temperature of 130°C for about 4 hours to obtain a polymer (polyamideimide resin) having a number average molecular weight of 17000. Then, the polyamideimide resin synthesized above was dissolved in N-methyl-2-pyrrolidone (polar solvent) so that the concentration of the polyamideimide resin (non-volatile content) was 20% by mass, and a polyamideimide resin varnish (polyamideimide resin: N-methyl-2-pyrrolidone = 20% by mass: 80% by mass) was obtained.

[0038] 62.5 g of the polyamideimide resin varnish obtained above was further diluted with 140 g of N-methyl-2-pyrrolidone (polar solvent), and 0.5 g of tri-n-propylamine (basic compound, base) was added, and then 47 g of water was added at room temperature (25° C.) while stirring the liquid at a high speed of 10,000 rpm. As a result, 250 g of a dispersion liquid (polyamideimide resin particles: N-methyl-2-pyrrolidone: water: tri-n-propylamine = 5% by mass: 76% by mass: 18.8% by mass: 0.2% by mass) of polyamideimide resin particles with a median diameter of 160 nm was obtained.

[0039] (2) Preparation of fluororesin particle dispersion Polyflon PTFE-D (manufactured by Daikin Industries, Ltd.) with a fluororesin particle (PTFE particle):water ratio of 60% by mass:40% by mass was diluted with water to obtain a dispersion of fluororesin particles with a median diameter of 200 nm (fluororesin particles:water=30% by mass:70% by mass).

[0040] (3) Preparation of electrodeposition solution 60 g of the polyamideimide resin particle dispersion and 10 g of the fluororesin particle dispersion were mixed to obtain an electrodeposition liquid (polyamideimide resin particles: fluororesin particles: N-methyl-2-pyrrolidone: water: tri-n-propylamine = 4.3% by mass: 4.3% by mass: 65% by mass: 26.2% by mass: 0.2% by mass). The polyamideimide resin particles and fluororesin particles are solid contents, and the N-methyl-2-pyrrolidone (polar solvent), water and tri-n-propylamine (base) are dispersion media.

[0041] (4) Flat conductive plate with insulating film The electrodeposition solution prepared above was used to prepare a flat conductive plate with an insulating film. The flat conductive plate used was an annular copper plate made by punching a copper plate, which had an opening in the center and one open part that was connected to the opening from the outer periphery.

[0042] First, the electrodeposition solution prepared in (3) above was stored in an electrodeposition tank, and the temperature of the electrodeposition solution in the electrodeposition tank was set to 20°C. Next, the annular copper plate (flat conductive plate) was used as the anode, and the cylindrical copper plate inserted in the electrodeposition solution in the electrodeposition tank was used as the cathode. With a DC voltage of 100V applied between the annular copper plate and the cylindrical copper plate, the annular copper plate and the cylindrical copper plate were held in the electrodeposition solution in the electrodeposition tank for 10 seconds. As a result, an electrodeposition film was formed on the surface of the annular copper plate. Next, the annular copper plate on which the electrodeposition film was formed was left to stand in a muffle furnace at 300°C for 3 minutes and dried to obtain a copper wire on which an insulating film having a thickness of 5 μm was formed on the surface. This copper wire with an insulating film was designated as Example 1.

[0043] [Examples 2 to 39 of the present invention and Comparative Examples 1 to 7] As shown in the following Table 1, except that the material of the flat conductive plate, the type and median diameter of the fluororesin particles, and the ratio (mass ratio) of the polyamideimide resin particles to the fluororesin particles were changed, an electrodeposition solution was prepared in the same manner as in Example 1 of the present invention. Then, except that the obtained electrodeposition solution was used, a flat conductive plate with an insulating coating was produced in the same manner as in Example 1 of the present invention.

[0044] [evaluation] The following items were evaluated for Inventive Examples 1 to 39 and Comparative Examples 1 to 7. The results are shown in the following Table 1. Note that in Comparative Example 7, an insulating coating could not be formed.

[0045] [Average film thickness] The thickness (T1) of the flat conductive plate with the insulating coating was measured using a micrometer (manufactured by Mitutoyo Corporation). The thickness (T0) of the rectangular conductive plate measured in advance was subtracted from the thickness (T1) of the flat conductive plate obtained, and the obtained value was divided by 2. The obtained value [(T1-T0) / 2] was defined as the average film thickness.

[0046] [Dielectric constant] The capacitance of the insulating film was measured using an LCR meter (manufactured by Hioki E.E. Corporation). The dielectric constant was calculated from the obtained capacitance and the average thickness of the insulating film measured above. The relative dielectric constant was calculated by multiplying the calculated dielectric constant by the dielectric constant of a vacuum, ε0 (8.85×10 -12 F / m) was used to calculate the force.

[0047] [Hardness] Measurements were made in accordance with JIS-K5600-5-4:1996 (General test methods for paints - Part 5: Mechanical properties of coatings - Section 4: Scratch hardness (pencil method)). Using a commercially available pencil hardness tester, a 750g load was applied to a pencil fixed at a 45° angle, and the coating surface was moved 7mm or more at a speed of 0.5-1mm / sec to check for the presence or absence of scratches. The same operation was repeated at different locations while changing the pencil hardness, and the highest hardness at which no scratches were observed was taken as the scratch hardness of the coating.

[0048] [Breakdown voltage] The dielectric breakdown voltage was measured using a dielectric breakdown tester (manufactured by YAMAGISHI CORPORATION) in accordance with JIS-C-3216-5:2011 (Winding test methods - Part 5: Electrical characteristics).

[0049] [Partial discharge inception voltage] The two electrodes were stacked and measured using B010 manufactured by Fujikura Dia Cable Co., Ltd. The evaluation method was performed in accordance with EN50178, the EN standard for circuits.

[0050] [Table 1]

[0051] From the results in Table 1, the flat conductive plates with insulating coating obtained in Examples 1 to 39 of the present invention all had a high hardness (pencil hardness) of 2B or more, a low relative dielectric constant of 2.8 or less, and a partial discharge inception voltage of 200V or more. This means that the film thickness is unlikely to decrease due to discharge, and the insulation can be maintained for a long period of time. In contrast, the flat conductive plates with insulating coating obtained in Comparative Examples 1 and 4 to 6, in which the content of the fluororesin was 70 mass%, which is less than the range of the present invention, had a high relative dielectric constant of 2.9. On the other hand, in Comparative Example 7, in which the content of the fluororesin was 97 mass%, which is more than the range of the present invention, an insulating coating could not be obtained. In addition, the flat conductive plate with insulating coating obtained in Comparative Example 2, which had an average film thickness of 2 μm, which was thinner than the range of the present invention, had a low partial discharge inception voltage of 150V. On the other hand, the flat conductive plate with insulating coating obtained in Comparative Example 3, which had an average film thickness of 150 μm, which was thicker than the range of the present invention, had a low hardness of 3B. [Explanation of symbols]

[0052] 1. Flat conductive plate with insulating film 10 Flat conductive plate 11 Opening 12 Liberation Department 20 Insulating Film

Claims

1. A flat conductive plate with an insulating coating, comprising a flat conductive plate which is a punched product and an insulating coating which covers at least a part of the flat conductive plate, The insulating coating is an electrodeposited film, the insulating coating contains a polyamide-imide resin and a fluorine-based resin, the content of the fluorine-based resin relative to the total content of the polyamide-imide resin and the fluorine-based resin is within a range of 72% by mass or more and 95% by mass or less, The dielectric constant at 25°C is in the range of 2.2 to 2.8, The average film thickness is in the range of 5 μm to 100 μm, A flat conductive plate with an insulating film, wherein the insulating film has a pencil hardness in the range of 2B to 4H.

2. 2. The flat conductive plate with an insulating coating according to claim 1, wherein a main component element of the flat conductive plate is copper or aluminum.

3. 3. The flat conductive plate with an insulating coating according to claim 1, wherein the flat conductive plate is an annular body having an opening at the center in a plan view and one open portion connecting the opening to an outer periphery.

4. A method for producing a flat conductive plate with an insulating film according to any one of claims 1 to 3, comprising the steps of: an electrodeposition step of electrodepositing an electrodeposition solution containing polyamideimide resin particles and fluorine-based resin particles on the surface of a flat conductor which is a punched product, the content of the fluorine-based resin particles being within a range of 72% by mass or more and 95% by mass or less with respect to the total content of the polyamideimide resin particles and the fluorine-based resin particles, to obtain a flat conductor with an electrodeposition layer; and a baking step of heating the flat conductor with the electrodeposition layer at a temperature of 260° C. or higher and 350° C. or lower to bake the electrodeposition layer onto the flat conductor.

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