ELECTRO-SEALING LIQUID AND METHOD FOR THE PRODUCTION OF AN INSULATING COATING FILM

Abstract

An electrodeposition dispersion for the electrodeposition of an electrodeposition film onto a substrate with conductive properties by anionic electrodeposition, wherein the electrodeposition dispersion comprises: water; an organic solvent; a solid component; a neutralizing agent; and an organic acid, wherein the solid component comprises at least one polyimide resin. A method for producing an insulating film for forming an insulating film on the surface of a substrate, wherein the method comprises: An electrodeposition film formation step (S02) for the formation of an electrodeposition film on the support by immersing the support and a counter electrode in the electrodeposition dispersion as described above, and the application of a voltage between the anode and the cathode, with the support as the anode and the counter electrode as the cathode; and a burn-in step (S03) for burning in the electrodeposition film.

Description

TECHNICAL AREA

[0001] The present invention relates to an electrodeposition dispersion used for the electrodeposition of an electrodeposition film on a substrate with conductive properties by anionic electrodeposition, and to a method for producing an insulating film.

[0002] The present application claims priority over Japanese patent application No. 2023-070843, filed on April 24, 2023, and Japanese patent application No. 2024-017133, filed on February 7, 2024, the contents of which are incorporated herein by reference. STATE OF THE ART

[0003] An insulated conductor, in which a carrier with conductive properties is coated with an insulating film consisting of an insulating resin, is frequently used as a conductive material or as a heat dissipation plate material for various types of electrical equipment that require insulation.

[0004] Various resins are used as components of the insulating film, and for example, patent document 1 discloses the use of a polyimide resin such as a polyamide-imide resin, and patent document 2 proposes the use of a mixed resin consisting of a polyimide resin and a fluoropolymer resin.

[0005] A method for forming the insulating film, which consists of such an insulating resin, on a surface of the substrate with conductive properties is known as an electrodeposition method.

[0006] In the electrodeposition process, the substrate on which the insulating film is to be formed and a counter electrode are immersed in the electrodeposition dispersion in which the insulating film materials are dispersed. A voltage is applied between the substrate and the counter electrode to deposit the insulating film materials onto the surface of the substrate, thus forming the electrodeposition film. The resulting electrodeposition film is then heated to fuse it to the substrate, thus forming the insulating film.

[0007] Furthermore, examples of the electrodeposition process include an anionic electrodeposition process, in which a voltage is applied to the support as the anode to form the insulating film on the surface of the support, and a cationic electrodeposition process, in which a voltage is applied to the support as the cathode to form the insulating film on the surface of the support. Reference list of patent specifications Patent document 1: Unexamined Japanese patent application, first publication no. 2017-115120 Patent document 2: Unexamined Japanese patent application, first publication no. 2018-070663 SUMMARY OF THE INVENTION Technical Task

[0008] An anionic electrodeposition dispersion, used in the anionic electrodeposition process, contains a solid component comprising the resin described above, water, an organic solvent, and a neutralizing agent. The pH is lowered near the surface of the anode (support) by applying a voltage, the solid component is deposited on the surface of the anode (support), and the electrodeposition film is formed.

[0009] If the electrodeposition film formed on the surface of the anode is baked on, there is a risk that fine cracks will form and the insulating properties of the insulating film will no longer be guaranteed.

[0010] The present invention was made in view of the circumstances described above, and an objective of the present invention is to provide an electrodeposition dispersion with which the occurrence of fine cracks can be suppressed in a case in which an electrodeposition film is baked on and an insulating film with excellent insulating properties can be formed, and to provide a method for forming an insulating film using the electrodeposition dispersion. Solution to the task

[0011] As a result of intensive studies carried out by the present inventors to achieve the above-described objective, it was found that the fine cracks that occur when the electrodeposition film is baked on are caused by an insufficient amount of an organic solvent contained in the electrodeposition film, but the insufficient amount of organic solvent contained in the electrodeposition film can be remedied by adding a suitable amount of an organic acid to the electrodeposition dispersion.

[0012] Therefore, it was found that in a case where a suitable amount of organic acid is added to the electrodeposition dispersion, the amount of organic solvent contained in the electrodeposition film is optimized in a case where the solid component is deposited on the surface of the anode (support), and the occurrence of fine cracks during firing can be suppressed.

[0013] The present invention was made on the basis of the above-described findings, and one aspect 1 of the present invention relates to an electrodeposition dispersion for the electrodeposition of an electrodeposition film on a substrate with conductive properties by anionic electrodeposition, wherein the electrodeposition dispersion comprises: water; an organic solvent; a solid component comprising at least one polyimide resin; a neutralizing agent; and an organic acid.

[0014] Since the electrodeposition dispersion according to aspect 1 of the present invention contains the organic acid, the amount of organic solvent contained in the electrodeposition film can be adjusted by a pH-buffering effect of the organic acid and an effect that influences the compatibility between the resin and the organic solvent. That is, it is possible to suppress a rapid drop in pH near the surface of the anode (the support) and to allow the electrodeposition film to contain a sufficient amount of the organic solvent. In this way, the formation of fine cracks during the firing of the electrodeposition film can be suppressed, and the insulating film can be formed with high insulating properties.

[0015] Aspect 2 of the present invention is the electrodeposition dispersion according to aspect 1 of the present invention, wherein the organic acid comprises one of the following acids: formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid, or hydroxybutyric acid. Furthermore, hydroxypropionic acid, hydroxybutyric acid, and the like exhibit effects independent of the position of the functional group, so that the positional isomers also produce the effect.

[0016] Since the electrodeposition dispersion according to aspect 2 of the present invention contains the organic acid, it is possible to reliably suppress a rapid drop in pH near the surface of the anode (support) and to allow the electrodeposition film to contain the organic solvent in sufficient quantity so that the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed.

[0017] An aspect 3 of the present invention is the electrodeposition dispersion according to aspect 1 or 2 of the present invention, wherein the organic acid is two or more organic acids selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid and hydroxybutyric acid.

[0018] Since the electrodeposition dispersion according to aspect 3 of the present invention contains two or more organic acids, it is possible to effectively suppress a rapid pH drop near the surface of the anode (the support) and to allow the electrodeposition film to contain the organic solvent in sufficient quantity so that the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed.

[0019] An aspect 4 of the present invention is the electrodeposition dispersion according to one of aspects 1 to 3 of the present invention, wherein the organic acid comprises a hydroxy acid.

[0020] In the electrodeposition dispersion according to aspect 4 of the present invention, since the organic acid contains the hydroxy acid, it is possible to effectively suppress a rapid drop in pH near the surface of the anode (the support) and to enable the electrodeposition film to contain the organic solvent in sufficient quantity, and thus the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed.

[0021] An aspect 5 of the present invention is the electrodeposition dispersion according to one of aspects 1 to 4 of the present invention, wherein the concentration of the organic acid is in a range of 5 mg / L or more and 500 mg / L or less.

[0022] In the electrodeposition dispersion according to aspect 5 of the present invention, since the concentration of the organic acid is in a range of 5 mg / L or more and 500 mg / L or less, a suitable pH buffering effect can be exerted, the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed, and the electrodeposition film can be formed stably.

[0023] An aspect 6 of the present invention is the electrodeposition dispersion according to one of aspects 1 to 5 of the present invention, wherein the ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is in a range of 5 or more and 500 or less.

[0024] In the electrodeposition dispersion according to aspect 6 of the present invention, since the ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is in a range of 5 or more and 500 or less, the occurrence of fine cracks during firing can be suppressed by the action of the organic acid without impairing the effect of the neutralizing agent.

[0025] An aspect 7 of the present invention is the electrodeposition dispersion according to one of aspects 1 to 6 of the present invention, wherein the solid component further comprises a fluorinated resin.

[0026] Since the electrodeposition dispersion according to aspect 7 of the present invention contains the fluorinated resin together with the polyimide resin as a solid component, it is possible to form the insulating film with particularly good insulating and dielectric properties. Furthermore, since it is more difficult to suppress cracks in the electrodeposition film containing the fluorinated resin than in the case of a single polyimide resin, the addition of the organic acid is effective.

[0027] An aspect 8 of the present invention is a method for producing an insulating film for forming an insulating film on the surface of a support, wherein the method for producing an insulating film comprises: an electrodeposition film formation step for forming an electrodeposition film on the support by immersing the support and a counter electrode in the electrodeposition dispersion according to one of aspects 1 to 7 and applying a voltage between the anode and the cathode, wherein the substrate serves as the anode and the counter electrode as the cathode; and a firing step for firing the electrodeposition film.

[0028] Since the method for producing an insulating film according to aspect 8 of the present invention includes the electrodeposition film formation step of forming an electrodeposition film using the electrodeposition dispersion according to one of aspects 1 to 7 of the present invention and the curing step of curing the electrodeposition film, it is possible to suppress the occurrence of fine cracks in the electrodeposition film in the curing step and to produce the insulating film with excellent insulating properties in a stable manner. Advantageous effects of the invention

[0029] According to the present invention, it is possible to provide the electrodeposition dispersion with which the occurrence of fine cracks can be suppressed when the electrodeposition film is baked on and the insulating film with excellent insulating properties can be formed, and it is also possible to provide the method for producing an insulating film using the electrodeposition dispersion. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] A flowchart showing a process for producing an insulating film using an electrodeposition dispersion according to an embodiment of the present invention. DESCRIPTION OF THE EXECUTION FORMS

[0030] Below, an electrodeposition dispersion and a method for producing an insulating film according to an embodiment of the present invention are described.

[0031] The electrodeposition dispersion according to the present embodiment is used in a case in which an electrodeposition film, serving as a precursor to an insulating film, is formed on a surface of a substrate with conductive properties.

[0032] In the present embodiment, the electrodeposition dispersion is used in an anionic electrodeposition process in which a voltage is applied to the support as the anode and an insulating film is formed on the surface of the support, which is the anode.

[0033] The electrodeposition dispersion according to the present embodiment contains water, an organic solvent, a solid component, a neutralizing agent and an organic acid.

[0034] In the electrodeposition dispersion according to the present embodiment, the electrodeposition dispersion contains, as described above, an amine as a neutralizing agent, since the electrodeposition dispersion is used in the anionic electrodeposition process.

[0035] In the present embodiment, the solid component comprises at least one polyimide resin, and it is preferred that the solid component comprises two types of resins, namely a polyimide resin and a fluoropolymer resin.

[0036] In the present embodiment, examples of the polyimide resin include polyamideimide, polyetherimide, polyimide, and the like. Furthermore, examples of the fluoropolymer resin include polytetrafluoroethylene, perfluoroalkoxyalkane, and the like.

[0037] Furthermore, the average particle diameter of the solid component need only be 50 nm or more and 500 nm or less, preferably 50 nm or more and 450 nm or less, and even more preferably 50 nm or more and 300 nm or less. In addition, the standard deviation of the particle diameter of the solid component needs only be 250 nm or less, preferably 150 nm or less, and even more preferably 100 nm or less.

[0038] The polyimide resin and the fluoropolymer, which are the solid components, are dispersed in the water and the organic solvent.

[0039] Examples of the organic solvent are N,N-dimethylacetamide, propylene carbonate, dimethyl sulfoxide, N,N-dimethylformamide, γ-butyrolactone, N-methyl-2-pyrrolidone, N-methyl-2-pyrrolidone and the like.

[0040] Furthermore, the water content in the electrodeposition dispersion is preferably 15% by weight or more, and more preferably 50% by weight or more. In addition, the water content in the electrodeposition dispersion is preferably 85% by weight or less, and more preferably 75% by weight or less.

[0041] Furthermore, the organic solvent content in the electrodeposition dispersion is preferably 15% by weight or more, and more preferably 50% by weight or more. Additionally, the organic solvent content in the electrodeposition dispersion is preferably 85% by weight or less, and more preferably 75% by weight or less.

[0042] The organic acid has a pH-buffering effect and influences the compatibility between the resin as a solid component and the organic solvent. By adjusting the material and the concentration of the organic acid, the amount of organic solvent contained in the electrodeposition film can be controlled.

[0043] The organic acid preferably comprises one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid or hydroxybutyric acid, and the organic acid preferably comprises two or more of these.

[0044] Furthermore, it is preferred that the organic acid includes a hydroxy acid. Examples of hydroxy acids are glycolic acid, hydroxypropionic acid, hydroxybutyric acid, tartronic acid, glyceric acid, and the like. Moreover, hydroxypropionic acid, hydroxybutyric acid, and the like exhibit effects independent of the position of the functional group, so that positional isomers also show this effect.

[0045] In the present embodiment, the concentration of the organic acid contained in the electrodeposition dispersion is preferably in the range of 5 mg / L or more and 500 mg / L or less. When the organic acid concentration is set to 5 mg / L or more, the pH buffering effect can be sufficiently demonstrated, the organic solvent is adequately absorbed into the electrodeposition film, and the formation of fine cracks during curing can be effectively suppressed. Conversely, when the organic acid concentration is set to 500 mg / L or less, it is possible to prevent blistering and a decrease in Coulombic efficiency due to an excess of organic solvent absorbed into the electrodeposition film, and efficient electrodeposition film formation is achieved.

[0046] The concentration of the organic acid contained in the electrodeposition dispersion is preferably 10 mg / L or more, and even more preferably 20 mg / L or more. Furthermore, the concentration of the organic acid contained in the electrodeposition dispersion is preferably 100 mg / L or less, and even more preferably 50 mg / L or less.

[0047] In the present embodiment, the ratio A / B between a concentration A mg / L of the neutralizing agent and a concentration B mg / L of the organic acid is preferably in the range of 5 or more and 500 or less. There is concern that the organic acid could undergo an acid-base reaction with the neutralizing agent, which contains an amine compound, potentially hindering the process by which the neutralizing agent ionizes the resin. Therefore, the ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is preferably in the range described above to reliably demonstrate the respective effect. If the ratio A / B is less than 5, the ionization effect of the resin by the neutralizing agent is impaired, and consequently, so is the stability of the liquid.If the A / B ratio exceeds 500, the organic acid will not have the desired effect, and cracks may occur in the film.

[0048] The ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is preferably 20 or more, and more preferably 50 or more. Furthermore, the ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is preferably 400 or less, and more preferably 200 or less.

[0049] Next, the method for producing an insulating film using the electrodeposition dispersion according to the present embodiment will be described with reference to Fig. 1 described.

[0050] As in Fig.As shown in Figure 1, the method for producing an insulating film in the present embodiment comprises a surface pretreatment step S01, an electrodeposition film formation step S02 and a baking step S03. (Surface pretreatment step S01)

[0051] First, the substrate on which the formation of an electrodeposition film (insulating film) is to take place is prepared. This substrate has conductive properties and consists, for example, of a metallic material such as copper, a copper alloy, aluminum, or an aluminum alloy.

[0052] Then the surface of the carrier described above is treated with a surface treatment fluid such as an organic solvent or a surfactant to remove the adhering oil and grease or an oxidized film. (Electrode deposition film formation step S02)

[0053] Next, the support and a counter electrode are immersed in the electrodeposition dispersion according to the present embodiment, and a voltage is applied between the anode (support) and the cathode (counter electrode), with the support acting as the anode and the counter electrode as the cathode. This lowers the pH of the electrodeposition dispersion near the support, and the solid component (in the present embodiment, a mixture of polyimide resin and the fluorinated resin) is deposited on the surface of the support. As a result, the electrodeposition film forms on the surface of the support. Since, in this case, the organic acid is added to the electrodeposition dispersion in the present embodiment, the organic solvent is sufficiently incorporated into the electrodeposition film due to the pH-buffering effect of the organic acid.

[0054] The temperature (liquid temperature) of the electrodeposition dispersion in the electrodeposition film formation step S02 is preferably set so that it is in a range of 5°C or higher and 35°C or lower.

[0055] Setting the liquid temperature to 5°C or higher prevents water from being mixed into the electrodeposition dispersion through condensation. Conversely, setting the liquid temperature to 35°C or lower improves the storage stability of the electrodeposition dispersion and allows for the stable formation of the electrodeposition film.

[0056] The voltage applied between the support (anode) and the counter electrode (cathode) in the electrodeposition film formation step S02 is preferably in the range of 10 V or more and 600 V or less.

[0057] Setting the applied voltage to 10 V or more ensures a certain electrodeposition rate and improves productivity. Conversely, setting the applied voltage to 600 V or less suppresses the formation of numerous bubbles on the substrate surface, and in the subsequent curing step S03, it suppresses the occurrence of a large number of irregular structures in the insulating layer caused by bursting bubbles. (Burning step S03)

[0058] In the curing step S03, the support on which the electrodeposition film containing the solid component (in the present embodiment the mixture of the polyimide resin and the fluorinated resin) is formed in the electrodeposition film formation step S02 is dried, for example, in a temperature range of 200°C or higher and equal to or lower than a melting point of the solid component, the residual electrodeposition dispersion is removed, and then the electrodeposition film is cured onto the support to form the insulating film.

[0059] The curing temperature in curing step S03 can be any temperature range within which the formation of an electrodeposition film of the solid component (in the present embodiment, the mixture of the polyimide resin and the fluorinated resin) and the formation of an insulating film on the substrate occur, and need only be, for example, within a range of 200°C or more and 400°C or less. Furthermore, the curing time need only be, for example, within a range of 0.5 minutes or more and 60 minutes or less.

[0060] The steps described above allow the insulating film containing the solid component (in the present embodiment, the mixture of polyimide resin and fluoropolymer) to be formed on the substrate with conductive properties. This suppresses the formation of fine cracks during curing and results in an insulating film with good insulating properties.

[0061] Since the electrodeposition dispersion according to the present embodiment with the composition described above contains the organic acid, the amount of organic solvent contained in the electrodeposition film can be adjusted by the pH-buffering effect of the organic acid and by influencing the compatibility between the resin and the organic solvent, so that the occurrence of fine cracks in a case where the electrodeposition film is baked on can be suppressed, and the insulating film with high insulating properties can be formed.

[0062] If the electrodeposition dispersion according to the present embodiment contains any of the following as an organic acid: formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid or hydroxybutyric acid, a rapid drop in pH near the surface of the anode (the support) can be reliably suppressed, so that the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed.

[0063] Furthermore, in a case where the electrodeposition dispersion according to the present embodiment contains two or more selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid and hydroxybutyric acid, a rapid drop in pH near the surface of the anode (support) can be further effectively suppressed, and the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed.

[0064] Furthermore, in a case where the organic acid contains the hydroxy acid, a rapid drop in pH near the surface of the anode (support) can be further effectively suppressed, and the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed.

[0065] If the concentration of the organic acid contained in the electrodeposition dispersion according to the present embodiment is 5 mg / L or more, the pH buffering effect of the organic acid is reliably evident, and the occurrence of cracks during the curing of the electrodeposition film can be sufficiently suppressed. Conversely, if the concentration of the organic acid is 500 mg / L or less, the excessive effect of the pH buffering is suppressed, and the electrodeposition film can be efficiently formed without causing blistering.

[0066] In the electrodeposition dispersion according to the present embodiment, in a case where the ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is in a range of 5 or more and 500 or less, the content of the neutralizing agent is ensured, and the occurrence of fine cracks during curing can be suppressed by the pH-buffering effect of the organic acid without impairing the effect of the neutralizing agent.

[0067] If the electrodeposition dispersion according to the present embodiment contains the fluorinated resin together with the polyimide resin as a solid component, the formation of an electrodeposition film consisting of the mixed resin of the polyimide resin and the fluorinated resin and the formation of an insulating film with particularly excellent insulating properties can take place.

[0068] Since the method for producing an insulating film according to the present embodiment includes the electrodeposition film formation step S02 for forming the electrodeposition film on the support by immersing the support and the counter electrode in the electrodeposition dispersion according to the present embodiment and applying a voltage between the anode and the cathode with the support as the anode and the counter electrode as the cathode, and the curing step S03 of curing the electrodeposition film, it is possible to suppress the occurrence of fine cracks in the electrodeposition film in the curing step S03, and it is possible to produce the insulating film with excellent insulating properties in a stable manner.

[0069] The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment and can be modified appropriately without departing from the technical features of the present invention. Examples

[0070] The following describes the results of confirmation tests carried out to confirm the effectiveness of the present invention.

[0071] As shown in Tables 1 and 2, the water, organic solvent, solid component, neutralizing agent and organic acid were provided and mixed in the (weight ratio) specified in Tables 1 and 2 to obtain the electrodeposition dispersion.

[0072] Then a flat square rod (1.47 mm × 2.94 mm × 25 cm length) made of oxygen-free copper was prepared as a support with conductive properties and a cylindrical copper sheet as a counter electrode.

[0073] The substrate and counter electrode were immersed in the electrodeposition dispersion described above, the liquid temperature of the electrodeposition dispersion was set to 20 °C, the applied voltage to 500 V, and the holding time to 0.5 minutes; this resulted in the formation of the electrodeposition film.

[0074] The electrodeposition film was then baked in a three-stage temperature ramp-up profile, being held at a workpiece temperature of 140 °C to 170 °C for 10 minutes, at a workpiece temperature of 240 °C to 260 °C for 5 minutes, and at a workpiece temperature of 340 °C to 350 °C for 90 seconds, and then rapidly cooled; this formed the insulating film.

[0075] The concentration of the organic acid contained in the electrodeposition film was determined as follows.

[0076] The electrodeposition dispersion was diluted with ultrapure water, and then a filtrate obtained by removing impurities and passing through a membrane filter was used as a solution for ion chromatographic measurement.

[0077] The measurement was then performed using a Thermo Fisher Scientific ICS-5000+ ion chromatograph. The stationary phases of the ion chromatograph were the anion exchange columns Dionex IonPac AG15 and Dionex IonPac AS15, the eluent was an aqueous potassium hydroxide solution, the suppressor was a Dionex ADRS 600, and the detector was an electrical conductivity detector.

[0078] In addition, the appearance of the formed insulating film was examined, and cracks and blistering were assessed.

[0079] A case in which a crack was present where the copper of the substrate could be confirmed by visual observation was rated as 'D', a case in which a crack was present where the copper of the substrate could not be confirmed by visual observation was rated as 'C', a case in which the crack could not be confirmed by visual observation but could be confirmed by microscopic observation was rated as 'B', and a case in which the crack could not be confirmed by microscopic observation was rated as 'A'.

[0080] Furthermore, a case in which blistering in the insulating film was observed by visual observation was assessed as "present", and a case in which blistering was not observed was assessed as "not present".

[0081] Furthermore, the relative dielectric constant of the insulating film was measured in the following way.

[0082] Silver paste was applied to two 10 mm wide sections at the ends and to a 100 mm wide central section on the surface of the insulating film, thus preparing a test sample. The capacitance between the conductor and the silver paste in the central section was measured using an IM3536 LCR meter manufactured by HIOKI EE CORPORATION, and the relative permittivity was calculated from the measured capacitance and the film thickness.

[0083] Furthermore, the stability of the electrodeposition dispersion was evaluated. When the electrodeposition dispersion was held at 40°C for 5 days, any instance where deposition or precipitation occurred in the electrodeposition dispersion was rated "B", and any instance where no deposition or precipitation occurred in the electrodeposition dispersion was rated "A".

[0084] In comparative examples 1 to 3, no organic acid was added to the electrodeposition dispersion, and the cracks in which the Cu of the carrier could be detected were created after baking in the insulating film.

[0085] On the other hand, the organic acid was added to the electrodeposition dispersion in Invention Examples 1 to 24, and the cracks in which the Cu of the carrier could be detected were not produced in the insulating film after baking.

[0086] Furthermore, in Invention Examples 3 to 24, any organic acid of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid or hydroxybutyric acid was used, and the cracks that could be detected by visual observation were not produced.

[0087] In Inventional Examples 1 to 5, the concentration of the organic acid was less than 5 mg / L, and fine cracks were observed, but cracks in which the support was seen were not observed, and there were no problems with the insulating properties. In Inventional Examples 6 to 9, blistering occurred on the film because the concentration of the organic acid exceeded 500 mg / L.

[0088] Furthermore, in Inventional Examples 6, 8, 9, 15, and 16, the A / B ratio between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid was less than 5, and deposition or precipitation occurred in the electrodeposition dispersion when the electrodeposition dispersion was held at 40°C for 5 days, resulting in poor stability of the electrodeposition dispersion. In Inventional Examples 10 to 14, the A / B ratio between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid even exceeded 500 in one case where the concentration of the organic acid was 5 mg / L or more, thereby generating the fine cracks.

[0089] Furthermore, the solid component in Invention Examples 21 and 22 contained the polyimide resin and the fluoro resin, and the relative dielectric constant was sufficiently low, and the insulating properties were particularly excellent.

[0090] The results of the confirmation experiments described above confirmed that, according to the examples of the invention, it was possible to provide an electrodeposition dispersion with which the occurrence of fine cracks could be suppressed when the electrodeposition film was baked on and the insulating film with excellent insulating properties could be formed, and that it was possible to provide the method for forming an insulating film using the electrodeposition dispersion. INDUSTRIAL APPLICABILITY

[0091] It is possible to provide the electrodeposition dispersion with which the occurrence of fine cracks can be suppressed when the electrodeposition film is baked on and the insulating film with excellent insulating properties can be formed, and it is possible to provide the method for producing an insulating film using the electrodeposition dispersion. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-070843

[0002] JP 2024-017133

[0002] JP 2017-115120

[0007] JP 2018-070663

[0007]

Claims

[1] An electrodeposition dispersion for the electrodeposition of an electrodeposition film on a substrate with conductive properties by anionic electrodeposition, the electrodeposition dispersion comprising: Water, an organic solvent; a fixed component; and a neutralizing agent; and an organic acid; wherein the solid component includes at least one polyimide resin. [2] The electrodeposition dispersion according to claim 1, wherein the organic acid comprises any of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid or hydroxybutyric acid. [3] The electrodeposition dispersion according to claim 1, wherein the organic acid is two or more organic acids selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, benzoic acid, phthalic acid, trimellitic acid, glycolic acid, hydroxypropionic acid and hydroxybutyric acid. [4] The electrodeposition dispersion according to claim 1, wherein the organic acid comprises a hydroxy acid. [5] The electrodeposition dispersion according to claim 1, wherein the concentration of the organic acid is in the range of 5 mg / L or more and 500 mg / L or less. [6] The electrodeposition dispersion according to claim 1, wherein the ratio A / B between the concentration A mg / L of the neutralizing agent and the concentration B mg / L of the organic acid is in a range of 5 or more and 500 or less. [7] The electrodeposition dispersion according to claim 1, wherein the solid component further comprises a fluorinated resin. [8] A method for producing an insulating film for forming an insulating film on the surface of a support, the method for producing an insulating film comprising: An electrodeposition film formation step for forming an electrodeposition film on the support by immersing the support and a counter electrode in the electrodeposition dispersion according to any one of claims 1 to 7, and applying a voltage between the anode and the cathode, with the support as the anode and the counter electrode as the cathode; and a baking step to bake on the electrodeposition film.

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