Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/004—Details
  • H01G9/04—Electrodes or formation of dielectric layers thereon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/004—Details
  • H01G9/04—Electrodes or formation of dielectric layers thereon
  • H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
  • H01G9/055—Etched foil electrodes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
  • C25D11/10—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing organic acids
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/18—After-treatment, e.g. pore-sealing
  • C25D11/20—Electrolytic after-treatment
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/18—After-treatment, e.g. pore-sealing
  • C25D11/24—Chemical after-treatment
  • C25D11/246—Chemical after-treatment for sealing layers
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/36—Phosphatising
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/0029—Processes of manufacture
  • H01G9/0032—Processes of manufacture formation of the dielectric layer
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/004—Details
  • H01G9/04—Electrodes or formation of dielectric layers thereon
  • H01G9/042—Electrodes or formation of dielectric layers thereon characterised by the material
  • H01G9/045—Electrodes or formation of dielectric layers thereon characterised by the material based on aluminium

Definitions

• the invention relates to a post-processing method for improving the quality of an oxide film of a medium-high voltage electrode foil.
• Aluminum electrolytic capacitors have always occupied a large share in the capacitor industry with their high quality and low price.
• the service life has always been the biggest problem that plagues aluminum electrolytic capacitors.
• the quality of the oxide film is directly related to the aluminum electrolytic capacitor. Life expectancy, market demand constantly proposes large-ripple-resistant, long-life capacitors to meet the design requirements of the whole machine.
• the oxide film quality of the electrode foil is also much improved compared with the past, but there is still room for improvement and improvement.
• the current problem is leakage current. There is still a need for further decline. Second, the hydration resistance needs to be further improved.
• the post-treatment method of the electrode foil for the medium-high voltage aluminum electrolytic capacitor is generally that the corrosion foil is subjected to hydration treatment, multi-stage electroforming, medium treatment, heat treatment, and post-reforming treatment, and then the foil is placed.
• the treatment liquid in the treatment tank is subjected to post-treatment, and the post-treatment bath liquid is an aqueous solution of ammonium dihydrogen phosphate, which is only immersed and not subjected to electrification treatment.
• the object of the present invention is to overcome the above deficiencies and provide a post-processing method for improving the quality of the oxide film of the medium-high voltage electrode foil for an aluminum electrolytic capacitor.
• the application of the variable current density causes the treatment liquid to accelerate ionization, and the phosphate ion permeates.
• the foil oxide film penetrates into the inner crucible, and the adsorption of oxygen ions is formed on the surface of the foil, so that Al 3+ in the oxide film rapidly forms an oxide film to reduce leakage current.
• phosphate ions are complexed with aluminum on the surface of the oxide film.
• the reaction produces a layer of triamite to prevent external water from hydrating with the foil, preventing the excessive production of the aluminite by reducing the current density, affecting the quality of the oxide film, and causing the leakage current of the foil oxide film by applying a current of variable current density. Decrease in hydration resistance, thereby improving the quality of the oxide film and increasing the life of the aluminum electrolytic capacitor.
• a post-processing method for improving the quality of the oxide film of the medium and high voltage electrode foil the steps are as follows:
• the corrosion foil is treated in deionized water at 95 ° C for 10 min, placed in a 6 wt% citrate aqueous solution in a chemical conversion tank, and subjected to a first-order condition at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 190 V. Forming, lasting 10 minutes, placed in a washing tank for cleaning;
• the cleaned foil is placed in a 4 wt% aqueous solution of citrate, and subjected to secondary formation at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 385 V for 10 min, placed in a water washing tank. Carry out cleaning;
• the chemical conversion foil is placed in the treatment liquid of the aftertreatment tank, and the post treatment is performed.
• the treatment tank is provided with a negative electrode having an electrode width of 0.5 to 5 cm, and the treatment liquid contains one or more phosphates, and the treatment liquid
• the pH value is controlled at 5 to 8, and the current density is controlled from 1 mA/cm 2 to 0.1 mA/cm 2 at a temperature of 50 to 90 ° C, 20 mA/cm 2 , and 100 to 800 V, and is formed into 3 to 15 minutes; ,drying;
• the post-treatment step is to form a foil into 0.1 wt% ammonium dihydrogen phosphate and 0.08 g/L hypophosphorous acid solution, and control the current density from 1 mA at 70 ° C, 20 mA/cm 2 , and 200 V. Cm 2 ⁇ 0.1 mA / cm 2 , into 5 min.
• the post-treatment step is to form a foil into 0.1 wt% ammonium dihydrogen phosphate and 0.08 g/L hypophosphorous acid solution, and control the current density from 0.5 mA at 70 ° C, 20 mA/cm 2 , and 200 V. /cm 2 -0.05 mA/cm 2 , and formed into 5 min.
• the post-treatment step is to form a foil into 0.1 wt% ammonium dihydrogen phosphate and 0.08 g/L hypophosphorous acid solution, and control the current density from 0.1 mA at 70 ° C, 20 mA/cm 2 , and 200 V. /cm 2 -0.01 mA/cm 2 , and formed into 5 min.
• the post-treatment step is to form a foil into 0.1 wt% ammonium dihydrogen phosphate and 0.08 g/L hypophosphorous acid solution, and control the current density from 1 mA at 70 ° C, 20 mA/cm 2 , and 200 V. Cm 2 -0.01 mA/cm 2 , and formed into 5 min.
• the post-treatment step is to form a foil into a 0.1 wt% ammonium dihydrogen phosphate solution and a 0.08 g/L hypophosphorous acid solution, and the current density is controlled to be 1 mA at 70 ° C, 20 mA/cm 2 , and 200 V. /cm 2 , into 5min.
• the negative electrode is a stainless steel electrode, equidistantly or non-equidistantly distributed within the processing tank.
• the present invention has the following advantages: by applying a current of a variable current density, the treatment liquid is accelerated and ionized, and the phosphate ions are permeated into a foil oxide film to penetrate into the inner crucible to form an adsorption of oxygen ions on the surface thereof, so that Al 3+ in the oxide film rapidly forms an oxide film to reduce leakage current.
• phosphate ions complex with aluminum on the surface of the oxide film to form a layer of triamite, which prevents external water from hydrating with the foil.
• Reducing the current density prevents the excessive production of the triamite, affecting the quality of the oxide film, and by applying a current of a variable current density, the leakage current of the foil oxide film is lowered, and the hydration resistance is improved, thereby improving the quality of the oxide film and improving the life of the aluminum electrolytic capacitor.
• Example 1 After the corrosion foil was treated in deionized water at 95 ° C for 10 min, it was placed in a 6 wt% aqueous solution of citrate in a chemical conversion tank, and was subjected to a condition of 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 190 V.
• Second-stage formation duration 10 min; placed in a washing tank for cleaning; the cleaned foil into a 4 wt% citrate aqueous solution at 85 ° C, current density of 20 mA / cm 2 , voltage of 385V be placed into the groove of the three 5wt% borate saline solution, at 85 °C, a current density of 20mA / cm 2, a voltage of 545V conditions; for secondary formation, the duration of 10min; washing tank disposed washed
• the formation was carried out for 15 min; the solution was placed in an 8 wt% borate aqueous solution, and the quaternization was carried out at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 620 V for 25 min; Washing; placed in an oven for high temperature heat treatment at 500 ° C for 3 min; placed in the same aqueous solution as the fourth stage, at 85 ° C, 20 mA / cm 2 , 620 V, into 10 minutes;
• Example 2 First-stage formation, duration 10 min; placed in a washing tank for cleaning; the cleaned foil into a 4 wt% citrate aqueous solution at 85 ° C, current density of 20 mA / cm 2 , voltage of 385V
• the secondary formation was carried out for 10 min; it was placed in a washing tank for washing; it was placed in a 5 wt% borate aqueous solution in a chemical conversion tank, and the third stage was carried out at 85 ° C, a current density of 20 mA/cm 2 and a voltage of 545 V.
• the formation was carried out for 15 min; the solution was placed in an 8 wt% borate aqueous solution, and the quaternization was carried out at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 620 V for 25 min; Washing; placed in an oven for high temperature heat treatment at 500 ° C for 3 min; placed in the same aqueous solution as the fourth stage, at 85 ° C, 20 mA / cm 2 , 620 V, into 10 minutes; placed in a washing tank for cleaning; In a 6wt% phosphoric acid solution Carried out at 70 °C for 5min processing; cleaning washing tank disposed; oven temperature heat treatment 3min 450 °C; and placed into an aqueous solution of the same in four, at 85 °C, 20mA / cm 2, 620V of Under the conditions, it was formed into 10min; it was placed in a washing tank for cleaning; it was placed in 0.1wt% ammonium dihydrogen phosphate and
• Example 3 The corrosion foil was treated in deionized water at 95 ° C for 10 min, placed in a 6 wt% aqueous solution of citrate in a chemical conversion tank, and subjected to a condition of 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 190 V.
• First-stage formation duration 10 min; placed in a washing tank for cleaning; the cleaned foil into a 4 wt% citrate aqueous solution at 85 ° C, current density of 20 mA / cm 2 , voltage of 385V
• the secondary formation was carried out for 10 min; it was placed in a washing tank for washing; it was placed in a 5 wt% borate aqueous solution in a chemical conversion tank, and the third stage was carried out at 85 ° C, a current density of 20 mA/cm 2 and a voltage of 545 V.
• the formation was carried out for 15 min; the solution was placed in an 8 wt% borate aqueous solution, and the quaternization was carried out at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 620 V for 25 min; Washing; placed in an oven for high temperature heat treatment at 500 ° C for 3 min; placed in the same aqueous solution as the fourth stage, at 85 ° C, 20 mA / cm 2 , 620 V, into 10 minutes; placed in a washing tank for cleaning; In a 6wt% phosphoric acid solution Carried out at 70 °C for 5min processing; cleaning washing tank disposed; oven temperature heat treatment 3min 450 °C; and placed into an aqueous solution of the same in four, at 85 °C, 20mA / cm 2, 620V of Under the conditions, it was formed into 10min; it was placed in a washing tank for cleaning; it was placed in 0.1wt% ammonium dihydrogen phosphate and
• Example 4 The corrosion foil was treated in deionized water at 95 ° C for 10 min, placed in a 6 wt% aqueous solution of citrate in a chemical conversion tank, and subjected to a condition of 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 190 V.
• Second-stage formation duration 10 min; placed in a washing tank for cleaning; the cleaned foil into a 4 wt% citrate aqueous solution at 85 ° C, current density of 20 mA / cm 2 , voltage of 385V be placed into the groove of the three 5wt% borate saline solution, at 85 °C, a current density of 20mA / cm 2, a voltage of 545V conditions; for secondary formation, the duration of 10min; washing tank disposed washed
• the formation was carried out for 15 min; the solution was placed in an 8 wt% borate aqueous solution, and the quaternization was carried out at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 620 V for 25 min; It is cleaned; placed in an oven for high temperature heat treatment at 500 ° C for 3 min; placed in the same aqueous solution as the fourth stage, at 85 ° C, 20 mA / cm 2 , 620 V, into 10 min
• Example 5 After treating the corrosion foil in deionized water at 95 ° C for 10 min, it was placed in a 6 wt% aqueous solution of citrate in a chemical conversion tank, and was subjected to a condition of 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 190 V.
• First-stage formation duration 10 min; placed in a washing tank for cleaning; the cleaned foil into a 4 wt% citrate aqueous solution at 85 ° C, current density of 20 mA / cm 2 , voltage of 385V
• the secondary formation was carried out for 10 min; it was placed in a washing tank for washing; it was placed in a 5 wt% borate aqueous solution in a chemical conversion tank, and the third stage was carried out at 85 ° C, a current density of 20 mA/cm 2 and a voltage of 545 V.
• the formation was carried out for 15 min; the solution was placed in an 8 wt% borate aqueous solution, and the quaternization was carried out at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 620 V for 25 min; washing; disposed high temperature heat treatment in an oven at 500 deg.] C 3min; the same is placed into an aqueous solution of four, at 85 °C, 20mA / cm condition 2, 620V, and into 10min; cleaning washing tank disposed; set In a 6wt% phosphoric acid solution Carried out at 70 °C for 5min processing; cleaning washing tank disposed; oven temperature heat treatment 3min 450 °C; and placed into an aqueous solution of the same in four, at 85 °C, 20mA / cm 2, 620V of Under the conditions, it is formed into 10min; it is placed in a washing tank for cleaning; it is placed in 0.1wt% ammonium dihydrogen phosphate and 0.08g
• Comparative Example After the corrosion foil was treated in deionized water at 95 ° C for 10 min, it was placed in a 6 wt% citrate aqueous solution in a chemical conversion tank, and subjected to a condition of 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 190 V. The aging was carried out for 10 min; it was placed in a washing tank for washing; the cleaned foil was placed in a 4 wt% citrate aqueous solution at 85 ° C, a current density of 20 mA/cm 2 and a voltage of 385 V.
• duration 10min placed in a washing tank for cleaning; placed in a 5wt% borate aqueous solution in a chemical tank, at a temperature of 85 ° C, current density of 20mA / cm 2 , voltage of 545V three-stage formation , the duration is 15 min; placed in an 8 wt% borate aqueous solution in a chemical conversion tank, and subjected to quaternization at 85 ° C, a current density of 20 mA/cm 2 , and a voltage of 620 V for 25 min; Cleaning; placed in an oven for high temperature heat treatment at 500 ° C for 3 min; placed in the same aqueous solution as the fourth stage, at 85 ° C, 20 mA / cm 2 , 620 V, into 10 min; placed in a washing tank for cleaning; placed In a 6 wt% phosphoric acid solution Carried out at 70 °C for 5min processing; cleaning washing tank disposed; oven temperature heat treatment 3min 450 °C; and placed into
• the experimental data shows that a negative electrode is provided in the treatment tank by using one or more kinds of phosphate as a treatment liquid for the post-treatment tank, and an electric field is applied to the foil by controlling a current of a variable current density to increase the oxide film. After the treatment effect, the obtained foil is superior to the traditional process products in terms of leakage current and hydration resistance.

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