US3477929A - Method of etching aluminum foil in the manufacturing of aluminum electrolytic condensers - Google Patents

Method of etching aluminum foil in the manufacturing of aluminum electrolytic condensers Download PDF

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Publication number
US3477929A
US3477929A US630972A US3477929DA US3477929A US 3477929 A US3477929 A US 3477929A US 630972 A US630972 A US 630972A US 3477929D A US3477929D A US 3477929DA US 3477929 A US3477929 A US 3477929A
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Prior art keywords
etching
aluminum
mol
manufacturing
etched
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US630972A
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English (en)
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Takeshi Namikata
Kazuo Kubo
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Fujitsu Ltd
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Fujitsu Ltd
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    • 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
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • C25F3/04—Etching of light metals

Definitions

  • Our invention relates to a method of manufacturing aluminum electrolytic condensers.
  • the aluminum anode element is etched to increase the effective surface area of the aluminum anode element thus increasing the capacity of the condenser.
  • the aluminum anode ele ment is etched electrolytically in a liquid including a large amount of halogen ion.
  • the aluminum anode element is etched electrolytically in an etchant comprising a 16% aqueous solution of HCl using a steady (nonpulsating) direct current at a temperature of about 70 C. for several minutes.
  • an etchant comprising a 16% aqueous solution of HCl using a steady (nonpulsating) direct current at a temperature of about 70 C. for several minutes.
  • the etching liquid is a weak acid, the pH gradually increases as the etching proceeds and aluminum hydroxide precipitate (or settlings) is produced. These settlings lower the conductivity of the liquid and raise the bath voltage as they are precipitated on the electrode.
  • Our invention has as an object the obviating of the above-mentioned defects and increasing the effective surface area of the aluminum anode element and inhibiting the settlings of aluminum hydroxide.
  • Our invention makes the aluminum anode element porous by etching.
  • corrosion inhibitors such as chromic acid and chromate, to a solution including halogen ion.
  • the chromic acid simultaneously inhibits the settlings of aluminum hydroxide.
  • the etching effectivity can be increased by properly selecting the wave form of the current used and the temperature 'of the liquid.
  • a pulsating current with a pulsating ratio of voltage [(the maximum value of a voltage-the minimum value of voltage)/the average value of voltage] of 15-3 is well suited as the current wave form and 65-85 C. is the optimum temperature.
  • FIGS. 1, 2, 3 and 4 respectively show variations of magnification (increase) of etching on the ordinate versus, respectively, temperature, pulsating ratio, current density and voltage.
  • the concentration of the inorganic acid added to prevent the precipitation of aluminum hydroxide during the etching should preferably be higher from the viewpoint of lowering the pH, but it has a certain upper limit since the etching of the anode element to make it porous by the above-mentioned liquid must not be affected.
  • the upper limit of the amount of nitric acid and sulfuric acid that can be added to a liquid of which the 01- concentration is 0.2 mol/l. is 0.8 mol/l. and the upper limit of phosphoric acid in this case is 0.8 mol/1.
  • this invention exhibits a particularly valuable effect in the etching of a thick aluminum plate.
  • FIG. 1 shows the effect on increase of porosity (magnification) in a 50 v. formation when the temperature of the liquid is varied in the examples of this invention.
  • Curve 1 corresponds to Example 1 and curve 2 corresponds to Example 3.
  • FIG. 2 shows the effect on magnification in a 50 v. formation when the pulsation factor of the etching voltage is varied according to the examples.
  • Curve 1 corresponds to Example 1 and curve 2 corresponds to Example 3. It can be seen from this figure that 1.5-3 is the optimum pulsation factor.
  • FIG. 3 shows the variation of magnification in a 50 v. formation when the current density is varied according to the examples.
  • Curve 1 corresponds to Example 1 and curve 2 corresponds to Example 3. It can be seen from the figure that the influence of current density is not great.
  • FIG. 4 shows the relation between the formation voltage and the magnification of etching.
  • Curve 1 corresponds to Example 1 and curve 2 corresponds to Example 3 with curve 3 corresponding to the conventional etching method.
  • Example 1 A smooth aluminum plate of a purity of 99.99% and a thickness of 1 mm. was etched electrolytical- 1y for 10 minutes in an aqueous solution of HCl of 0.1 mol/l. and Q0, of 0.05 mol/1., at C., using a pulsating current of single phase full wave (pulsation factor 1.6) with a current density of 0.6 a./cm. This was formed at 50 v. and then the electrostatic capacity on both surfaces of 1 cm. was 19 ,uf. This is 79 times as great as the case of the smooth surface.
  • Example 2 An aluminum plate of a thickness of 1 mm. was etched electrolytically for 10 minutes in an aqueous solution containing 0.1 mol/l. of HCl, 0.05 mol/l. of CrO and 0.1 mol/l. of HNO at 80 C., by the use of a pulsating current of single phase full wave of a current density of 0.6 a./cm. The same magnification as in Example 1 was obtained. Furthermore, settlings of aluminum hydroxide were precipitated when a current of 10 a.h.- was flowed per 1 liter of the liquid of Example 1 including no HNO but in the case of the liquid of this example including HNO the settlings of aluminum hydroxide did not precipitate until the current was increased to 35 ab. per liter of the liquid. The increase of the bath voltage was also slight making it possible to continue etching under a stable condition. y
  • Example 3 A smooth aluminum plate of a purity of 99.99% and of a thickness of 1 mm. was first etched electrolytically, weakly for 60 seconds in an aqueous 16% solution of HCl at 70 C. by a direct current of a current density of 0.7 a./cm. including no ripple and was then etched deeply by the method of Example 2. This was formed at 50 v.
  • the electrostatic capacity on both surfaces of 1 cm. was 21 ,uf. and the magnification of etching (surface increase) as against the smooth surface was 87 times.
  • Example 4 An aluminum plate was etched electrolytically in an aqueous solution including 0.2 mol/l. H PO instead of HNO in Example 2 and by the same method as the case of Example 2. The same magnification and stability as in Example 2 were obtained.
  • Example 5 An aluminum plate was etched electrolytically in an aqueous solution including 0.1 mol/l. H 80 instead of HNO in Example 2 and by the same method as the case of Example 2. The same magnification and stability as in Example 2 were obtained.
  • Example 6 A smooth aluminum plate of a purity of 99.99% and a thickness of 1 mm. was dipped for 90 seconds in an aqueous solution containing 5% H01 and 0.3% CuSO at a bath temperature of 65 C. The copper precipitated on the aluminum plate was resolved (dissolved) and removed by dipping the plate in a cold concentrated nitric acid. The thus etched aluminum plate was then etched deeply by the method of Example 2. The porous aluminum plate thus obtained was formed at 50 v. and then the electrostatic capacity amounted to 90 times that of the smooth surface.
  • Example 7 An aluminum wire of a purity of 99.99%
  • Example 4 a diameter of 3 mm. was etched electrolytically and was made porous by the same method as Example 4. This was formed at v. and then the electrostatic capacity per 1 cm. of the wire was 8 f. This is times as great as the electrostatic capacity of the wire the surface of which is left smooth.
  • a method of manufacturing aluminum electrolytic condensers which comprises electrolytically etching the aluminum as the anode using a pulsating current :with a pulsation factor of 1.5-3 in an aqueous solution consisting essentially of 002-02 mol/l. Cl" and 0.020.1 mol/l. CrO in a pH range at which the precipitation of aluminum hydroxides is minimized.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • ing And Chemical Polishing (AREA)
US630972A 1966-04-18 1967-04-14 Method of etching aluminum foil in the manufacturing of aluminum electrolytic condensers Expired - Lifetime US3477929A (en)

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3887447A (en) * 1971-07-09 1975-06-03 Alcan Res & Dev Process of electrograining aluminium
DE2650762A1 (de) * 1975-11-06 1977-05-18 Nippon Light Metal Res Labor Verfahren zur elektrolytischen koernung von aluminiumsubstraten fuer die lithographie
US4052274A (en) * 1975-04-05 1977-10-04 Agency Of Industrial Science & Technology Electrochemical wire cutting method
US4113587A (en) * 1974-08-05 1978-09-12 Agency Of Industrial Science And Technology Method for electrochemical machining
US4140599A (en) * 1975-06-04 1979-02-20 Fujitsu Limited Process for producing porous aluminum anode element
US4247377A (en) * 1979-02-21 1981-01-27 United Technologies Corporation Method for electrolytic etching
US4279715A (en) * 1980-09-15 1981-07-21 Sprague Electric Company Etching of aluminum capacitor foil
US4297184A (en) * 1980-02-19 1981-10-27 United Chemi-Con, Inc. Method of etching aluminum
US4336113A (en) * 1981-06-26 1982-06-22 American Hoechst Corporation Electrolytic graining of aluminum with hydrogen peroxide and nitric or hydrochloric acid
WO1982002620A1 (fr) * 1981-01-29 1982-08-05 Yoshiyuki Okamoto Procede de gravure d'une feuille d'aluminium pour un condensateur electrolytique
US4547275A (en) * 1984-02-03 1985-10-15 Showa Aluminum Kabushiki Kaisha Process for treating surface of aluminum foil for use as electrode of electrolytic capacitors
US4897168A (en) * 1987-05-12 1990-01-30 Hoechst Aktiengesellschaft Process and arrangement for production of printing plate support
WO2007085062A1 (en) * 2006-01-27 2007-08-02 Zijad Cehic Production of perforated aluminium (in the form of sheet or foil) hard- or soft-rolled

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721835A (en) * 1951-07-07 1955-10-25 Shwayder Bros Inc Surface treatment of aluminum articles
US2755238A (en) * 1955-03-25 1956-07-17 Sprague Electric Co Electrolytic etching and oxidizing of aluminum
US2930741A (en) * 1960-03-29 Electrolytic capacitors
US3035990A (en) * 1958-11-05 1962-05-22 Collins Radio Co Chemical blanking of aluminum sheet metal
US3085950A (en) * 1959-02-20 1963-04-16 British Aluminium Co Ltd Electrolytic etching of aluminum foil
US3249523A (en) * 1961-09-15 1966-05-03 Alusuisse Method of electrolytically etching aluminum
US3321389A (en) * 1964-07-20 1967-05-23 Mallory & Co Inc P R Method of anodically etching aluminum foils at elevated temperatures in an electrolyte including chloride and sulfate ions

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2930741A (en) * 1960-03-29 Electrolytic capacitors
US2721835A (en) * 1951-07-07 1955-10-25 Shwayder Bros Inc Surface treatment of aluminum articles
US2755238A (en) * 1955-03-25 1956-07-17 Sprague Electric Co Electrolytic etching and oxidizing of aluminum
US3035990A (en) * 1958-11-05 1962-05-22 Collins Radio Co Chemical blanking of aluminum sheet metal
US3085950A (en) * 1959-02-20 1963-04-16 British Aluminium Co Ltd Electrolytic etching of aluminum foil
US3249523A (en) * 1961-09-15 1966-05-03 Alusuisse Method of electrolytically etching aluminum
US3321389A (en) * 1964-07-20 1967-05-23 Mallory & Co Inc P R Method of anodically etching aluminum foils at elevated temperatures in an electrolyte including chloride and sulfate ions

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3887447A (en) * 1971-07-09 1975-06-03 Alcan Res & Dev Process of electrograining aluminium
US4113587A (en) * 1974-08-05 1978-09-12 Agency Of Industrial Science And Technology Method for electrochemical machining
US4052274A (en) * 1975-04-05 1977-10-04 Agency Of Industrial Science & Technology Electrochemical wire cutting method
US4140599A (en) * 1975-06-04 1979-02-20 Fujitsu Limited Process for producing porous aluminum anode element
DE2650762A1 (de) * 1975-11-06 1977-05-18 Nippon Light Metal Res Labor Verfahren zur elektrolytischen koernung von aluminiumsubstraten fuer die lithographie
US4247377A (en) * 1979-02-21 1981-01-27 United Technologies Corporation Method for electrolytic etching
US4297184A (en) * 1980-02-19 1981-10-27 United Chemi-Con, Inc. Method of etching aluminum
US4279715A (en) * 1980-09-15 1981-07-21 Sprague Electric Company Etching of aluminum capacitor foil
WO1982002620A1 (fr) * 1981-01-29 1982-08-05 Yoshiyuki Okamoto Procede de gravure d'une feuille d'aluminium pour un condensateur electrolytique
US4455200A (en) * 1981-01-29 1984-06-19 Yoshiyuki Okamoto Method for etching aluminum foil for electrolytic capacitors
DE3231662C2 (de) * 1981-01-29 1984-09-13 Suzuoka Electric Appliances Industrial Co. Ltd., Tenryu Verfahren zum elektrochemischen Ätzen von Aluminiumfolien
US4336113A (en) * 1981-06-26 1982-06-22 American Hoechst Corporation Electrolytic graining of aluminum with hydrogen peroxide and nitric or hydrochloric acid
US4547275A (en) * 1984-02-03 1985-10-15 Showa Aluminum Kabushiki Kaisha Process for treating surface of aluminum foil for use as electrode of electrolytic capacitors
US4897168A (en) * 1987-05-12 1990-01-30 Hoechst Aktiengesellschaft Process and arrangement for production of printing plate support
WO2007085062A1 (en) * 2006-01-27 2007-08-02 Zijad Cehic Production of perforated aluminium (in the form of sheet or foil) hard- or soft-rolled

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Publication number Publication date
DE1589784B2 (de) 1970-09-24
NL6705053A (nl) 1967-10-19
DE1589784A1 (nl) 1970-09-24

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