US3249523A - Method of electrolytically etching aluminum - Google Patents

Method of electrolytically etching aluminum Download PDF

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Publication number
US3249523A
US3249523A US222906A US22290662A US3249523A US 3249523 A US3249523 A US 3249523A US 222906 A US222906 A US 222906A US 22290662 A US22290662 A US 22290662A US 3249523 A US3249523 A US 3249523A
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United States
Prior art keywords
current
aluminum
etching
direct current
solution
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Expired - Lifetime
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US222906A
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English (en)
Inventor
Post Wolfgang
Worschischek Eduard
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Alcan Holdings Switzerland AG
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Alusuisse Holdings AG
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
    • B23H3/02—Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
    • B23H3/08—Working media
    • 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

  • the present invention relates to a method of electrolytically etching aluminum surfaces, especially of aluminum electrodes for electrolytic capacitors.
  • etching of aluminum electrode foils increases their surface areas, and consequently increases the capacitance of the capacitor, in which these foils are employed.
  • Electrolytic processes are known for etching by using a pulsating direct current, whereby greater increase in surface area is attained compared with a process employing direct current of constant value.
  • pulsating direct current is meant a uni-directional uninterrupted current Whose magnitudefiuctuates periodically.
  • the current-time curve of the pulsating current may be of different square or sine wave form, but the degree of pulsations must be within the range of 50 to 250%, i.e. the total current variation expressed as a percentage of the average current value.
  • the pulsating current may be generated in different ways, but an unsmoothed rectified current, which could be obtained from 1- or 3-phase alternating current of sine Wave form is said to be unsuitable, as the degree of pulsation is too low.
  • etching condi tions such as the temperature, the current density and the electrolyte concentration also influence the extent of surface increase.
  • a high current density as for example, 50 to 60 amps./dm. and an electrolyte concentration as low as possible, as for example, between 0.1 and 0.2 N are said to be optimum.
  • electrolyte aqueous solutions of several acids and salts, especially halogen compounds are employed.
  • the etching is carried out using direct current with a pulsation degree of below 50%, but of at least 5%, an average current density of over 50 amps./dm. an electrolyte concentration in the range of 3 moles per liter up to saturation and a temperature between 70 C. and the boiling point.
  • direct current with a pulsation degree of below 50%, but of at least 5%, an average current density of over 50 amps./dm. an electrolyte concentration in the range of 3 moles per liter up to saturation and a temperature between 70 C. and the boiling point.
  • the specified etching conditions must be applied in combination, in order to obtain the highest increase in surface area. If even one of these conditions is changed, as for example, by employing a degree of pulsation of over 50% or an average current density below 50 amps./dm. the surface increase is less.
  • the frequency of pulsation may be varied within a wide range, for example, between 50 and 2000 cycles per second or even more. Alterations of the frequency beyond 200 cycles per second have hardly an influence on the extent of surface increase.
  • the low degree of pulsation employed compared with the known method has the advantage of permitting the use of an unsmoothed, rectified current from 1- or 3-phase alternating current of sine form, which is easily generated.
  • the time-current curve of the pulsating current may also have other forms.
  • Suitable electrolytes which may be employed in accordance with the present invention are aqueous solutions of chlorides, bromides, iodides and chlorates of the alkaline metals, and especially a sodium chloride solution.
  • concentration of these compounds-in aqueous solution must be 3 moles per liter or higher.
  • a saturated sodium chloride solution has a concentration of about 5 moles perliter depending somewhat on the temperature.
  • An addition of 1 to 5% by Weight of hydrochloric acid proved to be advantageous. However, the addition should not be too great in order that the aluminum is not attacked by the electrolyte before the current is applied.
  • the current density is limited by the highest possible electrical load at which the foil becomes overheated and begins to melt.
  • FIGS. 1-3 show the time-current curves employed in connection with the following examples respectively.
  • FIGS. 4-6 show the corresponding circuits for generating the pulsating currents employed in connection with the following examples.
  • (1) designates the aluminum foil to be etched, (2) the etching electrolyte solution and (3) the electrolyte container constituting the cathode.
  • Example 1 An aluminum foil having a purity of 99.99% was electrolytically etched during seconds after degreasing and pickling, by feeding continuously through an aqueous solution of 5 moles of sodium chloride per liter (29%) at a temperature of 80 C.
  • the direct pulsating current employed was an unsmoothed rectified current derived from a 3 -phase alternating sine wave current. This pulsating current had an average current density of 80 amps./dm. and a time-current curve as shown in FIG. 1. The fluctuations of the current were of such magnitude as to give a degree of pulsation of 20%.
  • a circuit with a 3-phase rectifier 4, as shown in FIG. 4 was employed.
  • the increase in surface area obtained by etching the aluminum foil in accordance with Example 1 was measured as a ratio of the capacity values of an etched foiland an unetched foil after formation of the dielectric layer by anodic oxidation at 6 volts in an electrolyte containing boric acid. The increase was 45 to 50 fold.
  • Example 2 An aluminum foil of 99.85% purity was etched in an aqueous solution containing 5 moles of sodium chloride and 5% by weight of hydrochloric acid at a temperature of C.
  • the etching current was derived from a direct current generator smoothed land superposed with alternating current in such a way as to yield a pulsating direct current having a degree of pulsation of 20%.
  • the timecurrent curve of this pulsating direct current is shown in FIG. 2 and the circuit is shown in FIG. 5.
  • This circuit comprises a first loop consisting of a direct current generator 5 and a choke 6 in series with the generator for cutting up the alternating current, and a second loop in parallel with said first loop and consisting of an alternating current generator 7 and a condenser 8 in series with said alternating current generator for avoiding direct current flux through said alternating current generator, the two loops being connected in parallel with the aluminum foil 1 and the cathode container 3.
  • the average current density was amps./dm. After 75 seconds of etching, the increase in surface area was about 40 fold.
  • the method of etching aluminum to increase its surface area for use in electrolytic capacitors after a dielectric layer has been anodically formed thereon at a voltage below 100 volts which comprises subjecting said aluminum to the action of an aqueous electrolytic solution containing essentially a halogen compound of the class consisting of alkali metal chlorides, bromides, iodides and chlorates, by a pulsating direct current having a degree of pulsation of less than 50%, but of at least 5% and an average current density of more than 50 amps./ dm. the concentration of the halogen compound in said solution being 3 moles per liter up to saturation and the temperature of said solution being between C. and the boiling point of said solution.
  • electrolyte is an aqueous solution of 3 to 5 moles of sodium chloride per liter with the addition of 1 to 5% by weight of hydrochloric acid.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • ing And Chemical Polishing (AREA)
US222906A 1961-09-15 1962-09-11 Method of electrolytically etching aluminum Expired - Lifetime US3249523A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1072961A CH398244A (de) 1961-09-15 1961-09-15 Verfahren zum elektrolytischen Ätzen von Aluminiumoberflächen

Publications (1)

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US3249523A true US3249523A (en) 1966-05-03

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US222906A Expired - Lifetime US3249523A (en) 1961-09-15 1962-09-11 Method of electrolytically etching aluminum

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US (1) US3249523A (de)
BE (1) BE622454A (de)
CH (1) CH398244A (de)
GB (1) GB949148A (de)
NL (1) NL282834A (de)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3442810A (en) * 1966-02-25 1969-05-06 Garman Co Inc Chemical polishing composition and method
US3477929A (en) * 1966-04-18 1969-11-11 Fujitsu Ltd Method of etching aluminum foil in the manufacturing of aluminum electrolytic condensers
US3520788A (en) * 1951-01-28 1970-07-14 Hans Werner Paehr Process for the extension of the effective surface of aluminium electrodes or foils for electrolytic capacitors
FR2322014A1 (fr) * 1975-08-25 1977-03-25 Hoechst Ag Procede de fabrication de supports de plaque d'impression planographique en aluminium rendu rugueux par voie electrochimique
US4035209A (en) * 1972-06-20 1977-07-12 Tokai Metals Co., Ltd. Method of preventing deterioration by heat
US4332651A (en) * 1981-05-20 1982-06-01 Sprague Electric Company AC Etching of aluminum capacitor foil
EP0054990A1 (de) * 1980-12-23 1982-06-30 Koninklijke Philips Electronics N.V. Aluminiumfolie für Elektrolytkondensatoren
DE3127330A1 (de) * 1981-07-10 1983-01-27 United Chemi-Con, Inc., 60018 Rosemont, Ill. Verfahren zum elektrolytischen aetzen von aluminium
US4455200A (en) * 1981-01-29 1984-06-19 Yoshiyuki Okamoto Method for etching aluminum foil for electrolytic capacitors
US4671858A (en) * 1983-10-06 1987-06-09 Matsushita Electric Industrial Co., Ltd. Method for making anode foil for an aluminum electrolytic capacitor
US4735696A (en) * 1987-04-27 1988-04-05 Polychrome Corporation Method of electrolytically graining aluminum metal sheets suitable for lithographic plate supports
US4886572A (en) * 1987-12-14 1989-12-12 Ricoh Company, Ltd. Composite electrode comprising a bonded body of aluminum and electroconductive polymer and electric cell using such a composite electrode
US5405493A (en) * 1994-01-26 1995-04-11 Kdk Corporation Method of etching aluminum foil
WO2003046262A1 (en) * 2000-10-17 2003-06-05 Faraday Technology, Inc. Sequential electromachining and electropolishing of metals and the like using modulated electric fields
US20030146191A1 (en) * 2002-02-07 2003-08-07 Ho-Ming Tong Etching method for nickel-vanadium alloy
EP1870497A1 (de) * 2006-06-23 2007-12-26 Siemens Aktiengesellschaft Verfahren zum elektrochemischen Entfernen einer metallischen Beschichtung von einem Bauteil
US20100072073A1 (en) * 2006-09-18 2010-03-25 Rene Jabado Method for the electrochemically coating or stripping the coating from components
US20100272888A1 (en) * 2006-08-08 2010-10-28 Siemens Aktiengesellschaft Method for producing a wear layer

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB914836A (de) * 1900-01-01
US2699382A (en) * 1951-02-14 1955-01-11 Aluminum Walzwerke Singen G M Method of etching aluminum foils
US2755237A (en) * 1951-07-25 1956-07-17 Sprague Electric Co Electrolytically etched condenser electrode
US2755238A (en) * 1955-03-25 1956-07-17 Sprague Electric Co Electrolytic etching and oxidizing of aluminum
US2930741A (en) * 1960-03-29 Electrolytic capacitors
US3085950A (en) * 1959-02-20 1963-04-16 British Aluminium Co Ltd Electrolytic etching of aluminum foil

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB914836A (de) * 1900-01-01
US2930741A (en) * 1960-03-29 Electrolytic capacitors
US2699382A (en) * 1951-02-14 1955-01-11 Aluminum Walzwerke Singen G M Method of etching aluminum foils
US2755237A (en) * 1951-07-25 1956-07-17 Sprague Electric Co Electrolytically etched condenser electrode
US2755238A (en) * 1955-03-25 1956-07-17 Sprague Electric Co Electrolytic etching and oxidizing of aluminum
US3085950A (en) * 1959-02-20 1963-04-16 British Aluminium Co Ltd Electrolytic etching of aluminum foil

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3520788A (en) * 1951-01-28 1970-07-14 Hans Werner Paehr Process for the extension of the effective surface of aluminium electrodes or foils for electrolytic capacitors
US3442810A (en) * 1966-02-25 1969-05-06 Garman Co Inc Chemical polishing composition and method
US3477929A (en) * 1966-04-18 1969-11-11 Fujitsu Ltd Method of etching aluminum foil in the manufacturing of aluminum electrolytic condensers
US4035209A (en) * 1972-06-20 1977-07-12 Tokai Metals Co., Ltd. Method of preventing deterioration by heat
FR2322014A1 (fr) * 1975-08-25 1977-03-25 Hoechst Ag Procede de fabrication de supports de plaque d'impression planographique en aluminium rendu rugueux par voie electrochimique
EP0054990A1 (de) * 1980-12-23 1982-06-30 Koninklijke Philips Electronics N.V. Aluminiumfolie für Elektrolytkondensatoren
US4455200A (en) * 1981-01-29 1984-06-19 Yoshiyuki Okamoto Method for etching aluminum foil for electrolytic capacitors
US4332651A (en) * 1981-05-20 1982-06-01 Sprague Electric Company AC Etching of aluminum capacitor foil
DE3127330A1 (de) * 1981-07-10 1983-01-27 United Chemi-Con, Inc., 60018 Rosemont, Ill. Verfahren zum elektrolytischen aetzen von aluminium
US4671858A (en) * 1983-10-06 1987-06-09 Matsushita Electric Industrial Co., Ltd. Method for making anode foil for an aluminum electrolytic capacitor
US4735696A (en) * 1987-04-27 1988-04-05 Polychrome Corporation Method of electrolytically graining aluminum metal sheets suitable for lithographic plate supports
US4886572A (en) * 1987-12-14 1989-12-12 Ricoh Company, Ltd. Composite electrode comprising a bonded body of aluminum and electroconductive polymer and electric cell using such a composite electrode
US5405493A (en) * 1994-01-26 1995-04-11 Kdk Corporation Method of etching aluminum foil
WO2003046262A1 (en) * 2000-10-17 2003-06-05 Faraday Technology, Inc. Sequential electromachining and electropolishing of metals and the like using modulated electric fields
US20030146191A1 (en) * 2002-02-07 2003-08-07 Ho-Ming Tong Etching method for nickel-vanadium alloy
EP1870497A1 (de) * 2006-06-23 2007-12-26 Siemens Aktiengesellschaft Verfahren zum elektrochemischen Entfernen einer metallischen Beschichtung von einem Bauteil
WO2007147655A1 (de) * 2006-06-23 2007-12-27 Siemens Aktiengesellschaft Verfahren zum elektrochemischen entfernen einer metallischen beschichtung von einem bauteil
US20100089768A1 (en) * 2006-06-23 2010-04-15 Jens Dahl Jensen Method for the electrochemical removal of a metal coating from a component
US20100272888A1 (en) * 2006-08-08 2010-10-28 Siemens Aktiengesellschaft Method for producing a wear layer
US8673405B2 (en) 2006-08-08 2014-03-18 Siemens Aktiengesellschaft Method for producing a wear layer
US20100072073A1 (en) * 2006-09-18 2010-03-25 Rene Jabado Method for the electrochemically coating or stripping the coating from components

Also Published As

Publication number Publication date
BE622454A (de)
CH398244A (de) 1965-08-31
NL282834A (de)
GB949148A (en) 1964-02-12

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