US2721838A - Method of electrolytically pointing wires - Google Patents

Method of electrolytically pointing wires Download PDF

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Publication number
US2721838A
US2721838A US250609A US25060951A US2721838A US 2721838 A US2721838 A US 2721838A US 250609 A US250609 A US 250609A US 25060951 A US25060951 A US 25060951A US 2721838 A US2721838 A US 2721838A
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US
United States
Prior art keywords
wire
bath
liquid
electrolytically
pointing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US250609A
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English (en)
Inventor
Visser Simon Henricu Rudolphus
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hartford National Bank and Trust Co filed Critical Hartford National Bank and Trust Co
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Publication of US2721838A publication Critical patent/US2721838A/en
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    • 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
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/02—Local etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof

Definitions

  • the wires are vertically suspended as an anode in a bath containing etching liquid, current being supplied until the wire becomes punctiform in the vicinity of the meniscus of the liquid. This phenomenon is a result of a decrease in the current density and the concentration of the etching liquid towards the boundary between air and liquid at the area of the wire. The parts of the wire provided deep in the bath are dissolved completely.
  • a finely-divided insulating material insoluble in the bath liquid is added to the wire to be etched in an electrolytic bath.
  • the term finelydivided is to be understood to mean that the size of grain is smaller than microns, i. e. smaller than the radius of the point to be formed. This condition must be fulfilled to ensure uniform current density during etching.
  • the material must furthermore be divided and must not constitute a homogeneous, dense layer since it must be impregnated with the etching liquid.
  • the material must be insulating since it must not deviate the current from the surface to be etched.
  • the material may be provided on the wire in the form of an envelope, but as an alternative it may be contained in the metal of the wire itself. The latter case the quantity of insulating material is preferably from 0.1% to 3% by weight of the metal.
  • the metal is removed by etching, the insulating material retaining its initial form. If the substance is mixed with the metal, it acquires the shape of a very fine skeleton. When provided as an envelope, it remains in the form of a thin tube. In either case the remainder of the insulating substance insures satisfactory and stable adherence of the liquid. The remainder of substance is readily broken oflr the Wire, and in most cases already when the wire is withdrawn from the bath.
  • the insulating material must be insoluble in the etching liquid being used or at least dissolved less rapidly than the metal.
  • Fig. 1 shows diagrammatically a device for electrolytically pointing a wire
  • Figs. 2 and 3 show, on a greatly exaggerated scale, part of a wire at the area at which the point is formed, for two difierent forms of the wire to be etched.
  • the device comprises a container 1 in which a plurality of tungsten wires 3 are suspended by means of a pinch 2.
  • the thickness of the wires is, for example, microns.
  • the tungsten contains 0.25% of thorium oxide in a very finely-divided state.
  • the container furthermore contains a cathode 4, a 40% KOH solution being used as the etching liquid.
  • the bath is traversed by a current which is about 20 milliamps. per wire, the voltage being about 2 volts.
  • each tungsten wire 3 has acquired a point 6 in the vicinity of the meniscus, a very loosely coherent skeleton 7 of thorium oxide being formed at the foot of the wire.
  • This skeleton has a coherence suificient to ensure a constant form of the meniscus 5, but it breaks off with the slightest touch.
  • a wire is provided with an insulating envelope 8 (see Fig. 3) for example by causing a thin layer of aluminium oxide or magnesium oxide to be deposited thereon by cataphoretic means.
  • the etching treatment may subsequently take place in the manner above described.
  • a thin tube 9 of the oxide layer 8 is formed at the foot of the tungsten wire 3.
  • the oxide layer also insures that the meniscus does not vary in shape during etching.
  • a method of electrolytically pointing wire comprising the steps of uniting to at least the surface of the end of the wire a finely-divided porous electrically insulating material insoluble in a liquid of an electrolytic bath, suspending the wire as an anode in the electrolytic bath, and passing current through the bath until the end of the wire becomes punctiform in the vicinity of the meniscus formed by the bath liquid about the wire.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Cold Cathode And The Manufacture (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
US250609A 1950-10-28 1951-10-10 Method of electrolytically pointing wires Expired - Lifetime US2721838A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL305128X 1950-10-28

Publications (1)

Publication Number Publication Date
US2721838A true US2721838A (en) 1955-10-25

Family

ID=19783462

Family Applications (1)

Application Number Title Priority Date Filing Date
US250609A Expired - Lifetime US2721838A (en) 1950-10-28 1951-10-10 Method of electrolytically pointing wires

Country Status (7)

Country Link
US (1) US2721838A (en, 2012)
BE (1) BE506706A (en, 2012)
CH (1) CH305128A (en, 2012)
DE (1) DE936585C (en, 2012)
FR (1) FR1044215A (en, 2012)
GB (1) GB701474A (en, 2012)
NL (1) NL73679C (en, 2012)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2773024A (en) * 1954-04-08 1956-12-04 United States Steel Corp Method for electrolytically pointing wire
US3271280A (en) * 1962-06-29 1966-09-06 Csf Method for manufacturing coldemission cathodes
US3524803A (en) * 1968-05-13 1970-08-18 Us Army Method of electrolytically etching field filamentary material to make emitters
US5865978A (en) * 1997-05-09 1999-02-02 Cohen; Adam E. Near-field photolithographic masks and photolithography; nanoscale patterning techniques; apparatus and method therefor
US6386959B2 (en) 1999-01-13 2002-05-14 Micro Contacts Inc. Feeding system for electro-chemically polishing contact tips

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB322118A (en) * 1928-06-05 1929-12-05 Sherard Osborn Cowper Coles An improved process and apparatus for the electrolytic removal of metal from metallic bodies
US2018470A (en) * 1929-09-23 1935-10-22 Sirian Lamp Co Incandescent lamp, filament therefor and process and apparatus for making the same
US2434286A (en) * 1943-08-12 1948-01-13 Bell Telephone Labor Inc Method of forming a point at the end of a wire
US2545866A (en) * 1946-11-15 1951-03-20 Aluminum Co Of America Boron-containing aluminum wire and method of its production
US2628936A (en) * 1949-05-06 1953-02-17 Bell Telephone Labor Inc Method of forming a point at the end of a wire

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB322118A (en) * 1928-06-05 1929-12-05 Sherard Osborn Cowper Coles An improved process and apparatus for the electrolytic removal of metal from metallic bodies
US2018470A (en) * 1929-09-23 1935-10-22 Sirian Lamp Co Incandescent lamp, filament therefor and process and apparatus for making the same
US2434286A (en) * 1943-08-12 1948-01-13 Bell Telephone Labor Inc Method of forming a point at the end of a wire
US2545866A (en) * 1946-11-15 1951-03-20 Aluminum Co Of America Boron-containing aluminum wire and method of its production
US2628936A (en) * 1949-05-06 1953-02-17 Bell Telephone Labor Inc Method of forming a point at the end of a wire

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2773024A (en) * 1954-04-08 1956-12-04 United States Steel Corp Method for electrolytically pointing wire
US3271280A (en) * 1962-06-29 1966-09-06 Csf Method for manufacturing coldemission cathodes
US3524803A (en) * 1968-05-13 1970-08-18 Us Army Method of electrolytically etching field filamentary material to make emitters
US5865978A (en) * 1997-05-09 1999-02-02 Cohen; Adam E. Near-field photolithographic masks and photolithography; nanoscale patterning techniques; apparatus and method therefor
US6386959B2 (en) 1999-01-13 2002-05-14 Micro Contacts Inc. Feeding system for electro-chemically polishing contact tips

Also Published As

Publication number Publication date
BE506706A (en, 2012)
DE936585C (de) 1955-12-15
CH305128A (de) 1955-02-15
NL73679C (en, 2012)
FR1044215A (fr) 1953-11-16
GB701474A (en) 1953-12-23

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