US2186781A - Electrical rectifier - Google Patents

Electrical rectifier Download PDF

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Publication number
US2186781A
US2186781A US196912A US19691238A US2186781A US 2186781 A US2186781 A US 2186781A US 196912 A US196912 A US 196912A US 19691238 A US19691238 A US 19691238A US 2186781 A US2186781 A US 2186781A
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Prior art keywords
rectifier
copper
oxide
blanks
resistance
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Expired - Lifetime
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US196912A
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Philip H Dowling
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Hitachi Rail STS USA Inc
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Union Switch and Signal Inc
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Priority to US196912A priority Critical patent/US2186781A/en
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    • 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
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/16—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising cuprous oxide or cuprous iodide
    • H01L21/161—Preparation of the foundation plate, preliminary treatment oxidation of the foundation plate, reduction treatment
    • 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
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02565—Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
    • 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
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02614—Transformation of metal, e.g. oxidation, nitridation

Definitions

  • My invention relates to electrical rectifiers, and particularly to electrical rectifier-s of the copper oxide type.
  • One object of my invention is to improve the rectifying characteristics of rectifiers of the type described.
  • a feature of my invention comprises manufacturing copper oxide rectifiers from copper containing a small amount of another metal, such, for example, as lead.
  • Fig. 1 is a view showing in side elevation one form of copper blank ready to be manufactured into a rectifier element in accordance with my invention.
  • Fig. 2 is a view showing a number of blanks assembled on a support as they appear. during one step in the process of manufacture.
  • Fig. 3 is a vertical sectional view showing, in anexaggerated form, a rectifier element as it appears in another step in the process of manufacture.
  • Fig. 4 is a view showing a completed rectifier element constructed in accordance with my invention.
  • each blank A is now covered with an inner coating D of cuprous or red oxide of copper and a thin outer coating C of black oxide of copper.
  • the 5 flat face A of the blank which is exposed during the oxidizing process that is to say, the lower face, has a much heavier oxide coating than the upper face.
  • Each blank is next treated to remove the black oxide from the lower face of the blank, and both the black and red oxide from the upper face, after whichthe blank will appear as shown in Fig. 4.
  • One process which is particularly suitable for. removing the excess oxide from the blanks is described and claimed in Letl5 ters Patent of the United States No. 2,094,642 granted to me on October 5 1937.
  • the electrical contact to the exposed face of the cuprous oxide remaining on the blank is improved, as by rubbing into the face powdered petroleum coke.
  • Rectifier elements of the type described exhibit the characteristic of offering a relatively low resistance to current flowing through the element from the cuprous oxide to the copper and a relatively high resistance to the fiow of current through the element in the opposite direction.
  • the resistance of the element in the low resistance direction will hereinafter be referred to as the conducting resistance, while the 80 resistance of the element in the high resistance direction will hereinafter be referred to as the blocking resistance.
  • Rectifier elements of the type described also exhibit the characteristic that when a voltage is applied to them in the high resistance or blocking direction, the high or blocking resistance will de-. crease at first relatively rapidly and then somewhat more slowly with time until it obtains an apparently stable value which may be consider- 40 ably less than the initial value.
  • the stable virtual value of the reverse current when an alternating voltage is applied to the rectifier is increased due to this effect, and this effect accordingly in some-instances determines the voltage for which the rectifier is capable of effecting satisfactory' rectification in service.
  • This change in blocking resistance with time is ordinarily known as creep, or reverse creep, and is usually temporary in character, the apparent resistance in the reverse direction gradually returning toward its original value when the voltage'is removed.
  • Such impurity which I have found to be particularly eflfective in affecting the characteristics of the elements is lead, the presence of which in proper amounts increases the reverse resistance, decreases the tendency to creep, and also decreases the aging of the rectiflers in the blocking direction.
  • the lead to be effective should be present in a concentration of at least .001% by weight, and a concentration of 005% by weight gives particularly good results. In certain applications where exceptional reverse current sta-. bility is of more importance than a low resistance in the conducting direction, concentrations above .005% by weight may at times be found to be useful.
  • One advantage of the use of a copper body containing lead for the manufacture of rectifier elements is that it reduces the detrimental effects on the blocking resistance of the presence of anodic impurities during the manufacturing process.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Description

Jan. 9,1940. RHDOWUNG 2,186,781
ELECTRICAL RECTIFIER Filed March 19, 1938 Fly.
INVENTOR P1252450 HDowlz'ny.
HIS ATTORNEY Patented Jan. 9, 1940 PATENT OFFICE ELECTRICAL RECTIFIER Philip H-Doivling, Forest Hills, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application Mai-ch 19, 1938, Serial No. 196,912 3 Claims. (Cl. 175-366) My invention relates to electrical rectifiers, and particularly to electrical rectifier-s of the copper oxide type. i
One object of my invention is to improve the rectifying characteristics of rectifiers of the type described. p
A feature of my invention comprises manufacturing copper oxide rectifiers from copper containing a small amount of another metal, such, for example, as lead.
I shall describe one form of rectifiers embodying my invention, and shall then point out the novel features thereof in claims.
In the accompanying drawing, Fig. 1 is a view showing in side elevation one form of copper blank ready to be manufactured into a rectifier element in accordance with my invention. Fig. 2 is a view showing a number of blanks assembled on a support as they appear. during one step in the process of manufacture. Fig. 3 is a vertical sectional view showing, in anexaggerated form, a rectifier element as it appears in another step in the process of manufacture. Fig. 4 is a view showing a completed rectifier element constructed in accordance with my invention.
Similar reference characters refer to similar parts in all four views.
Inthe process of manufacturing copper oxide rectifiers, as. it is now generally practiced, a number of copper blanks, which may, for example, be similar to the blank A shown in Fig. 1,
are first cleaned in any suitable manner as by an acid etch, and these blanks are then assembled in pairs on a suitable support 13 in the manner shown in Fig. 2 so that the blanks of each pair have their adjacent faces A in contact. The blanks are then heated in the presence of air in an electric furnace, the temperature of which is usually maintained at about 1860" F. This heating of the blanks causes a layer of red or cuprous oxide to be formed on the blanks,
and is'continued until the cuprous oxide layer is.
of the desired thickness. After a sufficient amount of oxide has been formed on the copper blanks, these blanks are then transferred immediately to a secondfurnace which is maintained at a temperature of approximately 1050" F., and are allowed. to remain in this latter furnace only for a sufficient length .of time to permit them to cool down to the temperature of the second furnace. The oxidized blanks are then removed from the second furnace and are suddenly cooled or "quenched asby plunging the blanks into cold water or a current of cold air. Eachblank then appears as shown'in Fig.
3 from which it will be seen that each blank A is now covered with an inner coating D of cuprous or red oxide of copper and a thin outer coating C of black oxide of copper. It will also be seen from an inspection of Fig. 3 that the 5 flat face A of the blank which is exposed during the oxidizing process, that is to say, the lower face, has a much heavier oxide coating than the upper face. Each blank is next treated to remove the black oxide from the lower face of the blank, and both the black and red oxide from the upper face, after whichthe blank will appear as shown in Fig. 4. One process which is particularly suitable for. removing the excess oxide from the blanks is described and claimed in Letl5 ters Patent of the United States No. 2,094,642 granted to me on October 5 1937. As a last step, the electrical contact to the exposed face of the cuprous oxide remaining on the blank is improved, as by rubbing into the face powdered petroleum coke.
Rectifier elements of the type described exhibit the characteristic of offering a relatively low resistance to current flowing through the element from the cuprous oxide to the copper and a relatively high resistance to the fiow of current through the element in the opposite direction. The resistance of the element in the low resistance direction will hereinafter be referred to as the conducting resistance, while the 80 resistance of the element in the high resistance direction will hereinafter be referred to as the blocking resistance.
Rectifier elements of the type described also exhibit the characteristic that when a voltage is applied to them in the high resistance or blocking direction, the high or blocking resistance will de-. crease at first relatively rapidly and then somewhat more slowly with time until it obtains an apparently stable value which may be consider- 40 ably less than the initial value. The stable virtual value of the reverse current when an alternating voltage is applied to the rectifier is increased due to this effect, and this effect accordingly in some-instances determines the voltage for which the rectifier is capable of effecting satisfactory' rectification in service. This change in blocking resistance with time is ordinarily known as creep, or reverse creep, and is usually temporary in character, the apparent resistance in the reverse direction gradually returning toward its original value when the voltage'is removed.
I have found that when rectifier elements are manufactured by the process previously described, the presence in the copper from which the elements are manufactured or certain metallic impurities appears to materially affect the characteristics of the rectifier elements. One
such impurity which I have found to be particularly eflfective in affecting the characteristics of the elements is lead, the presence of which in proper amounts increases the reverse resistance, decreases the tendency to creep, and also decreases the aging of the rectiflers in the blocking direction. The lead to be effective should be present in a concentration of at least .001% by weight, and a concentration of 005% by weight gives particularly good results. In certain applications where exceptional reverse current sta-. bility is of more importance than a low resistance in the conducting direction, concentrations above .005% by weight may at times be found to be useful. In no event, however, should the concentration of the lead be large enough to interfere with the melting and rolling process by which the sheets or strips from which the blanks are punched are formed, nor should it be so large as to interfere with the adherence of the 'oxide layer 5 'to the mother metal.
One advantage of the use of a copper body containing lead for the manufacture of rectifier elements is that it reduces the detrimental effects on the blocking resistance of the presence of anodic impurities during the manufacturing process.
Although I have herein shown and described only one form of electrical rectiflers embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.
Having thus described my invention, what I claim is:
1. A copper oxide rectifier formed from a copper body containing approximately .001% by weight lead.
2. A copper oxide rectifier formed from a copper body containing approximately .005% by weight lead.
3. A copper oxide rectifier formed from a copper body containing between .001% and .005% by weight lead.
PHILIP H. BOWLING.
US196912A 1938-03-19 1938-03-19 Electrical rectifier Expired - Lifetime US2186781A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2484252A (en) * 1944-11-07 1949-10-11 Bell Telephone Labor Inc Asymmetrical conductor
US2793968A (en) * 1954-05-28 1957-05-28 Gen Electric Method of making copper oxide rectifier cells

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2484252A (en) * 1944-11-07 1949-10-11 Bell Telephone Labor Inc Asymmetrical conductor
US2793968A (en) * 1954-05-28 1957-05-28 Gen Electric Method of making copper oxide rectifier cells

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