US3086889A - Method and apparatus for coating a continuous sheet of material - Google Patents

Method and apparatus for coating a continuous sheet of material Download PDF

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US3086889A
US3086889A US16493A US1649360A US3086889A US 3086889 A US3086889 A US 3086889A US 16493 A US16493 A US 16493A US 1649360 A US1649360 A US 1649360A US 3086889 A US3086889 A US 3086889A
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coating
boat
metal
sheet
speed
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US16493A
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Richard V D Strong
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FJ Stokes Corp
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FJ Stokes Corp
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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
    • H01G13/00—Apparatus specially adapted for manufacturing capacitors; Processes specially adapted for manufacturing capacitors not provided for in groups H01G4/00 - H01G11/00
    • H01G13/06—Apparatus specially adapted for manufacturing capacitors; Processes specially adapted for manufacturing capacitors not provided for in groups H01G4/00 - H01G11/00 with provision for removing metal surfaces
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/246—Replenishment of source material
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/54—Controlling or regulating the coating process
    • C23C14/542—Controlling the film thickness or evaporation rate
    • C23C14/545—Controlling the film thickness or evaporation rate using measurement on deposited material
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/56—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
    • C23C14/562—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks for coating elongated substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors

Definitions

  • the present invention relates to a method and apparatus for coating a continuous sheet of material, and more particularly to a method and apparatus for applying a thin continuous metal film or a uniform thickness to a dielectric sheet material in a continuous operation.
  • the coating method herein concerned is one in which the sheet material to be coated is passed continuously through a 'low pressure chamber or zone in which a coating metal is vaporized.
  • the vaporized metal deposits on the material to form the coating.
  • a major problem has been to obtain a coating which is of uniform thickness along the entire length of the sheet material. For many purposes, as in the production of metal coated paper or electrical condensers, variations of coating thicknesses cannot be tolerated.
  • the drawing is a schematic sectional view of the coating apparatus of the present invention.
  • the coating apparatus of the present invention is generally designated as 10.
  • Coating apparatus 10 comprises a housing 12 which is completely enclosed so that the interior of the housing is hermetically sealed from the atmosphere.
  • the housing 12 contains an evaporation chamber 14 along the bottom portion thereof, and a coating chamber 16 above the evaporation chamber 14.
  • a horizontal partition 18 divides the evaporation chamber 14 from the coating chamber 16.
  • the partition 18 has an opening 20 therethrough adjacent one side of the housing 12 to permit the coating metal vapors to pass from the evaporation chamber 14 to the coating chamber 16.
  • the partition 18 also has an opening 22 therethrough to permit equalization of the pressures within the coating chamber 16 and the evaporation chamber 14.
  • a pipe 24 connects the interior of the evaporation chamber 14 to means for creating a vacuum, such as a vacuum pump, not shown.
  • a container 26 of a thermal insulation material is mounted within the evaporation chamber '14 directly beneath the opening 20 in the partition 18.
  • the container 26 contains a heater 28, such as an electrical resistance heater.
  • a boat or cup 30 of a material which will withstand high temperatures is seated in the container 26 above the heater 28.
  • the outer wall 62 of the boat 30 tapers so that the area encompassed by the bottom portion of the wall 32 is smaller than the area encompassed by the top portion of the wall 32.
  • the boat 30 contains the 3,086,889 Patented Apr. 23, 1963 source of the coating metal 34.
  • a reel 36 containing a strip or wire 38 of the coating metal is rotatably mounted on the side wall of the housing 12 within the evaporation chamber 14.
  • the strip or wire 38 of the coating metal passes from the reel 36 between a pair of mating teed rolls 40 and 42, and through a guide tube 44 to the boat 30.
  • the feed roll 49 is driven by an electric motor 46 mounted outside of the housing 12. The frictional engagement between the rotating feed roll 40 and the strip or wire 38 feeds the strip or wire 38 to the boat 30 so as .to maintain a constant supply of the coating material 34 within the coat 30.
  • a supply roll 48 of the sheet material 50 to be coated is rotatably mounted about a horizontal axis within the coating chamber 16 adjacent the top of the housing 12.
  • a backing plate 52 is mounted slightly above the partition 18, and extends across the opening 29 in the partition 18.
  • a pair of guide rolls 54 and 56 are rotatably mounted along each side of the backing plate 52.
  • the sheet material 50 to be coated passes from the supply roll 48 downwardly to and around the .guide roll 54.
  • the sheet material 50 then passes under the backing plate 52 and across the opening 20 in the partition 18. From the guide roll 56, the sheet material 50 passes upwardly around a pair of vertically spaced guide rolls 58 and 60 to a take-up roll 62 which is mounted adjacent the supply roll 48.
  • the take-up roll 62 is driven by an electric motor 64 which is mounted on the top of the housing 12.
  • Motor 64 is electrically connected to a source of electrical current through a speed control 66.
  • a tachometer 68 is mounted on the side of the housing 12, and is connected to the guide roll 60.
  • the tachometer 68 continuously measures the speed of rotation of the guide roll 60 as the sheet of material 50 passes around the guide roll 60.
  • the tachometer 68 is electrically connected to the speed control 66 of the motor 64. Any variations in the speed of rotation of the guide roll 60 from a predetermined setting of the tachometer 68 will operate the speed control 66 to vary the speed of the motor 64.
  • the speed of the motor 64 is varied to change the speed of rotation of the take-up roll 62 so that the speed of rotation of guide roll 60 is returned to the predetermined speed through the variation in the speed of the sheet of material 50.
  • the tachometer 68 will operate the speed control 66 to slow down the motor 64 and thereby maintain the linear speed of the sheet material 50 constant.
  • a pair of electrical contacts 70 and 72 engage the coated side of the sheet material 58 at spaced points between the guide rolls 58 and 60.
  • the contacts 70 and 72 are mounted on the ends of posts 74 and 76 which extend through and are supported on the side of the housing 12.
  • the posts 74 and 76 are insulated from the housing 12 by bushings 78 of an electrical insulating material.
  • the posts 74 and 76 are electrically connected by wires 80 and 82 respectively to a resistance measuring and control circuit, generally designated as 84,
  • the resistance measuring and control circuit 84 may include a bridge circuit which is balanced against the resistance measured between the contacts 70 and 72.
  • Such a bridge circuit is of the type which will provide an electrical signal upon any variation in the resistance measured between the contacts 70 and 72, which signal is of a polarity determined by whether the resistance measured between the contacts 70 and 72 increases or decreases.
  • resistance measuring bridges well known in the which will function in this manner, such as the resistance measuring bridge shown and described in Patent No. 2,545,576 to Philip Godley, 2nd issued March 20, 1951.
  • the resistance measuring and control circuit 84 may also include a rheostat which is operated by the signal from the bridge circuit in the manner shown in Patent No. 2,545,576.
  • the rheostat is electrically connected by the wires 86 and 88 to the motor 46 which drives the feed roll 48 for the strip or wire 38.
  • the resistance measuring and control circuit 84- is connected to the motor 46 so that an increase in the resistance measured between the contacts 70 and 72 will increase the speed of the motor 46, and a decrease in the resistance measured between the contacts 70 and 72 will decrease the speed of the motor 46.
  • the coating apparatus 18 of the present invention operates as follows:
  • the evaporating chamber 14 is evacuated through the pipe 2d which is attached to a vacuum pump. Evacuation of the evaporating chamber 14 also evacuates the coating chamber '16 which is in communication with the evaporating chamber 14- through the opening 22 in the partition 18.
  • the motor 64 is turned on to rotate the take-up roll 62 and thereby pull the sheet material 50 to be coated from the supply roll 48, and across the opening 28 in the partition 18 and across the contacts 70 and 72.
  • the tachometer 68 controls the speed of the motor 62 through the speed control 66 to maintain a constant linear speed of the sheet material 50.
  • the heater 28 within the container 26 is turned on to heat the coating material 34 to the temperature at which the coating metal 34 will evaporate at the pressure within the evaporation chamber 1-4.
  • the surface of the sheet material 58 is coated with a film of the metal 34, which film is of a thickness according to the amount of the vapors which contact and condense on the sheet material 50.
  • the strip or wire 38 of the coating metal is constantly fed from the supply reel 36 by the feed roll 40 into the boat 30 to maintain a desired amount of the coating metal 34 within the boat 30.
  • the amount of the coating metal 34 within the boat 30 determines the amount of the vapors which evaporate from the coating metal 34, and thereby determines the thickness of the metal film coated on the sheet material 50. Since the outer wall 32 of the boat 30 tapers, the more coating metal 34 within the boat 38 the greater the surface area of the coating metal 34, and the greater the amount of vapors which will evaporate from the coating metal 34.
  • the resistance value of the portion of the metal film between the contacts 70 and 72 is constantly measured by the resistance measuring and control circuit 84. It is well known that the electrical resistance of a thin metal film varies with the thickness of the film, with the electrical resistance decreasing with an increase in the thickness of the metal film.
  • the resistance measuring and control circuit 84 is balanced against a resistance value which is provided by a metal film of the desired thickness. Thus, as long as the metal film coated on the sheet material 50 is of the desired thickness, the resistance measuring and control circuit 84 will remain balanced.
  • the resistance measured between the contacts '70 and 72 will decrease causing an unbalance of the resistance measuring and control circuit 84.
  • the unbalance of the resistance measuring and control circuit 84- caused by a decrease in the resistance be tween the contacts 78 and 72 will operate the rheostat of the control circuit 84 to decrease the speed of the motor 46.
  • This in turn decreases the amount of the strip or wire 38 of the coating metal being fed into the boat 30 so as to decrease the amount of the metal 34 within the boat 30.
  • the amount of vapors evaporated from the metal 34 is decreased to decrease the thickness of the 4 metal film coated on the sheet material 50 until the thickness of the metal film applied to the sheet material 50- is back to a desired thickness.
  • the resistance across the contacts 70 and 72 increases.
  • the increase in the resistance value across the contacts '70 and 72 unbalances the resistance measuring circuit 84 so that the rheostat of the circuit 84 increases the speed of the motor 46.
  • This in turn increases the speed of the feed of the strip or wire 38 into the boat 38 so as to increase the amount of the metal 34 within the boat 38.
  • the amount of vapors evaporated from the metal 34 is increased to increase the thickness of the film coated on the sheet material 50 back to the desired thickness.
  • the sheet material 50 is moved at a constant speed across the opening 20 where the surface of the sheet material 50 is coated with a thin film of metal.
  • Any variations in the thickness of the film of metal coated on the sheet material 50 causes the resistance measuring and control circuit 84 to properly operate the motor 46 so as to vary the amount of coating material in the boat 30.
  • the variations in the amount of the metal within the boat 30 varies the amount of vapors evaporated from the coating metal within the boat 30 in a manner to compensate for any variations in the thickness of the metal film on the sheet material 50.
  • variations in the thickness of the metal film are automatically compensated for to provide the sheet material 50 with a coating of the metal which is of substantially uniform thickness.
  • Apparatus for coating a continuously moving sheet of material with a metal film comprising a housing, means for evacuating said housing, a boat Within said housing for containing the coating metal, means for heating said boat to evaporate the coating metal, means for continuously moving the sheet of material across the boat to continuously expose the sheet of material to the metal vapors difiusing from the boat, means for continuously measuring the electrical resistance per unit length of the metal film coating on the sheet of material, the improvement comprising means operated by a variation in the resistance measured to vary the surface area of the coating metal within the boat.
  • Apparatus for coating a continuous moving sheet of material with a metal film comprising a housing, means for evacuating said housing, a boat within said housing for containing the coating metal, means for heating the boat to evaporate the coating metal, a supply reel of a strip of the coating metal within said housing, means for feeding said strip to said boat, means for continuously moving the sheet of material across the boat to expose the sheet of material to the metalvapors difiusing from the boat, means for continuously measuring the electrical resistance per unit length of the metal film coating on the sheet material, the improvement comprising means operated by a variation in the resistance measured to vary the speed of the feed of the strip into the boat to vary the surface area of the coating metal in said boat.
  • Apparatus in accordance with claim 2 in which the means for varying the speed of the feed of the strip increases the speed upon an increase of the resistance measured, and decreases the speed upon a decrease of the resistance measured.
  • Apparatus for coating a continuously moving sheet of material with a metal film comprising a housing having an evaporating chamber and a coating chamber sepa rated by a common partition, said pantition having an opening therethrough, means for evacuating said housing, a boat within said evaporating chamber beneath the opening in the partition, means for heating said boat, a supply reel of the strip of the coating metal mounted in said evaporating chamber, means for feeding said strip of coating metal into said boat, a supply roll of the sheet of material rotatably mounted within the coating chamber, a take-up roll mounted Within said coating chamber, means for guiding said sheet of material from said supply roll to said take-up roll so that the sheet of material passes across the opening in the partition, means for rotating said take-up roll, a pair of contacts mounted in spaced relation along the path of travel of the sheet of material between the opening in the partition and the take-up roll, said contacts being adapted to engage the metal coating on the sheet of material, means for measuring the electrical resistance between said contacts, the improvement
  • Apparatus in accordance with claim 5 in which the means for varying the speed of the feed of the strip increases the speed upon an increase of the measured resistance and decreases the speed upon a decrease of the measured resistance.
  • a method of coating a continuous sheet of material with a metal film comprising feeding a coating metal into a boat, heating said boat to vaporize the coating metal, continuously moving the sheet of material across the top of the boat, continuously exposing the sheet of material to the metal vapors from the boat, continuously measuring the electrical resistance per unit length of metal film applied to the sheet of material, and varying the amount of material fed into the boat to vary the surface area of the coating metal in said boat according to variations in the measured resistance.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
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  • Microelectronics & Electronic Packaging (AREA)
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Description

APril 1963 R. v. D. STRONG 3,086,889
METHOD AND APPARATUS FOR COATING A CONTINUOUS SHEET 0F MATERIAL Filed March 21, 1960 INVENTOR. RICHARD V. D. STRONG ATTORNEY 3,086,889 METHOD AND APRARATUS FQR COATHQG A CONTINUOUS SHEET F MATERIAL Richard V. D. Strong, Meadowbrook, Pa, assignor to F. J. Stokes Corporation, Philadelphia, Pa, a corporation of Pennsylvania Filed Mar. 21, 1960, Ser. No. 164% 8 Claims. (Cl. 117--227) The present invention relates to a method and apparatus for coating a continuous sheet of material, and more particularly to a method and apparatus for applying a thin continuous metal film or a uniform thickness to a dielectric sheet material in a continuous operation.
The coating method herein concerned is one in which the sheet material to be coated is passed continuously through a 'low pressure chamber or zone in which a coating metal is vaporized. The vaporized metal deposits on the material to form the coating. In such a process a major problem has been to obtain a coating which is of uniform thickness along the entire length of the sheet material. For many purposes, as in the production of metal coated paper or electrical condensers, variations of coating thicknesses cannot be tolerated.
It is an object of the present invention to provide a novel coating apparatus.
It is another object of the present invention to provide a novel apparatus for coating a continuously moving sheet material with a thin metal tilm.
It is still another object of the present invention to provide an apparatus for applying a thin metal film of a uniform thickness to a continuously moving sheet material.
It is a further object of the present invention to provide a method for the application of a thin continuous metal film of a uniform thickness to a continuously moving sheet material.
Other objects will appear hereinafter.
For the purpose of illustrating the invention there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
The drawing is a schematic sectional view of the coating apparatus of the present invention.
Referring to the drawing, the coating apparatus of the present invention is generally designated as 10.
Coating apparatus 10 comprises a housing 12 which is completely enclosed so that the interior of the housing is hermetically sealed from the atmosphere. The housing 12 contains an evaporation chamber 14 along the bottom portion thereof, and a coating chamber 16 above the evaporation chamber 14. A horizontal partition 18 divides the evaporation chamber 14 from the coating chamber 16. The partition 18 has an opening 20 therethrough adjacent one side of the housing 12 to permit the coating metal vapors to pass from the evaporation chamber 14 to the coating chamber 16. The partition 18 also has an opening 22 therethrough to permit equalization of the pressures within the coating chamber 16 and the evaporation chamber 14. A pipe 24 connects the interior of the evaporation chamber 14 to means for creating a vacuum, such as a vacuum pump, not shown.
A container 26 of a thermal insulation material is mounted within the evaporation chamber '14 directly beneath the opening 20 in the partition 18. The container 26 contains a heater 28, such as an electrical resistance heater. A boat or cup 30 of a material which will withstand high temperatures is seated in the container 26 above the heater 28. The outer wall 62 of the boat 30 tapers so that the area encompassed by the bottom portion of the wall 32 is smaller than the area encompassed by the top portion of the wall 32. The boat 30 contains the 3,086,889 Patented Apr. 23, 1963 source of the coating metal 34. A reel 36 containing a strip or wire 38 of the coating metal is rotatably mounted on the side wall of the housing 12 within the evaporation chamber 14. The strip or wire 38 of the coating metal passes from the reel 36 between a pair of mating teed rolls 40 and 42, and through a guide tube 44 to the boat 30. The feed roll 49 is driven by an electric motor 46 mounted outside of the housing 12. The frictional engagement between the rotating feed roll 40 and the strip or wire 38 feeds the strip or wire 38 to the boat 30 so as .to maintain a constant supply of the coating material 34 within the coat 30.
A supply roll 48 of the sheet material 50 to be coated is rotatably mounted about a horizontal axis within the coating chamber 16 adjacent the top of the housing 12. A backing plate 52 is mounted slightly above the partition 18, and extends across the opening 29 in the partition 18. A pair of guide rolls 54 and 56 are rotatably mounted along each side of the backing plate 52. The sheet material 50 to be coated passes from the supply roll 48 downwardly to and around the .guide roll 54. The sheet material 50 then passes under the backing plate 52 and across the opening 20 in the partition 18. From the guide roll 56, the sheet material 50 passes upwardly around a pair of vertically spaced guide rolls 58 and 60 to a take-up roll 62 which is mounted adjacent the supply roll 48.
The take-up roll 62 is driven by an electric motor 64 which is mounted on the top of the housing 12. Motor 64 is electrically connected to a source of electrical current through a speed control 66. A tachometer 68 is mounted on the side of the housing 12, and is connected to the guide roll 60. The tachometer 68 continuously measures the speed of rotation of the guide roll 60 as the sheet of material 50 passes around the guide roll 60. The tachometer 68 is electrically connected to the speed control 66 of the motor 64. Any variations in the speed of rotation of the guide roll 60 from a predetermined setting of the tachometer 68 will operate the speed control 66 to vary the speed of the motor 64. The speed of the motor 64 is varied to change the speed of rotation of the take-up roll 62 so that the speed of rotation of guide roll 60 is returned to the predetermined speed through the variation in the speed of the sheet of material 50. Thus, as the linear speed of the movement of the sheet matrial 50 increases as more of the material 50 is wound on the take-up roll 62, the tachometer 68 will operate the speed control 66 to slow down the motor 64 and thereby maintain the linear speed of the sheet material 50 constant.
A pair of electrical contacts 70 and 72 engage the coated side of the sheet material 58 at spaced points between the guide rolls 58 and 60. The contacts 70 and 72 are mounted on the ends of posts 74 and 76 which extend through and are supported on the side of the housing 12. The posts 74 and 76 are insulated from the housing 12 by bushings 78 of an electrical insulating material. The posts 74 and 76 are electrically connected by wires 80 and 82 respectively to a resistance measuring and control circuit, generally designated as 84, The resistance measuring and control circuit 84 may include a bridge circuit which is balanced against the resistance measured between the contacts 70 and 72. Such a bridge circuit is of the type which will provide an electrical signal upon any variation in the resistance measured between the contacts 70 and 72, which signal is of a polarity determined by whether the resistance measured between the contacts 70 and 72 increases or decreases. There are many types of resistance measuring bridges well known in the which will function in this manner, such as the resistance measuring bridge shown and described in Patent No. 2,545,576 to Philip Godley, 2nd issued March 20, 1951.
The resistance measuring and control circuit 84 may also include a rheostat which is operated by the signal from the bridge circuit in the manner shown in Patent No. 2,545,576. The rheostat is electrically connected by the wires 86 and 88 to the motor 46 which drives the feed roll 48 for the strip or wire 38. The resistance measuring and control circuit 84- is connected to the motor 46 so that an increase in the resistance measured between the contacts 70 and 72 will increase the speed of the motor 46, and a decrease in the resistance measured between the contacts 70 and 72 will decrease the speed of the motor 46.
The coating apparatus 18 of the present invention operates as follows:
The evaporating chamber 14 is evacuated through the pipe 2d which is attached to a vacuum pump. Evacuation of the evaporating chamber 14 also evacuates the coating chamber '16 which is in communication with the evaporating chamber 14- through the opening 22 in the partition 18. The motor 64 is turned on to rotate the take-up roll 62 and thereby pull the sheet material 50 to be coated from the supply roll 48, and across the opening 28 in the partition 18 and across the contacts 70 and 72. As previously described, the tachometer 68 controls the speed of the motor 62 through the speed control 66 to maintain a constant linear speed of the sheet material 50.
The heater 28 within the container 26 is turned on to heat the coating material 34 to the temperature at which the coating metal 34 will evaporate at the pressure within the evaporation chamber 1-4. The vapors from the coating metal 34!- ditfuse upwardly through the opening 20 in the partition 18, and condense on the surface of the sheet material 50 to provide a film of the metal on the sheet material 50. Thus, as the sheet material 50 is pulled across the opening 20 in the partition 18, the surface of the sheet material 58 is coated with a film of the metal 34, which film is of a thickness according to the amount of the vapors which contact and condense on the sheet material 50. The strip or wire 38 of the coating metal is constantly fed from the supply reel 36 by the feed roll 40 into the boat 30 to maintain a desired amount of the coating metal 34 within the boat 30. The amount of the coating metal 34 within the boat 30 determines the amount of the vapors which evaporate from the coating metal 34, and thereby determines the thickness of the metal film coated on the sheet material 50. Since the outer wall 32 of the boat 30 tapers, the more coating metal 34 within the boat 38 the greater the surface area of the coating metal 34, and the greater the amount of vapors which will evaporate from the coating metal 34.
As the coated sheet material 50 passes across the contacts 70 and 72, the resistance value of the portion of the metal film between the contacts 70 and 72 is constantly measured by the resistance measuring and control circuit 84. It is well known that the electrical resistance of a thin metal film varies with the thickness of the film, with the electrical resistance decreasing with an increase in the thickness of the metal film. The resistance measuring and control circuit 84 is balanced against a resistance value which is provided by a metal film of the desired thickness. Thus, as long as the metal film coated on the sheet material 50 is of the desired thickness, the resistance measuring and control circuit 84 will remain balanced.
However, if the thickness of the metal film coated on the sheet material increases, the resistance measured between the contacts '70 and 72 will decrease causing an unbalance of the resistance measuring and control circuit 84. The unbalance of the resistance measuring and control circuit 84- caused by a decrease in the resistance be tween the contacts 78 and 72 will operate the rheostat of the control circuit 84 to decrease the speed of the motor 46. This in turn decreases the amount of the strip or wire 38 of the coating metal being fed into the boat 30 so as to decrease the amount of the metal 34 within the boat 30. Thus, the amount of vapors evaporated from the metal 34 is decreased to decrease the thickness of the 4 metal film coated on the sheet material 50 until the thickness of the metal film applied to the sheet material 50- is back to a desired thickness.
If the thickness of the metal film coated on the sheet material decreases, the resistance across the contacts 70 and 72 increases. The increase in the resistance value across the contacts '70 and 72 unbalances the resistance measuring circuit 84 so that the rheostat of the circuit 84 increases the speed of the motor 46. This in turn increases the speed of the feed of the strip or wire 38 into the boat 38 so as to increase the amount of the metal 34 within the boat 38. Thus, the amount of vapors evaporated from the metal 34 is increased to increase the thickness of the film coated on the sheet material 50 back to the desired thickness.
Thus, in the coating apparatus 10 of the present invention, the sheet material 50 is moved at a constant speed across the opening 20 where the surface of the sheet material 50 is coated with a thin film of metal. Any variations in the thickness of the film of metal coated on the sheet material 50 causes the resistance measuring and control circuit 84 to properly operate the motor 46 so as to vary the amount of coating material in the boat 30. The variations in the amount of the metal within the boat 30 varies the amount of vapors evaporated from the coating metal within the boat 30 in a manner to compensate for any variations in the thickness of the metal film on the sheet material 50. Thus, variations in the thickness of the metal film are automatically compensated for to provide the sheet material 50 with a coating of the metal which is of substantially uniform thickness.
The present invention may be provided with specific forms Without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.
I claim:
1. Apparatus for coating a continuously moving sheet of material with a metal film comprising a housing, means for evacuating said housing, a boat Within said housing for containing the coating metal, means for heating said boat to evaporate the coating metal, means for continuously moving the sheet of material across the boat to continuously expose the sheet of material to the metal vapors difiusing from the boat, means for continuously measuring the electrical resistance per unit length of the metal film coating on the sheet of material, the improvement comprising means operated by a variation in the resistance measured to vary the surface area of the coating metal within the boat.
2. Apparatus for coating a continuous moving sheet of material with a metal film comprising a housing, means for evacuating said housing, a boat within said housing for containing the coating metal, means for heating the boat to evaporate the coating metal, a supply reel of a strip of the coating metal within said housing, means for feeding said strip to said boat, means for continuously moving the sheet of material across the boat to expose the sheet of material to the metalvapors difiusing from the boat, means for continuously measuring the electrical resistance per unit length of the metal film coating on the sheet material, the improvement comprising means operated by a variation in the resistance measured to vary the speed of the feed of the strip into the boat to vary the surface area of the coating metal in said boat.
3. Apparatus in accordance with claim 2 in which the means for varying the speed of the feed of the strip increases the speed upon an increase of the resistance measured, and decreases the speed upon a decrease of the resistance measured.
4. Apparatus in accordance with claim 2 in which the boat has an outer wall which tapers outwardly from the bottom of the boat.
5. Apparatus for coating a continuously moving sheet of material with a metal film comprising a housing having an evaporating chamber and a coating chamber sepa rated by a common partition, said pantition having an opening therethrough, means for evacuating said housing, a boat within said evaporating chamber beneath the opening in the partition, means for heating said boat, a supply reel of the strip of the coating metal mounted in said evaporating chamber, means for feeding said strip of coating metal into said boat, a supply roll of the sheet of material rotatably mounted within the coating chamber, a take-up roll mounted Within said coating chamber, means for guiding said sheet of material from said supply roll to said take-up roll so that the sheet of material passes across the opening in the partition, means for rotating said take-up roll, a pair of contacts mounted in spaced relation along the path of travel of the sheet of material between the opening in the partition and the take-up roll, said contacts being adapted to engage the metal coating on the sheet of material, means for measuring the electrical resistance between said contacts, the improvement comprising means operating by a change in the resistance between said contacts to change the speed of the feed of the strip of coating material into the boat to vary the surface area or the coating metal in said boat.
6. Apparatus in accordance with claim 5 in which the means for varying the speed of the feed of the strip increases the speed upon an increase of the measured resistance and decreases the speed upon a decrease of the measured resistance.
7. Apparatus in accordance with claim 6 in which the boat has an outer wall which tapers outwardly from the bottom of the boat.
8. A method of coating a continuous sheet of material with a metal film comprising feeding a coating metal into a boat, heating said boat to vaporize the coating metal, continuously moving the sheet of material across the top of the boat, continuously exposing the sheet of material to the metal vapors from the boat, continuously measuring the electrical resistance per unit length of metal film applied to the sheet of material, and varying the amount of material fed into the boat to vary the surface area of the coating metal in said boat according to variations in the measured resistance.
References Cited in the file of this patent UNITED STATES PATENTS 2,273,941 Dorn Feb. 24, 1942 2,545,576 Godley Mar. 20, 1951 2,750,921 Purdy June 19, 1956 2,772,318 Holland Nov. 27, 1956 2,366,065 Hirsh Dec. 23, 1958 2,978,364 Blaustein Apr. 4, 1961 FOREIGN PATENTS 288,438 Switzerland May 16, 1953 752,141 Germany Feb. 1, 1954

Claims (1)

  1. 8. A METHOD OF COATING A CONTINUOUS SHEET OF MATERIAL WITH A METAL FILM COMPRISING FEEDING A COATING METAL INTO A BOAT, HEATING SAID BOAT TO VAPORIZE THE COATING METAL, CONTINUOUSLY MOVING THE SHEET OF MATERIAL ACROSS THE TOP OF THE BOAT, CONTINUOUSLY EXPOSING THE SHEET OF MATERIAL TO THE METAL VAPORS FROM THE BOAT, CONTINUOUSLY MEASUREING THE ELECTRICAL RESISTANCE PER UNIT LENGTH OF METAL FILM APPLIED TO THE SHEET OF MATERIAL, AND VARYING THE AMOUNT OF MATERIAL FED INTO THE BOAT TO VARY THE SURFACE AREA OF THE COATING METAL IN SAID ACCORDING TO VARIATIONS IN THE MEASURED RESISTANCE.
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Cited By (20)

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US3353895A (en) * 1962-04-16 1967-11-21 Polaroid Corp Light polarizer comprising filamentous particles on surface of transparent sheet and method of making same
US3362848A (en) * 1964-03-03 1968-01-09 Mc Donnell Douglas Corp Apparatus and method for evaporative coating
US3394678A (en) * 1966-12-23 1968-07-30 Air Reduction Apparatus for vacuum coating
US3400687A (en) * 1966-02-25 1968-09-10 Sylvania Electric Prod Film thickness monitoring apparatus
US3411082A (en) * 1962-12-20 1968-11-12 Centre Nat Rech Metall Method of measuring the potential difference across a conductive sheet material for controlling the pickling of said sheet
US3453984A (en) * 1966-09-16 1969-07-08 Ppg Industries Inc Apparatus for measuring and controlling film thickness
US3570449A (en) * 1969-03-13 1971-03-16 United Aircraft Corp Sensor system for a vacuum deposition apparatus
US3590777A (en) * 1969-03-13 1971-07-06 United Aircarft Corp Ingot feed drive
US3750623A (en) * 1972-02-11 1973-08-07 Mc Donnell Douglas Corp Glow discharge coating apparatus
US3831551A (en) * 1972-04-14 1974-08-27 Owens Corning Fiberglass Corp Apparatus for coating filamentary material
US3854442A (en) * 1971-08-20 1974-12-17 Bosch Gmbh Robert Vapor-deposition apparatus
US3881036A (en) * 1972-06-23 1975-04-29 William H Brown Galvanizing continuous elements with prevention of corrosion of the pan
FR2379146A1 (en) * 1977-01-28 1978-08-25 Siemens Ag REGENERABLE ELECTRIC CAPACITOR AND METHOD FOR ITS MANUFACTURING
WO1987001623A1 (en) * 1985-09-12 1987-03-26 Dennison Manufacturing Company Metallization of substrates
US4953497A (en) * 1987-08-06 1990-09-04 Leybold Aktiengesellschaft Apparatus for coating continuous webs
US5383969A (en) * 1993-04-05 1995-01-24 Cvd, Inc. Process and apparatus for supplying zinc vapor continuously to a chemical vapor deposition process from a continuous supply of solid zinc
DE19943379A1 (en) * 1999-09-10 2001-03-15 Fraunhofer Ges Forschung Production of metallized plastic foils comprises vaporizing the metal to be applied in the vaporizing chamber of the strip vaporization plant strip with ignition of a plasma
US6461667B1 (en) * 2000-04-04 2002-10-08 Eastman Kodak Company Apparatus and method for vapor depositing lubricant coating on a web
WO2016168636A1 (en) * 2015-04-17 2016-10-20 Ball Corporation Method and apparatus for controlling the speed of a continuous sheet of material
US10421111B2 (en) 2015-04-17 2019-09-24 Ball Corporation Method and apparatus for controlling an operation performed on a continuous sheet of material

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US2545576A (en) * 1948-02-21 1951-03-20 Nat Res Corp Automatic control of evaporated metal film thickness
CH288438A (en) * 1950-10-23 1953-01-31 Alois Dr Vogt Method for applying metal coatings to elongated work items, as well as device for carrying out the method.
DE752141C (en) * 1942-08-07 1954-02-01 Bosch Gmbh Robert Device for controlling the supply of material for evaporation in a vacuum
US2750921A (en) * 1953-01-12 1956-06-19 Western Electric Co Tension control apparatus for thermal vaporizing coating device
US2772318A (en) * 1952-12-31 1956-11-27 Holland Leslie Arthur Apparatus for vaporization of metals and metalloids
US2866065A (en) * 1957-02-26 1958-12-23 Bulova Res And Dev Lab Inc Signalling device for vacuum evaporation system
US2978364A (en) * 1956-03-05 1961-04-04 Fairchild Camera Instr Co Automatic control system for precision resistor manufacture

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US2273941A (en) * 1937-08-11 1942-02-24 Bosch Gmbh Robert Process for the production of resistances
DE752141C (en) * 1942-08-07 1954-02-01 Bosch Gmbh Robert Device for controlling the supply of material for evaporation in a vacuum
US2545576A (en) * 1948-02-21 1951-03-20 Nat Res Corp Automatic control of evaporated metal film thickness
CH288438A (en) * 1950-10-23 1953-01-31 Alois Dr Vogt Method for applying metal coatings to elongated work items, as well as device for carrying out the method.
US2772318A (en) * 1952-12-31 1956-11-27 Holland Leslie Arthur Apparatus for vaporization of metals and metalloids
US2750921A (en) * 1953-01-12 1956-06-19 Western Electric Co Tension control apparatus for thermal vaporizing coating device
US2978364A (en) * 1956-03-05 1961-04-04 Fairchild Camera Instr Co Automatic control system for precision resistor manufacture
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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3353895A (en) * 1962-04-16 1967-11-21 Polaroid Corp Light polarizer comprising filamentous particles on surface of transparent sheet and method of making same
US3411082A (en) * 1962-12-20 1968-11-12 Centre Nat Rech Metall Method of measuring the potential difference across a conductive sheet material for controlling the pickling of said sheet
US3362848A (en) * 1964-03-03 1968-01-09 Mc Donnell Douglas Corp Apparatus and method for evaporative coating
US3400687A (en) * 1966-02-25 1968-09-10 Sylvania Electric Prod Film thickness monitoring apparatus
US3453984A (en) * 1966-09-16 1969-07-08 Ppg Industries Inc Apparatus for measuring and controlling film thickness
US3394678A (en) * 1966-12-23 1968-07-30 Air Reduction Apparatus for vacuum coating
US3570449A (en) * 1969-03-13 1971-03-16 United Aircraft Corp Sensor system for a vacuum deposition apparatus
US3590777A (en) * 1969-03-13 1971-07-06 United Aircarft Corp Ingot feed drive
US3854442A (en) * 1971-08-20 1974-12-17 Bosch Gmbh Robert Vapor-deposition apparatus
US3750623A (en) * 1972-02-11 1973-08-07 Mc Donnell Douglas Corp Glow discharge coating apparatus
US3831551A (en) * 1972-04-14 1974-08-27 Owens Corning Fiberglass Corp Apparatus for coating filamentary material
US3881036A (en) * 1972-06-23 1975-04-29 William H Brown Galvanizing continuous elements with prevention of corrosion of the pan
FR2379146A1 (en) * 1977-01-28 1978-08-25 Siemens Ag REGENERABLE ELECTRIC CAPACITOR AND METHOD FOR ITS MANUFACTURING
WO1987001623A1 (en) * 1985-09-12 1987-03-26 Dennison Manufacturing Company Metallization of substrates
US4943446A (en) * 1985-09-12 1990-07-24 Dennison Manufacturing Company Metallization of substrates
US4953497A (en) * 1987-08-06 1990-09-04 Leybold Aktiengesellschaft Apparatus for coating continuous webs
US5383969A (en) * 1993-04-05 1995-01-24 Cvd, Inc. Process and apparatus for supplying zinc vapor continuously to a chemical vapor deposition process from a continuous supply of solid zinc
DE19943379A1 (en) * 1999-09-10 2001-03-15 Fraunhofer Ges Forschung Production of metallized plastic foils comprises vaporizing the metal to be applied in the vaporizing chamber of the strip vaporization plant strip with ignition of a plasma
US6461667B1 (en) * 2000-04-04 2002-10-08 Eastman Kodak Company Apparatus and method for vapor depositing lubricant coating on a web
WO2016168636A1 (en) * 2015-04-17 2016-10-20 Ball Corporation Method and apparatus for controlling the speed of a continuous sheet of material
US10073443B2 (en) 2015-04-17 2018-09-11 Ball Corporation Method and apparatus for controlling the speed of a continuous sheet of material
US10421111B2 (en) 2015-04-17 2019-09-24 Ball Corporation Method and apparatus for controlling an operation performed on a continuous sheet of material

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