EP0245500A1 - Procede et appareil pour l'elimination rapide de materiaux organiques contenus dans des pellicules par chauffage dans un champ electrique - Google Patents

Procede et appareil pour l'elimination rapide de materiaux organiques contenus dans des pellicules par chauffage dans un champ electrique

Info

Publication number
EP0245500A1
EP0245500A1 EP87900393A EP87900393A EP0245500A1 EP 0245500 A1 EP0245500 A1 EP 0245500A1 EP 87900393 A EP87900393 A EP 87900393A EP 87900393 A EP87900393 A EP 87900393A EP 0245500 A1 EP0245500 A1 EP 0245500A1
Authority
EP
European Patent Office
Prior art keywords
film
electric field
electrodes
heating
heating chamber
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.)
Withdrawn
Application number
EP87900393A
Other languages
German (de)
English (en)
Other versions
EP0245500A4 (fr
Inventor
David K. Flattery
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.)
Radiant Tech Corp
Original Assignee
Radiant Tech Corp
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 Radiant Tech Corp filed Critical Radiant Tech Corp
Publication of EP0245500A1 publication Critical patent/EP0245500A1/fr
Publication of EP0245500A4 publication Critical patent/EP0245500A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
    • H05K3/1283—After-treatment of the printed patterns, e.g. sintering or curing methods
    • H05K3/1291—Firing or sintering at relative high temperatures for patterns on inorganic boards, e.g. co-firing of circuits on green ceramic sheets
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B23/00—Heating arrangements
    • F26B23/04—Heating arrangements using electric heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B7/00—Drying solid materials or objects by processes using a combination of processes not covered by a single one of groups F26B3/00 and F26B5/00
    • F26B7/002—Drying solid materials or objects by processes using a combination of processes not covered by a single one of groups F26B3/00 and F26B5/00 using an electric field and heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
    • F27B9/062—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated electrically heated
    • F27B9/063—Resistor heating, e.g. with resistors also emitting IR rays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/28—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity for treating continuous lengths of work
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/40—Arrangements of controlling or monitoring devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/36—Arrangements of heating devices
    • F27B2009/3638—Heaters located above and under the track
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27M—INDEXING SCHEME RELATING TO ASPECTS OF THE CHARGES OR FURNACES, KILNS, OVENS OR RETORTS
    • F27M2003/00—Type of treatment of the charge
    • F27M2003/08—Curing; Baking
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/10—Using electric, magnetic and electromagnetic fields; Using laser light
    • H05K2203/105—Using an electrical field; Special methods of applying an electric potential
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/11—Treatments characterised by their effect, e.g. heating, cooling, roughening
    • H05K2203/1126—Firing, i.e. heating a powder or paste above the melting temperature of at least one of its constituents

Definitions

  • This invention relates to an apparatus and method for removing organic components from films, particularly thick film compositions, by heating in an electric field.
  • Thick films comprise one or more layers of conductive and/or dielectric inks which are deposited on insulative substrates to form electronic circuit elements such as resistors, conductors, capacitors, and the like. Thick films are typically applied to the substrate as a paste, the pattern for the desired electronic circuit component being formed by the use of a fine mesh screen utilizing silk screening techniques. Once the desired pattern is formed, the substrate is dried at low temperatures and then fired at high temperatures.
  • Thick film pastes generally include organic-containing solvents and a temporary organic binder.
  • the organic binder serves to provide dimensional stability to the dried print and to give it green strength for handling through firing. As the thick film heats up in the firing cycle, the first thing that occurs is burnout, i.e. the removal of any remaining solvent and the temporary organic binder. Following solvent and binder removal, the conductive or dielectric particles of the paste fuse together.
  • binder removal must be completely removed before any of the conductive or dielectric particles fuse together. Binder removal must occur cleanly, i.e., no reducing species can be allowed to remain to attackthe fused conductive ordielectricparticles. Moreover, the decomposed binder components must be removed from the process area immediately.
  • the present invention provides a method and apparatus for enhancing the removal of organic material from organic- containing films such as conductive and dielectric thick films.
  • the method comprises establishing an electric field around the film while heating the film, preferably to a temperature sufficient to cause at least some organic components of the film to form organic ions, i.e. , carbanions and carbonium ions.
  • the strength of the electric field is sufficient to increase the rate at which organic components are removed from the film and/or decrease the quantity of organic components left in the film as a residue after firing.
  • the upper limit is that which detrimentally affects the chemical or physical properties of the films or at which the atmosphere surrounding the thick film, e.g., air or nitrogen, begins to break down. It is preferred that an electric field strength of at least about 200 V/cm, preferably at least about 4000 V/cm and preferably no more than about 7500 V/cm be used.
  • the orientation of the electric field is not critical. However, the electric field is preferably established in an orientation normal to the top- surface of the film, preferably with a polarity that exerts an upward force on carbonium ions in the thick film.
  • An apparatus for removing organic components from organic-containing films in accordance with the present invention comprises a heating chamber having one or more heating elements, preferably infrared lamps.
  • a first voltage source is connected to the heating elements to provide energy to the heating elements.
  • At least two spaced-apart elec- trodes are provided which are connected to a second voltage source for generating an electric field within the chamber.
  • Means are also provided for supporting a substrate on which an organic-containing film has been deposited within the electric field generated by the electrodes.
  • means are also provided for introducing a select, preferably non-reactive gas, e.g., nitrogen, into the chamber.
  • the appa ⁇ ratus comprises a heating chamber having entrance and exit openings.
  • a motor driven metal conveyor belt runs through the chamber, passing through each opening.
  • Substrates on which an organic-containing film has been applied can be carried through the chamber on the conveyor.
  • Heating elements preferably infrared lamps, are mounted in the chamber, preferably above and below the conveyor and are electrically connected to a voltage source.
  • one or more electrodes are mounted above the conveyor belt, which acts as a second electrode.
  • the electrode(s) and the metal conveyor belt are electrically connected to a voltage source for generating an electric field within the chamber. Control circuits are provided for regulating the speed of the conveyor, the amount of energy radiated by the infrared lamps and the strength of the electric field generated between the electrodes.
  • FIG. 1 is a schematic block diagram of an infrared furnace constructed in accordance with the present invention
  • FIG. 2 is a perspective view of a heating chamber of an infrared furnace constructed in accordance with the present invention
  • FIG. 3 is a longitudinal cross-sectional view of the heating chamber shown in FIG. 2;
  • FIG. 4 is a transverse cross-sectional view of the heating chamber shown in FIG. 2 and 3 taken along lines 4-4;
  • FIG. 5 is a enlarged cross-sectional view showing the end portion of the electrode mounted in a ceramic holder secured to the side wall of the heating chamber.
  • a particularly preferred applications of the present invention is in providing an apparatus and process for firing thick films.
  • the thick films and the insulated substrates on which thick films have been applied are heated to a temperature and for a time sufficient to cause the removal of organic components from the film and then to fuse the conductive or dielectric particles present in the film.
  • At least the initial heating of the thick films to remove organic components is performed in the presence of an electric field. The presence of the electric field enhances the removal of the organic components from the thick film, increasing the rate at which the organic components are removed and/or decreasing the residual amount of carbon remaining in the film after firing.
  • the thick film is heated to a temperature of about 900*C.
  • the temporary organic binder is removed in the initial stages of the process, generally at temperatures below about 600*C.
  • the organic components undergo pyrolysis or combustion to form organic ions, e.g. , carbonium ions and carbanions. This typically occurs at about 300'C in air and about 350*C in nitrogen.
  • the strength of the electric field must be sufficient to increase the rate of organic removal and/or quantity of organic components removed from the thick film during heating.
  • an electric field strength of at least about 200 V/cm is required to produce any significant improvement in the rate and/or quantity of organic removal.
  • the maximum electric field strength is that which the atmosphere surrounding the thick film, e.g., air, nitrogen, oxygen, and the like, begins to breakdown. This occurs at about 7500 V/cm for air and nitrogen. It is believed that there are two separate mechanisms involved in the enhancement of organic removal from thick films by the use of the electric field. First, the electri ⁇ cal field induces a force on the carbonium ions or carbanions formed in the initial stages of the firing process in a direction out of the thick film.
  • boundary layer develops at the surface of the thick film.
  • the boundary layer is a static or stagnant layer of the gas in which the thick film is being heated which is adjacent to the thick film surface.
  • the boundary layer resists heat conduction to the film and mass diffusion away from the film and is thus a controlling factor in a heating process for removing organic components from thick films. It has been found that the presence of an electric field around the thick filmdisturbstheboundarylayerand, if sufficiently strong, will eliminate or at least reduce the thickness of the boundary layer. This permits not only more rapid heating of the thick film but more rapid transport of organic components away from the surface of the thick film.
  • the electric field be sufficient to eliminate or at least significantly reduce the thickness of the boundary layer. It has been found that an electric field having a strength of about 1000 V/cm, is sufficient for this purpose.
  • the orientation of the electric field i.e., the dir ⁇ ection of the lines of force while not critical, is prefer ⁇ ably normal to the upper surface of the thick film and the top surface of the insulative substrate. Since the thickness of conventional thick films is generally much less than the width of the thick film, such an orientation generates a force acting on charged organic ions, either positive or negative ions depending on the polarity of the electric field, in a direction towards the top surface of the thick -8- film which for the majority of the charged ions is the closest surface.
  • the polarity of the electric field is not critical. However, it has been found that a greater reduction in the carbon content of thick films is accomplished when the electric field has a polarity which induces a force on carbonium ions in a direction towards the upper surface of the thick film, than when the electric field has a polarity, which induces a force on carbanions in a direction towards the top surface of the thick film.
  • the reason for this is believed to lay in the pathways through which the organic compounds decompose or breakdown during the firing process.
  • the decomposition of organic material compounds may take place through the cleavage of carbon-carbon bonds with no charge being developed, i.e. through the formation of free-radicals, or it may take place through the formation of oppositely charged ions.
  • Free-radicals areveryshort-lived, energeticallyunfavorable species that would not be expected to make up the majority of the diffusing species.
  • Charged intermediates will be subjected to a force when the electric field is applied. This force will vary in magnitude and direction depending on the strength and polarity of the applied field. If the intermediates included charged species, one positive ion will be created for every negative ion.
  • the stability of carbon ions depends on the degree of substitution at the carbon that carries the charge.
  • Primary, secondary, and tertiary carbons are those bonded to one, two, or three other carbons respectively.
  • the stability of carbon ions depends on their degree of substitution and charge. Positively charged carbon ions, or carbonium ions, are most stable when highly substituted. Negatively charged carbon ions, or carbanions, are most stable when not substituted. This relationship is summarized below. Carbonium ions (+) Primary - Secondary - Tertiary Carbanions (-) Tertiary - Secondary - Primary The relationship between stability and the degree of substitution provides an explanation of the observed difference in residual carbon with polarity of the elsctric field.
  • the more highly substituted and branched fragments of the binder are more likely to be positively charged. These highly substituted fragments have the smallest diffusitivity due to their structure. Accordingly, when the electric field is applied with a polarity that will induce a force on these positively charged fragments to pull them out of the thick film, the greatest reduction in carbon content, is seen.
  • the length of time during which the thick film is heated in the electric field is also not critical.
  • the electric field is maintained around the thick film for a time sufficient to maximize the removal of carbon from the thick film.
  • Such time will depend on the temperature to which the thick film is heated while in the electric field. For example, it has been found that a time of one minute in an electric field of 4000 V/cm yields excellent results when the thick film is heated within that electric field to a temperature of about 600*C. Beneficial results would be seen by the use of shorter times.
  • the electric field could be maintained around the thick film throughout the entire firing process, which normally takes about 10 to about 60 minutes and reaches a temperature of up to about 900*C or more.
  • the electric field is created within the firing chamber by means of two or more electrodes which are connected to a voltage source. It is preferred that the voltage source be a direct voltage source. This creates an electric field with a single non-changing polarity which induces a steady force on either the carbonium ions or carbanions in a direction out of the film.
  • an alternatingvoltage source could be used in the practice of this invention.
  • An alternating voltage source would create an electric field having an alternating polarity. Such an electric field would not induce a steady force on either the carbanions or the carbonium ions. However, such an electric field could still disrupt and reduce or eliminate the boundary layer around the thick film and thereby enhance the removal of organics from the thick films by that mechanism.
  • the drawback to alternating voltage sources is that there is no steady force acting on either carbanions or carbonium ions pullingthemout ofthe thick film. Moreover, alternating voltage sources tend to induce current into the thick film circuit which is generally undesirable.
  • the present invention is applicable to both nitrogen and air-fireable thick films. It has been found however, that the presence of an electric field generally causes a greater increase in the rate and quantity of organic com- ponents removed from nitrogen-fireable thick films then from air-fireable thick films. While not being bound by theory, it is believed to stem from a difference in the mechanism of organic removal in an oxygen containing atmosphere versus a non-oxygen containing atmosphere. Air-fireable material benefit greatly from the presence and participation of oxygen in burnout, i.e., the initial stage in the firing process wherein the temporary organic binder is removed. It provides for a rapid combustion pathway that appears not to be diffusion-rate controlled. Burnout in nitrogen however, provides a different chemical and kinetic picture.
  • the temporary binders of nitrogen fireable thick films are high molecular weight polymers, e.g. acrylic, and must be removed prior to the development of physical film integrity.
  • the binder or other components of the film are designed to supply some oxygen to provide for partial combustion of the organic material. Nonetheless, decomposition remains the primary mechanism for binder removal.
  • Electron Spectroscopy for Chemical Analysis (ESCA) data has been collected that examines the binding energy of residual carbon in dielectric films fired both conventionally and in infrared equipment. Although bound carbon peaks were the same in both cases, the free carbon peak was substantially higher in the infrared-fired samples. This data indicated that thus, in contrast to air firing, burnout in nitrogen appears to be diffusion-rate controlled.
  • ESA Electron Spectroscopy for Chemical Analysis
  • FIG. 1 there is shown schematically an apparatus constructed in accordance with the present invention.
  • the apparatus comprises an infrared furnace 10 and a metal conveyor belt 11 for transporting thick film circuits to be fired through the furnace.
  • Infrared furnace 10 comprises a plurality of interconnected chambers including an entrance chamber 12, a heating or firing chamber 13, a cooling chamber 14 and an exit chamber 16.
  • Conveyor belt 11 is driven by a motor 17 having a speed control 18.
  • a temperature sensor 19 monitors the temperature in the firing chamber 13 of furnace 10. Responsive to temperature sensor 19, a temperature control circuit 21 adjusts the magnitude of the voltage applied to a plurality of infrared lamps in the firing chamber 13 of furnace ' 10 by a voltage source 22. Additional temperature control loops identical to temperature sensor 19, temperature control circuit 21, and voltage source 22 could be provided if desired for different zones in the firing chamber 13 of furnace 10 so as to establish the desired temperature profile for the thick film circuits on conveyor belt 11. in any case, the control loop 21 increases and decreases the energy radiated by the infrared lamps so as to maintain a constant temper ⁇ ature within the firing chamber or zone thereof, as the case may be.
  • An electric field control circuit 23 adjusts the magnitude of the voltage established between one or more first electrodes in the firing chamber 13 and the metal conveyor belt, which acts as a second electrode, by a second voltage source 24 and can be used to increase or decrease the strength of the electric field generated between the first electrodes and the conveyor belt. If more than one first electrode is utilized, separate electric field control circuits 23 and second voltage source 24 could be provided, if desired, to establish different electrical field strengths in different zones in the firing chamber 13.
  • the heating chamber 13 is generally rectangular in shape with upper and lower walls 26 and 27, a pair of side walls 28, and a pair of end walls 29.
  • Each end wall 29 comprises an upper insulation member 31 and a lower and insulation member 32 which are vertically spaced apart to provide a rectangular port or opening 33 through which the conveyor belt 11 passes.
  • the lower insulation member 32 is provided on its upper edge with three spaced semi-circular grooves 34.
  • the upper and lower and insulation members 31 and 32 of the end walls 29 are covered by upper and lower end sheet-metal covers 36 and 37.
  • the side walls 28 comprise an elongated, generally rectangular side insulation member 38 which is covered by a side sheet-metal cover 39.
  • the upper wall 26 also comprise an elongated, generally-rectangular upper insulation member _41 which is covered by an upper sheet-metal cover 42.
  • the upper sheet-metal cover 42 is spaced apart from the upper insulation member 41 by insulated upper spacers 43 to thereby form an upper plenum 44 between the upper sheet-metal cover 42 and the upper insulation member 41.
  • the lower wall 27 comprises an elongated, generally-rectangular lower insulation member 46 which is covered by a lower sheet-metal cover 47.
  • the lower sheet- metal cover 47 is spaced apart from the lower insulation member 46 by insulated lower spacers 48 to form a lower plenum 49 between the lower sheet-metal cover 47 and the lower insulation member 46.
  • the upper sheet-metal cover 42 comprises a side flange 51 which extends downwardly around periphery of the upper sheet-metal cover 42.
  • An upper bracket is provided on the side flange 51 of the upper sheet-metal cover 42.
  • the lower sheet-metal cover 47 also comprises a side flange 53 which extends upwardly around periphery of the lower sheet-metal cover 47 and comprises a lower bracket 54.
  • the side flange 51 of the upper sheet-metal cover 42 is drawn down over the side and upper end sheet-metal covers 39 and 36 and is held by tie rods 56 which pass through openings in the upper bracket 52 of the upper sheet-metal cover 42 and aligned openings in corresponding upper brackets 57 of the side and upper end sheet-metal covers 39 and 36.
  • the side flange 53 of the lower sheet-metal cover 47 is drawn up over the side and lower end sheet-metal covers 39 and 36 and is held by tie rods 58 which pass through openings in the lower bracket 54 of the lower sheet-metal cover 47 and aligned openings in a lower bracket 59 carried by the side and lower end sheet-metal covers 39 and 36.
  • the conveyor belt 11 is supported within the heating chamber 13 on three quartz tubes 61 which extend the length of the heating chamber 13 and rest on the three semi-circular grooves 34 provided on the lower insulation members 32 of the end walls 29.
  • a cover gas which may be air or nitrogen, for example, may be fed under a low pressure through upper and lower tubular connectors 62 and 63 mounted on the respective upper and lower sheet-metal covers 42 and 47.
  • the cover gas slowly and evenly filters through the porous upper and lower insulating members 41 and 46 which form each of the top and bottom walls of the heating chamber 13, thus causing the interior of the heating chamber 13 to be at a slightly higher pressure than the atmosphere surrounding the infrared furnace.
  • Each of the side walls 28 of the heating chamber 13 is provided with an upper series of spaced apart circular holes 64 above the conveyor belt 11 and a lower series of spaced circular holes 66 below the conveyor belt 11.
  • Each of the circular holes 64 and 66 extend through the side sheet-metal cover 39 and the side insulation member 38 forming each of the side walls 28.
  • the inner half portion of each the holes 64 and 66, and the side insulation member 38 is provided with a 45' chamfer 67.
  • a plurality of elongated infrared lamps 68 are mounted with their end portions passing through circular openings 64 or 66 and the opposing side walls 28.
  • the infrared lamps 68 may be mounted in any suitable manner such as that described in U.S. Patent No. 4,406,994 which is fully incorporated herein by reference.
  • Infrared lamps 68 are thus arranged side by side transverse to the direction of movement of conveyor belt 11 above and below conveyor belt 11.
  • Suitable infrared lamps may comprise a transparent or translucent elongated quartz tube in the center of which is located in electrically heated infrared ray emitting filament preferably made of tungsten.
  • the quartz tube is hermetically sealed at its ends.
  • the ends of the quartz tubes are provided with a metal terminal which connects to the respective ends of the tungsten filament. Leads are connected to each metal terminal.
  • Such infrared lamps are
  • the tubes generally being charged with an inert gas such as argon.
  • the energy emittedby such infrared lamps is concentrated in the near infrared band extending approximately from 0.7 microns to approximately 2.5 microns.
  • the exact distribution and the wave-length of the peak power vary as a function of the temperature of the lamp filament.
  • sufficient electrical voltage is applied to the lamp filament to maintain a filament temperature typically in the range of 1400* to 2000*K, depending upon the desired operating temperature and the quantity of heat that needs to be transferred to the thick films within the heating chamber 13.
  • the entrance portion 66 of the heating chamber 13 is separated from the remaining portion by a vertical wall 71 formed of upper and lower high temperature insulation sheet members 72 and 73 spaced to provide a central rectan ⁇ gular opening 74 for the traveling conveyor belt 11.
  • the series of upper and lower holes 64 and 66 in the side walls 28 are more closely spaced in the entrance portion
  • Infrared lamps 68 as previously described are mounted in the first, third, fourth, and sixth of the upper and lower holes 64 and 69.
  • a pair of upper electrodes 76 are mounted in the remaining two upper holes 66, i.e. the second and fifth holes.
  • the second and fifth lower holes of the entrance portion 69 of the heating chamber 13 are sealed by ceramic plugs 77.
  • the metal conveyor belt 11 forms a second or ground electrode.
  • the upper electrode 72 and the metal conveyor belt 11 are electrically connected to a voltage source (not shown) which can be adjusted to establish the desired potential difference between the upper electrode 72 and the metal conveyor belt 11, which is preferably maintained at ground potential. As best shown in FIG. 3, electrical contact is made between the voltage power source and the metal conveyor belt 11 by a metal brush 78 which continuously engages the conveyor belt 11 at a location outside of the heating chamber 13.
  • each upper electrode 76 comprises a metal wire 79 encapsulated in a quartz tube 81.
  • the wire 79 may be made of any metal which is stable at the operating temperatures of the furnace, i.e., up to about 1,000'C.
  • the thickness of the wire 79 is also not critical.
  • a presently preferred metal wire 74 is made of high-temperature stainless steel and has a diameter of about one millimeter.
  • the electrode wire 79 must be insulated to prevent arcing which may otherwise occur between the electrode wire 69 and conductive element at ground potential such as the side sheet-metal covers 39 of the sidewall 28, the metal conveyor belt 11, or even the thick film being processed if it contains any metallic particles.
  • the wall thickness of the quartz tube 81 must be sufficient to prevent such arcing.
  • the actual quartz tube thickness will therefore depend on the strength of the electric field being generated. For example, for an electric field having a strength of about 2000 V/cm and requiring an electrode potential of 15kV, a quartz tube having a wall thickness of about 5 millimeters is suitable. If the electric field strength is about 4000 V/cm and requires an electrode potential of 30,000 V, a quartz tube having a wall thickness of about 10 millimeters would be preferred.
  • the upper electrodes 76 are mounted in the upper holes 61 and in the side walls 28 by means of ceramic holders 82.
  • the upper electrodes 76 pass through openings in the ceramic holders 82.
  • the end of the electrode wire 79 protrudes from the quartz tube 81 and is connected to a generally cylindrical metal male terminal 83 which protrudes axially from the ends of the quartz tube 81.
  • the electrode wire 79 is connected to the voltage power supply by means of an insulated lead 84, which, in the embodiment shown is generally similar to a spark plug wire.
  • the lead 84 has an insulative rubber cap 86 which fits over the male terminal 83 and a portion of the end of the quartz tube 81 which protrudes from the sidewall 28.
  • a female connector 87 is provided which receives the male terminal 83 of the electrode 76.
  • the ceramic holder 82 has a hollow cylindrical body 88 with a shoulder 89 on its outer end and a bottom wall 91 on its inner end.
  • the bottom wall 91 is provided with a concentric circular opening 92.
  • the length of the body 88 of the ceramic holder 82 is approximately one-half the thickness of the side insulating member.
  • the ceramic holder 82 is positioned with its cylindrical body 88 having a relatively close fit in the circular hole 66 of the side wall 78 and with its shoulder 89 lying against the side sheet metal cover 39 and permanently sealed in position by use of a silicone sealant.
  • the closed end of the electrode 76 i.e. the end opposite the male terminal 83 is inserted into the ceramic holder 82 secured in hole 66 on one of the sidewalls 28.
  • the electrode 76 is then pushed, and rotated as needed, until it passes through the ceramic holder 82 in the opposing sidewall 28.
  • the chamber 67 on the inner portion of the hole 66 aids in guiding the electrode 76 into the opening of the opposing ceramic holder 82.
  • soluble refractory material such as sodium fluosilicate
  • the alumina gasket 93 Upon drying, the alumina gasket 93 is effectively bonded to the wall of the ceramic holder 82 and the wall of the quartz tube 81. This assures that the alumina gasket 93 does not work loose in the ceramic holder 82 as a result of the expansion and contraction of the sidewalls of the heating chamber 13 and that joint will remain gas-tight.
  • infrared lamps 68 heat the substrate and thick film, preferably to a temperature of at least about 350'C and typically to a temperature of about 600'C.
  • an electric field is established between the upper electrode 76 and the metal conveyor belt 11. As the substrate and the thick film pass through the entrance portion of the heating chamber 13, the temporary organic binder decomposes and .volatilizes.
  • the substrate and thick film After removal of the temporary organic binder, the substrate and thick film passes through the remainder of the heating chamber wherein the temperature of the thick film increases to about 900*C to cause the conductive or dielectric particles of the thick film to fuse together. The substrate then passes to the cooling and exit chambers.
  • any infrared furnace or, indeed, any conventional furnace may be used.
  • Particularly preferred furnaces to which the present invention is applicable are manufactured by Radiant Technology Corporation of Cerritos, California and sold as models CU300, CU600, L900 and L1200. While, infrared lamps are preferred, it is apparent that any type of heating element may be used.
  • the apparatus need not comprise a conveyor belt which runs through the heating chamber. Rather, a conventional furnace simply having a door and a stationary supporting means for holding the insulative substrate and thick film may be employed.
  • the size, shape, location and number of electrodes may vary as desired.
  • the upper electrode may be an insulated plate or screen.
  • Such shapes are not preferred for use in the described apparatus because they tend to restrict the flow of cover gas within the chamber. For other heating chamber designs, such shapes may .be preferred.
  • the lower electrode be the metal conveyor belt
  • electrodes similar to the described upper electrodes or electrodes of another shape and design, e.g., a plate or screen, may be used, as desired.
  • quartz is the preferred insulation material around the upper electrode because of its high thermal shock resistance, any suitable insulative material may be used.
  • the lower electrode need not be at ground potential. However, if at a potential other than ground potential, the lower electrode should be encapsulated in an insulative material.
  • An infrared furnace was modified to generate an electric field in the entrance portion of the heating chamber.
  • the infrared furnace employed was a Model Cu-610 furnace manufactured by Radiant Technology Corporation of Cerritos, California. Within the entrance portion of the infrared furnace, the second and fifth upper and lower infrared lamps were disconnected and replaced with four electrodes.
  • Each electrode consisted of a 1mm stainless steel wire surrounded by an 11mm diameter quartz tube. The ends of the electrode protruded out of the heating chamber. At one end, the quartz tube completely surrounded the end of the electrode wire. At the other end, the electrode wire protruded from the quartz tube and was connected to a cylindrical male connector having a length of about 1cm and a diameter of about 5mm.
  • a spark plug wire was connected to the male connector of each electrode, the fibber cap of the spark plug wire fitting over the end of the quartz tube.
  • the spark plug wires were connected to a direct voltage source, specifically a 0-3OkV DC power supply. The configuration implemented had sufficient electrical integrity to generate a field of 700 V/cm.
  • Nitrogen-fireable dielectric DuPont 4575
  • the material was fired in a pure nitrogen atmosphere ( ⁇ 10 ppm O2) ambient at a speed of 15 ipm. These conditions gave a 12 minute overall cycle with approximately 2.5 minutes at 900*C.
  • Residual carbon concentrations were measured by milling 200A below the surface of the dielectric with Ar + ions and using small spot ESCA analysis to determine atomic concentrations. The results are summarized below:

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Sustainable Development (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Textile Engineering (AREA)
  • Furnace Details (AREA)

Abstract

Un procédé et un appareil sont utilisés pour éliminer rapidement des composants organiques contenus dans des pellicules. L'appareil comprend une chambre de chauffage (13) ayant un ou plusieurs corps chauffants (68). Une paire d'électrodes espacées (76, 11) établissent un champ électrique dans la chambre de chauffage. Le procédé comprend le chauffage de la pellicule en présence du champ électrique jusqu'à une température suffisante pour provoquer l'élimination des composants organiques contenus dans la pellicule.
EP19870900393 1985-11-13 1986-11-12 Procede et appareil pour l'elimination rapide de materiaux organiques contenus dans des pellicules par chauffage dans un champ electrique. Withdrawn EP0245500A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US79762985A 1985-11-13 1985-11-13
US797629 1985-11-13

Publications (2)

Publication Number Publication Date
EP0245500A1 true EP0245500A1 (fr) 1987-11-19
EP0245500A4 EP0245500A4 (fr) 1988-03-21

Family

ID=25171373

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870900393 Withdrawn EP0245500A4 (fr) 1985-11-13 1986-11-12 Procede et appareil pour l'elimination rapide de materiaux organiques contenus dans des pellicules par chauffage dans un champ electrique.

Country Status (3)

Country Link
EP (1) EP0245500A4 (fr)
JP (1) JPS62503136A (fr)
WO (1) WO1987003077A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2653866A1 (fr) * 1989-10-31 1991-05-03 France Rayonnement Procede pour la gestion des conditions de fonctionnement d'un secheur ultra-violet.
US6495800B2 (en) 1999-08-23 2002-12-17 Carson T. Richert Continuous-conduction wafer bump reflow system
WO2001014811A1 (fr) 1999-08-23 2001-03-01 Radiant Technology Corporation Systeme de refusion pour bossages de tranche a conduction continue
US8865058B2 (en) 2010-04-14 2014-10-21 Consolidated Nuclear Security, LLC Heat treatment furnace
DE102013105959B4 (de) * 2013-06-07 2019-06-19 Heraeus Noblelight Gmbh Betriebsverfahren und Vorrichtung zur Bestrahlung eines Substrats
EP3327395A1 (fr) * 2016-11-29 2018-05-30 Valmet Technologies Oy Dispositif de rayonnement pour traiter un voile et/ou éliminer des bulles d'un revêtement d'un voile et procédé de traitement d'un voile et/ou éliminer des bulles d'un revêtement d'un voile par rayonnement

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2405249A (en) * 1943-11-13 1946-08-06 Fred K H Levey Co Inc Method of applying coating films
GB617968A (en) * 1944-11-29 1949-02-15 Hoe & Co R Improvements in the drying of printed matter by dielectric heating
DE1903005A1 (de) * 1969-01-22 1970-08-06 Siemens Ag Vorrichtung zum kapazitiven Erwaermen zu trocknender zylindrischer oder prismatischer Koerper,z.B.Spinnkuchen
EP0036632A2 (fr) * 1980-03-21 1981-09-30 The Mead Corporation Dispositif de séchage
EP0061158A1 (fr) * 1981-03-23 1982-09-29 Radiant Technology Corporation Procédé de cuisson de circuits électroniques à couches épaisses
EP0108314A2 (fr) * 1982-11-03 1984-05-16 Radiant Technology Corporation Procédé de fabrication de circuits à couches minces multicouches

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS516999Y1 (fr) * 1969-03-05 1976-02-25
US3931446A (en) * 1970-09-26 1976-01-06 Kureha Kagaku Kogyo Kabushiki Kaisha Process for producing polymeric piezoelectric elements and the article formed thereby
US3725114A (en) * 1971-05-28 1973-04-03 Sherwin Williams Co Curing photopolymerizable film-forming polymer coatings
US4155735A (en) * 1977-11-30 1979-05-22 Ppg Industries, Inc. Electromigration method for making stained glass photomasks
US4262665A (en) * 1979-06-27 1981-04-21 Roalstad W L Intramedullary compression device
NL8001944A (nl) * 1980-04-02 1981-11-02 Vries Jacob De Inrichting voor het verwarmen van een vel- of baanvormig materiaal.
US4404754A (en) * 1981-05-08 1983-09-20 Candor James T Electrostatic method for treating material
JPS5972104A (ja) * 1982-10-19 1984-04-24 Toshiba Corp 磁性体粉末

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2405249A (en) * 1943-11-13 1946-08-06 Fred K H Levey Co Inc Method of applying coating films
GB617968A (en) * 1944-11-29 1949-02-15 Hoe & Co R Improvements in the drying of printed matter by dielectric heating
DE1903005A1 (de) * 1969-01-22 1970-08-06 Siemens Ag Vorrichtung zum kapazitiven Erwaermen zu trocknender zylindrischer oder prismatischer Koerper,z.B.Spinnkuchen
EP0036632A2 (fr) * 1980-03-21 1981-09-30 The Mead Corporation Dispositif de séchage
EP0061158A1 (fr) * 1981-03-23 1982-09-29 Radiant Technology Corporation Procédé de cuisson de circuits électroniques à couches épaisses
EP0108314A2 (fr) * 1982-11-03 1984-05-16 Radiant Technology Corporation Procédé de fabrication de circuits à couches minces multicouches

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8703077A1 *

Also Published As

Publication number Publication date
JPS62503136A (ja) 1987-12-10
EP0245500A4 (fr) 1988-03-21
WO1987003077A1 (fr) 1987-05-21

Similar Documents

Publication Publication Date Title
EP1464629B1 (fr) Procédé de fabrication d'un creuset de silice très pure par affinage électrolytique
US3983385A (en) Method and apparatus for operating a mercury vapor lamp
US4902870A (en) Apparatus and method for transfer arc cleaning of a substrate in an RF plasma system
KR100393277B1 (ko) 전자원, 화상표시디바이스의 제조장치와 방법, 및기판처리 장치와 방법
EP0245500A1 (fr) Procede et appareil pour l'elimination rapide de materiaux organiques contenus dans des pellicules par chauffage dans un champ electrique
US5272414A (en) Discharge element, method of producing the same and apparatus comprising the same
US2219614A (en) Electrical discharge apparatus
US4548670A (en) Silicon melting and evaporation method for high purity applications
JPS60112671A (ja) 反応性環境に直接さらされるに適した安定な導電性要素
US2635994A (en) Production of carbon resistors
EP0768389A1 (fr) Article en nitrure de bore pyrolytique et son procédé de fabrication
AU7681581A (en) Arc furnace electrode
EP0061158B1 (fr) Procédé de cuisson de circuits électroniques à couches épaisses
EP0108314A2 (fr) Procédé de fabrication de circuits à couches minces multicouches
US3962670A (en) Heatable hollow semiconductor
US3373240A (en) Method of operating an electric arc furnace
US4853941A (en) D.C. arc furnace having electrically conductive hearth and method for making same
US4569307A (en) Silicon melting and evaporation apparatus for high purity applications
US3970768A (en) Grid electrodes
US9255325B2 (en) Method and apparatus for igniting silicon rods outside a CVD-reactor
US1637167A (en) Electrical heating body for high temperatures especially for ceramic metallurgical processes and chemical processes
NL8101750A (nl) Kathode voor elektronenbuizen.
US3183293A (en) Electric furnace
US901294A (en) Apparatus for electric lighting.
JPS57136747A (en) Fluorescent display tube

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE FR GB IT LI LU NL SE

17P Request for examination filed

Effective date: 19871029

A4 Supplementary search report drawn up and despatched

Effective date: 19880321

17Q First examination report despatched

Effective date: 19891109

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19900320

RIN1 Information on inventor provided before grant (corrected)

Inventor name: FLATTERY, DAVID, K.