EP0180010A2 - Processing materials in furnaces - Google Patents

Processing materials in furnaces Download PDF

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Publication number
EP0180010A2
EP0180010A2 EP85111305A EP85111305A EP0180010A2 EP 0180010 A2 EP0180010 A2 EP 0180010A2 EP 85111305 A EP85111305 A EP 85111305A EP 85111305 A EP85111305 A EP 85111305A EP 0180010 A2 EP0180010 A2 EP 0180010A2
Authority
EP
European Patent Office
Prior art keywords
oxygen
metal
furnace
catalyst
work material
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Withdrawn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
EP85111305A
Other languages
German (de)
French (fr)
Other versions
EP0180010A3 (en
Inventor
Robert Donald Macinnes
Robert Lewis Rohr
Helen Li Yeh
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.)
International Business Machines Corp
Original Assignee
International Business Machines 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 International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0180010A2 publication Critical patent/EP0180010A2/en
Publication of EP0180010A3 publication Critical patent/EP0180010A3/en
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0006—Details, accessories not peculiar to any of the following furnaces
    • C21D9/0025—Supports; Baskets; Containers; Covers
    • 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
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • 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
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace
    • F27B9/26—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace on or in trucks, sleds, or containers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D5/00—Supports, screens, or the like for the charge within the furnace
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/003—Linings or walls comprising porous bricks
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D5/00—Supports, screens, or the like for the charge within the furnace
    • F27D5/0068—Containers

Definitions

  • the present invention relates to processing materials in furnaces, and more particularly to a technique for processing materials in a furnace wherein additional material is included to reduce the oxygen in the furnace atmosphere.
  • Japanese Patent J5 1094-407 describes enclosing aluminum to be sintered in an atmosphere of nitrogen gas in a tray having cover which fits into a groove in the tray. In the groove is deposited magnesium powder through which the atmosphere around the aluminum powder communicates with the atmosphere outside the tray.
  • U.S. Patent 3,232,754 issued Feb. 1, 1966 to Storcheim and entitled POROUS METALLIC BODIES AND FABRICATION METHODS THEREFORE teaches a furnace in which parts are sintered, and through which hydrogen gas is circulated. Further, the metal being sintered is contained in a boat provided with a removable cover. Locating pins projecting from the cover which are receivable in correspondingly positioned apertures in the side walls of the boat iie hold the cover in place.
  • the boat is divided by a partition wall into a main section for accommodating green compact bearings to be sintered, and an auxiliary section filled with aluminum powder acting as a getter to pick up oxygen and moisture.
  • Heavy iron boats are used to contain the powder to be sintered and the boats must be heavy to deal with temperature gradients in the furnace.
  • the covered boat is not sealed from the hydrogen, but free circulation and turbulence of the gas within the boat is inhibited.
  • the work material in the furnace is surrounded by a hydrogen gas atmosphere and metal surfaces which convert oxygen in the hydrogen gas into water.
  • the prior art does not teach the technique of surrounding a material with a catalyst or gettering material to use up oxygen before it reaches the work material.
  • An object of the present invention is to provide a process control for a furnace wherein workpiece material is surrounded by an enclosure composed of catalytic material.
  • Another object of the present invention is to provide an enclosure for workpiece material in a furnace where the enclosure is a porous structure of catalytic metal for converting oxygen into water.
  • a still further object of the present invention is to provide an enclosure for a workpiece in a furnace for converting oxygen in the furnace atmosphere into water, wherein the enclosure is composed of a porous structure of platinum material.
  • the invention provides a receptacle for containing work material adapted to be located in a heating furnace having a percentage of oxygen in a reducing gas atmosphere
  • a receptacle for containing work material adapted to be located in a heating furnace having a percentage of oxygen in a reducing gas atmosphere
  • a tray structure for supporting said work material in said furnace, and an enclosure structure surrounding said work material in said tray structure, said enclosure structure being connected to said tray and being of a mesh or screen configuration to allow said reducing gas to pass through and contact said work material, said enclosure structure comprising or being composed of a catalyst material to react with said oxygen in said reducing gas to convert said oxygen into another compound to prevent said oxygen from combining with said work material.
  • FIG. 1 The structure of FIG. 1 is based on the principle of surrounding the work with metal surfaces which will convert oxygen in the hydrogen gas atmosphere passing through the furnace into water.
  • the work is surrounded with a catalyst or a gettering material to tie up the oxygen before it ever reaches the work.
  • the furnaces mentioned above include conveyor furnaces which are used in many processors such as Ni/Au diffusion, chip reflow, chip joining, pin brazing, seal band pretinning and cap sealing, etc.
  • processors such as Ni/Au diffusion, chip reflow, chip joining, pin brazing, seal band pretinning and cap sealing, etc.
  • chemical flux or high temperatures with a reducing atmosphere in processing parts.
  • Dry processes without the use of chemical flux have advantages such as eliminating cleaning steps, and eliminating flux caused defects, and corrosion, etc.
  • Reducing atmosphere such as hydrogen or hydrogen enriched gas is usually used in dry processes. However, in most of the dry bonding processes, the oxygen content has to be controlled to less than 1 ppm (part per million).
  • the process temperature for a successful heat treatment or bonding has to be significantly higher and such higher processing temperature may jeopardized the quality of the parts to be bonded or treated.
  • low oxygen content level must be maintained for accomplishing high quality bonds and heat treatment.
  • FIG. 1 a structure is shown for achieving the important but frequently unreachable low oxygen content in high through-put conveyor furnaces.
  • the structured FIG. 1 enables the provision of a high quality (low oxygen level) atmosphere surrounding a workpiece as it is processed in the reducing atmosphere of the furnace.
  • the structure of FIG..1 is a container which encloses the workpiece and functions as a catalyst for the reaction of H2 and 02 in an H2 containing atmosphere, i.e., H2 and forming gas, etc.
  • the structure of the enclosure or container includes a bottom tray or boat 10 which is coated with a metal such as platinum and a top or cover made from metal screening or metal coated screening which metal may also be platinum.
  • bottom tray 10 may also be composed of mesh or screening material as an alternative to being solid.
  • Platinum is a preferred embodiment for the metal boat 10 and screen 12 because it is an excellent catalyst for the reaction of 02 and H2 and is active at temperatures at least as low as 150°C.
  • One or more workpieces 14 are disposed in boat 10 so they are surrounded by the catalyst metal. The catalyst reaction depends upon gas contact with the surface, screening offers a large surface area which enhances this contact while still allowing the furnace gases to flow and convectively heat the part.
  • FIG. 2 illustrates a cross section of a typical hydrogen reflow furnace through which workpieces are conveyed by a belt.
  • Other examples of types of furnaces with which the present invention may be used are shown in the aforementioned U.S. Patents 3,232,754 and 4,113,240.
  • the enclosure for workpieces in a furnace that functions to reduce the oxygen in the furnace gas by converting the oxygen into water by catalytic action.
  • the reducing atmosphere in the furnace may include not only hydrogen containing gas, but also other types of reducing gases such as CO to convert the oxygen to C0 2 .
  • the described enclosure may be employed in any heating applications that need reducing atmosphere and require low oxygen level, and that the enclosure may be composed of other, different kinds of catalyst material, with platinum being only one example.

Abstract

A structure is shown for achieving low oxygen content high quality atmosphere surrounding a workpiece as it is processed in the reducing atmosphere of a furnace. The structure is a container which encloses the workpiece and functions as a catalyst for the reaction of H2 and 02 in an H2 containing atmosphere, i.e., H2 and forming gas, etc.
The structure of the enclosure or container includes a bottom tray or boat 10 which is coated with a metal such as platinum and a top or cover 12 made from metal screening or metal coated screening which metal may also be platinum. The bottom tray may also be composed of mesh or screening material as an alternative to being solid. Platinum is a preferred embodiment for the metal boat and screen because it is an excellent catalyst for the reaction of 02 and H2 and is active at temperatures at least as low as 150°C. One or more workpieces may be disposed in the boat so they are surrounded by the catalyst metal. The catalyst reaction depends upon gas contact with the surface, and the screening offers a large surface area which enhances this contact while still allowing the furnace gases to flow and convectively heat the workpiece.

Description

    PROCESSING MATERIALS IN FURNACES
  • The present invention relates to processing materials in furnaces, and more particularly to a technique for processing materials in a furnace wherein additional material is included to reduce the oxygen in the furnace atmosphere.
  • Japanese Patent J5 1094-407 describes enclosing aluminum to be sintered in an atmosphere of nitrogen gas in a tray having cover which fits into a groove in the tray. In the groove is deposited magnesium powder through which the atmosphere around the aluminum powder communicates with the atmosphere outside the tray.
  • U.S. Patent 3,232,754 issued Feb. 1, 1966 to Storcheim and entitled POROUS METALLIC BODIES AND FABRICATION METHODS THEREFORE teaches a furnace in which parts are sintered, and through which hydrogen gas is circulated. Further, the metal being sintered is contained in a boat provided with a removable cover. Locating pins projecting from the cover which are receivable in correspondingly positioned apertures in the side walls of the boat iie hold the cover in place. The boat is divided by a partition wall into a main section for accommodating green compact bearings to be sintered, and an auxiliary section filled with aluminum powder acting as a getter to pick up oxygen and moisture. Heavy iron boats are used to contain the powder to be sintered and the boats must be heavy to deal with temperature gradients in the furnace. The covered boat is not sealed from the hydrogen, but free circulation and turbulence of the gas within the boat is inhibited.
  • U.S. Patent 4,113,240 issued Sept. 12, 1978 to G. P. Klein, entitled CONTINUOUS OPEN-ENDED SINTERING FURNACE SYSTEM describes another example of a furnace system wherein the amount of oxygen and impurities in general are decreased but which provides no catalytic conversion of the oxygen.
  • In the present invention the work material in the furnace is surrounded by a hydrogen gas atmosphere and metal surfaces which convert oxygen in the hydrogen gas into water. The prior art does not teach the technique of surrounding a material with a catalyst or gettering material to use up oxygen before it reaches the work material.
    • SUMMARY OF THE INVENTION
  • An object of the present invention is to provide a process control for a furnace wherein workpiece material is surrounded by an enclosure composed of catalytic material.
  • Another object of the present invention is to provide an enclosure for workpiece material in a furnace where the enclosure is a porous structure of catalytic metal for converting oxygen into water.
  • A still further object of the present invention is to provide an enclosure for a workpiece in a furnace for converting oxygen in the furnace atmosphere into water, wherein the enclosure is composed of a porous structure of platinum material.
  • Accordingly, the invention provides a receptacle for containing work material adapted to be located in a heating furnace having a percentage of oxygen in a reducing gas atmosphere comprising: a tray structure for supporting said work material in said furnace, and an enclosure structure surrounding said work material in said tray structure, said enclosure structure being connected to said tray and being of a mesh or screen configuration to allow said reducing gas to pass through and contact said work material, said enclosure structure comprising or being composed of a catalyst material to react with said oxygen in said reducing gas to convert said oxygen into another compound to prevent said oxygen from combining with said work material.
  • The invention will now be more fully described with reference to the accompanying drawings, in which:-
    • FIG. 1 is an illustration of an enclosure for workpiece material to be heated in a furnace which functions as a catalyst according to the principles of the present invention.
    • FIG. 2 is a schematic illustration of a typical conveyor belt type reflow furnace in which the enclosure of the present invention may be used.
  • The structure of FIG. 1 is based on the principle of surrounding the work with metal surfaces which will convert oxygen in the hydrogen gas atmosphere passing through the furnace into water. Thus, the work is surrounded with a catalyst or a gettering material to tie up the oxygen before it ever reaches the work.
  • The furnaces mentioned above include conveyor furnaces which are used in many processors such as Ni/Au diffusion, chip reflow, chip joining, pin brazing, seal band pretinning and cap sealing, etc. In processes sensitive to oxidation, it is often necessary to use chemical flux or high temperatures with a reducing atmosphere in processing parts. Dry processes without the use of chemical flux have advantages such as eliminating cleaning steps, and eliminating flux caused defects, and corrosion, etc. Reducing atmosphere such as hydrogen or hydrogen enriched gas is usually used in dry processes. However, in most of the dry bonding processes, the oxygen content has to be controlled to less than 1 ppm (part per million). If the oxygen content is not controlled to less than 1 ppm, the process temperature for a successful heat treatment or bonding has to be significantly higher and such higher processing temperature may jeopardized the quality of the parts to be bonded or treated. Thus, low oxygen content level must be maintained for accomplishing high quality bonds and heat treatment.
  • In a well sealed furnace with pure incoming gases, most of the contamination comes through the gas curtains in the ends of the furnace as a result of disturbances caused by parts entering and leaving the furnace. Difficulties in maintaining the proper oxygen level in the reducing atmosphere belt furnaces have been encountered in areas such as chip reflow, chip joining, and pin brazing areas. The oxygen level of a conveyor furnace containing reducing atmosphere usually depends on the opening of the furnace. Typical oxygen levels of a conveyor furnace are in the range of 4 to 7 ppm.
  • In FIG. 1, a structure is shown for achieving the important but frequently unreachable low oxygen content in high through-put conveyor furnaces. The structured FIG. 1 enables the provision of a high quality (low oxygen level) atmosphere surrounding a workpiece as it is processed in the reducing atmosphere of the furnace. The structure of FIG..1 is a container which encloses the workpiece and functions as a catalyst for the reaction of H2 and 02 in an H2 containing atmosphere, i.e., H2 and forming gas, etc.
  • In FIG. 1, the structure of the enclosure or container includes a bottom tray or boat 10 which is coated with a metal such as platinum and a top or cover made from metal screening or metal coated screening which metal may also be platinum. As indicated in FIG. 1, bottom tray 10 may also be composed of mesh or screening material as an alternative to being solid. Platinum is a preferred embodiment for the metal boat 10 and screen 12 because it is an excellent catalyst for the reaction of 02 and H2 and is active at temperatures at least as low as 150°C. One or more workpieces 14 are disposed in boat 10 so they are surrounded by the catalyst metal. The catalyst reaction depends upon gas contact with the surface, screening offers a large surface area which enhances this contact while still allowing the furnace gases to flow and convectively heat the part.
  • The enclosure or container of FIG. 1, as previously stated, is used in a furnace for the purposes of diffusion, chip reflow, chip oxidation, et al. The state of the art furnace depends on the particular process, however, as an example, FIG. 2 illustrates a cross section of a typical hydrogen reflow furnace through which workpieces are conveyed by a belt. Other examples of types of furnaces with which the present invention may be used are shown in the aforementioned U.S. Patents 3,232,754 and 4,113,240.
  • What has been described is an enclosure for workpieces in a furnace that functions to reduce the oxygen in the furnace gas by converting the oxygen into water by catalytic action. Although, a specific configuration and selection of material was shown in the embodiment of FIG. 1, the specific appearance and design of the invention may be varied for different applications. Also, the reducing atmosphere in the furnace may include not only hydrogen containing gas, but also other types of reducing gases such as CO to convert the oxygen to C02. It will also be appreciated by those skilled in the art that the described enclosure may be employed in any heating applications that need reducing atmosphere and require low oxygen level, and that the enclosure may be composed of other, different kinds of catalyst material, with platinum being only one example.

Claims (6)

1. A receptacle for containing work material adapted to be located in a heating furnace having a percentage of oxygen in a reducing gas atmosphere comprising:
a tray structure for supporting said work material in said furnace, and
an enclosure structure surrounding said work material in said tray structure, said enclosure structure being connected to said tray and being of a mesh or screen configuration to allow said reducing gas to pass through and contact said work material,
said enclosure structure comprising or being composed of a catalyst material to react with said oxygen in said reducing gas to convert said oxygen into another compound to prevent said oxygen from combining with said work material.
2. A receptacle for containing work material according to Claim 1 wherein said reducing gas is hydrogen and said enclosure structure is composed of a catalyst material which reacts with said oxygen in said hydrogen atmosphere to convert said oxygen into water.
3. A receptacle for containing work material according to Claim 1 wherein said reducing gas is carbon monoxide atmosphere and said enclosure structure is composed of a catalyst material which reacts with said oxygen in said carbon monoxide atmosphere to convert said oxygen to carbon dioxide.
4. A receptacle for containing work material according to Claim 2 wherein the external surface of said enclosure structure is composed of platinum.
5. A receptacle for containing work material according to Claim 4 wherein the external surface of said tray structure is composed of platinum.
6. A receptacle for containing work material according to Claim 5 wherein said tray structure is of a mesh or screen configuration.
EP85111305A 1984-10-26 1985-09-06 Processing materials in furnaces Withdrawn EP0180010A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US66540484A 1984-10-26 1984-10-26
US665404 1984-10-26

Publications (2)

Publication Number Publication Date
EP0180010A2 true EP0180010A2 (en) 1986-05-07
EP0180010A3 EP0180010A3 (en) 1988-08-10

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EP85111305A Withdrawn EP0180010A3 (en) 1984-10-26 1985-09-06 Processing materials in furnaces

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EP (1) EP0180010A3 (en)
JP (1) JPS61107091A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2728270A1 (en) * 1994-12-20 1996-06-21 Commissariat Energie Atomique HYBRIDIZED OVEN FOR COMPONENT INTERCONNECTION BY FUSE MATERIAL
WO2004094057A1 (en) * 2003-04-23 2004-11-04 Volvo Aero Corporation Method and device for inhibiting contamination of a workpiece

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH087656Y2 (en) * 1989-08-15 1996-03-04 千住金属工業株式会社 Reflow furnace
SE526447C2 (en) * 2003-04-23 2005-09-20 Volvo Aero Corp Inhibiting contamination of workpiece used in aviation industry involves flushing/filling protective gas in container having workpiece and evacuating oven to reduce partial pressure for contaminant in container before workpiece is heated

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR40714E (en) * 1931-09-08 1932-08-22 Krupp Ag Thin sheet body, especially high-value material, such as stainless steel or refractory
US2131505A (en) * 1938-08-16 1938-09-27 Henry M Garsson Treating steel
US3232754A (en) * 1961-11-07 1966-02-01 Alloys Res & Mfg Corp Porous metallic bodies and fabrication methods therefor
DE1808236A1 (en) * 1967-11-11 1969-07-10 Nippon Kokan Kk Radiant heating furnace with regulation of the atmosphere
US4113240A (en) * 1976-01-16 1978-09-12 P. R. Mallory & Co. Inc. Continuous open-ended sintering furnace system
US4294436A (en) * 1979-09-05 1981-10-13 Kanto Yakin Kogyo Kabushiki Kaisha Furnace with protective atmosphere for heating metals

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR40714E (en) * 1931-09-08 1932-08-22 Krupp Ag Thin sheet body, especially high-value material, such as stainless steel or refractory
US2131505A (en) * 1938-08-16 1938-09-27 Henry M Garsson Treating steel
US3232754A (en) * 1961-11-07 1966-02-01 Alloys Res & Mfg Corp Porous metallic bodies and fabrication methods therefor
DE1808236A1 (en) * 1967-11-11 1969-07-10 Nippon Kokan Kk Radiant heating furnace with regulation of the atmosphere
US4113240A (en) * 1976-01-16 1978-09-12 P. R. Mallory & Co. Inc. Continuous open-ended sintering furnace system
US4294436A (en) * 1979-09-05 1981-10-13 Kanto Yakin Kogyo Kabushiki Kaisha Furnace with protective atmosphere for heating metals

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2728270A1 (en) * 1994-12-20 1996-06-21 Commissariat Energie Atomique HYBRIDIZED OVEN FOR COMPONENT INTERCONNECTION BY FUSE MATERIAL
EP0718067A1 (en) * 1994-12-20 1996-06-26 Commissariat A L'energie Atomique Hybridization oven for interconnection of components using a fusible material
WO2004094057A1 (en) * 2003-04-23 2004-11-04 Volvo Aero Corporation Method and device for inhibiting contamination of a workpiece

Also Published As

Publication number Publication date
JPS61107091A (en) 1986-05-24
EP0180010A3 (en) 1988-08-10

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