Abstract: A reflow soldering apparatus comprises a preheating chamber and a reflow chamber, both of which are furnished with a plurality of means for circulating a hot gas being composed of a cross flow blower, a divergent nozzle, a heater, a temperature sensor, a temperature controller, and a power regulator etc. The cross-flow blowers above a conveyer are arranged in a back to back manner and the blowers beneath the conveyer are arranged in a face to face manner, and soldering is performed by impinging the hot gas upon a circuit substrate being transferred by the conveyer.A reflow soldering apparatus having a small temperature fluctuation in the preheating chamber and the reflow chamber, high reliability in the soldering by maintaining a desired temperature profile, and preferable economy is provided.

Abstract: A soldering apparatus is disclosed which includes a longitudinally extending, air-tight housing having four contiguous, first through fourth zones and and inlet and outlet openings at both longitudinal ends thereof, a conveyer for conveying an article to be soldered along a predetermined path extending through the inlet opening, the first to fourth zones and the outlet opening, a soldering device provided in the second zone for applying a molten solder to the article traveling through the second zone, a plurality of upper and lower partition plates disposed in each of the first, third and fourth zones to partition each zone into a plurality of open ended chambers, an inert gas diffuser provided within at least one of the chambers of the third zone, and an air diffuser provided within at least one of the chambers of the fourth zone, so that the diffusion of air from the fourth zone to the third zone is substantially prevented while the diffusion of the inert gas from the third zone to the outlet opening throug

Abstract: An automatic soldering apparatus for soldering a printed circuit board having a plurality of electronic parts mounted thereon to be soldered while it is transported through a heating chamber having an inert gas fill therein is provided. The apparatus has a first station provided with a first opening for receiving the printed circuit board into the heating chamber and a second station provided with a second opening for removing the soldered printed circuit board from the heating chamber. Further, the apparatus has a supply of an inert gas and nozzles provided in the first and second stations. The inert gas is jetted through the nozzles toward the first and second openings, when required, so as to prevent outside air from flowing into the heating chamber.

Abstract: A radiation-shielding storage/transport container has a cast-iron vessel having an open end defining an end face, a steel ring engaging the end face and forming at least one annular seat, a weld unitarily bonding the ring to the end face, and a cover secured to the steel ring in the seat thereof. The cast-iron vessel is formed at its open end with an annular seat having a shoulder surface forming the end face. The weld is an aluminothermic weld that extends over the entire surface of the interface between the ring and the vessel. The ring is formed with two such seats and the cover includes an inner plug cover and an outer cover each in a respective one of the seats. The outer cover is of steel and a second peripheral weld connects the outer cover to the respective seat.

Abstract: A braze furnace of the inert gas type cooperatively uses the waste heat from the cooling chamber to vaporize liquid inert gas, while using the coolness of the inert gas being vaporized to accelerate the cooling process itself. The walls of the cooling chamber provide a hollow plenum into which stored liquified inert gas is metered and vaporized. From the plenum, vaporized gas is routed wherever needed to purge oxygen from the system. In addition, liquid gas can be injected directly into the cooling chamber for even quicker, direct part cooling and the purge the cooling chamber.

Abstract: Disclosed is a solder tool for reworking a pin-in-hole printed circuit board. The solder tool has means for providing a gas blanket. Also disclosed is a method of reworking a pin-in-hole printed circuit board using the solder tool.

Abstract: A gas flow distribution system for a solder dispensing head includes a base member adapted to be connected to the solder dispensing head and a structure connected to a source of an inert gas for distributing at least one continuous stream of the inert gas radially and axially below the solder dispensing head to exclude oxygen in the surrounding air therefrom.

Abstract: A method for bonding a solder wire is provided wherein a lower ball end of a material solder wire is first bonded to a first bonding portion of a workpiece. Then, the material solder wire is thermally cut to provide a solder wire segment held bonded to the first bonding portion and having an upper ball end. Finally, the upper ball end is bonded to a second bonding portion of the workpiece. All of the wire bonding process steps are performed in an oxygen-free atmosphere to prevent oxidation of the solder wire.

Abstract: A cover plate extends over at least part of a solder reservoir and has a slot for a solder wave to extend up above the cover plate. Shield gas is supplied under the cover plate to blanket the solder wave and prevent air from contacting the solder wave and circuit boards passing through the solder wave. Circuit boards are generally supported by conveyor fingers at side edges and the fingers pass through the solder wave. End shrouds are provided at both ends of the solder wave to prevent the entry of air through the conveyor fingers and to ensure that the side edges of the circuit board are uniformly blanketed by shield gas directed to the side edges passing up through the slot in the cover plate. The under surface, front edge, back edge and side edges of a circuit board are therefore uniformly blanketed by shield gas as the board passes through a solder wave.

Abstract: A bonding machine with an oxidation preventive assembly that is made up of two pipes installed on the bonding stage. The two pipes are formed with gas discharge holes and their terminal ends are closed by a block to prevent a back-flow of the gas supplied into the pipes. Thus, a uniform gas atmosphere is created around the workpiece which is placed on the bonding stage, preventing oxidation of the workpiece.

Abstract: The present invention relates to processes and apparatus for welding or joining metal parts which comprise moving a welding torch in a direction along a joint between said parts, causing a molten pool of metal with said welding torch along the joint and directing a laminar flow of inert fluid toward a freshly welded area behind said welding torch in the form of a trailing shield whereby the freshly welded area is protected from the surrounding air during its solidification. The laminar flow or inert fluid may also be directed along the joint ahead of the welding torch in the form of a leading shield such that turbulence in and around the joint caused by a high welding speed is reduced, thereby preventing oxygen entrainment in said molten pool of metal. The laminar flow of inert fluid is usually provided through at least one diffuser having at least one porous diffusing surface which is generally provided with a screen and/or a spatter shield.

Abstract: A bonding apparatus comprises a base (16) for supporting a printed circuit board (7), an atmosphere cover (1) which has a concavity (1c) covering a semiconductor device (5) mounted on the printed circuit board (7) and which is formed of laser light transmitting material, driving means (1j) for moving the atmosphere cover (1) upwards and downwards related to the base (16), pressing means (2) and (3) provided in the atmosphere cover (1) for pressing the semiconductor device (5) toward the printed circuit board (7), and laser heating means (9) for bonding a lead terminal (6) of the semiconductor device (5) with a junction (7a) of the printed circuit board (7).

Abstract: A cover plate or shroud extends over a solder reservoir and has a slot for a solder wave to extend up above the cover plate. A reduced oxygen atmosphere is supplied from gas outlets under the cover plate on both sides of the solder wave. Furthermore a gas knife is located to direct a stream of gas on an element such as a circuit board as it passes through the solder wave. The cover plate or shroud provides reduced oxides on the solder surfaces and the gas knife removes excess solder on elements that have been solder coated. The apparatus has a solder reservoir for holding solder with a solder nozzle projecting therefrom and a pump for forming a solder wave from the nozzle. Two solder waves may be provided each with their own cover plate and gas supplied on each side of each wave below the cover plate.

Abstract: A method of welding in which an inert gaseous shield at a welding zone is provided by a mixture of gases of different densities. The proportions of the individual gases in the mixture are controlled to ensure that the density of the gas mixture is about the same as the density of the surrounding atmospheric air. Cryogenic means may be used to form a condensed gas plug in a pipe or the like to be welded.

Abstract: A preheater for a wave soldering machine has high volume convection heating permitting components on circuit boards to be heated to more uniform temperatures throughout the assembly and more rapidly without damage to the components, the assemblies or both. The machine comprises a conveyor for circuit assembly boards, a housing through which the conveyor passes having an entrance and an exit, and a plurality of heating zones in the housing extending along the conveyor. Dividers are provided between heating zones and apertured heating panels are disposed in each of the zones with a space behind each of the panels and a recirculating gap around each of the panels. A fan is positioned in the space behind each of the panels for recirculating gas, either air or inert gas through the panels and the recirculating gap.

Abstract: A cover plate extends over a solder reservoir and has a slot for a solder wave to extend up above the plate, a gas excluding oxygen is supplied under the cover plate and flows up through the slot on both sides of the solder wave to blanket the solder wave. It has been found that oxygen content on the surface of the solder and on the solder wave is reduced so that clean oxide free soldering occurs. The apparatus has a solder reservoir for holding solder with a solder nozzle projecting therefrom, a pump for forming a solder wave from the nozzle, a cover plate for covering at least a portion of the reservoir having a longitudinal slot for the solder wave to pass therethrough. Provision is made for supplying pressurized gas, which is oxygen free, to pass upwards through the slot on both sides of the solder wave to provide a gas blanket over the solder wave, and a conveyor conveys elements to be soldered to pass through the solder wave.

Abstract: A reflow system for heating solders temporarily attaching electronic components to a circuit board, includes an elongated heating chamber in which a conveyor extending from an inlet to an outlet of the heating chamber, at least one first heating unit, a fan unit and an organic substance decomposition unit are disposed. The conveyor, first heater unit and fan unit are arranged to circulate gas in the heating chamber along a circulation path such that the gas is first heated by the first heater unit, then forced by the fan against the conveyor, and thereafter heated again by the first heater unit. The organic substance decomposition unit is disposed in the circulation path. The solders are heated by hot air. It is possible to heat the solder with hot nitrogen gas in which instance a nitrogen gas supply unit disposed outside the heating chamber is used to fill the heating chamber with nitrogen gas.

Abstract: The present invention is a unique solder reflow oven useful for annealing electronic parts through convective heating. It has an enclosed chamber with an entrance and an exit. A conveyor is located in the lower part of the chamber for transporting electronic parts from the entrance to the exit, and a diffuser plate is suspended in the upper part of the chamber. The diffuser plate has a central duct and a periphery edge. An entrance heater plate and an exit heater plate are mounted on the periphery edge of the diffuser plate and located proximal to the entrance and the exit of the chamber respectively. An impellar is mounted above the central duct of the diffuser plate for forming in the chamber a multiplicity of circulatory airstreams which are orginated from the impeller and circulating from above the diffuser plate, around the periphery edge of the diffuser plate, then between the diffuser plate and the conveyor and toward a lower central region below the central duct of the diffuser plate.

Abstract: A short hood for enclosing and providing a protective atmosphere over not more than the solder pot of a machine for wave soldering printed circuit boards. Other operative areas of the machine are exposed to air. The entrance and exit openings to the hood for the circuit boards are covered by electrically conductive curtains of thin material cut into vertical strips. The process employs a thin layer of no-clean flux and allows up to 5% oxygen content in the protective atmosphere.

Abstract: A reflow soldering apparatus having a pre-heating chamber and a reflow chamber, wherein a hot gas recirculation system including a cross-flow blower, a diverging nozzle and a heater is provided in the reflow chamber or both in the pre-heating chamber and the reflow chamber, so that a hot gas such as heated air is uniformly applied to the object such as a combination of a substrate and an electronic parts carried by the substrate, whereby uniform distributions of temperature and flow velocity of the hot gas are attained. The hot gas recirculation means may be arranged so as to vary the angle at which the hot gas impinges upon the substrate and the breadth over which the hot gas is applied.

Abstract: A device for providing a non-oxidizing atmosphere above a soldering bath in a vat of a machine for wave soldering, includes a hooding assembly closing the vat, an inner space and a conveyor for electronic circuits extending through the inner space. The inner space is separated from the surrounding atmosphere through seals disposed along the path of the circuits. There is structure for providing and maintaining a non-oxidizing atmosphere in the inner space, for example an inert gas or a mixture of inert and reducing gas.

Abstract: A machine for soldering printed circuit boards and the like includes a housing enclosing an outer process chamber having a soldering station and fluxing station enclosed therein and an inner heating chamber, in combination with input and output transport conveyors on which the circuit boards enter and exit the housing. The heating chamber includes an elevator rack assembly which transports a succession of circuit boards vertically between the input and output conveyors while subjecting the circuit boards to controlled heating. The heating chamber may also be supplied with an inert or reducing gas to facilitate or eliminate fluxing requirements. The environment within the housing is maintained by air lock doors.

Abstract: In case of suspending an apparatus upon the completion of soldering operation, from not smaller than 50% to less than 95% of a thermomedium in a reflow section is transferred to a filtering tank and the remaining thermomedium is made to pass through a water separator in advance of suspending the apparatus, so that water in the thermomedium is removed. This water removing operation makes it possible to prevent the corrosion of the reflow section and the deterioration of the thermomedium. Additionally, a method is disclosed for preventing water to be mixed with the thermomedium by warming the reflow section before operation.

Abstract: A reflow furnace has a tunnel through which a conveyor for printed circuit boards passes. A plurality of pairs of panel-type blowers capable of blowing hot gas are disposed in the tunnel. The two panel-type blowers in each pair are disposed opposite one another above and below the conveyor. Each panel-type blower has an inlet and a discharge port. The discharge ports of opposing panel-type blowers partially overlap one another in the longitudinal direction of the furnace. When a printed circuit board is present between a pair of panel-type blowers, gas discharged from the discharge ports simultaneously heats both sides of the printed circuit board.

Abstract: A convection braze furnace for brazing aluminum heat exchangers in an inert gas rich atmosphere includes entrance and exit vestibules forming atmosphere barriers of suspended stainless steel strips. The interior of the braze furnace is divided into multiple zones for progressively heating the heat exchangers to a brazing temperature and then cooling the heat exchangers in the final zone. An impeller circulates the heated intent gas atmosphere within each zone to accelerate heat transfer. A chain type conveyor supports the heat exchangers as they are moved through the braze furnace. An isolated return tube surrounds the lower return side of the conveyor chain as it passes through the braze furnace. The braze furnace housing is comprised of inner and outer shells having an inert gas pressurized cavity interstitial therebetween. The inner shell includes a plurality of expansion strips having generally ellipsoidal corner expansion joints.

Abstract: A soldering apparatus is disclosed which comprises a conveyor for moving print circuit boards along a predetermined path, an inert gas-filling chamber provided with a solder tank wherein the print circuit board is soldered in the inert gas atmosphere, primary and secondary, external air shutoff chambers positioned in front of and in rear of the inert gas-filling chamber, respectively. Both primary and secondary chambers are provided respectively with a first shutter having a mechanism for open/close action and capable of isolating the inside of the chambers from external air and with a second shutter having a mechanism for open/close action and capable of preventing release of the inert gas in the inert gas-filling chamber and are connected through a valve to a vacuum tank capable of evacuating the primary and secondary chambers.

Abstract: A novel composition of matter is disclosed comprising perfluorinated, ethyldimethyl cyclohexane. The compound has unique utilities in vapor phase heating and soldering, oxygen transport for biological fluids and other requirements for an inert, stable fluid.

Abstract: A reflow soldering method and the apparatus thereof is described for soldering a base board having electronic elements located thereon by an inert gas circulated through heater means in a plurality of chambers while the base board is transported through all the chambers, the inert gas being circulated by ventilating means driven by drive means, the method and the apparatus thereof comprising a shield case for enclosing at least the chambers, the ventilating means and the drive means to shut off the same from an outer air and refrigerating means for cooling down the inert gas in the shield case.

Abstract: A fluxless reflow soldering processing and system having a reactive inert gas control arrangement coupled to a conventional reflow soldering head for enabling solder to wet metallic surfaces for joining purposes. The gas control arrangement includes a set of gas regulating valves and heat exchange units for supplying selected quantities of inert gases under pressure at various temperatures to a soldering area during the soldering process. The inert gases are employed to clean the soldering area of metal oxides and are used to facilitate the forming of a reliable solder joint by inhibiting the formation of metal oxides and by helping to cool down the solder joint in a substantially uniform manner.

Abstract: An infrared soldering machine has an inert gas atmosphere to prevent oxidation of the solder. Heaters positioned within the machine housing above a conveyor have through apertures and fans direct inert gas down through the heaters onto the conveyor. The forced convection assists in maintaining uniform temperature across the conveyor. In order to prevent leakage of ambient air into the housing where the fan shafts protrude for connection to electric motors, a gas seal is provided at each fan shaft. The seal extends between two spaced bearings rotatably securing the fan shaft. Each electric motor is mounted away from the heat of the machine and is connected to the respective fan shaft by means of a belt drive. A novel gas curtain, which may be clamped at different angles, improves the gas seal at entry and exit locations of the conveyor.

Abstract: A localized soldering station is described that uses the vapor phase reflow principle. A container has of a medium selected because of the temperature at which it changes to a vapor. A heated conduit maintains the vapor state while conveying the vapor to a work location where a module with a part to be removed or attached by solder connections is supported. A transparent, quartz nozzle confines the vapor to the part and its solder connections and is positioned accurately by a unit that includes a guide light. Vapor will lose its latent heat of vaporization upon contact with the part and its solder connections, causing the solder to reflow and change back to a liquid, which is collected for reuse. When in a standby or ready condition, vapor is conveyed up through a shutoff valve through cooling fins where it changes back to a liquid and returns to the container, avoiding loss.

Abstract: A purge gas unit establishes an enclosed zone for purge gas within tubes or pipes having portions which are to be joined by welding. The purge gas unit includes a first bladder to be positioned on one side of the welding location and a second bladder positioned on the other side of the location. A purge gas supply tube extends through the first bladder and has an opening near the second bladder through which purge gas is supplied to the weld zone or space between the bladders. A vent tube extends through the first bladder and communicates with the weld zone near the first bladder and with a space beyond the first bladder. A safety cable also is attached to the second bladder and extends at least substantially through the first bladder, with the cable enabling the purge unit to be removed from the tubes after welding. The bladders can have annular chambers with central passages through which elongate members can extend. The bladders, in another embodiment, can be substantially flat when not inflated.

Abstract: A jig for use in manufacturing header assemblies from pipe and tubing. The jig assures the proper orientation and alignment of components during fit up and joining of component parts into a complete header assembly. In addition, the jig is configured to direct a flow of a purge gas that blankets the interior surfaces of the header assembly during a joining process such as soldering, brazing or welding and thus prevents oxidation of those surfaces.

Abstract: The apparatus of the present invention may be utilized for the automated bonding of electronic components to a circuit board. A placement and bonding head is attached to a manipulatable robotic arm and is utilized to select an electronic component having a plurality of conductive leads from a supply of such components and position that component adjacent a plurality of contact pads on a circuit board. While retaining the electronic component within the placement and bonding head, the component is then thermally bonded to the contact pads. In one embodiment of the present invention, an electronic component may be optically inspected while being retained within the placement and bonding head. In another embodiment, thermal bonding is accomplished utilizing a plurality of thermally activatable blades which each include a thermocouple mounted adjacent thereto.

Abstract: A tunnel enclosure has a fluid barrier curtain at an entry and an exit and provides an apparatus for soldering an element. The fluid barrier curtains permit an additive, such as a soldering aid or the like to be included with the fluid at the curtain. More than one zone permits different temperatures or gas atmospheres and elements are passed from zone to zone with fluid barrier curtains between. A process for soldering comprises conveying an element into an enclosed zone through an entry containing at least one fluid barrier curtain, with an additive added to fluid in the curtain, heating and soldering the element in the zone, and conveying the element from the enclosed zone through an exit containing at least one fluid barrier curtain.

Abstract: An anti-pollutant soldering iron protects workers against pollutant residual vapors resulting from soldering by operating an air moving fan, or the like, to create a suction air stream in a housing which guides pollutant residues trapped therein to and through a retaining filter and then directs the filtered air to the atmosphere. The air moving fan, or the like, may also be reversed to force the residual vapors away from the soldering iron.

Abstract: This invention relates to a method of conducting a joining/coating operation which provides good wetting of metal-comprising substrate surfaces by metal-comprising filler/coating materials while reducing the rate of metal oxide formation. The joining/coating operation is carried out in a controlled oxidizing atmosphere having an oxidation capability greater than that required to oxidize a metal-comprising filler material used for joining or a metal-comprising coating, but having less oxidation capability than that of air. Typically the controlled oxidizing atmosphere consists essentially of nitrogen and oxygen, wherein the oxygen concentration is controlled at a set point. The range of the setpoint corresponds with an oxygen concentration which can range from greater than about 10 ppm to about 100,000 ppm, depending on the application.

Abstract: An infrared soldering machine has an inert gas atmosphere to prevent oxidation of the solder. Heaters positioned within the machine housing above a conveyor has through apertures and fans direct inert gas down through the heaters onto the conveyor. The forced convection assists in maintaining uniform temperature across the conveyor. In order to prevent leakage of ambient air into the housing where the fan shafts protrude for connection to electric motors, a gas seal is provided at each fan shaft. The seal extends between two spaced bearings rotatably securing the fan shaft. Each electric motor is mounted away from the heat of the machine and is connected to the respective fan shaft by means of a belt drive.

Abstract: A nozzle assembly is shown for depositing solder onto a series of conductive surfaces such as the mounting pads of a surface mount integrated circuit board. The nozzle assembly includes a nozzle head which has an interior bore for receiving an elongate heat source. The nozzle head also includes an orifice for receiving solid solder fed within the interior bore to contact the elongate heat source. The interior bore terminates in a solder reservoir for molten solder which is fed within the inteiror bore to contact the elongate heat source. The molten solder is dispensed through a tip opening to deposit uniform amounts of solder on each pad. A source of bleed gas is supplied to the interior of the assembly to protect the component parts and excluse oxygen from the interior of the assembly. A cover gas is also supplied to the solder site to reduce oxidation of the moltent solder and reduce the amount of flux required.

Abstract: A wave soldering apparatus and process occurs in an atmosphere which substantially excludes oxygen. By providing a pressurized effect on an element to be soldered while passing through a solder wave, fluxless soldering is accomplished avoiding the necessity to remove flux residues. The element is preheated in a shield gas atmosphere substantially excluding oxygen, moved in a predetermined path so that at least a portion of the element passes through the solder wave which is oscillated while the element is in the solder wave and maintained in the shield gas until solder on the element has solidified.

Abstract: An apparatus for aligning and supporting confronting pipe or tube sections to be welded together. An elongated supporting table is provided with a pair of inwardly grooved tracks and various pipe secondary support members are also provided to mate with the tracks and to hold several pipe or tube arrangements utilizing conventional T-fittings, 45.degree. and 90.degree. elbow fittings, nozzle fittings, etc. The apparatus permits minimal setup time, proper alignment, stability during welding and the use of conventional orbital pipe welding heads and a smooth angular welding surface free from interference by prior art longitudinally disposed clamping external members.

Abstract: The present invention relates to a soldering machine, comprising: a soldering chamber wherein the soldering process is performed; a first lock chamber connecting to the soldering chamber; a second lock chamber connecting to the soldering chamber; two openings each arranged between a lock chamber and the soldering chamber; two openings each connecting a lock chamber to the outside wherein each opening is closable by a door; means for creating a vacuum in the lock chambers; means for transporting objects for soldering from the outside through the first lock chamber, the soldering chamber and the second lock chamber.

Abstract: A method and apparatus for uniting workpieces of silicon-infiltrated silicon carbide with large dimensions includes surrounding each of two silicon-infiltrated silicon carbide workpieces with at least one tightly closing shell in the vicinity of a junction between the workpieces, defining at least one intermediate space between the shell and the workpieces. A vacuum or an inert gas atmosphere is maintained in the intermediate space or spaces. Solder is placed at the junction and the junction is locally heated to soldering temperature for materially bonding the workpieces by soldering at the junction.

Abstract: Disclosed is a novel fluorocarbon comprising carbon atoms and fluorine atoms and having no double bond, the atomic ratio of fluorine to carbon atoms being 1.50 to 1.93, which exhibits a liquid state at room temperature. The liquid fluorocarbon has excellent water- and oil-repellent properties and can advantageously be used, for example, not only as a water- and oil-repellent but also as an inert liquid, a heat transfer agent and a vapor phase soldering liquid in various fields, especially in the electronic industry. The liquid fluorocarbon can be obtained directly from a pitch or from a pitch fluoride which can be obtained by direct fluorination of a pitch.

Abstract: The soldering arrangement has a lengthwise extending tunnel arrangement (1) with a soldering tunnel (3) through which a conveyor arrangement (10) for the work pieces extends. A soldering tunnel (3) which is inclined upwardly in the conveying direction is provided with a floor opening which is surrounded by a downwardly protruding sealing skirt (18) which is immersed in the molten liquid solder material (20) in a tub (19) below the soldering tunnel (3). The soldering nozzles (24, 25) arranged within the soldering tunnel (3) are supplied through riser channels within the sealing skirt (18). A protective gas conduit (41) for supplying nitrogen opens into the soldering tunnel (3). The soldering tunnel (3) and the conveyor path of the conveyor arrangement (10) extending within the soldering tunnel (3), are tiltable about a horizontal crosswise axis (47), whereby the inclination of the soldering tunnel (3) is adjustable.

Abstract: A ball bonding apparatus is provided with a "flame off" electrode which is positioned, during flame off, around and above the capillary tool so that the spark for melting the wire passes in close proximity to the end of the capillary tool. The flame off electrode is preferably mounted on the capillary tip.

Abstract: A brazing oven includes an arrangement employing a gas curtain or barrier to cover the port or opening of the oven whenever the door is opened. The curtain or barrier is formed by a region of flowing conditioned air directed across the opening. The flowing air curtain or barrier prevents gas from exiting the oven interior when the door is opened, and it also serves to replace or replenish any conditioned air which happens to escape from the oven interior. The air curtain or barrier is generated by a ported manifold and supply located either on the oven housing exterior adjacent the opening or inside the oven housing adjacent the opening.

Abstract: A fully-fluorinated and fully saturated fluorocarbon, containing at least two condensed or non-condensed six-membered rings, seventeen carbon atoms and from 28 to 32 (inclusive) fluorine atoms in its molecule, and having a boiling point from 250.degree. to 265.degree. C.; provided that where the rings are non-condensed they are separated by not more than 4 carbon atoms. Such multi-ring C.sub.17 saturated-perfluorocarbons are produced by the saturation fluorination of the corresponding multi-ring hydrocarbons and are suitable for use as high-temperature vapour-soldering fluids, especially for use with solders melting above 200.degree. C.

Abstract: Novel compositions include compounds of the formula: ##STR1## wherein the carbon rings are fully fluorinated.

Abstract: Novel compositions include compounds of the formula: ##STR1## wherein the carbon rings are fully fluorinated and R is selected from the group consisting of fluorine, --CF.sub.3 or --CF(CF.sub.3).sub.2.