Abstract: A process for wave soldering or reflow soldering comprises contacting substrates with a supply of molten solder containing from about 0.0001 to about 0.1% by weight of phosphorous in an atmosphere of diluent gas containing up to about 0.1% by volume oxygen. A reduced incidence of bridging and other soldering defects occurs.

Abstract: A preflux for a printed circuit board is provided, and the preflux has an excellent heat resistance adapted to a method of surface mounting electronic parts on the printed circuit board, and it is highly operable and reliable. The preflux is comprised mainly of a 2-alkylbenzimidazole derivative having the general formula of ##STR1## wherein R.sup.1 and R.sup.2 may be identical with or different from each other and are hydrogen atom, a lower alkyl group or a halogen atom, and R.sup.3 is an alkyl group of three or more carbon atoms, and contains a chelating agent reacting with copper ions added thereto. Addition of a proper amount of the chelating agent to the preflux makes it easy to form a highly heat-resistant film of the preflux only on copper or copper alloy patterns without masking the printed contacts and joint land.

Abstract: The invention provides a method that can be used online in a continuous printed circuit soldering process to measure and control the composition of soldering fluxes, in particular low-solids fluxes that utilize a solvent with a specific gravity close to the specific gravity of the flux composition. Samples of the flux are analyzed by ultra-violet absorption to determine solvent content and, based on this analysis, make up solvent is added to the flux composition to maintain a steady state composition.

Abstract: The brazing process for an aluminum headered condenser is improved by adding a flux drying and preheating process that both dries the wet flux layer and prepares the part for more efficient brazing. An oven is divided into two directly connected zones, one that dries the flux layer at a lower temperature, and one that preheats the condenser at a higher temperature that is still too low to melt the flux layer. Both the tanks and the core of the condenser are heated hotter than they would be if they were only flux dried, although the core is heated significantly more. The preheated parts are then transported to the braze furnace indirectly, through ambient, which serves to cool the core more than the tanks, to a temperature lower than the tanks. Finally, the part is run through a normal braze cycle. Because the tanks begin hotter than normal, they reach braze melt temperature sooner than they normally would.

Abstract: Potential difficulties with corrosion in hear exchangers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: A no-clean soldering flux consists essentially of one or more halide-free, water soluble activators in an aggregate amount not exceeding about 5% by weight of the flux, a water soluble fluorinated surfactant in an amount not exceeding about 1% by weight of the flux, and water. The flux is substantially VOC-free and is particularly useful in a method of producing soldered printed wiring assemblies with minimal residual ionic contamination, so that post-soldering cleaning of the assemblies is unnecessary. The absence of significant amounts of VOC's and the elimination of post-soldering cleaning result in substantial environmental and production-related benefits.

Abstract: A method is provided for electrically connecting a first electronic component which is not resistant to a reflowing temperature and a second electronic component which is resistant to the reflowing temperature to a substrate.

Abstract: An aluminum brazing method includes the steps of preheating aluminum members in the form of workpieces coated with flux and brazing material in antioxidizing atmosphere gas up to a temperature around the flux activating temperature, and then heating the aluminum members from the temperature around the flux activating temperature to the brazing temperature mainly by forced convection of the anti-oxidizing atmosphere gas. An aluminum brazing furnace includes radiation intercepting members which are provided in the brazing chamber and which intercept the heat radiation to the work-pieces.

Abstract: Solder powders coated with a thin layer of parylene and solder pastes containing the coated solder powders are disclosed. The coated solder powders can exhibit a high degree of resistance to oxidation and to reaction with the flux contained in the solder paste without substantially interfering with the reflow characteristics of the solder.

Abstract: A multiple-lead element soldering method of this invention contains a step of beforehand mounting a band-shaped sheet solder on a wiring board so as to be bridged over land portions of a wiring pattern on which lead terminals of the multiple-lead element are to be soldered, and a step of heating the band-shaped sheet solder by a heat press method to melt the band-shaped sheet solder, whereby the land portions of the wiring pattern and the lead terminals of the multiple-lead element are accurately soldered through the melted band-shaped sheet solder with sufficient amount of solder.

Abstract: A solder self-alignment process for aligning a semiconductor chip (13) with, and bonding the chip to, a substrate (12) is preformed in an atmosphere rich in gaseous formic acid, at least during the melting step. It is preferred that the formic acid atmosphere be maintained during the self-alignment step and the step of cooling and hardening the solder elements (23). With this feature, one can completely avoid the use of any solid or liquid fluxes and avoid the consequences of such use. Nonetheless, the molten solder elements (23) dependably bond to the bonding surfaces and vertically align themselves.

Abstract: Disclosed is a method and apparatus for applying flux and solder in order to attach connectors to printed circuit boards (PCBs). Flux is applied to the connector tails and the PCB pads by means of a roller mounted above a flux reservoir. The piece parts are then exposed to a solder wave such that the solder sticks only to the selected area to which the flux was applied.

Abstract: The invention provides a method of soldering a conductor on to a ceramic resistor body having a positive temperature coefficient, said method employing a soldering flux which is free of organic compounds having a high molecular weight. Preferably, the soldering flux comprises an aqueous solution of zinc chloride and hydrazine hydrochloride. The inventive method reduces the risk of explosion of soldered PTCs.

Abstract: A method of manufacturing tubes filled with powdery and/or granular substances, such as flux-cored welding wires. A tube filled with a powdery and/or granular substance is continuously manufactured by forming a metal strip being fed in its longitudinal direction into an unwelded tube (1a) using forming rolls (2), feeding a powdery and/or granular substance (F) into the unwelded tube (1a) being formed through its opening, butt-welding together fringing edges of the opening, and reducing the diameter of the welded tube (1b). An allowable minimum heat input below which cold cracking occurs and a maximum allowable heat input above which spatters whose diameter is not smaller than 0.83 times the inside diameter of the finished tube are generated are determined in advance, and the butt welding is performed with a heat input larger than the allowable minimum heat input and smaller than the allowable maximum heat input.

Abstract: An improved method for assembly of a brazed condenser unit for use in an automobile air conditioning system is provided which significantly reduced the defective rate due to leaky internal joints within the condenser. A sufficiently viscous flux composition is applied to the internal features of the condenser during assembly. The flux composition is specifically applied to surfaces of the aluminum alloy header which is clad internally with the brazing alloy, so as to promote complete and consistent brazing of the internal tubes and components. The brazing flux composition of this invention consists of potassium fluoaluminate particles in a liquid carrier consisting of a polyhydric alcohol, e.g., propylene glycol, and minimal amounts of water. This flux composition has a sufficiently high viscosity so as to permit its easy, consistent deposition on the header surface without subsequent displacement during assembly and processing.

Abstract: A method of brazing a temporarily assembled heat exchanger includes the steps of spraying an ionized fluid such as water on one surface. A powdered electrostatically charged flux is blown onto the opposite surface of the heat exchanger. A portion of the powdered flux is attracted to the one surface by the ionized fluid. Therefore, the flux material is uniformly spread across the heat exchanger. Finally, the heat exchanger is heated and brazed.

Abstract: An electronic component (14) is soldered to a circuit carrying substrate (11) by a method that allows the component to remain in better contact with the flat solder pads of the substrate. The circuit carrying substrate (11) has a plurality of solder pads (12) disposed thereon, each pad consisting of a terminal portion (16), a solder reservoir portion (18), and a bridging portion (17). The terminal portion is connected to the reservoir portion by the bridging portion. The bridging portion is typically a necked down portion of the pad. The electronic component (14) has a plurality of solderable terminals (15) corresponding to the terminal portions (16) of the solder pads (12). Each of the solder pad reservoir portions are coated with a reservoir of solder (23). The amount of solder coated onto the reservoir portion is sufficient to provide a fillet between the component (14) and the solder pad terminal portion (16) during a subsequent heating step.

Abstract: The invention provides a brazing flux for brazing metal and a method of using the same. More particularly, the invention provides a brazing flux for use in joining pieces of aluminum or aluminum alloys. The brazing flux comprises from about 62 percent by weight to about 74 percent by weight hydrated potassium cryolite and from about 26 percent by weight to about 38 percent by weight AlF.sub.3. The hydrated potassium cryolite comprises K.sub.3 AlF.sub.6 and K.sub.2 AlF.sub.5.H.sub.2 O. Preferably, the brazing flux is substantially free of KAlF.sub.4 and unreacted KF. More particularly, the brazing flux contains no KAlF.sub.4 and no unreacted KF. The brazing flux is capable of displaying a melting temperature as low as 560.degree. C. (1040.degree. F.).

Abstract: A method of soldering leadless components to a printed circuit board without using solder paste is disclosed. A thick layer of solder (42) is plated onto a printed circuit board (40), and an oxide layer (43) is formed by heating. Solder flux (45) is applied to those solder pads that are intended to be reflowed, and components (54) are placed. The printed circuit board is heated, and a solder joint (68) is effected between the components (54) and the circuit board (40), while the unfluxed solder pads (66) do not reflow and remain flat. Solder flux is then applied to the remaining solder pads (66) on the same or the opposite side of the circuit board. Additional components (77) are placed, and the circuit board (40) is reflowed a second time.

Abstract: A non-toxic, non-corrosive water-soluble soldering paste comprises at least about 80 wt % of particulate solder and the balance a thixotropic flux base. The flux base has a viscosity of at least about 200,000 cp and comprises (a) a botanical oil, (b) an aqueous emulsion of a thickening agent, such as corn starch or an ethoxylated linear alcohol in water, and (c) an organic acid having at least two carboxylic acid groups, such as citric acid. The paste of the invention produces solder joints of high metallic luster and excellent quality. Clean-up of paste residues is ac complished using only water.

Abstract: Water soluble soldering preflux compositions are shown which include gum arabic, modified polysaccharides and other natural resins as a carrier, an oxidation inhibitor and water. The compositions are useful in the assembly of precisely aligned electrical components during multiple step, electronic card assembly techniques. Use of the preflux compositions according to the method of the invention permits a flexible, site-specific method for joining electronic components to a printed circuit board with a fewer number of steps.

Abstract: Soldering is performed and the residues associated with the soldering process are removed through the use of a specific process. Components such as two integrated circuits or an integrated circuit and mounting board are initially tacked by compression bonding or through the use of adhesives. Flux is introduced, and the components to be soldered are brought to reflow temperature. The flux is chosen so that upon reflow and subsequent cooling to a temperature of 100.degree. C., or lower, the flux remains in liquid state. The flux is then easily removed by cleaning with a miscible liquid that is subsequently removed through processes such as spinning and evaporation.

Abstract: A process for joining ceramic superconductor fibers with a channel to fabricate a superconductor wire includes feeding the fibers into the channel and continuously dispensing a flowable solder paste into the channel over the fibers. The combination of channel, fibers and solder paste is then subjected to a rapid rise in temperature which sequentially activates the flux in the solder paste and then melts the solder. After the workpiece is cooled and the separated flux has been removed, a superconductor wire has been fabricated.

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: Potential difficulties with corrosion in heat exchangers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum; providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: A volatile flux coating solution which, when dry, provides durable protective film coating containing residual flux, and a fluxing-soldering process utilizing such a solution. The coating solution is applied to a cleaned metal surface to be later joined and soldered to another metal surface, thereby obviating the need for recleaning and refluxing at the time of joining and soldering. Where two objects prepared according to this invention are joined, no additional cleaning or fluxing is required, thus saving significant time and labor at the work site. However, an object prepared according to the present invention may nevertheless be joined to an unprepared object at the work site if the unprepared object is prepared by conventional techniques, thereby allowing the prepared object to be joined with either prepared or unprepared objects. The soldering process is completed by soldering the two objects together according to conventional techniques.

Abstract: A non-toxic, non-corrosive liquid soldering flux is provided, comprising an organic acid, such as citric acid, and a non-toxic carrier, such as water. This unique flux produces solder joints of high mettalic luster and excellent quality. Disposal presents no health hazards, and clean-up of flux residues is accomplished using only water.

Abstract: A method of joining components to a substrate by reflow soldering with non-rosin-based flux containing solder is disclosed comprising heating the solder in the presence of the components in a low oxidizing atmosphere.

Abstract: A dispenser (100) for solder flux includes a first solder flux reservoir (110) with a dispensing tip (118) at one end thereof for dispensing solder flux (112) in response to a frictional pressure applied to the tip. A second solder flux reservoir (102) is also included having a dispensing channel (106) for dispensing solder flux (104) responsive to a pressure applied to the flux (104) within the second solder flux reservoir (102).

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: A process for soldering a substrate surface which allows low ionic contamination without a cleaning operation which comprises (a) applying a stannous fluoride or eutectic mixture thereof to the substrate surface and (b) applying solder to the flux applied in (a). The stannous fluoride which is relatively inactive below its melting temperature can be applied to the substrate surface and the so treated substrate held for an extended period of time prior to soldering without any harmful effect on the substrate. The process is useful in electronic assembly that would include attachment of components to circuit boards, tinning of circuit boards, pretinning of component leads, connectors etc.

Abstract: A process for joining the surface of one preferably metallic member to another at a joint, and using solder to create the joint at a joining temperature, includes applying a medium to the joint which evaporates by microexplosion at below the joining temperature. The microexplosive evaporation of the medium advantageously cleans the surfaces of the members and reduces surface tension to allow solder to flow and wet the surfaces. The medium is advantageously glycerin or a mixture of glycerin and detergent so that no residue remains after the joining operation.

Abstract: A method for aligning and bonding the outer leads of the conductive fingers of a tape-and-semiconductor-chip sub-assembly to a package substrate is disclosed. Each section of tape is provided with an inner support ring and an outer support ring. The conductive fingers extend from under the inner support ring to under the outer support ring. The outer support ring is spaced away from the inner support ring to expose portions of the tape outer leads therebetween. The tape-and-chip sub-assembly is positioned over the package substrate so the outer leads are in register with the appropriate package substrate leads. A deposit of flux is applied to at least one location between the substrate and outer support ring to bond the sub-assembly to the substrate. The bonded outer support ring prevents the sub-assembly from moving so the leads do not become out of register with the substrate prior to and during the lead bonding process.

Abstract: A method of forming a heat exchanger includes brazing heat exchanger components with a flux of non-corrosive fluoride complexes. The components comprise an aluminum alloy having improved brazing characteristics and containing 0.3 to 0.8% Mg, 4.0 to 8.0% Zn, one or more of 0.05 to 0.30% Zr, 0.05 to 0.30% Mn, 0.05 to 0.30% of Cr, 0.05 to 0.30% of Cu, aluminum and unavoidable impurities.

Abstract: Disclosed in a fluxing agent comprising 45% to 55% by weight of peanut oil and 45% to 55% by weight of water-white rosin.

Abstract: Fluxes for use in brazing aluminum-based alloy pieces are disclosed. One is a flux which comprises 70 to 90% wt % K.sub.2 SiF.sub.6 and 30 to 10 wt % AlF.sub.3. The other is a flux which comprises 98.5 to 94 wt % base composition which includes K.sub.2 SiF.sub.6 whose amount is 70 to 90 wt % of the base composition and AlF.sub.3 whose amount is 30 to 10 wt % of the base composition; 0.5 to 3 wt % LiF; and 1 to 3 wt % NaF. In order to facilitate the application of the flux to the pieces to be brazed, polybutene is used as a dispersing agent.

Abstract: The instant flux and paste containing same are for brazing aluminum material. The flux consists essentially of a particulate blend of aluminum fluoride, potassium fluoride, and cesium chloride, or rubidium chloride or a mixture of cesium chloride and rubidium chloride, the fluorides being complexed with each other or not complexed or being a mixture of the complexed and not complexed fluorides. Lithium fluoride, preferably complexed with the other fluorides, is an optional ingredient. The weight fraction of the total fluorides is between about 1/10 and about 9/10, and the A1F.sub.3 -KF weight ratio is between about 4:1 to about 0.4:1.

Abstract: A method for production of a heat exchanger is disclosed, where a powder flux is applied in a process of soldering a heat exchanger core of aluminum. An annular groove is formed in a seat plate. Measures are taken for preventing wetting of the annular groove of the seat plate when sprayed with the water on the preassembled core, such that a non-corrosive flux would not adhere to the annular groove of the seat plate. Water is sprayed in the form of a mist on a preassembled heat exchanger core through plurality of spray nozzles. The annular grooves of the seat plates are thoroughly dried after the application of water for attaining a perfect absence of residual non-corrosive flux in the annular grooves of the seat plates. A non-corrosive flux powder is sprayed onto the preassembled heat exchanger core of aluminum with a powder spray gun. The non-corrosive flux is caused to adhere fast to the portion wetted with the water.

Abstract: A technique for soldering is provided wherein the solder contains a nominal amount of 4 to 5% tin and the remainder lead. A solder flux is utilized which incorporates a lead compound, such as lead acetate. When the solder and flux is heated, a redox reaction will take place in which the lead ions in the flux will replace the alloyed tin in the solder, thereby reducing the tin content of the solder, whereby the ductility of the solder joint is improved.

Abstract: A flux for brazing is prepared from 31.5% to 56.2% of KF and 68.5% to 43.8% of at least one of .UPSILON.-AlF.sub.3 and finely divided .beta.-AlF.sub.3. The KF is dissolved in water, and the AlF.sub.3 is then placed into the resulting KF aqueous solution to react the KF with the AlF.sub.3. The reaction product is dried.

Abstract: A solder paste mixture for soldering surface mount devices to a circuit board using a reflow soldering process which utilize a vapor phase furnace. The solder paste mixture has a metallic content which is 63% tin and 37% lead. The metallic content of the paste consists of 150 micron particles of 100% tin and 150 micron particles of an alloy of 10% tin and 90% lead. Included in the process of soldering components to the circuit board is the step of prebaking the circuit board with solder paste and components in their proper place on the board.

Abstract: A method for producing corrosion resistance heat exchangers having a plurality of aluminum tubular elements and fin members, the method comprising immersing the tubular elements in a bath with passing an electric current so that the surfaces thereof are covered with zinc layers of 0.3 .mu.m or more in thickness; combining the zinc plated tubular elements with fin members covered with a brazing sheet so that a core is provisionally formed; painting the provisional core with a non-corrosive flux; and placing the provisional core in a furnace to braze the fin members to the tubular elements, and also to enable the zinc layers to diffuse over the surfaces of the tubular elements.

Abstract: A halogen-free flux mixture for solder wires having one flux core or a plurality of flux cores based on natural and/or synthetic resins, organic acids, and optionally further additives contains from 20 to 80% by weight of resin, at least 2 organic acids in a ratio of from 1:5 to 5:1 and has an acid value of the total mixture of at least 200. Using said flux mixture, solder wires having one flux core or a plurality of flux cores of from 0.2 to 1.0% by weight can be produced which solder wires meet all requirements, including those made for the SMT technique.

Abstract: Disclosed is a method of forming solder terminals for a pinless module, preferably for a pinless metallized ceramic module. The method is comprised of the following steps: forming a substrate having a pattern of conductors formed onto its top surface and preformed via-holes extending from the top to bottom surface; applying a droplet of flux at at least one of said preformed via-hole openings of the bottom surface of said substrate to fill said via-holes with flux by capillarity and form a glob of flux at the bottom openings; applying a solder preform, i.e.

Abstract: A controlled amount of flux is applied to a circuit board (10) by first directing liquid flux through a nozzle (54) containing means for disintegrating the flux into a very fine fog of tiny flux droplets (62). The fog of flux droplets is injected into a laminar gas stream (52), thereby creating a laminar flux stream which is directed at the circuit board to coat the board with flux. As the flux spray is being directed at the circuit board, the concentration of flux solids on the board is being regulated, typically by controlling the rate of flux pumped into the nozzle.

Abstract: A method of applying a material of particulate form to the surface of an object by using a liquid, wherein the liquid is applied to the surface of the object to provide a film of the liquid thereon, and then the material of particulate form is applied to the film of the liquid on the surface of the object. Excess liquid may be removed from the surface of the object by using a jet of air current before the material of particulate form is applied to the film of the liquid on the surface of the object.

Abstract: A fluxing agent for soldering, e.g. of electronic components, characterized by consisting of a solution comprising 1-15, preferably 2-12% by weight of nonionic surface active agent and/or another substance with similar capacity to form liquid crystals in the fluxing agent film, 1-80, preferably 1-10% by weight of water, and volatile solvent, preferably at least 70% by weight, and minor quantities of activators which are capable of reacting with impurities on the surfaces subjected to soldering, such as halides and carboxylic acids, and preferably with a weight ratio of nonionic surface active agent to water of 1:8 to 5:1 and especially 0.5:1 to 2:1, and a process for soldering using said fluxing agent.

Abstract: A long chain organic acid, such as stearic acid, is used as a flux to bond aluminum to electro-deposited sheet of aluminum, magnesium, or alloys thereof.

Abstract: A heat exchanger core having a tube of aluminum material and heat transfer fins of aluminum material joined to each other with a brazing filler, which has at least part of the surface thereof coated with an inorganic sintered layer incorporating therein a pigment-containing phase of the two complexes of potassium hexafluoroaluminate and potassium tetrafluoroaluminate.

Abstract: In a wave soldering apparatus including a station for forming a standing wave of foamed flux, a preheater station, and a standing wave of hot molten solder station, a flux removing apparatus for reducing the thickness of flux on a coated printed circuit board includes an apertured pipe for gently blowing a plurality of streams of air against the foam coated board, the streams acting effectively as a continuous linear stream of air. The airstreams also blow the foamed flux into apertures in the printed circuit board.