A method of resistance spot welding a workpiece stack-up that includes an aluminum workpiece and an overlapping adjacent steel workpiece so as to minimize the thickness of an intermetallic layer comprising Fe—Al intermetallic compounds involves providing reaction-slowing elements at the faying interface of the aluminum and steel workpieces. The reaction-slowing elements may include at least one of carbon, copper, silicon, nickel, manganese, cobalt, or chromium. Various ways are available for making the one or more reaction-slowing elements available at the faying interface of the aluminum and steel workpieces including being dissolved in a high strength steel or being present in an interlayer that may take on a variety of forms including a rigid shim, a flexible foil, a deposited layer adhered to and metallurgically bonded with a faying surface of the steel workpiece, or an interadjacent organic material layer that includes particles containing the reaction-slowing elements.

An electrode (10) is presented including a sheath (14) formed of a ductile material, an outer coating (16) including a flux material, and a core (12) including at least one of flux material and alloying material. The ductile material may be an extrudable subset of elements of a desired superalloy material and the alloying material may include elements that complement the ductile material to form a desired superalloy material when the electrode is melted. The outer coating may be formed of a flexible bonding material or it may be segmented (18, 20) to facilitate bending the electrode onto a spool. Any hygroscopic material of the electrode may be included in the core to protect it from exposure to atmospheric moisture.

This disclosure relates generally to Gas Metal Arc Welding (GMAW) and, more specifically, to Metal-cored Arc Welding (MCAW) of mill scaled steel workpieces. A metal-cored welding wire, including a sheath and a core, capable of welding mill scaled workpieces without prior descaling is disclosed. The metal-cored welding wire has a sulfur source that occupies between approximately 0.04% and approximately 0.18% of the weight of the metal-cored welding wire, and has a cellulose source that occupies between approximately 0.09% and approximately 0.54% of the weight of the metal-cored welding wire.

As electronic equipment has become smaller in size, printed circuit boards which cannot be subjected to cleaning have been developed, and a no-clean lead-free solder paste is becoming necessary. In order for a solder paste not to require cleaning, it is necessary that the color of the residue be transparent and that the residue be non-tacky. A maleated rosin, which is a rosin suited for no-clean paste, has a high acid value so it is not suitable for a flux for lead-free solder. As a means of suppressing a reaction between a flux containing a maleated rosin and a Sn—Ag—Cu based solder alloy powder, a Sn—Ag—Cu—Sb based solder alloy powder is used which adds 1-8 mass % of Sb to a Sn—Ag—Cu based solder alloy. As a result, it is possible to provide a solder paste which has the excellent effect that the solder paste does not easily undergo changes over time and has a long pot life.

The invention relates to a paste, preferably for joining components of power electronics modules, the paste comprising a solder powder, a metal powder and a binder, wherein the binder binds solder powder and metal powder before a first heating. According to the invention, the binder is free of flux or is a flux having only low activation. In this way, a joining layer which exhibits only few included voids and good mechanical and electrical stability can be provided between a first and a second component.

The present invention is directed to flux compositions and uses thereof. One composition comprises an activator and a solvent being a glycerol ethoxylate with a molecular weight of 200-500. Another composition comprises an activator, a solvent being a glycerol ethoxylate with a molecular weight of 200-500 and an amine. A soldering method for joining objects is also provided, comprising the steps of applying a flux composition to at least a portion of one or more of the objects, and joining the objects.

Provided is a flux for soldering that can suppress a crack in a flux residue even if the flux for soldering is exposed to a cooling and heating cycle at the highest temperature of 150° C. such as the inside of an engine room of automobiles for a long period of time, and a soldering paste composition including the flux for soldering. The flux for soldering includes a synthetic resin, an activator, an organic solvent, and a thixotropic agent, in which synthetic resin contains a triblock copolymer of methacrylic acid ester with acrylic acid ester configured of a linear alkyl moiety having 3 to 6 carbon atoms. In addition, a soldering paste composition including the flux for soldering is used.

A flux according to the present invention contains a rosin methyl ester in which the flux is a solid or solid-like flux at 25° C., and is used for an inside of a flux-cored solder or an exterior of a flux-coated solder.

The object of the present invention is to provide a flux composition and a solder paste composition in which scattering of flux is suppressed. A flux composition comprising an anti-scattering agent represented by formula (1) below, ##STR00001##
wherein Z is optionally substituted alkylene, R.sup.1 and R.sup.2 are each independently optionally substituted alkyl, optionally substituted aralkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted cycloalkyl, or optionally substituted heterocycloalkyl, R.sup.3 and R.sup.4 are each independently optionally substituted alkyl.

A flux for soldering contains 10 to 40 wt % of coumarin, 5 to 30 wt % of a monoamide-based thixotropic agent and 40 to 80 wt % of a solvent. A solder paste contains the flux and a solder powder. A method for producing a soldered product includes supplying the solder paste to a soldering portion of an electronic circuit board, mounting an electronic component onto the soldering portion and heating the soldering portion up to a temperature at which the solder powder melts in a reducing atmosphere containing a reducing gas to join the electronic component and the electronic circuit board.