A solder paste is adopted, the solder paste containing: a solder alloy powder in which a content of solder alloy particles having a particle size of 8 μm or less is 99% by mass or more with respect to a total mass of the solder alloy powder; and a flux. This flux contains an acid-modified rosin, a solvent, an activator, and a thixotropic agent, in which the activator contains a halogenated aliphatic compound, and a dicarboxylic acid represented by General Formula (2).

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[in the formula, R represents an alkylene group having 1 to 7 carbon atoms, or a single bond, provided that a methylene group constituting the alkylene group may be substituted with an oxygen atom]

A flux according to the present invention is a flux for soldering, the flux including: an unsaturated aliphatic alcohol having one unsaturated bond, a thixotropic agent, and a solvent, in which the unsaturated aliphatic alcohol includes oleyl alcohol, and a content of the oleyl alcohol is 2.0 mass % or more and 12.0 mass % or less based on the entire flux.

A solder alloy is used for soldering, and its chemical composition in mass % includes: 2.0 to 4.0% of Ag; 0.6 to 1.2% of Cu; 2.0 to 5.0% of Sb; 1.1 to 3.5% of In; 0 to 0.20% of Ni; 0 to 0.20% of Co; 0 to 0.05% of Ge; and balance of Sn, and impurities.

A method includes applying a first flux onto an electrode provided on a substrate and placing a solder material on the electrode, heating the substrate to form a solder bump on the electrode, deforming the solder bump to provide a flat surface or a depressed portion on the solder bump, applying a second flux to the solder bump; placing a core material on the solder bump, the core material including a core portion and a solder layer that covers a surface of the core portion, and heating the substrate to join the core material to the electrode by the solder bump and the solder layer.

A solder paste includes a solder powder and a flux. The flux includes a rosin, an activator, a solvent, and a thixotropic agent containing a polyethylene glycol. A content of the polyethylene glycol is 10 mass % to 20 mass % with respect to a total mass of the flux, a content of the thixotropic agent excluding the polyethylene glycol is 5 mass % or less with respect to the total mass of the flux, and a content of the rosin is more than 15 mass % and 50 mass % or less with respect to the total mass of the flux.

A brazing material for brazing a brazed plate heat exchanger comprising a number of heat exchanger plates being provided with a pressed pattern of ridges and grooves adapted to provide contact points between neighbouring heat exchanger plates, such that the heat exchanger plates are kept on a distance from one another and such that interplate flow channels for media to exchange heat are formed between the heat exchanger plates comprises a brazing alloy comprising at least one melting point depressing element and metals resembling the composition of the heat exchanger plates. The brazing material comprises a mixture between grains of a melting brazing material having solidus and liquidus temperatures lower than a brazing temperature and a non-melting brazing material having solidus and liquidus temperatures above the brazing temperature. The ratio between the melting and non-melting brazing materials is such that an alloy formed by the melting and non-melting brazing materials has a solidus temperature lower than the brazing temperature and a liquidus temperature higher than the brazing temperature.

Provided are a solder alloy, a solder paste, a solder ball, a solder preform, and a solder joint, which have a melting temperature within a predetermined range, and high tensile strength and shear strength, suppress generation of voids, and have excellent mountability due to their thin oxide films. The solder alloy has an alloy composition consisting of, by mass %, Ag: 2.5 to 3.7%, Cu: 0.25 to 0.95%, Bi: 3.0 to 3.9%, and In: 0.5 to 2.3%, with the balance being Sn, and the alloy composition satisfies the following relations (1) and (2): 8.1≤Ag+2Cu+Bi+In ≤11.5 (1), and 1.00≤(Bi+In)/Ag≤1.66 (2). Ag, Cu, Bi and In in the relations (1) and (2) each represent the contents (mass %) in the alloy composition.

Pattern transfer sheets and methods are provided for printing paste patterns (e.g., thin fingers) with a high aspect ratio and for increasing throughput in pattern transfer printing. Trenches in the pattern transfer sheets, that are configured to be filled with printing paste and to enable releasing the printing paste from the trenches onto a receiving substrate upon illumination by a laser beam—are coated internally by a coating configured to disintegrate upon the illumination. The coating is configured to enhance the releasing of the paste—increasing throughput and printing accuracy. The receiving substrate may be cleaned after paste deposition by removing disintegration products of the coating therefrom. Alternatively or complementarily, laser absorbing dye may be mixed into the printing paste to facilitate its release from the trenches.

Provided is a solder paste which uses a conventional flux, and for which long-term preservation is made possible and an easy preservation method can be realized by suppressing changes in the viscosity of the paste over time. This solder paste is provided with a solder powder, a zirconium oxide powder, and a flux, and changes in the viscosity of the paste over time are suppressed.

A flux for a solder paste includes rosin, an activator and a solvent. The solvent includes a monoalkylene glycol-based solvent and a solid solvent that is solid at 20° C. The total content of the monoalkylene glycol-based solvent and the solid solvent ranges from 40% by mass to 60% by mass with the total amount of the flux as 100%. The content of the solid solvent ranges from 5% by mass to 25% by mass with the total amount of the flux as 100%.