Abstract: A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste exhibits high joint strength at room temperature and at high temperatures, excels in terms of temporal stability, exhibits minimal void formation, and can form highly cohesive joints. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising: a powdered intermetallic compound that comprises copper and tin and has metal barrier layers covering the surfaces thereof and a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

Abstract: A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste excels in terms of temporal stability and exhibits high joint strength at room temperature and at high temperatures. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising: 10-70 mass % of a powdered intermetallic compound comprising copper and tin and 30-90 mass % of a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

Abstract: A method of preventing variation of the viscosity of a solder paste, and flux for producing solder paste, viscosity of which is prevented from varying. In the flux, which is suitable to be mixed with solder powder to produce the solder paste, an amount of methacrylate polymer which reduces a thixotropic index of the solder paste and enhances viscosity thereof is contained. As the methacrylate polymer, polyalkyl methacrylate having an alkyl group is preferable, and it is preferable that an addition amount of polyalkyl methacrylate is 05.-5.0 mass % of the flux. Further, as a thixotropic agent, hardened castor oil is preferably added.

Abstract: A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste excels in terms of temporal stability and exhibits high joint strength at room temperature and at high temperatures. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising: 10-70 mass % of a powdered intermetallic compound comprising copper and tin and 30-90 mass % of a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

Abstract: A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste excels in terms of temporal stability and exhibits high joint strength at room temperature and at high temperatures. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising the following: 10-70 mass % of a powdered intermetallic compound comprising copper and tin and 30-90 mass % of a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

Abstract: A solder paste whereby metal does not flow out of a joint during a second or subsequent reflow heating stage. The solder paste exhibits high joint strength at room temperature and at high temperatures, excels in terms of temporal stability, exhibits minimal void formation, and can form highly cohesive joints. The solder paste comprises a powdered metal component and a flux component, the powdered metal component comprising: a powdered intermetallic compound that comprises copper and tin and has metal barrier layers covering the surfaces thereof and a solder powder including tin as a main component. Neither the powdered intermetallic compound nor the solder powder contains a copper-only phase, inhibiting the elution of copper ions into the flux.

Abstract: A solder paste which solves any nozzle clogging that suddenly occurs in a case of being used in a discharging method and which also realizes residue-free because flux is decomposed by heating during soldering. In the solder paste produced by mixing solder powders with the flux, the flux is flux containing polyalkyl-methacrylate of not less than 1.0 mass % and less than 2.0 mass % as methacrylate polymer of an amount such that it prevents the solder powders from being sedimented at ordinary temperature and it is decomposed or evaporated in the process of heating during the soldering, and containing stearic acid amide of not less than 5.0 mass % and less than 15.0 mass %, as viscosity modifier, wherein viscosity is 50 through 150 Pa·s. It is preferable that the content of flux in the solder paste is not less than 11 mass % and less than 13 mass %.

Abstract: To provide flux for producing solder paste, viscosity of which is prevented from varying. In the flux which is mixed with solder powder to produce the solder paste, an amount of methacrylate polymer which reduces a thixotropic index of the solder paste and enhances viscosity thereof is contained. As the methacrylate polymer, polyalkyl methacrylate having an alkyl group is preferable and it is preferable that an addition amount of polyalkyl methacrylate is 0.5-5.0 mass % thereof. Further, as the thixotropic agent, hardened castor oil is preferably added.

Abstract: To provide flux which has a property of suppression of sedimentation of the solder powder, dissolves by heating at the time of the soldering to remain no residue and does not block any wettability of the solder. In the flux which is mixed with solder powder to produce the solder paste, an amount of methacrylate polymer which suppresses of sedimentation of the solder powder at a normal temperature range and dissolves or vaporizes during a heating course at the time of the soldering. As the methacrylate polymer, polyalkyl methacrylate having an alkyl group is preferable and it is preferable that an addition amount of polyalkyl methacrylate is not less than 0.1 mass % through less than 1.0 mass %. It is also preferable to contain further a solvent having at least three OH groups.