A solder paste containing a solder powder and a flux, in which the flux contains a keto acid and a hydroxy group-containing compound different from the keto acid, and the keto acid has a melting point of 60° C. or lower, the hydroxy group-containing compound has a melting point of 60° C. or lower and has at least three hydroxy groups in the molecule, and a content of the keto acid, a content of the hydroxy group-containing compound and a content of the solder powder satisfy Expressions (1) and (2),

W.sub.1×⅓≤W.sub.2≤W.sub.1×⅚  (1)

(W.sub.1+W.sub.2)/W.sub.3×100≥2.0  (2) where W.sub.1 represents a weight (g) of the keto acid, W.sub.2 represents a weight (g) of the hydroxy group-containing compound, and W.sub.3 represents a weight (g) of the solder powder.

A solder paste includes a solder powder; and a flux component containing a compound having at least one carboxyl group protected by a trialkylsilyl group.

According to one aspect of the present invention, a lead-free solder alloy includes 2% by mass or more and 3.1% by mass or less of Ag, more than 0% by mass and 1% by mass or less of Cu, 1% by mass or more and 5% by mass or less of Sb, 3.1% by mass or more and 4.5% by mass or less of Bi, 0.01% by mass or more and 0.25% by mass or less of Ni, and Sn.

A bonding material includes: fine silver particles having an average primary particle diameter of 1 to 50 nm, each of the fine silver particles being coated with an organic compound having a carbon number of not greater than 8, such as hexanoic acid; silver particles having an average primary particle diameter of 0.5 to 4 m each of the silver particles being coated with an organic compound, such as oleic acid; a solvent containing a primary alcohol solvent and a terpene alcohol solvent; and a dispersant containing a phosphoric acid ester dispersant (or a phosphoric acid ester dispersant and an acrylic resin dispersant), wherein the content of the fine silver particles is in the range of from 5 wt % to 30 wt %, and the content of the silver particles is in the range of from 60 wt % to 90 wt %, the total content of the fine silver particles and the silver particles being not less than 90 wt %, and wherein the bonding material further includes a sintering aid of a monocarboxylic acid having an ether bond.

The flux according to the present invention includes a fatty acid amide; a first solvent having a temperature, at which its mass measured by thermogravimetry at a nitrogen flow rate of 0.2 to 0.3 L per minute and a temperature increase rate of 10 C. per minute becomes zero, of from 180 C. to lower than 260 C.; and a second solvent having a temperature, at which its mass measured by thermogravimetry at a nitrogen flow rate of 0.2 to 0.3 L per minute and a temperature increase rate of 10 C. per minute becomes zero, of from 100 C. to lower than 220 C. The flux has a content of the first solvent that is lower than a content of the second solvent. The flux does not include reducing agents for reduction removal of surface oxide films of solder, and does not include activators for improving reducibility.

Provided are a resin composition for soldering with not only improved wetting and spreading properties and but also excellent reliability and processability, a resin flux cored solder and a flux coated solder using this resin composition for soldering, and a liquid flux.

The resin composition for soldering includes 1 wt % or more and 40 wt % or less of: any of a dimer acid which is a reaction product of oleic acid and linoleic acid, a trimer acid which is a reaction product of oleic acid and linoleic acid, a hydrogenated dimer acid obtained by adding hydrogen to a dimer acid which is a reaction product of oleic acid and linoleic acid, or a hydrogenated trimer acid obtained by adding hydrogen to a trimer acid which is a reaction product of oleic acid and linoleic acid; or a total of two or more of a dimer acid which is a reaction product of oleic acid and linoleic acid, a trimer acid which is a reaction product of oleic acid and linoleic acid, a hydrogenated dimer acid obtained by adding hydrogen to a dimer acid which is a reaction product of oleic acid and linoleic acid, and a hydrogenated trimer acid obtained by adding hydrogen to a trimer acid which is a reaction product of oleic acid and linoleic acid, and 30 wt % or more and 99 wt % or less of a rosin.

It is an object of the present invention to provide flux and a solder material of which the activity hardly decreases even at a high temperature and which can also suppress the occurrence of migration. Flux containing an isocyanuric acid derivative containing two or more carboxyl groups and the like are provided.

A flux which imparts thixotropy, and which exhibits excellent printability, printing sagging-inhibiting ability, and heating sagging-inhibiting ability; and a solder paste which uses said flux. This flux includes a thixotropic agent, a rosin, an organic acid, and a solvent. The thixotropic agent includes a cyclic amide compound obtained by polycondensing a dicarboxylic acid and/or a tricarboxylic acid, and a diamine and/or a triamine into a cyclic shape; and an acyclic amide compound which is obtained by polycondensing a monocarboxylic acid, a dicarboxylic acid and/or a tricarboxylic acid into an acyclic shape. The flux includes at least 0.1 wt % but not more than 8.0 wt % of the cyclic amide compound, and at least 0.5 wt % but not more than 8.0 wt % of the acyclic amide compound. The total amount of the cyclic amide compound and the acyclic amide compound is at least 1.5 wt % but not more than 10.0 wt %.

Provided are a flux, resin flux cored solder and a flux coated pellet which are washable with water. Resin flux cored solder is composed of solder having a linear shape and a flux filled in a substantially central part (core) of the cross section of the solder. The flux contains an amine for salt formation and an organic acid for salt formation, in which the amount of the organic acid is within a range between 10 parts by mass or more and 645 parts by mass or less based on 100 parts by mass of the amine. The organic acid for salt formation is composed of at least one organic acid selected from the group consisting of malonic acid, succinic acid, glutaric acid, tartaric acid, malic acid, diglycolic acid, and citric acid.

There is provided the use of at least one ionic liquid as a soldering/brazing flux. There is also provided a method of soldering a metal comprising applying a solder/braze comprising a flux to a surface of the metal and heating said metal to a desired soldering/brazing temperature, wherein the soldering/brazing flux comprises one or more ionic liquids.