A rosin-modified product being a reactant of a rosin or a rosin derivative and an alkanolamine represented by a following Formula (1)

NH.sub.3-n—(R—OH).sub.n(n≤3); or  (1) being produced by a reaction of a rosin or a rosin derivative, an organic acid and an alkanolamine.

Provided is a flux that contains at least one of an amine compound containing at least one acetylated amino group and an amino acid compound containing at least one acetylated amino group, as an activator.

Provided is a flux capable of obtaining predetermined rheological characteristics both at room temperature and under a thermal history that is assumed for soldering and capable of suppressing the amount of a residue after soldering to realize a low residue. The flux contains a first alcohol compound that has two or more OH groups and has a melting point of lower than 25 C. and a second alcohol compound that has two or more OH groups and has a melting point of higher than 25 C., the first alcohol compound is glycerin, the second alcohol compound is 2,5-dimethylhexane-2,5-diol, the flux has a viscosity of 10 Pa.Math.s or more and 50 Pa.Math.s or less at 25 C. and has a viscosity of more than 0 Pa.Math.s and 1 Pa.Math.s or less at 100 C., and, in a case where 10 mg of the flux is heated up to 25 C. to 250 C. under a N.sub.2 atmosphere at a temperature rise rate of 10 C./min, the weight of the flux after heating is 15% or less of the weight of the flux before heating.

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.

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.

An object of the present invention is to provide a flux which does not precipitate a crystal and can improve solder wettability. A flux comprising 0.4 to 10.0 mass % of ditolylguanidine and 1.0 to 10.0 mass % of an organic acid, and not comprising diphenylguanidine as an amine compound.

Provided are a Cu column, a Cu core column, a solder joint, and a through-silicon via, which have the low Vickers hardness and the small arithmetic mean roughness. For the Cu column 1 according to the present invention, its purity is equal to or higher than 99.9% and equal to or lower than 99.995%, its arithmetic mean roughness is equal to or less than 0.3 m, and its Vickers hardness is equal to or higher than 20 HV and equal to or less than 60 HV. Since the Cu column 1 is not melted at a melting temperature in the soldering and a definite stand-off height (a space between the substrates) can be maintained, it is preferably applied to the three dimensional mounting or the pitch narrowing mounting.

The disclosure describes techniques for eliminating or reducing non-wet open (NWO) defect formation by using a low activity flux to prevent a solder paste from sticking to ball grid array (BGA) solder balls during reflow soldering. The low activity flux may be configured such that: i) it creates a barrier that prevents the solder paste from sticking to the solder balls of the BGA; and ii) it does not impede the formation of solder joints during reflow. In implementations, a solid coating of the low activity flux may be formed over balls of the BGA, and the BGA may then be bonded to a PCB during reflow. In implementations, the balls of a BGA may be dipped in a low-activity creamy or liquid flux prior to reflow. In some implementations, the flux may applied on a solder paste printed on pads of the PCB, followed by placement of a BGA.