CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2018/015366 filed on Apr. 12, 2018, which claims the benefit of priority from Japanese Patent Application No. 2017-081369, filed on Apr. 17, 2017. The entire disclosures of both of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a flux composition, a solder paste composition, and a solder joint.

BACKGROUND ART

For joining and assembling of electronic components together with a substrate of an electronic equipment, soldering using a solder paste composition is most advantageous in terms of cost and reliability, and is most commonly conducted. A solder paste composition is a mixture obtained by kneading a solder powder and a flux composition which is composed of other components than solder powder such as rosin, activator, thixotropic agent, and solvent to form a paste.

When applying a solder paste composition to a substrate, scattering of flux on the substrate leads to pollution of neighboring electronic components, and thus it is required to suppress scattering of flux.

In addition, applying of a solder paste composition to a substrate is conducted by, for example, screen printing using a metal mask. Thus, in order to secure printability of a solder paste composition, a solder paste composition is required to have suitable viscosity. However, particular types of solder paste compositions have inferior storage stability, and in some cases the viscosity of the solder paste compositions could increase over time.

As the conventional solder paste compositions, for example, a solder paste composition containing a lead-free solder powder, a rosin-based resin, an activator, a solvent, and an anti-oxidant consisting of a hindered phenol-based compound having a molecular weight of at least 500 has been proposed (PTL 1).

However, the applicants investigated the solder paste composition described in PTL 1, and as a result, it was found that scattering of flux occurred.

Therefore, a flux composition and a solder paste composition are desired in which scattering of flux is suppressed.

CITATION LIST

Patent Literature

PTL 1: Japanese Patent No. 4447798

SUMMARY OF INVENTION

Technical Problem

The object of the present invention is to provide a solder paste composition and a flux composition contained therein in which scattering of flux is suppressed.

Furthermore, the object of the present invention is also to provide a solder paste composition and a flux composition contained therein in which, in addition to scattering of flux, a viscosity increase over time is also suppressed.

Solution to Problem

The present inventors engaged in a diligent study to achieve the above object, and consequently completed the present invention by discovering that the flux composition and the solder paste composition comprising a particular anti-scattering agent could suppress scattering of flux when the solder paste composition was used and a viscosity increase over time. Specific embodiments of the present invention are as follows.

[1]

A flux composition comprising an anti-scattering agent represented by formula (1) below,


wherein

Z is optionally substituted alkylene,

R1and R2are each independently optionally substituted alkyl, optionally substituted aralkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted cycloalkyl, or optionally substituted heterocycloalkyl, and

R3and R4are each independently optionally substituted alkyl.

[2]

The flux composition according to [1], wherein

Z is C1-C6alkylene,

R1and R2are each independently C1-C6alkyl or alkylcycloalkyl, and

R3and R4are each independently C1-C6alkyl.

[3]

The flux composition according to [1] or [2], wherein the anti-scattering agent is 2,2′-methylenebis[6-(1-methylcyclohexyl)-p-cresol].

[4]

The flux composition according to any one of [1] to [3], wherein the percentage by weight of the anti-scattering agent is 0.5 to 10 wt. %.

[5]

The flux composition according to any one of [1] to [4], further comprising a rosin, an activator, a thixotropic agent, and a solvent.

[6]

A solder paste composition comprising the flux composition according to any one of [1] to [5] and a solder powder.

[7]

A solder joint formed by the solder paste composition according to [6].

Advantageous Effects of Invention

The flux composition and the solder paste composition of the present invention can suppress scattering of flux.

Furthermore, the flux composition and the solder paste composition of the present invention can suppress scattering of flux and can suppress a viscosity increase over time.

