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 flux for use in soldering comprises a first constituent and one or more secondary constituents that is selected from solvents, thickeners, and/or metal oxide reducing agents. The flux has a temperature profile in which the flux is in a non-flowable inactive state at temperatures at and below a maximum storage temperature that is above about 27 C., a liquid active state at an activation temperature, and a flowable inactive state in a deposition temperature range above the maximum storage temperature and below the activation temperature. A solder material comprises solder particles dispersed in the flux.