Abstract: An application device according to an embodiment includes a liquid nozzle part, an air nozzle part, and an ejection controlling unit. The liquid nozzle part ejects liquid to be applied to an electronic component mounted on a substrate. The air nozzle part ejects air toward the substrate. The air nozzle is concentrically arranged with respect to the liquid nozzle part. The ejection controlling unit ejects the air from the air nozzle part at a timing in synchronization with an ejection timing of the liquid to be applied by the liquid nozzle part.

Abstract: A solder paste according to an aspect of the invention includes, within a flux, an activator that has a dibasic acid with a molecular weight of 250 or less, a monobasic acid with a molecular weight of 150 or greater and 300 or less, and a dibasic acid with a molecular weight of 300 or greater and 600 or less; and at least one resin additive selected from the group consisting of high-density polyethylenes and polypropylenes. The solder paste has the resin additive in an amount of 4% by weight or greater and 12% by weight or less when the total amount of the flux is taken as 100% by weight, and has a viscosity of 400 Pa·s or greater at 80° C.

Abstract: A flux for a solder paste according to an aspect of the invention includes an acrylic resin obtained by radically copolymerizing a (meth)acrylate having a C6-C15 alkyl group and a (meth)acrylate other than the above-mentioned (meth)acrylate; and rosins. The weight ratio of the acrylic resin is 0.5 or greater and 1.2 or less when the weight of the rosins is taken as 1, and the flux for a solder paste is fluidized by application of a shear force of 10 Pa or greater and 150 Pa or less.