PURPOSE: To prevent adhesion of flux onto a board by discharging excess atomized flux upward through a discharger and disposing a filter for adsorbing the atomized flux falling onto the board above a conveyor.

CONSTITUTION: Flux is atomized through a spray nozzle 12 and then sprayed, along with compressed air, through an opening to be applied uniformly onto the bottom face of a printed board 15 being conveyed on a conveyor 11. Residual atomized flux is carried on the air flow produced through a discharger 13 in the direction of an arrow D and then sucked through an adsorption filter 14 into a hood 34. In this regard, suction force is insufficient at the upper part of the printed board 15 and large particles in the flux fall gravitationally as shown by an arrow F. The falling flux is captured by the adsorption filter 14 and prevented from adhering to the printed board 15.