PURPOSE: To provide a substantial matting effect and excellent cleaning property to the titled compsn. by compounding a specific ratio of a matting additive with a base flux having a matting effect.

CONSTITUTION: The additive having the matting effect on a resist surface as well is added into the base flux having the intermediate material effect on a soldered surface of a printed wiring board, etc., at 5W100pts.wt. per 100pts.wt. resin component of the flux. Pulverized PP powder, HDPE, or montanate wax, etc., are selected for the additive. The substantial matting effect is obtd. over the entire surface of the soldered surface and resist surface by such flux compsn. The excellent effect is also obtd. for the cleaning property.