PURPOSE: To allow the utilization of the solvent which has high volatility and rapidly volatiles and is removed after the flux is applied on a printed substrate so as to improve the workability of soldering by using fluorinated alcohol of the general formula as solvent in the liquid flux for soldering printed board.

CONSTITUTION: Dimethylamine hydrochloride, tartaric acid, polyethylene glycol 200, 5 fluoro alcohol, pentafluorol '5FPQ' (DAIKIN) are mixed and stirred to manufacture the liquid flux as the ordinary method. The dimethylamine hydrochloride and the tartaric acid are activator and the polyethylene glycol 200 is resin content and 5FP is non-combustible fluoro alcohol solvent of chemical structure CF3CF2CH2OH. As these solvent fluorinated alcohol shown with the general formula ClFnHmOH (in the formula, l=integer of 1-5, 2l+1=n+m), is used.