Abstract: The no-clean soldering fluxes used presently contained a high concentration of organic solvents which would generally turn into volatile organic compounds (VOC).VOC are one of main pollutant sources that contaminate air,and the VOC could cause much harm to environment and human health.Consequently, a new type of no-clean flux which was VOC-free and water-based was developed.Many performance tests had been carried out using Sn-3.8Ag-0.7Cu lead-free solder.The results show that the flux has measured up to the industry standards.The appearance,stability,viscosity and content of halide are up to the standard.The flux works well with Sn-3.8Ag-0.7Cu lead-free solder and the rate of spread is 80.1%.It has little residues after soldering and the residues have no corrosion.The surface insulation resistance (SIR) test was carried out at the condition of ambient temperature 85℃,relative humidity 85% in the moist-heat chamber.After wave soldering with this new no-clean flux,and the testing panels of comb type circuits laid in the chamber for 24 hours,96 hours and 168 hours respectively,SIR values were measured at the room temperature.The mini- mum value of testing panels was 3.8×10¹¹Ω.This new no-clean flux has fulfilled the reliability requirements of the standards of no-clean soldering flux