No-clean liquid soldering flux is made of high-tech multi-element formula and used in no-clean technique of wave soldering and dip soldering of assembled by high-reliability electronic products PCB. It is of reliable welding spot, nice appearance, cleanness, high insulation resistance after welding, and low ion pollution. The soldering flux has no halogen and only 2% solid content. After welding, the PCB plate reaches SJFF11273-2002 electronic industrial standard and American MIL-P-28809 standard