Lead-free solder bar is less harmful than leaded solder wire. The smoke of lead-free solder wire in welding is caused by the gasification of smoke caused by the welding aid outside the solder wire and the low temperature electric soldering iron. The outside of the solder wire auxiliary contains rosin and chemical raw materials, and the temporary inhalation of the bad factors caused by the human admixture will keep the ventilation good. The rosin in the non-feed solder wire is mainly composed of 80% resin containing rosin anhydride and balsam acid by about 5-6%, volatile oil and micro-bitter substances. At the low temperature of 250 degrees at the time of solder wire welding, there are oxides that can be decomposed into carbon dihydride. Other harmful gases, and lipid and volatile gas of the rosin itself, the county's, may cause slight consolation to the eyes, the conditional system of enterprises can be mounted to the smoke pollution can change the west manual solder wire welding workers task environment, eliminate often occur in the absence of salt solder wire welding to some sweet substances and smoke, such as hexanal, rosin acid, different atmosphere acid salt, Carbon per compound, these aromatic substances are seriously damaging human health, leading to the appearance of many occupational diseases, such as lung cancer, asthma, wet sores, bronchitis, skin allergies, respiratory tract infections and so on.