Lead free reflow soldering is also called lead-free reflow furnace. It belongs to reflow soldering. Early reflow solders were all made of lead containing materials. With the development of environmental protection, people pay more and more attention to lead-free technology. The change in material, especially in solder, is the largest. In terms of process, the welding process has the greatest impact. This is mainly caused by the characteristics of the solder alloy and the different fluxes.

For the sake of environmental protection, lead will be strictly restricted in the 21st century. Although the lead used in the electronic industry is very small, less than 1% of the total consumption, it is also prohibited and will be phased out in the next few years. Reliable and economical lead-free solders are being developed. At present, many substitutes developed generally have a melting point temperature of about 40C higher than that of tin lead alloy, which means that reflow soldering must be carried out at a higher temperature. Nitrogen protection can partially eliminate oxidation and damage to PCB due to temperature increase. However, the industry must probably go through this painful learning period to solve the problems encountered. The industry has applied the process as soon as possible, and the time has been saved. Many furnaces used now are designed to have a high operating temperature of not more than 3000 C. for lead-free solder or non eutectic solder (used for BGA, double-sided plates, etc.), higher furnace temperature is required, These new processes usually require the temperature in the reflux zone to reach 3500c-4000c. The design of the furnace must be changed to meet such requirements. The heat sensitive parts in the machine must be modified, or measures must be taken to prevent heat transfer to these parts.