Learn how to solder SMD in this detailed surface mount soldering guide.
SMD soldering and desoldering are almost no different from through-hole soldering and desoldering.
SMD desoldering is usually done using a hot air blower, while soldering can be done using a soldering iron and solder wire or solder paste or solder balls (BGA) and SMD hot air blower/rework station.
SMD welding process type
All SMD welding processes have technical problems, and there are ways to solve these problems. Due to the higher yield and lower operating cost of IR welding, where convection is dominant, it has developed into the preferred process for convection welding.
Vapor phase welding will not disappear, but will continue to be used for special occasions. For some professional jobs, other reflow soldering processes are used, such as laser and hot rod resistance welding. The purpose of these welding processes is not to replace gas phase or infrared, but to supplement them. The final process used should be selected based on the specific requirements of the intended application, solder defect results and total cost.
SMD welding process for mass production
For mass production in the factory, SMD welding is performed using SMT machines. The main machine of this type is the reflow oven
Reflow oven
The most widely used reflow soldering process in electronic products is:
Vapor phase; and infrared.
Manual SMD welding process

Use soldering iron or soldering station, hot air SMD rework station, solder wire and solder paste for manual SMD soldering. This process is mainly used for repair/rework.
Selection of welding process
Since the electronics industry will maintain a mixed PCB assembly mode, using SMD electronic components and through-hole electronic components to assemble different types of PCBs, the use of through-hole components will continue in the foreseeable future. For through-hole active and passive electronic components, there is no more cost-effective method than wave soldering. For some applications, solder paste reflow is also preferred.
Due to the widespread use of low solids or no-clean fluxes, nitrogen is commonly used in wave soldering and reflow soldering processes. However, nitrogen should not be expected to be a panacea for solder defects. It will only affect the welding output to a certain extent. Nitrogen does not solve problems related to other parameters, such as design, flux activity, solder paste, print quality, and solder profile.
The choice of soldering process depends on the mix of electronic components to be soldered. Various welding processes will complement each other rather than replace them. Even manual welding will not disappear completely.