Vacuum soldering is a special form of convection soldering and is used wherever flawless soldering is required. Three-dimensional imperfections (voids, pores) can occur wherever flux and solvents escape from the soldered joint and cannot completely leave the soldered joint. Convection soldering is supplemented here by an extended process step, vacuum. The purpose of vacuum soldering is to improve the final quality of the solder joint and results in application improvements over standard reflow soldering.
With the help of the vacuum, process residues can escape in the preheating phase and in the liquidus phase of the solder and lead to a reduction or absence of defects in the soldered joint.