Solder paste printer is commonly called stencil printer ，smd printing machine.Solder paste printing is a key part in the SMT (Surface Mount Technology) process. The solder paste printing process represents the first assembly process that consists of applying the solder paste onto the PCB.Since the solder paste is a mixture of powder and flux, it is fluid during the printing process. Viscosity is a major indicator of the form of solder paste fluids. If it has low viscosity, it flows easily for filling and collapses. If it has high viscosity, it is easy to roll, peel and form. The viscosity requirement is also different at different stages of solder paste printing. SMT has a flexible requirement of viscosity but fortunately viscosity itself is a variable that is easy to change. This requirement of varying viscosity places a higher dependence on the solder paste printing process and the printer’s parameter settings.