The principle of printing solder paste in SMT patch processing

Everyone knows that in the process of electronic processing SMT patch processing, it is necessary to use a printing machine to print the circuit board, so do you know the principle?

When the squeegee moves forward at a certain speed and angle, a certain pressure is generated on the solder paste, which pushes the solder paste to roll in front of the squeegee, and generates the pressure required to inject the solder paste into the mesh (ie, the opening of the template). The friction force causes the solder paste to shear at the junction of the squeegee and the stencil (template opening), and the shear force reduces the viscosity of the solder paste, thereby smoothly injecting into the mesh; when the squeegee leaves the template opening, the solder paste The viscosity quickly returns to its original state.

There are three key elements for the success of solder paste printing: solder paste rolling, filling, and demolding. 　　
During printing, only when the solder paste rolls in front of the squeegee, can the pressure to inject the solder paste into the opening be generated; the degree of the solder paste filling the opening of the template determines the amount of solder paste; the completeness of the demolding determines the missed printing of the solder paste and the solder paste pattern Completeness.