One of the most important parts of the surface mount assembly process is the application of solder paste to the printed circuit board (PCB). The aim of this process is to accurately deposit the correct amount of solder paste onto each of the pads to be soldered. This is achieved by screen-printing the solder paste through a stencil or foil but also can be applied by jet printing. It is widely believed that this part of the process, if not controlled correctly, accounts for the majority of assembly defects.

The most common method of applying solder paste to a PCB using a stencil printer is squeegee blade printing – see images below. The squeegees are the tools used to apply the necessary force required to move the solder paste across the stencil and on to the PCB. They are usually made from metal but can also be made from polyurethane.