Prototype Metal Stencil Printing

This video demonstrates the technique for using a metal SMT stencil for small production runs or prototyping. The board fixtures or “L” brackets are placed such that the board to be printed can be “snuggly” fit. Once these holders are secured the board can be placed in to the holders and the metal stencil aligned over the top. When the apertures line up with the pads secure the metal stencil in to position using painter’s tape. This will secure the stencil and maintain alignment while the tape acts like a “hinge” as the stencil is lifted on to and off of subsequent PCBs. After the solder paste comes up to temperature for 20 minutes mix the solder paste and scoop some out using a plastic tool. Now using the supplied squeegee, which is slightly wider than the image area is used to roll the solder paste through the apertures of the stencil. The squeegee should be about 45 degrees with respect to the suface of the stencil and consistent pressure needs to be applied as you travel the entire print area. Lift up the stencil, carefully remove the PCB and inspect the print area. The SMT prototype stencil printing process while easy, takes patience and technique to maintain consistent results over several boards.