Stepped Stencils

The combination of very different sized components on a printed circuit board represents a special challenge to the stencil paste printer. While high density chip housings with small pitch need small solder paste quantities for the avoidance of short-circuits and therefore require thin stencils, large components need more solder paste for a safe connection and thus thicker stencils.
 
Stepped stencils can help in such a situation, because there are different thicknesses implemented over the surface of the stencil.
 
For the production of stepped stencils three different procedures are used:

1. On the stencil sheet metal the areas which require a different material thickness are cut out.  Then the identical areas of thinner/thicker material are cut from another sheet and then inserted and welded with the laser.
2. Areas of the stencil which are to be thinner than the total sheet are etched thinner before laser cutting.
3. Areas of the stencil which are to be thicker than the total sheet are plated thicker with nickel before laser cutting.