Because the different components need different thickness (volume) of Tin, the thickness for different SMT area should be various from each other in the same stencil, then assembly factory need step-down or step-up artwork for their stencils.
Step-Down Stencil
Reducing the thickness of certain area in stencil to lessen the Tin volume of specified components in soldering process, and no affection of stencil cleaning. This step-down stencil will be helpful to solve printing defect for special bump (such as with label) of PCB.
Step-Up Stencil
Increasing the thickness of certain area in stencil to add Tin volume for designed components in population process, and it is especially suitable for through hole reflow solder artwork (such as plug-in, Dip components reflow solder)
Step-Down & Up Stencil
To reduce and increase the thickness of stencil for certain area, on the same stencil. It means there’re three different thicknesses in the same stencil, to meet different requirements of Tin volume
