Step stencils: two thicknesses in one foil

Step-up and step-down, in plain words

A step-down stencil starts from a thicker base and is thinned locally over the fine-pitch area — this is the most common type. A step-up starts from a thinner base and is thickened locally over the parts that need more paste, such as a large connector or a ceramic BGA. Both are machined into the foil — usually on the squeegee side, so the foil can still sit flat on the board — and both can be combined on one stencil if a board calls for it.

When a board needs one

The typical triggers are:

• Fine-pitch SMD parts (0.4 mm pitch or below) sharing a board with large through-hole joints that demand extra paste.
• Connectors, coils or ceramic BGAs that need a locally higher paste volume than the rest of the board allows.
• Raised features such as press-fit pins, tall vias or clamps that need a pocket so the foil does not rock on the board.
• Pin-in-paste assemblies, where through-hole parts are soldered with paste printed through the stencil.

What changes in the design

Stepping is a real machining operation, so the design rules matter. Practical guidance from the IPC-7525 family and common shop practice: keep apertures clear of the step boundary — around 1.5–2 mm of clearance is the usual floor — and keep the step depth modest, with ΔT ≤ 0.5 × base thickness as the usual upper bound and 0.05 mm a common practical limit. Rectangular steps aligned with the squeegee travel are the most forgiving. Tell us where the thin and thick zones must be; we will check the clearances and come back if anything needs to move.

How we quote a step stencil

Because the price depends on your actual layout, a step stencil is quoted from the Gerber file rather than from a list. To quote it in the first reply, we need six things: step-up or step-down; how many stepped areas; the area of each; the base and stepped thicknesses; which side is machined; and the surface finish. Send the file with those answers and we will price it, usually within the same working day.

When a single thickness is enough

Not every mixed board needs stepping. If the finest pitch still prints cleanly at the thickness the large joints want — and our thickness guide helps you estimate that — a standard stencil is simpler, cheaper and more consistent to print. Stepping is the tool for boards where that compromise does not exist.