A step stencil changes local thickness to serve different deposit requirements. Approval should include the transition region and neighboring apertures, not only the nominal thickness of each zone. A workable large-component deposit can coexist with an unqualified print condition nearby.
Review the transition on the stencil drawing
Alpha’s precision-milled stencil overview describes multi-level construction and flexibility in the transition and keep-out region. The specific design should be agreed with the stencil supplier for the actual aperture pattern and print process.
Overlay the thickness zones with the board’s aperture pattern. Identify which face carries each step and how the transition relates to the intended squeegee direction. Keep those details visible in the reviewed manufacturing drawing.
Mark the features requiring evidence
| Feature | Review focus |
|---|---|
| Thicker region | Target deposit and local release |
| Thinner region | Fine-feature printing requirement |
| Transition | Supplier-approved geometry and placement |
| Adjacent apertures | Effect of proximity and print direction |
| Board contact | Supported, represented printing arrangement |
Do not assign a universal transition clearance from an unrelated stencil. Ask the supplier to review the actual process and construction, including any limitation on aperture placement near the step.
Design the print trial around the boundary
Select inspection locations on both sides of the transition and in unaffected regions. Compare deposit shape, volume and consistency using the approved inspection method. Retain individual locations so a local issue is not hidden by a board-wide summary.
Include both print directions if they are used in production. Record the blade, paste, support and cleaning state. A trial using only the most favorable direction would not represent an alternating-stroke process.
For example, if one nearby component shows unstable deposits while the larger target component improves, assess the local transition and aperture design together. Raising pressure globally may trade one local problem for another.
Include a drawing reference for the transition geometry in the tooling order. A purchase description listing only two foil thicknesses leaves the supplier without the approved boundary placement and makes received-tool inspection less conclusive.
Release the whole tooling configuration
Retain the approved drawing, stencil construction and trial evidence under the same revision. When the board layout changes near a transition, review the stencil even if the large component remains unchanged.
Inspect received tooling against the approved design and confirm that its identification distinguishes it from earlier thickness variants. Similar-looking stencils can be difficult to distinguish on the line without a clear configuration record.
The squeegee mapping guide helps separate blade-related variation, and separation-speed review evaluates the release stage of printing.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist