Stepped stencils are an effective solution for managing solder paste volume across components with varying pad sizes. Whether you’re working with fine-pitch BGAs, tiny 01005s, or large thermal pads, stepped stencils help ensure the right amount of solder paste is deposited exactly where it’s needed.
Designing a stepped stencil requires clear and complete communication with your supplier. Providing the right information up front minimizes delays, reduces revision cycles, and helps deliver consistent print quality.
What is a Stepped Stencil?
Stepped stencils include localised thickness variations, either raised (step-up) or recessed (step-down) regions designed to control paste volume. These steps can be created through several fabrication methods, including:
- Milled Steps: Material is precisely machined away to create step-downs with the remaining material left for step-ups. This method provides excellent surface finish, sharp transitions, and highly accurate depth control, ideal for high-density or fine-pitch layouts.
- Laser-Welded Steps: Layers of stencil foil are laser-welded to add material where step-ups are needed. This technique is useful for creating distinct height differences, particularly when paste volume needs to be increased.
- Chemically Etched Steps: A subtractive process where chemicals are used to remove material and form recessed areas.
Specification Checklist: What Your Supplier Needs
Regardless of the step fabrication method, a clear specification will help your supplier manufacture the stencil accurately on the first attempt. Include the following details:
1. Base Foil Thickness
- Specify the original foil thickness before any profiling.
- Minimum base foil: typically 0.05 mm or per supplier capability.
2. Step Locations and Dimensions
- Supply a CAD file indicating:
- Step-up or step-down regions
- X/Y dimensions and positions
- Step depths or thicknesses
- Supply a CAD file indicating:
3. Transition Zone Requirements
- Define whether step transitions should be sharp, ramped, or blended.
- Include any tolerance requirements for the transition areas.
4. Mounting Requirements
- Specify if the stencil should be:
- Supplied as a loose foil
- Pre-mounted in a frame
- Specify if the stencil should be:
5. Foil Material and Finish
- Identify the stainless steel grade and surface finish required.
- A smooth, consistent finish supports reliable paste release and print quality.
How Datum Supports Advanced Stencil Requirements
Datum provides advanced, ready-to-cut stainless steel foils designed for stepped stencil fabrication. Our micro-profiling technology, a form of precision milling, creates recessed and elevated areas directly in the foil without the need for adhesive layers or post-processing.
This enables:
- Superior surface finish
- Highly accurate step placement and depth
- Smooth or sharp transitions as needed
Our foils are ideal for:
- Multi-level SMT stencils
- 3D epoxy or reservoir stencils
- 2-print processes
- Custom stepped designs for high-reliability applications
Dual sided steps
How Datum Supports Advanced Stencil Requirements
A well-specified stepped stencil is critical to solder paste control and assembly performance. Whether your application requires milled, welded, or etched steps, partnering with a knowledgeable supplier ensures your design is manufacturable and effective.
Need support specifying your next stencil?
Reach out to us and we’ll work with you to turn your ideas into high-performance, production-ready stencils.
