Minimum Feature Size & Tolerance Limits for Stainless Steel Shadow Masks

Minimum Feature Size & Tolerance Limits for Stainless Steel Shadow Masks

Stainless steel shadow masks are widely used in thin-film deposition systems, including PVD, CVD, and sputtering, due to their durability, low cost, and ease of fabrication.
However, stainless steel has practical resolution limits, and understanding these constraints is essential for designing patterns that are manufacturable and functional.

This page explains the smallest achievable feature size, recommended tolerances, and common design limitations backed by real fabrication experience from research labs and engineering teams.

What is the Minimum Feature Size?

For stainless steel shadow masks manufactured by laser cutting:

⭐ Realistic minimum feature size: 30–40 µm

⭐ Best accuracy achieved at: ≥50 µm

⭐ Tolerance range: ±5–10 µm (depending on thickness)

Ultra-fine features below 30 µm typically require:

  • Nickel electroforming
  • Silicon shadow masks
  • Lithographic methods

Why Stainless Steel Cannot Support Extremely Small Features

Stainless steel has limitations due to:

1. Laser beam spot size

Industrial laser cutters typically have:
~20–30 µm spot diameter → impossible to cut a perfectly crisp 10 µm opening.

2. Heat-affected zone (HAZ)

Edges melt slightly → causes sidewall taper + micro-burrs.

3. Material thickness

The thicker the steel, the harder to maintain clean micro-scale edges.

Recommended Feature Size vs Thickness Chart

Stainless Thickness Min Feature Size Recommended Notes
0.05 mm 25–35 µm ≥35 µm best for micro structures
0.10 mm 30–40 µm ≥40–50 µm most stable for R&D
0.15 mm 40–60 µm ≥60 µm balance between rigidity & accuracy
0.20 mm 60–100 µm ≥80 µm not suitable for micro patterns
0.30–0.50 mm >100 µm ≥150 µm macro-patterns only

Typical Manufacturing Tolerances

Laser-cut stainless steel masks normally achieve:

Parameter Typical Tolerance
X/Y feature accuracy ±5–10 µm
Edge roughness 3–10 µm
Sidewall taper 5–15 µm depending on thickness
Positional accuracy ±10–20 µm across 50 mm span


Why Designs Below 30 µm Usually Fail

1. Laser cannot cut smaller than its spot size

If spot = 25 µm → You cannot make a 15 µm hole.

2. Material melting causes taper

Narrow openings collapse.

3. Burr formation

Micro-scale bridges break during cutting.

4. Stainless steel stiffness

Small openings deform when heat accumulates.

Recommended Alternatives for Sub-20 µm Features

For university nanofabrication or micro-pattern lithography:

Method Advantage Limit
Electroformed nickel mask 10–20 µm features fragile
Silicon shadow mask (DRIE) 2–10 µm expensive
Photo-lithography sub-micron requires cleanroom


Frequently Asked Questions

Q1. What is the smallest feature size stainless steel can support?

30–40 µm for reliable production.

Q2. Does thinner stainless improve resolution?

Yes — 0.05–0.1 mm steel yields the best micro features.

Q3. Why are sub-20 µm features impossible?

Laser spot size + HAZ limitations.

Q4. What tolerance should I expect?

±5–10 µm typical.

Q5. Which material is best for sub-20 µm?

Electroformed nickel or silicon masks.

 

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