Shadow masks, also known as metal masks, are thin precision metal templates used for physical vapor deposition (PVD), evaporation and sputtering processes. They define the pattern of deposited thin films by blocking material in unrequired regions. Photochemical etching is widely adopted to fabricate thin metal shadow masks, delivering intricate micro patterns without mechanical stress or burrs.

How Shadow Masks Are Manufactured

1. Material Preparation: Clean ultra-thin metal foil to remove oil, oxide and surface contaminants to ensure photoresist adhesion.
2. Photoresist Lamination: Dry film photoresist is laminated on both sides of the metal substrate.
3. UV Exposure: Align CAD phototool and perform UV exposure. The resist on mask retaining areas is cured and hardened.
4. Development: Rinse away unexposed photoresist to expose the regions to be etched.
5. Chemical Etching: Double-sided controlled etching to form precise micro apertures. Sidewall profile is strictly controlled to minimize pattern deviation.
6. Stripping & Cleaning: Remove residual photoresist and fully clean the mask surface.
7. Metrology & Inspection: Optical dimensional inspection, flatness testing, followed by packaging.

Core Advantages

• Ultra-fine micro patterning: Achieve tiny, dense apertures with tight dimensional tolerance for thin film deposition.
• Burr-free & stress-free: No mechanical cutting, maintaining flatness of ultra-thin foil, no pattern distortion.
• Controllable sidewall geometry: Optimized etch profile reduces shadow effect during thin film evaporation.
• Design flexibility: Digital Gerber/CAD files only, fast prototyping, low cost for small and medium batches.
• Multiple material options: Stainless steel, invar, kovar, nickel and other low thermal expansion alloys available.
• Excellent reusability: Smooth surface and aperture walls allow repeated sputtering/evaporation cycles after cleaning.

Typical Application Fields

• OLED and Micro-OLED display pixel deposition shadow masks
• Semiconductor wafer thin film coating and metallization masking
• Sensor thin film patterning for pressure sensors and optical sensors
• Solar cell thin film deposition masks
• Medical device thin film coating, optical component metal masks

Design Considerations for Shadow Masks

• Flatness is critical; low thermal expansion alloy is preferred to avoid thermal deformation during high-temperature deposition.
• Minimum aperture size is limited by material thickness; follow aspect ratio rules for etching feasibility.
• Sidewall taper must be carefully designed to reduce pattern offset caused by shadow effect.
• Material selection: Invar/Kovar is recommended for high-temperature evaporation processes. Stainless steel is widely used for general sputtering applications.
• Particle control is essential; strict cleaning and packaging are required to avoid contamination of substrates.