Precision stainless steel photochemical etching (photo etching / PCM) is a subtractive manufacturing process for thin stainless steel sheets. Using photoresist masking and controlled ferric chloride based etchant, it selectively removes metal to form intricate microstructures. It overcomes common defects of stamping, laser cutting and CNC machining such as burrs, thermal oxidation, mechanical stress and material deformation. Commonly processed stainless steel grades include 304, 316L, 304H, 430 and other austenitic or ferritic stainless alloys.

Process Workflow for Stainless Steel Photochemical Etching

1. CAD Artwork & Phototool Production: Convert customer drawings into precision film phototool. No expensive hard metal molds required.
2. Surface Pretreatment: Degrease and thoroughly clean stainless steel sheet to remove oil, oxide and contaminants, ensuring stable photoresist adhesion. Stainless steel has a native chromium passivation film, which requires dedicated pre-treatment for uniform etching.
3. Dry Film Lamination: Laminating UV-sensitive photoresist on both sides of the stainless steel substrate.
4. UV Exposure & Alignment: Expose the coated sheet under UV light through the phototool, curing the resist on the protected part areas.
5. Developing: Rinse away unexposed photoresist, exposing stainless steel zones to be etched.
6. Controlled Chemical Etching: Circulating spray etching with temperature and pressure regulated etchant to dissolve exposed stainless steel. The process is precisely controlled to minimise undercut and guarantee consistent edge quality.
7. Photoresist Stripping: Strip off cured photoresist to reveal finished stainless steel parts.
8. Inspection & Post-treatment: Dimensional inspection, passivation, polishing, plating or laser marking according to custom requirements.

Core Advantages

1. Burr-free & stress-free edges: No mechanical cutting force or heat input. The native corrosion resistance and metallurgical properties of stainless steel are fully preserved, no microcracks or warpage.
2. Ultra-fine micro features: Manufacture micro holes, narrow slots, complex mesh patterns and sharp corners, ideal for thin stainless steel below 1.5mm.
3. Zero hard tooling cost: Only low-cost phototool films. Design revisions are fast and low-cost, perfect for prototype validation and low-to-medium volume orders.
4. Excellent batch consistency: Uniform etching across the whole sheet, stable dimensional repeatability for mass production.
5. Wide stainless steel grade compatibility: Process 304, 316L, 304H, 430 stainless steel for different corrosion resistance and mechanical requirements.

Typical Applications

• Filtration & fluid control: stainless steel filter meshes, sieve screens, micro-perforated plates
• Electronics & EMI shielding: stainless steel shielding cans, spring contacts, SMT stainless steel stencils
• Instrument & sensing: encoder discs, precision stainless steel shims, washers and spacers
• Medical devices: thin stainless steel surgical components, medical filter elements
• Consumer & industrial hardware: speaker grilles, etched metal nameplates, decorative panels

Design Considerations

• Material thickness: Best suited for 0.01mm ~1.5mm thin stainless steel sheets.
• Minimum feature rule: The smallest hole or slot width should be at least equal to sheet thickness for stable etching results.
• Tolerance: Dimensional tolerance correlates with material thickness; tolerance specification will be confirmed in DFM review.
• Material selection: 316L delivers superior corrosion resistance for medical and marine environments; 304 is cost-effective for general electronics.
• Post-treatment: Passivation is commonly applied after etching to restore stainless steel anti-corrosion performance.