Photochemical etching, also widely known as chemical photo etching, is a non-contact subtractive metal machining technology. It selectively removes material from thin metal foils using photoresist masking and controlled chemical etchants to form intricate two-dimensional geometries. Unlike traditional CNC machining, stamping or laser cutting, this subtractive method does not apply mechanical force to the workpiece, preserving the original material properties of ultra-thin and delicate metal sheets.

How Photochemical Etching Works

1. Surface Preparation: Metal sheets are thoroughly cleaned to eliminate grease, oxidation and surface contaminants, ensuring strong adhesion of photoresist film.
2. Photoresist Lamination: Dry photoresist is laminated onto both sides of the cleaned metal substrate.
3. UV Exposure: The digital artwork film is aligned with the metal sheet and exposed under ultraviolet light, curing the photoresist in the designed pattern areas.
4. Development: Uncured photoresist is washed away, exposing the metal areas scheduled for etching.
5. Chemical Etching: Etchant solution dissolves the exposed metal uniformly from top and bottom surfaces to form the required contours and microstructures.
6. Resist Stripping: Remaining cured photoresist is stripped off after etching is completed.
7. Quality Inspection & Post-processing: Dimensional verification, surface cleaning, finishing and packaging.

Core Advantages of Photochemical Etching

• Burr-free edges: Non-contact material removal eliminates burrs, removing the need for secondary deburring operations.
• No hard tooling charges: Designs are controlled by digital artwork. Prototype iterations and small batch orders avoid expensive metal die costs.
• Stress-free components: No mechanical impact or compression, so thin metal parts stay flat without warping or distortion.
• Excellent precision for micro features: Capable of creating micro holes, fine slots and complex patterns on metal foils as thin as 0.02 mm.
• Equal cost for complex geometries: Simple and intricate patterns share nearly identical processing cost, no premium for complex outlines.
• Broad material compatibility: Suitable for stainless steel, copper, nickel, brass, titanium, nitinol, kovar, molybdenum and other specialty alloys.

Typical Applications

• Semiconductor industry: lead frames, packaging stencils, electromagnetic shielding components
• New energy: fuel cell bipolar plates, vapor chamber microstructures, battery contact shims
• Medical devices: nitinol minimally invasive components, micro filters, precision surgical shims
• Consumer electronics: EMI/RFI shielding cans, speaker grilles, rotary encoder discs
• Industrial filtration & testing: custom sieves, micro porous filter meshes, metal screen panels

Design Considerations

• The minimum feature size is generally limited by the base metal thickness.
• Hole diameter and trace width must follow photochemical etching design rules for stable tolerance control.
• Different metal alloys have different etching rates, which will affect the final dimensional accuracy.
• Design modifications can be completed quickly by updating digital artwork, without remaking expensive molds.