How to Choose Photochemical Etching
Photochemical etching (also known as chemical etching or photo etching) is a precision subtractive manufacturing process that uses photoresist and chemical etchant to fabricate complex thin metal components without mechanical force. It is widely used for filter meshes, encoder discs, shims, bipolar plates and custom thin sheet metal parts. Knowing how to select photochemical etching helps you decide if it fits your project and pick the right specifications.
1. Check Material Compatibility
Photochemical etching works best with metals that can be uniformly etched. Common options include stainless steel, copper, brass, nickel, titanium, kovar and aluminium.
- Thin stainless steel: most popular for filter mesh, shielding and precision shims
- Copper / brass: high conductivity, ideal for electrical and thermal components
- Titanium: excellent corrosion resistance for medical and harsh-environment parts Some hard or alloyed metals are not suitable or will require longer etching time and higher cost. Confirm material feasibility with your manufacturer at the beginning.
2. Evaluate Metal Thickness & Feature Size
The core advantage of photo etching is handling ultra-thin metal foils. Typical thickness ranges from 0.01 mm up to around 1.5 mm. A basic rule: the minimum hole or line width is roughly equal to the material thickness. For example, 0.05 mm thick metal can produce ~0.05 mm micro holes. If your design requires features smaller than material thickness, photo etching may not be the best fit.
3. Dimensional Tolerance Requirements
Tolerance is closely related to sheet thickness. Thinner material achieves tighter tolerance. For ultra-thin foils, tolerances can reach ±0.005 mm, while thicker plates will have looser allowable deviation. If your part needs ultra-high precision with complex micro patterns, photochemical etching often outperforms laser cutting, especially for mass production. For large simple cuts, laser cutting may be more economical.
4. Part Geometry & Complexity
Photochemical etching has nearly no extra cost for intricate patterns, sharp corners, dense micro holes or asymmetric outlines. Unlike stamping, there is no tool wear. This makes it perfect for parts with many fine apertures such as filter mesh and encoder discs. However, the process is 2D planar forming. Deep 3D bending or raised structures cannot be achieved by etching alone; secondary forming operations will be required.
5. Surface Quality & Post-treatment
Etched parts have burr-free edges, which is a major benefit compared with laser or mechanical cutting. No additional deburring step is needed for most applications. Available post-processing: passivation, polishing, plating, coating. Select surface treatments according to requirements of corrosion resistance, conductivity or biocompatibility for medical components.
6. Quantity, Lead Time & Cost
Photochemical etching uses digital photo tooling. No hard stamping mold is required. Tooling cost is low and turnaround is fast, which suits prototyping and small batches. For very high-volume simple thick parts, stamping may become more cost-effective. Compare total project cost including artwork preparation, material, etching, inspection and post-processing, not only the raw part price.
7. Supplier Capability Verification
Verify whether the manufacturer can handle your target thickness and micro feature size. Request sample capability reports, tolerance data and material certificates. Confirm their inspection equipment for micro dimensions and quality control system.
Summary
Choose photochemical etching when you need burr-free complex thin metal parts, micro holes or intricate patterns. Match your metal material, thickness, feature size and tolerance with process limits. For flat thin components with fine geometry, photo etching offers great advantages in lead time and repeatability.
