Stress-free etching, commonly known as photochemical etching / photo etching, is a non-contact subtractive manufacturing process. It selectively dissolves unwanted metal via chemical reaction rather than mechanical shearing, cutting or thermal melting. No compressive, tensile or impact force is applied to the workpiece, and there is no localized heating. Therefore, no residual stress or work hardening is introduced into the finished metal parts. The original material microstructure and mechanical properties are fully preserved.

Why Traditional Processes Create Residual Stress

Stamping & punching: Shear force deforms metal lattices, leaving residual stress and work-hardened zones along cut edges. Thin foils tend to warp after cutting.

CNC machining: Cutting force creates stress concentration at feature edges, risking part bending after machining.

Laser cutting: Rapid heating and cooling generate thermal stress, causing distortion and material brittleness near cut lines.

Stress-Free Etching Step-by-Step Workflow

DFM Design Review: Optimize CAD drawings to compensate for isotropic undercut of wet etching.

Surface Preparation: Degrease and clean metal sheets to ensure consistent photoresist adhesion.

Dry Film Lamination: Laminate light-sensitive photoresist on both sides of the substrate.

UV Exposure & Development: Transfer the target pattern onto photoresist, wash away unprotected resist to expose bare metal.

Dual-sided Chemical Spraying Etching: Etchant dissolves exposed metal atom by atom simultaneously from top and bottom. No mechanical contact occurs.

Resist Stripping: Remove remaining photoresist mask.

Rinsing & Inspection: Fully clean residual chemicals and inspect flatness, dimension and material integrity.

Core Advantages of Stress-Free Etching

Zero residual stress & no work hardening The metal grain structure remains unchanged. Parts will not deform or shift dimensions after processing. This is critical for spring components, shims and thin foils that require stable elastic performance.

Excellent flatness for ultra-thin materials (0.02 mm ~ 0.5 mm) Thin stainless steel, nickel, titanium foils stay flat after etching, without warpage or curling.

Burr-free smooth edges Molecular-level material removal delivers clean edges without micro-tears, eliminating secondary deburring.

No heat-affected zone No thermal stress induced; suitable for heat-sensitive metal alloys.

Design flexibility Supports dense micro-holes, fine slots and complex mesh structures. Multiple part layouts can be arranged on one panel.

No hard tooling cost Only digital artwork is required. Fast prototyping and low-cost design iterations.

Typical Applications for Stress-Free Etched Parts

Automotive: Stainless steel spring plates, sensor shims, filter meshes. Stable elasticity without stress relaxation.

Medical: Nebulizer plates, micro filter components, where material property consistency is mandatory.

Electronics & Semiconductor: Encoder discs, EMI shielding, precision contacts. Avoid dimension drift after assembly.

New Energy: Titanium bipolar plates for hydrogen fuel cells, electrode meshes.

Precision Instruments & Aerospace: Thin shims, optical apertures, flexure springs.

Design Limitations

Stress-free etching follows isotropic etching rules, lateral undercut must be considered in CAD design. It is optimized for thin metal sheets. For thick metal substrates above 0.5 mm, other processes may be more suitable. While the process introduces no new stress, raw material internal stress from rolling may still exist in the base metal.