Chemical etching, also widely known as photochemical etching or photo etching, is a subtractive manufacturing technique that fabricates precision metal parts by selectively dissolving unwanted metal through controlled chemical reactions. Unlike mechanical cutting or laser melting, it removes metal at the molecular level without physical contact or heat input.

Step-by-Step Working Principle

DFM Design Review Engineers check customer CAD drawings for etching manufacturability. The isotropic nature of wet etching means material erodes sideways as well as vertically, so feature sizes must be adjusted to compensate for undercut.

Metal Surface Preparation Metal sheets (stainless steel, nickel, copper, titanium etc.) go through degreasing and cleaning. Oil, fingerprints and oxidation layers are removed to ensure strong, uniform adhesion of photoresist dry film. Poor cleaning causes film peeling and pattern defects.

Dry Film Lamination A light-sensitive photoresist dry film is laminated onto both sides of the cleaned metal sheet under controlled heat and pressure. This protective layer will shield the areas of metal that remain as the final part.

UV Exposure The metal sheet covered with photoresist is placed under UV light with a photomask (film artwork). The mask blocks UV light on the part geometry we want to keep. Exposed regions of the photoresist undergo chemical cross-linking and become hardened.

Development The sheet is sprayed with developer solution. Unhardened photoresist (the areas to be etched away) washes off, exposing bare metal. The hardened resist stays attached and acts as a protective mask. Now the desired part pattern is revealed on the metal surface.

Chemical Etching (Core Step) Etchant solution is sprayed onto both sides of the panel simultaneously. The etchant chemically reacts with the exposed bare metal and dissolves it away. The masked areas protected by cured photoresist remain intact. The etching continues until full penetration (through etching) or target depth (blind etching) is achieved.

Stripping / Resist Removal After etching completes, the remaining hardened photoresist mask is stripped away using stripping chemicals, leaving the finished metal component pattern.

Final Cleaning & Quality Inspection Parts are thoroughly rinsed to eliminate residual etchant and chemical contaminants. Inspection verifies dimensions, flatness, edge quality and surface cleanliness before packing and delivery.

Core Characteristics of Chemical Etching

Non-contact process: No cutting tools, no mechanical force applied to the workpiece. Zero burrs and no work hardening.

No heat input: No heat-affected zone; original metal grain and material properties stay unchanged.

Isotropic etching: Etchant attacks metal equally in all directions. Lateral undercut occurs, which must be considered during design.

Whole-panel processing: All features on one metal sheet are etched at the same time, ideal for meshes, arrays and multi-part layouts.

Common Applications

Chemical etching is widely used to manufacture encoder discs, spring plates, shims, gaskets, microporous filter meshes, medical nebulizer plates, titanium bipolar plates for hydrogen energy, EMI shielding and precision optical apertures.