Sheet metal etching (also called photochemical etching or chemical milling) is a non-contact subtractive manufacturing process that selectively removes material from thin metal sheets using controlled chemical etchants. Unlike stamping, laser cutting or CNC machining, sheet metal etching works through isotropic chemical dissolution rather than mechanical force or thermal impact. It produces flat, burr-free blanks with no residual stress, making it ideal for intricate thin-gauge metal parts across electronics, automotive, medical, aerospace and industrial sectors.

Common materials include stainless steel (304/316), copper and copper alloys, brass, aluminum, titanium, nickel silver, beryllium copper, Kovar and Invar. Typical sheet thickness ranges from 0.02 mm to 2.0 mm. The process supports through etching for contours and cutouts, plus blind/half etching for bend lines, recessed pockets and controlled-depth features.

Step-by-Step Sheet Metal Etching Workflow

1. DFM & Artwork ReviewEngineers review vector drawings, calculate side undercut compensation for isotropic etching, check minimum feature sizes, hole-to-thickness ratios and half-etch depth requirements. Optimize nesting layout to maximize material utilization.
2. Surface Pre-treatmentMetal sheets go through alkaline degreasing, acid pickling and DI water rinsing to remove oil, fingerprints and oxide layers. Clean surface ensures uniform photoresist adhesion and consistent etch rate across the whole panel.
3. Dry Film LaminationPhotosensitive dry film photoresist is laminated onto one or both sides of the cleaned sheet under controlled heat and pressure, forming a uniform protective mask layer.
4. UV Exposure & DevelopmentUV light transfers the part pattern onto the photoresist through a precision photomask. Developer washes away resist on areas to be etched, exposing bare metal; protected regions remain as the finished part geometry.
5. Controlled Chemical Etching (Core Step)The sheet is conveyed through a spray etch chamber where chemically matched etchant dissolves exposed metal from one or both sides. Process parameters (temperature, concentration, spray pressure, conveyor speed) are tightly monitored to control etch depth, dimensional tolerance and edge quality. Both through etching and blind half-etching can be achieved in the same step.
6. Resist Stripping & RinsingThe cured photoresist mask is stripped off, followed by multi-stage deionized water rinsing and drying to eliminate residual etchant and prevent surface corrosion.
7. Quality InspectionInspect overall dimensions, hole sizes, half-etch depth, flatness, edge quality and surface condition. Use microscopy and coordinate measuring machines for precision features.
8. Optional Post-processingSecondary operations include: bending, forming, plating (nickel, tin, gold, silver), passivation, anodizing, electropolishing, ink filling, welding, assembly and surface finishing.

Core Advantages of Sheet Metal Etching

1. Burr-free & stress-freeNo mechanical cutting force and no heat-affected zone. Parts come out flat with zero burrs and zero residual stress — no secondary deburring needed, and elastic materials retain their properties.
2. No hard tooling, fast prototypingOnly digital photomask artwork is required. Design changes update CAD files at near-zero cost. Typical prototype lead time is just a few days, far faster than stamping dies.
3. High precision & consistencyTight dimensional tolerances with uniform feature size across the entire panel. Suitable for micro holes, fine slits and intricate geometries that are difficult for stamping or laser cutting.
4. Design flexibilityCombine through holes, cutouts, half-etched bend lines, recessed pockets and variable patterns in one process. Multiple part designs can be nested on a single sheet for optimal material yield.
5. Wide material & thickness rangeWorks on virtually any thin sheet metal: stainless steel, copper, brass, aluminum, titanium, nickel, beryllium copper, Kovar and more. Thickness from ultra-thin foil (0.02 mm) up to 2.0 mm.
6. Cost-effective for low-to-medium volumesNo tooling investment means economical small-batch and custom orders. For high-volume simple parts, stamping may offer lower unit cost, but etching wins for complexity, flexibility and speed.

Typical Applications

• Electronics: EMI/RFI shielding cans, lead frames, encoder discs, spring contacts, contact fingers
• Industrial: precision filters, sieves, nameplates, shims, gaskets, washers
• Automotive: sensor components, fuel injector screens, acoustic grilles, heat shields
• Medical: surgical instrument components, stent blanks, microfluidic parts, instrument labels
• Aerospace & defence: lightweight structural shims, heat sink plates, RF components
• Decorative & consumer: metal nameplates, jewelry blanks, decorative grilles, branding plates

Design Limitations & Notes

Wet chemical etching is isotropic, so lateral undercut must be compensated during CAD design. Minimum feature width and hole diameter are generally limited by sheet thickness (typical minimum feature ≈ material thickness). Deep 3D formed parts are not directly achievable — etching produces 2D flat blanks, and secondary bending/forming is required for 3D geometries. For very thick sheets (over 2 mm) or deep drawn complex shapes, stamping, CNC or waterjet may be more suitable.