Etching Manufacturing Process

Etching manufacturing process, also widely known as photochemical machining (PCM) or chemical etching, is a cold subtractive manufacturing technology for thingauge metal sheets. Instead of mechanical cutting, stamping or thermal melting, it uses controlled chemical dissolution to remove unwanted metal material. This process delivers burrfree, stressfree flat parts with intricate geometries, microholes, fine slots and mesh structures. It is extensively adopted across automotive, medical, semiconductor, newenergy and general industrial sectors.

The whole etching manufacturing process covers design preassessment, phototool preparation, metal pretreatment, photoresist lamination, UV exposure, developing, spray etching, stripping, secondary finishing and final quality inspection. Every stage directly influences dimensional accuracy, edge quality and production yield.

Step 1: DFM Design Review & Phototool Fabrication

The manufacturing cycle starts with customer 2D CAD data. Engineering teams perform DesignforManufacturability analysis before production. Key parameters including metal grade, sheet thickness, minimum hole / slot width, feature spacing, tolerance requirements and postprocessing needs are fully validated.

Since wet chemical etching is isotropic, sideundercut will occur while material dissolves downwards. Engineers calculate etch compensation values and adjust feature sizes on phototool to offset lateral erosion. No expensive hard stamping dies are required. A highprecision phototool film is generated from modified CAD files, with transparent and opaque areas defining protected metal zones and zones to be etched away. Any design update only requires revising CAD and remaking phototool, greatly shortening iteration leadtime for prototype projects.

Step 2: Metal Sheet Surface Pretreatment

Surface preparation is the foundation for stable photoresist adhesion. Raw rolled metal panels go through multistage continuous pretreatment: alkaline degreasing to eliminate oil, grease and fingerprints; rinsing; microetching to remove surface oxide layer and contaminants; final hot air drying.

Poor cleaning will cause photoresist delamination, pinholes and pattern damage in subsequent etching steps. Every panel must be clean and oxidefree before entering lamination procedure.

Step 3: Photoresist Dryfilm Lamination

Lightsensitive dryfilm photoresist is hotroll laminated onto both top and bottom sides of clean metal sheets under controlled temperature and pressure. Operators avoid bubbles or wrinkles between resist film and metal substrate. Doublesided lamination enables simultaneous etching from two surfaces, improving feature consistency and production efficiency.

Step 4: UV Exposure

Phototool film is tightly aligned against the photoresistcovered metal panel inside UV exposure equipment. Highintensity ultraviolet light passes through transparent sections of phototool. Exposed photoresist undergoes crosslinking reaction and becomes chemically resistant to developer solution. Unexposed areas under opaque phototool remain soluble. Accurate doublesided alignment ensures pattern matching on top and bottom surfaces.

Step 5: Developing Process

Panels are conveyed through alkaline developer solution. Developer washes away uncrosslinked photoresist, exposing bare metal regions that need chemical removal. Cured crosslinked photoresist stays firmly bonded to metal, forming an antietch protective mask which exactly outlines finishedpart geometry. Visual check is carried out after developing, confirming all holes, slots and contours are fully opened before etching.

Step 6: Automated Spray Etching (Core Manufacturing Stage)

Masked sheets are fed into continuous conveyortype spray etching machines. Circulating metalspecific etchant is pressuresprayed onto both sides of panels. Chemical reagent reacts with exposed bare metal and dissolves material gradually. Critical process variables are monitored in realtime: etchant concentration, working temperature, spray pressure and conveyor running speed.

Two main manufacturing outcomes can be achieved:

Throughetching: Etch completely through sheet thickness for part outlines, holes, slots and meshes. Most common sheet range is 0.01 mm1.5 mm.

Partialdepth blind etching: Terminate etching before full penetration, producing surface channels, dimples, bend grooves and marking textures. Stable production depth is normally 0.02 mm0.5 mm.

Isotropic material removal means sideundercut is unavoidable. Deep narrow vertical wall structures cannot be realized by standard wet etching.

Step 7: Stripping & Multilevel Rinsing

Once target etch depth is achieved, panels exit the etching tunnel. Remaining cured photoresist mask is stripped off by dedicated stripping chemical. Multiple cycles of deionized water rinsing remove residual etchant, developer and stripping agent, preventing postproduction corrosion. Raw etched blank components are obtained at this phase.

Step 8: Secondary Finishing Operations

Valueadded secondary processing is implemented according to customer specifications: passivation, polishing, deburring, surface plating, color filling for nameplates, bending / forming, ultrasonic cleaning, panel depaneling and custom packaging. Integrated inhouse finishing reduces quality risks caused by multisupplier outsourcing. For highend industries, material certificates and batch test records can be provided.

Step 9: Comprehensive Quality Inspection

Finished parts undergo systematic quality verification. 2D vision measuring equipment checks dimensional tolerances of outlines, holes and slots. Metallurgical microscopes inspect microapertures, edge profile and surface defects. Additional tests such as saltspray corrosion test are available for medical, semiconductor and newenergy applications. Unqualified goods are screened out, and qualified products move to packaging and delivery.

Suitable Materials & Process Limitations

Processable metals: 304 / 316 stainless steel, spring steel, copper, brass, nickel, nickelcobalt, titanium. Optimal thickness: 0.011.5 mm. Not ideal: cast alloys, heavily hardened tool steel due to uneven grain structure.

Major limitation comes from isotropic etching: sideundercut restricts minimum feature size and blinddepth performance. Highaspectratio deep narrow trenches are not feasible. For thick blocks and full 3D structures, stamping, laser cutting or CNC machining are better alternatives.

Main Industrial Applications of EtchingManufactured Parts

Etchingproduced components are widely used for automotive horn grilles and spring plates, medical nebulizer meshes and surgical accessories, semiconductor EMI shielding and microstencils, newenergy flowfield sheets and filter meshes, as well as industrial gaskets, encoder discs and metal nameplates.