Etching Manufacturing Process

Etching manufacturing process, also referred to as photochemical machining (PCM) or chemical etching, is a cold subtractive manufacturing technique for thin rolled metal sheets. It removes excess material by controlled chemical dissolution rather than mechanical cutting, stamping or thermal processing. This technology produces burrfree, stressfree precision flat parts with intricate contours, microholes, fine slots and mesh structures. It is widely applied in automotive, medical device, semiconductor, newenergy and general industrial fields.

The complete etching manufacturing process consists of nine core stages: DFM assessment and phototool making, metal surface pretreatment, photoresist lamination, UV exposure, developing, automated spray etching, stripping and rinsing, secondary finishing and final quality inspection. Each procedure directly determines dimensional tolerance, edge quality and production yield.

Step 1: DFM Design Review and Phototool Fabrication

The whole manufacturing workflow starts with customer 2D CAD drawings. Engineering teams carry out DesignforManufacturability evaluation prior to production. Engineers verify metal grade, sheet thickness, minimum hole and slot width, web spacing, tolerance requirements and subsequent postprocessing demands.

Wet chemical etching features isotropic material removal. Metal dissolves downwards and sideways at nearly equal rates, generating unavoidable undercut. Etch compensation values are calculated and embedded into phototool dimensions to counteract lateral erosion. No costly hard stamping dies are required. A highaccuracy phototool film is output, where transparent and opaque zones separate protected areas from areas to be etched away. Design modification only needs updating CAD files and remaking phototool, greatly shortening prototype iteration cycles.

Step 2: Metal Sheet Surface Pretreatment

Surface pretreatment is critical for reliable photoresist bonding. Raw metal panels go through multistep continuous treatment: alkaline degreasing to wipe off oil, grease and fingerprints, circulating water rinsing, microetching for oxide and contaminant removal, followed by thorough hotair drying.

Insufficient cleaning leads to common defects including photoresist peeling, pinholes and broken patterns during later etching. Only fully clean, oxidefree metal sheets can move to the lamination station.

Step 3: Dryfilm Photoresist Lamination

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

Step 4: UV Exposure

The phototool is closely aligned against the photoresistcovered panel inside UV exposure equipment. Highintensity ultraviolet light passes through transparent parts of the phototool. Exposed photoresist produces crosslinking chemical reaction and becomes resistant to developer solution. Unexposed photoresist under opaque regions keeps soluble status. Precise doublesided alignment guarantees pattern coincidence on upper and lower surfaces.

Step 5: Developing

Panels pass through alkaline developer circulation tank. Developer washes away uncrosslinked photoresist and exposes bare metal waiting for chemical dissolution. Crosslinked cured photoresist stays tightly attached and forms an antietch protective mask exactly matching finishedpart geometry. Operators perform visual check after developing to ensure all holes, slots and outlines are fully opened before entering the etching chamber.

Step 6: Automated Spray Etching (Core Process)

Masked sheets are transported into continuous conveyortype spray etching machines. Metalmatched etchant is pressurized and sprayed onto both sides of panels. Chemical liquid reacts with bare exposed metal and gradually dissolves unwanted material. Key parameters are realtime controlled: etchant concentration, working temperature, spray pressure and conveyor travel speed.

Two main etching results can be achieved:

Throughetching: Completely penetrate the sheet to produce part outlines, holes, slots, meshes, shims and encoder discs. Optimal working thickness ranges 0.01 mm1.5 mm for most alloys.

Partialdepth blind etching: Stop etching before full penetration to fabricate flow channels, dimples, bend grooves and surface marking. Stable production blinddepth is 0.02 mm0.5 mm.

Due to isotropic nature, side undercut always occurs. Standard wet etching cannot achieve deep, narrow trenches with perfectly vertical side walls.

Step 7: Stripping and Multistage Rinsing

Once target etch depth is reached, panels exit the etching tunnel. Chemical stripping solution removes remaining cured photoresist mask. Multiple deionized water rinses wash residual etchant, developer and stripping chemicals thoroughly, avoiding secondary corrosion on finished components. Etched blank parts are obtained at this stage.

Step 8: Secondary Finishing Operations

According to customer technical specifications, a variety of inhouse secondary services are available: passivation, polishing, deburring, plating, nameplate color filling, bending and forming, ultrasonic cleaning, panel depaneling and custom packaging.

For highstandard projects from medical, semiconductor and newenergy sectors, material certificates, batch inspection reports and saltspray test records can be supplied. Inhouse finishing reduces quality risks caused by multivendor outsourcing.

Step 9: Comprehensive Quality Inspection

Finished parts undergo fullrange quality control. 2D vision measuring system verifies dimensional tolerances of outlines, holes and slots. Metallurgical microscopes check microapertures, edge profile and surface flaws. Additional performance tests can be arranged for special application scenarios. Defective products are screened out, and qualified goods proceed to packaging and shipment.

Applicable Materials & Process Constraints

Suitable metals: 304 / 316 stainless steel, spring steel, copper, brass, nickel, nickelcobalt, titanium. Preferred sheet thickness: 0.011.5 mm.

Less suitable: cast alloys, heavily quenched tool steel, because uneven grain structure brings unstable etching effect.

Major limitation originates from isotropic undercut. This process fits planar thinmetal parts, not for thick solid blocks or complex full 3D geometries. For these requirements, stamping, laser cutting or CNC machining are more suitable alternatives.

Typical Enduse Applications

Etched components are widely used in automotive horn grilles and spring contacts, medical nebulizer meshes, semiconductor EMI shielding sheets, newenergy flowfield plates, industrial gaskets, encoder discs, filter meshes and metal nameplates.