How to Do Etching on Metal

Industrialgrade metal etching, also called photochemical etching or photochemical machining (PCM), is a subtractive manufacturing method that uses chemical dissolution to remove unwanted metal material. It produces burrfree, stressfree precision parts including meshes, gaskets, shims, spring plates and microaperture components. Home DIY etching differs from massproduction industrial process; this article focuses on standard commercial manufacturing workflow.

Required Raw Materials & Consumables

l Thingauge rolled metal sheet: stainless steel, copper, brass, nickel, titanium etc., typical thickness 0.01 mm1.5 mm

l Dryfilm photoresist (lightsensitive resist film)

l Phototool film (pattern negative generated from CAD files)

l Degreasing and cleaning agents

l Etchant solution matched for target metal alloy

l Developer solution

l Resist stripping solution

l Deionized water for multistage rinsing

Stepbystep Industrial Process to Do Etching on Metal

Step 1: CAD Design Review and Phototool Production

Start with 2D CAD files of target metal parts. Engineering team conducts DFM (Design for Manufacturability) analysis. Calculate etch compensation value to offset isotropic sideundercut during chemical attack. After design optimization, output highaccuracy phototool negative film. The phototool carries transparent and opaque areas to define protected zones and zones to be etched away. No expensive hard stamping dies are needed. Design modification only requires updating CAD files and reproducing phototool.

Step 2: Metal Sheet Surface Preparation

Surface treatment is critical for stable photoresist adhesion. Raw metal sheets go through continuous multistage pretreatment: degreasing to remove oil, grease and fingerprints; alkaline cleaning; rinsing; microetching to eliminate oxide layer and surface contaminants. Fully dry the sheets. Any residual oil or oxide will cause photoresist peeling, pinholes or pattern damage in later procedures.

Step 3: Photoresist Lamination

Dryfilm photoresist is hotrolled and laminated onto both top and bottom surfaces of clean metal sheet under controlled temperature and pressure. Ensure tight, bubblefree bonding between resist film and metal substrate. Doublesided lamination enables simultaneous etching from two sides, improving feature precision and production efficiency.

Step 4: UV Exposure

Place the phototool film closely against photoresistcovered metal panel inside UV exposure machine. Highintensity ultraviolet light passes through transparent regions of phototool. Exposed photoresist areas undergo chemical crosslinking and become insoluble to developer. The unexposed areas under opaque phototool sections remain soluble for next developing step. Precise doublesided alignment guarantees pattern consistency on top and bottom sides.

Step 5: Developing

Treat laminated sheets with alkaline developer solution. Developer washes away uncrosslinked, unexposed photoresist, exposing bare metal areas that need to be dissolved. Crosslinked cured photoresist stays firmly on metal surface as protective mask, exactly covering the geometry of finished parts. After developing, perform visual inspection to confirm all contours, holes and slots are fully opened before entering etching chamber.

Step 6: Chemical Spray Etching (Core Operation)

Load masked sheets into automated conveyortype spray etching equipment. Circulating etchant liquid is sprayed under pressure onto both sides of metal panel. Chemical reagent reacts with bare exposed metal and dissolves it gradually. Key process parameters are strictly monitored and controlled: etchant concentration, liquid temperature, spray pressure, conveyor travel speed.

Etching can achieve two different results:

1. Throughetching: dissolve metal completely through sheet thickness for part outlines, holes and mesh openings.

2. Partialdepth blind etching: stop etching before full penetration to make surface channels, dimples or marking textures.

Because wet chemical etching is isotropic, material dissolves downwards and sideways at similar rates. Sideundercut is unavoidable and must be considered in earlier DFM and phototool compensation.

Step 7: Stripping and Primary Cleaning

Once target etch depth is reached, panels exit etching tunnel. Remaining cured photoresist protective mask is removed by chemical stripping solution. Multiple rinses with deionized water wash off residual etchant, developer and stripping chemicals to prevent postprocess corrosion on metal parts. At this stage, raw etched blank components are obtained.

Step 8: Secondary Finishing & PostTreatment

According to customer specifications, carry out valueadded secondary operations: passivation, polishing, deburring, surface plating, color filling for nameplates, bending / forming, ultrasonic cleaning, separation of individual parts from panel frame. Inhouse secondary processing helps maintain consistent product quality.

Step 9: Full Quality Inspection

Finished parts go through comprehensive quality control. 2D vision measuring system verifies dimensional tolerances of outlines, holes and slots. Metallurgical microscope checks microapertures, edge quality and surface defects. For highrequirement industries such as medical, semiconductor and newenergy, additional tests including saltspray corrosion test and hardness test can be performed. Batch inspection reports and material certificates can be provided.

Key Practical Notes When You Do Etching on Metal

Suitable material: mostly thin rolled metal sheets. Cast metal, heavily heattreated hardened steel generally produce poor etching results.

Isotropic etching limitation: wet etching cannot produce vertical sharpwall deep narrow trenches. Sideundercut always exists.

Thickness recommendation: best manufacturing performance within 0.01 mm1.5 mm sheet thickness. Thicker sheets bring longer etching time, higher cost and larger undercut.

Mask integrity: photoresist must stay well bonded during whole etching cycle; mask lifting will create scrap parts.

Difference between Industrial PCM and Home DIY Metal Etching

DIY metal etching uses simple manual tools, lowvolume corrosive liquid for artcraft marking. It cannot hold tight dimensional tolerance for precision engineering components. For functional industrial parts, professional photochemical etching manufacturing is required.

If you plan custom etched metal components, prepare CAD drawings, specify metal grade and sheet thickness for manufacturability assessment and formal quotation.