Overview

Photo etching — also called photochemical machining or photochemical etching — is a subtractive process that uses a photoresist mask and a controlled chemical etchant to dissolve selected areas of a thin metal sheet, leaving burr-free, stress-free parts. What are the advantages of photo etching? In short: it needs no hard die, introduces no mechanical force or heat-affected zone, holds very fine features in thin stock, and repeats the same geometry from the first article to high volume at low tooling cost. Compared with stamping, which deforms thin material and requires a costly die for every new part number, and with laser cutting, which can leave a heat tint and recast layer, chemical removal keeps parts flat and dimensionally stable.

Those advantages of photo etching translate into practical gains for engineers and buyers. A design change is a new film rather than new tooling, so prototypes and low-volume runs stay economical. Features down to 0.05 mm are formed in stainless steel 304/316L, copper, brass, nickel and Kovar between 0.02 mm and 2.0 mm without distortion. Because the whole sheet is imaged at once, every part on a panel shares the same aperture size, pitch and profile, which simplifies incoming inspection and reduces assembly rework. Understanding the advantages of photo etching helps specify when the process is the right fit: thin, fine, flat and burr-free components in electronics, medical, automotive and filtration assemblies.

Parameter Window

• Available Materials: stainless steel 304/316L, copper, brass, nickel, Kovar, titanium
• Material Thickness Range: 0.02–2.0 mm
• Tolerance: ±0.02 mm on critical profiles (down to ±0.01 mm on thin stock)
• Minimum Feature: 0.05 mm line width, 0.08 mm hole diameter at 0.1 mm stock
• Surface Options: passivation, electropolish, Ni/Au plating, black oxide, adhesive backing
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & DFM Review — Convert the drawing into vector artwork and check hole diameters, web widths and bend relief against the chosen stock before tooling.
2. Material Selection — Choose the alloy and temper, then confirm flatness and surface condition before lamination.
3. Cleaning & Lamination — Degrease the sheet and laminate dry-film photoresist on both faces under controlled heat and pressure.
4. UV Exposure — Expose the part pattern through high-resolution film registered to a common panel datum for accuracy.
5. Development — Wash out unexposed resist to open the apertures, then inspect the finest features for residue.
6. Controlled Etching — Spray or immerse in chemistry matched to the alloy, holding ±0.02 mm through time, temperature and conveyor speed.
7. Stripping & Finishing — Remove resist, neutralize, then apply the specified passivation or plating and an optional anneal for flatness.
8. Inspection & Packaging — Verify aperture size, profile and flatness against the approved first article, then pack in trays or on liner.

Core Advantages

1. Burr-free edges: Chemical removal leaves no roll-over or heat tint, so parts seat flush without secondary deburring.
2. No hard tooling: A new part number is a new film, keeping prototypes and low-volume programs economical.
3. Fine feature capability: Features down to 0.05 mm hold at production thickness without distortion.
4. Tight, repeatable tolerance: ±0.02 mm is held across the whole sheet, so assemblies fit without selective rework.
5. Stress-free flat parts: No mechanical force means thin components stay flat and dimensionally stable after etching.
6. Material and finish flexibility: Stainless, copper and nickel alloys run on one line with plating or passivation matched to the end environment.

Typical Applications

• Lead frames: Etched IC and semiconductor lead frames with fine, burr-free fingers.
• Encoder discs: High-resolution optical encoder discs with dense slot patterns.
• Shims and spacers: Precision thickness shims for instrument gap control.
• Filter meshes: Micro-perforated screens for filtration and metering.
• EMI shielding: Thin shielding cans and meshes for RF-sensitive modules.
• Aperture plates: Optical apertures and masks for imaging and sensing.

Design Notes & Process Considerations

1. Feature versus thickness: Keep the minimum web at or above 1.2 × material thickness so narrow ribs do not lift during etching.
2. Tolerance callout: State ±0.02 mm on critical profiles and separate half-etched depth from through-cut dimensions.
3. Hole geometry: Specify diameter, pitch and open area; round entries reduce stress concentration in fine patterns.
4. Flatness and burr: Call out flatness per 100 mm and require burr-free edges where parts mate to a housing.
5. Surface and plating: Name the finish and thickness, since plating adds to the final stack.
6. Panelization: Group parts with shared registration marks to cut handling cost on repeat volumes.