Overview

Thin grating etching produces fine, repeated line-and-space patterns in low-profile metal foil, where the single most important quality measure is line width consistency. A 304/316L stainless, nickel or copper sheet from 0.02 mm to 0.30 mm is laminated, exposed with the grating artwork and etched so that critical dimension, or CD, stays uniform across the whole panel. Line widths from 0.02 mm to 0.20 mm with a 50:50 duty cycle are routine, and CD uniformity within ±0.003 mm is what keeps an encoder scale or attenuation grid accurate.

Because chemical removal is uniform over a full sheet, a thin grating etching supplier can hold the same line width from edge to edge without the tool wear that changes a machined or ruled grating mid-run. Spray pressure, etchant temperature and conveyor speed are controlled together, and dual-side exposure with a CD bias offsets lateral undercut so lines finish on nominal width. The result is a flat, burr-free, stress-relieved foil with low line-edge roughness, supplied on a protective liner for optical, sensing and shielding assemblies.

Parameter Window

• Available Materials: 304/316L stainless, nickel 200/201, C1100 copper, beryllium copper C17200
• Material Thickness Range: 0.02–0.30 mm (0.05–0.15 mm typical for encoder and optical grids)
• Tolerance: ±0.003 mm CD uniformity across panel, ±0.01 mm pitch cumulative, ±0.01 mm outline
• Minimum Feature: 0.02 mm line width, 0.02 mm space, 0.05 mm pitch, duty cycle 40–60%
• Surface Options: as-etched, electropolished, blackened, nickel/gold plated, stress-relief annealed, protective film
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. CD Definition — Fix line width, space, pitch and duty cycle, then set the allowable CD spread across the full panel.
2. Material Selection — Choose low-stress foil and certify gauge and flatness, since thin stock amplifies CD drift.
3. Cleaning & Lamination — Degrease and laminate dry film on both faces to protect the dense line array.
4. Dual-Side Exposure — Register front and back artwork to shared fiducials and apply a CD bias for lateral undercut.
5. Development & CD Check — Develop both sides and measure resist line width at several panel positions before etching.
6. Uniform Spray Etching — Etch with matched chemistry and balanced spray to hold line width identical across the sheet.
7. Stripping & Stress Relief — Strip resist, electropolish or blacken, then anneal to relieve stress and stabilise flatness.
8. Metrology & Pack — Map CD, pitch and duty cycle against the approved article, then laminate a protective film and pack flat.

Core Advantages

1. Line width consistency: Controlled spray and CD bias hold critical dimension within ±0.003 mm edge to edge, so scale accuracy is uniform.
2. Tooling-free gratings: A thin grating etching run needs only a film, so a new pitch or duty cycle carries no ruling or die cost.
3. No tool wear drift: Chemical removal does not degrade a cutting edge, so the first and last line on a panel match.
4. Low line-edge roughness: Electropolished, burr-free lines reduce stray light and signal noise in optical encoders.
5. Flat, stress-relieved foil: Annealing and linered delivery keep the grating flat for bonding to glass or a carrier.
6. Fine duty-cycle control: Line and space can be biased independently, giving 40–60% duty cycles for tailored attenuation.

Typical Applications

• Optical encoder scales: Linear and rotary gratings where CD uniformity sets position accuracy.
• Spectrometer slits and diffraction grids: Repeated apertures for wavelength selection and light dispersion.
• Light attenuation grids: Neutral-density meshes with a controlled open ratio for cameras and sensors.
• Moiré and measurement grids: Registered patterns used for strain, alignment and surface inspection.
• EMI and optical shielding grids: Conductive line arrays that shield while passing a defined light fraction.
• Alignment and shadow masks: Fine registered line patterns for deposition and calibration fixtures.

Design Notes & Process Considerations

1. CD uniformity callout: Specify allowable line-width spread across the full panel, not just a nominal width at one point.
2. Side-etch compensation: Bias line artwork by the measured lateral undercut of the alloy so etched lines land on nominal width.
3. Duty cycle and pitch: State line:space ratio and cumulative pitch error; a drifting duty cycle shifts transmission and encoder phase.
4. Double-sided registration: Require shared fiducials and a front-to-back alignment tolerance when lines are etched from both faces.
5. Edge roughness and finish: Call out electropolishing or blackening, since rough line edges scatter light and add noise.
6. Flatness and protective film: A thin grating etching drawing should define flatness per 100 mm and linered, contamination-free packing.