Overview

Copper grating etching uses photochemical machining to cut fine, evenly spaced lines and slots into thin copper sheet for encoder discs, metrology scales and diffraction elements. A photoresist mask is exposed with the grating artwork, developed, and the unprotected copper is dissolved in a controlled cupric chloride or ferric chloride spray, so line width, pitch and duty cycle are set by the artwork and etch time rather than by a ruling engine or die. Typical substrates are oxygen-free C1020 and tough-pitch C1100 copper between 0.05 mm and 0.30 mm, valued for high conductivity, easy etching and a clean, burr-free edge at fine pitch.

For optical and motion-control buyers, copper grating etching solves three recurring problems: mechanically ruled or stamped lines carry burrs and edge waviness that add signal noise, pitches down to 0.05 mm are hard to hold uniformly over a long scale, and copper oxidizes readily so any heat tint or residue degrades subsequent plating and bonding. Chemical machining forms every line on a sheet at the same rate, holding pitch and duty cycle consistent from the first sample through volume production, while keeping the sheet flat and stress-free for lamination to a substrate.

Parameter Window

• Available Materials: oxygen-free copper C1020, tough-pitch C1100, phosphor bronze, brass; also stainless and nickel for mixed builds
• Material Thickness Range: 0.05–0.30 mm
• Tolerance: ±0.005 mm on line width, ±0.01 mm on pitch and position
• Minimum Feature: 0.02 mm line/slot width, 0.05 mm grating pitch
• Surface Options: anti-tarnish passivation, nickel or gold plating, matte blackening, electropolishing, ultrasonic cleaning
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Nesting — Convert the grating pattern to vector art, verify line-to-thickness and pitch rules, and lay out panels with shared fiducials.
2. Material Certification & Prep — Confirm copper grade, mill certificate and thickness, inspect flatness and surface, then shear to exposure size.
3. Cleaning & Lamination — Degrease and laminate dry-film resist on both faces under matched heat and pressure without trapped bubbles.
4. UV Exposure — Expose the grating artwork through high-resolution film, registered to the sheet edge for panel-level pitch accuracy.
5. Development — Wash out unexposed resist to open the slot areas and inspect for residue that would blur line edges.
6. Controlled Etching — Spray copper-matched chemistry, tuning time, temperature and conveyor speed to hold line width and avoid undercut.
7. Stripping & Anti-Tarnish — Strip resist, neutralize, then apply anti-tarnish passivation or nickel/gold plating to stabilize the copper surface.
8. Inspection & Packaging — Measure line width, pitch and duty cycle on a vision system, verify flatness, and pack between liners in clean trays.

Core Advantages

1. Burr-free line edges: Chemical removal leaves no rolled burr, so encoder signals stay clean and no particles shed into the optical path.
2. No hard tooling: Each pitch or duty cycle is a new film, keeping one-off scales and frequent revisions economical without a ruling die.
3. Fine, uniform pitch: Lines at 0.02 mm and pitches of 0.05 mm hold ±0.005 mm across a full panel with consistent duty cycle.
4. Stress-free flatness: With no shear or heat input, thin copper stays flat, so bonding to glass or a carrier will not warp the grating.
5. Conductor-ready surface: Copper's conductivity suits capacitive and EMI gratings, and the surface accepts nickel or gold plating for corrosion protection.
6. Repeatable custom patterns: copper grating etching can combine multiple pitches, index marks and code tracks on one part, reproduced from first article to volume.

Typical Applications

• Optical encoder discs: Rotary and linear code tracks where line-edge quality sets signal contrast and resolution.
• Metrology scales: Moiré and linear scales for coordinate measurement and motion-stage feedback.
• Spectrometer diffraction elements: Fine-slit and grating plates for wavelength separation in compact instruments.
• Capacitive sensing grids: Conductive electrode arrays for touch, displacement and proximity sensors.
• EMI shielding grids: Fine copper mesh apertures that balance ventilation, shielding and optical transparency.
• Laser diffraction masks: Aperture and grating plates for beam splitting and structured-light projection.

Design Notes & Process Considerations

1. Line-to-thickness ratio: Keep line and slot width at or above roughly the foil thickness; very fine lines in thick stock distort from undercut.
2. Pitch and duty cycle: State line width, pitch, duty cycle and total track length, rather than only a line count, for reliable signal performance.
3. Copper grade selection: Choose C1020 for plating and bonding, or phosphor bronze for spring temper, and note the material standard.
4. Anti-tarnish and plating: Define passivation or nickel/gold plating, since bare copper oxidizes and plating slightly changes the effective line width.
5. Tie bars and borders: Leave adequate tie bars and process borders, and specify final singulation so fine lines survive stripping and cleaning.
6. Handling and cleanliness: With copper grating etching, specify liner packaging, fingerprint control and residual-ion limits for clean optical assembly.