Overview

A grating etching service uses photochemical machining to cut encoder discs, slit arrays, ruling patterns and scale bars directly out of thin metal foil. A photoresist mask carrying the pitch pattern is exposed, developed, and the unprotected metal is dissolved in a matched etchant, so the grating lines are formed in the material itself instead of being printed or ruled on top. Typical substrates are molybdenum, nickel, stainless steel 304/316L and copper, supplied between 0.02 mm and 0.5 mm. Because removal is chemical rather than mechanical, lines are formed without cutting stress — no burr, no roll-over and no heat-affected zone — and the same film holds pitch from the first article to the full production batch.

For optical and metrology parts the decisive numbers are pitch, line-to-space ratio and edge sharpness. Photochemical etching holds 0.05 mm lines with uniform sidewalls across the whole sheet, and pitch stays within ±0.005 mm over 100 mm. Every part leaves the line flat and ready for blackening, plating or direct assembly into encoder and sensor modules.

Parameter Window

• Available Materials: molybdenum, nickel, stainless steel 304/316L, copper, titanium
• Material Thickness Range: 0.02–0.5 mm
• Tolerance: pitch ±0.005 mm over 100 mm, profile ±0.01 mm
• Minimum Feature: 0.05 mm line width and 0.05 mm gap on 0.05 mm foil
• Surface Options: black oxide, matte black coating, electroless nickel, gold flash, mirror finish
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Pattern Review — Convert the pitch drawing to vector film data and check line width, gap and line-to-space ratio against foil thickness.
2. Material Selection — Pick molybdenum for thermal stability, nickel for conductivity, or stainless 304/316L for corrosion resistance in the field.
3. Cleaning & Lamination — Degrease the foil and laminate dry film resist under controlled heat and pressure so no bubble distorts fine lines.
4. UV Exposure — Expose the pitch pattern through high-resolution film registered to the sheet edge for uniform pitch across the panel.
5. Development — Wash out unexposed resist to open the grating lines, then inspect for broken or bridged strokes under magnification.
6. Etching — Spray etch in chemistry matched to the alloy, holding time, temperature and line speed to keep sidewalls vertical and pitch stable.
7. Stripping & Surface Treatment — Remove resist, neutralize, then blacken, plate or polish to the optical finish the assembly requires.
8. Inspection & Packaging — Measure pitch, line width and flatness against the approved sample, then pack in trays with protective interleaf.

Core Advantages

1. Repeatable pitch: A grating etching service reproduces pitch within ±0.005 mm over 100 mm from one film, so parts from different batches drop into the same encoder without recalibration.
2. No tooling cost: A new pitch or disc pattern is only a new film, so prototypes and design revisions stay economical at small quantities.
3. Stress-free edges: Chemical removal leaves no burr, roll-over or heat-affected zone, keeping optical edges sharp and the foil flat.
4. Fine lines on thin foil: 0.05 mm line and gap hold on 0.05 mm stock, which gives high line counts on small-diameter encoder discs.
5. Full-panel uniformity: All parts on a sheet etch together, so line width and depth match across the batch and signal amplitude stays even.
6. Finish flexibility: Molybdenum, nickel and stainless run on one line, and blackening, gold flash or electroless nickel cover absorptive and reflective needs.

Typical Applications

• Rotary encoder discs: High-count pitch patterns etched in 0.1 mm molybdenum or stainless for motion-control modules.
• Linear scale bars: Long ruling patterns with reference marks for metrology stages and measuring equipment.
• Spectrometer slit arrays: Uniform slit widths and spacings etched in nickel foil for optical analysis instruments.
• Beam-limiting gratings: Fine line arrays that shape and sample light paths in laser and sensor heads.
• Wavelength selection plates: Etched comb patterns that pass or block narrow bands inside optical assemblies.
• Calibration targets: Ruled pitch standards etched in stainless for instrument calibration and QC checks.

Design Notes & Process Considerations

1. Line width versus thickness: Keep the narrowest line at 0.05 mm or 1.2 × foil thickness, whichever is larger, or the lines etch unevenly.
2. Pitch tolerance callout: State pitch tolerance over a defined length, not per line only, because accumulated drift matters on long scales.
3. Line-to-space ratio: Balanced 1:1 lines etch most uniformly; ratios beyond 1:3 need slower etch rates and a wider process window.
4. Optical finish: Specify the reflectance target for blackened or plated surfaces and whether the grating works in reflection or transmission.
5. Handling and flatness: Call out flatness per 100 mm and require protective interleaf, because thin foil gratings distort under point loads.
6. Registration features: Add fiducials and alignment holes on the panel so encoder discs mount without re-centering; a grating etching service can hold these to ±0.01 mm next to the pitch pattern.