Overview

Molybdenum grating etching uses photochemical machining to cut fine slit and bar patterns into thin refractory-metal sheet without mechanical force or a stamping die. A photoresist mask is exposed with the grating artwork, developed, and the unprotected molybdenum is dissolved in an alkaline or peroxide-based chemistry matched to Mo, so line width, pitch and duty cycle are governed by the film and etch dwell rather than tool pressure. Typical substrates are pure molybdenum (≥99.95% Mo) and TZM alloy in 0.05–1.0 mm gauges. Because the process is chemical, the grating leaves the line flat, burr-free and free of the recast layer, micro-cracks and tool wear that come with laser or EDM cutting of hard, brittle refractory foil.

For optical and instrumentation buyers, molybdenum grating etching addresses three recurring problems. Molybdenum is hard and brittle at room temperature, so punching fine slits cracks the webs and wears dies quickly; encoder, spectrometer and X-ray grids demand line widths down to 0.02 mm and tight pitch that are hard to hold mechanically; and the metal's low thermal expansion and high-temperature stability must survive without heat-affected zones that would distort the pattern. Chemical machining forms every slit on a panel at the same rate, holding duty cycle consistent from the first sample through volume production, while preserving the dimensional stability that makes molybdenum valuable in vacuum, thermal and radiation environments. New patterns need only a new film.

Parameter Window

• Available Materials: Pure molybdenum (Mo ≥99.95%), TZM (Mo-Ti-Zr), MoCu; also stainless and nickel for mixed builds
• Material Thickness Range: 0.05–1.0 mm (common 0.1 / 0.2 / 0.5 mm)
• Tolerance: ±0.005 mm on slit width, ±0.01 mm on pitch, ±0.02 mm on outline
• Minimum Feature: 0.02 mm slit/line width, 0.05 mm bar, 0.06 mm pitch
• Surface Options: electropolishing, blackening / anti-reflective coating, stress-relief anneal, light sandblast, ultrasonic cleaning
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Nesting — Vectorize the slit array, verify line-to-thickness ratio, and plan panel layout with tie bars and registration marks.
2. Material Certification & Prep — Verify Mo grade, mill certificate and thickness, inspect for cracks and flatness, then shear to exposure size.
3. Cleaning & Lamination — Degrease and laminate dry-film resist under matched heat and pressure so no bubbles sit under fine bars.
4. UV Exposure — Expose through high-resolution film with the array registered to the sheet edge for panel-level pitch consistency.
5. Development — Wash out unexposed resist to open the slit areas and inspect for residue that would block etching.
6. Controlled Etching — Spray molybdenum-matched chemistry, tuning time, temperature and conveyor speed to hold sidewalls and avoid bar thinning.
7. Stripping & Finishing — Remove resist, neutralize, then electropolish, blacken or stress-relieve to set flatness and optical contrast.
8. Inspection & Packaging — Measure slit width, pitch and duty cycle on a vision system, verify flatness, then pack in clean rigid trays.

Core Advantages

1. Burr-free micro-slits: Chemical removal leaves no recast layer or burr, so diffraction and transmission stay clean and no particles shed into optical paths.
2. No die cost: Each new grating pattern is a new film, keeping prototypes and frequent revisions economical without a stamping tool.
3. Thermal and vacuum stability: Molybdenum's low expansion and high melting point keep the pattern dimensionally stable in heat, vacuum and radiation.
4. Repeatable ultra-fine lines: 0.02 mm slits and 0.05 mm bars form together across a panel with tight pitch spread and uniform duty cycle.
5. Stress-free flatness: With no shear or heat input, brittle foil stays flat and crack-free, so bonding to frames or stacks will not warp it.
6. Precision optical duty cycle: With molybdenum grating etching, line, pitch and open ratio can be tuned item by item to hit a target diffraction or attenuation.

Typical Applications

• Optical encoder gratings: High-resolution scale and index gratings whose fine slits set measurement resolution.
• Spectrometer slits: Fixed entrance and exit slits for optical instruments that need clean, sharp edges.
• X-ray anti-scatter grids: Collimator and grid plates for imaging systems exploiting molybdenum's density and stability.
• Synchrotron and EUV masks: Beamline apertures and shadow masks that withstand heat and vacuum without distortion.
• Metrology scales: Precision length and angle standards that rely on low thermal expansion.
• Semiconductor shadow masks: Deposition and evaporation masks for thin-film patterning on temperature-sensitive substrates.

Design Notes & Process Considerations

1. Line-to-thickness ratio: Keep slit width at or above roughly material thickness; too fine a slit distorts from undercut and thins the bar.
2. Pitch and duty-cycle callout: State line width, pitch and open ratio, and define the bar/slit geometry rather than only a line count.
3. Grade selection: Choose pure Mo for stability or TZM for strength and creep resistance, and note the material standard and certificate needs.
4. Nesting and tie bars: Leave enough tie bars and process borders, and specify the final cut method so brittle webs survive stripping and cleaning.
5. Thin-foil and brittle handling: For foil below 0.1 mm, specify a carrier or rigid liner and call out flatness to avoid cracks and chipped edges.
6. Surface and cleanliness: With molybdenum grating etching, define electropolish, blackening and residual-ion limits, especially for vacuum and optical parts.