Overview

An etched copper aperture is made by photochemical machining that cuts precise light-passing holes, annuli and slits into thin copper sheet without mechanical force or a stamping die. The aperture artwork is imaged onto a photoresist mask, developed, and the unprotected metal is dissolved in a copper-matched chemistry, so hole diameter, roundness and position are set by the artwork and etch dwell rather than by tool pressure. Standard substrates are oxygen-free C1020 and tough-pitch C1100 copper from 0.02 mm to 0.5 mm. Because removal is chemical, the aperture leaves the line with steep, burr-free walls, no rolled edge and no heat-affected zone, which is exactly what an optical stop needs.

For optical and instrument engineers, the etched copper aperture solves three recurring problems. Light holes often shrink to 0.03 mm while demanding micron-level roundness, which punching rounds over and laser cutting loads with dross and heat distortion; imaging, laser and spectroscopy systems need straight, concentric, low-reflection edges that are hard to machine in thin sheet; and copper is soft, so stamping thin foil curls and deforms the part. Chemical machining forms every hole on a panel at the same rate, holding diameter and position consistent from the first sample through volume production, and a blackened finish suppresses stray reflection.

Parameter Window

• Available Materials: Oxygen-free C1020, tough-pitch C1100, copper alloys; also nickel, stainless and Invar for mixed builds
• Material Thickness Range: 0.02–0.5 mm (common 0.05 / 0.1 / 0.2 mm)
• Tolerance: ±0.005 mm on hole diameter, ±0.003 mm on roundness, ±0.01 mm on hole position
• Minimum Feature: 0.03 mm micro-hole, 0.05 mm annulus/ring width, 0.08 mm slit
• Surface Options: anti-reflection blackening, nickel plating, electropolishing, anti-tarnish, ultrasonic cleaning
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Nesting — Convert the hole, annulus or slit geometry to vector art, verify diameter-to-thickness ratio, and plan panel layout with registration marks.
2. Material Certification & Prep — Confirm C1020/C1100 grade, mill certificate and thickness, inspect flatness and surface, 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 annuli.
4. UV Exposure — Expose through high-resolution film with the array registered to the sheet edge for panel-level diameter consistency.
5. Development — Wash out unexposed resist to open the hole areas, and inspect for residue that would block etching or distort the edge.
6. Controlled Etching — Spray copper-matched chemistry, tuning time, temperature and conveyor speed to hold vertical walls and true roundness.
7. Stripping & Blackening — Remove resist, neutralize, then blacken or nickel-plate to kill stray reflection and protect the copper from tarnish.
8. Inspection & Packaging — Measure diameter, roundness and position on a vision system, verify edge quality, then pack flat in clean, anti-tarnish trays.

Core Advantages

1. Micron-level roundness: Chemically formed holes hold ±0.003 mm roundness, so beam profiles and diffraction behavior stay predictable.
2. No die cost: Each new hole size or slit pattern is a new film, keeping prototypes and frequent revisions economical without a stamping tool.
3. Burr-free optical edge: With no rolled edge or dross, the stop defines a clean beam boundary and sheds no particles into the optical path.
4. Low stray reflection: Copper takes a uniform anti-reflection blackening, cutting ghost images and flare inside cameras and spectrometers.
5. Stable thin sheet: No shear or heat input leaves the foil flat and stress-free, so stacked apertures register without gaps or warping.
6. Fast custom turnaround: the etched copper aperture moves from drawing to sample quickly, with hole size, array and frame tuned item by item.

Typical Applications

• Optical aperture stops: Beam-defining stops in lenses, telescopes and machine-vision optics that set f-number and cut stray light.
• Camera shutter blades: Thin copper leaves and diaphragm segments whose clean edges keep exposure repeatable at high cycle counts.
• Microscope field stops: Field and condenser apertures that demand concentric, burr-free holes for even illumination.
• Laser collimation holes: Pinholes and spatial-filter apertures that shape and clean a laser beam without edge scatter.
• Spectrometer slits: Precision entrance and exit slits where straight, parallel edges set spectral resolution.
• Electron-beam apertures: Beam-limiting diaphragms in analytical instruments that benefit from copper's thermal conductivity.

Design Notes & Process Considerations

1. Diameter-to-thickness ratio: Keep hole diameter at or above material thickness; too small a hole distorts from undercut and rounds the wall.
2. Roundness and edge callout: State diameter, roundness, wall verticality and burr limits, not just a nominal hole size.
3. Grade selection: Choose C1020 for purity and conductivity or C1100 for economy, and note temper, certificate and flatness needs.
4. Concentricity and datums: For multi-hole arrays, define the datum and concentricity so stacked apertures align to the optical axis.
5. Thin-foil handling: For foil below 0.05 mm, specify a carrier or liner and call out flatness and cleanliness to avoid creases and fingerprints.
6. Surface and cleanliness: With an etched copper aperture, define blackening, plating and tarnish limits, especially for vacuum and imaging duty.