Overview

Thin hole etching forms micro apertures directly in metal foil by photochemical machining, so hole size, position and wall quality are defined by artwork instead of by a drill bit or a punch. A photoresist layer is exposed through a high-resolution film, developed, and the exposed metal is dissolved in a matched etchant until the aperture breaks through. Because nothing touches the work mechanically, foil down to 0.01 mm stays flat and the holes leave the bath without burr, recast layer or micro-crack at the rim — the three failure modes that limit laser drilling and micro punching in very thin stock.

The useful limit of thin hole etching is set by the ratio of aperture to foil thickness rather than by aperture alone. On 0.05 mm stainless foil, 0.03 mm holes are routine and 0.02 mm is reachable under tightened process control; walls stay within a few micrometres of vertical, which keeps flow rate and filtration rating predictable instead of drifting with tool wear. Position holds to ±0.01 mm across a 300 mm panel, so an array of several thousand holes keeps the same pitch from edge to edge, and a single sheet can mix coarse and fine apertures where the flow model calls for it.

Parameter Window

• Available Materials: stainless steel 304/316L foil, nickel foil, copper foil, molybdenum, titanium foil
• Material Thickness Range: 0.01–0.2 mm
• Tolerance: ±0.01 mm on hole diameter, ±0.05 mm on outer profile, ±0.01 mm on hole position
• Minimum Feature: 0.02 mm aperture on 0.05 mm foil, 0.03 mm web between adjacent holes, aspect ratio up to 1:2 (diameter to depth)
• Surface Options: as-etched matte, electrolytic polish, passivation, black oxide, adhesive frame, carrier ring
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Hole Array Review — Check aperture, pitch and web width against foil thickness, and flag any hole that falls below the 1:1 diameter-to-depth ratio.
2. Foil Selection — Match alloy, temper and surface to the medium being filtered or metered; nickel for corrosion, 316L for medical and food contact.
3. Mounting & Cleaning — Laminate the foil to a temporary carrier so it can pass through the line without wrinkling, then degrease the active face.
4. Resist Lamination — Apply dry film resist at controlled temperature and nip pressure, keeping the layer thin so fine apertures do not close up.
5. Exposure — Expose both sides through registered film so the two etch fronts meet in the middle and the wall stays symmetrical.
6. Development — Wash out unexposed resist and inspect aperture openings under magnification before any metal is removed.
7. Etching & Breakthrough — Spray etchant and stop the run at optical breakthrough, then trim back to nominal diameter with a short controlled over-etch.
8. Strip, Inspect, Pack — Remove resist, neutralize, measure diameter, wall angle and burr on a sampling basis, then pack between interleaves.

Core Advantages

1. No burr and no recast: Chemistry removes metal without melting it, so the rim of each hole is clean and no hardened slag ring narrows the effective aperture.
2. Aperture scaled to thickness: Because the wall is nearly vertical, a 0.02 mm hole in 0.05 mm foil behaves as designed rather than tapering shut, which is where mechanical methods struggle.
3. Position locked to artwork: Hole centres follow the film, not a moving tool, so pitch error does not accumulate across a long array or from part to part.
4. Foil stays flat: No clamping force and no impact mean no dimple, no rolled edge and no residual stress pattern around the holes.
5. No tooling for new patterns: A new hole layout is a new film, so prototypes and low volumes avoid drill programming and punch die cost.
6. Mixed apertures in one sheet: Graded hole density, slot and round holes, and local fine zones can coexist without a second operation.

Typical Applications

• Filter membranes: Uniform micro apertures in 0.05 mm 316L for fuel, hydraulic and analytical filtration with a repeatable absolute rating.
• Aperture and orifice plates: Metering holes for gas and liquid flow where the discharge coefficient must not change with tool wear.
• Acoustic resistance parts: Fine hole arrays that set airflow resistance in miniature speakers and hearing instruments.
• Sensor and detector screens: Support mesh with high open area in front of optical or pressure sensing elements.
• Nebulizer and spray plates: Dense arrays of 0.03 mm holes that atomise liquid into a narrow droplet band.
• Medical cannula and probe screens: Burr-free apertures on thin stainless where a loose burr would be a contamination risk.

Design Notes & Process Considerations

1. Keep the aspect ratio honest: Aperture should be at least half the foil thickness; below that, etch time rises sharply and diameter spread across the panel widens.
2. Web width between holes: Leave at least 1.5 × foil thickness of metal between apertures, or the web etches through and neighbouring holes merge.
3. Entry and exit differ: Double-sided etching narrows the taper but still leaves a small difference; state which face is the functional side so the tolerance is applied there.
4. Hole shape and corners: Round holes etch most predictably; slots and sharp internal corners need a radius of at least 0.02 mm to avoid stress risers and uneven breakthrough.
5. Handling and flatness: Foil under 0.05 mm should be quoted on a carrier or frame, and flatness should be called out per 100 mm rather than as a single blanket figure.
6. Specify the measurement method: Agree on optical versus pin gauge, on the number of holes sampled, and on whether diameter is measured at entry, exit or mid-wall. Thin hole etching is only as repeatable as the inspection rule behind it.