Overview

A stainless steel diaphragm etching process forms thin, flexible pressure membranes by dissolving selected areas of 301, 304 or 316L sheet through a photoresist mask, rather than by stamping or spinning. Because material is removed chemically, the finished diaphragm keeps a uniform gauge across its whole active area, carries no work-hardened edge, and holds a flat, stress-free surface that deflects repeatably under pressure. Stock from 0.02 mm to 0.30 mm is common, and thickness uniformity within ±0.003 mm is achievable on the active region, which is the single figure that governs linearity and burst pressure in a sensing element.

Buyers choose this route for three reasons: deflection behaviour depends on gauge, so chemical thinning can dial a part to a target spring rate; half-etched corrugations and step profiles can be built into the same sheet without a second operation; and burr-free edges remove the crack-initiation sites that shorten fatigue life in a membrane flexing millions of times. From first article to production lot, the same film reproduces the same thickness map, so calibration coefficients stay valid across batches. The workflow is tooling-free, which keeps low-volume prototype and engineering-change costs modest.

Parameter Window

• Available Materials: 301, 304, 304L and 316L stainless; also beryllium copper C17200 and nickel alloys on request
• Material Thickness Range: 0.02-0.30 mm (active membrane 0.02-0.15 mm, with half-etched steps down to 0.01 mm)
• Tolerance: ±0.02 mm on outer profile, ±0.003 mm on gauge uniformity, ±0.01 mm on half-etch step depth
• Minimum Feature: 0.08 mm slot, 0.10 mm hole, 0.10 mm web between adjacent openings
• Surface Options: as-etched, electropolished, passivated, stress-relief annealed, selective plating, protective film
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Deflection Review — Review pressure range, stroke and target spring rate, then back-calculate the required gauge and corrugation geometry.
2. Material Selection — Choose the 301/304/316L temper and certify incoming gauge with a mapped thickness report before lamination.
3. Cleaning & Lamination — Degrease and laminate dry-film resist on both faces under controlled heat and pressure to avoid bubbles over the membrane.
4. Dual-Side Exposure — Register front and back artwork to shared targets so half-etched corrugations and through-slots align within 0.02 mm.
5. Development — Develop both sides and inspect the resist under magnification for pinholes before any metal is removed.
6. Controlled Etching — Spray-etch in ferric chloride matched to the alloy, using time, temperature and conveyor speed to hold gauge and wall taper.
7. Stripping & Stress Relief — Strip resist, neutralize, and vacuum-anneal where the part must keep long-term flatness and stable deflection.
8. Inspection & Packaging — Measure gauge map, flatness, profile and burst sample against the approved article, then pack between interleaving film.

Core Advantages

1. Gauge uniformity drives accuracy: Chemical removal holds a uniform active thickness, so pressure-deflection curves stay linear and calibration is transferable.
2. Tooling-free flexibility: Each revision is a new film, so a stainless steel diaphragm etching program absorbs design changes without a stamping die.
3. Burr-free fatigue life: No sheared or rolled edge means fewer crack-initiation points, which raises cycle life in flexing membranes.
4. Built-in step profiles: Half-etch corrugations, thinned hinges and thickened rims are produced in one sheet during the same etch cycle.
5. Stress-free flat parts: The process adds no mechanical work hardening, so membranes sit flat and seal evenly against a housing.
6. Batch-to-batch repeatability: A qualified film and fixed etch recipe reproduce the same thickness map, keeping sensor coefficients stable lot to lot.

Typical Applications

• Pressure sensor diaphragms: Thin 316L membranes for industrial transmitters and differential pressure cells.
• Regulator and valve membranes: Flexing discs in gas and liquid pressure regulators that need a stable spring rate.
• Medical infusion pump membranes: Burr-free, passivated diaphragms for dosing pumps with long flex life.
• Microphone and acoustic transducers: Low-mass membranes where uniform gauge sets sensitivity and batch spread.
• Burst discs and safety vents: Calibrated rupture membranes whose burst point depends on tight gauge control.
• Microvalve and bellows elements: Corrugated, half-etched diaphragms for miniature fluidic actuators.

Design Notes & Process Considerations

1. Gauge versus deflection: State the target spring rate and let the supplier set gauge; deflection scales roughly with the cube of thickness, so a 10% gauge error is large.
2. Side-etch compensation: For through-features, undersize the artwork by about one material thickness per side so lateral undercut lands the opening on nominal size.
3. Half-etch step callout: Specify remaining thickness, not just removed depth, and place steps away from the highest-strain region to protect fatigue life.
4. Grain and rolling direction: Align the bending axis with the rolling direction and note it on the drawing for consistent deflection across the sheet.
5. Flatness and residual stress: Call out flatness per 25 mm and request stress-relief anneal when the diaphragm is clamped at the rim.
6. Sealing and edge quality: A stainless steel diaphragm etching drawing should require burr-free, passivated edges and define the clamped sealing land width.