Overview

An etched 304 stainless steel diaphragm is a thin, flexible membrane that converts pressure or displacement into a repeatable deflection in sensors, valves and micro-pumps, produced by photochemical machining rather than stamping or spinning. A photoresist mask is exposed with the diaphragm outline and concentric corrugation pattern, developed, and the unprotected 304 foil is dissolved in a controlled ferric chloride spray, so thickness uniformity, corrugation width and profile are set by the artwork and etch time instead of tool pressure. Typical stock is 304/316L stainless between 0.02 mm and 0.20 mm, chosen for its spring temper, corrosion resistance and ability to hold a fatigue-resistant, burr-free membrane at very thin gauges.

For automotive and sensor buyers, an etched 304 stainless steel diaphragm solves three recurring problems: stamped membranes carry residual stress and thickness variation that shift the pressure curve, concentric corrugations at 0.05 mm scale are hard to form mechanically, and any burr or heat tint becomes a fatigue crack starter under millions of cycles. Chemical machining forms every feature on a sheet at the same rate, holding thickness and profile consistent from the first sample through volume production, while leaving the membrane flat, stress-free and free of the work-hardened edge that shortens cycle life.

Parameter Window

• Available Materials: 304 and 316L stainless steel; also copper alloys and nickel for mixed builds
• Material Thickness Range: 0.02–0.20 mm
• Tolerance: ±0.005 mm on thickness uniformity, ±0.02 mm on outline and profile
• Minimum Feature: 0.05 mm corrugation groove width, 0.10 mm hole diameter
• Surface Options: electropolishing, passivation, stress-relief anneal, acid pickling, ultrasonic cleaning
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Nesting — Convert the outline and corrugation pattern to vector art, verify groove-to-thickness rules, and lay out panels with shared fiducials.
2. Material Certification & Prep — Verify 304 grade, mill certificate and thickness, check temper and flatness, then shear to exposure size.
3. Cleaning & Lamination — Degrease and laminate dry-film resist on both faces under matched heat and pressure without trapped bubbles.
4. Dual-Side UV Exposure — Expose the corrugation artwork from top and bottom in register so both faces etch symmetrically.
5. Development — Wash out unexposed resist to open the groove areas and inspect for residue that would blunt a corrugation.
6. Controlled Etching — Spray 304-matched ferric chloride, tuning time, temperature and conveyor speed to hold thickness and groove depth.
7. Stripping & Stress Relief — Strip resist, neutralize, then apply a controlled stress-relief anneal and electropolish or passivate.
8. Inspection & Packaging — Measure thickness, profile and outline on a vision system, verify flatness, then pack between liners in clean trays.

Core Advantages

1. Uniform thin section: Chemical removal holds thickness to ±0.005 mm, so the pressure-deflection curve stays consistent part to part.
2. Burr-free fatigue life: No rolled edge or heat-affected zone removes the crack starters that shorten a cycling membrane's life.
3. No die cost: Each corrugation layout is a new film, keeping prototype sensors and frequent revisions economical without a forming tool.
4. Fine concentric features: 0.05 mm corrugation grooves form together with the outline, with symmetric, repeatable depth.
5. Stress-free flatness: With no shear or heat input, the foil stays flat, so bonding, welding or clamping will not preload the membrane.
6. Repeatable custom profiles: An etched 304 stainless steel diaphragm can combine corrugations, bosses and mounting holes on one part, reproduced from first article to volume.

Typical Applications

• Pressure sensor diaphragms: Sensing membranes in piezoresistive and capacitive pressure transmitters.
• EGR & emission valve membranes: Corrosion-resistant diaphragms in exhaust-gas recirculation and control valves.
• Injector & fuel metering discs: Thin metering membranes in fuel and fluid injection modules.
• Micro-pump diaphragms: Flexing membranes for medical and analytical micro-pumps and dosing devices.
• Microphone & acoustic diaphragms: Thin sensing foils where mass and flatness set frequency response.
• Rupture & burst discs: Calibrated thin membranes that open at a defined pressure for safety relief.

Design Notes & Process Considerations

1. Groove-to-thickness ratio: Keep corrugation width at or above roughly the foil thickness; very fine grooves in thick stock distort from undercut.
2. Thickness and flatness callout: State nominal thickness, allowable variation and bow, since these set the spring rate and pressure curve.
3. Grade and temper: Choose 304 or 316L by the media, and specify the temper and anneal state because they change stiffness and fatigue life.
4. Dual-side etch: Specify symmetric etching from both faces so corrugations stay balanced instead of tapered to one side.
5. Tie bars and borders: Leave adequate tie bars and process borders, and define final singulation so thin membranes survive stripping.
6. Cleanliness and handling: With an etched 304 stainless steel diaphragm, specify liner packaging, fingerprint control and residual-ion limits for clean sensor assembly.