Overview

An etched stainless steel diaphragm is a thin, flexible membrane whose deflection under pressure is the functional feature, so the process must preserve the material's spring properties rather than merely cut a shape. Dry film is laminated to both faces of spring-temper foil, the outline and annular half-etch rings are exposed and developed, and two-sided etching separates the outline while the rings stop at a designed residual thickness, leaving a thinner flexure web. Materials are usually 301, 304 or 316L stainless in spring temper, plus C17200 beryllium copper, nickel 200 or Alloy 42, at 0.02–0.3 mm, with 0.05–0.15 mm typical for pressure diaphragms. Because there is no stamping force or laser heat, the grain structure and temper stay intact, so hysteresis is low and fatigue life is long.

For a buyer, an etched stainless steel diaphragm is specified by deflection linearity, fatigue life and burst pressure together. Half-etched annular rings set the spring constant within one piece without welding on a separate spring, and residual web thickness held to ±0.005 mm makes the pressure-versus-deflection curve repeatable lot after lot. Stamping leaves work hardening and residual stress, while laser cutting leaves a recast layer and micro-cracks — both are crack-initiation sites under cycling, and chemical etching avoids both. Rolling direction should be noted and a stress-relief anneal scheduled after etching, or the zero point drifts; an un-etched flat rim is kept for welding or adhesive bonding.

Parameter Window

• Available Materials: 301 / 304 / 316L stainless (spring temper), C17200 beryllium copper, nickel 200, Alloy 42
• Material Thickness Range: 0.02–0.3 mm (0.05–0.15 mm typical for pressure diaphragms)
• Tolerance: ±0.005 mm on thickness; ±0.01 mm on profile; half-etched web ±10 % of gauge
• Minimum Feature: 0.10 mm flexure ligament; annular half-etch step to 0.02 mm residual web
• Surface Options: passivated, electropolished, stress-relief annealed, plated (Ni / Au), cleaned for bonding, adhesive ring
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Temper & Gauge Certification — Certify spring-temper 301/316L foil thickness and temper before release to the line.
2. Flexure Artwork — Draw the outline and annular half-etch rings; compensate each depth level for its side-etch.
3. Cleaning & Lamination — Laminate dry film to both faces without trapping particles in the flexure zone.
4. Two-Sided Exposure — Register the pattern so the thin annular web is symmetric through the thickness.
5. Development — Open the half-etch rings and check resist adhesion on the narrow flexure ligaments.
6. Controlled Etching — Time the bath so the outline separates while the annular web stops at the designed residual thickness.
7. Stripping & Stress Relief — Strip, neutralize and low-temperature anneal to remove resist-induced stress and stabilize flatness.
8. Deflection & Fatigue Test — Sample-test deflection linearity, burst pressure and cycle life, then pack flat between liners.

Core Advantages

1. Stress-free flexure: No stamping force or laser heat, so the spring temper and grain structure stay intact and hysteresis stays low.
2. Tunable stiffness by half-etch: Annular half-etched rings set the spring constant in one piece without welding a separate spring.
3. Fatigue life preserved: No recast layer or micro-cracks to initiate cracks, so the diaphragm survives millions of pressure cycles.
4. Thin-gauge flatness: 0.05 mm foil stays flat after etching, so the membrane seats evenly and does not pre-load the sensor.
5. Repeatable deflection: Depth and thickness are held to ±0.005 mm, so deflection-versus-pressure curves match from lot to lot.
6. Corrosion options: 316L for wet media and beryllium copper for high cycle life run on the same line.

Typical Applications

• Pressure sensors & transducers: Sensing diaphragms where deflection linearity sets accuracy.
• Valves & regulators: Metering membranes that set cracking pressure and shut-off force.
• Micro-pumps & dosing: Flexing membranes for diaphragm pumps and medical infusers.
• Burst & safety discs: Calibrated rupture membranes with half-etched score lines.
• Actuators & bellows: Thin flexure elements for pneumatic and hydraulic actuators.
• Acoustic & microphone capsules: Low-mass membranes with controlled stiffness and damping.

Design Notes & Process Considerations

1. Deflection target first: State the deflection at working pressure and the allowed non-linearity; thickness dominates the spring rate.
2. Half-etch ring geometry: Give ring width, residual web thickness and position; these set stiffness more than the outline does.
3. Grain direction: Note rolling direction for spring-temper 301, since flexural modulus and fatigue are anisotropic.
4. Stress & hysteresis: Require stress-relief anneal and low-hysteresis acceptance, because residual stress shifts zero point.
5. Burst & cycle life: Specify burst pressure and cycle count, and avoid sharp internal corners that concentrate stress.
6. Bonding land: Keep an un-etched flat rim for welding or adhesive bonding; etched stainless steel diaphragm flexure zones must stay clear of it.