Overview

An etched copper diaphragm is a thin, elastic sensing membrane made by photochemical machining, used to turn pressure, sound or force into a repeatable deflection. The artwork defines the outline and any half-etched concentric corrugations; after development the unprotected copper is dissolved in a matched etchant, so membrane thickness and corrugation profile are set by the film and bath time rather than by a die. Substrates are typically copper C1100, beryllium copper C17200, phosphor bronze or brass, supplied from 0.02 mm to 0.3 mm. Because the process is chemical and force-free, the diaphragm leaves the line flat, burr-free and free of the work hardening and residual stress that would shift its stiffness and fatigue life.

For buyers, etched copper diaphragm production solves the consistency problem that dominates sensor yield. Stamped membranes vary in thickness and carry cold-work stresses, so sensitivity drifts from part to part and the zero point wanders with temperature; machined or laser-cut foils work-harden and distort at 0.05 mm scale; and a glued-on corrugation adds a bond line that can creep. Photochemical machining holds membrane thickness to ±0.01 mm, forms half-etched concentric rings in the same pass, and leaves the copper stress-free so deflection stays linear over the rated range. Combined with nickel or gold plating against oxidation, the membrane keeps its calibration from the first sample through volume production, which is why it is widely used in automotive and industrial pressure sensing.

Parameter Window

• Available Materials: copper C1100, beryllium copper C17200, phosphor bronze, brass
• Material Thickness Range: 0.02–0.3 mm
• Tolerance: ±0.01 mm on membrane thickness uniformity, ±0.02 mm on corrugation profile
• Minimum Feature: 0.08 mm corrugation rib, half-etched concentric rings with controlled residual
• Surface Options: Ni/Au plating anti-oxidation, annealing to soften, half-etched thinned zone, stress-free finish
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Membrane & Corrugation Design — Set the active diameter, thickness and corrugation profile against the target pressure range and linearity.
2. Material Selection & Temper — Choose copper, beryllium copper or bronze for elasticity and fatigue, then verify thickness uniformity and temper.
3. Cleaning & Lamination — Degrease and laminate dry film resist with matched heat and pressure so no bubbles sit under fine rings.
4. UV Exposure — Expose through high-resolution film with corrugations registered to the outline for even, concentric deflection.
5. Development — Wash out unexposed resist to open the corrugation and outline areas, and inspect for residue that would stiffen a ring.
6. Controlled Etching — Spray copper-matched chemistry, tuning time so half-etched rings stop at the target residual while the outline cuts through.
7. Stripping & Finishing — Remove resist, anneal to relieve stress, then plate Ni/Au against oxidation and stabilize the elastic response.
8. Inspection & Packaging — Measure thickness, corrugation profile, flatness and fatigue, then pack flat in clean, non-contact trays.

Core Advantages

1. Linear, tunable stiffness: Half-etched concentric corrugations set the deflection curve, so sensitivity can be tuned without changing the alloy.
2. Uniform sensitivity: ±0.01 mm thickness uniformity keeps the pressure-to-deflection response consistent from part to part and batch to batch.
3. Long fatigue life: With no cold work or heat-affected zone, the membrane survives millions of pressure cycles without drifting.
4. Conductive and plateable: Copper conducts heat and current well and takes Ni/Au plating, suiting capacitive and contact sensing designs.
5. Fast revisions: A new diameter or corrugation profile is a new film, keeping sensor prototyping and tuning economical.
6. Material choice: etched copper diaphragm parts can use copper, beryllium copper, phosphor bronze or brass to match range, fatigue and cost.

Typical Applications

• Pressure sensor membranes: Primary sensing elements in industrial and process transmitters where linearity drives accuracy.
• Automotive TPMS and knock sensing: Diaphragms for tire-pressure and engine-knock sensors exposed to heat and vibration.
• Microphone diaphragms: Thin, low-mass membranes for condenser and MEMS microphones needing flat frequency response.
• Relay contact springs: Elastic copper elements that combine spring force with reliable electrical contact over many cycles.
• Barometric switch capsules: Sealed capsules and aneroid elements that convert ambient pressure into mechanical motion.
• Flow meter diaphragms: Isolating membranes in gas and liquid flow meters that resist media while transmitting pressure.

Design Notes & Process Considerations

1. Thickness versus range: Define active diameter, thickness and target pressure range together, since stiffness scales strongly with thickness.
2. Corrugation geometry: Give ring count, depth, pitch and residual thickness, as these set linearity, stroke and sensitivity.
3. Half-etch residual: State the residual thickness under corrugations and its tolerance, because an over-etched ring becomes a weak point.
4. Temper and fatigue: Choose annealed or spring temper and call out the cycle life, since fatigue depends on both alloy and stress state.
5. Plating and oxidation: Specify Ni/Au plating thickness and coverage, as bare copper oxides would change mass and stiffness over time.
6. Stress-free handling: With etched copper diaphragm work, require stress-free, burr-free edges and flat packing, since a crease becomes a calibration offset.