Overview

Brass diaphragm etching is a precision forming route for pressure sensors, instrument capsules and fluid-control elements. Photochemical machining produces corrugations, annular grooves, thinned zones and irregular profiles in thin brass sheet without mechanical force or a stamping die. Brass grades such as H62 and CuZn37 (C26000, C26800) form well, offer moderate elasticity and good electrical and thermal conductivity, and solder and plate readily, which is why they are a staple for elastic sensing elements. A photoresist mask is exposed with the artwork, developed, and the unprotected metal is dissolved in chemistry matched to brass, so corrugation depth, residual thickness and outline are set by the artwork and etch time, leaving burr-free, stress-free edges with no work hardening.

For sensor and structural engineers, brass diaphragm etching solves three recurring problems. Sensitivity depends on a uniform thinned zone, and stamping or machining at 0.05 mm scale cannot hold thickness consistency and throughput together without curling and springback; corrugations set displacement linearity, so any burr, scratch or local hardening shifts the pressure-to-displacement curve and increases hysteresis; and diaphragms are often brazed or plated into a sealed capsule, where laser dross and heat-affected zones foul the joint and shorten fatigue life. Chemical etching forms local thinning and corrugations together across a sheet, holding thickness consistent from the first article through volume production.

Parameter Window

• Available Materials: Brass H62 / CuZn37 (C26000, C26800 cartridge brass) as standard, also phosphor bronze, beryllium copper and 316L stainless
• Material Thickness Range: 0.05–0.50 mm
• Tolerance: ±0.02 mm on profile, ±0.01 mm on thinned-zone depth
• Minimum Feature: 0.10 mm slot/line, 0.15 mm hole, step depth from 0.02 mm
• Surface Options: nickel plating, anti-tarnish passivation, degreasing, ultrasonic cleaning, bright anneal, electropolishing
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Nesting — Convert corrugations, grooves and thinned zones to vector art, plan multi-stage exposure layers, and lay out registration marks.
2. Material Certification & Prep — Verify brass grade, mill certificate, thickness and temper, inspect scratches and flatness, then shear to exposure size.
3. Cleaning & Lamination — Degrease, remove oxide and laminate dry film resist under matched heat and pressure so no bubbles sit under fine grooves.
4. UV Exposure — Expose through high-resolution film, registering corrugation and thinning layers stage by stage for uniform thickness.
5. Development — Wash out unexposed resist to open the etch areas, and inspect for residue that would block local thinning.
6. Staged Controlled Etching — Etch through outline and slots first, then partially etch thinned zones, tuning time, temperature and line speed for step depth.
7. Stripping & Surface Finish — Remove resist and neutralize, bright-anneal to relieve stress, then apply nickel plating or anti-tarnish passivation.
8. Inspection & Packaging — Measure profile, corrugation and residual thickness on a vision system, verify flatness and elasticity, then pack in clean trays.

Core Advantages

1. Uniform sensitivity: Etch time sets the thinned zone precisely, so linearity is good and sensitivity spread stays small across a batch.
2. Bur-free, unhardened: Chemical removal leaves no rolled edge or work hardening, so hysteresis is low and fatigue life is long.
3. Local thinning: Through-cut on one face and step-thinning on the other form rigid and elastic zones in one piece, cutting part count.
4. No die cost: Each new corrugation is a new film, keeping prototypes and frequent revisions economical without a stamping tool.
5. Solderable and plateable: An etch-clean brass surface bonds reliably to nickel plating and braze, suiting sealed capsules and hermetic builds.
6. Volume repeatability: Every feature etches together, so thickness and profile hold from first article to production, with vision reports for traceability.

Typical Applications

• Pressure sensors: Gas and hydraulic sensing diaphragms where a uniform thinned zone gives linear, stable output.
• Instrument capsules: Corrugated capsules for gauges and differential transmitters, where consistent elasticity sets range and hysteresis.
• Automotive sensing: Manifold and oil-pressure diaphragms that resist vibration, media attack and drift.
• Flow and valve parts: Meter diaphragms and valve springs where local thinning balances stiffness and response.
• Acoustic devices: Microphone and speaker diaphragms using thin brass foil for elasticity, conductivity and solderability.
• Relays and switches: Elastic contacts and actuator diaphragms where burr-free edges limit wear and fatigue cracking.

Design Notes & Process Considerations

1. Grade and temper: Choose H62 or CuZn37 for elasticity, conductivity and corrosion, and note temper, hardness and certificate requirements.
2. Residual-thickness ratio: Keep residual thickness adequate for working pressure, or undercut makes thickness uneven and hurts linearity.
3. Corrugation callout: Specify depth, pitch, ring count and thinned-zone boundary, plus layer-to-layer registration for staged etching.
4. Flatness and stress: Call out flatness and anneal condition, and for brazed or plated parts set plating type and thickness to avoid warp.
5. Nesting and tie bars: Leave enough tie bars and process borders, and define the final cut method so thin webs survive stripping and cleaning.
6. Documentation: With brass diaphragm etching, attach residual-thickness tolerance, corrugation datums and an elasticity test method to the drawing for repeatable approval.