Overview

An etched sensor diaphragm is a thin metal membrane produced by photochemical machining, in which the diaphragm thickness is set by controlled material removal and the surrounding rim or boss is left full-thickness for mounting. Unlike machined or stamped diaphragms, the etched version is free of tool marks and residual stress, so it deflects symmetrically under pressure. This symmetry, together with precise and uniform thickness, is what determines the linearity and sensitivity of a pressure or force sensor.

The controlling properties are sensitivity and thickness uniformity. A diaphragm's deflection is proportional to the cube of its thickness, so a small thickness error becomes a large output error; etched diaphragms hold tight thickness tolerance across the full active area. Materials are stainless steel, nickel and titanium from 0.01 mm to 0.2 mm thick, and fine patterns such as strain gauges, bosses or corrugations can be etched in the same step. This makes etched sensor diaphragm parts well suited to pressure, force, load and acoustic sensors where repeatable deflection is everything.

Parameter Window

• Available Materials: stainless steel 304/316L, nickel, titanium (Grade 1/2)
• Material Thickness Range: 0.01–0.2 mm
• Tolerance: diaphragm thickness ±0.005 mm, profile ±0.025 mm
• Minimum Feature: pattern feature down to 0.05 mm
• Surface Options: as-etched, electropolished, passivated, PVD or plated
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Diaphragm Design Review — Convert the membrane layout to vector artwork and confirm active diameter, thickness and pattern.
2. Material Selection — Choose stainless, nickel or titanium for the required stiffness, fatigue and media compatibility.
3. Cleaning & Lamination — Degrease the foil and laminate dry film resist on both sides for controlled double-side removal.
4. Double-Side Exposure — Expose the membrane and rim pattern with front-to-back registration to center the active area.
5. Development — Wash out unexposed resist and inspect the membrane boundary for residue or under-development.
6. Controlled Etching — Etch with matched chemistry, controlling time and temperature to reach the target diaphragm thickness uniformly.
7. Stripping & Finishing — Strip resist, neutralize, then electropolish or passivate to stabilize the surface and finish.
8. Inspection & Packaging — Measure diaphragm thickness across the active area, check flatness and pattern, then pack protected.

Core Advantages

1. Uniform membrane thickness: Controlled double-side etching holds thickness tight, so sensor sensitivity and linearity repeat.
2. Stress-free diaphragm: Chemical removal leaves no machining stress, so the membrane deflects symmetrically.
3. Tight thickness tolerance: Thickness is held to ±0.005 mm across the active area, reducing output scatter.
4. Fine integrated patterns: Strain gauges, bosses and corrugations etch in the same step as the membrane.
5. No tooling: Diaphragm diameter, thickness and pattern change with the artwork, not a new die.
6. Media-compatible alloys: Stainless, nickel and titanium cover corrosive and biocompatible applications.

Typical Applications

• Pressure sensor diaphragms: Sensing membranes for gauge, absolute and differential pressure.
• Force and load cells: Deflecting membranes that convert force into strain.
• Acoustic and microphone membranes: Thin, uniform diaphragms for sound detection.
• Medical sensor membranes: Biocompatible diaphragms for disposable and implantable sensors.
• Vacuum and flow sensors: Membranes responding to small pressure differentials.
• Automotive sensor membranes: Durable diaphragms for engine and brake pressure sensing.

Design Notes & Process Considerations

1. Thickness versus sensitivity: Sensitivity scales with the cube of thickness, so state the target thickness and its tolerance explicitly.
2. Active diameter: Define the active area and rim width, since the rim stiffness fixes the boundary condition.
3. Material selection: Pick stainless for general use, titanium for biocompatibility, nickel for specific modulus needs.
4. Integrated features: Specify bosses, corrugations or gauge patterns to be etched in the same step.
5. Surface finish: Call out electropolish or passivation for corrosion and a stable, clean membrane surface.
6. Flatness: State flatness over the active area, as residual bow shifts the zero point of the sensor.