Overview

Micro leaf spring etching forms miniature flexures and contacts by chemically thinning spring-temper sheet into beams, hinges and domes that store and release elastic energy. The part is judged less by its outline than by its spring rate, deflection and fatigue life, so the process is built around grain direction, half-etched thinning and burr-free edges. Stock is typically 301 or 304 stainless, beryllium copper C17200 or phosphor bronze, from 0.03 mm to 0.50 mm, with half-etched flexure regions that leave 30–70% of the original gauge.

A micro leaf spring etching supplier gains an advantage over stamping here because chemical removal introduces no work hardening and leaves no sheared burr, which is the usual starting point for a fatigue crack. Step etching lets one piece carry a stiff mounting rim and a thin, compliant beam in the same cycle, tuning stiffness without a secondary operation. Add a stress-relief anneal and generous fillet radii, and the flexure survives millions of cycles at a stable load. With no hard die, revised beam widths or spring rates are simply a new film.

Parameter Window

• Available Materials: 301/304 spring-temper stainless, beryllium copper C17200, phosphor bronze C51000, nickel alloys
• Material Thickness Range: 0.03–0.50 mm, with half-etched flexure zones retaining 30–70% of gauge
• Tolerance: ±0.02 mm on profile, ±0.01 mm on half-etch remaining thickness, ±0.03 mm on formed free height
• Minimum Feature: 0.08 mm beam width, 0.10 mm fillet radius, 0.10 mm slot
• Surface Options: as-etched, stress-relief annealed, electropolished, Ni/Au plating, passivated, formed and set
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Spring Rate Review — Convert target load, deflection and cycle life into beam width, gauge and half-etch remaining thickness.
2. Material Selection — Choose alloy and temper, then verify rolling direction and certify gauge before lamination.
3. Cleaning & Lamination — Degrease and laminate dry film on both faces so fine beams are fully protected.
4. Step Artwork Exposure — Expose full-thickness rims and half-etched beams with separately timed masks on each face.
5. Development — Develop both sides and inspect narrow beams for resist loss or undercut before etching.
6. Controlled Step Etching — Etch in alloy-matched chemistry, timing the half-etch regions to hit the target remaining thickness.
7. Stripping & Stress Relief — Strip resist, anneal to relieve stress, then form and set the free height where required.
8. Inspection & Packaging — Measure beam width, remaining gauge, load-deflection and flatness against the approved sample, then tray-pack.

Core Advantages

1. Tunable elasticity: Half-etch thinning sets stiffness in the same sheet, so load and deflection can be dialled without adding parts.
2. Tooling-free spring rates: A micro leaf spring etching program changes beam geometry with a new film, avoiding a forming die.
3. Superior fatigue life: Burr-free, stress-relieved edges remove the crack-initiation sites that stamped springs carry.
4. No work hardening: Chemical removal keeps the temper uniform, so spring force stays consistent across the batch.
5. Integrated step profiles: Stiff frames, thin beams and contact pads are produced together in one etch cycle.
6. Fine, repeatable beams: Sub-0.1 mm flexures hold width and thickness tightly, giving a narrow spread of spring constants.

Typical Applications

• Micro switch and relay springs: Thin flexures that open and close contacts over millions of cycles.
• Connector and battery contacts: Spring beams that hold a stable normal force against mating pads.
• MEMS suspensions and flexures: Compliant beams that guide motion in sensors and actuators.
• Medical device clips: Burr-free, passivated spring clips for minimally invasive instruments.
• Haptic domes and button springs: Formed snap elements with a consistent tactile load.
• Probe card and test springs: Fine contacts that must keep force and flatness across a dense array.

Design Notes & Process Considerations

1. Grain versus bending axis: Align the beam with the rolling direction and note it on the drawing, since transverse bending shortens fatigue life.
2. Half-etch remaining thickness: Specify remaining gauge, not removed depth; spring rate scales roughly with the cube of beam thickness.
3. Fillet radii: Use the largest practical radius at beam roots, because sharp inside corners concentrate stress and start cracks.
4. Side-etch compensation: Bias beam and slot artwork by roughly one material thickness of lateral undercut per side to hold width.
5. Stress relief and flatness: Request stress-relief anneal and call out flatness after forming to keep contact force even.
6. Plating and contact area: A micro leaf spring etching drawing should define plated zones, contact finish and free-height tolerance.