Overview

Leaf spring chemical etching uses photochemical machining to cut flat spring blanks out of thin metal without a stamping die. A photoresist mask is exposed with the spring profile, developed, and the unprotected metal is dissolved in a matched etchant, so the entire leaf spring — arms, slots, holes and bend lines — is formed in one pass. Typical substrates are 301/304 stainless steel, beryllium copper (C17200) and phosphor bronze (C52100), supplied between 0.05 mm and 1.0 mm.

Because material is removed chemically rather than sheared, the blank leaves the bath stress-free, burr-free and free of the work-hardening that stamping introduces along the cut edge. Spring rate, deflection and fatigue life therefore depend only on the alloy, thickness and geometry you specify, not on edge damage from the process. Forming and heat treatment are handled downstream, so the same etched blank can feed multiple bend programs without dedicated tooling.

Parameter Window

• Available Materials: 301/304 stainless steel, beryllium copper (C17200), phosphor bronze (C52100), spring steel
• Material Thickness Range: 0.05–1.0 mm
• Tolerance: ±0.05 mm on profile, slot width and hole position
• Minimum Feature: 0.1 mm slot width and 0.2 mm arm width
• Surface Options: passivation, electroless nickel, electrolytic Ni/Au, tin, stress-relief heat treatment
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork Review — Convert the spring drawing to vector artwork and check arm width, slot width and bend relief against material thickness.
2. Material Selection — Match alloy and temper to spring force, conductivity and corrosion needs; beryllium copper for contacts, stainless for corrosion resistance.
3. Cleaning & Lamination — Degrease the strip and laminate dry film resist so no bubbles sit under fine arms or slots.
4. UV Exposure — Expose the profile through high-resolution film registered to the strip edge for panel-level repeatability.
5. Development — Wash out unexposed resist to open the spring outline, then inspect for under-developed thin arms.
6. Etching — Spray or immerse in chemistry matched to the alloy; edge quality is controlled by time, temperature and conveyor speed.
7. Stripping & Finishing — Remove resist and neutralize, then passivate, plate or heat-treat to set the final temper and spring properties.
8. Inspection & Packaging — Verify profile, thickness, flatness and bend relief against the sample, then pack flat or on reels.

Core Advantages

1. Stress-free blanks: The chemical process leaves no work-hardened edge, so etched springs keep repeatable spring rate and fatigue life.
2. No tooling cost: A new spring profile is a new film, so prototypes and revisions ship without a stamping or progressive die.
3. Burr-free edges: Etched edges need no deburring, so the spring seats cleanly and avoids stress risers that crack under load.
4. Fine geometry: Slots down to 0.1 mm and arms down to 0.2 mm hold across the sheet, ideal for compact contact springs.
5. Full-sheet consistency: Every spring on the strip etches at the same rate, so dimensions stay uniform across a batch.
6. Material flexibility: Stainless, beryllium copper and phosphor bronze run on one line. Leaf spring chemical etching also supports multiple profiles on a single strip for mixed runs.

Typical Applications

• Battery contact springs: Flat leaf springs in beryllium copper that press against cells with controlled force.
• Switch and relay springs: Repeatable flexure springs with tight form for electrical switching.
• Connector springs: Small stamped-free contact leaves etched with fine slots for retention and compliance.
• Shim and load springs: Precision leaf springs used to set preload or clamp force in assemblies.
• Medical device springs: Clean, burr-free flat springs for instruments and disposable devices.
• Sensor flexures: Thin flexure springs for scales, load cells and micro-switch mechanisms.

Design Notes & Process Considerations

1. Arm versus thickness: Keep the narrowest arm at or above 1.5 × material thickness, or the arm will etch unevenly and weaken.
2. Bend relief: Add a small radius at the bend line to prevent cracking during forming; specify bend location on the drawing.
3. Grain direction: State the grain orientation relative to the bend axis, since fatigue life is better when the bend is across the grain.
4. Temper callout: Specify the final temper or heat treatment, as forming is usually done after etching on a softer condition.
5. Plating: Name the plating and thickness for contact areas; selective plating is available where only the tip needs gold.
6. Flatness: Call out flatness per 100 mm, since etched blanks arrive flat and must stay flat through forming. For leaf spring chemical etching, these six points on the drawing reduce back-and-forth.