Phosphor bronze chemical etching

Phosphor bronze chemical etching produces thin spring contacts, terminals and connector parts without burrs or mechanical stress. Because nothing shears or heats the strip, the temper, spring force and fatigue life of the alloy are the same after etching as before.

Why phosphor bronze is etched rather than stamped

Phosphor bronze is a copper-tin alloy with a small addition of phosphorus. It is chosen for its spring properties, fatigue resistance, conductivity and corrosion resistance. Stamping work-hardens the cut edge and leaves a burr, both of which matter on a small spring finger. Chemical etching removes metal without force, so thin fingers stay flat and behave as the material data sheet predicts.

Diagram of an etched phosphor bronze contact strip with carrier rails, tabs and half-etched fold lines, and a formed spring contact in side view — Contact fingers are etched in a carrier strip with half-etched fold lines, then formed.

Grades

Common spring grades include C5191 and C5210 (also specified as C51000 and C52100), supplied in tempers from half hard to extra spring hard. Etching does not change the temper, so the grade and temper are chosen for the function of the part.

Typical etched parts

Spring contacts and contact fingers
Battery contacts and terminals
Connector and switch parts
Grounding clips and EMI shielding fingers
Diaphragms, washers and shims
Lead frames and small precision springs

Thin photo etched contact strips held in carrier rails by tabs — Etched contact strips in carrier rails (example shown in nickel). Phosphor bronze parts are supplied in the same way.

Process notes

Etchant: phosphor bronze etches cleanly in ferric chloride or cupric chloride, like other copper alloys.
Bending: half-etched fold lines can be added to locate bends. State the rolling direction on the drawing, because spring tempers bend best across the grain.
Plating: etched parts are commonly plated with tin, nickel, silver or gold for solderability and contact resistance.
Thickness: we etch sheet from 0.05 mm to 5.0 mm; most contact parts use the thin end of this range.

Related materials

For other copper alloys see copper etching and brass etching. For solderable shielding parts see nickel silver etching and etched EMI and RF shielding. Design limits are in the chemical etching design guide.

Request a quote

Send your drawing in DXF, DWG, STEP or PDF format with the material and grade, thickness, quantity and required delivery date through our contact page. We check manufacturability against the drawing before tooling. Sample lead time is typically 3 to 7 working days. Drawings are treated as confidential.