Brass, Copper or Phosphor Bronze? Choosing Material for Stamped Electrical Terminals
Electrical terminals, contacts and lugs are among the most common progressive-stamped parts. The material decides how well the part conducts, how well it holds contact pressure, how easily it forms and what it costs. Here is how the three most common choices compare.
The quick comparison
| Property | Copper (ETP) | Brass (CuZn30) | Phosphor bronze |
|---|---|---|---|
| Electrical conductivity (approx. % IACS) | ~100% | ~28% | ~15% |
| Spring / contact force | Low | Moderate | High |
| Formability | Excellent | Very good | Good |
| Relative material cost | High | Lower | Highest of the three |
| Typical use | Lugs, busbars, high-current links | Terminals, sockets, general contacts | Spring contacts, connectors, clips |
Values are approximate and vary by exact grade and temper. Always confirm with your material supplier.
Copper: when current matters most
Copper has the best conductivity of the common choices, so it runs coolest at high current. It is soft and forms easily. The trade-off is that it has little spring. A copper contact that is bent open does not push back firmly, so it suits lugs, busbars and links more than spring contacts.
Brass: the economical all-rounder
Brass has lower conductivity than copper but costs less, stamps cleanly and forms well. It is the usual choice for terminals, sockets and general-purpose contacts where current is moderate. The temper (soft, half-hard, hard) changes how it bends and how springy it is, so specify it on the drawing.
Phosphor bronze: when it must spring back
Phosphor bronze has excellent spring properties and fatigue resistance. That makes it the standard choice for contacts that must keep pressure through many insertions, such as connector contacts and clips. Its conductivity is lower, so it is not ideal for high-current paths.
Don't forget plating
Bare copper alloys oxidise, which raises contact resistance over time. Terminals are usually tin plated, with nickel or silver used for more demanding applications. There are two routes:
- Pre-plated strip: cheaper and faster, but the cut edges are left unplated.
- Post-plating after stamping: fully covers the part but adds cost and handling.
Stamping considerations
- Burrs matter. On electrical parts, a burr can cause a short circuit or damage the mating part. See Controlling Burrs in High Speed Stamping.
- Bend direction vs grain. Harder tempers crack more easily when bent along the rolling direction. The strip layout should account for this.
- Thin material needs fine clearances. Accurate punches and dies cut on CNC wire cut EDM keep edges clean on thin strip.
We build progressive tools and stamp terminals and contacts for electrical manufacturers. See the industries we serve, or send your drawing and we'll advise on material and tooling.