BeCu vs. Phosphor Bronze vs. Stainless Steel for Spring Contacts
Spring contacts appear in connectors, switches, battery packs and consumer devices. The material choice affects contact resistance, spring force, fatigue life and cost. Beryllium copper, phosphor bronze and stainless steel are common, but they are not interchangeable.
This comparison focuses on the properties that matter for stamped contacts and the situations where each material makes sense.
Comparison
| Property | BeCu C17200 | Phosphor bronze C5191/C5210 | Stainless 301 |
|---|---|---|---|
| Conductivity | High (~22-28% IACS) | Moderate (~11-15% IACS) | Very low (~2-3% IACS) |
| Strength | High | Moderate | High when work-hardened |
| Fatigue life | Good | Good | Moderate |
| Stress relaxation | Good at moderate temperature | Moderate | Moderate |
| Springback | Moderate | Moderate | High |
| Corrosion | Good; plating often used | Good | Good |
| Cost | Higher | Lower | Low |
When to choose BeCu
- Low contact resistance is required.
- The contact must carry current and act as a spring.
- High cyclic life or resistance to stress relaxation is important.
- The design is space-constrained and needs high strength in a thin section.
When to choose phosphor bronze
- Moderate conductivity is acceptable.
- Cost is a major driver.
- The contact force and deflection are moderate.
- The environment is benign and plating provides corrosion protection.
When to choose stainless steel
- The part is structural rather than conductive.
- Corrosion resistance and strength matter more than conductivity.
- No electrical current passes through the spring.
Plating and contact resistance
Plating can change the ranking. Gold over nickel provides low, stable contact resistance; tin is lower cost but can oxidize and has higher contact resistance. Silver has excellent conductivity but can tarnish. The mating surface and the environment should drive the plating choice.
FAQ
Can phosphor bronze replace BeCu?
Sometimes, if the current is moderate and the spring stress is low enough. It is not a drop-in replacement for high-current or high-cycle contacts.
Is stainless steel suitable for battery contacts?
Usually not for the conductive path, because its conductivity is low. It may be used for structural springs or as a substrate with plating.
Does plating increase spring force?
Plating adds a thin layer and can slightly affect friction and contact resistance, but it is not a substitute for changing the spring geometry.
Related: spring contacts and request a material recommendation.
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