EMC spring contacts or fingerstock are originally made of copper-beryllium (CuBe2) due to its unique combination of high electrical conductivity, excellent spring properties, and mechanical strength. This made it the gold standard for EMI/RFI shielding in demanding applications such as aerospace, defense, and telecommunications.
However, copper-beryllium can be toxic during processing and may pose health risks. Stricter regulations have limited its use in many sectors.
As safe alternatives, EMC spring contacts made from stainless steel (SS), titanium-copper (CuTi), and phosphor bronze (CuSn) fingerstock can be used, depending on the specific requirements of the application, such as conductivity, spring properties, corrosion resistance, and mechanical strength:
Comparison of Materials for Fingerstock
| Property | Copper-Beryllium (CuBe2) | Titanium-Copper (CuTi) | Phosphor Bronze (CuSn) | Stainless Steel (AISI-316) |
|---|---|---|---|---|
| Electrical Conductivity | ✅✅✅ Highest | ✅✅ High | ✅ Medium | ❌ Low |
| Mechanical Strength | ✅✅✅ Very Strong | ✅✅ Strong | ✅ Medium | ✅✅✅ Very Strong |
| Spring Properties & Elasticity | ✅✅✅ Excellent | ✅✅ Good | ✅ Fair | ✅✅ Good, but Stiffer |
| Corrosion Resistance | ✅✅ Good | ✅✅✅ Very Good | ✅✅✅ Very Good | ✅✅✅ Very Good |
| Wear Resistance & Durability | ✅✅✅ Very High | ✅✅ High | ✅ Medium | ✅✅✅ Very High |
| Safety | ❌ Harmful during processing | ✅ Safe | ✅ Safe | ✅ Safe |
| Cost | ❌ High | ✅ Medium | ✅✅ Low | ✅✅✅ Low |
Choose stainless steel options when strength, wear resistance, and extreme environmental resistance are required, and EMI shielding is less critical.
Choose titanium-copper fingerstock when high EMI shielding, flexibility, and spring properties are essential, and mechanical stress is less extreme.
Choose phosphor bronze for applications where a balance between cost and shielding is necessary.
These spring contacts are available in various standard strip lengths, in rolls, or custom cut. The surface can also be coated with finishes such as tin, zinc, nickel, gold, or silver.
