Solid vs Bimetal Contact Rivets: Cost, Performance & Selection
When specifying contact rivets for relays, switches, or contactors, one of the first decisions is whether to use solid or bimetal construction. This choice affects cost, performance, manufacturing complexity, and thermal behavior.
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What Is a Solid Contact Rivet?
A solid contact rivet is made entirely from a single material—typically a silver alloy such as AgSnO2, AgNi, or pure silver—from the contact face through the shank.
Advantages: Maximum conductivity, uniform properties, no bond interface, excellent for welding.
Disadvantages: Highest material cost, heavier weight.
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What Is a Bimetal Contact Rivet?
A bimetal contact rivet consists of a silver alloy face bonded to a copper, brass, or steel base. The face handles the arc and current conduction, while the base provides structural support.
Advantages: 60–80% cost reduction, optimized material usage, good thermal performance, standard for volume production.
Disadvantages: Bond integrity must be verified, slightly higher thermal resistance at interface.
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Side-by-Side Comparison
| Criteria | Solid Rivet | Bimetal Rivet |
|---|---|---|
| Material cost | High (100% Ag alloy) | Low (Ag face + Cu base) |
| Conductivity | Maximum | Very good |
| Thermal performance | Excellent | Very good |
| Arc resistance | Same as face material | Same as face material |
| Mechanical strength | Moderate | Excellent |
| Weight | Heavier | Lighter |
| High-current (>50A) | Preferred | Acceptable |
| Cost-sensitive volume | Expensive | Economical |
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When to Choose Solid
Specify solid rivets when current exceeds 50A continuous, thermal management is critical, maximum conductivity is required, or high reliability with no bond interface risk is needed.
Typical applications: High-current circuit breakers, heavy-duty contactors, aerospace relays.
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When to Choose Bimetal
Specify bimetal rivets when cost reduction is a priority, current is below 50A, volume production requires material efficiency, or standard relay and switch applications.
Typical applications: Automotive relays, appliance switches, power relays, industrial contactors.
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Conclusion
For the vast majority of relay and switch applications, bimetal contact rivets offer the optimal balance of performance and cost. Solid rivets are justified only in high-current, high-reliability, or specialized applications.
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