What Is an Electrical Contact Rivet?

An electrical contact rivet is a rivet-shaped component with a conductive contact face—typically made from a silver alloy such as AgSnO₂, AgNi, or AgCdO—that is staked, welded, or pressed onto a conductive base material such as copper, brass, or steel. The rivet geometry allows the contact face to be positioned precisely within a switching mechanism, creating a reliable electrical path when the contact closes.

The term “rivet” refers to the manufacturing form: a cylindrical shank with a formed head. In mass production, contact rivets are typically installed by automated staking, resistance welding, or orbital riveting machines that bond the contact to a carrier blade, terminal, or spring.

Key Characteristics

  • Electrical conductivity: The contact face must carry rated current with minimal voltage drop and heat generation.
  • Arc resistance: During switching, arcs erode the contact surface. Material selection directly determines contact life.
  • Anti-welding properties: Under high inrush currents (e.g., motor starting, lamp switching), contacts must resist fusion (welding) upon closure.
  • Mechanical durability: Contacts must withstand mechanical impact and sliding friction over millions of operations.
  • Regulatory compliance: With RoHS II phasing out cadmium-containing contacts by July 2025, material selection now involves both performance and compliance considerations.

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How Electrical Contact Rivets Work

The function of a contact rivet is deceptively simple but engineering-critical:

  1. Mounting: The rivet shank is inserted through a hole in a copper or steel carrier (blade, spring, or terminal).
  2. Securing: The shank is mechanically staked, welded, or cold-headed to create a permanent bond with the carrier.
  3. Switching: When the switch or relay closes, the contact face presses against a mating contact surface, creating an electrical path.
  4. Arcing: When the circuit opens, an arc forms across the separating contacts. The contact material must withstand this arc without excessive erosion, material transfer, or welding.
  5. Heat dissipation: During operation, resistive heating (I²R losses) at the contact interface must be conducted away through the rivet and carrier to prevent overheating.

The design of the contact rivet—its head diameter, thickness, shank length, and material composition—must be matched to the application’s current rating, switching frequency, load type (resistive, inductive, or capacitive), and environmental conditions.

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Main Types of Electrical Contact Rivets

Electrical contact rivets are categorized by construction method, which determines cost, performance, and manufacturing efficiency.

1. Solid Contact Rivets

Solid contact rivets consist entirely of a single silver alloy, from the contact face through the shank. They offer maximum conductivity and thermal mass, making them ideal for high-current applications where heat dissipation is critical.

Key features:

  • Uniform material properties throughout the rivet
  • Highest electrical and thermal conductivity
  • Excellent for welding to copper carriers
  • Maximum durability under heavy arcing

Best for: High-current circuit breakers, heavy-duty contactors, industrial relays, and applications where the full cross-section must carry current.

Common materials: Pure silver (FAg), AgNi, AgSnO₂, AgCdO (legacy), AgW.

Browse our range of solid silver contact rivets for high-current applications.

2. Bimetal Contact Rivets

Bimetal contact rivets are the industry standard for cost-effective, high-volume production. They consist of a thin working layer (face material) of silver alloy bonded to a base material such as copper, brass, or CuNi. The base provides structural support and electrical conductivity at a fraction of the cost of solid silver.

Key features:

  • Silver alloy placed only where the arc occurs—optimal material utilization
  • Base material (Cu, brass, CuNi) provides mechanical strength and conductivity
  • Significantly lower cost than solid silver rivets
  • Manufactured by cold bonding or internal oxidation on high-speed machines

Common face/base combinations:

Face Material Base Material Best Application
AgSnO₂ Cu / CuNi EV charging, industrial contactors, motor controls
AgNi Cu / Brass Household relays, appliance switches, signal relays
AgCdO (legacy) Cu / CuNi Heavy inductive loads (being phased out)
Pure Ag Cu Low-current precision relays, timers
AgW Cu High-voltage breakers, short-circuit duty

Best for: Automotive relays, appliance switches, power relays, contactors, and any application requiring a balance of performance and cost.

Explore our bimetal contact rivet catalog with custom face/base combinations.

3. Trimetal Contact Rivets

Trimetal rivets add an intermediate layer between the silver face and the base material—typically a copper or nickel layer—to improve bonding, reduce diffusion, and enhance thermal performance. This construction is used when the face and base materials have significantly different thermal expansion coefficients or when additional barrier properties are required.

Best for: High-reliability aerospace relays, critical industrial contactors, and applications with extreme thermal cycling.

4. Composite / Clad Contacts (Non-Rivet)

While not rivets in the traditional sense, clad and inlay contacts are worth mentioning as alternatives. These are produced by rolling or bonding a silver alloy strip onto a copper or steel strip, then stamping the final contact shape. They are used in very high-volume applications where riveting is not practical.

Best for: Miniature PCB relays, microswitches, and consumer electronics where automated SMD assembly is required.

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Contact Materials: Selection Guide

Material selection is the most critical decision in contact design. The right alloy depends on load type, current, switching frequency, and regulatory requirements.

AgSnO₂ (Silver-Tin Oxide)

AgSnO₂ has become the dominant replacement for AgCdO under RoHS regulations. It offers excellent arc erosion resistance and anti-welding properties, particularly under high inrush currents.

Key properties:

  • Excellent anti-welding performance under motor and lamp loads
  • Good arc erosion resistance; life 1.5–3× longer than AgNi in inductive DC applications
  • Harder than AgNi; slightly higher contact resistance
  • Environmentally friendly; RoHS-compliant

Common compositions: AgSnO₂ 92/8, 90/10, 88/12, 85/15. Often doped with In₂O₃ or Bi₂O₃ to reduce temperature rise.

Best for: EV charging relays, solar inverters, industrial contactors, motor controls, power relays under inductive/capacitive loads.

View our AgSnO₂ contact materials with custom oxide content ratios.

AgNi (Silver-Nickel)

AgNi is the most economical silver alloy for general-purpose switching. It offers low contact resistance and good processability, making it the workhorse material for high-volume relay production.

Key properties:

  • Low cost; excellent value for resistive loads
  • Low contact resistance (< 2 mΩ typical)
  • Easy to process on automated riveting and welding lines
  • Less suited for heavy inductive loads compared to AgSnO₂

Common compositions: AgNi 90/10, 85/15, 80/20.

Best for: Household appliance relays, signal relays, automotive auxiliary relays, light-duty switches (< 30 A resistive).

AgCdO (Silver-Cadmium Oxide) — Legacy

AgCdO was historically the gold standard for high-inrush inductive loads due to its exceptional anti-welding and arc-quenching properties. However, cadmium is toxic and restricted under RoHS II.

Key properties:

  • Best anti-welding performance of all silver alloys
  • Excellent arc erosion resistance
  • Restricted under RoHS; general-use exemption expires July 2025

Best for: Legacy replacement only. New designs should specify AgSnO₂ or AgSnO₂In₂O₃.

Transitioning from AgCdO? Contact our engineering team for AgSnO₂ compatibility analysis.

Pure Silver (Ag / FAg)

Fine grain silver (FAg, > 99.85% Ag with 0.15% Ni) offers the highest electrical conductivity of all contact materials.

Key properties:

  • Highest conductivity and lowest contact resistance
  • Soft; prone to mechanical wear and material transfer under arcing
  • Best for low-current, low-wear applications

Best for: Signal relays, timer contacts, precision switches, low-current control circuits.

AgW (Silver-Tungsten)

AgW composites combine the arc resistance of tungsten with the conductivity of silver. Produced by powder metallurgy, these materials handle extremely high currents and short-circuit conditions.

Key properties:

  • Extreme hardness and arc erosion resistance
  • Higher contact resistance (10–20 mΩ)
  • Handles hundreds to thousands of amps
  • Expensive; used only where necessary

Best for: High-voltage circuit breakers, heavy motor controls, short-circuit duty applications.

AgC (Silver-Graphite)

AgC contains 5–10% graphite, providing self-lubrication during arcing. This prevents material transfer and welding, making it ideal for DC switching.

Best for: EV pre-charge relays, battery disconnect switches, DC circuit breakers (e.g., 60 VDC / 50 A).

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Key Applications by Industry

Power Relays & Contactors

Industrial and automotive relays rely on bimetal contact rivets for cost-effective, high-reliability switching. AgSnO₂ dominates new designs for inductive motor loads, while AgNi remains standard for resistive and light-duty applications. Contact life requirements typically range from 100,000 to 1,000,000 operations.

Circuit Breakers

Circuit breakers demand contacts that can carry rated current continuously while withstanding short-circuit currents during fault interruption. Solid AgW or AgNi contacts are common in molded-case breakers (MCB, MCCB), while air circuit breakers (ACB) may use larger composite contacts.

Automotive Electronics

Modern vehicles contain dozens of relays controlling lighting, HVAC, fuel pumps, and power windows. AgSnO₂ and AgNi contact rivets are standard in 12 VDC and 48 VDC automotive relay designs. The shift to electric vehicles has increased demand for DC-rated contact materials capable of handling higher voltages and inrush currents.

EV Charging Infrastructure

EV charging piles and onboard chargers require relays and contactors that switch high DC currents (up to 350 A at 1000 VDC) under inductive loads. AgSnO₂In₂O₃ and AgC contacts are increasingly specified for these demanding applications.

Solar & Energy Storage Inverters

Solar inverters and battery energy storage systems (BESS) require high-reliability switching with minimal contact resistance to maximize efficiency. AgSnO₂ and AgNi contacts are standard in DC contactors used to isolate battery strings and inverter stages.

Household Appliances

Washing machines, refrigerators, air conditioners, and water heaters use AgNi or AgSnO₂ contact rivets in thermostat controls, motor relays, and heater switches. Cost-sensitive designs favor bimetal construction to minimize silver usage.

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How to Choose the Right Contact Rivet

Selecting the optimal contact rivet requires balancing electrical performance, mechanical requirements, regulatory compliance, and cost.

  1. Load type: Resistive loads favor AgNi for its low cost and low resistance. Inductive or capacitive loads (motors, lamps, transformers) require AgSnO₂ or AgSnO₂In₂O₃ for anti-welding and arc resistance.
  2. Current rating: Higher currents demand larger contact faces and materials with better thermal conductivity. Consider solid rivets for currents above 50 A.
  3. Switching frequency: High-frequency switching (e.g., PWM contactors) accelerates contact erosion. Specify harder materials like AgSnO₂ or AgW.
  4. Voltage and load type: DC switching is more demanding than AC due to the absence of current zero-crossings. DC applications above 24 V often require AgC or specially formulated AgSnO₂.
  5. Regulatory compliance: Ensure your contact materials meet RoHS, REACH, and any customer-specific environmental requirements. AgCdO should no longer be specified for new designs.
  6. Construction type: Bimetal rivets offer the best cost-performance ratio for most applications. Solid rivets are justified for high-current or high-reliability designs. Trimetal rivets address bonding challenges between dissimilar materials.
  7. Manufacturing compatibility: Ensure the contact rivet geometry and base material are compatible with your staking, welding, or riveting equipment.

Need help selecting contact materials for your application? Request a free technical consultation.

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Conclusion

Electrical contact rivets are far more than simple fasteners—they are precision-engineered components that determine the reliability, safety, and lifetime of electrical switching devices. Whether you need the arc resistance of AgSnO₂ for inductive motor controls, the economy of AgNi for household relays, or the extreme durability of AgW for circuit breakers, the right contact material and construction type make the difference between a product that lasts decades and one that fails prematurely.

As the industry transitions away from cadmium-containing contacts under RoHS II, AgSnO₂ and its doped variants have established themselves as the new standard for demanding applications—offering performance that meets or exceeds legacy AgCdO in most use cases.

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Get a Quote for Your Contact Rivet Requirements

At ContactRivets, we manufacture and supply a comprehensive range of electrical contact rivets, contact components, and contact materials including AgSnO₂, AgNi, AgW, pure silver, and custom silver alloys. We serve relay manufacturers, switch producers, circuit breaker OEMs, and automotive Tier-1 suppliers worldwide.

Our capabilities include:

  • Solid, bimetal, and trimetal contact rivets
  • Custom head geometries and shank dimensions
  • Material formulation to your exact AgSnO₂, AgNi, or AgW specification
  • RoHS-compliant and REACH-certified materials
  • High-volume production with consistent quality

Contact us today for competitive pricing, material samples, and engineering support.

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