Cost-Down Strategy for Electrical OEMs: How Bimetal and Trimetal Silver Rivets Reduce Material Costs

Bimetal and trimetal silver contact rivets replace high-cost solid silver contacts by using a silver alloy contact layer combined with copper or brass base materials. Through precision cold heading, metallurgical bonding, and controlled silver layer thickness, manufacturers achieve equivalent electrical performance while reducing precious metal consumption by 30–70%.

 

For electrical OEMs requiring millions of switching cycles, the key engineering factors are not silver volume alone but contact resistance stability, interface bonding strength, arc erosion resistance, and compliance with IEC electrical endurance requirements.

 

 

 

Silver remains the preferred contact material for relays, contactors, circuit breakers, and switching components because of its:

Electrical conductivity: 106% IACS for pure silver
Low contact resistance: typically <1mΩ under rated current conditions
High thermal conductivity: 429 W/(m·K)
Excellent arc erosion resistance

 

However, silver price fluctuations directly increase electrical component manufacturing costs. For high-volume applications such as:

EV high-voltage contactors
Battery management relays
Smart meters
Industrial control relays
Solar inverter switching modules

Solid silver contacts create unnecessary material consumption.

A typical solid silver rivet contains precious metal throughout the entire cross-section, although only the contact surface participates in electrical switching.

 

The engineering solution is replacing solid silver rivets with:

Bimetal silver contact rivets
Trimetal contact points
Silver alloy composite rivets

These structures place silver only where electrical performance is required while using C1100 pure copper or C2680 brass as the structural core.

 

Material Cost Comparison Under Same Contact Diameter

Contact Type	Structure	Silver Usage	Electrical Performance	Typical Application
Solid Silver Rivet	100% Ag material	100%	Excellent conductivity	Low-volume precision relays
Bimetal Silver Rivet	Ag + Cu core	30–50% reduction	Comparable contact resistance	EV relays, contactors
Trimetal Contact Rivet	Ag alloy + intermediate layer + Cu/Brass core	50–70% reduction	Improved mechanical stability	High-cycle switching devices

 

 

Multi-Metal Cold Heading Process Control With ±0.01mm Dimensional Tolerance

The manufacturing principle of bimetal and trimetal contact points relies on precision cold heading rather than mechanical assembly.

The process includes:

 

Silver wire preparation
Copper/brass core wire feeding
Multi-layer material positioning
Cold heading deformation
Head forming
Surface finishing
Electrical and mechanical inspection

During cold heading, high-pressure plastic deformation creates intimate contact between different metals.

 

Unlike adhesive bonding, the interface depends on:

Plastic deformation pressure
Material hardness matching
Interface cleanliness
Grain flow continuity

 

Apollo Electronic Components applies controlled cold heading parameters to maintain:

Diameter tolerance: ±0.01mm
Rivet height tolerance: ±0.02mm
Silver layer thickness tolerance: ±0.005mm
Automatic optical inspection accuracy: ±0.01mm

Bimetal vs Trimetal Contact Structure

Structure	Material Combination	Main Advantage	Limitation
Bimetal Rivet	Ag/Cu or Ag/Brass	Lower material cost, simple production	Limited interface optimization
Trimetal Rivet	Ag alloy/Ni/Cu or Ag/Cu/Brass	Better bonding and mechanical strength	Higher process complexity
Solid Silver Rivet	Pure Ag	Maximum conductivity	High material cost

 

 

Electrical OEMs evaluate contact rivets based on long-term switching reliability rather than material composition alone.

Key validation parameters include:

Initial contact resistance
Temperature rise
Arc erosion
Mechanical impact resistance
Welding resistance
Electrical endurance cycle testing

Electrical Performance Comparison

Test Parameter	Solid Silver Contact	Bimetal Silver Contact	Trimetal Contact Point
Electrical Conductivity	100% Ag reference	95–100% equivalent at contact surface	95–100% equivalent
Contact Resistance	<1mΩ	<1mΩ	<1mΩ
Temperature Rise Control	Excellent	Equivalent after optimization	Equivalent
Silver Consumption	High	Reduced 30–50%	Reduced 50–70%
Mechanical Strength	Medium	High	Higher
Cost Stability	Poor	Better	Best

 

Interface Bonding Strength Controls Contact Reliability

The most common failure mode of composite contacts is silver layer separation caused by:

Insufficient deformation pressure
Surface contamination
Incorrect material hardness matching
Poor interface design

 

Apollo controls bonding quality through:

Cross-section metallographic inspection
Pull-off strength testing
Shear strength testing
CMM dimensional inspection
Electrical resistance testing

 

For high-reliability applications, bonding interfaces are evaluated to ensure:

No visible delamination
No cracks after deformation
Stable resistance after thermal cycling

 

Request Free DFM Evaluation & Quote

 

 

Mass production of bimetal and trimetal contact points requires stable process capability rather than individual part inspection.

 

Apollo Electronic Components integrates:

Precision cold heading machines
Automatic feeding systems
Inline optical inspection
CMM measurement
Material traceability management

Production quality follows automotive supply chain requirements:

IATF 16949 quality management system
PPAP Level 3 documentation
ISO 14001 environmental management
RoHS and REACH compliance

Cold Heading Process Control Parameters

Process Item	Control Standard
Material Composition	ICP chemical analysis
Rivet Diameter	±0.01mm
Head Height	±0.02mm
Silver Layer Thickness	±0.005mm
Surface Defects	AOI 100% inspection
Batch Traceability	Full production record

 

Material Selection: C1100 Copper vs C2680 Brass Core

The core material determines mechanical strength, conductivity, and forming performance.

 

Material	Conductivity	Mechanical Property	Application
C1100 Pure Copper	100% IACS	High conductivity, softer	High-current contact applications
C2680 Brass	25–30% IACS	Higher hardness, better forming	Mechanical switching contacts
Copper Alloy	50–90% IACS	Balanced performance	Customized contact designs

 

 

 

Apollo Electronic Components provides OEM manufacturing support for:

Bimetal silver contact rivets
Trimetal contact points
Relay contact assemblies
High-current switching components

 

The production advantages include:

Precision Composite Forming
Multi-layer metal feeding technology
Stable silver layer distribution
Controlled deformation ratio
Continuous production capability

Engineering Support Before Mass Production

Apollo supports:

Material selection analysis
Contact structure optimization
Drawing review
DFM evaluation
Prototype validation
PPAP Level 3 submission

Typical Application Fields
EV DC contactors
Battery charging systems
Energy storage PCS equipment
Solar inverter relays
Industrial electrical control systems

 

 

What is the typical silver material reduction when using bimetal silver contact rivets?

Bimetal silver contact rivets reduce silver consumption by approximately 30–50% compared with solid silver rivets while maintaining contact resistance below 1mΩ.

 

Can Apollo provide PPAP Level 3 documentation for trimetal contact point production?

Yes. Apollo provides PPAP Level 3 documentation, material traceability records, dimensional inspection reports, and quality validation data for automotive customers.

 

What tests verify bonding quality between silver and copper layers?

Bonding quality is verified through metallographic cross-section analysis, pull-off testing, shear testing, and electrical resistance stability evaluation.