Industry Knowledge and Technical Details of Trimetal Rivet Contacts

Trimetal Rivet Contacts, also known as tri-metal rivet contacts, are a high-end composite product among electrical contact elements. They are not made of a single metal, but rather through a special metallurgical process that firmly bonds three metal materials with different properties together to form a unified rivet-like structure.

A typical three-layer structure includes:

Contact Layer: The working end of the Electrical Trimetal Rivet Contacts, serving as the contact function, is usually made of silver or a silver alloy (such as silver-tin oxide or silver-zinc oxide). This layer directly handles the connection and disconnection of current, therefore requiring excellent conductivity, resistance to arc erosion, resistance to welding, and corrosion resistance.

Intermediate Layer: Serving as a barrier layer of the Trimetallic Relay Contacts, it typically uses nickel or a nickel-copper alloy. This layer is one of the core technologies; its main function is to prevent the interdiffusion of atoms between the upper and lower metal layers during high-temperature processing or use, preventing the formation of a brittle phase, thereby ensuring the long-term stability and conductivity of the composite interface.

Base Layer: Serving as the support and riveting component of the Trimetal Contact Rivets, this layer typically uses copper or copper alloys (such as brass or copper) with good conductivity and low cost. This layer provides mechanical support for the contacts and, utilizing its good plastic deformation capacity, is fixed to moving parts such as the relay's spring or armature through riveting.

Composite Rolling and Composite Methods: This is the mainstream manufacturing method for Trimetal Moving Contacts. Through processes such as explosive bonding, rolling bonding, or extrusion bonding, a three-layer composite plate or strip of silver/nickel/copper is first prepared. This process requires precise control of parameters such as pressure and temperature to ensure a strong metallurgical bond between the layers, rather than simple physical adhesion.

Precision Cold Heading: The aforementioned three-layer composite strip is fed into a high-precision cold heading machine, where it is punched, drawn, and formed using multi-station dies, initially creating the prototype of the Electrical Trimetal Rivet Contacts. This process has high material utilization, high production efficiency, and can improve product strength through cold work hardening.

Precision Turning and Finishing: For Trimetal Rivet Contacts requiring extremely high dimensional accuracy and surface finish, a precision turning process is performed after cold heading. This process ensures that the spherical curvature of the contact head, dimensional tolerances, and root angle meet the drawing requirements, guaranteeing accurate and stable contact with the mating component.

Heat Treatment and Surface Treatment: Depending on the material properties, annealing may be required to eliminate internal stress and adjust hardness. Finally, to ensure Trimetallic Relay Contact cleanliness and prevent oxidation of the underlying copper, cleaning, passivation, or an extremely thin plating treatment is typically performed.

Material standards: The raw materials involved, such as silver, copper, and nickel, must comply with the corresponding national standards.

Performance Testing: Key inspection items include dimensions and tolerances, bond strength, contact resistance, hardness, and observation of the interfacial metallographic structure under a high-power microscope.

Environmental Requirements: Trimetal Rivet Contacts must comply with RoHS directives and other domestic and international regulations regarding the restriction of hazardous substances.