Welding is one of the most core joining processes in metalworking. It achieves atomic-level metallurgical bonding of workpiece materials through the application of heat, pressure, or a combination of both. In industries such as electrical contact manufacturing, mechanical structures, automotive, aerospace, and new energy equipment, welding technology directly determines the product's electrical conductivity, mechanical strength, and long-term stability. With the continuous development of technologies such as brazed electrical contacts and contact welding, modern welding has evolved beyond structural joining to become a crucial processing method for highly conductive functional components.
Arc Welding-A Universal Welding Method Core to Arc Heat
Arc welding utilizes arc heat generated between the electrode and the workpiece to simultaneously melt the base material and the welding wire (or rod), forming a weld. This method is the most widely used, accounting for over 60% of all industrial welding. Based on electrode type, it can be categorized as manual metal arc welding, gas shielded arc welding (GMAW/MIG/MAG), and submerged arc welding (SAW).
Manual Metal Arc Welding (SMAW): A coated electrode is used as the electrode. The electrode coating burns to form a shielding gas and slag, preventing oxidation. While simple equipment and low cost are required, the welder's skill is highly dependent on the welder's skill.
Gas Shielded Metal Arc Welding (GMAW): A shielding gas (such as Ar or Ar+CO₂) stabilizes the arc, resulting in well-formed welds and minimal spatter. It is widely used in automotive manufacturing and stainless steel welding.
Submerged Arc Welding (SAW): Performed under flux, it is suitable for efficient welding of thick plates and large structures.
These methods are not only applicable to steel structure fabrication but are also commonly used for pre-welding of highly conductive components, providing structural support for components such as electrical contact assemblies and silver contact brazed assemblies.
Resistance Welding-A Rapid Joining Process Core to "Resistance Heat"
Resistance welding (RSW) achieves a metal-melting connection through resistance heating at the workpiece contact point. It boasts high efficiency, requires no welding wire, and consumes minimal energy. It is particularly suitable for spot welding and stitch welding of highly conductive materials such as copper, silver, and nickel in the electrical industry.
Spot welding (RSW)
Using welding clamp electrodes to apply pressure and pass high current, it melts and forms a "nugget." This process is widely used in the production of electrical switches and relay contacts, including copper spot welding, resistance projection welding, and resistance butt welding.
Seam welding (RSEW)
Using a roller electrode for continuous welding creates a hermetic weld seam, suitable for metal containers requiring airtight or liquid-tight sealing.
AC resistance welding (AC resistance welding)
Using the cyclical nature of AC to control heat input, it effectively reduces spatter and is suitable for precision welding of electrical silver contact tip assemblies.
Resistive Welding Silver Contact technology is particularly critical in the electrical industry, achieving a secure bond between highly conductive silver contacts and the copper substrate, ensuring low contact resistance and long-life performance.
Brazing: A high-precision joining process centered around "low-melting-point solder"
Brazing is a process that achieves a metallurgical bond by melting the solder without melting the base metal. It is particularly suitable for joining dissimilar metals, such as brazing silver contacts to copper bars or brazing silver contacts on copper bars. Brazing is categorized into soft soldering and hard soldering based on the temperature.
1. Soldering
Using a solder with a melting point below 450°C (such as tin-lead alloys and silver-tin alloys), it is widely used in the electronics and electrical industries. Silver soldering, or silver solder, ensures smooth, porosity-free electrical connections with strong corrosion resistance. It is suitable for the manufacture of small electrical contact assemblies.
2. Brazing
Using silver-based brazing filler metals or copper-zinc alloys with a melting point above 450°C, brazing is a core process in the manufacture of brazed electric and electrical contacts. By controlling the temperature and gap (typically 0.05-0.15mm), high-strength joints can be achieved, meeting the requirements of applications with high current density and high thermal conductivity.
Brazing is particularly important in the manufacture of brazing contacts for MCCBs (molded case circuit breakers). Electrical contact resistance brazing (ECR) or contact joining brazing techniques achieve a stable, low-resistance, high-strength connection between silver contacts and copper conductors.
Laser Welding: High-Energy Density, High-Precision Connections
Laser welding uses a high-energy laser beam to locally heat and melt the metal, forming an extremely small molten pool. It offers high precision, minimal distortion, and high speed. Laser welding produces clean, porosity-free welds for complex components such as miniature electrical contacts or silver and copper welded button contacts.
In the electrical contact industry, laser welding is often combined with the brazing of electrical contacts to produce highly reliable conductive components. Its minimal heat-affected zone makes it ideal for welding composite materials with high thermal conductivity, such as silver and copper.
Application Selection of Welding Processes in Electrical Contact Manufacturing
The selection of different welding methods requires a comprehensive consideration of material, thickness, structural form, and conductivity requirements:
| Requirement Type | Recommended Welding Process | Typical Applications |
| High-Conductivity | Silver-Copper Contact Brazing on Copper Bars / Brazing Silver Contacts to Copper Bars | Circuit breakers, relays, and contactor contacts |
| High-Frequency, Low-Resistance Connections | Electric Resistance Spot Welding Silver Contact Low-Voltage Electrical Components | Electric Vehicle Relays |
| Precision Dissimilar Material Connections | Contact Joining Brazing / Brazed Contacts | Precision Relays, Sensor Terminals |
| High-Strength Joints | Resistance Projection Welding Silver Contact Electrical Contacts | Load Switch Components |
| Micro-Components | Silver Soldering / Silver Solder PCB Solder Joints | Electrical Connectors |
By appropriately selecting a welding method, the conductivity of electrical contact assemblies can be improved while significantly enhancing reliability and production consistency.
Development Trends and Intelligent Directions
With the increasing automation of brazing electrical contacts and contact welding, welding technology is evolving towards intelligent and integrated processes. Modern manufacturing is achieving fully automated control of the silver contact brazed assemblies process through robotic welding and vision monitoring. In the future, AC resistance welding of silver contacts and laser-brazing hybrid processes will become important trends in high-end electrical contact manufacturing.
Summary
Welding technology is the core foundation for both connection performance and electrical conductivity. From traditional arc welding and resistance welding to modern electrical contact resistance brazing and silver contact brazing on copper bars, each process evolution is driving the electrical industry towards a more efficient, reliable, and environmentally friendly manufacturing future.
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