A Complete Guide to Copper Braid for Electrical Contact: From Basic Characteristics to Practical Tips

The industry commonly faces four major pain points when welding latching relay copper braids: First, copper has a high thermal conductivity of 401 W/(m·K), causing rapid heat loss during welding, making it difficult to form a stable weld nugget and easily leading to incomplete welds. Second, the hollow braided structure results in uneven heat and current distribution, easily causing localized overheating and underheating, leading to defects such as porosity and insufficient penetration. Third, an oxide film easily forms on the copper surface at room temperature, hindering current conduction and affecting the conductivity and weld strength of the joint. Fourth, when connecting with copper plates or copper busbars, the significant differences in thickness and heat capacity make it difficult to control thermal balance, easily resulting in problems such as one side burning through while the other side fails to fuse.

To address these pain points, resistance welding is the core welding method adapted to flexible copper connectors. Different processes correspond to different application scenarios, and accurate selection is key to successful welding. Spot welding is suitable for small-area, single-point fixing scenarios. It is simple to operate, highly efficient, and compatible with automated production lines. Care must be taken to control electrode pressure to avoid damaging the braided structure. Seam welding is suitable for scenarios requiring continuous sealing of the weld seam. Intermittent seam welding can create a continuous weld seam, balancing connection strength and conductivity while preventing overheating and burn-out. Resistance brazing is the preferred method for connecting precision electronic equipment. It uses silver-copper or copper-based brazing filler metals for heating and welding, resulting in low temperatures and minimal deformation, making it suitable for delicate and fragile Pure Copper Braids. Capacitor welding completes welding at millisecond speeds, producing uniform weld joints and a minimal heat-affected zone. It effectively solves the problem of rapid heat conduction and overheating in Bar Copper Braids, making it suitable for high-requirement scenarios.

Precise setting of welding parameters is key to reducing defect rates. The current and time need to be adjusted according to the cross-sectional size: 500-2000A is recommended for small cross-sections, and 5000-8000A for large cross-sections. Welding time should be controlled within 1-3 seconds, using a strict specification of short time, high current to reduce weld nugget size and indentation. Electrode pressure should be controlled between 200-500N, requiring real-time monitoring with a pressure sensor. Excessive pressure can flatten the braided structure, while insufficient pressure will lead to poor contact and surface burns. Chromium-zirconium copper electrodes are preferred, balancing conductivity and wear resistance. Welding temperature should be controlled between 1100-1200℃, using water-cooled electrodes to reduce cracking caused by thermal stress.

Equipment selection directly affects welding efficiency and stability. For Copper Braid for Latching Relay welding, a medium-frequency inverter DC welding machine is preferred. Its current control accuracy is ±2%, and it is equipped with temperature control (±5℃), continuously adjustable pressure (0.1-1.0MPa), and adjustable welding time (0.1-5s) to effectively ensure welding consistency. The electrodes should be equipped with a built-in circulating water cooling system to extend their service life and avoid damage due to high temperature.