In high-temperature environments, the contact reliability of terminal blocks faces multiple challenges. Metal contacts are prone to oxidation at high temperatures, leading to increased contact resistance; insulating materials may soften or release corrosive gases, damaging the internal structure; differences in thermal expansion coefficients can also cause contact loosening, or even connection failure. To address these challenges, a comprehensive approach is needed, encompassing material selection, structural design, surface treatment, heat dissipation optimization, and process control.
Material selection is fundamental to improving high-temperature reliability. Metal contacts must be made of oxidation-resistant, highly conductive materials, such as platinum group metals or composite plating structures. Platinum group metals maintain stable conductivity at high temperatures, while composite plating (such as a nickel underlayer with a gold surface layer) enhances the adhesion between the plating and the substrate, preventing cracking caused by thermal stress. Insulating materials must possess high heat resistance; engineering plastics such as polyimide, polyphenylene sulfide, or liquid crystal polymers are common choices. They not only have strong heat resistance but can also withstand mechanical stress, preventing softening and deformation. Sealing materials should be high-temperature resistant silicone or fluororubber. These materials maintain elasticity even above 200°C, effectively isolating dust and moisture.
Structural design must balance thermal expansion and contact stability. In high-temperature environments, differences in the coefficients of thermal expansion of different materials can lead to loosening of contact points or seal failure. Therefore, split or spring-loaded contacts can be used to compensate for displacement caused by thermal expansion and maintain contact pressure. The geometry of the contact surface needs to be optimized to avoid stress concentration caused by sharp edges and reduce the risk of crack propagation. Threaded locking or snap-fit designs must consider dimensional changes at high temperatures and can be used with high-temperature resistant locking adhesives or locking washers to improve connection stability. Furthermore, the number of insertion and removal cycles of terminal blocks must be considered during the design phase, and materials with excellent wear resistance should be selected to prevent accelerated mechanical wear at high temperatures.
Surface treatment is key to improving corrosion resistance. High-temperature environments accelerate metal oxidation, and the surface protective layer must have high corrosion resistance. Gold plating, silver plating, nickel plating, and other processes can form a dense oxide film, but the choice must be based on the specific temperature. For example, gold plating exhibits excellent performance below 150℃, but its hardness and adhesion decrease above this temperature. In such cases, a composite plating structure can be used, with nickel plating as the bottom layer to enhance adhesion. For chemical gas corrosion, targeted testing is necessary to screen for materials or coatings with stronger corrosion resistance.
Heat dissipation design is crucial for reducing high-temperature damage. Due to current flow and high external environmental temperatures, the internal temperature of terminal blocks is often higher than the ambient temperature, requiring heat dissipation measures to reduce the thermal load. Metal casing designs can increase the heat dissipation area, and internal heat sinks or thermal pads can accelerate heat conduction. Thermally conductive materials must also possess insulation properties to avoid short-circuit risks. In extreme high-temperature environments (such as engine compartments), active cooling methods, such as air cooling or liquid cooling, can be introduced in conjunction with the overall system cooling scheme to prevent heat buildup.
The manufacturing process directly affects the final performance of terminal blocks. The thickness and uniformity of the contact plating must be strictly controlled, and the heat-affected zones of riveting and welding processes must be properly treated to prevent localized overheating and performance degradation. Automated production lines and online monitoring technology ensure process consistency, allowing for real-time detection of coating thickness, contact pressure, and mechanical strength, and timely rejection of defective products. The quality management system needs to strengthen supply chain management to ensure stable material supply, regularly maintain production equipment, and reduce process deviations.
Improving the reliability of terminal blocks in high-temperature environments is a systematic project requiring coordinated optimization across materials, structure, surface treatment, heat dissipation, and processes. Through innovative design and technological upgrades, the high-temperature resistance of terminal blocks can be significantly enhanced, meeting the higher reliability requirements of industrial and consumer electronic equipment.
