Big head small foot type electrical contact: in-depth interpretation of the industry

Large-head and small-foot electrical contacts, as the name suggests, have a large contact area at one end (the "big head" part) and a relatively small contact area at the other end (the "small foot" part). The large head part is usually used as the main electrical contact surface, contacting the mating component to achieve current conduction. A larger contact area can reduce current density, reduce contact resistance, and thus reduce heat generation and energy loss. This is particularly important for applications that require high current transmission, such as circuit breakers, contactors, and other equipment in power systems. The small foot part is used to connect or install with other components. Its relatively small structural design may be to adapt to specific installation space restrictions, or to achieve a specific mechanical connection method to ensure that the Special Size Silver Contact is installed firmly in the equipment and does not occupy too much space. ​

Material for the large head part: Since the large head undertakes the main current conduction and Thick Layer Bimetallic Silver Contacts tasks, the material requirements are extremely high. Materials with high conductivity and good anti-welding properties are usually selected. Silver and its alloys are commonly used. Silver has extremely high conductivity and can effectively reduce contact resistance and heat generation. At the same time, silver alloy can improve its anti-welding performance and hardness by adding other elements, such as nickel and cadmium oxide. For example, in silver-cadmium oxide alloy, cadmium oxide particles are dispersed in the silver matrix. Under the action of the arc, the cadmium vapor generated by the decomposition of cadmium oxide can suppress the arc energy, thereby reducing the welding phenomenon on the contact surface and improving the service life of the Shaped Silver Alloy Contacts. On some occasions, with high environmental protection requirements, cadmium-free materials such as silver-tin-indium oxide are also used to replace silver-cadmium oxide alloy. ​

Material for the small foot part: In addition to having a certain conductivity, the small foot part also needs to have good mechanical strength and machinability to meet the needs of connection and installation. Common materials include copper alloys, such as beryllium bronze and tin bronze. Beryllium bronze has high strength, high elasticity, good conductivity and thermal conductivity, and excellent fatigue resistance. It is very suitable for the small foot part of the Short Foot Bimetal Electronic Contacts that needs frequent operation, and can ensure that the connection part of the Allotype Solid Copper Contact Rivet will not be damaged by mechanical stress during long-term use. Tin bronze has good casting performance and friction reduction performance, and is more common in some applications that are more sensitive to cost.​

Big head part: For the big head part, powder metallurgy or stamping molding is often used. Powder metallurgy is to make metal powder (such as silver powder, alloy powder, etc.) into a compact with a certain shape and performance through mixing, pressing, sintering, and other steps. This process can accurately control the composition and density of the material, obtain a uniform organizational structure, and thus improve the performance consistency of the Thick Head Bimetal Contact. The stamping molding process is suitable for some large-head contacts with less complex shapes, by stamping the metal sheet into the required shape in the mold. The advantages of stamping molding are high production efficiency and relatively low cost, but for some PCB Circuit Board Riveted Contact with Steps with complex shapes, subsequent processing procedures may be required to meet the accuracy requirements. ​

Small foot part: The small foot part is generally manufactured by mechanical processing (such as turning, milling, etc.) or die casting. Turning and milling can accurately process small feet of various shapes and sizes to meet different installation requirements. Die casting is to inject liquid metal (such as copper alloy) into the mold cavity under high pressure, and form the required small foot shape after cooling and solidification. Die casting has high production efficiency and is suitable for mass production, but it has high requirements for molds and high initial mold development costs. ​

Connection process: After the big head and small foot parts are manufactured, they need to be connected. Common connection processes include brazing and resistance welding. Brazing is the use of a brazing material with a lower melting point than the parent material. At a temperature lower than the melting point of the parent material and higher than the melting point of the brazing material, the big head and small foot are connected through the wetting and capillary action of the liquid brazing material. Different brazing materials can be selected for brazing to meet different electrical and mechanical performance requirements. Resistance welding generates resistance heat by passing current through the connection between the big head and the small foot, so that the metal at the Electrical Contacts Big Head Small Foot part melts instantly and connects. The advantages of resistance welding are fast welding speed and high joint strength, but the control requirements for welding equipment and process parameters are relatively strict. ​