Do you know the three types of tin plating&connection of terminals?

- 2022-11-19-

Terminal blocks are common components for connecting circuits. It is mainly used as an electrical connection and signal transmission between equipment and components, components and cabinets, and systems and subsystems, and tries to prevent signal distortion and energy loss between systems. Terminal blocks are widely used in computer, telecommunications, network communication, industrial electronics, transportation, aerospace, medical equipment and automobile industry. 
Terminal piercing connection is also known as insulation replacement connection, in the connection process, the cable does not need to strip the insulation layer, the front end of the U-shaped contact reed of the connecting terminal is pierced into the insulation layer, so that the conductor of the cable slips into the groove of the contact reed, and is clamped, so as to form a tight electrical connection between the conductor of the cable and the reed of the connecting terminal. 
Terminal winding is to wrap the wire directly on the winding column of the angular contact. When winding, the wire is wound under controlled tension, pressed into and fixed at the corner of the contact winding column to form an air-tight contact. There are several requirements for winding wire: the nominal diameter of the wire should be in the range of 0.25 mm to 1.0 mm, the wire diameter is not greater than 0.5 mm, the elongation of the wire should not be less than 15%, when the diameter of the wire is greater than 0.5 mm, the elongation of the wire material should not be less than 20%. The winding tools include a winding gun and a fixed winding machine. 
Terminal crimping is a technique that compresses and moves metal within specified limits and connects wires to contact pairs. A good crimped connection produces a metal fusion flow that causes the wire and contacts to deform the material symmetrically. This connection is similar to the cold welding connection, which can obtain better mechanical strength and electrical continuity, and can withstand harsh environmental conditions. Right crimping is now considered by most to be superior to soldering, especially at high currents. 
Terminal welding usually refers to tin welding, and the formation of metallic continuity between the solder and the surface to be welded is important for the welding connection. Therefore, weldability is important for connection terminals. Tin alloy, silver and gold are common coatings for connection terminals. Common welding ends of reed contact pairs are welded plates, stamped welded plates, and notched welded plates. The common welding end of the pinhole contact pair has a circular arc notch. 
At present, in the terminal market of our country, the market of mobile communication and Internet continues to increase, and the terminal connected with it also shows a good trend of continuous rise. Today's electronic information development trend for the development of connector industry has created a broad space, with household appliances, electronic information products, automobiles, mobile phones and other manufacturing industries continue to shift to China, China has become the world's largest household appliances and information products manufacturing, consumer electronics, network design and communication terminal products output growth. As a result, the demand for intermediate products such as terminals is growing rapidly. At present, China has become the world's fastest growing terminal market. As the automation level of industry one is getting higher and higher, the industrial control requirements are becoming more and more strict and accurate, and the use of terminals is gradually increasing. 



Connector terminals should be surface treated, generally refers to plating. There are two main reasons for electroplating connector terminals: one is to protect the base material of the terminal reed from corrosion; The second is to optimize the performance of the terminal surface, establish and maintain the contact interface between the terminals, especially the film control. In other words, it makes metal to metal contact easier. 
There are three types of tin plating for connector terminals, which are pre-tin plating, pre-coating, and electroplating. Tin is relatively soft, relatively inexpensive, easy to solder, and has a coating thickness of 2-12μm. Brass or bronze can be tinned at 110 degrees, and steel can be tinned at 190 degrees. Electroplating gold on connector terminals is a better electroplating method for existing electrical contacts. It is soft, insoluble in acid and has good electrical conductivity. The gold plating thickness is usually 0.4-3.5μm.