There is no air gap in the column of the magnetic system of the power terminal board, and the remanence is too large. File a part of the polar surface at the remanence gap, so that the gap is 0.1 ~ 0.3mm, or parallel two ends of the coil with a 0.1uF capacitor. There is oil on the iron core surface of the activated contactor or greasy after a period of use. Clean the antirust grease on the surface of iron core. The surface of iron core shall be flat, but it shall not be over polished, otherwise it is easy to cause delayed release. In the whole assembly process, it needs to withstand the high temperature of preheating area and the temperature transmitted to the terminal body through wave soldering. The flux shall not affect the terminals, be easy to remove, and be free of any residue. The whole assembly process can be cleaned with water. Preheat temperature is usually 100 ℃ or higher, and peak temperature is 280 ℃. The pierced welding pins need to be accurately positioned, appropriately sized, evenly placed, and have good weldability, which is conducive to insertion and welding. In the whole assembly process, it needs to withstand the high-temperature impact caused by heat treatment. In the welding process, infrared preheating and convection preheating are mainly used to make the heat transfer to the interface between the welding needle and the tin plate to melt the solder paste. The contact has poor resistance to fusion welding. When the motor is started or the circuit is short circuited, high current causes contact. The head is firmly welded and cannot be released, and the pure silver contact is easy to be welded. The main contact of AC contactor shall be silver base alloy with strong resistance to fusion welding, such as silver iron, silver nickel, etc. In the optical fiber communication (transmission) link, in order to realize different modules. For the need of flexible connection between equipment and system, there is a device that can be detachable (movable) connection between optical fiber and optical fiber, so that the optical path can be transmitted according to the required channel, so as to achieve and complete the predetermined or expected purposes and requirements. The device that can achieve this function is called connector. The power terminal board is to precisely connect the two ends of the optical fiber, so that the optical energy output by the transmitting optical fiber can be coupled to the receiving optical fiber to a large extent, and the influence on the system caused by its intervention in the optical link is reduced to a very small extent, which is the basic requirement of the optical fiber connector.