Spot welding equipment : several welding methods of thermal fuse

　　Thermal fuse, also called temperature fuse, is a temperature sensing circuit cut-off device.

　　Thermal fuse can sense the overheating generated during abnormal operation of electrical and electronic products, thereby cutting off the circuit to avoid fire. Commonly used: electric hair dryer, electric iron, rice cooker, electric stove, transformer, electric motor, water dispenser, coffee maker, etc. The thermal fuse cannot be used again after it is operated, and it only works once at the melting temperature.

　　The thermal fuse can be connected by soldering, spot welding, or splicing.

　　When the spot welding method is selected for connection, the thermal fuse spot welding machine generally adopts the Shenzhen Site Technology intermediate frequency inverter DC spot welding machine. The equipment changes from single-phase or three-phase alternating current to pulsating direct current through a rectifier circuit, and then passes through power switching devices. The composed inverter circuit becomes an intermediate frequency square wave and is connected to the transformer. After the voltage is reduced, it is rectified into a small pulsating direct current supply electrode to weld the workpiece. The inverter usually uses current feedback pulse width modulation to obtain a stable constant current output. The intermediate frequency inverter spot welder has excellent performance and is suitable for welding thin metal parts with high thermal conductivity and fine workpieces.

　　When using solder that can be spot welded, care must be taken to avoid damage to the thermal fuse due to overheating of the welding. The following table is a guide for the longest soldering time (single leg, leg length 10mm, under the condition of 300 degrees Celsius)

　　Rated operating temperature TF Welding time (seconds)

　　102—115℃ 1

　　125—139℃ 2

　　150°C 3

　　Because the internal temperature sensing element of the thermal fuse is a low-melting-point alloy wire, which is connected to the two pins, improper welding operation (welding temperature is too high, the welding time is too long, the lead is too short, etc.) will cause heat to pass through the pins. Into the thermal fuse, the temperature sensing element will be overheated and damaged (fuse, or the end will be thinned by thermal shock, which will become fragile, and the reliability of the connection with the pin will be reduced. When the current passes through or other reasons, the damaged part may produce early Phenomenon.

　　Ways to avoid welding overheating and damaging the thermal fuse:

　　Use longer pins as much as possible. Longer pins allow longer soldering time and reduce the possibility of overheating. In the case of short pins, use needle-nose pliers or other tools to clamp the position between the solder joints on the pins and the fuse body to dissipate heat, and avoid the amount of soldering being transferred into the thermal fuse. At the same time, the welding temperature should be controlled not to be too high, and the welding time should be as short as possible.

　　Shenzhen Site Technology Co., Ltd. is a high-tech production enterprise integrating R&D, production and sales of automated welding equipment and power battery PACK line equipment. The professional technical engineering team provides customers with timely and perfect pre-sales and after-sales services.