I. working principle of polymer PPTC self-recovery fuse
Polymer self-healing fuse is a mixture of polymer and conductive material, so it is also called polymeric switch. In the normal state, the polymer forms a crystalline structure, and conduction passes through the polymer to form a three-dimensional conductive material, which is in a low-resistance conductive state. Due to the low impedance, the heat generated by the normal current flowing through the element is small, and the crystal structure will not change. When the current passes or overcurrent occurs, the temperature of the polymer recovery fuse rises rapidly, and the heat generated by the parts immediately expands the polymer, resulting in the break of the electrical material chain, and the resistance value of the parts rises to more than 1 * 10 6 times of the original resistance value in a very short time. Restrict the passage of large current through components, and only small current will pass through. Just like cutting off the circuit, it achieves the purpose of protection. After the abnormal high current is eliminated or overheating is eliminated, the conductive chain in the component is re-established, and the component returns to the normal low resistance state.
Second, the application field of polymer PPTC self-recovery fuse
Polymer PPTC self-recovery fuse can be used in computers and their external equipment, mobile phones, battery packs, telecommunication and network equipment, transformers, industrial control equipment, automobiles and other electronic products, and can play an overcurrent or overtemperature protection role. We often use digital products, cameras, mobile phones, electronic photo frames, control boards, toys, audio and other consumer electronic products, liquid crystal displays, power supply, communication equipment, safety products, converters and other low-voltage power products and lightning protection combinations in the market, which can find the existence of polymer PPTC self-recovery fuses.
