Electronic components include components and devices. Electronic components are finished products whose molecular composition is not changed during the whole manufacturing process.
Such as capacitors, resistors and inductors. Electronic devices are finished products whose molecular structure changes in the whole process of manufacturing, such as electronic tubes and integrated circuits. Resistance components.
The faults of resistance components account for a large proportion in electronic equipment. Resistors can be divided into shunt, step-down, load, impedance matching and other functions. Resistance elements can be divided into wire wound resistance and non - wire wound resistance according to the different structure. Contact damage, open circuit and lead mechanical damage are the main methods of resistance component failure. The main influence of temperature change on resistance is that the thermal noise of resistance increases, the resistance deviates from the nominal value, and the allowable consumption probability decreases when the temperature increases. However, we can also use this resistance property.
The main reasons for capacitor breakdown are as follows:
1. Dielectric defects, impurities and conductive ions; 2. Medium aging; 3. Dielectric material has electrical air gap breakdown; 4. Mechanical damage to the medium in the manufacturing process; 5. The molecular structure of the medium changes; 6. Metal ions migrate to form conductive channels or edge arc discharge.
Capacitor failures can also be caused by open circuit. Oxidation of the contact point between wire and capacitor leads to open low level, poor contact between wire and electrode, and electrolytic capacitor anode leads to open circuit failure of metal foil due to mechanical fracture. This means that capacitors can also fail due to degradation of electrical parameters, such as migration of metal ions from electrode materials. Self-healing effect of metallized electrode. Electrolytic and chemical corrosion of electrodes. Humidity. Surface contamination may cause electrical degradation of the capacitor. Inductor. Inductance components include transformers, inductors, filter coils, vibration coils and so on. Most of the faults of inductance components are caused by external factors, such as transformer temperature rise, load short circuit, excessive coil current, etc., will lead to coil short circuit, short circuit, breakdown and other faults.
In the integrated circuit, no matter which part of the problem, the whole can not run normally, such as: electrode short circuit, open circuit, mechanical wear, poor welding and so on. Faults are mainly divided into complete damage and poor thermal stability. Thermal stability faults mainly occur at high or low temperature, beyond the operating temperature range of the equipment and faults. So how do you effectively find failing electronic components and replace or repair the problem? During debugging, problems occur when circuits do not work or work abnormally. First of all, through dynamic observation method, namely when the line equipment is energized, through listening, seeing, touch, smell and other methods to judge the fault of electronic components. For example, listen to whether the device has abnormal sound. Carefully observe whether there is smoke and sparks in the circuit; Touch elements, whether the circuit is hot; Smell the burning. By measuring various values in normal and abnormal circuits, you can also use a multimeter to measure the on-off status of the circuit.