Failure Mechanism and Failure Analysis of Common Electronic ComponentsCurrent location ：Home > Failure Mechanism and Failure Analysis of Common Electronic Components
- Most of the faults in electronic equipment are ultimately caused by electronic components failure. If you are familiar with the type of faults of components, sometimes you can quickly find faulty components through intuition, and sometimes you can find the fault by simple resistance and voltage measurement.
Resistor class
Resistor-like components include resistive components and variable resistive components. Fixed resistors are commonly referred to as resistors, and variable resistors are commonly referred to as potentiometers. Resistor-like components are used in electronic devices in a large number and are power-consuming components. The failure rate of electronic devices caused by resistor failure is relatively high, accounting for about 15%. The failure mode and cause of the resistor are closely related to the structure, process characteristics and use conditions of the product. The failure mechanism of the resistor potentiometer varies depending on the type. The main failure modes of non-linear resistors and potentiometers are open circuit, resistance drift, lead mechanical damage and contact damage; the main failure modes of wirewound resistors and potentiometers are open circuit, lead mechanical damage and contact damage. There are four main categories:
(1) Carbon film resistors. Lead breakage, matrix defects, poor uniformity of the film layer, groove defects in the film layer, poor contact between the film material and the lead end, film and substrate contamination, etc.
(2) Metal film resistors. The resistive film is uneven, the resistive film is broken, the lead is not strong, the resistive film is decomposed, the silver migration, the resistive film oxide reduction, the electrostatic charge action, the lead breakage, the corona discharge, and the like.
(3) Wirewound resistors. Poor contact, current corrosion, poor lead wires, poor wire insulation, solder joint melting, etc.
(4) Variable resistors. Poor contact, poor soldering, contact reed rupture or lead drop, impurity contamination, poor epoxy adhesive, shaft tilt, etc. The resistor is prone to deterioration and open circuit failure. After the resistance is deteriorated, the resistance is often a large drift. The resistor is generally not repaired and the new resistor is replaced directly. Wirewound Resistors When the wire is blown, in some cases the blown process can be re-welded and used. Resistance deterioration is mostly caused by poor heat dissipation, excessive moisture or defects during manufacturing, and burnout is caused by abnormal circuits such as short circuit and overload. There are two common phenomena of resistor burnout. One is that the current is too large, causing the resistor to burn out due to resistance heating. At this time, the surface of the resistor is visible in the form of a burnt paste, which is easy to find. In another case, since the instantaneous high voltage is applied to the resistor to cause the open circuit or the resistance to become large, in this case, the surface of the resistor generally does not change significantly, and the resistance of the fault phenomenon can often be found in the high voltage circuit.
2. Capacitor class
Common fault phenomena of capacitors mainly include breakdown, open circuit, degradation of electrical parameters, electrolyte leakage and mechanical damage. The main reasons for these failures are as follows:
(1) Breakdown. Defects, defects, impurities or conductive ions in the medium; aging of the dielectric material; electrochemical breakdown of the dielectric; arcing of the inter-electrode edge in high humidity or low pressure environments; transient short circuit of the dielectric under mechanical stress; migration of metal ions Forming a conductive channel or edge arcing discharge; dielectric air gap breakdown inside the dielectric material causes electrical breakdown of the medium; mechanical damage of the medium during the manufacturing process; change of the molecular structure of the dielectric material and the applied voltage is higher than the rated value.
(2) Open the road. Breakdown causes electrode and lead insulation; electrolytic capacitor anode lead foil is corroded or mechanically broken; lead wire and electrode contact point oxide layer to cause low level open circuit; lead wire and electrode contact poor or insulated; electrolytic capacitor anode lead metal foil Open circuit due to corrosion; dry or frozen working electrolyte; instantaneous open circuit between electrolyte and dielectric under mechanical stress.
(3) Degradation of electrical parameters. Moisture and dielectric aging and thermal decomposition; metal ion migration of electrode materials; existence and variation of residual stress; surface contamination; self-healing effect of metallized electrode of material; volatilization and thickening of working electrolyte; electrolytic corrosion or chemical corrosion of electrode; Lead and electrode contact resistance increases; impurities and harmful ions. Since the actual capacitor works under the combined action of working stress and environmental stress, one or several failure modes and failure mechanisms are generated, and there is also a failure mode that causes another failure mode or failure mechanism to occur. For example, temperature stress can promote surface oxidation, accelerate the influence of aging, accelerate the degradation of electrical parameters, and promote the decline of electric field strength, accelerate the early arrival of dielectric breakdown, and the degree of influence of these stresses is a function of time. Therefore, the failure mechanism of the capacitor is closely related to the type of product, the type of material, the difference in structure, the manufacturing process and environmental conditions, and the working stress.
QR Code