Physical Damage: Mechanical stress, vibration, or impact can physically damage capacitors, leading to internal short circuits or breakage of the connections. Aging and Wear: Over time, capacitors naturally degrade. Electrolytic capacitors, in particular, can dry out, losing their ability to store charge effectively.
Mica and tantalum capacitors are more likely to fail in the early period of use (early failure), while aluminum electrolytic capacitors are more likely to experience wear-out failure due to aging use. In the case of film capacitors, when a local short circuit failure occurs, the shorted area may temporarily self-heal.
When a capacitor fails a short circuit (Figure 3), DC current flows through the capacitor and the shorted capacitor behaves like a resistor. For example, if a capacitor, placed between the input line and ground to remove AC current such as ripple current or noise, is shorted, DC current directly flows from the input to ground.
Paper and plastic film capacitors are subject to two classic failure modes: opens or shorts. Included in these categories are intermittent opens, shorts or high resistance shorts. In addition to these failures, capacitors may fail due to capacitance drift, instability with temperature, high dissipation factor or low insulation resistance.
Continued operation of the capacitor can result in increased end termination resistance, additional heating, and eventual failure. The "open" condition is caused by a separation of the end-connection of the capacitor. This condition occurs more often with capacitors of low capacitance and a diameter of less than .25 inch.
Capacitor failure is a significant concern in electronics, as these components play a critical role in the functionality and longevity of electronic circuits. Understanding the nuances of capacitor failure is essential for diagnosing issues in electronic devices and implementing effective solutions.