Why Do Capacitors Go Bad? Here is Why

Why Do Capacitors Go Bad? | howtoimprovehome.com

Have you ever questioned why these little electronic components occasionally quit and often go bad?

They deteriorate due to leakage, deformation, aging, dielectric damage, and high temperatures. Leakage and deformation from dielectric damage in the material and physical stress reduce the capacitor’s efficiency. Unused capacitors also deteriorate. High temperatures can cause capacitor dielectric failure.

Leaking

One of the main causes of capacitor failure is leakage. When a small amount of electric current escapes from a capacitor even though it is meant to store it, it is called leakage in capacitors.

It often happens as a result of flaws in the dielectric. This material serves as insulation between the capacitor’s plates and is intended to prevent direct current flow across them. The capacitor’s efficiency can decrease as these flaws enlarge and more current leaks. 

In extreme circumstances, the capacitor may malfunction since it cannot store charge. Additionally, if the leaky current produces heat, it may harm the capacitor’s other parts or, in severe circumstances, result in an explosion.

Why Do Capacitors Go Bad? | howtoimprovehome.com

Deformation

A layered structure can be found in capacitors. An insulating dielectric separates the conductive plates that make them up. Failure of the capacitor may occur due to these components deforming. 

Physical stressors that can deform the plates or dielectric include a thermal expansion or contraction, mechanical shock, and vibration. The distance between the plates may change if the layers are distorted, which could modify the capacitance value and cause an issue. 

Additionally, deformation can bring the plates into contact, creating a direct path for current to travel across and resulting in a short circuit and capacitor failure.

Old Capacitor 

Capacitors deteriorate over time, just like many other electronic parts. A capacitor’s performance might decline with time, making it less effective than it previously was. The liquid electrolyte of electrolytic capacitors, which can dry out with time, is a good example.

Additionally, the dielectric material may deteriorate with time, increasing leakage current. Similarly, over time, the metallic components of the capacitor may also experience oxidation or other chemical changes that impact its performance. 

Because of this, a capacitor may not function according to its original specifications when it is ultimately used, even if it has been sitting idle on a shelf for many years.

Why Do Capacitors Go Bad? | howtoimprovehome.com

Dielectric Damage

The term “dielectric damage” describes the breakdown of the insulating material in the capacitor’s conducting plates. Numerous things, such as overheating, overvoltage, physical stress, and the capacitor’s age, might contribute to this. The failure of the dielectric to adequately insulate the plates causes excessive leakage current or possibly a short circuit when it occurs.

Dielectric damage is particularly frequent in capacitors exposed to voltages over their rated maximum or to extremely high or low temperatures, which can cause the dielectric’s physical structure or chemical stability to disintegrate.

High Temperature

Like most electrical components, capacitors are made to function in a specific range of temperatures. Capacitors can sustain damage from exposure to extreme temperatures, whether hot or cold, which can cause them to fail.

The dielectric breakdown due to high temperatures might result in a rise in leakage current and eventual failure. High temperatures may cause the electrolyte to dry out in electrolytic capacitors, lowering capacitance and increasing the risk of failure.

Extremely low temperatures, on the other hand, can also damage capacitors, especially electrolytic ones, by causing the electrolyte to freeze or become too viscous, which raises the capacitor’s equivalent series resistance (ESR) and lowers its capacity to conduct alternating current (AC).

It is also important to note that frequent, abrupt temperature changes can put the components of the capacitor under physical stress and deformation, eventually failing.

How Long Do Capacitors Last For?

If used properly and within the limits of their ratings in a stable working environment, they can last up to 30 to 40 years. Polyester, polypropylene, and metalized film capacitors have a long lifespan. But the manufacturing quality of a capacitor also impacts its lifespan.

The type of capacitor, its quality, how it is used, and the environment in which it is operated are only a few of the variables that affect a capacitor’s lifespan. The operating hours of capacitors are typically used to gauge their lifetime.

Under typical circumstances, the lifespan of an electrolytic capacitor, specifically an aluminum or tantalum kind, ranges from 2,000 to 15,000 hours. Their rated voltage may have an impact on how long they last; when used close to their rated voltage, these capacitors may break more quickly. 

To maximize its lifespan, selecting a capacitor with a voltage rating at least twice as high as its anticipated operating voltage is recommended. On the other hand, solid tantalum capacitors often have longer lifespans, with premium models providing up to 10,000–100,000 hours of service. Because of their dependability and resilience, they are preferred in many applications.

Due to their low price and small size, ceramic capacitors are often employed and can last for many years without seeing a substantial change in their electrical characteristics. They have an almost infinite lifespan under normal circumstances since they are resistant to voltage spikes and extreme temperatures.

Why Do Capacitors Go Bad? | howtoimprovehome.com

What Factors Affect Capacitor Lifespan?

Operating conditions, environmental factors, manufacturing quality, and the inherent properties of a capacitor all affect its lifespan. Consequently, choosing the appropriate capacitor for each application is essential to ensure reliable and long-lasting performance.

Operating Temperature

The operating temperature of a capacitor has a big impact on how long it lasts. A rated temperature exists for each type of capacitor. Operating a capacitor above this temperature might cause the dielectric material or electrolytes in other capacitors to deteriorate, shortening their lifespan. Typically, a capacitor’s lifespan doubles for every 10 degrees Celsius drop in operating temperature.

Voltage Stress

The applied voltage shouldn’t be higher than the capacitor’s rated voltage. A dielectric breakdown in the capacitor due to overvoltage can result in long-term damage. Long-term exposure to voltages near the rated voltage may also shorten the capacitor’s life.

Voltage stress is particularly important for electrolytic capacitors since it can speed up electrolyte evaporation and reduce capacitance and life expectancy.

Why Do Capacitors Go Bad? | howtoimprovehome.com

Mechanical Stress

Capacitors are susceptible to physical damage from mechanical stress, particularly those containing ceramic or solid electrolytes. This damage might impact the performance and lifespan of these capacitors. Machinal stress often occurs due to the wrong placement of PCB or components.

Environmental Aspects

Environmental factors like humidity, air pressure, and corrosive gases can impact a capacitor’s longevity. Excessive air pressure can cause mechanical stress, while excessive humidity can cause corrosion of the capacitor terminals. Degradation of the capacitor material might also result from exposure to corrosive gases.

Manufacture Quality

Another important consideration is the production process’s dependability and quality. Manufacturing flaws, such as subpar electrolytic capacitor seals or voids in the dielectric material, can result in early failure. These flaws can be reduced, and the lifespan of the capacitors can be increased with the aid of excellent production practices and strict quality control.

Can You Tell If A Capacitor Is About To Fail?

There are signs like physical deformation and damage, constant temperature fluctuations in the capacitor, and the electrical performance of the capacitor. If there is any indication, you need to replace the capacitor immediately to prevent further damage to your circuit.  

Physical Deformation

Visible physical damage or distortion is the most noticeable indicator that a capacitor is likely to fail. It is obvious that a capacitor is likely to fail or has already failed if it is bulging, dripping fluid, or exhibits burn marks. 

The top of the capacitor should be flat, especially for electrolytic capacitors. It is obvious that the capacitor has failed or is soon to fail if the top protrudes outward or bursts open.

Why Do Capacitors Go Bad? | howtoimprovehome.com

Temperature fluctuations

Depending on their particular purpose, capacitors typically work at a range of temperatures. A capacitor may begin functioning at temperatures outside this range just before it fails. Overheating is a common sign of an impending capacitor breakdown.

Electrical Performance Changes 

Electrical energy can be stored in and released from capacitors. If it fails, the capacitor’s capacity to carry out this task effectively may deteriorate. You might notice electrical noise, erratic behavior in the electrical circuit, or power supply variations. 

A multimeter can be used to test this by measuring the capacitance. If it isn’t within specs, the capacitor is probably failing.

Conclusion

Several factors, such as leakage, deformation, aging, dielectric degradation, and extreme temperatures, can cause capacitors to fail. Electric current leaking from the capacitor causes leakage, which lowers the capacitor’s efficiency over time. 

Changes in capacitance and even short circuits can result from component deformation in capacitors. As the dielectric material and electrolyte age, capacitors lose their effectiveness. Dielectric damage can develop in high leakage currents or short circuits due to overheating, overvoltage, and physical stress. 

Capacitor failure can result from dielectric breakdown and the electrolyte drying up at high temperatures. The lifespan of a capacitor might vary from 2,000 to 100,000 hours, depending on the capacitor’s kind and quality. 

The longevity of a capacitor can be impacted by elements such as operational temperature, voltage stress, mechanical stress, climatic conditions, and manufacturing quality. 

Physical deformation, temperature changes, and electrical function modifications are all indications that a capacitor is failing. Circuit damage can be avoided by examining these symptoms and replacing damaged capacitors as soon as possible.

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