What Role Do Capacitors Play in Obsolescence?

Capacitors are well-known components in the world of repair. They have been present for a long time in almost 100% of electrical and electronic products, sometimes in large quantities, interacting with multiple functions and parts.

Over time, capacitors have often been pointed out as playing a role in planned obsolescence. So, is this a myth or truth? We’re trying to decipher it, and it might not be what you expect!

What is a Capacitor?

Capacitors are passive electronic components that play an essential role in many electronic and electrical applications due to their ability to store, release, filter, and transmit electrical energy.

Their size varies depending on their characteristics, particularly their electrical capacity, which is expressed in Farads (Thanks to Michael Faraday) for charge and in Volts for service voltage. This capacity represents the amount of electrical energy a capacitor can accumulate per unit of voltage. Visually, the larger the capacitor, the more powerful it is, and the more energy it can store.

More specifically, a capacitor with a capacity of 1 farad (1F) can store 1 coulomb (1C) of charge when the voltage between its plates is 1 volt (1V). In other words, a capacitor’s capacity is defined by the formula:
C = Q/V

• C is the capacity in farads (F).
• Q is the electrical charge in coulombs (C) stored by the capacitor.
• V is the voltage in volts (V) between the capacitor’s plates.

In practice, capacitors generally have much smaller capacities than 1 farad. The common sub-units used for capacitor capacities are:

• Microfarad (μF, 1 μF = 10^-6 F)
• Nanofarad (nF, 1 nF = 10^-9 F)
• Picofarad (pF, 1 pF = 10^-12 F)

Thus, on consumer electronics circuit boards, you’ll often find capacitors with values such as 1 μF, 100 nF, or 10 pF. Each capacitor, from the smallest to the largest, has an inscription that identifies its main characteristics.

What is a Capacitor Made of?

A capacitor is mainly composed of two conductive metal plates separated by an insulating material called a dielectric.

Depending on the capacitors and their applications, the conductive plates may be made from various conductive materials (aluminum, tantalum, or stainless steel), while the dielectric can be made of polymers, ceramics, or paper.

What Do Capacitors Do?

The primary feature of a capacitor is its ability to store electrical energy in the form of electrical charge. When a voltage is applied across the capacitor’s terminals, electrical charges accumulate on the conductive plates, creating an electric field between them. The higher the capacitor’s capacity, the more charge it can store—essentially making it an “electricity reservoir” (be cautious of electric shocks!)

• Energy Storage:

Capacitors can temporarily store electrical energy and release it when needed. They are used in camera flash circuits, vehicle ignition circuits, and other applications that require a quick discharge of energy.

• Voltage Stabilization, Filtering, and Coupling/Decoupling:

Capacitors are often used to smooth voltage fluctuations in power supplies, ensuring a more stable supply to electronic components. This is particularly helpful in avoiding malfunctions and interference in sensitive electronic circuits.

Capacitors can also filter electrical signals by removing DC components, low frequencies, and high frequencies. This is commonly used in audio circuits to eliminate unwanted noise. In integrated circuits and microprocessors, decoupling capacitors are used to eliminate disturbances and electromagnetic noise, ensuring a clean and stable power supply.

They are also used to transmit alternating signals from one part of a circuit to another while blocking direct current. This function is crucial in many amplifiers and data transmission circuits.

• Motor Starting:

In single-phase electric motors, start-up capacitors are used to provide the extra energy needed to get the motor rotating. The capacitor discharges rapidly and massively to assist the motor’s start-up.

• Timing Adjustment:

In timer and regulation circuits, capacitors are used to determine the circuit’s response time. The response time of an electrical circuit depends on several factors, including the nature of the circuit, the components used, and operating conditions. In general, the response time refers to how long it takes for the circuit to reach a new stable state in response to a change in conditions.

For example, in an RC (resistor-capacitor) circuit, the response time is often related to the time constant of the circuit, which is the product of resistance (R) and capacitance (C). The formula to calculate the time constant (τ) is:
τ = RC
The approximate response time is generally considered to be 5 times the time constant (5τ), which corresponds to the time it takes for the circuit to reach about 99.3% of its new stable state in response to a change.

There are many other applications of capacitors, including power factor compensation and resonance in conjunction with coils.

What Are the Different Types of Capacitors?

There are many types of capacitors. They can be grouped by technology, as they differ in their structures, materials, sizes, and capacities.

Here is a non-exhaustive list from most common to least common:

• Electrolytic Capacitors
• Ceramic Capacitors
• Film Capacitors
• Glass Dielectric Capacitors
• Mica Capacitors
• Supercapacitors
• Variable Capacitors
• Air Capacitors
• Paper Capacitors

What is a Self-Healing Capacitor?

A self-healing capacitor is a type of capacitor that can automatically recover its nominal capacity after a short circuit or brief overvoltage. Its technology differs from that of traditional capacitors.

When a short circuit or overvoltage occurs, one of the following two situations typically arises with a non-self-healing capacitor:

• Short Circuit: A short circuit creates a very low-resistance electrical path, allowing an excessively high current to flow through the capacitor. Since capacitors have very low impedance at high frequencies, they allow this current to pass. The capacitor discharges rapidly, releasing all its stored energy almost instantly.

• Overvoltage: Overvoltage happens when the voltage across the capacitor exceeds its rated voltage or the breakdown voltage of the dielectric. In this case, the dielectric may fail, causing the capacitor to discharge. Again, this results in a rapid release of the stored energy.

Non-self-healing capacitors usually cannot recover their stored energy once it has been released. In contrast, self-healing capacitors use a specific dielectric material that isolates the damaged area and “repairs” it partially, allowing it to continue functioning under near-nominal conditions. They are used in applications where temporary overvoltages may occur, helping to extend the lifespan of circuits by minimizing damage from overvoltage events.

Les condensateurs cicatrisants utilisent quant à eux un matériau diélectrique spécifique capable d’isoler la zone endommagée et de la “réparer” partiellement pour continuer de fonctionner des conditions quasi-nominales.Ils sont utilisés dans des applications où des surtensions temporaires peuvent se produire, contribuant ainsi à prolonger la durée de vie des circuits en minimisant les dommages causés par les événements de surtension.

However, self-healing capacitors have their limits. Small breakdowns that occur repeatedly, excessive or prolonged overvoltages, will gradually diminish their self-healing capacity and eventually cause irreversible damage. Appropriate protections are thus necessary in circuits.

What is the Lifespan of a Capacitor?

The lifespan of a capacitor is highly variable and multifactorial, making it difficult to provide a definitive answer except in specialized aerospace and military applications where operational reliability is crucial.

Capacitors are typically reliable components when used according to best practices, but they tend to age faster than other passive or active components. Here are a few factors that can influence their lifespan.

• The Influence of Price on Capacitors:

The price of the capacitor directly impacts its quality. A highly reliable capacitor is rarely a very cheap one! The materials used can vary in quality, as can the manufacturing process. This is often where the problem lies. Manufacturers of low-quality products tend to cut costs on all components, including capacitors.

• The Influence of Capacitor Sizing on the Electronic Circuit:

The manufacturer must select the correct type of capacitor for the intended application and size it with a safety margin, especially for operating temperature and overvoltage.

• The Influence of Capacitor Placement on the Circuit Board:

It is not common for temperature to directly and significantly impact the aging of capacitors because they generally have specifications that allow them to withstand operating temperatures between 85°C and 105°C

If a capacitor is poorly placed, such as near a heat sink (aluminum radiator) or within a resistive system, it might be affected. However, this failure would occur quite quickly, most likely during the product’s warranty period. Electronic designers have long considered this factor, so unless there is an exception, placement and heat do not have a significant impact when the design is well executed.

• The Influence of Operating Time on the Capacitor:

Operating time leads to normal aging of capacitors. Their lifespan correlates with the compatibility between their specifications and the voltage/temperature applied during operation.

The lifespan can be estimated using a calculation formula. A commonly used model to estimate the lifespan of electrolytic capacitors is the Arrhenius activation-life model. This equation is based on the theory of life acceleration due to temperature. It predicts the expected lifespan of the capacitor based on its operating temperature in Kelvins.

What Causes Capacitor Failures?

All capacitors have a limited lifespan, even when unused. Over time, internal materials can degrade, resulting in a loss of capacity or leakage. However, certain operating conditions can increase the risk of failure.

• Excessive Current:

  If the operating voltage exceeds the nominal voltage, during a voltage spike or a product issue, the capacitor can be damaged and fail to perform its function. It may short-circuit if overvoltage causes degradation or fusion of internal dielectric materials.

• Excessive Reverse Voltages:

  When disassembling or replacing parts, incorrect wiring can cause failure. Some capacitors have polarity. Applying reverse voltage can cause leakage, swelling, and rarely, an explosion.

• Electrolytic Aging:

  Electrolytic capacitors, commonly used in electronics, have a limited lifespan due to the degradation of the electrolyte. This can increase the capacitor’s internal resistance and reduce its capacity.

• Temperature Variations:

  For capacitors exposed to harsh environmental conditions, significant temperature fluctuations can drastically reduce their performance.

What failures do capacitors cause?

The failures caused by capacitor malfunctions are numerous and depend on the capacitor’s function. In the case of a failure in a start capacitor, the electric motor will either fail to start or run at too low a speed. If the capacitor serves as a timing regulator, as in a toaster, your toast will either be undercooked or overcooked! For an LED display, it is possible that the power supply will be poorly managed, causing the display or character inscriptions to become partial.

In all these situations, it is possible that the products will display error messages or fault codes.

Electronics is a field that generally has a high level of reliability, but no system is infallible. Each of these components can fail for various reasons, but the capacitor is often singled out.

Capacitors and Planned Obsolescence

The capacitors have regularly been suspected of programmed obsolescence to the point that France 2 took up this topic in a Cash Investigation episode titled “The Planned Death of Our Devices.” According to some repair technicians, the episode only partially addressed this complex issue.

Here is the feedback from a repair technician:

“The demonstration made in the Cash Investigation program… was biased and partially false. Samsung was clearly suspected of accelerating the aging of capacitors by placing them near aluminum heat sinks responsible for dissipating the heat generated by the warming of electronic components.” In this case, the inaccurate statements of a ‘teacher-researcher’ about the intention of planned obsolescence had been illustrated by a computer-generated animation.

If a television technician had been questioned, he would have had no trouble proving that this had nothing to do with the proximity of a radiator. Indeed, of the 5 capacitors placed in parallel under identical electrical conditions, showing the same accelerated aging defect, 2 of them were far from any heat sink.

The cause of the defect had nothing to do with ambient heat (capacitors designed to operate at 105°C). It was simply due to the poor quality of the original Chinese capacitors, which were likely chosen by buyers more focused on price than on adhering to the specifications.

As proof, at that time, under identical operating conditions, only Japanese manufacturers were spared from this type of problem. This is actually mentioned in the report. It is a proven certainty today: this problem was solely due to the quality of the capacitors, because once replaced in after-sales service with high-quality (Japanese) components, the defect never occurred again. Manufacturers have since corrected the issue and upgraded the quality of this type of component.

This testimony confirms that capacitors are indeed a source of failure but disproves the idea that it was intentional and part of a plan to program the lifespan of the device. Indeed, when a manufacturer chooses poor-quality components by mistake or for cost reasons, it becomes very difficult for them to control the lifespan of their product, as failures will be random.

The capacitors in small household appliances

Kettles, toasters, vacuum cleaners, coffee machines… these small household appliances (SHA) often include a small auxiliary electronic board, which controls a display or a regulation function (temperature, speed). It is necessary to supply power to this board for it to function. To do this, a minimalist DC power supply, responsible for transforming 220 Volts into 5V, 12V, or 24V, is integrated into the product. This simple electronic board (the power supply) only requires a few basic components such as resistors, diodes, and capacitors. It’s a very common setup.

Testimony of an issue with capacitors

According to reported testimonies, this “capacitor-based DC power supply” seems to cause recurring failures, particularly problematic in small heating devices that do not have an on/off switch or an automatic shutdown system.

The capacitor is then continuously exposed to the 230V network voltage, which accelerates its aging. As explained earlier, the aging of capacitors is mainly impacted by the operating temperature, the voltage it is subjected to, and the duration of exposure to this voltage. This phenomenon will be further exacerbated if the capacitor is of poor quality, poorly sized, or placed in a very hot environment (which is rare).

Its performance, and more specifically its capacitance value in uF, will gradually decrease. As a result, the power supply board will no longer perform its role because gradually the voltage will degrade, providing, for example, 9 Volts instead of the required 12, causing the device to function erratically. Generally, when the capacitance drops by 30% (e.g., from 0.32uF to a nominal value of 0.47uF), the capacitor causes the device to malfunction.

This failure is characterized by intermittent or random operation of the affected product. The device may not start consistently, the LCD screen may flicker, the characters may be incomplete, or the device may stop working randomly.