What are solid capacitors? Marking and classification

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Speaking of solid capacitors, this is the same electrolytic capacitor, but it uses a special conductive polymer or a polymerized organic semiconductor. While other capacitors use a conventional liquid electrolyte.

General characteristics

As already mentioned, the difference between solid and conventional capacitors is the internal "stuffing" of the device. So why are they better?

The first and most significant difference lies precisely in the fact that solid-state capacitors use a solid polymer electrolyte, rather than a liquid one. This eliminates the possibility of leakage or evaporation of the electrolyte. The second significant advantage of solid state devices was their series equivalent resistance, which is called ESR. The decrease in this indicator has led to the fact that it has become possible to use less capacitive capacitors, as well as smaller sizes in the same conditions. Another significant advantage of solid capacitors is that they are less sensitive to temperature changes. This advantage is alsoindicates that the lifespan of such an object will be about six times longer, which means that the object in which it is installed will last much longer.

Electrolytic

The solid state electrolytic capacitor uses a thin layer of metal oxide as the dielectric. The formation of this layer is carried out by means of an electrochemical method. The flow of this process is carried out on the cover of the same metal.

The second cover of this capacitor can be presented in the form of a liquid or dry electrolyte. Conventional electrolytics use liquid, while solid state uses dry. This type of solid capacitor uses a material such as tantalum or aluminum to create the metal electrode.

It is worth noting that tantalum capacitors also belong to the electrolytic group.

Asymmetrical

The asymmetric solid state capacitor is a relatively recent invention, as other devices have been used before. The first and simplest capacitor from this group was the T-shaped. In this object, the plates were located in the same plane. The subsequent development of asymmetrical capacitors led to the disc type. It consisted of a flat ring, as well as a disc located inside it. The subsequent improvement of asymmetric capacitors led to an even greater simplification of the design, and devices with two electrodes were obtained. One of them waspresented in the form of a thin wire, and the second - a thin plate or a thin strip of metal. But it is worth noting that the use of this particular type of capacitor is difficult due to the use of high-voltage equipment.

Marking

There is a label for solid capacitors that describes their characteristics. The presence of this marking will help to understand certain properties of the capacitor:

• Based on the marking of the device, you can accurately determine the operating voltage for each capacitor. It is also worth noting that this value must exceed the voltage that is present in the circuit using this object. If this condition is not met, then there will either be failures in the operation of the entire circuit, or the capacitor will simply explode.
• 1,000,000 pF (picofarad)=1 uF. This marking is the same for many capacitors. This is due to the fact that almost all devices have a capacitance equal to or close to this value, and therefore can be indicated both in picofarads and in microfarads.

Swelling capacitor

Despite the fact that capacitors of this type are quite resistant to breakage, they still do not last forever, and they also have to be changed. The replacement of a solid capacitor may be necessary in several cases:

• There can be quite a few reasons for the breakdown, that is, swelling of this device, but the main one is called the poor quality of the part itself.
• To the causes of bloating, you canalso refer to the boiling off or evaporation of the electrolyte. Even though a solid electrolyte is used, such problems are still not completely ruled out, and at very high temperatures it does happen.

It is important to note that overheating of this device can occur both due to the influence of the external environment, and due to the internal one. Incorrect installation can be attributed to internal influence. In other words, if the polarity is reversed when mounting this part, then when it is started, it will heat up almost instantly and, most likely, will explode. In addition to these reasons, severe overheating is also possible due to non-compliance with the operating rules. It could be the wrong voltage, capacitance, or operating in too high a temperature environment.

How to avoid bloating and frequent replacement

Start with how to avoid bloating a solid capacitor.

• The first thing advised is to use only quality parts.
• The second piece of advice that can help avoid such problems is to keep the capacitor from overheating. If the temperature reaches 45 degrees or more, then urgent cooling is needed, and it is even better to place these devices as far as possible from heat sources.
• Since most capacitors swell in computer power supplies, it is recommended to use voltage stabilizers that protect the network from sudden power surges.

If swelling did occur, thendevice needs to be replaced. The main rule of repair is to choose a capacitor with the same capacity. It is allowed to deviate this parameter upwards, but only slightly. Downward deviations are not allowed. The same rules apply to the voltage of the object. It is also worth adding that when replacing electrolytic capacitors with solid-state ones, devices with a lower capacity can also be used. This is possible due to the lower ESR discussed earlier. But before that, it is still worth consulting with a specialist. The replacement process itself consists in removing the burnt part by soldering and soldering a new one.

Repair

Quite often, it is necessary to carry out preventive maintenance of capacitors. Suppose a suspicious capacitor was found during disassembly of a computer. It must be checked and replaced if necessary. To replace, you will need a soldering iron with a power of 25 to 40 watts. These are medium power devices. Their use is justified by the fact that less powerful soldering irons will not be able to solder the capacitor, and more powerful ones are too large, and it is inconvenient to work with them.

It is best to have a soldering iron with a conical tip on hand. To carry out repairs, the old capacitor is soldered, but this must be done very carefully, since the boards in which they are installed are most often multilayer - up to 5 layers. Damage to at least one of them will disable the entire board, and it can no longer be repaired. After soldering the old device, the installation holes are punchedneedle, best medical, it is thinner. Soldering a new object is best done using rosin.

Solid Polymer Capacitors

It can be said that all devices of this type are polymer, since inside this device a solid polymer is used instead of a liquid electrolyte. The use of solid material in standard solid capacitors has resulted in the following benefits:

• at high frequencies - low equivalent resistance;
• high ripple current value;
• capacitor life is much longer;
• more stable operation at high temperatures.

In more detail, for example, reduced ESR means less energy consumption, and hence less heating of the capacitor at the same loads. A higher degree of current ripple ensures stable operation of the entire board as a whole. Naturally, it was the replacement of a liquid electrolyte with a solid one that led to the fact that the service life increased significantly.