Everything You Need To Know About Polymer Capacitor

Polymer capacitor brings many benefits to electronic devices. It is mainly used for low-frequency content and has been used in high-end audio equipment for a long time. Today, polymer capacitor is becoming increasingly popular in various applications.

Polymer capacitor comes with an array of advantages over traditional electrolytic capacitors. The article explains everything you need to know about polymer capacitors so that you can decide if it’s right for your next project. Keep reading to discover the ins and outs of this special type of capacitor.

What is a polymer capacitor?

Polymer capacitor is a capacitor that uses a polymer film as its dielectric. The main function of the capacitor is to store an electric charge. The polymer film is made of two or more layers of plastic and it acts as the dielectric between these layers.

Polymer capacitors are smaller than electrolytic capacitors. They are often used for low-frequency content because they have better tolerance to heat and operate in high temperatures. This makes them suitable for many applications like video games, computers, and much more.

Polymer capacitors have a larger tolerance to humidity than electrolytic capacitors making them ideal for outdoor use too. They can easily withstand the effects of moisture, temperature changes, and mechanical shock.

The properties of polymer capacitors make them suitable for use in circuits that require high current or voltage capabilities such as power supplies and power management circuits in computers and televisions, motor control circuits, and electrical tools like drills, and mixers among many others.

Polymer Capacitor Construction

What do polymer capacitors look like and how are they made? Well, they look like a standard capacitor with two metal plates. The dielectric is made of a transparent plastic film that is sandwiched between the two metal plates, the anode and cathodes.

After the assembly, the capacitor is rolled into a defined cylindrical shape. The electrodes are cased in an aluminum casing. Given their features and application areas, polymer capacitors are usually made using the Surface-Mount Technology (SMT). This manufacturing method allows them to be compact and fit into the PCB.

The transparent plastic film is made of polymers that are flexible and will not deteriorate in high temperatures.

Polymer capacitors are available in different shapes, sizes, and ratings depending on their intended use.

They come in cylindrical or rectangular shapes with either axial or radial leads. Their size ranges from very small to very large depending on the rating and application requirements.

How does a polymer capacitor work?

The polymer capacitor working principle is due to the presence of the conductive polymer. The polymer acts like a dielectric that is sandwiched between the two metal plates. The dielectric is made of a transparent plastic film that is sandwiched between the two metal plates, the anode and cathode.

The capacitor works when an electrical current passes through it. The current flow causes the positive and negative charges to attract each other in order to balance out the charge difference between them. This creates a potential difference across the capacitor.

When a voltage is applied across a capacitor, there will be two results: First, the charges on the capacitor will spread out evenly, so that there are no differences in charges. Second, a potential difference is created between the two plates of the capacitor.

The potential difference is directly proportional to the applied voltage, and inversely proportional to the capacitance of the capacitor. Capacitance is a measure of how much charge can be stored in a capacitor for a given voltage. The more charge stored in the capacitor for a given voltage, the smaller its capacitance.

Components of a polymer capacitor

The main components in polymer capacitors are:

– Electrolyte: It is the conductive liquid (solid or liquid) that will be the medium for charge movement. The electrolyte can be a solid or a liquid.

– Dielectric: It is the material between the plates of a capacitor that will store and release charge. The dielectric may be an oxide, air, vacuum, paper, plastic film, ceramic, mica and other materials.

– Conductor/Electrode: A material with good electrical conductivity to carry current between two electrodes. The electrode can be made from various materials such as aluminum, silver or gold-plated brass.

– Electrode: A conducting path in a circuit where there is a voltage difference or potential difference across it.

– Separator: A thin layer of nonconducting material (polymer) is used to keep the electrodes apart from each other so that no direct contact occurs between them and keeps them insulated from each other.

Types of polymer capacitors

Film capacitors vs rolled capacitors

Polymer capacitors are divided into two types based on their structures: film capacitors and rolled capacitors. Film capacitors have electrolytes deposited on one side of a thin dielectric layer deposited on an aluminum foil substrate. On the other hand, rolled capacitors have electrolytes deposited on both sides of an aluminum foil substrate which is rolled up into cylindrical shapes during the manufacturing process.

The main advantage of a rolled polymer capacitor is that it has higher reliability compared to film polymer capacitors while the main advantage of a film polymer capacitor is that it has lower equivalent series resistance (ESR) and equivalent series inductance (ESL) compared to rolled polymer capacitors.

Single layer vs multi-layer capacitors

The topology of polymer capacitors is divided into two categories based on how many layers are used in their construction: single-layer polymer capacitors and multilayer polymer capacitors.

Single-layer polymer capacitors are constructed using only one electrolyte layer and two electrodes (separators) while multilayer polymer capacitors are constructed using two or more electrolyte layers and two or more electrodes (separators). The main advantage of a single layer polymer capacitor is that it has higher capacitance-voltage characteristics compared to multilayer polymer capacitors.

Organic vs inorganic polymer capacitors

Polymer electrolyte used in polymer capacitors are divided into two categories based on their chemical compositions: organic electrolyte and inorganic electrolyte. Organic electrolytes are more widely used than inorganic electrolytes since they have lower equivalent series resistance (ESR) and equivalent series inductance (ESL). However, organic electrolytes are more flammable than inorganic electrolytes.

Polymer capacitors with organic electrolytes are divided into two categories based on their chemical composition: conductive polymer capacitors and supercapacitors.

In conductive polymer capacitors, an ionic liquid or a salt acts as an ionic conductor while in supercapacitors, a solid state ionic conductor acts as an ionic conductor between the electrodes.

Polymer hybrid capacitors

These capacitors are a combination of polymer and solid electrolytes. This combination of polymer and solid electrolytes provides the benefits of both polymer capacitors and supercapacitors. These capacitors have high energy density and high power density.

Solid state polymer capacitors

These are solid-state polymers with ionic conductors in their structure. They have high energy density and high power density compared to conventional polymer capacitors.

Polymer tantalum capacitor

A polymer tantalum capacitor is a type of polymer electrolyte capacitor that consists of polymer tantalum as the dielectric and solid electrolytes as the conductive polymer.

These capacitors are made of slid metals and use manganese dioxide as their main electrolyte. However, they tend to be easily affected by temperature changes. For instance, a slight increase in temperature will reduce the voltage rating of the capacitor.

What is the difference between polymer capacitors and ceramic capacitors?

Polymer capacitors and ceramic capacitors differ in many different ways. First polymer capacitors are more stable than ceramic capacitors. Stability in this context refers to the ability to withstand changes in temperature and voltage. In addition, polymer capacitors are more durable than ceramic capacitors. Also, polymer capacitors are able to withstand higher temperatures than ceramic capacitors.

Another difference is durability. Polymer capacitors are more durable than ceramic capacitors. This is due to the fact that polymer capacitors are able to withstand higher temperatures.

Polymer capacitors and ceramic capacitors also differ in their electrical characteristics. Polymer capacitors have a higher voltage rating than ceramic capacitors.

Also, they have a lower ripple current rating than ceramic capacitors do. In addition, polymer tantalum capacitors and ceramic tantalum capacitors have different dielectric constants. The dielectric constant of the polymer tantalum capacitor is 0.048 while the dielectric constant of the ceramic tantalum capacitor is 0.051

Advantages of polymer capacitors

Should I buy a polymer capacitor? Here are the top advantages that you stand to gain from this type of capacitor.

-High capacitance: The main advantage of polymer capacitors is despite their small size, polymer capacitors tend to offer a considerably high capacitance. This means that the capacitance is able to keep up with the demands of the capacitor. For example, a 1 uF capacitor can have a capacitance of 3,000 pF. This is very high and when compared to other types of capacitors, this value is very impressive.

-High stability: Another advantage of polymer capacitors is their ability to maintain its working condition even after long periods of time. This means that this type of capacitor has a very high tolerance toward humidity and temperature variations. This means that you can use this type of capacitor in applications where you need quality and reliability over long periods of time.

-Low profile: Another advantage you stand to gain from using polymer tantalum capacitors is their low profile in comparison with ceramic tantalum capacitors. This makes it easier for you to install this type of capacitor in your electronic equipment. On top of that, polymer capacitors are lightweight and thus making them easy on your equipment’s power supply unit (PSU).

-Low ESR: ESR is the measure used to determine the amount of resistance that is produced by a capacitor. As such, this type of capacitor produces very low ESR values. This is because polymer capacitors have a very high dielectric strength and thus have very good ESR values.

-Low noise: Another benefit you stand to gain from using polymer tantalum capacitors is their ability to reduce or eliminate noise produced by other types of devices. This makes it easy for you to install this type of capacitor in your electronic equipment.

Disadvantages of polymer capacitors

The main disadvantage of polymer capacitor is they tend to have high leakage current. This means that they may produce high voltage and current spikes, which can lead to damage to the equipment.

Application of polymer capacitors

From their features and advantages, there is no doubt that polymer capacitors have a wide range of applications including:

-Computer motherboards: This is because they are reliable and do not produce any noise.

-Electronic equipment: These are also very reliable and do not produce any noise.

-Telecommunications: These types of capacitors are used in telecommunication systems to reduce the effects of electromagnetic interference (EMI).

-Sensitive circuits due to their ability to reduce the noise

-High-end equipment: These are used in high-end equipment such as military and industrial applications.

-Medical equipment: These are used in medical equipment to reduce the effects of electromagnetic interference (EMI).

What should I look out for when buying polymer capacitors?

Here are some of the vital things that you should consider checking out;

-Capacitance: This is the measure of how much charge a capacitor can store. For example, if you have a capacitance of 100nF and you have a voltage of 10V, then your capacitance is 100×10=1000pF.

-Dielectric: This is the material that the capacitor is made out of. It has to be able to withstand the high electrical and temperature conditions that it is subjected to.

-Temperature rating: If you are using polymer capacitors in high-temperature environments, then you need to ensure that they are rated for such applications.

-Efficiency: This refers to how well a capacitor can remove charges from the circuit, which will affect its ability to pass electrical signals. For instance, if your application requires a low ripple current (a small value), then a low ESR value will be best suited for your application.

Buy from a reliable polymer capacitor manufacturer and supplier

Finally, ensure that you buy your capacitors from a reliable polymer capacitor manufacturer and supplier. The best way to ensure that you get the right product is to ask for samples. You can also use a sourcing agent to get such manufacturers and suppliers.

For instance, if you are buying in China, ICRFQ can do the sourcing for you. Simply contact us and we will do all that it takes to deliver quality polymer capacitors.

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