What Is a Conductive Polymer Capacitor?
A conductive polymer capacitor is a capacitor that uses a conductive polymer as the electrolyte material and is characterized by low impedance, excellent high-frequency characteristics, and insensitivity to temperature and applied voltage.
They have more stable capacitance, lower ESR (equivalent series resistance), and higher reliability than conventional capacitors, contributing to the realization of higher-performance electronic devices.
Uses of Conductive Polymer Capacitors
Conductive polymer capacitors are used in a wide range of applications due to their stable capacitance, low impedance, fast charge/discharge performance, and high reliability. The main applications are as follows:
1. Electronic Devices
Conductive polymer capacitors are used in portable electronic devices such as smartphones, tablets, and laptop computers. They are particularly suited for use in battery-related circuits and high-frequency circuits, which require high-speed charging and discharging performance.
2. In-Vehicle Electronic Equipment
In-vehicle electronic equipment is required to operate under severe environmental conditions such as high temperatures and high humidity. Conductive polymer capacitors are suitable for in-vehicle electronic equipment that requires high reliability and durability.
3. Organic EL Displays
The drive circuits of OLED displays require high-speed charging and discharging performance. Conductive polymer capacitors are used in the drive circuits of OLED displays because of their fast charging and discharging performance.
4. Solar Power Generation
Photovoltaic inverter circuits require high-speed switching. Conductive polymer capacitors are used in the inverter circuits of photovoltaic power generation, taking advantage of their high switching performance.
Principle of Conductive Polymer Capacitors
Conductive polymer capacitors are based on conventional tantalum electrolytic capacitors and aluminum electrolytic capacitors. Conventional types of electrolytic capacitors use manganese dioxide or electrolyte as the cathode.
Conductive polymer capacitors, on the other hand, are electrolytic capacitors that use a conductive polymer as the electrolyte. In other words, a polymer-type aluminum electrolytic capacitor uses aluminum foil as the anode, a conductive polymer as the electrolyte, and aluminum as the cathode material.
In the case of a polymer-type tantalum electrolytic capacitor, the anode is made of tantalum metal, and the electrolyte is made of a conductive polymer. The conductive polymer referred to here is a polymer such as polypyrrole polythiophene.
Types of Conductive Polymer Capacitors
The following types of conductive polymer capacitors are currently available in the market:
1. Conductive Polymer Aluminum Electrolytic Capacitor
The anode is an aluminum foil, the dielectric is an aluminum oxide film, and the electrolyte is a conductive polymer in contact with a silver electrode. It is a multilayer type and characterized by miniaturization.
2. Conductive Polymer Capacitor (Tantalum Electrolytic Capacitor)
A conductive polymer capacitor is a tantalum electrolytic capacitor in which the electrolyte is replaced by a conductive polymer instead of manganese dioxide. It is also characterized by its high safety.
3. Conductive Polymer Aluminum Solid Electrolytic Capacitor
The cathode material of conventional OS capacitors is replaced with a polymer. It features high ripple and high withstand voltage characteristics.
4. Conductive Polymer Hybrid Aluminum Electrolytic Capacitor
This type of capacitor combines an electrolyte and a conductive polymer as the electrolyte in an aluminum electrolytic capacitor. It has the same shape as the conventional aluminum electrolytic capacitor.
Other Information on Conductive Polymer Capacitors
Characteristics of Conductive Polymers
1. Low ESR (Equivalent Series Resistance)
Conductive polymers have low ESR due to their low resistance and large surface area. This enables high-speed charging and discharging.
2. High Heat Resistance
Conductive polymers generally have high heat resistance. This allows them to be used in high-temperature environments.
3. High Reliability
Conductive polymers are highly flexible, making them highly durable and reliable against external forces such as vibration. In addition, low ESR means low heat generation due to current during charging and discharging. This greatly affects the life of the capacitor and is one of the reasons for the long life of conductive polymer capacitors.