What are the temperature characteristics in ceramic capacitors?

Capacitor technology trend under the development of new energy vehicles

Any hardware circuit is inseparable from the basic passive components, and capacitors are also indispensable in new energy vehicles. In general, its role is nothing more than filtering, absorption and resonance. But it is these basic functions that help build the core electronic control system of new energy vehicles.

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The "new energy" road of ceramic capacitors

When it comes to capacitors, probably most people's first reaction is a common component like a "screw". But since 2021, capital has seen the possibility of rapid growth in this segment: In the primary market, Shanghai Yingfeng Electronics, a leading subdivision enterprise, completed two consecutive rounds of financing this year, and its valuation rose sharply; In the secondary market, relevant listed companies are also expanding production in a big way. Among them, Farad electronic automotive film capacitors will be expanded by 100% in 2021, and another 100% is planned to be expanded in 2022; Jianghai film capacitors have not only entered a large number of applications in consumer electronics and industrial equipment, but also began mass delivery in the field of new energy electric vehicles and military industry, and the production of automotive film capacitors will also be expanded by 70-80% in 2022. Ceramic capacitors: capacitors with ceramic as dielectric materials, there are many branches of such capacitors, including various packages and withstand voltages, in which the internal dielectric materials are also divided into ferroelectric ceramics, barium titanate, talc and other materials, and then use pyrolysis and other methods to make an outer wrapped electrode. Ceramic capacitors have no polarity, ceramic capacitors with wires generally have high withstand voltage, and are used in high-voltage occasions with safety requirements; The most widely used is the chip multilayer ceramic capacitor (MLCC), which has the characteristics of small size, low price, high specific volume and high precision, and can be applied to high frequencies, but the material is brittle and the relative capacity is low. Representative companies: Fenghua Hi-Tech (000636), Sanhuan Group (300408), etc. According to the data of the China Electronic Components Industry Association, ceramic capacitors accounted for more than 50% of the global capacitor market in 2019 due to their wide range of application fields and high cost performance, followed by aluminum electrolytic capacitors (accounting for more than 30%), film capacitors and tantalum electrolytic capacitors accounted for less than 10%. Compared with other capacitors, film capacitors have the advantages of excellent high temperature and high pressure resistance, good reliability, long life, and overvoltage self-healing ability. In various frequency conversion and AC/DC conversion scenarios, such as electric drives, OBCs, charging piles of new energy vehicles, as well as inverters and converters of photovoltaic and wind power, film capacitors are widely used.

What are the uses of ceramic capacitors?

Class 1: Small temperature coefficient, suitable for tuning circuits and circuits that require compensation effects. Class 2: High dielectric constant, suitable for bypassing, coupling, DC blocking and filtering circuits. Class 3: large capacity, small size, low voltage. Used for filtering, bypassing, coupling circuits. AC: Anti-electromagnetic interference. High-frequency ceramic capacitors (Class I porcelain dielectric capacitors): good capacity stability, small dielectric loss, high insulation resistance, but small capacity; It is mainly used in high-frequency circuits and high-frequency high-voltage circuits in electronic equipment. (e.g. secondary output rectification of computer motherboard and switching power supply) Low-frequency ceramic capacitors (Class II ceramic dielectric capacitors): refers to capacitors with ferroelectric ceramics as dielectrics, Class II ceramic dielectric capacitors have small capacitance, large capacity, but poor stability and large loss. It is mainly used for low-frequency bypass, DC blocking, and filter circuits. (e.g. filtering after AC rectification)