What are the different types of dielectric materials for SMD capacitors?

The parameters such as X5R, X7R, Y5V, Z5U, COG, COH, etc. of chip capacitors describe the type of dielectric material used for capacitor acquisition, temperature characteristics, and error parameters. Different values also correspond to the range of capacitor capacity. What are the differences? Let's explain it separately below

High frequency class: Capacitors made of this type of dielectric material are Class I capacitors, including general-purpose high-frequency COG, COH capacitors, and temperature compensated high-frequency HG, LG, PH, RH, SH, TH, UJ, SL capacitors. Among them, COG and COH capacitors have the most stable electrical performance and almost do not change with temperature, voltage, and time. They are suitable for high-frequency circuits with low losses and high stability requirements. The capacities of HG, LG, PH, RH, SH, TH, UJ, and SL capacitors change accordingly with temperature, and are suitable for low loss, temperature compensated circuits

X7R, X5R, X7S, X6S: Capacitors made of this type of dielectric material are Class II capacitors with high dielectric constant, higher capacity than Class I capacitors, and more stable temperature characteristics. They are suitable for circuits with a wide range of capacity and low stability requirements, such as isolation, coupling, bypass, frequency discrimination, etc

Y5V: Capacitors made of this type of dielectric material are Class II capacitors, which have the highest dielectric constant among all capacitors. However, their capacity stability is poor and they are sensitive to temperature, voltage, and other conditions. They are suitable for circuits that require high capacity and have little temperature change

Z5U: Capacitors made of this type of dielectric material are Class II capacitors, with temperature characteristics between X7R and Y5V. They have poor capacity stability and are sensitive to temperature, voltage, and other conditions. They are suitable for circuits that require high capacity, use temperature ranges close to room temperature for bypass, coupling, and low DC bias

Characteristics of Class I ceramics:

Class I ceramic capacitors, formerly known as high-frequency ceramic capacitors, use a non ferroelectric (paraelectric) dielectric formula with TiO2 as the main component (dielectric constant less than 150), which has the most stable performance.

; Alternatively, by adding a small amount of other (ferroelectric) oxides, such as CaTiO3 or SrTiO3, to form an "extended" temperature compensation ceramic, it can exhibit an approximately linear temperature coefficient, with a dielectric constant increasing to 500. These two types of media have low losses, high insulation resistance, and good temperature characteristics. Especially suitable for coupling capacitors in oscillators, resonant circuits, high-frequency circuits, and other circuits that require low losses and stable capacitance, or for temperature compensation

Method for expressing the temperature characteristics of Class I ceramics:

The temperature capacity characteristic (TCC) of Class I ceramics is very small, often in ppm/℃, and the change in capacity from the reference value is often much smaller than 1 pi method.

. The Electronic Industries Association (EIA) standard uses the code form of "letter+number+letter" to represent the temperature coefficient of Class I ceramics. For example, the common C0G What is the temperature coefficient represented by C0G

C indicates that the significant number of the temperature coefficient of the capacitor is 0ppm/℃

0 indicates that the multiplication factor of the significant number is -1 (i.e. 10 to the 0th power)

G indicates a tolerance of ± 30ppm with temperature change

After calculation, the final TCC of the C0G capacitor is: 0 × （-1）ppm/℃±30ppm/℃。 The corresponding temperature coefficient of other Class I ceramics, such as U2J capacitors, is calculated as -750 ppm/℃ ± 120 ppm/℃& nbsp;

Relationship between NPO and C0G:

NPO is a term in the US Military Standard (MIL), which should actually be NP0 (zero), but it is generally written as NPO (Europe).

. This is the abbreviation for Negative Positive Zero, used to represent the temperature characteristics of. It shows that the capacitance temperature characteristic of NPO is very good, and the capacitance value does not drift with the change of positive and negative temperature As we have already known, C0G is the most temperature stable type of Class I ceramics, with a temperature characteristic of approximately 0, which satisfies the meaning of "negative positive zero". So C0G is actually the same as NPO, just two standard representations (of course, C0K, C0J, etc. with smaller capacitance and slightly lower accuracy are also NPO capacitors). Similarly, U2J corresponds to the group code N750 in the MIL standard NPO is the most commonly used single crystal ceramic capacitor with temperature compensation characteristics. Its filling medium is composed of rubidium, samarium, and other rare oxides NPO capacitors are one of the capacitors with the most stable capacitance and dielectric loss. The change in capacity from -55 ℃ to+125 ℃ is 0 ± 30 ppm/℃, and the change in capacitance with frequency is less than ± 0.3 Δ C。 The drift or hysteresis of NPO capacitors is less than ± 0.05%, which is negligible compared to thin film capacitors that are less than ± 2%. Its typical capacity relative changes the lifespan within ± 0.1%. The capacitance and dielectric loss characteristics of NPO capacitors vary with the packaging form, and the frequency characteristics of the packaging size are better than that of the packaging size. The following table provides the selectable capacity range of NPO capacitors NPO capacitors are suitable for slot capacitors in oscillators, resonators, and coupling capacitors in frequency circuits& nbsp;