Differences in Dielectric Materials NP0, C0G, X7R, X5R, Y5V, Z5U
We all know that ceramic capacitors come in various dielectric materials. Different dielectric types have distinct polarization characteristics, leading to varying response speeds and polarization rates to changes in the electric field. Capacitance differs for the same volume, resulting in differences in dielectric losses and capacitance stability. Dielectric materials can be categorized into two classes based on their temperature stability: Class I ceramic capacitors and Class II ceramic capacitors. NPO belongs to Class I ceramics, whereas others like X7R, X5R, Y5V, Z5U belong to Class II ceramics.
Class I Ceramic Capacitors
Class I ceramic capacitors, formerly known as high-frequency ceramic capacitors, use non-ferroelectric (paraelectric) formulations for their dielectric material, primarily composed of TiO2 (dielectric constant less than 150). As a result, they exhibit the most stable performance. Alternatively, by adding small amounts of other (ferroelectric) oxides such as CaTiO3 or SrTiO3, they can form "expanded" temperature-compensating ceramics, demonstrating an approximately linear temperature coefficient, with the dielectric constant increasing to 500. Both of these dielectrics have low dielectric losses, high insulation resistance, and excellent temperature characteristics. They are particularly suitable for coupling capacitors in oscillators, resonant circuits, high-frequency circuits, and other circuits requiring low losses, stable capacitance, or temperature compensation.
How Temperature Characteristics are Represented in Class I Ceramics
The Temperature Capacitance Characteristic (TCC) of Class I ceramics is very small, often expressed in parts per million per degree Celsius (ppm/℃), with capacitance variation from the reference value often much less than 1 picofarad. The Electronic Industries Alliance (EIA) standard uses a code format of "letter + number + letter" to represent the temperature coefficient of Class I ceramics, such as the common C0G.
What Does C0G Represent in Terms of Temperature Coefficient?
C: Represents the effective number for the temperature coefficient of capacitance, which is 0 ppm/℃.
0: Represents the multiplication factor for the effective number, which is -1 (i.e., 10 to the power of 0).
G: Represents the tolerance in capacitance variation with temperature, which is ±30 ppm.
After calculation, the final Temperature Coefficient of Capacitance (TCC) for C0G capacitor is 0 × (-1) ppm/℃ ± 30 ppm/℃. For corresponding other Class I ceramics, such as U2J capacitor, the calculated TCC is -750 ppm/℃ ± 120 ppm/℃
Is NPO the same as C0G?
NPO and C0G are the same type of capacitor. NPO is the terminology used in the United States Military Standard (MIL), but it should be NP0 (zero). However, it is commonly written as NPO in Europe. This abbreviation stands for Negative-Positive-Zero, indicating its temperature characteristics. NPO capacitors have excellent temperature stability and do not exhibit capacitance drift with temperature changes.
As mentioned earlier, C0G is one of the best in terms of temperature stability among Class I ceramics, with a temperature coefficient close to 0, meeting the "negative-positive-zero" criteria. So, in essence, C0G and NPO are the same; they are just represented differently in two different standards. (Of course, capacitors like C0K, C0J, with slightly lower capacitance and accuracy, are also considered NPO capacitors.) Similarly, U2J corresponds to the MIL standard's group code N750.
NPO capacitors exhibit different frequency characteristics and dielectric losses depending on their packaging size. Larger packages have better frequency characteristics than smaller ones.
What is Class II Ceramic and What are Its Characteristics?
Class II ceramic capacitors, formerly known as low-frequency ceramic capacitors, use ferroelectric ceramics as their dielectric material, hence they are also called ferroelectric ceramic capacitors. These capacitors have a higher capacitance, nonlinear capacitance change with temperature, and higher losses. They are often used in electronic devices for bypassing, coupling, or in circuits with low requirements for losses and capacitance stability. Class II ceramic capacitors are further divided into stable and usable grades. X5R and X7R belong to the stable grade of Class II ceramics, while Y5V and Z5U belong to the usable grade.
What are the Differences Between X5R, X7R, Y5V, and Z5U?
The main differences lie in the temperature range and the variation of capacitance with temperature. The table below provides the meanings of these codes:
[The table with the meanings of X5R, X7R, Y5V, and Z5U is not provided in the given text. If you have the specific table or details you would like me to explain, please provide them, and I'd be happy to assist further.]
Taking X7R as an Example:
X: Represents the lowest operating temperature of the capacitor, which is -55°C.
7: Represents the highest operating temperature of the capacitor, which is +125°C.
R: Indicates the capacitance change with temperature, which is ±15%.
Similarly,
Y5V: Operates within a normal temperature range of -30°C to +85°C, with corresponding capacitance variations of +22% to +82%.
Z5U: Operates within a normal temperature range of +10°C to +85°C, with corresponding capacitance variations of +22% to -56%.
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