Material specifications of SMD Capacitors

SMD capacitor (MLCC) Multilayer Ceramic Capacitor
Generally, the SMD capacitor refersMultilayer Ceramic Capacitors), AbbreviationMLCC. It is inSome ceramic film billet are covered with electrode Propeller Material, and then merged into an integral whole.,Encapsulated with Resin. It has the advantages of small size, large capacity, high Q value, high reliability and high temperature resistance. It also has the disadvantages of large capacity error and high temperature coefficient. It is generally used in noise bypass, filter, integral, and oscillating circuit.
Conventional SMD capacitors are divided by materialCOG (NPO), X7R, Y5VCommon packages include 0201, 0402, 0603, 0805, 1206, 1210, 1812, and 2010.

 

The main difference between NPO, X7R, z5u, and Y5V is that they have different filling media. In the same volumeThe capacity of capacitors composed of different filled media varies, and the dielectric loss and capacity stability of the capacitors vary accordingly.. Therefore, when using a capacitor, you should choose different capacitors Based on the function of the capacitor in the circuit.

The above table shows the temperature characteristics of different materials.

One NPO Capacitor

NPO is one of the most commonly usedSingle-Chip Ceramic Capacitor with Temperature Compensation Characteristics. It is filled with medium consisting of Rb, SM and some other rare oxides.
NPO capacitor isOne of the most stable capacitors with capacitance and Dielectric Loss. InThe capacity changes from-55 ℃ to + 125 ℃ to 0 + 30ppm/℃, and the electrical capacity changes with the frequency less than + 0. 3 Delta C. The drift or lag of the NPO capacitor is less than ± 0. 05%, which is negligible for the film Capacitor larger than ± 2%. The relative service life of typical capacity is less than ± 0. 1%. NPO capacitors vary with the encapsulation form, and their capacitance and dielectric loss vary with frequency,Large packages have better frequency characteristics than small packages.. NPO capacitors are suitableChannels and capacitors of the oscillator and Resonator, AndCoupling capacitance in High-Frequency Circuits.

Two X7R Capacitors
The X7R capacitor is calledTemperature-stable Ceramic Capacitor. When the temperature is-Its Capacity changes from 55 ℃ to + 125 ℃ to 15% ℃.Note thatThe capacitor capacity variation is non-linear..
The capacity of the X7R capacitor varies with the voltage and frequency.Changes with time, Which changes about 1% △c every 10 years. The result is about 5% changed every 10 years.
X7R capacitor is mainly used inLess demanding industrial applicationsAnd whenWhen the voltage changes, the capacity changes are acceptable.. Its main feature is that the electric capacity can be relatively large under the same volume.

Three z5u Capacitors
The z5u capacitor is called"General" ceramic monolithic capacitor. The first thing to consider here is:Temperature range,Z5u capacitor is mainly used for its small size and low cost.. The z5u capacitor has the maximum electrical capacity under the same volume for the above three ceramic single-chip capacitors. However, its electric capacity is greatly affected by the environment and working conditions, and its aging rate can reach a maximum reduction of 5% every 10 years.
Despite its unstable capacitySmall Size, equivalent series inductance (ESL) and equivalent series resistance (ESR) low, good frequency responseSo that it has a wide range of applications. Especially in the application of the decoupling circuit.
Other technical indicators of z5u capacitors are as follows:
Operating temperature range + 10 ℃ --- + 85 ℃
Temperature Characteristics + 22% -----56%
Maximum Dielectric Loss 4%

4y5v Capacitor
Y5V capacitor is a typeGeneral Capacitors with a certain temperature limitIn the range of-30 ℃ to 85 ℃, the capacity change can reach + 22% to-82%.
The high dielectric constant of Y5V allows the manufacture of up to 4.7 μF capacitors in smaller physical sizes.
Other technical indicators of Y5V capacitors are as follows:
Operating temperature range-30 ℃ --- + 85 ℃
Temperature Characteristics + 22% -----82%
Maximum Dielectric Loss 5%

Main characteristic parameters of capacitor:
(1)Capacity and error: The maximum allowable deviation between the actual capacity and the nominal capacity. Generally, the used capacity error is: J-level ± 5%, K-level ± 10%, and m-level ± 20%.The allowable error of precision capacitors is small, while the error of electrolytic capacitors is large.They use different error levels. The precision level of a common capacitor is the same as that of a resistor. Represented by letters: Level D-± 0. 5%; F-± 1%; G-± 2%; j-± 5%; k-± 10%; m-± 20%.
(2)Rated operating voltage: Capacitor in the circuitLong term stable and reliable operation, the maximum DC voltage, also known as Withstand Voltage. ForFor devices with the same structure, medium, and capacity, the higher the voltage, the larger the volume..
(3)Temperature Coefficient: Within a certain temperature range, each temperature change is 1 ℃, and the relative change value of the electric capacity. The smaller the temperature coefficient, the better.
(4) insulation resistance: used to indicate the electric leakage. It is usually a small capacity capacitor with a large insulation resistance, which can be several hundred megabytes of OHM or several gigabytes of Ohm. The insulation resistance of electrolytic capacitors is generally small. Relatively speaking, the larger the insulation resistance, the better, and the smaller the leakage.
(5)Loss: Under the action of an electric fieldEnergy consumed by containers in a unit of time. These losses mainly come from Dielectric Loss and Metal loss. Usually expressed by the tangent of the loss angle.
(6)Frequency features: The properties of the electric parameters of the capacitor that change with the electric field frequency. Capacitor working in high-frequency conditions, because the dielectric constant at high frequency is smaller than that at low frequency, the electrical capacity is also reduced accordingly. The loss also increases with the increase in frequency. In addition, when working at high frequency, the distribution parameters of the capacitor, such as the pole resistance, the resistance between the lead and the pole, the inductance of the pole, and the lead inductance, will affect the performance of the capacitor. All these limits the usage frequency of the capacitor.

The maximum usage frequency varies with different types of capacitors. The small mica capacitor is less than 300 MHz; the disc-type porcelain dielectric capacitor is 200 MHz; the cylindrical porcelain dielectric capacitor is 3000 MHz; the disc-type porcelain dielectric can reach MHz; and the small paper dielectric capacitor is 80 MHz; medium Paper Capacitor is only 8 MHz.
The performance of the patch capacitor is evaluated from three aspects: the four general electrical properties of the patch capacitor, that isCapacity cap. Loss DF, insulation resistance IR and Voltage Resistance DBVGenerally, the loss value of X7R products is DF <= 2.5%. The smaller the value, the better. IR * cap> 500 euro * method, BDV> 2.5ur.
SecondAcceleration performance of SMD CapacitorIn 125deg. c Environment Temperature and 2.5ur DC load conditions, the chip should be able to withstand 100 hours without breakdown, good quality can withstand 1000 hours without breakdown. AgainProduct heat-resisting impact performanceImmerse the capacitor in the 300deg. c tin Furnace for 10 seconds, do a few more particles, observe the surface crack under the microscope, and then test the capacity loss and compare with the thermal shock to determine whether the chip has internal cracks. The quality of the SMD capacitor may be poor due to circuit problems, it may also be caused by factors such as poor specification selection during design or thermal impact of mechanical force on the surface mount, which may cause some damage to the SMD capacitor.