The most comprehensive ceramic chip capacitor (MLCC) knowledge chapter, worthy of the collection of electronic engineers.
Multilayer chip ceramic capacitor
——referred to as chip capacitor, chip capacity
Japan and Taiwan are often called multilayer capacitors or laminated capacitors.
MLCC—Multi-Layer Ceramic Capacitors
The 1960's was invented by the Americans, and the 1980's Japanese were carried forward and mass-produced with low-cost base metals.
Manufacturing process
Internal structure
Size series
Standard serialized form factor
The most commonly used inch unit system to represent:
0603—"06" means: length 0.06inch=1.6mm,
"03" means: width 0.03inch = 0.8mm
Also expressed in the International System of Units:
1608—"16" means: length 1.6mm
"08" means: width 0.8mm
Table 1 SMD Capacitor Full Series Size Chart
The minimum size is 01005 (length 0.25mm* width 0.125mm), and only a few Japanese companies are currently in mass production;
0201, 0402, 0603 are the largest size specifications currently available, and large MLCC companies can mass produce. Domestic, Shenzhen Yuyang is a manufacturer specializing in small size MLCC;
2220 and above size products, the market share is small, large enterprises generally do not produce, mainly small and medium MLCC companies in production supply.
Rated voltage series
The voltage series are:
3.3V, 6.3V, 10V, 16V, 25V, 50V;
100V, 200V, 250V, 500V, 630V;
1000V, 2000V, 3000V;
4000V, 5000V, 8000V
3.3V ~ 16V, low voltage, generally high capacity to replace electrolytic capacitors;
25V ~ 50V, is the most common product;
100V ~ 630V, medium voltage, generally 0805 and above size specifications;
1000V ~ 3000V, high pressure, generally size specifications of 1206 and above;
4000V or more is an ultra-high pressure product, and the corresponding size is 2220 and above.
Japanese brands occupy most of the market share of low-voltage and high-capacity products; the main manufacturers of medium and high-voltage products include TDK, Fenghua Hi-Tech and Heshentang.
Material (ceramic medium)
The ceramic dielectric materials used in ceramic chip capacitors (MLCC) are mainly divided into two major categories: paraelectric (class I) and ferroelectric (class II). Below them, there are many kinds of different temperature and characteristic laws, and the specific values ​​are different. Media material. The dielectric constants of these two types of dielectric materials vary with temperature, but the magnitude and regularity of the two types of dielectric materials are completely different. For this reason, EIA has developed "class I ceramic dielectric temperature coefficient" and "class II porcelain dielectric temperature characteristics" Set of capacity temperature characteristics standards.
Table 2 Temperature coefficient of dielectric type I
Example: COG indicates a temperature coefficient of (0±30) ppm/°C, which is NPO (Negative-Positive-"0", negative-positive-zero) in the MIL standard. COG and NPO are representations of different standard systems and are equivalent.
Table 3 Type II porcelain dielectric temperature characteristics
Example: X7R indicates a temperature range of -55 ° C to 125 ° C, based on 20 ° C, the allowable range of capacity is ± 15%
In practical applications, mainly the following three materials
(1) Doping modification of strontium zirconate SrZrO3, mainly manufacturing NPO (COG) MLCC
The electrical properties of this material MLCC are quite stable and hardly change with temperature, voltage, frequency and time:
The capacity change rate is -0±30ppm/°C from -55°C to 125°C;
The change in capacitance with frequency is less than ±0.3 ΔC;
The drift or hysteresis of the capacitance is less than ±0.05%;
The change in capacitance relative to the service life is less than ±0.1%;
The NPO (COG) MLCC is suitable for a variety of circuits, including high frequency circuits for stability requirements, and is commonly used for oscillators, tank tank capacitors, and coupling capacitors in high frequency circuits.
RF capacitors made by optimized design can be used up to 3 GHz, of which ATC is the RF-MLCC benchmarking company.
(2) Barium titanate BaTiO3 doping modification, is the main material for the manufacture of X7R, X5R MLCC products
Because the capacity that NPO(COG) MLCC can achieve cannot meet the requirements of the circuit for larger capacitance, such strontium titanate-based X7R and X5R MLCCs have been developed. Its capacity can be made larger under the same volume, X7R, X5R MLCC capacity can be very high, up to 100uF.
This material has poorer stability than NPO(COG)MLCC. The capacity of X7R and X5R MLCC varies with voltage, frequency conditions and time:
There is a DC bias characteristic, that is, when a high DC voltage is applied across the capacitor, its effective capacity is reduced;
The capacity change rate is +15% from -55 ° C to 125 ° C, and the curve is non-linear;
Changed by about 1% ΔC every 10 years, showing a change of about 5% in 10 years;
X7R and X5R MLCCs are widely used in non-high frequency circuits and are the largest type of capacitors, accounting for more than 60% of the total MLCC market.
(3) Barium titanate BaSrTiO3 doping modification, is the main material for the manufacture of Z5U, Y5V MLCC products
This type of material was developed to achieve greater capacity than the X7R and X5R MLCCs. This material can achieve high capacity and low cost per unit capacity.
Z5U and Y5V MLCCs have poor stability, are sensitive to temperature and voltage, and have a narrow temperature range:
-30 ° C ~ 85 ° C capacity change + 22% ~ -82%;
There is a strong DC bias characteristic;
High loss, up to 5% or even larger;
Despite its unstable capacity, it can achieve a capacity level that can replace electrolytic capacitors, and has a certain range of applications, mainly in the application of decoupling circuits.
In recent years, due to the development of X7R/X5R product manufacturing technology, the capacitance obtained by continuously reducing the film thickness of X7R/X5R MLCC dielectrics is close to the capacitance level of Y5V/Z5U MLCC. However, due to the large grain size, the Y5V/Z5U material cannot be further reduced in thickness and cannot effectively develop higher capacity products. In addition, the Y5V/Z5U materials have problems of large loss and poor reliability, so the Y5V/Z5U has gradually been eliminated.
Capacity and its error level
NPO (COG) capacitor
The capacity accuracy is about 5%. This material is generally used for smaller capacity. Under normal 100PF, products above 10nF can also be mass-produced, but the cost will be higher. The table below lists the maximum capacitance at the common specification voltage for this type of product.
Table 4 NPO (COG) MLCC mass production capacity maximum value
X7R capacitor
The capacity accuracy is about 10%, the capacity range is wide, and the conventional 100PF~47uF ​​can be produced.
The table below gives the maximum range of capacities that can be selected for the X7R capacitor.
Table 5 X7R MLCC mass production capacity maximum value
Naming rules
The name of the chip capacitor generally contains the following parameters: size, temperature characteristics, nominal capacity, capacity error level, rated voltage, terminal electrode type, and packaging method.
Typical naming rules are as follows:
0805X7R104K500NT
0805: size, "08" length 0.08 inches, 05 means width 0.05 inches;
X7R: capacity temperature characteristics;
104: electrostatic capacity, the first two digits are valid figures, the latter 4 indicates how many zeros 104 = 10 × 10000, that is, = 1000PF;
K: The error value achieved by the capacity value is 10%, and the error accuracy is related to the medium type;
500: It is required that the capacitor withstand voltage is 50V, the first two digits of 500 are valid figures, followed by the number of "0".
N: the end material, the general end is a three-layer electrode (silver / copper layer), nickel, tin;
T: packaging method, T means tape packaging.
MLCC main brands and their naming rules:
The world's major chip capacitor (MLCC) manufacturers are located in the Asia-Pacific region, with the most advanced technology in Japan, followed by Taiwan and South Korea, the main MLCC manufacturers:
Japan Murata, TDK, Kyocera, Taiyo Yuden; South Korea's Samsung; Taiwan's national giant, Huaxinke; the famous mainland is Fenghua Hi-Tech, Yuyang.
The manufacturer's product specification naming rules are different in form, but the specification code basically includes: size, temperature characteristics, nominal capacity, capacity error level, rated voltage and packaging method.
Major brand manufacturers MLCC naming rules:
Chip capacitor purchase
The parameters to be provided in the selection of chip capacitors are size, required accuracy, voltage requirements, capacity values, and further requirements for loss, porcelain strength, and DC bias characteristics.
about the price
The price is determined by the cost. The cost of MLCC has a great relationship with the size of the production batch. The size, capacity and voltage are standard serialized and continuous mass production specifications. The cost is low and the price will naturally be low.
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