What Exactly are Passive Components, and Why are MLCCs So Popular?

With MLCCs attracting new market attention, what exactly are the functions and advantages of these electronic components?

The function of the resistor is mainly to adjust the current and voltage, and the inductor is to filter the current noise, prevent electromagnetic interference, and stabilize the current. Capacitors are the main electrical energy storage components on the board, performing functions such as coupling and coordination. Among the three passive components, capacitors have the largest market size. They can be divided into ceramic capacitors, aluminum capacitors and tantalum capacitors. Currently, the most popular capacitors are MLCCs. (Multi-layer Ceramic Capacitors.)

Characteristics of Passive Components

The capacitance value of multilayer ceramic capacitors is proportional to the product surface area and the number of stacked layers of ceramic films. Product codes usually classify MLCCs by their package size. However, due to the advancement of ceramic film stacking technology, a smaller volume may not necessarily mean a smaller capacitance value. MLCCs have began to replace electrolytic and tantalum capacitors. but the latter two still occupy a considerable market share, and each has its own advantages. However, for high-performance consumer electronic products such as personal computers and smart phones, MLCC have pretty much replaced the other capacitors.

Ceramic capacitors are favored because of their physical properties such as high voltage and heat resistance, wide operating temperature range, and low loss rate when used at high frequencies. They can be produced as chips, reducing volume and price, and increasing stability. MLCCs are very suitable for mass production. Although the capacitance value of aluminum capacitors is high, and the degree of chip manufacturing is second only to MLCCs, their performance is more affected by the environment. Tantalum capacitors also have the advantages of DC bias and stable capacitance, low leakage loss, and pressure resistance to substrate deflection, but they have more pollution problems and are more expensive.

Not just traditional electronic products need passive components, but the automotive industry also needs passive components as well. In recent years, new products such as electric vehicles and self-driving cars have become popular. While cars in the past required nearly 2,000 passive components, newly designed cars may require as many as 10,000 passive components. This increase in demand has led to not only MLCCs being in short supply, but the delivery time of aluminum capacitors has also been extended to more than half a year. At present, the main global supplier of passive components is Japan. Although Taiwan is the second largest supplier of passive components, there has been relatively little investment in upstream material development. Nearly 70% of MLCC raw materials, such as interface ceramic powder, ceramic substrates, alumina substrates, quartz substrates, conductive adhesives, and cathode foils are sourced from Japan.

What is a Multilayer Ceramic Capacitor (MLCC)?

A Multi-layer Ceramic Capacitor (MLCC) is a kind of ceramic capacitor. Ceramic capacitors are divided into single-layer ceramic capacitors and multilayer ceramic capacitors (MLCC). Due to the advancement of ceramic film stacking technology, MLCCs can be directly attached through SMT (Surface Mount Technology), and the production speed is faster than electrolytic capacitors and tantalum capacitors. MLCCs have become the mainstream product of the capacitor industry, accounting for about 43% of the output value of capacitors, followed by aluminum electrolytic capacitors at about 32%.

MLCCs are composed of parallel ceramic and electrode materials. Its internal structure consists of ceramic layers and internal metal electrode layers alternately stacked. Each ceramic layer is sandwiched by two parallel electrodes up and down to form a flat capacitor. The inner electrode and the outer electrode are connected in parallel, so that the total storage capacity of the capacitor can be increased. The total capacitance of the multilayer ceramic capacitor is the sum capacitances of the layers.

The two main materials used in the construction of MLCCs, are a dielectric ceramic powder and internal and external electrodes. The main raw material of dielectric ceramic powder is barium titanate. After adding various additives, it forms NPO, COG, Y5V, X7R, Z5U and other types. Applications may vary according to the electrical characteristics desired. The dielectric ceramic powder determines the characteristics of MLCC. X7R, X5R and Y5V have high-capacitance values. In terms of grades, X5R and X7R are better than Y5V, while NPO is mainly used for communication products. In terms of price, for MLCCs of the same size and capacitance value, X7R≒X5R; Y5V; Y5U.

The metal used for the electrodes can account for more than 35% of the production cost of the capacitor. To keep up with the demand for increased speed of CPUs and communication components, the number of layers in MLCCs must also be increased. With each additional layer added to the MLCC, it is necessary to add a layer of internal electrodes. Palladium metal used in these electrodes is a rare and precious metal, the price is quite expensive, and the main supply is from Russia. As stocks are often insufficient, the industry replaces the palladium metal electrode material with base metal (nickel, copper) and other metals, hoping to reduce the cost but at the cost of efficiency.

MLCCs have a variety of different specifications, and the difference between each product mainly lies in the capacitance value (storage power per unit voltage), size (above 1210, 0805, 0603, 0402, 0201 and other specifications), temperature stability (Y5V, X7R and NPO, etc.), upper limit of operating voltage, safety certification, ESR (capacitance/time required for charging and discharging) and Q value (the degree of loss of input energy). Taking temperature stability as an example, MLCCs will have different temperature stability due to the difference of the main raw material dielectric ceramic powder. Among them, Y5V type MLCCs have the lowest unit capacitance cost, X7R is the second, and NPO is the highest. Due to the low technical difficulty of production, low price and many competitors, the MLCC of X7R and X5R will gradually replace the Y5V type as portable electronic products require higher temperature stability.

MLCCs can be divided into 0201, 0402, 0603, 0805 and larger than 1206 according to the size of the product. Type 0805 and type 0603 are mainly used for information products such as motherboards and notebook computers. Type 0402 and 0201 are mainly used in high-end mobile phones. With the trend of thin and light electronic products, the proportion of products with 0402 and 0201 specifications continues to increase, and the growth momentum comes from the demand for consumer electronic products such as iPod/iPhone, game consoles and LCD TVs.

Major global suppliers of MLCCs include: Japan's Murata Mfg (25% of the market), TDK (14%), Taiyo Yuden (8%), Kyocera, Panasonic, and Taiwan's Yageo (13%), Walsin Technology (13%), Holystone, Honey Hope Honesty, Darfon, and mainland China’s Fenghua. Japanese manufacturers mainly focus on high-capacity MLCCs. Taiwan's Yageo and Walsin Technology mainly produce medium-to-low-capacity products in bulk specifications, while Holystone mainly produces niche-type high-voltage and high-capacity MLC.