MLCC: Applications and Future Development

Ⅰ What is MLCC?

MLCC (Multi-layer Ceramic Capacitors) is made of the ceramic dielectric film with printed electrodes (inner electrode) stacked in a misaligned manner, sintered at high temperature at one time to form a ceramic chip, and then sealed with a metal layer (outer electrode) at both ends of the chip to form a monolithic-like structure, so it is also called a monolithic capacitor.

MLCC

There are many types of capacitors, which are divided into non-polar variable capacitors, non-polar fixed capacitors, polarized capacitors, etc. From the material point of view, there are mainly: CBB capacitors (polyethylene), polyester capacitors, porcelain chip capacitors, mica capacitors, monolithic capacitors (i.e. chip capacitors or MLCC), electrolytic capacitors, tantalum capacitors, etc.

Ⅱ MLCC Classification

According to the temperature characteristics, material, and production process, MLCC can be classified as follows: NP0, C0G, Y5V, Z5U, X7R, X5R, etc. NP0 and C0G have smooth temperature characteristics, small capacitance, and high price; Y5V and Z5U have large temperature characteristics, large capacitance, and low price; X7R and X5R are between the above two.

According to the size of the material, It can roughly be divided into 3225, 3216, 2012, 1608, 1005, 0603, 0402. The larger the value, the wider and thicker the SIZE. The most commonly used for 3225 minimum 0402.

Chip multilayer ceramic capacitor (MLCC) materials are widely used in portable products. It can be divided into two main categories based on temperature characteristics: C0G products and X7R (X5R) products.

The capacity of C0G type MLCC is mostly below 1000pF, and the main performance index involved in the low power consumption of this type of capacitor is the loss angle tangent tanδ (DF). The conventional C0G products with noble metal electrodes (NME) have DF values ranging from (2.0 to 8.0) × 10-4, while the C0G products with technically innovative alkali metal electrodes (BME) have DF values ranging from (1.0 to 2.5) × 10-4, which is about (31 to 50)% of the former. The low power consumption characteristics of these products are more significant in GSM, CDMA, cordless phones, Bluetooth, and GPS systems that contain T/R module circuits.

The capacity of the X7R (X5R) class MLCC is mainly concentrated above 1000pF. The main performance index involved in the low power consumption of this class capacitor is the equivalent series resistance (ESR).

Ⅲ MLCC core technology 

1. Material technology (preparation of ceramic powder)

Nowadays, ceramic powders for MLCC are divided into three main categories (Y5V, X7R, and COG). Among them, X7R material is the most competitive specification in various countries and is also one of the varieties with the largest market demand and electronic machine usage. Its manufacturing principle is based on the modification of nano-scale barium titanate ceramic material (BaTiO3). According to the demand for large capacity (above 10μF), Japanese manufacturers (such as Murata) added rare earth metal oxides to the wet BaTiO3 with D50 of 100nm to produce high-reliability X7R ceramic powder, and finally produced a small size of 10μF-100μF (Such as 0402, 0201, etc.) MLCC.

One NOP and three X7R

2. Laminated printing technology (multilayer dielectric film laminated printing)

How to manufacture higher capacitance value MLCC on the basis of 0805, 0603, 0402 and other small sizes has been one of the important issues in the MLCC industry. In recent years, with the continuous improvement of materials, processes, and equipment levels, Japanese companies have practiced stacking 1000 layers on 2μm thin film dielectrics and produced 100μFMLCCs with a single layer dielectric thickness of 1μm. It has a lower ESR value and wider operating temperature (-55°C to 125°C) than chip tantalum capacitors.

3. Co-Firing Technology (Ceramic Powder and Metal Electrode Co-Firing)

The structure of MLCC components is simple, consisting of three metal layers: ceramic dielectric, inner electrode metal layer, and an outer electrode. MLCC is made of multiple layers of ceramic dielectric printed with inner electrode paste, stacked, and co-fired. For this reason, it is inevitable to solve the problem of co-fired ceramic powder and metal electrodes, i.e. how to avoid delamination and cracking of ceramic media and inner electrode metal with different shrinkage rates after high-temperature firing.

The key technology to solve this problem is co-fired technology, mastering co-fired technology can produce thinner media (less than 2μm), higher layer (more than 1000 layers) of MLCC. At present, Japanese companies are ahead of other countries in the technology of MLCC sintering special equipment. They not only have a variety of nitrogen atmosphere furnaces (bell and tunnel furnaces) but also have obvious advantages in equipment automation and precision.

Ⅳ MLCC industry chain and application areas

The upstream of MLCC industry is mainly ceramic powder materials and electrode materials, among which ceramic powder materials include high-purity barium sodium titanate base powder and MLCC formula powder, which belong to the cross-section of nano-materials, rare earth functional and information functional materials; electrode materials include nickel, silver, palladium, copper, silver, etc.

MLCC industry midstream is mainly the finished product manufacturing.

MLCC industry downstream is the terminal electronic product industry. MLCC products have a wide range of applications, its downstream customers cover almost all areas that require electronic equipment, from aerospace, aviation, ships, weapons, and other weapons and equipment fields to rail transportation, automotive electronics, smart grid, new energy, consumer electronics and other industrial and consumer fields.

Ⅴ MLCC industry market demand size and development potential     

The global MLCC market size reached $12 billion in 2019, up 4.6% year-on-year, and the global MLCC market size CAGR (compound annual growth rate) from 2011-2019 reached 7.08%. According to professional institutions, with the increase of 5G, automotive electronics, and IoT penetration, MLCC demand will continue to grow, and the global MLCC industry demand will likely grow at around 10%-15% per year for at least the next five years. Please note that this forecast data is the volume of the whole industry, considering that China has more room for development in the above areas.

Global MLCC market size chart

1. Incremental volume in 5G base stations   

5G base station application environment is harsh. From the single macro base station MLCC demand, 5G base station for MLCC demand mainly from the baseband processing unit (BBU) and active antenna processing unit (AAU), where BBU needs high capacitance, AAU has a large number of high-power high Q capacitance demand. In addition, 5G needs to load more and higher frequency bands, the circuitry in the base station will become more complex, and the requirements for MLCC reliability will become higher. According to the data provided by VENKEL, the amount of MLCCs for 4G base stations is 3,750, while the amount for 5G base stations is significantly increased to 15,000. According to the forecast, the demand for MLCCs in base station communication equipment will grow 2.1 times more in 2023 than in 2019.

2. Incremental growth in the automotive sector, especially in pure electric vehicles

Countries around the world are making efforts to advance the process of converting gasoline and diesel vehicles to electric vehicles (EVs). For example, China has set a target of 20% of new vehicle sales of new energy vehicles by 2025; European countries have also set different target years to reach 100% of new vehicle sales of EVs. The three electric systems in new energy vehicles can significantly drive the demand for MLCC. In the EV development, the development of self-driving cars is also accelerating, and with the gradual increase of ADAS (Advanced Driver Assistance System) penetration, MLCC usage will also increase significantly.

Demand forecast of MLCC for vehicles

In addition, MLCC's demand growth is also benefiting from more audio and display screens being equipped in cars. According to industry leader Murata, the power system of pure electric vehicles will use 2,700-3,100 MLCCs, much higher than the demand for 450-600 MLCCs in traditional fuel vehicles. According to Murata, demand for MLCCs in the automotive sector in 2025 is expected to grow more than 1.8 times that of 2019.

Ⅵ MLCC Selection

There are many factors to consider when selecting capacitors, and the following discusses the elements of capacitor selection for MLCCs.

1. MLCC selection: meeting the parameters is not enough

The general decision logic of purchasing goods is: can it work, is it good, is it durable, and the price. In fact, this logic can also be applied to the MLCC selection process: first of all, MLCC parameters to meet the circuit requirements, followed by whether the parameters and media can make the system work in the best condition. Second, Whether there are defective incoming MLCCs, how reliable they are, and finally, whether the price is advantageous and whether the suppliers cooperate in a timely manner. Many design engineers do not pay attention to passive components, thinking that only by theoretical calculation of parameters on the line. In fact, the selection of MLCC is a complex process.

2. Selection elements

-Parameters: capacitance value, tolerance, withstand voltage, operating temperature, size

-Material

-DC bias effect

-Failure

-Price and availability

3. Different dielectric properties determine different applications of MLCC

-C0G capacitors have high-temperature compensation characteristics and are suitable as bypass capacitors and coupling capacitors.

-X7R capacitors are temperature stable ceramic capacitors, suitable for less demanding industrial applications.

-Z5U capacitors are characterized by their small size and low cost and are particularly suitable for decoupling circuits.

-Y5V capacitors have the worst temperature characteristics, but have high capacity and can replace low capacitance aluminum electrolytic capacitors.

MLCCs are commonly used with different dielectric specifications such as C0G(NP0), X7R, Z5U, Y5V, etc. Different specifications have different characteristics and applications. The main difference between C0G, X7R, Z5U, and Y5V is that they have different filling media. Under the same volume, the capacity of the capacitor is different due to the different filling medium, and the capacitor's dielectric loss and capacity stability are also different, so when using the capacitor, different capacitors should be selected according to their different roles in the circuit.