What are Multilayer Ceramic Capacitors (MLCC)?
Multilayer ceramic capacitors (MLCC), also known as ceramic chip capacitors, are a type of capacitor with multiple layers of ceramic material as dielectric. They are many single layer capacitors stacked together in one package. MLCCs have alternating layers of metal electrodes and ceramic dielectric, acting as a ‘dam’ that charges and discharges electricity. They regulate current flow in a circuit and prevent electromagnetic interference between components. MLCCs are used in many electronic devices, computers, smartphones and TVs.
Construction and Styles of MLCC Capacitors
- Ceramic capacitors can be constructed in different styles, surface-mount, through-hole and radial.
- Multilayer ceramic capacitors (MLCCs) are a type of ceramic capacitor that uses alternating layers of ceramic and metal electrodes.
- Ceramic capacitors can also be constructed in special shapes and styles, feed-through capacitors and power capacitors.
- The construction and style of a ceramic capacitor determines its electrical characteristics and applications.
- MLCCs are made in standard shapes and sizes for same handling.
Types of Ceramic Capacitors
- Ceramic capacitors are divided into two application classes: general-purpose and high-reliability.
- General-purpose ceramic capacitors are used in many applications, power supplies, filters and decoupling.
- High-reliability ceramic capacitors are used in applications where reliability and stability is critical, aerospace and defense industries.
- Ceramic capacitors can be classified based on dielectric material, NP0, X7R, X5R and Y5V.
- Each type of ceramic capacitor has its own characteristics and applications.
MLCC Capacitors Electrical Characteristics
Ceramic capacitors have many electrical characteristics, capacitance value, tolerance and frequency response. The desired dielectric properties are critical to ensure high capacitance and performance as they directly affect the final product’s electrical behavior. The capacitance value of a ceramic capacitor is determined by the ceramic material composition and the capacitor design. Ceramic capacitors can be used in many applications, power supplies, filters and decoupling. The electrical characteristics of a ceramic capacitor determines its suitability for an application. MLCCs have low impedance, equivalent series resistance (ESR) and equivalent series inductance (ESL) so they can achieve higher capacitance values compared to other capacitor types.
Advantages of MLCC Capacitors with High Capacitance Values
- High capacitance density due to multi-layered construction.
- Low ESR for efficient discharge.
- Ideal for applications where space is limited, such as mobile devices.
- Multilayer ceramic chip capacitors (MLCCs) have high capacitance value and small size, suitable for many applications.
- They are also relatively cheap compared to other capacitors.
Applications of MLCC Capacitors
- Used in power supplies and voltage regulators for filtering out noise and ripple.
- Used in decoupling circuits to isolate one circuit from another.
- Used in timing circuits to stabilize frequency and provide accurate timing signals.
- Used in RF filters to tune circuits to specific frequencies and reject unwanted signals.
- MLCCs are used in many electronic devices, computers, smartphones and TVs.
Ceramic Materials and Properties
- Ceramic materials are used as dielectric in MLCC capacitors.
- The ceramic material determines the electrical behavior and therefore applications of the capacitor.
- Ceramic materials can be classified based on dielectric properties, NP0, X7R, X5R and Y5V.
- Each type of ceramic material has its own characteristics and applications.
- The ceramic material used in MLCCs is typically made from ferroelectric raw materials.
Manufacturing Process and Quality Control
- A thin ceramic foil is cast from a suspension of powder with a suitable binder.
- Rolls of foil are cut into equal-sized sheets, which are screen printed with a metal paste layer.
- Sheets are stacked in the required number of layers and solidified by pressure. Electrodes are stacked in an alternating arrangement slightly offset from each other.
- The process involves many steps, base metal or precious metal electrodes are used.
- The process ensures the capacitors meet specific voltage ratings so they can operate safely without damage in high and low voltage applications.
Design Considerations and Selection
When designing with multilayer ceramic capacitors (MLCCs), several factors must be considered to ensure optimal performance and reliability. Here are some
key design considerations and selection criteria:
- Capacitance Value: The capacitance value of an MLCC is determined by number of layers, dielectric constant of ceramic material, active area and dielectric thickness. To get higher capacitance values, engineers can increase the number of layers, use ceramic material with higher dielectric constant or increase the active area.
- Voltage Rating: The voltage rating of an MLCC is determined by dielectric thickness and voltage withstanding capability of ceramic material. Higher voltage rating can be achieved by increasing dielectric thickness or selecting ceramic material with higher voltage withstanding capability.
- Temperature Range: MLCCs are available in various temperature ratings, from -55°C to 125°C. It is important to select a capacitor with temperature range that matches the circuit operating conditions to ensure reliable performance.
- Dielectric Material: The choice of dielectric material affects the performance and reliability of an MLCC. Common ceramic materials like NP0, X7R and Y5V have different dielectric constants, temperature coefficients and voltage withstanding capabilities making them suitable for various applications.
- Plate Capacitor Enhanced Design: The plate capacitor enhanced design of an MLCC has alternating layers of ceramic and metal, metal layers act as capacitor plates. This design allows higher capacitance values and improved reliability.
- Single Layer Capacitors Stacked: MLCCs are constructed by stacking single layer capacitors in an alternating arrangement, slightly offset from each other. This design approach allows higher capacitance values and improved reliability.
- Alternating Layers: The alternating layers of ceramic and metal in an MLCC contribute to higher capacitance values and improved reliability. Ceramic layers are dielectric and metal layers are capacitor plates.8. Dielectric Thickness: Dielectric thickness of an MLCC affects both capacitance value and voltage rating. Thicker dielectric results in lower capacitance value but higher voltage rating, so it’s important to balance these based on application requirements.
- Higher Capacitance Values: Due to multilayer design, MLCCs can achieve higher capacitance values than other types of capacitors. This makes them suitable for applications that require high capacitance in small form factor.
- Ferroelectric Raw Materials: Some MLCCs use ferroelectric raw materials which have high dielectric constant and can be used to achieve higher capacitance values. These materials can improve performance and reliability of capacitors.
- Rated Voltage: Rated voltage of an MLCC is the maximum voltage the capacitor can withstand without failure. It’s important to select an MLCC with rated voltage that matches the circuit operating voltage to ensure safe and reliable operation.
By considering these design considerations and selection criteria, engineers can ensure their MLCCs meet the performance and reliability requirements of their application.
Reliability and Failure Modes
- MLCC capacitors can fail due to many reasons including overheating, overvoltage and physical stress.
- Reliability of an MLCC capacitor is determined by its design, materials and manufacturing process.
- MLCC capacitors can be designed to meet specific reliability requirements such as high-reliability applications.
- Failure modes of MLCC capacitors can be classified into several categories including electrical, thermal and mechanical.
- Reliability of MLCC capacitors is critical in determining its suitability for a particular application.
Safety and Regulatory Compliance
- MLCC capacitors must comply with various safety and regulatory standards such as RoHS and REACH.
- Safety of MLCC capacitors is determined by its design, materials and manufacturing process.
- MLCC capacitors can be designed to meet specific safety requirements such as high-voltage applications.
- Regulatory compliance of MLCC capacitors is critical in determining its suitability for a particular application.
- MLCC capacitors must also comply with various industry standards such as IEC and JEDEC.
Future Developments and Trends
- Demand for MLCC capacitors is expected to increase due to growing use of electronic devices.* New ceramic materials and manufacturing processes will improve MLCC capacitors performance and reliability.
- Miniaturization and higher capacitance values will continue.
- MLCC capacitors will be used in emerging applications such as 5G and IoT.
- New technologies like 3D printing will improve MLCC capacitors manufacturing process.
Summary
- MLCC is a type of capacitor that uses multiple layers of ceramic material as dielectric.
- They are used in power supplies, filters and decoupling.
- Design and selection of MLCC capacitors depends on application requirements.
- Reliability and safety of MLCC capacitors determines its suitability for an application.
- Future of MLCC capacitors will be better.