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Ceramic Capacitors: Applications, Types, and Key Considerations
December 19th, 2024
Ceramic capacitors are essential components in modern electronics. With their high stability, versatility, and reliability, they are widely used in a range of electronic applications. When choosing a ceramic capacitor, it is vital to understand classifications, common applications, and performance considerations.
Understanding Ceramic Capacitors
A ceramic capacitor is a type of fixed-value capacitor that uses ceramic as the dielectric. The models used in modern electrics are typically made with one or more layers of ceramic material and metal electrodes.
Ceramic capacitors are widely used in electronic design due to their small size and low levels of dielectric loss. These stable, reliable capacitors are often used for filtering, coupling, and smoothing in electronic circuits. They are non-polarized, allowing them to be connected in any direction in a circuit without regard for polarity placement.
Basic Construction of Ceramic Capacitors
Some ceramic capacitors feature a single ceramic dielectric layer sandwiched between two electrode layers. Multilayer ceramic capacitors (MLCC) use alternating layers of dielectric ceramic and metal electrodes with connecting terminals on each end. The number and thickness of the dielectric layers affect the capacitance and voltage rating.
The ceramic layers in a capacitor are usually made with ultra-fine ferroelectric or paraelectric materials such as barium titanate and calcium zirconate. Newer capacitors often have nickel electrodes, while high-voltage models may use palladium silver.
Common Applications in Modern Electronics
Ceramic capacitors are used in a few common applications, including:
- Decoupling. These capacitors reduce noise in the power supply, removing voltage variances that could impact other parts of the circuit.
- Ceramic capacitors can smooth out signal fluctuations. They can also even out voltage waveforms to create a consistent current.
- Filtering signals. Paired with inductors and resistors, ceramic capacitors can create filters that block unwanted frequencies. They are often used in audio systems to eliminate frequency interference.
Types of Ceramic Capacitors
Most ceramic capacitors fall into four classifications:
- Class I. Known for low losses and high stability, these capacitors are ideal for precision applications and resonant circuits.
- Class II. These capacitors are less stable than Class II but have higher capacitance per volume, making them a good choice for less-sensitive applications such as coupling and buffering
- Class III. Class III capacitors have a higher capacitance than Class II models. They are useful in applications that do not require high levels of temperature stability or precision.
- Class IV. These capacitors feature a barrier-layer design and are highly temperature-sensitive.
Class II, III, and IV capacitors are ferroelectric due to their barium titanate dielectrics. They may lose capacitance if they are not heated or charged — a process called aging.
Class I Capacitors: Precision and Stability
Class I ceramic capacitors use ceramic materials that are not sensitive to changes in temperature, which means that capacitance remains the same during temperature fluctuations. EIA describes these models as “temperature compensating.” Class I capacitors are not ferroelectric, which means they do not lose capacitance due to aging. They are a popular choice for circuits that require precision and/or stability, such as timers and oscillators.
Class II Capacitors: High Capacitance With Trade-Offs
Class II ceramic capacitors have higher capacitance per volume than Class I capacitors. However, because they are made with ferroelectric materials, these capacitors are less stable, vulnerable to aging, and more sensitive to temperature fluctuations. As a result, the capacitance tends to drop over time. Even with these trade-offs, Class II capacitors are commonly used in less-critical applications that require high capacitance, such as bypass circuits and noise filtering in power supplies.
Key Performance Considerations
As you select a ceramic capacitor, it is essential to consider factors that impact performance — namely, temperature sensitivity, voltage ratings, and required storage conditions.
Temperature Sensitivity: Class I vs. Class II
Class I ceramic capacitors are temperature-compensating, making them ideal for applications with varying levels of heat and cold. For example, the highly stable C0G capacitors experience a capacitance change of just +/-30PPM over a temperature range of -40 to +100°C.
By contrast, the capacitance of Y5P Class II capacitors can vary by +/-10% over a more limited temperature range of -30 to +85°C.
Temperature sensitivity can be a critical factor in high-heat applications such as downhole drilling electronics and low-temperature space systems.
Ways to compensate for temperature sensitivity include:
- Conducting thermal simulations to predict system temperatures
- Choosing a capacitor rated for anticipated temperatures
- Comparing project requirements to the maximum potential capacitance loss
Voltage Ratings and Safety Margins
The voltage rating on a ceramic capacitor indicates the maximum level of voltage that can be applied without breaking down the dielectric and impacting performance. If an extremely high voltage is applied, the capacitor can fail. Standard ratings range from 3kV to 20kV DC; Dean Technology offers high-voltage capacitors rated up to 50 kilovolts.
When voltage consistently approaches or exceeds the maximum rating, it can degrade the capacitor and reduce capacitance. To reduce this effect, it is common practice to choose a unit with a higher than necessary rating. The safety margin varies based on potential voltage fluctuations but usually ranges from 20% to 50%.
If you are using Class II capacitors, the safety margin should account for the DC bias effect — a drop in capacitance that happens when you apply a DC voltage. At higher voltages, the reduction can be as high as 80%.
Storage and Longevity Best Practices
Proper storage can increase the long-term reliability and performance of ceramic capacitors by maintaining capacitance and solderability. To prevent degradation, store capacitors in their original packages in a space that stays between 5° and 40°C and 20% to 70% relative humidity. Avoid areas with changing temperatures, moisture, and corrosives.
Why Ceramic Capacitors Are Essential for Modern Electronics
Ceramic capacitors are affordable, compact, and stable, making them key components in modern electronic design. As you search for the right capacitors, turn to Dean Technology for innovative solutions and high-performance dielectrics. To learn more, explore our product offerings.