Ceramic Capacitors Information

Ceramic capacitors are passive electronic components constructed using a ceramic dielectric. Ceramic materials have been used as insulators since the beginning of the study of electronics. Early ceramic insulators included mica, steatite, and titanium oxide, while modern technical ceramics include barium titanate, silicates, and aluminum oxide.

Ceramic capacitors consist of two electrical conductors separated by a dielectric material, in this case a type of ceramic. They are among the most commonly produced capacitor types. Like other capacitors, ceramic types are used to store potential energy, delay voltage changes, and filter unwanted signals.

Cross-section of a ceramic disc capacitor.

For basic information on capacitor construction, capacitance ratings, and applications please see Engineering360's Capacitors Specification Guide.

Types

Ceramic capacitors can be broadly classified into two different groups: multilayer and single layer.

Multilayer

Multilayer ceramic capacitors, often referred to as MLCCs, consist of several stacked ceramic capacitors. The image below shows a cross-section of an MLCC. The arrow labeled (1) denotes the stacked ceramic insulators, while (3) points to the electrode.

MLCCs are some of the most common capacitors and are extensively used in electronics applications. They can be produced as very small chips and feature excellent temperature stability and frequency characteristics.

Single Layer

Single layer capacitors, also known as monolithic capacitors, have a single layer dielectric. Single layer devices may take a variety of forms, including:

Dielectric Types

Ceramic capacitors can also be classified by their specific type of dielectric. Most ceramic dielectric types can also be labeled with an EIA (Electronic Industries Alliance) class designation as defined in EIA 535. Note that classes do not determine a product's superiority or inferiority, but exist to group capacitors with similar characteristics and applications.

The EIA labels capacitors using a three digit code to represent the dielectric's capacitance/temperature slope. More information on using these codes can be found here.

C0G (EIA designation) or NP0 ("Negative-Positive Zero"; industry term) materials are typically comprised of titanates, such as titanium dioxide, and are known as EIA Class 1 dielectrics. They have low dielectric constants and remain stable under variable voltage, temperature, and frequency conditions. Class 1 products are typically used in timing circuits and low-loss applications.

X7R is a common Class 2 material typically containing high levels of barium titanate. Class 2 dielectrics are temperature stable but experience moderate electrical property changes under variable environmental and electrical conditions. Class 2 products are relatively less long-lasting when compared to Class 1 materials, and may lose capacitance over time.

Z5U is a Class 3 dielectric material. They feature better volumetric efficiency than Class 2 products but are susceptible to very wide electrical variations under variable temperature conditions. Class 3 devices have generally been replaced by superior MLCCs and are considered nearly obsolete.

Standards

In addition to the EIA standard linked above, some ceramic capacitor standards include:

• BS EN 60384-21 -- Class 1 MLCC
• BS EN 60384-22 -- Class 2 MLCC
• MIL-C-11015 -- General specification for fixed ceramic capacitors
• MIL-PRF-20 [series] -- Reliability of ceramic capacitors

Additional Specifications

For information on additional selection details, including packaging, mounting, and product features, please visit the Capacitors Specification Guide.

References

MIT - Capacitors and Dielectrics

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