WHAT ARE THE UNIQUE PROPERTIES OF CERAMIC DIELECTRICS?

A ceramic capacitor is a fixed-value capacitor that uses ceramic material as its dielectric. It is very common in electronic circuits for applications ranging from general decoupling and noise filtering to use in high-frequency and high-precision circuits. Ceramics capacitors are also found in integrated circuits.

Ceramic capacitors are typically made of multiple alternating layers of ceramic dielectric and metal electrode (multilayer ceramic capacitors, or MLCCs for short), and are most widely produced capacitors globally. Common varieties include ceramic disc capacitors (usually through-hole), surface-mount MLCCs, and specialized forms for high-voltage or EMI suppression. Ceramic is a non-polarized inorganic insulator, giving good reliability and frequency response to capacitors.

Classes of Ceramic Capacitors

Ceramic capacitors are divided into two classes.

• Class 1: Precision, stable, low-loss, used in resonant and timing circuits. NP0/C0G types offer tight tolerances even as low as ±1% and high thermal stability (variation as low asn±0.54% from -55°C to +125°C), and good high-frequency response.
• Class 2: These have higher volumetric efficiency, widely used for bypass, coupling, and decoupling, based on dielectric composition and application. Class 2 (e.g., X7R, Y5V) types provide higher capacitance per unit volume with broader tolerances and more pronounced variation over temperature and applied voltage.

Main differences between Class 1 and Class 2 ceramic capacitors are their stability, precision, dielectric materials, and typical applications. Dielectric materials fundamentally influence the performance of ceramic capacitors by determining their capacitance, voltage tolerance, temperature stability, dielectric losses, aging behavior, and mechanical properties.

Class 1 Ceramic Capacitors

These capacitors use temperature-compensating dielectrics such as C0G (NP0), P100, N220, etc., which are highly stable and have nearly linear or zero temperature coefficients. They offer very high precision, low losses, and capacitance stability over temperature, voltage, and frequency—often within ±1% or less from -55°C to +125°C. Class 1 capacitors are best suited for resonant circuits, filters, oscillators, precision timing, and RF circuits where minimal drift and low microphony are essential. Capacitance values are generally lower (a few pF to low nF) due to lower permittivity of dielectric materials.

These dielectrics rely on paraelectric materials, mainly titanium dioxide with addition of calcium or strontium titanate. Paraelectricity refers to property of material that polarize under external electric field, and polarization disappears as soon as field is removed.  They do not have spontaneous dipole alignments (unlike ferroelectrics), resulting in zero net polarization in the absence of electric field.

Class 2 Ceramic Capacitors

Class 2 capacitors use high-permittivity dielectrics based on barium titanate (X7R, X5R, Y5V, Z5U), which are more temperature and voltage sensitive. They provide much higher capacitance in the same volume, but with greater variation due to temperature, voltage, and aging (up to ±15% or more, with significant drift and aging). Class 2 dielectrics mainly use ferroelectric compositions, typically barium titanate with additives.

Class 2 capacitors are used mainly for DC blocking, bypass, decoupling, and general-purpose applications where large capacitance per volume and cost effectiveness are prioritized over extreme precision or stability. They show higher losses, non-linear characteristics, and are susceptible to piezoelectric (microphony) effects.

Features of Ceramics as Dielectric Materials