CERAMIC CAPACITORS

8

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Page revised 02/21

Taping : dimensions

MLCC STRUCTURE

Terminations

Ceramic

Tin

Tin / Lead

Gold

(Solderable layer)

Electrodes

Margins

Silver or Silver / Palladium (electrodes contact layer)

Polymer (crack protection layer)

Nickel or Copper barrier (leaching protection layer)

EQUIVALENT CIRCUIT

Capacitor is a complex component combining resistive, inductive and capaci-

tive phenomena. A simplified schematic for the equivalent circuit is:

Ls

Rs

C

IR

DIELECTRIC CHARACTERISTICS

Insulation Resistance (IR) is the resistance measured under DC voltage

across the terminals of the capacitor and consists principally of the parallel

resistance shown in the equivalent circuit. As capacitance values and hence

the area of dielectric increases, the IR decreases and hence the product (C x

IR) is often specified in Ω.F or MΩ.

µF.

The Equivalent Series Resistance (ESR) is the sum of the resistive terms

which generate heating when capacitor is used under AC voltage at a given

frequency (f).

Dissipation factor (DF) is the ration of the apparent power input will turn to

heat in the capacitor:

DF = 2π f C ESR

When a capacitor works under AC voltage, heat power loss (P), expressed in

Watt, is equal to:

P = 2π f C Vrms2 DF

The series inductance (Ls) is due to the currents running through the elec-

trodes. It can distort the operation of the capacitor at high frequency where the

impedance (Z) is given as:

Z = Rs + j (Ls.q - 1⁄(C.q)) with q = 2πf

When frequency rises, the capacitive component of capacitors is gradually

canceled up to the resonance frequency, where :

Z = Rs and LsC.q2 = 1

Above this frequency the capacitor behaves like an inductor.

P100

NPO

N2200 (C4xx)

BX

2C1

X7R

Dielectric material

Porcelain

Magnesium titanate or Neodynium

baryum titanate

Barium zirconate

titanate

Baryum titanate (BaTiO3)

Dielectric constant

15 – 18

20 – 85

450

2,000 – 5,000

Electrode technology

PME (Precious Metal Electrodes): Ag/Pd

Capacitance variation between –55°C

and +125/°C without DC voltage

(100±30)ppm/°C

(0±30)ppm/°C

(–2,200±500)

ppm/°C

±15%

±20%

±15%

Capacitance variation between –55°C

and +125/°C with DC rated voltage

0 -15%

15% –25%

20% –30%

Not

applicable

Piezo-electric effect

None

None

Yes

Dielectric absorption

None

Few %

Few %

Thermal shock sensitive

+

+

++

Ceramic Capacitors Technology