ELECTRICAL CHARACTERISTICS The fundamental electrical properties of multilayer ceramic capacitors are as follows: Polarity: Multilayer ceramic capacitors are not polar, and may be used with DC voltage applied in either direction. Rated Voltage: This term refers to the maximum continuous DC working voltage permissible across the entire operating temperature range. Multilayer ceramic capacitors are not extremely sensitive to voltage, and brief applications of voltage above rated will not result in immediate failure. However, reliability will be reduced by exposure to sustained voltages above rated. Capacitance: The standard unit of capacitance is the farad. For practical capacitors, it is usually expressed in microfarads (10-6 farad), nanofarads (10-9 farad), or picofarads (10-12 farad). Standard measurement conditions are as follows: Class I (up to 1,000 pF): Class I (over 1,000 pF): Class II: Class III: 1MHz and 1.2 VRMS maximum. 1kHz and 1.2 VRMS maximum. 1 kHz and 1.0 kHz and 0.5 0.2 VRMS. 0.1 VRMS.

The variation of a capacitor's impedance with frequency determines its effectiveness in many applications. Dissipation Factor: Dissipation Factor (DF) is a measure of the losses in a capacitor under AC application. It is the ratio of the equivalent series resistance to the capacitive reactance, and is usually expressed in percent. It is usually measured simultaneously with capacitance, and under the same conditions. The vector diagram in Figure 2 illustrates the relationship between DF, ESR, and impedance. The reciprocal of the dissipation factor is called the "Q", or quality factor. For convenience, the "Q" factor is often used for very low values of dissipation factor. DF is sometimes called the "loss tangent" or "tangent as derived from this diagram.

Like all other practical capacitors, multilayer ceramic capacitors also have resistance and inductance. A simplified schematic for the equivalent circuit is shown in Figure 1. Other significant electrical characteristics resulting from these additional properties are as follows:

Insulation Resistance: Insulation Resistance (IR) is the DC resistance measured across the terminals of a capacitor, represented by the parallel resistance (Rp) shown in Figure 1. For a given dielectric type, electrode area increases with capacitance, resulting in a decrease in the insulation resistance. Consequently, insulation resistance is usually specified as the "RC" (IR x C) product, in terms of ohm-farads or megohm-microfarads. The insulation resistance for a specific capacitance value is determined by dividing this product by the capacitance. However, as the nominal capacitance values become small, the insulation resistance calculated from the RC product reaches values which are impractical. Consequently, IR specifications usually include both a minimum RC product and a maximum limit on the IR calculated from that value. For example, a typical IR specification might read "1,000 megohm-microfarads or 100 gigohms, whichever is less." Insulation Resistance is the measure of a capacitor to resist the flow of DC leakage current. It is sometimes referred to as "leakage resistance." The DC leakage current may be calculated by dividing the applied voltage by the insulation resistance (Ohm's Law). Dielectric Withstanding Voltage: Dielectric withstanding voltage (DWV) is the peak voltage which a capacitor is designed to withstand for short periods of time without damage. All KEMET multilayer ceramic capacitors will withstand a test voltage 2.5 x the rated voltage for 60 seconds. KEMET specification limits for these characteristics at standard measurement conditions are shown on page 2. Variations in these properties caused by changing conditions of temperature, voltage, frequency, and time are covered in the following sections.

Impedance: Since the parallel resistance (Rp) is normally very high, the total impedance of the capacitor is: