ECIA EIA-198-1-F

EIA-198-1-F of this standard provides means to characterizeceramic capacitors electrically and mechanically by use of typedesignators. In addition, this section outlines dielectricclassifications, marking specifications and test sequences.

Dielectric classification

There are four major classifications of ceramic dielectrics,with class I being the least variable with temperature and voltage,and class IV being the most variable. Class I dielectrics aretypically used in applications requiring the tightesttolerance.

Class I

Components of this type are temperature compensating ceramicdielectrics, fixed capacitors of a type suited for resonant circuitapplications or other applications where high Q and stability ofcapacitance characteristics are required. (See table 1.)

Class II

Components of this classification are fixed, ceramic dielectriccapacitors of a type suited for bypass and decoupling applicationor for frequency discriminating circuits where Q and stability ofcapacitance characteristics are not of major importance. Thisclassification is further defined as those capacitors havingtemperature characteristics A through S (see table 3). Class IIceramic dielectrics exhibit a predictable change with time andvoltage. Compensation for the aging effect is made by referencingcapacitance limits to a future time deemed to be most useful to thebuyer; 1,000 hours is normally chosen, but other arrangements maybe negotiated between the buyer and seller. Voltage will also causea temporary capacitance change, and the test sequence should besuch that capacitance measurements are not affected by previousvoltage tests.

The aging rate of a dielectric is essentially constant over manydecades of time, i.e., 10 h to 100 h, 100 h to 1,000 h, 1,000 h to10,000 h, etc., when measured from the time of the last heat ofdepolarization in manufacture. Restoration of the originalcapacitance at time of manufacture will occur on heating to 150 oCfor one hour, after which normal aging will again commence.Capacitors measured prior to 24 hours may exhibit temporarily highcapacitance values that will age downward.

Class III

Components herein standardized are fixed ceramic dielectriccapacitors of a type specifically suited for use in electroniccircuits for bypass, decoupling or other applications in whichdielectric losses, high insulation resistance and capacitancestability are not of major consideration. This classification isidentical to that of class II, except that it is restricted tothose capacitors having temperature characteristics T through V(table 3).

Class IV

This classification is restricted to those components utilizingreduced titanate or barrier layer type construction,. Whilebasically fitting the descriptions of class II and class III,certain other electrical differences can be noted, as described inEIA-198-3-F of this specification.

Edition:

F

Published:

11/01/2002

Number of Pages:

26

File Size:

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