EIA 198-1-F-2002

$27.30

Ceramic Dielectric Capacitors Classes I, II, III and IV – Part I: Characteristics and Requirements

Published By	Publication Date	Number of Pages
ECIA	2002	26

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Description

EIA-198-1-F of this standard provides means to characterize
ceramic capacitors electrically and mechanically by use of type
designators. In addition, this section outlines dielectric
classifications, 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 are
typically used in applications requiring the tightest
tolerance.

Class I

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

Class II

Components of this classification are fixed, ceramic dielectric
capacitors of a type suited for bypass and decoupling application
or for frequency discriminating circuits where Q and stability of
capacitance characteristics are not of major importance. This
classification is further defined as those capacitors having
temperature characteristics A through S (see table 3). Class II
ceramic dielectrics exhibit a predictable change with time and
voltage. Compensation for the aging effect is made by referencing
capacitance limits to a future time deemed to be most useful to the
buyer; 1,000 hours is normally chosen, but other arrangements may
be negotiated between the buyer and seller. Voltage will also cause
a temporary capacitance change, and the test sequence should be
such that capacitance measurements are not affected by previous
voltage tests.

The aging rate of a dielectric is essentially constant over many
decades of time, i.e., 10 h to 100 h, 100 h to 1,000 h, 1,000 h to
10,000 h, etc., when measured from the time of the last heat of
depolarization in manufacture. Restoration of the original
capacitance at time of manufacture will occur on heating to 150 oC
for one hour, after which normal aging will again commence.
Capacitors measured prior to 24 hours may exhibit temporarily high
capacitance values that will age downward.

Class III

Components herein standardized are fixed ceramic dielectric
capacitors of a type specifically suited for use in electronic
circuits for bypass, decoupling or other applications in which
dielectric losses, high insulation resistance and capacitance
stability are not of major consideration. This classification is
identical to that of class II, except that it is restricted to
those capacitors having temperature characteristics T through V
(table 3).

Class IV

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

Additional information