The Capacitor
CERAMIC
LAYER
ELECTRODE
TERMINATE
EDGE
basic characteristics into more easily specified classes. The
basic industry specification for ceramic capacitors is EIA
specification RS-198 and as noted in the general section
it specifies temperature compensating capacitors as Class
1 capacitors. These are specified by the military under
specification MIL-C-20. General purpose capacitors with
non-linear temperature coefficients are called Class 2
capacitors by EIA and are specified by the military under
MIL-C-11015 and MIL-C-39014. The new high reliability
military specification, MIL-C-123 covers both Class 1 and
Class 2 dielectrics.
Class 1 –
Class 1 capacitors or temperature compensating
capacitors are usually made from mixtures of titanates
where barium titanate is normally not a major part of the
mix. They have predictable temperature coefficients and
in general, do not have an aging characteristic. Thus they
are the most stable capacitor available. Normally the
T.C.s of Class 1 temperature compensating capacitors are
C0G (NP0) (negative-positive 0 ppm/°C). Class 1 extended
temperature compensating capacitors are also manufac-
tured in T.C.s from P100 through N2200.
Class 2 –
General purpose ceramic capacitors are called
Class 2 capacitors and have become extremely popular
because of the high capacitance values available in very
small size. Class 2 capacitors are “ferro electric” and vary in
capacitance value under the influence of the environmental
and electrical operating conditions. Class 2 capacitors
are affected by temperature, voltage (both AC and DC),
frequency and time. Temperature effects for Class 2
ceramic capacitors are exhibited as non-linear capacitance
changes with temperature.
TERMINATE
EDGE
END
TERMINATIONS
ELECTRODES
MARGIN
Figure 1
Table 1: EIA Temperature Compensating Ceramic Capacitor Codes
TC TOLERANCES
(1)
Capacitance
in pF
NP0
+30
-75
±30
CG
C0G
N030
+30
-80
±30
HG
S1G
N080
N150
N220
N330
N470
+60
-210
±60
TH
T2H
N750
+120
-340
±120
UJ
U2J
N1500
+250
-670
±250
NONE
P3K
N2200
+500
-1100
±500
NONE
R3L
10 and Over
-55°C to +25°C in PPM/°C
+30
+30
+30
+60
-90
-105
-120
-180
+25°C to +85°C in PPM/°C
±30
±30
±30
±60
LG
U1G
PG
P2G
RG
R2G
SH
S2H
10 and Over
Closest
MIL-C-20D
Equivalent
EIA Desig.
(1)
Table 1 indicates the tolerance available on specific temperature characteristics. It may be noted that limits are established on the basis of measurements at
+25°C and +85°C and that T.C. becomes more negative at low temperature. Wider tolerances are required on low capacitance values because of the effects of
stray capacitance.
4
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