The Capacitor
Table 2: MIL and EIA Temperature Stable and General Application Codes
MIL CODE
Symbol
A
B
C
Symbol
Temperature Range
-55°C to +85°C
-55°C to +125°C
-55°C to +150°C
Cap. Change
Zero Volts
+15%, -15%
+22%, -56%
+15%, -15%
+30%, -70%
+20%, -20%
Cap. Change
Rated Volts
+15%, -40%
+22%, -66%
+15%, -25%
+30%, -80%
+20%, -30%
EIA CODE
Percent Capacity Change Over Temperature Range
RS198
X7
X5
Y5
Z5
Code
D
E
F
P
R
S
T
U
V
Temperature Range
-55°C to +125°C
-55°C to +85°C
-30°C to +85°C
+10°C to +85°C
Percent Capacity Change
±3.3%
±4.7%
±7.5%
±10%
±15%
±22%
+22%, -33%
+22%, - 56%
+22%, -82%
R
W
X
Y
Z
Temperature characteristic is specified by combining range and change
symbols, for example BR or AW. Specification slash sheets indicate the
characteristic applicable to a given style of capacitor.
EXAMPLE – A capacitor is desired with the capacitance value at 25°C
to increase no more than 7.5% or decrease no more than 7.5% from
-30°C to +85°C. EIA Code will be Y5F.
In specifying capacitance change with temperature for
Class 2 materials, EIA expresses the capacitance change
over an operating temperature range by a 3 symbol code.
The first symbol represents the cold temperature end of the
temperature range, the second represents the upper limit
of the operating temperature range and the third symbol
represents the capacitance change allowed over the
operating temperature range. Table 2 provides a detailed
explanation of the EIA system.
Effects of Voltage –
Variations in voltage affects only the
capacitance and dissipation factor. The application of DC
voltage reduces both the capacitance and dissipation
factor while the application of an AC voltage within a
Cap. Change vs. A.C. Volts
AVX X7R T.C.
Capacitance Change Percent
reasonable range tends to increase both capacitance and
dissipation factor readings. If a high enough AC voltage is
applied, eventually it will reduce capacitance just as a DC
voltage will. Figure 2 shows the effects of AC voltage.
Capacitor specifications specify the AC voltage at which to
measure (normally 0.5 or 1 VAC) and application of the
wrong voltage can cause spurious readings. Figure 3 gives
the voltage coefficient of dissipation factor for various AC
voltages at 1 kilohertz. Applications of different frequencies
will affect the percentage changes versus voltages.
D.F. vs. A.C. Measurement Volts
AVX X7R T.C.
10.0
Dissipation Factor Percent
Curve 1 - 100 VDC Rated Capacitor
8.0 Curve 2 - 50 VDC Rated Capacitor
Curve 3 - 25 VDC Rated Capacitor
6.0
4.0
2.0
0
.5
1.0
1.5
2.0
2.5
AC Measurement Volts at 1.0 KHz
Curve 1
Curve 3
Curve 2
50
40
30
20
10
0
12.5
25
37.5
Volts AC at 1.0 KHz
50
Figure 2
5
Figure 3
AVX [ AVX CORPORATION ]
