MIL-C-11272E
4.6.15 Temperature coefficient and capacitance drift (see 3.18).
4.6.15.1 Qualification inspection. Capacitance measurements shall be made at the following temperatures, in the
order listed:
Temperatures (°C)
25 ±2
-55 +0, -2
-10 ±2
25 ±2
65 ±2
85 +2, -0
125 +2, -0
25 ±2
The measurement at each temperature shall be recorded when two successive readings taken at 5-minute intervals
at that temperature indicate no change in capacitance. The temperature at the time of measurement shall be
measured to an accuracy of ±1 percent of the temperature difference between the nominal test temperature and the
nominal reference temperature +0.5°C. Measurements shall be made at a frequency of 100 kHz ±10 kHz. The
reference frequency at which measurements are made shall not drift more than ±50 Hz during the test. An accuracy
of ±0.025 percent of nominal capacitance +0.05 pF shall be maintained for measurement of capacitance change.
4.6.15.1.1 Continuous curve temperature coefficient. As an alternate to the measurements specified in 4.6.15.1,
a continuous curve of capacitance versus temperature may be produced by subjecting the capacitors to a slowly
varying temperature. The temperature shall be varied from 25° to -55° to +125° to 25°C. A temperature-sensing
device shall be embedded in a dummy capacitor in a manner to assure accurate internal readings in the sample
under test. Temperature shall be varied slowly enough to produce a smooth uniform curve with no loops at -55° or
125°C. Measurements shall be made at a frequency of 100 kHz ±10 kHz. Accuracy shall be as specified in
4.6.15.1.
4.6.15.1.2 Temperature coefficient. The temperature coefficient shall be computed as follows:
(C 2 - C 1)10 6
TC =
(T 2 - T 1)C 1
Where:
TC = temperature coefficient in parts per million per degree centigrade.
C1 = capacitance at the middle 25°C (reference) temperature in pF.
C2 = capacitance at test temperature in pF.
T1 = 25°C.
T2 = test temperature in degrees centigrade.
4.6.15.1.3 Capacitance drift. Capacitance drift shall be computed by dividing the greatest single difference
between any two of the three values recorded at 25°C by the intermediate value recorded at 25°C.
4.6.15.2 Conformance inspection.
4.6.15.2.1 Temperature coefficient. Capacitance measurements shall be made as specified in 4.6.15.1 or
4.6.15.1.1, except that measurements need be made only at 25°C, -55°C, 25°C, 125°C, and 25°C, respectively. The
temperature coefficient shall be computed as specified in 4.6.15.1.2.
4.6.15.2.2 Capacitance drift. Capacitance drift shall be computed as specified in 4.6.15.1.3.
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