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Temperature coefficient and capacitance drift |
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|  MIL-C-11272D
w/Amendment 1
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 +0.5C. 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 25C. 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
125C. 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 25C (reference) temperature in pF.
C2 = capacitance at test temperature in pF.
T1 = 25C.
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 25C by the intermediate value recorded at 25C.
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 25C, -55C, 25C, 125C, and 25C, 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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