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MIL-PRF-19978 Capacitors, Fixed, Plastic \(Or Paper-Plastic\) Dielectric \(Hermetically Sealed In Metal, Ceramic Or Glass Cases\), Established And Non-Established Reliability General Specification ForThis specification covers the general requirements for established reliability \(ER\) and non-established reliability \(non-ER\), direct current \(dc\), plastic or paper-plastic dielectric, fixed capacitors, hermetically sealed in metal or ceramic or glass cases. Capacitors meeting the established reliability requirements specified herein have failure rate \(FR\) levels ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.9\). These FRLs are established at a 90-percent confidence level and maintained at a 10-percent producer\'s risk and are based on life tests performed at maximum rated voltage and maximum rated temperature. An acceleration factor of 5:1 has been used to relate the life test data obtained at 140 percent of rated dc voltage at the applicable high test temperature to the rated voltage at the applicable high test temperature. This specification also covers removable mounting retainers for use with applicable capacitors \(see 3.1\). A parts per million \(ppm\) quality system is used for documenting and reporting the average outgoing quality of ER capacitors supplied to this specification. Statistical process control \(SPC\) techniques are required in the manufacturing process to minimize variation in production of ER capacitors supplied to the requirements of this specification.

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MIL-PRF-19978K
1.2.1.1 Style The style is identified by either the three-letter symbol "CQR" or the two-letter symbol "CQ" followed
by a two-digit number. The letters identify plastic (or paper-plastic) dielectric, fixed capacitor, hermetically sealed in
metal, ceramic or glass cases. The symbol "CQR" identifies established reliability (ER) capacitors; the symbol "CQ"
identifies capacitors for which no specific reliability requirements are specified (non-ER). The first digit following the
letter symbols identifies the general shape of the case, and the second digit identifies specific details other than case
size. Each style designation may include a family of case sizes.
1.2.1.2 Terminal. The terminal is identified by a single letter in accordance with table I.
TABLE I. Terminal.
Symbol
Type of terminal
A
Axial wire lead
B
Solder lug (nonremovable)
C
Threaded stud and nuts
D and H
Pillar insulator for use at altitudes up to 7,500 feet (22.8 inches of mercury)
E
Pillar insulator for use at altitudes up to 50,000 feet (3.4 inches of mercury)
1.2.1.3 Circuit. The circuit diagram and the number of terminals are identified by a single digit in accordance with
table II.
TABLE II. Circuit diagram and number of terminals.
Symbol
Circuit diagram
Number of terminals
1
2
3
2
1.2.1.4 Characteristic. The characteristic is identified by a single letter in accordance with table III.
TABLE III. Characteristic.
Values of characteristics
Characteristic
E
F and G
K 2/
M
P
Q
T
V
High ambient test temperature, degrees Celsius
+85
+85
+125
+85  +65  +125 +170 +125
3C 1/
Low ambient test temperature, degrees Celsius
-65
-55
-65
-65
-65
-55
-65
-55
+0C, -5C
Life-test dc voltage, percent of the dc voltage
rating (see 4.7.20):
Watt-second group (see 6.5.3):
I (0.5 watt-second and less)
140
140
140
140
140
150
140
150
II (0.5+ to 5 watt-seconds)
140
130
140 3/
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III (5+ to 50 watt-seconds)
140
110
140
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IV (greater than 50 watt-seconds)
140
90
140
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Flashpoint of impregnant of filling compound,
+142
+135
+142
+142 +142 +142 +217 +142
degrees Celsius
1/ For characteristic K, voltage derating may be necessary at the high ambient test temperature (see 3.1).
2/ For tubular units of characteristic K rated at 1,000 volts dc, life test voltage is 1,200 volts.
3/ For tubular units of characteristic K in watt-seconds group II, use 130 percent of the dc voltage at +40C for the
life-test dc voltage.
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