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.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14

MIL-PRF-19978K

FIGURE 2. Intended operating temperature.

6.5.5 Barometric pressure (reduced) (see 4.7.7).

6.5.5.1 Ceramic-cased or glass-cased tubular capacitors. The dc voltage that may be applied to ceramic-cased

or glass-cased tubular capacitors at altitudes from 50,000 to 100,000 feet may be obtained from figure 3.

6.5.5.2 Metal-cased tubular capacitors. The dc voltage that may be applied to metal-cased tubular capacitors at

altitudes other than 80,000 feet may be obtained from figure 4, except that the dc voltage rating must not be

exceeded.

6.5.6 Representation of minimum insulation resistance. A graphical representation of minimum insulation

resistance, as specified in the applicable specification sheet, is shown in figure 5.

6.5.7 Life at temperatures and voltages below and above rated. The failure rates used in this specification are

referred to operation at rated voltage at the maximum rated temperature. The sampling plans and failure-rate

determinations throughout the specification assume an acceleration factor of 5 for the life test conducted at the

maximum rated temperature and 140 percent of rated voltage. Lower failure rates than those for which the

manufacturer has obtained qualification may be achieved by operating the capacitors at lower voltage, or at lower

temperatures, or both. Factors by which failure rates are to be multiplied under conditions other than maximum

conditions are shown on figure 6 (characteristic K only).