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

3.11 Barometric pressure (reduced) (when applicable. see 3.1), qualification only. When capacitors are tested as

specified in 4.7.7, there shall be no momentary or intermittent arcing or other indication of breakdown, nor shall there

be any visible evidence of damage.

3.12 Insulation resistance (IR).

3.12.1 Sleeving (when applicable. see 3.1). When measured as specified in 4.7.8, the insulation resistance shall

be not less than 1,000 megohms.

3.12.2 Terminal to terminal. When measured as specified in 4.7.8, the insulation resistance shall be not less than

the applicable values specified (see 3.1).

3.12.3 Terminal to case. Unless otherwise specified (see 3.1), when measured as specified in 4.7.8, the

insulation resistance between any terminal and case, when the case is not a terminal, shall exceed 50,000

megohms.

3.13 Capacitance. When measured as specified in 4.7.9, the capacitance shall be within the tolerance specified

3.14 Dissipation factor. When measured as specified in 4.7.10, the dissipation factor shall not exceed the

applicable value specified (see 3.1).

3.15 Vibration. When capacitors are tested as specified in 4.7.11, there shall be no intermittent contacts of 0.5

milliseconds (ms) or greater duration or momentary arcing, or other indication of breakdown, nor shall there be any

open-or-short circuiting or evidence of mechanical damage. In addition, retainers, as tested to 4.7.11, shall exhibit

no evidence of mechanical damage.

3.16 Salt spray (corrosion) (metal surfaces only, see 3.1). When capacitors or retainers are tested as specified in

4.7.12, there shall be no evidence of harmful corrosion and at least 90 percent of any exposed metal surfaces of the

capacitor or retainer shall be protected by the finish. Harmful corrosion shall be construed as any type of corrosion

which in any way interferes with the mechanical or electrical performance of the capacitor or retainer, as applicable.

For capacitors or retainers with painted surfaces, not more than 10 percent of the surfaces shall be affected by

flaking, peeling, or blistering of paint. There shall be no evidence of unwrapping of or mechanical damage to the

insulating sleeves when applicable. In addition, corrosion of the terminal hardware or mounting surface shall not

exceed 10 percent of the surface area. Marking shall remain legible.

3.17 Immersion. When tested as specified in 4.7.13, capacitors or retainers, as applicable, shall meet the

following requirements:

a. Capacitors:

Dielectric withstanding voltage:

Insulating sleeves (when applicable, see 3.1): Not less than 4,000 V dc.

As specified in 3.10.1.

Terminal to terminal:

Terminal to case:

As specified in 3.10.1.

Insulation resistance at +25C:

Insulating sleeves (when applicable, see 3.1): Not less than 1,000 megohms.

Terminal to terminal:

Unless otherwise specified, not less than 60 percent of

the value specified in 3.12.2.

Terminal to case:

Unless otherwise specified, not less than 50 percent of

the value specified in 3.12.3.