MIL-PRF-20 Capacitor, Fixed, Ceramic Dielectric \(Temperature Compensating\), Established Reliability And Non-Established Reliability, General Specification ForThis specification covers the general requirements for established reliability \(ER\) and non-ER, temperature compensating, fixed capacitors for use primarily where compensation is necessary for circuit applications due to temperature changes, in bypass and coupling applications. Capacitors meeting the ER requirements specified herein have a failure rate level \(FRL\) ranging from 1.0 percent per 1,000 hours to 0.00l percent per 1,000 hours. These failure rate levels are established at a 90-percent confidence level based on the life test parameters specified and are maintained at a 10-percent producer\'s risk. An acceleration factor of 8:1 has been used to relate the life test data at 200 percent of rated voltage at the applicable high test temperature to the rated voltage at the applicable high test temperature. A part 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-20M

4.7.16 Marking legibility (laser marking only) (see 3.24.3). Capacitors shall be coated with .005 inch (0.13 mm)

minimum of silicone resin insulating compound. After curing, coated capacitors shall be examined for legibility under

normal production room lighting by an inspector with normal or corrected 20/20 vision.

4.7.17 Resistance to solvents (ink marking only) (see 3.20). Capacitors shall be tested in accordance with method

215 of MIL-STD-202. Brushing may be applied to the marked portion of the capacitor body only.

4.7.18 Radiographic inspection (for qualification and FRL "S" only) (see 3.21). Capacitors shall be tested in

accordance with method 209 of MIL-STD-202. The following details and exception shall apply:

a. Radiographic quality: The radiograph shall render a clear, sharp image of the penetrameter.

b. Image-quality indicator: A radiograph of the penetrameter shall be included on each radiograph film. The

penetrameter may be made from a sample capacitor, of the same style as the capacitor being radiographed,

with an AWG number 48 copper wire mounted across the capacitor body or it may be fabricated in

accordance with, or be equivalent to, the example on figure 5.

c. Positions of specimen: Unless otherwise specified (see 6.2), one view shall be taken of each capacitor

perpendicular to the plane of the lead surface (see figure 6).

d. Evaluation of images:

(1) Special kind of viewing equipment: Magnifying glass.

(2) Magnification: 10X.

(3) Defects to be sought in specimen: As specified in 3.21.

e. Additional required examination:

(1) There shall be a minimum of 80 percent solder fillet between capacitor element and each lead.

(2) There shall be a minimum of .005 inch (0.13 mm) encapsulating material encasing the capacitor element

(3) There shall be a minimum of .005 inch (0.13 mm) between edge of case and tip of solder spike.

(4) Extraneous particles or voids in encapsulating material shall not be greater than .005 inch (0.13 mm) in

any dimension.

f. Non-film techniques and real time x-ray: The use of non-film techniques such as real time x-ray is permissible

if the equipment is capable of producing results of equal or better quality as the film technique and all

requirements of this specification are complied with, except those pertaining to the actual film. Radiographic

image-quality indicators, as specified in 4.7.18b, may be used at the beginning and end of each inspection lot

if equipment settings are not modified.

NOTE: Test results (covering the number of capacitors tested with number and kinds of failure noted) and radiograph

shall be retained for a minimum period of 2 years. Upon request of the acquiring activity, this data shall be supplied

with each shipment.

4.7.19 Fungus (see 3.22). Capacitors shall be tested in accordance with method 508 of MIL-STD-810.

4.7.20 Life (at elevated ambient temperature) (see 3.23).

4.7.20.1 For qualification inspection. Capacitors shall be tested in accordance with method 108 of MIL-STD-202.

The following details and exceptions shall apply:

a. Distance of temperature measurements from specimens, in inches: Not applicable.