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.

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MIL-PRF-20M

3.25 Recycling and waste prevention. Recovered materials or environmentally preferable materials shall be used

wherever possible without jeopardizing the intended use of this item.

3.26 Workmanship. Capacitors shall be processed in such a manner as to be uniform in quality when using 2x

minimum to 4x maximum magnification. Capacitors shall not exhibit pits, corrosion, cracks, chips, or other defects

that will affect life, serviceability, or appearance.

4. VERIFICATION

4.1 Classification of inspections. The examination and testing of capacitors shall be classified as follows:

a. Qualification inspection (see 4.4)

b. Verification of qualification (see 4.5)

c. Conformance inspection (see 4.6)

4.2 QPL system. The manufacturer shall establish and maintain a QPL system in accordance with 3.3. Evidence

of such compliance is a prerequisite for qualification and retention of qualification.

4.3 Inspection conditions and methods.

4.3.1 Inspection conditions. Unless otherwise specified herein, all inspections shall be performed in accordance

with the "GENERAL REQUIREMENTS" of MIL-STD-202 except relative humidity shall not exceed 75 percent.

Accuracy of all test voltage measurements shall be within �2.0 percent of the specified voltage.

4.3.2 Methods.

4.3.2.1 Reference measurements. When requirements are based on comparative measurements made before

and after conditioning, the reference measurement shall be considered the last measurement made at +25�C �3�C

prior to conditioning. Unless reference measurements have been made within 30 days prior to the beginning of

conditioning, they shall be repeated.

4.3.3 Power supply. The power supply used for life testing shall have a regulation of �2 percent or less of the

specified test voltage.

4.4 Qualification inspection. Qualification inspection shall be performed at a laboratory acceptable to the

Government (see 6.3), on sample units produced with equipment and procedures normally used in production.

4.4.1 Sample size. The number of capacitors to be subjected to qualification inspection shall be as specified in

table IV and appendix A of this specification. Each capacitor style shall be qualified separately.

4.4.2 Inspection routine. Sample units shall be subjected to the qualification inspection specified in table IV, in the

order shown. All sample units shall be subjected to the inspection of group I and group II. The sample shall then be

divided as specified in table IV for group III through group VI inclusive and subjected to the tests for their particular

group. Samples that have been selected to be submitted to the life test shall be divided into two groups. One group

shall be subjected to the accelerated condition and the other group to the rated condition. The decision as to whether

or not the product is to be included on the QPL shall be made at the conclusion of the 1,000-hour life test. Each unit

subjected to the accelerated condition shall be continued on for a total of 4,000 hours. Each unit subjected to the

rated condition shall be continued on for a total of 32,000 hours.

4.4.3 Failures. Failures in excess of those allowed in table IV shall be cause for refusal to grant qualification

approval.