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

3.4 Material. The material shall be as specified herein. However, when a definite material is not specified, a

material shall be used that will enable the capacitors to meet the performance requirements of this specification.

Acceptance or approval of any constituent material shall not be construed as a guarantee of the acceptance of the

finished product.

3.4.1 Insulating and impregnating compounds. Insulating and impregnating compounds, including resins,

varnishes, waxes, and the like, shall be suitable for each particular application. Compounds shall preserve the

electrical characteristics of the insulation to which they are used.

3.5 Interface and physical dimensions. Capacitors shall meet the interface requirements and physical dimensions

specified (see 3.1).

3.5.1 Case. Each capacitor shall be effectively sealed against the entry of moisture. When a molded case is

specified (see 3.1), the capacitor element shall be enclosed via transfer molding or the use of a pre-formed case.

When a conformal (dipped) case is specified (see 3.1), the capacitor element shall be enclosed within insulating

resin, plastic, or ceramic.

3.5.2 Connections. Electrical connections shall not depend on wires, lugs, terminals, and the like, that are

clamped between a metallic member and an insulating material other than the ceramic material. Such connections

shall be soldered or shall be clamped between metallic members.

3.5.2.1 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally.

Tin content of capacitor components and solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a

minimum of 3 percent lead, by mass (see 6.8).

Use of lead-free high temperature solder for internal connections requires approval by the qualifying activity. The tin

content of lead-free high temperature solders shall not exceed 97 percent by mass.

3.5.2.2 Solder dip (retinning). The manufacturer may solder dip/retin the leads of product supplied to this

specification, provided that the solder dip process has been approved by the qualifying activity using the

requirements of appendix A of this specification.

3.6 Thermal shock and voltage conditioning (ER parts only). When tested as specified in 4.7.2, capacitors shall

withstand the extremes of high and low temperature without visible damage and meet the following requirements:

a. Dielectric withstanding voltage (DWV) (at +25�C): Shall be as specified in 3.9. Not applicable if optional

voltage conditioning was performed at or above 300 percent of rated voltage.

b. Insulation resistance (at +25�C): Shall not be less than the value shown on figure 2. NOTE: This step may

be skipped if +125�C IR is performed with +25�C limits.

c. Insulation resistance (at +125�C): Shall not be less than the value shown on figure 2.

d. Capacitance (at +25�C): Shall be within the tolerance specified (see 3.1).

e. Dissipation factor (at +25�C): Shall not exceed the initial requirement (see 3.8).