electromagnetic interference. Filters furnished to the requirements of this specification contain shunting ceramic discoidal capacitors and series inductors \(FSC 5915\). Capacitors furnished to the requirements of this specification contain shunting ceramic discoidal capacitors \(FSC 5910\). For the purposes of this specification, feed-through capacitor types \(C circuit configuration\) are referred to herein as a filter. Passband power may be alternating current \(ac\) or direct current \(dc\) and the filters used primarily in the reduction of broadband radio frequency interference. This specification provides for two levels of product assurance requirements. Filters covered by this specification are capable of operation over the temperature range of -55 degrees C to +125 degrees C.

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MIL-PRF-28861D

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

material shall be used which will enable the filters to meet the performance requirements of this specification.

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

finished product.

3.4.1 Impregnating and potting compounds. Compounds used in the impregnating and potting of filters shall be

chemically inactive with respect to the filter unit and case (see 3.5.2). The compound either in the state of original

application or as a result of having aged, shall have no adverse effect on the performance of the filter. The use of

wax is prohibited.

3.4.2 Outgassing (applicable to nonhermetically sealed class S filters only) (see 6.7). When tested as specified in

4.6.28, the polymeric sample shall meet the following requirements:

Total mass loss (TML) - - - - - - - - - - - - - - - - - Shall not exceed 1.0 percent

Volatile condensable material (VCM) - - - - - - -Shall not exceed 0.1 percent

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

externally. Tin content of filter components, associated mounting hardware, and solder shall not exceed 97 percent,

by mass. Tin shall be alloyed with a minimum of 3 percent lead, by mass (see 6.5.1 and 6.5.5). Lead-free, tin alloy

high temperature solders may be used where high temperature solder is required herein with approval by the

qualifying activity. The tin content of lead-free high temperature solders, shall not exceed 97 percent by mass.

3.5 Interface and physical dimensions. Filters shall meet the interface and physical dimensions specified

(see 3.1).

3.5.1 Performance. Filter performance shall be such that none of the components of the filter are over-stressed

during operation as electrically and mechanically specified herein. Unless allowed for herein, no degradation shall

occur during any 100-percent screens specified herein. The filter shall meet the specified electrical characteristics at

all operating temperatures, voltages, currents, or any combinations thereof as specified herein. Unless otherwise

specified, the insertion loss requirements between any two adjacent specified frequencies shall be that of the lower of

the two frequencies.

3.5.2 Case. Filters shall be enclosed in a suitable case in order to pass the performance requirements of this

specification. The case shall be hermetically sealed or non-hermetically sealed as specified (see 3.1 and 6.4.2). The

case shall protect the filter components from damage under all test conditions specified and prevent leakage of

impregnant or filling compound. All metallic surfaces shall be free from insulating protective finishes except as

specified.

3.5.3 Finish. All exposed metallic surfaces shall be suitably protected against corrosion by plating, solder coating,

or other means. The finish shall:

a. Provide good electrical contact when used as a terminal or conductor.

b. Have uniform texture and appearance.

c. Be adherent.

d. Be free from blisters, pinholes, and other defects that may affect the protective value of the coating.

3.5.3.1 Tin-lead plated. T code case finish filters (see 1.2.1.2 and 3.1) shall be, tin-lead plated (the minimum lead

content shall be 3 percent), or hot-solder dipped. Use of pure tin plating is prohibited. For guidance on tin-lead finish,

3.5.3.2 Silver-plated. S code case finish filters (see 1.2.1.2 and 3.1) shall be silver-plated. For guidance on silver

finishes see 6.5.3.

3.5.3.3 Gold-plated. G code case finish filters (see 1.2.1.2 and 3.1) shall be gold plated. For guidance on gold

finishes see 6.5.4.