MIL-PRF-22097J
3.25 Solderability (applicable to terminal types P, W, X, and Y only). When resistors are tested as specified in
4.7.20, the dipped surface of the terminals shall be at least 95 percent covered with a new, smooth, continuous
surface free from pin holes. The remaining 5 percent of the terminal surface shall show only pin holes, voids, or
rough spots. These shall not be concentrated in one area. Bare base metal and areas where the solder dip has
failed to cover the original coating are indications of poor solderability, and shall be cause for failure. In case of
dispute, the percentage of coverage with pinholes or rough spots shall be determined by actual measurement of
these areas, as compared to the total area.
3.26 Immersion (applicable to terminal types P, S, W, X, and Y only). When resistors are tested as specified in
4.7.21, no continuous stream of bubbles shall be emitted.
3.27 Fungus. All external materials shall be nonnutrient to fungus or shall be treated to retard fungus growth. The
manufacturer shall verify by certification that all external materials are fungus resistant or shall test resistors as
specified in 4.7.22. There shall be no evidence of fungus growth on the external surfaces.
3.28 Marking. Resistors shall be marked with the PIN and the manufacturer's name or code symbol. The circuit
diagram shall be marked on the resistor as specified in 3.4.3.1. The location of the manufacturers code symbol shall
be at the discretion of the manufacturer. Marking shall remain legible at the end of all tests. There shall be space
between the symbols which comprise the PIN. If lack of space requires it, the PIN may be placed on two lines or on
separate surfaces. In the event, the PIN shall be divided between the characteristic and terminal symbols, as shown
in the following example:
RJ24F
P103
3.29 Supplying to tighter resistance temperature characteristics. Parts qualified and marked to lower resistance
temperature characteristics, with procuring activity approval, are substitutable for higher resistance temperature
characteristics and shall not be remarked unless specified in the contract or purchase order (see 6.2) (see table IV).
TABLE IV. Characteristics.
Characteristic
Characteristic
substitute
O
Symbol
ppm/ C
1/
A
±100
F
±250
C
F
1/ See table III.
3.30 Riveting. When riveting is required, the operation shall be carefully performed to insure that the rivets are
tight and satisfactorily headed.
3.31 Solder, flux, and soldering. Materials and processes for soft soldering shall be as specified in 3.31.1 and
3.31.2.
3.31.1 Soft solder. Soft solder, when used for electrical connections, shall conform to composition type A of
3.31.2 Flux and cleaning agents. Flux for soldering electrical connections shall be resin or resin and alcohol. No
acid or acid salts shall be permitted for pretinning of electrical connections and for tinning of electrical circuits, but in
no case shall acid or acid salts be use where they come into contact with insulation material. Where acid or acid
salts are used, as permitted herein, they shall be completely neutralized and removed immediately after use.
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