MIL-PRF-22710H
3.3.4 Solder. Solder shall not be used for mechanical strength and shall be selected to enable the switch to meet
the performance requirements of this specification.
3.3.5 Potting compounds. Potting compounds, when used, shall be selected to enable the switch to meet
performance requirements of this specification. Additional information and guidance on potting compounds is
provided in 6.9.
3.4 Interface and dimensions. Switches shall be so constructed as to ensure proper operation when mounted in
any position. The switches shall meet the interface and dimensions specified (see 3.1).
3.4.1 Threaded parts. All threaded parts shall be in accordance with FED-STD-H28. Wherever possible, unified
screw threads shall be used.
3.4.1.1 Engagement of threaded parts. All threaded parts shall engage at least three full threads in soft metals like
aluminum and its alloys. A minimum of two full threads shall be used in harder materials such as brass or steel.
When a screw mates with a plastic part, a threaded metal insert shall be molded therein to receive the screw. Drive
screws used directly in plastic parts are acceptable only when retention is assured by subsequent module assembly
secured by metal threaded fasteners.
3.4.1.2 Locking of screw-thread assemblies. Bronze or corrosion-resistant steel flat washers shall be provided
under nuts or screw heads, except where a double-chamfered nut is used in contact with plastic, a flat washer is not
required. Nuts, other than lock nuts, shall have a locking sealant applied to the threads of the screw or stud and the
nut. For additional information on locking sealant see 6.11.
3.4.2 Stops. Stops, when required, shall be permanently fixed and their position specified (see 6.2).
3.4.3.1 Connector terminals. The leading edge of the printed circuit board conductor shall be tapered and shall not
extend to the edge of the printed circuit board. The mating area for this type of wafer design shall be treated to
facilitate connection. Gold plating may be used and shall be over a low stress nickel plate. For additional information
and guidance see 6.10.
3.4.3.2 Solder terminals. Terminals shall accommodate two AWG size 22 stranded wires. Terminals which are
integral with the printed circuit shall be mechanically bonded to the board prior to fusion to the board.
3.4.3.3 Printed circuit board terminals. Terminals shall accommodate two AWG size 22 stranded wires. The walls
of plated-through holes may be copper and overplated with the thickness to be not less than .001 inch (0.0254 mm).
3.4.4 Indexing. Unless otherwise specified (see 6.2.2), switches shall have a positive detent or indexing
mechanism locating each position. The detent or indexing mechanism shall be designed to minimize the possibility of
movable element or elements coming to rest between indexing positions. When indexing is accomplished by means
of a push button or toggle, 100-percent indexing of the movable element or elements and character shall be attained
at, or before, the push button is fully depressed. Glass or other fragile materials shall not be used in detent or
indexing mechanisms.
3.4.5 Switch contacts.
3.4.5.1 Rotor contacts. The rotor contact shall require no adjustments during any of the tests specified herein.
The rotor contact assembly shall be adequately staked or anchored to the rotor insulator to preclude any axial, radial,
or longitudinal movement during the life of the switch. The rotor contact interface with the switch stator may be of a
gold, gold alloy, platinum alloy material or gold plated. For additional information and guidance see 6.10.
3.4.5.2 Stator contacts. The conductive pattern of the wafer stator shall be fabricated with a printed wiring pattern
(circuit configuration). The minimum conductor or pad width shall be .025 inch (0.6350 mm), unless otherwise
specified (see 3.1 and 6.2). The contact portion of the printed conductor, which makes contact with the rotor blade,
may be rhodium-plated or gold-plated. The portion of the conductor where the terminals are staked to the printed
circuit board shall not be rhodium-plated. When the terminal portion of the printed circuit board is used as the male
connector, the leading edge of the connector shall be tapered and shall not extend to the edge of the printed circuit
board. For additional information and guidance on plating see 6.10.
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