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|  MIL-R-5757H
3.3.1.1 Plated finishes.
a. Use of tin plating is prohibited internally and externally (see 6.6.1). Use of tin-lead finishes are
acceptable provided that the minimum lead content is 3 percent.
b. Use of zinc plating is prohibited internally and externally.
c.
Use of cadmium plating is prohibited internally and externally.
3.3.1.2 Dissimilar metals. When dissimilar metals are used in intimate contact with each other,
protection against electrolysis and corrosion shall be provided. The use of dissimilar metals in contact,
which tends toward active electrolytic corrosion (particularly brass, copper, or steel used in contact with
aluminum or aluminum alloy), is not acceptable. However, metal spraying or metal plating of dissimilar
base metals to provide similar or suitable abutting surfaces is permitted. Dissimilar metals should be as
defined in 6.6. In hermetic seals, the 0.25 V difference between the header material and the housing
material is not applicable.
3.3.2 Magnet wire. Magnet wire used shall enable the relay to meet the performance requirements of
this specification.
3.3.3 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or
environmentally preferable materials should be used to the maximum extent possible provided that the
material meets or exceeds the operational and maintenance requirements, and promotes economically
advantageous life cycle costs.
3.4 Interface and construction requirements. Relays shall meet the interface and construction
requirements as specified (e.g. weight, physical dimensions) (see 3.1).
3.4.1 Case. Unless otherwise specified (see 3.1), the case shall not be electrically connected to the
contacts or coil; however, it may be used as part of the magnetic circuit.
3.4.1.1 Case grounding. When specified (see 3.1), a means for connecting the relay case to ground
shall be provided.
3.4.2 Sealing process. Relays shall be dried, degassed, backfilled with an atmosphere, and sealed in
such a manner that all the requirements of this specification are met. Adjunct sealant (see 6.8), if used,
must comply with the following characteristics:
a. Shall not extend above 20 percent of the length of the exposed terminals above the glass
meniscus.
b. Trace color is permitted if it is a natural result of the sealant process.
c. Shall form, after curing, a permanent nonconductive, noncracking seal under all relay
environments.
3.4.3 Contacts. Contacts shall have load ratings and arrangements as specified (see MIL-STD-1285
and 3.1) and unless otherwise specified (see 3.1), shall be capable of carrying the maximum rated
current continuously as well as making and breaking the specified current under all environmental
conditions specified herein.
3.4.3.1 Orientation of contact motion (dry reed relays only). The flat surface of the reed contact shall
be parallel to two sides at right angles to the relay housing unless otherwise specified (see 3.1).
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