MIL-DTL-28827C
3.3 Material. Material shall be as specified herein. However, when a definite material is not specified,
a material shall be used which will enable the switches to meet the performance requirements of this
specification. Acceptance or approval of any constituent material shall not be construed as guaranty of
the acceptance of the finished product.
3.3.1 Fungus resistance. All material shall be inert or fungus resistant in accordance with ASTM-G21.
3.3.2 Metals. All metals parts, other than current-carrying parts, shall be of corrosion-resistant
material, or shall be suitably protected to resist corrosion. Paint is not acceptable for corrosion protection.
3.3.2.1 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 which, in
contact, tent toward active electrolytic corrosion (particularly brass, copper, or steel used in contact with
aluminum or aluminum alloy) is not acceptable. However, metal plating or metal spraying of dissimilar
base metals to provide similar or suitable butting surfaces is permitted. The use of dissimilar metals
separated by a suitable insulating material is also permitted
3.3.2.2 Magnesium. Magnesium and magnesium alloys shall not be used.
3.3.2.3 Aluminum. Aluminum and aluminum alloys shall be suitably protected against corrosion.
When anodized, it shall be in accordance with MIL-A-8625. Internal parts not in contact with the media or
subject to wear may be chemically treated in accordance with MIL-DTL-5541.
3.3.2.4 Solder. Solder shall have a minimum melting point of 100°F above the maximum temperature
rating of the temperature switch and shall conform to J-STD-006. Where solder is employed, flux shall be
in accordance with J-STD-004. When stainless steel is used, corrosive flux may be used providing the
device is cleaned and the flux is neutralized prior to final assembly.
3.3.2.5 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and
externally. Tin content of switch components and solder shall not exceed 97 percent, by mass. Tin shall
be alloyed with a minimum of 3 percent lead, by mass (see 6.3)
3.3.3 Nonmetals. Switches shall not be adversely affected by weathering and aircraft, missile, and
spacecraft fluids, at the temperature specified for the applicable switch.
3.3.3.1 Plastic. Unless otherwise specified (see 3.1), thermosetting plastics shall be in accordance
with ASTM-D5948; however, cotton or wood-cell-filled materials shall not be used. Thermoplastics shall
not be used for the switch case or cover. When used for non-case material, thermoplastic material shall
be in accordance with Type I of ASTM-D4066. The plastic material used shall be self-extinguishing when
tested in accordance with ASTM D635, as applicable, to the thinnest section of the material used. The
self-extinguishing requirement applies to all materials for external parts and enclosures regardless of
whether the material used is procured to a Military Specification or not.
3.3.3.2 Ceramic. Ceramic insulating material shall conform to SAE AMS-I-10, Grade L411 or better.
3.3.3.3 Potting compounds. Potting compounds used in contact with the atmosphere shall be in
accordance with A-A-59877 and shall be compatible with the design requirements of the switch.
3.3.4 Weldability. Leads designed for weldability shall conform to requirements of MIL-STD-1276, type K.
3.3.5 Screw terminals. Screw terminals shall be provided with hardware as specified (see 3.1 and
6.1.2). Lock washers shall be captive to the screw. For direct Government orders, all terminal hardware
shall be assembled in proper order.
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