MIL-DTL-28731F
3.3 Materials. Examples of materials used in manufacturing these connectors are identified herein.
However, when a specific material is not identified, a material shall be used which will enable the sockets
and accessories to meet the requirements of this specification. Acceptance or approval of a constituent
material shall not be construed as a guaranty of acceptance of the finished product.
3.3.1 Reference materials, plating, and processes. The materials, plating and processes identified in
this specification assure that connectors will properly interface to similar industry standard and
government specified connector systems, without problems such as electrochemical contamination or
deterioration, electrolytic corrosion, or excessive surface wear. Manufacturers may be allowed minor
variations from these exact requirements upon written request to, and subsequent written approval from
DSCC-VAI. Significant variations from this specification, especially those which could affect short or long
term reliability or performance, must undergo the normal coordination and approval process. Any short or
long term failures or reliability problems due to such deviation shall be the responsibility of the supplier.
3.3.2 Recycled, recovered, or environmentally preferable material. 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.
3.3.3 Nonmagnetic materials. All parts, with the exception of screws, washers, and mounting hardware,
shall be made from materials, which are classified, as nonmagnetic and the permeability of the basic
connector shall be less than 2.0μ. The permeability shall be checked by the instrument described in
ASTM A342/A342M or equivalent (see 4.7.2).
3.3.4 Dissimilar metals. When dissimilar metals are used in intimate contact with each other, protection
against electrolysis and corrosion shall be provided as specified in MIL-STD-889.
3.3.5 Contacts and plating.
3.3.5.1 Contacts. Contacts shall be made of phosphor bronze in accordance with ASTM B139/B139M.
3.3.5.1.1 Plating. Unless otherwise specified, the contacts shall be plated as follows.
3.3.5.1.2 Contact mating area. The contact mating area shall be gold plated in accordance with
ASTM B488, type 2, code C, class 1.27 μm (50 microinches minimum) over a nickel underplate in
accordance with SAE-AMS-QQ-N-290, class 2, 50 microinches (1.27 μm) minimum.
3.3.5.1.3 Remaining areas of the contact. Those areas of the contact not included in 3.3.5.1.1 and
3.3.5.1.2 shall be nickel plated in accordance with SAE-AMS-QQ-N-290, class 2 with a minimum
thickness of 50 microinches (1.27 μm). Overplating is not required in this area.
3.3.5.1.4 Contacts furnished in strip form. If contacts are furnished in strip form, when the contact is
separated from the carrier strip, the absence of the nickel or other plating at the broken edge of the
contact is acceptable, provided it is in a nonfunctional area of the contact and any corrosion formed as a
result of the salt spray test does not creep into the contact mating area.
3.3.5.2 Terminations.
3.3.5.2.1 Wrappost terminations. Wrappost terminations shall be gold plated in accordance with
ASTM B488, type 2, code C, class 1.27 μm (50 microinches minimum) over a nickel underplate in
accordance with SAE-AMS-QQ-N-290, class 2, 30 microinches (0.76 μm) minimum.
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