It is said that in the early 1930s, Cannon (now part of ITT-Cannon) developed connectors for Douglas Aircraft Corporation for DC-1 and subsequent DC-2 and DC-3 aircraft platforms. In the late 1930s, during World War II, Cannon began mass production of multi-core electrical connectors used by almost all aircraft manufacturers in the United States.
Connon's "A/N" (Army/Navy) series of connectors laid a solid foundation for the establishment of modern military circular connector standard specifications, and gradually evolved into the first connector standard marked MIL in the late 1940s. -5015 US military standard, commonly known as the first generation US military grade connector
(MIL-5015 is equivalent to China's GJB600A-2001).
The follow-up Mil-STD was informally called Mil-Spec or MS. It is now widely used in the aerospace, industrial, marine, and even automotive industries. Standards generally include a complete standard system including general specifications, sub-specifications, and QPL (qualified product catalog). Any US Department of Defense not listed in the QPL will not allow manufacturers to provide it to the military.
Connector terminals that comply with US military standards are usually made of beryllium copper (BeCu) or phosphor bronze, and then plated with gold or other non-corrosive highly conductive metals.
The terminals are separated by an insulator and placed in a housing. The housing is usually die-cast aluminum and is treated by electroplating or anodizing. There are also composite materials and stainless steel materials. The terminal end is either soldered or crimped. The housing and the insulating sheath are moisture-proof or sealed.
The housing and the insulating sheath usually include keyed foolproof and scoop-proof functions to prevent erroneous docking that may damage connector terminals or cause electrical problems. In addition, cable clamps and other installed accessories usually use a locking mechanism to protect the connected parts to prevent breakage and cracking.
Remarks: Scoop-Proof connector: It is the anti-oblique connector. It is designed to prevent the plug from damaging or short-circuiting the terminal on the socket when the military connectors and components
are blindly inserted. Generally, lengthening the length of the outer shell of the socket is conducive to blind insertion.
The MIL-STD-38999 type III connector appeared in the 1980s, and the composite material 38999III appeared in the 1990s. This upgrade due to its fast threaded butt joint mode allows rapid advancement of back stitches and vibration resistance. It is widely used by the military and civil aviation departments.
In addition, the US military standard has specially prepared the M39029 standard for connector terminals and the M85049 standard for cable rear accessories, which further details the path of the connector in military applications. The US government has the same export ban on high-grade connectors as high-tech chips, which shows the importance of military-standard connectors.