MIL-SPEC Connectors: All things you Need to Know About Them

FACTS CHECKED BY  Jose George​

This post will hopefully clear some of the air surrounding the MIL-SPEC Connectors. Recently, the aftermarket automotive industry has started using Mil-Spec when marketing wiring harnesses connectors. So consumers believe that regular automotive connectors are “MIL-SPEC” because they are marketed and sold. 

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What are Military (MIL-SPEC) Connectors?

You may hear Military Connectors as “MIL-STD” or “MIL-SPEC” connectors. 

Mil-spec circular connectors have found use other than military applications in aviation, industry, shipping, and even the automobile. 

In such connectors, at least one of the connection pieces, or its contacts, should be floating to decrease mechanical strains. Moreover, these connectors typically come in pairs with either male (pin) or female (socket) contacts.

Contacts in electrical connectors are made up of Beryllium copper (BeCu) or Phosphor bronze. The manufacturers coat them with a layer of gold or another non-corrosive, highly conductive metal. Additionally, Mansel Glass serves as the dielectric insulator that surrounds the contacts inside the enclosure (i.e., the shell) of aluminum with a coating for corrosion protection.

Mil-Spec multi-Pin Connector

Caption: Mil-Spec multi-Pin Connector

Specifications of MIL-SPEC Connectors

Understanding product parameters is essential when choosing military (MIL-SPEC) connections. 

Contacts

  • The Number of Contacts: Connectors in the military have a certain number of contacts that must mate to create a reliable electrical connection.
  • Type of Contact: Pins and sockets are the two most common contact forms.
  • Coupling of Contact: Bayonet couplings, threaded couplings, push-and-pull (ball detent) couplings, breech-lock couplings, spring-rack couplings, and quick-connect couplings are all examples of coupling types.
  • The gauge of Contact: American Wire Gauge (AWG) is the standard notation for contacts’ sizes, identifying one connection from another.

Shell

  • Shell Style: The primary casing for a connector is the “shell” in this design approach. These shells are cylindrical and come in.375-inch sizes in their area. Furthermore, there are several different shell styles and genders, including straight plug, angle plug, wall/box mount, in-line/cable, dummy, solder/weld, jam nut, and bulkhead.
  • Shell Size: The most widely used shell size ranges from size 8 (0.50 inches) to size 36(2.25 inches). With every measure, it increases by 0.0625 inches in width. The producers of both connectors and accessories use the word “size” to describe the dimensions of their wares. Connector shell sizes are typically within (.062) of the socket shell size for military connectors that use threading to attach backshells.
  • Shell Gender: The gender of the shell is specified as either female or male. It’s common to refer to male “plugs” as “free connectors” or a header. The plug, usually movable, connects to a cable that serves as a detachable sub-assembly. Moreover, the connectors have the plug on the “hot” aspect of the system. Thus, a circuit connection is created when you place the pin into a female connector, like a jack, receptacle outlet, etc.

Terminals

Terminals connect the wires in a wire harness. To make the current path smoother, you can create a circuit by fixing studs, posts, or other metal surfaces. For that, you can choose from multiple options. 

Cage Clamp

A cage clamp ensures secure connections. Thus it is popular in places with uncertain conditions.

Crimp

It is possible to build an electrical and mechanical connection to a wire by compressing (deforming) contact wire barrels around the conductor.

Insulation Displacement Connectors (IDCs)

Cables can be joined together using insulation displacement connectors (IDCs). Thus, you work by displacing or cutting through the insulation of the lines. However, the insulation can be removed when you push a wire into a narrow slot in the connection part of a contract. So, instead of peeling insulation before connecting two ends of a flat wire, IDCs are used.

PCB Solder

Soldering wires to a PCB creates an electrical connection.

Screw

Connections in electrical systems are typically established using screws.

Lugs

Connecting electrical components requires the use of lugs.

Lanyard Release

A lanyard’s release allows for a range of lengths to be used. Other factors to consider are whether or not the product is MIL-SPEC compliant, whether or not it comes with a lanyard and backshell attachments, and whether or not you may use it for audio or visual purposes.

Solder Cup

To solder, you must first put conductors into a solder cup, a terminal end, or contact. Then, to join them, you can further use a metal or metal alloy. Here, a core composed of 60 percent tin and 40 percent lead is helpful when soldering electrical components. Moreover, the act of soldering requires the use of a wet procedure.

Tabs

You can also make electrical connections with the help of convenient tabs.

Through-Hole Technology

Manufacturers pass the leads through holes in the printed circuit boards using through-hole technology (THT). Then, they solder the resulting connections. Additionally, Pin termination is a method for attaching components to printed circuit boards that do not require soldering.

Wire Wrap

Electrical connections are created using wire wrap, in which a solid wire, either stripped or not, is wrapped around a terminal post with several sharp edges. A specialized wrapping tool is needed for this solder-free procedure.

Mil-Spec Commercial electronic connectors

Caption: Mil-Spec Commercial electronic connectors

Standard of MIL-SPEC Connectors

Military (MIL-SPEC) connectors are shell-type connectors built following military specifications. Their design considers the need to protect the connection from environmental factors, allowing them to be used in military and aerospace applications. EXCEPT for specific military specifications, other standards for Military (MIL-SPEC) connectors include RoHS compliance and ARINC.

Military Specifications

MIL-C-5015

The operating temperature range for these connectors is from -55 degrees Celsius to 125 degrees Celsius, 175 degrees Celsius, or 200 degrees Celsius, depending on the connector class.

MIL-C-22992

Heavy duty, multiple-contact, quick-disconnecting, high-power MIL-C-22992. Connectors can withstand temperatures from -55 to +125 degrees Celsius.

MIL-C-26482

General specifications for two families of small circular connectors that can withstand harsh environments and have a quick disconnect are outlined in the MIL-C-26482 standard.

MIL-C-26500

The MIL-C-26500 standard specifies a group of electrical connectors that can withstand harsh conditions to fulfill the needs of cutting-edge airplanes, rockets, missiles, and spaceships.

MIL-C-27599

Miniature electrical connectors from two different series that can work reliably from -65 degrees Celsius to +175 degrees Celsius are specified by MIL-C-27599.

MIL-C-38999

MIL-C-38999 covers two families of remote connections, and they can work reliably between -65 degrees Celsius and +175.0 degrees Celsius.

MIL-C-81703

The MIL-C-81703 standard includes miniature circular connectors that withstand harsh conditions and their corresponding accessories.

MIL-C-83723

It was a standard in earlier years. However, engineers have ruled out the Military Standard C-83723 Series I in favor of Military Standard C-26482 Series II later.

MIL-DTL-5015

When it comes to MIL-Aerospace connectors, the MIL-DTL-5015 standard is the workhorse. Further, it satisfies the needs of the aerospace and ground support sectors.

MIL-DTL-32139

The Defense Supply Center in Columbus, Ohio, is in charge of the MIL-DTL-32139 joint services specification (DSCC). The nano miniature connections in this Mil-Spec can be either plastic or metal.

MIL-DTL-38999

MIL-DTL-38999 specifies the four types of connectors. They can function in temperatures ranging from -65 degrees Celsius to +200 degrees Celsius, and their contacts are either replaceable crimps or fixed hermetic solder.

MIL-DTL-83513

This specification, known as MIL-DTL-83513, is managed by the Defense Supply Center in Columbus, Ohio, on behalf of the armed forces (DSCC). Also, it supports both plastic and metal Micro-D shells.

MIL-DTL-83723

The electrical connectors, contacts, and accessories are all addressed in MIL-DTL-83723.

Connectors that meet RoHS and ARINC requirements are also acceptable with military equipment that uses Mil-Spec connectors.

RoHS Compliant

The European Union (EU) has the Restriction of Hazardous Substances (RoHS) directive. According to it, all electronic equipment in the markets of Europe must have certifications having no more than the legally allowed amounts of a wide range of elements. These include lead, cadmium, mercury, and diphenyl ether.

PRINT

To put it simply, ARINC is an aviation industry technical standard. Connectors that meet the ARINC standard are used to join together various pieces of aviation electronics.

Commercial Wire connectors 

Caption: Commercial Wire connectors 

Features of MIL-SPEC Connectors

Additional features are offered for military (MIL-SPEC) plugs to improve their functionality in the intended environment.

  • A filter or magnetics built into the connector shields it from interference.
  • These connectors have proper sealing to allow for use in submerged environments.
  • Also, they have hermetic sealing, so there are no condensation or other moisture leaks.
  • Moreover, the connector prevents electrostatic discharge (ESD) and electromagnetic interference (EMI) by a filter and shielding.
  • The environmental resistance of the connectors ensures that they will not break down when exposed to chemicals, sunlight, dirt, etc.

Conclusion

Mil-spec connectors ensure safety and product quality. Thus many industries prefer these components nowadays. Also, there are specific standards like military specifications and the RoHS and ARINC regulations to which it has to conform. Or, if you want to use them in harsh conditions, you can order ones with unique features. Here at Cloom, we offer wiring harnesses and cable assemblies with types of mil-spec connectors available so your connection can be safe and reliable.

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