Definitions of Electronic Terms
"A" "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

Back Shell Definition

What is a Back Shell. A Backshell is the rear portion of a connector, which is normally a separate section from the connector head, used to secure the cable via a clamp to the end of the connector. Also called a Hood.

Flat Cable Connector Back Shell Diagram
Connector Back Shell

D-Sub Connector Back Shell per MIL-C-24308/20

A Connector Backshell is a component specifically designed to be placed around that portion of a connector [plug or receptacle] which contains the facilities for attaching wires or cables. A backshell may be designed to provide the necessary accommodations between an electrical cable clamping device and an electrical connector shell, or it may include the clamping device. It may be used for shielding against electrical interference, mechanical injury, or physical damage due to environmental conditions.

A Back Shell is used to shield the wire connection points of the inter-connecting cable and the connector. Some Back-Shells include a cable clamp [shown above] to secure the cable to the back shell and connector. The length of the cable clamp varies with the connector and the number of wires the connector accepts, the more wires the larger the back shell. A grommet may be supplied which needs to be sized to the Outside Diameter [OD] of the cable. In some cases the back-shell may only consist of Threaded Strain Relief. Backshells may also be purchased as a 90o Backshell or 45 degrees Back shell, with EMI or Environmental protecting.

In some cases the cable shield is connected to the back shell, in other cases the cable drain wire connects to the back shell. However, there are cases when no wire is attached to the shell of the connector or the back shell so that no connection is passed from the cable to the attachment point.
See Definition of Faraday Shield.

Manufacturers of Connectors / Dsub Vendor Manufacturers
Manufacturers of Cable Clamps
Manufacturers of Cable Strain Reliefs

Metal EMI
D-Sub Back-Shell
Round Cable

Round Cable Connector Back Shell Diagram Back Shell
Connector Back Shell

MIL-C-24308/20; [MIL D-Sub Backshells]; Connectors, Electric, Rectangular, Miniature, Polarized Shell, Rack and Panel, Shield, Straight, Deep
MIL-C-85049/11; [MIL Cylindrical Backshells]; Connector Accessories, Electrical, Backshell, Environmental, Cable Sealing, Straight, Category 1A, (for Mil-C-5015 Crimp, MIL-C-26482 Series 2, MIL-C81703 Series 3, and MIL-C-83723 Series III Connectors. [M85049]
MIL-C-85049/12; [MIL Cylindrical Backshells]; Connector Accessories, Electrical, Strain Relief, Self-Locking and Non-Self-Locking, Straight, Category 4B (for Mil-C-5015 Crimp, MIL-C-26482 Series 2, MIL-C81703 Series 3, and MIL-C-83723 Series III Connectors.

90 degree Connector Back Shell Diagram
Right Angle Connector Back Shell, D-Sub

Each of the graphics above show examples of backshells for D-Sub connectors. The first back-shell is a D-sub connector using a flat cable. The next two pictures are D-sub connectors with a backshell using a round cable, with either a straight backshell or right-angle back-shell. Part of the MIL-DTL-28840 series of Navy connectors, high shock.

Molex Connector Clam Shell Back Shell
Molex Back Shell

The example just right shows a clam shell style backshell used with a Molex style connector.
The example below shows and example of a circular MIL connector with an attached back-shell.

MIL-DTL-28840 Connector and Back Shell
MIL-DTL-28840 Connector and Back Shell

Back Shells should be used with any type connector to protect the cable connections and provide Strain Relief to the solder joints. In most, but not all cases the back shell is a separate part number, so be sure to request a back shell part number when ordering a connector. Of course ask for the straight, 45 degree or 90 degree back shell as required in the design.

PC motherboard

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