D-Sub Connectors
The D-subminiature or D-sub is a common type of
electrical connector. They are named for their characteristic D-shaped metal
shield. When they were introduced, D-subs were among the smaller connectors
used on computer systems.
A D-sub contains two or more parallel rows of pins or sockets usually
surrounded by a D-shaped metal shield that provides mechanical support,
ensures correct orientation, and may screen against electromagnetic
interference. The part containing pin contacts is called the male connector
or plug, while that containing socket contacts is called the female
connector or socket. The socket's shield fits tightly inside the plug's
shield. The plug also may have screws on either side of the shield that
fasten into holes in the socket (although sometimes the screws are on the
socket: see the DE9 pictured to the left). When screened cables are used,
the shields are connected to the overall screens of the cables. This creates
an electrically continuous screen covering the whole cable and connector
system.
Wire-contact attachment types
There are at least five different methods used to attach wires to the
contacts in D-sub connectors.
-
Solder-bucket (or solder-cup) contacts have
a cavity into which the stripped wire is inserted and hand-soldered.
-
Insulation displacement contacts (IDCs)
allow a ribbon cable to be forced onto sharp tines on the back of the
contacts; this action pierces the insulation of all the wires
simultaneously. This is a very quick means of assembly whether done by
hand or automatically.
-
Crimp contacts are assembled by inserting a
stripped wire end into a cavity in the rear of the contact, then
crushing the cavity using a crimp tool, causing the cavity to grip the
wire tightly at many points. The crimped contact is then inserted into
the connector where it locks into place. Individual crimped pins can be
removed later by inserting a special tool into the rear of the
connector.
-
PCB pins are soldered directly to a printed
circuit board and not to a wire. These connectors are frequently mounted
at a right angle to the PCB, allowing a cable to be plugged into the
edge of the PCB assembly.
-
Wire wrap connections are made by wrapping
solid wire around a square post with a wire wrap tool. This type of
connection is usually used in prototyping.
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