An insulation-displacement contact, also known as insulation-piercing contact, is
an electrical connector designed to be connected to the conductor(s) of an
insulated cable by a connection process which forces a selectively sharpened
blade or blades through the insulation, bypassing the need to strip the
conductors of insulation before connecting. When properly made, the
connector blade cold-welds to the conductor, making a theoretically
reliable gas-tight connection. History
Modern IDC technology developed after and was influenced by research on
wire-wrap and crimp connector technology originally pioneered by Western
Electric, Bell Telephone Labs, and others. Although originally designed to
connect only solid conductors, IDC technology was eventually extended to
multiple-stranded wire as well. Initially, IDCs were seen only in
extra-low voltage applications, such as telecommunications, networking and
signal connections between parts of an electronic or computer system. However,
they are now also used in some domestic and industrial low voltage applications,
as can be seen in the illustration. The benefits claimed for their use in these
applications include up to 50 percent faster installation, due to the
reduction in the stripping, twisting and screwing down processes.
Ribbon cable Ribbon cable is designed to be used with
multi-contact IDC connectors in such a way that many IDC connections can be
made at once, saving time in applications where many connections are
needed. These connectors are not designed to be reusable, but can often
be re-used if care is taken when removing the cable.
Pin 1 is typically indicated on the body of the connector by a red or raised "V"
mark. The corresponding wire in a ribbon cable is usually indicated by red
coloration, a raised molded ridge, or markings printed onto the cable
insulation. On the connector pin 2 is opposite pin 1, pin 3 is next to pin 1
along the length of the connector, and so on. On the cable, the wire connected
to pin 2 is next to the wire connected to pin 1, and so on.
Telephone and network plugs In some types of telephone and network
plug, including the BS 6312 and the registered jack family, generally
separate wires in a sheath are used. In these applications, the outer sheath is
stripped then the wires are inserted into the connector and a special
termination tool is used to force the conductors into the contacts.
Traditionally these connectors have been used with flat cable which makes it easy
to ensure the right conductors go into the right slots. However modular
connectors used with Category 5 twisted pair cable require careful arranging of
the conductors by hand before inserting them into the connector.
Punch-down blocks Punch-down blocks are intended to
connect individual conductors punched down into each position in the block
with a special punch-down tool. Punch-down terminations are also
generally seen in telephone and network connectors, in patch panels and
distribution frames, and in telephone equipment such as PBXs.
Common layouts Pins are commonly numbered from pin 1
with odd numbers along one side and the even numbers along the other side.
Connectors are categorized by pin spacing in mm, number of pins, and
number of rows. Connectors commonly used in computers include:
3.5 in IDE desktop computer hard disc drives – 2.54 mm pitch, 40 pins, 2×20
2.5 in IDE notebook computer hard disc drives – 2.00 mm pitch, 44 pins, 2×22
SCSI 8-bit – 2.54 mm pitch, 50 pins, 2×25
SCSI 16-bit – 1.27 mm pitch, 68 pins, 2×34
Floppy disk – 2.54 mm pitch, 34 pins, 2×17
Serial DE-9 on motherboards – 2.54 mm pitch, 10 pins, 2×5 – sometimes called
everex Parallel DB-25 – 2.54 mm pitch, 26 pins,
2×13 In some instances USB through version 2
on motherboards – 2.54 mm pitch, 10 pins, 2×5
For all of the above connectors, the computer manufacturer typically attaches
a female IDC connector onto one end of a ribbon cable, and later slides that
connector onto a matching pin header on the computer motherboard.
See also Vampire tap
Wire wrap Electrical connector
DC connector Berg connector
JST connector Molex connector
Pin header connector References
External links IDC Cable, Headers & Connectors
Brochure on 3M Scotchlok insulation displacement connectors
Molex Connectors Explained, as used in Pinball
Insulation Displacement Contact Technology from Sensors, May 2001.
A New Type of Very High Reliability Torsion IDC Zierick Manufacturing
Corporation white paper. AT/Everex wiring for RS-232 COM port