
An insulation-displacement contact (IDC), also known as insulation-piercing contact (IPC), is an
electrical connector
Components of an electrical circuit are electrically connected if an electric current can run between them through an electrical conductor. An electrical connector is an electromechanical device used to create an electrical connection between ...
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
Western Electric Co., Inc. was an American electrical engineering and manufacturing company that operated from 1869 to 1996. A subsidiary of the AT&T Corporation for most of its lifespan, Western Electric was the primary manufacturer, supplier, ...
,
Bell Telephone Labs, and others.
Although originally designed to connect only solid (single-stranded) conductors, IDC technology was eventually extended to multiple-
stranded wire as well.
Initially, IDCs were seen only in
extra-low voltage
Extra-low voltage (ELV) is an electricity supply voltage and is a part of the low-voltage bandIEC 61140:2016 Chapter 4.2 in a range which carries a low risk of dangerous electrical shock. There are various standards that define extra-low voltage. ...
applications, such as
telecommunications
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...
,
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 (power) 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 (the red coded wire), and so on.
Telephone and network plugs
In some types of telephone and network plug, including the
BS 6312 and the
registered jack
A registered jack (RJ) is a standardized telecommunication network interface device, network interface for connecting voice and data equipment to a computer service provided by a local exchange carrier or long distance carrier. Registered inter ...
(RJ) 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 correct conductors go into the correct slots. Modular connectors used with
Category 5 twisted pair
Twisted pair cabling is a type of communications cable in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced ...
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 frame
In telecommunications, a distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made.
For example, the Main Distribution Frame (MDF) located at a telephone exchange, telephone central office te ...
s, 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 (pitch), number of pins, and number of rows. Connectors commonly used in computers include:
* 3.5 inch
IDE desktop computer
A desktop computer, often abbreviated as desktop, is a personal computer designed for regular use at a stationary location on or near a desk (as opposed to a portable computer) due to its size and power requirements. The most common configuratio ...
hard disk drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...
s – 2.54 mm pitch, 40 pins, 2×20 (2 rows of 20 pins)
* 2.5 inch IDE
notebook computer
A notebook computer or notebook is, historically, a laptop whose length and width approximate that of letter paper ().
The term ''notebook'' was coined to describe slab-like portable computers that had a letter-paper footprint, such as Epson's ...
hard disk drives – 2.00 mm pitch, 44 pins, 2×22 (2 rows of 22 pins)
*
SCSI
Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced ...
8-bit – pitch, 50 pins, 2×25 (2 rows of 25 pins)
* SCSI 16-bit – pitch, 68 pins, 2×34 (2 rows of 34 pins)
*
Floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...
– pitch, 34 pins, 2×17 (2 rows of 17 pins)
*
Serial DE-9 on motherboards – pitch, 10 pins, 2×5 (2 rows of 5 pins) – sometimes called ''everex''
*
Parallel DB-25
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 smallest connectors used on computer systems.
Description, ...
– pitch, 26 pins, 2×13 (2 rows of 13 pins)
* In some instances
USB
Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...
through version 2 on motherboards – pitch, 10 pins, 2×5 (2 rows of 5 pins)
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 male
box header or
pin header on the computer motherboard.
See also
*
Vampire tap
A vampire is a mythical creature that subsists by feeding on the Vitalism, vital essence (generally in the form of blood) of the living. In European folklore, vampires are undead, undead humanoid creatures that often visited loved ones and c ...
*
Wire wrap
*
DC connector
A DC connector (or DC plug, for one common type) is an electrical connector that supplies direct current (DC) power.
Compared to domestic AC power plugs and sockets, DC connectors have many more standard types that are not interchangeable. The d ...
*
Krone LSA-PLUS
*
Berg connector
*
JST connector
*
Molex connector
*
Pin header
References
External links
{{Commons category, Insulation displacement connectors
IDC Cable, Headers & ConnectorsBrochure on 3M Scotchlok insulation displacement connectorsMolex Connectors Explained, as used in PinballInsulation Displacement Contact Technologyfrom Sensors, May 2001.
A New Type of Very High Reliability Torsion IDCZierick Manufacturing Corporation white paper.
Electrical signal connectors
Telephone connectors