![ATX computer case - back - 2018-03-18](https://upload.wikimedia.org/wikipedia/commons/4/4a/ATX_computer_case_-_back_-_2018-03-18.jpg)
Components of an
electrical circuit are electrically connected if an
electric current can run between them through an
electrical conductor
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gene ...
. An electrical connector is an
electromechanical
In engineering, electromechanics combines processes and procedures drawn from electrical engineering and mechanical engineering. Electromechanics focuses on the interaction of electrical and mechanical systems as a whole and how the two systems ...
device used to create an electrical connection between parts of an electrical circuit, or between different electrical circuits, thereby joining them into a larger circuit.
Most electrical connectors have a
gender
Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most cultures ...
i.e. the male component, called a ''plug'', connects to the female component, or ''socket''. The connection may be removable (as for portable equipment), require a tool for assembly and removal, or serve as a permanent electrical joint between two points.
An
adapter
An adapter or adaptor is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one c ...
can be used to join dissimilar connectors.
Thousands of configurations of connectors are manufactured for
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
,
data
In the pursuit of knowledge, data (; ) is a collection of discrete Value_(semiotics), values that convey information, describing quantity, qualitative property, quality, fact, statistics, other basic units of meaning, or simply sequences of sy ...
, and
audiovisual
Audiovisual (AV) is electronic media possessing both a sound and a visual component, such as slide-tape presentations, films, television programs, corporate conferencing, church services, and live theater productions.
Audiovisual service pr ...
applications.
Electrical connectors can be divided into four basic categories, differentiated by their function:
* ''inline'' or ''cable'' connectors permanently attached to a cable, so it can be plugged into another
terminal
Terminal may refer to:
Computing Hardware
* Terminal (electronics), a device for joining electrical circuits together
* Terminal (telecommunication), a device communicating over a line
* Computer terminal, a set of primary input and output dev ...
(either a stationary instrument or another cable)
* ''Chassis'' or ''panel'' connectors permanently attached to a piece of equipment so users can connect a cable to a stationary device
* ''PCB mount'' connectors soldered to a
printed circuit board, providing a point for
cable
Cable may refer to:
Mechanical
* Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof
* Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...
or
wire
Overhead power cabling. The conductor consists of seven strands of steel (centre, high tensile strength), surrounded by four outer layers of aluminium (high conductivity). Sample diameter 40 mm
A wire is a flexible strand of metal.
Wire is c ...
attachment.
(e.g.
pin header
A pin header (or simply header) is a form of electrical connector. A male pin header consists of one or more rows of metal pins molded into a plastic base, often apart, though available in many spacings. Male pin headers are cost-effective du ...
s,
screw terminal
A screw terminal is a type of electrical connection where a wire is held by the tightening of a screw.
Description
The wire may be wrapped directly under the head of a screw, may be held by a metal plate forced against the wire by a screw, o ...
s,
board-to-board connector Board-to-board (BTB) connectors are used to connect printed circuit boards (PCB), electronic components that contain a conductive pattern printed on the surface of the insulating base in an accurate and repeatable manner. Each terminal on a BTB conn ...
s)
* ''Splice'' or ''butt'' connectors (primarily
insulation displacement connector
An insulation-displacement contact (IDC), also known as insulation-piercing contact (IPC), is an electrical connector designed to be connected to the conductor(s) of an insulated cable by a connection process which forces a selectively sharp ...
s) that permanently join two lengths of wire or cable
In computing, electrical connectors are considered a physical interface and constitute part of the
physical layer in the
OSI model
The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...
of networking.
Physical construction
In addition to the classes mentioned above, connectors are characterised by their
pinout
In electronics, a pinout (sometimes written "pin-out") is a cross-reference between the contacts, or ''pins'', of an electrical connector or electronic component, and their functions. "Pinout" now supersedes the term "basing diagram" that was the s ...
,
method of connection, materials, size,
contact resistance
The term contact resistance refers to the contribution to the total resistance of a system which can be attributed to the contacting interfaces of electrical leads and connections as opposed to the intrinsic resistance. This effect is describe ...
,
insulation
Insulation may refer to:
Thermal
* Thermal insulation, use of materials to reduce rates of heat transfer
** List of insulation materials
** Building insulation, thermal insulation added to buildings for comfort and energy efficiency
*** Insulated ...
, mechanical durability,
ingress protection
The IP code or ingress protection code indicates how well a device is protected against water and dust. It defined by the International Electrotechnical Commission (IEC) under the international standard IEC 60529 which classifies and p ...
,
lifetime (number of cycles), and ease of use.
It is usually desirable for a connector to be easy to identify visually, rapid to assemble, inexpensive, and require only simple tooling. In some cases an equipment manufacturer might choose a connector specifically because it is ''not'' compatible with those from other sources, allowing control of what may be connected. No single connector has all the ideal properties for every application; the proliferation of types is a result of the diverse yet specific requirements of manufacturers.
Materials
Electrical connectors essentially consist of two classes of materials: conductors and insulators. Properties important to conductor materials are contact resistance,
conductivity
Conductivity may refer to:
*Electrical conductivity, a measure of a material's ability to conduct an electric current
**Conductivity (electrolytic), the electrical conductivity of an electrolyte in solution
** Ionic conductivity (solid state), ele ...
,
mechanical strength
The field of strength of materials, also called mechanics of materials, typically refers to various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the re ...
,
formability Formability is the ability of a given metal workpiece to undergo plastic deformation without being damaged. The plastic deformation capacity of metallic materials, however, is limited to a certain extent, at which point, the material could experienc ...
, and
resilience.
Insulators must have a high
electrical resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual paralle ...
, withstand high temperatures, and be easy to manufacture for a precise fit.
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...
s in connectors are usually made of
copper alloy
Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both of t ...
s, due to their good conductivity and
malleability.
Alternatives include
brass
Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wit ...
,
phosphor bronze
Phosphor bronze is a member of the family of copper alloys. It is composed of copper that is alloyed with 0.5–11% of tin and 0.01–0.35% phosphorus, and may contain other elements to confer specific properties (e.g. lead at 0.5–3.0% to form ...
, and
beryllium copper. The base electrode metal is often coated with another inert metal such as
gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...
,
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...
, or
tin
Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal.
Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
.
The use of a coating material with good conductivity, mechanical robustness and corrosion resistance helps to reduce the influence of passivating oxide layers and surface adsorbates, which limit metal-to-metal contact patches and contribute to contact resistance. For example, copper alloys have favorable mechanical properties for electrodes, but are hard to solder and prone to corrosion. Thus, copper pins are usually coated with gold to alleviate these pitfalls, especially for analog signals and high reliability applications.
Contact ''carriers'' that hold the parts of a connector together are usually made of plastic, due to its insulating properties. ''Housings'' or ''
backshells'' can be made of molded plastic and metal.
Connector bodies for high-temperature use, such as
thermocouple
A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of th ...
s or associated with large
incandescent lamps, may be made of fired ceramic material.
Failure modes
The majority of connector failures result in intermittent connections or open contacts:
Connectors are purely
passive
Passive may refer to:
* Passive voice, a grammatical voice common in many languages, see also Pseudopassive
* Passive language, a language from which an interpreter works
* Passivity (behavior), the condition of submitting to the influence of o ...
componentsthat is, they do not enhance the function of a circuitso connectors should affect the function of a circuit as little as possible. Insecure mounting of connectors (primarily chassis-mounted) can contribute significantly to the risk of failure, especially when subjected to extreme shock or vibration.
Other causes of failure are connectors inadequately rated for the applied current and voltage, connectors with inadequate ingress protection, and threaded
backshells that are worn or damaged.
High temperatures can also cause failure in connectors, resulting in an "avalanche" of failuresambient temperature increases, leading to a decrease in insulation resistance and increase in conductor resistance; this increase generates more heat, and the cycle repeats.
Fretting
Fretting refers to wear and sometimes corrosion damage of loaded surfaces in contact while they encounter small oscillatory movements tangential to the surface. Fretting is caused by adhesion of contact surface asperities, which are subsequent ...
(so-called ''dynamic corrosion'') is a common
failure mode
Failure causes are defects in design, process, quality, or part application, which are the underlying cause of a failure or which initiate a process which leads to failure. Where failure depends on the user of the product or process, then human er ...
in electrical connectors that have not been specifically designed to prevent it, especially in those that are frequently mated and de-mated. Surface
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...
is a risk for many metal parts in connectors, and can cause contacts to form a thin surface layer that increases resistance, thus contributing to heat buildup and intermittent connections.
However, remating or reseating a connector can alleviate the issue of surface corrosion, since each cycle scrapes a microscopic layer off the surface of the contact(s), exposing a fresh, unoxidised surface.
Circular connectors
Many connectors used for industrial and high-reliability applications are circular in cross section, with a cylindrical housing and circular contact interface geometries. This is in contrast to the rectangular design of some connectors, e.g.
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
or
blade connectors. They are commonly used for easier engagement and disengagement, tight environmental sealing, and rugged mechanical performance.
They are widely used in military, aerospace, industrial machinery, and rail, where
MIL-DTL-5015
MIL-DTL-5015 is a United States Military Standard which covers heavy-duty circular electrical connectors with soldered or crimped contacts. They are used for both digital and analog signals, as well as power distribution, and are common in v ...
and
MIL-DTL-38999 are commonly specified. Fields such as
sound engineering
An audio engineer (also known as a sound engineer or recording engineer) helps to produce a recording or a live performance, balancing and adjusting sound sources using equalization, dynamics processing and audio effects, mixing, reproductio ...
and
radio communication also use circular connectors, such as
XLR and
BNC.
AC power plugs are also commonly circular, for example,
Schuko
"Schuko" () is a registered trademark referring to a system of AC power plugs and sockets that is defined as " CEE 7/3" (sockets) and "CEE 7/4" (plugs). A Schuko plug features two round pins of 4.8 mm diameter (19 mm long, centers 19&n ...
plugs and
IEC 60309
IEC 60309 (formerly IEC 309 and CEE 17, also published by CENELEC as EN 60309) is a series of international standards from the International Electrotechnical Commission (IEC) for "plugs, socket-outlets and couplers for industrial purp ...
.
![N2K-CABLING](https://upload.wikimedia.org/wikipedia/commons/1/1f/N2K-CABLING.jpg)
The
M12 connector, specified in IEC 61076-2-101, is a circular electrical plug/receptacle pair with 12mm OD mating threads, used in
NMEA 2000 NMEA 2000, abbreviated to NMEA2k or N2K and standardised as IEC 61162-3, is a plug-and-play communications standard used for connecting marine sensors and display units within ships and boats. Communication runs at 250 kilobits-per-second and allows ...
,
DeviceNet DeviceNet is a network protocol used in the automation industry to interconnect control devices for data exchange. It utilizes the Common Industrial Protocol over a Controller Area Network media layer and defines an application layer to cover a rang ...
,
IO-Link, some kinds of
Industrial Ethernet
Industrial Ethernet (IE) is the use of Ethernet in an industrial environment with protocols that provide determinism and real-time control. Protocols for industrial Ethernet include EtherCAT, EtherNet/IP, PROFINET, POWERLINK, SERCOS III, CC ...
, etc.
A disadvantage of the circular design is its inefficient use of panel space when used in arrays, when compared to rectangular connectors.
Circular connectors commonly use
backshells, which provide physical and electromagnetic protection, whilst sometimes also providing a method for locking the connector into a receptacle.
In some cases, this backshell provides a
hermetic seal
A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers, but as technology advanced it applied to a larger categor ...
, or some degree of
ingress protection
The IP code or ingress protection code indicates how well a device is protected against water and dust. It defined by the International Electrotechnical Commission (IEC) under the international standard IEC 60529 which classifies and p ...
, through the use of
grommet
Curtain grommets, used among others in shower curtains.
A grommet is a ring or edge strip inserted into a hole through thin material, typically a sheet of textile fabric, sheet metal or composite of carbon fiber, wood or honeycomb. Grommets ar ...
s,
O-ring
An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...
s, or
potting.
Hybrid connectors
Hybrid connectors allow the intermixing of many connector types, usually by way of a housing with inserts. These housings may also allow intermixing of electrical and non-electrical interfaces, examples of the latter being pneumatic line connectors, and
optical fiber connectors. Because hybrid connectors are modular in nature, they tend to simplify assembly, repair, and future modifications. They also allow the creation of composite cable assemblies that can reduce equipment installation time by reducing the number of individual cable and connector assemblies.
Mechanical features
Pin sequence
Some connectors are designed such that certain pins make contact before others when inserted, and break first on disconnection.
This is often used in
power connectors to protect equipment, e.g. connecting
safety ground
In electrical engineering, ground or earth is a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.
Electrical circuits may be con ...
first. It is also employed for digital signals, as a method to sequence connections properly in
hot swapping
Hot swapping is the replacement or addition of components to a computer system without stopping, shutting down, or rebooting the system; hot plugging describes the addition of components only. Components which have such functionality are said ...
.
Keying
Many connectors are keyed with some mechanical component (sometimes called a ''keyway''), which prevents mating in an incorrect orientation.
This can be used to prevent mechanical damage to connectors, from being jammed in at the wrong angle or into the wrong connector, or to prevent incompatible or dangerous electrical connections, such as plugging an audio cable into a power outlet.
Keying also prevents otherwise symmetrical connectors from being connected in the wrong orientation or ''polarity''. Keying is particularly important for situations where there are many similar connectors, such as in signal electronics.
For instance,
XLR connector
The XLR connector is a type of electrical connector primarily used in professional audio, video, and stage lighting equipment. XLR connectors are cylindical in design, and have three to seven connector pins, and are often employed for analog b ...
s have a notch to ensure proper orientation, while
Mini-DIN
The mini-DIN connectors are a family of multi-pin electrical connectors used in a variety of applications. Mini-DIN is similar to the larger, older DIN connector.
Design
Mini-DIN connectors are in diameter and come in seven patterns, wit ...
plugs have a plastic projection that fits into a corresponding hole in the socket (they also have a notched metal skirt to provide secondary keying).
Locking mechanisms
Some connector housings are designed with locking mechanisms to prevent inadvertent disconnection or poor environmental sealing.
Locking mechanism designs include locking levers of various sorts,
jackscrew
A jackscrew, or screw jack, is a type of jack that is operated by turning a leadscrew. It is commonly used to lift moderately and heavy weights, such as vehicles; to raise and lower the horizontal stabilizers of aircraft; and as adjustable supp ...
s, screw-in shells,
push-pull connector, and toggle or
bayonet systems. Some connectors, particularly those with large numbers of contacts, require high forces to connect and disconnect. Locking levers and jackscrews and screw-in shells for such connectors frequently serve both to retain the connector when connected and to provide the force needed for connection and disconnection. Depending on application requirements, housings with locking mechanisms may be tested under various environmental simulations that include physical shock and vibration, water spray, dust, etc. to ensure the integrity of the electrical connection and housing seals.
Backshells
Backshells are a common accessory for industrial and high-reliability connectors, especially
circular connectors.
Backshells typically protect the connector and/or cable from environmental or mechanical stress, or shield it from
electromagnetic interference.
Many types of backshells are available for different purposes, including various sizes, shapes, materials, and levels of protection. Backshells usually lock onto the cable with a clamp or moulded boot, and may be threaded for attachment to a mating receptacle.
Backshells for military and aerospace use are regulated by SAE AS85049 within the USA.
Hyperboloid contacts
To deliver ensured signal stability in extreme environments, traditional pin and socket design may become inadequate. Hyperboloid contacts are designed to withstand more extreme physical demands, such as vibration and shock.
They also require around 40% less insertion force
as low as per contact,
which extends the lifespan, and in some cases offers an alternative to
zero insertion force
Zero insertion force (ZIF) is a type of IC socket or electrical connector that requires very little (but not literally zero) force for insertion. With a ZIF socket, before the IC is inserted, a lever or slider on the side of the socket is move ...
connectors.
In a connector with hyperboloid contacts, each female contact has several equally spaced longitudinal wires twisted into a hyperbolic shape. These wires are highly resilient to strain, but still somewhat elastic, hence they essentially function as linear springs.
[.] As the male pin is inserted, axial wires in the socket half are deflected, wrapping themselves around the pin to provide a number of contact points. The internal wires that form the hyperboloid structure are usually anchored at each end by bending the tip into a groove or notch in the housing.
[.]
Whilst hyperboloid contacts may be the only option to make a reliable connection in some circumstances, they have the disadvantage of taking up greater volume in a connector, which can cause problems for high-density connectors.
They are also significantly more expensive than traditional pin and socket contacts, which has limited their uptake since their invention in the 1920s by Wilhelm Harold Frederick.
[.] In the 1950s, Francois Bonhomme popularised hyperboloid contacts with his "Hypertac" connector, which was later acquired by
Smiths Group
Smiths Group plc is a British, multinational, diversified engineering business headquartered in London, England. It operates in over 50 countries and employs 14,600 staff.
Smiths Group has its origins in a jewellery shop, ''S Smith & Sons'', ...
. During the following decades, the connectors steadily gained popularity, and are still used for medical, industrial, military, aerospace, and rail applications (particularly trains in Europe).
Pogo pins
![Pogo Pin Connectors](https://upload.wikimedia.org/wikipedia/commons/f/f3/Pogo_Pin_Connectors.jpg)
''Pogo pin'' or ''spring loaded'' connectors are commonly used in consumer and industrial products, where mechanical resilience and ease of use are priorities.
The connector consists of a barrel, a spring, and a plunger. They are in applications such as the
MagSafe
MagSafe is a series of proprietary magnetically attached power connectors developed by Apple Inc. for Mac laptops. MagSafe was introduced on January 10, 2006, in conjunction with the MacBook Pro, the first Intel-based Mac laptop, at the Ma ...
connector where a quick disconnect is desired for safety. Because they rely on spring pressure, not friction, they can be more durable and less damaging than traditional pin and socket design, leading to their use in
in-circuit test
In-circuit testing (ICT) is an example of white box testing where an electrical probe tests a populated printed circuit board (PCB), checking for shorts, opens, resistance, capacitance, and other basic quantities which will show whether the assemb ...
ing.
Crown spring connectors
![Crown Spring Render](https://upload.wikimedia.org/wikipedia/commons/2/2e/Crown_Spring_Render.png)
Crown spring connectors are commonly used for higher current flows and industrial applications. They have a high number of contact points, which provides a more electrically reliable connection than traditional pin and socket connectors.
Methods of connection
Whilst technically inaccurate, electrical connectors can be viewed as a type of adapter to convert between two connection methods, which are permanently connected at one end and (usually) detachable at the other end.
By definition, each end of this "adapter" has a different connection methode.g. the solder tabs on a male
phone connector, and the male phone connector itself.
In this example, the solder tabs connected to the cable represent the permanent connection, whilst the male connector portion interfaces with a female socket forming a detachable connection.
There are many ways of applying a connector to a cable or device. Some of these methods can be accomplished without specialized tools. Other methods, while requiring a special tool, can assemble connectors much faster and more reliably, and make repairs easier.
The number of times a connector can connect and disconnect with its counterpart while meeting all its specifications is termed as ''mating cycles'' and is an indirect measure of connector lifespan. The material used for connector contact, plating type and thickness is a major factor that determines the mating cycles.
Plug and socket connectors
Plug and socket connectors are usually made up of a male plug (typically pin contacts) and a female socket (typically receptacle contacts). Often, but not always, sockets are permanently fixed to a device as in a chassis connector , and plugs are attached to a cable.
Plugs generally have one or more pins or prongs that are inserted into openings in the mating socket. The connection between the mating metal parts must be sufficiently tight to make a good electrical connection and complete the circuit. An alternative type of plug and socket connection uses
hyperboloid contacts, which makes a more reliable electrical connection. When working with multi-pin connectors, it is helpful to have a
pinout
In electronics, a pinout (sometimes written "pin-out") is a cross-reference between the contacts, or ''pins'', of an electrical connector or electronic component, and their functions. "Pinout" now supersedes the term "basing diagram" that was the s ...
diagram to identify the wire or circuit node connected to each pin.
Some connector styles may combine pin and socket connection types in a single unit, referred to as a
hermaphroditic connector.
These connectors includes mating with both male and female aspects, involving complementary paired identical parts each containing both protrusions and indentations. These mating surfaces are mounted into identical fittings that freely mate with any other, without regard for gender (provided that the size and type match).
Sometimes both ends of a cable are terminated with the same gender of connector, as in many
Ethernet
Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
patch cables. In other applications the two ends are terminated differently, either with male and female of the same connector (as in an
extension cord
An extension cord (US), power extender, drop cord, or extension lead (UK) is a length of flexible electrical power cable (flex) with a plug on one end and one or more sockets on the other end (usually of the same type as the plug). The term usu ...
), or with incompatible connectors, which is sometimes called an ''
adapter
An adapter or adaptor is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one c ...
cable''.
Plugs and sockets are widely used in various connector systems including blade connectors,
breadboards,
XLR connector
The XLR connector is a type of electrical connector primarily used in professional audio, video, and stage lighting equipment. XLR connectors are cylindical in design, and have three to seven connector pins, and are often employed for analog b ...
s,
car power outlets,
banana connector
A banana connector (commonly banana plug for the male, banana socket or banana jack for the female) is a single-wire (one conductor) electrical connector used for joining wires to equipment. The term 4 mm connector is also used, especiall ...
s, and
phone connectors.
Jacks and plugs
![Jackplug](https://upload.wikimedia.org/wikipedia/commons/9/91/Jackplug.jpg)
A jack is a connector that installs on the surface of a bulkhead or enclosure, and mates with its reciprocal, the plug.
According to the
American Society of Mechanical Engineers,
the stationary (more fixed) connector of a pair is classified as a ''jack'' (denoted J), usually attached to a piece of equipment as in a chassis-mount or panel-mount connector. The movable (less fixed) connector is classified as a ''plug'' (denoted P),
designed to attach to a wire, cable or removable electrical assembly.
This convention is currently defined in ASME Y14.44-2008, which supersedes
IEEE 200-1975, which in turn derives from the long-withdrawn MIL-STD-16 (from the 1950s), highlighting the heritage of this connector naming convention.
IEEE 315-1975 works alongside ASME Y14.44-2008 to define jacks and plugs.
The term ''jack'' occurs in several related terms:
* The
registered jack
A registered jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier. Registration interfaces were first defined in the ...
or
modular jack in RJ11, RJ45 and other similar connectors used for
telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...
and
computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
ing
* The telephone jack of manual
telephone switchboard
A telephone switchboard was a device used to connect circuits of telephones to establish telephone calls between users or other switchboards, throughout the 20th century. The switchboard was an essential component of a manual telephone exchange, ...
s, which is the socket fitting the original
telephone plug
A telephone jack and a telephone plug are electrical connectors for connecting a telephone set or other telecommunications apparatus to the telephone wiring inside a building, establishing a connection to a telephone network. The plug is inserte ...
* The
phone jack common to many electronic applications in various configurations, sometimes referred to as a ''headphone jack''
* The
RCA jack
The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name ''RCA'' derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connectors male plug an ...
, also known as a ''phono jack'', common to consumer audiovisual electronics
* The
EIAJ jack for consumer appliances requiring a power supply of less than 18.0 volts
Crimp-on connectors
![Crimping tool 04](https://upload.wikimedia.org/wikipedia/commons/3/3e/Crimping_tool_04.jpg)
Crimped connectors are a type of solderless connection, using mechanical friction and uniform deformation to secure a connector to a pre-stripped wire (usually stranded).
Crimping is used in
splice connectors, crimped multipin plugs and sockets, and crimped coaxial connectors. Crimping usually requires a specialised crimping tool, but the connectors are quick and easy to install and are a common alternative to solder connections or insulation displacement connectors. Effective crimp connections deform the metal of the connector past its
yield point
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
so that the compressed wire causes
tension
Tension may refer to:
Science
* Psychological stress
* Tension (physics), a force related to the stretching of an object (the opposite of compression)
* Tension (geology), a stress which stretches rocks in two opposite directions
* Voltage or el ...
in the surrounding connector, and these forces counter each other to create a high degree of
static friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of t ...
. Due to the elastic element in crimped connections, they are highly resistant to
vibration
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic, such as the motion of a pendulum—or random, su ...
and
thermal shock
Thermal shock is a type of rapidly transient mechanical load.
By definition, it is a mechanical load caused by a rapid change of temperature of a certain point.
It can be also extended to the case of a thermal gradient, which makes different pa ...
.
Crimped contacts are permanent (i.e. the connectors and wire ends cannot be reused).
Crimped plug-and-socket connectors can be classified as ''rear release'' or ''front release''. This relates to the side of the connector where the pins are anchored:
* Front release contacts are released from the front (contact side) of the connector, and removed from the rear. The removal tool engages with the front portion of the contact and pushes it through to the back of the connector.
* Rear release contacts are released and removed from the rear (wire side) of the connector. The removal tool releases the contacts from the rear and pulls the contact out of the retainer.
Soldered connectors
Many plug and socket connectors are attached to a wire or cable by soldering conductors to electrodes on the back of the connector. Soldered joints in connectors are robust and reliable if executed correctly, but are usually slower to make than crimped connections.
When wires are to be soldered to the back of a connector, a
backshell is often used to protect the connection and add strain relief. Metal ''solder buckets'' or ''solder cups'' are provided, which consist of a cylindrical cavity that an installer fills with solder before inserting the wire.
When creating soldered connections, it is possible to melt the
dielectric
In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...
between pins or wires. This can cause problems because the thermal conductivity of metals causes heat to quickly distribute through the cable and connector, and when this heat melts plastic dielectric, it can cause
short circuit
A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circui ...
s or "flared" (conical) insulation.
Solder joints are also more prone to mechanical failure than crimped joints when subjected to vibration and compression.
Insulation-displacement connectors
Since stripping insulation from wires is time-consuming, many connectors intended for rapid assembly use insulation-displacement connectors which cut the insulation as the wire is inserted.
These generally take the form of a fork-shaped opening in the terminal, into which the insulated wire is pressed, which cut through the insulation to contact the conductor. To make these connections reliably on a production line, special tools accurately control the forces applied during assembly. On small scales, these tools tend to cost more than tools for crimped connections.
Insulation displacement connectors are usually used with small conductors for signal purposes and at low voltage. Power conductors carrying more than a few amperes are more reliably terminated with other means, though "hot tap" press-on connectors find some use in automotive applications for additions to existing wiring.
A common example is the multi-conductor flat ribbon cable used in computer disk drives; to terminate each of the many (approximately 40) wires individually would be slow and error-prone, but an insulation displacement connector can terminate all the wires in a single action. Another very common use is so-called
punch-down block
A punch-down block (also punchdown block, punch block, punchblock, quick-connect block and other variations) is a type of electrical connection often used in telephony. It is named because the solid copper wires are "punched down" into short open ...
s used for terminating
unshielded twisted pair
Twisted pair cabling is a type of wiring used for communications 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 ba ...
wiring.
![Bi-amp capable](https://upload.wikimedia.org/wikipedia/commons/5/5a/Bi-amp_capable.jpg)
Binding posts
Binding posts are a single-wire connection method, where stripped wire is screwed or clamped to a metal electrode. Such connectors are frequently used in
electronic test equipment
Electronic test equipment is used to create signals and capture responses from electronic devices under test (DUTs). In this way, the proper operation of the DUT can be proven or faults in the device can be traced. Use of electronic test equipmen ...
and audio. Many binding posts also accept a
banana plug
A banana connector (commonly banana plug for the male, banana socket or banana jack for the female) is a single-wire (one conductor) electrical connector used for joining wires to equipment. The term 4 mm connector is also used, especial ...
.
Screw terminals
Screw connections are frequently used for semi-permanent wiring and connections inside devices, due to their simple but reliable construction. The basic principle of all screw terminals involves the tip of a bolt clamping onto a stripped conductor. They can be used to join multiple conductors,
to connect wires to a
printed circuit board, or to terminate a cable into a plug or socket.
The clamping screw may act in the longitudinal axis (parallel to the wire) or the transverse axis (perpendicular to the wire), or both. Some disadvantages are that connecting wires is more difficult than simply plugging in a cable, and screw terminals are generally not very well protected from contact with persons or foreign conducting materials.
Terminal blocks (also called terminal ''boards'' or ''strips'') provide a convenient means of connecting
individual electrical wires without a splice or physically joining the ends. Since terminal blocks are readily available for a wide range of wire sizes and terminal quantity, they are one of the most flexible types of electrical connector available. One type of terminal block accepts wires that are prepared only by stripping a short length of
insulation
Insulation may refer to:
Thermal
* Thermal insulation, use of materials to reduce rates of heat transfer
** List of insulation materials
** Building insulation, thermal insulation added to buildings for comfort and energy efficiency
*** Insulated ...
from the end. Another type, often called ''barrier strips'', accepts wires that have ring or spade terminal ''lugs'' crimped onto the wires.
Printed circuit board (PCB) mounted screw terminals let individual wires connect to a PCB through leads soldered to the board.
Ring and spade connectors
The connectors in the top row of the image are known as ring terminals and spade terminals (sometimes called fork or split ring terminals). Electrical contact is made by the flat surface of the ring or spade, while mechanically they are attached by passing a screw or bolt through them. The spade terminal form factor facilitates connections since the screw or bolt can be left partially screwed in as the spade terminal is removed or attached. Their sizes can be determined by the
gauge
Gauge ( or ) may refer to:
Measurement
* Gauge (instrument), any of a variety of measuring instruments
* Gauge (firearms)
* Wire gauge, a measure of the size of a wire
** American wire gauge, a common measure of nonferrous wire diameter, ...
of the conducting wire, and the interior and exterior diameters.
In the case of insulated crimp connectors, the crimped area lies under an insulating sleeve through which the pressing force acts. During crimping, the extended end of this insulating sleeve is simultaneously pressed around the insulated area of the cable, creating strain relief. The insulating sleeve of insulated connectors has a color that indicates the wire's
cross-section area. Colors are standardized according to DIN 46245:
* Red for cross-section areas from 0.5 to 1 mm²
* Blue for cross-section areas from 1.5 to 2.5 mm²
* Yellow for cross-section areas over 4 to 6 mm²
Blade connectors
A blade connector is a type of single wire, plug-and-socket connection device using a flat conductive blade (plug) that is inserted into a receptacle. Wires are typically attached to male or female blade connector terminals by either
crimping or
soldering
Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...
. Insulated and uninsulated varieties are available. In some cases the blade is an integral manufactured part of a component (such as a switch or a speaker unit), and the reciprocal connector terminal is pushed onto the device's connector terminal.
Other connection methods
*
Crocodile (alligator) clips – conductive clamps used for temporary connections, e.g.
jumper cable
Jumper cables are electric cables to connect two rail or road vehicles.
Rail
Jumper cables are between the locomotive, the railroad cars and the cab car or the driving van trailer on push-pull trains for multiple-unit train control and the tr ...
s
*
Board to board connector Board-to-board (BTB) connectors are used to connect printed circuit boards (PCB), electronic components that contain a conductive pattern printed on the surface of the insulating base in an accurate and repeatable manner. Each terminal on a BTB conn ...
s – e.g.
card-edge connectors or
FPGA mezzanine connectors
*
Twist-on wire connector
Twist-on wire connectors are a type of electrical connector used to fasten two or more low-voltage (or extra-low-voltage) electrical conductors. They are widely used in North America and several European countries in residential, commercial ...
s (e.g. wire nuts) – used in
low-voltage In electrical engineering, low voltage is a relative term, the definition varying by context. Different definitions are used in electric power transmission and distribution, compared with electronics design. electrical safety codes define "low vol ...
power circuits for wires up to about 10 AWG
*
Wire wrapping – used in older circuit boards
See also
*
Adapter
An adapter or adaptor is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one c ...
*
Bent pin analysis
Bent pin analysis is a special kind of failure mode and effect analysis (FMEA) performed on electrical connectors, and by extension it can also be used for FMEA of interface wiring. This analysis is generally applicable to mission-critical and ...
*
Cable gland
A cable gland (more often known in the U.S. as a cord grip, cable strain relief, cable connector or cable fitting) is a device designed to attach and secure the end of an electrical cable to the equipment. A cable gland provides strain-relief a ...
*
Electrical contacts
An electrical contact is an electrical circuit component found in electrical switches, relays, connectors and circuit breakers. Each contact is a piece of electrically conductive material, typically metal. When a pair of contacts touch, they c ...
*
Electrical network
An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources ...
*
Electrical splice
In telecommunications, a line splice is a method of connecting electrical cables (electrical splice) or optical fibers (optical splice).
Splices are often housed in sleeves to protect against external influences.
Splicing of copper wires
...
*
Electrical termination
In electronics, electrical termination is the practice of ending a transmission line with a device that matches the characteristic impedance of the line. Termination prevents signals from reflecting off the end of the transmission line. Reflect ...
*
Gender of connectors and fasteners
*
InCa3D
*
Lightbulb socket
A lightbulb socket, lightbulb holder, light socket, lamp socket or lamp holder is a device which mechanically supports and provides electrical connections for a compatible electric lamp base. Sockets allow lamps to be safely and conveniently re ...
*
Pothead
A pothead is a type of insulated electrical terminal used for transitioning between overhead line and underground high-voltage cable or for connecting overhead wiring to equipment like transformers. Its name comes from the process of potting o ...
for a termination on a high voltage electric power cable
*
Tee connector
A tee connector is an electrical connector that connects three cables together. It is usually in the shape of a capital T. It is usually used for coax cables and the three connector points can be either female or male gender, and could be differen ...
*
Tube socket
Tube sockets are electrical sockets into which vacuum tubes (electronic valves) can be plugged, holding them in place and providing terminals, which can be soldered into the circuit, for each of the pins. Sockets are designed to allow tubes to b ...
*
Wire nut
Twist-on wire connectors are a type of electrical connector used to fasten two or more low-voltage (or extra-low-voltage) electrical conductors. They are widely used in North America and several European countries in residential, commercial ...
Connectors
*
AC power plugs and sockets
AC power plugs and sockets connect electric equipment to the alternating current (AC) mains electricity power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and electric current, current ...
*
Audio and video connector
Audio connectors and video connectors are electrical or optical connectors for carrying audio or video signals. Audio interfaces or video interfaces define physical parameters and interpretation of signals. For digital audio and digital vide ...
*
Banana connector
A banana connector (commonly banana plug for the male, banana socket or banana jack for the female) is a single-wire (one conductor) electrical connector used for joining wires to equipment. The term 4 mm connector is also used, especiall ...
*
Battery holder
A battery holder is one or more compartments or chambers for holding a battery. For dry cells, the holder must also make electrical contact with the battery terminals. For wet cells, cables are often connected to the battery terminals, as is ...
*
Battery terminals
Battery terminals are the electrical contacts used to connect a load or charger to a single cell or multiple-cell battery. These terminals have a wide variety of designs, sizes, and features that are often not well documented.
Automotive ba ...
*
Coaxial power connector
A coaxial power connector is an electrical power connector used for attaching extra-low voltage devices such as consumer electronics to external electricity. Also known as barrel connectors, concentric barrel connectors or tip connectors, these ...
*
Computer port (hardware)
In computer hardware, a port serves as an interface between the computer and other computers or peripheral devices. In computer terms, a port generally refers to the part of a computing device available for connection to peripherals such as in ...
*
Crocodile clip
Alligator clip
A crocodile clip or alligator clip is a plier-like spring-tensioned metal clip with elongated, serrated jaws that is used for creating a temporary electrical connection. This simple mechanical device gets its name from the re ...
*
DC connector
A DC connector (or DC plug, for one common type of connector) is an electrical connector for supplying direct current (DC) power.
Compared to domestic AC power plugs and sockets, DC connectors have many more standard types that are not intercha ...
*
DIN connector
The DIN connector is an electrical connector that was standardized by the ' (DIN), the German Institute for Standards, in the early 1970s. The male DIN connectors (plugs) feature a 13.2 mm diameter metal shield with a notch that limits the ...
*
Dock connector
A dock connector is a connector used to attach a mobile electronic device simultaneously to multiple external resources. The dock connector will typically carry a variety of signals and power, through a single connector, to simplify the process o ...
*
D-sub connectors
*
Edge connector
An edge connector is the portion of a printed circuit board (PCB) consisting of traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a sin ...
*
Elastomeric connector
Elastomeric connectors, also known by the registered trademark ZEBRA connectors, consist of alternating conductive and insulating regions in a rubber or elastomer matrix to produce overall anisotropic conductive properties. The original version co ...
*
IEC appliance couplers (IEC 60320)
*
JST connector
JST connectors are electrical connectors manufactured to the design standards originally developed by J.S.T. Mfg. Co. (Japan Solderless Terminal). JST manufactures numerous series (families) and pitches (pin-to-pin distance) of connectors.
JST c ...
*
Mini-DIN connector
The mini-DIN connectors are a family of multi-pin electrical connectors used in a variety of applications. Mini-DIN is similar to the larger, older DIN connector.
Design
Mini-DIN connectors are in diameter and come in seven patterns, wi ...
*
Optical fiber connector
An optical fiber connector joins optical fibers, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass. Better connectors lose very little light due ...
*
Phone connector (audio)
A phone connector, also known as phone jack, audio jack, headphone jack or jack plug, is a family of electrical connectors typically used for analog audio signals. A plug, the male connector, is inserted into the jack, the female connect ...
*
Pin header
A pin header (or simply header) is a form of electrical connector. A male pin header consists of one or more rows of metal pins molded into a plastic base, often apart, though available in many spacings. Male pin headers are cost-effective du ...
*
RCA connector
The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name ''RCA'' derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connectors male plug an ...
*
RJ-XX connector
*
Flexible electronics
Flexible electronics, also known as ''flex circuits'', is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additi ...
References
;General
* Foreman, Chris, "Sound System Design", ''Handbook for Sound Engineers'', Third Edition, Glen M. Ballou, Ed., Elsevier Inc., 2002, pp. 1171–72.
External links
{{DEFAULTSORT:Electrical Connector