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Definitions for jargon, scientific terms and phrases used at Harwin and across the connector and electronics industries.

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3D Models
4-finger Contact

A style of Beryllium Copper contact used on the Datamate and M300 ranges from Harwin. The contact is a formed clip, with 4 downward-oriented fingers that will make contact with the mating circular pin. Because of the 4 points of contact, these clips perform very well under vibration: no matter which direction the pin moves, there is always a clip finger maintaining contact.

Airflow Path

To assist with cooling, PCB designers may need to look at how free or forced air (by a fan) will travel around the layout of the PCB. It might be necessary to move taller or bigger objects around in case they obstruct the flow of the air and diminish the effectiveness of the air cooling.

Alignment Features

In order to make sure that connectors mate successfully, they first need to be aligned to each other. To assist with getting the connectors successfully mated, additional features can be designed onto one or both sides of the connector halves. These can include oversize chamfers, pegs or posts, or even separate posts mounted on the PCB that line up with a hole in the mating PCB.

Alignment Posts

Normally long posts that extend past the mating face of a connector, they are additional housing features. They can be either metal or plastic, do not carry current, and mate with plain holes in the mating connector. These help line up the two mating connectors before the contacts touch, helping to avoid misalignment and potential damage to the contacts. They can also assist with blind mating.

Alternating Current (AC)

An electric current whose electrons periodically reverse their flow. The most common form of AC alternates in a sine wave.


The base SI unit of electric current (symbol A), defined as "that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2×10−7 newtons per meter of length."

The ampere is often shortened to "amp" (as in "Current rating of 3 amps"). It is named after André-Marie Ampère (1775–1836), a French mathematician and physicist, who is considered to be the father of electrodynamics. Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current; this force is used in the formal definition of the ampere.

As this is not a feasible measurement to reproduce, the ampere standard is practically realized through its relationship to the Volt (voltage) and the Ohm (resistance), as both of these can be tied to physical phenomena that are relatively easy to reproduce.

Analog signal (Analogue)

A continuous electrical signal current that can vary by any amount - compared to digital, which can only operate at discrete defined values. In practice, all signals are analog, but degradation or noise is easier to spot in digital signals as it will show up as any deviation from the expected values, and the signal can be corrected back to the digital value. Analog signals will always contain noise, which accumulates along the signal path, and which cannot be distinguished from the original signal. Shielding can be utilized to help prevent noise (caused by interference), but there is no reliable method to restore the signal loss.


A 1.27mm pitch (0.05" or half-pitch) PCB connector system from Harwin based on simple pin header and socket styles. Part numbers all start with either M50 or M52. The connectors are available in Board-to-Board or Cable-To-Board styles, and are generally suited for static equipment and consumer electronics. See also Archer Kontrol.

Archer Kontrol

A 1.27mm pitch (0.05" or half-pitch) PCB connector system from Harwin. Part numbers all start with M55. The connectors are available in Board-to-Board with a choice of vertical or horizontal orientation on both male and female connectors. Variable mating heights are also possible, up to 20mm. The range has improved functionality over the basic Archer ranges, and includes polarization, shrouding and location pegs on all connectors.


A quality management system similar to ISO 9001, but with additional requirements and an emphasis on continuous improvement. Originally designed for the Aerospace market, it is becoming recognized in other markets and within the component supply chain. The version was updated from C to D in 2017, and further work and audits must be completed for companies wishing to upgrade their certification to the new version. EN 9100 is the international version, and effectively identical. Information on Harwin's AS9100 certification can be found on the Quality page.

Automated Optical Inspection (AOI)

An additional automated process that can be added to the end of a solder process (or other manufacturing processes). The setup consists of a camera and a PC. The camera takes an image of the part that needs inspection, and the PC compares this image to a bank of acceptable images or other criteria. Using these criteria, the PC can then confirm if the assembly passes inspection. Much faster and more repeatable / less prone to interpretation than manual inspection.


Any procedure that is carried out solely or with the assistance of machinery that follows a program, rather than needing an operator to operate a control for every function.


The application of an epoxy resin or similar compound to the rear of a connector (normally a cable connector). This resin barrier assists with strain relief and sealing. A connector designed for backpotting will have an additional wall on the rear edge of the housing, to contain the liquid epoxy while it sets to solid. Harwin's blog article on backpotting gives more in-depth information on usage, materials and processes.


An accessory item that fits onto the rear of a cable-mounted connector, to protect the rear of the connector from physical knocks and gives a larger connector area to help with unmating by hand. May also add strain relief to the cables (for when the cable connector is unmated by pulling on the cables). Depending on the design, can also add sealing to the rear of a connector. Also known as hoods.

Bend Radius

The minimum radius (defined by the manufacturer) at which a cable can be bent. To bend at a smaller radius risks damage to the cable, or will pull the insulation away from the end of the conductive core. The more flexible the cable, the smaller a radius possible. This will be determined by the size of the core, and the material and thickness of the insulation. Temperature extremes may also need to be considered.

Bill of Materials (BoM)

A complete list of all the components of a product to be manufactured. Each item should also list (as a minimum) the quantity or volume/length/weight required. The BoM can also include suppliers or manufacturers and their associated part numbers for purchased sub-items, packaging, relevant instructions or work procedures.

Blanked Pin

A form of polarization or keying. In the female half, instead of a receptacle with a hole in the center, it will be a solid contact (the blanked pin). On the other half, the male pin is removed. If the blanked pin is mated with a location where the male pin is still present, the connectors cannot be mated.

Blind Mating

The action of mating two connectors without being able to see the mating. This makes mating successfully and without damage more difficult, as misalignment is more likely. Connectors can have features that help with blind mating, such as alignment posts or large entry chamfers.

Board Level Shielding (BLS)

Shielding specifically designed to be mounted to the PCB to cover certain elements. The shield would act as 5 sides of a box - the PCB would need to also have an inbuilt grounding plane within or on the underside, which then completes the box and finishes the Faraday cage. See also Shield Cans. Harwin offers a range of BLS products.


A particular arrangement of mating connectors that are both mounted to PCBs - thus a connection is made directly from one board to another.


A profiled form of heatshrink, often used over the rear of a cable connector and the start of the cable, to seal off the vulnerable area and help with strain relief. The boots are profiled as often the cable will be much smaller than the rear of the connector - normal heatshrink (all the same diameter) may not shrink far enough to enclose the cable if it is large enough to enclose the connector.


A length of conducting element (often Copper) or a number of strands twisted together, covered with an insulating material (such as PTFE or PVC). Typically available on reels, suitable to be cut to length for any application. Can also have multiple bundles of cables bound together with another layer of insulation (multicore cable), or have a braided woven jacket of very fine wire covered by a further layer of insulation (coax cable).

Cable Assembly

A construction consisting of one or more connectors attached to a cable.

Cable Bundle

A collection of cables bound together, or a collection of cable assemblies bound together to form a more complex harness or loom. The binding is typically required to lower the amount of wear due to movement, or prevent the cables from touching other parts of the equipment.

Cable Harness
Cable Loom
Cable Management

The use of mechanical holding devices to hold the cables of a cable assembly stationary. Typically this is either against a cabinet wall or chassis member, or against the PCB, or the bundle itself is made very stiff and unmoving. Cable management is generally good practice to prevent wear, burning or shorts, by stopping the cables from: moving around under vibration or shock; touching other elements that could cause damage (or be damaged themselves); causing weight re-distribution with larger cables.

Cable Routing

The design showing the path that a completed cable assembly will take through the equipment. This may be done onsite, or in advance, depending on the industry. Cable management needs to be considered in the design, to ensure the cable is secured where relevant, and avoids key problem areas. Bend radiuses and strain relief are also key considerations.


A particular arrangement of mating connectors, one of which is mounted to a PCB, the other is mounted to cable.


A particular arrangement of mating connectors, both connector halves being mounted to cables.

CAD Models

Files that contain code to construct a 3D virtual model of a product within a Computer Aided Design program. Some manufacturers supply CAD Models for customers to use, that they can feed into their own design - these transferable models are usually supplied in standard formats such as STEP or IGES, which many CAD systems can accept. Register or Login for access to Harwin's CAD Models.

Capacitive Coupling

The transfer of energy within a circuit or network by means of displacement current between circuit nodes, induced by the electric field.


A closed loop of electron flow, defined and contained by various electronic devices and conductive elements connecting the devices. Can also refer to the equivalent in an optoelectronic device.

Coax cable, Coaxial cable

A cable constructed with an inner conducting element (which carries the signal current or data), with a layer of insulation, then a braided woven metal jacket or similar conductive element (for shielding purposes), then a final second layer of insulation. Used when the signal being passed through the inner conductor may be particularly susceptible to interference, such as audio or video signals.

Commercial Off-The-Shelf

Goods, materials, components and services that do not need to be commissioned as custom-made or bespoke. When used specifically in the connector industry, normally refers to connectors with a higher specification level that would be suitable for use on aviation, space or defense applications without modification.

Computer Aided Design

Software specifically developed for producing designs of any product or component. The most common CAD types in electronics are 1) for component design, which allows you to model any item in 3D space and run analysis on its features, or 2) PCB design, which has specific inbuilt features designed to help with this complicated task, such as track layout automation. Either CAD system can often import models from accepted standard formats, and output machine-readable data that can be directly used by production equipment.

Conducting Element, Conductor

A single piece of suitable material that will carry the electrical current along its length. Typically metal, the conductor may be the central wire or stranded cable in an insulated cable, a connector male or female contact, a connection point or test point mounted to a PCB, a track printed onto a PCB, or even a shielding element.

Conductive Coupling

Also known as direct coupling or DC coupling. Electrical energy is transferred through physical contact between two conductive elements, via a third conductive medium.

Conflict Minerals

Certain mineral substances that are mined in areas of conflict, where unauthorized mining and selling of the mineral may be contributing finances to the forces involved in the conflict. Currently these are listed as Tin, Tantalum, Tungsten and Gold (colloquially known as 3TG after their initials). the current main areas of concern are in the eastern region of the Democratic Republic of Congo, along with the nine neighboring countries. See also Dodd-Frank. Harwin have a support article on Conflict Minerals.


An electrical product capable of transferring (without altering) electrical current from one device to another. Typically consists of one of more conducting element (normally metal), and may also be electrically insulated with a housing (commonly plastic). Connectors often consist of two mating halves, which can be connected and disconnected as required, either during manufacture or operation. Also known as interconnect devices. Can also refer to an equivalent device in a fiber-optic circuit, where the "conducting element" would be suitable for passing the light from one device or cable to another.

Contact Pad

A flat conductive element, made from a flat piece of metal with no additional features. Normally used to mate with a spring contact or spring pin.

Continuity Test

Testing carried out on completed cable assemblies or PCBs to ensure that the ends of a circuit are correctly connected, and maintain a steady current with no fluctuation.


When current flows within a device or circuit, the resistance within each material causes the temperature of that material to rise. In a compact piece of equipment, with many elements, this temperature rise could be detrimental to the circuit and specific heat-sensitive components - or could even lead to a fire hazard. Certain elements can be added to the equipment to provide a way to cool down these elements, or the surrounding air. There is a choice of active cooling (fans and refrigeration pipes) or passive cooling (aluminium heat sinks). The choice depends on the space available and the severity of the problem.


Elemental substance: symbol Cu, atomic number 29. A soft, malleable, and ductile reddish-orange metal with very high thermal and electrical conductivity; one of the few metals that occur in nature in directly usable metallic form as opposed to requiring extraction from ore. Its conductivity, workability and relatively wide availability has made it the conducting material of choice in the electronics industry. Depending on the application, may be used in alloy form to improve strength, wear and spring force characteristics, or plated to also improve wear and prevent corrosion.


An alternative term used for the conducting element in a cable. Can be either solid (one single wire of metal) or stranded (multiple wires twisted together). These two types give different performances for flexibility and strength.


A method of attaching a cable to a contact, that involves deformation of an area of the contact. The cable end is stripped to reveal the bare core, and is placed in the crimping area of the contact. A specific tool (with jaws or holder designed to suit the contact) is then used to deform this area of the contact, such that a compressed metal-to-metal joint is made that is both mechanically secure and electrically sound. Crimping instructions for any crimp contact should include a pull-off force rating.


When two conductive elements are near each other, the current in one element can cause a current to flow (or interfere with an existing current) in the other element. It is usually caused by undesired capacitive, inductive, or conductive coupling from one circuit or channel to another. The effect is detrimental to signal integrity, and various methods can be employed to keep crosstalk to a minimum.


A small form-factor type of NEO (Near Earth Orbit) satellite. Based on a 10x10x10cm cube (although the final satellite can be multiple cubes), each cube is no more than 1.33kg, and often uses COTS (Commercial Off-The-Shelf) components. Often deployed from either the International Space Station, or as secondary payloads on a launch vehicle. Popular with academia due to the lower cost and availability of COTS components.


The movement of electrons (or positive ions, negative ions or holes) which is observed as an electrical flow of charge. The SI unit of current is the ampere.


A 2.00mm pitch high-reliability connector range designed and manufactured by Harwin, low-profile and compact, available in 1, 2 or 3 row formats. Available in Board-to-Board, Cable-to-Board and Cable-to-Cable configurations. Options include with latches or with jackscrews. See also Datamate J-Tek, Datamate Mix-Tek, Datamate Power, Datamate Coax and Datamate L-Tek, and our blogpost on "What is Datamate?".

Datamate Coax

A 4.00mm pitch high-reliability connector range designed and manufactured by Harwin. This sub-range of the Datamate family is based on the Datamate Mix-Tek connector system, but uses simply coax contacts in a single row format. Jackscrews are located at either end of the connector housings. See also our blogpost on "What is Datamate?".

Datamate J-Tek

A 2.00mm pitch high-reliability connector range designed and manufactured by Harwin. This sub-range of the Datamate family is in double or triple row formats, with jackscrews located at either end of the connector housings. Available in Board-to-Board, Cable-to-Board and Cable-to-Cable configurations. See also our blogpost on "What is Datamate?".

Datamate L-Tek

A 2.00mm pitch high-reliability connector range designed and manufactured by Harwin. This sub-range of the Datamate family is in single or double row formats, with Beryllium Copper latches located at either end of the connector housings. Available in Board-to-Board, Cable-to-Board and Cable-to-Cable configurations. See also our blogpost on "What is Datamate?".

Datamate Mix-Tek

A 2.00mm pitch high-reliability connector range designed and manufactured by Harwin. This sub-range of the Datamate family is based on the double row format of Datamate J-Tek, with jackscrews located at either end of the connector housings. The contacts are a mixture of signal (in double row) and power or coax (or both) in single row - each special contact (power or coax) takes up the same space as 4 signal contacts. Available off-the-shelf in Cable-to-Board format, with Board-to-Board and Cable-to-Cable configurations available made-to-order. See also our blogpost on "What is Datamate?".

Datamate Power

A 4.00mm pitch high-reliability connector range designed and manufactured by Harwin. This sub-range of the Datamate family is based on the Datamate Mix-Tek connector system, but uses simply power contacts (either 20A max or 40A max) in a single row format. Jackscrews are located at either end of the connector housings. See also our blogpost on "What is Datamate?".


A document with some technical content that normally shows the physical dimensions of a product, and may also include specification information, usage information, general product data, etc. There is no set standard that defines the contents of a datasheet, and this will vary across manufacturers. Harwin use the Technical Drawing as the Datasheet, as we include all the relevant dimensions, and a summary of the specification. Datasheets are available from individual product pages.

Digital signal

A discrete signal for which both time and amplitude have discrete, defined values. Any drift from these values (such as from interference/noise) can be detected and corrected. This is in comparison to analog signals, where interference or noise are difficult to detect and remove.

Direct Current (DC)

An electric current whose electrons flow in only one direction.


A broken (temporary or permanent) connection, such that current is interrupted and unable to flow at that point. Used as a pass criteria for various physical tests (such as vibration).


The Dodd-Frank Wall Street Reform and Consumer Protection Act of 2009 introduced changes to the yearly financial reporting that certain USA companies submit to the SEC (Securities Exchange Commission). The changes included a requirement (Section 1502) to declare on whether their products were conflict-free, i.e. did not use any of the four Conflict Minerals (Tin, Tantalum, Tungsten and Gold) from a conflict source.


See Ground

Electromagnetic Compatibility (EMC)

The correct operation of different equipment in a common electromagnetic environment, where interference may be an issue. Often controlled by standards in many countries, and covers both EMI and RFI effects.

Electromagnetic Interference (EMI)

Any undesirable disturbance in a current-carrying element caused by the external influence of an electric or magnetic field. It can cause a loss of signal integrity, potentially to the point of total disruption. It can come from both natural and man-made sources. Prevention is usually by some form of shielding to form a Faraday cage effect - by Board Level Shielding, braiding (as seen on coax cables), or total enclosure of a complete system in a metal shell. See also Electromagnetic Compatibility.

Electronic Connector

See Connector


Devices and systems involving the flow of electrons through electrical circuits, to control and modify the electron flow that enables electronic devices to function. Includes active components such as vacuum tubes, transistors, diodes, integrated circuits, optoelectronics, and sensors; passive components such as capacitors, resistors and inductors; and interconnect devices.


A subatomic particle, one of the fundamental particles of physics. Electrons orbit the nucleus of every atom. They have a negative charge (defined as one negative elementary charge), of the same magnitude but opposite charge to a proton (which is positively charged). However, its mass is only 1/1840 that of a proton. Electrons exhibit both wave and particle characteristics. The movement of electrons through a material or vacuum creates an electric current.

EN 9100

See AS9100


Also referred to by the acronym EOL. A product is said to be in the EOL phase if it is a) obsolete, but stock is still available, b) a Last Time Buy period has been announced and the product is therefore about to go obsolete, or c) firm plans are in place to declare the item as obsolete.

Epoxy Resin

A type of thermoset polymer that, when fully cured, forms a strong barrier or bond. These resins typically require either a catalyst or a co-reagent to commence the hardening or curing process to form a solid (they are supplied in liquid form). Most familiar to the consumer in two-part adhesives (such as Araldite®), these resins are also available as sealants and strong bonding materials, used for backpotting cable connectors.

Equipment Wire

See Cable

Evaluation Samples

Manufacturers may offer samples for customers to have a visual look at the product, which help with the total evaluation of whether the product is suitable for the required function. Customers should be aware that these samples may not have been manufactured using production tooling, or may have been stored in sub-optimal conditions. Therefore, for later prototyping and for any full-scale manufacturing, production items should be acquired, not evaluation samples. Evaluation samples are available from Harwin for many ranges on request.

Flame Retardant

An additive to plastics, rubbers or other compounds that makes the original substance less prone to burning, or reduces the flame height or likelihood it is self-sustaining.


A 1.25mm pitch high-reliability connector range designed and manufactured by Harwin, low-profile and compact with a double-row rectangular layout. Available in Board-to-Board, Cable-to-Board and Cable-to-Cable configurations. Options include with latches or with Screw-Loks.

Gecko-SL (Gecko Screw-Lok)

A development of the Gecko 1.25mm pitch high-reliability connector range designed and manufactured by Harwin that uses small jackscrews (called Screw-Lok) to affix the connectors together (to ensure the shock and vibration requirements are met).


Also known as Earth. Either a direct, physical connection to the earth itself, or a reference point on a circuit from which voltage is measured. The physical connection to earth provides a route to overload or leak excess current or interference current away from the circuit. This is called an Earth Return, and helps prevent static build-up, overloads or dangerous currents. The Earth is so enormous that it can absorb an unlimited amount of current without changing its potential (which is effectively zero).

Ground Connection

The physical path from the connection to Ground or Earth.

Ground Plane

A conductive surface, ideally connected to Ground. However, in portable devices, this is not actually connected to a physical earth, and the term should more strictly speaking refer to a "common". This would be a reference plane from which all voltages in the equipment is measured.

Half Pitch

1.27mm (0.05") pitch. So-called because it was developed to be half the pitch of a 2.54mm (0.1") pitch connector, which was a very common and popular size.


A declaration that states that the plastic has no Halogen compounds (normally Chlorine or Bromine) as part of its composition. Chlorine and Bromine are used in various Flame Retardants, and are not uncommon in many plastics used in electronics.

Heat Sink

A passive cooling device designed to sit above a source of heat in a circuit, that vastly maximizes the amount of surface to dissipate heat. Typically aluminium (which is a good conductor of heat), with many channels and vanes machined into a block. Most engineers will be familiar with the heat sinks in personal computers that are mounted on top of the main processing IC.


A type of rubber tubing that contracts when heat is applied. Can be used for covering exposed conductors or cable joints, for keeping multiple cables bundled together, or just for labelling/identification purposes. Also available in profiled shapes, known as boots.

High Density Connector

A connector that includes a higher number of contacts in a set space. There is no exact definition for the number of contacts with a space that makes it high density - different manufacturers will use the term differently, partly depending on their existing range. For instance, a manufacturer selling connectors with pitches from 10mm down to 3mm might call the 3mm high density - but for a manufacturer selling from 2.54mm down to 0.5mm, the 1mm might be high density.

High Speed Connector

Connectors designed to handle high data-rates of multiple gigahertz (GHz). May also include dedicated ground planes or power planes. There is no set definition for this term, any manufacturer can use it if their product is proven to perform at high data-rates.

High-Reliability Connector

Connectors built to withstand high performance levels of vibration, shock and operating temperature range (and other robust or durable requirements). Generally specified in markets such as Aerospace, Defense, Motorsport, and high-end Industrial.

Holding Force

The amount of force that would need to be exceeded to separate two mated contacts or connectors. This force does not include anything contributed by mechanical fixings - it is purely to overcome the spring forces keeping the connection point mated. Is also referred to as Withdrawal Force - although some specifications may quote both, often there is very little difference.


A connector orientation - the mating face of the connector is at 90 degrees or right angles to the PCB where the connector is mounted. Called Horizontal because the housing lies horizontally flat along the PCB.

Hot-Pluggable, Hot-Swappable

Connectors specially designed for hot-pluggable applications generally have the four corner ground pins longer than the rest, to ensure ground connection is made before any live electrical connections are mated. See Sequencing.


The amount of water vapor in the air. Connectors and other electrical devices normally have a humidity resistance rating, which is defined as a maximum amount of time in a certain relative humidity percentage in which the device has been tested to still perform to its operating parameters.


Acronym for Insulation Displacement Connector. A type of connector compatible for use with ribbon cable. The connector has a row of sharp contact points, that pierce the insulation either side of each ribbon cable conductor. The conductor is forced down to bottom-out on the contact between the two points, compressing the conductor onto the inside faces of the contact for a good electrical joint. Typically the connector is designed with a separate cover that snaps over the ribbon cable to keep it in place in the field.

IGES Files

A file format for exchange of 3D virtual models across different makes of Computer Aided Design programs. IGES is an acronym for Initial Graphics Exchange Specification (IGES) (pronounced eye-jess). Originally developed by the United States Air Force, the file format was last updated in 1996, after the STEP File format became popular, but is still widely used today. Files are given the extension .iges or .igs.


The measure of opposition to a current when voltage is applied. Similar to resistance, but impedance has both magnitude and phase, and therefore applies to AC circuits. A DC circuit would have no distinction between impedance and resistance. The SI unit of impedance is the Ohm (Ω).


The production of an electromotive force (voltage) in a conductor by using a changing magnetic field. The magnetic field can itself be produced by current in a separate conductor.

Inductive Coupling

Two conducting elements are inductively coupled if the change in current through one wire induces a change in current in the other, by means of induction. It can be intentional (and therefore required) or unintentional (and therefore not desirable).

Insertion Force

The amount of force required to fully engage two mating contacts or connectors. This force does not include anything contributed by mechanical fixings - it is purely to overcome the spring forces that will make the mated pair pass electricity. This force is normally quoted in specifications as being a maximum force requirement, but may also have a minimum.

Insulation Displacement Connector


Insulation, Insulating Material

A material having a very low conductivity. Often a plastic material but can also be rubber, PTFE, PVC, etc. where flexibility is required (such as a cable insulator). When placed around a conductor, it prevents the electric current being passed from the conducting element to other nearby conducting elements or conductive materials (such as a metal enclosure). When used on a connector, usually doubles up as the main structure of the connector - holding the contacts in the right place, adding polarization and alignment features, etc.


That part of a connector, cable or other device made from an insulating material that provides the insulation between contacts or other conducting materials.

Interconnect Device

See Connector


Association Connecting Electronics Industries (formerly the Institute for Printed Circuits).


Standard "IPC/WHMA-A-620: Acceptability of Electronic Wire Harnesses and Cables" is widely used across multiple industries as the de-facto method of manufacturing and inspecting cable assemblies. From the WHMA website "The IPC/WHMA-A-620 standard prescribes practices and requirements for the manufacture of cable, wire and harness assemblies. The standard describes materials, methods, tests and acceptability criteria for producing crimped, mechanically secured and soldered interconnections, and the related assembly activities (corresponding lacing/restraining criteria) associated with cable and harness assemblies. Any method that produces an assembly conforming to the acceptability requirements described in this standard may be used."

ISO 9001

Part of the collection of ISO 9000 international standards that encourage the use of quality management systems. ISO 9001 details the specific requirements that organisations must fulfil, and will be assessed against. To be certified to ISO 9001, a company must develop the quality management system in line with the standard, then pass a number of audits by one of the authorized accreditation bodies. Further audits will be carried out on a regular schedule to continue to keep the certification.


A mechanical connection system that allows two mating halves to be screwed together by means of an additional mechanical fixing or fixings integrated into the connector housings. One half will have an external thread, the other an internal thread. Depending on the design, the parts may be mated before the jackscrews need to be engaged (Mate-Before-Lock), or the engaging of the jackscrews will pull (or 'jack') the mating halves together.


A style of cable management, traditionally used in telecoms, naval and aerospace applications, that uses a thin cord (often waxed linen) to tie the cables together and bind them tightly along the routing length. The advantage of the lacing method is that there are no obstructions such as those created by plastic cable ties. However, the method is much more complicated and requires some training and practice.

Land Pattern
Last Time Buy

When a product is made obsolete, the manufacturer may choose to grant a Last Time Buy period. This gives customers a fixed date, before which orders will still be accepted. However, MOQs or lead-times may increase during this period, as the manufacturer wants to make sure that any last manufacturing batch does not lead to an excess of inventory and can group final production runs in the most efficient manner possible.


A form of mechanical fixing that is attached to one mating half of a connector pair, and will snap or lock around a feature on the other connector housing. Can be either locking (requires manual intervention directly on the latch to unmate from the mating half) or friction (just adds some additional force to the total withdrawal force between the two connectors, but they can still be pulled apart).


The amount of time required to process an order through production, from order acknowledgement to shipment of the order. The time includes not just the amount of production time required, but also has to consider the capacity of the affected production lines, and the amount of other orders scheduled before this order.


A 2.54mm pitch (0.1") PCB connector system from Harwin based on simple pin header and socket styles. Part numbers all start with M20. The connectors are available in Board-to-Board or Cable-To-Board styles, and are generally suited for static equipment and consumer electronics.


A 2.00mm pitch (0.079") PCB connector system from Harwin based on simple pin header and socket styles. Part numbers all start with M22. The connectors are available in Board-to-Board or Cable-To-Board styles, and are generally suited for static equipment and consumer electronics.


A 3.00mm pitch high-reliability connector range designed and manufactured by Harwin. This selection of power connectors will handle up to 10A per contact, and is available in 3-contact (single row), 6 or 10-contact (double row). Jackscrews are located at either end of the connector housings. Available in Board-to-Board, Cable-to-Board and Cable-to-Cable configurations.


On an electrical switch or relay, on mating the new connection is engaged before the previous connection is broken, so the center contact is momentarily connected to both contacts. This can also be referred to as "First-To-Make" or "First Mate Last Break (FMLB)".


A style of Jackscrew or Screw-Lok that enables the connectors to be mated before the screws need to be engaged. Easier to use that jackscrews that "jack" together connectors, as you can fully screw down one side before starting on the other side. See the Mate-Before-Lock blog article for more information.


The act of plugging together two connectors so that current can flow across the connection. Sometimes called coupling. The reverse action of separation can be called unmating, de-mating, uncoupling or other variants of these. See also Mating Cycles.

Mating Cycles

The minimum number of times that a connector pair can be mated and unmated, and that their electrical and mechanical performance will still be maintained. Mating cycles will be defined for connectors, because continued mating and unmating will have various physical effects that will eventually affect performance. These include wear on the mating surface and permanent set on the spring contacts.

Mating Height

Used specifically for Board-to-Board connectors that connect in a parallel or mezzanine configuration (the two boards are parallel to each other, one above the other). Both connectors are vertical connectors (the mating face is vertically above the tails/leads). The mating height is the distance between the two PCBs, specifically between the two surfaces of the PCBs that face each other.

Mechanical Fixing

A separate part of a connector that does not carry current, but is purely to give a robust connection to either the PCB or the mating connector (or both). These fixings will give additional strength in addition to solder joints or the holding force of the mated connectors, which is important or even crucial in a connection subject to mechanical stress.

Mechanical Stress

Any action that causes physical wear or strain on a device or connection. This can include mating actions, vibration and shock, friction against other system elements, or induced stresses as an item warms or cools.

Metal Backshells

A type of backshell that is manufactured from metal in order to also give shielding to the connector. Depending on the design, the cable exit may also be designed to accept an external metal braid being connected, by means of a tie-band or similar. This would then give a completely shielded cable assembly when fully assembled.

Minimum Line Value

The minimum sales value of a specific product that a manufacturer will accept on one order. Also referred to by the acronym MLV. This is to ensure that manufacturers are keeping to sound economic rules and not spending more on shipping than on the potential profit of an order.

Minimum Order Quantity

The minimum amount of a specific product that a manufacturer will accept on one order. Also referred to by the acronym MOQ. A company will set an MOQ on non-stocked items to ensure that any order placed for these items makes economic sense to manufacture.


The failed attempt at mating two connector halves. In the best case, it means the user must simply try again. However, depending on the connector design, it may also be possible to temporarily or permanently damage the connector - which in the worst case would mean the two halves can no longer be engaged together.


A particular form of mis-mating, where the connectors are mostly lined up, but a bit out in one direction. Certain connectors will have systems that accommodate a certain amount of misalignment, such as large chamfers on the mating faces, alignment posts, or spring loaded contacts that mate with a flat surface.

Mixed Technology

Any single circuit item that incorporates more than one function or connection technology. In connectors, can either refer to a mixture of Throughboard and SMT tails/legs/leads, or a mixture of contact types (such as signal and power contacts) in one connector.


A type of design of equipment or device that allows for easy replacement of certain parts of the device by making the whole piece of equipment from smaller sub-units. For the equipment to be truly modular, it should be a simple operation to replace any sub-unit within the equipment.

Obsolescence, Obsolete product

When a product is declared by the manufacturer as no longer available from them, and they will never manufacture the item again. This may be immediate, or there may be a Last Time Buy period available, or some stocks remain in the distributor supply chain.

Operating Temperature Range

The temperature range (maximum and minimum temperatures) at which the connector or other component can be used in continuous service. A number of characteristics may be downgraded as the product is utilized away from ambient temperature. For instance, current rating typically goes down as temperature goes up.


The release of particles (as a gas) from a solid - the gas particles may previously have been dissolved, trapped, frozen or absorbed. Vacuum or partial vacuum conditions will enhance this effect, making a clean environment in a high-vacuum situation very difficult. Space agencies (NASA and ESA) maintain a list of low outgassing materials that are their preference for use on space vehicles. This is to minimize the exposure in a closed environment to toxic gases, avoid the contamination of optical devices, thermal radiators or solar cells, and lower the risk of other equipment being affected by particle build-up. Raising temperatures can also increase this effect - so components or systems can be baked before use, to drive off the volatile elements. Harwin has a list of outgassing figures pulled from a variety of sources relating to the different plastics used on our products.

PC Tail

An electrical circuit constructed by printing or etching copper (or similar) onto an insulating material. The acronym PCB is short for Printed Circuit Board. Modern production methods mean that this process is completely automated. Designers use CAD software to design the layout of the component locations and the tracks that link them. The design is then converted to a machine-readable format, and the PCBs are then produced by industry standard machinery. This method eliminates variation in what can be very complicated circuits.

PCB Layout

Also know as a Land pattern, this is the layout of tracks that is required on the PCB for the attachment of a device with solder. Typically each part of the layout will be the same size or a little larger than the area on the device designed to be soldered. See also Space Constraints.

PCB Real Estate

Perfluorooctane sulfonates and Perfluorooctanoic acid. In the EU, manufacture and essentially all uses of PFOS are now prohibited under the EU Amendment 2006/122/ECOF – an amendment to the Dangerous Substances Directive 76/769/EEC. PFOA is still manufactured and is not currently prohibited under this legislation. However, both substances have shown in various reports to be carcinogenic and toxic. Harwin's general Environmental Legislation Statement includes a statement on these materials, and can be downloaded from our Environment section..

Pin Header

A particular type of male connector, a very basic construction. Consists of a carrier housing made from an insulating material, normally quite featureless, and an array of conductor pins (typically square or round cross-section) in a regular spaced pattern, on a regular pitch.

Pin Spacing

See Pitch


The pitch of a connector is the distance between the center lines of two adjacent contacts. On a typical rectangular connector such as a pin header, this would be the same value between all adjacent pins, and becomes a defining element of the whole connector. Typical examples include 2.54mm (0.1") pitch and 1.27mm (0.05") pitch.

Plating Finish

Although copper and copper alloys make very good conductive elements within connectors and other devices, they also have their problems. Copper forms a layer of oxide (called verdigris) that is more insulating than copper, making the contact-to-contact resistance high. Also, bare copper would not solder very well. By electroplating the surface of the copper with various substances, oxidization is prevented and soldering is vastly improved.

The two most common plating finishes (the top layer of plating) in electronics are Tin and Gold. Tin gives an excellent solderable contact, whilst Gold gives the best wear resistance for mating surfaces. Neither are prone to oxidization that would cause a conductivity issue, and both are easy to electroplate. Nickel is also often added as an undercoat, to improve the bonding to the base metal and also to reduce effects such as tin whiskers.

Plating Thickness

As plating finishes are generally applied by electroplating, the thickness of the applied metal is normally very thin - in the order of microns (or micro-inches). Gold is often one of the thinnest plating finishes - very little is required to achieve reasonable wear, and a "flash" thickness (less than 0.05 microns or 2 micro-inches) is suitable for commercial low-price contacts. Thicker plating may be required for more rugged applications.


An additional feature on a connector housing which mates into a complimentary feature on the opposing mating half. Often seen as a bump on one side, with a cutout on the other. This feature will make sure that the connectors are always mated in the same orientation to one another. In the case of rectangular connectors, it cannot be mated 180° round the wrong way. On a circular connector, it can only be mated at one angle, not a variety of angles (depending on pin layout).

Power Feed

The line (or lines) of current attached to a piece of equipment, giving that equipment the level of electricity it needs to operate or charge.

Power Transfer, Power Current

The flow of current through a device, typically referring to a higher level of current that will actually drive or power the device (as opposed to signal current, which is typically lower current and used to carry data).

Pre-crimped contacts, Pre-cabled contacts, Pre-wired contacts

An alternative to a fully manufactured cable assembly. An individual crimp or solder contact already attached to a set length of wire. This solution saves the customer from the cost of the crimping or soldering tools and operation, but still gives some flexibility in their final cable assembly.

Printed Circuit Board


Product Change Notification

The notice sent to customers or other interested parties when a product undergoes a major change, or is declared for obsolescence.


A development build of a product, that can be tested for certain characteristics, or to check the physical shape of an item, or any other steps that need to be checked before moving to production. Normally constructed by hand, and done in very low numbers.

Pull-Off Force

The amount of force, measured in Newtons (N), required to separate a cable from the contact to which it is crimped. A contact will have a Minimum pull-off force that is required to confirm it is a good crimp. As this is a destructive test, the testing would be done on additional product made at the same time as the production run. An acceptable result is also that the cable breaks rather than the crimp joint, as long as the minimum pull-off force is exceeded.

Radio Frequency (RF)

Electromagnetic frequencies ranging from 20kHz (kilohertz) to 300GHz (gigahertz). Energy from currents in these frequencies radiates into space as electromagnetic waves. These waves are used to transmit both radio and television. These frequencies start above audio signals and finish below infrared light frequencies - a comprehensive frequency chart is given in Wikipedia (external site link).

Radio Frequency Interference (RFI)

A specific form of Electromagnetic Interference, when the interfering signal is located in the radio frequency spectrum. Generally associated with the interference to signal integrity due to transmission sources (TV, radio, mobile/cell phone, Bluetooth, Wi-Fi, etc.). Any item that transmits will require some form of shielding for the rest of the circuitry to protect it from its own RFI. Also, in many countries the equipment needs to meet standards that define the amount of interference permissible (see Electromagnetic Compatibility).


Usually refers to the qualifying processes that have to be repeated on safety critical systems, whenever a part has to be replaced by an alternative, either from a different supplier or of a different design, or both. Typical industries include (but are not limited to): Aerospace, Automotive, Defense, Medical.


An acronym for "Registration, Evaluation, Authorisation and restriction of CHemicals" - a legislation in place throughout Europe that has a number of aims. Registration has compiled a comprehensive list of all substances used in the manufacture of anything sold in the EU. Further parts of this legislation evaluate the effects of each substance on humans and the environment, and restricts the usage of any substances found to be harmful. The legislation is Regulation (EC) No 1907/2006. Harwin have a support article on REACH.

Reflow Solder

The most common solder process used on Surface Mount PCBs and devices. The solder is applied in a paste format directly to the PCB, and the devices are placed on top of that. Then the whole board with the devices is passed through a solder oven on a conveyor belt. The ambient heat inside the oven turns the paste into solder liquid and creates a solder joint. The PCB carries on to an area where it is then cooled and the solder joint solidifies.


A desirable condition such that the device will provide the specified performance for a specified time under specified conditions. A factor of quality of a connector.

Research & Development

Any department or work that involves working on new technologies, new product concepts, new manufacturing methods, or development of any existing products or methods.

Resistance (Electrical)

A measure of the difficulty with which current flows through an object. Resistance is caused by both the shape of the conducting element, and by the physical properties of the material itself (how conductive is the material). Other factors can also influence the resistance, such as temperature, by influencing the conductivity of the material. The SI unit of resistance is the Ohm (Ω).

Restriction List

A list of substances maintained as part of REACH. These substances are restricted (in various applications or total ban) - each substance has a Conditions document detailing the restriction on the substance.

Ribbon Cable

A specific form of multicore cable, also know as a multi-wire planar cable. The conductors are laid parallel, and the insulation covers each conductor separately, but also bridges between the contacts. The flat top and bottom sides of the ribbon cable can be completely flat, but are normally ridged with valleys between each conductor. The conductors can be solid or stranded. Typically the cable is grey, with one edge showing a red stripe for contact number one - however, rainbow ribbon cable is also available. Adding a connector to a ribbon cable can be done as discrete connections (by splitting up the end of the ribbon), but normally an IDC would be used.


An acronym for "Restriction of Hazardous Substances" - a legislation in place throughout Europe that restricts the use of 10 substances in electrical and electronic equipment. The current version is Directive 2011/65/EU, with amendment Directive 2015/863. Commonly, these directives are referred to as RoHS 2 and RoHS 3. Harwin have a support article on RoHS.

Rugged Connector

A connector designed with harsh or extreme environments in mind, with certain additional design features or material considerations applied to help resist those environments. The harsh environment factors include (but are not limited to): vibration, shock (mechanical), operating temperature range, physical abuse, untrained operator handling.


When the housing shroud around a contact extends far enough past the front of the contact, such that you cannot touch the contact with your finger. Usually seen on the female/socket half of a mating pair of connectors. A good feature to have when the female socket is live and there is a risk of accidental touching by a user.


A mechanical connection system designed by Harwin for use on the Gecko connector. It allows two mating halves to be screwed together by means of two mechanical fixings, one each end of the connector housing. One half has an external thread, the other an internal thread. The parts can be mated before the screws need to be engaged - this action is called Mate-Before-Lock.


The use of a connector with different length mating contacts, to stagger the order in which the contacts mate as the connectors are pushed together. For instance, the grounding conductive element may mate and complete connection before the current-carrying element, for safety reasons. Specific types are called "Hot-Pluggable", "Make-Before-Break", "First-To-Make" or "First Mate Last Break (FMLB)".

Shield Cans

A metal box, designed to fit to a PCB and give board level shielding to certain devices on the PCB. Simple cans are 5 sides (a top and 4 walls), but designs can also be more complex to fit the PCB if space is at a premium. The simplest cans have no fixture elements on themselves, but are designed to slot into surface mount clips arranged on the PCB, making assembly much simpler and rework possible. Harwin offer a range of SMT clips and shield cans.


The application of the principle of a Faraday Cage to prevent the leakage (from inside the shielded area) or interference (from outside the shielded area) of unwanted electromagnetic signals. Includes coax cables, metal backshells, and board level shielding cans.

Shock (mechanical)

A test criteria for mated connectors. A mated pair will be subject to a single sharp movement and dead-stop at a set acceleration in each of the three axes (X, Y and Z, tested separately) and at the same time monitoring for any electrical discontinuity. Typically to pass a shock test, the mated connectors should show no discontinuity for greater than 1µs (one micro-second or 10-6 seconds), and should pass visual inspection.


A feature on a connector housing that protects the contacts (normally the male pins), normally by extended the housing to be level with the end of the contact or slightly further. The mating housing would fit inside this shroud when the housings are mated. Shrouds will protect the contacts from physical damage when the connector is not mated.

Signal Current

The flow of current through a device, typically referring to a lower level of current encoded with data (as opposed to power current, which is typically a higher current that will actually drive or power the device).

Signal Integrity

A measure of the quality of the electrical signal. The cleaner the signal, the better its integrity. Signal integrity and quality can be degraded by various factors, such as resistance, short circuits, power supply noise, ground bounce, and various EMI/RFI factors (like crosstalk). Distance can also be a serious factor, as it gives disruption more time and space to pollute the signal.

Size, Weight and Power (SWaP)

A term used to sum up the issues in the continued miniaturization of electronics - the drive to make products (and therefore components within products) smaller, with less weight, and either more power-efficient, or carry the same or increased current or power within the smaller package.

Size, Weight and Power and Cost (SWaPC)

An extension to the existing term SWaP (Size, Weight and Power), adding the additional issue of keeping the costs down or under control in the continued miniaturization of electronics. The requirements of this strategy is not to use the cheapest possible product, as this would lead to choosing a device not meeting the performance requirements. Instead, the plan is to keep cost as a reminder to choose a product that meets the performance requirements, but does not significantly exceed them, thus keeping the costs to an appropriate level.


Any connector that accepts a male mating pin (so normally a female connector). Can be a single contact, a rectangular array of contacts, or an irregular or oddform layout.


A specific compound of metals and other substances, designed to turn into liquid at temperatures around 210 to 250°C. The solder is placed at the junction between a device and its attachment point to a PCB track, is melted in a solder oven or with a soldering iron, and then allowed to cool back into a solid. The solder then forms a solid conductive bond between the device and the PCB track, holding the device to the PCB and allowing current to pass between the device and the PCB. This is called the solder joint. Solder is also used on some cable assemblies to attach the cable to the contact, depending on the contact construction.

Solder Joints

The completed solder connection between the PCB and the device, or the cable and the contact.

Solder Surface Tension

During the phase of the soldering process in which solder is a liquid, the liquid exhibits surface tension characteristics the same way most other liquids do. For soldering, this often has the beneficial effect of pulling the soldered device into the center of the solder area. Normally this is a desirable effect - but on extremely small and light products being mounted to a PCB, this can also lead to a situation called tombstoning. This is when the product gets pulled up onto a narrow edge, much like a grave tombstone. Causes and solutions to this are many and varied and further investigation would be required.

Space Constraints

The amount of physical space that will be occupied by a connector or other device. It needs to consider 3 factors:

  • The amount of PCB that will be taken up by both the device itself, and the associated PCB layout of solder pads or holes (also known as PCB real estate),
  • The physical volume of the device above (and/or below) the PCB, or for a cable connector, the amount of 3D space required for the physical item,
  • The amount of additional air space required for the function of the device, for any mating item to occupy, for cooling, for wire exit and bend, etc. This is the space within which no other items should intrude, even though there is no physical barrier to that space.
Spring Contact

A contact made from a folded piece of metal. The spring qualities are imparted by the flexible nature of the metal, rather than any inbuilt spring (see Spring Pin for contacts with springs). View Harwin's range of Spring Contacts and Development Kit, containing 16 spring contact designs.

Spring Pin, Spring Loaded Contact

A particular form of contact that consists of 3 elements: a plunger or head, that will make contact with the mating surface; a very small internal metal spring; and a body that provides the tail/lead of the connector, houses the spring, and has a turned-over top edge to stop the plunger from being pushed out. The design will allow the plunger to move up and down within the body, and current is normally conducted through the complete assembly.

There are two main designs. One is very long and thin, called ATE probes (used on Automated Test Equipment), normally used in a test bed in multiples mounted next to each other. The other is short and stubby, sometimes called pogo pins. These can be mounted singly or on connector housings in a rectangular array. They are used as an alternative for pin and socket connectors, as they are more tolerant to misalignment and work well when mating faces may approach each other at angles (as used on the hinges of flip phones, to make the contact between the two phone halves).


Any written document that serves as a definition of requirements, principles of conduct, or agreed level of quality. Many international bodies exist that publish thousands of standards.

Steady-State Current

A value of current that is fixed (does not change with time), and should not vary during operation (under normal circumstances).

STEP Files

An ASCII coded file format for exchange of 3D virtual models from different makes of Computer Aided Design programs. The file format is defined in ISO 10303-21 "Clear Text Encoding of the Exchange Structure". Files are given the extension .stp or .step.

Strain Relief

Any part of a device that will route mechanical stress through the housings and mechanical fixings, rather than through the contacts. Strain through the contacts may cause premature failure or electrical discontinuity, depending on the type of strain.

Substance Resistance

A list of various chemical substances and a guidance against each to show how well a device will withstand the ill-effects of that substance. These lists are normally supplied by the plastics manufacturer, rather than the device manufacturer, as it is anticipated the metal parts of any device will withstand these effects much better than the plastic.

Supply Chain

The layers of suppliers involved in producing any item for a customer - a tree-like structure that extends back to the raw material producers. The number of layers in this tree (or links in the chain) can vary from product to product, company to company.

Surface Mount

A method of attaching devices to a PCB using solder. Surface Mount devices have short tails/legs/leads that either splay outwards on inwards from the product, with a flat surface on the underside. The PCB is designed with similarly shaped pads printed on the PCB. Solder paste is applied to these pads, the device is placed on top, then the PCB is subjected to a solder oven. The joints are formed and allowed to cool. The Surface Mount process is much easier to automate than Throughboard - all aspects of solder application, device placement and solder process can be automated.

Surge Current

The possible maximum current that might occur under occasional circumstances, that is not damped out by other elements within the equipment. This can occur at switch-on (called inrush current), or with spikes in the power grid (such as lightning strikes or line faults).


An acronym for "Substances of Very High Concern". A list of substances maintained as part of REACH. If the item you manufacture contains any of the SVHCs over 0.1%, then you are obligated to report this to your customers proactively (not on request only). Substances on this list have been shown to be harmful to humans and the environment, and listing them here is the first step in the REACH process in eventually restricting and banning their use. Harwin have a support article on REACH.

Technical Drawing

A document (normally produced to an engineering drawing standard such as BS 8888) that shows the physical dimensions of a product, and may also include specification information. Styles and content will vary across manufacturers and in consideration of the target audience (e.g. for production or for customers). On Harwin's website, Technical Drawings are available from individual product pages.


A device consisting of two dissimilar metals or conductors joined at one end, used to to detect temperature and temperature changes. A thermoelectric effect is caused by the different heating characteristics of the two different materials. Therefore a temperature-dependent voltage is generated, which can be interpreted to a temperature measurement.


A method of attaching devices to a PCB using solder. Throughboard devices normally have straight tails/legs/leads. These legs pass through holes in the PCB, and are typically soldered on the underside of the PCB, usually using a wave solder process. Also suitable for hand soldering. Gives greater mechanical strength than Surface Mount soldered products, but is harder to automate product placement on the PCB.


The amount of data (in the form of electrical signal) that can be passed through the circuit or system, or individual components. Can be measured in data packets, frequency, or other signal requirements.


Every dimension created during manufacturing, or every resultant dimension from one or more feature, will have a tolerance in the actual measurement of that feature. For instance, a manufacturing process will be aiming for 3mm exactly, but due to many elements in the manufacturing process, it will get near most of the time rather than perfect. The tolerance is the allowed amount by which the dimension can vary - for instance +/-0.1mm. These will normally have been considered during the design process and checked to make sure they will not affect the functionality of the product.

Track, Trace

An element of PCB design, that connects the components attached to the printed circuit. Works in a similar method to cable, but designing all the tracks on a PCB so that they do not touch or overlap can be taxing depending on the complexity of the application.

Twisted Pair

A type of cable assembly in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. The pairing reduces electromagnetic radiation and crosstalk between neighboring pairs, and improves the rejection of external electromagnetic interference. The pitch of the twist should be part of the cable assembly specification, as bundles of multiple twisted pairs should normally have different twists. Commonly used in telephony and computer networking.


The technical definition is a space devoid of any matter. In practice, it is very difficult to achieve a perfect vacuum, and levels of partial vacuum are more common. On Earth, ultra-high vacuum chambers can achieve 100 particles/cm³. Outer space has the equivalent of a few hydrogen atoms per cubic meter. Near-vacuum is sometimes used to describe the conditions in low earth orbit, where the conditions are not far from true outer space.


A connector orientation - the mating face of the connector is parallel and facing away from the PCB where the connector is mounted. Called Vertical because the housing stands vertical when the PCB is held flat.


A test criteria for mated connectors. A mated pair will be subject to a continuous steady shaking at a set acceleration, frequency and amplitude in each of the three axes (X, Y and Z, tested separately) and at the same time monitoring for any electrical discontinuity. Typically to pass a vibration test, the mated connectors should show no discontinuity for greater than 1µs (one micro-second or 10-6 seconds), and should pass visual inspection.


The derived SI unit of electric potential difference (voltage), defined as the electric potential energy per unit charge. The symbol for volt is V, and is equivalent to joules per coulomb. The voltage between point A to point B is equal to the work which would have to be done, per unit charge, against or by the electric field to move the charge from A to B.

The volt is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.


The electric potential difference between two points. The SI unit of voltage is the volt.

Wave Solder

The most common solder process used on Throughboard PCBs and devices. The devices are placed onto the PCB: their tails/leads hang through the board to the underside. These are placed onto a conveyor, which moves the PCB over a solder tank. The tank has a standing wave of hot liquid solder in it, so that the underside of the PCB and the leads pass through the top of this wave. The solder only sticks to where there is exposed metal (the tracks and the device leads), and does not stick to the rest of the PCB underside. Surface Tension in the solder creates a solder joint between the PCB track and the device lead, which then solidifies as the PCB passes out the machine and cools down.


Wiring Harness Manufacturer’s Association®


See Cable


The transfer of information or power between two or more devices without any visible, physical conductor. Most common are radio waves, but can also include other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound.

Typical applications include Bluetooth, cellular/mobile telephones, Wi-Fi, GPS, radio and broadcast television. Power transmission is one of the latest applications that is in the early stages of development.

Wiring Assembly
Wiring Harness
Wiring Loom
Withdrawal Force

The amount of force required to separate two mated contacts or connectors. This force does not include anything contributed by mechanical fixings - it is purely to overcome the spring forces keeping the connection point mated. This force is normally quoted in specifications as being a minimum force requirement, but may also have a maximum. It is sometimes also referred to as Holding Force.