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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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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.


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.