A connector is a component used to connect or disconnect an electrical circuit without special tools or procedures such as soldering; the product is connected or cut off by hand or with simple tools. Connectors come in many types but broadly fall into two groups: one-piece types used on their own, in which a printed circuit board or wire is connected directly to the connector, and two-piece types consisting of a plug and a receptacle. In the two-piece type the mating part between plug and receptacle is called the contact area, and the part where the board or wire is attached is called the connection area.

Connector ratings and performance generally fall into the following four main groups.

1. Electrical performance: rated voltage, rated current, contact resistance, insulation resistance and dielectric withstand voltage.

2. Mechanical performance: insertion and withdrawal force, mating durability, vibration resistance and shock resistance.

3. Environmental performance: heat resistance, cold resistance, humidity resistance and gas resistance.

4. Mounting performance: solderability and resistance to soldering heat.

Electrical performance

(1) Rated current: the maximum current that can flow continuously without deterioration of electrical or mechanical characteristics.

(2) Rated voltage: the voltage that can be applied continuously without deterioration of electrical or mechanical characteristics.

(3) Contact resistance: the electrical resistance of mated contacts under specified conditions. The resistance including the resistance of the conductors leading to the contact, the total resistance, is usually called contact resistance, and stability matters more than the absolute value.

(4) Insulation resistance: the resistance between insulated contacts.

(5) Dielectric withstand voltage: the limit value at which insulation performance is not impaired when a voltage is applied between insulated metal parts for one minute.

Mechanical performance

(1) Insertion and withdrawal force: the force required to fully insert or withdraw a pair of connectors with the coupling mechanism not operating.

(2) Mating durability: the guaranteed number of insertion and withdrawal cycles, also called the mating count. It depends mainly on the contact pressure of the contact points and the plating specification.

The gold plating on the contact surface gradually wears with mating cycles and the nickel underplate becomes exposed. Because nickel is harder than gold, has better wear resistance and is applied more thickly, the base material, usually a copper alloy, can far exceed the guaranteed number of cycles.

If only simple mating is performed, contact resistance stays low and stable even with the nickel exposed, and there is no problem from the contact resistance value alone. If a product in this state is used in a harsh environment, however, contact resistance may rise because of nickel corrosion and become unstable.

Other performance

The effects of service environment and ageing have been tested, and vibration resistance, shock resistance, environmental performance and mounting performance are all assured. These items are generally carried out individually with their own conditions and criteria rather than as a combined condition and criterion. Depending on function or structure, connectors may also have custom performance requirements, including locking strength and wire pull-out strength.