What Is a Connector?

A connector is an electromechanical device used to create a separable electrical connection between two segments of a circuit or between distinct electrical systems. Unlike soldered joints or wire terminations, connectors are designed to be mated and unmated repeatedly without degrading the conductive path, enabling system assembly, maintenance, field replacement, and modular design across virtually every segment of electronics and electrical engineering.

Connectors are distinguished by their mating interface, termination method, current and voltage rating, environmental sealing, and insertion force requirements. A connector pair normally consists of a plug, the movable connector attached to a cable or assembly, and a receptacle or jack, the fixed connector mounted to a chassis or printed circuit board. The classification follows conventions defined in standards such as ASME Y14.44, which governs connector designation in engineering drawings, and is complemented by IEEE 315-1975, which defines graphical symbols for jacks and plugs in schematics.

Connector Types and Form Factors

Connectors are categorized by the signals or power they carry and by their physical interface geometry. Coaxial connectors, including the BNC, SMA, and N-type families, are widely used in radio-frequency and microwave systems and are standardized in IEEE 287.1-2021, the standard for precision coaxial connectors at RF, microwave, and millimeter-wave frequencies. Rectangular multi-pin connectors such as D-subminiature and MIL-DTL-38999 circular connectors serve data, signal, and power applications in aerospace, industrial, and military equipment. Board-to-board connectors and zero-insertion-force (ZIF) connectors are prevalent in consumer electronics and computing. Power connectors including IEC 60320 appliance couplers regulate the interface between mains-powered equipment and supply cords across international markets.

Electrical and Mechanical Performance

A connector's performance is characterized by its contact resistance, insulation resistance, current-carrying capacity, voltage rating, and durability over a specified number of mating cycles. Contact resistance, typically measured in milliohms, is sensitive to contact geometry, plating material, and normal force between mating contacts. Gold plating is preferred for low-level signal contacts because it resists oxidation, while tin and silver platings serve higher-current applications at lower cost. Mechanical retention force, vibration resistance, and ingress protection rating (IP code per IEC 60529) determine suitability for automotive, marine, and outdoor applications. Dielectric materials such as polyamide, polyetherimide, and liquid crystal polymer are selected for temperature resistance, dimensional stability, and flammability compliance. The IEC connector standards maintained by Amphenol LTW outline the interoperability requirements that manufacturers follow.

High-Frequency and Fiber Optic Connectors

At radio and microwave frequencies, connector design is dominated by impedance matching requirements. A coaxial connector must maintain its characteristic impedance, most commonly 50 ohms, through the transition region to avoid reflections that degrade signal integrity. Connectors operating above 40 GHz require precision machining tolerances measured in micrometers. Fiber optic connectors, including the LC, SC, and MPO types, achieve optical coupling through physical contact or angled-physical-contact polishes of the ferrule end face. Return loss and insertion loss are the governing metrics, typically specified at better than 0.3 dB insertion loss and 40 dB return loss for standard single-mode applications. Selection guidance for connector types across applications is cataloged in GlobalSpec's electrical connector selection guide.

Applications

Connectors have applications in a range of fields, including:

• Consumer electronics and mobile devices
• Aerospace and defense instrumentation
• Automotive and electric vehicle power systems
• Telecommunications and data center infrastructure
• Medical devices and patient monitoring equipment