Essential Guide to PCB Pin Connector Types: What You Need to Know

Introduction to PCB Connectors

• PCB pin connectors transfer current, data and power between the printed circuit board (PCB) and the external world, including sensors, power supplies, electronic modules, external devices, and external components; as input/output interfaces or signal connectors, they create an electrical connection that lets data or power enter or exit a device. This connection to the world outside the PCB is accomplished via mating connectors, wire cables, and links to other components suited to the application. PCB pin connectors are usually referred to as headers, and they are mounted directly onto the PCB. They serve as a gateway to the world outside the PCB. Their basic structure includes an insulating housing for support and conductive metal contacts. These connectors ensure reliable transfer of power, signal and data between circuits in diverse environments.

• The terms pin, contacts and terminal are used interchangeably in the connector industry, although pin can refer to a stamped terminal or a drawn wire pin. In this article, we use the words pin or contact to refer to a stamped terminal.

• The selection of PCB connectors depends on factors like pin spacing or pitch, termination method, materials, coatings, features such as locking mechanisms, operating environment, and mechanical performance; harsh or corrosive settings may also require enhanced insulation and corrosion-resistant materials.

• PCB connectors can be attached to the circuit board via through-hole, surface mount or press-fit technology. In through-hole technology, the connector leads are inserted into pre-drilled and plated holes on the PCB, called plated-through-holes, and wave or reflow soldered in place. In surface mount technology, the connector is soldered directly onto pads on the PCB surface. In press-fit technology, the connector pin is inserted into a plated-through-hole (PTH) in the PCB, and establishes a high-normal force and gas-tight mechanical connection between the pin and the PCB.

• Understanding PCB connectors is crucial for designing and developing electronic systems, as they play a vital role in maintaining signal integrity, power transmission and mechanical stability.

• PCB connectors are used in a wide range of applications, including consumer electronics, automotive systems, aerospace, medical and industrial equipment.

Classification of PCB Connectors

• Common PCB connector types are primarily classified by connection interface: board-to-board, wire-to-board, and wire-to-wire, with each category serving a specific purpose in electronic devices.

• Board-to-board connectors link two PCB’s, and can be configured with through-hole, surface mount or press-fit technologies on either end.

• Wire-to-board connectors connect wire cables to a PCB, allowing communication and/or power transmission between components, and can be configured with through-hole, surface mount or press-fit technology on one end, and crimp-style contacts on the other, where wires are crimped onto contacts and inserted into a plastic housing, or insulation displacement connectors, where the contact pierces insulation without stripping.

• Wire-to-wire connectors are a separate category used to directly join cables or harnesses for reliable power or signal transfer.

• Terminal block connectors connect wires using a screw or spring mechanism, making them useful where installers need to connect wires in the field.

• Board-to-blade connectors connect power blades to a PCB, and can be configured with through-hole, surface mount or press-fit technology on the board end, and fuse fork (also called tuning fork) technology on the other end.

• The classification of PCB connectors helps designers choose the appropriate connector type for their specific application, considering functional requirements such as signal, data and power transmission, as well as mechanical and electrical performance.

Types of PCB Connectors

• There are various types of PCB connectors, including pin connectors, socket connectors, backplane connectors, circular connectors, card edge connectors, and data connectors, each with unique characteristics and applications.

• Pin header connectors are male connectors with rows of pins, used for board-to-board, wire-to-board and blade-to-board connections, offering different pin spacings and pin counts for varied applications, and together with sockets are the most common type of standard connectors, with male pins mating to female receptacles.

• Socket connectors are female connectors designed to mate with pin connectors, providing secure connections for board-to-board and wire-to-board applications.

• Mezzanine connectors are board-to-board options for short-distance parallel or vertical links and support dense, high density connections where space is limited.

• Stacking connectors are used to vertically stack boards to save space in compact assemblies.

• Card edge connectors let a PCB edge insert directly into a slot and are common for expansion cards such as RAM, GPUs, or peripheral component interconnect express cards.

• FPC connectors are designed for flexible printed circuits and other flexible electronic components in compact products.

• Connectors for flexible flat cable are also used with ribbon cables in compact electronics and mobile devices.

• Backplane connectors connect PCBs in a parallel (stacked one above the other) or perpendicular (vertical daughter cards, like books on a shelf) manner, while circular connectors offer a robust and reliable connection for high-frequency applications.

• The design of the plug side of the connector is dictated by mating connector requirements, while the design of the PCB side of the connector is dictated by terminal performance requirements, manufacturing assembly efficiencies, thermal management, and long-term reliability. Experienced connector companies, like Autosplice, can provide valuable insights in designing the PCB side termination for press-fit technology, through hole technology (THT), pin-in-paste reflow technology, surface mount technology (SMT), and other less common PCB connection methods. 

• Coaxial connectors and high frequency connectors are also used for RF links in wireless communication systems, with micro coaxial and micro miniature coaxial versions suited to tight spaces. The selection of the most suitable and cost effective termination type among the different termination approaches depends on application requirements, PCB assembly process, production volume, and mechanical, electrical and thermal performance requirements. Data connectors also include D-sub and high definition multimedia interface options for carrying data or video between systems. This also improves modularity by making components easier to add, remove, or replace.

Power Connectors

• Power connectors are designed to deliver electrical power to components on the PCB, via specific current ratings at a given voltage, while maintaining signal integrity where control or monitoring lines are present and providing a secure connection under load.

• They are classified by current rating, voltage rating, AC/DC type, and geometry, and should be rated with at least a 20% margin over peak load. At a given voltage, low power connectors typically operate at current ratings of between 5A and 15A. High power connectors typically operate at current ratings of between 15A and 40A.

• Power connectors are critical for ensuring the reliable operation of electronic devices, and their selection depends on electrical requirements, operating environment, and physical size constraints. They must also withstand thermal and electrical stresses associated with power transmission, especially in demanding operating environments.

• Proper selection of power connectors is essential to prevent overheating, electrical shock, or device malfunction, and material choice affects conductivity, corrosion resistance, and temperature tolerance for power applications.

Pin Headers and Socket Connectors

• Pin headers and socket connectors are commonly used for board-to-board and wire-to-board connections, offering a secure and reliable connection.

• Pin headers are male connectors with rows of pins, while socket connectors are female connectors designed to mate with pin headers. Common contact materials include copper alloys as the base, brass where added strength is needed, and phosphor bronze for spring contacts and repeated mating cycles.

• Beryllium copper is also used in high-performance versions, including demanding medical devices applications.

• These connectors are available in various configurations, including straight, right-angle, and surface mount types, with different pin spacings and counts for diverse applications, and the choice of materials affects conductivity, corrosion resistance, and temperature tolerance, while high-performance plastics and advanced metal alloys improve electrical and mechanical performance.

• Gold plating is often used on contacts to improve reliable signal transmission and achieve low contact resistance.

• Pin headers and socket connectors are widely used in electronic devices, including consumer electronics, industrial equipment, and medical devices.

Backplane Connectors

• Backplane connectors connect PCBs in a parallel or perpendicular manner, enabling high-speed data transmission and reliable connections.

• They are commonly used in communications and computer systems, where high-density interconnects are required.

• Backplane connectors offer a secure and reliable connection, with key features including high-density contacts, low insertion loss, and excellent signal integrity.

• These connectors are designed to maintain signal integrity and mechanical stability, even in high-vibration environments.

Universal Serial Bus (USB) Connectors

• USB connectors are widely used for data transmission and power supply between electronic devices and peripherals.

• They offer a compact and versatile connection, with key features including high-speed data transmission, low power consumption, and excellent signal integrity.

• USB connectors are commonly used in consumer electronics, including computers, smartphones, and tablets, with various types including USB-A, USB-B, USB-C, Mini-USB, and Micro-USB.

• These connectors are designed to provide a secure and reliable connection, with a locking mechanism to prevent accidental disconnection.

Connector Pitch and Size

• Connector pitch and size are critical factors in the selection of PCB connectors, with key features including low insertion loss, excellent signal integrity, and high-frequency performance.

• The pitch of a connector refers to the distance or spacing between the pin contacts, with smaller pitches allowing for higher density connections.

• The size of a connector is also an important consideration, with smaller connectors providing a more compact design and larger connectors offering higher current carrying capacity.

• Proper selection of connector pitch and size is essential to ensure reliable and efficient operation of electronic devices.

PCB Connector Installation and Maintenance

• The installation and maintenance of PCB connectors are critical factors in ensuring reliable and efficient operation of electronic devices.

• Proper installation techniques include soldering, crimping, and insulation displacement, with key considerations including connector pitch, termination method, and materials.

• Regular maintenance is essential to prevent connection failures and extend connector lifespan, with key activities including cleaning, inspection, and replacement of worn or damaged connectors.

• Proper installation and maintenance of PCB connectors are essential to prevent overheating, electrical shock, or device malfunction.

Applications of PCB Connectors

• PCB connectors have a wide range of applications, including consumer electronics, industrial equipment, medical devices, and aerospace systems, where dense, reliable connector solutions are also used in avionics systems.

• They are used in various devices, including computers, smartphones, tablets, and televisions, with key functions including data transmission, power supply, and signal processing, and compact consumer products often rely on surface mount technology for smaller, high-speed connector implementations.

• PCB connectors are essential components in electronic systems, providing a secure and reliable connection between components and peripherals.

• Proper selection and installation of PCB connectors are essential to ensure reliable and efficient operation of electronic devices.