PCB Connectors: Types, Structures & How to Choose the Right Connector
PCB connectors play an essential role in modern electronic and RF equipment by providing reliable electrical connections between circuit boards, cables, and external devices.
As electronic devices become smaller and RF systems operate at higher frequencies, connector size, mounting method, and electrical performance have become increasingly important.
In this article, we explain the basic structure of PCB connectors, common mounting and connection methods, typical coaxial connector types, and key points to consider when selecting a connector.
What Is a PCB Connector?
A PCB connector is a component mounted directly on a printed circuit board (PCB) to establish an electrical connection between circuit boards, cables, or external equipment.
PCB connectors do more than simply provide electrical continuity. They can also help ensure reliable signal and power transmission, simplify equipment assembly, and improve maintainability by making modules and circuit boards easier to connect and replace.
Basic Structure of a PCB Connector
PCB connectors generally consist of conductive metal contacts and insulating components that hold and protect them. For RF and coaxial connectors, shielding is also important for maintaining stable signal transmission.
Housing / Shell / Insulator
The housing or insulator holds the contacts in the correct position and prevents electrical shorts between them. Connectors with a metal shell can also provide shielding against external noise and may help prevent incorrect mating through mechanical keying.
Contacts
Contacts are the conductive metal components responsible for carrying electrical signals or power. They typically use a pin-and-socket mating structure.
In coaxial RF connectors, the interface consists of a center contact for signal transmission and an outer contact that provides the ground connection and shielding.
PCB Connector Types by Structure and Mounting Method
Connector Structure
| Type | Structure | Main Advantages |
|---|---|---|
| One-Piece | Makes direct contact with PCB patterns such as card edges | Fewer components, lower cost, and space-saving design |
| Two-Piece | Uses mating plug and receptacle connectors | Reliable contact, durability, and resistance to vibration |
PCB Mounting Methods
Through-Hole (DIP)
Connector pins are inserted through holes in the PCB and soldered from the opposite side. This method provides strong mechanical retention and is suitable for connectors subject to mechanical stress.
Surface Mount (SMT)
The connector is soldered directly onto pads on the PCB surface. SMT is suitable for high-density PCB designs and automated assembly.
Edge Mount
The connector is mounted along the edge of the PCB, allowing a short connection between the PCB transmission line and the connector interface. This method is commonly used with high-frequency RF connectors such as SMA.
PCB Connector Types by Connection Method
PCB connectors can also be classified according to what the circuit board connects to.
Board-to-Board (BtoB)
Connects two circuit boards directly, such as a main board and sub-board.
Board-to-Wire (BtoW)
Connects a PCB to wires or coaxial cables. RF receptacles used to connect coaxial cables to circuit boards also fall into this category.
Input/Output (I/O)
Provides an interface between internal circuitry and external equipment or cables.
Shorting and Termination Connections
Used for circuit configuration or to terminate transmission lines and help prevent signal reflections.
Common Coaxial PCB Connector Types
Coaxial PCB connectors are available in various sizes and interface designs depending on the required frequency range, installation space, and connection method.
The table below shows some common coaxial connector types used in PCB applications.
| Connector Type | Coupling | Main Feature | Typical Applications |
|---|---|---|---|
| SMA | Threaded | Compact, high-frequency performance | RF equipment, test equipment, wireless systems |
| SMB | Snap-On | Compact and easy to connect | Communication equipment, compact RF devices |
| MCX / MMCX | Snap-On | Very compact design | Wireless modules, compact electronic devices |
| BNC | Bayonet | Quick and reliable connection | Test equipment, video and RF systems |
| SMP | Push-On | Compact, high-frequency interface | High-density RF systems |
| Micro BNC | Bayonet | Compact BNC-style interface | Broadcast and high-density equipment |
How to Select a PCB Connector
Frequency Range
Select a connector that supports the operating frequency of your system.
Impedance
For RF applications, ensure that the connector impedance matches the system impedance, typically 50 Ohm or 75 Ohm.
Mounting Method
Consider whether through-hole, SMT, or edge mounting is appropriate for the PCB design.
Available PCB Space
Compact connectors such as MMCX and SMP may be suitable for high-density PCB layouts.
Environmental Requirements
Consider waterproofing, dust resistance, vibration, shock, and other environmental conditions.
Mating and Installation Requirements
Consider the required connection method, mating frequency, and mechanical reliability.
Summary
PCB connectors are available in a wide variety of structures, mounting methods, and interface types depending on the application.
For RF and high-frequency systems, selecting the appropriate coaxial PCB connector requires consideration of frequency range, impedance, mounting method, available space, and environmental conditions.
Understanding these factors can help ensure reliable signal transmission and stable system performance.
Purchase Guide
Tyclon coaxial connectors and processed coaxial cable products can be purchased directly online using a variety of credit cards.
