PCB Connectors: A Guide to Common Types and Choosing the Best Fit

Found everywhere from compact consumer gadgets to aerospace platforms, Printed Circuit Board (PCB) connectors are vital interface parts that allow power and communication signals to flow between other boards, cables, or electronic components. With so many variations available, selecting the right one may appear daunting. However, this guide will offer some clear, practical advice for making informed decisions and highlight some of the most widely utilized PCB connector types for your consideration.

Initial Steps for Selecting the Best Fit

Step 1: Define Electrical Requirements

The voltage, current, and signal frequency demands of your application will always be the most important aspects dictating your choice. The connector must safely handle the peak current without causing overheating or excessive voltage drop. For data transmission, especially in high-speed digital applications, evaluate additional parameters such as:

• Characteristic Impedance Matching: Connectors and PCB traces should have an impedance that matches the transmission line, usually 50 ohms for RF or 100 ohms for differential pairs like USB, HDMI, or Ethernet. Additionally, for RF or high-speed digital designs, impedance-controlled connectors should be prioritized.
• Insertion Loss: Insertion loss is the reduction in signal strength as it passes through the connector, caused by conductor resistance and dielectric material losses. It also increases with frequency and connector size. To ensure signal integrity, choose connectors with low insertion loss at or above your system’s highest operating frequency.
• Crosstalk and Return Loss: Crosstalk occurs when signals in adjacent pins or conductors interfere with each other, while return loss reflects how much signal is reflected due to impedance mismatches. Pick connectors with internal shielding, differential pair routing, or specified spacing between high-speed signal pins to mitigate this if needed for the application.

Step 2: Analyze Mechanical Constraints and Environmental Conditions

Next, assess the physical layout of your PCB, including available space and how the connector must interface with nearby components. This will determine whether a vertical, right-angle, or custom orientation is required.

Moreover, if the device will operate in rugged or outdoor environments, the connector must meet relevant environmental protection standards. In general, pick options with the required amount of vibration and shock resistance, align the operating temperature range with expected conditions, and use corrosion-resistant materials for long-term reliability.

Step 3: Consider Assembly, Maintenance, and Lifecycle Factors

Connector selection should align with your manufacturing and maintenance strategy. The decision between Surface Mount Technology (SMT) and Through-Hole Technology (THT) depends on mechanical load, assembly volume, and repair expectations:

• THT connectors provide superior mechanical strength, especially for connectors subject to mating cycles or external force
• SMT connectors are preferred for high-density, automated assembly

Additionally, if you want to reduce assembly time and minimize human error, look for connectors with polarization features, retention mechanisms, or toolless mating options.

Popular Connector Types

Header Connectors

Perhaps the most ubiquitous type, header connectors facilitate wire-or-cable-to-board connections. If you have ever looked inside a desktop computer or tinkered with a prototyping board like an Arduino, chances are you have seen them. They essentially consist of rows of pins or sockets, available in single-row or dual-row configurations to support varying interface complexities.

The pitch, or the distance between pin centers, is a particularly crucial specification when considering these boards for use. The standard 2.54mm pitch is selected in situations like prototyping and larger devices, while finer pitches like 1.27mm or smaller are used in compact electronics.

Backplane Connectors

For complex systems that require multiple PCBs to communicate and handle massive amounts of data, backplane connectors are the solution. They connect several daughterboards to a central backplane or motherboard, supporting high pin counts and maintaining signal integrity across dense, high-speed communication paths.

Edge Connectors

Edge connectors, also called card-edge connectors, enable a direct mating interface with the conductive pads along the edge of a PCB without requiring additional connectors on the board itself. This makes edge connectors perfect for applications requiring easy insertion, swappability, or expansion capability. The most recognizable example is the PCI Express slot on a computer motherboard, which accepts graphics cards, network adapters, and other expansion cards.

Wire-to-Board Connectors

Wire-to-board connectors establish direct electrical and mechanical connections between discrete wires or multi-conductor cables and a PCB, enabling the integration of off-board components like sensors, displays, power supplies, and switches. As such, these connectors are extremely common across consumer electronics, industrial control systems, and automotive assemblies.

You should always match the selected wire-to-board connector with wire gauge and insulation diameter, but there are also several termination styles available for different production and application needs:

• Screw Terminals: Easy for field wiring and maintenance, though bulky and not ideal for high-density layouts.
• Crimp Contacts: Used in high-volume manufacturing for secure, low-resistance connections, crimp contacts require proper tooling but are highly reliable when assembled correctly.
• Insulation Displacement Connectors (IDC): This method allows for fast, solderless termination by piercing the insulation and contacting the conductor directly.

Find a Variety of Quality PCB Connectors on Just Connectors

Ultimately, selecting connectors that are both high-quality and compliant with the application’s needs is imperative for creating PCB devices that display excellent signal integrity, mechanical durability, and regulatory adherence. If you want to source trustworthy PCB connectors, Just Connectors is a leading destination. As an ASAP Semiconductor platform, we offer a vast catalog of components from leading manufacturers, all of which are ready for purchase with competitive and timely fulfillment options. To see how we make it easy to secure everything you need for your projects, check out our website and connect with our experts at your convenience.

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1. nicholas smith
2. Posted on July 11, 2024
airborn connectors

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