You have big choices when you pick parts for your PCB design. Looking at all the different circuit board connector types can be confusing. Early choices you make here affect your board layout, case design, and how well your product works.
This guide will clear things up. We will show you the most common connector types PCB designers use. You’ll learn how to tell them apart, where to use them, and what to watch out for.
Key Takeaways
- Group connectors by what they connect. The three main groups are Board-to-Board (B2B), Wire-to-Board (WTB), and Wire-to-Wire (WTW). This makes it easier to find what you need.
- Match the connector to the job. Consider key factors like current rating, pin count, and mating cycles. Always verify these values against the manufacturer’s datasheet and relevant industry standards like IEC.
- Know the common types. Getting familiar with pin headers, FPC connectors, and USB ports will cover most of your projects.
How to Make Sense of PCB Connectors
Let’s start with a simple trick to organize the chaos. The best way to sort through all the different connectors is to ask one simple question: What is it connecting?
Almost every connector falls into one of three main groups. At SOULIN, our product catalog is organized around these core applications to help engineers quickly find what they need. You can see this structure in our main product categories
The Main Categories
- Board-to-Board (B2B): These connect two circuit boards together without any wires. They are for stacking boards or plugging a small card into a bigger one.
- Wire-to-Board (WTB): These link wires from an external part (like a battery, sensor, or switch) to your PCB. For a deep dive, see our complete wire-to-board connector selection guide.
- Wire-to-Wire (WTW): These connect one cable to another, acting as a splice point in a wiring harness.
The Visual Encyclopedia of Common PCB Connectors
Let’s look at the specific types of circuit board connectors you will see in real designs. For each one, we’ll show you a picture and explain what makes it unique.
Board-to-Board Connectors
These are for when you need your PCBs to talk directly to each other.
Pin Headers & Sockets
These are the Lego bricks of the electronics world. Pin headers are the most fundamental way to connect two boards. You get a set of male pins (the header) and a matching female socket. They’re simple, cheap, and everywhere.
- Things to Know:
- Pitch: The spacing between pins. 2.54mm (0.1″) is the classic breadboard-compatible pitch, while high-density designs often use 1.27mm, 1.0mm, or even smaller.
- Pins: Can be a single pin or have 80+ pins in two rows.
- Where You’ll See Them:
- Plugging “shields” onto Arduinos or “HATs” onto a Raspberry Pi.
- Connecting Raspberry Pi HATs.
- Ports for programming tools like a JTAG debugger.
When selecting pin headers for your design, quality matters significantly. SOULIN’s 2.54mm pitch pin headers offer gold-plated contacts for superior conductivity and corrosion resistance. Their reinforced plastic housings also provide better durability during repeated insertions compared to standard options.
Mezzanine Connectors
When you need to stack boards parallel to each other, like floors in a high-rise, you need a mezzanine connector. These are sophisticated connectors built for high-speed, high-density links in a compact, stacked layout.
- Things to Know:
- Stacking Height: They are designed to create a specific distance between boards, often specified in millimeters (e.g., 4mm to 10mm).
- High Density: Packs hundreds of pins into a tiny space.
- High Speed: Built to handle fast data signals without messing them up, often with controlled impedance rated for multi-gigabit speeds.
- Where You’ll See Them:
- Complex communications hardware and server equipment.
- Advanced embedded systems with multiple stacked boards.
Backplane Connectors
Backplane connectors are used in huge systems where multiple “blade” cards all plug into one giant “backplane” board. They are built to be incredibly robust and handle massive amounts of data.
Things to Know:
- Rugged: Made for reliability and many connections.
- Fast: Designed for system-level protocols like PCIe. Many are compliant with standards set by PICMG (PCI Industrial Computer Manufacturers Group).
Where You’ll See Them:
- Data center servers and network switches.
- Telecommunications racks.
Card Edge Connectors
You may see these connectors. If you’ve ever installed a graphics card or a stick of RAM in a PC, you’ve used a card edge connector. The cool part is that one half of the “connector” is just a set of gold-plated traces right on the edge of the smaller board..
- Things to Know:
- Low Cost: The “male” side is part of the PCB, so you only buy the socket.
- Standardized: Follows rules for PCIe, M.2, and computer memory. For example, PCIe connectors follow specifications from the PCI-SIG (Peripheral Component Interconnect Special Interest Group), ensuring interoperability between motherboards and cards from different vendors.
- Where You’ll See Them:
- PC motherboards for GPUs, SSDs, and Wi-Fi cards.
- RAM slots.
Wire-to-Board Connectors
This group is your PCB’s link to the outside world.
FFC/FPC Connectors
Ever wondered how those paper-thin, flexible cables inside a laptop connect? The answer is FFC (Flexible Flat Cable) or FPC (Flexible Printed Circuit) connectors. Before choosing, it’s vital to know the differences between FFC and FPC cables and consult our technical guide to FPC/FFC connectors for precise details.
- Things to Know:
- Zero Insertion Force (ZIF): Most have a small locking latch. You flip it up, slide the cable in gently, and press the latch down to lock it.
- Low Profile: They are extremely flat, which is perfect for thin devices.
- Note: Be mindful of their limited durability. Many common FPC connectors are rated for only 10-20 mating cycles. They are not intended for frequent user connection/disconnection.
- Where You’ll See Them:
- Inside virtually every smartphone, laptop, and camera are screens, sensors, and keyboards.
SOULIN offers a variety of FFC/FPC Connectors, which are engineered for critical applications, offering unparalleled quality and performance. Each is tailored for specific applications and performance requirements. You can find proper connectors according to your needs.
I/O (Input/Output) Connectors
These are the ports you see and touch on the outside of a device.
USB Connectors
Universal Serial Bus (USB) is the standard for both charging and data transfer. From the old, chunky Type-A to the modern, reversible USB-C, they are a must-have for most devices.
- Things to Know:
- Standardized: The specifications are governed by the USB Implementers Forum (USB-IF). Using a certified connector is crucial for compliance and performance. For instance, the USB Type-C Cable and Connector Specification defines the pins for high-speed data and power delivery.
- Power & Data: Can charge a device and transfer data over the same cable.
- Where You’ll See Them:
- You can find them in phones, computers, chargers, and toys.
Modular Jacks (RJ45)
You probably know this one as the Ethernet port. The RJ45 is the trusty plug for wired internet connections. It has a little plastic tab that clicks into place for a connection you can count on.
Things to Know:
- Locking Tab: Snaps in for a secure physical link.
- Shielding: Often built with a metal shell to block electrical noise.
Where You’ll See Them:
- Routers, modems, desktop computers, and smart TVs.
High-Frequency (RF) Connectors
Radio signals are picky. You can’t just send them through any old wire or connector. They need a special, controlled path, which is where RF connectors come in.
SMA Connectors
SMA connectors are a common type of RF connector used for antennas. They have a screw-on design that creates a very secure connection, which is key for good signal quality.
- Things to Know:
- 50 Ohm Impedance: They are designed to match the 50 Ohm standard for RF equipment, preventing signal loss.
- Secure: The threaded barrel keeps it from vibrating loose.
- Where You’ll See Them:
- External antennas on Wi-Fi routers.
- GPS units and radio testing gear.
U.FL Connectors
U.FL connectors are incredibly small. Their tiny size makes them perfect for connecting antennas inside compact wireless devices like laptops and drones.
- Things to Know:
- Extremely Small: Takes up just a few square millimeters of PCB space.
- Snap-on: Makes a small “click” when you mate it correctly.
- Note: These connectors are extremely delicate and typically rated for only about 30 mating cycles. Always use a proper extraction tool to disconnect them; prying with a screwdriver can easily damage the connector or rip the pad off the PCB.
- Where You’ll See Them:
- Inside laptops and tablets, connecting the mainboard to the Wi-Fi/Bluetooth antenna.
- On drone flight controllers for video transmitters and receivers.
How to Select the Right PCB Connector
Okay, so that’s a lot of options. How do you actually choose the right one for your project? You have to weigh your electrical needs against your physical space and budget. Here’s a quick checklist with specific, verifiable details to guide your decision.
| Factor | Ask Yourself… | Why It’s a Big Deal |
| Current Rating (A) | How much power juice does this need to handle? | If you push 3A through a common JST-PH pin rated for only 2A, it will overheat, potentially melting the plastic housing and creating a fire hazard. |
| Voltage Rating (V) | What’s the highest voltage this will see? | For high-voltage designs (>30VAC or >60VDC), you need enough space between pins (creepage and clearance) to prevent a dangerous electrical arc. Safety standards like IEC 62368-1 dictate these minimum distances. |
| Signal Integrity | Am I sending very fast data signals? | High-speed data is sensitive. The wrong connector can act like a roadblock and corrupt your signal. Look for impedance-controlled connectors (50Ω or 90Ω) for protocols like USB 3.0, PCIe, or RF. |
| Pitch | How much space do I have? | Smaller pitch = more connections in a smaller area. A 1.0mm pitch allows twice the I/O density of a 2.0mm pitch connector in the same length. |
| Pin Count | How many separate signals (including power/ground) do I need? | Always plan for a few extra pins if you can. You’ll thank yourself later. |
| Mating Cycles | How often will this be plugged and unplugged? | A USB-C port is rated for at least 10,000 cycles. An internal FPC connector might only be rated for 10-20 cycles. Choose accordingly. |
| Environment | Will this be outside? Will it vibrate? Get hot? | A connector for a car engine needs to be way tougher than one for a TV remote. |
Note: Always check the manufacturer’s datasheet for a connector’s exact ratings. Never guess.
By understanding these main connector families, you can look at a circuit board and know exactly how it connects to other parts and the world. If you plan for your connector needs early, you will have fewer problems later in your design.
What’s Next?
You’ve now got a solid foundation. The next time you look at a circuit board, you won’t just see a sea of confusing plastic and metal. You’ll be able to spot the pin headers, identify the USB ports, and understand how the different parts of the system are designed to talk to each other.
From here, you can dive deeper into any of these categories. By understanding the main families first, you’re well on your way to mastering the world of PCB design.
Ready to find the right part for your project?
The best way to move from theory to practice is by exploring real-world components.
Browse the SOULIN product portfolio to see detailed specifications and drawings for all the connector types discussed in this guide.
Have a specific design challenge? Contact our engineering team. We can help you navigate the trade-offs and select the optimal connector for your application, whether it’s for consumer electronics, automotive systems, or industrial equipment.
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