Connecting two PCB (Printed Circuit Board) boards together can be done in several ways, depending on your requirements for durability, flexibility, space, and cost. Here are some common methods:

1. Pin Headers and Sockets:
   • Description: This involves soldering a male pin header onto one PCB and a female socket onto the other.
   • Pros: Easy to connect and disconnect; provides a strong mechanical connection.
   • Cons: Takes up more vertical space; may require alignment during assembly.
2. Ribbon Cables:
   • Description: Ribbon cables use flat cables with multiple wires to connect between two PCBs.
   • Pros: Flexible and can connect boards that are not directly aligned; good for parallel connections.
   • Cons: Can be bulky; requires connectors on both boards.
3. Flexible Flat Cables (FFC) or Flexible Printed Circuit (FPC):
   • Description: These are thin and flexible cables that are soldered or clamped to each PCB.
   • Pros: Highly flexible, ideal for compact spaces; lightweight.
   • Cons: Can be fragile; requires careful handling during assembly.
4. Board-to-Board Connectors:
   • Description: These are connectors specifically designed to join two PCBs. They come in various configurations, such as mezzanine, coplanar, or orthogonal.
   • Pros: Reliable and robust connections; available in many sizes and pin configurations.
   • Cons: More expensive; specific design requirements.
5. Edge Connectors:
   • Description: One PCB has edge connectors that fit into a slot on the other PCB.
   • Pros: Allows easy swapping of boards; commonly used in modular designs.
   • Cons: Requires precise alignment and design; may wear out with repeated use.
6. Soldered Wires:
   • Description: Directly soldering wires between the two boards.
   • Pros: Simple and cost-effective; good for permanent connections.
   • Cons: Less flexible and can be prone to breaking if moved frequently.
7. Wireless Connections:
   • Description: Using wireless technologies like Bluetooth, Wi-Fi, or Zigbee to communicate between boards.
   • Pros: No physical connectors needed; ideal for remote connections.
   • Cons: Requires additional components and power; potential for interference and latency.

When choosing a method, consider the electrical requirements, mechanical constraints, and environmental factors your project might face. For instance, if you need to frequently disconnect the boards, a pin header might be more suitable, whereas for compact devices, FPC might be a better choice.

Source: ChatGPT