Keyboard PCBs: How to Build Custom Mechanical Keyboards

What are Custom Keyboard PCBs?

A custom keyboard PCB is a printed circuit board designed specifically for a particular keyboard layout and feature set. Unlike mass-produced, off-the-shelf keyboards, Custom PCBs allow for greater flexibility in terms of key placement, functionality, and aesthetics. They are the foundation upon which a custom mechanical keyboard is built, connecting the switches, stabilizers, and other components to create a functional input device.

Types of Custom Keyboard PCBs

There are several types of custom keyboard PCBs available, each with its own set of features and compatibility:

1. Through-hole PCBs: These PCBs require soldering switches directly to the board, with pins protruding through the holes. They are easy to work with and offer a sturdy connection.

2. Hot-swappable PCBs: Designed for easy switch replacement, hot-swappable PCBs feature sockets that allow users to install and remove switches without soldering.

3. SMD PCBs: Surface-mount device (SMD) PCBs have components mounted directly on the surface of the board, resulting in a sleeker appearance and reduced overall thickness.

4. Split PCBs: Split keyboards consist of two separate PCBs connected by a cable, allowing for a more ergonomic typing experience.

5. Wireless PCBs: Some custom PCBs incorporate wireless functionality, enabling users to connect their keyboards to devices via Bluetooth or other wireless protocols.

Designing Custom Keyboard PCBs

Designing a custom keyboard PCB involves several key considerations:

Keyboard Layout

The first step in designing a custom PCB is determining the desired keyboard layout. This includes the number of keys, their arrangement, and any additional features such as a number pad, function keys, or macro keys. Popular layouts include:

• 60% (61 keys)
• 65% (68 keys)
• 75% (84 keys)
• Tenkeyless (87 keys)
• Full-size (104 keys)

Switch Compatibility

Different switches have varying pin configurations, so it’s essential to ensure that the PCB is designed to accommodate the chosen switch type. The most common switch types are:

• Cherry MX
• Gateron
• Kailh
• Alps

Firmware and Programmability

Custom keyboard PCBs often support programmable firmware, such as QMK or VIA, which allow users to customize key mappings, macros, and lighting effects. When designing a PCB, consider the desired level of programmability and ensure compatibility with the chosen firmware.

Electrical Components

A custom keyboard PCB requires various electrical components, such as:

• Microcontroller (e.g., ATmega32U4, STM32)
• Diodes (for preventing ghosting)
• Resistors
• Capacitors
• USB connector
• TRRS jack (for split keyboards)

PCB Design Software

To create a custom keyboard PCB, you’ll need to use PCB design software. Some popular options include:

• KiCad
• Eagle
• Altium Designer
• EasyEDA

These software tools allow you to create schematic diagrams, design the PCB layout, and generate manufacturing files.

Manufacturing Custom Keyboard PCBs

Once your PCB design is complete, you’ll need to have it manufactured. There are several options available:

PCB Fabrication Houses

PCB fabrication houses specialize in manufacturing PCBs based on provided design files. They offer a range of materials, finishes, and turnaround times. Some popular PCB fabrication houses include:

• JLCPCB
• PCBWay
• OSH Park
• Seeed Studio

In-House PCB Milling

For small-scale prototyping, you can use a PCB milling machine to create PCBs in-house. This process involves using a small CNC machine to route copper traces on a blank PCB substrate. While this method is more labor-intensive and time-consuming than using a fabrication house, it allows for rapid iteration and testing.

Assembling Custom Mechanical Keyboards

With your custom PCB manufactured, you can begin assembling your mechanical keyboard. The process typically involves the following steps:

1. Soldering switches: If your PCB is not hot-swappable, you’ll need to solder the switches to the board. Ensure that the switches are oriented correctly and seated firmly before soldering.

2. Installing stabilizers: Stabilizers are used for larger keys, such as the spacebar, enter, and shift keys, to prevent wobbling. Install them according to the manufacturer’s instructions.

3. Mounting the PCB: Place the PCB into the keyboard case and secure it using the provided mounting points. Ensure that the USB connector and any other ports are properly aligned with the case cutouts.

4. Connecting the USB cable: Solder the USB cable to the PCB or connect it to the pre-installed USB port.

5. Installing keycaps: Finally, install the keycaps onto the switches, ensuring that they are properly aligned and seated.

Firmware and Programming

After assembling your custom mechanical keyboard, you’ll need to flash the appropriate firmware and configure the key mappings and other settings. The process varies depending on the chosen firmware, but generally involves the following steps:

1. Downloading the firmware: Obtain the firmware files for your specific keyboard and PCB combination from the manufacturer’s website or repository.

2. Flashing the firmware: Use a firmware flashing tool, such as QMK Toolbox or dfu-programmer, to load the firmware onto the keyboard’s microcontroller.

3. Configuring the firmware: Use the firmware’s configuration tool or text editor to customize key mappings, macros, and lighting effects according to your preferences.

4. Testing and fine-tuning: Test your keyboard to ensure that all keys and features are working as intended. Make any necessary adjustments to the firmware configuration.

Frequently Asked Questions (FAQ)

1. What is the difference between a custom keyboard PCB and a pre-built PCB?
   A custom keyboard PCB is designed and manufactured according to your specific requirements, while a pre-built PCB is mass-produced and offers limited customization options.

2. Do I need prior electronics experience to design a custom keyboard PCB?
   While prior electronics experience is helpful, it is not strictly necessary. There are numerous resources, tutorials, and communities available to guide you through the process.

3. How much does it cost to manufacture a custom keyboard PCB?
   The cost of manufacturing a custom keyboard PCB depends on factors such as the PCB size, complexity, material, and quantity. Expect to pay anywhere from $20 to $100 or more per PCB, with prices decreasing for larger quantities.

4. Can I use any switch type with a custom keyboard PCB?
   Most custom keyboard PCBs are designed to be compatible with a specific switch type or family. Ensure that your chosen switches are compatible with your PCB before purchasing or designing.

5. What should I do if my custom keyboard is not working after assembly?
   If your custom keyboard is not functioning correctly after assembly, first check for any visible soldering issues or loose connections. Ensure that the firmware is properly flashed and configured. If the problem persists, consult the manufacturer’s support resources or seek assistance from the mechanical keyboard community.

Conclusion

Building a custom mechanical keyboard with a custom PCB is a rewarding and enjoyable process for enthusiasts seeking a truly unique and personalized typing experience. By understanding the types of custom PCBs, design considerations, manufacturing options, and assembly processes, you can create a keyboard that perfectly suits your needs and preferences.

Remember to take your time, consult resources and the community when needed, and enjoy the journey of creating your own custom mechanical keyboard. With patience and perseverance, you’ll soon be typing on a one-of-a-kind input device that reflects your individual style and requirements.