TKL PCBs refer to the printed circuit boards used in tenkeyless mechanical keyboards. Tenkeyless or TKL keyboards provide a compact layout without the number pad section for more ergonomic positioning during gaming or regular typing.
This article will provide a detailed look at TKL PCB characteristics, layouts, components, build process, and design considerations. Read on to learn about crafting custom TKL keyboards using specialized PCBs tailored for the tenkeyless format.
What is a Tenkeyless (TKL) Keyboard Layout?
Tenkeyless mechanical keyboards were originally designed for gamers desiring more mouse space without compromising on key count.
As the name implies, TKL boards omit the number pad section of full-size keyboards. This allows placing the mouse closer while retaining the full alpha section, modifiers, function keys, arrow cluster, and main controls.
Common characteristics of TKL keyboards:
- Compact form factor without number pad
- Conserves desk space for mouse movement
- Standard ANSI keycap layout compatibility
- 87 to 89 total keys depending on bottom row
- Reduced weight compared to full-size
- Detachable USB-C cable for transportability
For users focused on typing rather than data entry, the TKL provides an optimized minimalist layout.
TKL PCB Design and Layout
The PCB is the heart of any TKL keyboard build. TKL PCBs arrange electrical connections and components to match the abbreviated TKL layout.
-maintain standard switch and stabilizer spacing
-accommodate required number of keys and switches
-retain typical keyboard matrix wiring for simplicity
-permit optional underglow RGB LED integration
-allow controller, connectors, and other components positioning
-provide bottom side anchor points for case mounting
-designed for easy DIY assembly and modification
Careful electrical and physical layout is crucial for a functional TKL PCB.
Essential Components on a TKL PCB
TKL PCBs host various components that support keyboard capabilities:
Microcontroller
The brain controlling the keyboard’s operation from scanning the matrix to executing user programmability. Popular choices are STM32, ATmega32U4, Elite-C.
Keyswitches
The mechanical switches providing the tactile user interface for typing. Compatible with MX style switches from Cherry, Gateron, Kailh and others.
Keycaps
The plastic keycaps that mount on switches and get pressed during typing. Follows conventional layouts.
Stabilizers
Bar mechanisms supporting wider keys like spacebar for level movement. Often PCB mount style.
Connectors
A USB-C connector allows connecting the keyboard to a host computer. Some PCBs also offer a daughterboard connector.
LEDs
Optional RGB LEDs seated in switch sockets provide underglow or per-key backlighting effects.
Passives
Support components like resistors, diodes for key matrix isolation, capacitors for power filtering.
Together, these elements comprise a fully functional TKL keyboard PCB assembly.
Design Considerations for TKL PCBs
Several considerations go into designing an effective TKL PCB:
Size – Matching a compact case footprint while fitting all required components. Microcontrollers with integrated USB reduce space needs.
Layer Count – 2 to 4 layer stacks allow routing dense switch matrix connections. Multilayer is not usually needed.
RGB Lighting – Under switch LED sockets require additional PCB real estate but allow flashy effects.
Hot Swap Support – Special connector pads for hot swapping switches without soldering adds complexity.
Debugging – Test points for debugging and validation require planning on the PCB.
Daughterboard – Some PCBs allow daughterboards for optional features like macros or audio.
Aftermarket Cases – Having mounting points and positioning that fits off-the-shelf enclosures expands options.
Cost – More layers or large form factors increase fabrication costs. Optimizing space reduces wasted PCB area.
The right tradeoffs result in a PCB optimized for the target keyboard build and budget.
TKL Keyboard PCB Fabrication
TKL PCBs can be fabricated using typical consumer PCB processes:
Material – FR-4 fiberglass offers sufficient performance at low cost. Metal-core or ceramic PCBs are overkill.
Layer Count – 2 to 4 layer designs allow complexity at accessible costs. Keep it minimum needed.
Trace/Space – 5/5 mil process enables high density routing for matrix connections.
Finishes – Immersion silver or ENIG are cost-effective finishes that support soldering and provide durability.
Coatings – Solder mask and silkscreen can add cosmetic appeal and legend text.
Via Construction – Plated through hole vias simplify interlayer connections compared to blind/buried vias.
Prototyping – Batching prototype PCB orders across customers reduces cost.
Leveraging standard amateur PCB fabrication processes keeps costs down without compromising keyboard functionality.
TKL Keyboard PCB Assembly
Assembling the components requires basic SMT production skills:
Stencils – Laser cut stencils allow solder paste application for SMD parts. Kapton or steel work well.
Solder Paste – SAC305 lead-free is commonly used. Dispensing rather than stencil printing simplifies amateurs.
Reflow – Small batch oven, hot plate, or heat gun reflow affords flexibility for prototyping.
Hand Soldering – Through-hole components can be hand soldered if needed.
Debugging – Test points and headers enable debugging the matrix, controller, LEDs, etc.
Programming – Firmware flashed into the controller configures the keyboard behavior as desired.
Case Integration – Mounting points on the PCB facilitate installation into aftermarket or custom cases.
With practice, even hobbyists can hand assemble TKL PCBs suitable for personal use. For production, outsourced professional assembly services are recommended.
Customizing and Modding TKL Keyboards
One benefit of DIY TKL builds is customizability:
Keymaps – Fully programmable controllers allow remapping keys and layers.
Key Switches – Hot swap sockets let users change switches for tuning feel.
Keycaps – Aftermarket keycap sets provide aesthetic personalization.
Acoustics – Case and switch choices modify the sound signature.
RGB Lighting – LEDs effects from reactive to mood lighting are software configurable.
OLED Screens – Some PCBs support add-on OLED screens for animations.
Daughterboards – Additional functionality like rotary dials can be added via daughterboard.
TKL PCBs designed for modding empower users to build truly personalized keyboards matching individual needs and preferences.
TKL Keyboard PCB Examples
Some popular examples of PCBs designed for TKL customs builds include:
- KBD8X MKII – Compact tenkeyless board with RGB underglow and daughterboard support.
- Wavez Green TKL – Green themed silkscreen graphics and edge glow LED integration.
- Mode Eighty – Premium machined aluminum case paired with solderable or hotswap PCB.
- NK87 Entry Edition – Budget plastic case and plate paired with premium PCB featuring underglow.
- KBD Fans TKL – Value priced DIY kit with VIA compatibility and RGB underglow.
There are numerous PCB options at different price points for custom TKL keyboard builds.
Conclusion
TKL PCBs enable compact tenkeyless mechanical keyboards retaining just the most useful keys for gaming and typing. Thoughtful electrical layout and physical design create feature-packed PCBs supporting modern keyboard customization. For keyboard enthusiasts, developing custom TKL PCBs provides exciting opportunities to build exactly the keyboard they want.
Frequently Asked Questions
What is the easiest way for a hobbyist to get a custom TKL PCB made?
Many online PCB prototyping services like JLCPCB, PCBWay, and OSH Park allow ordering custom keyboard PCBs in low volumes at reasonable costs. They handle fabrication based on the uploaded design files.
What are some good ways to reduce costs for hobbyist TKL builds?
Using DIY kits of generic components, sharing common components across projects, panelizing PCBs, using the simplest adequate PCB process, and buying in bulk can help reduce total build cost.
How can you add wireless connectivity to a TKL keyboard PCB?
A daughterboard with a Bluetooth module can be connected via socket on the main PCB, allowing wireless communication while keeping the main board simple.
How thick should the PCB substrate be for durability?
The standard 1.6 mm thickness is typically adequate for keyboard PCBs. Metal or thicker boards are unnecessary and only increase cost without significant benefit.
What are some innovations happening with TKL PCBs?
Some innovations are transparent materials for integrated see-through case lighting, flexible PCBs for ergonomic curved housings, ultra compact layouts squeezing in more keys, and modular daughterboards for expandability.
