Introduction to Keyboard Backlighting

Backlighting is a fantastic way to personalize your custom mechanical keyboard. It can range from a simple, functional white glow to a complex, animated light show. Understanding the basic components and types of lighting is the first step to creating the perfect aesthetic for your build.

At its core, keyboard backlighting is achieved using Light Emitting Diodes (LEDs). These tiny light sources are integrated into the keyboard's PCB and can be controlled to produce different colors and effects.

Two Flavors of Light: Single-Color and RGB

There are two primary types of LEDs used in keyboard backlighting:

Single-Color LEDs: These are the simplest form of backlighting. Each LED emits a single, fixed color (e.g., white, blue, red). They are typically less expensive and easier to implement. While you can't change the color, you can often control the brightness. These are great for a clean, minimalist aesthetic.
RGB LEDs: This is where the real magic happens. RGB (Red, Green, Blue) LEDs can combine these three primary colors to produce a vast spectrum of over 16 million different colors. This allows for complete customization, from setting a single static color for your entire board to creating complex, multi-colored animations.

The LEDs Themselves: Through-Hole vs. SMD

The physical form of the LED also matters:

Through-Hole LEDs: These are the more "traditional" looking LEDs with two long metal legs (an anode and a cathode). They are inserted through holes in the PCB and then soldered into place. They are often used for single-color backlighting and require a PCB that is specifically designed to accommodate them.
Surface-Mount (SMD) LEDs: These are tiny, compact LEDs that are soldered directly onto the surface of the PCB. They are the standard for modern RGB keyboards because they are small, bright, and can be pre-installed by the PCB manufacturer. They sit underneath the switch and shine up through a transparent switch housing.

Understanding these basic building blocks is key to making informed decisions about your keyboard's lighting. Are you aiming for a classic, understated look, or a vibrant, dynamic centerpiece?

Next, we'll dive deeper into the two main styles of illumination: Per-Key vs. Underglow.

Brightness, Power, and Safety Basics

Before you pick parts, it helps to understand how much power lighting draws and how to keep things safe and reliable.

USB power: Most wired keyboards draw power from USB. USB 2.0 typically allows up to 500 mA total device current; your controller, matrix, and accessories also consume some of that. Plan your LED current so you don’t exceed the budget.
LED current: A typical small SMD RGB LED can pull up to ~60 mA at full white (about 20 mA per color channel), but firmware usually limits this to a safer number (for example, 8–12 mA per color, or lower). Many boards enforce a global brightness cap to stay within limits.
Heat and reliability: High current means heat. Running at 100% brightness all the time shortens LED life and can cause color shift. Most people prefer 20–40% brightness for comfort and longevity.
ESD and handling: LEDs and controllers can be sensitive to static electricity. Ground yourself when handling bare PCBs and avoid dragging components across synthetic mats without an ESD strap.

Optics and Diffusion: Why Some Builds Look Better

Two keyboards with the same LEDs can look very different depending on how the light is guided and diffused.

Switch housings: Clear tops (or at least translucent) let more light reach the keycap. Opaque housings push light out the sides rather than through the legends.
Keycap plastic: PBT tends to be more opaque than ABS. “Pudding” keycaps have a translucent sidewall that amplifies RGB effects. Shine-through caps require double-shot or laser-etched legends designed for lighting.
Case materials: Frosted acrylic bottoms and mid-layers act like a diffuser for underglow, smoothing out hotspots between individual LEDs.
Diffuser films and light pipes: Some PCBs and cases include thin diffuser sheets or molded light guides that distribute light more evenly across the board.

LED Packaging: Package Size and Color Quality

Common addressable RGB footprints on keyboards include 3528 and 5050 packages, while per-key SMD LEDs are often in compact footprints placed right under each switch. A few color-quality notes:

Binning and consistency: Even quality LEDs have manufacturing variance. Using LEDs from the same reel improves color matching.
CRI and white tone: RGB-mixed “white” can look cool or greenish. If you care about a clean white, consider single-color white backlight or RGBW packages where available.

Compatibility Checklist

Run through this quick list before buying parts:

PCB supports the lighting you want (per-key, underglow, both).
Case exposes that lighting (clear tops for per-key, translucent bottom for underglow, or both).
Switches are SMD-friendly and/or have LED slots for through-hole installs.
Firmware (QMK/VIA/VIAL) supports your board’s LED driver and has enough flash to enable features you want.

Common Pitfalls to Avoid

Mixing opaque switch tops with shine-through expectations.
Expecting vibrant underglow in a solid metal case with no diffuser.
Overdriving brightness and then seeing USB disconnects or flicker when you type.
Forgetting that stabilizer housings can cast shadows—some layouts look better with per-key RGB disabled under long bars.

With these fundamentals, you’ll be able to choose parts that not only light up but look great and run reliably. Continue to the next page to compare styles in detail: Per-Key vs. Underglow.