The Secret Sauce of an LED Flat Panel: the PMMA Light Guide Plate

Secret Inside An LED Flat Panel

While all LED flat panel lights may look the same on the outside, the difference can be found in one component, the “secret sauce” that’s sandwiched in between the layers: the light guide plate. It’s a sheet with a matrix of lines etched onto it that has the most important job in a flat panel luminaire: to transmit and direct light evenly outwards.


The Most Important Component in the LED Flat Panel

The Light Guide Plate is the most important piece and also the most expensive, depending on what material is used to make it. Quality flat panel ceiling lights use 100% polymethyl methacrylate (PMMA) a.k.a. acrylic, a lightweight material that’s so strong, it is used for spectator protection in hockey rinks and even for the ceiling of the Houston Astrodome. But cheaper flat panel lights may be using other materials, such as polystyrene (PS) (stuff used to make disposable cutlery and packaging) to make their light guide plates.

When it comes to comparing PMMA with PS, there’s clearly a difference of quality and cost.


Why Is Using PMMA To Make A Light Guide Plate Essential?

Using PMMA as the material for the light guide plate in a flat panel ceiling light means a premium luminaire that is designed to be trouble-free. Here’s three reasons why:

  1. PMMA has a high heat tolerance and resists UV light so they won’t yellow—ever. Flat panel lights that use other materials such as polystyrene in their light guide plates will yellow in as little as 8 months.
  2. Higher Efficiency. With a 92% light transmittance, PMMA allows more light to pass through while requiring less power, resulting in a higher lumens per watt. Other flat panel lights that don’t use PMMA make their drivers work harder and still cannot match the efficiency.
  3. Longer Life. Less power to achieve higher efficacy ensures the LED chips inside don’t get overworked (and don’t forget, you’ll avoid the ticking time bomb of a warranty nightmare because the panels won’t yellow!).


A PMMA Light Guide Plate is a Must for Flat Panel Ceiling Lights

PMMA Inside an LED Flat Panel Light


So next time you consider an LED Flat Panel, be informed and ask the manufacturer the question: what’s in your light guide plate?

Want to learn more about the components of an LED Flat Panel and how they work together to provide bright, uniform lighting? See Nick’s LED Flat Panel teardown video and our entire LED Flat Panel Ceiling Light collection.