---
title: "What is a LED bulb made of?"
description: "Blue LED chips under a yellow phosphor, plus a driver circuit and a heat sink — and it is the driver that dies. Every component, the material it uses, and the constr"
url: https://atoneplace.net/made-of/led-bulb/
site: "At One Place"
---

# What is a LED bulb made of?

**What is a LED bulb made of?: Blue LED chips under a yellow phosphor, plus a driver circuit and a heat sink — and it is the driver that dies.**

The chip is rated for tens of thousands of hours, but the bulb frequently fails in two or three years, and the reason is nearly always the driver — specifically the electrolytic capacitors, whose life halves for roughly every 10 °C of temperature rise, in a sealed enclosure full of waste heat. Enclosed fittings and downlights in insulated ceilings make this much worse. The other everyday consequence of the electronics is flicker: cheap drivers pass a strong 100 or 120 Hz ripple, visible as banding in phone video and implicated in headaches, and dimmer compatibility problems come from the same place.

## Component by component

*Every material is a choice, and the third column is the constraint that drove it.*

| Part | Material | Why that material |
| --- | --- | --- |
| LED die | indium gallium nitride grown on a sapphire or silicon carbide substrate | InGaN is the material that finally produced an efficient blue LED, which is the discovery the 2014 Nobel Prize in Physics recognised. |
| phosphor | cerium-doped yttrium aluminium garnet, sometimes with a red-emitting phosphor added | It converts part of the blue light to yellow, and blue plus yellow reads as white — the red phosphor is what raises the colour rendering. |
| driver | a rectifier, capacitors and a constant-current controller | LEDs need low-voltage direct current; the mains does not supply that, so every bulb contains a small power supply. |
| heat sink | aluminium, or thermally conductive plastic | LEDs do not radiate their waste heat away like a filament; it has to be conducted out of the junction or the chip degrades. |
| diffuser | polycarbonate or acrylic with scattering particles | A bare chip is a painfully bright point source; the diffuser spreads it into something that resembles a lamp. |

## Other electronics objects

- [Alkaline battery](https://atoneplace.net/made-of/alkaline-battery/) — Zinc powder and manganese dioxide either side of a potassium hydroxide paste, in a steel can.
- [Smartphone screen](https://atoneplace.net/made-of/smartphone-screen/) — Chemically strengthened aluminosilicate glass over a touch layer and an OLED or LCD panel, with an oil-shedding coating on top.
- [Solar panel](https://atoneplace.net/made-of/solar-panel/) — Doped silicon wafers with silver contacts, sealed between low-iron glass and a plastic backsheet in an aluminium frame.
- [Touchscreen](https://atoneplace.net/made-of/touchscreen/) — A grid of transparent electrodes measuring the tiny capacitance your finger adds — which is why gloves fail.
- [Computer keyboard](https://atoneplace.net/made-of/keyboard/) — ABS or PBT keycaps over either a silicone rubber dome on printed film, or individual mechanical switches.
- [Headphones](https://atoneplace.net/made-of/headphone/) — A neodymium magnet, a coil of copper wire and a thin plastic diaphragm — a loudspeaker shrunk to fit an ear.
- [Loudspeaker](https://atoneplace.net/made-of/speaker/) — A paper or plastic cone hung on a rubber surround, driven by a coil in a magnet gap.
- [Computer mouse](https://atoneplace.net/made-of/computer-mouse/) — An ABS shell around a tiny camera taking thousands of pictures a second, plus two clicky microswitches and PTFE feet.

## Common questions

### What is a LED bulb made of?

Blue LED chips under a yellow phosphor, plus a driver circuit and a heat sink — and it is the driver that dies.

### What is the LED die of a LED bulb made of?

Indium gallium nitride grown on a sapphire or silicon carbide substrate. InGaN is the material that finally produced an efficient blue LED, which is the discovery the 2014 Nobel Prize in Physics recognised.

### What is the phosphor of a LED bulb made of?

Cerium-doped yttrium aluminium garnet, sometimes with a red-emitting phosphor added. It converts part of the blue light to yellow, and blue plus yellow reads as white — the red phosphor is what raises the colour rendering.

## Related pages

- [Alkaline battery](https://atoneplace.net/made-of/alkaline-battery/)
- [Smartphone screen](https://atoneplace.net/made-of/smartphone-screen/)
- [Solar panel](https://atoneplace.net/made-of/solar-panel/)
- [Touchscreen](https://atoneplace.net/made-of/touchscreen/)
- [Computer keyboard](https://atoneplace.net/made-of/keyboard/)
- [Headphones](https://atoneplace.net/made-of/headphone/)
- [Loudspeaker](https://atoneplace.net/made-of/speaker/)
- [Computer mouse](https://atoneplace.net/made-of/computer-mouse/)
- [Pencil](https://atoneplace.net/made-of/pencil/)
- [Tennis ball](https://atoneplace.net/made-of/tennis-ball/)
- [Banknote](https://atoneplace.net/made-of/banknote/)
- [Golf ball](https://atoneplace.net/made-of/golf-ball/)
- [Paper](https://atoneplace.net/made-of/paper/)
- [Glass](https://atoneplace.net/made-of/glass/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)