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
| 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 Zinc powder and manganese dioxide either side of a potassium hydroxide paste, in a steel can.
- 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 Doped silicon wafers with silver contacts, sealed between low-iron glass and a plastic backsheet in an aluminium frame.
- Touchscreen A grid of transparent electrodes measuring the tiny capacitance your finger adds — which is why gloves fail.
- Computer keyboard ABS or PBT keycaps over either a silicone rubber dome on printed film, or individual mechanical switches.
- Headphones A neodymium magnet, a coil of copper wire and a thin plastic diaphragm — a loudspeaker shrunk to fit an ear.
- Loudspeaker A paper or plastic cone hung on a rubber surround, driven by a coil in a magnet gap.
- 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 Zinc powder and manganese dioxide either side of a potassium hydroxide paste, in a steel can.
- 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 Doped silicon wafers with silver contacts, sealed between low-iron glass and a plastic backsheet in an aluminium frame.
- Touchscreen A grid of transparent electrodes measuring the tiny capacitance your finger adds — which is why gloves fail.
- Computer keyboard ABS or PBT keycaps over either a silicone rubber dome on printed film, or individual mechanical switches.
- Headphones A neodymium magnet, a coil of copper wire and a thin plastic diaphragm — a loudspeaker shrunk to fit an ear.
- Loudspeaker A paper or plastic cone hung on a rubber surround, driven by a coil in a magnet gap.
- Computer mouse An ABS shell around a tiny camera taking thousands of pictures a second, plus two clicky microswitches and PTFE feet.
- Pencil Stationery and paper
- Tennis ball Sport and games
- Banknote Around the house
- Golf ball Sport and games
- Paper Stationery and paper
- Glass Building materials
Sources
- Typical range compiled from manufacturer specifications — At One Place