What are COB LEDs?

Chip-on-Board (COB) LEDs are high-power white LED arrays. They are sometimes nicknamed “fried eggs” (when they are not lit) because of their yellow phosphor circle on a white board.

COBs are made up of multiple chips/dies, usually with a minimum of 9 on a board. They are bright for their size, making them an alternative option to using lots of individual LEDs. They also cut out the need for soldering multiple times; it is just the one package.

The chips used in COBs are LEDs without their package. They are more compact and can be packed densely next to each other. These blue pumps are then coated with a phosphor layer (the yolk) which converts the blue light into the white light output. You cannot see the individual chips when lit - they look like a single uniform light source. This circular part is also referred to as a light emitting surface (LES) and comes in a range of different diameters.

COB LEDs from Lumileds

Although still a relatively new technology, there is a large variety of COBs already. Lumileds have a range of COB LEDs designed to suit a variety of applications. The Lumileds range includes:

• LUXEON COB Compact LEDs which have the smallest packages. They are ideal for retrofit and lighting in retail or at home.
• LUXEON COB Core LEDs which are the standard range for general lighting and industrial lighting. 
• LUXEON COB with CrispWhite Technology LEDs which are designed for retail applications. They create bright whites and saturated colours to compliment retail displays.

Lumileds Product Configuration

Lumileds part numbers contain a 4-digit number, for example 1202. This number explains the chip structure within the COB LED. So for example 1208 means 12 rows of 8 chips and 1211 would be 12 rows of 11 chips. It is handy to know how many chips are in the COB as obviously the more chips, the brighter it should be. A full part number breakdown can be found on the Lumileds data sheets.

COB Accessories

There is a large ecosystem of holders and lenses/optics designed for COB LEDs. For lenses, reflectors or holders, LEDiL have a wide range of products designed for LEDs, including COBs.

COB LED array holders provide a solderless alternative mounting method where you simply position the LED inside and twist the top of the holder to fasten.

If you need a high-power white LED, the COB could be a potential solution. They are a simple and easy-to-use light source with a high light output from a single package.

View the range of COB LEDs at RS here.

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