COB (Chip on Board) LEDs are compact LED modules with a bright light output. They consist of a small square or circular substrate which houses multiple LED chips/dies. These are covered with a phosphor coating. The most common colour of COB LED is white, however there a few more colours available as the technology develops. How do they work?COB LEDs have a base substrate, made of aluminium or ceramic, on which the LED dies are mounted. The actual LEDs provide a blue light. The number of LED dies and their typical luminous flux determines the "brightness" of the COB LED.The layer of phosphor, which is an orangey-yellow colour, sits on top of the LED dies. The phosphor converts the blue LED dies into a white light. The type of phosphor creates different colour temperatures.What is colour temperature?Colour temperature describes the warmth or coolness of the LED light output. "Warm" COB LEDs offer a yellow-orange light output while "Cool" COB LEDs tend to be a bluer white. Colour temperature is measured in Kelvins with the symbol "K". What are the advantages of COB LEDs?• Higher LED density than traditional LED mounting process• No need for multiple soldering - just one package• Bright light outputUses for COB LEDs:• General purpose lighting• Downlights• High Bay lighting• Low Bay lighting• Spotlights• Solid State Lighting (SSL) replacements