COB

COB or Chip-on-board LED, is a type of LED that consists of multiple LED chips mounted directly onto a substrate, typically made of metal or ceramic.  The chips are then coated with a phosphor layer that converts the blue light emitted by the chips into white light. A single COB  is made up of several LED chips arranged on a board or substrate that is thermally efficient. Every chip is a bare die, meaning it lacks a lens, phosphor coating, and lead frame. This implies that a very tight mounting of the chips on the substrate is possible. Compared to single packed LEDs, high intensity or light density can be emitted from a smaller area thanks to the near positioning of the LED chips. The entire array of chips is then uniformly coated with phosphor by the COB maker to transform the blue light into the necessary white color temperature.