COB surface light source, also known as chip on board packaging, is one of the bare chip mounting technologies. Semiconductor chips are transferred and mounted on printed circuit boards, and the electrical connection between the chip and the substrate is achieved by wire stitching, and covered with resin to ensure reliability. Although COB is the simplest bare chip mounting technology, its packaging density is far inferior to TAB and reflow soldering techniques. Therefore, COB surface light sources obtained through COB packaging are also known as COB light sources, COB flat light sources, COB integrated light sources, and ceramic COB light sources.