COB LED

The latest LED improvement has been “Chip On Board” or COB innovation. A COB (Chip-on-Board) is an LED packaging technology that describes mounting multiple LED chips directly onto a substrate to form a single module.  

Multiple LEDs, minuscule in size, are wired and packaged together into a single ceramic or copper board so that they function as a sole light source.​

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, usually with a minimum of 9 on a board. Due to the small size of the LED chips (imagine a quarter), Chip-on-Board technology allows for a much higher packing density than surface mount technology (SMD).

COB chips only have 1 circuit and 2 contacts, regardless of the number of the diodes. When a COB LED package is energized, it appears more like a lighting panel than multiple individual lights as usually the case with other LED packages, like when using several SMD LEDs mounted closely together.

​They are bright for their size, making them an alternative option to using lots of individual LEDs. COB LEDs are still LEDs, they’re basically the same technology in a different package. So there isn’t much to compare other than light distribution. While COB LEDS do provide an excellent light intensity, they’re not exactly the best when it comes to spread, because COB LEDs are a single-point light source (meaning all light comes from a single point in space).

And this is where small SMDs have an advantage over a COB LED, being of such a small size you can place many of them very close to each other and form a light panel. The problem here is ensuring that the LEDs have enough light intensity to justify the increased cost of manufacturing such a panel.

In mass-produced devices that utilize high-power LEDs, passive thermal management devices may be built into the device, such as cooling fins integrated into the head of a streetlight post. 

Advantage of COB LEDs

• Being multi-chip packaged, the light emitting area of a COB LED can contain many times more light sources in the same area that standard LEDs could occupy resulting in a greatly increased lumen output per square inch.
• COB LEDs use a single circuit with just two contacts to energize the multiple diode chips it houses. This result in fewer components required per LED chip for proper operation. 
• Furthermore, the reduced components, along with the elimination of the traditional LED chip structure packaging, can reduce the heat generated from each LED chip. 
• The ceramic/aluminum substrate of COB LEDs also acts as a higher efficiency heat transfer medium when coupled to an external heatsink, further lowering the overall operating temperature of the assembly. 

• When mounting a COB to a heatsink, care must be taken to choose a heatsink capable of dissipating the heat generated to enable a COB to be used to their full potential. In the long run, the proper heat dissipation increases efficiency and lowers failure rates.
• Another aspect of COB LEDs that reduces failure rates is the fact that spot soldering of the individual LED chips is not necessary as each chip is directly mounted onto the substrate. The smaller amount of welding points results in lowering the rate of failure.