COB (Chip On Board), is a relatively newer LED technology.
COB LEDs are basically multiple LED chips (typically nine or more) bonded directly to a substrate by the manufacturer to form a single module. Since the individual LEDs used in a COB are chips and not traditionally packaged, the chips can be mounted such that they take up less space and the highest potential of the LED chips can be obtained. When the COB LED package is energized, it appears more like a lighting panel than multiple individual lights as would be the case when using several SMD LEDs mounted closely together.
Advantages of COB LED Technology
- The light emitting area of a COB LED contains many times more light sources in the same area than standard LEDs could occupy resulting in significantly increased PPFD values.
- COB LEDs use a single circuit with just two contacts to energize the multiple diode chips it houses. This results 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.
- 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.
With regards to grow lights COB LEDs are typically biased towards the blue and red wavelengths but typically offer a much more full spectrum than lighting panels with multiple individual lights. Figure 1, below, shows the "McCree curve". This data from a 1972 paper by Dr. McCree and Dr. Inada who performed several studies in the to determine the influence of light spectra on photosynthesis. Below in Figure 2 you will see the typical emission spectrum from the Sun, an HPS bulb, and the COB design that Indo Products uses. Figure 3 shows the emission from other LED panels, which are missing much of the PAR potential of a light. You will notice in Figure 3 that the emission is missing much of the light that is part of photosynthesis and therefore will likely not be as effective with plant growth if that is the only source of light a plant receives.
Figure 1.
Figure 1. Indo COB LED Spectrum
Figure 2. Typical LED Panel
