LEDs have been the top choices, be indoors or outdoors, for either hobbyist or commercial growers. But one big drawback of LEDs is their big size, making it hard to fit small spaces. That's why people invented one type of LEDs which are still powerful for most vegetative and flowering flower, while don't contain much space. That isCOB LED grow light.
But COB isn't just known for its compact size, it also has more light intensity, and advantages than traditional LEDs and other grow light types.
What are COB LEDs ?
COB, or Chip-on-Board, is the new LED technology. It has its name as the LED chips will be mounted onto the circuit board to create LED arrays. Because of the way COBs are built, COB LEDs reduce the components used and maximize the number of LED chips on the circuit. This makes COB LEDs have a number of advantages over the traditional SMD (Surface Mounted Device) LEDs.
The Differences Between COB LEDs And Traditional SMD LEDs
SMD (Surface Mounted Device) LEDs are the most common LED grow light you can find on the market. Though both SMDs and COBs share similar characteristics such as wide light spectral spectrum, long lifespan, and efficient light output, here are some of the key winning points of COBs over SMDs.

Improved Lumen Density
Since COBs can be packed with more LED chips on the same substrate than SMD, it has a stronger light intensity and higher uniformity.
More Focused Light
Because more led chips are contained within an area and with the support of a reflector, the light produced is denser. With the use of a reflector, you can have a stronger and more vibrant light intensity for flowering plants.
Smaller Size
A 200 lumen COB LED array can be much smaller than a 200 lumen SMD because COB makes better uses of the space.
Less Heat
Because fewer components are used to make these LEDs, and the thermal sink is pointed toward the circuit board, COBs tend to emit less heat than traditional LEDs. But the material of the COB substrate, the heat sink structure and the board circuit design play (Source) an important role in heat distribution. That's why you should look for a quality COB LED.

Why Choose COB LED Grow Lights?

The table below shows you that besides the cost, COB LED tends to win over other grow light types in every criterium. Let's blast through the details.
Light Intensity
This is the number one factor that affects your plant growth, especially flowering plants. Regarding this, COB LED is only behind HPS. It has a stronger light output than traditional LED grow lights and other light types.
Light Spectrum
All modern LED grow lights, including COB LEDs, are known for their widest spectrum wavelengths. Some bulbs also include 12-color spectrum colors, including IR (infrared ray) and UR (ultraviolet ray)
Heat Output
Heat ventilation is also a strong point of COB LED. Modern technology allows these LEDs to produce strong light output while controlling the heat emitted. Some high-end COBs also use quality substrate, drivers, fans, which control the heat to the minimum.
Size
Though COB LEDs with more power will be bigger, you'll never have such a compact light that still generate lots of light like COB, which makes it better suited for small areas.
Lifespan
Depending on the COB material build, most COBs can last from 30,000 - 60,000 hours. This is several times higher than other grow light types.