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COB Grow Lights

History Of COB Grow Lights

Over the last few years COB (Chip On Board) LED based light sources have been developed, COB uses a film of phosphor film over LEDs to create the spectrum of visible light between 2000k and 6500k, used mostly for High-output commercial and general lighting purposes. Today’s High-Tech Phosphor coatings can be designed to create a blend of light plants thrive under. 

MCOB (Multiple Chips On Board) allows for perfect horticultural light efficiency and spectrum mixing by placing chips of different spectrum very close together

cob led spectrum

COB (and MCOB) LEDs are more adaptable for indoor horticulture than any other light source including traditional designed “High Power” LED panels and arrays, its incomparable light efficiency and spectrum-mixing ability providing a better lighting combination for plant growth, both in vegetative stage and blooming stage. Properly engineered phosphor films for COB can provide superiority in actual growth performance.

cob series grow light vs high power 3w 5w series

MCOB Challenges 


mcob led

Due to its special structure of encapsulation of LEDs on board, MCOB usually faces bigger challenge on heat-sinking than any high power 3W/5W series grow light, a cluster of LEDs in a very narrow space (24mm×24mm) will generate incredible heat in a very short time, so “Active” heat-sinking will be the key factor to the lifetime of both MCOB and COB LED grow light.

The past two years have seen an increase of COB LED for grow lights, however off the shelf COB are not designed for Horticulture and in fact are designed to use in interior and exterior lighting. Horticultural COB are developed especially for indoor gardeners of all types.

New COB from Growthstar

Growthstar’s focus has been on horticultural LED grow light since 2010, now we are producing MCOB and COB technology with proven production, function, design and price.

Keeping our COB cool with heat-sinking solutions matters most to the lifetime of our LED grow lights, not just the heat-radiator, but actual COB frame, because when LEDs are powered-on, the temperature at the core area of COB will reach very high levels, and much heat is consequently generated, if the heat is not able to be dissipated quickly, the lifetime of LEDs and phosphors in COB will be diminished.

Compared to regular COB frame that most companies adopted, Growthstar adopts global leading thermo-electric separation technology; it is not only most stable COB frame, but also has ultra-transmission, heat-sinking, that will dissipate the heat very quickly, its heat-transmission rate is 58% faster than standard COB model, thus the lifetime of COB is dramatically improved.

Growthstar COB frame      growthstar cob frame



Growthstar MCOB frame      mcob frame growthstar


Only Growthstar’s new copper COB frame applies a gold-plated layer over the COB for optimum thermal management and helping to prevent oxidization.

Heat-radiator for COB

COB (MCOB) should be mounted to heat-radiators for heat-sinking, compared to normal heat-radiator in the market, Growthstar uses the best heat-radiator with thermo-tube technology, its excellent heat-sinking performance supports up to 150W frames!

heat-radiator cob light

Traditional sunflower heat-radiator is only able to support less than 50W COB

Traditional sunflower heater

cob grow light test


mcob vs cob grow light


MCOB and COB share same metal frame, they are in two kinds of encapsulation of LED in different ways, and produce different result and hence different growth results.

What are the main differences of the two MCOB and COB: 


Multiple Chips On Board create a full spectrum, each LED has different kinds of color or bandwidth, from 380 – 740/850nm, and theoretically, it is able to achieve any kind of spectrum blend, even pure white light. These color ratios are customizable to cultivators or growers’ specific requests -   MCOB also supports multi-channel, dimmable function, so we can adjust different spectrum to realize the color blend needed for different plant growth.

2 Spider Pro MCOB analysis 

2 Spider Pro MCOB Analysis

  -   As there are different kinds of LEDs on the COB frame, so its cost is relatively much higher due to production time, labor cost of encapsulation and cost of LED are relatively higher; 

  -   Compared to TS COB, the light attenuation is relatively much smaller, which makes it enjoy longer lifetime, and we can drive with higher electric currency (500-700mA) for higher lumen output.



  -  COB (first Generation) came with two peak spectra only, red and blue 

3st Gen COB

  • Growthstar COB

Figure 4 Growthstar COB

   -   COB is made with one layer of blue LEDs on which applied with florescent powder (630nm or 660nm), when this powder is activated with electricity, it will generate excitation light based on blue color LED, so you can see the red peak spectrum on the above spectrum, the reason why you can see the green or even 740, 780nm and so on, it is from the excitation light, but such excitation light is also useful to the plant growth.

   -   COB is not able to support dimmable function;

   -   COB light source is becoming more and more popular for greenhouse use, like some LED bar products, as it is more economical to greenhouse investors, like for tomato, vegetables, etc. 

   -   As there is only blue LED only in the COB, so its cost is relatively lower, florescent powder is very weak in attenuation-resistance, so use 300 – 350mA to drive the LED, thus the attenuation resistance will be controlled in a reliable range.

Depending on the wattage, there are two kinds of heat-radiator:  Thermo-tube heat-sinking radiator and our proprietary design Sunflower heat-sinking radiator

  Thermo-tube heat-sinking radiator


 -  Testing of temperature of core are of COB, we found that sunflower heat radiator is fine, when actual wattage of COB is less than 80W, , and thermo-tube heat radiator is only needed for higher power MCOB, like 64/68/80×3W COB.

 cob grow lights

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