COB stands for Chips on Board.
This is a new technology in the packaging of LEDs for lighting purposes. Essentially, many LED chips are integrated together on a single, good thermal conductor substrate without separate encapsulation. When lit, it looks like a continuous light panel without visible individual light points.
The reason for the development of this technology is to ensure that LED light sources with increasingly higher efficiency have a longer lifespan. This is achieved by emitting light over a larger surface area, and since there is no individual encapsulation, the substrate can dissipate heat over a large area and directly. Ensuring a lower operating temperature is the clear key to longer-lasting LED operation.
From a user experience perspective, the advantage of COB LEDs over other LED light sources is that because the light is generated over a larger, continuous area, it is possible to create designs that do not cause glare and yet provide adequate illumination. A traditional LED (DIP LED, SuperFlux, or Power LED, SMD LED) as a point light source can be very glaring. To reduce the glare caused by the strong light point, these LEDs often use optical lenses or etched glass surfaces, which all reduce efficiency. Although for other reasons, such as design, COB LEDs can also use matte finishes, lenses, or etched surfaces, fundamentally, COB LEDs are the least glaring and provide the most uniform illumination among LEDs.
It’s also worth highlighting the advantage of COB LEDs in creating line lighting. A traditional fluorescent tube provides even illumination over a relatively large surface due to the phosphor coating. If we replace this with an LED tube or LED strip, we either solve the problem of glare and ensure even illumination with a matte surface at the cost of reduced efficiency, or we allow the glare and ensure even illumination by placing the LED chips closer together. If spaced too far apart, we may get multiple shadows as shown in the picture below, while with a COB LED tube, we only get a blurred dark spot similar to a traditional fluorescent tube.
COB LED multi-chip packaging provides the same amount of light from a surface area 10 times larger on average, thus the amount of glare is considered to be one-tenth.
In short, we can say that a COB LED is a continuous LED array mounted directly on a thermal conductive plate. This kind of good heat dissipation can be achieved by other means as well. One such method is when individual SMD LEDs, which are normally individually packaged, are glued directly onto the thermal conductive plate instead of being individually packaged. This can also be considered a COB LED, as it is Chips on Board, but it does not provide a continuous light surface. The advantage is better efficiency due to the longer expected lifespan provided by good heat dissipation and the resulting higher load capacity. However, some manufacturers do not even call these COB LEDs; they simply refer to them as LED modules. It is possible that some distributors call them COB LEDs due to the similar principle, to make the product more attractive to customers.
The advanced version of COB LEDs is the MCOB LED.
MCOB LED Technology
MCOB stands for “Multi Cups / Chip on Board”. This means that the LED appears on multiple small surfaces, in several so-called cups, rather than on one large surface.
Since the goal in LED lighting technology remains to provide the highest possible luminous flux with the best possible efficiency, which fundamentally relies on even better thermal conduction, further developments have been made. According to the developers of MCOB technology, compared to the traditional copper-aluminum flat COB technology, they are better because the cups are coated with a reflective material and can reflect the light scattering due to the material structure. Thus, their optical utilization is better, and smaller LED groups are relatively more efficient. Overall, due to the larger proportion of heat-dissipating surface and the relatively smaller inter-reflection losses, multiple smaller COB LED groups produce more light with the same power consumption.
Ceramic COB LED
Obviously, as in the past, future developments will proceed along multiple lines. The technology companies advocating for larger COB LEDs also abandoned the copper-aluminum substrate for higher efficiency and are integrating the chip onto a ceramic substrate.
Generally, the efficiency of aluminum flat COB LEDs was considered to be 50-75 lumens/Watt, which lags behind almost any traditional encapsulated DIP or SMD LED.
In contrast, Ceramic flat COB LEDs have an efficiency of 100-120 lumens/Watt, while MCOB LEDs have 100-130 lumens/Watt.
The advantage of COB LED technology is that they are flat, i.e., thin, which is very advantageous for backlighting monitors, as the thinness of the display is a very important factor. This thinness is determined by two factors: the angle of illumination and the thickness of the LED panel. The thinness of the module is particularly advantageous for RGB COB LEDs, as only every third LED is the same color, so the thickness of the module is even more important for ensuring uniform color shade. The module is not only thinner, but the chips are also placed much closer together without encapsulation.