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COB and SMD LED Chips What You Need to Know

Author: Site Editor     Publish Time: 2023-04-01      Origin: Site

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What is COB(Chip On Board)?

COB light source refers to the LED chip directly affixed to a highly reflective metal or ceramic substrate, integrating multiple chips in the inner substrate package, thus forming an overall light source.


It mainly solves the problem of low power chips that cannot produce high wattage LED lights, disperses heat from the chips, increases luminous efficiency and improves glare. COB light sources feature high flux density, less glare, soft light and a uniform luminous surface.


COB light sources are less costly as they eliminate the need for the bracket manufacturing process and do not require plating, reflow soldering and SMD processes. For the same power, COB lamps usually cost less than SMD lamps.


COB light sources can be simply understood as high power integrated surface light sources, which can be designed according to the shape of the product in terms of light emitting area and size. In the market, COB sizes are usually 11mm, 17mm, 20mm, 23mm, 32mm, 42mm and 60mm etc., and the power is usually greater than 3 watts.


Feature of COB LED Chips


Electrical stability is achieved through a scientifically and reasonably designed circuit, as well as an optimized heat dissipation design.

The use of heat sink technology ensures that the LED has an industry-leading heat lumen maintenance rate of 95%, resulting in a lifetime of over 50000 hours.

The product facilitates secondary optical matching, which improves the lighting quality and provides uniform luminescence without any spots. The COB chips used generally have a color rendering index of over 90, making them healthy and environmentally friendly.

The product is easy to install and use, reducing the difficulty of lamp design and saving costs associated with lamp production processing and maintenance.


Some of our COB LED Lights


COB LED Downlight

COB Chip LED Down Light

COB LED Solar  Light

SMD&COB  Chip LED Track Light


What is SMD(Surface Mounted Devices)?


  • SMD stands for Surface Mounted Devices and is a type of SMT component. Each light source contains only one or a few chips.

  • SMD light sources emit divergent light and are often used with reflectors when making LED lamps. Typically, their power is low.

They are best suited for large-scale use on aluminum substrates to create high-power products. The main SMD LED chips available include:



LED Chip Model

Size (mm)

Power (W)

Voltage and Current (V/A)

Lumen (lm)

Famous Brand (Manufacturer)

Lighting Application

2835

2.8 x 3.5

0.2-0.5

3.0-3.4/0.06-0.18

20-65

Sanan, Epistar

Home lighting, commercial lighting

3030

3.0 x 3.0

0.5-1.5

3.0-3.4/0.15-0.35

40-150

Lumileds, Cree

Indoor lighting, automotive lighting

3528

3.5 x 2.8

0.1-0.2

2.8-3.2/0.02-0.06

5-20

Sanan, Epistar

Home lighting, commercial lighting

5050

5.0 x 5.0

0.5-1.5

3.0-3.4/0.15-0.35

40-150

Nichia, Samsung

Indoor lighting, automotive lighting



Some of our SMD LED Lights

SMD LED  Track L ight

SMD Downlighter Recessed

SMD  LED Solar Light

SMD&CO B  Chip LED Magnetic  Light


What is the difference between COB and SMD chip?


The production process differs between the two.


  • SMD: LED chips are fixed onto the pad of the lamp bead holder with conductive and insulating glue, and then the chip's conductive performance is welded to the package, after which it is encapsulated with epoxy resin. The light is then split, cut, taped, and transported to the screen factory.

  • COB: LED chips are directly fixed onto the soldering pad of the lamp bead on the PCB board with conductive and insulating glue, and then the chip's conductive performance is welded. After the test is completed, it is encapsulated with epoxy resin.


The luminous effect differs.

  • SMD: The light-emitting surface of SMD LED chips is scattered, creating glare.

  • COB: The viewing angle of COB is large and easily adjustable, with no glare.


LED lights with COB chips typically have uniform, round spots with no astigmatism, black spots, or shadows. In contrast, LED luminaires with SMD chips have bright spots in the middle of the spot, halos on the outer edges, and uneven light spot transitions. You can use this difference to compare COB LED Downlights and SMD LED Downlights.


Packaging method: point source vs. multi-point source.


SMD: SMD packaging adopts surface mounting technology to attach multiple discrete LED chips to a PCB board to form a light source component for LED applications. It is a multi-point light source form.

COB: COB packaging is a highly efficient integrated light source technology. N chips are integrated and packaged on the substrate to manufacture high-power LED chips with small power chips, forming a uniform small light-emitting surface.


Different heat dissipation effects

COB light source has a dense arrangement of small chips, which generates a large amount of heat that is concentrated. The packaging material absorbs heat and accumulates it in the lamp body. However, it has a low thermal resistance heat dissipation method of "chip-glue-aluminum", which ensures good heat dissipation. SMD light source is limited by the packaging, and heat dissipation requires several steps including "adhesive-solder-solder-copper foil-insulating layer-aluminum", resulting in slightly higher thermal resistance.


However, in the production of high-power lamps, the scattered arrangement of chip-on-board (COB) light source creates a large heat dissipation area, and heat can be easily dissipated. The temperature of the whole lamp is acceptable for long-term use. Therefore, for the temperature of the whole lamp, the general SMD solution is better than the COB solution.


Different application areas

COB light source is generally used for indoor lighting such as spotlights and downlights, with a power of basically below 50W. Whereas SMD LED chips can be used for almost all indoor and outdoor lighting, and can be composed of different numbers and powers of SMD LED chips, even exceeding 2000W.


Different Color Rendering Index (CRI) The Color Rendering Index (CRI) of most SMD LED chips on the market is generally between 70-80, and some brands have CRI90 options, such as Osram SMD2835. Most COB chips have a CRI of 90 or above, and even up to CRI97, which is a good CRI. This is also why indoor commercial lighting with high index requirements often choose COB LED lamps.

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