What is cob led chip types and Why Do We Use Them?

What is COB LED ? This latest innovation has already significantly impacted the lighting and display industries. Yet, despite the improvements it can provide, especially with LED displays, many people remain unfamiliar with it. 

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Read on to learn about what COB LED technology is, how it works, and why it‘s the way forward or go ahead and visit ViewSonic’s latest COB LED Display solutions.  

COB LED, or chip on board light-emitting diode is the latest innovation in the field of LED technology. It provides numerous improvements and has already made waves in a few key areas, including lighting and LED display devices. Although greater reliability, energy efficiency, and image quality define most prominent advantages, many customers are still unfamiliar with COB LED display technology and the way it actually works.  

In this article, we will explore what chip on board LED technology means, how it’s relevant to display devices and how it differs from other established LED packaging technologies. We’ll also discuss in detail the above-mentioned primary benefits of the COB approach. 

COB LED Technology Explained

 

Chip on board (COB) technology is a method of directly mounting red, green, and blue chips onto a printed circuit board (PCB). Packaging the bare chips directly onto the PCB enables a much higher chip density while creating a flat uniform LED surface. The combination of three-color values allows the chips to achieve a higher color gamut and replicate true-to-life imagery. 

In other words, with COB LED technology, the number of LEDs that can be placed in any given area of a display is way higher than with other LED packaging approaches, such as Surface Mounted Diode (SMD) and Dual in-line Package (DIP). 

Occupying less space on the board without any bonding wires allows for a tighter pixel pitch. The tighter the pixel pitch, on the other hand, the higher resolution. This is one of the reasons behind COB’s breakthrough in the LED packaging world. The potential of improving image quality, reliability, and energy efficiency of a display is huge and will be only further explored in various future applications. 

 

SMD vs. COB Packaging Technology

 

Before the emergence of the latest COB LED technology, display devices using LEDs relied on other LED packaging processes. The two most common types were SMD and DIP. As the SMD offered superior density and array power, it quickly emerged to be the most popular choice for LED displays. 

SMD technology works by using bonding wires to mount the components on the surface of the PCB. This is done using a soldering machine that applies heat and pressure to the joints to create a permanent connection. While this initially represented a major improvement over other techniques, if the soldering is not controlled accurately properly, there’s a bigger risk of weak points in that connection. They may be too weak or too strong, leading to failure. 

Besides, SMD components are more susceptible to damage from external factors such as heat and humidity or collision. Since the components are mounted on the surface of the circuit board, they are exposed to the environment and can be easily damaged by external factors. 

In contrast, COB technology involves bonding the components to the circuit board using an adhesive, which can provide a more robust and reliable connection. This makes COB technology less susceptible to failure due to external factors and soldering issues. Not needing the bonding wires is also what enables a finer pixel pitch.   

Finally, SMD technology is generally limited to components that are larger than 0.5 mm, while COB technology can be used with much smaller components, down to a few micrometers in size. 

Benefits of COB LED Technology

 

With an understanding of what chip on board technology is and how COB LED technology differs from competing technologies, let’s explore what it can do.  

1. Superior Pixel Pitch

 

Essentially, pixel pitch is a measurement of the density of pixels and refers to the distance between the center of one pixel and the center of an adjacent pixel. One of the biggest benefits associated with COB LED technology for display devices, including wall displays and other large-format displays, is precisely the improvements to the pixel pitch. The smaller the pixel pitch, the higher the pixel density thus the higher resolution. The COB LED displays can deliver the tightest pixel pitch which translates to a resolution of up to 4K. 

The praised improvements to pixel pitch provided by COB technology are most noticeable when using a display up close because a smaller pixel pitch and higher pixel density will reduce the viewing distance. This means that viewers will be able to stand close to a display and still view it comfortably without noticing the individual pixels.  

2. Improved Reliability

 

When compared to LCD, any LED display will be less impacted by issues like the surrounding environment and various lighting conditions. Once the screen has been set up, it can be used in differently lit situations, without the need to recalibrate the screen. 

Among LED displays, the major benefit of COB LED technology specifically, is its improved reliability including water-proof, dust-proof and anti-collision capabilities. The previously mentioned reduction in soldering sites minimizes the possible points of failure. This translates overall to better thermal performance, facilitated maintenance, and, ultimately, peace of mind. Additionally, mounting the LEDs directly on the board also improves moisture- and dust resistance as the surface is protected by a durable clear epoxy resin. 

According to the Ingress Protection (IP) rating that defines the level of protection against the ingress of solid objects, dust, and water, COB technology scores IP54 which is a high score for LED displays (by comparison, SMD scores only IP20 or IP30). 

3. Great Energy Efficiency

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In general, LED technology is more energy efficient than its alternatives, including LCD displays. By the same token, LED technology helps to make display devices much less expensive to operate on a day-to-day basis. 

COB LED technology delivers higher energy efficiency than SMD. This is important when it comes to the total cost of operation for large format displays that are going to be used all day, every day for months and years to come. 

4. Enhanced Viewing Experience

 

Finally, COB LED technology has the potential to provide a better all-around viewing experience. While the process of connecting LED chips directly to the printed circuit board allows a COB LED display to deliver a higher contrast ratio, the adoption of flip chips provides wider viewing angles (170 degrees).  

COB Technology also drives 4K resolution. This is of paramount importance for large-format displays used in places that need detailed and intricate visuals such as research institutions, engineering facilities, schools of architecture, or fine arts.  

When compared to SMD technology, COB LED displays deliver a higher contrast ratio, smoother surface, and better reliability. COB LED technology can result in much-improved brightness and deeper blacks which is great for use indoors where plenty of natural light is present like car exhibition centers, architectural studios, hospitals, and other places that need images of high resolution.  

The very best COB LED displays on the market, such as the ViewSonic LDP163-091 and LDP216-121, will combine these improvements with an excellent color gamut and higher contrast ratio, for the ultimate viewing experience and real-to-life color. 

Final Thoughts

 

Chip on board or COB LED technology is the latest breakthrough in LED packaging technology and delivers especially great results when used in display devices. It tightens pixel pitch, boosts brightness, and improves viewing angles and viewing distances while providing greater long-term reliability and anti-collision, energy efficiency as well as better dust and moisture resistance. 

If you like reading this article, be sure to also explore Direct view LED video wall vs LCD video wall: What’s the difference? or go straight to ViewSonic’s LED Display solutions. 

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What are CoB LEDs?

LUXEON CoB Finder

A CoB LED (or chip-on-board LED) is a single device with many LED chips mounted on a thermally efficient substrate placed below a uniform phosphor coating.

Anyone who walks through a store or home with recessed or track lighting likely experiences light from a chip-on-board LED (CoB). CoBs are widely used because they emit a bright white light output from a compact light source and are very efficient in a broad range of applications.

So what is a CoB LED, and how is it different from other types of LEDs?

CoB (chip-on-board) refers to the way in which the LED unit is constructed. The basic elements of white CoB LEDs are:

• An electrical power supply to provide the energy to drive the LED
• The light-emitting chip or ‘die’. This is sometimes referred to as the blue light pump, and is made of a semiconductor material, indium gallium nitride (InGaN), which emits blue photons when energized
• A phosphor coating which converts the blue light to white. The chemical composition of the phosphor is controlled to produce light of a specific color temperature

CoB LED cutaway showing multiple connected LED chips on a board underneath a uniform phosphor coating.

CoB LED: Space-Saving Array of Multiple LED Chips

A CoB LED is a single device with many LED chips mounted on a thermally efficient substrate, or board. Each chip is a bare die – that is, the chip does not have its own leadframe, phosphor coating or lens. This means that the chips can be mounted extremely closely together on the substrate. The close placement of the LED chips allows for high intensity or light density to be emitted from a smaller area than is possible with single packaged LEDs. The CoB LED manufacturer then applies a uniform phosphor coating to the entire array of chips to convert the blue light to the required white color temperature.

An interactive 3D diagram of a CoB LED.

Advantages of a CoB LED

A single CoB LED can contain hundreds of chips forming a dense array. This dense array enables a CoB LED to produce more light output from a smaller area than is generally possible with an array of packaged LEDs.

Using a single LED can result in simpler design and product as well as providing optical advantages for uniform light and efficient optics.

Electrical design is simpler because the CoB LED only requires a single two-wire power supply to the entire array of chips. The positive and negative terminals on a CoB LED are clearly visible in the picture of LUXEON CoB Core Range products above. By contrast, an array of packaged LEDs requires dedicated power supply traces to be routed on the PCB to each LED unit.

Production is simpler because the number of units to be soldered to the board will be lower if a CoB LED is used instead of an array of packaged LEDs.

Optically, a broad range of optics, usually reflectors, can be used with CoBs of different sizes to determine the direction and width of the beam such as with a spot or flood lamp.

Finally, a CoB LED’s color is potentially more consistent because a single phosphor coating is applied to the entire array of chips, whereas in an array of packaged LEDs, each LED unit has its own phosphor coating.

An example of CoB LEDs of various sizes is shown below.

Lumileds LUXEON CoB Core Range – High Density CoB LEDs.

CoB LEDs from Lumileds

Lumileds supplies a comprehensive range of CoB LEDs for general lighting, as well as CoB LED products optimized for retail and hospitality lighting. More information can be found at lumileds.com/products/cob-leds/.

The company is the world’s best cob led chip size supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.