Your Guide to Common LED Terms SMD COB COG and Beyond

·August 2, 2025

·15 min read

Your Guide to Common LED Terms SMD COB COG and Beyond — Image Source: unsplash

SMD, COB, and COG represent key technologies in the world of LED lighting. SMD refers to surface mount device LEDs, which use compact packages for efficient mounting on circuit boards. COB, or chip on board, describes a method where multiple light emitting diode chips combine on a single substrate, producing powerful, uniform light. COG, known as chip on glass, involves mounting LED chips directly onto glass, enabling high-density displays. Many misunderstandings exist, such as confusing COB with COG or mislabeling MicroLED as any small-pitch LED, when true MicroLED relies on sub-100-micron chiplets and advanced substrates. Understanding these distinctions helps consumers and professionals make better choices in LED lighting, as the difference between SMD LED, COB, and COG directly impacts performance, efficiency, and application.

Key Takeaways

SMD, COB, and COG are different LED technologies with unique designs and uses that affect brightness, efficiency, and application.
SMD LEDs offer flexible layouts and color options, making them great for general lighting and displays with space limits.
COB LEDs provide powerful, uniform light with better heat management, ideal for high-brightness and energy-efficient lighting.
COG and COF technologies help create thinner, lighter, and more flexible LED displays, improving device design and performance.
BOE leads in LED innovation by combining these technologies to deliver brighter, more efficient, and advanced display solutions.

Why LED Terms Matter

Making Smart LED Choices

Understanding LED terms empowers both consumers and professionals to make informed decisions when selecting lighting solutions. LED technology has transformed the lighting industry, offering energy efficiency, long lifespan, and versatile applications. When buyers know the difference between SMD, COB, and COG, they can choose LED fixtures that best match their needs. For example, SMD LEDs often suit general lighting, while COB LEDs excel in high-output environments. COG technology enables ultra-thin displays, which are ideal for modern devices. Recognizing these distinctions helps users compare LED products based on performance, durability, and cost-effectiveness.

Tip: Always check the specifications of LED fixtures before purchasing. Key terms like brightness (measured in nits), color rendering index (CRI), and power consumption directly affect the quality and efficiency of lighting.

A clear grasp of LED terms also supports professionals in designing advanced lighting systems. Architects, engineers, and lighting designers rely on precise terminology to specify the right components for each application. This knowledge ensures that solid state lighting installations deliver optimal performance and meet project requirements.

LED Performance and Applications

The performance of LED products depends on several factors, including chip type, packaging method, and integration technology. Each LED fixture offers unique benefits for different applications. SMD LEDs provide flexibility for compact designs, while COB LEDs deliver powerful, uniform illumination. COG and COF technologies enable thinner, lighter displays, expanding the possibilities for consumer electronics and automotive panels.

BOE’s leadership in display technology highlights the value of mastering advanced LED terms.

BOE introduced a 16K 110” naked-eye 3D display with Mini-LED backlight, demonstrating expertise in Mini-LED and advanced pattern algorithms.
The P0.3 Micro-LED product achieves 2000nit peak brightness and 110% NTSC color gamut, showing deep understanding of brightness and color metrics.
AI-powered image quality restoration in MLED COG direct display chips improves picture quality through advanced LED integration.
BOE’s in-vehicle ultra-large oxide product uses glass-based Mini-LED backlight for a million-level contrast ratio and 2000nit brightness.
The 16” Ultra-S gaming notebook features Mini-LED backlight, 2000:1 static contrast ratio, and 240Hz refresh rate, emphasizing the importance of contrast and refresh rate.

These innovations prove that a strong command of LED terms enables companies to push the boundaries of performance, efficiency, and application. As LED technology evolves, understanding these concepts remains essential for anyone involved in lighting or display solutions.

SMD LED and COB: Key Differences

What is SMD LED?

SMD LED stands for surface-mounted device light-emitting diode. This technology uses individual LED chips mounted directly onto a printed circuit board (PCB) through surface-mount technology. Each chip in an smd led has its own packaging, phosphor coating, and reflective cavity. The design allows for compact arrangements and flexible layouts, making smd led a popular choice in modern lighting and display solutions. The surface-mounted device approach enables efficient mass production and easy integration into a wide range of electronic products.

SMD LED Features

SMD LED technology offers several distinct features:

Each smd led chip is individually packaged and mounted on the PCB, allowing for precise placement and flexible design.
SMD LEDs support a wide range of colors, including RGB combinations, which enables dynamic color-changing effects.
The compact size of smd led chips makes them suitable for applications where space is limited.
SMD LEDs typically have a beam angle between 120° and 160°, providing directional lighting.
The surface-mounted device structure allows for easier replacement of individual LEDs if one fails.
SMD LEDs require more solder points and space for ventilation, which can increase production complexity.
Heat dissipation occurs through the electrodes to the substrate and then to the heatsink, which may require additional cooling solutions.

SMD LED technology is widely used in consumer electronics, LED strips, backlighting for displays, signage, spotlights, and architectural installations. Applications also include wearable devices, smart appliances, and IoT products. The versatility of smd led makes it a preferred choice for both decorative and functional lighting in residential, commercial, and industrial environments.

What is COB?

COB, or chip-on-board, represents a different approach to LED packaging. In cob technology, multiple bare LED chips are mounted directly onto a single substrate, such as ceramic or aluminum, forming a unified light-emitting surface. Unlike smd led, cob does not use individual packaging for each chip. Instead, the chips are arranged closely together, creating a seamless module that emits uniform and powerful light. COB modules have only two metal connection points—anode and cathode—regardless of the number of chips, which simplifies the electrical design.

The direct mounting of chips on the substrate in cob technology results in superior thermal conductivity and fewer solder points. This reduces the risk of production failures and enhances the reliability of the lighting system. The fixed chip arrangement in cob limits design flexibility but ensures consistent performance and high efficiency.

COB Features

COB technology brings several advantages to LED lighting and display applications:

Multiple LED chips are integrated directly onto a single substrate, creating a compact and unified light source.
COB modules deliver high brightness and uniform, glare-free illumination with a wide beam angle, typically around 180°.
The design offers excellent thermal management, as heat dissipates efficiently through the substrate, often made of ceramic or aluminum.
COB LEDs have a longer lifespan and higher energy efficiency compared to SMD Led, often reaching about 80 lumens per watt.
The simplified structure, with only two connection points, reduces the likelihood of electrical failures.
COB modules are durable and exhibit strong anti-static properties, making them suitable for demanding environments.
The fixed chip arrangement means that if one chip fails, the entire module may need replacement, which can increase maintenance complexity.

COB LEDs excel in applications that require intense, uniform lighting. Typical uses include high-ceiling industrial spaces, retail and display lighting, automotive headlights, medical lighting, and architectural illumination. In residential settings, cob technology enhances kitchens, living rooms, and workspaces with bright, even light. Commercially, cob is valued for its high lumen output and energy efficiency in offices, stores, and hospitality venues.

SMD LED vs. COB: Structure, Advantages, and Applications

The structural differences between smd led and cob technologies shape their performance and ideal use cases.

SMD LEDs consist of individual chips, each with its own packaging, mounted on a PCB. This allows for flexible layouts and easy replacement but increases the number of solder points and production complexity.
COB integrates multiple bare chips onto a single substrate, forming a seamless light-emitting surface. This design improves thermal management and reliability but limits flexibility in chip arrangement.

Feature	SMD LED	COB
Structure	Individual chips, each packaged, on PCB	Multiple bare chips on single substrate
Beam Angle	120°–160°, directional	~180°, wide and uniform
Brightness	Lower per chip, can be increased by quantity	High, uniform, glare-free
Color Options	Rich, supports RGB and dynamic effects	Limited, usually single color or white
Heat Dissipation	Through electrodes and substrate, less efficient	Direct to substrate, highly efficient
Maintenance	Easy to replace individual LEDs	Module replacement required if chip fails
Cost	Lower initial and installation costs	Higher upfront, long-term savings
Applications	Decorative, accent, flexible, and display lighting	Industrial, commercial, automotive, architectural

SMD LED technology suits applications where flexibility, color variety, and cost-effectiveness are priorities. COB technology excels in scenarios demanding high brightness, uniformity, and energy efficiency.

BOE’s Use of SMD and COB in Advanced Display Products

BOE leverages both smd led and cob technologies to deliver cutting-edge display solutions. In direct view LED products, BOE uses smd led with various pixel pitches and chip sizes, achieving moderate brightness levels suitable for a wide range of applications. The company’s cob-based displays offer very fine pixel pitches, high brightness, and enhanced visual experiences, making them ideal for high-end, large-format displays and professional environments.

BOE’s integration of cob technology enables displays with superior contrast, resolution, and energy efficiency. The company’s cob modules support micro pitch displays below 1.0mm, which traditional smd led technology cannot reliably achieve. This advancement allows BOE to produce high-definition, durable, and energy-efficient displays for automotive, medical, and commercial markets.

Note: BOE’s commitment to innovation in both smd led and cob technologies ensures that customers receive tailored solutions for diverse lighting and display needs.

COG and COF in LED Displays

COG Technology

COG, or Chip on Glass, represents a significant advancement in led display packaging. This technology mounts the driver IC chip directly onto the glass substrate of the display, eliminating the need for a separate printed circuit board. The process uses flip chip bonding with gold bumps and an anisotropic conductive film (ACF) to create a secure connection. This approach results in a thinner, more compact module, often less than 3 mm thick.

Feature	Traditional LCD Module	COG Technology
Driver Location	On a PCB behind the LCD module	Directly on the glass substrate of the LCD
Connection Method	Multiple bonds via pins or elastomer connectors	Single bond per connection using Flip Chip and ACF
Thickness	Increased due to PCB and connectors	Less than 3 mm, very thin
Reliability	Dependent on multiple external bonds	Improved by minimizing external connections
Components	LCD glass, PCB, driver IC, connectors	LCD glass, driver IC chip, cable

The basic principle of COG technology centers on reducing the overall size and complexity of the led module. By bonding the chip directly to the glass, manufacturers achieve a compact design that supports mass production, especially for consumer electronics like smartphones and tablets. COG modules also offer improved reliability by minimizing external connections, which reduces the risk of failure. The integration of backlight and electronic components onto the glass substrate enables thinner, lighter, and more energy-efficient devices. This technology also enhances viewing angles and color consistency, making it ideal for high-performance led displays.

COF Technology

COF, or Chip on Film, takes a different approach by mounting the driver IC onto a flexible printed circuit (FPC) made from polyimide film. This flexible film can bend and fold, allowing the chip to be positioned behind or beneath the display area. COF technology enables manufacturers to create ultra-thin, flexible, and even foldable led and OLED displays.

Aspect	COF (Chip on Film)	COG (Chip on Glass)
Manufacturing Process	Driver IC mounted on flexible film (FPC); requires high precision, advanced equipment, skilled personnel; higher cost and lower yield	Driver IC bonded directly on glass substrate; mature process; lower cost; higher production efficiency
Flexibility & Design	Enables thinner, more flexible modules; allows narrower bezels and larger screen-to-body ratio	Glass substrate is rigid; results in wider bezels due to IC placement
Performance	Better flexibility and thinner profile; more fragile during installation	More durable; lower defect rates during installation
Yield & Cost	Lower yield, higher cost due to complexity	Higher yield, lower cost due to mature technology
Application	Favored for modern full-screen mobile devices requiring narrow borders	Popular for cost-sensitive and mature production environments

COF technology supports the development of displays with extremely narrow bezels and high screen-to-body ratios. The flexible nature of the film allows for innovative form factors, such as curved or foldable screens, which are increasingly popular in smartphones and wearable devices. While COF offers superior flexibility and design freedom, it requires advanced manufacturing equipment and skilled personnel, resulting in higher costs and lower production yields compared to COG. However, the benefits in terms of display thinness and flexibility make COF a key technology for next-generation led and OLED products.

Applications in BOE Displays

Both COG and COF technologies play vital roles in the evolution of modern led and OLED displays. COG technology enables BOE to produce thinner, lighter, and more compact devices by integrating the backlight and electronic components directly onto the glass substrate. This integration improves energy efficiency, enhances durability, and allows for consistent color accuracy and brightness from various viewing angles. COG also supports manufacturing flexibility, making it easier to integrate into diverse product designs.

COF technology, on the other hand, empowers BOE to create ultra-thin and flexible displays. By mounting the driver IC on a flexible film, BOE can develop displays that curve, fold, or fit into unconventional shapes. This capability is essential for the latest trends in foldable smartphones, wearable electronics, and automotive displays. COF technology allows for a larger display area and narrower bezels, meeting the demands of consumers who seek immersive visual experiences.

BOE’s Knowledge Cool Pro series highlights how these technologies drive innovation in the display industry. COG and COF have enabled the miniaturization of devices, improved environmental sustainability, and supported the creation of new product categories. For example, COG technology has made it possible to design sleek, compact smartphones and tablets, while COF has paved the way for flexible and foldable screens. Both approaches reduce module thickness and improve design flexibility compared to traditional chip on board methods, which rely on rigid circuit boards.

Note: COG and COF technologies have transformed the led display landscape, enabling manufacturers like BOE to deliver products that are thinner, lighter, and more versatile than ever before. These advancements continue to shape the future of consumer electronics, automotive displays, and beyond.

MLED and BOE Innovations

What is MLED?

MLED stands for Mini/Micro LED, a next-generation display technology that builds on the strengths of previous LED advancements. Unlike traditional LCDs, which use passive light emission, or OLEDs, which can suffer from burn-in and shorter lifespan, MLED uses small, self-luminous LEDs that can be individually controlled. This approach delivers superior brightness, contrast, and color fidelity. MLED displays combine Mini LED and Micro LED chips, achieving higher pixel density and better visual performance. The self-emitting nature of MLED enables true blacks and faster response times, making it suitable for a wide range of applications, from large commercial displays to wearable devices and AR glasses.

MLED vs. Traditional LED

MLED technology offers several advantages over traditional LED solutions, including SMD and COB. The following table summarizes key differences:

Feature	Traditional LED (SMD/COB)	MLED
Chip Size	Larger (SMD), moderate (COB)	Miniaturized (10-100 microns)
Pixel Density	Limited by chip size and packaging	Ultra-high, supports 4K/8K resolutions
Light Emission	Backlit (LCD), direct (COB)	Self-emitting, true blacks
Brightness	Good (COB excels in high output)	Exceptional, stable at high levels
Color Gamut	Standard (SMD/COB)	Wide, supports advanced color spaces
Lifespan	Long (COB), moderate (SMD)	Extended, less prone to burn-in
Power Consumption	Moderate to high	Low, efficient thermal management

MLED achieves higher brightness and a wider color gamut through several mechanisms:

Micro LED chips arranged at high density enable ultra-high resolution and color accuracy.
Advanced packaging optimizes thermal management, maintaining brightness and preventing color shifts.
Optical enhancements, such as color conversion layers and brightness enhancement films, further improve performance.

BOE’s Role in LED Innovation

BOE has established itself as a leader in MLED research and development. At major industry events, BOE has showcased its latest MLED products, including COB, Micro MPD, and virtual shooting solutions. The company integrates MLED into its strategic business framework, driving innovation across indoor, outdoor, and creative display applications. BOE’s advancements in PCB design, high-voltage Mini LED chips, and active matrix driving technology have improved performance and reduced costs. The evolution from SMD to COB and then to COG has paved the way for MLED, addressing challenges in pixel pitch, durability, and display quality. Glass-based MLED displays, enabled by COG, now achieve ultra-fine pixel pitches and superior image quality. BOE’s ongoing efforts continue to expand the application scenarios for MLED, enhancing user experiences worldwide.

LED Glossary: Essential Terms

CRI (Color Rendering Index)

Color Rendering Index (CRI) measures how accurately a led lighting source displays colors compared to natural daylight. The CRI scale ranges from 0 to 100. A CRI above 90 means colors appear vibrant and true, which is essential in art galleries, retail, and residential spaces. CRI values between 80 and 90 suit most commercial environments. Lower CRI can cause colors to look dull or unnatural. High CRI led fixtures improve visibility, reduce eye strain, and create a more inviting atmosphere. Accurate color rendering is critical for tasks that require color discrimination.

CCT (Correlated Color Temperature)

Correlated Color Temperature (CCT) describes the color tone of white light, measured in Kelvin (K). Lower CCT values (2200K–3000K) produce warm, yellowish light, ideal for living rooms and restaurants. Higher CCT values (5000K–6500K) create cool, bluish-white light, suitable for offices and outdoor areas. Selecting the right CCT affects the ambiance and functionality of a space. Many modern led fixtures offer adjustable CCT, allowing users to switch between warm and cool tones to match mood or task. This flexibility supports comfort and productivity throughout the day.

CCT Range (Kelvin)	Appearance Description	Typical Applications
2200K - 3000K	Warm, cozy, yellowish light	Living rooms, bedrooms, restaurants, hotels
3000K - 3500K	Neutral white	Offices, kitchens, retail environments
4000K - 4500K	Cool white	Workstations, garages, workshops
5000K - 6500K	Daylight, bluish-white	Outdoor lighting, stadiums, parking lots

Lumens and Wattage

Lumens measure the total visible light output from a led. Wattage indicates the energy consumed by the fixture. Luminous efficacy, expressed as lumens per watt, shows how efficiently a led converts power into light. For example, a led producing 1,080 lumens using 12 watts achieves a luminous efficacy of 90 lumens per watt. Modern leds often reach 75–110 lumens per watt, far surpassing traditional bulbs. High luminous efficacy means more light with less energy, reducing electricity costs. When selecting led fixtures, users should focus on lumens for brightness and wattage for energy consumption. Using lumens instead of wattage helps ensure the right brightness while maximizing efficiency.

Tip: Always compare lumens, not just wattage, when choosing led products for the best energy savings and performance.

DIP and Other LED Types

DIP (Dual In-line Package) leds represent the oldest technology, using individual diodes mounted through holes on a circuit board. DIP leds offer high brightness and durability, making them ideal for outdoor signage and stadium displays. However, they have lower pixel density and less precise color blending than newer types. SMD (Surface Mount Device) leds integrate multiple chips into a compact package, supporting higher resolution and better color uniformity. COB (Chip on Board) leds mount many chips on a single substrate, delivering seamless, high-brightness light with excellent thermal management. Each type serves different needs, from rugged outdoor displays to high-performance indoor lighting.

Feature/Aspect	DIP LEDs	SMD LEDs	COB LEDs
Technology Age	Oldest	More recent	Latest
Structure	Individual diodes	Integrated chips	Multiple chips on substrate
Brightness	High	Moderate to high	Highest
Energy Efficiency	Lower	Higher	Highest
Typical Applications	Outdoor signage, stadiums	Indoor displays, TVs	Spotlights, downlights

Note: Understanding the differences among led types helps users select the right led drivers and fixtures for their specific applications.

Understanding SMD, COB, COG, and MLED technologies enables users to make informed decisions about lighting and display solutions. Each technology offers unique advantages in image quality, durability, and efficiency. When comparing LED products, users should review wattage, lumens, CRI, power factor, and certifications for optimal performance. BOE’s MLED innovations set new standards for brightness, energy efficiency, and installation flexibility. For further insights and detailed product information, readers can explore BOE’s website, which features advanced display technologies and practical resources.

FAQ

What is the main difference between SMD and COB LEDs?

SMD LEDs use individual chips mounted on a circuit board, offering flexibility and color options. COB LEDs combine multiple chips on one substrate, providing higher brightness and uniform light. Each technology serves different lighting and display needs.

How does COG technology benefit modern displays?

COG technology mounts the driver chip directly onto the glass. This design reduces thickness and weight. It also improves reliability and enables slimmer, more energy-efficient devices. Manufacturers use COG for smartphones, tablets, and advanced displays.

Where are high-powered floodlights commonly used?

High-powered floodlights illuminate large outdoor areas, such as stadiums, parking lots, and building facades. They provide intense, uniform lighting for safety and visibility. Many commercial and industrial facilities rely on these fixtures for nighttime operations.

What makes MLED displays stand out from traditional LEDs?

MLED displays use miniaturized, self-emitting LEDs. This technology delivers higher brightness, wider color gamut, and longer lifespan. MLED also supports ultra-high resolutions and true black levels, making it ideal for premium screens and professional applications.

Why is CRI important when choosing LED lighting?

CRI measures how accurately a light source shows colors compared to natural daylight. A higher CRI value means colors appear more vivid and true. This factor is essential for environments where color accuracy matters, such as art galleries and retail stores.