How LED Packaging Affects LED and LED Display Performance

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On 02/13/2025

When manufacturing LED displays, the cost of LED display components typically accounts for 40% to 70% of the overall cost. This depends on factors such as the cost of the LED itself and the production costs of the LED screen. Recently, the significant reduction in the cost of LED displays is primarily due to the continuous improvement of the upstream supply chain and the mature LED packaging technology, which has lowered the production costs of LED display components. It is evident that the quality of LED packaging plays a crucial role in determining the quality of the final LED display. The key to LED packaging reliability lies in selecting the right LED chip materials, packaging materials, and effective process control. Moreover, strict reliability standards are essential to ensure high-quality LED display components.
As the demand for LED displays in high-end markets continues to grow, manufacturers are raising the bar for LED display component quality. Below, we will explore some key technologies that ensure high-quality LED display components during the LED packaging process.

Table of Contents

Kinglight LED Display Components

Kinglight has gained recognition for producing high-performance LED display components, particularly in outdoor and high-brightness applications. Their innovative designs, including stretched cups and multi-waterproof structures, enhance the longevity and reliability of their LEDs. These components are often used in large-scale outdoor LED displays, where durability and consistent performance in various environmental conditions are crucial.

Introduction to SMD LED and Types

SMD (Surface Mounted Devices) LED refers to LEDs that use a surface-mount packaging structure. SMD LEDs are commonly used in various applications, including LED displays, automotive lighting, and consumer electronics. SMD packaging offers several advantages, such as compact size, efficient heat dissipation, and easy integration into automated manufacturing processes.
Types of SMD LEDs:
● Chip-type LEDs: These are compact LEDs mounted directly onto a PCB. They are usually less expensive but may have lower efficiency and brightness compared to other types.
● PLCC-type LEDs (Top LEDs): These LEDs are more efficient in terms of light output and heat dissipation. They are typically used in higher-performance applications like full-color displays and signage.
For instance, PLCC-type LEDs are often used in larger LED screens and outdoor displays due to their higher light output and improved heat resistance. As display technology advances, the demand for more compact and energy-efficient SMD LEDs is expected to grow.

How LED Packaging Affects LED and LED Display Quality

LED display components require several materials for packaging, including the LED bracket, LED chip, die attach adhesive, bond wires, and encapsulant.
1. LED Bracket
The LED bracket serves as the housing that supports the LED chip, providing structural support, electrical connections, and protection.
● Material Choices: High-quality LED brackets are typically made from materials such as thermally conductive plastics, metal alloys (like aluminum), or composite materials. These materials are selected to optimize heat dissipation and ensure durability in harsh environments.
● Reliability of Brackets: The thermal expansion mismatch between the materials used in the bracket and the LED chip can lead to mechanical stress, which may impact the overall reliability of the LED over time. Therefore, selecting materials with similar thermal expansion coefficients is essential for long-term performance.
① Function of the Bracket
PLCC (Plastic Leaded Chip Carrier) brackets are used as the carrier for SMD LEDs. The bracket is crucial for the reliability and light output performance of the LED.
② Production Process of the Bracket
The production of PLCC brackets involves processes such as metal tape punching, electroplating, PPA (Polyphthalamide) injection molding, bending, and five-sided 3D printing. Electroplating, metal substrates, and plastic materials represent the primary costs of the bracket.
③ Structural Design Improvements of the Bracket
In PLCC brackets, the physical bond between PPA and metal can cause gaps after high-temperature reflow soldering. Water vapor can easily enter the device through these gaps, affecting LED reliability.
To prevent such issues, LED packaging manufacturers often employ strategies to enhance the design. For instance, Kinglight’s outdoor series LEDs use stretched cups and multi-waterproof structures to improve the water resistance of the LED. Testing has shown that the stretched cup enhances the airtightness of the LED, effectively prolonging the path for water vapor to enter and minimizing its impact on product performance

2. LED Chip
The LED chip is the core component of the LED device, and its reliability directly influences the lifespan and luminous performance of both the LED device and the display. The cost of the LED chip is also the largest portion of the overall cost of the LED device. As LED chips shrink in size, they introduce various reliability issues.
● Design Considerations: To improve the performance of LED chips, manufacturers are exploring advanced materials like Gallium Nitride (GaN) and Quantum Dots, which can offer better efficiency and brightness. However, these new materials come with their own set of challenges in terms of processing and cost.
● Reliability Challenges: As LED chips decrease in size, it becomes increasingly difficult to maintain stability in the packaging process. Issues like bonding wire stability, heat management, and electrical connections become critical in ensuring the longevity of the LED.
As the size of the chip decreases, the P-electrode and N-electrode pads also shrink. Smaller pads affect the stability of wire bonding, leading to issues such as gold ball detachment or even electrode detachment during packaging or use, ultimately resulting in LED failure. Moreover, the reduced distance between the two pads increases current density, causing localized heat buildup, uneven current distribution, and performance degradation such as overheating, uneven brightness, leakage, or even low luminous efficiency. These factors reduce the overall reliability of the LED display.
3. Bonding Wire
Bonding wire is one of the key materials in LED packaging, serving as the electrical connection between the chip and the leads. Common bonding wire materials include gold wire, copper wire, palladium-coated copper wire, and alloy wire.
● Material Selection: The choice of bonding wire material is important for both cost and performance. Gold wire, although expensive, offers the best conductivity and long-term reliability. Copper wire is more affordable and provides better heat dissipation but is prone to oxidation.
● Advances in Bonding Technology: Manufacturers are increasingly using new bonding techniques, such as thermosonic and ultrasonic bonding, to improve the strength and reliability of wire bonds.
① Gold Wire
Gold wire is the most widely used and has the most mature process, but it is expensive, which increases the packaging cost of the LED.

② Copper Wire
Copper wire is a cost-effective alternative to gold wire. It offers good heat dissipation and slower growth of metal intermetallic compounds during the bonding process. However, copper is prone to oxidation and has high hardness and strain strength, which complicates the bonding process.
③ Palladium-coated Copper Wire
Palladium-coated copper wire is gaining attention in the packaging industry due to its high mechanical strength, moderate hardness, and excellent ball-welding performance. It is particularly suitable for high-density, multi-lead integrated circuit packaging.
4. Encapsulant
LED display devices typically use two types of encapsulant: epoxy resin and silicone.
● Materials and Properties: Epoxy resins are commonly used for their excellent adhesive properties and cost-effectiveness. However, they may degrade over time due to environmental factors such as UV light, humidity, and heat. Silicone is more durable and offers better heat resistance and moisture protection, but it is generally more expensive.
● Innovative Encapsulation Solutions: Manufacturers are continuously developing new encapsulation materials, such as hybrid resins and phosphor-based solutions, to improve the durability and performance of LEDs in outdoor and high-temperature applications.
① Epoxy Resin
Epoxy resin is susceptible to aging, moisture absorption, poor heat resistance, and discoloration under short-wavelength light or high temperatures. It also has toxicity in its uncured state and poor compatibility with LED thermal stress, which affects the reliability and lifespan of LEDs. To improve its performance, LED packaging manufacturers often modify epoxy resin during the encapsulation process.
② Silicone
Silicone offers better cost-effectiveness, excellent insulation, dielectric properties, and adhesion compared to epoxy resin. However, its relatively poor air-tightness and moisture absorption limit its use in LED display packaging.
Furthermore, high-quality LED displays demand excellent visual performance. For example, Kinglight uses additives to improve the stress of the encapsulant while achieving a matte finish. This helps reduce the impact of internal stress on bonding wire breakage and decreases the surface reflectivity of the LED device.

Conclusion

The quality of LED packaging is directly linked to the performance of both individual LED devices and the final LED display. By focusing on critical packaging materials, such as brackets, chips, bonding wires, and encapsulants, manufacturers can ensure that their products meet the stringent reliability and performance requirements of the high-end LED display market. Through innovative packaging designs and material selection, companies like Kinglight continue to enhance the durability and visual quality of their outdoor LED products.