How to Determine the Quality of LED Screen Lamp Beads

LED screens have become an integral part of our modern world. You can find their applications in advertising, digital signage, and even all type of event use. The quality of LED is crucial to ensure the longevity and performance of these New or Used LED display screens. In this post, we will explore four effective methods to determine the quality of LEDs, helping you make informed decisions when selecting the right LED video wall for your specific needs.

How to Determine the lamp beads Quality of LED Display

Common considerations

Check the LED’s Brand and Manufacturer:

One of the most reliable ways to assess the quality of LED  display modules is by looking at the brand and manufacturer. A reputation brands quality are more likely to produce reliable LED components. Well-known LED display manufacturers invest in research and development to improve their products, ensuring higher performance and longer lifespan. Additionally, these reputable LED companies often provide warranties and customer support, offering peace of mind for consumers.

Inspect the Color Uniformity:

Color uniformity is a critical factor in LED display quality. To evaluate this, look at the LED module from various angles and distances. High-quality modules will maintain consistent color and brightness across the entire screen. In contrast, lower-quality LEDs may exhibit color variations, leading to an uneven and unprofessional display. Color uniformity can be particularly important for applications where the LED screen needs to display vibrant and accurate colors, such as in advertising or video presentations.

Test for Brightness and Contrast:

The brightness and contrast levels of LED display play a pivotal role in their quality. Check the specifications provided by the manufacturer and ensure they meet your requirements. Brightness determines the visibility of the display, especially in outdoor settings. Adequate contrast, on the other hand, enhances the clarity of content displayed. A high-quality LED module should provide consistent and reliable performance in terms of both brightness and contrast.

Assess the Build Quality:

The physical build of LED modules can indicate their durability. Examine the materials used, heat dissipation mechanisms, and weather resistance. For outdoor applications, weatherproofing is crucial to prevent damage from moisture, dust, and extreme temperatures. Additionally, well-designed LED modules should include efficient heat sinks to prevent overheating, which can significantly extend the lifespan of the LEDs.

Professional considerations

Nowadays, the packaging method used by LED display manufacturers is mainly SMD (Surface Mounted Devices). This kind of SMD is usually welded on the PCB board, and is generally divided into PCB board structure LED (Chip LED) and PLCC structure LED (TOP LED). The following takes SMD LED of TOP LED as an example. LED screen packaging materials include brackets, chips, solid crystals, bonding wires and packaging glue.

LED bracket

1) The role of the bracket. The PLCC (Plastic Leaded Chip Carrier) bracket is the carrier of SMD LED equipment and plays an important role in the reliability, luminescence and other functions of the LED.

2) The production process of the stent. The PLCC bracket production process mainly includes metal strip punching, electroplating, PPA (polyphthalamide) injection molding, bending, five-sided three-dimensional inkjet and other processes. Among them, electroplating, metal substrates, plastic materials, etc. account for the main part of the bracket cost.

3) Structural improvement planning of the bracket. Because the PLCC bracket is a physical combination between PPA and metal, the gap will become larger after being exposed to a high-temperature reflow oven, causing water vapor to easily enter the interior of the equipment, affecting the reliability of the LED lamp beads.

In order to improve the reliability of LED screens, some LEDs packaging manufacturers have improved the structural planning of the bracket. For example, advanced waterproof structural planning and bending and stretching methods are used to prevent water vapor from entering the inside of the bracket, and multiple waterproof methods are used to add waterproof grooves, waterproof steps and drain holes inside the bracket.

This method can not only greatly improve the reliability of the product, but also save packaging costs. This kind of lamp beads is generally used in outdoor LED displays. Moreover, it was found after use that the LED bracket with the SMD lamp bead bending structure has better air tightness.

LED chip

LED chips are an important part of LEDs, and their reliability is related to LED display, service life and luminous performance. The cost of LED chips accounts for about 70,000 of the total cost of LED display. As costs continue to decline, LED chip sizes are getting smaller and smaller, and their reliability is getting higher and higher. The structure of the LED blue-green chip is shown in the figure below.

LEDs chip

As the size of LED chips becomes smaller and larger, the pads of P electrode and N electrode are also getting smaller and smaller. The shrinkage of the electrode pad directly affects the quality of the bonding wire, causing the gold ball to detach during the packaging process and use, and even the electrode itself to detach, causing failure problems.

At the same time, the distance a between the two pads will also shrink, causing the current density at the electrode to increase excessively, and the current to accumulate locally at the electrode. The unevenly distributed current will seriously affect the chip, causing the local temperature of the chip to be too high. Uneven brightness, leakage, electrode drop, and even lower efficiency will affect the reliability of LED electronic large screens.

The function of the bonding wire is to electrically connect the chip to the pins, and then allow the current to be introduced and exported between the chip and the outside world. It is one of the key materials for LED packaging. Commonly used bonding wires for LEDs packaging include gold wires, copper wires, palladium-plated copper wires and alloy wires. Generally speaking, gold wire is widely used, but due to the high price, the cost of LED packaging is too high, so it is used less.

Although copper wire can replace gold wire, the cost is lower, the heat dissipation effect is good, and the growth of intermetallic compounds during the wire bonding process is several times slower. However, copper wire is relatively prone to oxidation, has high hardness and strain strength, etc.

Especially in the heating environment of the bonding copper ball-burning process, the copper surface is prone to oxidation, forming an oxide film, which will reduce the bonding wire performance of the copper wire and impose higher requirements on the production process.

In order to prevent oxidation of copper wires, LEDs packaging manufacturers use palladium-plated bonded copper wires instead of copper wires. Palladium-plated bonding copper wire has the advantages of high mechanical strength, moderate hardness, and good welding ballability, and is very suitable for high-density, multi-pin integrated circuit packaging.

glue

The glue for LED screen packaging devices mainly includes epoxy resin and silicone. Epoxy resin is relatively easy to age, has poor moisture-proof and heat-resistant properties, and is prone to discoloration under short-wave light and high temperatures. It has a certain degree of toxicity in its colloidal state, and its thermal stress does not match well with LEDs, all of which affects the reliability of LED displays. and lifespan.

Compared with epoxy resin, silicone has a higher cost performance, excellent insulation, dielectric and adhesion properties. However, the disadvantage is that it has poor air tightness and is easy to absorb moisture, so it is rarely used in LED display device packaging.

In addition, some packaging manufacturers use additives to improve the stress of the glue, while achieving a matte matte effect, improving the display effect and quality of LED screens.

Conclusion:

The above is a brief introduction by IAMLEDWALL about the quality of LED screen lamp beads, including LED brackets, LED chips, bonding wires and glue. Among bonding wires, gold wire is a better material and has advantages in heat dissipation, reliability, service life, and moisture resistance. However, due to the high cost, copper wire or other materials are generally used instead.

Investing in high-quality LED display is essential to ensure the longevity and performance of LED screens in various applications. By considering above factor, you can make informed decisions when choosing the right LED components for your specific needs. Quality LEDs not only provide better visual experiences but also save you time and money in the long run, making them a worthwhile investment.