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Some lighting designers believe that the quality of all LED products is the same. However, there are many manufacturers and suppliers of LEDs, and Asian manufacturers supply low-cost LEDs to the world. Surprisingly, only a small percentage of these manufacturers can produce high-quality LEDs. For indication applications, low quality LEDs are sufficient. However, high quality LEDs must be used in many areas requiring consistency, reliability, solid state indication or lighting, especially in harsh environments such as highways, military/aviation, and industrial applications. In environments such as the New York subway station, security requirements are very demanding, and LEDs must meet the fundamentals of high quality requirements.
What are the factors that distinguish the quality of LEDs? How to tell the difference between the two LEDs? In fact, choosing high-quality LEDs can start from the chip until assembly is complete, and there are many factors to consider during this period. Tier-OnELED manufacturing companies are able to produce superior, consistent wafers that are made from high-quality LED manufacturing materials to produce superior chips. The chemical materials used in the wafer production process are quite important factors in determining the performance of all LED performance specifications.
A 2-inch wafer can cut more than 6,000 LED chips, and only the performance of individual chips is different from the overall one. Chips made by a good chip maker have very little difference in color, brightness, and voltage drop. When the LED chip package is completed, many of their performance indicators may have great differences, such as viewing angle. In addition, the influence of the encapsulating material is also considerable, for example, the resin is better than the epoxy resin.
LED manufacturers with excellent classification capabilities can not only manufacture high-quality chips, but also have the ability to classify and package LEDs according to their color, brightness, voltage drop and viewing angle. High-quality LED suppliers offer customers products with consistent work characteristics, while lower-quality LED suppliers can only provide LEDs that are similar to hybrids.
For high-end, quality-critical applications, such as boundary lights for airport runways, FAA-level color and brightness specifications must be met. To ensure performance and safety, the consistency of LED packaging is also strictly limited. LEDs with poorer packaging levels are used in demanding applications that can lead to premature failures and other inconsistencies, which can lead to major accidents. In order to avoid equipment downtime and to ensure reliable operating characteristics of the LEDs specified in the design, it is important to avoid the use of mixed products in high-end and quality-critical applications.
In addition to discrete LEDs, LED assembly and power supply have a very important impact on its performance, brightness and color. Since ambient temperature, operating current, circuit structure, voltage spikes, and environmental factors can all affect LED performance, proper circuit design and assembly are key to protecting LEDs and ensuring performance. LED manufacturers also use a variety of techniques and materials to design circuit structures and assemblies. In most cases, the difference in LED assembler experience can result in differences in overall performance and reliability for LEDs in the same application.
As the demand for LEDs grows rapidly, manufacturers and assembly plants serving the global market are also rapidly increasing. But unfortunately, the surge of support manufacturers not only use a large number of low-quality LEDs, but their packaging and LED design engineers experience is relatively insufficient. Therefore, in addition to accurately screening LED suppliers through existing experience, OEMs must also review their circuit design and assembly techniques to ensure that design specifications are met and that the design provides adequate thermal dissipation due to LED failure and performance. The main factor of inconsistency is overheating.
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To ensure that design requirements are met, OEMs must test LED assembly and circuit structure. In order to eliminate the injustices in testing, many companies have embarrassed manufacturers to test LED assembly and circuit structure. An LED device can be tested or used in harsh environments for several weeks. In the test process, pressure, temperature cycle, voltage fixed / change, current fixed / change test, etc., other tests under harsh environmental conditions to determine whether the LED meets the requirements of the application. A large number of parameter changes that occur before and after the test are recorded, and the changes in brightness, color, and voltage drop of the LED under test are monitored.
Accelerated lifecycle testing is a key test to avoid failures in specific application areas. Testing helps ensure that LEDs that are expected to work at least 100,000 hours, but fail only 1000 hours in advance, are likely to occur because of the low quality LEDs (which may also be unreasonably assembled). High quality LED) brightness will decrease after 1000 hours of operation. In fact, if a low-quality LED has a higher drive current, it will be brighter than a high-quality LED at the beginning of the work. However, too high a current will cause the LED to heat up too quickly, and the end result is that the brightness becomes dark or burned.
In addition, there are some examples of assembly techniques that have a greater impact on LED performance than the chip itself. Design engineers should ask the LED supplier for the reliability specifications of the LEDs, and should also perform LED assembly tests to ensure that the brightness is higher. Some excellent LED suppliers can guarantee the reliability of their LED assembly technology for three years or longer, and can further provide the final LED products including high quality LEDs and proper design for specific applications.
The Importance of Detection Two applications in the transportation sector help explain how adequate testing can prevent LEDs from failing in applications that provide high visibility. In the early 1990s, LEDs were used in brake lights for cars and trucks. Some LED designs quickly showed inconsistencies in performance metrics and quickly burned out, perhaps because of the quality of the LEDs, or perhaps the design of the product itself. Until recently, in the case of traffic lights, this phenomenon was taken seriously when LEDs became more suitable sources. Companies designing LED-covered 8-inch or 12-inch printed boards must consider environmental and application requirements in terms of choosing LEDs and improving design.
In any of the above cases, if the stress test or accelerated life cycle test has been done, it can be considered that the assembly of high-quality LED or LED is qualified, and it can be applied to the need for longer life and higher reliability. The occasion is over.
Fair use is not every application requires high quality LED assembly technology. If the assembly of the LED does not meet the requirements of a harsh environment, the application does not necessarily present a large safety risk, or if the repair cost of the final product is not very high, it may be more appropriate to use a poor assembly technique.
The most fundamental point is that LEDs must be affordable. Therefore, within the cost requirements, factors such as the packaging level of the supplier's products, the experience of assembly design, and testing must be considered. Designs that meet application and market needs are the most effective means of serving end users. If an application requires a high-end solution, the chip vendor's choice, design experience, and testing are all factors that should be considered. If you do not consider the sales price of high-end products, you should carefully consider other relevant factors that distinguish between good and bad LEDs. LED suppliers with the ability to classify packaging grades, as well as manufacturers capable of reliability and accelerated lifecycle testing, can work together for a long time, which helps manufacturers develop more high-end products with more reliable LEDs.
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