For ordinary users, the quality of LED products can guarantee normal operation. But for some LED lighting products that work in special environments, their performance and quality must have more stringent requirements than ordinary LEDs. This article will introduce you to several key points that you need to pay special attention to if you want to make high-quality LEDs.
If you want to assemble high-quality LEDs, you need to pay attention to many aspects. A 2-inch wafer can cut out more than 6000 LED chips, only the performance indicators of individual chips are different from the whole. However, the difference in color, brightness, and voltage drop among chips made by an excellent chip manufacturer is very small. When the LED chip is packaged, there may be big differences in many of their performance indicators, such as viewing angles. In addition, the impact of packaging materials is also considerable, for example, silicone resin has better performance than epoxy resin.
Excellent LED manufacturers 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 will provide customers with products with consistent working characteristics, while lower-quality LED suppliers can only provide LEDs similar to "mixed".
For high-end applications with strict quality requirements, such as airport runway boundary lights, they must meet FAA-level color and brightness specifications. To ensure performance and safety, the consistency of LED packaging is strictly limited. The use of LEDs with poor packaging grades in demanding applications will lead to a series of inconsistencies such as premature failures, which are likely to lead to major accidents. In order to avoid equipment downtime and ensure that the LEDs specified in the design have reliable operating characteristics, it is very important to avoid the use of "mixed" products in high-end and strict quality applications.
Product supporting abilityIn addition to discrete LEDs, the assembly and power supply of LEDs have a very important impact on its performance, brightness, color and other indicators. Since ambient temperature, operating current, circuit structure, voltage spikes, and environmental factors can affect the performance of LEDs, proper circuit design and assembly are the keys to protecting LEDs and ensuring performance. LED manufacturers also use multiple technologies and different materials to design circuit structures and assembly. In most cases, differences in the experience of LED assemblers will cause differences in overall performance and reliability of LEDs in the same application.
With the rapid growth of LED demand, manufacturers and assembly plants serving the global market are also rapidly increasing. Unfortunately, the surge in support manufacturers not only adopt a large number of low-quality LEDs, but also have relatively insufficient experience in packaging and LED design engineers. Therefore, in addition to accurately screening LED suppliers through existing experience, OEMs must also examine their circuit design and assembly technology to ensure that they meet the design specifications, and whether the design provides sufficient heat dissipation capacity, which leads to LED failure and performance The main factor of inconsistency is overheating.
To ensure that the design requirements are met, the OEM must inspect the LED assembly and circuit structure.
Third-party testingIn order to eliminate the injustice in the test, many companies have entrusted a third party to test the LED assembly and circuit structure. An LED device may be tested or used for several weeks in a harsh environment. During the testing process, tests of pressure, temperature cycle, voltage fixation/change, current fixation/change, etc. are carried out at the same time, and other tests under harsh environmental conditions are used to determine whether the LED meets the requirements of the application. A large number of parameter changes before and after the test must be recorded, and the changes in the brightness, color and voltage drop of the tested LED must be monitored.
Accelerated life cycle testing is a key test to avoid failures in special applications. Testing helps to ensure that those LEDs that are expected to work for at least 100,000 hours, but fail prematurely after only 1,000 hours of operation. This situation is possible because low-quality LEDs (or high-quality LEDs with unreasonable assembly design) will decrease in brightness after 1000 hours of operation. In fact, if a low-quality LED has a higher driving current, it will be brighter than a high-quality LED in the early stage of operation. However, an excessively high current will cause the LED to heat up too fast, and the final result will be dimming or burning.
In addition, there are also examples where assembly technology has a greater impact on LED performance than the chip itself. The design engineer should ask the LED supplier for the reliability specification of the LED, and should also carry out the assembly test of the LED to ensure that the higher brightness is indeed better. Some excellent LED suppliers can guarantee the reliability of their LED assembly technology for three years or more, and can further provide final LED products that include high-quality LEDs and appropriate designs for special applications.
Importance of testingTwo applications in the transportation field help explain how adequate testing prevents LEDs from malfunctioning in applications that provide a high degree of visibility. In the early 1990s, LEDs were used in the brake lights of cars and trucks. Some LED designs quickly showed inconsistencies in performance indicators and quickly burned out. The reason may be due to the quality of the LED, or it may be entirely a design problem of the product itself. Until recently, when LEDs became a more suitable light source for traffic lights, this phenomenon was taken seriously. Companies that design printed boards with a diameter of 8 inches or 12 inches full of LEDs must consider environmental and application requirements when selecting LEDs and improving designs.
In any of the above cases, if the stress test or accelerated life cycle test has been done, it can be considered that the high-quality LED or LED assembly is qualified, and it can be applied to the needs of longer service life and higher reliability. Occasion.
Fair useNot every application requires high-quality LED assembly technology. If the LED assembly does not meet the requirements of the harsh environment, the application will not necessarily present a greater safety risk, or if the maintenance cost of the final product is not very high, it may be more appropriate to use a worse assembly technology.
Although the quality of LED products will increase correspondingly with the investment in cost, developers still need to pay attention to controlling the price within a reasonable range, and the cost control takes into account factors such as packaging level, assembly design experience and testing. Suppliers with packaging grade classification can cooperate with manufacturers with life cycle inspection capabilities, which is conducive to the production of high-end products.
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