Calculate LED reliability from component standards
In the face of fierce market competition, industry insiders are eager to introduce a set of LED reliability standards, which can be used not only to assess reliability, but also to identify the pros and cons of products, to ensure the healthy and orderly development of my country’s LED industry. As everyone knows, many reliability standards of some electronic components (including semiconductor devices) and their application products are also applicable to LEDs.
In view of this situation, it is necessary to briefly introduce several electronic component standards that can be used for LED reliability evaluation, so as to guide everyone to learn and master, and be able to apply them to LEDs. These standards have been published for a long time, and the time span has been about 30 years from the 1980s to the present. As traditional standards, they have been tested by time and practice over the years. Among the standards introduced here, some are fully applicable to LEDs, and some can be used as a reference and basis for formulating LED-related standards.
Nowadays, white LED lighting has been practical and industrialized, and its luminous efficiency has surpassed traditional incandescent lamps and fluorescent lamps, fully showing the characteristics of energy saving and environmental protection.
With the increasingly widespread application of LED lighting, its reliability has attracted more and more attention.
1. General rules for accelerated life testing of electronic components (GB 2689.1-81 referred to as general rules)
This standard is used to quantitatively evaluate the reliability of electronic components. When formulating product technical standards with reliability requirements, it can provide a unified method for the tested products. The working life of electronic components, especially semiconductor devices, is as long as hundreds of thousands of hours. The method of thermal acceleration is generally used to obtain the life value, which is the so-called accelerated life test. The "General Principles" specifies the implementation details of the thermally accelerated life test, which includes: sampling, test stress, determination of failure time, parameter testing, failure analysis, failure effectiveness judgment, data processing, test reports, etc. These are completely applicable to LED devices.
2. Life estimation method of electronic components (GB 2689.3-81 and GB 2689.4-81)
This standard specifies the methods and procedures for data processing of accelerated life test of electronic components. According to the number of samples, it is divided into two methods: simple linear unbiased estimation and best linear unbiased estimation. Since the test is in the wear failure period of the device, the test can not be terminated until the specified number of failures is reached, so it is also called "fixed number". Using this method, multiple reliability parameters such as the average lifetime, failure rate, and activation energy of the device can be obtained. This is a commonly used method in engineering to evaluate the life of electronic components, and it is also applicable to LED devices.
3. Evaluation method of semiconductor device durability (GB/T 4589.1-2006)
This standard is a part of the International Electrotechnical Commission’s electronic component quality assessment system. It specifies the general procedures and general principles of semiconductor device quality assessment, including durability tests. Sampling according to the allowable failure rate of the batch, the durability of LED devices refers to the allowable number of failures within a given time under the specified ambient temperature of the LED device. If the number of failures exceeds the allowable number of failures, it will be judged as unqualified (rejection) ). Since the test is carried out within a given time, the test will be terminated when the time is up, so it is also called timing truncation. This method can evaluate the quality of the device in a short time. The durability of LED devices is mainly reflected in the degradation of light output (luminous flux, color temperature, color rendering index, color tolerance and other parameters) in a given time under a specified ambient temperature.
4. Evaluation method of LED application product life (GB 5080.4-85)
This method is used for the reliability assessment of electronic equipment, but the time censoring method in this standard can be used to obtain the average fault-free life and failure rate of LED application products, and the lower limit of life under a given confidence level can be obtained.
5. Graphical estimation method of LED device life test (GB 2689.2-81)
The use of Weibull distribution diagram estimation method is a basic skill that must be mastered for technicians engaged in LED life test.
This standard is mainly used to judge whether the life test data with fixed number censored is abnormal, or whether the data processing result is correct.
The Weibull distribution map estimation method is commonly used in engineering. As a tool for judging whether the test is correct, it has strong universality and is obviously applicable to LED devices.
The above five reliability standards for electronic components can not only play a role in the formulation of LED reliability standards, but also serve as a link between the past and the future. Together with the announced LED standards, they can also become regulations for the purification of the LED market.
With the progress and development of LED technology, on the basis of traditional standards, there will be more new LED industry standards and national standards to escort the healthy and orderly development of the LED industry.
Years of practice has shown that the above five standards are feasible from devices to application products, and have become the basis for electronic industry component manufacturers to formulate product standards and technical specifications, and the assessment of the reliability of LEDs is also applicable. For those who are eagerly looking forward to the introduction of LED reliability standards, it is recommended to understand these standards first, and learn to apply them flexibly.
