The LED chip process analysis of life test

Share the LED has small volume, low power consumption, long life advantages, such as environmental protection, in the process of actual production research and development, need to life test to evaluate the reliability of the LED chip level, and through the quality feedback to improve the reliability of the LED chip level, to ensure the quality of the LED chip. Electronic components with low quote, light-emitting diode ( LightEmittingDiode - 领导) Has been more than 40 years, but for a long time, limited to the luminous efficiency and brightness, only for use by light, until the end of last century broke through the technical bottleneck, produce the high brightness leds and lincom LED with high efficiency, extended to the use of light, city light engineering, full color, etc. , provided the possibility for the lighting light source. As the LED application range, improve the LED reliability has more important significance. Leds have the advantages of high reliability and long life, in the process of actual production research and development, need to life test to evaluate the reliability of the LED chip level, and through the quality feedback to improve the reliability of the LED chip level, to ensure the quality of the LED chip, so at the same time of realizing industrialization of full color LED, developed the LED chip life test conditions, methods, means and devices, etc. , in order to improve the accuracy of the science and the results of the life test. The determination of the low life test in the regulation of electrical products and environmental conditions, the ongoing work of the test is called the life test, also called durability test. With the improvement of LED production technology level, the life and reliability of the product improved, LED the theory of life of 100000 hours, if still adopts the conventional life test under normal stress rating, it is very hard to the life and reliability of the product to make relatively objective evaluation, and the main purpose of our experiment is to, through the life test master LED chip light output attenuation situation, thus infer that its life. According to the characteristics of the LED device, through the contrast test and statistical analysis, the final rules for 0. 3×～0. 3 was the life of the chip under the test conditions, samples randomly, number is 8 ~ 10 chips, made ф 5 single lamp; Working current is 30 ma; Environmental conditions for room temperature ( 25℃±5℃) ; Test period is 96 hours, 1000 hours and 5000 hours. The working current of 30 ma is a rating of 1. 5 times, is to increase the electric stress life test, although the result does not represent a real life situation, but has great reference value; Life test for epitaxial wafer production batch of mother sample, a random sample of a piece of 8 ~ 10 particles in the epitaxial wafer chip, encapsulated into a ф 5 single lamp device, life test for 96 hours, the results on behalf of all the extension of the production batch. It is generally believed that test period is 1000 hours or more are called life test for a long time. Production process stability, 1000 hours of life test frequency is low, 5000 hours of life test frequency can be lower. Low process and matters needing attention for the LED chip life test sample, and can be used in a chip, generally called naked crystal, also after encapsulation, the device can be used. USES the naked crystal form, the external stress is small, easy to heat dissipation, so the light failure is small, long service life, and the actual application of the gap is bigger, although can be adjusted by increasing current, but not directly in the form of single lamp device intuitive. Life test with single lamp device form, and caused the light of the device aging factors of complex, there may be factors of chip, also have packaging. In the process of test, adopt various measures to reduce the effects of encapsulated factors, that is likely to affect the life test result accuracy details, one by one, to improve, to ensure the life of the objectivity and accuracy of the test results. 1, sample extraction way life test only USES the evaluation method of sampling test, have a certain risk. First of all, the quality of the products have a certain degree of homogeneity and stability is the precondition of sample evaluation, only believe that the quality of the products is uniform, sampling is representative; Second, because in the real product quality has certain discreteness, random sampling method, we take the partition in order to improve the life test result accuracy. We by looking for related information and a lot of contrast test, and put forward a more scientific way of sample extraction, the chip according to its position in the epitaxial wafer is divided into four area, were 2 ~ 3 chip, a total of 8 ~ 10 chips, for different device life test results of six to one, and even contradictory situation, we stipulated the strict life test method, namely were 4 ~ 6 chip, a total of 16 ~ 20 grains chips, according to the normal conditions of life test, just number add yan, rather than add strict test conditions; Third, generally speaking, the more sampling, the smaller the risk, the more accurate the result of the life test results, however, the more sampling sampling quantity too much, will cause the waste of manpower and material resources and time, test costs. How to deal with the relationship between the risk and cost, has been our research, our goal is to take scientific sampling methods, under the same test cost, resulting in a risk to the minimum.

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