The characteristics and methods of electronic product reliability test and its introduction

First, the reliability test of electronic products:

The test conducted to evaluate and analyze the reliability of electronic products is called reliability test. The purpose of the test is usually as follows:

1. In the development stage, it is used to expose the defects in all aspects of the trial-produced products and evaluate the reliability of the products to reach the predetermined indicators.

2. The production stage provides information for monitoring the production process.

3. Carry out reliability evaluation or acceptance of stereotyped products.

4. Expose and analyze the failure laws and related failure modes and failure mechanisms of products under different environmental and stress conditions.

5, in order to improve the reliability of the product, develop and improve the reliability test program, to provide a basis for users to choose products.

For different products, in order to achieve different purposes, you can choose different reliability test methods. Reliability tests have a variety of classification methods, such as by environmental conditions, can be divided into simulated tests and field tests under various stress conditions. According to the test project, it can be divided into environmental test, life test, accelerated test and various special tests. According to the purpose of the test, it can be divided into screening test, identification test and acceptance test. If it is divided according to the nature of the test, it can also be divided into two categories: destructive test and non-destructive test. However, the commonly used classification method is to summarize it into five categories, namely, environmental test, life test, screening test, field use test and identification test.

1, environmental test is to assess the adaptability of products under various environmental conditions (vibration, shock, centrifugation, temperature, thermal shock, hot flash, salt spray, low pressure, etc.), is one of the important test methods to evaluate product reliability.

2, the life test is a method to study the life characteristics of the product, which can be carried out in the laboratory to simulate various conditions of use. Life test is one of the most important and basic items in reliability test, which is to investigate the failure (damage) of the product under specific test conditions with time. Through the life test, we can know the life characteristics, failure rule, failure rate, average life and various failure modes that may occur in the course of life test. If combined with failure analysis, the main failure mechanism leading to product failure can be further clarified, which can be used as the basis for reliability design, reliability prediction, improvement of new product quality and determination of reasonable screening and routine (batch guarantee) test conditions. If in order to shorten the test time, the test can be carried out by increasing the stress without changing the failure mechanism, this is the accelerated life test. The reliability level of products can be evaluated by life test, and the reliability level of new products can be improved by quality feedback.

3, screening test is a non-destructive test for all product inspection. The purpose is to select products with certain characteristics or to eliminate early failure products to improve the reliability of the use of products. In the manufacturing process of the product, due to the defects of the material, or due to the process is out of control, so that some products appear so-called early defects or failures, these defects or failures can be eliminated early, you can ensure the reliability level of the product in actual use.

2. The characteristics of reliability screening test are:

1, This test is not sampling, but 100% test.

2, the test can improve the overall reliability level of qualified products, but can not improve the inherent reliability of the product, that is, can not improve the life of each product.

3. The screening effect can not be evaluated simply by the level of the screening elimination rate. The high elimination rate may be due to serious defects in the design, components, and process of the product itself, but it may also be that the screening stress intensity is too high. Low elimination rate, there may be fewer product defects, but it may also be caused by the strength of the screening stress and insufficient test time.

Generally, the screening elimination rate Q and screening effect β value are used to evaluate the merits of the screening method: a reasonable screening method should be a large β value and a moderate Q value.

The above tests are carried out by simulating the field conditions. Due to the limitations of equipment conditions, the simulation test can often only apply a single stress to the product, and sometimes can also apply double stress, which is very different from the actual use of environmental conditions, so it can not truthfully and comprehensively expose the quality of the product. Field use test is different, because it is carried out in the use of the site, it can most truly reflect the reliability of the product, the data obtained for the reliability of the product prediction, design and guarantee of high value. Field use test plays a more important role in making reliability test plan, verifying reliability test method and evaluating test accuracy.

Qualification test is a test performed to evaluate the reliability level of a product. It is a sampling scheme based on sampling theory. Qualification tests are carried out in such a way as to ensure that the producer does not cause the rejection of products of quality conforming to the standards.

Third, reliability test method:

There are many kinds of reliability test methods for electronic products, and several commonly used methods are introduced below.

The first approach is the "test - problem - record - test again" model. This method is to take the preliminarily developed products, through the test found the problem, not to improve immediately, but to record the problem, to be at the end of a test stage and before the next stage, according to the failure mechanism of various failure modes, concentrated improvement, and then the test. Using this test method, the reliability of products will have a great leap forward. This test method is more suitable for a batch of testing machines, there are several problems, one of which is the main problem and the rest of the problem is secondary.

The second approach is the "trial-improve-try" model. This method is to expose the weak link of the product through the test, analyze the failure mode and failure mechanism of the product, find out the problem and immediately improve, and then test to confirm the solved problem, so that the reliability of the product is increased. This method in the development stage of electronic products, through the system test, exposed the weak links of the product, according to the specific situation, immediately make the necessary improvement is able to make the reliability of the product has a substantial increase, this method is more suitable for the test only a more common and serious problem situation, more targeted.

The third method is the "trial-improve-retest with deferred improvement" model. This method is a combination of method 1 and method 2, through the test found the problem of the product, some improvements in the test in the product problems, some improvements in the test immediately started, some delayed until the end of the test to make improvements. In the test, for the problems that can be improved in time, immediate measures are taken to improve the product and improve the reliability. After the end of the test phase, the delayed problems are improved before the next test begins, and then the test is carried out, so that the reliability of the product is greatly increased. This method is more suitable for several problems in the test, and some problems can be easily improved in the short term, while others need a considerable period of time to improve the comprehensive situation.

For the above three methods, electronic products in the development stage, after systematic tests, according to the exposed problems for specific analysis, flexible application. The three methods commonly used in reliability test are often repeated, and the reliability level of a cycle is higher than that of a cycle product. In addition, reliability test should expose the weak links of product production through various aspects of climate environment test, mechanical environment test and human normal use test according to the specific situation, in addition to system test. Through comprehensive scientific analysis and corresponding improvement, the inherent reliability of electronic products can be further improved in the design and development stage.

Iv. Concluding remarks

The reliability of electronic products is very important and is the main index of product quality. The reliability test of electronic instruments in China follows the standard GB11463 "Reliability Test of Electronic Measuring Instruments". The reliability index of general products in the identification is 300H. If the reliability assessment is carried out according to the commonly used timed truncated test scheme, the total test time should reach about 10000H. Because the electronic products in the design and development stage has experienced many times the "test - analysis - improvement - re-test" reliability growth test process. In this process, due to a series of measures such as improving the design and process measures to eliminate the failure, the occurrence of failure is gradually reduced, and the reliability is increased. The reliability indicators of some electronic products in China are still short of international advanced standards, so we must fully study the relevant standards at home and abroad, and truly evaluate the reliability level in the whole process of product program demonstration, design, production, testing and use, so as to greatly improve the reliability level of electronic products in China and make product quality reach the world advanced level.