Life test of electronic products - Reliability Test

Date：2022-04-08 15:13:52Views：1212

Reliability test is a means to investigate, analyze and evaluate the reliability of products. The test to evaluate and analyze the life characteristics of products is called life test. It is the most important type of test in reliability identification and acceptance test. Life test can be divided into storage life test, working life test and accelerated life test. Through the life test, we can understand the characteristics and failure law of product life, and calculate the reliability indexes such as average life and failure rate of products, which can be used as an important basis for reliability design, reliability prediction and improving product quality.

Life test is a test that simulates the actual working conditions under laboratory conditions. Although there is still some approximation in this simulation, the test results have great reference value. This test can not only be used to assess the reliability of parts and structures, the rationality of materials and manufacturing technology, but also identify and improve the quality of products. According to the method and purpose of reliability statistical test, reliability statistical test can be divided into reliability verification test and reliability measurement test. Reliability measurement test is a test for measuring reliability characteristics or their values, which is usually used to provide reliability data. Reliability verification test is a test used to verify whether the reliability characteristic value of equipment meets the specified reliability requirements. Generally, reliability identification and acceptance test are collectively referred to as reliability verification test.

1. Divided by environmental conditions, it can be divided into simulation test and field test under various stress conditions;

2. Divided by test items, it can be divided into environmental test, life test, accelerated test and various special tests;

3. According to the test purpose, it can be divided into screening test, identification test and acceptance test;

4. According to the test nature, it can also be divided into destructive test and non-destructive test;

5. However, the commonly used classification method is to classify it into five categories: environmental test, life test, screening test and field use test.

The life test is subdivided into different categories (see the figure below)

In summary, the purpose of life test is three points:

1. Clarify the life distribution of products

Finding out the life distribution of parts or products through life test is of great significance to design and application. For example, the service life of bearing follows Weibull distribution; The lifetime of electronic components conforms to the normal distribution of Weibull and logarithm; The high temperature endurance life of alloy steel obeys lognormal distribution; The system composed of a large number of electronic components obeys exponential distribution and so on.

2. Obtain various reliability indexes of the product

Through the life test, the failure rate, failure density, failure probability, reliability, average life, life variance and other indicators of the product can be obtained, so as to evaluate the quality of the product.

3. Study the failure mechanism of products

Through the life test, the causes of product failure can be found out, and on this basis, the physical and mathematical models of product failure can be established, the failure mechanism can be clarified, and the model can be used for theoretical prediction.

Function of life test in reliability test

Life test is one of the most important and basic contents in reliability test. It is to put the sample under the special test conditions, and dac8550ibdgkrg4 measures the distribution of the number of failures (losses) with time. Because failures occur in order, the order statistics theory can be used to analyze the life test data, so as to determine the life characteristics and failure distribution law of products, and calculate the reliability indexes such as failure rate and average life of products. In addition, it can also determine the reasonable reliability screening process and conditions of products, and further improve the basis for ensuring product quality.

Effective life test items

High accelerated life test (HALT) and accelerated life test (ALT) are the two most effective reliability test technologies used in product reliability design. High accelerated life test is suitable for finding design defects, determining failure mechanism and describing product margin. When the main failure mechanism is not caused by wear, it is best to use high accelerated life test. The accelerated life test is suitable for describing the failure mechanism caused by wear. It is usually used to test the failure of the organization when it exceeds the user's expectation and beyond the warranty period.

In most cases, the two methods are best used together. Because each method is suitable for revealing different types of failure mechanisms. The proper combination of the two methods provides a complete and comprehensive test means for product reliability design.

High accelerated life test (HALT) was first proposed by Dr. Gregg K Hobbs, President of Hobbs engineering company in the United States. Since the 1990s, halt has been popularized and applied. The biggest feature of halt is time compression, that is, simulate the situation that may be encountered during the whole life of a product in just a few days.

Relevant standards for life test

GB2689. General and accelerated life test method 81-1

GB2689. 2-81 graph estimation method for life test and accelerated life test (for Weibull distribution)

GB2689. 3-81 simple linear unbiased estimation method for life test and accelerated life test (for Weibull distribution)

GB2689. 4-81 best linear unbiased estimation method for life test and accelerated life test (for Weibull distribution)

Life test is a method to study the life characteristics of products. This method can simulate various service conditions in the laboratory. Life test is one of the most important and basic items in reliability test. It is to put the product under specific test conditions to investigate the variation law of its failure (damage) with time. Through the life test, we can understand the life characteristics, failure law, failure efficiency, average life and various failure modes that may appear in the process of life test. For example, combined with failure analysis, the main failure mechanism leading to product failure can be further clarified as the basis for reliability design, reliability prediction, improving new product quality and determining reasonable screening and routine (batch guarantee) test conditions.