Reliability test: introduction to conventional reliability items and types

Date：2021-04-26 16:17:00Views：2102

Reliability test is a means to investigate, analyze and evaluate the reliability of products. The test results provide a basis for fault analysis, study the corrective measures taken and judge whether the product meets the index requirements. 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 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.

Routine reliability test items:

1. Climate and environment test: high temperature test, low temperature test, temperature and Humidity Cycle / constant damp heat test, cold and heat shock test, rapid temperature change test, low pressure test, light aging test, corrosion test, etc.

2. Mechanical environment test: vibration test, impact test, collision test and drop test.

3. Comprehensive environmental test: temperature + humidity + vibration / shock / collision, halt / Hass / hasa, temperature and humidity stacking test, high-pressure cooking test.

4. Packaging materials and packaging transportation test: ambient temperature and humidity test, stacking test, packaging compression test, vibration test, impact test, drop test, collision test, horizontal clamping test and low air pressure test.

5. IP protection test: dustproof test and waterproof test.

6. Physical property test: 100 grid test, wear resistance test, scratch test, plug test, bending test, color fastness test, fire / combustion test; Swing test, key life test, hardness test, drop impact / pendulum impact test, tensile strength / compressive strength / yield strength test, melt index test.

7. EMC environment test: RF performance test, SAR test, OTA test, HAC test, tcoil test, digital TV performance test, audio and video product performance test, satellite navigation product (GPS) performance test, flat panel display performance test, China medical device registration test, China telecom network access license test.

8. Electrical performance test: temperature rise test, withstand voltage test, insulation resistance test, dielectric strength test, contact resistance test, surface resistivity test and grounding resistance test.

Introduction to reliability test types:

1. If 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. If it is divided according to the test purpose, it can be divided into screening test, identification test and acceptance test;

4. If divided according to the nature of the test, it can also be divided into destructive test and non-destructive test.

5. However, the usual classification is to classify it into five categories:

A.environmental test

Environmental test is to assess the adaptability of products under various environmental conditions (vibration, impact, centrifugation, temperature, thermal shock, hot tide, salt spray, low air pressure, etc.), and it is one of the important test methods to evaluate the reliability of products.

B.life test

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 examine the variation law of failure (damage) with time under specific test conditions. Through the life test, we can understand the life characteristics, failure law, failure efficiency, average life and various failure modes that may occur 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. In order to shorten the test time, the accelerated life test can be carried out by increasing the stress without changing the failure mechanism. The reliability level of products can be evaluated through life test, and the reliability level of new products can be improved through quality feedback.

C.Screening test

Screening test is a non-destructive test for full inspection of products. The purpose is to select products with certain characteristics or products with early failure, so as to improve the service reliability of products. In the manufacturing process of products, some products have so-called early defects or faults due to material defects or out of control of process. If these defects or faults can be eliminated as soon as possible, the reliability level of products in actual use can be guaranteed. The characteristics of reliability screening test are: A. This test is not sampling, but 100% test; B. This test can improve the overall reliability level of qualified products, but can not improve the inherent reliability of products, that is, it can not improve the service life of each product; C. The screening effect cannot be evaluated simply by 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 due to too high screening stress intensity. The elimination rate is low, there may be few product defects, but it may also be caused by insufficient strength of screening stress and test time. Usually based on the screening elimination rate Q and screening effect β Value to evaluate the advantages and disadvantages of screening methods: a reasonable screening method should be β The value is large, while the Q value is moderate.

D.Field service test

The above tests are carried out by simulating field conditions. Due to the limitation of equipment conditions, the simulation test can only apply single stress to the product, and sometimes double stress, which is very different from the actual use environmental conditions, so it fails to truthfully and comprehensively expose the quality of the product.

The field use test is different because it is carried out on the use site, so it can most truly reflect the reliability of the product. The data obtained is of high value for the reliability prediction, design and guarantee of the product. The field application test plays a greater role in formulating the reliability test plan, verifying the reliability test method and evaluating the test accuracy.

E.Qualification test

Qualification test is a test done when evaluating the reliability level of products. It is a sampling scheme based on sampling theory.