GB/T 2424.19-1984 Basic environmental testing procedures for electrical and electronic products Guidelines for environmental testing simulating storage effects GB/T2424.19-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Basic environmental testing procedures for electric and electronic productsGuidance for the environmental testssimulating the effects of storage
Basic environmental testing procedures for electric and electronic productsGuidance for the environmental testssimulating the effects of storageThis standard applies to electric and electronic products.
The purpose of formulating this standard is to guide the selection of appropriate storage test methods and test severity levels. UDC 621.3 :620.1
GB 2424.19-84
This standard is equivalent to the international standard IEC68-2-48 "Guidelines for the use of test methods of IEC68 standard to simulate the effects of storage" (first edition in 1982).
1 Definition of storage
In this guideline, storage refers to the storage of components, equipment or other products in a non-working state (such as one of the following three conditions) for a relatively long period of time (from weeks to thousands of years).
a. In environmental conditions such as industrial warehouses and commercial retail warehouses. b. Equipment or complete sets of equipment for standby or emergency use. For example: fire alarms, auxiliary motors, standby generators, etc. Due to the influence of the operation of surrounding equipment, they may be subjected to severe environmental stress. c. Complete sets of equipment that take a long time to install. For example: large telephone exchanges, large computer equipment, power stations, etc., whose initial environment is much more severe than the working environment.
Note: Professional standards for environmental data related to the above conditions should be referred to. 2 Definition and purpose of storage test
Storage test refers to the simulation of the impact of one or more environmental stresses on the product during the specified storage life of the product. When fatigue accumulation exists, storage test can be used to determine the following issues: a. Whether storage affects the use of the product in its intended application. For example: whether the solderability of component leads or printed circuit boards deteriorates; whether it exceeds the specified electrical parameter drift value, and whether it causes an open circuit or a short circuit; b. After storage, whether the main performance or reliability of the product is reduced when it is working; c. For emergency equipment, whether its accurate and reliable operating ability is damaged after a long period of non-operation. Note: To determine the reliability of stored products or the reliability of product operation after storage, reference should be made to the reliability and maintainability standards for electrical and electronic products. 3 Examples of deterioration mechanisms and failure types under storage conditions 3.1 The solderability of component leads and printed circuit boards can be reduced due to oxidation or diffusion processes between the base material and the plating. High temperatures accelerate these processes and form a surface with greatly reduced solderability. Wet corrosion can also reduce solderability, and this corrosion is often accelerated by pollutants in the atmosphere.
3.2 Examples of failure mechanisms caused by humidity changes. 3.2.1 Even at relatively low temperatures, long-term low humidity can dry out certain plastics. When these materials are used after storage, their electrical and mechanical properties will decrease, resulting in damage or failure. Issued by the National Bureau of Standards on December 24, 1984
Implemented on July 1, 1985
GB 2424.19-84
3.2.2 Due to the lack of any natural effects, high humidity during storage is more dangerous than high humidity during operation. Therefore, long-term storage under conditions of relative humidity above 80% will have a harmful effect on the performance and reliability of the product. 3.2.3 When stored under conditions of high relative humidity with repeated peaks, or under general high humidity conditions with temperature fluctuations, the humidity inside an incompletely sealed container will gradually increase. Therefore, after long-term storage, condensation will form inside the container due to a sudden drop in temperature. 3.2.4 Products, especially organic materials, stored under conditions of high temperature and high humidity will be affected by mold growth. High temperature and high humidity can also accelerate chemical reactions such as salt spray and industrial gases. 3.3 Examples of other failure mechanisms
3.3.1 Long-term exposure to high temperature ambient conditions can cause electrolyte drying of electrolytic capacitors and batteries: thermoplastic materials lose rigidity, protective glue and impregnating wax soften or creep. Generally, under such conditions, material aging can be accelerated. 3.3.2 Long-term exposure to low temperature ambient conditions can cause rubber, plastic and even metal parts to become brittle, crack and break. - Some seals can be damaged by shrinkage or cracking. bzxz.net
3.3.8 Long-term exposure to dusty atmospheres can cause dust to accumulate between conductors. Under the accelerated action of moisture, it can cause insulation resistance to drop, leakage and metal corrosion.
3.4 ​​Mechanical parts can become blocked or stuck due to high temperature oxidation or moisture corrosion. 3.5 Functional parameters of the product drift beyond the specified range. Open circuits or short circuits may occur. 4 Selecting the appropriate test
Because different parameters produce different stresses, these stresses can produce different types of damage or failure modes. Therefore, it is impossible to specify a single storage test.
The test methods of GB2423 "Basic Environmental Test Procedures for Electrical and Electronic Products" can be used to simulate specific storage conditions. The usual storage tests are based on test A: low temperature, test B: high temperature, and test Ca: constant damp heat. The test time is generally very long (the longest time for test Ca is 56 days), and some may be as long as several months. For some situations (such as salt spray, industrial atmosphere, etc.), other tests may be more important, and these tests should be considered when formulating detailed storage specifications. It must be pointed out that the above test methods are not intended to simulate actual conditions. Therefore, in some cases, some special tests are required. However, from technical and economic considerations, standard test methods should be used whenever possible. When selecting appropriate tests, the relevant specification developers should consider the following points: a. Test purpose (see Chapter 2),
b. Expected degradation mechanism and failure mode: these can be known from experience or analysis of product characteristics and storage conditions, and are related to the interaction between environment and materials (see Chapter 3), c. Involving major environmental stresses: This stress may be a single, combined or sequential stress, d. In the case where the failure mode does not change substantially or does not induce new failure modes, consider the possibility of accelerating the progress of the degradation mechanism. 4.1 The corresponding guidelines of GB2423 test method should be referred to. Taking into account the purpose of storage test, this guide lists special provisions that must be followed when selecting the test severity level. 4.2 Accelerated tests used to effectively shorten the test time cannot always be achieved by increasing the stress method. This is because this will cause a great change in the degradation mechanism and thus fail to obtain test results of practical value, for example: a. Regardless of the humid corrosion phenomenon caused by the participation of light atmospheric pollutants, the corrosion products produced by increasing the relative humidity will be different in morphology from the corrosion products formed under natural conditions. b. As a result of the absorption of water vapor by the insulating material, especially the result of irreversible effects caused by changes in the material structure, it is more appropriate to use lower temperature and humidity conditions (lower than the conditions specified in test Ca: constant damp heat). This is especially true when analyzing the impact of water vapor absorption on poorly protected products.
C. The slow deformation of some materials under natural conditions is very important for the drift of electronic components and device parameters. This is often different from the phenomenon caused by large temperature changes. 4.3 In some cases, storage tests can be continued for a long time. The effectiveness of the test does not lie in shortening the time to obtain the test results, but in controlling and reproducing the phenomena that occur under the conditions. 611
GB2424.19-84
In general, for tests of long duration and limited stress, greater variations in test conditions can be tolerated compared with high stress accelerated tests, so that the control and adjustment of the test equipment can be simplified. 4.4 In other cases where the degradation mechanism is not substantially changed, the stress can be increased to accelerate the test, for example: a. Increasing the test temperature can accelerate the electrolyte dry-out of electrolytic capacitors and batteries. In general, exposure of materials to high temperatures will accelerate the aging process.
b. Exposure to temperatures below the actual storage temperature can accelerate the embrittlement, cracking and fracture of rubber, plastics and some metals caused by low temperatures.
5 Details of the test procedure
Storage tests do not require more care than tests used for other purposes (performance determination, identification, etc.). Normal protective measures used in general tests, especially those related to the use of test equipment and control instruments, are applicable to storage tests. Special attention should be paid to the measurement of functional parameters during and after long-term tests. The recovery conditions after the test are important. For example, dehydrated materials may begin to absorb moisture, and materials that have absorbed or adsorbed moisture begin to dry. In this case, the recovery conditions should be determined and strictly controlled (refer to GB2423 test method). Note: See GB2421-81 "General Principles of Basic Environmental Test Procedures for Electrical and Electronic Products" 4.4.1 "Controlled recovery conditions". Additional notes:
This standard was proposed by the National Technical Committee for Standardization of Environmental Conditions and Environmental Testing for Electrical and Electronic Products (hereinafter referred to as the Environmental Standards Committee). This standard was drafted by the Storage Environment Working Group of the Environmental Standards Committee. The main drafters of this standard:
Hao Xueming, Zhao Peiyu, Zhong Huaijing of Guangzhou Electrical Science Research Institute Wang Xiurong of the 301st Institute of the Ministry of Aviation Industry
Li Zhiqing of the 5th Institute of the Ministry of Electronics Industry
Zhu Xuan of the Standardization and Metrology Institute of the Ministry of Railways
Che Naizhong of the Standardization Institute of the Ministry of Posts and Telecommunications
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.