GB/T 2423.26-1992 Basic environmental test procedures for electrical and electronic products Test Z/BM: High temperature/low pressure comprehensive test GB/T2423.26-1992 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Basic environmental testing procedures for electric and electronic products Test Z./BM: combined dry heat/low air pressure tests GB/T 2423.26-92
Replaces GB2423.26-81
This standard adopts the international standard IEC68-2-41 (1976) "Basic environmental testing procedures Part 2 Test Test 2/BM High temperature/low air pressure test" and its 1983 amendment. 1 Subject content and scope of application
1.1 Subject content
This standard specifies the test purpose, test equipment, severity level and test procedures for the combined test of high temperature (temperature gradient and sudden change) and low air pressure of heat dissipation and non-heat dissipation test samples. : 1.2 Scope of application
1.2.1 The comprehensive test specified in this standard is usually used only when the test sample cannot obtain the comprehensive environmental impact by a single environmental test. 1.2.2 The test method specified in this standard is only applicable to test samples that can achieve temperature stability during the test. 1.2.3 The test method specified in this standard can only test one heat dissipation test sample at a time. The heat dissipation test sample should generally be tested in a test chamber without forced air circulation in accordance with the provisions of GB2423.2. 1.2.4 This standard is only applicable to pressure tests with air pressure greater than 1kPa. 1.2.5 For the relationship between altitude, pressure and temperature, see GB1920. 1.2.6 The guidance on the comparison of the application of non-heat dissipation test sample testing and heat dissipation test sample testing in GB2423.2 also applies to this standard. Note: The definition of non-heat dissipation test samples is as specified in GB2422, and the temperature of its hottest point should not be measured under low air pressure. 2 Reference standards
GB1920 "Standard atmosphere (below 30 km)" GB2421 General rules for basic environmental testing procedures for electric and electronic products GB2422 Terminology of basic environmental testing procedures for electric and electronic products GB2423.2 Basic environmental testing procedures for electric and electronic products Test B: High temperature test method GB2423.21 Basic environmental testing procedures for electric and electronic products Test M: Low pressure test method GB2423.22 Basic environmental testing procedures for electric and electronic products Test N: Temperature change test method GB242 4.1 Basic environmental test procedures for electric and electronic products Guidelines for high temperature and low temperature tests GB2424.15 Basic environmental test procedures for electric and electronic products Guidelines for temperature/low pressure comprehensive tests 3 Test purpose and general description
3.1 Test purpose
The purpose of this test is to determine the adaptability of components, equipment and other products to the high temperature and low pressure comprehensive environment encountered in their use and (or) storage.
Approved by the State Administration of Technical Supervision on July 1, 1992 276
Implementation on March 1, 1993
3.2 General description
GB/T2423.26--92
3.2.1 This test is a combination of GB2423.2 test Bb or Bd and GB2423.21 test M. 3.2.2 In the test, the test sample shall first be subjected to a high temperature test of the severity level specified in the relevant standards. If the test sample is to work during the test, it must be inspected to ensure that it can work normally. Then, while the temperature is maintained at the specified value, the pressure of the test chamber is reduced to the test pressure specified in the relevant standard. This temperature and pressure condition is maintained for the specified time. Figures 1 and 2 show the cross-section of this procedure.
Test temperature specified in the clause or subclause
Test room temperature
Test room air pressure
Specified test air pressure
3. Power on the test sample
4. Functional test and
(or) appearance inspection
Initial test
··Only for running test
·Intermediate test
8.2.5,8.2.6.8.2.7
Conditional test
Test chamber temperature
Test sample temperature
Test chamber pressure
Mold time
Test sample can be powered off
Figure 1 Test profile of non-heat dissipation test sample8.2.8
Double-use test
Terms or sub-terms
Specified test temperature
Test room temperature
Test room air pressure
Specified test air pressure
3. Test sample powered on
4. Functional test and
(or) visual inspection
4 Test equipment
4.1 Test chamber
Initial test
GB/T 2423.26--92
·Intermediate test
8.2.5,8.2.6,8.2.7
Condition test
Test chamber deterioration
Test sample temperature
Test chamber pressure
Exposure time
Test sample can be powered off
Figure 2 Test cross section of heat dissipation test sample
Slow final test
4.1.1 The test chamber shall be able to produce and maintain the test conditions specified in GB2423.2 Test Bb or Test Bd and GB2423.21 Test M. However, the temperature requirements for the chamber wall do not apply during temperature and pressure changes. 4.1.2 When restoring the pressure, the auxiliary equipment, devices and introduced air of the test chamber should be prevented from polluting the air in the test chamber. 4.2 Installation
When the heat dissipation test sample is tested, its installation should comply with the requirements specified in GB2423.2 Test Bd. 5 Severity level
5.1 General requirements
5.1.1 Severity is expressed in terms of temperature, air pressure and exposure duration. The severity level selected for the test should be specified in the relevant standards. 5.1.2 Temperature, low air pressure values ​​and their tolerances and duration should generally comply with the provisions of GB2423.2 Test Bb or Test Bd and GB2423.21 Test M.
For this comprehensive test, regardless of the size of the test chamber, the tolerance of temperature (T) is allowed to be larger. That is: ±3℃ when T≤100℃
100℃T<200℃: ±5℃
5.1.3 The exposure duration shall be calculated from the time when the test sample reaches temperature stability under low pressure conditions (see Figures 1 and 2). 5.2 Priority of temperature, pressure and duration. A set of temperature, pressure and duration values ​​shall be selected from the following table in priority. 278
6 Pretreatment
GB/T2423.26-92
Corresponding height
Relevant standards may require pretreatment and specify pretreatment atmospheric conditions and time. 7 Initial inspectionWww.bzxZ.net
Perform visual inspection and electrical and mechanical performance inspection on the test sample in accordance with relevant standards. 8 Conditional Tests
8.1 General Provisions
8.1.1 Heat Dissipation Test Specimens
Duration
The test shall be conducted in a test chamber without forced air circulation in accordance with the provisions of GB2423.2 Test Bd. If the test chamber used for the test is large enough to meet the conditions specified in GB2423.2 Test Bd, the test may be conducted using Method A of GB2423.2 Test Bd.
8.1.2 Non-heat dissipation test specimens
The test may be conducted in a test chamber with or without forced air circulation. 8.2 Test Procedure for Heat Dissipation Test Specimens without Artificial Cooling and Non-heat Dissipation Test Specimens 8.2.1 The test specimens in an unpackaged, unpowered and ready-to-use state shall be placed in the test chamber in their normal working position or in accordance with the provisions of the relevant standards. At this time, the temperatures of the test specimens and the test chamber are both the ambient temperature of the test chamber. The heat dissipation test specimens shall be powered or loaded with electrical loads. 8.2.2 The temperature in the test chamber shall be lowered to the specified test temperature at a rate not exceeding 1°C/min (not greater than the average value of 5 minutes), and the test sample shall be allowed to reach temperature stability at this temperature. The test temperature shall be measured in accordance with Article 2.7 of GB2422. Note: The maximum change rate of 1°C/min is not applicable to test samples that can withstand thermal shock, such as test samples that can usually withstand rapid temperature changes specified in Test Na or Test Nc in GB2423.22. 8.2.3 This clause is only applicable to test samples that are required to work during the test. Inspect the test sample to see if it can work according to the requirements of the relevant standards. Then keep the test sample in this working state or disconnect the power supply according to the relevant standards.
Related standards may specify other test procedures under high temperature and normal pressure. Note: Non-heat dissipation test samples can be operated or loaded. The identification of non-heat dissipation test samples shall be in accordance with the provisions of Article 1.16 of GB2422. 8.2.4 Reduce the pressure in the test chamber to the specified test value at a rate not exceeding 10kPa/min. 8.2.5 This clause is only applicable to test samples that are required to work during the test. 279
GB/T 2423.26--92
Test the test sample to see if it can work according to the requirements of the relevant standards (if the test sample is not in the working state at this time, it should be powered on or loaded before this test). After the test, the heat dissipation test sample should remain in the working state, and the non-heat dissipation test sample should remain in this working state according to the relevant standards, or disconnect the power supply. If the relevant standards have provisions, intermediate testing may be carried out in accordance with Article 9 of this standard. Before carrying out this intermediate testing, the heat dissipation test sample should first reach temperature stability.
8.2.6 Maintain this temperature and pressure condition for the specified time. 8.2.7 This clause is only applicable to test samples that are required to work during the test. During the last 1h of the low pressure time, intermediate testing shall be carried out in accordance with the requirements of the relevant standards, and then the power supply shall be cut off or the load shall be removed. 8.2.8 The pressure in the test chamber shall be restored to normal pressure at a rate not exceeding 10kPa/min, and the temperature of the test chamber shall be slowly reduced to the temperature range of the standard atmospheric conditions of the test room at a rate not exceeding 1℃/min (not greater than the average value of 5min). Note: The maximum change rate of 1℃/min is not applicable to test samples that can withstand thermal shock, such as test samples that can usually withstand the rapid temperature changes specified in Test Na or Nc.
8.2.9 Allow the test sample to recover in the test chamber or in accordance with the provisions of the relevant standards. 8.3 Precautions when testing test samples with artificial cooling See GB2423.2 Test Bd9.7.2.
9 Intermediate test
See GB2423.2 Test Bb and Bd.
10 Recovery
See GB2423.2 Test Bb and Bd.
11 Final test
Perform visual inspection and electrical and mechanical performance tests on the test samples according to the relevant standards. 12 Information to be given in the relevant standards
When applying this test method, the following applicable details should be given in the relevant standards: Pretreatment;
Initial test:
Detailed requirements for mounting frame or support (applicable to heat dissipation test samples): Test sample state (including cooling system) severity level (temperature, pressure and exposure duration), whether the temperature change is sudden or gradual, test items to be carried out at high temperature before depressurization: Inspection, measurement and loading requirements during high temperature/low pressure test; Load conditions during recovery,
Final test.
Additional Notes:
This standard was proposed and managed by the National Technical Committee for Environmental Conditions and Environmental Test Standards for Electrical and Electronic Products. This standard was drafted by the 301st Research Institute of the Ministry of Aerospace Industry and the Guangzhou Electrical Science Research Institute of the Ministry of Machinery and Electronics. The main drafters of this standard are Zhu Yaochang, Xia Yuemei and Xu Guobao. 280
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