GB/T 2423.40-1997 Environmental testing for electric and electronic products Part 2: Test methods Test Cx: Unsaturated high pressure steam steady state wet heat
Some standard content:
GB/T2423.40—1997
This standard is equivalent to the international standard IEC68-2-66 (first edition in 1994) "Environmental testing Part 2: Test method Test Cx: Unsaturated high pressure steam steady humidity heat" to revise GB/T2423.40-90 Basic environmental testing procedures for electrical and electronic products "Unsaturated high pressure steam steady humidity heat test method". The main technical differences between this standard and GB/T2423.40-90 are: 1. Special requirements are put forward for the test chamber and humidification water, such as the requirements for the resistivity and pH value of the humidification water; 2. The test duration of the severity level is changed from two to three at each temperature, the tolerance of relative humidity is relaxed from ±3% to ±5%, the tolerance of the test time is relaxed from ±5min to 0~+2h, and the concept of uniformity is given. 3. This standard has four new appendices, which solve the problem of measuring relative humidity at high temperatures (110℃, 120℃, 130℃) during the implementation of the standard, and provide structural schematic diagrams of two test chambers, etc. This standard is the 40th part of the GB/T2423 series of standards for environmental testing of electric and electronic products. The standards involving damp heat testing in this series of standards are:
GB/T2423.3-93 Basic environmental testing procedures for electric and electronic products Test Ca: Steady damp heat test method GB/T2423.4-93 Basic environmental testing procedures for electric and electronic products Test Db: Alternating damp heat test method GB2423.9-89 Basic environmental testing procedures for electric and electronic products Test Cb: Steady damp heat test method for equipment GB2424.2-93 Basic environmental testing procedures for electric and electronic products Guide to damp heat testing Appendix A of this standard is a standard appendix, and Appendix B, Appendix C and Appendix D are prompt appendices. GB/T2423.40-90 shall be abolished as of the date of promulgation and implementation of this standard. This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Environmental Conditions and Environmental Tests for Electrical and Electronic Products. The drafting unit of this standard: Guangzhou Electric Science Research Institute of the Ministry of Machinery Industry. The drafter of this standard: Xie Jianhua.
This standard was first issued in November 1990, and this revision is the first revision 381
GB/T2423.40-1997
IEC Foreword
1) IEC (International Electrotechnical Commission) is a worldwide standardization organization composed of various national electrotechnical committees (IEC National Committees). The purpose of IEC is to promote international cooperation on standardization issues in the field of electrical and electronic engineering. To this end, IEC, among other activities, also publishes international standards. International standards are formulated by technical committees, and any IEC National Committee interested in the standards formulated can participate in this formulation work. International organizations, governmental and non-governmental organizations associated with IEC can also participate in this formulation work. IEC and ISO (International Organization for Standardization) work closely together under the conditions determined by the agreement between the two organizations. 2) IEC's formal agreements and decisions on technical issues are made by technical committees in which countries with special interests in the issue are represented. They express the international consensus on the issues under discussion as accurately as possible. 3) IEC's formal resolutions or agreements are published in the form of standards, technical reports or guidelines, which are recommended for use by various countries and accepted by the various national committees in this sense. 4) In order to promote international unification, each IEC national committee explicitly commits to adopt IEC international standards to the maximum extent possible in its national and regional standards. Any differences between IEC standards and corresponding national or regional standards should be clearly indicated in the latter. International standard IEC68-2-66 was formulated by Subcommittee 50B of Technical Committee 50 (Environmental Testing). The text of this standard is based on the following documents: DIS
50B(CO)342
Voting Report
50B(CO)345
Full voting information for the approval of this standard can be found in the voting report indicated in the table above. According to IEC Guide 104, this standard has the status of a basic safety publication. The general title of IEC68 is environmental testing, which includes the following parts: - Part 1: General;
Part 2 Tests;
- Part 3: Background information;
- Part 4: Information for specification writers - Key points of testing; Part 5: Guidelines for writing test methods.
Appendix A is an integral part of this standard. Appendix B, Appendix C and Appendix D are informative appendices. 382
1 Scope
National Standard of the People's Republic of China
Environmental testing for electric and electronic products
Part 2: Test methods
Test Cx : Damp heat,steady state (unsaturated pressurized vapour)GB/T 2423. 40 -1997
idt IEC 68-2-66:1994
Replaces GB2423.40-90
This standard specifies a standard test method for evaluating the resistance of small electric and electronic products, mainly non-hermetic components, to the effects of damp heat degradation in an accelerated manner.
This test is not suitable for evaluating external effects such as corrosion and deformation. 2 Overview
In this test, the test specimen is subjected to extremely high levels of unsaturated hot and humid steam for a relatively short period of time. An electrical bias is usually applied.
Because this test is highly accelerated, it has a significant impact on the type of failure mode that may occur (see Annex B). Therefore, careful consideration must be given to the choice of test conditions. This test specifies three test temperatures under conditions of 85% relative humidity. The test severity level is determined by one of the temperatures and duration.
It should be noted that the maximum rated temperature of the test specimen and the critical temperature of the packaging material, or both, should not be reached. For example, the glass transition temperature of plastic is a typical critical transition temperature. For plastic encapsulated components, degradation is caused by the absorption of water vapor by the plastic and the penetration of moisture along the lead terminals. 3 Description of the test apparatus
3.1 Test chamber
The construction of the test chamber should:
a) be able to produce the temperatures and relative humidity given in Table 1 and to maintain the pressure values given in Note 3 of Chapter 4. b) It can provide controlled temperature, relative humidity and pressure conditions during the test and can rise or fall to the specified test conditions at the required slope.
c) The temperature and humidity of the test chamber can be monitored by sensitive devices located in the working space and/or in other areas (such as steam generators) that can give the same results.
Note: Under the current technical level, it is not possible to directly measure the relative humidity during the test. For guidance on the determination of relative humidity in the working space, see Appendix C.
Approved by the State Administration of Technical Supervision on December 26, 1997 and implemented on December 1, 1998
GB/T 2423.40--1997
d) The air in the confined space can be exhausted from the test chamber by water vapor before the test begins. e) Condensation is not allowed to fall on the test specimens. f) The structural materials used should not cause corrosion to the test specimens or deteriorate the quality of the water used for humidification (see D2 in Appendix D). The temperature tolerance of ±2°C is used to take into account the absolute measurement error, temperature fluctuations at any point and temperature variations between all points in the working space. However, in order to maintain the relative humidity tolerance within the specified ±5%, the temperature difference between any two points in the working space (at any moment) must be kept within a narrower range.
If the temperature difference is greater than 1.5°C, the specified relative humidity tolerance will be exceeded. At the same time, it is also necessary to limit the short-term temperature fluctuations caused by the periodic operation of the test chamber heater to similar values. The test sample should not significantly block the flow of steam. Condensation is not allowed to form on the test sample at any time during the test. 3.2 Humidification water
Distilled water or deionized water should be used. At 23°C, the resistivity of water should not be less than 0.5M2·cm and the pH value should be between 6.0 and 7.2.
Before filling the humidifier with water, all parts inside the test chamber should be cleaned. Cleaning guidelines are given in Appendix D. 4 Severity level
Unless otherwise specified in the relevant specification, one of the combinations of temperature and duration in Table 1 should be used. Three durations are specified for each temperature.
Table 1 Severity level
Relative humidity
1) The temperature tolerance in the working space of the test chamber is ±2%; 2) The humidity tolerance in the working space of the test chamber is ±5%; 3) The tolerance of the test duration is 0~+2h. Note
Duration (h) 3)
Although it is not recommended to restart a test, if the test sample is required to withstand a longer duration than the first column of Table 1 at the same given temperature, the test should be restarted according to the requirements of 6. This test should be restarted within 96 after the end of the cooling stage of the previous test. Unless otherwise specified in the relevant specification, the test sample should be kept under the standard atmospheric conditions for measurement and testing during the interval between each test. 2 Under the specified test conditions, the test duration does not include the additional time required for the temperature rise and fall phases, the time for cleaning the test chamber and the preparation time. 3 At 110°C, 120°C and 130°C, the steam pressure is approximately 0.12MPa, 0.17MPa and 0.23MPa respectively. 5 Initial inspection
The test sample shall be subjected to visual inspection, dimensional inspection and functional inspection as specified in the relevant specifications. 6 Test
6.1 With the test chamber and the test sample both at laboratory temperature, pressure and humidity conditions, place the test sample in the working space of the test chamber.
6.2 Positioning and mounting of the test sample
The test sample shall not be affected by radiant heat from the heater or the walls of the test chamber. If required by the relevant specifications, a special mounting device shall be used. The thermal conductivity and heat capacity of the mounting fixture shall be low enough so that the test sample is insulated for all practical purposes. GB/T2423.40--1997
Care should be taken in selecting the materials of the mounting device and the mounting fixture to minimize the effects of contaminants and to minimize the effects of degradation due to corrosion and other mechanisms (see D2 in Appendix D). 6.3 Bias
If required by the relevant specification, a bias shall be applied to the test specimen during the exposure period. Guidance on the application of bias is given in Appendix D. The bias (or bias cycle) shall be applied to the test specimen after the temperature and relative humidity have reached a stable state and shall continue until the test specimen is under recovery conditions.
6.4 Test cycle
6.4.1 The temperature of the test chamber is raised to an appropriate value, during which the air enclosed in the test chamber is driven out of the test chamber by means of steam, but the temperature and relative humidity shall not exceed the specified values. No condensation shall be allowed on the test specimen at any time during the test cycle. The temperature and relative humidity shall reach stability within 1.5 h. However, if the specified test duration is longer than 48 h and stability is achieved within 3 h, the test requirements are deemed to be met even if the stabilization time is longer than 1.5 h.
6.4.2 During the test duration specified in the relevant specification, the temperature and relative humidity shall be maintained within the specified tolerance range. As soon as the temperature and humidity conditions are stable, the test duration shall be calculated. 6.4.3 After the specified test time, the pressure, temperature and relative humidity in the test chamber shall be restored to the standard atmospheric conditions for measurement and testing within 1 h to 4 h.
During this stage, the temperature and relative humidity shall not be greater than the specified values. These conditions can be achieved by natural cooling. If the pressure is reduced by venting, it should be noted that the test sample should not be affected by the rapid decompression effect and the pressure should not drop below the laboratory pressure. The bias pressure should usually be maintained during this stage. 6.4.4 As soon as the cooling stage is over, the test sample should enter the recovery procedure. 7 Intermediate testing
The relevant specification may require electrical or mechanical testing, or both, during the test. If intermediate testing is required, the relevant specifications should specify the test items and the stage of the test at which these tests are to be performed. Intermediate testing should not cause any changes to the test conditions. During the test, it is not allowed to move the test samples out of the test chamber for testing before recovery. 8 Recovery
Once the test is completed, the test samples should be immediately restored under the standard atmospheric conditions for measurement and testing. The recovery time is 2h to 24h. 9 Final test
The test samples should be subject to visual inspection, dimensional and functional testing as specified in the relevant specifications. 10 Information to be provided by relevant specifications
When adopting this test, the relevant specifications should give the following details according to their adoption. The relevant specifications should provide the information required by the following items, especially the items marked with "*" must provide this information. a) Test severity level*
b) Initial test*
c) Special installation device
d) Bias
e) Intermediate test
f) Final test*
Chapter number
GB/T 2423. 40-1997
Appendix A
(Standard Appendix)
Steam table
Dry steam temperature 100℃ to 123℃
Saturation temperature,
Relative humidity, %RH
GB/T 2423. 401997
Table (continued)
Saturation temperature, ℃
Relative humidity, %RH
GB/T2423.40
Table (end)
Saturation temperature, C
Relative humidity. %RH
Appendix B
(Indicative Appendix)
Physical significance of the test
B1 Accelerated penetration of water vapor into the test sample is the most important physical factor in the unsaturated high-pressure steam test. The acceleration is due to the pressure difference between the water vapor partial pressure inside the non-airtight test sample and the test environment. B2 This test was first used to accelerate the corrosion of aluminum in integrated circuits and other plastic-encapsulated semiconductor devices. However, when considering the application of this test to other products, it is important to determine the failure mode and the degradation process and severity level associated with each failure mode. It should be understood that the failure mode of different electrical and electronic products may not be associated with the severity level given in Table 1. Appendix C
(Indicative Appendix)
Determination of Humidity
At present, a standard method for directly measuring humidity in a high temperature and high pressure zone above 100°C in a water vapor environment has not been established. c1
Therefore, the determination of humidity in this area has to be based on a theoretical evaluation of the measured value, and a method must be used to keep the deviation of the measured humidity from the theoretical value within the allowable range. 2 The following C3 classifies the various applicable methods. The description of each method is limited to its possible use as specified in C4. 02
In addition, the correctness of each method is based on the following assumptions, that is, in the test working space, other gases and air emitted from the humidification water and the test sample can be ignored, and the humidity level is not affected by the presence of these gases, that is, the working space of the test chamber is full of water vapor.
GB/T 2423.40-1997
Note: In addition to water vapor, there are trace gases emitted by the test samples and materials in the test chamber, which may affect the test results. See Appendix D. C3 Classification of humidity measurement methods
a) Temperature method
The temperatures of unsaturated water vapor and saturated water vapor in the working space are directly measured by sensors, and the relative humidity at these temperatures is found in the table in Appendix A.
The temperature of saturated water vapor is the temperature of the humidification water, or the temperature of water vapor measured directly above the humidification water. b) Wet-dry bulb method
Install a wet-dry bulb thermometer in the working space of the test chamber to determine the wet-bulb temperature difference. In fact, the relative humidity can be determined in the same way as in C3a).
c) Dew point meter method
A dew point meter with a mirror is installed in the working space, and the mirror temperature is measured at the beginning of condensation; the dry steam temperature in the working space is directly measured by a thermometer, and the relative humidity of the working space is determined by the same method as C3a). The common point of the three methods specified in C3a), C3b) and C3c) is that the temperature is measured first and then the relative humidity is determined based on the steam table. The above methods are all indirect methods for measuring the relative humidity of the working space. It must be noted that the measurement results will be affected by air and other gases (see C2).
C4 Application of various hygrometric methods
a) Temperature method (see C3a))
This method meets the definition of humidity in this test environment and is the most reasonable hygrometric method. It is used to verify the performance of the test equipment and to monitor the conditions during the test.
b) Dry-wet bulb method (see C3b))
This method is used to monitor the test conditions during the test. c) Dew point method (see C3c)
This method can be used to confirm the performance of the test equipment and monitor the conditions during the test, but it is difficult to use modern technology in practical application.
Appendix D
(Informative Appendix)
Test apparatus and treatment
D1 Types of test apparatus
Two types of apparatus are usually used:
a) Single container type (see Figure D1)
The humidification water tank and the working space are both in one container, and the working space is surrounded by several walls and separated from the water tank. The water vapor flow is usually forced by a fan installed in the test chamber. b) Double container type (see Figure D2)
This device consists of two pressure vessels, one of which is used as the working space and the other contains the humidification water. The water vapor pressure difference between the two containers creates a convective flow of steam. In this type, fans can be used to promote and/or assist the humidification flow. In both types of devices, the air velocity should be kept below 0.5 m/s, close to the wind speed of natural convection. Since the test method involves overpressure inside the test chamber, it is important to follow the equipment operating procedures. D2 Selection of materials
In order to minimize the degradation effects and released pollutants caused by corrosion and other mechanisms under the combined conditions of temperature and humidity specified in this test, care must be taken to select the materials used in the test chamber. Suitable materials include: stainless steel, glass, ceramics and other corrosion-resistant materials. D3 Bias
GB/T2423.40—1997
Bias is defined as the voltage applied for the purpose of the test to enhance the effect of humidity. Bias is not necessarily related to the normal function of the test sample. If required, it should be applied to the test sample during the test in accordance with the provisions of the relevant specifications. The bias should be applied according to the following guidelines, which are given in order of importance: a) The temperature at the specified position on the surface of the test sample should be 2°C lower than the nominal temperature of the working space. b) Special care must be taken in selecting a bias that will both enhance hydrolysis and limit self-heating of the test specimen, as this will affect the penetration and/or absorption of condensed gases. Where continued application of the bias will produce significant self-heating, it is recommended that the bias be applied continuously, and unless otherwise specified, the bias should be stopped for 3 h and then applied for 1 h. The sequence of bias application should begin with the bias being stopped. c) Precautions should be taken to limit the energy dissipation caused by the error condition. NOTE: Biasing the test error condition under constant humidity conditions enhances the effect of induced moisture. On the other hand, bias-induced power dissipation may produce localized heating and a decrease in relative humidity at critical locations, which may have an effect contrary to the purpose of the test. D4
Cleaning the test chamber and all internal fixtures (specimen racks, etc.) is essential. The test chamber and internal fixtures may be cleaned with a diluted laboratory detergent and a soft brush, followed by a rinse with distilled or deionized water. It is recommended that the chamber be cleaned before each test. After each test, all water in the steam generating vessel and/or test chamber shall be removed. It is recommended to use gloves and masks to prevent contamination of cleaned parts and equipment, and it is recommended to use the equipment in a reasonably clean area. Unless otherwise specified, the test samples shall be tested in accordance with normal procedures under standard "conditions". Testing of samples that have been specially cleaned before testing may not show those effects that occur in use. D5 Overall structure of several typical test devicessy
Figure D1 Single container type
In Figures D1 and D2:
PV—a pressure vessel (test chamber and steam generator);390
Figure D2 Double container type
WS-—working space,
GB/T 2423. 40—1997
PV,—-—pressure vessel used as the working space of the test chamber); PV2-——pressure vessel used as the humidifying water tank (steam generator): WA——water for humidification;
IG——pressure gauge;
SV----safety valve;
exhaust valve;
S.—temperature sensor for wet gas;
S ---
Temperature sensor for humidifying water;
——Fan:
——Wet steam heater;
HW--—Heater for humidifying water.40—1997
Bias is defined as the voltage applied for the purpose of the test to intensify the effect of humidity. The bias may not necessarily be consistent with the normal function of the test specimen. If required, the bias shall be applied to the test specimen during the test in accordance with the provisions of the relevant specification. The bias shall be applied in accordance with the following guidelines, which are given in order of importance: a) The temperature at the specified location on the test specimen surface should be 2°C lower than the nominal temperature of the working space. b) Special care must be taken in selecting a bias that will both enhance hydrolysis and limit self-heating of the test specimen, as this will affect the penetration and/or absorption of condensate. Where continuous application of the bias will produce significant self-heating, it is recommended that the bias be applied continuously. Unless otherwise specified, the bias should be stopped for 3 hours and then applied for 1 hour. The sequence of bias application should start with the cessation of bias. c) Precautions should be taken to limit the energy dissipation caused by the error condition. NOTE: Biasing the test error condition under constant humidity conditions intensifies the effect of induced moisture. On the other hand, bias voltage causes power dissipation, which causes local heating and leads to a decrease in relative humidity at critical locations, which may produce an effect contrary to the purpose of the test. D4
It is essential to clean the test chamber and all the mounting tools inside it (sample rack, etc.). You can use a diluted laboratory detergent to clean the test chamber and internal mounting tools with a soft brush, and then rinse with distilled or deionized water. It is recommended to clean the test chamber before each test. After each test, all accumulated water in the steam generating container and (or) test chamber should be removed. It is recommended to use gloves and masks to prevent contamination of cleaned parts and equipment, and it is recommended to use the equipment in a fairly clean area. Unless otherwise specified, the test samples should be tested in accordance with normal procedures under standard "conditions". Testing samples that have been specially cleaned before testing may not show those effects that occur in use. D5 Overall structure of several typical test devicessy
Figure D1 Single container type
In Figures D1 and D2:
PV—a pressure vessel (test chamber and steam generator);390
Figure D2 Double container type
WS-—working space,
GB/T 2423. 40—1997
PV,—-—pressure vessel used as the working space of the test chamber); PV2-——pressure vessel used as the humidifying water tank (steam generator): WA——water for humidification;
IG——pressure gauge;
SV----safety valve;
exhaust valve;
S.—temperature sensor for wet gas;
S ---
Temperature sensor for humidifying water;
——Fan:
——Wet steam heater;
HW--—Heater for humidifying water.40—1997bZxz.net
Bias is defined as the voltage applied for the purpose of the test to intensify the effect of humidity. The bias may not necessarily be consistent with the normal function of the test specimen. If required, the bias shall be applied to the test specimen during the test in accordance with the provisions of the relevant specification. The bias shall be applied in accordance with the following guidelines, which are given in order of importance: a) The temperature at the specified location on the test specimen surface should be 2°C lower than the nominal temperature of the working space. b) Special care must be taken in selecting a bias that will both enhance hydrolysis and limit self-heating of the test specimen, as this will affect the penetration and/or absorption of condensate. Where continuous application of the bias will produce significant self-heating, it is recommended that the bias be applied continuously. Unless otherwise specified, the bias should be stopped for 3 hours and then applied for 1 hour. The sequence of bias application should start with the cessation of bias. c) Precautions should be taken to limit the energy dissipation caused by the error condition. NOTE: Biasing the test error condition under constant humidity conditions intensifies the effect of induced moisture. On the other hand, bias voltage causes power dissipation, which causes local heating and leads to a decrease in relative humidity at critical locations, which may produce an effect contrary to the purpose of the test. D4
It is essential to clean the test chamber and all the mounting tools inside it (sample rack, etc.). You can use a diluted laboratory detergent to clean the test chamber and internal mounting tools with a soft brush, and then rinse with distilled or deionized water. It is recommended to clean the test chamber before each test. After each test, all accumulated water in the steam generating container and (or) test chamber should be removed. It is recommended to use gloves and masks to prevent contamination of cleaned parts and equipment, and it is recommended to use the equipment in a fairly clean area. Unless otherwise specified, the test samples should be tested in accordance with normal procedures under standard "conditions". Testing samples that have been specially cleaned before testing may not show those effects that occur in use. D5 Overall structure of several typical test devicessy
Figure D1 Single container type
In Figures D1 and D2:
PV—a pressure vessel (test chamber and steam generator);390
Figure D2 Double container type
WS-—working space,
GB/T 2423. 40—1997
PV,—-—pressure vessel used as the working space of the test chamber); PV2-——pressure vessel used as the humidifying water tank (steam generator): WA——water for humidification;
IG——pressure gauge;
SV----safety valve;
exhaust valve;
S.—temperature sensor for wet gas;
S ---
Temperature sensor for humidifying water;
——Fan:
——Wet steam heater;
HW--—Heater for humidifying water.
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