Constant temperature and humidity test - Reliability Test

Date：2021-11-04 17:22:00 Views：2244

Constant temperature and humidity test is an environmental reliability test for products. That is, simulate the temperature and humidity environment of product storage and operation, and check whether the impact of the product after a period of time in this environment is within the acceptable range. Constant temperature and humidity are generally high temperature and high humidity. With the increasingly strict requirements for quality control, the demand for constant temperature and humidity environment is increasing, and the application field is becoming wider and wider. Constant temperature and humidity test can simulate high temperature, low temperature and damp heat environment, and carry out temperature and humidity test under specific environment. Constant temperature and humidity test can ensure that the tested products are under the same temperature and humidity environmental conditions.

Application scope of constant temperature and humidity test

Constant temperature and humidity test is used to test the performance of materials in various environments and test the heat, cold, dry and moisture resistance of various materials. It is suitable for testing the quality of electronics, electrical appliances, mobile phones, communications, instruments, vehicles, plastic products, metals, food, chemistry, building materials, medical treatment, aerospace and other products.

Purpose of constant temperature and humidity test

In the natural environment, temperature and humidity are two inseparable natural factors. Different regions have different temperature and humidity effects due to different geographical locations. For example, the northern region of China has a low temperature and low humidity environment in winter, while the southern region has a high temperature and high humidity environment in summer. Constant temperature and humidity test is used to confirm the adaptability of products to storage, transportation and use under temperature and humidity climate and environmental conditions. The severity of the test depends on high / low temperature, humidity and exposure duration.

Constant temperature and humidity test method

Constant temperature and humidity test is to use the equipment temperature and humidity box with heating, refrigeration and humidification functions. Before the test, check whether the relevant functions and performance of the product are normal and take photos, then place the product in the temperature and humidity box, start up and set the temperature, humidity and test duration of the temperature and humidity box. For example, 70 ° C, 95% humidity, test for 168 hours. After setting, let the temperature and humidity box work and the test begins. After reaching the set end time, take out the product and check again whether there are any changes in the relevant functions and performance of the product before the test, so as to judge whether the product meets the test requirements. Sometimes it is necessary to take out the product for inspection during reliability testing to understand the state of the product at different test times. If the impact on the product has exceeded the acceptable range before the preset test completion time, the test can be terminated in advance to find a solution to the problem, and retest after the product is improved.

Constant temperature and humidity test has no fixed standard for specific test temperature, humidity and test duration. The client needs to confirm the test conditions according to its own situation or customer requirements. When determining the test conditions, refer to the actual storage environment, transportation environment and use environment of the product. The usual temperature is 40-80 ° C, the humidity is 65% - 95%, and the duration varies from more than ten hours to hundreds of hours. There is no fixed judgment standard for constant temperature and humidity test, which needs to be confirmed by the client according to its own situation or customer requirements. Generally, it is aimed at the degree to which the appearance, function and performance of the product are affected after the test.

Constant temperature and humidity test is divided into constant temperature and humidity storage and constant temperature and humidity operation. Constant temperature and humidity storage is tested when the product is not working. Constant temperature and humidity operation is a test for electronic products when the product is powered on.

Reliability constant temperature and humidity test capability

GB / T 2423.3, IEC 60068-2-78 test capability

1. Temperature range: - 70 ℃ - 150 ℃, humidity range: (20% ~ 98%) RH, volume ≤ 0.08m;

2. Temperature range: - 40 ℃ - 150 ℃, humidity range: (20% ~ 98%) RH, volume ≤ 1m.

Treatment of common faults in constant temperature and humidity test

In the constant temperature and humidity damp heat test, the actual humidity will reach 100%, or the actual humidity is very different from the target humidity, and the value is much lower. The former phenomenon: it may be caused by the drying of the gauze on the wet ball sensor, so it is necessary to check whether there is water shortage in the water tank of the wet ball sensor, and the water level in the water tank is automatically controlled by a water level controller, Check whether the water supply system of the water level controller supplies water normally and whether the water level controller works normally. Another possibility is that the wet ball gauze will harden due to long service time or the purity of water supply quality, so that the gauze cannot absorb water and dry. The above phenomenon can be eliminated as long as the gauze is replaced or cleaned. The latter phenomenon is mainly that the humidification system does not work. Check the water supply system of the humidification system, whether there is a certain amount of water in the water supply system, whether the water level control controlling the water level of the humidification boiler is normal, and whether the water level in the humidification boiler is normal. If all the above are normal, check the electrical control system, which should be overhauled by professional maintenance personnel.

When the constant temperature and humidity test equipment breaks down suddenly during the test operation, the corresponding fault display prompt and audible alarm prompt appear on the control instrument. The operator can quickly check the type of fault according to the chapter on troubleshooting in the operation and use of the equipment, and then ask professional personnel to quickly eliminate the fault, so as to ensure the normal operation of the test. There will be other phenomena in the use of other environmental test equipment, which should be analyzed and eliminated.

Reliability constant temperature and humidity test standard

GB / T 2423.3, IEC 60068-2-78 environmental testing Part 2: Test methods Test cab: constant damp heat test;

GB / T 2423.50 and IEC 60068-2-67 environmental testing Part 2: Test methods Test Cy: constant damp heat is mainly used for accelerated testing of components.

Environmental executive standards for electrical and electronic products:

GB / T 2423.3-2016 environmental test: constant damp heat test

GB / T 2423.3-2006 environmental testing of electric and electronic products Part 2: Test methods Test cab: constant damp heat test

GB / T 2423.4-2008 environmental testing for electric and electronic products - Part 2: test method test DB: alternating damp heat (12h + 12h cycle)

GB / T 2423.9-2001 environmental testing of electric and electronic products Part 2: Test methods Test CB: constant damp heat for equipment

GB / T 15969.2-2008 programmable controllers Part 2: equipment requirements and testing

GJB 150.9-2009 environmental test methods for military equipment damp heat test

Gjb548a-1996 gjb548b-2005 test methods and procedures for microelectronic devices

GJB360A-1996 test methods for electronic and electrical components, etc.