Why do we do damp heat test? Importance of alternating damp heat test

Date：2022-02-18 16:20:00Views：1744

Alternating damp heat test includes constant damp heat test and alternating damp heat test. The test simulates the environment of tropical rain forest to determine the adaptability of products and materials to use and storage when temperature changes and product surface condensation. It is commonly used in life test, evaluation test and comprehensive test. The technical indexes include: temperature, relative humidity, conversion time and alternating times.

Purpose of alternating damp heat test

High and low temperature alternating damp heat test is a necessary test item in aviation, automobile, household appliances, scientific research and other fields. It is used to test and determine the parameters and performance of electrical, electronic and other products and materials after high temperature, low temperature, alternating damp heat or constant test.

Importance of alternating damp heat test

In the reliability experiment, humidity is generally applied to the high temperature section. The comprehensive effect of high temperature and later low temperature should be considered while analyzing the fault mechanism induced by humidity. In terms of mechanical properties, moisture invades the surface of the material and decomposes, molds and deforms the material. If it works with high temperature at the same time, the moisture absorption of insulating materials will accelerate, and even adsorption, diffusion and absorption phenomena and respiration will occur, resulting in swelling, deformation, blistering and coarsening of the material surface, as well as increased friction and even jamming of moving parts; In the electrical aspect, due to humidity, frost is easy to occur when the temperature changes, resulting in electrical short circuit.

The surface deterioration of organic materials caused by humidity will also lead to the deterioration of electrical properties. At the same time, humidity at high temperature will also lead to the contact pollution of contact parts and poor contact. The main failure modes induced by humidity are: 1. Electrical short circuit; 2. The movable components are stuck; 3. Circuit board corrosion; 4. Surface damage; 5. The performance of insulating materials is reduced.

In addition, there is a certain corresponding relationship between other types of environmental stress and the types of faults that can be excited. In the product reliability test, the application of comprehensive stress can more effectively add the defects of the product than the application of single stress, because the influence of one environmental factor on the product will be strengthened and lead to failure with the induction of another environmental factor. This requires that when RET is carried out for specific products, the mechanism of various types of stresses on various types of defects of products must be deeply analyzed to determine the comprehensive mode of various stresses in ret.

Method standard

GB2423. 22 environmental testing Part 2: Test methods Test N: temperature change

Gb2423.34 environmental testing of electric and electronic products Part 2: Test methods Test Z / AD: Combined temperature / Humidity Cycle Test

GJBl50. 9 environmental test methods for military equipment damp heat test