In the process of product development and quality control, high and low temperature alternating damp heat testing (usually referred to as damp heat alternating testing) is an important environmental test. This type of test is mainly used to evaluate the performance and durability of products in environments with alternating high temperature, low temperature, and humidity changes. Especially for electronic products, automotive components, home appliances, and other devices that require operation under extreme environmental conditions, this test is particularly critical. This article will provide a detailed introduction to the definition, testing principles, application scope, and importance of high and low temperature alternating humidity testing.

1 Definition

High and low temperature alternating humidity test refers to exposing the test sample to an environment with alternating temperature and humidity changes, simulating the extreme weather conditions that the product may encounter in actual use. Specifically, this test evaluates the durability, stability, and reliability of the product in this environment by continuously alternating between high and low temperatures and maintaining a certain level of humidity at each stage.

The key purpose of this test is to simulate the impact of different climate changes on the product. For example, how electronic devices perform in extreme high or low temperature, high or low humidity environments, and whether they will experience malfunctions, damage, or performance degradation.

2 Working principle

The principle of high and low temperature alternating humidity testing is to set temperature and humidity change programs in the testing box, allowing the equipment to repeatedly experience different temperature and humidity changes under the set environmental conditions. Generally speaking, the testing cycle includes the following parts:

• High temperature stage: Expose the test sample to a high temperature environment (such as 60 ℃, 70 ℃ or higher) and maintain a certain humidity (such as 80% RH to 95% RH).

• Low temperature stage: Transfer the sample to a low temperature environment (such as -20 ℃ to -40 ℃), with humidity typically maintained at a lower level (such as 30% RH to 60% RH).

• Alternating change stage: a cyclic change between high and low temperatures, typically lasting several hours or days, to simulate the temperature and humidity fluctuations that equipment may encounter in actual use.

• Stability assessment: By repeatedly alternating high and low temperatures and humidity changes, evaluate the stability of the equipment, especially whether the internal components of the equipment can withstand such environmental changes without failure.

3 Parameters

High and low temperature alternating humidity testing requires precise control of multiple environmental parameters to ensure the accuracy and reliability of the testing. Here are a few key parameters:

• Temperature range: The typical testing temperature range is set between -40 ℃ and+100 ℃, and in extreme cases, it can reach -70 ℃ to+150 ℃. This temperature range can simulate various environmental conditions, from the cold Arctic to the hot desert.

• Humidity range: The humidity range is usually set between 20% RH and 95% RH. Changes in humidity can affect the electrical, mechanical, and corrosive properties of products.

• Testing cycle: The testing cycle is set according to the actual application environment of the product, and the common cycle is 24 hours or 48 hours. The longer the testing time, the more comprehensive the durability and stability evaluation of the product.

• Cycle times: In order to simulate long-term use of the device, multiple cycle tests are usually conducted. For example, after 10 or 20 cycles of alternating high and low temperature and humidity, check whether the product has aged, decreased performance, or other problems.

4 Application fields 

High and low temperature alternating humidity testing is widely used in multiple fields, especially for products that need to work or be stored in extreme environments. Here are some main application areas:

• Electronic products: including mobile phones, televisions, computers, household appliances, etc. These devices are susceptible to temperature and humidity changes during prolonged use. High and low temperature alternating humidity testing can evaluate their performance and reliability in different environments.

• Automotive industry: Automotive components such as batteries, electronic control systems, sensors, etc. need to work under extreme conditions such as high temperature, low temperature, and high humidity. Testing can help ensure that these components can still operate efficiently in extreme weather conditions.

• Aerospace: Aerospace vehicles, satellites, and other space equipment need to withstand environmental influences such as high temperature, low temperature, and high humidity to ensure their stable operation during long-term flights or space missions.

• Medical equipment: During transportation and storage, it is necessary to ensure that the equipment is not affected by high temperature, low temperature, and humidity. By conducting high and low temperature humidity tests, it is possible to ensure the stable performance of these devices in different environments.

• Batteries and energy storage devices: With the development of new energy technologies, the application of batteries and energy storage devices is becoming increasingly widespread. Especially in electric vehicles and energy storage systems, batteries need to operate stably under high temperature, low temperature, and humidity conditions to ensure safety and reliability.

• Protective equipment: such as personal protective equipment, outdoor exploration equipment, etc. The effectiveness of these products in extreme environments needs to be verified through high and low temperature humidity tests.