Electronic components are exposed to plenty of damaging environmental influences over the course of their life cycle. Just how well you can protect them from these effects, can be tested in environmental chambers under controlled conditions. It is easy for minor errors to occur during these tests, however, which can lead to incorrect results.
Extremely high/low temperatures, a quick change of temperature, UV radiation, salt spray, dust and acid rain - all of these elements have an impact on components. They can damage the components, which in turn leads to functional restrictions or a complete breakdown.
Just how resistant the components are, can be investigated in the environmental chamber. Fault analyses are also possible here. The scenarios range from climatic testing in the climate chamber, to corrosion testing in the salt spray chamber, to dust testing. Mechanical stresses are simulated on what is known as a shaker.
In the climate chamber, both intense cold (up to -40°C) and intense heat (up to 120 or even 180°C) are tested. High temperatures such as these are often tested by the automotive industry on components used in the engine compartment. The testing of extreme temperatures also often involves conditions with up to 98% relative humidity.
In climate chambers, components are exposed to temperatures ranging from -40 to 180°C. Even more wearing than the extreme heat or cold is, however, a quick change of temperature. (Image: MBtech)
Another type of temperature testing involves the change test. This involves changing the temperature several times within a brief period of time. The climate shock tests are an extreme form of this. Climate chambers comprising a hot and cold semi-chamber are used for this purpose. By pushing the test item through both chambers, it is possible to achieve temperature changes of over 100 Kelvin in just a matter of seconds.
The splash water test is another climate shock test. Here, the heated component is shocked with cold water. Due to the rapid drop in temperature, a vacuum is created in the component which draws the water in. The splash water test is thus not only a climate shock test, but also an extremely strict leak test.
The tests carried out in the climate chamber may be combined with functional testing of the component. Here, they are charged with operating voltage or low/high voltage during the tempering. Moving parts, such as electric motors for example, can also be actuated in the climate chamber in order to test their effectiveness under extreme climate conditions.
In the salt spray chamber, the resistance of electronic components to corrosion is tested by exposing them to alternating periods of salt spray and dryness over a period of several hours. Alternatively, they are exposed to a salt spray for a few hours until a salt crust forms. Finally, a function test is carried out to check the impact of the salt on the electronics of the component. In the salt spray chamber, condensation testing at 40 to 50°C and 100% relative humidity is also possible.
The dust tests are carried out in a similar fashion. With these tests, the components are exposed to a very fine, standardized dust before their operating efficiency is then tested. “Arizona Dust” is used for this purpose. This is an industrially manufactured dust with a specific grain size, which corresponds to the dust found in the Arizona desert. Dust tests tell us more about how impermeable the components are.
In order to test mechanical strength, the components are exposed to shakers of varying frequencies. These tests are used more to determine operating stability than environmental simulation. There are, however, also shakers which can be used in conjunction with a climate chamber. Meaning it is thus possible to combine a shaker test with a climate test.
For environmental simulation in the broader sense, IP protection testing is also carried out. Here, the impermeability of the components against water and dust is tested under the most varied of conditions.
All of the methods mentioned above are important for the testing of electric and electronic components. This applies both for control and power supply units, as well as moving components such as electric motors. Environmental chambers vary in size, from a testing volume of 0.35 to 16m3. In large chambers, entire containers of components can be tested.
In order to minimize or eliminate the risk of incorrect test results, various parameters need to be considered during the testing process. Errors can occur as early as calibration of the chamber. It is important to measure several points per area. Often, the temperature is not measured at enough points. If a chamber is tempered and the
defined temperature has been reached, this does not automatically mean that the entire test piece has also reached the temperature in question. Particularly with large components comprising various materials, there may be large temperature differences found in the component. In these cases, consideration needs to be given to where the specific testing temperature must be maintained in the component and in which areas this temperature may deviate.
If components have a very large mass, they often only reach low temperatures very slowly. In cases like these, the test item needs to be conditioned for longer before the actual test. During temperature testing, the speed at which the temperature changes plays an important role: The test item must be able to follow the change of temperature in the chamber. For example, if the temperature changes within the chamber by 100 Kelvin in 15 minutes, the test item must also adopt this temperature within the same period of time. Otherwise, the test results will be flawed.
When testing in the corrosion chamber, there may be too little or too much saline water sprayed, thus leading to incorrect results. The formation of drops on the test items, due to excessive amounts of spray, should be avoided. All nozzles in the chamber must spray the same quantity of solution at the same time. And this requires sufficient pressure and saline solution. Furthermore, the machine must be in perfect working condition. With the salt spray test, it must also be ensured that the saline solution is used one to two days after it has been gassed out. Storing the solution for a longer period can lead to the formation of algae. And this makes the saline unusable.
How the item is installed also plays an important role. An unsuitable arrangement of the test items in the chamber can lead to a collection of saline on the items or the dripping of saline onto any items below. This may then adversely affect the results. Once the tester is aware of the risks of incorrect test results, technical components and products can be exposed to the most varied of defined environmental influences.
In salt spray chambers, the corrosion resistance of the component can be tested, among other things.
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MBtech Group GmbH & Co. KGaA is a globally active engineering and consultancy service provider for the mobility sector. In Europe, we are one of the leading providers in the automotive, railway transportation and aerospace industries. MBtech supports manufacturers and suppliers along the entire product development process – from the design to series production. MBtech, with its headquarters in Sindelfingen, employs a workforce of approximately 3,300. Since 2012, the company has been part of the AKKA Technologies SE network, which is based in Paris.