Charcroft Electronics director, Roger Tall, explains why a component needs to be rated to deliver reliable operation under different harsh environments.
Harshness comes in many forms. A component may have to work in an application with very high/low temperatures or a combination of both. There may be high vibration/acceleration or humidity. The part may even be submerged.
Other factors which can affect reliability are electromagnetic interference (EMI), plus contaminants or corrosive chemicals including salt-spray and sulphur. Distance can play a part too. It is easy to replace a failed component in an industrial application but difficult to access a sub-sea communications amplifier. It is extremely difficult or impossible to replace a component which has failed in a satellite or deep space probe.
Each one of these issues is important and the distributor must have the expertise and resources to support customers to source components for every harsh environment, from the most basic to the highest level of custom testing.
Moisture and temperature
The Ingress Protection (IP) standard defines how a component can withstand the ingress of solid particles or liquids. For example, IP67 means the component is dust-tight and can be immersed in water up to a depth of 1 m.
Standard temperature ranges are from 0 to 70°C for commercial, through higher industrial/automotive temperatures to military at -55 to 125°C. Some extreme applications are rated to 300°C.
Acceleration and vibration
As an example of acceleration, a roller coaster can reach 6.3g, while 10g can be experienced in a jet fighter. Vibration combines g-force with Hertz (Hz), showing the frequency of vibration. For example, a datasheet could state a component can withstand vibration of between 50Hz to 500Hz.
Custom manufacture and test
For harsh environments, manufacturers offer specific component screening to known standards such as automotive, military or space. Many now also offer a choice of screening options which allow selective screening. There is also the option to develop a completely customised component to meet the most demanding applications.
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