Electronic devices that are used in water transport system are called as marine electronics. With the advancement in technology, mechanical boards are replaced by electronic circuits that give quick and precise observations. Devices like chartplotter, autopilot, SONAR, marine RADAR, satellite television etc. are designed in such a manner so that they remain unaffected by salt water and humidity.
How humidity affects the electronic circuits?
It does not directly impact the functioning of the circuits by affecting the components. Instead, it attacks different components, differently. Modern circuits have multi-layered printed circuit boards. Adhesives are used to join the multi layers back to back. Due to excessive exposure to the humid environment, the adhesion starts losing and external factors start affecting the connecting tracks of the board. It is very important to take countermeasures to control the adhesion of PCBs.
Humidity accelerates corrosion. Due to the presence of salty water and temperature, the humidity level in the sea keeps on increasing. Up to 70% humidity is quite common. The electronic components have metal connectors and conductors. For the right functioning of the module, it is very important that they should not get corroded. If the surface of connectors or conductors is not apt, the phenomenon of ion migration won’t happen.
How to test the behaviour of circuits?
Humidity Chamber simulates the perfect marine environment in the closed lab. The device is equipped with heaters and a water reservoir that can produce humidity in the range of 65% to 95%. It has double glass door feature and glass wool insulation to avoid any heat loss. The double door feature allows the operator to check the behaviour in between the test without opening the door of the chamber. The temperature range that can be set is 20°C to 60°C. This is also called environment chamber as it creates a real working condition in the controlled environment.
The test procedure is very simple, the operator just has to set the predefined temperature and relative humidity. The test sample is kept on the sample shelf for the prescribed time as per the industrial requirements.
Due to high humidity inside the chamber, the components which are not designed for high humidity starts showing volatile behaviour. This involves high current leakage from components like capacitors and reduced gain. The pins of ICs may start getting short which is why microprocessors and microcontrollers may not give the desired output. Sometimes, the components like LCD and LEDs starts showing error. Instead of intended number, the LEDs might display 8 by turning on all the diodes inside. This all happens due to current leakage.
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