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Extend lifetime of automotive electronic components

Posted: 18 Aug 2014     Print Version  Bookmark and Share

Keywords:electronic components  pressure differential  inverter  venting solution  PTFE 

There are several proven methods of testing vents to determine their ability to withstand extreme temperatures (ISO 16750-4). In the temperature resistance test, the vent is exposed to a maximum temperature of up to 150 C for 2,000 hours, or a minimum of -40 C for 1,000 hours. In the ice dunk test, the vent is placed in a sealed housing and heated at a temperature between 80 and 120 C in an oven for 40 to 60 minutes. The housing is then rapidly cooled to between 0 and 4 C by placing it in iced water containing 5 % sodium chloride, a solution designed to simulate the salt water that electronic housings are likely to come into contact with in the winter. This procedure is repeated ten to twenty times, with venting properties measured before and after the test.

Different applications require individual membrane solutions
Choosing the right membrane to suit each particular application and its requirements is vitally important. In order to cover all application areas, membrane manufacturers offer adhesive and weldable vents as well as moulded parts. Adhesive Vents are coated with a high-performance adhesive that adheres strongly to various kinds of metal and plastic. They are supplied on a lightly adhesive backing for manual or automated installation. The adhesive is long-lasting and capable of withstanding harsh conditions. However, as the adhesive has only limited resistance to extremely high temperatures and strong chemicals, these vents are less suitable for under-the-hood use. They are designed to be used with vehicle components that are less likely to come into contact with liquid chemicals, such as automotive lamps.

Weldable vents can be made of different material combinations and in different sizes to suit the specific requirements of the intended application. They are mainly used in applications with plastic housings, and are attached by the customer using ultrasonic welding. At the weld seam a small section of the housing material melts and flows into the porous structure of the membrane, thereby guaranteeing that the join is sealed and solid. Since the melting point of PTFE is much higher than the welding temperature, this process does not compromise the membrane. These vents provide a long-lasting, reliable solution even when exposed to high temperatures and strong chemicals. However, the welding process is very complex and requires specialised welding tools and qualified experts to complete the process. In addition, protective walls have to be integrated into the housing design to protect the vent from steam jets and mechanical loads, which can be an expensive and complicated process.

Moulded parts represent a solution that is able to withstand the most challenging environmental conditions as well as being easy to integrate. This can be achieved by adding a step to the manufacturing process. For example, insert moulding is a process that integrates the membrane directly as part of the plastic injection moulding process. The moulded parts can then be attached by simply snapping them into place in an opening in the housing. This protects the membrane from mechanical loads without the need to integrate expensive and complex protective walls into the housing. Furthermore, integrating the vent does not call for special machines or qualified experts: the vent is simply fitted in the housing via the plug & play method.

Customised venting solution for different applications
The rising number of electronic components in cars increases the need for reliable protection measurements against environmental impacts. Especially high-performance electronics and batteries in electric and hybrid vehicles present an enormous challenge for automotive manufacturers and suppliers. The most effective solutions are automotive vents with membranes that protect sensitive electronics against contamination and fluids and provide air exchange and pressure equalisation at the same time. Since every application has specific requirements, it is important to collaborate with the membrane manufacturer at the earliest stage in the design process. This ensures that the selected technology undergoes the necessary testing, meets the correct requirements and provides the best venting solution.

About the author
Robert Chamberlain is Sales Manager Automotive Electronics, W. L. Gore & Associates, Ltd.

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