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To meet an increasing demand for products, Melexis is setting up a temporary clean room at the site near its headquarters in Ypres for testing electronics. The client's requirements? Building the optimal environment for testing electronics, of course. But above all create a safe, healthy and comfortable workplace for the employees.
Melexis is a publicly traded global player in the semiconductor industry, designing, developing and testing microelectronic semiconductor solutions. These microelectronics are used in the automotive, transportation, home automation, industrial and medical sectors, among others. The decision was made to house a temporary clean room with adjacent lab space in a former storage warehouse. The box-in-box design of the cleanroom allows the required air quality to be achieved in a simple manner. As a result, the air purification system, which takes up a lot of space, can also be largely concealed in the void between the two volumes.
Five to 10 people will be working in the building at a time. The clean room provides space for 42 setups of test equipment to test and program computer chips in various conditions. Those test setups develop a lot of heat released into the space.
On the other hand, the chips are also temporarily exposed to very cold temperatures. This is obtained by using liquid nitrogen. The nitrogen evaporates, extracts a lot of heat locally in the process, and expands enormously; 1 liter of liquid nitrogen becomes 700 liters of nitrogen gas. The gas then enters the clean room, lowering the oxygen content in the ambient air. This poses a risk to employees on site. Therefore, oxygen levels must be constantly monitored and some 8 volumes per hour of fresh air is blown into the cleanroom.
Cold nitrogen gas is heavier than air and will accumulate at the bottom of the cleanroom. Consequently, its extraction is done at the bottom of the room. To remove the enormous amount of heat, some 70 volumes of air per hour must be recirculated and cooled. The contaminated air from the clean room is simultaneously purified by means of filter boxes with HEPA filters.
In addition, proper moisture management is also important, this to avoid static electricity. The balance is kept optimal by adiabatic humidification, which is the most energy-friendly solution in this case.
The challenge for working comfort is to ensure a comfortable temperature in the corridors between the equipment - where employees are working - while avoiding unpleasant drafts by controlling air velocity.
70 air changes per hour is a very large amount of air. As a standard, 5 to 8 air changes are usually sufficient to air condition industrial spaces. In order to distribute this ventilation air as evenly as possible, custom fabric ducts are used.
Each type of test equipment introduces heat into the room differently. On the one hand, heat is given off by radiation, and on the other by forced convection via fans. The impact of this on the local air temperature and air flows is a complex issue. To gain an insight into this, CFD simulations were carried out in close cooperation with the manufacturer of the textile ducts. Using these dynamic simulations, the ideal position of the textile ducts in relation to the equipment could be investigated. After some optimizations, it was obtained that the cooled blown-in air stops the largest heat flows. At the same time, it is partially mixed at the level of the corridors between the equipment, resulting in a pleasant air temperature and velocity.
In the context of business continuity, Melexis chooses to set up a clean room with lab space in a temporary arrangement. Even in this case, it is important to use energy-efficient techniques to create a high-quality, healthy, safe and pleasant working environment.
Would you also like to call on our years of expertise with labs and cleanrooms?
Neem contact op met onze expert Wim Boone: wim.boone@ingenium.be of bel 050 40 45 30
