Pure air at Lake Plansee

In the 400 sqm cleanroom CleanCell4.0® of ISO cleanroom class 6, components for semiconductor manufacturing are produced.

Since no suspension was possible on the on-site ceiling, the cleanroom was self-supporting constructed from a framework made of aluminum profiles.

Special cleanroom furniture and roller shutters with contactless operation ensure safe process flows.

Material sluices and doors feature an intelligent lighting concept that takes into account the flushing times and indicates when a door may be opened.

The Plansee Group, headquartered in Reutte, Austria, specializes in the powder metallurgical processing of high-tech metals molybdenum and tungsten. Continuous investments in the development of new products and process improvements secure the location and employment of around 2,400 employees. Now, a nearly 400 sqm cleanroom of ISO class 6 has been put into operation, meeting the high safety standards of the semiconductor industry.

Clean Metal Processing

With over 14,000 employees worldwide at 50 production sites, the private company Plansee Group achieved a turnover of 1.5 billion euros in the 2018/2019 fiscal year and is among the world market leaders in the powder metallurgical processing of tungsten and molybdenum. In Austria, where the company originated in 1921 as Metallwerk Plansee, the headquarters and the largest production site are located.

While one might initially think of a metalworking operation with chips, dust, and dirt, the opposite is true at Plansee. The company focuses on high-melting metals like tungsten and molybdenum, which possess special properties such as high resistance and good conductivity. The metals are first processed into high-purity powder and then pressed, sintered, and mechanically machined. The semi-finished products and components are needed in the electronics industry, semiconductor manufacturing, and medical technology. Absolute cleanliness in manufacturing is therefore of utmost priority.

For the current production of components for semiconductor manufacturing, the process even takes place within an ISO class 6 cleanroom. In the modern cleanroom, CleanCell4.0®, installed in 2019, parts and components made of molybdenum and other materials are assembled, which can be impaired by even the smallest contaminants. Contamination of the sensitive components by particles must be absolutely excluded. Over half of the 400 sqm production area therefore meets the strict cleanliness requirements of ISO class 6 cleanroom standards.

Cleanroom Technology with Energy-Efficient Recirculation

Using laminar flow units integrated into the ceiling, equipped with ULPA15 high-performance filters, pure air is supplied into the cleanroom. The particle-free air streams displace airborne particles downward and are then extracted from the cleanroom into the recirculation system. This air exchange process is carried out up to 60 times per hour. The recirculation and exhaust air are managed within the walls of the cleanroom. The already cooled and filtered air is circulated in a loop, contributing to very efficient operation of the cleanroom. Additionally, the air management within the walls ensures optimal space utilization. Plansee opted for a cleanroom system from Schilling Engineering. Mario Kuisle, project engineer at Plansee, explains the advantages of the system:

"The recirculation system of CleanCell4.0 convinced us from the start. We can save high energy costs in the long term. It was also important that the air management within the walls ensures optimal space utilization. The cleanroom was precisely adapted to our conditions."

The special conditions of the on-site location required a cleanroom tailored to customer needs in multiple ways. The project engineer recalls some challenges faced by the planning company:

"The existing ceiling of the Plansee hall is, among other things, not suitable for suspension due to the expected snow loads. The cleanroom ceiling was therefore constructed with a self-supporting framework made of aluminum profiles. The ceiling is walkable and has designated sturdy walkways. A major advantage of this construction is that the cleanroom was built without supports or columns."

Modular Design

Another challenge was the desired height of the cleanroom, designed with an interior height of four meters, higher than typical cleanrooms. The height, necessary for the installation of measurement machines, was achieved with removable wall elements. The ceiling, equipped with 67 clean air units, is also modular and can be reconfigured flexibly. The modular system of the CleanCell4.0® cleanroom allows for flexible planning of future utilization, as Mario Kuisle explains:

"The modular design of the cleanroom system greatly assisted us in our investment decision. We wanted the ability to quickly and flexibly adapt the cleanroom to other production processes. Currently, we are producing for semiconductor manufacturing and have integrated the production machines into the cleanroom walls accordingly. Thanks to the modular wall and ceiling elements, we can reconfigure for different occupancy concepts in the future."

Intelligent Control

Homogeneously integrated into the aluminum strips of the ceiling are dimmable LED light strips, providing uniform illumination of 1000 Lux with minimal shadows and contributing to energy savings. Doors and material sluices are also LED-illuminated and display different colors to indicate whether a door can be opened or must remain closed for pressure equalization and active flushing. An intelligent control system, CR-Control®, manages and monitors individual filter units, room data relevant to production such as temperature and humidity, and the climate technology. The highly precise climate control maintains the room temperature with a deviation of only +/- 1°C and features an extremely energy-efficient air treatment system.

Mario Kuisle is very satisfied with the first months of operation of the cleanroom: "The cleanroom runs flawlessly. The technology is very complex but perfectly coordinated and well thought out. Energy optimization was very important to us. By using a heat pump, we can save significant auxiliary costs in the long term. We also have the option to program a night setback. The quiet filters and good lighting are also very positive, making daily work in the cleanroom easier."