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Capacitor Film Production
Experience & innovations for ultra-thin high-class applications
Introduction
A capacitor consists of two electrodes or plates, each of which stores an opposite charge. These two plates are conductive and are separated by an insulator or dielectric. The charge is stored at the surface of the plates, at the boundary with the dielectric. Because each plate stores an equal but opposite charge, the total charge in the capacitor is always zero.
Polypropylene (PP) and polyethylene terephthalate (PET) are the preferred choice of raw material for film capacitors. The dielectric strength of both is increased considerably by biaxial orientation, inducing a more perfect crystalline formation.
The biaxially stretched film is metallized, slitted and coiled. One important factor for the size of a capacitor is the film thickness. The quality of the capacitor is defined by: |  | Pureness of the film
| | | A perfect film profile
| | | A consistent metallizing quality |
Generally two types of capacitor-designs are state-of-the-art:
PP Capacitors | | high current
| | | thickness range: 3 - 15 µm |
PET Capacitors
| | high heat resistant, up to 150°C
| | | thickness range: 0.5 - 6 µm |
Capacitor film must be extremely clean. Therefore the production of capacitor film demands: | | Ultra-pure raw material
| | | A special process, which makes the usually needed addition of anti-blocking agents negligible (BOPP)
| | | Special line design, suitable for clean room conditions |
Brückner`s vast experience | | First capacitor film line sold 1970
| | | Up to date 27 Brückner capacitor lines in operation
| | | More capacitor lines sold than any other line supplier
| | | Expertise in both, sequential and simultaneous stretching process |
Highlight: Capacitor films down to 0.5 µm | | DuPont Teijin Films, Luxembourg, produces films in a thickness as low as 0.5 µm on a Brückner LISIM® production line
| | | Production speed: 350-400 m/min
| | | Further products: PEN capacitor films (better heat resistance compared to normal PET films) |
Brückner`s first class equipment | | 100% clean room suitability
| | | Leading twin screw technology, optimizing the extremely important extrusion process
| | | Precise direct drives, ideal for sensitive thin-film production
| | | Proprietarily developed TCE system for an optimal thickness profile adjustment |
Elaborate TDO oven design | | Independent fan adjustment for top and bottom for excellent film flatness control
| | | Floating nozzles for perfect air curtain, temperature separation and levelling |
Pull roll stand with active tension control - ATC | | Maintain film tension under changing conditions (temperature, speed, film properties)
| | | No nip rolls: tension separation with high friction on rolls No dust, no wear, no wrinkles |
Latest high-speed winder concept for optimal winding quality | | Bow adjustable contact roll for a constant pressure over the complete width
| | | New: LIWIND system - revolutionary contact roll damping for excellent winding performance and increased line efficiency. |
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