Planartransformator für Schaltnetzteile zur Erzeugung von Kleinspannungen und Verfahren zu dessen Herstellung

摘要

The proposed planar transformer (1) for a switched-mode power supply used for producing low voltages comprises two or more plastic carrier plates (2) on which are printed helical primary or secondary coils, the carrier plates form a sandwich with an insulating layer between them and are provided with a magnet core; a central limb of the magnet core protrudes through a central aperture in the carrier plates and each carrier plate (2) is provided on both faces with an imprinted coil (3a, 3b), the coils being connected in series by a plated-through interconnection. To improve potential separation with a view to adapting the coils to low-power outputs and simplifying manufacture, the coils (3a, 3b) are imprinted on a 10-100 micron thick plastic film (12). Two coil ends (3c, 3d) lie exposed over a notch (10) in the plastic film (12) and the plastic film (12) provided with the two coils (3a, 3b) has an insulating thermoplastic synthetic material (11) sprayed around it, said material pressing the two coil ends (3c, 3d) firmly together in the region of the notch (10). During manufacture of the carrier plates (2), the coil ends (3c, 3d) are made to lie exposed above the notch (10) in the plastic film (12) and the plastic film (12) provided with the coils (3a, 3b) is provided with a surrounding insulating thermoplastic synthetic material (11) which is sprayed under high pressure. To assemble a planar transformer (1), two or more carrier plates (2) provided with surrounding material (11) are stacked, the magnet core is fitted and the components are fixed with a sprayed insulating thermoplastic synthetic substance.