Transformer

Abstract

Transformer comprises a core (K1, K2), a primary winding (W1) and at least one secondary winding (W2), which are arranged as conductors on one or more layers of a flat carrier, and a coil former with a chamber system having chambers (C1, C2), which accommodate the layers with the windings (W1, W2). At least one of the chambers (C1, C2) is closed at least in regions, with the result that long distances for creepage paths are obtained. As a result of this, it is possible to adhere to existing safety regulations for the mains power supply isolation even with very compact dimensions and/or with full utilization of the width available for the conductor tracks. The chamber system can be formed from two or three plastic parts (P1, P2, P3) by mating. The layers with the conductor tracks are routed laterally out of the chamber system in order to make contact with terminals. In an advantageous refinement, webs with metallized slots are arranged on walls of the chamber system, in order to make contact with the conductor tracks (L). The slots are, for example, notched or trough-shaped depressions in which the carrier layers latch into place and are held thereby. The electrical contact afforded by the slots can be additionally supported by a solder-paste application with subsequent soldering. The lateral contacts mean that plated-through holes are avoided in the case of the carrier layers, with the result that the latter can be produced significantly more inexpensively. By virtue of the chamber system, it is possible for the openings in a core, for example an E/E or E/I core, to be utilized significantly better if the transformer has to comply with a sufficient insulation strength, such as in the case of mains power supply isolation, for example.