| 摘要 |
<p>A planar intrinsically safe transformer comprises a single, bonded, multilayer printed circuit board comprising a plurality of layers (20a, 20b, 20c) of insulating material each carrying conductor tracks (TL2, TL3; TL4, TL5; TL6, TL7) on at least one side, an additional thin layer (22a, 22b, 22c, 22d) of insulating material between each pair of adjacent conductor tracks, and a magnetic core (12). No conductor track (TL3 to TL6) buried between two of the thicker layers (20a, 20b, 20c) extends to within a predetermined distance (t) from the edge of the board, and each of the thicker layers (20a, 20b, 20c) which carries tracks on both sides is at least as thick as said predetermined distance (t). <IMAGE></p> |
