To miniaturize a power supply unit which has a power supply circuit formed by a printed circuit board and has a power transformer built onto the board.
The printed circuit board is provided with a notch for insertion of an iron core of the power transformer. A wiring pattern forming wiring of the power supply circuit and a winding pattern forming windings of the power transformer are formed to be separated from each other on a plurality of such printed circuit boards having such a notch. The plurality of printed circuit boards are laminated to form a printed circuit board assembly. The assembly is provided with a through-hole which has a conductive layer therein for connection between the patterns of the printed circuit boards as layers. The iron core is inserted into the notch of the assembly to assemble a power transformer.
Yoshihide Komada
Kiyoshi Matsuzaki
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