The leakage inductance in a Flyback transformer negatively affects the efficiency of the converter itself. Leakage inductance stores energy in the core window area but is not transferred to the secondary. This energy is primarily dissipated either in the RCD clamp network or in a turn-off snubber as heat. Typically the leakage inductance is about 3-5% of the magnetizing inductance. The leakage inductance can be reduced by interleaving the secondary winding between two halves of the primary winding. It can also be reduced by minimizing the thickness of the insulation between the primary and secondary turns and spreading the winding on a longer center leg of the core.
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