Planar magnetics E-book

Nowadays, planar magnetic elements are commonly used in the power electronics industry due to their
advantages over wound magnetic components, especially in high-frequency power converters. This technology
allows for low-profile, core shapes which cover wider surface areas compared with conventional transformers,
giving a better heat dissipation and larger cross-sectional areas.

Other advantages are:

•Higher power density.
•AC resistance and leakage inductance minimization due to easier interleaving winding arrangements.

AC Resistance and leakage inductance minimization by easy interleaving arrangements.
With regards to the manufacturing process, the rigid structure of the printed circuit board allow for the bobbin
to be removed from the component. This is necessary in wound transformers for easier winding manufacturing,
thus reducing this number of necessary elements in the magnetic component manufacturing.
Number of magnetics parts and therefore cost can be reduced since the use of coil formers are no longer
needed in planar transformers.

Nothing comes for free and although planar magnetics have the aforementioned benefits they also have some
drawbacks. High current applications require stacking of several copper lead frames that require specific
manufacturing techniques. It is well known as well that whereas leakage inductance can be reduced, planar
transformer have considerable parasitic capacitance that need to be taken into account.