Planar coils (top and bottom sides) for wireless charging, for low power application such as mobile phone.
The rectangular backing has dimensions 38 x 32 x 1 mm. The black backing is 0.5 mm thick (it is deposited on the white layer of a thin substrate) and is partially filled with magnetic particles to increase magnetic coupling. The coil is wound with a double 0.25 mm thick wire, wound in a bifilar way, but shorted together at the terminals. There are 17 effective turns. The weight of the assembly is around 4.2 g. Inductance at 100 kHz = 11.1 μH, DC resistance = 0.25 Ω.
Some of the data was available from the Digikey distributor, datasheet for TDK17M2-G: https://media.digikey.com/pdf/Data%20Sheets/TDK%20PDFs/WR-383250-17M2-G.pdf {accessed 2021-06-11}
wireless_charging_coils_tdk_e-m.jpg
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