Coil assembly comprising planar coil
Coil assembly ( 1 ) comprising a planar coil ( 2 ) comprising a plurality of turns ( 15 ) arranged in a trench ( 10 ) in a first magnetic core plate ( 3 ) and a second magnetic core plate ( 8 ), where the first magnetic core plate ( 3 ) and second magnetic core plate ( 8 ) are in direct contact with each other or separated by an electrically insulating insulator layer ( 5 ) with a thickness (t) equal to or less than 50 μm and least one tap ( 6 ) extends from the coil ( 2 ) in a respective via hole ( 11 ) through the first magnetic core plate ( 3 ) to a respective contact pad ( 7 ), wherein the coil ( 2 ) and the tap ( 6 ) are integrally formed.
1. A method of manufacturing a coil assembly device including a planar coil comprising a plurality of turns, comprising:
providing a first magnetic core plate with a thickness in a range of more than 200 μm up to 5000 μm,
providing a trench formed in a turn pattern with a depth in a range of 100 μm to 1000 μm, a width of turns of the trench in a range of 50 μm to 1000 μm, and spacing between the turns of the trench in a range of 50 μm to 1000 μm in the first magnetic core plate, and
providing via holes through the first magnetic core plate, a ratio of the width of the turns of the trench to the depth of the trench being 1:1.2 to 1:20, the thickness of the first magnetic core plate being in a range of more than 100 μm up to 4000 μm thicker than the depth of the trench,
providing an insulator layer covering at least a bottom of the trench, a substantial part of sidewalls of the trench, and a sidewall of each of the via holes, the insulator layer being deposited conformally on all surfaces, and a thickness of the insulator layer being in a range of 1 μm to 50 μm,
providing a seed layer in the trench, a total thickness of the seed layer being in a range of 100 nm to 700 nm,
providing coil conducting material by electroplating, filling the trench and the via holes during a same stage, a height of coil conducting material of the turns of the coil being in a range of more than 100 μm up to 1100 μm,
providing a second magnetic core plate with a thickness in a range of 50 μm to 4000 μm,
providing a recess in the second magnetic core plate, and
mounting the second magnetic core plate on the first magnetic core plate,
wherein at least one tap extends from the coil in a respective via hole through the first magnetic core plate to a respective contact pad, and the coil and the at least one tap are integrally formed.
2. The method according to claim 1 , wherein coil conducting material is provided on a side of the first magnetic core plate which is opposite to a side of the first magnetic core plate where the trench is present.
3. The method according to claim 1 , wherein the seed layer is deposited through a shadow mask.