JPH04137610A - Flat inductance element - Google Patents

Abstract

PURPOSE:To narrow or get rid of gaps between a flat coil and ferromagnetic layers and facilitate manufacture of a thinner element and increase in inductance by drawing one end of a wound wire from the center of the flat coil to the outside through a through hole made in approximately the center of one of the ferromagnetic layers in the direction of the thickness. CONSTITUTION:Through holes 5 are made in approximately the centers of a lower insulating layer 2b and a lower ferromagnetic layer 3b in the direction of the thickness and one end of a wound wire 4b is drawn from the center of a flat coil 1 to the outside of the ferromagnetic layer 3b through the through holes 5. The sire 4b is not drawn between the flat coil 1 and the lower ferromagnetic layer 3b, therefore, no gap to draw the wire 4b is required. Hence the thickness of the whole device is decreased at least by the thickness of the wire forming the flat coil. Because the gap of a magnetic path is almost removed, the inductance value increases remarkably.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a planar inductance element, and particularly to a thin planar inductance element used in choke coils and transformers of power supplies, inverters, oscillators, etc. Regarding elements.

(Prior Art) For example, a planar inductance element configured as shown in cross section in FIG. 2 is known as a planar inductance element used in choke coils, transformers, etc. of power supplies, inverters, etc.

In Fig. 2, 1 indicates a planar coil, and this planar coil 1 can be formed by winding a winding (insulated wire) in a spiral, or by printing a spiral conductor pattern on a substrate. It consists of a method. Moreover, this planar coil 1 can be arranged in multiple layers with insulating layers interposed therebetween, if necessary.

Thus, on both outer main surfaces (upper and lower surfaces) of the planar coil 1, a ferromagnetic material layer formed by laminating a plurality of ferromagnetic thin strips, for example, is provided with insulating layers 2a and 2b interposed therebetween. 3
a and 3b are arranged (arranged). The winding ends of the windings constituting the planar coil 1 are drawn out as lead wires 4a and 4b, respectively.

(Problems to be Solved by the Invention) However, the planar inductance element having the above configuration has the following disadvantages. That is, the lead wire 4b from the center of the planar coil 1 is connected to the planar coil 1.
and the lower ferromagnetic layer 3b (lower insulating layer 2b) and are drawn out to the outside, so a gap at least equivalent to the thickness of the winding (insulated wire) is required between them. do.

Since such a wide gap is created in the magnetic path, there is a problem in that the inductance decreases.

In addition, a plurality of the planar coils 1 are laminated via insulating layers, a lead wire 4b from the center is drawn out between the planar coils 1, and ferromagnetic layers are laminated above and below each of the lead wires 4b. When used as an element, there was a problem in that the magnetic coupling coefficient between the planar coils 1 was low, and the conversion efficiency of the transformer was low. These problems can be said to be serious problems in the current situation where various electric circuits and electronic circuits are being made smaller and have higher performance (higher functionality).

The present invention was made to solve these problems, and aims to provide a thin planar inductance element with high inductance and improved coupling coefficient.

[Structure of the Invention] (Means for Solving the Problems) A planar inductance element of the present invention includes at least one planar coil, an insulating layer disposed on the main surface side of the planar coil, and a planar inductance element of the present invention. and a ferromagnetic layer disposed on the outermost main surface of the coil with the insulating layer interposed therebetween, wherein the winding end portion drawn out from the center of the planar coil is connected to the ferromagnetic layer. It is characterized by having a hole penetrating through the thickness direction substantially in the center of either one of the holes and extending outward.

In the present invention, examples of the ferromagnetic material constituting the ferromagnetic layer include ferromagnetic materials with high magnetic permeability, such as amorphous metal, permalloy, and soft ferrite. Further, a layer made of a ferromagnetic material is formed by laminating thin films of such a magnetic material or by forming a magnetic material into a plate shape.

(Function) The planar inductance element according to the present invention has a through-hole in the thickness direction that is formed approximately at the center of the ferromagnetic layer on either one (upper or lower) of the outermost main surface of the planar coil. Since the lead wire from the center of the planar coil is drawn out through the hole, the gap between the planar coil and the ferromagnetic layer is reduced, and the overall thickness is reduced. In other words,
There are no air gaps in the magnetic path, improving inductance.

In addition, in a structure in which multiple planar coils are stacked,
The magnetic coupling coefficient between each planar coil is improved, and the conversion efficiency of the transformer is improved.

(Example) Hereinafter, the present invention will be explained in detail with reference to FIG.

In Fig. 1, numeral 1 indicates a planar coil formed by spirally winding an insulated winding wire, and permalloid coils are provided on the upper and lower sides (amphibious side) of the coil through insulating layers 2a and 2b, respectively. Ferromagnetic layers 3a and 3b with high magnetic permeability are laminated and arranged. A hole 5 penetrating each of the lower insulating layer 2b and the lower ferromagnetic layer 3b in the thickness direction is formed at approximately the center of the lower insulating layer 2b and lower ferromagnetic layer 3b.
The end portion of the winding 4b drawn out from the center of the planar coil 1 is inserted through and drawn out to the outside of the ferromagnetic layer 3b.

In the planar inductance element configured in this manner, the lead wire 4b is not led out between the planar coil 1 and the lower ferromagnetic layer 3b, so that a gap for leading out the lead wire 4b is not required. Therefore, the overall thickness can be reduced by at least the thickness of the windings forming the planar coil. Furthermore, since there are almost no air gaps in the magnetic path, the inductance value is significantly improved.

Furthermore, in a structure in which a plurality of planar coils are stacked vertically with insulating layers in between, there are gaps between each of the planar coils and between the planar coil and the ferromagnetic layer. In other words, since the air gap in the magnetic path is reduced, the magnetic coupling coefficient between each coil increases, and the conversion efficiency of the transformer improves.

In the above embodiment, only the end of the winding drawn out from the center of the planar coil was inserted through a hole drilled in the ferromagnetic layer. Another hole may be formed in the end of the winding to allow the ferromagnetic layer to pass therethrough.

[Effects of the Invention] As explained above, the planar inductance element according to the present invention has a configuration in which the inner winding end is drawn out through the through hole provided in the ferromagnetic layer. The gap between the shaped coil and the ferromagnetic layer is reduced or eliminated,
It is easy to reduce the overall thickness and improve inductance. Thus, the planar inductance element according to the present invention is
For example, it can be said to be suitable for use in mounting circuits for the purpose of making circuit devices more compact.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the configuration of a planar inductance element according to the present invention, and FIG. 2 is a sectional view showing the configuration of a conventional planar inductance element. 1... Planar coils 2a, 2b... Insulating layers 3a, 3b... Ferromagnetic layers 4a, 4b... Lead wire 5... Penetration hole

Claims (1)

[Claims] At least one planar coil, an insulating layer disposed on the main surface side of the planar coil, and an insulating layer disposed on the outermost main surface of the planar coil with the insulating layer interposed therebetween. In a planar inductance element comprising a ferromagnetic layer, a hole passing through a winding end drawn out from the center of the planar coil in the thickness direction approximately at the center of one of the ferromagnetic layers. A planar inductance element characterized by being inserted through the element and extending outward.