JPH0810658B2 - Split coil type inductance element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency thin film inductance element, and to an improvement of an exciting conductor for increasing an effective cross section of a coil in a high frequency region.

[0002]

2. Description of the Related Art FIGS. 7A and 7B show the shape of a spiral coil or a comb coil of a thin film inductor which has been conventionally studied. Generally, by arranging these coils around a magnetic core thin film via an insulating film, or by arranging a magnetic core on one or both surfaces of these coils via an insulating film, an inductance element such as a thin film inductor or a transformer is manufactured. ing.

[0003]

However, under the present circumstances, it is necessary to increase the number of turns of the coil in order to obtain a high inductance in these inductance elements. Along with this, the resistance of the coil increases, which causes the Q of the inductance element to decrease. In order to solve this, a method of increasing the coil film thickness to reduce the resistance may be considered, but in the high frequency region, the entire coil cross section cannot be effectively used even if a single layer thick coil is used due to the skin effect. Therefore, even if the film thickness of the single-layer coil is simply increased, the resistance of the coil in the high frequency region cannot be reduced.

The present invention has been made in view of the above circumstances, and in a high frequency thin film inductance element, by increasing the effective section of the coil in the high frequency region, the split coil type which can reduce the resistance of the coil in the high frequency region. An object is to provide an inductance element.

[0005]

In order to solve the above-mentioned problems, the present invention provides an inductance element in which an exciting conductor is arranged around a thin film magnetic body with an insulating film interposed therebetween. It is characterized by

[0006]

With the above-mentioned means, the insulating film is inserted so that the minor axis of the coil having the rectangular cross section has the width within the skin depth, and the coil is divided into two or more layers. To increase the effective area,
It is a useful means for increasing the Q of the high frequency inductance element.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. Example 1

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows a sectional view taken along the line AB of FIG. For convenience of explanation, a winding type inductor will be described as an example. Insulating substrate 1
A high-frequency thin film inductance element in which a coil 2 of an exciting conductor is wound around a magnetic core 3 made of a thin film magnetic material via an insulating film 4 is formed on the above. In FIG. 1, the insulating film 4 between the coil 2 and the magnetic core 3 is omitted to avoid complication. The coil 2 has a structure in which a two-layer coil is wound with an insulating film 5 interposed therebetween. A method of dividing the coil 2 into two layers is shown in FIGS. That is, as shown in FIG. 3, this is a method in which the insulating layer 5 is sandwiched substantially parallel (or substantially at right angles) to the major axis of a rectangular cross section cut at right angles to the longitudinal direction of the coil 2. In this case, the width of the conductor portion of the divided coil 2 is determined as follows. The skin depth of copper shown in FIG. 5, that is, the value is 1 / with respect to the current density on the conductor surface.
From the relationship between the depth from the skin and the frequency at which e = approximately 1 / 2.7, the skin depth of copper corresponding to the operating frequency of the inductance element can be known. Therefore, the film thickness of one layer of the coil 2 is about twice the skin depth. The insulating film 5 between the conductors is made of a thermosetting resist film or SiO ₂ film. In FIG. 2, the coil 2 in the plane direction has two layers, but the coil 2 in the vertical direction, that is, in the joint portion of the coil 2 has a single layer. As a result, the effect of forming two layers is sufficiently exhibited. As shown in FIG. 4, when the coil 2 is divided in the vertical direction, that is, the joint portion of the coil 2 is divided by the insulating film 5, the entire coil 2 becomes a divided coil, which is effective in reducing resistance in a high frequency region. Example 2

FIG. 6 is a schematic sectional view of an embodiment showing another method of dividing the coil. This is a method in which the insulating film 5 is sandwiched only in the central portion of the coil 2 to form a multilayer structure. According to this method, the coupling portion of the first embodiment also becomes a multi-layer split coil, which is more effective, and is effective in increasing the Q of the high frequency inductance element.

In general, the resistance is reduced by increasing the film thickness of the coil in the low frequency region. However, in the high frequency region, even if a thick film coil is used, the coil cross section that is effectively used due to the skin depth is limited. It has been difficult to reduce the resistance of the coil in the high frequency region. In the inductance element according to the present invention, the coil is divided in consideration of the skin depth, that is, the minor axis of the rectangular cross-section coil is divided into about the skin depth and the coil is effectively used within the skin depth. It is very advantageous for achieving high Q. In the above embodiment, the case where the moving body is divided into two layers through the insulating layer has been shown, but if the number of insulating layers is increased and the thickness of the conductor is increased, the resistance is further reduced, and a more remarkable effect is obtained. can get.

[0011]

As described above, according to the present invention, by dividing the coil, the resistance of the coil in the high frequency region can be reduced and the Q of the inductor can be increased.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AB of FIG.

FIG. 3 is a configuration explanatory view showing an example of a coil dividing method according to the present invention.

FIG. 4 is a structural explanatory view showing another example of the coil dividing method according to the present invention.

FIG. 5 is a characteristic diagram showing the relationship between the skin depth of copper and frequency.

FIG. 6 is a perspective view showing a method of dividing a coil into multiple layers according to a second embodiment of the present invention.

FIG. 7 is a schematic view of a conventional planar coil.

[Explanation of symbols]

1 ... Insulating substrate, 2 ... Coil, 3 ... Magnetic core, 4, 5 ... Insulating film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Murakami 1-29 Komatsushima 1-chome, Aoba-ku, Sendai City, Miyagi Prefecture (56) Reference JP-A-2-126610 (JP, A)

Claims (2)

[Claims] 1. An inductance element in which a coil of an exciting conductor is arranged around a thin film magnetic body via an insulating film,
An insulator is sandwiched between each thin-film coil having a thickness within the skin depth.
In the laminated structure, one coil is made of an insulating material within the skin depth.
A split coil type inductance element characterized by being split into thin film coils of thickness . 2. The length of the short side of the rectangular cross section of each conductor portion having the divided rectangular cross section of the split coil is about twice the skin depth at the operating frequency of the inductance element. The split coil type inductance element according to claim 1.