JPH1050522A - Planar coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the inductance characteristics by constituting a conducting part to be coated with a ferromagnetic material layer. SOLUTION: An insulating board 1 is made of an insulating organic board member, produced by impregnating a woven fabric of basic glass material with epoxy resin and then curing the epoxy resin, wherein a predetermined number of sheets of woven fabrics are laminated together with metal sheet materials for forming a coil pattern corresponding to a conductive part 2 on the surface, and then they are cured thermally. The conductive part 2 has a planar coil pattern, including an angular spiral coil part 2a where adjacent patterns are spaced apart by a specified insulation distance from each other and terminals, i.e., land parts 2b, 2b, to be connected with a predetermined circuit. A coating layer 3 of ferromagnetic material is formed by plating to cover the entire surface at the conductive part 2, including the edge 2c of the spiral conductive part 2. According to the arrangement, high inductance characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar coil which can be used as an inductance of a choke coil or a low-pass filter, and more particularly to a planar coil having a structure in which a coil pattern is formed on an insulating substrate and covered with a coating layer.

[0002]

2. Description of the Related Art Conventionally, a coil component as an inductance element such as a choke coil or a low-pass filter is formed by winding a linear conductor and providing a core material having ferromagnetic characteristics such as ferrite at the center of the coil as required. It is composed. However, with the recent need for lightness, small size, and the expansion of the operation characteristics of products to a high frequency band, a planar coil in which a coil pattern as a spiral conductive portion is formed on an insulating substrate may be used.

[0003] This planar coil is thin and has low electric loss in a high frequency band. However, when high inductance characteristics are required, for example, a through hole having a predetermined size is formed at the center of a spiral coil pattern. A structure in which a ferrite core material is formed and inserted is used.

[0004]

Therefore, in the above-mentioned structure in which the ferrite core material is inserted, the thickness of the planar coil portion is increased, and the assembling work such as the step of making a hole in the insulating substrate or the insertion of the ferrite core material is performed. And the production cost was high.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flat coil having a coil pattern formed on an insulating substrate without using an additional member such as a ferrite core material. An object of the present invention is to provide a planar coil capable of obtaining inductance characteristics.

[0006]

According to a first aspect of the present invention, there is provided a planar coil in which a spiral conductive portion is formed on an insulating substrate.
The conductive portion is configured such that the surface is applied by an application layer made of a ferromagnetic material. Thereby, the magnetic resistance of the magnetic path of the magnetic flux generated around the conductive portion becomes small.

According to a second aspect of the present invention, there is provided a planar coil in which a spiral conductive portion is formed on an insulating substrate, and at least two layers are stacked to connect the conductive portions of the respective layers. Is formed such that the surface is covered by a deposition layer made of a ferromagnetic material. Thereby, the magnetic resistance of the magnetic path of the magnetic flux generated around the conductive portion of the multilayer planar coil becomes small.

According to a third aspect of the present invention, there is provided a planar coil, wherein the deposition layer according to the first or second aspect is applied so as to cover the entire surface of the conductive portion. Thereby, the magnetic resistance of the magnetic path of the magnetic flux generated around the conductive portion becomes smaller.

In the planar coil according to the fourth aspect, the adhered layer according to the first to third aspects is formed by plating. Thereby, the deposited layer can be formed with high productivity.

[0010] In the planar coil according to the fifth aspect, the ferromagnetic material according to the fourth aspect is a nickel material. Thereby, corrosion resistance can be obtained without performing other rust prevention treatment.

Further, in the planar coil according to the present invention, the material for forming the conductive portion and the deposition layer according to the first or second aspect is formed by a combination of materials that do not diffuse with each other.
Thereby, there is no decrease in conductivity and no decrease in magnetic permeability of the deposition layer due to the diffusion of the material forming the deposition layer into the conductive portion.

Further, in the planar coil according to the present invention, the conductive portion is formed of a copper material, and the adhered layer is formed of an iron material. Thereby, the adhered layer is formed of the iron material.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the first embodiment of the planar coil of the present invention will be described.
The second embodiment will be described with reference to FIGS. 1 and 2, the second embodiment will be described with reference to FIG. 3, and the third embodiment will be described with reference to FIGS. 4 and 5.

[First Embodiment] FIG. 1 is a plan view of a planar coil according to a first embodiment. FIG. 2 shows FIG.
FIG. 3 is an explanatory sectional view of the planar coil shown in FIG.

The planar coil includes an insulating substrate 1, a spiral conductive portion 2 formed on the surface of the insulating substrate 1, and a deposition layer 3.

The insulating substrate 1 is, for example, an organic substrate member having an insulating property obtained by impregnating and curing a woven cloth made of a glass base material with an epoxy resin, and forms a coil pattern corresponding to the conductive portion 2 on the surface, which will be described later. For example, a predetermined number of woven fabrics are laminated and heat-cured together with a sheet material made of a metal material such as a copper material.

The conductive portion 2 is a coil pattern of a planar coil. In this device, a spiral coil portion 2a having an angular shape with a predetermined insulating distance between adjacent patterns and a predetermined circuit are connected. And land portions 2b, 2b, which are terminals for the connection. Note that the spiral pattern is not limited to the square shape, and may be, for example, a substantially circular shape. This conductive part 2
Is formed from a copper-clad laminate or the like formed by the insulating substrate 1 by an etching process or the like that leaves a predetermined spiral pattern or the like by a coil portion etching process.

The coating layer 3 is a coating portion made of a ferromagnetic material that covers the surface of the conductive portion 2. The coating layer 3 has ferromagnetism, has a high surface hardness, is excellent in abrasion resistance, and has corrosion resistance. It is also formed by a plating process using an excellent nickel material. This plating treatment is a surface treatment method used for forming a general printed circuit board, for example, for improving corrosion resistance, and has high productivity. As shown in FIG. 2, the deposition layer 3 is formed so as to cover and cover the entire surface including the edge 2 c of the conductive portion 2 having a spiral shape, as shown in FIG. 2. The material to be deposited is not limited to a nickel material, but may be iron, cobalt, or the like. The deposition may be performed by plating, for example, by coating or vapor deposition. You may.

Next, an example and an operation of the planar coil of the above embodiment will be described.

[Embodiment 1] A conductive portion 2 is formed on an upper surface of an insulating substrate 1 having a predetermined outer dimension by a copper foil having a thickness of 50 μm.
When a spiral coil pattern having a width of 0.2 mm and an insulation distance between adjacent patterns of 0.1 mm and one side of the outer circumference of about 4 mm is formed, a frequency of 1 MHz in a state where the adhesion layer 3 is absent is obtained. The inductance value based on the sine wave signal was 50.3 nH. For it,
When the entire surface of the copper foil of the conductor portion 2 is adhered by an adhesion layer made of a nickel material having a thickness of 20 μm, the inductance value by the same sine wave signal as described above is 56.
It was 5 nH. Then, an increase in the inductance value of about 12% was recognized.

The above-mentioned increase in the inductance value is due to a decrease in the magnetic resistance of the magnetic path of the magnetic flux generated around the conductor when the current flows through the conductor portion 2. Therefore, by configuring the conductor portion 2 so as to cover and cover all surfaces including the edge 2c where the magnetic flux concentrates, the magnetic resistance is further reduced.

In the above-described planar coil, the magnetic resistance of the magnetic path of the magnetic flux generated around the conductive portion 2 is reduced.
High inductance characteristics can be obtained without using an additional member such as a ferrite core material. Further, since the magnetic path of the magnetic flux generated around the conductive portion has a smaller magnetic resistance, higher inductance characteristics can be obtained. Further, since the deposited layer can be formed with high productivity, low cost is achieved. In addition, since corrosion resistance can be obtained without performing other rust preventive treatment, rust preventive treatment is not required and low cost is achieved.

[Second Embodiment] FIG. 3 is an explanatory sectional view of a planar coil according to a second embodiment.

The planar coil comprises a conductive portion 2 and a coating layer 3
Is formed by a combination of materials that do not diffuse with each other. The material of the adhered layer 3 is different from that of the first embodiment, and has a rust prevention layer 4. This is the same as that of the first embodiment.

The deposition layer 3 is made of an iron material as a combination of the copper material of the conductive portion 2 and a material that does not diffuse with each other. This iron material is ferromagnetic, has a high surface hardness, is excellent in abrasion resistance, and is inexpensive. The nickel material, which is the material of the adhered layer in the first embodiment, diffuses at a high temperature of, for example, about 60 ° C. with respect to the copper material of the conductive part 2, but almost diffuses at about 100 ° C. Nothing to do. Therefore, at a practical temperature, the conductivity of the conductive portion 2 is prevented from being reduced due to mutual diffusion.

The rust preventive layer 4 is for maintaining the corrosion resistance of the adhered layer 3 made of an iron material. The rust preventive layer 4 is made of a resin material and has a predetermined thickness by a coating process, for example. Is formed as appropriate so as to cover the surface, for example, by a coating operation.

According to the above-described planar coil, since the material for forming the adhered layer 3 does not diffuse into the conductive portion 2 and the conductivity does not decrease, a decrease in inductance characteristics due to an increase in electric loss is prevented. Is done. Further, since the adhered layer 3 is formed of an iron material, low cost is achieved by being formed of an inexpensive material.

The combination of the conductive portion 2 and the deposition layer 3 does not limit the conductive portion 2 to a copper material and the deposition portion 3 to an iron material. The attachment portion 3 may be made of a nickel material, the conductive portion 2 may be made of a silver material, and the attachment portion 3 may be made of an iron material. This combination of the silver material and the iron material does not diffuse with each other, and does not lower the inductance characteristics even at a higher temperature.

[Third Embodiment] FIG. 4 is a plan view of a conductive portion of each layer of a planar coil according to a third embodiment.
(A) is the first layer surface, (b) is the second layer surface, and (c) is the second layer back surface. 5A and 5B are cross-sectional explanatory views of the planar coil shown in FIG. 4, wherein FIG. 5A shows a state before bonding and FIG.

The planar coil is a planar coil formed by forming a spiral conductive portion on an insulating substrate, laminating at least two layers and connecting the conductive portions of the respective layers, and forming a conductive portion formed on the upper and lower surfaces. In the first embodiment described above or in the second
This is the configuration of the embodiment. This is provided with insulating substrates 1a and 1b, a conductive part 2, an adhesion layer 3, and conduction holes 4a and 4b, and has two layers.

The conductive part 2 is a terminal for connecting to a predetermined circuit a spiral coil part 2a having a predetermined insulating distance between adjacent patterns on the surface of the insulating substrate 1a. And a certain land portion 2b.

The conductive holes 4a and 4b are for electrically connecting the conductive portions of the respective layers. The conductive portions 4a, which are called through holes for providing conduction between the different insulating substrates 1a and 1b, A conduction hole 4b called an inner via hole for establishing conduction between the conduction portion on the front surface and the conduction portion on the back surface of the same insulating substrate.
There is. These conductive holes 4a and 4b are generally provided with a conductive layer by plating on the inner surface after drilling holes with a drill-like material, so that conduction between the layers is established.

One of the manufacturing procedures is as follows: first, an insulating substrate 1a having a copper-clad surface for forming the coil pattern of the conductive portion 2; and a conductive portion having the coil pattern formed thereon. And an insulating substrate 1b having a copper-clad surface for forming a coil pattern of the conductive portion 2 on the back surface and having the above-described conduction hole 4b (inner via hole) on the back surface. The insulating substrates 1a, 1
A prepreg 1c impregnated with an epoxy resin is appropriately placed on a woven fabric made of a glass base material for bonding b, and heated and pressed to bond the insulating substrates 1a and 1b. Next, in order to electrically connect the conductive portions 2 of each layer, through holes for forming conductive holes 4a (through holes) are provided, and the insulating substrate 1 is formed.
A coil pattern is formed by etching on the copper-clad surface between the front surface of a and the back surface of the insulating substrate 1b, and the inner surface of the through hole is connected by plating to form a conduction hole 4a (through hole). Thereafter, the deposition layer 3 is deposited by plating or the like, thereby forming a target configuration.

[Embodiment 2] The conductive portion 2 is formed on the upper surfaces of the insulating substrates 1a and 1b having predetermined outer dimensions and on the rear surface of the insulating substrate 1b.
The copper foil has a thickness of 50 μm, a width of 0.2 mm, an insulation distance between adjacent patterns of 0.1 mm, and a spiral coil pattern of approximately 4 mm on one side of the outer periphery to form a three-layer multilayer substrate. In some cases, the inductance value based on a sine wave signal having a frequency of 1 MHz without the deposition layer 3 was 370 nH. On the other hand, when the entire surface of the copper foil of the conductor portion 2 on the front surface of the insulating substrate 1a and the back surface of the insulating substrate 1b is formed by a 20 μm thick nickel material, The inductance value due to the signal was 419 nH. Then, an increase in the inductance value of about 13% was recognized.

The increase in the inductance value is caused by the fact that the adhesion layer 3 forms a closed loop of a magnetic flux generated around the conductor when a current flows through the respective conductive portions 2 formed on the upper surface and the lower surface. This is because the magnetic resistance of the road is reduced. Therefore, in particular, by configuring so that only the upper surface and the lower surface, that is, other than the upper surface of the insulating substrate 1b of the intermediate layer, the conductor portion 2 is adhered by the adhered layer 3,
With a small number of additional processing steps, one having a low magnetic resistance can be obtained effectively.

The above-described planar coil is reduced by additional processing in which the magnetic resistance of the magnetic flux of the magnetic flux generated around the conductive portion of the multilayer planar coil is small, so that the ferrite core material or the like is used in the planar coil using the multilayer substrate. The high inductance characteristic can be obtained without using the additional member.

[0037]

According to the first aspect of the present invention, since the magnetic resistance of the magnetic path of the magnetic flux generated around the conductive portion is small, high inductance characteristics can be achieved without using an additional member such as a ferrite core material. Can be obtained.

In the planar coil according to the second aspect of the present invention, the magnetic resistance of the magnetic path of the magnetic flux generated around the conductive portion of the multilayer planar coil has a small magnetic resistance. The high inductance characteristic can be obtained without using the additional member.

In the planar coil according to the third aspect, in addition to the effects of the first or second aspect, since the magnetic path of the magnetic flux generated around the conductive portion has a smaller magnetic resistance, it is higher. Inductance characteristics can be obtained.

Further, in the planar coil according to the fourth aspect, in addition to the effects of the first to third aspects, since the deposited layer can be formed with high productivity, low cost is achieved.

Further, the flat coil according to the fifth aspect has the same effects as those of the fourth aspect, and can provide corrosion resistance without any other rust prevention treatment. As a result, low cost is achieved.

According to the planar coil of the present invention, in addition to the effects of the first and second aspects, the material for forming the adhered layer is diffused into the conductive portion, whereby the conductivity is reduced and the permeability of the adhered layer is reduced. Since there is no decrease in magnetic susceptibility, a decrease in inductance characteristics due to an increase in electrical loss is prevented.

Further, in the planar coil according to the seventh aspect, in addition to the effect of the sixth aspect, since the adhered layer is formed of an iron material, the cost can be reduced by being formed of an inexpensive material. Is achieved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a planar coil according to a first embodiment of the present invention.

FIG. 2 is an explanatory sectional view of the planar coil shown in FIG. 1;

FIG. 3 is an explanatory sectional view of a planar coil according to a second embodiment.

FIGS. 4A and 4B are plan configuration diagrams of a conductive portion of each layer of the planar coil according to the third embodiment, wherein FIG. 4A is the first layer surface, FIG. 4B is the second layer surface, and FIG. It is.

FIG. 5 is an explanatory cross-sectional view of the planar coil shown in FIG. 4;
Shows before bonding, and (b) shows after bonding and formation of the adhered layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Conductive part 3 Adhered layer

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[Procedure amendment]

[Submission date] August 4, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

The above-mentioned increase in the inductance value is due to a decrease in the magnetic resistance of the magnetic path of the magnetic flux generated around the conductor when the current flows through the conductor portion 2. Therefore, by configuring the conductor portion 2 so as to cover and cover all surfaces including the edge 2c , the magnetic resistance is further reduced.

Claims (7)

[Claims] 1. A planar coil in which a spiral conductive portion is formed on an insulating substrate, wherein the conductive portion is configured such that the surface is covered by a deposition layer made of a ferromagnetic material. And a planar coil. 2. A planar coil in which a spiral conductive portion is formed on an insulating substrate, and at least two layers are stacked and the conductive portions of the respective layers are connected to each other. A planar coil characterized in that the surface is adhered by an adhesion layer made of a magnetic material. 3. The planar coil according to claim 1, wherein the deposition layer is configured so as to cover and cover all surfaces of the conductive portion. 4. A planar coil according to claim 1, wherein said coating layer is formed by plating. 5. The planar coil according to claim 4, wherein said ferromagnetic material is a nickel material. 6. The planar coil according to claim 1, wherein the material for forming the conductive portion and the deposition layer is formed by a combination of materials that do not diffuse with each other. 7. The planar coil according to claim 6, wherein the conductive portion is formed of a copper material, and the adhered layer is formed of an iron material.