JP3601619B2 - Common mode choke coil - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a common mode choke coil.
[0002]
[Prior art]
Conventionally, as a common mode choke coil , a winding type coil component 41 shown in FIG. 15 is known. The coil component 41 includes a core 42 and a wire 43 wound around the body of the core 42. The end of the wire 43 is wrapped around an external terminal 44 provided on the end face of the rectangular base of the core 42.
[0003]
Further, as shown in FIG. 16, a coil component 51 manufactured using a green sheet laminating technique is also known. The coil component 51 is manufactured by laminating magnetic green sheets provided with coil conductors 52 ₁ , 52 ₂ , 52 ₃ , and 52 ₄ on the surface and integrally firing them, and then forming external electrodes 56 and 57. ing. The coil conductors 52 _{1 to} 52 ₄ are electrically connected in series via a via hole or the like provided in the magnetic green sheet to form the coil 52.
[0004]
Further, a coil component 61 shown in FIG. 17 is known. The coil component 61 includes a coil portion 62 formed by laminating an insulator green sheet having a coil conductor provided on a surface thereof, and two magnetic cores 63 and 64 sandwiching the coil portion 62. For the insulator green sheet, a material containing no magnetic material is used.
[0005]
[Problems to be solved by the invention]
Among the above-described conventional coil components, the coil component 41 shown in FIG. 15 requires the core 42 to be formed individually and the wire 43 to be wound for each core 42. Further, since the wire 43 and the external terminals 44 are made of different materials, an electrical connection step such as soldering is required, and this step has to be performed for each coil component. As a result, the productivity of the coil component 41 was low and the cost was high. Further, there is a limit in reducing the size of the core 42 and the wire 43 due to handling problems.
[0006]
The coil component 51 shown in FIG. 16 is due to the multilayer structure, most of the process for the coil conductor 52 _{1-52 4} is formed by printing or transferring the magnetic green sheet is produced in the substrate state High productivity and handling problems have been solved. Coil conductors 52 _{1-52 4} is also suitable for miniaturization because it can be thinner and thinner form. However, there has been a problem that variations in electrical characteristics occur due to shrinkage of the magnetic green sheet in the firing step. In addition, since a closed magnetic path is formed for each magnetic green sheet, there is a problem that the inductance of the coil 52 is relatively small. In particular, when the coil component 51 is a transformer or a common mode choke coil, this problem is a major cause of lowering magnetic coupling between the coils and impairing performance.
[0007]
Further, the coil component 61 shown in FIG. 17 has good electromagnetic characteristics because the insulating green sheet does not contain a magnetic material, but has a problem that an effective magnetic path must be formed separately. That is, it is necessary to separately prepare the cores 63 and 64 made of a magnetic material. As a result, the productivity of the coil component 61 was low.
Therefore, an object of the present invention is to provide a small common mode choke coil having high productivity and excellent electric characteristics.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a common mode choke coil according to the present invention is:
(A) a first magnetic substrate;
(B) a laminate formed by stacking in the thickness direction an insulator layer made of a nonmagnetic layer, a coil pattern, and a lead electrode formed on the surface of the first magnetic substrate by a thin film forming means;
(C) a second magnetic substrate sandwiching the laminated body between the first magnetic substrate and the first magnetic substrate;
(D) an external electrode provided on an end surface of a laminated structure including the first magnetic substrate, the laminated body, and the second magnetic substrate;
(E) the coil pattern forms at least two coils, and the coils are covered with an insulator of an insulator layer;
(F) each of the coils is disposed in the insulator in a direction perpendicular to the thickness direction of the insulator layer , and is provided with a first magnetic substrate and a second magnetic substrate via an extraction electrode formed by being covered with the insulator . Electrically connected to external electrodes without penetrating the magnetic substrate,
It is characterized by.
[0009]
Also, common mode choke coil according to the present invention is further characterized in that each one of the lead electrode of the plurality of coils are provided on the same said insulator layer.
Further, in the common mode choke coil according to the present invention, in a coil pattern which is substantially overlapped in the thickness direction and adjacent to the first magnetic substrate, the conductor width of the coil pattern far from the first magnetic substrate is closer to the first magnetic substrate. The width of the conductor is smaller than the width of the conductor.
[0010]
[Action]
According to the above configuration, since the laminate does not include a magnetic material, there is no need to worry about variation in electrical characteristics due to shrinkage of the magnetic green sheet in the firing step. Further, the inductance does not decrease due to the closed magnetic path formed for each magnetic green sheet. Therefore, the electromagnetic characteristics of the plurality of coils are improved. Furthermore, a laminated body composed of an insulator layer and a coil pattern is formed on the first magnetic substrate with high precision by the thin film forming means, so that a small-sized common mode choke coil with high precision is produced. .
[0011]
And, by providing one extraction electrode of each of the plurality of coils on the same insulator layer, the number of insulator layers is reduced as compared with the case where the extraction electrodes are provided on different insulator layers, respectively. The manufacturing process is simplified. Further, when the extraction electrode is provided between the coil patterns in the thickness direction, the thickness of the insulator layer between the coil patterns is almost twice as large, and the insulation reliability is improved.
[0012]
Further, in the coil patterns adjacent in the thickness direction, if the conductor width of the coil pattern far from the first magnetic substrate is smaller than the conductor width of the coil pattern close to the first magnetic substrate, it is assumed that the adjacent two patterns are temporarily closed. Even if the two coil patterns are displaced from each other, the insulation interval between the coil patterns does not become small, and the withstand voltage does not decrease.
[0013]
【Example】
Hereinafter, an embodiment of a common mode choke coil according to the present invention will be described with reference to the accompanying drawings. In the embodiment, a case in which the common mode choke coil is manufactured as a single product will be described. However, in mass production, the mother board provided with a plurality of common mode choke coils is used to efficiently produce .
[0014]
As shown in FIG. 1, the common mode choke coil 1 is composed of magnetic substrates 2 and 3 and a laminated body 14 sandwiched between the magnetic substrates 2 and 3. The laminate 14 is formed by stacking insulator layers 4, 5, 6, 7, coil conductors 10, 11, and extraction electrodes 8, 9, 12, 13 in the thickness direction. Ferrite or the like is used as a material for the magnetic substrates 2 and 3. When ferrite is used, the choke coil 1 has high inductance and excellent high frequency characteristics.
[0015]
The extraction electrodes 8 and 9 are provided on the surface of the insulator layer 4, and one end of the extraction electrodes 8 and 9 is exposed at the front edge of the insulator layer 4. A spiral coil conductor 10 is provided on the surface of the insulator layer 5, and one end of the coil conductor 10 is electrically connected to a lead electrode 12 provided on an inner edge of the insulator layer 5. I have. A spiral coil conductor 11 is provided on the surface of the insulator layer 6, and one end of the coil conductor 11 is electrically connected to a lead electrode 13 provided on an inner edge of the insulator layer 6. I have.
[0016]
As a material of the extraction electrodes 8, 9, 12, 13 and the coil conductors 10, 11, a metal having excellent conductivity, for example, Ag, Pd, Cu, Al, or an alloy thereof is adopted. As a material of the insulator layers 4 to 7, a resin such as a polyimide resin, an epoxy resin, an acrylic resin, a cyclic olefin resin, or a benzocyclobutene resin, a glass such as SiO _2, or a glass ceramic is used. In this embodiment, a photosensitive polyimide resin is used. When a polyimide resin is used, the extraction electrodes 8, 9, 12, 13 and the coil conductors 10, 11 can be formed easily and with good adhesion on the insulating layers 4 to 6 by vapor deposition or sputtering. Physical and chemical properties of 4 to 7 can be excellent and stable.
[0017]
In the stacked state, the extraction electrode 8 is electrically connected to the coil conductor 10 through the via hole 15 provided in the insulator layer 5, and the extraction electrode 9 is connected to the via holes 16 a and 16 b provided in the insulator layers 5 and 6. It is electrically connected to the coil conductor 11 via. The coil conductors 10 and 11 constitute a pair of coils that are magnetically closely coupled.
[0018]
When the distance between the magnetic substrates 2 and 3 is as narrow as possible, the magnetic resistance is low and a larger inductance is obtained. In addition, a larger number of turns of the coil provides a larger inductance. On the other hand, the size of the choke coil 1 is desirably small, and the cost can be reduced from the viewpoint of the material used. Therefore, the thickness of the insulator layers 4 to 7 is preferably 10 μm or less, and the conductor width of the coil conductors 10 and 11 is preferably 100 μm or less. The thicknesses of the coil conductors 10 and 11 are arbitrarily set in order to provide a DC resistance according to the specifications of the coil component. It is preferable that the positioning of the coil conductors 10 and 11 be performed with high accuracy. From these viewpoints, thin film forming means such as photolithography is used for forming the insulator layers 4 to 7, the coil conductors 10 and 11, and the extraction electrodes 8, 9, 12, and 13.
[0019]
As shown in FIGS. 2 and 3, external electrodes 20 and 22 are provided on the front end face of the common mode choke coil 1, and external electrodes 21 and 23 are provided on the rear end face. The external electrodes 20, 21, 22, and 23 are electrically connected to extraction electrodes 8, 12, 9, and 13, respectively. The external electrodes 20 to 23 are formed by means such as vapor deposition, sputtering, and electroless plating, and firmly adhere to the end face of the choke coil 1. Further, if necessary, electroplating may be further performed to increase the thickness of the external electrodes 20 to 23. FIG. 4 is an electric equivalent circuit diagram of the choke coil 1.
[0020]
Next, a manufacturing procedure of the common mode choke coil 1 will be described with reference to FIGS.
As shown in FIG. 5, an insulator layer 4 is formed on the surface of the magnetic substrate 2 by a thin film forming means. As the thin film forming means, for example, a method such as photolithography or printing is employed. In the photolithography method, for example, a photosensitive resin film is formed on the entire surface of the magnetic substrate 2 by a spin method, a dipping method, a spray method, a transfer method, and the like, and then exposed and developed to obtain a predetermined insulating layer 4. . Another method of photolithography is to form an insulating resin film on the entire surface of the magnetic substrate 2 by the spin method or the like, and then apply a photosensitive resist film to the surface of the insulating resin film, and expose, develop, I do. Next, after the portion of the insulating resin film exposed from the photosensitive resist film is etched to remove unnecessary portions of the insulating resin film, the photosensitive resist film is peeled off. Alternatively, the insulator film obtained by the spin method or the like is pierced and cut by a laser beam. Thus, the insulator layer 4 is formed on the surface of the magnetic substrate 2.
[0021]
Next, extraction electrodes 8 and 9 are provided on the surface of the insulator layer 4 by thin film forming means such as photolithography. That is, after a metal film is formed on the entire surface of the insulator layer 4 by plating, vapor deposition, sputtering, or the like, a photosensitive resist film is applied to the surface of the metal film, exposed, and developed. Next, after the portion of the metal film exposed from the photosensitive resist film is etched to remove an unnecessary portion of the metal film, the photosensitive resist film is removed. Thus, the extraction electrodes 8 and 9 are formed on the surface of the insulator layer 4 in the same step. Therefore, the structure of the via hole is somewhat complicated as compared with the case where the extraction electrodes are formed on the surfaces of different insulator layers, but the number of layers is reduced, the manufacturing process is simplified, and the manufacturing cost is reduced. Become cheap.
[0022]
Next, as shown in FIG. 6, the insulator layer 5 is formed by a thin film forming means such as photolithography. Via holes 15 and 16a are formed in the center of the insulator layer 5 so that one ends of the extraction electrodes 8 and 9 are exposed. Next, as shown in FIG. 7, a coil conductor 10 and an extraction electrode 12 are formed on the surface of the insulator layer 5 by thin film forming means such as photolithography. One end of the coil conductor 10 is in contact with and electrically connected to one end of the extraction electrode 8 via the via hole 15.
[0023]
Next, as shown in FIG. 8, the insulator layer 6 is formed by a thin film forming means such as photolithography. A via hole 16b is formed at the center of the insulator layer 6 so as to be connected to the via hole 16a, and one end of the extraction electrode 9 is exposed from the via hole 16b. Next, as shown in FIG. 9, the coil conductor 11 and the extraction electrode 13 are formed on the surface of the insulator layer 6 by thin film forming means such as photolithography. One end of the coil conductor 11 contacts and is electrically connected to one end of the extraction electrode 9 via the via holes 16a and 16b.
[0024]
In the case of the choke coil 1 of the present embodiment, a structure in which the coil conductors 10 and 11 substantially overlap in the thickness direction is employed. Here, the conductor widths of the coil conductors 10 and 11 may be set equal, but in this case, there is a concern about the withstand voltage reliability between the coil conductors 10 and 11. This is because, when the insulating layer 6 is formed, when the liquid insulating resin is applied to the uneven portion of the coil conductor 10, the insulating layer 6 at the edge portion tends to be locally thin. As shown in FIG. 10, if the coil conductors 10 and 11 are displaced, when a potential difference occurs between the coil conductors 10 and 11, the edge portion where the thickness of the insulator layer 6 is small and the electric field concentration occurs is generated. In this case, a short circuit between the coil conductors 10 and 11 easily occurs.
[0025]
Therefore, as a countermeasure, as shown in FIG. 11, the conductor width of the coil conductor 11 far from the magnetic substrate 2 is set to be smaller than the conductor width of the coil conductor 10 near the magnetic substrate 2. Specifically, assuming that the conductor widths of the coil conductors 10 and 11 are D ₁ and D ₂ , respectively, and the maximum misalignment dimension of the coil conductors 10 and 11 is P ₁ , the following relational expressions should be satisfied. preferable.
[0026]
D ₂ <D _1-2 P ₁
As a result, the coil conductor 11 is always disposed at a position away from the edge of the coil conductor 10 because the thickness of the insulator layer 6 is large. As a result, the insulation interval between the coil conductors 10 and 11 is not reduced, and there is no possibility that the withstand voltage is reduced.
Next, as shown in FIG. 12, the insulator layer 7 is formed by a thin film forming means such as the spin method. This insulator layer 7 needs to function as an adhesive between the laminate 14 and the magnetic substrate 3. The insulator layer 7 may have a function of insulating and bonding as a single layer, or may be a composite material such as an insulating layer, an adhesive layer, and a base material. As a material, a resin such as a polyimide resin, an epoxy resin, an acrylic resin, and a fluororesin, or glass, glass ceramic, inorganic cement, or the like can be used. In the present embodiment, a prepreg of polyimide resin is used for the insulator layer 7 in order to sufficiently secure the bonding strength between the laminate 14 and the magnetic substrate 3. In this method, a polyamide acid varnish or the like as a precursor of a polyimide resin is applied and then heated to remove volatile components and perform partial imidization. Alternatively, a prepreg sheet may be used. Next, as shown in FIG. 13, after placing the magnetic substrate 3 on the surface of the insulator layer 7, it is set on a vacuum hot press and thermocompression-bonded in vacuum. Thus, the choke coil 1 in which the magnetic substrates 2 and 3 and the laminate 14 are integrated without any bubbles inside the insulator layers 4 to 7 is obtained. In particular, the integration by vacuum hot pressing is suitable when a relatively brittle ferrite substrate is used as the magnetic substrates 2 and 3 or when a large-area mother substrate is used for efficient production.
[0027]
In the choke coil 1 thus obtained, since the laminated body 14 is formed on the surface of the magnetic substrate 2 by the thin film forming means, the laminated body 14 can be formed with high precision, and the choke coil 1 can be downsized. Can be. In addition, since the insulator layers 4 to 7, the coil conductors 10, 11, and the extraction electrodes 8, 9, 12, 13 constituting the laminated body 14 do not include a magnetic material, a choke coil having excellent magnetic coupling of a plurality of coils. 1 can be obtained.
[0028]
The common mode choke coil according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention.
As shown in FIG. 14, in the above embodiment, the insulator layer 4 provided with the lead electrodes 8 and 9 is disposed between the insulator layers 5 and 6 provided with the coil conductors 10 and 11, respectively. You may. In this case, the number of insulator layers is mostly two between the coils 10 and 11, and the insulation reliability is further improved. In the figure, reference numerals 28 and 29 indicate via holes.
[0029]
Further, in the above embodiment, the coil is constituted by one spiral coil conductor, but may be a helical coil in which a plurality of coil conductors are electrically connected in series via via holes. Further, the plurality of coils are not limited to the structure overlapping in the thickness direction, and may be a structure in which the coils are juxtaposed in a direction perpendicular to the thickness direction.
Alternatively, a laminate may be formed on both magnetic substrates and joined together.
[0030]
Further, when ferrite is used as the material of the magnetic substrate, the magnetic substrate may be porous. Further, when a polyimide resin or the like is used as a material of the insulator layer, the insulator layer may have water absorption. All of these undesirably reduce the reliability of the common mode choke coil . Therefore, a ferrite or a polyimide resin may be impregnated with a moisture-proofing agent (eg, resin or wax), or may be applied to the surface of the manufactured coil component while leaving the external electrode.
[0031]
【The invention's effect】
As is clear from the above description, according to the present invention, since the laminate does not include a magnetic material, the electromagnetic characteristics of a plurality of coils can be improved. Then, a laminated body composed of an insulator layer and a coil pattern can be formed on the first magnetic substrate with high accuracy by the thin film forming means, so that a small-sized common mode choke coil with high precision is produced. be able to.
[0032]
In addition, by providing one extraction electrode of each of the plurality of coils on the same insulator layer, the number of insulator layers can be reduced and the manufacturing process can be simplified. Further, when the extraction electrode is provided between the coil patterns in the thickness direction, the thickness of the insulator layer between the coil patterns is almost twice as large, and the insulation reliability is improved.
Further, in the coil pattern adjacent in the thickness direction, the conductor width of the coil pattern far from the first magnetic substrate is made narrower than the conductor width of the coil pattern near the first magnetic substrate, so that the adjacent coil pattern is temporarily provided. A common mode choke coil is obtained in which there is no concern that the withstand voltage between the coil patterns is reduced even if the patterns are displaced from each other.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an embodiment of a common mode choke coil according to the present invention.
FIG. 2 is a perspective view showing the appearance of the common mode choke coil shown in FIG.
FIG. 3 is a sectional view taken along the line III-III of FIG. 2;
FIG. 4 is an electric equivalent circuit diagram of the common mode choke coil shown in FIG.
FIG. 5 is an exemplary perspective view showing a procedure for manufacturing the common mode choke coil shown in FIG. 1;
FIG. 6 is a perspective view showing a manufacturing procedure following FIG. 5;
FIG. 7 is a perspective view showing a manufacturing procedure following FIG. 6;
FIG. 8 is a perspective view showing a manufacturing procedure following FIG. 7;
FIG. 9 is a perspective view showing a manufacturing procedure following FIG. 8;
FIG. 10 is a sectional view showing an example of a coil pattern adjacent in the thickness direction.
FIG. 11 is a sectional view showing another example of a coil pattern adjacent in the thickness direction.
FIG. 12 is a perspective view showing a manufacturing procedure following FIG. 9;
FIG. 13 is a perspective view showing a manufacturing procedure following FIG. 12;
FIG. 14 is an exploded perspective view showing another embodiment of the common mode choke coil according to the present invention.
FIG. 15 is a perspective view showing a conventional example.
FIG. 16 is a sectional view showing another conventional example.
FIG. 17 is a sectional view showing still another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Common mode choke coil 2, 3 ... Magnetic substrate 4, 5, 6, 7 ... Insulator layer 8, 9 ... Leader electrodes 10, 11 ... Coil conductors 12, 13 ... Leader electrode 14 ... Laminate

Claims (3)

A first magnetic substrate,
A laminate formed by stacking an insulator layer made of a nonmagnetic layer, a coil pattern, and an extraction electrode in a thickness direction, formed on the surface of the first magnetic substrate by a thin film forming means;
A second magnetic substrate sandwiching the laminate between the first magnetic substrate,
An external electrode provided on an end face of a laminated structure including the first magnetic substrate, the laminated body, and the second magnetic substrate;
The coil pattern constitutes at least two coils, and the coils are covered with an insulator of the insulator layer,
Each of the coils is disposed in the insulator in a direction perpendicular to the thickness direction of the insulator layer , and the first magnetic substrate and the first magnetic substrate are provided through the lead electrodes formed by being covered with the insulator. Being electrically connected to the external electrode without penetrating the second magnetic substrate;
A common mode choke coil characterized by the following. 2. The common mode choke coil according to claim 1 , wherein one extraction electrode of each of the plurality of coils is provided on the same insulator layer. The coil width of a coil pattern which is substantially overlapped and adjacent in the thickness direction and which is far from the first magnetic substrate is smaller than the conductor width of a coil pattern which is close to the first magnetic substrate. 2. The common mode choke coil according to 1 .

Images