JP2006310716A - Planar coil element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin, planar coil element having a high inductance. <P>SOLUTION: Since a resin layer 33 contains a magnetic substance, the planar coil element is thinner than that employing a sintered core. Magnetic flux Φ, leaking from the inside to the outside of a conductor pattern 34, passes through the magnetic substance in the resin layer 33. Since two resin layers 33 are spaced apart through a gap "g" in the thickness direction in the fringe region Q of the conductor pattern 34, magnetic saturation of a magnetic circuit due to the magnetic flux is suppressed, and the inductance can be enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a planar coil element.

  2. Description of the Related Art Conventionally, surface mount type planar coil elements have been widely used in electrical products such as consumer equipment and industrial equipment. In particular, in small portable devices, as functions are enhanced, it is necessary to obtain a plurality of voltages from a single power source in order to drive each device. Therefore, surface mount type planar coil elements are also used for such power supply applications. As requirements for use in small portable devices, etc., electrical insulation and reliability, ultra miniaturization, and cost reduction are emphasized, and therefore a planar coil structure that applies printed circuit circuit technology and semiconductor circuit technology is proposed. Has been.

  The coil of the following Patent Document 1 is formed by abutting two magnetic cores on the front and back surfaces of an insulating plate having an outer shell portion and a central leg portion closed at both ends, and a through hole in the central portion. A spiral coil conductor is formed, and a coil substrate in which the spiral coil conductors on the front and back surfaces are connected to each other through front and back contact portions, and an external electrode connected to the coil conductor is provided. In a state where the central leg portion enters the through hole, the coil substrate is disposed inside the core structure, and the magnetic core has a gap in the central leg portion.

  In the coil of Patent Document 1, a planar coil substrate is sandwiched between upper and lower ferrite cores. Although a sintered core is used as the ferrite core, sufficient strength cannot be obtained when the thickness of the sintered core is about 0.5 mm or less. The coil element is required to be thin, but this sandwich structure is difficult to cope with. That is, in order to further reduce the size and thickness of the coil element, it is necessary to increase the integration (high density) of the coil conductor. There is a limit.

  Therefore, a coil having the structure of Patent Document 2 below is also considered. The coil of Patent Document 2 is configured such that a coil pattern formed by printed wiring technology is provided on an insulating substrate, and an electroplating layer by electroplating is provided on the coil pattern to reinforce the coil pattern. is there.

  The coil of Patent Document 2 is formed by forming a coil pattern on an insulating substrate by application of printed circuit board circuit technology and semiconductor circuit technology. Especially in miniaturization, the coil is made thinner than a conventional winding structure. There are advantages such as low variation in electrical characteristics and product dimensions, and reduction in cost by mass production. However, a sufficient inductance value cannot be obtained.

  From the viewpoint of thickness reduction, a coil disclosed in Patent Document 3 below is known. The coil of Patent Document 3 includes a planar magnetic element having a planar coil on the surface of the first ferrite magnetic film, a second ferrite magnetic film formed thereon, and an external electrode electrically connected to the planar coil. In this case, one or both of the first and second ferrite magnetic films are formed by fixing ferrite magnetic powder with a resin binder.

Since the coil of Patent Document 3 uses a ferrite magnetic film in which a ferrite magnetic powder is mixed in a resin binder instead of a sintered core, it can be thinned while maintaining an inductance value.
JP 2004-349468 A JP-A-7-142354 JP 2001-244124 A

  However, in the coil structure of Patent Document 3, when a DC bias current is applied, magnetic saturation occurs and the inductance value decreases. For this reason, in the coil structure of Patent Document 3, it is difficult to improve the inductance value.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a flat coil element that is thin and has high inductance.

  In order to solve the above-described problem, a first planar coil element includes a nonmagnetic insulating substrate having an opening, a first conductor pattern for a planar coil provided on one surface of the insulating substrate, and a first conductor pattern. And a second magnetic layer provided on the other surface of the insulating substrate, the first and second magnetic layers contain a magnetic material, are connected through an opening, and The outer edge region of the first conductor pattern is spaced apart with a gap in the thickness direction.

  In this case, since the magnetic layer contains a magnetic material, the magnetic layer is thin, but the magnetic flux that goes from the inside to the outside of the conductor pattern passes through the magnetic body. Here, since the two magnetic layers are separated from each other with a gap in the thickness direction in the outer edge region of the first conductor pattern, magnetic saturation of the magnetic circuit due to the magnetic flux is suppressed, and when a DC bias current is applied. The inductance can be increased.

  The second planar coil element further includes a second conductor pattern for a planar coil provided on the other surface of the insulating base so as to be covered with the second magnetic layer, and the first and second via the openings. The conductor patterns are electrically connected.

  In this case, the density of magnetic flux passing through the opening can be increased by connecting the two conductor patterns.

  The third planar coil element is characterized in that a resin layer not containing a magnetic material is formed on the first magnetic layer. In this case, since the first magnetic layer is protected by the layer, deterioration and oxidation of the magnetic body of the first magnetic layer can be suppressed.

  The fourth planar coil element is characterized in that a resin layer not containing a magnetic material is formed on the second magnetic layer. In this case, since the second magnetic layer is protected by the layer, deterioration and oxidation of the magnetic body of the second magnetic layer can be suppressed.

  The fifth planar coil element includes a resin layer that is interposed between the first conductor pattern and the first magnetic layer and does not contain a magnetic substance. In this case, since the AC resistance and capacitance between the conductors constituting the first conductor pattern can be controlled independently of the magnetic substance content rate, the resin material not including the magnetic substance is not obstructed by the magnetic substance. Since it can enter between conductors, a highly accurate planar coil element can be provided.

  The sixth planar coil element includes a resin layer that is interposed between the second conductor pattern and the second magnetic layer and does not contain a magnetic substance. In this case, since the AC resistance and capacitance between the conductors constituting the second conductor pattern can be controlled independently of the magnetic substance content rate, the resin material not including the magnetic substance is not disturbed by the magnetic substance. Since it can enter between conductors, a highly accurate planar coil element can be provided.

  In the seventh planar coil element, the first and / or second conductor pattern includes a Cu treatment layer in which a roughening treatment or an oxidation treatment is performed on a copper surface. In this case, the adhesive strength between the resin layer and the Cu treatment layer can be increased, and the reliability of the element is improved.

  The eighth planar coil element is characterized in that the first and / or second magnetic layer is a resin layer containing a magnetic material. In this case, the first and / or second magnetic layer can be easily formed.

  The tenth planar coil element is characterized in that the first and / or second magnetic layer includes ferrite as a magnetic material and is formed by a fine powder spraying method. In this case, the first and / or second magnetic layer can be easily formed and the inductance can be further increased.

  The planar coil element of the present invention is thin and has high inductance.

  Hereinafter, the planar coil element according to the embodiment will be described. In addition, the same code | symbol is attached | subjected to the same part and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view of the coil substrate 30.

  A coil substrate 100 (planar coil element) is formed by coating the coil substrate 30 with a resin material such as an epoxy resin.

  First, an XYZ rectangular coordinate system is set as shown in the figure. The cross-sectional shape of the coil substrate 30 in the XY plane is a quadrangle with a side of several mm. When the thickness direction of the coil substrate 30 is the Z direction, an external terminal (not shown) is provided on a plane parallel to the XZ plane.

  The coil substrate 30 includes a non-magnetic insulating plate (insulating base) 31 having a circular opening 35 in the center portion, a first conductor pattern 34 for a planar coil provided on one surface of the insulating plate 31, and an insulating plate. A planar coil second conductor pattern 34 provided on the other surface of 31 is provided, and the first and second conductor patterns 34 are electrically connected through an opening 35.

  A spiral planar coil 34 formed of a conductive material is disposed so as to surround a circular opening 35. The first and second planar coils 34 are formed on both surfaces of the coil substrate 30 and are electrically connected to the lead-out end electrodes 32, respectively. Each coil 34 spirally extends from the vicinity of the circular opening 35 toward the outside.

  When viewed from the direction facing the coil exposed surface, the planar coil 34 on one side forms a left-handed spiral along the direction toward the outer side, and the planar coil 34 on the other side also looks from the direction facing the coil exposed surface. As seen, when a left-handed spiral is formed along the outward direction, these central portions are electrically connected and overlapped, and when current flows in one direction, the rotational direction in which the current flows is the same Is set to That is, the magnetic fluxes generated by the two planar coils 34 are superimposed and strengthened.

  The lead-out end electrode 32 connected to the planar coil 34 formed on one surface of the coil substrate 30 and the lead-out end electrode 32 connected to the planar coil 34 formed on the other surface are respectively coil substrates. It is provided on 30 opposite sides. The planar coils 34 provided on both surfaces of the coil substrate 30 are electrically connected to each other by front and back contact portions 36 formed at the peripheral edge of the circular opening 35. The front and back contact portions 36 penetrate the insulating plate 31 in the thickness direction.

  Therefore, when a voltage is applied between the lead-out end electrode 32 provided on one side of the coil substrate 30 and the lead-out end electrode 32 provided on the other side, it is formed on one surface of the coil substrate 30. A current flows from the coil 34 that is formed to the coil 34 that is formed on the other surface.

  A resin material containing a magnetic material such as iron, nickel, or ferrite is located in the circular opening 35 of the coil substrate 30.

  Next, a method for manufacturing the coil substrate 30 will be described with reference to FIGS.

  2 and 3 are views for explaining a method of manufacturing the coil substrate 30, and illustrate a longitudinal section (XZ plane) of a portion corresponding to a part of the coil substrate 30.

  First, the insulating plate 31 is prepared (see FIG. 2A). This insulating plate 31 has a thickness of 60 μm, and glass cloth is impregnated with cyanate resin (BT (bismaleimide / triazine) resin: registered trademark), and a circular opening 35 is already formed. (Not shown in FIG. 2). In addition to BT resin, polyimide, aramid, etc. can also be used. In addition, a resin having a dielectric constant of 7 or less is selected in order to avoid an increase in stray capacitance. Ceramic can also be used as the material of the insulating plate 31. Glass can also be used as the material of the insulating plate 31. The material of the insulating plate 31 is preferably a mass-produced printed board material, and particularly preferably a resin material used for a BT printed board, FR4 printed board, or FR5 printed board.

  Subsequently, the base layer 60 is simultaneously formed on the front and back surfaces of the insulating plate 31 by electroless plating (see FIG. 2B).

  Next, a photoresist layer 61 (resist layer) is simultaneously electrodeposited on each of the underlying layers 61 formed simultaneously on the front and back surfaces of the insulating plate 31 (see FIG. 2C). In the photoresist layer 61 formed on the front surface and the back surface, exposure is performed for each surface of the front surface and the back surface by photolithography along the pattern for forming the coil conductor 34 (see FIG. 1). Development is performed to form a removal portion 611 (see FIG. 2D).

  Using the photoresist layer 61 thus patterned as a plating mask, a portion corresponding to the removal portion 611 in FIG. 2D is selectively subjected to electrolytic plating to simultaneously coat both the front and back surfaces of the coil conductor plating layer 62 ( First electroplating layer) is formed (see FIG. 3A).

  FIG. 4 is a configuration diagram of a film forming apparatus 8 used when forming an electrolytic plating film.

  The film forming apparatus 8 has a liquid tank 81, and a plating solution is placed in the liquid tank 81. A plating jig 82 for holding a wafer 83 on which an electrolytic plating film is formed is disposed in the liquid tank 81. The plating jig 82 is provided with a jig shielding plate 821 to shield the outer peripheral portion of the wafer 83. A pair of anodes 84 is provided so as to sandwich the plating jig 82. An outer shielding plate 85 and a stirring grid 86 are provided between the plating jig 82 and the pair of anodes 84, respectively. Since a predetermined voltage is applied between the plating jig 82 and the pair of anodes 84, it is possible to simultaneously perform plating on both surfaces of the wafer 83 attached to the plating jig 82.

  In this way, for example, a Cu conductor pattern (conductor line) having a height of 20 μm, a width of 70 μm, and a gap of 30 μm can be formed. The “height” and “width” are the height and width of the Cu conductor pattern, and the gap here is the distance between adjacent Cu conductor patterns.

  After the coil conductor plating layer 62 is formed, the photoresist layer 61 as a plating mask is peeled and removed simultaneously on both the front and back surfaces (see FIG. 3B).

  From the state shown in FIG. 3B, the base layer 60 other than the portion where the coil conductor plating layer 62 is formed is removed by etching, and the base portion 60a is removed from the coil conductor plating layer 62, the insulating plate 31, and the like. (See FIG. 3C).

  Thereafter, without the selective plating mask, the second electrolytic plating is simultaneously performed on both sides using the apparatus shown in FIG. 4, and the coil conductor plating layer 62 is further grown and formed by electrodeposition (see FIG. 3D). For example, a Cu conductor pattern having a height of 80 to 100 μm, a width of 80 to 85 μm, and a gap of 15 μm is formed on both sides simultaneously. There are several examples of numerical values, for example, a conductor pattern having a height of 35 μm and a width of 35 μm is produced by the first plating process, and a conductor pattern having a height of 75 μm and a width of 65 μm is produced by the second plating process. is there.

  Thereby, a sufficiently thick conductor portion as the planar coil 34 is obtained. The planar coil 34 can be grown and formed at a high density until the gap G between adjacent coil conductors is 15 μm or less. This is because the plating layer is formed in proportion to the amount of electricity in the height direction, but the rate at which the plating layer is formed becomes slower as the gap becomes narrower in the width (gap G) direction. by.

  Thus, the coil substrate 30 has the planar coil 34 in which the electroplating layer 62 is grown at a high density until the gap G between the adjacent planar coils 34 becomes 15 μm or less. Moreover, since the aspect ratio of the coil conductor (height / width of the planar coil 34) can be set as high as about 0.2 to 5, the direct current resistance can be reduced to about 0.01 to 10 ohms. . It is difficult for a small coil to make the DC resistance less than 0.01 ohm, and if it exceeds 10 ohm, heat generation of the conductor becomes a problem. When the aspect ratio is less than 2, the DC resistance of the coil conductor is increased, and when it exceeds 5, the electroplating time is increased.

  After the formation of the coil conductor plating layer 62 is completed, after the planar coil 34 has been formed on both surfaces of the insulating plate 31, the top surface of the planar coil 34 is polished to remove the excess portion 34K, and the planar coil 34 Make the in-plane height uniform. The height uniformity is performed so that the maximum deviation from the average value is 10% or less.

  Next, the surface Cu on which the Cu conductor pattern is formed is treated to form a Cu treatment layer 34a. The Cu treatment layer 34a is formed by a roughening treatment in which irregularities (for example, 5 μm to 7 μm) are provided on the copper surface, or an oxidation treatment in which an oxide film is provided on the copper surface. Moreover, you may use a roughening process and an oxidation process together. The adhesive strength with the resin 33 is improved by the Cu treatment layer 34a. In addition, the resin 33 easily enters between the lines of the Cu conductor.

  Next, the protective resin layer 33 (solder resist) is printed on both surfaces of the insulating plate 31, and the planar resin 34 is covered and protected by the protective resin layer 33 to complete the coil base material 100 including the coil substrate 30. . Actually, in order to produce a plurality of coils at a time, a wafer (coil substrate assembly) in which coil conductors of a spiral pattern are aligned is produced. Further, Cr and Cu are continuously formed on the solder resist by a mask sputtering method, and an electrode is taken out from a predetermined spiral electrode portion.

  Each coil substrate is coated with an epoxy adhesive mixed with a magnetic material and cured in an atmosphere at 150 ° C. Thereafter, each element is fabricated by dicing into chips. In order to form external terminal electrodes to be user terminals for circuit connection, after barrel polishing, the Cu (leading end electrode portion) on the terminal surface is cleaned using both wet processing and dry processing, and mask sputtering is performed. Cr and Cu are continuously formed by the method. This is subjected to barrel plating of Cu, Ni, and Sn to form external terminal electrodes. Thereby, for example, a surface-mounted coil element having a product size of 3 mm long × 2.6 mm wide × 0.4 mm high can be produced. The external terminal electrode may be formed by applying a conductive paste such as Ag or Cu and effect processing.

  As described above, in the present embodiment, a protective resin layer 33 is formed on a wafer (insulating plate 31) in which a plurality of planar coils 34 are arranged so as to cover the planar coil 34, and the wafer ( A coil element is obtained by cutting the insulating plate 31). In the obtained coil element, the insulating plate 31 functions as a gap in the thickness direction in the outer edge region. When Cu is used as the coil conductor material and the resin substrate material used in the printed circuit board for electronic component integration is used as the insulating plate 31, a method for forming the protective resin layer 33 at a low temperature is required. The

  Next, the protective resin layer 33 that is a feature of the present invention will be described.

  FIG. 5 is a longitudinal sectional view of the coil substrate 100.

  In FIG. 5A, a protective resin layer 33 is provided around a coil substrate 30 in which planar coils 34 are provided on both surfaces of an insulating plate 31. A magnetic material (magnetic body) is mixed in the protective resin layer 33. Ferrite powder can be used as the magnetic material.

  Here, the resin layer 33 located on one side of the insulating substrate is referred to as a first resin layer, and the resin layer 33 located on the other side is referred to as a second resin layer. The planar coil element 100 includes a first resin layer (33) covering the first conductor pattern 34 for the planar coil provided on one surface of the insulating plate 31, and a first resin layer (33) provided on the other surface of the insulating plate 31. Two resin layers (33), the first and second resin layers (33) contain a magnetic material, are connected via openings 35 (see FIG. 1), and are outer edge regions of the first conductor pattern 34. In Q, they are separated with a gap “g” in the thickness direction. The gap “g” is the thickness of the insulating plate 31.

  In this case, since the resin layer 33 contains a magnetic material, the planar coil element is thinner than that using a sintered core, but the magnetic flux Φ (see FIG. 6) wraps around from the inside to the outside of the conductor pattern 34. ) Passes through the magnetic body in the resin layer 33. Here, since the two resin layers 33 are separated from each other with a gap “g” in the thickness direction in the outer edge region Q of the first conductor pattern 34, the magnetic saturation of the magnetic circuit due to the magnetic flux is suppressed, and the inductance is reduced. Can be high. The resin filled in the openings 35 belongs to the first resin layer 33 for convenience.

  As described above, the second conductor pattern 34 for the planar coil is provided on the other surface of the insulating plate 31 so as to be covered with the second resin layer 33, and the first and second conductors are provided through the openings 35. The pattern 34 is electrically connected. Therefore, the magnetic flux density passing through the opening 35 can be increased by connecting the two conductive patterns.

  Next, a modified example of the planar coil element will be described. In the following description, only differences from the planar coil element 100 will be described.

  In FIG. 5B, a protective resin layer 33 containing a magnetic material is provided around the coil substrate 30 in which the first conductor pattern 34 is provided only on one surface of the insulating plate 31.

  In FIG. 5C, the coil substrate 30 in which the conductor pattern 34 is provided on both surfaces of the insulating plate 31 is embedded in a protective resin layer 33x that does not contain a magnetic material, and the periphery of the protective resin layer 33x is made of a magnetic material. It is covered with the protective resin layer 33 contained.

  The planar coil element 100 includes a resin layer 33x that is interposed between the first conductor pattern 34 and the first resin layer 33 on one surface side and does not contain a magnetic substance. In this case, since the AC resistance and capacitance between the conductors constituting the first conductor pattern 34 can be controlled independently of the magnetic substance content rate, the resin layer (resin material) 33x not containing the magnetic substance is magnetic. Since it can enter between conductors without being obstructed by the body, a highly accurate planar coil element can be provided.

  The planar coil element 100 includes a resin layer 33x that is interposed between the second conductor pattern 34 on the other surface side and the second resin layer 33 and does not contain a magnetic substance. In this case, since the AC resistance and capacitance between the conductors constituting the second conductor pattern can be controlled independently of the magnetic substance content rate, the resin layer (resin material) 33x not containing the magnetic substance is a magnetic substance. Therefore, it is possible to provide a planar coil element with high accuracy.

  In FIG. 5D, the coil substrate 30 in which the conductor pattern 34 is provided on both surfaces of the insulating plate 31 is embedded in the protective resin layer 33x containing no magnetic material so that the top surface T of the coil is exposed. The periphery of the protective resin layer 33x is covered with a protective resin layer 33 containing a magnetic material.

  In FIG. 5E, the coil substrate 30 in which the conductor patterns 34 are provided on both surfaces of the insulating plate 31 is embedded in a protective resin layer 33 containing a magnetic material, and the protective resin layer 33 is surrounded by a magnetic material. It is covered with a protective resin layer 33y that does not contain.

  That is, the resin layer 33y not containing a magnetic material is formed on the first resin layer 33 on one side. In this case, since the first resin layer 33 is protected by the resin layer 33y, the deterioration and oxidation of the magnetic substance inside the first resin layer 33 can be suppressed. In addition, since the resin layer 33y not containing a magnetic material is formed on the second resin layer 33, and the second resin layer 33 is protected by the resin layer 33y, the deterioration of the magnetic material inside the second resin layer 33 or Oxidation can be suppressed.

  In FIG. 5F, the coil substrate 30 in which the conductor pattern 34 is provided on both surfaces of the insulating plate 31 is embedded in the protective resin layer 33, and the outer periphery of the conductor of the conductor pattern 34 is roughened or oxidized. A Cu treatment layer 34a is formed. A magnetic material is mixed in the protective resin layer 33.

  In the planar coil element 100, the first and / or second conductor pattern 34 includes a Cu treatment layer 34a on the surface of copper. In this case, the adhesive strength between the resin layer 33 and the Cu treatment layer 34a can be increased, and the reliability of the element is improved.

  In FIG. 5G, the coil substrate 30 in which the conductor pattern 34 is provided on both surfaces of the insulating plate 31 is roughened or oxidized on the outer periphery of the conductor, and is embedded in the protective resin layer 33x that does not contain a magnetic material. Has been. The periphery of the protective resin layer 33x is covered with a protective resin layer 33 containing a magnetic material, and the protective resin layer 33 is covered with a protective resin layer 33y containing no magnetic material.

  In the planar coil element 100, the first and / or second conductor pattern 34 includes a Cu treatment layer 34a on the surface of copper. In this case, the adhesive strength between the resin layer 33x and the Cu treatment layer 34a can be increased, and the reliability of the element is improved.

  In the embodiment described above, the first magnetic layer covering the conductor pattern 34 provided on one surface of the insulating plate 31 is the resin layer 33 (first resin layer) located on the one surface side of the insulating substrate, The second magnetic layer provided on the other surface of the insulating plate 31 is a resin layer 33 (second resin layer) located on the other surface side of the insulating plate 31. Thus, when the first magnetic layer is a resin layer containing a magnetic material, the first magnetic layer can be easily formed. Moreover, when the second magnetic layer is a resin layer containing a magnetic material, the second magnetic layer can be easily formed.

  In the embodiment described above, a resin layer containing a magnetic material is used as the magnetic layer, but the present invention is not limited to this. For example, instead of a resin layer containing a magnetic material, a magnetic layer containing ferrite as a magnetic material and formed by a fine powder spraying method may be used.

  The fine powder spraying method is a general term for a method of spraying fine powder onto a substrate at a high speed to coat a base, and can achieve a crystal layer having a large density and high magnetic properties at a low temperature. One of the fine powder spraying methods is the AD (aerosol deposition) method. The AD method is a method in which fine powders such as oxides are ejected from a nozzle by a carrier gas and solidified by impact on a substrate, and is suitable for a ferrite material.

  With reference to FIG. 7, the formation method of the magnetic layer using AD method is demonstrated. In the AD method, the ferrite powder in the aerosol chamber 103 is aerosolized by the vibration mechanism 102 to generate ferrite fine particles. The generated ferrite fine particles are transported at high speed using a carrier gas (for example, He gas) from the gas cylinder 101 using the pressure difference between the film forming chamber 107 and the aerosol chamber 103, and jetted from the nozzle 104 toward the substrate 105. To do. The pressure difference between the film forming chamber 107 and the aerosol chamber 103 is formed by a rotary pump 108. The ferrite fine particles are crystallized on the substrate 105 while being repeatedly crushed and deposited by the energy of jetting to form a magnetic layer. The substrate 105 is attached to a movable substrate holder 106. The AD method is described in IEEJ Transactions A (Basic, Materials, Common Category), Vol. 124 (2004) No. 10 pp.887-891.

  By using the above-described AD method, the first magnetic layer covering the conductor pattern 34 provided on one surface of the insulating plate 31 can be formed, and the first magnetic layer provided on the other surface of the insulating plate 31 can be formed. Two magnetic layers can be formed. Even in this case, the first and second magnetic layers contain the magnetic material, are connected through the opening of the insulating plate 31, and have a thickness in the outer edge region of the conductor pattern 34 provided on one surface of the insulating plate 31. Separated with a gap in the direction. The gap is the thickness of the insulating plate 31.

  Even when the magnetic layer is formed by using the AD method, the planar coil element is thinner than the one using the sintered core as in the above embodiment in which the magnetic layer is the resin layer 33. The magnetic flux Φ (see FIG. 6) that goes from the inside to the outside passes through the magnetic layer. Here, since the two magnetic layers are separated from each other with a gap in the thickness direction in the outer edge region Q of the first conductor pattern 34, magnetic saturation of the magnetic circuit due to the magnetic flux is suppressed, and the inductance is increased. Can do.

  As described above, the second conductor pattern 34 for the planar coil is provided on the other surface of the insulating plate 31 so as to be covered with the second magnetic layer, and the first and second conductor patterns via the opening 35. 34 is electrically connected. Therefore, the magnetic flux density passing through the opening 35 can be increased by connecting the two conductive patterns.

  According to the AD method, since a crystal layer having a high density and high magnetic properties can be achieved at a low temperature, a magnetic layer made of a thick ferrite film having a higher magnetic permeability than a magnetic layer made of a resin containing ferrite is used. Formation becomes possible. Therefore, the inductance can be further increased.

  Moreover, since the magnetic layer is formed by the AD method, a magnetic layer containing ferrite as a magnetic body can be easily formed.

  The first magnetic layer covering the conductor pattern 34 provided on one surface of the insulating plate 31 is a resin layer 33 (first resin layer), and the second magnetic layer provided on the other surface of the insulating plate 31 is AD. You may form by a method. Further, the first magnetic layer covering the conductor pattern 34 provided on one surface of the insulating plate 31 is formed by the AD method, and the second magnetic layer provided on the other surface of the insulating plate 31 is formed by the resin layer 33 ( The second resin layer may be used.

  The magnetic layer may be formed by a method other than the fine powder spraying method described above. For example, it may be formed by applying paste-like ferrite so as to cover the conductor pattern by a thick film method and then sintering. Moreover, you may form a magnetic layer using formation techniques, such as a compacting method, a plating method, and a spraying method. When forming the magnetic layer, it is necessary to consider the heat resistance of the insulating base or conductor pattern as a base. For the formation of the magnetic layer, it is preferable to employ a technique capable of forming the magnetic layer at a low temperature, such as the fine powder spraying method described above.

  Further, the coil element 30 may be configured by putting the coil substrate 30 in a small case made of ferrite or the like.

  The present invention can be used for planar coil elements.

3 is a plan view of a coil substrate 30. FIG. 6 is a diagram for explaining a method of manufacturing the coil substrate 30. FIG. 6 is a diagram for explaining a method of manufacturing the coil substrate 30. FIG. It is a block diagram of the film-forming apparatus 8 used when forming an electrolytic plating film. 1 is a longitudinal sectional view of a coil substrate 100. FIG. FIG. 3 is a view showing a vertical cross-sectional configuration of a coil base material 100. It is a figure for demonstrating AD method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 ... Coil board | substrate, 31 ... Insulating board, 32 ... Derived end electrode, 33 ... Protective resin layer, 34 ... Coil conductor, 36 ... Front and back contact part.

Claims (9)

A non-magnetic insulating substrate having an opening;
A first conductor pattern for a planar coil provided on one surface of the insulating substrate;
A first magnetic layer covering the first conductor pattern;
A second magnetic layer provided on the other surface of the insulating substrate;
With
The first and second magnetic layers contain a magnetic material, are connected through the opening, and are separated from each other with a gap in the thickness direction in an outer edge region of the first conductor pattern. Planar coil element.   A second conductor pattern for a planar coil provided on the other surface of the insulating base so as to be covered with the second magnetic layer is further provided, and the first and second conductor patterns are formed through the openings. The planar coil element according to claim 1, wherein the planar coil element is electrically connected.   The planar coil element according to claim 1, wherein a resin layer not containing a magnetic material is formed on the first magnetic layer.   4. The planar coil element according to claim 2, wherein a resin layer not containing a magnetic material is formed on the second magnetic layer.   5. The planar coil element according to claim 1, further comprising a resin layer interposed between the first conductor pattern and the first magnetic layer and containing no magnetic substance. 6.   6. The planar coil element according to claim 2, further comprising a resin layer that is interposed between the second conductor pattern and the second magnetic layer and does not contain a magnetic substance.   6. The planar coil element according to claim 2, wherein the first and / or second conductor pattern includes a Cu treatment layer that has been subjected to a roughening treatment or an oxidation treatment on a surface of copper. .   The planar coil element according to any one of claims 1 to 7, wherein the first and / or second magnetic layer is a resin layer containing a magnetic substance. The planar coil element according to any one of claims 1 to 7, wherein the first and / or second magnetic layer includes ferrite as a magnetic material and is formed by a fine powder spraying method.

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