JP5621573B2 - Coil built-in board - Google Patents

Description

  The present invention relates to a coil built-in substrate, and more particularly to a coil built-in substrate in which a coil is built in a substrate.

  Circuit components such as semiconductor integrated circuits, capacitors, and resistors are mounted on a coil-embedded substrate produced by alternately laminating insulating layers containing ceramic materials and internal conductor layers and firing the integrated laminate. Module parts are used in mobile phones.

  It has been proposed to provide a gap inside the substrate for the coil-embedded substrate.

  For example, in Patent Document 1, as shown in the sectional view of FIG. 8A and the enlarged sectional view of FIG. 8B, a gap 140 is formed between the coil electrodes 130 in the multilayer body 110 of the multilayer electronic component. In this case, the number of the gaps 140 should be ½ or more of the number of layers of the coil electrode 130, and the width a of the gap 140 in the stacking direction and the distance b between the coil electrodes 130 adjacent to each other in the stacking direction It is disclosed that the ratio is 0 <a / b ≦ 1/2. The reason for 0 <a / b is to develop a stress relaxation effect, and the reason for a / b ≦ 1/2 is to develop a crack prevention effect.

  Patent Document 2 discloses that the formation of irregularities on the surface of the laminated body is suppressed by alternately laminating inner and outer coils having different sizes as compared with a case where coils having the same diameter are arranged in a straight line. Has been.

JP 2006-352018 A International Publication No. 2009/081865

  As in Patent Document 2, when the formation of irregularities on the surface of the laminate is suppressed by alternately laminating inner and outer coils having different sizes, stress is reduced and the magnetic characteristics of the coil are improved. It is not clear how to provide a gap that can be used.

  In view of such circumstances, the present invention clarifies a void structure that reduces stress and effectively improves magnetic characteristics of a coil in a coil-embedded substrate in which inner and outer coils having different sizes are alternately stacked. For the purpose.

  In order to solve the above problems, the present invention provides a coil built-in substrate configured as follows.

The coil-embedded substrate is respectively disposed between (a) a substrate body on which a plurality of insulating layers containing a ceramic material are laminated, and (b) a different set of the insulating layers adjacent to each other. A plurality of coil elements formed around a virtual central axis extending in the stacking direction in which the insulating layers are stacked; and (c) an interlayer connection conductor that connects the coil elements through the insulating layer; (D) at least one gap portion formed inside the substrate body. The coil element includes first and second coil elements having a constant line width. The first coil elements overlap each other when viewed in the stacking direction. When the second coil element is seen through in the stacking direction, the first coil element is in contact with and overlaps the inner periphery inside the outer periphery of the outer coil region where the first coil elements overlap each other. The first and second gaps extend in an annular shape between the inner periphery of the inner coil region and the outer periphery of the outer coil region where the second coil elements overlap each other when seen in the stacking direction. One of the coil elements is disposed between at least one of the two coil elements, the one insulating layer in contact with the coil element, and the other insulating layer facing the coil element. The part is formed so as to be exposed to the gap part. When the line width of the first and second coil elements is A and the width of the gap is B, 1.5 ≦ B / A ≦ 2.0. The number of the gaps is less than half of the total number of the first coil elements and the second coil elements.

  In the above configuration, the outer coil region where the first coil elements overlap each other and the inner coil region where the second coil elements overlap each other are in contact with each other when seen in the stacking direction. Since the outer coil region and the inner coil region do not overlap each other, it is possible to suppress the formation of irregularities on the front and back surfaces of the substrate body as compared to the case where all the coil elements overlap when viewed in the stacking direction. Moreover, since the residual stress accompanying firing shrinkage is relieved by the gap formed between the coil element and the insulating layer, the efficiency of the coil is improved.

  When the gap is formed outside the outer periphery of the outer coil area when seen through in the stacking direction, a crack starting from the gap occurs when the collective substrate is folded to divide the pieces from the collective substrate. Cheap. However, when the gap portion is seen through in the stacking direction as in the present invention, if the gap extends inward from the outer periphery of the outer coil region, cracks are unlikely to occur, so that break failures and cracks are unlikely to occur.

  When viewed through in the stacking direction, the L value of the coil decreases when a gap is formed inside the inner periphery of the inner coil region. However, the L value of the coil does not decrease when the gap extends outside the inner periphery of the inner coil region as seen in the stacking direction as in the present invention.

  When the coil element is exposed in the gap portion, the residual stress of the coil element is more relaxed than when the coil element is not exposed in the gap portion. It can be made difficult to occur.

  Since the width B of the gap is 1.5 times or more the line width A of the first and second coil elements, when viewed in the stacking direction, the gap is more than half of the outer coil area and the inner coil area. It overlaps with more than half. Therefore, the residual stress can be sufficiently relaxed for both the first coil element and the second coil element, and the efficiency of the coil can be improved.

  If the number of gaps is less than half of the total number of the first coil elements and the second coil elements, for example, the gaps and the first and second coil elements are alternately arranged in the stacking direction. And the residual stress of the 2nd coil element can be eased efficiently.

  Preferably, the insulating layer of the substrate body includes (a) first and second magnetic ferrite layers containing a magnetic ceramic material, and (b) between the first and second magnetic ferrite layers. And an intermediate non-magnetic ferrite layer disposed adjacent to the first and second magnetic ferrite layers.

  In this case, the direct current superimposition characteristic is improved by providing the intermediate non-magnetic ferrite layer between the first and second magnetic ferrite layers.

  Preferably, the insulating layer of the substrate body is disposed adjacent to the first magnetic ferrite layer on the opposite side of the intermediate magnetic non-magnetic ferrite layer of the first magnetic ferrite layer. A first non-magnetic ferrite layer having a thermal expansion coefficient smaller than that of the first magnetic ferrite layer; and (d) the intermediate non-magnetic ferrite layer of the second magnetic ferrite layer. A second non-magnetic ferrite layer disposed adjacent to the second magnetic ferrite layer on the opposite side of the first magnetic ferrite layer and having a thermal expansion coefficient smaller than that of the second magnetic ferrite layer. In addition.

  By sandwiching the first and second magnetic ferrite layers between the first and second nonmagnetic ferrite layers, the strength of the substrate body is improved. Since the spread of the magnetic field is suppressed by the first and second non-magnetic ferrite layers, noise induced on the front and back surfaces of the substrate body and the wiring and terminal electrodes provided in the vicinity thereof is reduced.

  According to the present invention, even if voids are formed, break failures and cracks are not likely to occur.

It is sectional drawing of a coil built-in board | substrate. Example 1 It is an exploded plan view of a coil built-in substrate. Example 1 It is a principal part enlarged view of the intermediate | middle layer of a coil built-in board | substrate. Example 1 It is a graph of the number of void layers and conversion efficiency. (Production Example 1) It is a graph of the amount of protrusion outside the air gap and the conversion efficiency. (Production Example 2) It is a graph of the amount of protrusion inside a space | gap and conversion efficiency. (Production Example 3) It is a graph of a space | gap introduction position and conversion efficiency. (Production Example 4) It is (a) sectional drawing of a laminated type electronic component, (b) It is an expanded sectional view. (Conventional example 1)

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  Example 1 A coil-embedded substrate 10 of Example 1 will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view of the coil-embedded substrate 10. As shown in FIG. 1, the coil-embedded substrate 10 has a coil 30, an in-plane wiring conductor 22, and an interlayer connection conductor 24 formed inside the substrate body 12. The coil-embedded substrate 10 is a piece obtained by cutting and dividing a collective substrate including a portion to be a plurality of substrate bodies 12 along a break groove.

  The substrate body 12 includes a first non-magnetic ferrite layer 16a, a first magnetic ferrite layer 14a, an intermediate non-magnetic ferrite layer 16c, a second magnetic ferrite layer 14b, The non-magnetic ferrite layer 16b is laminated. The first and second magnetic ferrite layers 14a and 14b include a magnetic ceramic material, for example, a magnetic ferrite mainly composed of iron oxide, zinc oxide, nickel oxide, and copper oxide, and a ceramic material. The first and second non-magnetic ferrite layers 16a and 16b and the intermediate non-magnetic ferrite layer 16c include, for example, non-magnetic ferrite and ceramic materials mainly composed of iron oxide, zinc oxide, and copper oxide. Each layer 14a, 14b, 16a, 16b, 16c of the substrate body 12 is made of an insulating layer including one layer or two or more laminated ceramic materials. The thermal expansion coefficients of the first and second nonmagnetic ferrite layers 16a and 16b and the intermediate nonmagnetic ferrite layer 16c are smaller than the thermal expansion coefficients of the first and second magnetic ferrite layers 14a and 14b.

  The coil 30 includes first coil elements 32a to 32d and second coil elements 34a to 34d. The coil elements 32a to 32d and 34a to 34d are formed with a constant line width inside the first and second magnetic ferrite layers 14a and 14b and the intermediate nonmagnetic ferrite layer 16c.

  The first coil elements 32a to 32d and the second coil elements 34a to 34d are respectively disposed between different insulating layers of adjacent insulating layers. The first coil elements 32a to 32d and the second coil elements 34a to 34d are alternately formed in the stacking direction. The first coil element 32a and the second coil element 34d at both ends in the stacking direction are connected to the land electrodes 26a and 26b and the terminal electrode 28 via an interlayer connection conductor and an in-plane wiring conductor (not shown).

  Although the intermediate nonmagnetic ferrite layer 16c may be eliminated, when the intermediate nonmagnetic ferrite layer 16c is formed between the first and second magnetic ferrite layers 14a and 14b, the DC superimposition of the coil 30 is achieved. Improved characteristics.

  Although the first and second non-magnetic ferrite layers 16a and 16b can be eliminated, the first and second magnetic expansion coefficients smaller than the thermal expansion coefficients of the first and second magnetic ferrite layers 14a and 14b are possible. The nonmagnetic ferrite layers 16a and 16b are provided, and the first and second magnetic ferrite layers 14a and 14b are sandwiched between the first and second nonmagnetic ferrite layers 16a and 16b. Will improve. Since the spread of the magnetic field is suppressed by the first and second non-magnetic ferrite layers 16a and 16b, noise induced on the front and back surfaces of the substrate body 12 and wiring and terminal electrodes provided in the vicinity thereof is reduced.

  Land electrodes 26 a and 26 b for mounting the electronic components 2 and 4 are formed on the upper surface 12 a of the substrate body 12. A terminal electrode 28 for mounting the coil built-in substrate 10 on another circuit board or the like is formed on the lower surface 12 b of the substrate body 12. If there is no component mounted on the upper surface 12a of the substrate body 12, the land electrode can be eliminated.

  FIG. 2 is an exploded plan view of the coil-embedded substrate 10. As shown in FIG. 2, the coil-embedded substrate 10 is formed with a conductive pattern with a solid diagonal line formed on the insulating layers 12 m,..., 12 p to 12 t,. Has been. Further, interlayer connection conductors 24p to 24t penetrating the insulating layers 12p to 12t are formed. In FIG. 2, illustration of interlayer connection conductors penetrating the insulating layer other than the interlayer connection conductors 24p to 24t is omitted. Also, illustration of an insulating layer on which the first coil element 32a and the second coils 34a and 34d are formed is omitted.

  The first coil elements 32a to 32d and the second coil elements 34a to 34d are alternately connected via interlayer connection conductors. For example, as shown in FIG. 2, one end 34p, 34s side of the second coil elements 34b, 34c on the insulating layers 12q, 12s and one end 32q, first coil elements 32b, 32c on the insulating layers 12p, 12r. The 32t side is connected by interlayer connection conductors 24p and 24r penetrating the insulating layers 12p and 12r. The other end 34q, 34t side of the second coil elements 34b, 34c on the insulating layers 12q, 12s and the other end 32s, 32u side of the first coil elements 32c, 32d on the insulating layers 12r, 12t are insulated. They are connected by interlayer connection conductors 24q and 24s penetrating the layers 12q and 12s.

  As shown in FIG. 2, the first and second coil elements 32 a to 32 d and 34 a to 34 d are virtual centers extending in the stacking direction in which the insulating layers of the substrate body 12 are stacked (the direction perpendicular to the paper in FIG. 2). It is formed in a substantially ring shape or a substantially C shape so as to extend substantially around the shaft 38 in the circumferential direction. The first coil elements 32a to 32d have substantially the same shape, are concentrically arranged, and, when viewed in the stacking direction, overlap each other while shifting the angle, and have an annular outer coil region 32 having a relatively large outer diameter (FIG. 1). Reference).

  The second coil elements 34a to 34d are also substantially the same shape, are concentrically arranged, and when viewed in the stacking direction, overlap each other while shifting the angle, and the annular inner coil region 34 (FIG. 1) having a relatively small outer diameter. Reference).

  As shown in FIG. 1, when viewed in the stacking direction, the inner periphery of the outer coil region 32 where the first coil elements 32 a to 32 d overlap each other and the outer periphery of the inner coil region 34 where the second coil elements 34 a to 34 d overlap each other. Is touching. Therefore, since the first coil elements 32a to 32d and the second coil elements 34a to 34d do not overlap in the stacking direction, the upper surface 12a and the lower surface of the substrate body 12 are compared to the case where all the coil elements overlap in the stacking direction. It is possible to suppress the formation of irregularities of 12b.

  Inside the substrate body 12, a gap 40 is formed along the second coil elements 34 b and 34 c so as to extend annularly around the virtual central axis 38 when seen in the stacking direction. The gap 40 includes one insulating layer in contact with the second coil elements 34b and 34c and the second coil elements 34b and 34c, and another insulating layer facing the second coil elements 34b and 34c. Are formed such that the entire lower surface of the second coil elements 34b, 34c is exposed.

  The gap 40 extends from the inner periphery of the inner coil region 34 to the outer coil region 32 through the outer periphery of the inner coil region 34 when viewed in the stacking direction. The first coil elements 32b and 32c and 32c and 32d facing each other extend to an intermediate position in the stacking direction.

  By the gap 40, not only the second coil elements 34a to 34d but also the residual stresses of the first coil elements 32a to 34d are alleviated, and the efficiency of the coil is improved. In other words, the gap 40 is formed also in the insulating layer between the first coil elements 32b and 32c and 32c and 32d beyond the second coil elements 34b and 34c, so that the gap is the first coil element. Compared with the case where the insulating layer is not formed between the insulating layers between 32b and 32c and 32c and 32d, the residual stress is more relaxed and the efficiency of the coil is further improved.

  When the gap is formed outside the outer periphery of the outer coil region 32 as seen through in the stacking direction, cracks originating from the gap are generated when the collective substrate is bent to divide the pieces from the collective substrate. Likely to happen. Therefore, the gap 40 is formed inside the outer periphery of the outer coil region when seen through in the stacking direction. That is, when the line width of the first coil elements 32a to 32d and the second coils 34a to 34d is A and the width of the gap is B, the gap 40 is formed so that A / B ≦ 2.0. Has been.

  The gap 40 is formed in an annular shape so as to overlap the second coil elements 34b and 34c and to protrude outside the second coil elements 34b and 34c, as shown in the enlarged views of the main part in FIGS. The void forming material 36 such as the carbon paste thus formed is formed by disappearing during firing. In FIG. 3, the broken line indicates the first coil element 32 b seen through in the stacking direction. The air gap forming material 36 is formed so as to overlap with an area of at least half of the inner peripheral side of the first coil element 32b.

  Next, a manufacturing process when the coil-embedded substrate 10 is manufactured in a collective substrate state will be described.

  (1) First, in order to form each layer of the substrate body 12 and a constraining layer (not shown), an unsintered ceramic green sheet containing a ceramic material powder and formed into a sheet shape is prepared.

  For the ceramic green sheets for forming the first and second magnetic ferrite layers 14a and 14b, for example, magnetic ferrite mainly composed of iron oxide, zinc oxide, nickel oxide and copper oxide is used. The ceramic green sheet for forming the first and second non-magnetic ferrite layers 16a and 16b and the intermediate non-magnetic ferrite layer 16c is, for example, non-magnetic mainly composed of iron oxide, zinc oxide and copper oxide. Body ferrite is used.

  As shown in FIG. 2, a through hole is formed in an appropriate position of each layer 12p to 12t of the ceramic green sheet by laser processing, punching processing, or the like, and a conductor paste is embedded in the through hole by printing or the like, thereby providing an interlayer connection conductor 24p. ~ 24t are formed.

  Further, a solid line is printed on one main surface of each layer 12m, 12p to 12t, 12w of the ceramic green sheet by printing a conductive paste by a screen printing method or a gravure printing method or by transferring a metal foil having a predetermined pattern shape. The conductor patterns of the coil elements 32a to 32d, 34a to 34d, the in-plane wiring conductor 22, the land electrodes 26a and 26b, and the terminal electrode 28 are formed.

  For the ceramic green sheet layers 12q and 12s forming the second coil elements 34b and 34c, an annular gap forming material indicated by a broken line by printing a carbon paste that is burned off by firing in advance. 36, and the second coil elements 34b, 34b, 34b, etc. are formed by printing a conductor paste on the gap forming material 36 by a screen printing method or a gravure printing method or by transferring a metal foil having a predetermined pattern shape. 34c is formed. In the case of upside down, the gap forming material 36 is formed after the second coil elements 34b and 34c of the ceramic green sheet are formed.

  The shrinkage suppressing green sheet used for the constraining layer is an unsintered green sheet formed into a sheet shape. The green sheet for shrinkage suppression includes an inorganic material powder such as alumina that is sintered at a temperature higher than the firing temperature of the ceramic green sheet for forming each layer of the substrate body 12, and a ceramic for forming each layer of the substrate body 12. The green sheet is not substantially sintered at the firing temperature.

  (2) Next, a non-sintered ceramic green sheet forming each layer of the substrate body 12 is laminated to form a laminated body, and constraining layers including shrinkage-suppressing green sheets are arranged on both sides in the laminating direction of the laminated body. Thus, a composite laminate is produced. A relatively small pressure is applied in the stacking direction to temporarily press-bond each layer of the stack and the constraining layer.

  The composite laminate may be prepared by preparing a temporarily bonded laminate and then laminating the shrinkage-suppressing green sheets and further temporarily pressing, or the ceramic green sheets that form the layers of the substrate body 12 and the shrinkage suppression. It may be produced by laminating the green sheets for use and then temporarily pressing them together.

  The constraining layer may be formed by applying a slurry for producing a shrinkage-suppressing green sheet by screen printing on a laminate in which unsintered ceramic green sheets forming each layer of the substrate body 12 are laminated. . You may form by forming the green sheet for shrinkage | contraction suppression on a support body, and transferring it on the laminated body which laminated | stacked the unsintered ceramic green sheet which forms each layer of the board | substrate body 12. FIG.

  (3) Next, a relatively large pressure is applied to the composite laminate, and a constraining layer is finally bonded to the laminate.

  (4) Next, the composite laminate in which the constraining layer is finally bonded to the laminate is fired. Firing is performed under the conditions in which the ceramic material powder included in the ceramic green sheet forming each layer of the laminate that becomes the substrate body 12 is sintered and the inorganic material powder included in the green sheet for suppressing shrinkage of the constraining layer is not sintered. Do. That is, firing is performed at a temperature higher than the sintering temperature of the ceramic green sheet forming each layer of the laminated body that becomes the substrate body 12 and lower than the sintering temperature of the green sheet for suppressing shrinkage of the constraining layer.

  By baking, the carbon paste is decomposed and volatilized, and a void 40 is formed in the portion where the carbon paste was located.

  (5) Next, by removing the constraining layer from the fired composite laminate, the fired laminate, that is, the collective substrate of the coil-embedded substrate 10 is taken out, and a break groove is formed by laser processing or dicing. If necessary, the land electrodes 26a and 26b formed on the upper surface 12a of the substrate body 12 and the terminal electrodes 28 formed on the lower surface 12b are plated.

  (6) After mounting the components 2 and 4 such as surface mount components and IC chips on the land electrodes 26a and 26b of the collective substrate of the coil built-in substrate 10 completed by the above steps, the coil built-in substrate 10 along the break groove. The collective substrate is cut and divided into pieces.

  Next, an example of manufacturing a coil-embedded substrate (DC-DC converter) manufactured by the above method will be described with reference to FIGS. In the production example, the first and second coil elements 32a to 32d, 34a to 34d have a line width A of 200 μm, the first coil elements 32a to 32d have an inner diameter of 1700 μm, and the second coil elements 34a to 34d have an inner diameter. The thickness of 1300 μm and the substrate body 12 is 600 μm. When seen through in the stacking direction, the outer periphery of the inner coil region is in contact with the inner periphery of the outer coil region.

  <Production Example 1> FIG. 4 is a graph showing the conversion efficiency of each of three samples in which the number of voids, that is, the number of void layers, was changed. The vertical axis represents the conversion efficiency (%) for a load current of 100 mA. In the sample having the number of void layers of 0, no void portion is formed. In the sample having the number of void layers of 1, only the void portion in contact with the second coil element 34c shown in FIG. 1 is formed. In the sample having two void layers, a void portion in contact with the first coil element 32b shown in FIG. 1 and a void portion in contact with the second coil element 34c are formed. The gap that is in contact with the first coil element 32b is in contact with the inner peripheral half of the first coil element 32b and is formed between the second coil elements 34a and 34b. In the sample having three void layers, three void portions in contact with the second coil elements 32a, 32b, and 32c shown in FIG. 1 are formed. All the gaps are formed with a width of 300 μm from the inner circumference of the inner coil region to the intermediate position of the outer coil region.

  It can be seen from FIG. 4 that the conversion efficiency is improved by forming at least one gap.

  <Production Example 2> FIG. 5 is a graph showing the conversion efficiency of each of three samples in which the amount of gaps protruding from the outer periphery of the inner coil region is changed. Only the gap 40 along the second coil element 34 c shown in FIG. 1 was formed, and the dimension L that the outer peripheral side 40 q of the gap 40 protrudes outside the outer periphery of the inner coil region 34 was changed.

  FIG. 5 shows that the conversion efficiency is improved when the amount L of the gap protruding from the outer periphery of the inner coil region is 100 μm or more. Assuming that the width of the gap is B, since B = A + L, it can be seen that when B / A ≧ 1.5, the conversion efficiency is improved.

  <Production Example 3> FIG. 6 is a graph showing the conversion efficiency and the coil L value of each of three samples in which the amount of the gap portion protruding inward from the second coil element is changed. The amount of protrusion inside the gap is the length X between the inner circumference 40x of the gap 40 and the inner circumference 34x of the inner coil region 32, as indicated by the chain line in FIG.

  From FIG. 6, it can be seen that when the gap protrudes inside the second coil element, both the conversion efficiency and the coil L value are lowered. Therefore, the gap is preferably formed outside the inner circumference of the inner coil region.

  <Manufacturing Example 4> FIG. 7 shows three samples each having a gap portion in contact with the first coil element (outer coil layer) and a gap portion in contact with the second coil element (inner coil layer). It is a graph which shows conversion efficiency (%) about each three samples. In the former sample, the inner halves of the lower surfaces of the lower three first coil elements 32b, 32c, and 32d in FIG. 1 are exposed, and when viewed in the stacking direction, the middle between the inner periphery and the outer periphery of the outer coil region Three gaps extending from the position to the inner periphery of the inner coil region 34 are provided. In the latter sample, the entire lower surfaces of the upper three second coil elements 32a, 32b, and 32c in FIG. 1 are exposed, and when viewed through from the stacking direction, the inner periphery and the outer periphery of the outer coil region are changed from the inner periphery of the inner coil region. It has three voids extending to an intermediate position between them. The length of the gap is 300 μm.

  From FIG. 7, it can be seen that the conversion efficiency is improved both when the first coil element is exposed in the gap and when the second coil element is exposed. Moreover, it turns out that conversion efficiency improves, so that there are many areas of the coil element exposed to a space | gap part.

  <Summary> When the gap is formed as described above, the magnetic characteristics of the coil can be improved and the efficiency can be improved.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications.

  For example, the shapes of the first and second coil elements and the gap are not limited to the examples. The number of first and second coil elements and gaps may be larger or smaller than in the embodiment. The first and second coil elements can be arranged in any order in the stacking direction.

DESCRIPTION OF SYMBOLS 10 Coil built-in board | substrate 12 Board | substrate body 12a Upper surface 12b Lower surface 12m, 12p-12t, 12w Insulating layer 14a 1st magnetic body ferrite layer 14b 2nd magnetic body ferrite layer 16a 1st nonmagnetic body ferrite layer 16b 2nd non- Magnetic ferrite layer 16c Intermediate non-magnetic ferrite layer 22 In-plane wiring conductor 24, 24p-24t Interlayer connection conductor 26a, 26b Land electrode 28 Terminal electrode 30 Coil 32 Outer coil area 32a-32d First coil element 34 Inner coil area 34a to 34d Second coil element 36 Material for forming gap 38 Virtual center line 40 Air gap

Claims (3)

A substrate body in which a plurality of insulating layers containing a ceramic material are laminated;
A plurality of coil elements disposed around different virtual layers of the insulating layers adjacent to each other and formed around a virtual central axis extending in a stacking direction in which the insulating layers of the substrate body are stacked; ,
An interlayer connection conductor that connects the coil elements through the insulating layer;
At least one gap formed inside the substrate body;
With
The coil element includes first and second coil elements having a constant line width;
The first coil elements overlap each other when seen through in the stacking direction,
The second coil element is in contact with and overlaps the inner periphery inside the outer periphery of the outer coil region where the first coil elements overlap each other when seen through in the stacking direction,
The first and second gaps extend in an annular shape between the inner periphery of the inner coil region and the outer periphery of the outer coil region where the second coil elements overlap each other when seen in the stacking direction. One of the coil elements is disposed between at least one of the two coil elements, the one insulating layer in contact with the coil element, and the other insulating layer facing the coil element. Part is exposed to the gap,
When the line width of the first and second coil elements is A and the width of the gap is B, 1.5 ≦ B / A ≦ 2.0,
The coil-embedded substrate, wherein the number of the gaps is less than half of the total number of the first coil elements and the second coil elements.


The insulating layer of the substrate body is
First and second magnetic ferrite layers containing a magnetic ceramic material;
The intermediate non-magnetic ferrite layer disposed adjacent to the first and second magnetic ferrite layers is interposed between the first and second magnetic ferrite layers. The coil built-in substrate according to 1. The insulating layer of the substrate body is
The first magnetic ferrite layer is disposed adjacent to the first magnetic ferrite layer on the side opposite to the intermediate non-magnetic ferrite layer, and is larger than the thermal expansion coefficient of the first magnetic ferrite layer. A first non-magnetic ferrite layer having a small coefficient of thermal expansion;
The second magnetic ferrite layer is disposed adjacent to the second magnetic ferrite layer on the side opposite to the intermediate non-magnetic ferrite layer, and is larger than the thermal expansion coefficient of the second magnetic ferrite layer. A second non-magnetic ferrite layer having a small coefficient of thermal expansion;
The coil built-in substrate according to claim 2, further comprising:

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