JP2013149933A - Substrate with built-in coil and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce electrical resistance of wiring while considering characteristics of a coil conductor in a substrate with a built-in coil.SOLUTION: A substrate 1 with a built-in coil includes: a magnetic layer 11a; an insulator layer 11b provided on the magnetic layer 11a; a coil conductor 12 provided in the magnetic layer 11a; an element connecting electrode 13a provided on the insulator layer 11b; a first via conductor 14, a first wiring conductor layer 15, and a second via conductor 16 which are provided in the insulator layer 11b; a second wiring conductor layer 17 provided on the insulator layer 11b; and a side conductor 18 provided on a side surface of the insulator layer 11b. The second via conductor 16 is provided close to the first via conductor 14 in the insulator layer 11b.

Description

  The present invention relates to a coil-embedded substrate and an electronic device used for a DC-DC converter, for example.

  For example, a coil-embedded substrate is used in a DC-DC converter or the like mounted on a mobile phone or the like. The coil-embedded substrate includes a base including a magnetic layer and a coil conductor provided in the magnetic layer. For example, an electronic element is mounted on the coil-embedded substrate and electrically connected to the coil conductor. Is done. For example, a voltage output from an external battery or the like is supplied to the electronic element through a wiring provided on the base.

Japanese Patent Laid-Open No. 2005-158975

  When the coil-embedded substrate is used in, for example, a DC-DC converter or the like, in order to supply a desired voltage to an application connected to the DC-DC converter, etc. It is necessary to reduce the resistance. When designing the wiring of the coil-embedded substrate, it is necessary to reduce the influence on the characteristics of the coil conductor in consideration of the magnetic flux generated in the wiring.

  As described above, in the coil-embedded substrate, it is required to reduce the electric resistance of the wiring while considering the characteristics of the coil conductor.

  A coil-embedded substrate according to one aspect of the present invention is provided on a magnetic layer, an insulator layer provided on the magnetic layer, a coil conductor provided in the magnetic layer, and the insulator layer. An element connection electrode; a first via conductor provided in the insulator layer; a first wiring conductor layer and a second via conductor; a second wiring conductor layer provided on the insulator layer; And a side conductor provided on the side surface of the insulator layer. The first via conductor is electrically connected to the element connection electrode. The first wiring conductor layer is electrically connected to the first via conductor. The second via conductor is provided in the insulator layer so as to be close to the first via conductor, and is electrically connected to the first wiring conductor layer. The second wiring conductor layer is electrically connected to the second via conductor. The side conductors are electrically connected to the first and second wiring conductor layers.

  An electronic device according to another aspect of the present invention includes a coil-embedded substrate having the above-described configuration, and an electronic element mounted on the coil-embedded substrate and electrically connected to a coil conductor and an element connection electrode.

  A coil-embedded substrate according to one aspect of the present invention includes a first via conductor electrically connected to an element connection electrode, a first wiring conductor layer electrically connected to the first via conductor, A second via conductor provided close to the first via conductor and electrically connected to the first wiring conductor layer; and a second wiring electrically connected to the second via conductor By including the conductor layer, it is possible to improve the characteristics of the coil conductor while reducing the electrical resistance of the wiring.

  The electronic device according to another aspect of the present invention includes the coil-embedded substrate having the above-described configuration, thereby improving the characteristics of the coil conductor while reducing the electrical resistance of the wiring. If used, a desired voltage can be supplied to the connected application.

(A) has shown the upper surface perspective view of the electronic device in embodiment of this invention, (b) has shown the lower surface perspective view of the electronic device shown by (a). The longitudinal cross-sectional view in AA of the coil built-in board | substrate in the electronic device shown by Fig.1 (a) is shown. FIG. 2 shows a circuit diagram of the electronic device shown in FIG. FIG. 3 is a schematic diagram illustrating current and magnetic flux in the wiring structure shown in FIG. 2. FIG. 6 is a partial exploded view showing first and second wiring conductor layers in another example of the electronic device shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, the electronic device according to the embodiment of the present invention includes a coil built-in substrate 1 and an electronic element 2 mounted on the coil built-in substrate 1. The electronic device is provided in a virtual xyz space, and for the sake of convenience, the upward direction refers to the positive direction of the virtual z axis.

  The coil built-in substrate 1 includes a base 11, a coil conductor 12 provided in the base 11, a plurality of element connection electrodes 13a to 13f provided on the top surface of the base 11, and a plurality of element connection electrodes 13a to 13f. A first via conductor 14 electrically connected to the first via conductor 14, a first wiring conductor layer 15 electrically connected to the first via conductor 14, and the first wiring conductor layer 15 electrically Electrically connected to the second via conductor 16 connected to the second via conductor 16, the second wiring conductor layer 17 electrically connected to the second via conductor 16, and the first and second wiring conductor layers 15 and 17. The connected side conductor 18 includes a plurality of terminals 19 a to 19 f provided on the lower surface of the base 11. One of the terminals 19a to 19f is electrically connected to the side conductor 18.

  The base 11 includes a magnetic layer 11a and insulator layers 11b and 11c provided above and below the magnetic layer 11a. Hereinafter, for convenience, the insulator layer 11b may be referred to as an upper insulator layer 11b, and the insulator layer 11c may be referred to as a lower insulator layer 11c.

The magnetic layer 11a is made of, for example, ferrite such as ZnFe ₂ O ₄ , MnFe ₂ O ₄ , FeFe ₂ O ₄ , CoFe ₂ O ₄ , NiFe ₂ O ₄ , BaFe ₂ O ₄ , SrFe ₂ O _4, or CuFe ₂ O _4. Made of material. The insulator layers 11b and 11c are made of an insulating material such as low temperature co-fired ceramics (LTCC).

  The coil conductor 12 is provided in the magnetic layer 12. Here, “provided in the magnetic layer 12” means that, for example, a nonmagnetic layer is provided in the magnetic layer 12, and the coil conductor 12 is partially in contact with the nonmagnetic layer. The structure is also included.

The plurality of element connection electrodes 13a to 13f are provided on the upper insulator layer 11b. The plurality of element connection electrodes 13a to 13f include a voltage input electrode 13a (VIN), an operation control electrode 13b (EN), a ground electrode 13c (GND), an output voltage monitoring electrode 13d (FB), and an inductor input electrode 13e (
Lx) and the operation switching electrode 13f (MODE).

  Hereinafter, each of the plurality of element connection electrodes 13a to 13f will be described with reference to FIG. The voltage input electrode 13a is used, for example, to supply a voltage output from a battery of an electronic device to the electronic element 2. The operation control electrode 13b (EN) is used to switch the electronic element 2 between an on state and an off state. The ground electrode 13c (GND) is used for supplying a ground voltage to the electronic element 2. The output voltage monitoring electrode 13d (FB) is used for monitoring that the voltage supplied to the application electrically connected to the electronic device of this embodiment is normal. The inductor input electrode 13e (Lx) is used to supply the current output from the electronic element 2 to the coil conductor 12. The operation switching electrode 13f (MODE) is used to switch the operation mode of the electronic element 2.

  The first via conductor 14 is provided vertically in the upper insulating base 11b and is electrically connected to the voltage input electrode 13a.

  The first wiring conductor layer 15 is provided in the lateral direction in the upper insulator layer 11 b and is electrically connected to the first via conductor 14. The first wiring conductor layer 15 extends to the side surface of the upper insulator layer 11b.

  The second via conductor 16 is provided in the vertical direction in the upper insulator layer 11 b and is disposed so as to be close to the first via conductor 14. “Arranged so that they are close to each other” means that the second via conductor 16 is arranged at a position where the magnetic flux generated by the first via conductor 14 can be reduced by the second via conductor 16. The second via conductor 16 is provided on the first wiring conductor layer 15 and is electrically connected to the first wiring conductor layer 15.

  The second wiring conductor layer 17 is provided on the upper insulator layer 11 b and is electrically connected to the second via conductor 16. The second wiring conductor layer 17 is provided on the second via conductor 16 and extends to the end of the upper surface of the upper insulator layer 11b.

  The side conductor 18 is provided on the side surface of the base 11. The side conductor 18 is electrically connected to the first and second wiring conductor layers 15 and 17 on the side surface of the upper insulator layer 11b.

  The plurality of terminals 19a to 19f are provided on the surface of the lower insulator layer 11c. The plurality of terminals 19 include a voltage input terminal 19a (VIN), an operation control terminal 19b (EN), a ground terminal 13c (GND), an output voltage monitoring terminal 19d (FB), an inductor output terminal 19e (IND), and an operation switching terminal. 19f (MODE).

  Hereinafter, each of the plurality of terminals 19a to 19f will be described with reference to FIG. The voltage input terminal 19a receives a voltage output from a battery of an electronic device, for example. The operation control terminal 19b (EN) is used to switch the electronic element 2 between an on state and an off state. A ground voltage is applied to the ground terminal 19c (GND). The output voltage monitoring terminal 19d (FB) is used for monitoring that the voltage supplied to the application electrically connected to the electronic device of this embodiment is normal. The inductor output terminal 19e (IND) is used to supply the current flowing from the coil conductor 12 to, for example, an application electrically connected to the electronic device of this embodiment. The operation switching terminal 19f (MODE) is used for switching the operation mode of the electronic element 2.

The electronic element 2 is an IC element used for a DC-DC converter, for example. The electronic element 2 is mounted on the plurality of element connection electrodes 13 by, for example, solder.

  From here, the wiring which comprises the electric current path from the voltage input electrode 13a to the side conductor 18 is demonstrated with reference to FIG.

  The voltage input electrode 13a is not connected to the side conductor 18 only by the wiring provided on the surface of the upper insulator layer 11a in order to reduce the possibility of solder or the like flowing out of a predetermined position, but the upper insulator layer It is connected to the side conductor 18 through a wiring embedded in 11b. If the voltage input electrode 13a is connected to the side conductor 18 only by wiring provided on the surface of the upper insulator layer 11b, solder or the like for mounting the electronic element 2 is provided on the surface of the upper insulator layer 11b. The possibility of flowing out along the routed wiring increases.

  More specifically, the wiring (that is, current path) from the voltage input electrode 13a to the side conductor 18 is as follows.

  First, the wiring connected to the voltage input electrode 13a extends downward in the upper insulator layer 11b by the first via conductor 14. As described above, the wiring connected to the voltage input electrode 13a is submerged in the upper insulator layer 11b, so that the wiring on the surface of the upper insulator layer 11b extending from the voltage input electrode 13a can be eliminated. The possibility that the solder used for mounting flows out from a predetermined position is reduced.

Next, the wiring connected to the first via conductor 14 includes a first path extending laterally in the upper insulator layer 11b by the first wiring conductor layer 15, a second via conductor 16 and a second via. The wiring conductor layer 17 has a second path coming out again on the surface of the upper insulating layer 11b. The first wiring conductor layer 15 and the second wiring conductor layer 17 are arranged in parallel in the upper insulator layer 11b. That is, the current I ₁₄ flowing through the first via conductor 14 merges at the connection portion between the first wiring conductor layer 15 and the second via conductor 16. The current I ₁₄ is the sum of the current I ₁₅ flowing through the first wiring conductor layer 15 and the current I ₁₆ (or current I ₁₇ ) flowing through the second via conductor 16 and the second wiring conductor layer 17. The current flowing through the two paths is shunted on the side surface of the upper insulator layer 11b (that is, the side surface of the substrate 11).

  In the coil-embedded substrate 1 of this embodiment, the area of the cross section perpendicular to the extending direction of the second wiring conductor layer 17 is larger than the area of the cross section perpendicular to the extending direction of the first wiring conductor layer 15. Designed to be large. Here, the extending direction of the second wiring conductor layer 17 and the extending direction of the first wiring conductor layer 15 refer to a virtual positive direction of the x axis. As a method for making the area of the cross section perpendicular to the extending direction of the second wiring conductor layer 17 larger than the area of the cross section perpendicular to the extending direction of the first wiring conductor layer 15, for example, the second wiring conductor There is a method of making the thickness of the layer 17 larger than the thickness of the first wiring conductor layer 15. As another example, there is a method in which the line width of the second wiring conductor layer 17 is made larger than the line width of the first wiring conductor layer 15. Further, these two methods may be combined.

  Here, actions and effects obtained by including the second via conductor 16 in the coil-embedded substrate 1 in the present embodiment will be described from the viewpoint of magnetic flux and electrical resistance.

First, the magnetic flux F ₁₄ generated by the current I ₁₄ in the first via conductor ₁₄ will be described. If there is no idea in the present embodiment, the magnetic flux F ₁₄ in the first via conductor 14 may affect the magnetic flux that should originally be generated in the coil conductor 12. As a result, the characteristics of the coil conductor 12 may be affected. The coil-embedded substrate 1 according to the present embodiment includes the second via conductor 16 provided so as to be close to the first via conductor 14, so that the first via conductor 14 is located at a position close to the first via conductor 14. It is possible to have a path for a current flowing in a direction opposite to the current I ₁₄ flowing in one via conductor 14. As a result, the coil-embedded substrate 1 of this embodiment, a position close to the magnetic flux F ₁₄ in the first via conductor 14, may be provided with a magnetic flux F ₁₆ to be formed in the opposite direction of the magnetic flux F _14, the coil It is possible to reduce the magnetic flux F ₁₄ that may affect the characteristics of the conductor 12. Further, since the first via conductor 14 and the second via conductor 16 are close to each other, the mutual inductance between the first via conductor 14 and the second via conductor 16 is increased. There is an effect of reducing the combined inductance with the self-inductance of the second via conductor 16.

  Next, the electrical resistance from the voltage input electrode 13a to the side conductor 18 will be described. The coil-embedded substrate 1 in the present embodiment has a current path by the second via conductor 16 and the second wiring conductor layer 17 in addition to the current path by the first wiring conductor layer 15. The electrical resistance to the side conductor 18 is reduced. Therefore, the electrical resistance of the current path from the voltage input terminal 19a to the voltage input electrode 13a shown in FIG. 3 can be reduced. For example, when the electronic device in this embodiment is used as a DC-DC converter, The characteristic regarding the voltage supplied to the application connected to the electronic device in this embodiment can be improved.

Next, the magnetic flux F ₁₅ generated by the current I ₁₅ in the first wiring conductor layer ₁₅ will be described. Flux F ₁₅ of the first wiring conductor layer 15 is relatively for generating the portion close to the coil conductors 12, there is a concern that affect the characteristics of the coil conductor 12. Further, below the first wiring conductor layer 15 for magnetic layer 11a is provided, the magnetic flux F ₁₅ is also a concern that increased by the magnetic layer 11a. However, as described above, since the cross-sectional area of the second wiring conductor layer 17 is larger than the cross-sectional area of the first wiring conductor layer 15 in the coil-embedded substrate 1 of this embodiment, the second wiring conductor layer 17 the current I ₁₇ flowing is greater than the current I ₁₅ flowing in the first wiring conductor layer 15. Therefore, in the coil-embedded substrate 1 of the present embodiment, the magnetic flux F ₁₅ in the first wiring conductor layer 15 is smaller than the magnetic flux F ₁₇ in the second wiring conductor layer 17, and the influence of the magnetic flux F _{15 on} the coil conductor 12 is affected. Has been reduced.

In the coil-embedded substrate 1 of the present embodiment, the current path from the first and second wiring conductor layers 15 and 17 to the voltage input terminal 19a is realized by the side conductor 18 provided on the side surface of the base 11. Therefore, the influence of the magnetic flux on the coil conductor 12 in this current path is reduced. More specifically, by this current path is in contact with the low spatial magnetic permeability, magnetic flux F18 generated in the side conductor 18 is reduced, the coil-embedded substrate 1 of this embodiment, a coil by a magnetic flux F ₁₈ The influence on the conductor 12 is reduced.

  As described above, the coil-embedded substrate 1 according to this embodiment includes the first via conductor 14 electrically connected to the element connection electrode 13a and the first via conductor 14 electrically connected to the first via conductor 14. A wiring conductor layer 15, a second via conductor 16 provided close to the first via conductor 14 and electrically connected to the first wiring conductor layer 15, and a second via conductor 16. By including the second wiring conductor layer 17 electrically connected to the wiring, it is possible to improve the characteristics of the coil conductor 12 while reducing the electrical resistance of the wiring.

  The electronic device according to the present embodiment includes the coil-embedded substrate 1 having the above-described configuration, thereby improving the characteristics of the coil conductor while reducing the electrical resistance of the wiring. For example, the electronic device is used for a DC-DC converter. In some cases, a desired voltage can be supplied to the connected application.

In the above-described example, the second wiring conductor layer is used as a technical device for making the current I ₁₇ flowing through the second wiring conductor layer 17 larger than the current I ₁₅ flowing through the first wiring conductor layer 15. Although the cross-sectional area of 17 is made larger than the cross-sectional area of the first wiring conductor layer 15, two other technical devices will be described below.

In the first other example, the second wiring conductor layer 17 is made of a material having a higher conductivity than the material of the first wiring conductor layer 15. That is, the conductivity of the second wiring conductor layer 17 is set to be higher than that of the first wiring conductor layer 15. For example, when the first and second wiring conductor layers are separated by 50 μm in the vertical direction, the conductivity is 5 × 10 ⁷ (S / m) when the conductivity of the second wiring conductor layer 17 is 5 × 10 ⁷ (S / m). When the conductivity of the first wiring conductor layer 15 is set to about 5 × 10 ⁶ to 1 × 10 ⁷ (S / m), it is effective in reducing the inductance of the wiring.

  The method of making the conductivity of the first wiring conductor layer 15 lower than that of the second wiring conductor layer 17 is, for example, when the second wiring conductor layer 17 is made by adding glass or the like to silver. There is a method of increasing the amount of glass added to the conductor wiring layer 15 as compared with the second wiring conductor layer 17.

In the first other example, since the second wiring conductor layer 17 is made of a material having higher conductivity than the material of the first wiring conductor layer 15, the current I ₁₇ flowing through the second wiring conductor layer 17 is reduced. The current I ₁₅ flowing in the first wiring conductor layer 15 becomes larger, and the magnetic flux F ₁₅ in the first wiring conductor layer 15 becomes smaller than the magnetic flux F ₁₇ in the second wiring conductor layer 17 in the coil-embedded substrate 1. In addition to reducing the influence of magnetic flux on the coil conductor 12, current concentration on the wiring conductor layer 17 away from the magnetic material reduces the amount of magnetic flux generated around the wiring conductor and reduces the inductance of the wiring conductor. Has been.

  The technical device in the first other example can be applied together with the technical device related to the cross-sectional area described above.

  As shown in FIG. 5, in the second other example, the wiring length from the connection portion with the second via conductor to the connection portion of the side conductor 18 in the first wiring conductor layer 15 is second. The wiring conductor layer 17 is set to be longer than the wiring length.

  In FIG. 5, the first via conductor 14 is shown by a broken line in a state where the element connection electrode 13a is seen through, and the second via conductor 16 is shown by a broken line in a state where the second wiring conductor layer 17 is seen through. Has been. Further, the connection portions of the first via conductor 14 and the second via conductor 16 in the first wiring conductor layer 15 are indicated by reference numerals (14) and (15). Connections (14) and (15) are virtually indicated by a two-dot chain line.

  The portion from the connection portion of the second via conductor to the connection portion of the side conductor 18 in the first wiring conductor layer 15 is provided so as to bypass the area between the second via conductor and the side conductor 18, for example. It is set to be longer than the wiring length of the second wiring conductor layer 17.

In the second other example, the wiring length from the connection portion of the first wiring conductor layer 15 to the second via conductor to the connection portion of the side conductor 18 is longer than the wiring length of the second wiring conductor layer 17. As a result, the current I ₁₇ flowing through the second wiring conductor layer 17 becomes larger than the current I ₁₅ flowing through the first wiring conductor layer 15, and the first wiring in the coil-embedded substrate 1. smaller than the magnetic flux F ₁₇ flux F ₁₅ in the conductor layer 15 in the second wiring conductor layer 17, in addition to the influence of the magnetic flux is reduced relative to the coil conductors 12, the wiring conductor layer 17 away from the magnetic By concentrating the current, the amount of magnetic flux generated around the wiring conductor is reduced, and the inductance of the wiring conductor is reduced.

  The technical device in the second other example can be applied together with the technical device related to the cross-sectional area described above, the technical device related to the cross-sectional area, and the technical device in the first other example.

1 Coil-embedded substrate
11 Substrate
12 Coil conductor
13a-13f Electrode for electrode connection
14 First via conductor
15 First wiring conductor layer
16 Second via conductor
17 Second wiring conductor layer
18 Side conductor
19a-19f Terminal 2 Electronic device

Claims (5)

A magnetic layer;
An insulator layer provided on the magnetic layer;
A coil conductor provided in the magnetic layer;
An element connection electrode provided on the insulator layer;
A first via conductor provided in the insulator layer and electrically connected to the element connection electrode;
A first wiring conductor layer provided in the insulator layer and electrically connected to the first via conductor;
A second via conductor provided in the insulator layer so as to be close to the first via conductor and electrically connected to the first wiring conductor layer;
A second wiring conductor layer provided on the insulator layer and electrically connected to the second via conductor;
A coil-embedded board comprising a side conductor provided on a side surface of the insulator layer and electrically connected to the first and second wiring conductor layers.   The area of a cross section perpendicular to the extending direction of the second wiring conductor layer is larger than the area of a cross section perpendicular to the extending direction of the first wiring conductor layer. Coil built-in substrate.   3. The coil-embedded substrate according to claim 1, wherein the second wiring conductor layer is made of a material having higher conductivity than the material of the first wiring conductor layer.   4. The coil-embedded substrate according to claim 1, wherein a wiring length of the first wiring conductor layer is longer than a wiring length of the second wiring conductor layer. 5. The coil-embedded substrate according to claim 1,
An electronic device comprising: an electronic element mounted on the coil-embedded substrate and electrically connected to the coil conductor and the element connection electrode.

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