JP5716391B2 - Coil built-in board - Google Patents

Description

  The present invention relates to a coil-embedded substrate that includes a coil inside and is applied to a DC-DC converter module or the like.

  Patent Document 1 discloses a DC-DC converter module in which a coil is formed inside a substrate. FIG. 1 is a cross-sectional view of a multilayer ceramic electronic component (DC-DC converter module) 1 disclosed in Patent Document 1. As shown in FIG. A multilayer ceramic electronic component 1 is a ceramic multilayer having a multilayer structure including a base layer 2 made of ferrite ceramic and surface layers 3 and 4 respectively arranged on upper and lower main surfaces of the base layer 2 and made of ferrite ceramic. A body 5 is provided. The multilayer ceramic electronic component 1 includes a conductor pattern provided inside and outside the ceramic multilayer body 5. The conductor pattern is roughly classified into an in-plane wiring conductor 6, a surface conductor film 7, and an interlayer connection conductor 8. The in-plane wiring conductor 6 and the surface conductor film 7 are formed on the main surface of the ceramic green sheet that is laminated to form the base material layer 2 or the surface layers 3 and 4 in the process of manufacturing the multilayer ceramic electronic component 1. The interlayer connection conductor 8 is provided so as to penetrate the ceramic green sheet in the thickness direction. The in-plane wiring conductor 6 is formed inside the ceramic laminate 5.

  A coil conductor 9 is formed inside the base material layer 2 by a specific in-plane wiring conductor 6 and a specific interlayer connection conductor 8. The multilayer ceramic electronic component 1 constitutes, for example, a DC-DC converter, and surface-mounted electronic components 10 and 11 are mounted on the main surface facing outward of the surface layer 3. The electronic component 10 is, for example, an IC chip, and is electrically connected to the surface conductor film 7 formed on the main surface facing outward of the surface layer 3 via the solder bumps 12. The other electronic component 11 is, for example, a chip capacitor, and is electrically connected via a solder 13 to a surface conductor film 7 formed on the main surface facing outward of the surface layer 3. The surface conductor film 7 formed on the main surface facing outward of the lower surface layer 4 is used as a terminal electrode when the multilayer ceramic electronic component 1 is mounted on a mother substrate (not shown).

  On the other hand, a shield with high permeability external magnetic layers arranged on the top and bottom surfaces to prevent the influence of leakage magnetic flux of open magnetic circuit type inductors with low magnetic permeability but good linearity and DC superposition characteristics A type inductor is disclosed in Patent Document 2.

International Publication No. 2007/148556 Japanese Patent Publication No. 3-58164

  In the coil-embedded substrate having the structure shown in Patent Document 1, when a conductor other than the coil conductor such as an interlayer connection conductor, an in-plane wiring conductor, or a shield conductor is provided in the vicinity of the coil conductor, these conductors Compared with the case where there is no magnetic flux, the magnetic flux is suppressed, and the electrical characteristics as an inductor deteriorate. That is, when the obtained inductance value is reduced and the wire width of the coil conductor is reduced to increase the number of turns in order to obtain a required inductance value, the Q value and the DC resistance value deteriorate. Further, the signal interferes between a conductor other than the coil conductor and the coil conductor. For example, when a DC / DC converter module is configured, a switching current flows through a coil conductor, and a magnetic field generated by the switching current is combined with a voltage output interlayer connection conductor (via hole conductor) penetrating the substrate. There is a problem that noise is superimposed on the output voltage.

  The shield-type inductor disclosed in Patent Document 2 can prevent unnecessary magnetic flux leakage to the outside, but does not have a structure that prevents unnecessary coupling between the coil conductor and other conductors in the substrate.

  An object of the present invention is to provide a coil-embedded substrate in which unnecessary magnetic flux leakage to the outside is prevented, and noise superposition on conductors such as wiring formed inside or on the outside of the substrate is suppressed.

( 1 ) A first aspect of the present invention is a coil-embedded substrate comprising a magnetic material layer in which a coil conductor and a magnetic material are laminated to constitute all or a main part of the substrate.
An interlayer connection conductor extending in the laminating direction of the magnetic body;
A magnetic region having a higher magnetic permeability than the magnetic layer, extending in the lamination direction of the magnetic body, around the formation region of the coil conductor as viewed from the lamination direction of the magnetic body ,
Further comprising
The magnetic body region is an entire region of the coil conductor formed between the interlayer connection conductor and the coil conductor formation region that is located outside the coil conductor formation region when viewed from the lamination direction of the magnetic bodies. It is characterized in that it is formed only on a part rather than the circumference .

  With this structure, the magnetic field generated by the coil conductor is concentrated in the magnetic material region having a high magnetic permeability, and the spread of the magnetic field in the surface direction of the magnetic material is suppressed. Noise superimposed on the extending interlayer connection conductor is suppressed.

( 2 ) It is preferable that the magnetic material region having a high magnetic permeability extends on a straight line connecting the first main surface and the second main surface of the substrate. With this structure, the process of forming a through hole in the magnetic laminate and filling the magnetic paste can be applied as it is and can be easily manufactured.

( 3 ) The magnetic material region having a high magnetic permeability may be provided discontinuously on one straight line perpendicular to the first main surface and the second main surface of the substrate. With this structure, the unevenness of the component mounting surface (upper surface) of the substrate and the mounting surface (lower surface) of the mounting destination substrate, which is caused by the different shrinkage rates of the magnetic pastes having different magnetic permeability, can be reduced.

( 4 ) It is preferable that the first main surface side and the second main surface side of the substrate are covered with a non-magnetic layer. With this structure, the entire strength is improved because the layer is coated with a layer having a higher strength than the magnetic material.

  According to the present invention, an unnecessary magnetic flux leakage to the outside can be prevented by a single coil-embedded substrate, and noise can be prevented from being superimposed on a conductor such as a wiring formed inside or outside the substrate.

FIG. 1 is a cross-sectional view of a multilayer ceramic electronic component (DC-DC converter module) disclosed in Patent Document 1. As shown in FIG. FIG. 2 is a cross-sectional view showing the configuration of the coil-embedded substrate 101 of the first embodiment and the DC-DC converter module 111 having the same. FIG. 3A is a cross-sectional view showing the configuration of the coil-embedded substrate 102 of the second embodiment and the DC-DC converter module 112 having the same. FIG. 3B is a cross-sectional view of the coil conductor forming layer of the coil-embedded substrate 102. FIGS. 4A and 4B are cross-sectional views showing the configuration of the coil-embedded substrate of the third embodiment and a DC-DC converter module including the same.

<< First Embodiment >>
FIG. 2 is a cross-sectional view showing the configuration of the coil-embedded substrate of the first embodiment and a DC-DC converter module including the same. The DC-DC converter module 111 includes a coil built-in substrate 101 and electronic components (11 and the like) mounted on the upper surface of the coil built-in substrate 101. Usually, a plurality of electronic components are mounted on the upper surface of the coil-embedded substrate 101, but FIG. 2 shows only one of these electronic components (electronic component 11).

  The coil built-in substrate 101 includes a coil conductor forming layer 20 and nonmagnetic layers 31 and 32. The coil conductor forming layer 20 is a magnetic layer in which the coil conductor 9 and a magnetic body are laminated. The non-magnetic layer 31 is formed on the electronic component mounting surface side (first main surface side) and includes the surface conductor film 7. The non-magnetic layer 32 is formed on the mounting surface side (second main surface side) with respect to the wiring board to be mounted, and includes the surface conductor film 7.

The coil conductor forming layer 20, the magnetic layers 21 and 22, and the nonmagnetic layers 31 and 32 are provided with an in-plane wiring conductor 6 and an interlayer connection conductor 8 as necessary.
A magnetic layer 41 having a high magnetic permeability is provided between the coil conductor forming layer 20 and the nonmagnetic layer 31. Further, a magnetic layer 42 having a high magnetic permeability is provided between the coil conductor forming layer 20 and the nonmagnetic layer 32.

  A magnetic layer 21 made of the same magnetic material as the coil conductor forming layer 20 is provided between the magnetic layer 41 having a high magnetic permeability and the nonmagnetic layer 31. A magnetic layer 22 made of the same magnetic material as the coil conductor forming layer 20 is also provided between the magnetic layer 42 having a high magnetic permeability and the nonmagnetic layer 32.

  Here, when the magnetic permeability of the coil conductor forming layer 20 and the magnetic layers 21 and 22 is expressed by μ1, and the magnetic permeability of the magnetic layers 41 and 42 having high magnetic permeability is expressed by μ2, the relationship is μ1 <μ2.

  Thus, by arranging the magnetic layers 41 and 42 having a high magnetic permeability so as to sandwich the coil conductor forming layer 20 in the layer direction, the magnetic layers 41 and 42 in which the magnetic flux generated by the coil conductor 9 has a high magnetic permeability are formed. A magnetic field is distributed so as to pass in the layer direction. Therefore, leakage of the magnetic flux by the coil conductor 9 to the outside is prevented. Moreover, since the magnetic flux by the coil conductor 9 is guided in the laminating direction, the spread of the magnetic flux in the laminating direction (vertical direction) of the magnetic body is suppressed. Therefore, eddy currents hardly flow through the in-plane wiring conductor 6, the surface conductor film 7, the interlayer connection conductor 8, and the like formed in the nonmagnetic layers 31 and 32. That is, the superposition of noise on the in-plane wiring conductor 6, the surface conductor film 7, the interlayer connection conductor 8, and the like formed in the nonmagnetic layers 31, 32 is suppressed.

  The magnetic layers 41 and 42 having a high magnetic permeability may be located closer to the nonmagnetic layers 31 and 32. Alternatively, it may be formed over the entirety between the coil conductor forming layer 20 and the nonmagnetic layers 31 and 32. However, as shown in FIG. 2, the magnetic layers 41 and 42 with high magnetic permeability are close to the coil conductor forming layer 20, and the magnetic layers 41 and 42 with high magnetic permeability and the nonmagnetic layers 31 and 32 are high. If magnetic material layers 21 and 22 having a relatively low magnetic permeability exist between the magnetic material layers 41 and 42, the magnetic flux passing through the magnetic material layers 41 and 42 having a high magnetic permeability is formed in the nonmagnetic material layers 31 and 32. It can be separated from the in-plane wiring conductor 6, the surface conductor film 7, the interlayer connection conductor 8, and the like. For this reason, the superposition of noise on the in-plane wiring conductor 6, the surface conductor film 7, the interlayer connection conductor 8 and the like formed in the nonmagnetic layers 31 and 32 is more reliably suppressed.

  In the first embodiment, the laminated body of the coil conductor forming layer 20, the magnetic layers 21 and 22, and the magnetic layers 41 and 42 having high magnetic permeability is a magnetic layer constituting the main part of the substrate. The first main surface side and the second main surface side of the magnetic layer are covered with the nonmagnetic layers 31 and 32. In general, a non-magnetic material has a higher strength than a magnetic material. Therefore, according to the first embodiment, a high strength can be obtained for the entire substrate.

  The coil-embedded substrate 101 is manufactured by a green sheet process. The coil conductor forming layer 20 and the magnetic layers 21 and 22 are, for example, magnetic ferrites mainly composed of Fe—Ni—Zn—Cu-based oxides. Before firing, it is a laminate of these ceramic green sheets. The nonmagnetic layers 31 and 32 are nonmagnetic ferrites composed mainly of Fe-Zn-Cu oxides. Before firing, it is a laminate of this ceramic green sheet.

  The interlayer connection conductor 8 is a sintered body of conductive paste. Before firing, a conductive paste (unsintered interlayer connection conductor) filled in through holes formed in a predetermined ceramic green sheet. The coil conductor 9, the in-plane wiring conductor 6, the surface conductor film 7, and the interlayer connection conductor 8 are sintered bodies of conductive paste. Before firing, the conductive paste is printed on a predetermined ceramic green sheet. The conductive metal contained in these conductive pastes is preferably composed mainly of silver or silver / palladium.

  In the above embodiment, the magnetic layers 41 and 42 having a high magnetic permeability are arranged so as to sandwich the coil conductor forming layer 20 in the layer direction. However, the coil conductor is formed between the coil conductor forming layer 20 and the electronic component mounting surface. By disposing a magnetic layer having a high magnetic permeability on at least one between the layer 20 and the mounting surface, an effect of preventing leakage of magnetic flux to at least one side by the coil conductor 9 can be obtained.

<< Second Embodiment >>
FIG. 3A is a cross-sectional view showing the configuration of the coil-embedded substrate of the second embodiment and a DC-DC converter module including the same. FIG. 3B is a cross-sectional view of the coil conductor forming layer. The DC-DC converter module 112 includes a coil built-in substrate 102 and electronic components (11 and the like) mounted on the upper surface of the coil built-in substrate 102.

  The coil built-in substrate 102 includes a coil conductor forming layer 20 and nonmagnetic layers 31 and 32. The coil conductor forming layer 20 is a magnetic layer in which the coil conductor 9 and a magnetic body are laminated. The non-magnetic layer 31 is formed on the electronic component mounting surface side (first main surface side) and includes the surface conductor film 7. The non-magnetic layer 32 is formed on the mounting surface side (second main surface side) with respect to the wiring board to be mounted, and includes the surface conductor film 7.

The coil conductor forming layer 20, the magnetic layers 21 and 22, and the nonmagnetic layers 31 and 32 are provided with an in-plane wiring conductor 6 and an interlayer connection conductor 8 as necessary.
A laminated body of the coil conductor forming layer 20 and the magnetic layers 21 and 22 is a magnetic layer constituting the main part of the substrate. In the magnetic layer, magnetic regions 51 and 52 having high permeability are provided around the region where the coil conductor 9 is formed.

  Here, when the magnetic permeability of the coil conductor forming layer 20 and the magnetic layers 21 and 22 is expressed by μ1, and the magnetic permeability of the magnetic regions 51 and 52 having a high magnetic permeability is expressed by μ2, there is a relationship of μ1 <μ2.

  Thus, by providing the magnetic material regions 51 and 52 with high magnetic permeability extending in the laminating direction of the magnetic sheet around the region where the coil conductor 9 is formed, the magnetic material region where the magnetic field generated by the coil conductor 9 has high magnetic permeability. As a result, the spread of the magnetic field in the plane direction of the magnetic body is suppressed. For this reason, noise superimposed on the interlayer connection conductor 8 formed in the substrate and extending in the magnetic layer stacking direction is suppressed.

  According to the second embodiment, the magnetic material regions 51 and 52 having high magnetic permeability extend on a straight line connecting the first main surface and the second main surface of the substrate. Therefore, since it is only necessary to add a step of forming a through hole in the magnetic laminate and filling the magnetic paste to the green sheet process, it can be easily manufactured.

<< Third Embodiment >>
4A and 4B are cross-sectional views showing the configurations of the coil-embedded substrates 103A and 103B and the DC-DC converter modules 113A and 113B having the same according to the third embodiment. What is different from the structure shown in FIG. 3 in the second embodiment is the shape of the magnetic regions 51 and 52 having high magnetic permeability. In the example of FIG. 4A, magnetic material regions 51 and 52 having high magnetic permeability extending in the magnetic material laminating direction are provided around the formation region of the coil conductor 9, but the nonmagnetic material layers 31 and 32 are respectively provided. Is not formed in the central portion of the magnetic layer that is a laminate of the coil conductor forming layer 20 and the magnetic layers 21 and 22. That is, the magnetic regions 51 and 52 having high magnetic permeability are discontinuously provided on one straight line perpendicular to the first main surface and the second main surface of the substrate.

  In the example of FIG. 4B, magnetic material regions 51 and 52 having high magnetic permeability extending in the magnetic material laminating direction are provided around the formation region of the coil conductor 9, but the coil conductor forming layer 20 and the magnetic material are provided. Of the magnetic layers, which are laminated bodies with the layers 21 and 22, are formed in the center.

  With these structures, it is possible to reduce irregularities on the component mounting surface (upper surface) of the substrate and the mounting surface (lower surface) of the mounting destination substrate, which are caused by different shrinkage rates of ferrite pastes having different magnetic permeability.

<< Other embodiments >>
The coil-embedded substrate of the present invention includes both the high-permeability magnetic layers 41 and 42 shown in the first embodiment and the high-permeability magnetic regions 51 and 52 shown in the second embodiment. May be provided. According to the structure, the magnetic flux by the coil conductor 9 passes through the magnetic layers 41 and 42 having a high magnetic permeability in the plane direction of the magnetic material, and the magnetic material regions 51 and 52 having a high magnetic permeability in the lamination direction of the magnetic materials. Pass through. Therefore, unnecessary magnetic flux leakage to the outside is prevented, and noise superposition to conductors such as wiring formed inside or outside the substrate is more effectively suppressed.

  Further, the magnetic layer of the coil-embedded substrate of the present invention only needs to constitute the entire layer or the main layer of the substrate on which the coil conductor and the magnetic body are laminated.

6 ... In-plane wiring conductor 7 ... Surface conductor film 8 ... Interlayer connection conductor 9 ... Coil conductor 11 ... Electronic component 20 ... Coil conductor forming layer (magnetic layer)
21, 22 ... magnetic layer 31, 32 ... nonmagnetic layer 41, 42 ... high magnetic permeability magnetic layer 51, 52 ... high magnetic permeability magnetic region 101, 102, 103 A, 103 B ... coil built-in substrate 111, 112, 113A, 113B ... DC-DC converter module

Claims (4)

In the coil-embedded substrate provided with a magnetic layer in which the coil conductor and the magnetic material are laminated to constitute the whole or the main part of the substrate,
An interlayer connection conductor extending in the laminating direction of the magnetic body;
A magnetic region having a higher magnetic permeability than the magnetic layer, extending in the lamination direction of the magnetic body, around the formation region of the coil conductor as viewed from the lamination direction of the magnetic body ,
Further comprising
The magnetic body region is an entire region of the coil conductor formed between the interlayer connection conductor and the coil conductor formation region that is located outside the coil conductor formation region when viewed from the lamination direction of the magnetic bodies. A substrate with a built-in coil, characterized in that it is formed only on a part rather than a circumference . The coil-embedded substrate according to claim 1 , wherein the magnetic material region having a high magnetic permeability extends on a straight line connecting the first main surface and the second main surface of the substrate. 2. The coil-embedded substrate according to claim 1 , wherein the high-permeability magnetic body region is discontinuously provided on one straight line perpendicular to the first main surface and the second main surface of the substrate. The first main surface side and a second main surface side is covered with a layer of non-magnetic material, coil-embedded substrate according to any one of claims 1 to 3 of the substrate.

Images