WO2014030471A1

WO2014030471A1 - Laminated substrate and manufacturing method therefor

Info

Publication number: WO2014030471A1
Application number: PCT/JP2013/069586
Authority: WO
Inventors: 家田章弘; 大坪喜人
Original assignee: 株式会社村田製作所
Priority date: 2012-08-21
Filing date: 2013-07-19
Publication date: 2014-02-27

Abstract

Provided is a laminated substrate such that cracking due to shear stress between a blade and ceramic material during a punching process for forming end-face electrodes or due to stress attributable to a difference in linear expansion coefficient between the end-face electrodes and the ceramic material is prevented. No end-face electrode is formed on a non-magnetic ferrite layer (11) and a non-magnetic ferrite layer (15) on the outermost layers. Mounting electrodes formed on the outermost layers are electrically connected to as far as the internal wiring at a boundary surface between a magnetic ferrite layer (12) and a magnetic ferrite layer (14) by means of via holes provided inside the non-magnetic ferrite layer (11) and non-magnetic ferrite layer (15) on the outermost layers, and are then connected to the end-face electrodes through the internal wiring. Consequently, only the outermost non-magnetic ferrite layers are connected by means of the via holes, and the magnetic ferrite layers are connected through the end-face electrodes instead of the via holes.

Description

Multilayer substrate and manufacturing method thereof

The present invention relates to a multilayer substrate formed by laminating a plurality of ceramic green sheets.

Conventionally, there has been known a multilayer substrate obtained by printing a conductor pattern on a ceramic green sheet made of a magnetic material and laminating (see, for example, Patent Document 1).

The multilayer substrate shown in Patent Document 1 employs a technique of electrically connecting the top surface and the bottom surface by forming electrodes on the end surfaces.

Japanese Patent Laid-Open No. 11-345713

However, when forming a through-hole with a puncher or the like before firing to form an electrode on the end face, as the thickness of the laminated substrate increases, the shear stress (shear stress) between the puncher blade and the ceramic green sheet increases. It may increase and cause cracks. Moreover, since the electrode and the ceramic green sheet have different linear expansion coefficients, cracks may occur due to the stress generated during cooling after firing depending on the thickness of the laminated substrate.

Therefore, an object of the present invention is to provide a laminated substrate that prevents the occurrence of cracks, and a method for manufacturing the same.

The multilayer substrate of the present invention includes a magnetic layer formed by stacking a plurality of magnetic substrates, and a nonmagnetic layer formed by stacking a plurality of nonmagnetic substrates and disposed in the outermost layer. . A plurality of mounting electrodes formed on the front and back surfaces of the outermost layer of the multilayer substrate; and a plurality of mounting electrodes provided on the nonmagnetic material layer of the outermost layer and electrically connected to the plurality of mounting electrodes, respectively. Via holes, end face electrodes provided on end faces of the multilayer substrate, and internal wirings that electrically connect the plurality of via holes and the end face electrodes, wherein the end face electrodes are formed of the nonmagnetic material. It is not formed in the nonmagnetic body layer arrange | positioned at least in any one side of the said surface or a back surface among body layers.

As described above, in the multilayer substrate of the present invention, no end face electrode is formed on at least one of the nonmagnetic layers on the front side or the back side. In this case, the mounting electrode is electrically connected to the end face electrode formed in the magnetic layer on the inner layer side through the via hole and the internal wiring. Thereby, compared with the case where an end surface electrode is formed in all the layers of a multilayer substrate, the length of the end surface electrode in the stacking direction can be reduced. Therefore, compared to the case where the end face electrodes are formed on all the layers of the multilayer substrate, the number of sheet layers that need to be formed with through holes can be reduced, so that the shear between the blade and the ceramic green sheet during the formation of the through holes can be reduced. Stress (shear stress) can be reduced. Moreover, the stress which arises at the time of cooling after baking can be reduced and generation | occurrence | production of a crack can be prevented.

In addition, the aspect in which the end surface electrode is not formed on both end surfaces of the nonmagnetic material layer on the front surface side and the back surface side is also possible.

Further, the intermediate layer including the magnetic layer may include a nonmagnetic material.

The laminated substrate includes a non-magnetic substrate manufacturing process and a magnetic substrate manufacturing process, respectively, and then, the plurality of non-magnetic substrates are arranged in an outermost layer, and the plurality of non-magnetic substrates and It is manufactured by laminating a plurality of magnetic substrates to obtain a laminated substrate and firing the laminated substrate.

Non-magnetic substrate manufacturing process
(1) Step of preparing a plurality of non-magnetic substrate ceramic green sheets (2) Step of forming a plurality of mounting electrodes on the front and back surfaces of the non-magnetic substrate disposed in the outermost layer (3) On the inner layer side The method includes a step of providing a plurality of via holes in a plurality of nonmagnetic substrates to be arranged.

The magnetic substrate manufacturing process
(1) Step of preparing ceramic green sheets of a plurality of magnetic substrates (2) Step of providing end face electrodes on end surfaces of the plurality of magnetic substrates (3) Forming internal wiring in a part of the magnetic substrates It consists of a process.

In the multilayer substrate manufacturing method of the present invention, in each of the above steps, the internal wiring is formed so as to electrically connect the via hole and the end face electrode, and at least a part of the mounting electrode is It is electrically connected to the end face electrode through a via hole and the internal wiring. As a result, the end face electrode is not formed on the nonmagnetic layer disposed on at least one of the front and back surfaces of the nonmagnetic layer.

According to the present invention, when the end face electrode is formed, cracks are generated due to shear stress (shear stress) between the puncher blade and the ceramic green sheet, and also due to the difference in coefficient of linear expansion between the end face electrode and the ceramic. Thus, it is possible to prevent cracks from being generated due to the stress generated.

It is a longitudinal cross-sectional view of a DC-DC converter. It is a top view of a DC-DC converter. It is a figure which shows a nonmagnetic board | substrate manufacturing process. It is a figure which shows a magnetic substrate manufacturing process. It is a perspective view of the nonmagnetic material layer and magnetic material layer of a mother laminated body.

FIG. 1 is a diagram schematically showing a longitudinal cross-sectional structure of a DC-DC converter module provided with the multilayer substrate of the present invention.

The laminated substrate is composed of a laminated body in which a plurality of ceramic green sheets are laminated. The laminated substrate includes a nonmagnetic ferrite layer 11, a magnetic ferrite layer 12, a nonmagnetic ferrite layer 13, a magnetic ferrite layer 14, in order from the front surface (upper surface) side to the back surface (lower surface) side of the outermost layer. In addition, a nonmagnetic ferrite layer 15 is disposed.

FIG. 2A is a plan view of the uppermost surface (first layer) in the component-mounted state of the DC-DC converter module, and FIG. 2B is a plan view of the uppermost surface when the mounted components are omitted. is there. FIG. 2C is a plan view of a nonmagnetic substrate disposed in the lower layer (second layer). 2D is a plan view of the uppermost surface of the magnetic ferrite layer 12, and FIG. 2E is a plan view of a magnetic substrate on which the conductor pattern 31 is formed in the magnetic ferrite layer 12. As shown in FIG. is there.

As shown in FIGS. 1 and 2B, a plurality of component mounting electrodes are formed on the uppermost surface in the stacking direction of the stacked substrate. In FIG. 1 and FIG. 2B, an electrode 21A connected to the input terminal 55 of the control IC 51, an electrode 21B connected to the ground terminal 56 of the control IC 51, an electrode 21C connected to the output terminal 57 of the control IC 51, And electrode 21D connected to the terminal of output side capacitor 52 is shown.

On the bottom surface in the stacking direction of the multilayer substrate, various electrodes are formed for connection to the land electrode on the mounting substrate side on which the DC-DC converter is mounted. In FIG. 1, an input electrode 25 and an output electrode 26 are shown.

A via hole is formed in each substrate of the non-magnetic ferrite layer 11 including the second layer. The via hole is formed by opening a through hole in each non-magnetic ceramic green sheet and filling the through hole with a conductive paste. For example, as shown in FIGS. 1 and 2C, a via hole 41 is formed in the lower part of the component mounting electrode 21A, a via hole 42 is formed in the lower part of the electrode 21B, and a lower part of the electrode 21C. A via hole 43 is formed, and a via hole 44 is formed below the electrode 21D.

As shown in FIG. 1 and FIG. 2 (D), an internal wiring is formed on the uppermost surface of the magnetic ferrite layer 12. For example, an internal wiring 71 is formed below the via hole 41, an internal wiring 77 is formed below the via hole 42, and an internal wiring 74 is formed below the via hole 44. Thus, the electrode 21A is electrically connected to the internal wiring 71 through the via hole 41, the electrode 21B is electrically connected to the internal wiring 77 through the via hole 42, and the electrode 21D is connected to the internal wiring 71 through the via hole 44. It is electrically connected to the internal wiring 74.

Further, as shown in FIG. 1, the internal wiring 72 and the internal wiring 73 are also formed on the top surface of the nonmagnetic ferrite layer 15. The internal wiring 72 and the internal wiring 73 are electrically connected to the input electrode 25 and the output electrode 26 through via holes formed in the nonmagnetic ferrite layer 15, respectively.

As shown in FIGS. 1, 2D, and 2E, the end surfaces of the magnetic ferrite layer 12, the non-magnetic ferrite layer 13, and the magnetic ferrite layer 14 of the laminated substrate are end-through. A hole 75, an end surface through hole 76, an end surface through hole 95, and an end surface through hole 96 are formed.

The end face through hole 75 electrically connects the internal wiring 71 and the internal wiring 72. Thus, the electrode 21A is electrically connected to the input electrode 25. The end surface through hole 76 electrically connects the internal wiring 73 and the internal wiring 74. Thereby, the electrode 21 </ b> D is electrically connected to the output electrode 26. The end face through hole 95 and the end face through hole 96 connect various electrodes on the uppermost surface (for example, the electrode 21B for mounting components) to ground electrodes (not shown) on the lowermost surface.

Further, as shown in FIG. 1 and FIG. 2 (E), a conductor pattern 31 which is an internal wiring is formed on a part of the ceramic green sheets arranged on the inner layer side of the multilayer substrate. The conductor pattern 31 is wired in a spiral manner with the magnetic ferrite layer 12, the nonmagnetic ferrite layer 13, and the magnetic ferrite layer 14 sandwiched between them by via connection via holes. Thus, a coil conductor is formed, the laminated substrate functions as an inductor, and functions as a DC-DC converter module by mounting electronic components such as the control IC 51 and various capacitors.

For example, in the case of a step-down DC-DC converter, the conductor pattern 31 functioning as an inductor is connected to the output terminal 57 of the control IC 51. The output side of the conductor pattern 31 is connected to the output side capacitor 52, and the output side of the output side capacitor 52 and the conductor pattern 31 is various types such as the electrode 21D, the internal wiring 74, the end face through hole 76, and the internal wiring 73. It is connected to the output electrode 26 through wiring.

The non-magnetic ferrite layer 13 as an intermediate layer functions magnetically to be equivalent to the case where a gap exists between the magnetic ferrite layer 12 and the magnetic ferrite layer 14, and DC superimposition as an inductor is performed. Although it improves the characteristics, it is not an essential element in the present invention.

The outermost nonmagnetic ferrite layer 11 and the nonmagnetic ferrite layer 15 have a function of covering the upper surface side and the lower surface side of the magnetic ferrite layer 12 and the magnetic ferrite layer 14, respectively. Further, by sandwiching the magnetic ferrite layer 12 and the magnetic ferrite layer 14 having a relatively high heat shrinkage rate between the nonmagnetic ferrite layer 11 and the nonmagnetic ferrite layer 15 having a relatively low heat shrinkage rate, It is provided to improve the strength by compressing the entire element by firing.

The multilayer substrate of the present embodiment includes an outermost nonmagnetic ferrite layer 11 and a nonmagnetic ferrite layer as shown in FIGS. 1, 2A, 2B, and 2C. No end face through-hole is formed in 15.

Each mounting electrode formed in the outermost layer is connected to the magnetic ferrite layer 12 and the magnetic ferrite layer via via holes provided in the nonmagnetic ferrite layer 11 and the nonmagnetic ferrite layer 15 of the outermost layer. 14 is electrically connected to the internal wiring arranged on the boundary surface with 14 and connected to the end face electrode through the internal wiring. Thereby, only the outermost nonmagnetic layer is connected by the via hole, and the magnetic layer is connected not by the via hole but through the end face electrode. For the nonmagnetic layer, even if a via hole is provided, the parasitic inductance does not increase. In this case, the length of the end surface electrode in the stacking direction can be reduced as compared with the case where the end surface electrodes are formed on all the layers of the stacked substrate. Therefore, compared to the case where the end face electrodes are formed on all the layers of the multilayer substrate, the stress (due to the difference in the linear expansion coefficient between the electrode and the ceramic) generated during cooling after firing can be reduced, and cracks can be reduced. Occurrence can be prevented.

In the multilayer substrate shown in FIG. 1, the end face electrode is not formed on both the outermost nonmagnetic ferrite layer 11 and the nonmagnetic ferrite layer 15, but at least on either side. Any mode may be used as long as it is not formed in the arranged nonmagnetic ferrite layer.

Also, the end face electrode may not be formed in the nonmagnetic ferrite layer 13 as the intermediate layer. In this case, internal wiring is formed on the uppermost surface and the lowermost surface of the nonmagnetic ferrite layer 13, and the internal wiring is electrically connected through a via hole.

Next, a method for manufacturing the laminated substrate will be described. The laminated substrate is subjected to a nonmagnetic substrate manufacturing process and a magnetic substrate manufacturing process, respectively, and then a plurality of nonmagnetic substrates are arranged in the outermost layer, and the plurality of nonmagnetic substrates and a plurality of magnetic substrates are arranged. It is manufactured by performing a step of obtaining a laminated substrate by laminating body substrates and a step of firing the laminated substrate.

FIG. 3 is a diagram showing a non-magnetic substrate manufacturing process. First, as shown in FIG. 3A, a plurality of ceramic green sheets (mother sheets) of a non-magnetic substrate are prepared.

Next, as shown in FIG. 3B, various electrodes are formed on the non-magnetic substrate arranged in the outermost layer, and as shown in FIG. 3C, the non-magnetic substance arranged on the inner layer side. A hole is formed in the body substrate by a punch or the like at a position corresponding to the lower portion of the electrode. Finally, as shown in FIG. 3D, a via hole is formed by filling a hole formed in the step of FIG. 3C with a conductive material such as silver.

On the other hand, FIG. 4 is a diagram showing a magnetic substrate manufacturing process. First, as shown in FIG. 4A, a plurality of ceramic green sheets (mother sheets) of a magnetic substrate are prepared. Then, as shown in FIG. 4 (B), a rectangular hole is opened with a punch or the like at a position to be an end face of each laminated substrate after singulation, and a conductive material is filled as shown in FIG. 4 (C). .

Then, as shown in FIG. 4D, internal wiring is formed on the magnetic substrate disposed on the uppermost surface of the magnetic ferrite layer 12. Internal wiring is also formed on the nonmagnetic substrate disposed on the top surface of the nonmagnetic ferrite layer 15.

On the other hand, as shown in FIG. 4E, the magnetic substrate disposed on the inner layer side of the laminated substrate and the nonmagnetic substrate disposed on the nonmagnetic ferrite layer 13 as an intermediate layer include A conductor pattern to be a coil conductor is formed.

Thereafter, the nonmagnetic substrate is disposed in the outermost layer, and a plurality of nonmagnetic substrates and a plurality of magnetic substrates are stacked to obtain a mother stacked body.

FIG. 5 shows a perspective view of the non-magnetic layer and the magnetic layer of the mother laminate obtained in this way. 5A shows the surface of the outermost nonmagnetic layer, FIG. 5B shows the surface of the magnetic layer at the interface between the magnetic layer and the nonmagnetic layer, and FIG. 5C shows the magnetic layer. The layer in which the conductor pattern used as the coil conductor inside a layer is formed is shown. As shown in FIG. 5A, punching or the like is performed in a direction (orthogonal direction) different from the rectangular hole shown in FIG. 4B that was previously opened in the magnetic layer from the nonmagnetic layer on the surface. Open a more rectangular hole with. The shape of the hole opened in the step of FIG. 4B and the shape of the hole opened in the step of FIG. 5A are not limited to a rectangle, and may be any shape such as an ellipse or a circle.

Thereby, the rectangular hole opened in the process of FIG. 5A becomes a through hole, and the rectangular hole opened in the process of FIG. 4B (filled with the conductive material) becomes the end face electrode. Become.

The nonmagnetic substrate disposed in the nonmagnetic ferrite layer 13 as the intermediate layer has an end face electrode similar to the steps shown in FIGS. 4B, 4C, and 4D. It is formed.

Then, the mother laminate is fired and then later broken to obtain the laminated substrate of the present invention.

11, 13, 15 ... non-magnetic ferrite layers 12, 14 ... magnetic ferrite layers 21 A, 21 B, 21 C, 21 D ... electrodes 25 ... input electrodes 26 ... output electrodes 31 ...

conductor patterns

41, 42, 43, 44 ... via holes 51 ... IC
52 ... Output-side capacitor 55 ... Input terminal 56 ... Ground terminal 57 ...

Output terminals

71, 72, 73, 74, 77 ...

Internal wiring

75, 76, 95, 96 ... End face through hole

Claims

A magnetic layer formed by laminating a plurality of magnetic substrates;
A plurality of non-magnetic substrates are laminated, and a non-magnetic layer disposed in the outermost layer;
A laminated substrate comprising:
A plurality of mounting electrodes formed on the front and back surfaces of the outermost layer of the multilayer substrate;
A plurality of via holes provided in the outermost nonmagnetic layer and electrically connected to the plurality of mounting electrodes,
An end face electrode provided on the end face of the laminated substrate;
An internal wiring for electrically connecting the plurality of via holes and the end face electrode;
Further comprising
The laminated substrate, wherein the end face electrode is not formed on a nonmagnetic layer disposed on at least one of the front and back surfaces of the nonmagnetic layer.
2. The laminated substrate according to claim 1, wherein the end face electrode is not formed on both end faces of the nonmagnetic layer on the front side and the back side.
The multilayer substrate according to claim 1 or 2, wherein the intermediate layer including the magnetic layer contains a non-magnetic material.
Preparing a plurality of non-magnetic substrate ceramic green sheets, forming a plurality of mounting electrodes on the front and back surfaces of the non-magnetic substrate disposed in the outermost layer, and a plurality of non-magnetic substrates disposed on the inner layer side Providing a plurality of via holes in the magnetic substrate, and a non-magnetic substrate manufacturing process comprising:
A magnetic body comprising a step of preparing ceramic green sheets of a plurality of magnetic substrates, a step of providing end face electrodes on end surfaces of the plurality of magnetic substrates, and a step of forming internal wiring in a part of the magnetic substrates. Substrate manufacturing process;
Each, then
Arranging the plurality of non-magnetic substrates in an outermost layer and stacking the plurality of non-magnetic substrates and the plurality of magnetic substrates to obtain a laminated substrate;
Firing the laminated substrate;
A method for manufacturing a multilayer substrate, comprising:
The internal wiring is formed so as to electrically connect the via hole and the end face electrode,
At least a part of the mounting electrode is electrically connected to the end face electrode through the via hole and the internal wiring.
The non-magnetic substrate manufacturing process includes:
Including a manufacturing process of a non-magnetic substrate disposed on the inner layer side,
The method for manufacturing a laminated substrate according to claim 4, wherein the nonmagnetic substrate disposed on the inner layer side includes a step of providing an end face electrode on the end face.