JP4332954B2 - Multilayer ceramic substrate and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer ceramic substrate manufactured by applying a so-called non-shrinkage process that can substantially prevent shrinkage in the main surface direction in the firing step, and particularly to a method for manufacturing the same. The present invention relates to an improvement in ensuring isolation between wiring conductors.
[0002]
[Prior art]
The multilayer ceramic substrate includes a plurality of laminated ceramic layers, and appropriate wiring conductors are provided on specific interfaces between these ceramic layers and on the outer surface of the multilayer ceramic substrate. These wiring conductors achieve an electrical connection between a plurality of functional elements provided in association with the multilayer ceramic substrate, and are used for IC chips and other chip-like electronic components mounted on the outer surface of the multilayer ceramic substrate. Provides connection pads for electrical connection. Further, in the multilayer ceramic substrate, necessary functional elements such as capacitor elements may be constituted by the wiring conductor.
[0003]
When such a multilayer ceramic substrate is used as a component constituting a high frequency circuit, the dielectric constant of the ceramic layer provided in the multilayer ceramic substrate is made as low as possible, thereby ensuring isolation between a plurality of wiring conductors. I have to.
[0004]
[Problems to be solved by the invention]
In order to increase the functionality, density, performance, and size of a multilayer ceramic substrate, it is effective to provide high-density wiring in such a multilayer ceramic substrate. However, as high-density wiring advances, it becomes difficult to ensure sufficient isolation between wiring conductors only by reducing the dielectric constant of the ceramic layer as described above.
[0005]
On the other hand, for the isolation between the wiring conductors, it is effective to arrange a magnetic body capable of absorbing electromagnetic waves between the wiring conductors. Therefore, it is conceivable to replace a specific dielectric ceramic layer with a magnetic ceramic layer in a multilayer ceramic substrate including a plurality of laminated dielectric ceramic layers.
[0006]
However, when it is intended to manufacture a multilayer ceramic substrate in which the dielectric ceramic layer and the magnetic ceramic layer are mixed, the dielectric green sheet containing the dielectric ceramic material and the magnetic green sheet containing the magnetic ceramic material are used. Since there is a relatively large difference in the sintering shrinkage rate or shrinkage behavior in the firing process, warping and distortion are likely to occur in the case of large-scale multilayer ceramic substrates, regardless of chip-shaped multilayer ceramic electronic components. At present, it is difficult to manufacture a multilayer ceramic substrate having both such a dielectric ceramic layer and a magnetic ceramic layer on a mass production scale.
[0007]
Accordingly, an object of the present invention is to provide a multilayer ceramic substrate and a method for manufacturing the same, which can solve the above-described problems.
[0008]
[Means for Solving the Problems]
In short, the present invention enhances the effect of isolation between wiring conductors by forming a magnetic ceramic layer on a multilayer ceramic substrate, and at the same time, reduces the sintering shrinkage between the dielectric green sheet and the magnetic green sheet. The problem caused by the difference in contraction behavior is to be solved by applying a so-called no-shrink process.
[0009]
More specifically, the multilayer ceramic substrate according to the first aspect of the present invention is disposed in contact with a plurality of dielectric ceramic layers including a dielectric ceramic material, and a specific one of these dielectric ceramic layers, and a dielectric A magnetic ceramic material that is thinner than the thickness of the body ceramic layer and that does not sinter at the sintering temperature of the dielectric ceramic material in an unsintered state, and a portion of the material contained in the dielectric ceramic layer is infiltrated; It is characterized by comprising a magnetic ceramic layer and a wiring conductor provided along a specific interface of a laminated structure composed of a dielectric ceramic layer and a magnetic ceramic layer.
[0010]
On the other hand, the multilayer ceramic substrate according to the second aspect of the present invention includes a plurality of dielectric ceramic layers including a dielectric ceramic material, and a magnetic ceramic material that can be sintered at a sintering temperature of the dielectric ceramic material. The magnetic ceramic layer is disposed between the dielectric ceramic layer and the magnetic ceramic layer, and is thinner than the thickness of the dielectric ceramic layer and the magnetic ceramic layer, and each of the dielectric ceramic material and the magnetic ceramic material is sintered. An insulation ceramic material that does not sinter at a temperature in an unsintered state, and a part of each material contained in each of the dielectric ceramic layer and the magnetic ceramic layer is infiltrated; and a dielectric A wiring conductor provided along a specific interface of the laminated structure including the ceramic layer, the magnetic ceramic layer, and the shrinkage suppression layer. It is a symptom.
[0011]
In each of the multilayer ceramic substrates according to the first and second aspects described above, a plurality of wiring conductors may be provided along the same interface of the multilayer structure, or different interfaces of the multilayer structure so as to sandwich the magnetic ceramic layer. It may be provided along.
[0012]
The present invention is also directed to a method of manufacturing a multilayer ceramic substrate as described above.
[0013]
A manufacturing method of a multilayer ceramic substrate according to a first aspect includes a plurality of dielectric green sheets including a dielectric ceramic material, and a thickness of the dielectric green sheet, which is disposed in contact with a specific one of these dielectric green sheets. Along a specific interface between a magnetic green sheet and a laminated structure composed of the dielectric green sheet and the magnetic green sheet, including a magnetic ceramic material that is thinner and does not sinter at the sintering temperature of the dielectric ceramic material. It is characterized by comprising a step of preparing a raw composite laminate including a wiring conductor, and a step of firing the raw composite laminate.
[0014]
A manufacturing method of a multilayer ceramic substrate according to a second aspect includes a plurality of dielectric green sheets including a dielectric ceramic material, and a magnetic body including a magnetic ceramic material that can be sintered at a sintering temperature of the dielectric ceramic material. The green sheet is positioned between the dielectric green sheet and the magnetic green sheet, and is thinner than each thickness of the dielectric green sheet and the magnetic green sheet, and each sintering temperature of the dielectric ceramic material and the magnetic ceramic material. A wiring conductor provided along a specific interface of a laminate structure comprising a dielectric sheet, a magnetic green sheet, and a shrinkage suppression green sheet containing an insulating ceramic material that does not sinter. A step of preparing a raw composite laminate, and a step of firing the raw composite laminate It is characterized in that to obtain.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view schematically showing a part of a multilayer ceramic substrate 1 according to an embodiment of the present invention.
[0016]
The multilayer ceramic substrate 1 includes a plurality of dielectric ceramic layers 2 containing a dielectric ceramic material. The dielectric ceramic material used here is preferably sinterable at a low temperature for the reason described later. Therefore, the dielectric ceramic material preferably contains crystallized glass or a mixture of glass and ceramic. More specifically, for example, a BaO—Al ₂ O ₃ —SiO ₂ low temperature sintered ceramic material is used as the dielectric ceramic material.
[0017]
The multilayer ceramic substrate 1 also includes a magnetic ceramic layer 3. The magnetic ceramic layer 3 is disposed so as to be in contact with a specific one of the dielectric ceramic layers 2. The magnetic ceramic layer 3 contains a magnetic ceramic material that is not sintered at the sintering temperature of the dielectric ceramic material described above in an unsintered state. As this magnetic ceramic material, for example, a Mn—Zn-ferrite-based magnetic ceramic material or a Ni—Zn-ferrite-based magnetic ceramic material is used.
[0018]
In addition, as a result of firing to obtain the multilayer ceramic substrate 1, a part of the material contained in the dielectric ceramic layer 2 has permeated into the magnetic ceramic layer 3. In order to ensure such penetration, the magnetic ceramic layer 3 is made thinner than the dielectric ceramic layer 2.
[0019]
The multilayer ceramic substrate 1 also includes wiring conductors 4 to 13. These wiring conductors 4 to 13 are formed by baking a conductive paste containing a conductive component such as copper, silver or gold.
[0020]
Of the wiring conductors 4 to 13, the wiring conductors 4 and 5 are provided on the outer surface of the multilayer ceramic substrate 1. Further, the wiring conductors 6 to 13 are provided along a specific interface of the laminated structure composed of the dielectric ceramic layer 2 and the magnetic ceramic layer 3.
[0021]
Among the latter wiring conductors 6 to 13 described above, the wiring conductors 7 to 10 and the wiring conductors 11 to 13 are respectively provided along the same interface of the above-described laminated structure. Moreover, the wiring conductors 6 to 10 and the wiring conductors 11 to 13 are provided along different interfaces of the laminated structure so as to sandwich the magnetic ceramic layer 3.
[0022]
Such a multilayer ceramic substrate 1 is manufactured as follows. FIG. 2 is a cross-sectional view schematically showing a part of the raw composite laminate 1a that is to be fired to become the multilayer ceramic substrate 1 in an exploded manner.
[0023]
The raw composite laminate 1a includes a plurality of dielectric green sheets 2a. These dielectric green sheets 2a are to become the dielectric ceramic layer 2 by being fired, and each includes a dielectric ceramic material.
[0024]
The raw composite laminate 1a includes a magnetic green sheet 3a. The magnetic green sheet 3a becomes the magnetic ceramic layer 3 by being fired, and is disposed in contact with the specific dielectric green sheet 2a. The magnetic green sheet 3a is thinner than the dielectric green sheet 2a. The magnetic green sheet 3a includes a magnetic ceramic material that does not sinter at the sintering temperature of the dielectric ceramic material included in the dielectric green sheet 2a.
[0025]
Further, the wiring conductors 4 to 13 are formed on each main surface of the specific one of the dielectric green sheets 2a described above or on the main surface of the magnetic green sheet 3a.
[0026]
By stacking such dielectric green sheets 2a and magnetic green sheets 3a, a raw composite laminate 1a is obtained. This raw composite laminate 1a is then fired to obtain the multilayer ceramic substrate 1 shown in FIG.
[0027]
In the firing step described above, the magnetic green sheet 3a acts to suppress shrinkage of the dielectric green sheet 2a. That is, the magnetic green sheet 3a leaves the magnetic ceramic material contained therein in an unsintered state and does not sinter itself, thereby suppressing shrinkage in the main surface direction of the dielectric green sheet 2a. become.
[0028]
Further, since the magnetic green sheet 3a is not sintered in the firing process as described above, it may cause a problem due to a difference in sintering shrinkage rate or shrinkage behavior with respect to the dielectric green sheet 2a. Therefore, warpage and distortion can be made difficult to occur in the multilayer ceramic substrate 1 after sintering.
[0029]
Moreover, in the obtained multilayer ceramic substrate 1, since the magnetic ceramic layer 3 has the capability to absorb electromagnetic waves, for example, between the wiring conductors 7 to 10 and the wiring conductor located along the same interface. To increase the effect of isolation between the wiring conductors 6 to 10 and the wiring conductors 11 to 13 positioned along the different interfaces so as to sandwich the magnetic ceramic layer 3. Can do.
[0030]
In the multilayer ceramic substrate 1 shown in FIG. 1, the position and number of the magnetic ceramic layers 3 can be appropriately changed.
[0031]
FIG. 3 is a cross-sectional view schematically showing a part of a multilayer ceramic substrate 21 according to another embodiment of the present invention.
[0032]
The multilayer ceramic substrate 21 includes a plurality of dielectric ceramic layers 22 including a dielectric ceramic material. This dielectric ceramic material is preferably sinterable at a low temperature for the reason described later. Therefore, the same dielectric ceramic material contained in the dielectric ceramic layer 2 shown in FIG. 1 can be used.
[0033]
The multilayer ceramic substrate 21 also includes a magnetic ceramic layer 23 containing a magnetic ceramic material. This magnetic ceramic material is preferably sinterable at a low temperature as in the case of the dielectric ceramic material described above. Further, the sintering start temperature of the magnetic ceramic material is preferably selected within about ± 100 ° C. of the sintering start temperature of the dielectric ceramic material, and is a temperature applied to sinter the dielectric ceramic material. It can be sintered under the conditions. In other words, the magnetic ceramic material and the dielectric ceramic material are sintered together in the simultaneous firing step. Therefore, it is preferable that the magnetic ceramic material is composed of, for example, a mixture of glass and ferrite.
[0034]
The multilayer ceramic substrate 21 also includes a shrinkage suppression layer 24 disposed between the dielectric ceramic layer 22 and the magnetic ceramic layer 23. In this embodiment, the shrinkage suppression layer 24 is also disposed between the dielectric ceramic layers 22 adjacent to each other.
[0035]
The shrinkage suppression layer 24 includes an insulating ceramic material that is not sintered at each sintering temperature of the dielectric ceramic material and the magnetic ceramic material described above in an unsintered state. As this insulator ceramic material, for example, alumina or zirconia is advantageously used.
[0036]
Further, in the shrinkage suppression layer 24, as a result of firing to obtain the multilayer ceramic substrate 21, a part of each material included in each of the dielectric ceramic layer 22 and the magnetic ceramic layer 23 in contact with the shrinkage suppression layer 24, In the uppermost shrinkage suppression layer 24, a part of the material contained in the dielectric ceramic layer 22 penetrates. In order to make this permeation more sufficient, the thickness of the shrinkage suppression layer 24 is made thinner than each thickness of the dielectric ceramic layer 22 and the magnetic ceramic layer 23.
[0037]
The multilayer ceramic substrate 21 also includes several wiring conductors 25-36. Among these wiring conductors 25 to 36, the wiring conductors 25 and 26 are provided on the outer surface of the multilayer ceramic substrate 21, and the wiring conductors 27 to 36 are inside the multilayer ceramic substrate 21, and are the dielectric ceramic layer 22. The laminated structure is formed along a specific interface of the magnetic ceramic layer 23 and the shrinkage suppression layer 24.
[0038]
Among the wiring conductors 27 to 36 provided in the above, the wiring conductors 28 to 30, the wiring conductors 31 and 32, the wiring conductors 33 and 34, and the wiring conductors 35 and 36 are respectively the same interface of the above laminated structure. It is provided along. Further, the wiring conductors 27 to 32 and the wiring conductors 33 to 36 are provided along different interfaces of the multilayer structure so as to sandwich the magnetic ceramic layer 23.
[0039]
Also in this embodiment, since the magnetic ceramic layer 23 absorbs electromagnetic waves, for example, between the wiring conductors 28 to 30, between the wiring conductors 31 and 32, between the wiring conductors 33 and 34, and between the wiring conductors 35 and 36. The isolation effect can be increased between the wiring conductors 27 to 32 and the wiring conductors 33 to 36.
[0040]
The multilayer ceramic substrate 21 as described above is manufactured as follows. FIG. 4 is a cross-sectional view showing a part of the raw composite laminate 21a that becomes the multilayer ceramic substrate 21 by being fired.
[0041]
The raw composite laminate 21a includes a plurality of dielectric green sheets 22a. These dielectric green sheets 22a become the above-described dielectric ceramic layer 22 by being fired, and contain a dielectric ceramic material.
[0042]
The raw composite laminate 21a includes a magnetic green sheet 23a. The magnetic green sheet 23a becomes the above-described magnetic ceramic layer 23 by firing, and includes a magnetic ceramic material that can be sintered at the sintering temperature of the dielectric ceramic material.
[0043]
The raw composite laminate 21a includes a shrinkage-suppressing green sheet 24a. The shrinkage-suppressing green sheet 24a becomes the shrinkage-suppressing layer 24 after the firing step, and includes an insulating ceramic material that does not sinter at each sintering temperature of the dielectric ceramic material and the magnetic ceramic material. It is out. The shrinkage-suppressing green sheet 24a is disposed between the dielectric green sheet 22a and the magnetic green sheet 23a or between the adjacent dielectric green sheets 22a. Each thickness of the shrinkage-suppressing green sheet 24a is made thinner than each thickness of the dielectric green sheet 22a and the magnetic green sheet 23a.
[0044]
Further, the above-described wiring conductors 25 to 36 are formed on the specific dielectric green sheet 22a, the magnetic green sheet 23a, or the shrinkage suppressing green sheet 24a.
[0045]
The above-described dielectric green sheet 22a, magnetic green sheet 23a, and shrinkage suppressing green sheet 24a are laminated to obtain a raw composite laminate 21a. This raw composite laminate 21a is then fired, whereby the multilayer ceramic substrate 21 shown in FIG. 3 is obtained.
[0046]
In the firing step described above, the shrinkage-suppressing green sheet 24a leaves the insulating ceramic material contained therein in an unsintered state and does not sinter itself. Therefore, the dielectric green sheet 22a and the magnetic green sheet 23a The shrinkage | contraction in the main surface direction of each is suppressed. Therefore, the difference in the sintering shrinkage rate or the shrinkage behavior between the dielectric green sheet 22a and the magnetic green sheet 23a as described above is first caused by the suppression of the respective shrinkage in this manner. Can be eliminated.
[0047]
Further, since the shrinkage-suppressing green sheet 24a or the shrinkage-suppressing layer 24 that is not sintered is interposed between the dielectric green sheet 22a and the magnetic green sheet 23a, for example, the dielectric green sheet 22a and the magnetic substance Even if a difference in sintering shrinkage rate or shrinkage behavior occurs with the green sheet 23a, the shrinkage-suppressing green sheet 24a or shrinkage suppression layer 24 advantageously absorbs such a difference in sintering shrinkage rate or shrinkage behavior. can do.
[0048]
Thus, this embodiment also advantageously avoids problems resulting from differences in sintering shrinkage.
[0049]
In the multilayer ceramic substrate 21 shown in FIG. 3, the stacking order and number of the dielectric ceramic layer 22, the magnetic ceramic layer 23, and the shrinkage suppression layer 24 can be appropriately changed.
[0050]
【The invention's effect】
As described above, according to the multilayer ceramic substrate according to the present invention, since the magnetic ceramic layer is provided, the isolation effect between the wiring conductors can be enhanced by the electromagnetic wave absorbing action of the magnetic ceramic layer. . Such an isolation effect is caused by the difference in the multilayer structure between a plurality of wiring conductors provided along the same interface of the multilayer structure constituting the multilayer ceramic substrate or by sandwiching the magnetic ceramic layer. It can also work between the wiring conductors provided along the interface.
[0051]
Therefore, according to the present invention, it is possible to improve the high-frequency characteristics related to the wiring conductor in the multilayer ceramic substrate, and it is easy to deal with high-density wiring.
[0052]
In addition, according to the method for manufacturing a multilayer ceramic substrate according to the present invention, the firing is performed in a state where the shrinkage suppression effect is exerted by the magnetic green sheet or the shrinkage suppression green sheet. Problems due to differences in sintering shrinkage rate or shrinkage behavior with the green sheet can be advantageously avoided.
[0053]
Also, when a shrinkage-inhibiting green sheet is placed between the dielectric green sheet and the magnetic green sheet, the difference in sintering shrinkage or shrinkage behavior between the dielectric green sheet and the magnetic green sheet Since the function of absorbing heat can be performed by the shrinkage-suppressing green sheet, problems caused by differences in sintering shrinkage rate or shrinkage behavior can be avoided more reliably.
[0054]
In addition, when the magnetic green sheet exerts a shrinkage-inhibiting action, the magnetic ceramic material contained therein does not sinter, so that no sintering shrinkage occurs in this magnetic green sheet, and therefore the dielectric green sheet The difference in sintering shrinkage rate or shrinkage behavior between them is not a problem.
[0055]
For this reason, according to the method for manufacturing a multilayer ceramic substrate according to the present invention, a large-scale multilayer ceramic substrate such as an RF module can be manufactured without warping or distortion.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a part of a multilayer ceramic substrate 1 according to an embodiment of the present invention.
2 is an exploded cross-sectional view showing a part of a raw composite laminate 1a prepared for manufacturing the multilayer ceramic substrate 1 shown in FIG. 1. FIG.
FIG. 3 is a sectional view schematically showing a part of a multilayer ceramic substrate 21 according to another embodiment of the present invention.
4 is an exploded sectional view showing a part of a raw composite laminate 21a prepared for manufacturing the multilayer ceramic substrate 21 shown in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,21 Multilayer ceramic substrate 2,22 Dielectric ceramic layer 3,23 Magnetic ceramic layer 4-13, 25-36 Wiring conductor 24 Shrinkage suppression layer 1a, 21a Raw composite laminated body 2a, 22a Dielectric green sheet 3a, 23a Magnetic green sheet 24a Green sheet for shrinkage suppression

Claims (10)

A plurality of dielectric ceramic layers comprising a dielectric ceramic material;
A magnetic ceramic material that is disposed in contact with a specific one of the dielectric ceramic layers and is thinner than the thickness of the dielectric ceramic layers and that does not sinter at the sintering temperature of the dielectric ceramic material is included in an unsintered state. And a part of the material contained in the dielectric ceramic layer is infiltrated, a magnetic ceramic layer,
A multilayer ceramic substrate comprising: a wiring conductor provided along a specific interface of a laminated structure including the dielectric ceramic layer and the magnetic ceramic layer. The multilayer ceramic substrate according to claim 1, wherein the plurality of wiring conductors are provided along the same interface of the multilayer structure. The multilayer ceramic substrate according to claim 1 or 2, wherein a plurality of the wiring conductors are provided along different interfaces of the multilayer structure so as to sandwich the magnetic ceramic layer. A plurality of dielectric green sheets including a dielectric ceramic material, and disposed so as to be in contact with a specific one of the dielectric green sheets, being thinner than the thickness of the dielectric green sheets and sintering the dielectric ceramic material A magnetic green sheet containing a magnetic ceramic material that does not sinter at a temperature; and a wiring conductor provided along a specific interface of the dielectric green sheet and the laminated structure composed of the magnetic green sheet. Preparing a raw composite laminate;
And a step of firing the raw composite laminate. A multilayer ceramic substrate obtained by the production method according to claim 4. A plurality of dielectric ceramic layers comprising a dielectric ceramic material;
A magnetic ceramic layer comprising a magnetic ceramic material that can be sintered at a sintering temperature of the dielectric ceramic material;
Each of the dielectric ceramic material and the magnetic ceramic material is disposed between the dielectric ceramic layer and the magnetic ceramic layer, and is thinner than each thickness of the dielectric ceramic layer and the magnetic ceramic layer. A shrinkage suppression layer comprising an insulating ceramic material that is not sintered at temperature in an unsintered state, and a portion of each of the materials contained in each of the dielectric ceramic layer and the magnetic ceramic layer is infiltrated;
A multilayer ceramic substrate comprising: a wiring conductor provided along a specific interface of a laminated structure including the dielectric ceramic layer, the magnetic ceramic layer, and the shrinkage suppression layer. The multilayer ceramic substrate according to claim 6, wherein the plurality of wiring conductors are provided along the same interface of the multilayer structure. The multilayer ceramic substrate according to claim 6 or 7, wherein the plurality of wiring conductors are provided along different interfaces of the multilayer structure so as to sandwich the magnetic ceramic layer. A plurality of dielectric green sheets including a dielectric ceramic material, a magnetic green sheet including a magnetic ceramic material that can be sintered at a sintering temperature of the dielectric ceramic material, the dielectric green sheet, and the magnetic An insulator that is disposed between the dielectric green sheet and the magnetic green sheet and is not sintered at each sintering temperature of the dielectric ceramic material and the magnetic ceramic material. A shrinkage-suppressing green sheet containing a ceramic material; and a wiring conductor provided along a specific interface of the laminated structure including the dielectric green sheet, the magnetic green sheet, and the shrinkage-suppressing green sheet. Preparing a raw composite laminate,
And a step of firing the raw composite laminate. A multilayer ceramic substrate obtained by the production method according to claim 9.

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