MULTILAYER BODY AND ELECTRONIC COMPONENT

Abstract

A multilayer body includes a multilayer structure including a glass ceramic layer including a glass and a filler and a ferrite layer including a ferrite, in which the glass ceramic layer has a glass content of about 30.0% or more by weight and about 80.0% or less by weight and a filler content of about 20.0% or more by weight and about 70.0% or less by weight, the glass included in the glass ceramic layer includes about 0.5% or more by weight and about 5.0% or less by weight R.sub.2O (R represents at least one selected from the group consisting of Li, Na, and K), about 0% or more by weight and about 5.0% or less by weight Al.sub.2O.sub.3, about 10.0% or more by weight and about 25.0% or less by weight B.sub.2O.sub.3, and about 70.0% or more by weight and about 85.0% or less by weight SiO.sub.2 based on the total weight of the glass, and the filler included in the glass ceramic layer includes at least one of SiO.sub.2 and Al.sub.2O.sub.3 and also includes about 5.0% or more by weight and about 15.0% or less by weight of a ferrite based on the total weight of the glass and the filler.

Claims

1. A multilayer body comprising: a multilayer structure that includes a glass ceramic layer including a glass and a filler and a ferrite layer including a ferrite; wherein the glass ceramic layer has a glass content of about 30.0% or more by weight and about 80.0% or less by weight and a filler content of about 20.0% or more by weight and about 70.0% or less by weight; the glass included in the glass ceramic layer includes about 0.5% or more by weight and about 5.0% or less by weight R.sub.2O, where R represents at least one selected from the group consisting of Li, Na, and K, about 0% or more by weight and about 5.0% or less by weight Al.sub.2O.sub.3, about 10.0% or more by weight and about 25.0% or less by weight B.sub.2O.sub.3, and about 70.0% or more by weight and about 85.0% or less by weight SiO.sub.2 based on the total weight of the glass; and the filler included in the glass ceramic layer includes at least one of SiO.sub.2 and Al.sub.2O.sub.3 and also includes about 5.0% or more by weight and about 15.0% or less by weight of a ferrite based on the total weight of the glass and the filler.

2. The multilayer body according to claim 1, wherein the ferrite included in the glass ceramic layer has a same composition as the ferrite included in the ferrite layer.

3. The multilayer body according to claim 1, wherein each of the ferrite included in the glass ceramic layer and the ferrite included in the ferrite layer is a NiZn-based ferrite.

4. The multilayer body according to claim 1, wherein the multilayer body is a multilayer ceramic substrate.

5. The multilayer body according to claim 1, wherein the multilayer body is a chip component.

6. The multilayer body according to claim 1, wherein the glass ceramic layer is in contact with the ferrite layer.

7. The multilayer body according to claim 1, wherein the multilayer structure is a co-sintered body in which the glass ceramic layer and the ferrite layer are co-sintered.

8. The multilayer body according to claim 1, wherein the ferrite included in the ferrite layer is a ferromagnetic ferrite including a solid solution having a spinel structure.

9. The multilayer body according to claim 1, wherein the ferrite layer includes a filler other than the ferrite.

10. The multilayer body according to claim 9, wherein the ferrite layer has a ferrite content of about 95.0% or more by weight.

11. The multilayer body according to claim 1, wherein the filler included in the glass ceramic layer includes SiO.sub.2 and Al.sub.2O.sub.3.

12. The multilayer body according to claim 11, wherein a SiO.sub.2 content is about 5.0% or more by weight and about 60.0% or less by weight based on the total weight of the glass and the filler, and an Al.sub.2O.sub.3 content is about 0.5% or more by weight and about 10.0% or less by weight based on the total weight of the glass and the filler.

13. The multilayer body according to claim 12, wherein the SiO.sub.2 content is about 20.0% or more by weight and about 40.0% or less by weight based on the total weight of the glass and the filler.

14. The multilayer body according to claim 4, wherein the multilayer ceramic substrate includes the ferrite layer and two of the glass ceramic layers that sandwich the ferrite layer therebetween in a thickness direction of the multilayer ceramic substrate.

15. The multilayer body according to claim 14, further comprising conductive leads provided in or on the glass ceramic layers.

16. The multilayer body according to claim 15, wherein the conductive leads include conductive films and via-hole conductors.

17. The multilayer body according to claim 15, wherein the conductive leads are primarily made of one of silver and copper.

18. The multilayer body according to claim 4, further comprising a coil conductor provided in the ferrite layer.

19. The multilayer body according to claim 18, wherein the coil conductor is primarily made of one of silver and copper.

20. An electronic component comprising the multilayer body according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a schematic cross-sectional view of an example of a multilayer body according to a preferred embodiment of the present invention.

[0022] FIG. 2 is a schematic cross-sectional view of an example of a multilayer ceramic substrate according to a preferred embodiment of the present invention.

[0023] FIG. 3 is a schematic cross-sectional view of an example of an LC filter defined by a chip component according to a preferred embodiment of the present invention.

[0024] FIGS. 4A to 4C are schematic diagrams of a dielectric capacitor produced in each of examples of preferred embodiments of the present invention and comparative examples. FIG. 4A is a sectional view taken in the thickness direction, FIG. 4B is a sectional view taken along a plane through which one electrode extends, and FIG. 4C is a sectional view taken along a plane through which the other electrode extends.

[0025] FIGS. 5A to 5C are schematic diagrams of a co-sintered capacitor produced in each of the examples of preferred embodiments of the present invention and the comparative examples. FIG. 5A is a sectional view taken in the thickness direction, FIG. 5B is a sectional view taken along a plane through which one electrode extends, and FIG. 5C is a sectional view taken along a plane through which the other electrode extends.

[0026] FIGS. 6A and 6B are schematic diagrams of a substrate for evaluating opacity, the substrate being produced in each of the examples of preferred embodiments of the present invention and the comparative examples. FIG. 6A is a sectional view taken in the thickness direction, and FIG. 6B is a sectional view taken a plane through which an electrode extends.

[0027] FIG. 7 is a schematic diagram of a co-sintered body for evaluating delamination, the co-sintered body being produced in each of the examples of preferred embodiments of the present invention and the comparative examples.

[0028] FIG. 8 is a photograph of the exterior of a co-sintered body produced from a sample having a composition within the range of a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Multilayer bodies and electronic components according to preferred embodiments of the present invention will be described below.

[0030] However, the present invention is not limited to the following structures. Various modifications may be appropriately made as long as the gist of the present invention is not changed.

[0031] Preferred embodiments described below are illustrative, and structures indicated in different preferred embodiments may be partially replaced or combined.

[0032] A combination of two or more of individual preferred embodiments of the present invention described below is also included in the present invention.

[0033] FIG. 1 is a schematic cross-sectional view of an example of a preferred embodiment of a multilayer body of the present invention.

[0034] A multilayer body 10 illustrated in FIG. 1 includes a multilayer structure including a glass ceramic layer 1 that includes a glass and a filler and a ferrite layer 2 that includes a ferrite. An intermediate layer is not provided between the glass ceramic layer 1 and the ferrite layer 2. The glass ceramic layer 1 is in contact with the ferrite layer 2. The multilayer body 10 is preferably a co-sintered body formed by co-sintering the glass ceramic layer 1 and the ferrite layer 2, for example.

[0035] In FIG. 1, each of the glass ceramic layer 1 and the ferrite layer 2 is illustrated as a single layer. However, each of the layers may preferably have a multilayer structure including a plurality of layers.

[0036] The ferrite included in the ferrite layer is preferably a ferromagnetic ferrite including a solid solution having a spinel structure. Examples thereof include NiZn-based ferrites (also including NiZnCu-based ferrites), MnZn-based ferrites, MgZn-based ferrites, and NiCo-based ferrites. These ferrites may be included alone or in a combination of two or more. Among ferromagnetic ferrites having a spinel structure, NiZn-based ferrites are preferred, and NiZnCu-based ferrites are more preferred because of their sufficiently high permeability in high frequencies.

[0037] The ferrite layer may include a filler other than the ferrite. The ferrite layer preferably has a ferrite content of about 95.0% or more by weight, more preferably about 100% by weight, for example.

[0038] The glass included in the glass ceramic layer preferably includes, for example, about 0.5% or more by weight and about 5.0% or less by weight R.sub.2O (R represents at least one selected from the group consisting of Li, Na, and K), about 0% or more by weight and about 5.0% or less by weight Al.sub.2O.sub.3, about 10.0% or more by weight and about 25.0% or less by weight B.sub.2O.sub.3, and about 70.0% or more by weight and about 85.0% or less by weight SiO.sub.2 based on the total weight of the glass. Al.sub.2O.sub.3 is an optional component.

[0039] The glass included in the glass ceramic layer may further include impurities. When impurities are included, the content of the impurities is preferably less than about 5.0% by weight, for example.

[0040] The glass ceramic layer preferably has a glass content, of, for example, about 30.0% or more by weight and about 80.0% or less by weight, more preferably about 45.0% or more by weight and about 65.0% or less by weight.

[0041] The filler included in the glass ceramic layer preferably includes at least one of SiO.sub.2 and Al.sub.2O.sub.3, for example. An example of SiO.sub.2 is quartz.

[0042] In this specification, the filler refers to an inorganic additive that is not included in the glass.

[0043] The glass ceramic layer preferably has a filler content of, for example, about 20.0% or more by weight and about 70.0% or less by weight, more preferably about 35.0% or more by weight and about 55.0% or less by weight.

[0044] The SiO.sub.2 content is preferably, for example, about 5.0% or more by weight and about 60.0% or less by weight, more preferably about 20.0% or more by weight and about 40.0% or less by weight based on the total weight of the glass and the filler. The Al.sub.2O.sub.3 content is preferably about 0.5% or more by weight and about 10.0% or less by weight based on the total weight of the glass and the filler.

[0045] The filler included in the glass ceramic layer further includes a ferrite. The ferrite included in the glass ceramic layer is preferably a ferromagnetic ferrite including a solid solution having a spinel structure. Examples thereof include NiZn-based ferrites (including NiZnCu-based ferrites), MnZn-based ferrites, MgZn-based ferrites, and NiCo-based ferrites. These ferrites may be included alone or in a combination of two or more.

[0046] The ferrite included in the glass ceramic layer may have a different composition from the ferrite included in the ferrite layer and preferably has the same composition as the ferrite included in the ferrite layer. In particular, each of the ferrite included in the glass ceramic layer and the ferrite included in the ferrite layer is preferably a NiZn-based ferrite, more preferably a NiZnCu-based ferrite, for example.

[0047] The ferrite content is preferably about 5.0% or more by weight and about 15.0% or less by weight, more preferably about 8.0% or more by weight and about 12.0% or less by weight based on the total weight of the glass and the filler, for example.

[0048] The glass ceramic layer may include a filler (such as ZrO.sub.2) other than SiO.sub.2, Al.sub.2O.sub.3, or the ferrite.

[0049] In the vicinity of the interface between the glass ceramic layer and the ferrite layer (i.e., regions extending from the interface to positions about 1 m from the interface) of the multilayer body according to the present preferred embodiment, their components are diffused because of the junction. Thus, when the compositions of the glass ceramic layer and the ferrite layer are measured, the compositions are measured not in portions in the vicinity of the interface between the glass ceramic layer and the ferrite layer, but in portions remote from the interface.

[0050] To produce the multilayer body 10 illustrated in FIG. 1, glass ceramic sheets for the glass ceramic layer 1 and ferrite sheets for the ferrite layer 2 are prepared.

[0051] The glass ceramic sheets are preferably formed by forming a slurry including a glass powder, a filler powder, an organic binder, and a solvent into sheets by, for example, a doctor blade method. The ferrite sheets are formed by forming a slurry including a ferrite powder, an organic binder, and a solvent into sheets by, for example, a doctor blade method. These slurries may include various additives, such as a plasticizer, for example.

[0052] A predetermined number of the glass ceramic sheets and a predetermined number of the ferrite sheets are stacked and fired to provide the multilayer body 10.

[0053] A multilayer body according to a preferred embodiment of the present invention may be used for a multilayer ceramic substrate, for example.

[0054] FIG. 2 is a schematic cross-sectional view of an example of a multilayer ceramic substrate according to a preferred embodiment of the present invention.

[0055] A multilayer ceramic substrate 20 illustrated in FIG. 2 including a multilayer structure including a ferrite layer 22 and two glass ceramic layers 21 that sandwich the ferrite layer 22 in the thickness direction.

[0056] The multilayer ceramic substrate 20 includes conductive leads provided in or on the glass ceramic layers 21. The conductive leads are used to define passive elements, such as capacitors and inductors or to establish connections, such as electrical connections between elements. As illustrated in FIG. 2, the conductive leads include some conductive films 24, 25, and 26 and some via-hole conductors 27. Preferably, these conductive leads are primarily made of silver or copper.

[0057] The conductive films 24 are provided in or on the glass ceramic layers 21. The conductive films 25 and 26 are provided on one main surface and the other main surface, respectively, of the multilayer ceramic substrate 20. The via-hole conductors 27 are electrically connected to any of the conductive films 24, 25, and 26 and so as to extend through the glass ceramic layers 21 in the thickness direction.

[0058] The multilayer ceramic substrate 20 further includes a coil conductor 28 provided in the ferrite layer 22. Preferably, the coil conductor 28 is primarily made of silver or copper.

[0059] FIG. 2 illustrates an example in which two triple-wound planar coil conductors are vertically arranged to define the coil conductor 28.

[0060] A chip component (not illustrated) is mounted on the one main surface of the multilayer ceramic substrate 20 while being electrically connected to the conductive films 25, resulting in an electronic component including the multilayer ceramic substrate 20. The chip component mounted on the multilayer ceramic substrate 20 may be a multilayer body according to a preferred embodiment of the present invention.

[0061] The conductive films 26 provided on the other main surface of the multilayer ceramic substrate 20 are used as electrical connecting members when the electronic component is mounted on a motherboard (not illustrated).

[0062] The multilayer ceramic substrate may be produced by forming a conductive lead pattern to be formed into the conductive leads on the glass ceramic sheet and forming a coil conductor pattern to be formed into the coil conductor on the ferrite sheet in a method for producing the multilayer body. The multilayer ceramic substrate 20 illustrated in FIG. 2 may be produced, for example, as follows: a predetermined number of the glass ceramic sheets including the conductive leads are arranged on the upper and lower surfaces of a predetermined number of the ferrite sheets including the coil conductor pattern to form a multilayer sheet body, followed by firing the multilayer sheet body.

[0063] The conductive lead pattern and the coil conductor pattern are preferably formed by applying a conductive paste including a powder of metal, such as silver or copper, an organic binder, and a solvent into a predetermined pattern using, for example, a screen printing method. The conductive paste may include various additives, such as a dispersant, for example.

[0064] The firing temperature at which the multilayer sheet body is fired is not particularly limited. For example, a firing temperature of about 1,000 C. or lower may preferably be used. The firing atmosphere is not particularly limited. For example, when a material such as silver, which is not easily oxidized, is used as a conductive material, the firing is preferably performed in an air atmosphere. When a material such as copper, which is easily oxidized, is used, the firing is preferably performed in a low-oxygen atmosphere, such as a nitrogen atmosphere, for example.

[0065] A multilayer body according to a preferred embodiment of the present invention may be used for a chip component, in addition to the foregoing multilayer ceramic substrate.

[0066] FIG. 3 is a schematic cross-sectional view of an example of an LC filter defining a chip component according to a preferred embodiment of the present invention.

[0067] An LC filter 30 illustrated in FIG. 3 has a multilayer structure including a glass ceramic layer 31 and a ferrite layer 32.

[0068] Capacitor electrodes 33 are arranged in the glass ceramic layer 31 so as to face each other, thus defining a capacitor 34. A coil conductor 35 extending in the shape of a coil is provided in the ferrite layer 32, thus defining an inductor 36.

[0069] The LC filter 30 further includes connecting conductors that connect the capacitor 34 to the inductor 36, terminal electrodes defining input-output terminals, and a terminal electrode defining a ground terminal, which are not illustrated in FIG. 3. Of these, the terminal electrodes defining the input-output terminals and the terminal electrode defining the ground terminal are provided on the outer surface of the LC filter 30.

[0070] Examples of a chip component for which the multilayer body according to the present preferred embodiment may be used include capacitors and inductors in addition to LC composite components, such as LC filters, for example.

[0071] A multilayer body according to a preferred embodiment of the present invention may be used to define a component other than the multilayer ceramic substrate or the chip component.

[0072] The structures of multilayer bodies according to preferred embodiments of the present invention are not particularly limited as long as they have the multilayer structure including the glass ceramic layer and the ferrite layer.

[0073] In the multilayer ceramic substrate 20 illustrated in FIG. 2, the ferrite layer 22 is arranged between the two glass ceramic layers 21. However, the multilayer body may have a structure in which a glass ceramic layer is arranged between two ferrite layers. The number of layers stacked is not particularly limited. Any of the glass ceramic layer and the ferrite layer may be arranged on a surface of the multilayer body.

[0074] Examples that more specifically disclose multilayer bodies according to preferred embodiments of the present invention will be described below. The present invention is not limited to these examples only.

[0075] Oxides or carbonates as starting materials were mixed together such that glass compositions listed in Table 1 were satisfied. Each of the resulting mixtures was placed in a Pt crucible and melted for about 3 hours at about 1,400 C. or higher and about 1,600 C. or lower, depending on the glass composition. The resulting molten glasses were quenched and pulverized to provide glass powders for samples. Each of the glass powders was mixed with a corresponding one of filler powders, listed in Table 1, including an alumina powder, a quartz powder, and a calcined NiZnCu-based ferrite powder in proportions listed in Table 1. To the resulting mixtures, a solvent, a binder, and a plasticizer were added. The mixtures were sufficiently stirred to provide slurries. Here, as the solvent, a mixed solution of ethanol and toluene was used. As the binder, a butyral resin was used. As the plasticizer, phthalate was used. The resulting slurries were formed by a doctor blade method into glass ceramic sheets.

[0076] In Table 1, the proportions by weight of alumina, quartz, and the ferrite as a filler are expressed as the proportions by weight based on the total weight of the glass and the filler.

TABLE-US-00001 TABLE 1 Glass Composition (based on 100 Filler of total weight of glass) Total K.sub.2O Al.sub.2O.sub.3 B.sub.2O.sub.3 SiO.sub.2 Content Alumina Quartz Ferrite content Sample [% by [% by [% by [% by [% by [% by [% by [% by [% by No. weight] weight] weight] weight] weight] weight] weight] weight] weight] 1 0.5 0 20.0 79.5 65.0 5.0 20.0 10.0 35.0 2 5.0 0 20.0 75.0 50.0 5.0 35.0 10.0 50.0 3 2.0 0 20.0 78.0 55.0 5.0 30.0 10.0 45.0 4 2.0 5.0 20.0 73.0 55.0 5.0 30.0 10.0 45.0 5 3.0 3.0 10.0 84.0 65.0 5.0 20.0 10.0 35.0 6 2.0 0 25.0 73.0 50.0 5.0 35.0 10.0 50.0 7 3.0 2.0 25.0 70.0 50.0 5.0 35.0 10.0 50.0 8 2.0 0 13.0 85.0 65.0 5.0 20.0 10.0 35.0 9 2.0 0 20.0 78.0 50.0 10.0 30.0 10.0 50.0 10 2.0 0 20.0 78.0 55.0 1.0 34.0 10.0 45.0 11 3.0 0 22.0 75.0 30.0 5.0 55.0 10.0 70.0 12 2.0 0 18.0 80.0 80.0 5.0 5.0 10.0 20.0 13 2.0 0 20.0 78.0 55.0 5.0 30.0 10.0 45.0 14 2.0 0 20.0 78.0 65.0 5.0 15.0 15.0 35.0 15 2.0 0 20.0 78.0 65.0 5.0 25.0 5.0 35.0 16* 0.2 0 20.0 79.8 70.0 5.0 15.0 10.0 30.0 17* 5.5 0 20.0 74.5 45.0 5.0 40.0 10.0 55.0 18* 2.0 10.0 15.0 73.0 55.0 5.0 30.0 10.0 45.0 19* 2.0 0 8.0 90.0 55.0 5.0 30.0 10.0 45.0 20* 2.0 0 28.0 70.0 55.0 5.0 30.0 10.0 45.0 21* 4.0 3.0 25.0 68.0 55.0 5.0 30.0 10.0 45.0 22* 2.0 0 10.0 88.0 55.0 5.0 30.0 10.0 45.0 23* 2.0 0 20.0 78.0 25.0 5.0 60.0 10.0 75.0 24* 2.0 0 20.0 78.0 85.0 2.0 3.0 10.0 15.0 25* 2.0 0 20.0 78.0 65.0 5.0 13.0 17.0 35.0 26* 2.0 0 20.0 78.0 65.0 5.0 27.0 3.0 35.0 27* 2.0 0 20.0 78.0 68.0 5.0 27.0 0 32.0

[0077] In Table 1, the compositions of the samples marked with * are outside the ranges of preferred embodiments of the present invention.

[0078] The same solvent, binder, and plasticizer as described above were added to a calcined NiZnCu-based ferrite powder and sufficiently mixed together to provide a slurry. The slurry was formed by a doctor blade method into ferrite sheets.

[0079] The glass ceramic sheets and the ferrite sheets were subjected to measurements and evaluations.

[0080] Pieces formed by cutting the glass ceramic sheet were stacked and pressure-bonded to form a pressure-bonded body having dimensions of about 50 mmabout 50 mmabout 0.6 mm. The pressure-bonded body was fired at about 900 C. for about 1 hour in air to form a ceramic substrate. The relative dielectric constant .sub.r of the ceramic substrate was measured by a cavity resonator method at a measurement frequency of about 3 GHz. Table 2 lists the relative dielectric constants of the samples. The evaluation criterion is .sub.r4.5.

[0081] FIGS. 4A to 4C are schematic diagrams of a dielectric capacitor produced in examples of preferred embodiments of the present invention and comparative examples.

[0082] An Ag-based electrode paste was applied by printing to pieces formed by cutting the glass ceramic sheet. The resulting pieces were stacked and pressure-bonded so as to have a predetermined thickness, and then fired at about 900 C. for about 1 hour in air to form a dielectric capacitor having dimensions of about 10 mmabout 10 mmabout 1.0 mm (electrode area: about 4 mmabout 4 mm, interelectrode distance: about 30 m).

[0083] FIGS. 5A to 5C are schematic diagrams of a co-sintered capacitor produced in each of the examples of preferred embodiments of the present invention and the comparative examples.

[0084] A co-sintered capacitor including a composite of dielectric and magnetic materials was produced with a glass ceramic sheet and ferrite sheets. The composite having a structure in which the glass ceramic sheet having a thickness of about 90 m after firing was arranged between the ferrite sheets each having a thickness of about 0.5 mm after firing was co-sintered at about 900 C. for about 1 hour in air to form a co-sintered capacitor in which a capacitor was formed only in the middle of the glass ceramic sheet, the co-fired capacitor having dimensions of about 10 mmabout 10 mmabout 1.0 mm (electrode area: about 4 mmabout 4 mm, interelectrode distance: about 30 m).

[0085] The insulation resistance of each of the dielectric capacitor and the co-sintered capacitor was measured with an insulation resistance tester. Table 2 lists the insulation resistance (log IR) of each sample. The evaluation criterion is log IR>10.

[0086] FIGS. 6A and 6B are schematic diagrams of a substrate for evaluating opacity, the substrate being produced in each of the examples of preferred embodiments of the present invention and the comparative examples.

[0087] An Ag-based electrode paste was applied by printing to pieces formed by cutting the glass ceramic sheet. The resulting pieces were stacked and pressure-bonded so as to have a predetermined thickness, and then fired at about 900 C. for about 1 hour in air to form a substrate including an inner electrode therein, the substrate having dimensions of about 10 mmabout 10 mmabout 1.0 mm (electrode area: about 4 mmabout 4 mm). The inner electrode was arranged at a position about 10 m away from and below a surface layer.

[0088] The opacity was checked by visually observing the appearance of the resulting substrate and evaluated according to the following evaluation criteria: x: the built-in inner electrode is seen; and : the built-in inner electrode is not seen. Table 2 lists the results of the samples.

[0089] FIG. 7 is a schematic diagram of a co-sintered body for evaluating delamination, the co-sintered body being produced in each of the examples of preferred embodiments of the present invention and the comparative examples.

[0090] A co-sintered capacitor including a composite of dielectric and magnetic materials was produced with a glass ceramic sheet and ferrite sheets. The composite having a structure in which the glass ceramic sheet having a thickness of about 0.4 mm after firing was arranged between the ferrite sheets each having a thickness of about 0.4 mm after firing was co-sintered at about 900 C. for about 1 hour in air to form a co-sintered body having dimensions of about 15 mmabout 15 mmabout 1.2 mm.

[0091] The appearance of the resulting co-sintered body was observed with a metallographic microscope to check the presence or absence of, for example, delamination and cracking at the interfaces between the layers. Table 2 lists the results of the samples.

TABLE-US-00002 TABLE 2 Co-sintered body Sample Dielectric alone Delamination at No. .sub.r logIR Opacity logIR interface Example 1 1 4.31 11.8 11.8 no Example 2 2 4.28 11.1 10.9 no Example 3 3 4.29 10.9 10.7 no Example 4 4 4.29 11.7 11.7 no Example 5 5 4.31 11.0 11.0 no Example 6 6 4.28 10.7 10.5 no Example 7 7 4.28 11.1 11.1 no Example 8 8 4.31 11.0 10.9 no Example 9 9 4.42 11.4 11.4 no Example 10 10 4.18 11.1 10.9 no Example 11 11 4.23 10.5 10.5 no Example 12 12 4.34 11.8 11.5 no Example 13 13 4.29 11.3 11.3 no Example 14 14 4.47 11.3 11.3 no Example 15 15 4.17 11.5 11.5 no Comparative example 1 16* unsintered yes Comparative example 2 17* 4.21 10.8 8.6 no Comparative example 3 18* 4.25 11.9 9.5 no Comparative example 4 19* unsintered yes Comparative example 5 20* 4.25 10.7 8.3 no Comparative example 6 21* 4.25 10.9 8.9 no Comparative example 7 22* unsintered yes Comparative example 8 23* unsintered yes Comparative example 9 24* 4.23 11.7 8.2 no Comparative example 10 25* 4.53 11.1 11.1 no Comparative example 11 26* 4.12 11.6 X 7.6 no Comparative example 12 27* 4.05 11.6 X yes

[0092] FIG. 8 is a photograph of the exterior of a co-sintered body produced from a sample having a composition within the range of preferred embodiments of the present invention. As with FIG. 7, the co-sintered body illustrated in FIG. 8 has a structure in which a dielectric material (glass ceramic layer) is arranged between two magnetic material pieces (ferrite layers). FIG. 8 indicates that delamination, cracking, and so forth do not occur.

[0093] As is clear from Table 2, each of the multilayer bodies (Examples 1 to 15) including the glass ceramic layer having a composition within the range according to preferred embodiments of the present invention and the ferrite layer satisfied all requirements: a low relative dielectric constant (.sub.rabout 4.5) of the glass ceramic layer, non-occurrence of delamination or the like at the interface, the co-sintered capacitor having insulation resistance (log IR>about 10) comparable to the dielectric capacitor, and low transparency of the glass ceramic layer.

[0094] In contrast, in Comparative example 1 in which the glass had a low K.sub.2O content, Comparative example 4 in which the glass had a low B.sub.2O.sub.3 content and a high SiO.sub.2 content, Comparative example in which the glass had a high SiO.sub.2 content, and Comparative example 8 in which the glass ceramic layer had a low glass content and a high filler content, the dielectric capacitor was not sintered.

[0095] In Comparative example 2 in which the glass had a high K.sub.2O content, Comparative example 3 in which the glass had a high Al.sub.2O.sub.3 content, Comparative example 5 in which the glass had a high B.sub.2O.sub.3 content, Comparative example 6 in which the glass had a low SiO.sub.2 content, and Comparative example 9 in which the glass ceramic layer had a high glass content and a low filler content, the insulation resistance of the co-sintered capacitor was lower than the insulation resistance of the dielectric capacitor.

[0096] In Comparative example 10 in which the glass ceramic layer had a high ferrite content, the glass ceramic layer had a high relative dielectric constant.

[0097] In Comparative example 11 in which the glass ceramic layer had a low ferrite content, the glass ceramic layer had high transparency, and the insulation resistance of the co-sintered capacitor was lower than the insulation resistance of the dielectric capacitor. In Comparative example 12 in which the glass ceramic layer did not include a ferrite, the glass ceramic layer had high transparency, and delamination occurred at the interface.

[0098] Accordingly, the use of the multilayer bodies of preferred embodiments of the present invention will provide electronic components with good characteristics.

[0099] While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.