JPH01262695A - Ceramic multilayer board having built-in capacitor - Google Patents

Abstract

PURPOSE:To enable capacitor elements to have high dielectric constant, by interposing a specified intermediate layers between an insulator layers having conductor patterns and a dielectric layer having conductor patterns so that capacitor elements are contained internally. CONSTITUTION:Internal electrodes 3 are formed within a dielectric layer 21 consisting of a dielectric and insulator layers 22 consisting of an insulating material are formed on the opposite sides of the dielectric layer 21. External electrodes 13 are formed on the external face of each of the insulator layers 22 and connected with the internal electrodes 3 by means of internal interconnections 23 through the dielectric layer 21, intermediate layers 24 and the insulator layers 22. The intermediate layers 24 are formed of a dielectric material having low reactivity with respect to the insulator layers 22, a content different from the dielectric layer 21, and thermal shrinkage property intermediate between those of the insulator layer 22 and the dielectric layer 21. The capacitor elements thus produced are allowed to have a high dielectric constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ceramic multilayer substrate incorporating a capacitor element.

[Conventional technology]

Conventionally, ceramic multilayer substrates with built-in capacitor elements of this type have been made of dielectric materials that exhibit a high dielectric constant, for example, as shown in FIG. An internal electrode 3 is formed within the dielectric layer 21.
The structure was such that an insulator layer 22 disposed on both sides of the device 1 was connected to an external electrode 13 formed on the outside by an internal wiring 23.

[Problem to be solved by the invention]

In the conventional multilayer substrate with a built-in capacitor element described above, the insulating ceramic material of the insulating layer 22 (hereinafter referred to as an insulating material) diffuses into the dielectric ceramic material of the dielectric layer 21 (hereinafter referred to as a dielectric material) and reacts therewith. In addition, due to the difference in thermal shrinkage characteristics between the insulating material and the dielectric material during the firing process, stress is generated at the interface between the insulating layer and the dielectric layer, resulting in peeling of the two.
and cracks in the material occur. Due to these reasons, the dielectric constant (approximately 10,000>
It exhibits a significantly poor dielectric constant (approximately 1500), and furthermore, poor conduction is likely to occur between the insulator layer and the dielectric layer. Therefore, a large area is required to incorporate a large-capacity capacitor, but this not only hinders the miniaturization and high integration that are the characteristics of ceramic multilayer boards with built-in capacitor elements, but also increases insulation by increasing the area. The disadvantage is that alignment of the body and dielectric layers becomes more difficult.

The purpose of the present invention is to shield the diffusion caused by the dielectric material and the insulating material, and to alleviate the stress generated at the interface between the dielectric material and the insulating material due to the difference in thermal shrinkage characteristics between the two. An object of the present invention is to provide a ceramic multilayer substrate with a built-in capacitor element, which allows a capacitor within the ceramic multilayer substrate to exhibit the high dielectric constant that it originally has.

[Means to solve problems,]

A ceramic multilayer board with a built-in capacitor element of the present invention is a ceramic multilayer board with a built-in capacitor element in which a dielectric layer on which a conductor pattern is formed is sandwiched between a plurality of insulator layers on which a conductor pattern is formed. between the dielectric layer and the dielectric layer, the dielectric material has low reactivity with the insulating layer, has heat shrinkage characteristics between the dielectric layer and the insulating layer, and has a composition different from that of the dielectric layer. The structure is characterized in that the intermediate layer is sandwiched.

The intermediate layer made of the dielectric material may be a dielectric material containing manganese/lead niobate, magnesium/lead tungstate, lead titanate, and niobium dioxide, or manganese/lead niobate.

Nickel lead niobate, magnesium tungstic acid,
Dielectric materials containing lead titanate and lead zirconate and manganese-niobium [9], or dielectric materials containing lead magnesium oxide, nickel-lead niobate, and lead titanate can be used.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is an exploded view showing the laminated structure of FIG. 1. In this embodiment, a capacitor constructed within a ceramic multilayer substrate will be described as having a simple pair of internal electrodes facing each other.

In FIG. 1, the ceramic multilayer substrate with a built-in capacitor element of the present invention has a dielectric layer 21 made of a dielectric material, and an insulator layer 22 made of an insulating material on both sides of the dielectric layer 21 on which internal electrodes 3 are formed. are laminated, an external electrode 13 is formed on each outer surface of the insulating layer 22, and an internal wiring 23 connects the internal electrode 3 and the external electrode 13 through the dielectric layer 21, the intermediate layer 5, and the insulating layer 22. do.

FIG. 2 shows an embodiment of the laminated structure of the present invention.
Explain in detail. The dielectric ceramic sheet (hereinafter referred to as dielectric sheet) 1 is made from a dielectric material (hereinafter referred to as dielectric material DY) containing iron/lead niobate, iron/lead tungstate, zinc/lead niobate, and manganese/lead niobate. A sheet with a thickness of about 50 μm formed by adding an organic binder to powder and kneading it and forming it by a doctor blade method,
Via holes 2 for conduction between the upper and lower sheets are provided at desired positions on the dielectric sheet 1. The internal electrode 3 is a dielectric sheet 1
It is formed by depositing a conductive paste containing silver and palladium on one side of the plate.

The dielectric sheet (hereinafter referred to as intermediate layer sheet) 5 constituting the intermediate layer is a dielectric ceramic material (hereinafter referred to as dielectric material DX) containing manganese/lead niobate, magnesium/lead tungstate, lead titanate, and niobium oxide as components. This is a dielectric sheet produced by the same method as dielectric sheet 1, in which a via hole 2 is formed, and 4 indicates a circular or rectangular land surrounding the via hole 2 and covered with a conductive paste.

Insulating ceramic green sheets (hereinafter referred to as insulating sheets) 10 are disposed above and below the dielectric sheet 1, and are mainly composed of aluminum oxide and lead borosilicate glass. 11
are via holes provided at predetermined positions in each insulating sheet 10.

12 is a land formed in the same manner as in the case of the above-mentioned intermediate layer sheet 5, and 13 is an external electrode for a terminal material formed by applying a conductive paste to the outermost layer. The above-mentioned insulation sheet 10
．． The dielectric sheet 1 and the intermediate layer sheet 5 are thermocompression bonded to form a ceramic multilayer substrate with a built-in green capacitor element. By firing this unfired ceramic multilayer substrate with a built-in capacitor element at 800 to 900° C., a ceramic multilayer substrate with a built-in capacitor element is formed. Here, the laminated dielectric sheet 1 is placed on the dielectric layer 21 (Fig. 1), the insulating sheet 10 is placed on the insulating layer 22 (Fig. 1), and the intermediate layer sheet 5 is placed on the intermediate layer 24 (Fig. 1). , are formed by firing, respectively.

As mentioned above, in the conventional ceramic multilayer substrate with a built-in capacitor element, the insulating material in the insulating layer 22 is different from the dielectric layer 21.
Reacts with the dielectric material by interdiffusion with the dielectric material. As a result, the dielectric material changes in quality and becomes a material with a low dielectric constant, and the sinterability also decreases, resulting in a significant reduction in the capacitance that should originally be exhibited by the dielectric ceramic. In addition, microcracks occur in the dielectric layer 21, which has poor mechanical strength due to the difference in heat shrinkage characteristics between the dielectric material and the insulating material, and peeling occurs between the dielectric layer 21 and the insulating layer 22, resulting in This causes a decrease in the capacitor capacity and moisture load resistance of layer 21.

However, in the intermediate layer 24 in the present invention, the component dielectric material DX has lower reactivity with the insulating material than the dielectric material DY.
Significantly reduces the diffusion of insulating and dielectric materials DY, and
As shown in the figure, the heat shrinkage characteristics of the dielectric material DX, which is a component of the intermediate layer, are between those of the insulating material and that of the dielectric material DY. Therefore, in the conventional structure without an intermediate layer as shown in Fig. 5,
While the built-in capacitor has a specific dielectric constant of about 1500, the structure with the intermediate layer 24 of the present invention shown in FIG. The dielectric constant is approximately 6000, which is approximately four times higher.

FIG. 4 is a sectional view of another embodiment of the invention.

In this embodiment, a capacitor formed in a ceramic multilayer substrate has a simple pair of opposing electrodes.

In FIG. 4, in the ceramic multilayer substrate with a built-in capacitor element of the present invention, internal electrodes 3 are formed in an intermediate layer 24 made of a dielectric material DX. A dielectric layer 22 made of a dielectric material DY is formed on each inner surface of the intermediate layer on which the internal electrodes 3 are formed. An insulator layer 22 made of an insulating material is laminated on each outer side of the intermediate layer 24 on which the internal electrode 3 is formed, and the insulator layer 2
An external electrode 13 is formed on each outer surface of the internal electrode 2, and an internal wiring 23 connects the internal electrode 3 and the external electrode 13 through the intermediate M24 and the insulating layer 22. In the second embodiment above, the dielectric sheet and the intermediate layer sheet.

The materials used for the insulating sheet and electrodes are all the same as in the first embodiment. The internal electrodes are formed on the intermediate layer sheet 5 by the same method as that applied to the dielectric sheet 1 of the first embodiment.

Via holes 2 and lands 4 in dielectric sheet 1 are formed. Via hole in insulating sheet 10 4. The method of forming the land 2 and the external electrode 13 is the same as in the first embodiment.

The above-mentioned insulating sheet 10. A ceramic multilayer substrate with a built-in capacitor element is formed by thermocompression bonding the intermediate layer sheet 5 and the dielectric sheet 1 and firing the unfired ceramic multilayer substrate with a built-in capacitor element at 800 to 900°C. The capacitor capacitance can also be obtained from the dielectric constant (relative permittivity: about 2000), and there is an advantage that the capacitor capacitance can be varied based on the difference in relative permittivity between the intermediate layer and the dielectric layer.

In the first and second embodiments described above, dielectric materials containing manganese/lead niobate, magnesium/lead tungstate, lead titanate, and niobium oxide were used as the intermediate layer, but manganese/lead niobate , a dielectric material containing nickel/lead niobate, magnesium/lead tungstate and lead titanate, or a dielectric material containing manganese/lead niobate, magnesium/lead tungstate, lead titanate and lead zirconate, Alternatively, dielectric materials containing manganese/lead niobate, magnesium/lead niobate, nickel/lead niobate, and lead titanate can be similarly used.

[As described in the detailed description of the invention, the present invention uses a dielectric material made of a dielectric material that has low reactivity with the dielectric material and has heat shrinkage characteristics between those of the dielectric material and the insulating material as an intermediate layer, and a dielectric material and an insulating material. By layering between the dielectric material and the insulating material, the diffusion that occurs between the dielectric material and the insulating material is shielded, and the stress that occurs at the interface between the dielectric material and the insulating material due to the difference in thermal shrinkage characteristics between the two materials is alleviated. This has the effect of allowing the capacitor element within the ceramic multilayer substrate to exhibit the high dielectric constant inherent to the dielectric material. Furthermore, by forming internal electrodes in the intermediate layer, there is an effect that the capacitor capacitance can be varied due to the difference in dielectric constant between the intermediate layer and the dielectric layer.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is an exploded perspective view of the embodiment shown in FIG. 1, and FIG. 3 is a dielectric material (DX),
FIG. 4 is a cross-sectional view of another embodiment, and FIG. 5 is a cross-sectional view of a conventional ceramic multilayer substrate with a built-in capacitor element. 1... Dielectric sheet, 2, 11... Via hole, 3
...Internal electrode, 4.12... Land, 5... Intermediate layer sheet, 10... Insulating sheet, 13... External electrode, 21... Dielectric layer, 22... Insulator Layer, 23...
- Internal wiring, 24... Intermediate layer, 31... Shrinkage rate curve of insulating material, 32... Shrinkage rate curve of dielectric material DX, 33.
...Shrinkage rate curve of dielectric material DY.

Claims (1)

[Claims] In a ceramic multilayer substrate with a built-in capacitor element in which a dielectric layer on which a conductor pattern is formed is sandwiched between a plurality of insulator layers on which a conductor pattern is formed, between the insulator layer and the dielectric layer, An intermediate layer is sandwiched between the dielectric layer and the insulating layer, which is made of a dielectric material that has low reactivity with the insulating layer, has a heat shrinkage property, and has a composition different from that of the dielectric layer. Ceramic multilayer board with built-in capacitor element.