JP2990819B2 - Grain boundary insulated semiconductor ceramic multilayer capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain boundary insulated semiconductor ceramic multilayer capacitor, and more particularly to a grain capacitor in which a semiconductor ceramic material and an internal electrode material are simultaneously fired, and the grain boundary layer of the semiconductor ceramic is insulated by a subsequent heat treatment. The present invention relates to a field-insulated semiconductor ceramic multilayer capacitor.

[0002]

2. Description of the Related Art Conventionally, a multilayer ceramic capacitor is manufactured by laminating a dielectric ceramic material and an internal electrode material, firing the material, and then baking an external electrode that is electrically connected to the internal electrode on the end face of the dielectric ceramic. You. In recent years, miniaturization of electronic components has been pursued, and multilayer capacitors have also tended to be smaller and have larger capacities. In multilayer ceramic capacitors,
As a means for reducing the size and increasing the capacity, a method of increasing the capacity by thinning the layer of the dielectric porcelain material is generally used. However, the grain size of the dielectric porcelain is several μm, and there is a limit to thinning the layer. There is. On the other hand, studies have been made to reduce the grain size of the dielectric porcelain in terms of material. However, when the grain size is reduced, the dielectric constant also decreases, and it is difficult to increase the capacity. As a method of increasing the dielectric constant of the dielectric, there is a grain boundary insulated semiconductor porcelain in which only the grain boundaries of the semiconductor porcelain are insulated, and the effective thickness of the dielectric is reduced to increase the capacity. Widely used. To insulate the grain boundaries of these semiconductor porcelains, it is necessary to diffuse oxygen from the surface of the porcelain.

[0003]

However, in a laminate composed of a semiconductor porcelain and an internal electrode, oxygen cannot be sufficiently diffused into the internal electrode due to the internal electrode, so that the grain boundary insulating semiconductor It has been difficult to use porcelain for multilayer capacitors. Therefore, in order to make a multilayer capacitor using grain boundary insulated semiconductor porcelain, after forming a layered space instead of the internal electrode, a grain boundary insulated semiconductor porcelain was made by heat treatment, and the lead melted later as an internal electrode. It has been studied to make a multilayer capacitor by press-fitting such metals into the space, but the press-fitted metal reduces the insulation between the layers of the semiconductor porcelain, resulting in a high incidence of defects due to short circuits. was there.

[0004] Therefore, a main object of the present invention is to provide a highly reliable grain boundary insulated semiconductor ceramic multilayer capacitor. The present inventors studied using a grain boundary insulated semiconductor porcelain having a high apparent dielectric constant to make a highly reliable multilayer capacitor, and found that copper oxide, which is known as an insulating agent for insulating the grain boundaries of the semiconductor porcelain, was used. (CuO). That is, a laminated body is formed with semiconductor porcelain using nickel containing copper as an internal electrode, and copper is oxidized to copper oxide by heat treatment, and this is diffused into the grain boundaries of the semiconductor porcelain. It has been found that grain boundaries can be oxidized. As a result, a grain boundary insulated semiconductor ceramic multilayer capacitor can be manufactured, which has led to the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a grain boundary insulated semiconductor ceramic multilayer capacitor in which the grain boundaries of a semiconductor ceramic of a laminate obtained by laminating and firing a semiconductor ceramic material and an internal electrode material are insulated by heat treatment. , A grain boundary insulated semiconductor ceramic multilayer capacitor using a nickel metal composition containing 0.1 wt% to 20 wt% of copper as an internal electrode material. A grain boundary insulating semiconductor ceramic laminate core according to the present invention
At the capacitor, the semiconductor ceramic material and the internal electrode material are fired.
After heat treatment in an oxygen atmosphere,
Copper in the electrode material is oxidized, and the grain boundaries of the semiconductor porcelain are insulated
Have been.

[0006]

Since the semiconductor ceramic material and the internal electrode material are fired and sintered together, the electrode material does not enter between the grains of the semiconductor ceramic. The firing of the semiconductor porcelain material is generally performed in a reducing atmosphere, but the process of insulating the grain boundaries of the semiconductor porcelain is performed in an oxidizing atmosphere. When insulating grain boundaries in an oxidizing atmosphere with controlled oxygen partial pressure, if a nickel metal composition containing copper is used as an internal electrode material, copper can be selectively oxidized by appropriately selecting the oxygen partial pressure of the atmosphere. For this reason, the grain boundaries of the semiconductor porcelain are selectively oxidized, and the semiconductor porcelain becomes a grain boundary insulating semiconductor porcelain. In addition, it is not possible to selectively oxidize copper or to oxidize nickel of the internal electrode material. Specifically, copper is used as the internal electrode material.
Use nickel metal composition containing 0.1-20% by weight
Is preferred. At this time, if a nickel metal composition containing less than 0.1% by weight of copper is used as the internal electrode material, the grain boundaries of the semiconductor porcelain cannot be sufficiently oxidized, and the insulation resistance of the fired product is low. If a nickel metal composition containing more than 20% by weight of copper is used as the internal electrode material, cracks occur between the internal electrode and the semiconductor porcelain due to oxidative expansion of copper. There is a problem that the firing temperature range of the semiconductor porcelain decreases. In addition, an oxide such as lead, bismuth, or boron, which is generally used when insulating grain boundaries, or an insulating agent obtained by mixing glass with the oxide, is mixed with the fired laminate, and stirred. It is also possible to share heat treatment.

[0007]

According to the present invention, a highly reliable grain boundary insulated semiconductor ceramic multilayer capacitor can be obtained. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments.

[0008]

EXAMPLE First, 15% by weight of a mixed aqueous solution comprising an organic binder, a dispersant and an antifoaming agent was added to the semiconductor ceramic compositions A and B shown in Table 1, and mixed with a 50% by weight water and mixed and pulverized by a ball mill. The slurry was adjusted. This slurry was flowed through a doctor blade to produce a ceramic green sheet having a thickness of 20 μm.

On this ceramic green sheet, as shown in Table 2, an internal electrode paste using nickel (Ni) powder or copper (Cu) powder as the internal electrode composition was applied by a method for manufacturing a conventional multilayer ceramic capacitor. Screen printed. Then, ceramic green sheets were laminated so that the internal electrode paste became 10 layers, and a laminated body obtained by integrating them by using a hot press was obtained. Thereafter, the laminate was cut into a predetermined size to produce a raw chip. After firing, these dimensions are 1.6 mm long and 0.3 mm wide.
It was adjusted to be 8 mm.

Next, the prepared or prepared raw chip was subjected to a binder removal treatment by keeping it at a temperature of 350 ° C. for 2 hours in the air or in an atmosphere in which the oxygen partial pressure was controlled. Then, the raw chip subjected to the binder removal treatment is fired at a temperature of 1250 to 1300 ° C. in a reducing atmosphere in which the oxygen partial pressure is controlled at 10 ⁻⁷ to 10 ⁻²⁰ atm, and the semiconductor chip and the internal electrodes are fired. Was obtained.

Next, the sintered body is subjected to an oxygen partial pressure of 10 ^-2 to
Heat treatment was performed in an oxidizing atmosphere controlled at 10 ⁻⁵ atm to insulate the grain boundaries of the semiconductor porcelain. In this case, for some sintered bodies, heat treatment is performed while mixing an insulating agent in which oxides such as lead, bismuth, and boron are mixed.
The porcelain grain boundaries were insulated. An external electrode material is applied to the end face of the sintered body in which the grain boundaries of the semiconductor porcelain are insulated in this way, and then baked in an atmosphere in which the oxygen partial pressure is controlled, to obtain a grain boundary insulated semiconductor porcelain multilayer capacitor. .

With respect to the obtained grain boundary insulated semiconductor ceramic multilayer capacitor, the capacitance and the dielectric loss were 1 kHz and 1 kHz.
It was measured under the condition of Vrms. The apparent permittivity was calculated from the electrode area and the distance between the electrodes by measuring the area and the distance and the capacitance. Furthermore, insulation resistance IR
Was measured by applying a DC voltage of 50 V. Table 2 shows the measurement results. Those marked with * in Table 2 are out of the scope of the present invention.

In Sample Nos. 1 and 2, since the content of copper in the internal electrode material is small, the insulation of the grain boundaries of the semiconductor porcelain is not sufficient, and the insulation resistance is undesirably low. On the other hand, in sample No. 6, since the content of Cu is large, cracks occur between the internal electrode and the porcelain in the heat treatment after firing, and the insulation resistance is undesirably low. On the other hand, sample number 3,
Reference numerals 4, 5, and 7 each denote a grain boundary insulated semiconductor ceramic multilayer capacitor using an internal electrode material having a copper content within the range of the present invention. Is also high.

In the above-described embodiment, the firing of the laminate and the insulation (oxidation) of the grain boundaries are performed in separate steps, but both may be performed at the same time in the same firing profile.

As described above, according to the present invention, copper is contained in the internal electrode material, and by applying the oxidative diffusion of the internal electrode material, the grain boundary insulation that enables oxygen to diffuse to the internal grain boundaries of the multilayer capacitor is provided. Type semiconductor ceramic multilayer capacitor can be obtained. As a result, the capacity can be easily increased, and the size and the capacity of the multilayer capacitor can be reduced.

[0016]

[Table 1]

[0017]

[Table 2]

Claims (2)

(57) [Claims] 1. A grain boundary insulated semiconductor ceramic multilayer capacitor in which a semiconductor ceramic material and an internal electrode material are laminated and fired to thereby insulate a grain boundary of the semiconductor ceramic by heat treatment, wherein the internal electrode material is 0.1% to 20% of copper
A grain boundary insulated semiconductor ceramic multilayer capacitor characterized by using a nickel metal composition containing 0.1% nickel metal. (2) The semiconductor porcelain material and the internal electrode material
After baking, heat treatment is performed in an oxygen atmosphere.
Thus, the copper in the internal electrode material is oxidized,
The grain boundary insulation type according to claim 1, wherein the grain boundaries of the vessel are insulated.
Semiconductor porcelain multilayer capacitor.