JPS60175307A - Conductive paste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a conductive paste, and particularly to a conductive paste, a piezoelectric material,
It relates to a conductive paste used for external or internal electrodes of ceramic electronic components such as ceramic capacitors.

[Technical background of the invention and its problems]

Ceramic electronic components such as varistors have recently tended to have a larger capacity by having a laminated structure, and as a result, the area of their internal electrodes, etc. increases. For this reason,
It is no exaggeration to say that the price of ceramic electronic components is determined by the cost of the electrode material.

By the way, l'id is a conductive paste conventionally used for electrodes of the ceramic electronic components.

Precious metal powder such as Ag, βd-AgsF'' is used as a conductive material, and a mixture of binder, solvent, glass frit, etc. is used.
It has a resistivity on the order of 0-5Ω, and is characterized by being resistant to seizure and oxidizing atmosphere of the material used. However, multilayer capacitors aimed at increasing capacity! R-layer piezoelectric material.

When used as an internal electrode of a laminated ceramic electronic component such as a laminated Paris, the thermal expansion coefficient of the conductor paste is significantly different from that of the ceramic, so it has the drawback of being prone to cracking and warping.

Further, since the conductive material constituting the conductive paste is made only of expensive noble metals, there is a drawback that the cost of the multilayer ceramic electronic component increases significantly due to an increase in the internal electrode area as the capacity increases.

For this reason, the conductive material is injected into the conductive material.

For example, in the case of capacitors together with solvent and glass frit,
A conductive paste containing the same ceramic material as the dielectric layer has been developed (Japanese Patent Laid-Open No. 128916/1983). However, the table shows that in such conductor yeast, if the amount of ceramic mixed in is increased to bring the coefficient of thermal expansion closer to that of the ceramic used in multilayer ceramic electronic components,
The resistivity becomes high, and if the resistivity is lowered by suppressing the amount of ceramic mixed in, the coefficient of thermal expansion of the electronic component differs greatly from that of the ceramic, resulting in cracks and the like.

[Purpose of the invention]

It is an object of the present invention to provide an inexpensive conductive paste that has low resistivity, is resistant to oxidizing atmospheres, has a small coefficient of thermal expansion, and has good bonding properties with ceramic porcelain.

[Summary of the invention]

As a result of examining various oxides with excellent conductivity, the present inventors noticed that oxides based on BaPbO have low resistivity and a coefficient of thermal expansion similar to that of ceramic porcelain. By mixing and yeasting oxide powder, we can create an inexpensive conductive paste that has low resistivity, is resistant to oxidizing atmospheres, has a small coefficient of thermal expansion, and has good bonding properties with ceramic porcelain. I found it.

In addition, it has been found that it is especially effective to use the conductive oxide powder to partially replace the metal powder.

That is, the present invention provides Ba1Rkl++x Os (however, 0<X≦0.2)
or (13al-yA)' ) (Pb5-z j3z
) It is characterized by containing at least one kind selected from conductive oxide powders represented by Os as a conductive material.

The conductive oxide powder functions to lower the thermal expansion coefficient of the conductive paste and improve bondability with ceramic porcelain. One such oxide powder, BaF! b++x
Os (however, when 0<x≦0.2), X is 0.2
If it exceeds , a two-phase structure is formed and the resistivity becomes high. In order to supplement the conductivity of this conductive oxide, metal powder can also be used as a conductive material.

As this metal powder, in addition to noble metal powders such as (7T, rd, Ag, etc.), N'+W, Mo, etc. can be used.For example, when used as internal electrodes of multilayer capacitors, multilayer varistors, etc., integrally sintered To be done, J?
It is preferable to use noble metal powder such as ttrJiAg+Au. At this time Ft.

PdpAg alone may be used, for example, pd-Ag
There is no need to mention that it may be used as an alloy such as. Another type of oxide powder is (Ba+-yA)'
), (Pbx-zBZ)Os, y.

If 2 exceeds 0.3, the stability of the structure will decrease and the resistance will increase.

Conductive yeast contains a binder, a solvent, a glass frit, etc. as is generally done, but it is desirable that the amount of the conductive oxide powder in the conductive material ranges from 20 to 90% by weight. . The reason for this is that when the amount of conductive oxide powder blended exceeds 90% by weight, the resistivity of the conductive yeast increases, but when the amount is less than 20% by weight, the coefficient of thermal expansion cannot be sufficiently reduced. Therefore, it becomes difficult to sufficiently improve the bondability with ceramic porcelain.

[Embodiments of the invention]

Next, the present invention will be explained in detail.

Examples 1 to 17 BaCOs y17t) 304 y 5btOa Weighed and prepared so that the composition after calcination would be as shown in Table 1 below, mixed uniformly in a ball mill, dried, and placed in an alumina crucible at about 900°C for 30 minutes. The mixture was calcined in an oxygen flow for 1 hour, further ground and mixed in a ball mill, and then calcined again at about 900° C. for 3 hours in an oxygen 70°C atmosphere. Next, grind with a ball mill,
The mixture was mixed and dried to produce three types of conductive oxide powders shown in Table 1. Next, add ethyl cellulose to these oxide powders.

Three types of conductive pastes were made by adding glass frit and terpineol.

Examples 4-19 BaCOs I Pbs'4*, [, t, COs
s La208y Cent pSnO,, ZnO, F
e2O3J CoC0,)Sb203 was weighed and mixed so that the composition after calcining would be as shown in Tables 2 and 3 below, mixed uniformly in a ball mill, dried, and placed in an alumina crucible at approximately 900°C for 3 hours. , calcined in an oxygen flow, further pulverized once in a ball mill, lengthened, and then heated again to about -9'0-σ℃-
It was calcined in an acidic flow for 3 hours. Subsequently, the powders were ground in a ball mill, mixed, and dried to produce 13 types of conductive oxide powders shown in Tables 2 and 3. Continuing,
These oxide powders were added to the noble metal powder in the proportions shown in Tables 2 and 3, and after mixing, 16 kinds of conductive pastes were prepared including ethyl cellulose, glass 7 liters, and terpineol.

Use a screen to measure each conductive paste obtained 7 x 1
0/'c), pre-dried at 100°C for 30 minutes, and baked at 700°C in the air for 30 minutes to form a conductive layer, and the resistivity of these conductive layers was measured using the DC four-terminal method. did. These results are also listed in Tables 1 to 3. In addition, q! of Examples 4 to 19! The thermal expansion coefficient of the r-electric layer was measured, and the results are also listed in Tables 2 and 3.

Table 1 As shown in Tables 1 to 3 above, the conductive paste of the present invention has a low resistivity, and even when it contains metal powder (second
Table, Table 3) For example, alumina substrate (thermal expansion coefficient 3
It can be seen that the material has a coefficient of thermal expansion similar to that of ceramic materials, such as 10-'/°C to 7 x 10-'/°C).

If only the purpose of matching the thermal expansion coefficients is considered as in the conventional case, it is possible to mix A7203. For comparison, we investigated the case where ANOZOS was mixed (the weight ratio of AAOs and Ag was 426), and it was found that the coefficient of thermal expansion was s The resistivity was 1QllJ7m or more, and it could not be used as a conductive paste.

In addition, a conductive layer was formed using a conductive paste in which the mixing ratio of Ag powder and Ba1qbO powder was changed in the same manner as in the example, and the resistivity was measured using the four-terminal method.
The characteristic diagram shown was obtained. As is clear from this figure, Ba
Even if P, bO, powder is added up to 90% by weight, the resistivity remains 10.
It is sufficiently small, less than Ω.

It is particularly suitable to use the above-mentioned conductive paste as an internal electrode of a 4V star, a multilayer piezoelectric element, or a multilayer capacitor by laminating the same and sintering them together.

〔Effect of the invention〕

As detailed above (according to the present invention, it has a low resistivity,
It is resistant to oxidizing atmospheres, has a small coefficient of thermal expansion, has good bonding properties with ceramic porcelain, and is low cost.
Multilayer capacitor.

A conductive paste suitable as an electrode material for laminated ceramic electronic components such as laminated piezoelectric bodies and laminated varistors can be provided. It is particularly effective when used as an internal electrode of such a laminated component and integrally sintered the ceramic layer and the electrode.

[Brief explanation of drawings]

The figure is a characteristic diagram showing the relationship between the blending amount of BaPbO3 and the resistivity of a conductive layer made of a conductive layer in an example of the present invention. Applicant's representative Patent attorney Takehiko Suzue Ag+2, iJ
i & ltb of BaPbO3* (fi°/,)---
One------

Claims (1)

[Claims] (1) BaFlb++xOs (where O<X≦0.2
) or (Bat-yAy)(Pb+-zBZ)Os, as a conductive material. f2) BaPk'++zos (however, O< x≦0.
2) Also) -! (Ba+-yAy) (Pl)t-zBZ
) A conductive paste containing at least one kind selected from conductive oxide powders represented by os and metal powder as conductive materials. (3) As a metal powder, A u e A g + F?
The conductive paste according to claim 2, characterized in that at least one selected from d and pt is used. (4) The conductive paste according to claim 2, wherein the conductive oxide powder is blended in a proportion of 20 to 90% by weight and the metal powder is blended in a proportion of 10 to 80% by weight.