JPH0793228B2 - Rare earth silver conductive paste and electronic parts using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste for forming a conductive coating on a capacitor partial body of a composite part such as a laminated LC filter, and more particularly to a conductive paste which tends to occur during firing of the body. The present invention relates to a silver conductive paste that can prevent the occurrence of a defective appearance of a capacitor portion by preventing the diffusion of the paste into a fired body, and an electronic component using the paste.

[0002]

2. Description of the Related Art In a laminated LC filter, a laminated capacitor portion formed by laminating dielectric layers having electrodes is formed on an upper portion of a laminated inductor portion having a coil for an internal electrode in a ferrite for a magnetic material and an external electrode. Capacitor C with a terminal
The LC circuit of the inductor L and the inductor L is formed by one element.

Generally, in the above capacitor portion, a green sheet layer obtained by applying a dielectric powder made of TiO ₂ , CuO, NiO, MnO _{3 and the} like into a slurry on a base film by a doctor blade method is laminated. The internal electrodes arranged between these layers in order to obtain the capacitance are inserted in a form in which a paste mainly containing Ag is printed on each green sheet layer.

FIGS. 3 (a) to 3 (d) are plan views showing the stacking order of such LC filters from above, and FIG. 3 (a) is a plan view of the blank green sheet 6 located in the surface layer.
2B and 2C show layers in which the conductor 7 of the pattern A and the conductor 8 of the pattern B mainly containing Ag are respectively printed. These patterns are repeatedly laminated, and as shown in FIG. 7D, the required number of lamination sheets 9 for the inductor portion are laminated and integrated underneath. The arrows in the figure indicate the stacking order.

Next, the laminated green sheets are subjected to pressure molding while being heated, and further, external electrode terminals are baked on the sintered body which is cut after being cut into a predetermined chip shape and baked to produce a laminated LC filter. Method is used. It should be noted that, for the sake of explanation, FIG. 3 shows individual chip bodies cut after stacking and pressing the green sheets.

[0006]

[Problems to be Solved by the Invention] Inserted conventional Ag
Ag in an internal electrode (hereinafter referred to as an electrode) made of a conductor using a paste diffuses into a chip element body during firing and promotes sintering of the element body. Since the electrode pattern was inserted in a pattern almost similar to the cut chip shape, no problem occurred. However, when the conventional technique as described above is used for manufacturing a laminated LC filter having a complicated capacitor pattern, the sintering of the element body in contact with the electrode does not occur in the portion not in contact with the electrode, that is, the side of the electrode. Phenomenon that progresses faster than the sintering of the body of the margin part,
As a result, as shown in the perspective view of FIG. 4, a recess 10 having the shape of an electrode pattern is formed on the surface of the sintered body 2 and there is a problem in that it is not desirable in appearance.

Therefore, an object of the present invention is to provide an improved conductive paste and an applied electronic device which do not cause a defective appearance such as a discolored portion or a dent portion in the shape of an electrode pattern on the surface layer of the capacitor portion during firing of the chip element body. It is to provide parts.

[0008]

Means for Solving the Problems As a result of intensive research to solve the above-mentioned problems, the present inventor has found that by adding a rare earth metal oxide powder to a conventional conductive paste mainly composed of Ag, it is The inventors have found that grain growth of the dielectric substrate near the electrodes formed by the conductive paste is suppressed, and have reached the present invention.

That is, the present invention relates to a conductive paste containing Ag powder as a conductive substance, which is a rare earth metal oxide group, more preferably La ₂ O ₃ , Sm ₂ O ₃ and Nd ₂ O _3.
The present invention provides a silver conductive paste in which at least one rare earth metal oxide selected from the group consisting of powders is mixed in an amount of 3 to 10 wt% with respect to Ag powder in the conductive paste, and its applied electronic component, that is, its An applied electronic component having a built-in internal electrode pattern formed of a paste, characterized in that a green sheet having an internal electrode pattern formed of the conductive paste is laminated and fired, and the obtained sintered body is used as an element. The present invention provides an electronic component using a rare earth-containing silver conductive paste.

[0010]

[Function] When the electrode is printed with Ag paste on a green sheet made of TiO ₂ , CuO, NiO and Mn ₃ O ₄ and fired at around 860 ° C., CuO thermally dissociates to release oxygen and the surface becomes Void Ag / C
A solid solution of u ₂ O is made and penetrates into the side margin of the electrode. The Ag / Cu ₂ O solid solution that entered is TiO ₂ , Ni.
It acts as a binder for O and Mn ₃ O ₄ , and accelerates the sintering reaction of these oxides. Therefore, when a chip element body prepared by laminating several green sheets is fired, grain growth of the base material near the electrode progresses faster than other portions, and discoloration of the electrode shape or the surface of the obtained sintered body occurs. It was speculated that electrode-shaped depressions would occur.

Therefore, in the present invention, it was predicted that mixing the rare earth metal oxide powder into the Ag paste could prevent the appearance of the sintered body from being defective, and a study was conducted to confirm that the prediction was correct. is there. This is for the following reason. That is, the melting point of the rare earth metal oxide is higher than the melting point of Ag (960 ° C.), and since the rare earth metal is a base metal far less than Ag, the rare earth metal oxide is reduced in the molten Ag. Instead, it should be suspended as it is in powder form. Further, all the rare earth metals are weak magnetic materials like Mn and have similar electromagnetic characteristics. Therefore, an electrode is printed on the green sheet having the above composition with an Ag paste mixed with a rare earth metal oxide powder, and when the electrode is fired, TiO ₂ , CuO, N
rare earth metal oxide powder in the paste between iO and Mn ₃ O ₄ powder particles, since entering the form of a solid particle with Ag · Cu ₂ O and a half molten state thereof, the amount of intrusion Ag · Cu ₂ O and a half molten state thereof is The function of the Ag.Cu ₂ O semi-molten state as a binder is suppressed, and only the grain growth of the base material near the electrode is prevented from proceeding. Moreover, since the properties of the rare earth metal oxide are similar to those of NiO and Mn ₃ O ₄ , it is considered that the sinterability and the mechanical properties such as shrinkage rate and strength of the sintered body and the dielectric properties are not affected. To be

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by the following examples.

[0013]

Example 1 Commercially available TiO ₂ , CuO, NiO and M
Each raw material powder made of n ₃ O ₄ was wet mixed in a required ratio by a ball mill, an organic binder was further added, and the mixture was sufficiently mixed in the same ball mill to form a slurry, and a ceramic green sheet was prepared by a doctor blade method. On the other hand, commercially available Ag powder was replaced with La ₂ O ₃ powder in Table 1.
After mixing and stirring at the ratios shown in Table 1, ethyl cellulose as an organic binder, α-terpineol and butyl carbitol acetate as a solvent were mixed in the same ratio as shown in Table 1 to prepare a paste.

On the green sheet prepared as described above,
The electrode pattern was screen-printed using the prepared Ag paste. Then, 6 sheets of these sheets are laminated,
A blank sheet is placed on each of the upper and lower sides, and 120 ℃
While maintaining the pressure on the substrate, the pressure was applied to 300 kg / cm ² to perform thermocompression bonding, and the chip size was cut. The chip body thus obtained was heated to 500 ° C. at a temperature rising rate of 10 ° C./min in the air, held at the same temperature for 10 minutes, and then cooled to room temperature at a cooling rate of 10 ° C./min to remove the organic binder. Burned off. Then, the heating rate is 5 ℃ / min.
Then, the temperature is raised to 860 ° C., and the temperature is maintained for 1 hour. Then, it is cooled to room temperature at a cooling rate of 5 ° C./min to obtain a sintered body. Was prepared (FIG. 1).

With respect to the sintered body 2 produced as described above, the difference between the electrode portion 3 and the margin portion 4 of the surface layer, that is, the depression is measured using the thickness measuring instrument 5 as shown in FIG. The results are also shown in Table 1. The measurement was performed 3 times and the average value was recorded.

[0016]

[Table 1]

The following findings were obtained from the results shown in Table 1. The depression of the electrode portion could be easily confirmed with the naked eye for the electrodes of sample Nos. 1 and 2, but could not be confirmed with the naked eye for the electrodes of sample Nos. 3 to 6 with great care. In the electrodes of sample Nos. 3 to 5, the chip surface was burnt uniformly and no color difference was generated, but in the electrode of sample No. 6, the sintering of the electrode part was delayed from the side margin part, There was a phenomenon that the part was burnt white. That is, when the amount of La ₂ O ₃ added to Ag is 3 wt% or less, the effect of reducing the depression of the electrode portion is small, and when it is 10 wt% or more, the sintering rate is different, which is not preferable in appearance, so 3 to 10 wt% is an appropriate amount. You can say that.

[0018]

Example 2 Sm ₂ O ₃ or Nd which is a member of La ₂ O _3
2 O ₃ was used instead of La ₂ O ₃ , TiO ₂ , Cu
A sintered body was produced in the same manner as in Example 1 except that a green sheet was produced from a raw material powder obtained by adding borosilicate glass to O, NiO and Mn ₃ O ₄ . The same test as in Example 1 was performed on the produced sintered body, and the results are shown in Table 2.

[0019]

[Table 2]

[0020] As can be seen from Table 2, even if the addition of La ₂ O ₃ and Sm ₂ O ₃ or Nd ₂ O ₃ of cognate Ag paste was obtained the same effects as in Example 1. Also,
It has been confirmed that the conductive paste of the present invention suppresses the depression of the electrode portion even when a glass sheet containing a glass component such as borosilicate glass is used as the green sheet.

[0021]

As a result of the development of the present invention, by only using a paste prepared by adding a rare earth metal oxide to a conventional silver paste, the sintering rate of the base substrate near the electrodes can be suppressed and the sintering rate of the entire surface of the substrate can be suppressed. The problem that occurred when using the conventional Ag paste was improved by making it possible to eliminate the occurrence of the change in the color of the electrode shape type on the substrate surface and the occurrence of depressions in the same part due to this. Facilitated the production of a sintered substrate having a complicated pattern.

[Brief description of drawings]

FIG. 1 is a perspective view showing a chip incorporating an electrode pattern formed of a rare earth metal oxide-containing silver conductive paste of the present invention.

FIG. 2 is a perspective view showing an aspect in which unevenness on the surface of a sintered body containing an electrode pattern formed by the rare earth metal oxide-containing silver conductive paste of the present invention is measured.

FIG. 3 is a plan view showing step by step a stacking procedure of sheets when manufacturing an inductor.

FIG. 4 is a perspective view showing a sintered body containing an electrode pattern formed of a conventional conductive paste.

[Explanation of symbols]

 1 ... External electrode 2 ... Sintered body 3 ... Electrode section 4 ... Margin section 5 ... Dimple measuring device 6 ... Blank green sheet 7 ... Pattern A conductor 8 ... Pattern B conductor 9 Laminating sheet for inductor part 10 Cavity

Claims (4)

[Claims] 1. A rare earth-containing silver conductive paste, characterized in that 3 to 10 wt% of at least one oxide of a rare earth metal is blended with a conductive paste containing Ag powder as a main component, based on the amount of Ag powder. 2. The rare earth metal oxide is La ₂ O ₃ or S.
The rare earth-containing silver conductive paste according to claim 1, which is at least one selected from the group consisting of m ₂ O ₃ and Nd ₂ O ₃ . 3. An electronic component having a thin film conductor obtained by applying a silver conductive paste and then baking the silver conductive paste on the surface or in the interior thereof, wherein the silver conductive paste is at least one of conductive powders containing Ag powder as a main component. An electronic component, characterized by being a rare earth metal-containing silver conductive paste containing 3 to 10 wt% of the rare earth metal oxide of 3) with respect to the amount of Ag powder. 4. The rare earth metal oxide is La ₂ O ₃ , S.
The electronic component according to claim 3, which is at least one selected from the group consisting of m ₂ O ₃ and Nd ₂ O ₃ .