JPH02150010A - Laminated porcelain capacitor - Google Patents

Abstract

PURPOSE:To prevent the deterioration in electric characteristics due to defective connection by composing an internal electrode of a base metal and forming a baked electrode layer containing Ag, Cu and glass frit as an external electrode while a plating layer shaped of at least one kind of Ni, Cu, Sn and solder is applied onto the surface of the baked electrode layer. CONSTITUTION:A capacitor chip body 3 formed by laminating a plurality of dielectrics 2, internal electrodes 1 of which are shaped of Ni as a base metal, and external electrodes 4 formed onto the side faces of the body 3 are provided. The external electrode 4 is shaped by a first layer 5 formed by the sintered body of paste consisting of a metal and a glass component, a second layer 6 as a plating layer and a third layer 7. The first layer 5 is composed of a metallic component, which can be baked in atmospheric air, and the glass component. It is desirable that Ag and Cu are included as principal ingredients and a base metal such as Ni, Fe, Co, Cr, etc. is combined as the metallic component. The second layer 6 can be formed by using electroless and electro-plating methods while Ni or Cu is employed as a material, and the third layer 7 is formed while Sn or solder is used as its material by employing the same method.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a multilayer ceramic capacitor.

(Prior Art) A multilayer ceramic capacitor is made by sequentially laminating and firing ceramic green sheets printed with electrode materials as internal electrodes.
, PL, Ag-Pd, and other noble metals were used.

However, in these conventional multilayer ceramic capacitors,
As the number of layers of internal electrodes increases, the ratio of the internal electrodes to the volume of the capacitor increases, which has a large impact on the cost of the capacitor.

For these reasons, various multilayer ceramic capacitors using inexpensive base metals as internal electrodes have been studied recently.For example, base metal materials such as Pes Co are used as internal electrodes, and as external electrodes. Ag, Ag-
Proposed methods include coating and baking a paste made by adding glass frit to noble metal powder such as Pd, and baking a paste made by adding glass frit to metal powder such as COs Cu.

Further, for the purpose of improving solderability when mounting these laminated ceramic capacitors on a circuit board or the like, it is also being considered to further apply Nl plating or solder plating to the surface of the baked electrode.

(Problem to be Solved by the Invention) However, as the external electrode, as in the former case, A
g. When electrode material paste such as Ag-Pd is baked, it does not fit well with the internal electrodes, resulting in poor connection between the internal and external electrodes, resulting in a decrease in capacitance and dielectric loss. Increase was likely to occur.

In addition, as the electrode material for the external electrode, as in the latter case, Ni
s If Co, Cu, etc. are selected, baking them in the atmosphere will oxidize the internal electrodes in contact with the external electrodes, resulting in poor connections or high resistance, resulting in a decrease in capacitance and dielectric loss. This will result in increased losses.

For this reason, Nl is used as the electrode material for the external electrode.

When Go, Cu, etc. were selected, it was necessary to bake in a neutral gas atmosphere such as N2 or ^r, or in a reducing gas atmosphere of N2 mixed with a small amount of 112, but in this way, When baking in a neutral or reducing gas, the vehicles contained in the electrode material paste are not sufficiently decomposed, and the remaining organic matter prevents the densification of the electrode layer and reduces the tensile strength of the electrode layer. There was a problem in which the value decreased.

Therefore, conventionally, before baking the electrode layer, a degreasing process must be performed to remove the vehicle contained in the electrode material, which inevitably complicates the work process.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems of conventional capacitors by using a laminated porcelain material that does not cause deterioration of electrical characteristics due to poor connection, and that allows easy baking of external electrodes in the atmosphere. Our goal is to provide capacitors.

(Means for Solving the Problems) The multilayer ceramic capacitor according to the first invention of the present application has an internal electrode made of a base metal, and an external electrode comprising a baked electrode layer containing Ag, Cu, and glass frit. This is a characteristic feature.

The above-mentioned multilayer ceramic capacitor has, on the above-mentioned baked electrode layer,
It is desirable to further include a plating layer formed of at least one of N1% C1, Sn, and solder.

In the multilayer ceramic capacitor according to the second invention of the present application, the internal electrodes are made of base metal, and the external electrodes are made of Ag and Cu.
It is characterized by comprising a baked electrode layer containing at least one selected from N1% Fe, Co, and Cr and glass frit.

Preferably, this multilayer ceramic capacitor further includes a plating layer formed of at least one of copper, copper, Sn, and solder on the baked electrode layer.

(Function) As described above, in the multilayer ceramic capacitor according to the first invention of the present application, the internal electrode is made of base metal, and the external electrode is provided with a baked electrode layer containing Ag, Cu, and glass frit. Since the Cu contained in the baked electrode layer has good wettability with the base metal of the internal electrode, the connecting portion between the internal electrode and the external electrode is well connected, and at that time, the Ag contained in the baked electrode layer is well connected. This function prevents oxidation of the connecting portion between the internal electrode and external electrode during baking in the air, and oxidation of the Cu contained in the external electrode.

In the multilayer ceramic capacitor according to the second invention of the present application, as described above, the internal electrodes are made of base metals, and the external electrodes are made of Ag, Cu, and Nl.

At least one selected from Pa, 00% Cr
Since it is equipped with a baked electrode layer containing seeds and glass frit, Cu and old F contained in the baked electrode layer are
Since the wettability between es 00% Cr and the base metal of the internal electrode is good, the connection part between the internal electrode and the external electrode is well connected, and at the same time, the A contained in the baked electrode is
The action of g can prevent the oxidation of the connecting portion between the internal electrode and the external electrode during baking in the air, as well as the oxidation of the Cu, old Pe, and GoSCr contained in the external electrode.

Furthermore, if a plating layer formed of at least one of CuSn and solder is applied to the surface of the baked electrode layer of the multilayer ceramic capacitor of the above two inventions, solder wettability and solder resistance during mounting can be improved. can be improved.

(Example) Hereinafter, a multilayer ceramic capacitor according to an example of the present invention will be described with reference to the accompanying drawings.

The drawing is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

Structure of a multilayer ceramic capacitor This multilayer ceramic capacitor includes a capacitor chip main body 3 formed by laminating a plurality of dielectric materials 2 on which internal electrodes 1 are formed using base metals,
The external electrode 4 is formed on the side surface of the external electrode 4.

The external electrode 4 includes a first layer 5 formed of a sintered paste of metal and glass components, and a second layer 5 that is a plated layer.
It consists of a layer 6 and a third layer 7.

The first layer 5 is composed of a metal component that can be easily connected to the internal electrode 1 and can be baked in the air, and a glass component that has good wettability with the metal component.

Specifically, the above-mentioned metal components include Ag as a main component,
Contains at least Cu, and further includes Ni and PC! SCO%O
A combination of base metals such as r is desirable. Further, the above-mentioned glass components are set in consideration of atmospheric baking properties, and can be selected from a wide range of types, such as zinc borosilicate, lead, barium, etc., depending on the application.

The second layer 6 and the third layer 7 improve the wettability to solder, which deteriorates due to metal components being oxidized when the first layer 5 is baked in the air, or improve the wettability and solder resistance. It is intended to improve. Therefore, the second layer 6 is made of N1 or Cu, while the third layer 7 is made of Sn or solder using electroless and electrolytic plating methods.

Method for manufacturing a multilayer ceramic capacitor First, the capacitor chip body 3 is made of N, which is a base metal.
A plurality of dielectric materials 2 on which internal electrodes 1 are formed are laminated with l,
It is formed by firing this.

Next, to explain the external electrode 4, this external electrode 4
The formation of the first layer 5 is carried out by first adjusting the paste for forming the first layer 5. This paste was prepared by mixing Ag powder, Cu powder, and glass powder in a ratio of 10 to 89:10.
After weighing at a ratio of ~70:1 to 20, an organic binder solution is added at a ratio of 20 to 30% based on the total weight, and the mixture is mixed in a three-roll mill. When preparing this paste, at least one powder selected from Fes Co, Fes Co, and Cr may be mixed with the Cu powder so that the total amount thereof is within the range of the blending ratio of the Cu powder.

The paste is applied to the side surface of the fired capacitor chip main body 3 as shown in the drawing, dried, and then baked at 600 to 850°C in the air.
The first layer 5 of the external electrode 4 is formed.

The second layer 6 and the third layer 7 are formed on the first layer 5 by barrel plating, such as electroless plating and electrolytic plating.

Preparation of a sample to confirm the effects of the invention This sample laminated ceramic capacitor using Ni for its internal electrodes is as follows:
For example, Special Publication Showa GO-20850, Special Publication No. 60-20
No. 851, Special Publication No. 81-14607, Special Publication No. 61-1
No. 4808, Special Publication No. 14809, Special Publication No. 61-14809, Special Publication No. 61-14809, Special Publication No. 61-14809
14fs10, Special Publication No. 61-14611, Special Publication No. 8
2-24388, JP 132-131412, JP 62-131413, JP 62-131414
No., JP-A-62-131415, JP-A-82-157
No. 804, JP-A-82-157805, JP-A-132
It is possible to use dielectric ceramic compositions described in JP-A-157806 and JP-A-82-157607.

As disclosed in Japanese Patent Publication No. 80-20851, the dielectric material has a composition formula (Bao, eo C
ao, oh Sro, 04) (Tlo, 8
2 Zro, +g) For the main component consisting of 03,
A glass component containing 1.0% by weight of a glass component consisting of Li20-BaO-CaO-3rO-3102 was prepared. A raw material slurry was prepared from a mixed aqueous solution of a dielectric material, an organic binder, a dispersant, and an antifoaming agent, and a ceramic green sheet with a thickness of 40 μm was obtained using a doctor blade method. After printing the old paste that will become the internal electrodes on this ceramic green sheet, print four sheets so that the internal electrodes face each other.
After laminating 0 ceramic green sheets and pressing them under heat, they were fired at 1.150°C in a reducing atmosphere, and the external dimensions were
Sample chips for evaluation measuring 3.15 mm x 2.45 mm x 1.15 mm were prepared.

An external electrode 4 is formed on the side surface of the evaluation sample chip produced as described above, as described below.
Samples 1 to 38 according to Examples of the present invention were prepared.

In forming the first layer of the external electrode, first prepare powder materials having the composition ratio shown in Table 1, and after mixing them,
An organic binder solution was added to the powder at a ratio of 15 to 35 weight percent and mixed in a three-roll mill to prepare a paste for the first layer of the external electrode. The viscosity is adjusted for one week using an organic solvent. A sample chip for evaluation with this paste applied to the side surface was placed in the air at 600 to 850°C for 60 minutes.
The first layer of the external electrode was formed by baking for about a minute. The film thickness of this first layer after firing was 60 to 80 μm at the plane part and 10 to 30 II m at the five corners.

On this first layer, an electroless or electrolytic plating layer selected from Nl and Cu is provided as a second layer, and further on top of this, as a third layer, electrolytic tin or 7U solder (Sn-
A Pb) plating layer was formed and a sample was produced.

In addition, as shown in Table 1, Comparative Examples 1 to 8 were produced using substantially the same method as the method for producing the samples of the present invention, except that the composition of the paste was changed from that of the present invention.

(Hereinafter, blank spaces) Illustrated Capacitance and Dielectric Loss of Samples and Comparative Example Chip Capacitors obtained as described above were measured at room temperature, frequency lK11z, and input voltage IV. Further, a DC voltage of 100 V was applied for 20 seconds to determine the insulation resistance value Δp1. Furthermore, to evaluate the solder heat resistance, the samples were immersed in solder solutions at 300°C and 330°C for 3 seconds, and the electrical properties and appearance were examined.

Furthermore, as a test to evaluate the adhesion strength of external "txti", a sample was half-attached to a copper wiring glass epoxy board, the sample was pressed from the back, and the strength at breakage was examined.

The results are shown in Table 1.

As can be seen from Table 1, the sample of this example is:
It was satisfactory in all respects: capacitance, loss of one dielectric layer, insulation resistance, half-10 heat resistance, and strength.

On the other hand, the comparative examples had, for example, extremely low capacitance and unsatisfactory strength. In addition, in the comparative examples, other tests were not conducted for those whose capacitance was unsatisfactory.

(Effects of the Invention) As explained above, according to the present invention, not only can the external electrodes of a multilayer ceramic capacitor be easily baked in the atmosphere, but also the multilayer ceramic capacitor as a product can be In addition to having good physical characteristics, the connection strength is also satisfactory.

[Brief explanation of the drawing]

The figure is a sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. 1...Internal electrode 2...Dielectric 4...External electrode 5...First layer 6...Second layer 7...Three people outside the third layer

Claims (3)

[Claims] 1. The internal electrode is made of base metal, and the external electrode is made of Ag.
A multilayer porcelain capacitor comprising a baked electrode layer containing Cu and glass frit. 2. The internal electrode is made of base metal, and the external electrode is made of Ag.
A laminated ceramic capacitor comprising a baked electrode layer containing Cu, at least one selected from Ni, Fe, Co, and Cr, and glass frit. 3. The laminated ceramic capacitor according to claim 1 or 2, further comprising a plating layer formed of at least one of Ni, Cu, Sn, and solder on the baked electrode layer. .