JPH05242726A - Conductive paste - Google Patents

Abstract

PURPOSE:To obtain a conductive paste hard to deteriorate with the lapse of time by including metal fine powder, organic nitrogen compounds of make a chelate complex therewith, organic binder and organic solvent. CONSTITUTION:For an example, Pd powder of 50 parts, ethyl cellulose of 4 parts, mineral spirit of 60 parts, butylcalbinal of 30 parts and ethylene diamine of 1 part are kneaded to make a paste, which is used for printing on a ceramic green sheet. After it is dried, 50 layers of it are laminated and compressed for pressure-fitting, and then cut. Electrodes are attached to them to obtain capacity. Metal ion existing on the surface of metal fine powder and organic nitrogen compounds make a chelate complex, so that the reaction of the metal ion with the hydroxyl of organic binder is prevented to reduce the deterioration with the lapse of time of the conductive paste and to increase the dispersibility of the paste.

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 internal electrodes of laminated ceramic capacitors.

[0002]

2. Description of the Related Art A laminated ceramic capacitor is a capacitor having a structure in which dielectric ceramic layers and internal electrodes are alternately laminated, and each dielectric ceramic layer is sandwiched between internal electrodes. Here, the dielectric porcelain layer is formed by firing an unsintered porcelain sheet (ceramic green sheet) at a high temperature to sinter, and the internal electrodes are obtained by firing a conductive paste at a high temperature to form a conductive film. Consists of.

The conductive paste generally comprises fine metal powder dispersed by an organic binder and an organic solvent. Here, the fine metal powder includes precious metals (Pd, A
g) or a base metal (Ni, Cu, etc.) fine powder, acrylic resin, phenol resin, alkyd resin, rosin ester, various celluloses, etc. are used as the organic binder, and the organic solvent is Organic solvents such as alcohols, hydrocarbons, ethers and esters are used.

This conductive paste is printed on a ceramic green sheet in a predetermined pattern by a screen printing method. The ceramic green sheet on which the conductive paste is printed in a predetermined pattern is dried with an organic solvent, and then a plurality of sheets are stacked and pressure-bonded and cut into dice, and then 1
It is fired at a high temperature of 200 to 1400 ° C. By this firing, the organic binder in the conductive paste is burned and removed, and the fine metal powder is sintered to form an internal electrode.

[0005]

By the way, when the internal electrodes are formed by using the conventional conductive paste, the metal ions on the surface of the fine metal powder gradually react with the hydroxyl groups of the organic binder to form the conductive paste. There is a problem that the change with time causes the dispersibility of the fine metal powder in the conductive paste to deteriorate, the thickness of the internal electrode becomes uneven when printing the internal electrode, and the capacity yield decreases and reliability deteriorates. There was a point.

The present invention provides a conductive paste having a small change with time such that the film thickness of the internal electrodes does not become uneven during printing, the capacity yield does not decrease, and the reliability does not deteriorate. It is intended.

[0007]

According to the present invention, a conductive paste prepared by dispersing fine metal powder with an organic binder and an organic solvent contains an organic nitrogen compound which forms a chelate complex with the fine metal powder. This is a solution to the above problems.

Here, as the kind of the metal fine powder, for example, noble metal fine powder such as Pd, Pt, Ag, Au, Ni,
Fine powder of base metal such as Cu can be used. Also,
Examples of the organic binder include acrylic resins, phenol resins, alkyd resins, rosin esters, various celluloses, etc., but are not limited to these, and organic compounds other than these can also be used. As the organic solvent, alcohol type, hydrocarbon type,
A solvent such as an ether type or an ester type can be used.

Additives are generally added to the conductive paste in addition to the above components. As the additive, an oxide such as BaO or TiO ₂ , a ceramic powder having the same quality as the dielectric layer, an organic bentonite, or the like can be used.

As the organic nitrogen compound forming a chelate complex with the fine metal powder, an organic nitrogen compound having -N = N- bond, an organic nitrogen compound having -C = N- and OH bond, -N <and -OH. At least one organic nitrogen compound selected from organic nitrogen compounds having a bond can be mentioned.

Specific examples of the organic nitrogen compound which forms a chelate complex with the fine metal powder include aliphatic amines having hydroxyl groups and their derivatives {ethylenediamine, ethylenediaminetetraacetic acid, triethylenetetramine, N- (2-hydroxyethyl) ethylenediamine. }, Aromatic amines having hydroxyl groups and their derivatives {bis (2,2,6,6,-
Tetramethyl-4-piperidyl) sebacate, N, N '
-Disalicylidene-1,2-propanediamine, N,
N'-disalicylidene-1,2-butanediamine}, hydrazide derivative {1,2,3-benzotriazole, tolyltriazole, decamethylenedicarboxylic acid disalicyloyl hydrazide, 3- (N-salicyloyl) amino-
1,2,4-triazole}, oxime derivative {salicylaldehyde oxime, dimethylglyme oxime, diethylglyme oxime}, other {O-phenanthroline, 2,2′-dipyridine}, NG compound, amine derivative having no hydroxyl group {P , P'-dioctyldiphenylamine, N, N'-diphenyl-P-phenylenediamine} can be mentioned, but organic nitrogen compounds other than these can of course be used as long as they are compounds capable of forming a chelate complex with fine metal powder. Can be used.

The amount of the organic nitrogen compound added to the conductive paste is 0.01-5.
The range of 0 wt% is preferable. If the addition amount of the organic nitrogen compound is less than 0.01 wt%, there is a disadvantage that metal ions remain due to lack of chelate and the dispersibility becomes insufficient. If the addition amount of the organic nitrogen compound exceeds 5.0 wt%, desorption occurs. This is because the binder becomes defective and delamination occurs.

[0013]

In the present invention, the metal ions on the surface of the fine metal powder form a chelate complex with the organic nitrogen compound, and the reaction between the metal ions on the surface of the fine metal powder and the hydroxyl groups of the organic binder is hindered. The change is small,
The dispersibility of the conductive paste is improved.

[0014]

【Example】

Example 1 First, Pd powder (50 parts), ethyl cellulose (4 parts)
Part), mineral spirits (60 parts), butyl carbitol (30 parts), and organic nitrogen compound (1 part) were put into a three-roll mill and sufficiently kneaded to prepare a conductive paste for internal electrodes.

Next, this conductive paste was printed on a barium titanate-based ceramic green sheet by a screen printing method. After the conductive paste is dried, 50 layers of this ceramic green sheet are laminated, pressed and pressed, cut into dice, baked in a baking furnace, and external electrodes are baked to form a laminated ceramic capacitor. did.

Next, regarding this laminated ceramic capacitor,
The standard deviation of acquisition capacity was investigated. Standard deviation of acquisition capacity is 1
It was determined by measuring 000 laminated ceramic capacitors by Hewlett-Packard Company 4278A. The results are shown in Table 1.

This laminated ceramic capacitor was cut along a plane perpendicular to the internal electrode surface, mirror-polished, and observed with an optical microscope to examine the number of delaminations in 100 laminated ceramic capacitors. The results are shown in Table 1.

Comparative Example 1 A conductive paste was prepared under the same conditions as in Example 1 except that an organic nitrogen compound was not added, and a laminated ceramic capacitor was formed under the same conditions as in Example 1 to obtain a laminated ceramic. The standard deviation of the acquired capacity of the capacitors was examined, and the number of delaminations in 100 capacitors was examined. The results are shown in Table 1.

[0019]

[Table 1]

Example 2 A conductive paste was prepared under the same conditions as in Example 1 except that Ni powder was used as the fine metal powder, and a laminated ceramic capacitor was formed under the same conditions as in Example 1 to obtain a laminated ceramic. The standard deviation of the acquired capacity of the capacitors was examined, and the number of delaminations in 100 capacitors was examined. The results are shown in Table 2.

Comparative Example 2 A conductive paste was prepared under the same conditions as in Example 2 except that the organic nitrogen compound was not added, and a laminated porcelain capacitor was formed under the same conditions as in Example 2 to obtain a laminated porcelain. The standard deviation of the acquired capacity of the capacitors was examined, and the number of delaminations in 100 capacitors was examined. The results are shown in Table 2.

[0022]

[Table 2]

From the results shown in Tables 1 and 2, when the organic nitrogen compound forming the chelate complex with the fine metal powder is contained in the conductive paste, the internal electrode film thickness obtained by printing becomes uniform, and the capacity yield and reliability are improved. It can be seen that the sex is improved.

Example 3 The content of the organic nitrogen compound was 0.01 based on the weight of the fine metal powder.
In the range of 5.0 wt% to prepare a conductive paste in the same manner as in Example 1, form a laminated ceramic capacitor in the same manner as in Example 1, and make a laminated ceramic capacitor in the same manner as in Example 1. The standard deviation of the acquisition volume and the number of delaminations were investigated. As a result, when the addition amount of the organic nitrogen compound is less than 0.01 wt%, there is a problem that the chelating agent is insufficient and the dispersibility is insufficient, and when the addition amount of the organic nitrogen compound exceeds 5.0 wt%. The debinding process became defective, and delamination occurred, which was a problem.

[0025]

According to the present invention, the conductive paste forming the internal electrodes contains the fine metal powder and the organic nitrogen compound forming the chelate complex, so that the internal electrode film thickness obtained by printing becomes uniform. This has the effect of improving yield and reliability.

Claims (3)

[Claims] 1. A conductive paste obtained by dispersing metal fine powder with an organic binder and an organic solvent, wherein the conductive paste contains an organic nitrogen compound that forms a chelate complex with the metal fine powder. 2. An organic nitrogen compound having a —N═N— bond, an organic nitrogen compound having a —C═N— and an OH bond, and an organic nitrogen compound which forms a chelate complex with the fine metal powder.
The conductive paste according to claim 1, wherein the conductive paste is at least one organic nitrogen compound selected from N <and an organic nitrogen compound having an -OH bond. 3. The content of the organic nitrogen compound which forms a chelate complex with the fine metal powder is 0.01 to the weight of the fine metal powder.
The conductive paste according to claim 1, which is 5.0 wt%.