JPH01304717A - Conductive paint for multilayer capacitor internal electrodes - 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] Sad 1 Yu! Warp 111 The present invention relates to a conductive paint for forming internal electrodes of a ceramic multilayer capacitor.

In general, multilayer capacitors are manufactured by alternately stacking several to dozens of unfired ceramic dielectric layers and internal electrode layers, sintering them at high temperatures, and providing external terminals. . The dielectric material used is a ceramic powder such as composite herovskite containing barium titanate, titanium oxide, and lead mixed with an organic binder to form a slurry and formed into a sheet by a method such as a doctor blade method. The internal electrode material is made by blending conductive powders such as platinum, palladium, gold, silver, nickel, copper, and mixtures and alloys thereof with inorganic oxide additives as necessary, and dispersing them in an organic vehicle. A composition made into a paint is used. Usually, this conductive paint is screen printed on the unfired dielectric sheet to form an internal electrode layer, which is stacked and molded under heat and pressure, cut into chips, and then fired to a predetermined profile. The capacitor body has an integrated structure.

However, during the firing of multilayer capacitors, delamination (c) often occurs between the internal electrodes and the dielectric ceramic layer, resulting in a decrease in capacitance and the occurrence of thermal cracks due to thermal changes during soldering. This has become a big problem. Although the cause of delamination has not yet been fully elucidated, the occurrence rate of delamination is due to the material system, that is, internal '! It varies depending on manufacturing conditions such as the 4-electrode material and dielectric material, the number of laminated layers and size of the capacitor, lamination conditions, firing conditions, etc., and the manufacturing conditions must be extremely strictly controlled for barium titanate-based high laminated products, which have the highest occurrence rate. However, it is difficult to reduce the incidence to zero, and countermeasures against delamination are an important issue in order to improve productivity and quality. Various measures have been taken to prevent delamination, and in Japanese Patent Application Laid-Open No. 136212/1983, the same organic binder as that of the dielectric material is used as the organic binder of the internal electrode material. Although this suppresses delamination to some extent, delamination still occurs depending on the firing conditions, and the effect cannot be said to be sufficient. It has been described that delamination can be suppressed by adding dielectric ceramic powder to 44 [1], but this method deteriorates the continuity of the internal electrode layer and meets the recent demand for thinner internal electrode layers. It is also undesirable from this point of view.

An objective of the present invention is to effectively prevent the occurrence of delamination during firing of a multilayer capacitor by using an internal electrode material having a specific composition.

In the present invention, (a) 100 parts of conductive powder, (b) 0.02 to 0.8 parts by weight of a titanate coupling agent in terms of metal, and (c) an organic vehicle. A conductive paint for the inside of a multilayer capacitor made by dispersing the inside of a multilayer capacitor.

2. The conductive paint for internal electrodes of a multilayer capacitor according to claim 1, wherein the surface of the conductive powder is coated with a titanate coupling agent.

3 (a) 100 parts by weight of conductive powder and (b) a mixture of 0.02 to 0.8 parts by weight of a titanate coupling agent and barium organic acid salt in terms of metal are dispersed in (c) an organic vehicle. Conductive paint for internal electrodes of multilayer capacitors.

4. The conductive paint for internal electrodes of a multilayer capacitor according to claim 3, wherein either the titanate coupling agent or the barium organic acid salt is coated on the surface of the conductive powder, and the other is dispersed in an organic vehicle.

5. Claim 3, wherein the surface of the conductive powder is coated with a mixture of a titanate coupling agent and a barium organic acid salt.
This is the "conductive paint for electrodes" inside the multilayer capacitor as described.

Examples of titanate coupling agents include isopropyltriisostearoyltitanate, isopropyltri(N-aminoethyl-aminoethyl)titanate, isopropyltrioctanoyltitanate, isopropyldimethacrylisostearoyltitanate, isopropylisostearoyldiacryltitanate, and isopropyltrictitanate. Milphenyl titanate and the like are used.

Examples of barium organic acid salts include barium naphthenate, barium octylate, barium stearate, barium oxalosuccinate, and the like.

These metal organic compounds may be simply added and mixed into the paint, but they may also be used by coating the surface of the conductive powder in advance.

■ In the paint of the present invention, by using a titanate coupling agent or a mixture of a titanate coupling agent and a barium organic acid salt (hereinafter referred to as "metal organic compound 1") together with a conductive powder, it is possible to In other words, in the case of conventional internal electrode paints, delamination occurs even if the firing conditions are controlled very strictly, but by adding a metal-organic compound, delamination can be easily prevented. It is possible to reduce the incidence to 0.The amount of the metal organic compound blended is preferably about 0.02 to 0.8 parts by weight based on the conductive powder in terms of metal, and from 0.021! parts by weight. If it is less than 0.8 parts by weight, the effect will not be sufficient, and if it is more than 0.8 parts by weight, problems will occur with the baking rack.A range of 0.05 to 0.5 parts by weight is particularly desirable.

The reason why metal-organic compounds are effective in suppressing the occurrence of delamination is that when the laminate is fired, the metal-organic compounds act like an adhesive between the internal electrodes and the dielectric layer, preventing them from peeling off. This is thought to be for the purpose of In addition, the metal organic compound has an excellent effect of suppressing the oxidation swelling of palladium when, for example, palladium powder is used as the conductive powder, and this effect also has an excellent effect of preventing the occurrence of delamination. It is considered that after firing, the metal organic compound ultimately exists in the form of metal oxide in the t-electrode film.

In addition to adding the metal organic compound to the paint as it is, the same effect can be obtained by coating the surface of the conductive powder in advance. The coating treatment may be performed by any method. For example, in a dry method, the conductive powder is premixed in a mixer, and then the required amount of the metal organic compound is dropped and mixed. In the wet method, the conductive powder is dispersed in water or an organic solvent, and the required amount of the metal organic compound is added dropwise with sufficient stirring, followed by filtration, drying, etc.
Alternatively, there is a method in which a conductive powder is mixed and dispersed in a solution of a metal organic compound, and then filtered and dried.

There are no particular limitations on the organic vehicle used in the present invention (although it is possible to use those commonly used in the internal electrode coating of multilayer capacitors).

The conductive paint of the present invention may also contain metal oxides, organic bentonite, and the like, which are conventionally added for the purpose of preventing cracks and the like.

Cold ■ Yo Example 1 Palladium powder 100 parts by weight Titanate coupling agent 1.0 parts by weight (0.05 parts by weight in terms of metal Ti) Ethyl cellulose 7 parts by weight Terpineol 30 parts by weight! kerosene
47 11* Isopropyl triisostearoyl titanate, Ti content 5% The above composition was kneaded to produce a paste-like conductive paint.

This conductive paint was screen-printed in a predetermined pattern on a BaTiOs-based dielectric green sheet, and after drying,
The layers were laminated, pressure bonded, and cut into a predetermined size to produce an unfired multilayer capacitor chip.

When this chip was heated at a heating rate of 200°C/hour and fired by holding it at a maximum temperature of 1350°C for 2 hours, the occurrence rate of delamination was investigated and found to be 0.
Met.

Examples 2 to 4 Conductive paints were obtained in the same manner as in Example IMI, except that the amounts of the titanate coupling agent and kerosene were as shown in Table 1. Multilayer capacitors were manufactured in the same manner, and the incidence of delamination is also shown in Table 1.

Example 5 0.8 parts by weight of a titanate coupling agent and 1.3 parts by weight of barium naphthenate (Ba content 9%) were blended,
A conductive paint was obtained in the same manner as in Example 1 except that the amount of kerosene was changed to 46 parts by weight. A multilayer capacitor was manufactured in the same manner, and the incidence of delamination is shown in Table 1.

Example 6.7 Ti content as titanate coupling agent 11.
Conductive paints were obtained in the same manner as in Example 1, except that 5% isopropyl tri(N-aminoethyl-aminoethyl) titanate was used and the amounts of the coupling agent and kerosene were as shown in Table 1. A laminated capacitor was manufactured in the same manner, and the occurrence rate of delamination is also shown in Table 1.

Example 8 A conductive paint having the composition of Example 2 was obtained in the same manner as in Example 2, except that the surface of the palladium powder was coated with a titanate coupling agent.

The coating treatment was performed by dissolving a titanate coupling agent in methyl ethyl ketone, adding palladium powder to this solution, ultrasonically dispersing it for 10 minutes, and then drying.

When a multilayer capacitor was manufactured using this conductive paint, the incidence of delamination was zero.

Example 9 With the same composition as in Example 5, a titanate coupling agent and barium naphthenate were coated on the surface of palladium powder in the same manner as in Example 8 to obtain a conductive paint. When a multilayer capacitor was manufactured using this conductive paint, the incidence of delamination was zero.

Comparative Example 1 A conductive paint was obtained in the same manner as in Example 1, except that the titanate coupling agent was not blended. When laminated capacitors were similarly manufactured, delamination occurred in 75% of the chips.

Comparative Example 2 The amount of titanate coupling agent was 0.2 parts by weight (Ti
A conductive paint was obtained in the same manner as in Example 1, except that the amount was 0.01 part by weight (calculated as 0.01 part by weight), and a multilayer capacitor was manufactured in the same manner. The incidence of delamination was 30%.

Comparative Example 3 A conductive paint was obtained in the same manner as in Example 1, except that the amount of titanate coupling agent was 20 parts by weight (1.01 parts in terms of Ti) and the amount of kerosene was 28 parts by weight. Ta. When a multilayer capacitor was similarly manufactured, no delamination was observed, but many cracks occurred after firing, making it unusable.

i1 Muara 1 The present invention effectively prevents delamination of multilayer capacitors by blending a titanate-based coupling agent or a mixture of a titanate-based coupling agent and a barium organic acid salt in a conductive paint for internal electrodes. This is extremely useful in industry.

Claims (1)

[Claims] 1 (a) 100 parts by weight of conductive powder and (b) 0 in terms of metal
．． A conductive paint for internal electrodes of a multilayer capacitor, comprising: 02 to 0.8 parts by weight of a titanate coupling agent dispersed in (c) an organic vehicle. 2. The conductive paint for multilayer capacitor internal electrodes according to claim 1, wherein the titanate coupling agent is coated on the surface of the conductive powder, 3. (a) 100 parts by weight of the conductive powder and (b) 0 parts by weight in terms of metal.
．． 02 to 0.8 parts by weight of a mixture of a titanate coupling agent and a barium organic acid salt, dispersed in (c) an organic vehicle, a conductive paint for internal electrodes of a multilayer capacitor; 4. a titanate coupling agent; 4. The conductive paint for multilayer capacitor internal electrodes according to claim 3, wherein one of the barium organic acid salts is coated on the surface of the conductive powder and the other is dispersed in an organic vehicle. 5. Claim 3, wherein the surface of the conductive powder is coated with a mixture of a titanate coupling agent and a barium organic acid salt.
Conductive paint for internal electrodes of multilayer capacitors as described.