JPH07118429B2 - Conductive paint for internal electrodes of multilayer capacitors - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a conductive coating material for forming internal electrodes of a ceramic multilayer capacitor.

2. Description of the Related Art Generally, a multilayer capacitor is manufactured by alternately laminating several layers to several tens layers of unfired ceramic dielectric layers and internal electrode layers, sintering the layers at high temperature, and providing external terminals thereto. As the dielectric, there is used a ceramic powder such as a composite perovskite containing barium titanate, titanium oxide or lead mixed with an organic binder to form a slurry, which is formed into a sheet by a method such as a doctor blade method. For the internal electrode material, conductive powder such as platinum, palladium, gold, silver, nickel, copper and mixtures and alloys thereof, if necessary, may be mixed with an inorganic oxide additive or the like and dispersed in an organic vehicle. A paint composition is used. Usually, this conductive paint is screen-printed on the unsintered dielectric sheet to form an internal electrode layer, a plurality of these are stacked and heat-pressed, cut into chip pieces, and then fired in a predetermined profile. The capacitor element body has an integrated structure.

However, during firing of the multilayer capacitor, delamination (delamination) 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. It's a problem. Although the cause of delamination has not been fully clarified, the rate of delamination is determined by the material system, that is, the internal electrode material and dielectric material, the number and size of the capacitors, the stacking conditions, and the manufacturing conditions such as firing conditions. The highest occurrence rate of barium titanate-based high-lamination products makes it difficult to reduce the occurrence rate to 0 even if the manufacturing conditions are very strictly controlled, and delamination measures are required to improve productivity and quality. This is an important issue. Various measures have been taken to prevent delamination. For example, in JP-A-60-136212, the same organic binder as a dielectric material is used as the organic binder for the internal electrode material. Although delamination is suppressed to some extent, delamination still occurs depending on the firing conditions, and the effect cannot be said to be sufficient. Further, JP-A-61-248412 describes that delamination is suppressed by adding a dielectric ceramic powder to the internal electrode, but this method deteriorates the continuity of the internal electrode film. However, it is not desirable from the viewpoint of the recent demand for thinner internal electrodes.

An object 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.

Means for Solving the Problems The present invention includes: 1. (a) one or more conductive materials selected from platinum, palladium, gold, silver, nickel, copper, and alloys containing these metals as main components. 100 parts by weight of the powder and (b) a titanate-based coupling agent having both an inorganic affinity group and an organic affinity group (0.02 to 0.8 parts by weight in terms of metallic titanium) are added to (c) the organic vehicle. Conductive paint for dispersed capacitor internal electrodes.

2. The conductive paint for a multilayer capacitor internal electrode 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) 0.02 in terms of metal
A conductive coating material for an internal electrode of a multilayer capacitor, comprising: (c) an organic vehicle, and a mixture of a titanate coupling agent and a barium organic acid salt in an amount of about 0.8 part by weight.

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

5. The surface of the electrically conductive powder is coated with a mixture of a titanate coupling agent and a barium organic acid salt.
The conductive paint for the internal electrodes of the multilayer capacitor described above. "

Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacrylic titanate, isopropyl trictanate. Those having both an inorganic affinity group and an organic affinity group such as milphenyl titanate are used.

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

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

Action In the coating material of the present invention, by using a titanate-based coupling agent or a mixture of a titanate-based coupling agent and a barium organic acid salt (hereinafter referred to as “metal organic compound”) in combination with a conductive powder, any condition can be obtained. Even below, delamination could be effectively prevented. That is, in the case of the conventional internal electrode coating material, delamination occurs by controlling firing conditions and the like very strictly, but delamination can be easily prevented by adding a metal organic compound, and the generation rate can be made zero. The compounding amount of the metal organic compound is preferably about 0.02 to 0.8 parts by weight in terms of metal with respect to the conductive powder. If it is less than 0.02 part by weight, the effect is not sufficient, and
If it is more than 0.8 parts by weight, firing cracks become a problem. In particular
A range of 0.05 to 0.5 parts by weight is desirable.

The metal organic compound has an effect of suppressing the occurrence of delamination. The metal organic compound acts as an adhesive between the internal electrode and the dielectric layer when firing the laminated body, and prevents the peeling of the two. It is thought to be to do. Further, the metal organic compound has an excellent effect of suppressing the oxidative expansion of palladium when 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 finally exists in the electrode film in the form of a metal oxide.

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

The organic vehicle used in the present invention is not particularly limited, and those commonly used for coating internal electrodes of laminated capacitors can be used.

The conductive paint of the present invention may also be mixed with metal oxides, organic bentonite, etc. which are conventionally added for the purpose of preventing cracks.

Examples Example 1 Palladium powder 100 parts by weight Titanate coupling agent * 1.0 parts by weight (0.05 parts by weight in terms of metallic Ti) Ethyl cellulose 7 parts by weight Terpineol 30 parts by weight Kerosene 47 parts by weight * Isopropyltriisostearoyl titanate, Ti content 5% The above composition was kneaded to produce a paste-like conductive paint.

This conductive coating is screen-printed on a BaTiO ₃ -based dielectric green sheet in a predetermined pattern, dried, and then laminated with 35 layers,
It was pressure-bonded and cut into a predetermined size to produce an unfired multilayer capacitor chip. The occurrence rate of delamination was 0 when the chip was fired by raising the temperature at a temperature rising rate of 200 ° C./hour and holding it at the maximum temperature of 1350 ° C. for 2 hours.

Examples 2 to 4 Conductive paints were obtained in the same manner as in Example 1 except that the amounts of titanate coupling agent and kerosene were as shown in Table 1. Similarly, a laminated capacitor was manufactured, and the occurrence rate of delamination is also shown in Table 1.

Example 5 A conductive coating material was prepared in the same manner as in Example 1 except that 0.8 parts by weight of a titanate coupling agent and 1.3 parts by weight of barium naphthenate (Ba content 9%) were blended, and the amount of kerosene was 46 parts by weight. Got Similarly, a multilayer capacitor was manufactured, and the occurrence rate of delamination is shown in Table 1.

Examples 6 and 7 Examples 6 and 7 except that isopropyl tri (N-aminoethyl-aminoethyl) titanate having a Ti content of 11.5% was used as the titanate coupling agent, and the amounts of the coupling agent and kerosene were as shown in Table 1. Conductive paints were obtained in the same manner as in Example 1. Similarly, a laminated capacitor was manufactured, 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 except that the surface of the palladium powder was coated with a titanate coupling agent. The coating treatment was carried out by dissolving the titanate coupling agent in methyl ethyl ketone, adding palladium powder to this solution, ultrasonically dispersing for 10 minutes, and then drying.

When a laminated capacitor was manufactured using this conductive paint, the occurrence rate of delamination was 0.

Example 9 Using the same composition as in Example 5, the 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 laminated capacitor was manufactured using this conductive paint, the occurrence rate of delamination was 0.

Comparative Example 1 A conductive coating material was obtained in the same manner as in Example 1 except that the titanate coupling agent was not added. When a multilayer capacitor was manufactured in the same manner, delamination was observed in 75% of the chips.

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

Comparative Example 3 The amount of the titanate coupling agent was 20 parts by weight (calculated as Ti.
1.0 part by weight), except that the amount of kerosene is 28 parts by weight,
A conductive coating material was obtained in the same manner as in Example 1. Similarly, when a laminated capacitor was manufactured, delamination was not observed, but many cracks were generated after firing, which was not practical.

EFFECTS OF THE INVENTION The present invention effectively prevents delamination of a multilayer capacitor by blending a conductive paint titanate coupling agent for an internal electrode or a mixture of a titanate coupling agent and a barium organic acid salt. It has been obtained and is extremely useful industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01G 4/30 301 C 9174-5E (72) Inventor Naoki Nose 2-9, Suehiro-cho, Ome-shi, Tokyo Address 3 within Shoei Chemical Industry Co., Ltd. (56) Reference JP-A-58-195 (JP, A) JP-A-59-155988 (JP, A) JP-A-59-155989 (JP, A) JP-A-62 -225573 (JP, A)

Claims (5)

[Claims] 1. (a) 100 parts by weight of one or more conductive powders selected from platinum, palladium, gold, silver, nickel, copper and alloys containing these metals as main components;
(B) A multilayer capacitor obtained by dispersing 0.02 to 0.8 parts by weight, in terms of metallic titanium, of a titanate coupling agent having both a group having an affinity for an inorganic substance and a group having an affinity for an organic substance in (c) an organic vehicle. Conductive paint for internal electrodes. 2. The conductive paint for a multilayer capacitor internal electrode 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 a conductive powder and (b) 0.02 to 0.8 parts by weight of metal as a mixture of a titanate coupling agent and a barium organic acid salt are dispersed in (c) an organic vehicle. Conductive paint for internal electrodes of multilayer capacitors. 4. A conductive material for an internal electrode of a multilayer capacitor according to claim 3, wherein either one of the titanate coupling agent and the barium organic acid salt is coated on the surface of the conductive powder and the other is dispersed in the organic vehicle. Paint. 5. A conductive powder surface is coated with a mixture of a titanate coupling agent and a barium organic acid salt.
The conductive paint for an internal electrode of the multilayer capacitor according to claim 3.