JPH0449766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrode material used as an internal electrode in a multilayer ceramic capacitor.

Conventional Technology Recently, as electronic components have become smaller and thinner, electronic devices equipped with these electronic components have also become increasingly smaller and thinner, whether for industrial use or general consumer use. Furthermore, this trend is demanding further miniaturization and greater integration of electronic components. Even in capacitor parts, which are an important element in electronic components, ceramic capacitors with relatively small capacitance have shifted from conventional disk-type capacitors to chip-type capacitors, which can increase capacitance by stacking layers and can be made smaller. However, the demand is currently increasing rapidly. However, even the chip capacitor is a single discrete component, and when configured as one electronic component with other electronic components, there is a limit to the integration density of the electronic components. Therefore, recently, capacitor blocks have been developed which are a single capacitor chip but have a plurality of capacitances each having different capacitance values. However, in this case, it is necessary to configure one circuit part in a certain electric circuit as one block, so the capacitance values that should be included in one capacitor block are diverse, and therefore the internal electrode The pattern shape becomes extremely complex. On the other hand, the above ceramic multilayer capacitor chip (hereinafter simply referred to as capacitor chip)
One of the main causes of defective products in the manufacturing process is a phenomenon called delamination, which occurs in the internal electrode layers of capacitor chips. The cause of the delamination has not yet been fully elucidated, but from a material standpoint, it is mainly caused by the dielectric material that makes up the capacitor chip and the organic binder used to form a slurry when forming the green sheet. There are materials and internal electrodes, and in terms of manufacturing conditions, factors include the temperature and pressure when stacking green sheets, and the temperature profile during firing. In particular, among the organic materials that make up the internal electrodes together with metal powders,
For example, the combination of a glue material such as ethyl cellulose and an organic solvent has various properties such as viscosity, thixotropy, solubility in green sheets, and dispersibility of metal powder as a paste or ink for printing.
It has also been found that this has a great effect on the dissipation of organic materials due to evaporation, sublimation, combustion, etc., which is considered to be one of the causes of the delamination phenomenon during firing of the capacitor chips. Furthermore, research has recently revealed that the cause of the delamination is that its tendency varies greatly depending not only on the materials and manufacturing conditions but also on the shape of the internal electrodes.

Problems to be Solved by the Invention As mentioned above, the causes of delamination can be broadly classified into three factors: the dielectric material forming the capacitor chip, the internal electrodes, and the manufacturing conditions, which act independently or in conjunction with each other. It is thought that this phenomenon occurs when a conventional capacitor chip having a simple internal electrode is manufactured using conventional materials that are commonly used. In the capacitor chip according to the present invention, which has a so-called complex electrode shape having a plurality of capacitance values, the defects due to delamination, which occur less frequently, are caused by the above three factors acting in a more complex manner. The result was as follows.

In view of the above problems, the present invention combines a plurality of capacitors having different capacitance values as described above into one.
This is an attempt to solve the problems of capacitor chips, which require complicated internal electrode shapes and are prone to delamination defects, in order to incorporate them into ceramic chips. The object of the present invention is to provide a conductive paste for internal electrodes that has excellent characteristics by combining organic materials with large physical property changes that greatly affect the delamination phenomenon under optimal conditions.

Means for Solving the Problems In order to solve the above problems, the electrode material of the present invention consists of 40-70% by weight of metal palladium powder, 4-16% by weight of ethyl cellulose, 10-40% by weight of turpentine oil, and 40% by weight of ethyl cellosolve. ~80% by weight, an organic binder consisting of 1-6% by weight sorbitan triolate, and 1-6% by weight butylbenzyl phthalate.
It has a structure in which 30 to 60% by weight is added.

Effects The present invention has the above-mentioned configuration, and solves the problems pointed out above by combining a solvent for dissolving ethyl cellulose, that is, turpentine oil and ethyl cellosolve, in an optimal component ratio and utilizing their synergistic effect. Defects due to delamination can be prevented, and an extremely highly accurate electrode shape can be obtained without causing the electrode pattern on the green sheet to flow during printing of the electrode material.

The effects of each component constituting the present invention will be explained in detail below.

If the metal palladium powder is less than 40%, a homogeneous electrode film cannot be obtained after firing, resulting in a significantly high resistance value or wire breakage. If it exceeds 70%, the electrode film becomes too thick, causing delamination and increasing costs. If the ethyl cellulose content is less than 4%, appropriate printability cannot be obtained and the content is 16%.
If it exceeds the viscosity, the viscosity will become extremely high and it will not be possible to form a paste. If turpentine is less than 10%, ethyl cellulose will not dissolve, and if it is more than 40%, the green sheet will dissolve when internal electrodes are printed. If the content of ethyl cellosolve is less than 40%, the solvent in the electrodynamic paste will evaporate quickly, resulting in high viscosity during printing and resulting in printing impurities. If it exceeds 80%, the solubility in ethyl cellulose will deteriorate. Sorbitan triolate is 1
% or less, the dispersibility of metal palladium is poor and the powder particles tend to aggregate together. If it exceeds 6%, printability will be adversely affected. If the content of butyl benzyl phthalate is less than 1%, cracks will occur on the electrode surface dried after printing, and if it is more than 6%, the drying time will be longer and delamination will likely occur. 30 organic binders
% or less, when printed in relation to the amount of metal palladium added, the electrode film thickness becomes thicker, causing delamination. If it exceeds 60%, the electrode thickness will become thinner, resulting in a significant increase in resistance value or wire breakage.

Examples Examples of the present invention will be described below. Generally, a conductive paste is composed of metal powder, which is a conductive material, and an organic binder for forming a paste. First, as an organic glue material, the viscosity is
Add 40 g of ethyl cellulose of 10 cps to 100 cps to a mixed solvent of 200 g of ethyl cellosolve and 20 g of turpentine oil and stir well to dissolve.

The metal powder is well dispersed in the organic binder. 20 sorbitan triolate as a dispersant
g, 20 g of butylbenzyl phthalate as a plasticizer
is added and further mixed to form an organic binder. Next, 180g of metal palladium powder with an average particle size of 0.05-2.0μ
Add 120g of the organic binder above and mix well.
This pasty mixture is then kneaded on a three-roll mill until it is sufficiently homogeneous.

When manufacturing a multilayer ceramic capacitor using the conductive paste prepared as described above, first, dielectric powder and organic binder are mixed and ground and mixed using a ball mill or the like for about 3 to 7 days to form a slurry. The thickness of this slurry is reduced using a doctor blade.
After forming into a green sheet of 20 to 40 μm, it is cut out to a predetermined size and printed in a predetermined shape by screen printing using the above-mentioned conductive paste. This is 90℃
After drying for about 5 minutes, the required number of chips are stacked, pressure molded, cut into individual chips, and heated in an electric furnace to a maximum temperature of 1000 ~
Bake at 1400℃ for about 2 hours. At the beginning of the above firing process, the organic binder in the green sheet and the organic binder in the internal electrode conductive paste decompose, gasify, and dissipate, but it is suspected that the materials and process conditions used are inappropriate. Lamination defects occur. According to the above example, 10 to 40% by weight of turpentine and 40% by weight of ethyl cellosolve, which constitute the organic solvent component in the organic binder.
By containing up to 80% by weight, it was possible to eliminate the occurrence of delamination and to obtain an electrode shape with high dimensional accuracy despite having an extremely complex shape.

Effects of the Invention As described above, the present invention provides a metal palladium powder of 40~
Organic binder 30 consisting of 70% by weight, 4-16% by weight of ethyl cellulose, 10-40% by weight of turpentine oil, 40-80% by weight of ethyl cellosolve, 1-6% by weight of sorbitan triolate, and 1-6% by weight of butylbenzyl phthalate. By providing an electrode material to which ~60% by weight is added as an internal electrode, a capacitor chip without delamination defects can be obtained.

Claims (1)

[Claims] 1 40-70% by weight of metallic palladium powder, 4-16% by weight of ethyl cellulose, 10-40% by weight of turpentine oil, 40-80% by weight of ethyl cellosolve, 1-6% by weight of sorbitan triolate, and 1-6% by weight of butylbenzyl phthalate. Organic binder consisting of % by weight
An electrode material characterized by containing 30 to 60% by weight of the additive.