JPH0449769B2 - - 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 for 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 laminating layers and can be made smaller. However, the demand is currently expanding 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, a capacitor block is being developed which is a single capacitor chip but has 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 complicated. On the other hand, in the manufacturing process of the above-mentioned ceramic multilayer capacitor chips (hereinafter simply referred to as capacitor chips), one of the main causes of defective products is the delamination phenomenon called delamination that occurs in the internal electrode layers of the capacitor chips. be.
The cause of the delamination has not yet been fully elucidated, but from a material standpoint, it is mainly due to
There is an organic binder material needed to form a slurry when forming green sheets, and internal electrodes, and manufacturing conditions include the temperature and pressure when stacking green sheets, and the temperature profile during firing. This can be considered as a factor. In particular, among the organic materials that constitute the internal electrodes together with metal powders, the combination of glue materials such as ethyl cellulose and organic solvents is particularly important for the viscosity, thixotropy, solubility of green sheets as pastes or inks for printing, or for metal powders. It has been found that it has a great effect on the dispersibility and other properties of organic materials, as well as on the dissipation of organic materials during evaporation, sublimation, or combustion, which is considered to be one of the causes of the delamination phenomenon during firing of capacitor chips. There is. 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 The causes of delamination as described above 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. This phenomenon is thought to be caused by In the capacitor chip according to the present invention having a so-called complex electrode shape having a plurality of capacitance values each having a different capacitance value, the above three elements act more complexly, resulting in a frequent occurrence of defects due to fewer delaminations. .

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 materially solve the problem of capacitor chips, which require a complicated internal electrode shape and are prone to delamination defects.
In particular, the present invention provides a conductive paste for internal electrodes that has excellent characteristics by combining organic materials with large physical property changes that have a large effect on 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 contains 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 mineral spirits. 80% by weight of an organic binder, 1-6% by weight of sorbitan triolate, and 1-6% by weight of butylbenzyl phthalate.

Effect The present invention solves the problems pointed out above by combining the solvent for dissolving ethyl cellulose, that is, turpentine oil and mineral spirits in an optimal component ratio and utilizing their synergistic effect in the above configuration. Such defects due to delamination can be prevented, and there is no fear that the green sheet will be damaged when printing 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 content of ethyl cellulose is less than 4%, appropriate printability cannot be obtained, and if it is more than 16%, the viscosity becomes extremely high and cannot be used as a paste. If turpentine oil is less than 10%, it will not dissolve the ethyl cellulose, and if it is more than 40%, it will dissolve the green sheet when internal electrodes are printed. If the content of mineral spirits is less than 40%, the solvent in the conductive paste will evaporate quickly, and the viscosity will increase during printing, making it impossible to print. If it exceeds 80%, the solubility in ethyl cellulose will deteriorate. If the sorbitan oleate is less than 1%, the dispersibility of metal palladium is poor and the powder particles tend to aggregate together. If it exceeds 6%, printability will be adversely affected. Butylbenzyl phthalate is 1
If it is less than 6%, 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 be more likely to occur. If the organic binder content is less than 30%, when printed in relation to the amount of metal palladium added, the electrode film thickness becomes thick and causes 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, the viscosity is
Add 40 g of ethyl cellulose of 10 cps to 100 cps to a mixed solvent of 200 g of mineral spirits and 20 g of turpentine oil and stir well to dissolve. The metal powder is well dispersed in the organic binder. 20 g of sorbitan triolate as a dispersant and 20 g of butyl benzyl phthalate as a plasticizer are added and further mixed to obtain an organic binder. Next, the average particle size is 0.05~2.0μ
Add 120 g of the above organic binder to 180 g of metallic palladium powder 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 pulverized and mixed using a ball mill or the like for about 3 to 7 days to form a slurry. This slurry is formed into a green sheet having a thickness of 20 to 40 μm using a doctor blade, and then cut out to a predetermined size and printed into a predetermined shape by screen printing using the above conductive paste. After drying at 90°C for about 5 minutes, the required number of sheets are laminated, pressure molded, cut into chips, and fired at a maximum temperature of 1000 to 1400°C for about 2 hours in an electric furnace according to a predetermined heating program. At the beginning of the firing process, the organic binder in the green sheet and the organic binder in the internal electrode conductive paste decompose, gasify, and dissipate. If the materials and process conditions used are inappropriate, delamination occurs. Shion failure occurs.

In this way, according to the above embodiment, 10 to 40% of turpentine, which constitutes the organic solvent component in the organic binder, is
By containing mineral spirits in an amount of 40 to 80% by weight, it was possible to eliminate the occurrence of delamination, and the green sheet was not corroded when printing electrodes.

Effects of the Invention As described above, the present invention provides a metal palladium powder of 40~
70% by weight, ethyl cellulose 4-16%, turpentine oil 10-40%, mineral spirits 40-80%.
% by weight, sorbitan triolate 1-6% by weight,
By providing an electrode material to which 30 to 60% by weight of an organic binder consisting of 1 to 6% by weight of butylbenzyl phthalate 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 mineral spirits, 1-6% by weight of sorpitan triolate, and 1% by weight of butylbenzyl phthalate. An electrode material comprising 30 to 60% by weight of an organic binder comprising 6% by weight.