Method for manufacturing conductive paste

Abstract

The invention provides a method for manufacturing a conductive paste which has high dispersivity and excellent viscosity stability as a paste for an internal electrode of a laminated porcelain capacitor. The method for manufacturing the conductive paste is characterized by including one to three steps of: a preliminary treatment dispersion step, heating and mixing the coarse conductive paste including the conductive metallic powders, a dispersant, an organic adhesive and an organic solvent, permitting it to pass through a nozzle having an orifice; a dispersion step, dispersing the heated conductive paste by a high-pressure homogenizer; and a filtering step, filtering the conductive paste after dispersion treatment by a filter.

Description

technical field [0001] The present invention relates to a method for producing a conductive paste having excellent viscosity stability while maintaining high dispersibility among pastes for internal electrodes of laminated ceramic capacitors. Background technique [0002] Along with thinner and smaller electronic devices such as mobile phones and digital devices, there are demands for miniaturization, higher capacity, and higher performance of multilayer ceramic capacitors (hereinafter referred to as MLCCs) as chip components. The most effective method for realizing these is to achieve multilayering by thinning the internal electrode layers and dielectric layers. [0003] The MLCC is generally manufactured as follows. In order to form the dielectric layer, firstly the barium titanate (BaTiO 3 ) on a dielectric green sheet containing an organic binder such as barium titanate and polyvinyl butyral as the main component, and dispersing conductive powder as the main component ...

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Problems solved by technology

[0014] However, the common feature of the kneading method in the conventional conductive paste production process is that inorganic powder such as conductive metal powder or ceramic powder and organic matter ( organic solvent, dispersant, organic vehicle, etc.) for mixing

However, in these kneading methods, the organic vehicle is often mixed insufficiently, and the surface of the conductive metal powder or ceramic powder is not sufficiently wetted. After these kneading methods are used to carry out the next process, the use of a high-pressure homogenizer In the case of decentralized processing, the following problems are likely to occur

[0015] First, the viscosity of the conductive coarse paste increases due to the addition of an organic vehicle, and as a result, the fluidity becomes insufficient, making it difficult to perform dispersion treatment with a high-pressure homogenizer

[0016] Second, there is an incompletely mixed organic vehicle in the conductive coarse paste, and when it is put into a high-pressure homogenizer, the solid component containing the organic vehicle adheres to the device, making it difficult to work normally

[0017] Third, hindered by the organic carrier, the collision force or shear force generated by the high-pressure homogenizer on the conductive metal powder or ceramic powder cannot be maximized (the organic carrier becomes a buffer, and the mechanical shear force cannot effectively Conductive metal powder or ceramic powder functions, and sufficient dispersibility cannot be obtained)

[0018] Fourth, since the surface of the conductive metal powder or ceramic powder is not sufficiently wetted, the conductive paste has little luster, and the frequency of nozzle clogging becomes high due to the presence of agglomerates larger than the diameter of the nozzle

In particular, there is a limit to dispersing a conductive paste using fine-grained nickel powder of 0.2 μm or less only by mechanical shearing using a conventional 3-roll machine, because the adsorption of the dispersant to the nickel surface becomes Insufficient, as a result, it is difficult to control the change in viscosity over time

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