JP4161472B2 - Conductive thick film paste, method for producing the same, and multilayer ceramic capacitor using the same - Google Patents

Description

【００２４】
表１から明らかであるように、試料２ないし６の導電性厚膜ペーストは、初期粘度が１５．１ないし２０．０Ｐａ・ｓであり、初期粘度の許容範囲である１８±３Ｐａ・ｓの範囲内となった。これに対して、オキシエチレンドデシルアミンを添加しなかった試料１ならびに５．５０重量部添加した試料７は、それぞれ２２．２Ｐａ・ｓ、１２．３Ｐａ・ｓで許容範囲外となった。
【００２５】
３０日後の粘度変化率は、オキシエチレンドデシルアミンを０．１０重量部、１．５０重量部、３．５０重量部、５．００重量部添加した試料３ないし６は、０．６％ないし１．０％で大変小さく優れた。これに対して、オキシエチレンドデシルアミンを０．０５重量部添加した試料２は、１３９．０％で大きく劣り、初期粘度で許容範囲外であった試料１と試料７についても、それぞれ１５５．９％、−３４．１％で同様に大きく劣った。
【００２６】
【発明の効果】
以上のように本発明によれば、平均粒径１μｍ以下の導電性粉末と、有機ビヒクルと、からなる導電性厚膜ペーストにおいて、アミン系界面活性剤と、アニオン性高分子分散剤と、を添加することで、平均粒径１μｍ以下の導電性粉末を用いた導電性厚膜ペーストであっても、分散性に優れ、かつ経時的な粘度変化が少ないという効果が得られる。
【００２７】
また、前記アミン系界面活性剤は、アルキレンオキサイドまたはその重合体と、アルキル基または水素と、からなることで、上述した効果がより確実に発揮される。
【００２８】
また、前記アミン系界面活性剤は、前記導電性厚膜ペースト１００重量部のうち、０．１〜５．０重量部含有することで、上述した効果がより確実に発揮される。
【００２９】
また、前記導電性粉末は、Ｎｉ粉末、およびＣｕ粉末、これらの金属粉末を含む合金粉末から選ばれる１種または２種以上からなることで、電子部品の電極形成に好適な導電性厚膜ペーストが得られるという効果が得られる。
【００３０】
また、本発明の導電性厚膜ペーストは、積層セラミックコンデンサの内部電極に用いられることで、微粒の導電性粉末を含有する導電性厚膜ペーストの効果が十分に発揮される。
【００３１】
また、アニオン性高分子分散剤と導電性粉末を混合して、前記導電性粉末に前記アニオン性高分子分散剤を吸着させた中間ペーストを得る工程と、前記中間ペーストに前記アミン系界面活性剤を添加する工程と、を備えることを特徴とすることで、平均粒径１μｍ以下の導電性粉末を用いた導電性厚膜ペーストでありながら分散性に優れ、かつ経時的な粘度変化の少ない導電性厚膜ペーストを製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive thick film paste used for forming an electrode of an electronic component, a manufacturing method thereof, and a multilayer ceramic capacitor using the conductive thick film paste.
[0002]
[Prior art]
Conventionally, a conductive thick film paste has been used as a material for forming an electrode of a multilayer ceramic capacitor. As such a conductive thick film paste, a conductive powder made of Ni, Cu, Ag, Pd or the like dispersed in an organic vehicle formed by mixing an organic binder and a solvent is used.
[0003]
[Problems to be solved by the invention]
However, the conventional conductive thick film paste has a viscosity that increases with the passage of time after the paste is manufactured when fine particles with a conductive powder particle size of 1 μm or less are used, and can be printed on a green sheet by a method such as screen printing. There is a problem that the film thickness is likely to fluctuate. Thus, when the electrode dry film | membrane with nonuniform film thickness is laminated | stacked and sintered, there existed a problem that the delamination and the crack resulting from the nonuniformity of a volume change were easy to generate | occur | produce.
[0004]
Therefore, in order to effectively and uniformly disperse such fine conductive powder, there is a method of adding a dispersant as an additive. That is, the surface of the conductive powder such as Ni or Cu is basic, and there is a method of adding an anionic polymer dispersant in consideration of acid-base interaction, for example. However, by adding a dispersant, wetting of the conductive powder into the solvent is promoted, and a uniform mixed system can be formed in a shorter time. However, the polymer dispersant has a single excess adsorption site. Not only particles but also a plurality of particles are likely to form a three-dimensional cross-linking, and when such cross-linking proceeds, problems of viscosity increase and gelation newly occur.
[0005]
The object of the present invention is to solve the above-mentioned problems. The conductive thick film paste using conductive powder having an average particle size of 1 μm or less is excellent in dispersibility and changes in viscosity over time. It is an object of the present invention to provide a conductive thick film paste with a low content and a method for producing the same.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the conductive thick film paste of the present invention is a conductive thick film paste comprising a conductive powder having an average particle size of 1 μm or less and an organic vehicle. And a functional polymer dispersant.
[0007]
The amine-based surfactant is characterized by comprising an alkylene oxide or a polymer thereof and an alkyl group or hydrogen.
[0008]
In addition, the amine-based surfactant is contained in an amount of 0.1 to 5.0 parts by weight in 100 parts by weight of the conductive thick film paste.
[0009]
Further, the conductive powder is characterized by being composed of one or more selected from Ni powder, Cu powder, and alloy powder containing these metal powders.
[0010]
Also, the method for producing a conductive thick film paste of the present invention comprises mixing an anionic polymer dispersant and a conductive powder to obtain an intermediate paste in which the anionic polymer dispersant is adsorbed to the conductive powder. And a step of adding the amine surfactant to the intermediate paste.
[0011]
In addition, the multilayer ceramic capacitor of the present invention is characterized in that an internal electrode is formed using the above-described conductive thick film paste.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The feature of the present invention is that the excess adsorption sites of the anionic polymer dispersant added to enhance the dispersibility of the conductive powder in the conductive thick film paste, that is, the acid sites are neutralized with the additive. There is.
[0013]
Examples of such additives include the addition of a basic low molecular weight compound or a surfactant. When an amine surfactant comprising an alkylene oxide or a polymer thereof and an alkyl group or hydrogen is used, it is effective. In particular, the increase in viscosity could be suppressed.
[0014]
The added amount of the amine surfactant is preferably 0.1 to 5.0 parts by weight in 100 parts by weight of the conductive thick film paste. That is, when the addition amount is less than 0.1 part by weight, the addition effect is not sufficiently exhibited, and the increase in viscosity cannot be suppressed. On the other hand, when the addition amount exceeds 5.0 parts by weight, the viscosity of the conductive thick film paste is remarkably lowered, and an appropriate viscosity as a printing paste cannot be obtained.
[0015]
Moreover, it is preferable that electroconductive powder consists of 1 type (s) or 2 or more types chosen from Ni powder, Cu powder, and alloy powder containing these metal powders. These metal powders or alloy powders are generally used as conductive components of conductive thick film pastes.
[0016]
In addition, as a method for producing the conductive thick film paste of the present invention, an intermediate paste in which an anionic polymer dispersant and a conductive powder are mixed and the anionic polymer dispersant is adsorbed on the conductive powder is used. It is preferable to include a step of obtaining and a step of adding the amine-based surfactant to the intermediate paste. In other words, it is necessary to adsorb the anionic polymer dispersant to the conductive powder. However, if an amine surfactant is added after the anionic polymer dispersant is added, the anionic polymer dispersant becomes an amine surfactant. Since it is sufficiently adsorbed to the conductive powder without adsorbing with the agent, the dispersion effect of the conductive powder is sufficiently improved.
[0017]
In addition, the conductive thick film paste of the present invention is preferably used as an internal electrode of a multilayer ceramic capacitor. In recent years, monolithic ceramic capacitors have become lighter, thinner, and smaller, and for conductive thick film pastes used for forming internal electrodes, further refinement of conductive powder is required. In response to such demands, the conductive thick film paste of the present invention is a conductive thick film paste using a conductive powder having an average particle size of 1 μm or less, but has excellent dispersibility and little change in viscosity over time. It has the advantage of.
[0018]
【Example】
First, 80 parts by weight of terpineol as a solvent and 20 parts by weight of an ethyl cellulose resin as an organic binder are prepared, and after adding the organic binder to the solvent, the organic vehicle is obtained by uniformly mixing with a stirrer.
[0019]
Next, 45 parts by weight of an organic vehicle, 5 parts by weight of a polyacrylic acid-polyacrylate ester anionic polymer dispersant, and 50 parts by weight of Ni powder having an average particle size of 0.5 μm were added, and three rolls were added. To obtain a first intermediate paste.
[0020]
Next, as shown in Table 1, amine surfactants composed of different addition amounts of oxyethylene dodecylamine were prepared, added to the first intermediate paste transferred to the mortar and mixed, and the conductivity of Samples 1 to 7 was measured. Thick film paste was obtained.
[0021]
Therefore, the initial viscosity of the conductive thick film pastes of Samples 1 to 7 was measured, and after standing for 30 days at 25 ° C. in the atmosphere, the viscosity was measured again to determine the change in viscosity.
[0022]
The viscosity of the conductive thick film paste was measured at 25 ° C. and 2.5 rpm using an E-type viscometer manufactured by Tokimec Co., Ltd. The allowable range of the initial viscosity of the conductive thick film pastes of Samples 1 to 7 used for the evaluation was 18 ± 3 Pa · s. Viscosity change rate was calculated | required by following Formula.
Viscosity change rate (%) = (viscosity after 30 days−initial viscosity) / initial viscosity × 100
In the comprehensive evaluation, “◯” was given for samples within the scope of the present invention, and “X” was given for samples outside the scope.
[0023]
[Table 1]

[0024]
As is clear from Table 1, the conductive thick film pastes of Samples 2 to 6 have an initial viscosity of 15.1 to 20.0 Pa · s, and the range of 18 ± 3 Pa · s which is an allowable range of the initial viscosity. It became inside. On the other hand, Sample 1 to which oxyethylene dodecylamine was not added and Sample 7 to which 5.50 parts by weight were added were outside the allowable range at 22.2 Pa · s and 12.3 Pa · s, respectively.
[0025]
After 30 days, the rate of change in viscosity was 0.6% to 1 for samples 3 to 6, to which 0.10 parts by weight, 1.50 parts by weight, 3.50 parts by weight, and 5.00 parts by weight of oxyethylene dodecylamine were added. Very small and excellent at 0.0%. On the other hand, Sample 2 to which 0.05 part by weight of oxyethylene dodecylamine was added was greatly inferior at 139.0%, and Sample 1 and Sample 7 which were outside the allowable range in initial viscosity were 155.9 respectively. % And -34.1% were similarly inferior.
[0026]
【The invention's effect】
As described above, according to the present invention, in the conductive thick film paste comprising the conductive powder having an average particle size of 1 μm or less and the organic vehicle, the amine-based surfactant and the anionic polymer dispersant are: By adding, even the conductive thick film paste using the conductive powder having an average particle size of 1 μm or less has an effect of excellent dispersibility and little change in viscosity over time.
[0027]
In addition, the amine-based surfactant includes the alkylene oxide or the polymer thereof, and the alkyl group or hydrogen, so that the above-described effect is more reliably exhibited.
[0028]
Moreover, the said effect is demonstrated more reliably by containing 0.1-5.0 weight part of said amine type surfactant among 100 weight part of said electroconductive thick film pastes.
[0029]
In addition, the conductive powder is composed of one or more selected from Ni powder, Cu powder, and alloy powder containing these metal powders, so that the conductive thick film paste suitable for forming electrodes of electronic components is used. Is obtained.
[0030]
Moreover, the conductive thick film paste of the present invention is used for the internal electrode of the multilayer ceramic capacitor, so that the effect of the conductive thick film paste containing the fine conductive powder is sufficiently exhibited.
[0031]
A step of mixing an anionic polymer dispersant and a conductive powder to obtain an intermediate paste in which the anionic polymer dispersant is adsorbed to the conductive powder; and the amine surfactant in the intermediate paste. A conductive thick film paste using a conductive powder having an average particle size of 1 μm or less, and having excellent dispersibility and a small change in viscosity over time. Thick film paste can be produced.

Claims (6)

In a conductive thick film paste comprising a conductive powder having an average particle size of 1 μm or less and an organic vehicle,
A conductive thick film paste comprising an amine-based surfactant and an anionic polymer dispersant. 2. The conductive thick film paste according to claim 1, wherein the amine-based surfactant is composed of alkylene oxide or a polymer thereof and an alkyl group or hydrogen. 3. The conductive thick film paste according to claim 1, wherein the amine-based surfactant is contained in an amount of 0.1 to 5.0 parts by weight out of 100 parts by weight of the conductive thick film paste. The electroconductive powder according to any one of claims 1 to 3, wherein the electroconductive powder is composed of one or more selected from Ni powder, Cu powder, and alloy powder containing these metal powders. Thick film paste. Mixing an anionic polymer dispersant and conductive powder to obtain an intermediate paste in which the conductive powder is adsorbed with the anionic polymer dispersant;
Adding the amine surfactant to the intermediate paste;
A method for producing a conductive thick film paste, comprising: A multilayer ceramic capacitor, wherein an internal electrode is formed using the conductive thick film paste according to any one of claims 1 to 4.