JPH04238854A - Production of ceramic green sheet - Google Patents

Abstract

PURPOSE:To improve antistatic effects by blending raw material powder of ceramics composition with a quaternary ammonium salt containing neither halogen nor metallic element and slurrying. CONSTITUTION:100 pts.wt. raw material powder of ceramics composition is blended with 0.05-3 pts.wt. quaternary ammonium salt shown by the formula R4NX (R is alkyl or aryl; X is NO2<->, NO3<-> or CH3COO<->) containing neither halogen nor metallic element, a binder, a plasticizer and an organic solvent to give a ceramics slurry. The slurry is applied to a substrate and dried.

Description

Description: FIELD OF INDUSTRIAL APPLICATION [0001] The present invention relates to a method for manufacturing a ceramic green sheet, and more particularly, to a method for manufacturing a ceramic green sheet useful as a material for ceramic electronic components having a laminated structure. [0002] Generally, when manufacturing a ceramic electronic component having a laminated structure, such as a laminated capacitor, ceramic raw material powders are mixed into a slurry to have a desired composition, and the resulting ceramic slurry is Form a sheet, form a conductive layer such as an electrode layer on its surface, and laminate it.
A method is adopted in which this is baked and integrated. Normally, when a ceramic slurry, especially a ceramic slurry prepared using an organic solvent, is formed into a sheet, the resulting ceramic green sheet has a high surface resistance, so it is easily charged, and the strong static electricity causes dust to adhere to the surface of the green sheet. There is a problem in that the quality of ceramic electronic components deteriorates as a result. This phenomenon is remarkable when the green sheet becomes thin, especially when its wall thickness becomes 10 μm or less. For this reason, static electricity on the green sheet is removed by physical means such as bringing the green sheet into contact with a static elimination brush or blowing ionized air onto the green sheet. [Problems to be Solved by the Invention] However, although the above-mentioned physical means are extremely effective in removing static electricity, after removing static electricity, static electricity may be removed due to contact with other substances, friction, or peeling from other substances. For example, when a green sheet comes into contact with a roll and then separates from the roll, or when the green sheet is peeled off from a carrier film, strong static electricity is generated and the roll is charged again. Therefore, physical means can only temporarily eliminate static electricity, and are insufficient as permanent static elimination means. [0004] Accordingly, an object of the present invention is to improve the quality of ceramic electronic components by making it possible to prevent charging during the manufacturing process even in ceramic green sheets using organic solvents. Means for Solving the Problems The present invention, as a means for solving the above problems, provides that quaternary ammonium containing no halogen or metal element is added to 100 parts by weight of raw material powder of a ceramic composition. A ceramic slurry is prepared by adding 0.05 to 3 parts by weight of salt. As the quaternary ammonium salt, any salt can be used as long as it does not contain halogen or metal elements, but typical ones include those with the general formula: R4NX
(However, R is the same or different and represents an alkyl or aryl group, and X represents NO2-, NO3-, CH3COO-.) A quaternary ammonium salt represented by the following formula is preferred. These quaternary ammonium salts can be used alone or in combination of two or more. [Function] The quaternary ammonium salt added to the ceramic slurry reduces the surface resistance of the ceramic green sheet, so even if the ceramic green sheet is charged during the manufacturing process, the half-life of the charged voltage is significantly shortened. ,
Static electricity is removed and problems caused by charging are eliminated. Furthermore, the inclusion of this quaternary ammonium salt also serves to improve the dispersibility of ceramic powder in a solvent and the molded density of ceramic green sheets. The reason why the amount of the quaternary ammonium salt added is 0.05 to 3 parts by weight per 100 parts by weight of the ceramic composition is that if the amount added is less than 0.05 parts by weight, a sufficient static elimination effect is not obtained. If the amount exceeds 3 parts by weight, the green sheet becomes brittle and becomes difficult to handle. [Example] Example 1: 100 parts by weight of barium titanate powder, 10 parts by weight of polyvinyl butyral resin as a binder, 5 parts by weight of dioctyl phthalate as a plasticizer, 50 parts by weight of toluene and 5 parts by weight of ethyl alcohol as a solvent.
0 parts by weight of dimethylethylpropylammonium acetate as a quaternary ammonium salt.
A ceramic slurry was prepared by adding ~6 parts by weight. This slurry was formed into a sheet by a doctor blade method and dried to form a 10 μm thick ceramic green sheet on a carrier film. A polyethylene terephthalate film was used as the carrier film. [0010] After preparing the slurry and forming the ceramic green sheet, the viscosity of the slurry and the molded density of the green sheet were measured. When the amount of quaternary ammonium salt added was 0, the viscosity of the slurry was 420 cps;
The molded density of the green sheet was 3.2 g/cm3, but when 0.05 parts by weight or more of quaternary ammonium salt was added, the viscosity of the slurry was 330 cps, and the molded density of the green sheet was 3.5 g/cm3. It was cm3. [0011] The charging voltage and half-life of the obtained green sheet were measured. The results are shown in FIGS. 1 and 2 as a function of the amount of quaternary ammonium salt added. As is clear from the results shown in FIG.
In the case where quaternary ammonium salt is not added, the charging voltage is extremely high at 6 kV and its half-life is more than 30 seconds, but as the amount of quaternary ammonium salt added increases, the charging voltage after sheet forming increases rapidly. barium titanate 100
When the amount of the quaternary ammonium salt is 0.5 parts by weight, the charging voltage is halved, and when it is 2 parts by weight or more, it is reduced to 0.2 kv or less. Furthermore, from the results shown in Figure 2, the half-life of the charging voltage rapidly decreases as the amount of quaternary ammonium salt added increases.
It can be seen that when the amount added is 0.1 part by weight, the time required is 5 seconds, and when the amount added is 0.5 parts by weight or more, it is reduced to 1 second or less. [0013] Furthermore, when the charged voltage of the ceramic green sheet immediately after the barium titanate green sheet was peeled off from the carrier film was measured, the same results as those shown in FIG. 1 were obtained. At this time, when the green sheet was peeled off from the carrier film in the case where no quaternary ammonium salt was added, the green sheet was full of wrinkles.
The green sheets to which 0.05 parts by weight or more of grade ammonium salts were added did not wrinkle when peeled. Furthermore, when green sheets were stacked, when the amount of quaternary ammonium salt added was 0 parts by weight, they turned over due to static electricity, but when the amount of quaternary ammonium salt added was 0.
When 0.05 parts by weight or more was added, no peeling occurred. After degreasing the green sheet peeled from the carrier film at 450° C. for 3 hours in a nitrogen gas atmosphere, the amount of residual carbon was measured and found to be 0.
．． It was observed that the content was approximately constant at 8 to 0.9% by weight. A slurry was prepared with the same composition as above except that quaternary ammonium nitrate was used instead of quaternary ammonium acetate, and a ceramic green sheet was formed in the same manner as in the above case. did. When the charging characteristics of this ceramic green sheet were measured, results similar to those shown in FIGS. 1 and 2 were obtained. Also,
After degreasing this green sheet by heating it at 450°C for 3 hours in a nitrogen gas atmosphere, the amount of residual carbon was measured, and it was found to be approximately constant at 0.9 to 1.0% by weight. It was found that when salt was used, the amount of residual carbon was smaller and the thermal decomposition properties were better. It was also found that acetate was slightly better than nitrate in terms of static elimination effect and slurry dispersibility. [0016] In the above example, when preparing the ceramic slurry, barium titanate powder prepared in advance is used as the raw material powder, but this is not necessarily necessary, and the starting materials barium carbonate and titanium oxide are used. You may also use Furthermore, the present invention is not limited only to the production of ceramic green sheets made of barium titanate, but a portion of barium is replaced with one or more other elements, such as lead, strontium, calcium, magnesium, etc. In addition to barium titanate-based ceramic compositions in which titanium is partially replaced with one or more other elements such as zirconium and tin, rare earth elements, niobium, and other semiconducting elements are added to them. It can also be applied to the production of ceramic green sheets made of any ceramic composition such as a barium titanate-based semiconductor ceramic composition or a lead titanate-based ceramic composition. Example 2: A ceramic slurry was prepared by adding 0.5 parts by weight of dibutylmethylethylammonium acetate to 100 parts by weight of barium titanate dielectric ceramic raw material. Using this slurry, a 10 μm thick green sheet was formed on a carrier film by a doctor blade method. After printing a paste for internal electrodes of a multilayer capacitor on this sheet, the sheets were laminated by a conventional method to produce a multilayer capacitor. Separately, a slurry was prepared using the same ceramic raw material as in Example 2 without the addition of a quaternary ammonium salt, and a multilayer ceramic capacitor was fabricated in the same manner. The short circuit rate and number of voids were investigated for each of the obtained multilayer ceramic capacitors. The results are shown in Table 1. [Table 1]
Table 1
Quaternary ammonium salt

Additive-free
Addition Short rate 15 pieces/100 pieces
6/100 voids
8 pieces/10 pieces 2 pieces/10 pieces As is clear from the results shown in Table 1, the short-circuit ratio and the number of voids were significantly improved by adding the quaternary ammonium salt, and the initial value of the multilayer ceramic capacitor was Defects can be suppressed. This is considered to be because the static electricity of the ceramic green sheet was reduced, and the adhesion of dust and the like was reduced. According to the present invention, the following excellent effects can be obtained by adding a predetermined amount of quaternary ammonium salt to the slurry when producing ceramic green sheets. [0023] Since the surface resistance of the ceramic green sheet can be reduced, even if the green sheet is charged after manufacturing, the charging voltage can be extremely low, and the half-life of the charging voltage can be greatly shortened, so the ceramic green sheet can be It can prevent dust from adhering to sheets, wrinkles, and crinkling when stacked due to static electricity. In addition, the static elimination effect of the quaternary ammonium salt is not temporary, but lasts until it disappears due to thermal decomposition, so that physical static elimination is not required after formation, and handleability can be improved. Furthermore, when preparing a ceramic slurry, the dispersibility of ceramic powder particles or ceramic raw material powder particles can be improved. Moreover, these synergistic effects can improve the quality of ceramic electronic components.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the amount of quaternary ammonium salt added and the charging voltage of a ceramic green sheet.

FIG. 2 is a diagram showing the relationship between the amount of quaternary ammonium salt added and the half-life of the charging voltage of a ceramic green sheet.

Claims (2)

[Claims] Claim 1: Based on 100 parts by weight of the raw material powder of the ceramic composition, a fourth powder containing no halogen or metal element is added.
1. A method for producing a ceramic green sheet, which comprises preparing a ceramic slurry by adding 0.05 to 3 parts by weight of a class ammonium salt. [Claim 2] The quaternary ammonium salt has the general formula:
R4NX (However, R is the same or different and represents an alkyl or aryl group, and X is NO2-, NO3-, CH3COO
- represents. 2. The method according to claim 1, wherein the quaternary ammonium salt is at least one of the following quaternary ammonium salts.