JPH03148814A - Manufacture of material for capacitor - Google Patents

Abstract

PURPOSE:To reduce the dispersion in capacitance of a capacitor for augmenting the yield by a method wherein the whole quantity of minute additive and ceramic material in specific ratio are pre-mixed and then the premixed material and residual quantity of ceramic base material are regular-mixed. CONSTITUTION:1-20wt.% of the whole quantity of Nb2O5 and SrTiO3 as well as the water in double quantity of the whole powder are agitated in a ball mill for 15 hours, premixed, dehydrated and dried up to produce the powder. Next, residual SrTiO3 and double wt. quantity of water are added to this powder and after agitation for 15 hours, dehydration-drying up processes, 5wt.% of polyvinyl alcohol as a binder is added to granulate and then pressure-molded in a molder. Next, this molded product is fed to a furnace and after burning the binder in the furnace, the product is baked in the furnace changed into a reducing atmosphere to produce a semiconductor ceramic as well as a grain boundry insulated dielectric ceramic by performing a coating process with paste and a heating process. Finally, both surfaces are coated with silver paste and then baked to form electrode so that semiconductor capacitor may be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of manufacturing a material for a capacitor.

(Prior Art) Conventionally, materials for capacitors have been manufactured using 13aTi, for example, in the case of semiconductor capacitors.

s, SrTiO3, CaTiOs, etc., NbzOs, Y203, B1zO
This was done by blending and dispersing trace additives such as s in a ball mill, but the milling and dispersion of the trace additives was not done sufficiently, which caused variations in the capacitance of the finished capacitors. .

Therefore, after pulverizing only trace additives in a ball mill,
A method of adding and mixing it to the base material was proposed. A method of mixing using a bead mill using beads with a diameter of 1 to 2 mm has also been proposed.

(Problems to be Solved by the Invention) However, in the method of pulverizing only the above-mentioned trace additives in a ball mill and then adding and mixing them to the base material,
Re-agglomeration of the pulverized additives occurred, and dispersibility was not improved, nor was variation in capacitance improved.

In addition, in the method of mixing using a bead mill using beads with a diameter of 1 to 2 mm, the base material is pulverized at the same time as the additive is dispersed, resulting in uneven particle size, which reduces the capacitance. There were cases where variations occurred and molding defects occurred during extrusion molding, and no improvement effect was obtained.

Therefore, the present invention is capable of pulverizing trace additives and highly dispersing them into the paste material, and at the same time, the base material is pulverized.
It is an object of the present invention to provide a method for producing a capacitor material that can prevent particle size from becoming non-uniform.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a method for manufacturing a capacitor material by mixing a small amount of additives into a ceramic paste material. The method is characterized in that 1 to 20 wt% of the total amount of the materials is premixed, and then this premix is mixed with the remaining amount of the ceramic base material.

(-Effect) In the method for manufacturing a capacitor material according to the present invention,
First, by mixing the entire amount of the trace additive and a portion of the base material, pulverization of the trace additive is promoted. As a result, even if reaggregation occurs thereafter, the trace additive will coagulate together with the base material, so that the dispersed state will be maintained.

Further, since the remaining base material is then mixed with the above-mentioned premix, unnecessary pulverization is not performed and the particle size of the base material does not become non-uniform.

(Example) Hereinafter, examples of the present invention will be described together with comparative examples and conventional examples with reference to the accompanying drawings.

First, in the following descriptions of Examples 1 to 4, Comparative Examples 1.2, and Conventional Example 1, SrTiO as the base material is used.
995 parts by weight, N b x O as a trace additive
The following explanation assumes that s is added in an amount of 5 parts by weight.

First, the total amount of NbzOs and 1 of the total amount of SrTiO3
wt% and water in an amount twice as much by weight as the total amount of these powders were stirred in a ball mill for 15 hours to perform premixing. Next, this premix was dehydrated and dried to obtain a powder. To the thus obtained powder, the remaining SrTiO and water in an amount twice as much as the total amount of these powders were added, and the mixture was stirred and mixed in a ball mill for 15 hours.

After dehydrating and drying this mixture, 5 wt% of binder was added.
of polyvinyl alcohol was added thereto and granulated, and the granulated product was put into a molding machine and pressure-molded into a disk shape at a pressure of 1000 kg/cm''.

Next, this molded product was placed in a furnace and heated to 800 m
The temperature was raised at a rate of 100°C per hour to burn the polyvinyl alcohol as a binder.

Thereafter, the inside of the furnace was changed to a reducing atmosphere of 97 N2, 1% Qvo, and 1% H-, and the temperature was maintained at 1400° C. for 3 hours to obtain semiconductor ceramics.

Furthermore, a paste containing CuO as a component was applied to this disk-shaped semiconductor ceramic, and the temperature was raised at a rate of 100 °C per hour and the temperature was maintained at 1200 °C for 3 hours to diffuse CuO into the grain boundaries of the semiconductor ceramic. A grain boundary insulated dielectric ceramic having a thickness of 0.50 mm and a diameter of 16 mm was obtained.

Next, Nami paste was applied to both sides of this dielectric ceramic and baked at 800° C. to form electrodes with a diameter of 1 mm to obtain a semiconductor capacitor.

Fruit 11112”.

The mixing amount of SrTiOs in the above premixing was 5wt%.
, 10 wt%, and 20 wt%, semiconductor capacitors were obtained in the same manner as in Example 1, and these were used as Example 2.
It was set to h to 4.

Ratio U The mixing amount of SrTiOs in the above premixing is Q, 5w
t% and 30wt%, semiconductor capacitors were obtained in the same manner as in Example 1, and these were used as Comparative Examples 1 and 2, respectively.
And so.

1 The entire amount of NbxOs and the entire amount of SrTiOs were mixed at one time, and the granulation process and subsequent steps were carried out in the same manner as in Example 1 to obtain a semiconductor capacitor, which was designated as Conventional Example 1.

Next, in the following descriptions of Examples 5 to 8, Comparative Examples 3.4, and Conventional Example 2, SrTiO* as the base material is used.
The explanation will be given assuming that 5 parts by weight of N b z Os and 25 parts by weight of Biass are added as trace additives to 970 parts by weight.

[Act] Iretsu” - First, the total amount of N b x Os and 131205,
3. 1 wt% of the total amount of TiOs and 2 times the amount of water based on the total amount of these powders were mixed in a ball mill.
The mixture was stirred for 5 hours and premixed. Next, this premix was dehydrated and dried to obtain a powder. To the thus obtained powder, the remaining SrTiOs and water in an amount twice as much as the total amount of the powder were added, and the mixture was stirred and mixed in a ball mill for 15 hours.

Thereafter, a semiconductor capacitor was obtained in the same manner as in the above example.

5.21 The mixing amount of S r Ti Os in the above premixing is
5wt%, lQwt%, and 20wt%, and the above Example 5
Semiconductor capacitors were obtained in the same manner as in Example 6 to Example 8, respectively.

Ratio m The mixing amount of S r T i Os in the above premixing is
Q, 5 wt% and 30 wt%, semiconductor capacitors were obtained in the same manner as in Example 5, and these were respectively used in Comparative Example 3.
．． It was set as 4.

1 pot ■l The entire amount of NbzOs and Bi,03 and the entire amount of SrTi03 were mixed at one time, and the granulation process and subsequent steps were carried out in the same manner as in Example 5 to obtain a semiconductor capacitor, which was designated as Conventional Example 2.

The above Examples 1 to 8, Comparative Examples 1 to 4, and Conventional Example 1,
For 2, 100 sample semiconductor capacitors were prepared for each sample, the capacitance was measured, and the variation in capacitance, that is, the standard deviation, was measured based on the capacitance obtained by this measurement. . The results are shown in the attached graphs of FIGS. 1 and 2.

Although the above embodiments have all been described using materials for semiconductor capacitors as examples, the present invention is not limited thereto, and can be used for other materials for ceramic capacitors.

(Effects of the Invention) According to the method for producing capacitor materials of the present invention as described above, as can be seen from the attached graphs of FIGS. 1 and 2, variations in capacitance of capacitors can be greatly reduced. Therefore, the yield of capacitor manufacturing can be improved, and it is possible to cope with the narrowing of the allowable capacitance range.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are graphs showing the standard deviation of capacitance of capacitors according to an example of the present invention, a comparative example, and a conventional example, respectively.

Claims (1)

[Claims] In a method of manufacturing a capacitor material by mixing a trace additive with a ceramic base material, the total amount of the trace additive and the total amount of the ceramic base material are 1 to 20 wt%.
1. A method for manufacturing a capacitor material, comprising: premixing the premix with the remaining amount of the ceramic base material.