JP2917335B2 - Manufacturing method of ceramic electronic components - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic electronic component such as a barium titanate-based PTC thermistor used for a self-heating element or the like in an electric circuit.

Conventional technology Barium titanate-based PTC thermistors
It was manufactured by the manufacturing method shown in the figure.

That is, the main components and additives wet-mixed in the mixing step 1 are dried in the dehydration / drying step 2, and then this is subjected to primary calcination in the calcination step 3 and then crushed in the crushing step 4 to granulate. It has been produced by granulating in step 5, shaping it in forming step 6, and sintering in firing step 7.

Problems to be Solved by the Invention However, in the above-mentioned conventional manufacturing method, measures against room temperature resistivity change caused by lot-to-lot variation of raw materials were implemented before the granulation step. For this reason, in the granulation process during mass production, several hundreds of
When granulation of kg is carried out, if the room temperature resistivity value of the sintered body obtained by molding and firing the granulated powder greatly differs from the target value, this large amount The granulated powder was lot-out.

Therefore, the present invention solves such a problem,
The purpose is to improve the productivity of the granulated powder once granulated.

Means for Solving the Problems In order to achieve this object, the present invention provides a granulation step and a secondary mixing step of newly impregnating and mixing a specific resistance adjusting agent between the molding step. It is characterized by the following.

According to the above-described means, the room temperature specific resistance of the sintered body obtained by initially forming and firing a part of the granulated powder once granulated satisfies the target specific resistance. If not,
The specific resistance can be adjusted by impregnating the granulated powder with Mn, Cu, or the like in a solution state of a nitrate, a sulfate, or the like and uniformly mixing the impregnated powder. Therefore, lot-out of a large amount of granulated powder is eliminated.

Example Hereinafter, an example of the present invention will be described.

FIG. 1 shows a flowchart of the steps performed in the present invention.

First, in the mixing step 8, (Ba _0.75 Pb _0.25 ) TiO ₃ as a main component and Nb ₂ O ₅ , Si as additives are added in advance.
O _2, Mn (NO ₃₎ blended those _two each from 0.001 to 0.024 moles of the composition was carried out wet mixing in a ball mill. Next, the mixed powder dried in the dehydration / drying step 9 is
Calcination was performed at 1100 ° C., and thereafter, in a pulverizing step 11, wet pulverization was performed using a ball mill until the particle diameter became 2.0 μm or less. Then, 5% by weight of this was dried in the granulation step 12
PVA (polyvinyl alcohol) is 10wt% to the raw material
It was added and granulated.

Then, a part of the sample was sampled and formed into a disk having a diameter of 17.5 mm and a thickness of 4.0 mm by applying a pressure of 1 ton / cm ² ,
It baked for 1 hour in 0 degreeC-1300 degreeC air.

On the other hand, as the secondary mixing step 13, a part of the granulated powder was sampled and processed. At this time, Mn was used as a resistivity adjuster.
Using the (NO ₃ ) ₂ solution, the weight% of Mn (NO ₃ ) ₂ was 1 to 3 based on the value obtained by converting the weight of the granulated powder into the weight of the pulverized powder.
%, Diluted with pure water so as to obtain a molar ratio of Mn in multiple steps, and added, followed by secondary mixing (shown in Table 1 below).

As an addition method, the volume converted from the number of moles of the Mn (NO ₃ ) ₂ solution is accurately measured using a whole pipette,
This was dropped or sprayed only on the sampled granulated powder and dispersed in a polypot or the like, dry-mixed and thoroughly dispersed and impregnated.

Then, the secondary mixed powder is molded in the molding step 14 in the same manner as the first sampled powder, and then fired in the firing step 15, each of which has an ohmic property.
An Al electrode was provided.

Table 2 below shows the room-temperature specific resistance and the results of the voltage-breakdown test of the samples prepared in the secondary mixing step 13.

Here, the results of the voltage-breakdown test indicate a voltage value at which the element was broken when the voltage was increased from 100 V from both ends of the sample electrode in steps of 20 V at intervals of 30 seconds at a step of 20 V as a withstand voltage value.

As is clear from Table 2 above, Sample Nos. 2, 3, and 4 showed Mn (NO
₃ ) It can be seen that the room temperature resistivity increases stepwise with the addition amount of ₂ . Further, it can be seen from the withstand voltage value at this time that no element deterioration or the like has occurred.

On the other hand, it was experimentally confirmed that the application range of the secondary mixing can be similarly applied to a barium titanate-based PTC thermistor granulated powder other than the composition in the above-described example.

Advantageous Effects of the Invention As described above, the present invention provides a method for forming a granulated powder that has been granulated once, and then setting the room temperature resistivity of the sintered body obtained by molding and firing the granulated powder to the target resistivity. If it is less than
The room temperature specific resistance can be adjusted by impregnating the granulated powder with a solution containing an element contributing to specific resistance adjustment.

Therefore, the granulated powder that has been granulated once is not lot-out, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart of one embodiment of the present invention, and FIG. 2 is a flowchart of a conventional example. 13 Secondary mixing step.

Claims (1)

(57) [Claims] 1. A mixing step of wet-mixing a main component and a primary additive, a dehydration / drying step of dehydrating / drying the wet-mixed product, and a step of dehydrating / drying the dehydrated / dried product. A calcining step of next firing, a pulverizing step of pulverizing the calcined substance, a granulating step of adding a binder to the pulverized substance, and a granulating step, and then the pulverized substance A secondary mixing step of impregnating the mixture with a specific resistance adjuster, followed by a molding step of pressing the secondary-mixed product into a required shape, and then firing the molded product by sintering And a method of manufacturing a ceramic electronic component.