JP2996052B2 - Manufacturing method of ceramic electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic electronic component, and more particularly to a method for manufacturing a ceramic electronic component including a step of rounding a corner portion of a ceramic green chip before sintering.

[0002]

2. Description of the Related Art For example, in a ceramic electronic component such as a multilayer capacitor, a corner portion is rounded. The reason will be described with reference to FIG. 3 taking a multilayer capacitor as an example.

A multilayer capacitor is obtained by laminating a plurality of ceramic green sheets on which a conductive paste for forming an internal electrode is printed, to obtain a laminated green chip, press-bonding the green chip in the thickness direction, and then firing. It has been manufactured by applying an external electrode to the drawn end face of the internal electrode.

In the above process, as shown in FIG. 3, when the obtained ceramic sintered body 11 is square,
That is, when the corner portions 11a where the respective surfaces of the sintered body 11 are connected are square, the external electrodes 12 and 13
Was sometimes cut at the corner 11a.

[0005] The external electrodes 12 and 13 are
a, the multilayer capacitor 10 is placed on the printed circuit board from the lower surface side, and when the multilayer capacitor 10 is joined by reflow soldering or the like, the outer electrodes 12, 13 are placed on the lower surface 11b of the sintered body 11 Located parts 12a, 13a
Only the electrodes 12 and 13 of the internal electrodes 12 and 13 that are electrically connected to the internal electrodes cannot be electrically connected to the circuit on the printed circuit board.

Therefore, conventionally, by making the corner portion 11a round, the thickness of the external electrode is made uniform,
Attempts have been made to prevent the above-described electrical connection failure, to improve the solder heat resistance, and to prevent cracking and chipping of the sintered body in the manufacturing process and the mounting process on the substrate.

As a method for obtaining a sintered body in which the corner portions 11a are rounded as described above, there are a method in which the ceramic green chip is rounded before firing, and a method in which the sintered body after firing is polished. A method of adding roundness to a corner is known. The method of rounding before firing is, specifically, adding a raw material such as ceramic balls and steel balls together with ceramic raw chips and water as a buffer in a rotating container, and rotating the rotating container. It was done by.

[0008]

However, when the above-mentioned ceramic raw chips, water and an abrasive are put into a rotary container and polished by rotation, the temperature in the rotary container rises due to friction caused by collision of the abrasives, and the ceramics are removed. There is a problem that the raw chips easily adhere to each other. Therefore, conventionally, the above-described rotary polishing has to be performed after each ceramic green chip cut from the mother green laminate is dried to a certain degree of drying in advance to reduce the adhesion of the ceramic green chip.

Further, after the completion of the rotary polishing, a complicated cleaning step has to be performed in order to remove the abrasive attached to the ceramic green chip. An object of the present invention is to omit the drying step and the step for separating the abrasive as described above, and therefore, a ceramic electronic component having a step capable of efficiently rounding a corner portion of a ceramic green chip. It is to provide a manufacturing method of.

[0010]

SUMMARY OF THE INVENTION The present invention is a method of manufacturing a ceramic electronic component in which a step of rounding a corner portion of a ceramic green chip prior to firing is improved, comprising the following steps.

In the present invention, first, a step of preparing an unfired ceramic green chip is performed. The step of preparing the unfired ceramic green chip can be performed according to a known method conventionally employed in a method of manufacturing a ceramic electronic component.

In the present invention, a plurality of ceramic raw chips prepared as described above and only a liquid as a buffer are placed in a polishing container, and the container is rotated or vibrated to give a raw material. The corners of the chip are rounded.

The liquid is used as a buffer, and may be any liquid as long as the collision between the ceramic raw chips and the inner wall of the container and the collision between the ceramic raw chips can be moderately reduced without dissolving the binder or the like of the ceramic raw chips. For example, water, an inert solvent, and the like can be used.

[0014]

According to the present invention, the container is rotated or vibrated in a state where only a plurality of ceramic raw chips and a liquid as a buffer are charged into the polishing container.
By giving this rotation or vibration, the ceramic raw chips in the container collide with each other, thereby rounding the corners of the ceramic raw chips. in this case,
The liquid functions as a buffer, and moderates the collision between the ceramic raw chips and the collision between the ceramic raw chips and the inner wall of the container to an appropriate level.

In the present invention, since the corners of the ceramic raw chips are rounded by the collision of the ceramic raw chips as described above, the abrasive material made of ceramic balls or steel balls, which is required in the conventional method, is not required. Therefore, in the conventional method using an abrasive, there was a problem that the ceramic raw chips easily adhere to each other due to a temperature increase due to the collision between the abrasives, but in the present invention, such a temperature increase is unlikely to occur. The step of drying the ceramic raw chips prior to polishing can be omitted.

In the conventional method using an abrasive,
After the polishing, it was necessary to carry out a cleaning step of removing abrasives and polishing debris from the raw chips.However, in the present invention, since no polishing material is used, the temperature rise is unlikely to occur, so polishing debris to the raw chips Since the adhesion hardly occurs, the cleaning step for removing the abrasive can be simplified.

Therefore, according to the present invention, a ceramic green chip having a rounded corner can be obtained much more efficiently than the conventional method, and therefore, the productivity of ceramic electronic components can be effectively increased.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing embodiments of the present invention. The following examples are applied to a method for manufacturing a multilayer capacitor.

First, a dielectric ceramic powder such as barium titanate, an organic binder, a plasticizer and an organic solvent are kneaded to obtain a ceramic slurry, and a ceramic green sheet is obtained according to a known sheet forming method such as a doctor blade method. Next, the obtained ceramic green sheet is punched into a rectangular shape having a predetermined size to prepare a mother ceramic green sheet.

By printing a conductive paste on the upper surface of the obtained mother ceramic green sheet, an electrode pattern for forming a plurality of internal electrodes is formed. Next, a plurality of ceramic green sheets on which the electrode patterns are printed are laminated, and an appropriate number of ceramic green sheets on which no electrode patterns are formed are laminated on the upper and lower sides to obtain a mother laminate. After the obtained mother laminate is pressed in the thickness direction, it is cut in the thickness direction in order to obtain a ceramic green chip for each individual multilayer capacitor.

The raw ceramic chips of the individual multilayer capacitors cut out as described above are put into the polishing container 1 shown in FIG. The polishing container 1 has a lid 1a, and is configured to be rotatable about a central axis extending in the longitudinal direction thereof. This rotation is performed by connecting to a rotation drive source such as a motor (not shown). The polishing container 1 itself is no different from a polishing container conventionally used in a method of manufacturing a ceramic electronic component.

In polishing, the lid 1a is removed, water and a plurality of ceramic raw chips are charged, and the lid 1a is closed. FIG. 2 is a sectional view showing the internal structure in this state. FIG.
In the figure, 2 indicates a ceramic raw chip, and 3 indicates water.

Next, the polishing container 1 is connected to a rotation drive source (not shown) and rotated. Due to this rotation, the ceramic raw chips 2 collide with each other, and the corners of the ceramic raw chips 2 are rounded. In this case, unlike the conventional method,
Since no abrasive is used, a rise in temperature during rotary polishing hardly occurs. Therefore, the ceramic raw chip 2
After preparing, a complicated drying step of sufficiently drying can be omitted. Moreover, since it is not necessary to remove the abrasive after the corner portion is rounded, there is no need to perform a complicated cleaning step as in the conventional method.

Next, more specific experimental examples will be described. Ceramic powder containing barium titanate as a main component,
A mother ceramic green sheet was prepared using polyvinyl butyral having a glass transition point of 60 ° C. as an organic binder, a plasticizer, and the like. Next, a mother laminated body was obtained using the mother ceramic green sheet according to the method of the above-described embodiment, and the mother laminated body was cut out to obtain a large number of rectangular ceramic raw chips.

The obtained ceramic green chip was placed in the polishing vessel 1 so as to occupy about 50% of the total internal volume without going through a drying step. Similarly, pure water was added so that the total amount was about 80% of the total internal volume of the polishing container 1, and the polishing container 1 was closed with the lid 1a. Thereafter, the polishing container 1 was rotated at a rotation speed of 150 rpm for 1 hour. After the rotation was completed, the ceramic raw chips 2 inside were taken out, and it was confirmed that the corners were rounded with a radius of curvature of about 0.1 mm and that the ceramic raw chips 2 hardly adhered to each other. .

When the temperature of pure water before and after rotation was measured, it was 24 ° C. before rotation and 25 ° C. after rotation was completed.
It was confirmed that the temperature hardly increased due to the rotation. Therefore, according to the method of the present embodiment, which does not use an abrasive, it can be seen that a rise in temperature can be reliably prevented, probably because heat generation due to collision between the abrasives does not occur.

In the conventional method, when the temperature during the rotational polishing is raised to a temperature equal to or higher than the glass transition point of the organic binder used for obtaining the ceramic green chips, the ceramic green chips tend to adhere frequently. Therefore, in the conventional method, it is necessary to control the temperature rise due to the collision between the abrasives to be equal to or lower than the glass transition point of the organic binder. In the production method described above, since the above-described temperature rise is unlikely to occur, such temperature control does not need to be performed, and there are few restrictions on the organic binder used.

Although the above embodiment is applied to a method of manufacturing a multilayer capacitor, the method of the present invention
It should be pointed out that the present invention can be applied to other ceramic multilayer electronic components such as multilayer inductors, and general methods for manufacturing ceramic electronic components such as non-laminate ceramic piezoelectric components.

Further, in the present invention, the step of rounding the corner portion of the ceramic green chip as described above is improved, and the following steps for obtaining a ceramic electronic component using the rounded ceramic green chip will be described. Can be performed according to a conventionally known method for manufacturing a ceramic electronic component.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a polishing container.

FIG. 2 is a partially enlarged cross-sectional view illustrating a state of a ceramic raw chip and water put in a polishing container.

FIG. 3 is a cross-sectional view of a multilayer capacitor for describing a problem of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1: Polishing container 1a: Lid 2: Ceramic raw chip 3: Water

Claims (1)

(57) [Claims] 1. An unfired ceramic green chip is prepared,
Placing only a plurality of the ceramic raw chips and a liquid in a polishing container, and turning or vibrating the container to round the corners of the ceramic raw chips. Manufacturing method of electronic components.