JPH06251983A - Manufacture of laminated ceramic electronic part - Google Patents

Abstract

PURPOSE:To prevent interlayer separation of a ceramic green sheet laminate by a method wherein air bubbles are prevented from being left between laminated sheets when the green sheet laminate is hydrostatically pressed. CONSTITUTION:Finely powdered talc is previously applied onto the surface of a containing section of a frame 4 provided with a base plate, and a ceramic green sheet laminate is set inside the containing section. The laminate and a jig are put in a flexible sheathing bag 7 and hermetically sealed up under vacuum, then two opening of the flexible sheathing bag 7 is sealed up, and the sheathing bag 7 is put in an outer bag 13 and hermetically sealed, which is hydrostatically compressed in a hydrostatic press 14.

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 an electronic component which is formed by laminating ceramic green sheets such as ceramic multilayer capacitors, varistors and thermistors.

[0002]

2. Description of the Related Art As a method for manufacturing a ceramic multilayer capacitor, for example, in Japanese Patent Laid-Open No. 61-159719,
Each ceramic green sheet with internal electrodes is laminated and held in a metal frame, the area surrounded by this frame is covered with a flexible sheet, and the air in this area is extracted by vacuum. It has been proposed that a method of sealing with a hydrostatic press and then applying pressure with a hydrostatic press is used.

Further, in Japanese Patent Laid-Open No. 2-305419, ceramic green sheets each having an internal electrode formed thereon are laminated and held in a metal frame body, and the laminated ceramic green sheets are flexible together with the frame body. A method is disclosed in which a bag is kept in a vacuum state to remove air between the layers, and then the vacuum packaged product is pressure-bonded under normal pressure.

Thereafter, the laminated body of the ceramic green sheets after pressure bonding is cut into chips having a predetermined size so that the end faces of the pair of internal electrode portions appear on the opposite side faces of the chip,
External electrodes that are electrically connected to the end faces of the respective internal electrode portions are formed by coating and then fired.

[0005]

However, in each of the above-mentioned prior arts, if the air extraction between the stacks of the ceramic green sheets is incomplete in vacuum packaging, the stack is hydrostatically pressed in a subsequent step. Since the bubbles remain between the layers even when (pressurized), there is a problem that the residual bubbles expand due to the heating in the subsequent process and delamination easily occurs.

Since the frame body is made of metal, the surface of the laminated body and the surface of the frame body are easily adhered to each other when the isostatic pressing is performed.
When the laminated body is taken out from the frame body, the laminated body is deformed at the contact portion, so that defective products are often generated, resulting in a problem that product yield is deteriorated. The present invention aims to solve these problems.

[0007]

In order to achieve the above object, the invention of the method for producing a monolithic ceramic electronic component according to claim 1 is to spread powder on a surface of a jig of a floor plate or a frame body made of a porous material. A step of applying or laying release paper,
It comprises a step of setting a laminated body of ceramic green sheets on this jig, and a step of hydrostatic pressing in a state where the laminated body and the jig are sealed in a flexible covering bag.

According to the second aspect of the invention, the laminate and the jig are vacuum-sealed in a flexible covering bag, and then the covering bag is sealed. The process of isostatic pressing is performed.

[0009]

EXAMPLE Next, an example in which the present invention is embodied will be described. In a laminated ceramic capacitor, a ceramic dielectric having an internal electrode formed by printing is laminated on the surface, and the end of the internal electrode is formed at both ends of a capacitor chip. A laminate 1 that is electrically connected to the outside and is shown in FIGS. 1 and 2.
Is a silver-paradium-based material on a wide surface of a so-called ceramic green sheet 2 in an unfired state in which a ceramic dielectric material containing titanium oxide or barium titanate as a main component as a ceramic dielectric is formed in a rectangular flat plate shape in a plan view. Alternatively, it is formed by stacking a plurality of printed internal electrodes 3 made of Pd metal or the like. This laminated body 1 is cut in the thickness direction (short axis direction) of the laminated body 1 so as to be divided into a plurality of capacitor chips later. A first embodiment as a jig for setting the laminated body 1 is a frame body 4 with a bottom plate,
The frame body 4 made of an open-cell porous material is a flat box having an open upper surface, and has a storage portion 5 in which the laminated body 1 can be stored.

The frame body 4 is hard to be deformed by the pressure of a hydrostatic press, which will be described later, and is made of a material having heat resistance and a small coefficient of thermal expansion. For example, a material such as β-wollastonite, mica, alumina, and siliceous material is formed to be porous. In addition, Ca ・ nSiO ₂ system, Al ₂ O-TiO ₂ system, K ₂
An O.nAl ₂ O ₃ -based ceramic powder is pressure-molded at a low density and fired to form an open-cell porous sintered body. In addition, when the metal fiber is compression-molded and then sintered in a predetermined atmosphere at a predetermined temperature, a fiber sintered body is obtained, which is also a porous body having continuous cells. The porous material may be an organic material.

Further, when the ceramic green sheets 2 are pressure-bonded to each other in a laminated state, that is, when the isostatic pressing work is performed with the laminated body 1 being set on the frame body 4, the binder contained in the green sheets 2 is generally used. Since pressurization is performed while being heated to a temperature equal to or higher than the glass transition point, at this time, the frame body 4 is preferably made of a material having heat resistance and a small coefficient of thermal expansion.

As a first embodiment of the manufacturing method, as shown in FIG. 2, the front surface (bottom surface and 4 of the housing 5 of the frame 4 is described.
First, fine powder talc 6 as a spread powder is applied to the peripheral surface).
Next, the stack 1 is stored (set) in the storage section 5.
Then, the frame body 1 containing the laminated body 1 is placed in a flexible covering bag body 7 made of nylon or the like, and the frame body 1 is placed on a placing table 9 in a vacuum chamber 8. At this time, the opening 7 a of the covering bag 7 is placed on the sealing table 10. Then, the vacuum pump 11 is operated to evacuate the air inside the coated bag body 7, and the laminated body 1
The air bubbles existing in the inner laminated portion are degassed (see FIG. 3).
After that, the heat seal body 12 is pressed toward the sealing table 10 to seal the opening 7a of the covering bag body 7.

The outer side of the hermetically sealed cover bag 7 taken out from the vacuum chamber 8 is covered with another outer bag body 13,
The opening is sealed with a heat seal device (not shown),
Next, as shown in FIG. 4, the frame body 4 and the laminated body 1 which are doubly sealed by the outer bag body 13 and the covering bag body 7 are housed in the working chamber 15 of the hydrostatic press device 14 as shown in FIG. The hydrostatic pressurization is executed by a predetermined pressurization process (program) as shown in FIG. That is, the working chamber 15 having a large diameter and the pressurizing portion 16 having a small diameter in the hydrostatic pressing device 14 are communicated with each other by a communication pipe 17 having a shutoff valve 20, and the pressurized fluid 18 such as water or oil is filled therein. Then, when a predetermined pressurizing force is applied to the pressurizing plunger 19 in the pressurizing unit 16, equal pressures act on the object in the working chamber 15 through the pressurizing fluid 18 from the three directions of XYZ, It is possible to carry out the pressure bonding of the ceramic green sheets 2 in a laminated form.

By the way, in the above-mentioned embodiment, since the laminated body 1 is accommodated in the frame body 4 with the bottom plate, when the hydrostatic pressure is applied, the laminated body 1 is opened in the accommodating portion 5 of the frame body 4. Upon receiving pressure from the side, the laminate 1 is compressed in a direction perpendicular to the wide surface (the thickness direction of the laminate), and the plurality of ceramic green sheets 2 are pressure-bonded in a laminate. At this time, the air bubbles (air) remaining between the layers of the laminated ceramic green sheets 2 move into the inside of the frame body 4 made of a porous material and are absorbed, so that the interlayer peeling (delamination) occurs. It is possible to almost completely eliminate the residual bubbles between the layers of the ceramic green sheet 2 which cause the generation.

If the shape of the housing 5 of the frame body 4 in plan view is made substantially equal (slightly larger) to the shape of the laminate 1 in plan view, the laminated ceramic green sheets 2 are less likely to laterally shift between layers. Therefore, it is possible to reduce the occurrence rate of defects at the time of cutting into chip pieces in a later process. Furthermore, since the frame body 4 is made of a porous material, the surface of the housing portion 5 has large irregularities (surface roughness). Therefore, when the laminated body 1 is brought into direct contact with the surface of the accommodating portion 5, the laminated body 1 is attached (adhered) to the accommodating portion 5 of the frame body 1 by the subsequent pressurization (hydrostatic press) and removed. However, if the laminated body 1 is to be removed by an unreasonable external force, the laminated body 1 may be collapsed. In order to avoid the inconvenience, by applying the differential talc 6 to the surface of the housing portion 5 of the frame body 4 in advance, it becomes extremely easy to remove the laminated body 1 from the frame body 4 after the hydrostatic pressing.

In FIG. 5, instead of the frame body 4 with the bottom plate,
A second embodiment in which a flat plate 22 made of a porous material is used is shown. The shape of the plate 22 is formed slightly larger than the plan view shape of the laminate 1, and the differential talc 6 is formed on the surface of the plate 22. After applying the ceramic green sheet 2
Are mounted in a laminated state. In the subsequent steps, as in the case of the above-described embodiment, the inside of the cover bag body 7 is evacuated, the opening 7a of the cover bag body 7 is sealed, and then the outer bag body 13 is sealed again. Perform a hydraulic press.

In the second embodiment, the floor plate 22 and the laminated body 1 are used in the vacuuming and heat sealing (sealing work).
Is held in a horizontal posture, the covering bag body 7 is brought into close contact with the outer peripheral surfaces of the floor plate 22 and the laminated body 1, and the lateral displacement movement between the ceramic green sheets 2 between the laminated layers and the surface of the floor plate 22 is performed. It is possible to prevent lateral displacement of the entire laminated body 1.

Table 1 shows a conventional example using a conventional dense metal floor plate (frame body) and the floor plate 22 of the porous material of the present invention.
It is a comparison of the delamination occurrence rate when the (frame body 4) is used. In this comparative experiment example, the conditions such as vacuuming and double sealing with a bag before the isostatic pressing process are the same. Further, the pressurizing time is as shown in FIG.
As shown in, the maximum pressure holding time T (unit: minute) is referred to.

The delamination occurrence rate is 100 (chip number) as a final product (external electrode formed) after the laminated body 1 is hydrostatically pressed and then cut (cut) into a predetermined capacitor chip size. The electrical characteristics of each piece are inspected and the number of defective products is counted. In Table 1, the numbers in parentheses indicate the case where the frame body 4 with a bottom plate is used.

[0020]

[Table 1]

Table 2 shows a case where the laminated body 1 is set on the floor plate 22 and shows the deformation rate of the plan view shape of the laminated body 1 after performing the hydrostatic pressing after the evacuation. The maximum pressure of the hydrostatic press is 300 Kg / cm ² , and the pressure holding time is 3 minutes. The material is a laminated body 1 of 150 mm square on each side, and each side A, B, C, D (see FIG. 7).
Table 2 shows the expansion / contraction ratios of the lengths as the deformation ratios. Number of materials is 1
The number is 0 and the average value is shown in Table 2.

[0022]

[Table 2]

As can be understood from the results in Table 2, the deformation rate is extremely smaller in the case of the manufacturing method of the present invention, and therefore, the occurrence of the defective rate when the capacitor chip pieces are cut later can be reduced. Has the effect of being able to. Note that FIG. 8 shows a frame body 23 made of a porous material, and since the storage portions 5 and 5 are formed on both upper and lower surfaces, the frame body 2 is formed.
A partition plate 23a is integrally formed in the middle of 3,
A third embodiment in which the laminated body 1 of the ceramic green sheets 2 is set after the differential talc 6 is applied to the inner peripheral surfaces of the upper and lower storage portions 5, 5 will be described. The subsequent steps are the same as those in the first embodiment.

Further, FIG. 9 shows a ceramic green sheet 2 similar to the above in a frame body 24 having only a four-circle frame without a bottom plate.
4 shows a fourth embodiment in which the laminated body 1 in which the ceramic green sheets 2 are laminated is housed. Is inserted into the frame of the frame body 24 and is evacuated while being inserted into the flexible covering bag body 7.
After the opening 7a is sealed, it is put in the outer bag body 13 again and sealed, and then the hydrostatic pressing is performed.

Further, after the laminated body 1 is set on the frame body 4 (23, 24) or the floor plate 22, the laminated bag body 7 is sealed without vacuuming, and further sealed by the outer bag body 13 if necessary. Then, the process of hydrostatic pressing may be performed next. Even in this case, the air bubbles (air) remaining between the layers of the laminated ceramic green sheets 2 move into the inside of the frame body 4 made of a porous material and are absorbed, so that the interlayer peeling ( It is possible to almost completely eliminate the residual bubbles between the layers of the ceramic green sheet 2 which cause delamination.

The frame 4 (23, 24) or floor plate 22
When setting the laminated body 1 on the substrate 1, instead of the differential talc applied to facilitate the subsequent taking-out of the laminated body, a porous release paper is used for the frame 4 (23, 24) or the floor plate 22 and the laminated body 1. It may be interposed between the contact surfaces with and. The double bag for sealing is to prevent fluid from entering the inside of the bag due to a hole being opened in the bag during the hydrostatic press work, etc. It goes without saying that a single bag may be used.

By forming the outer peripheral edges and corners of the frame 4 (23, 24) and the floor plate 22 into a convex curved shape (so-called chamfering), the covering bag 7 and the outer bag 13 are formed. It is preferable that the frame body 4 (23, 24) and the floor plate 22 are covered, or the bag body is prevented from being scratched and not perforated when being put in the bag body or during transportation. Further, even after the evacuation is once performed, pressurization (hydrostatic pressure) to the laminate 1, that is, pressure bonding of the ceramic green sheets 2 into a laminated shape is included in the binder contained in the green sheets 2. When heated to a temperature equal to or higher than the glass transition point of No. 1, the residual solvent is vaporized from the ceramic green sheet 2 or from the internal electrodes printed on the sheet 2 by the heating, and the bubbles are accumulated between the laminated layers. As a result, delamination may occur after pressure bonding or firing, but in the present invention, the frame body 4 made of a porous material is used.
(23, 24) or when the laminated body 1 is set on the floor plate 22, when hydrostatic pressing is performed, air bubbles accumulated between the layers are pushed out toward the frame body 4 (23, 24) or the floor plate 22 to form a porous member. As it can be absorbed and retained in the quality,
The occurrence of the above-mentioned delamination can be eliminated.

[0028]

As described above, claim 1
In the invention described in (1), there is provided a method for manufacturing a laminated ceramic electronic component, the method comprising applying a spread powder or laying a release paper on the surface of a jig of a floor plate or frame made of a porous material, and the jig. And a step of hydrostatically pressing the laminate and the jig in a flexible covering bag, in which a hydrostatic pressure is applied. Then, the laminated body set on the frame body or the floor plate is compressed in a direction perpendicular to the wide surface (in the thickness direction of the laminated body), and a plurality of ceramic green sheets are pressure-bonded in a laminated form. At this time, the air bubbles (air) remaining between the layers of the laminated ceramic green sheets are
Almost completely eliminates residual air bubbles between the layers of the ceramic green sheet, which causes delamination due to transfer to the inside (holes) of the frame or floor plate made of porous material and absorption. The effect is that it can be done.

Furthermore, since the frame body or floor plate is made of a porous material, the surface irregularities (surface roughness) are large. Therefore, if the laminate is set so as to be in direct contact with a jig such as a frame or a floor plate, the laminate adheres (adheres) to the surface of the jig and is removed by subsequent pressurization (hydrostatic press). It becomes difficult to remove the laminated body with an unreasonable external force, which causes inconvenience such as collapse of the laminated body. However, it is extremely easy to remove the laminate from the jig after isostatic pressing by applying differential talc on the surface of the jig such as the frame or the floor plate in advance or laying a release paper. It has an effect.

In the invention according to claim 2, the laminate and the jig are vacuum-sealed in a flexible covering bag, and then the covering bag is sealed. Since the step of hydrostatic pressing is performed by using the above method, air bubbles remaining between the laminated ceramic green sheets can be positively removed before pressurization, and the delamination can be further eliminated. That is the effect.

[Brief description of drawings]

FIG. 1 is a perspective view of a ceramic green sheet and a frame body with a bottom plate.

FIG. 2 is a cross-sectional view in which a ceramic green sheet is set in a frame with a bottom plate.

FIG. 3 is a cross-sectional view of a vacuumed work state.

FIG. 4 is a cross-sectional view of a hydrostatic pressing device.

FIG. 5 is a cross-sectional view of a ceramic green sheet set on a floor plate.

FIG. 6 is a time chart of isostatic pressing work.

FIG. 7 is a plan view of a ceramic green sheet.

FIG. 8 is a cross-sectional view showing a state where ceramic green sheets are set in upper and lower storage portions of a frame body with a partition plate.

FIG. 9 is a cross-sectional view in which ceramic green sheets are laminated in a frame body without a bottom plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated body 2 Ceramic green sheet 4,23,24 Frame body 5 Storage part 6 Differential talc 7 Coated bag body 13 Outer bag body 14 Hydrostatic press device 22 Laying board

Claims (2)

[Claims] 1. A step of applying spread powder or laying a release paper on the surface of a jig of a floor plate or frame body made of a porous material, and a step of setting a laminated body of ceramic green sheets on the jig. And a step of isostatically pressing the laminated body and the jig in a flexible covering bag in a sealed state. 2. The step of vacuum-sealing the laminated body and the jig in a coated bag body, and then isostatically pressing the coated bag body in a sealed state. The method for manufacturing a monolithic ceramic electronic component according to claim 1.