JPH05283277A - Manufacture of laminated ceramic electronic component - Google Patents

Abstract

PURPOSE:To enhance the substrate mounting property of the title electronic component by a method wherein a pressure strain is reduced in a compression molding operation and the difference in a thickness between the lamination central part of an electrode layer and the lamination end part of the electrode layer is reduced even when the number of laminated layers is large. CONSTITUTION:A laminated green body 12 composed of a plurality of ceramic green sheets in which electrode layers have been formed on the individual sheets is laminated and bonded temporarily on the surface of a rigid carrier plate 10 and the laminated green body which has been bonded temporarily is put into a flexible bag 18 together with the carrier plate and vacuum-packed. Regarding the manufacturing method, of a laminated ceramic electronic component, wherein the packed laminated green body provided with the carrier plate is hydrostatically pressed, a process wherein a rigid plate 16 having an area covering at least the electrode lamination part of the laminated green body is placed on the top surface of the laminated green body 12 is provided between a temporary bonding process and a vacuum-packing process, and the rigid plate 16 is vacuum-packed in a state that it has been placed on the surface of the laminated green body 12.

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 laminated ceramic electronic component such as a laminated ceramic capacitor, a multilayer printed wiring board, a laminated varistor, a laminated piezoelectric element and a laminated chip inductor. More specifically, the present invention relates to a method for manufacturing a laminated ceramic electronic component by laminating and pressing a plurality of ceramic green sheets each having electrodes printed thereon and then firing the laminated ceramic green sheets.

[0002]

2. Description of the Related Art Conventionally, as a method of integrating a laminated green body obtained by laminating a plurality of ceramic green sheets of this type, a laminated green body having an electrode layer formed therein is put in a lower mold of a mold and then the There is known a mechanical pressing method in which each green sheet forming a laminated green body and an internal electrode layer are pressure-bonded to each other by pressing a mold without a gap. Generally, the sheet thickness of the electrode forming portion of the ceramic green sheet is larger than the sheet thickness of the electrode non-forming portion, but when pressed by this mechanical pressing method, pressure is mainly applied to the laminating portion of the electrode forming portion. There is an advantage that the difference in thickness between the electrode and the portion where the electrode is not formed is laminated. However, in this mechanical pressing method, the work is complicated and inefficient, and when pressure is applied by this method, pressure is not uniformly applied to the laminated green body, and pressure strain easily occurs in the laminated green body.
As a result, when this laminated green body is fired, it tends to cause delamination (layer peeling) and cracks inside. Further, in the mechanical press, it is difficult to accurately maintain the parallelism and the position of the upper mold and the lower mold, and when the green sheet becomes thin, delamination and the like are more likely to occur due to pressure distortion. As a method for eliminating the above-mentioned pressure distortion, there has been proposed a method in which a ceramic green sheet is vacuum-packaged in a flexible bag and then the vacuum-packaged laminated green sheet is subjected to hydrostatic pressing to be pressure bonded (Japanese Patent Publication No. 58524).

[0003]

However, in the hydrostatic pressing method, pressure is uniformly applied to the laminated portions of the electrode forming portion and the electrode non-forming portion of the laminated green body, so that as shown in FIG. For example, in the case of the chip type monolithic ceramic capacitor 1, the laminated central portion A of the electrode layer 11 and the electrode layer 11
There is a thickness difference d between the laminated end portion B and the laminated end portion B. The thickness difference d becomes more remarkable as the number of stacked layers increases. If this thickness difference is larger than the layer thickness of the external electrode 2, even if the external electrode 2 is provided at the laminated end portion B of the electrode layer 11, the laminated central portion A of the electrode layer 11 protrudes outward from the external electrode 2 in the laminating direction. become. When such a capacitor 1 is mounted on the printed circuit board 3, the external electrode 2 does not come into contact with the substrate 3, so that the capacitor 1 has poor stability and is likely to be displaced. In particular, when the external electrode 2 of the capacitor 1 is soldered to the substrate 3 by using an automatic soldering device, there are problems that the contact between the cream solder 4 and the external electrode 2 becomes poor and that mounting failure easily occurs.

An object of the present invention is to provide a monolithic ceramic electronic component which has a small pressure strain, and has a small thickness difference between the central portion of the electrode layer and the laminated end portion of the electrode layer even when the number of laminated layers is large, and which is excellent in board mountability. It is to provide a manufacturing method of.

[0005]

According to the present invention, as shown in FIGS. 1 to 5, a laminated green body 12 comprising a plurality of ceramic green sheets each having an electrode layer 11 formed on each sheet.
Is laminated on the surface of the rigid carrier plate 10 and temporarily adhered thereto, and the laminated green body 12 temporarily adhered to the carrier plate 10 is put in a flexible bag 18 together with the carrier plate 10 and vacuum-packaged. And a step of isostatically pressing the packaged laminated green body 12 with a carrier plate, which is an improvement of the method for producing a laminated ceramic electronic component. The characteristic configuration is that at least the laminated green body 12 is provided on the upper surface of the laminated green body 12 between the temporary bonding step and the vacuum packaging step.
The step of placing the rigid plate 16 having an area that covers the electrode laminated portion is to vacuum-pack the rigid plate 16 on the upper surface of the laminated green body 12 in the vacuum packaging step. The rigid plate 16 is preferably a metal plate or a heat-resistant plastic plate because it may be subjected to pressure in a heated fluid.

[0006]

The laminated green body 12 is sandwiched between the rigid carrier plate 10 and the rigid plate 16 by vacuum packaging with the rigid plate 16 placed on the upper surface of the laminated green body 12. When the hydrostatic pressing is performed in this state, the laminated green body 12 is laminated. The green body 12 is compressed by the rigid carrier plate 10 and the rigid plate 16. Figure 6
As shown in FIG.
Since the laminated end B of the electrode layer 11 is prevented from being extremely smaller in thickness than the laminated central portion A of the electrode layer 11, the thickness difference D between the both after forming the external electrode 2 is shown in FIG. And the pressure strain is reduced.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. In this example, a monolithic ceramic capacitor will be described as a representative. <Temporary Adhesion Step> As shown in FIG.
Laminated green body 12 having electrode layer 11 inside thereof on the surface of
Is temporarily bonded. Specifically, a base film 14 made of polyethylene terephthalate and having a thickness of about 250 μm, which is coated with an adhesive on one side, is attached to the surface of the carrier plate 10 with this adhesive (not shown). The base film 14 may be another plastic sheet. The adhesive is selected to have such an adhesive force that the base film 14 can be peeled off from the carrier plate when the base film 14 is lightly pulled up by hand. Ethyl cellulose is applied to the surface of the film 14 to form a thin resin layer (not shown). This resin layer exhibits an adhesive force when a ceramic green sheet forming the laminated green body 12 is hot pressed. The resin layer is not limited to ethyl cellulose and may be any resin having an equivalent adhesive effect. In this example, the carrier plate 10 is an aluminum plate having a thickness of about 1 mm, the surface of which is anodized. The material is not limited to the aluminum plate and may be, for example, a stainless steel plate as long as the material does not deform or shrink at high temperature and high pressure.

The laminated green body 12 is a rigid carrier plate 10.
It is made by fixing a plurality of ceramic green sheets one by one on the film 14 on the surface of the sheet by hot pressing. In this example, the green sheet is formed by film-forming and drying a barium titanate-based dielectric slurry having JIS-R characteristics containing a polyvinyl butyral or acrylic binder and a plasticizer by a doctor blade method. After stacking a predetermined number of green sheets, the internal electrode layer 11 is
It is formed by printing a conductive paste for an electrode layer on the upper surface and drying it. After that, stacking of a predetermined number of green sheets without forming the electrode layer and formation of the electrode layer are repeated. In this example, the conductive paste is prepared by mixing Pd powder with a vehicle based on ethyl cellulose. Ag / Pd, Ni, Cu or the like may be used instead of Pd.

<Step of Mounting Rigid Plate> A characteristic point of this embodiment is that after the predetermined number of electrode layers 11 are formed, the rigid plate 16 is mounted on the surface of the uppermost green sheet, that is, the upper surface of the laminated green body 12. Especially. In this example, the rigid plate 16
Is a stainless steel plate having a thickness of about 1 mm. The material is not limited to the stainless steel plate, and may be, for example, an aluminum plate or a heat-resistant plastic plate as long as the material does not deform or shrink at high temperature and high pressure. This rigid plate 16 is shown in FIG.
As will be described in detail below, the area is slightly smaller than the outer circumference of the laminated green body 12 and has an area that covers the laminated portion of at least 24 electrode layers 11. Although not shown, the rigid plate 16 may have the same area as the upper surface of the laminated green body 2.

<Packaging Process> As shown in FIG. 3, the laminated green body 12 temporarily bonded in the temporary bonding process is the carrier plate 10.
It is vacuum-packaged with a flexible bag 18 in a state of being sandwiched between the rigid plate 16 and the rigid plate 16. In this example, the bag 18 is made of nylon. The material is not limited to nylon as long as it can be vacuum-depressurized and sealed, and a flexible material such as rubber or other plastic may be used. It is preferable to seal in a vacuum in order to remove the residual solvent gas in the laminated green body.

<Pressing Step> As shown in FIG. 4, the working fluid 22 of the pressing machine 20 is stored in a tray 21 in a state where a plurality of laminated green bodies 12 sandwiched between a carrier plate 12 and a rigid plate 16 and vacuum-packaged are accommodated in a tray 21. insert. 300 kg here
Laminated green body 12 by applying a pressure of / cm ²
Is hydrostatically pressed. As a result, the plurality of laminated green bodies 12 are collectively pressure-treated. Silicone oil or water is used as the working fluid 22. In order to enhance the pressure-bonding effect, it is preferable to raise the temperature of the working fluid to about 65 ° C. The temperature of the working fluid is raised by intermittently injecting the working fluid stored in a heating tank (not shown) from the heating tank.

<Cutting Step> As shown in FIG. 5, the isostatically pressed laminated green body 12 is taken out by opening the flexible bag 18. After removing the rigid plate 16, the laminated green body 12 with a carrier plate is set on the base of a cutting machine (not shown). Here, when the vertical direction and the horizontal direction of the carrier plate 10 are respectively defined as the x direction and the y direction (see FIG. 2), the laminated green body 12 is cut in the x direction and the y direction while leaving the carrier plate 10. Specifically, a blade of a cutting machine (not shown)
Is stopped when it reaches the inside of the base film 14 as shown by the broken line C in FIG.

<Peeling Step> When the base film 14 is peeled from the carrier plate 10 after the laminated green body 12 is cut, the film 14 is curved, and at the same time, the laminated green body 12 cut into chips is formed. Easy to peel off. The remaining carrier plate 10 is repeatedly used for the temporary adhesion of the next laminated green body.

<Firing Step> The chip-shaped laminated green body is subjected to binder removal processing, and then at 1300 ° C. under atmospheric pressure.
And hold for 2 hours to obtain a chip type monolithic ceramic capacitor element body. The appearance inspection and internal analysis were carried out on each of the 20 chip-type monolithic ceramic capacitor bodies, and no defects such as delamination and cracks were found. As shown in FIG. 6, the difference D in thickness between the both ends of the capacitor body, that is, the laminated end B of the electrode layer 11 and the laminated central portion A of the electrode layer 11 is larger than that of the conventional one in which no rigid plate is mounted. When the external electrode 2 is formed on the laminated end portion B of the electrode layer 11 and mounted on the substrate 3, the surface of the external electrode 2 and the surface of the laminated central portion A of the electrode layer 11 become almost the same, and The ceramic capacitor 1 could be stably placed on the surface of the substrate 3.

In the examples, as the dielectric slurry,
Although the barium titanate-based material having JIS-R characteristics has been described, other dielectric slurry such as lead-based material may be used. Further, although the multilayer ceramic capacitor has been described, the present invention is not limited to this, and can be applied to the production of multilayer ceramic electronic components such as a multilayer printed wiring board, a multilayer varistor, a multilayer piezoelectric element, and a multilayer chip inductor.

[0016]

As described above, since the present invention is based on the hydrostatic pressing method, pressure is evenly applied to the laminated green body to reduce the pressure strain, and after the firing, which occurs in the conventional mechanical pressing method. Defects such as delamination and cracks are eliminated. Further, compared to the conventional hydrostatic pressing method, the laminated green body is held between the rigid carrier plate and the rigid plate during compression molding, and the rigid plate suppresses the reduction in the thickness of the laminated end portion of the electrode layer due to the hydrostatic pressure. Therefore, it is possible to reduce the difference in thickness between the laminated center portion of the electrode layer and the laminated end portion of the electrode layer.
As a result, if external electrodes are formed on both ends of the chip-shaped ceramic body, that is, on the laminated ends of the electrode layers, the central portion of the laminated layers of the electrode layers will be flush with the external electrodes, and the mountability on the substrate will be improved. Will increase. Furthermore, since the rigid plate also has an effect of suppressing the lateral contraction of the laminated green body, the variation in the lateral dimension of the laminated green body after pressing is reduced, and the initial positional accuracy when the electrode layer is formed remains unchanged. It is possible to maintain and improve the product yield of the monolithic ceramic electronic component.

[Brief description of drawings]

FIG. 1E of FIG. 2 showing a state in which a laminated green body according to an embodiment of the present invention is temporarily attached to the surface of a rigid carrier plate and then a rigid plate is placed thereon.
-E line sectional drawing.

FIG. 2 is a plan view of FIG.

FIG. 3 is a cross-sectional view showing a state in which a laminated green body is vacuum-packaged in a flexible bag while being sandwiched between a carrier plate and a rigid plate.

FIG. 4 is a cross-sectional view of a main part of the hydrostatic pressing machine for the laminated green body.

FIG. 5 is a cross-sectional view of a laminated green body with a carrier plate that is hydrostatically pressed.

FIG. 6 is a cross-sectional view showing a state in which the monolithic ceramic capacitor of the example is mounted on a substrate.

FIG. 7 is a sectional view showing a state in which a conventional laminated ceramic capacitor is mounted on a substrate.

[Explanation of symbols]

 10 Rigid carrier plate 11 Electrode layer 12 Laminated green body 16 Rigid plate 18 Flexible bag

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01G 4/30 Z 8019-5E

Claims (3)

[Claims] 1. A laminated green body (1) comprising a plurality of ceramic green sheets each having an electrode layer (11) formed on each sheet.
2) is laminated on the surface of the rigid carrier plate (10) and is temporarily bonded, and the laminated green body (12) is temporarily bonded to the carrier plate (10).
And packaged in a flexible bag (18) together with the carrier plate (10) and vacuum-packed, and the vacuum-packaged laminated green body (12) with carrier plate
In the method for producing a laminated ceramic electronic component comprising a step of isostatic pressing, at least the laminated green body (1) on the upper surface of the laminated green body (12) between the temporary bonding step and the vacuum packaging step.
2) a step of placing a rigid plate (16) having an area covering the electrode laminated portion, and vacuum packaging with the rigid plate (16) placed on the upper surface of the laminated green body (12) in the vacuum packaging step. A method of manufacturing a monolithic ceramic electronic component, comprising: 2. The method for manufacturing a monolithic ceramic electronic component according to claim 1, wherein the rigid plate (16) is a metal plate. 3. The method for producing a laminated ceramic electronic component according to claim 1, wherein the rigid plate (16) is a heat-resistant plastic plate.