JPS62204513A - Manufacture of wound ceramic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a wound ceramic capacitor.

[Technical background of the invention and its problems 1 As consumer and industrial equipment becomes smaller, lighter, and more electronic, and there is a demand for improved component integration, we have responded to the need for smaller size and larger capacity with a chip structure. Demand for multilayer ceramic capacitors continues to grow rapidly. A conventional method for manufacturing a multilayer ceramic capacitor is to laminate a plurality of dielectric green sheets 12 on which internal electrodes 11 are printed as shown in FIG. 6, and to produce a ceramic laminate 13 constructed as shown in FIG. As shown in the figure, the lower mold 14 and the upper mold 1
9, the ceramic molded body 17 is formed as shown in FIG. After cutting 1,71 and degreasing and firing, external electrodes 19 are formed on both end faces of the unit body 18 formed as shown in FIG. 10 to form a multilayer ceramic capacitor.

However, since the ceramic molded body 17 is formed by thermocompression bonding between the lower mold 14 and the upper mold 15, the pressure distribution during compression is not uniform, and the pressure distribution in the ceramic molded body 17 is Variations were likely to occur.

The variation in pressure distribution causes a difference in the shrinkage rate when the capacitor element 18 formed by cutting the ceramic molded body 17 is fired. The difference in shrinkage rate causes internal stress in the element during firing, causing deformation such as warpage and bending, causing delamination (layer delamination 111 [)]. The air trapped in the 12th hole was forced to escape, further promoting delamination during firing. And delamination is yield? This can be said to be a serious drawback that leads to a decrease in tHQ performance and reliability. However, the above drawback is that the dielectric raw sheet 12
This is more noticeable as the number of laminated layers increases, and J3 limits are naturally imposed on the number of V4 layers that can be applied to the above manufacturing method. was in a situation where it was limited.

Furthermore, as is clear from FIG. 11, the multilayer ceramic compactor made by 1q with the above structure has internal molds J4 on three sides.
Margin part 2 that does not form i11 and does not contribute to capacitor capacity ω
0 exists, and when considering the proportion of the blank space 20 that does not contribute to the capacity, it has become a major bottleneck in miniaturization.

[Object of the Invention] The present invention has been made in view of the above points, and provides a method for manufacturing a wound ceramic capacitor having a novel configuration that has good characteristics, significantly increases capacity, and can be significantly reduced in size. The purpose is to

[Summary of the Invention] The method for manufacturing a rolled ceramic compact of the present invention involves laminating a pair of strip-shaped ceramic dielectric green sheets each having one end in the width direction as a margin and forming an internal electrode, with the margins facing opposite sides. A means for forming a wound body by winding it around a core coated with a release agent, a means for placing the wound body in a water-resistant bag, sucking out the air inside it, vacuum packaging it, and heat-pressing it with a hydrostatic press machine; After said means, said winding core is removed, degreased and fired, and external electrodes are formed on both correspondingly eroded end surfaces.

[Embodiment of the Invention] An embodiment of the present invention will be described in detail below. That is, as shown in FIG. 1, Pb, Ba, Ti, and Fe.

A strong W1-body material with a strong luherovskite crystal structure such as Nb, W, MO, Sr, and Zn is used, and a thermoplastic resin such as acrylic resin or polyvinyl butyral resin is used as a binder, and extrusion method or doctor blade is used. Form it by a method etc., and make one end in the width direction the margin part 1, and make it 1- to A.
Pd, Pd, Pt.

Using a pair of strip-shaped ceramic dielectric sheets 3 on which internal electrodes 2 are formed by printing and applying an electrode paste made of Au, Ni, etc. or by vapor-depositing the electrode material, the dielectric sheets are prepared with the blank portions 1 on opposite sides. 3 pairs are stacked,
Using a winding core 4 whose surface is coated with a release agent such as wax or silicone, the core 4 is wound a necessary number of times to form a winding body 5. Then the second
As shown in the figure, the rolled body 5 is housed in a water-resistant bag 6 made of rubber, resin, etc., and the air inside the water-resistant bag 6 is sucked and packaged under vacuum.
/(g/crj) and heat and press using a hydrostatic press machine 7 set at a time of 5 to 12.0 minutes.Next, the core 4 is extracted from the rolled body 5 taken out from the water-resistant bag 6,
In the degreasing process, the binder is blown off and firing is performed at 950 to 1150°C, and then, as shown in FIG. This is how a ceramic capacitor is obtained. 9 in FIG. 1 is a margin at the end of the winding.

According to the method for manufacturing the wound ceramic capacitor configured as described above, since the hot press bonding is performed using the hydrostatic press machine 7, the pressure distribution is uniform around the entire circumference of the wound body 5 in the direction of the arrow. Unlike the conventional method using a mold press, the cause of delamination can be eliminated, and it not only improves yield but also has excellent effects without deterioration of characteristics. In addition, since it is a hot press bonding process using a hydrostatic press machine 7, it is possible to easily form a wound ceramic capacitor 19, which was not possible with a hot press bonding process using a mold press. Strip-shaped L ramic dielectric sheet 3
Since it is only provided at one end in the width direction of the internal electrode 2, it requires blank areas on three sides of the internal electrode 2 that do not contribute to the capacitance. The size can be significantly reduced. Furthermore, the pressure bonding using the isostatic press machine 7 results in a more uniform pressure distribution around the entire circumference of the wound body 5 compared to that using a mold press, so even if the number of turns is increased, the pressure distribution is uniform, and the This method has many advantages, such as the ability to obtain a ceramic capacitor of high quality that exceeds the limits of GI layer ceramic capacitors obtained by mold pressing.

Next, an example of a comparison between Example A of the present invention having the configuration shown in FIG. 3 and the multilayer ceramic capacitor of Reference Example B shown in FIG. 10 obtained by a conventional manufacturing method will be described.

Example A ■Dielectric material Acrylic resin is added as a binder to the PB composition.

■Sheet formation□Doctor blade method■Seal 1-1 method・All white area dimensions□Thickness 50μm.

Length 150ya, Width 6M, Margin 0.5M (The margin is 15m at the start of winding and 30s+ at the end of winding.) ■ Internal electrode □ AQ-Pd paste printing ■ Hydrostatic press machine conditions □ Temperature 65°C 2 Internal pressure 300
K9/ci, time 10 minutes ■Baking humidity/time□
1050℃ - 4 hours ■ External electrode □ AQ base 1 to Baking reference example B ■ Dielectric material □ Same as Example ■ Sheet formation □ ■ Sheet thickness / Firing simple 8! 1 layer dimensions / Margin sheet thickness Size: 50μm, laminate size: 5.4M x 4.0m x 2m
, 0.4 m each on three sides of the margin ■ Internal electrode □ Same as Example A ■ Mold press machine conditions □ Temperature 65°C, pressure 300 K
'l/cri, time 10 minutes■Baking temperature/time□1
050° C. for 4 hours ■ External electrode □ Same as Example A Note that both A and B have a rating of 50 WV and 1.2 μF. The results of comparing the characteristics and volume of 30 examples of Example A of the present invention and the conventional reference example B were as shown in the table below. The numerical values shown in the table are average values.

Below Margin As is clear from the table above, Example A is slightly superior in each characteristic compared to Reference Example B, and Example A is the reference example. It was demonstrated that a large reduction in size is possible with a capacity ratio of about 1.5 times, and that a large capacity increase is possible with the same volume as Reference Example B.

In the above embodiment, the shape of the wound body 5 was exemplified as a cylindrical shape. 10 shape is also applicable since it results in uniform pressure distribution over the entire periphery by the hot pressing means using the isostatic press machine. Furthermore, when a base metal such as Ni is used for the internal mold, it is natural to perform atmospheric firing.

[Effects of the Invention] According to the present invention, pressure can be uniformly distributed around the entire circumference of the wound body by heat-pressing using an isostatic press machine, which has good characteristics and has high practical value, making it possible to downsize and increase capacity. A method for manufacturing a wound ceramic capacitor can be described (q).

[Brief explanation of drawings]

FIGS. 1 to 3 are for explaining a method of manufacturing a wound ceramic capacitor according to an embodiment of the present invention. FIG. 1 is a partially exploded perspective view of a wound body, and FIG. FIG. 3 is a perspective view showing a wound ceramic capacitor, and FIGS. 4 and 5 show winding cores according to other embodiments of the present invention. The perspective views, FIGS. 6 to 11, are for explaining the manufacturing method of a multilayer ceramic capacitor according to a conventional reference example. FIG. 6 is a perspective view showing a ceramic laminated sheet, and FIG. FIG. 8 is a schematic diagram showing the heat-pressing method using a mold press, FIG. 9 is a perspective view showing a ceramic molded product, FIG. 10 is a perspective view showing a multilayer ceramic capacitor, and FIG. 11 10 is a partially exploded perspective view of the unit before forming external electrodes on the capacitor shown in FIG. 10. FIG. 1... Margin area 2... Internal electrode 3... Band-shaped ceramic dielectric sheet 4...
... Winding core 5 ... Winding body 6 ...
... Waterproof bag 7 ... Hydrostatic press machine 8 ... External electrode 9 ... Margin at end of winding 10 ... Winding core patent applicant Perspective view of wound ceramic capacitor by Marukon Electronics Co., Ltd. Figure 3 Figure 8 Figure 11 Figure 7 Figure 10 Figure 9

Claims (1)

[Claims] means for forming a wound body by stacking a pair of band-shaped raw ceramic dielectric sheets with one end in the width direction as a margin and forming internal electrodes, with the margins facing opposite sides, and winding the sheets around a core coated with a release agent; The wound body is placed in a water-resistant bag, vacuum-packaged by suctioning the air inside, and heat-pressed using a hydrostatic press machine. After the means, the core is removed, degreased and baked, and then both end surfaces are sealed. 1. A method for manufacturing a wound ceramic capacitor, comprising: means for forming an external electrode.