JPH0997733A - Manufacture of laminated ceramic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hardly generate a delamination between dielectric layers and protective layers by a method wherein green sheets, whose shrinkgage starting temperature due to a firing is lower than that of green sheets for the dielectric layers use, are used as green sheets for the protective layers use. SOLUTION: A plurality of sheets of green sheets, which are respectively formed with an internal electrode pattern 4 consisting of a conductive paste and are ones for dielectric layers 2 use, are laminated on a green sheet in such a way that the patterns 4 oppose to each other holding the green sheets for the layers 2 use between them. Moreover, green sheets for protective layers 6 use are laminated on the upper and lower surfaces of this laminated material by several sheets and a large pressure is applied to the laminated material from the vertical directions to make these green sheets pressure bond. At this time, as the green sheets for the layers 6 use, green sheets, whose shrinkage starting temperature due to a firing is lower than that of the green sheets for the layers 2 use, are used and green sheets having a density higher than that of the green sheets for the layers 2 use are used. Thereby, a difference between the shrinkage behavoirs of the green sheets for the layers 6 use and the green sheets for the layers 2 use at the time of the firing is decreased and as the internal stress of the laminated material is relaxed, the deformation of a product is reduced.

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 monolithic ceramic component, in particular a monolithic ceramic capacitor, in which ceramic layers and conductor layers are alternately laminated and external electrodes are formed at ends thereof.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view of an example of a monolithic ceramic capacitor. As shown in the figure, this monolithic ceramic capacitor has a plurality of dielectric layers 2 which are alternately laminated.
And a pair of protective layers 6 are laminated on the outer sides of the plurality of layers of internal electrodes 4, and the ends of the internal electrodes 4 are alternately connected in parallel by the pair of external electrodes 8, 8.

Here, the dielectric layer 2 and the protective layer 6 are made of a ceramic containing a dielectric material such as barium titanate as a main component, and the internal electrodes 4 are made of a conductive paste containing palladium powder as a main component. It is composed of a conductor film formed in this way. The outer electrode 8 is also made of the same conductor as the inner electrode 4.

Next, an example of a method of manufacturing this conventional monolithic ceramic capacitor will be described.

First, a ceramic raw material powder such as barium titanate, an organic binder, an organic solvent and the like are put in a ball mill together with zirconia balls, and these are crushed and mixed to prepare a slurry. Then, this slurry is applied in a film form on a running polyethylene terephthalate (hereinafter referred to as PET) film by a doctor blade method, and the film form slurry is dried as it is on a PET film to mainly contain barium titanate powder. Obtain a green sheet as an ingredient.

Next, an internal electrode pattern made of a conductive paste is printed on this green sheet by a screen printing method. Then, a plurality of green sheets on which the internal electrode patterns are formed are laminated so that the internal electrode patterns face each other with the green sheets sandwiched therebetween, and further, the internal electrode patterns are formed on the upper and lower surfaces of the laminated green sheets. Stack several unprinted green sheets one by one. Then, a large pressure is applied to the laminated body from above and below under heating so that the respective layers are pressure-bonded.

Next, the laminated body is cut into a lattice shape for each internal electrode pattern to form a laminated body chip, and the laminated body chip is fired at 1200 to 1400.degree. By this firing,
The internal electrode pattern is sintered to become an internal electrode, the green sheet sandwiched between the internal electrodes is sintered to become a dielectric layer, and the outermost green sheet is sintered to become a protective layer.

Next, a conductive paste is baked on both end faces of the fired laminated chip to form a pair of external electrodes. The ends of the internal electrodes are alternately connected in parallel by the pair of external electrodes to complete a monolithic ceramic capacitor.

[0009]

By the way, in the above-described conventional method for manufacturing a monolithic ceramic capacitor, when a laminated chip is fired, the internal electrode pattern contains metal powder as a main component, so that the sintering starting temperature is low. The shrinkage of the dielectric layer starts before the dielectric layer, and the dielectric layer is also affected by the shrinkage of the internal electrode pattern and starts shrinking at a lower temperature than when it exists alone. However, since the protective layer is not provided with the internal electrode pattern, the shrinkage of the internal electrode pattern is less affected. Therefore, in the initial stage of firing, a difference in shrinkage may occur between the protective layer and the dielectric layer, and delamination may occur.

In the latter stage of firing, the shrinkage of the dielectric layer is completed, but the shrinkage of the protective layer continues, and the dielectric layer is dragged by the shrinkage of the protective layer to be further shrunk.
As shown in FIG. 2, the monolithic ceramic capacitor sometimes contracts in the plane direction and expands in the thickness direction, resulting in a product having internal distortion and poor solder heat resistance.

The present invention has been made to solve the above problems, and it is difficult for delamination to occur between an internal ceramic layer such as a dielectric layer and a protective layer, and the product deformation is small. Moreover, it is an object of the present invention to obtain a method for manufacturing a monolithic ceramic component having good soldering heat resistance.

[0012]

In order to achieve the above-mentioned object, a method for manufacturing a laminated ceramic component according to the present invention is such that a green sheet for a protective layer has a shrinkage starting temperature by firing more than a green sheet for an internal ceramic layer. Low green sheet was used. The other steps are the same as in the conventional technique.

If a green sheet having a higher density than that of the green sheet for the internal ceramic layer is used as the green sheet for the protective layer, the shrinkage initiation temperature due to firing can be lowered.

By making the crushing / mixing time of the slurry for forming the green sheet for the protective layer longer than the crushing / mixing time of the slurry for forming the green sheet for the internal ceramic layer, a high density green sheet is obtained. be able to.

Further, the amount of grinding media (crushed stone) used for crushing and mixing the slurry for forming the green sheet for the protective layer is adjusted by crushing the slurry for forming the green sheet for the internal ceramic layer. A green sheet having a high density can be obtained by increasing the amount of the medium used for mixing.

Further, a green sheet having a high density can be obtained by previously compressing the green sheet for the protective layer.

Even if the green sheet for the protective layer contains a sintering aid, the shrinkage initiation temperature by firing can be lowered. As the sintering aid, a liquid phase forming substance that becomes a glass component or a metal oxide can be used.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION First, an organic binder, an organic solvent, etc. are added to a ceramic raw material powder, and these are put in a ball mill together with ceramic balls, ceramic beads, urethane balls, etc., and sufficiently pulverized and mixed to form a slurry. .

Here, for example, barium titanate can be used as the ceramic raw material powder, but other materials may be used depending on the intended product.
As the organic binder, an acrylic ester polymer,
Glycerin, condensed phosphate, etc. can be used.

Next, the slurry prepared as described above is applied in a film form on a running PET film by a doctor blade method, and the film form slurry is dried as it is on the PET film to obtain a green sheet. .

Next, an internal electrode pattern made of a conductive paste is printed on the green sheet by a screen printing method. The conductive paste has an average particle size of 1.
It is possible to use a powder obtained by dispersing palladium powder having a size of about 5 μm and a small amount of ethyl cellulose in butyl carbitol.

Next, a green sheet on which this internal electrode pattern is formed (green sheet for internal ceramic layer)
Are laminated so that the internal electrode patterns face each other with the green sheet for the internal ceramic layer interposed therebetween. Further, several green sheets for the protective layer, on which the internal electrode patterns are not printed, are laminated on the upper and lower surfaces of this laminated body, and a large pressure is applied in the vertical direction to press them together.

As the green sheet for the protective layer,
It is preferable that the shrinkage start temperature by firing is lower than that of the green sheet for the internal ceramic layer. Here, if a green sheet having a higher density than that of the green sheet for the internal ceramic layer is used as the green sheet for the protective layer, the shrinkage initiation temperature due to firing can be lowered.

It is possible to obtain a dense green sheet by making the crushing / mixing time of the slurry for forming the green sheet for the protective layer longer than the crushing / mixing time of the slurry for forming the green sheet for the internal ceramic layer. it can.

Further, the amount of the medium used for pulverizing and mixing the slurry for forming the green sheet for the protective layer is used for pulverizing and mixing the slurry for forming the green sheet for the internal ceramic layer. A green sheet having a high density can be obtained by increasing the amount of the medium.

A high density green sheet can also be obtained by pre-compressing the protective layer green sheet before lamination.

Even if the green sheet for the protective layer contains a sintering aid, the shrinkage initiation temperature by firing can be lowered. As the sintering aid, a liquid phase forming substance or a metal oxide which becomes a glass component can be used.

It goes without saying that a green sheet for a protective layer having a high density may be manufactured by combining these methods.

Next, the laminate formed as described above is cut into a lattice shape for each internal electrode pattern to obtain a laminate chip, and the laminate chip is fired at 1200 to 1400 ° C. By this firing, the internal electrode pattern is sintered to become an internal electrode, the green sheet between the internal electrodes is sintered to become a dielectric layer, and the outermost green sheet is sintered to become a protective layer. .

Next, a conductive paste is applied to both ends of this laminated chip and baked at a temperature of about 550 ° C. to form external electrodes. As a result, the monolithic ceramic capacitor according to the present invention is formed.

It should be noted that instead of forming the external electrodes after firing the laminated chip as described above, the conductive paste is applied to both ends of the laminated chip before firing the laminated chip, The external electrodes may be formed at the same time when the laminated chip is fired. The present invention is not limited to the above-mentioned multilayer ceramic capacitor, but can be applied to a multilayer chip inductor, a multilayer LC component and other multilayer ceramic components.

[0032]

【Example】

Example 1 Ceramic raw material powder containing barium titanate as a main component,
An organic binder and an organic solvent are put in a ball mill together with zirconia balls, and these are crushed and mixed for 24 hours to prepare a slurry, and this slurry is applied in a film form on a running PET film by a doctor blade method and dried. A green sheet for the dielectric layer (internal ceramic layer) was obtained. The density of the green sheet for this dielectric layer was 3.05 g / cm ³ .

Next, the same amount of raw material and zirconia balls as described above were placed in a ball mill and crushed and mixed for 48 hours to obtain a slurry. This slurry was placed on a running PET film. A green sheet for a protective layer was obtained by applying a film by a doctor blade method and drying. The density of the green sheet for this protective layer is 3.
It was 20 g / cm ³ .

Next, an internal electrode pattern is printed on the dielectric layer green sheet, and a plurality of the dielectric layer green sheets are arranged so that the internal electrode patterns face each other with the dielectric layer green sheet interposed therebetween. And a plurality of green sheets for protective layers are laminated on each of the upper and lower surfaces to form a laminated body, and the laminated body is applied with a pressure of 400 kgf / cm ² from below in 100 ° C. Crimped. Density of the green sheet for the dielectric layer of the crimped allowed laminates were 3.60 g / cm ^3, the density of the green sheet for the protective layer had become 3.80 g / cm ^3.

Next, the laminated body is cut into a grid shape for each internal electrode pattern to form a laminated body chip, and the laminated body chip is fired at 1250 ° C., and the end portion of the fired laminated body chip is cut. The conductive paste was baked to form external electrodes, thus completing the laminated ceramic capacitor.

Next, the number of occurrences of delamination and the amount of product deformation of this laminated ceramic capacitor were examined, and a solder heat resistance test was conducted. The results are shown in Table 1.

Here, the delamination is the product 100.
The number of delaminated products is checked by polishing each product, and the product deformation is the difference between the most contracted part L ₁ and the non-contracted part L ₂ in the length of the product in the L dimension direction. In the solder heat resistance test, the number of products with cracks in appearance was examined after immersing the product in molten solder for 3 seconds without preheating.

Example 2 The raw material composition was the same as in Example 1, the amount of zirconia balls was twice the weight of the ceramic raw material powder, and the crushing / mixing time was 24.
A slurry was prepared under the condition of time, and a green sheet for a dielectric layer was prepared using this slurry. The density of the green sheet for this dielectric layer was 3.05 g / cm ³ .

Further, the raw material composition was the same as in Example 1, the amount of zirconia balls was 4 times the weight of the ceramic raw material powder, and the slurry was prepared under the conditions that the crushing and mixing time was 24 hours, and the slurry was used to form the protective layer. I got a green sheet for. The density of the green sheet for this protective layer is 3.15.
It was g / cm ³ .

Next, an internal electrode pattern is printed on the green sheet for the dielectric layer, and the green sheet for the dielectric layer and the green sheet for the protective layer are used to form a laminated body. 400kg from below in ℃
A pressure of f / cm ² was applied for pressure bonding. The density of the green sheet for the dielectric layer of the pressure-bonded laminated body is 3.60.
g / cm ³ , the density of the green sheet for the protective layer is 3.7
It was 0 g / cm ³ .

Next, this laminated body was cut into a laminated body chip, which was fired to prepare a laminated ceramic capacitor.
Similarly to the above, the number of delaminations and the amount of deformation of the product were examined, and a solder heat resistance test was conducted. The results are shown in Table 1.

Example 3 Green sheet for a dielectric layer (density 3.05 g / cm
³ ) was prepared under the same conditions as in Example 1. In addition, some of the green sheets for this dielectric layer are 400
Compressed by applying pressure of kgf / cm ² , density 3.55g
A green sheet for a protective layer of / cm ³ was prepared.

Next, an internal electrode pattern is printed on the green sheet for the dielectric layer, a laminated body is formed using the green sheet for the dielectric layer and the green sheet for the protective layer, and this laminated body is formed into 100 layers. 400kg from below in ℃
A pressure of f / cm ² was applied for pressure bonding. The density of the green sheet for the dielectric layer of the pressure-bonded laminated body is 3.60.
g / cm ³ , the density of the green sheet for the protective layer is 3.7
It was 0 g / cm ³ .

Next, this laminated body was cut into a laminated body chip, which was fired to prepare a laminated ceramic capacitor.
Similarly to the above, the number of delaminations and the amount of deformation of the product were examined, and a solder heat resistance test was conducted. The results are shown in Table 1.

Example 4 Green sheet for a dielectric layer (density 3.05 g / cm
³ ) was prepared under the same conditions as in Example 1. Further, using a slurry obtained by adding 0.5 wt% of a Li-Ca-Si-O-based liquid phase forming substance to the ceramic powder, under the same conditions as when the green sheet for the dielectric layer was prepared,
A green sheet for a protective layer having a density of 3.03 g / cm ³ was prepared.

Next, an internal electrode pattern is printed on the green sheet for the dielectric layer, a laminated body is formed by using the green sheet for the dielectric layer and the green sheet for the protective layer, and the laminated body is formed into 100 layers. 400kg from below in ℃
A pressure of f / cm ² was applied for pressure bonding. The density of the green sheet for the dielectric layer of the laminated body which is pressure-bonded is 3.55.
g / cm ³ , the density of the green sheet for the protective layer is 3.5
It was 0 g / cm ³ .

Next, this laminated body is cut into laminated body chips and fired to produce a laminated ceramic capacitor. The laminated ceramic capacitor is manufactured in the same manner as in Example 1, and the number of delaminations and the product When the amount of deformation was examined and a solder heat resistance test was further conducted, the results are shown in Table 1.

Example 5 Green sheet for a dielectric layer (density 3.05 g / cm
³ ) was prepared under the same conditions as in Example 1. Also, using a slurry in which 0.2 wt% of TiO ₂ was added to the ceramic powder as a sintering aid, the density was 3.05 g under the same conditions as when the green sheet for this dielectric layer was prepared.
A green sheet for a protective layer of / cm ³ was prepared.

Next, an internal electrode pattern is printed on the green sheet for the dielectric layer, a laminated body is formed using the green sheet for the dielectric layer and the green sheet for the protective layer, and this laminated body is formed into 100 layers. 400kg from below in ℃
A pressure of f / cm ² was applied for pressure bonding. The density of the green sheet for the dielectric layer of the laminated body which is pressure-bonded is 3.55.
g / cm ³ , the density of the green sheet for the protective layer is 3.5
It was 0 g / cm ³ .

Next, this laminated body was cut into laminated body chips and fired to form a laminated ceramic capacitor. The laminated ceramic capacitor was processed in the same manner as in Example 1 to find the number of delaminations and the product. When the amount of deformation was examined and a solder heat resistance test was further conducted, the results are shown in Table 1.

Comparative Example 1 A green sheet having a density of 3.05 g / cm ³ was prepared under the same conditions as the preparation of the green sheet for the dielectric layer of Example 1, and this green sheet was used as a green sheet for the dielectric layer. It was used as a green sheet for the protective layer.

Next, an internal electrode pattern is printed on the green sheet for the dielectric layer, and the green sheet for the dielectric layer and the green sheet for the protective layer are used to form a laminated body. A pressure of 400 kgf / cm ² was applied at 0 ° C. to perform pressure bonding. The density of the green sheet for the dielectric layer was 3.60 g / cm ³ , and the density of the green sheet for the protective layer was 3.55 g / cm ³ .

Next, this laminated body was cut into laminated body chips and fired to produce a laminated ceramic capacitor. With respect to this laminated ceramic capacitor, the number of delaminations generated and the product When the amount of deformation was examined and a solder heat resistance test was further conducted, the results are shown in Table 1.

[0054]

[Table 1]

[0055]

According to the present invention, the difference in shrinkage behavior during firing between the green sheet for the dielectric layer and the green sheet for the protective layer becomes small, and the internal stress is relieved.
This has the effects of suppressing the occurrence of delamination, reducing the deformation of the product, and suppressing the generation of cracks due to solder heat.

[Brief description of drawings]

FIG. 1 is a sectional view of a general monolithic ceramic capacitor.

FIG. 2 is a cross-sectional view of a modified monolithic ceramic capacitor.

[Explanation of symbols]

 2 Dielectric layer 4 Internal electrode 6 Protective layer 8 External electrode

Claims (8)

[Claims] 1. A laminate chip in which green sheets for internal ceramic layers and conductive paste films for conductor layers are alternately laminated, and a pair of green sheets for protective layers are laminated as outermost layers. In the method for manufacturing a laminated ceramic component having at least a step of forming and a step of firing the multilayer chip, as a green sheet for the protective layer, a shrinkage start temperature due to the firing is higher than that of the green sheet for the internal ceramic layer. A method for manufacturing a laminated ceramic component, characterized in that a low green sheet is used. 2. A green sheet for the protective layer,
2. A green sheet having a density higher than that of the green sheet for the internal ceramic layer is used.
A method for manufacturing the laminated ceramic component according to. 3. The crushing / mixing time of the slurry for forming the green sheet for the protective layer is longer than the crushing / mixing time of the slurry for forming the green sheet for the internal ceramic layer. A method for manufacturing the laminated ceramic component according to. 4. The amount of grinding media used to grind and mix the slurry to form the green sheet for the protective layer is to grind and mix the slurry to form the green sheet for the inner ceramic layer. The method for producing a laminated ceramic component according to claim 2 or 3, wherein the amount of the medium used is larger than that of the medium. 5. The method for manufacturing a laminated ceramic component according to claim 2, wherein the green sheet for the protective layer is pre-compressed. 6. The method for producing a laminated ceramic component according to claim 1, wherein the green sheet for the protective layer contains a sintering aid. 7. The method for producing a laminated ceramic component according to claim 6, wherein the sintering aid is a liquid phase forming substance that becomes a glass component. 8. The method for manufacturing a monolithic ceramic component according to claim 6, wherein the sintering aid is a metal oxide.