JP3468110B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example relates to a manufacturing method of a multilayer ceramic electronic component, such as a multilayer capacitor,
More particularly, to a method of manufacturing a multilayer ceramic electronic component of the external electrode surface is flattened by devising the shape of the sintered ceramic end face.

[0002]

2. Description of the Related Art In electronic parts such as multilayer capacitors, external electrodes are formed on both ends of an electronic part body. Figure 3
FIG. 7 is a sectional view showing a state in which a conventional multilayer capacitor is mounted on a printed circuit board.

The multilayer capacitor 51 is made of a dielectric ceramic and has a rectangular parallelepiped ceramic sintered body 52. Inside the ceramic sintered body 52, internal electrodes 53 to
56 are arranged so as to overlap with each other through the ceramic layer. The internal electrodes 53, 55 are drawn out to the end surface 52a, and the internal electrodes 54, 56 are drawn out to the end surface 52b. External electrodes 57 and 58 are formed so as to cover the end surfaces 52a and 52b.

The external electrodes 57 and 58 are formed by applying and baking a conductive paste. That is, the external electrode 57 is formed by immersing the ceramic sintered body 52 in the conductive paste from the end face 52a side, applying the conductive paste, drying and baking. The external electrode 58 is also formed by the same method.

In the external electrodes 57 and 58 formed by baking the conductive paste, the thickness becomes thicker at the central portions of the end surfaces 52a and 52b, and the edge portions formed by the end surfaces 52a and 52b and the upper surface 52c and the lower surface 52d, Alternatively, the thickness of the external electrodes 57 and 58 tends to be thin at the edge portions formed by the side surfaces (not shown) and the end surfaces 52a and 52b. That is, as shown by the arrow A in FIG. 3, the thickness of the external electrodes 57 and 58 tends to be thin at the edge portion.

When the thickness of the external electrodes 57, 58 becomes thin near the edges, when a plating layer is formed on the outside of the external electrodes 57, 58 or when the external electrodes 57, 58 are mounted on the printed circuit board 59, the plating solution, the solder flux, etc. are made into ceramics. Sintered body 5
There is a possibility that it will penetrate into the inside of the No. 2 and deteriorate the characteristics.

[0007]

Therefore, conventionally, after the ceramic sintered body 52 is obtained, the edge portion of the ceramic sintered body 52 is rounded by barrel polishing or the like as shown in FIG. The method of increasing the thickness of the external electrodes 57 and 58 at the edge portions is adopted. However, as shown in FIG. 3, even if the edge portion of the ceramic sintered body 52 is rounded by polishing, the thickness of the external electrodes 57 and 58 is still not sufficiently thick at the edge portion. In some cases, the characteristics may be deteriorated due to the penetration of the plating solution, moisture, solder flux, or the like.

In recent years, electronic components such as multilayer capacitors have been further miniaturized. Therefore, the ceramic sintered body 52 is also becoming smaller. As a result, for example, as shown in FIG. 3, when the multilayer capacitors 51 are mounted on the electrode lands 59a and 59b on the printed circuit board 59 by using the solders 60 and 61, one of them is required before the solders 60 and 61 are solidified. Due to the surface tension of the solder 61, the ceramic sintered body 52 sometimes stood up as shown by the arrow B. In particular, when the end surface portion of the ceramic sintered body 52 is rounded as described above,
The above-mentioned rising, that is, a phenomenon called a tombstone phenomenon was likely to occur.

The object of the present invention is to suppress the occurrence of the tombstone phenomenon even when miniaturization is promoted,
When implemented using solder to provide an electrical connection method of reliability may multilayer ceramic electronic component that enhances production for such as a printed circuit board.

[0010]

Means for Solving the Problems] inventions of claim 1
Is a concave surface in which the first and second end faces are dented at the intermediate height position.
It is said that the thickness is inside the ceramic layer.
Multiple internal electrodes are arranged so that
To obtain a ceramic sintered body with rounded edges
And whether the ceramic sintered body is on the side of each of the first and second edges.
Dip it in a conductive paste and pull it up.
First and second flat outer surfaces on the first and second end faces
Forming an external electrode.
Click Ru manufacturing method der of electronic components.

[0011]ContractRequirementTwoAccording to the invention described in 1.
The manufacturing method of electronic partssoIsObtain the above ceramic sintered body
StepOn the other hand, a plurality of internal electrodes are formed on the main surface
Ceramic green sheet and internal electrodes are formed
The process of preparing a plain green ceramic green sheet
And a plurality of ceramic grees on which the internal electrodes are formed.
Above and below the laminated sheet
With the internal electrodes so that the
Green sheet and plain ceramic green sheet
To obtain a laminate and firing the laminate.
And a step of obtaining a ceramic sintered body by
As a ceramic green sheet with internal electrodes
Softer than plain ceramic green sheets.
Using Lamic green sheet and before firing
Further comprises a step of polishing the end faces of the laminated body with an abrasive.
It is characterized by

In the method for manufacturing a monolithic ceramic electronic component according to the third aspect of the present invention, the ceramic sintered body is obtained.
A step of preparing a plurality of ceramic green sheets having internal electrodes formed on one main surface thereof and a plain ceramic green sheet having no internal electrodes formed thereon, and a plurality of ceramics having the internal electrodes formed therein. A step of stacking a ceramic green sheet and an uncoated ceramic green sheet having internal electrodes formed so that the plain ceramic green sheets are located above and below the green sheet stacking portion to obtain a stack, and firing the stack. And a step of obtaining a ceramic sintered body according to claim 1, wherein a ceramic green sheet having a shrinkage rate during firing that is smaller than that of the ceramic green sheet on which the internal electrodes are formed is used as the plain ceramic green sheet. And

According to the fourth aspect of the invention, as the ceramic green sheet on which the internal electrodes are formed, a ceramic green sheet having a higher glass frit content than the plain ceramic green sheet is used.

According to the fifth aspect of the invention, as the ceramic green sheet on which the internal electrodes are formed, a ceramic green sheet having a plasticizer content higher than that of the plain ceramic green sheet is used.

[0015]

1 is a sectional view showing a monolithic capacitor as an embodiment of a monolithic ceramic electronic component according to the present invention.

The multilayer capacitor 1 has a ceramic sintered body 2 made of dielectric ceramics. The ceramic sintered body 2 has a substantially rectangular parallelepiped shape. That is, the ceramic sintered body 2 has an upper surface 2a, a lower surface 2b, a pair of opposing end surfaces 2c and 2d, and a pair of side surfaces (not shown).

Of course, the first and second end faces 2c, 2d
Is a recessed concave surface at the intermediate height position. Further, the end faces 2c, 2d of the ceramic sintered body 2, the upper face 2a, the lower face 2b, and the pair of side faces are rounded. That is, as shown by the arrow A in FIG.
For example, the edge portion formed by the end surface 2c and the upper surface 2a is rounded.

In the ceramic sintered body 2, a plurality of internal electrodes 3 to 6 are arranged so as to overlap each other in the thickness direction with a ceramic layer interposed therebetween. The internal electrodes 3 and 5 have end faces 2c
Is exposed to expose. On the other hand, the internal electrodes 4 and 6 are drawn out so as to be exposed at the second end surface 2d.

To cover the end faces 2c and 2d, respectively,
First and second external electrodes 7 and 8 are formed. The external electrodes 7 and 8 are formed so as to reach not only the end faces 2c and 2d but also the upper face 2a, the lower face 2b, and the pair of side faces of the ceramic sintered body 2.

The external electrodes 7 and 8 are formed by applying a conductive paste and baking after obtaining the ceramic sintered body 2. That is, the ceramic sintered body 2
Is immersed in the conductive paste from the side of the end face 2c and pulled up to adhere the conductive paste so as to cover the end face 2c, and thereafter, the conductive paste is similarly attached to the end face 2d. After that, the external electrodes 7 and 8 are formed by baking a conductive paste.

The characteristic of the multilayer capacitor 1 is that the end faces 2c, 2
d is that it is a concave concave surface at the intermediate height position, whereby the end surfaces 2 of the external electrodes 7 and 8 are formed.
The outer surfaces 7a and 8a of the portions covering c and 2d are made flat. Preferably, the outer surfaces 7 of the outer electrodes 7, 8
a and 8a are made flatter than the end faces 2c and 2d of the ceramic sintered body 2.

That is, when forming the external electrodes 7 and 8, the conductive paste is attached so as to cover the end faces 2c and 2d as described above. In this case, when the end face is flat, when the ceramic sintered body is pulled up from the conductive paste, as in the case of the conventional multilayer capacitor 51 shown in FIG. 3, the thickness of the conductive paste is at the center of the end face. Get thicker.

On the other hand, in this embodiment, the end faces 2c,
Since 2d is a concave surface, the end surface 2
When d or end face 2d is dipped and pulled up, end face 2
The conductive paste adheres thickly at the intermediate height positions of c and 2d, but the outer surface of the conductive paste is flattened by the amount of the concave surface. Therefore, the flatness of the outer surfaces 7a, 8a of the external electrodes 7, 8 is improved after baking.

Therefore, the tombstone phenomenon described above is more likely to occur with the downsizing, but in the multilayer capacitor 1 of this embodiment, the outer surfaces 7a and 8a of the external electrodes 7 and 8 are flattened, so that the tombstone phenomenon occurs. Can be effectively suppressed.

Regarding the degree of the concave surface,
Although it cannot be uniquely determined because it depends on the adhesive force of the conductive paste, it is preferable to effectively suppress the above-mentioned tombstone phenomenon by forming the external electrode 7 in the portion where the internal electrodes 3 to 6 are laminated. , 8 are determined so that the outer surfaces thereof are flat.

The specific degree of the concave shape of the concave surface cannot be uniquely determined because it depends on the size of the ceramic sintered body 2 or the like. When using one having a size of × 0.8 × 0.8 mm or less, the innermost end of the end faces 2c and 2d should be 3 μm or more, more preferably 5 μm or more indented from the outermost end. Is desirable, which allows the outer surfaces 7a, 8a of the external electrodes 7, 8 to be made flatter.

As described above, the method of making the end surfaces 2c, 2d concave by denting at the intermediate height position is not particularly limited, but the following various methods can be exemplified. As a first method, in obtaining the ceramic sintered body 2, plain ceramics which are arranged above and below a portion where the internal electrodes 3 to 6 are laminated as a ceramic green sheet having internal electrodes formed on the upper surface. A method of using a ceramic green sheet that is softer than that of a green sheet and polishing the end faces of the laminate with an abrasive prior to firing. That is, when the laminated body is polished by sandblasting or the like, since the central ceramic green sheet on which the internal electrodes are laminated is relatively soft, the intermediate height position portion of the end face of the laminated body is more than the upper and lower portions. Many are polished. Therefore, after firing, the end faces 2c and 2d can be formed into the concave surfaces.

As described above, various methods can be used for making the ceramic green sheet on which the internal electrodes are laminated softer than the plain ceramic green sheet. For example, a ceramic on which the internal electrodes are formed can be used. Examples include a method of relatively increasing the plasticizer content in the green sheet.

In the second method, the plain ceramic green sheet, which has a smaller shrinkage rate during firing than the ceramic green sheet on which the internal electrodes are formed, is used. In this case, although the end face is flat at the stage of obtaining the laminated body prior to firing, the firing causes the intermediate height position of the end faces 2c and 2d to be dented due to the difference in shrinkage ratio, and the end face 2c , 2d are concave surfaces.

Various methods can be used as the method for making the shrinkage ratio different as described above. For example, a method of increasing the glass frit content rate in the ceramic green sheet in which the internal electrodes are formed to be higher than the glass frit content rate in the plain ceramic green sheet, or the plasticizer content rate in the ceramic green sheet in which the internal electrodes are formed A method of increasing the content of the plasticizer in the plain ceramic green sheet may be used.

As a third method, after obtaining the ceramic sintered body 2, the end faces 2c, 2d of the ceramic sintered body 2 are obtained.
Selectively polish the middle height position part of the end faces 2c, 2d
May be a concave surface. The above-mentioned various methods in which the end surfaces 2c and 2d are concave surfaces may be appropriately used in combination.

Next, a concrete experimental example will be described to clarify the method for manufacturing the above-mentioned multilayer capacitor and concretely explain that the tombstone phenomenon is effectively suppressed.

Ceramic powder containing barium titanate as a main component, polyvinyl butyral binder, organic solvent and dioctyl phthalate as a plasticizer were mixed, and the dioctyl phthalate content was 2.5 parts by weight based on 100 parts by weight of ceramic powder. A first ceramic slurry was obtained.

Next, as in the case of the first ceramic slurry, except that the dioctyl phthalate content is 3.0 parts by weight with respect to 100 parts by weight of the ceramic powder.
The ceramic slurry of was prepared.

Using the above first ceramic slurry, a first ceramic green sheet was formed by the doctor blade method. Similarly, a second ceramic green sheet was formed using the second ceramic slurry.
An internal electrode was formed by screen-printing a conductive paste on the upper surface of the first ceramic green sheet.

Next, each of the first and the first shown in FIGS.
A second ceramic green sheet was laminated and pressed in the thickness direction to obtain a ceramic laminated body. That is, the first ceramic green sheets 11 and 13 printed with the internal electrodes 12 and 14 shown in FIGS. 2B and 2C.
70 sheets are alternately laminated, and the second plain green ceramic green sheets 15 and 16 shown in FIGS.
15 sheets were laminated to obtain a ceramic laminated body.

The first and second end faces (the end faces from which the internal electrodes are drawn out) of the ceramic laminate obtained as described above were ground by the sandblast method. As a result, the first content of dioctyl phthalate as a plasticizer is high.
The intermediate height position portion where the ceramic green sheets of (1) were laminated was shaved more than the upper portion and the lower portion, and the end surface was made a concave surface.

As described above, the ceramic laminate having the concave end surface was fired to obtain the ceramic sintered body 2 shown in FIG. After that, the end surface 2 of the ceramic sintered body 2
The ceramic sintered body 2 was immersed in the conductive paste layer from the c side and pulled up to attach the conductive paste so as to cover the end face 2c. Subsequently, the ceramic sintered body 2 was immersed in the conductive paste layer from the end face 2d side and pulled up to form a conductive paste layer so as to cover the end face 2d.

Thereafter, the conductive paste attached so as to cover the end faces 2c and 2d is baked to form the first and second external electrodes 7 and 8 and the multilayer capacitor 1
Got The external dimensions of the multilayer capacitor 1 are 1.6 × 0.
It is 8 × 0.8 mm.

In obtaining the above multilayer capacitor 1, by changing the grinding conditions by the sandblast method,
As shown in Table 1 below, the amount of dents on the end faces 2c and 2d is 0.
Various laminated capacitors were obtained by changing the thickness to 1 μm, 1 μm, 3 μm and 5 μm. Then, various laminated capacitors thus obtained were mounted on a printed circuit board by a reflow soldering method, and it was confirmed whether or not a tombstone phenomenon occurs. The results are shown in Table 1 below.

The above-mentioned dent amount means the end faces 2c, 2d.
The horizontal distance from the outermost end to the innermost end of the concave portion.

[0042]

[Table 1]

As is clear from Table 1, the end faces 2c, 2d
When the dent amount is 0 μm, that is, on the surface which is not the concave surface, the tombstone phenomenon occurs in 5 laminated capacitors per 1000 laminated capacitors.

On the other hand, when the dent amount is 1 μm or more and the end surfaces 2c and 2d are concave surfaces, the occurrence rate of the tombstone phenomenon can be effectively suppressed, and particularly, the dent amount is 3 μm or more. In this case, the tombstone phenomenon did not occur at all.

Therefore, by making the end surfaces 2c and 2d concave, the outer surfaces 7a and 8a of the external electrodes 7 and 8 formed by applying and baking the conductive paste are flattened,
As a result, it can be seen that the occurrence of the tombstone phenomenon can be effectively suppressed.

In the above embodiments, the multilayer capacitor is described as an example, but the multilayer ceramic electronic component according to the present invention is not limited to the multilayer capacitor, and various types such as a multilayer thermistor, a multilayer varistor, a multilayer piezoelectric ceramic electronic component, etc. It can be applied to multilayer ceramic electronic components in general.
And the external dimensions of the monolithic ceramic electronic component are 1.6 ×
It is more effective when applied to those having a size of 0.8 × 0.8 mm or less.

[0047]

In the method for manufacturing a monolithic ceramic electronic component according to the first aspect of the present invention, the first and second end surfaces of the ceramic sintered body are concave surfaces which are recessed at the intermediate height position. The first and second external electrodes are formed by applying and baking a conductive paste, but the surfaces of the first and second external electrodes are flattened. In addition, the ceramic sintered body
The edges are rounded. Therefore, the tombstone phenomenon when mounted on a printed circuit board or the like by, for example, the reflow soldering method can be effectively suppressed, and the reliability and stability of the mounting work of the laminated ceramic electronic component can be improved.

[0048] Further, first, and second end surfaces is with the concave surface, whereby the outer surface of the outer electrode is flat. Therefore, the tombstone phenomenon at the time of mounting the laminated ceramic electronic component on the printed circuit board can be suppressed, and the reliability and stability of the mounting of the laminated ceramic electronic component can be improved.

In the method for manufacturing a laminated ceramic electronic component according to the second aspect of the present invention, a ceramic green sheet that is softer than a plain ceramic green sheet is used as the ceramic green sheet on which internal electrodes are formed, and the ceramic green sheet is laminated before firing. When the body end surface is polished with an abrasive, the edge of the ceramic green sheet on which the internal electrode is formed is largely polished, whereby the end surface can be made a concave surface. Thus, by firing, first, as possible out to the second end face to reliably obtain a ceramic sintered body which is a recessed concave surface at an intermediate height position.

According to the third aspect of the present invention, since the ceramic green sheet having a shrinkage factor during firing that is smaller than that of the ceramic green sheet on which the internal electrodes are formed is used as the plain ceramic green sheet,
In the ceramic sintered body obtained by firing,
On the second end surface, the intermediate height position portion where the internal electrodes are laminated is dented, and the first and second end surfaces are concave surfaces .

Further, in the invention according to claim 4 , as the ceramic green sheet on which the internal electrodes are formed, the ceramic green sheet having a higher glass frit content ratio than the plain ceramic green sheet is used.
The shrinkage rate of the plain ceramic green sheet during firing is made smaller than the shrinkage rate of the ceramic green sheet on which the internal electrodes are formed. Thus, after firing, the first and second end surfaces is reliably concave surface.

In the invention described in claim 5 , as the ceramic green sheet on which the internal electrodes are formed, a ceramic green sheet having a higher plasticizer content ratio than that of the plain ceramic green sheet is used. When the second end face is polished, the intermediate height position where the internal electrodes are laminated is polished larger than the upper and lower portions, whereby the first and second end faces can be surely made concave. it can. Further, the shrinkage rate of the plain ceramic green sheet during firing is made smaller than the shrinkage rate of the ceramic green sheet on which the internal electrodes are formed. Therefore, after firing, the first and second end faces are surely made concave .

[Brief description of drawings]

FIG. 1 is a sectional view showing a multilayer capacitor according to an embodiment of the present invention.

2A to 2D are plan views for explaining a ceramic green sheet prepared for obtaining the multilayer capacitor of the embodiment and the shape of internal electrodes formed thereon.

FIG. 3 is a vertical cross-sectional view for explaining a tombstone phenomenon when a conventional multilayer capacitor is mounted on a printed circuit board.

[Explanation of symbols]

1. Multilayer capacitor 2 ... Ceramic sintered body 2c, 2d ... First and second end faces 3-6 ... Internal electrodes 7, 8 ... First and second external electrodes 7a, 8a ... Outer surface 11, 13, 15, 16 ... Ceramic green sheet 12, 14 ... Internal electrodes

Claims (5)

(57) [Claims] 1. The first and second end faces are dented at an intermediate height position.
It is a concave surface with a ceramic layer inside.
Multiple internal electrodes are arranged so that they overlap each other in the thickness direction.
The ceramic sintered body is placed and has rounded edges.
And the ceramic sintered body is electrically conductive from the first and second end face sides.
By soaking in the paste and pulling it up,
First and second external electrodes having flat outer surfaces on the end faces of the
Ru and a step of forming a method for manufacturing a multilayer ceramic electronic component. 2. A step of obtaining the ceramic sintered body.
However , a step of preparing a plurality of ceramic green sheets having internal electrodes formed on one main surface and a plain ceramic green sheet having no internal electrodes formed, and a plurality of ceramic green sheets having the internal electrodes formed A step of laminating a ceramic green sheet and internal ceramic green sheets having internal electrodes formed so that the plain ceramic green sheets are located above and below the laminated portion to obtain a laminated body; and by firing the laminated body, ceramic A step of obtaining a sintered body, using a ceramic green sheet softer than a plain ceramic green sheet as the ceramic green sheet on which the internal electrodes are formed, and polishing the end faces of the laminate with an abrasive prior to the firing. The method further comprising the step of : 1. A method for manufacturing a monolithic ceramic electronic component according to 1 . 3. A step of obtaining the ceramic sintered body.
However , a step of preparing a plurality of ceramic green sheets having internal electrodes formed on one main surface and a plain ceramic green sheet having no internal electrodes formed, and a plurality of ceramic green sheets having the internal electrodes formed A step of laminating a ceramic green sheet and internal ceramic green sheets having internal electrodes formed so that the plain ceramic green sheets are located above and below the laminated portion to obtain a laminated body; and by firing the laminated body, ceramic And a step of obtaining a sintered body, characterized in that as the plain ceramic green sheet, a ceramic green sheet having a shrinkage rate during firing smaller than that of a ceramic green sheet on which internal electrodes are formed is used. A method for manufacturing a monolithic ceramic electronic component according to claim 1 . Wherein the ceramic green sheet in which the internal electrodes are formed, characterized by using glass frit content is high ceramic green sheet in comparison with plain ceramic green sheet, according to claim 2 or
4. The method for manufacturing a multilayer ceramic electronic component according to item 3 . 5. The ceramic green sheet having a plasticizer content higher than that of a plain ceramic green sheet is used as the ceramic green sheet on which the internal electrodes are formed, according to claim 2 or 3 . Manufacturing method of multilayer ceramic electronic component.