JPH07120602B2 - Manufacturing method of multilayer capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a multilayer capacitor, and more particularly, an improved step of forming a side margin region between an internal electrode and a side surface of a dielectric. And a method for manufacturing a multilayer capacitor.

[Conventional technology]

Multilayer capacitors are widely used in order to achieve miniaturization and large capacity of capacitors. The multilayer capacitor has an internal electrode material as shown in FIGS. 2 (a) and (b), for example.
Ceramic green sheets 3 and 4 coated with 1 and 2 were prepared, and a plurality of them were alternately laminated, and further, ceramic green sheets to which the internal electrode material was not coated were laminated on top and bottom as needed. The laminate is pressure-bonded in the thickness direction and then fired to form external electrodes on the end faces of the sintered body from which the internal electrode materials 1 and 2 are drawn out.

By the way, the internal electrode materials 1 and 2 formed on the ceramic green sheets 3 and 4 are
It is provided by a printing method or the like so as to extend from the first end edges 3a, 4a of the third and fourth parts toward the second end edges 3b, 4b. Also,
The internal electrode materials 1 and 2 are provided in such a width that a side margin region 5 of width x is left between the side edges 3c, 3d, 4c and 4d of the ceramic green sheets 3 and 4.

The side margin region 5 is provided for the internal electrode material 1,
This is to improve the adhesion between the ceramic green sheets located above and below 2 and to prevent the internal electrode materials 1 and 2 from being exposed on the side surface of the sintered body after sintering.

[Technical problem to be solved by the invention]

However, when the width x of the side margin region 5 is wide, the widths of the internal electrode materials 1 and 2 are naturally narrowed, which hinders an increase in capacity. Therefore, it is preferable that the width of the side margin region 5 is narrow in order to achieve further miniaturization and large capacity.

On the other hand, in mass production of multilayer capacitors, Fig. 3 (a)
And, as shown in (b), after preparing relatively large mother ceramic green sheets 6 and 7, and alternately laminating a plurality of mother inner electrode materials 8 and 9 formed on one main surface thereof, By cutting the laminated body at the portion along the dashed-dotted lines A and B, individual laminated dielectric raw chips are obtained, and by firing the individual laminated dielectric raw chips, sintering for individual laminated capacitors is performed. I have a body.

However, when printing a plurality of mother internal electrode materials 8 and 9,
Print displacement is unavoidable due to the temporal deformation of the printing screen. In addition, when the mother ceramic green sheets 6 and 7 on which the mother internal electrode materials 8 and 9 are formed are laminated, some stacking deviation must occur. As a result, in each dielectric raw chip after cutting, the internal electrode material may be exposed on the side surface of the dielectric raw chip. If the internal electrode material is exposed on the side surface of the dielectric raw chip, the obtained sintered body may have a poor withstand voltage or a short circuit between the internal electrodes.

Further, when the ceramic green sheets are misaligned as described above, the overlapping area of the internal electrodes is also reduced, and the obtained capacitance may be lower than the designed capacitance.

Furthermore, when the internal electrode reaches the vicinity of the side surface of the sintered body even before it is not exposed, that is, in FIG.
If the side margin region 5 of (b) is narrow, this also causes a breakdown voltage failure or insufficient adhesion strength between the upper and lower ceramic layers, resulting in layer peeling after sintering.

As shown in FIG. 4 in a sectional view taken along line IV-IV in FIG. 2A, when the internal electrode material 1 having a width narrower than that of the ceramic green sheet 3 is printed, the internal electrode material 1 In the side edge portions 1a, 1a, the thickness of the internal electrode material 1 tends to be thicker than other portions. As a result, there is also a problem that layer peeling easily occurs between the ceramic layers at the side edge portions of the internal electrodes after lamination and sintering.

For various reasons as described above, the side margin region 5
Although it is preferable that the width x is narrow, in the conventional method for manufacturing a multilayer capacitor, the width x needs to be increased more than necessary. Therefore, it has been an obstacle to miniaturization and large capacity. In addition, variations in capacity and layer peeling due to stacking deviation cannot be ignored.

Therefore, the object of the present invention is to achieve further miniaturization and large capacity as compared with the conventional multilayer capacitor, less variation in the capacitance value, and inexpensive that can be manufactured by a relatively simple process. Another object of the present invention is to provide a method of manufacturing a multilayer capacitor.

[Means for solving technical problems]

According to the present invention, a plurality of dielectric ceramic layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is narrower than that of the dielectric ceramic layer, whereby the side electrodes are laterally disposed on the side of the internal electrode. A method of manufacturing a multilayer capacitor provided with a margin region, characterized by comprising at least the following steps.

That is, a first internal electrode material made of a material that is difficult to etch is provided near the one edge along one edge, and the one end on the upper surface side or the lower surface side of the first internal electrode material. A plurality of ceramic green sheets having on one main surface a second internal electrode material made of an easily-etchable material that is provided over the entire width so as to extend from the edge to the other edge side facing the one edge, A step of obtaining a laminated-type dielectric raw chip in which the one edge on the side to which the first internal electrode material is applied is alternately located on the opposite end face in the thickness direction; The dielectric green chip is fired to sinter the ceramic green sheet, and the first and second inner electrode materials are fired to form a plurality of inner electrodes each having a first and a second inner electrode portion. Process and above sintering By etching with a chemical that selectively etches the second internal electrode portion to remove at least a portion of the second internal electrode portion exposed on the side surface of the sintered body and the vicinity thereof, thereby forming a side margin region. And a step of forming external electrodes on the facing end faces of the sintered body where the first internal electrode portions are exposed, and a method for manufacturing a multilayer capacitor.

[Action]

In the manufacturing method of the present invention, since the side margin region is formed by etching after obtaining the laminated type sintered body,
The width of the side margin region can be accurately formed by controlling the etching state. Therefore, it is possible to accurately control the overlapping area of the internal electrodes and to reduce the capacitance variation.

Further, since the internal electrodes having the same width as the dielectric ceramic layer are interposed between the dielectric ceramic layers, it is not necessary to unnecessarily widen the width of the side margin region in consideration of stacking deviation when stacking prior to sintering. Therefore, it is possible to obtain a multilayer capacitor having a smaller size and a larger capacity.

Moreover, since the tolerance for the above-mentioned stacking deviation is large,
The laminating work prior to sintering can be easily performed.

The second internal electrode material is applied to the upper surface side or the lower surface side of the first internal electrode material. That is, since it is formed so as to be laminated with the first internal electrode and is applied so as to cover the entire width of the ceramic green sheet, it is not necessary to pay attention to the positioning when applying.

Furthermore, since the first internal electrode portion is made of a material that is difficult to etch, only the portion of the second internal electrode portion exposed on the side surface of the sintered body is immersed in the etching agent. Can be reliably and easily etched.

[Explanation of Examples]

Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 5 (a) and 5 (b) are plan views for explaining the printed shapes of the mother ceramic green sheet used in the manufacturing method of this embodiment and the mother internal electrode material formed on the upper surface thereof.

First, a rectangular mother ceramic green sheet 11 is prepared. The mother ceramic green sheet 11 is obtained by molding a ceramic slurry mainly composed of a dielectric material by, for example, the doctor blade method.

An internal electrode material 13 made of an easily-etchable material is printed on the entire upper surface of the mother ceramic green sheet 11. Since the printing of the internal electrode material 13 may be performed on the entire surface, it can be performed without complicated positioning work or the like.

Next, as shown in FIG. 5 (b), internal electrode materials 12a and 12b made of a material which is difficult to etch are printed in parallel at predetermined intervals as shown.

Each of the internal electrode materials 12a, 12b and 13 is composed of a conductive paste obtained by kneading a conductive material with an organic binder. As the conductive material, various metallic materials such as Ni, Cu, Ag or Ag-Pd can be used.

The internal electrode materials 12a and 12b described above constitute the first internal electrode material of the present invention, and the internal electrode material 13 printed on the entire surface constitutes the second internal electrode material of the present invention. To do. The first internal electrode materials 12a and 12b are made of a material that is difficult to be etched by an etching agent used in an etching process described later. On the other hand, the second internal electrode material 13 is
It is made of a material that is easily etched by an etching agent.

Next, the ceramic green sheet shown in FIG. 5 (b)
Prepare a plurality of 11 and stack them in a state of being alternately inverted 180 degrees. This will be described with reference to FIG. The sixth
In the figure, the inverted ceramic green sheets are denoted by different reference numerals for ease of explanation. That is, the mother ceramic green sheet 14 arranged below the mother ceramic green sheet 11.
The second internal electrode material 16 is printed on the entire surface,
Two first internal electrode materials 15a and 15b are printed in parallel on the upper surface in a strip shape.

By alternately laminating a plurality of mother ceramic green sheets 11 and 14 as described above and cutting at the portions corresponding to the portions along the dashed-dotted lines A and B in FIG. 6, the laminated dielectric shown in FIG. A somatic chip 17 can be obtained.

In the dielectric raw chip 17, a ceramic green sheet 18 to which an internal electrode material is not applied is laminated on the uppermost part. In addition, for easy understanding, the dielectric raw chip 17
The internal electrode materials therein will be described with the same reference numerals as the internal electrode materials shown in FIG.

The first inner electrode material 12a is exposed on the first end surface 17a, and the first inner electrode material 15a is exposed on the second end surface 17b. Also, since the second internal electrode materials 13, 16 have the same width as the ceramic green sheet layer, the first and second end surfaces 17a, 17b
Not only is it exposed on both side surfaces 17c and 17d of the dielectric raw chip 17.

As described above, the dielectric raw chip 17 is obtained by stacking a plurality of ceramic green sheets 11 and 14 shown in FIG. 6 and cutting the green green sheets 11 and 14 at a portion corresponding to the one-dot chain lines A and B. In the case of the conventional example shown in FIG. 3, it was necessary to cut the laminated body in consideration of the width x of the side margin region 5 in advance. The raw chip 17 can be obtained extremely easily and stably.

The mother ceramic green sheets 11,1 shown in FIG.
It is not always necessary to manufacture a large number of dielectric raw chips 17 at a time by using 4. Ie individual dielectric raw chips
Even if the dielectric raw chip 17 is prepared by laminating a rectangular ceramic green sheet of a size required for laminating 17 on which each internal electrode material having the same width as the ceramic green sheet is printed is laminated. Good.

Next, the dielectric raw chip 17 is pressed in the thickness direction. This pressing is performed prior to sintering in order to increase the density of the dielectric raw chips 17 and increase the adhesion between the ceramic green sheets.

In the conventional method described with reference to FIG. 2, the internal electrode materials 1 and 2 are printed in a smaller area than the ceramic green sheets 3 and 4 during the press prior to this sintering. The press pressures tended to vary in three types of regions, that is, two overlapping regions, a region where only the internal electrode materials 1 and 2 exist, and a region where the internal electrode materials 1 and 2 do not exist at all. That is, a high pressing pressure is applied only to the area where the internal electrode materials 1 and 2 are overlapped with each other, and sufficient pressing pressure is not applied to other areas, which causes layer peeling after sintering.

On the other hand, in the manufacturing method of the present embodiment, as shown in FIGS. 7 and 8 (a) and (b), the dielectric raw chip 17 is used.
In the entire area when viewed from above, the internal electrode materials 13, 16,
12a and 15a overlap. Therefore, since the entire region is pressed by a sufficiently large pressing pressure, it is possible to obtain a dense sintered body in which layer peeling is less likely to occur during firing to be described later.

Further, as shown in FIG. 4, in the conventional manufacturing method, the side edge portions 1a and 1b of the internal electrode material 1 tend to be thicker than the other portions, so that a plurality of ceramic green sheets are laminated. In that case, since the thickness of the internal electrode material was not uniform in the width direction, layer peeling easily occurred after sintering.

On the other hand, in this embodiment, as shown in the cross-sectional view of FIG. 9, the second internal electrode material 13 is formed to have the full width of the ceramic green sheet 11 '. The material 13 has a uniform thickness in the width direction. Therefore, it is possible to effectively prevent the occurrence of delamination due to the nonuniformity of the thickness of the internal electrode material in the width direction. The ceramic green sheet 11 'is shown by extracting one layer of the ceramic green sheet layer in the raw chip 17.

Next, the pressed dielectric green chip 17 is fired to integrally fire the internal electrode material and the ceramic green sheet. In addition, in the following description, each internal electrode portion baked by firing is described with the same reference numeral as each internal electrode material described above.

As shown in FIG. 10, in the obtained sintered body 20, a plurality of internal electrodes 21, 22 are arranged so as to overlap each other with a dielectric ceramic layer interposed therebetween in the thickness direction. In the internal electrode 21, the first internal electrode portion 12a is exposed on the first end face 20a, and in the internal electrode 22, the first internal electrode portion 15a.
a is exposed on the second end face 20b.

On the other hand, the second inner electrode portions 13 and 16 of the inner electrodes 21 and 22 are
It is exposed to the first and second end faces 20a and 20b and both side faces 20c and 20d.

That is, in the thickness direction of the sintered body 20, the plurality of internal electrodes 21 and 22 are arranged so that the first internal electrode portions 12a and 15a are alternately exposed to the first and second end surfaces 20a and 20b. Has been done.

Next, the sintered body 20 is immersed in a chemical that selectively etches the second internal electrode portions 13 and 16, and etching is performed. The state after etching is shown in a perspective view in FIG. 11 and a plan view in FIG.

As is clear from FIG. 1, the portions of the second internal electrode portion 13 exposed on the end faces 20a, 20b and the side faces 20c, 20d of the second internal electrode portion 13 and the vicinity thereof are removed. That is, by this etching, the tip margin region 25 is formed between the side margin regions 23 and 24 and the end face 20b on the side of the second internal electrode portion 13. In this case, the first internal electrode portion 12a is not etched by etching.

That is, a chemical that selectively etches only the second internal electrode portions 13 and 16 is used during the etching.

In FIG. 1, only the portion where the internal electrode 21 is formed is shown, but in the portion where the internal electrode 22 is formed, the side margin region and the tip margin region between the end face 20a are similarly formed. It

Each side margin area 23, 24 and tip margin area 2
The width of 5 can be accurately controlled by adjusting the etching conditions, that is, the type and concentration of the agent, the etching time, and the like. Therefore, the overlapping area of the internal electrodes can be set accurately.

In addition, since the side margin regions 23 and 24 can be formed regardless of the lamination process up to sintering, etc., the side margin having a width sufficient and sufficient to prevent short circuit between internal electrodes in the completed multilayer capacitor. The regions 23 and 24 may be formed. That is, a side margin region having a narrower width than that of the conventional method can be formed, so that a small-sized and large-capacity multilayer capacitor can be realized.

Next, the first and second end faces 20a, 20 of the sintered body 20 shown in FIG.
On b, as shown in FIG. 12, a pair of external electrodes 26, 27 are formed. The external electrodes 26, 27 can be formed by applying and baking a conductive paste, but other conductive film forming methods such as plating and sputtering may be appropriately used.

Note that, as shown in FIG. 13 in a sectional view taken along line XIII-XIII in FIG. 11, after the etching, the side margin region
A void 28 is formed along with the formation of 23, 24 and the tip margin region. If the gap 28 has a size that cannot be ignored, a sealing material 29 may be filled as shown in FIG. As the sealing material 29, it is preferable to use a synthetic resin having excellent insulation and moisture resistance.

Further, it is preferable that the sealing material 29 is filled in the state shown in FIG. By filling the sealing material 29 before the formation of the external electrodes 26, 27, the sealing material can also be filled in the tip margin region, so that the internal electrode 21 or 22 and the other internal electrode 22 can be filled.
Alternatively, it is possible to reliably prevent a short circuit with an external electrode connected to 21.

FIGS. 15 (a) and 15 (b) are plan views for explaining a ceramic green sheet that can be used in another embodiment of the present invention and an applied shape of the external electrode paste formed thereon.

As shown in FIG. 15 (a), a second internal electrode material made of an easily-etchable material is formed on the rectangular ceramic green sheet 31 so as to extend from one end edge 31a to the other end edge 31b side.
Prepare a printout of 33. Here, the second internal electrode material 33 is the other end edge 31b of the ceramic green sheet 31.
It is said that the length does not reach. Next, in the vicinity of the one end edge 31a, the first internal electrode material 32 made of a difficult-to-etch material is printed. Similarly, as shown in FIG. 15 (b), the first and second internal electrode materials 35, 36 are printed on the ceramic green sheet 34 in a state in which the position is reversed from that on the ceramic green sheet 31. Prepare what you did.

A plurality of these ceramic green sheets 31 and 34 are alternately laminated, and if necessary, the ceramic green sheets on which the electrode paste is not printed are laminated on the uppermost and lowermost portions,
A raw dielectric chip may be obtained. In this case, since the second inner electrode materials 33, 36 are formed so as not to reach the edges 31b, 34b, etching should be performed only on the side edge portions of the second inner electrode materials 33, 36. Good. That is, the leading edge margin region in the above-described embodiment is formed by providing a region where the internal electrode material is not printed.

Also, the mother ceramic green sheets 11 and 1 shown in FIG.
Instead of 4, a plurality of mother ceramic green sheets 37, 38 shown in FIGS. 16 (a) and 16 (b) may be alternately laminated. In the example of FIG. 16 (a), after stacking, cutting is performed along the alternate long and short dash lines A and B of FIGS. 16 (a) and 16 (b). However, the printed shape of the internal electrode material formed on the upper surface of the ceramic green sheet 14 shown in FIG. 5 (b) is the reverse of the printed shape of the internal electrode material formed on the upper surface of the ceramic green sheet 11. Is equivalent to
While only one type of printing shape was required, in the example of FIG. 15, different printing shapes were used for the first and second internal electrode materials 39, 40, 41.
Ceramic green sheets 37,38 with a, 41b, 42 printed
You must prepare two kinds of.

〔The invention's effect〕

As described above, in the manufacturing method of the present invention, the side margin region on the side of the internal electrode is exposed on the side surface of the sintered body.
It is formed by etching the side edge portion of the internal electrode portion of. Therefore, in the laminating step performed to obtain the laminated type sintered body, the side margin area having the minimum necessary width is accurately formed without considering the laminating deviation of the ceramic green sheets and the printing deviation of the conductive paste for internal electrodes. can do. Therefore, it is possible to obtain a small-sized and large-capacity multilayer capacitor with small variation in capacitance value.

Further, in the laminated type sintered body, the width of the second internal electrode portion is the same as the width of the dielectric ceramic layer, and therefore, the allowable positioning range of the ceramic green sheet is widened during the lamination prior to sintering, The laminating operation can be performed relatively easily. Further, when forming the first and second internal electrode portions, the conductive paste is formed to have the same width as the ceramic green sheet, so that the types of electrode print patterns can be reduced. Therefore, the cost of the multilayer capacitor can be reduced by simplifying the work process.

Further, in the above-mentioned integrally sintered type sintered body, since the first internal electrode portion and the second internal electrode portion are exposed on the side surface, the internal electrode portion exposed on the side surface during sintering is inside the ceramics. It also serves as a heat transfer medium for accelerating the sintering, and has an effect that the sintering can be favorably performed in a short time.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a state in which a side margin region is formed by etching in a manufacturing method according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are used for manufacturing a conventional multilayer capacitor. 3A and 3B are plan views showing the printed shapes of the ceramic green sheet and the internal electrode material formed thereon, and FIGS. 3A and 3B are mother ceramic green sheets and mother internal electrodes used in mass production of conventional multilayer capacitors. Each plan view for explaining the print shape of the material,
FIG. 4 is a cross-sectional view for explaining problems in the conventional multilayer capacitor, and FIGS. 5 (a) and 5 (b) are respectively,
FIG. 6 is a plan view showing each mother ceramic green sheet used in one embodiment of the present invention and each internal electrode material formed thereon, and FIG. 6 is a perspective view showing a laminating step. 8 is a perspective view showing a laminated dielectric raw chip, FIGS. 8 (a) and 8 (b) are side sectional views and plan sectional views of the dielectric raw chip of FIG. 7, and FIG. 9 is an embodiment of the present invention. It is a figure for demonstrating the shape of the side edge of the 2nd internal electrode material, Comprising: Sectional drawing which corresponds to the part which follows the IX-IX line in FIG.8 (b), FIG. Perspective view showing union, No. 11
FIG. 12 is a perspective view showing a sintered body after etching, FIG. 12 is a perspective view showing a state in which external electrodes are formed, and FIG. 13 is XI of FIG.
An enlarged cross-sectional view taken along line II-XIII, FIG. 14 is a cross-sectional view showing a state in which a gap is filled with a sealing material, and FIGS. 15 (a) and 15 (b).
Is a plan view for explaining another embodiment of the present invention,
FIGS. (A) and (b) are plan views for explaining still another example of the printed shapes of the ceramic green sheet and the internal electrode material that can be used in the present invention. In the figure, 11 and 14 are ceramic green sheets, 12a and 1
2b, 15a, 15b are first internal electrode parts (first internal electrode material),
13, 16 are second internal electrode portions (second internal electrode material), 17 are green chips, 20 is a sintered body, 20a, 20b are first and second end faces, 20
Reference numerals c and 20d denote side surfaces, 21 and 22 denote internal electrodes, 23 and 24 denote side margin regions, 25 denotes a tip margin region, and 26 and 27 denote external electrodes.

Claims (1)

[Claims] 1. A plurality of dielectric ceramic layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is narrower than the width of the dielectric ceramic layer, whereby the side of the internal electrode is formed. In a method of manufacturing a multilayer capacitor having a side margin region formed on one side, a first internal electrode material made of a non-etching material provided near one edge along one edge, and a first internal electrode material A second internal electrode material made of an easily-etchable material and provided over the entire width so as to extend from the one edge to the other edge side facing the one edge on the upper surface side or the lower surface side of the internal electrode material; A plurality of ceramic green sheets each having on one main surface are laminated such that the one edge on the side provided with the first internal electrode material is alternately located on the opposite end surface in the thickness direction. And a step of obtaining the laminated dielectric raw chip, the firing of the laminated dielectric raw chip to sinter the ceramic green sheet, and the firing of the first and second internal electrode materials, respectively. First, a step of forming a plurality of internal electrodes having a second internal electrode portion, and etching the sintered body with a chemical that selectively etches the second internal electrode portion to obtain a second internal electrode portion. A step of forming a side margin region by removing at least a portion exposed on the side surface of the sintered body and the vicinity thereof, and the first internal electrode portion is opposed to the exposed sintered body. And a step of forming external electrodes on the end faces.