JP4252277B2 - Multilayer electronic component and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminated electronic component in which a plurality of electrode layers are laminated via an insulating layer, and a method of manufacturing such a laminated electronic component using a ceramic green sheet.
[0002]
[Prior art]
Conventionally, when manufacturing this type of multilayer electronic component, for example, a multilayer ceramic electronic component in which an insulating layer is formed of a ceramic layer, a predetermined number of ceramic green sheets having the same shape are usually stacked (for example, Patent Documents). 1, see Patent Document 2).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-241890
[Patent Document 2]
JP-A-3-283490
[0004]
[Problems to be solved by the invention]
However, in the conventional multilayer ceramic electronic component, the following problems have been pointed out.
[0005]
Such multilayer ceramic electronic components are widely used as multilayer ceramic capacitors and multilayer ceramic inductors. In these electronic components, a capacitor electrode or an inductor electrode is formed on a ceramic green sheet by a printing method, for example, and the ceramic green sheets are laminated.
[0006]
In the stacked upper and lower sheets, there are a portion where the sheet and the sheet are directly in contact with each other and a portion where the sheet is stacked with the electrode interposed, for the convenience of different electrode patterns and formation positions. FIG. 12 is an explanatory view schematically showing such a state. Since this occurs for all the stacked sheets, as shown in the drawing, the central portion of the sheet in the figure as a whole is the other sheet portion (in the drawing, because of the electrode 101 interposed between the sheets 100). It is more convex than the left and right end portions.
[0007]
If the green sheet is sintered with such a convex shape, the convex shape remains in the sintered product (multilayer ceramic electronic component) after sintering. It is subjected to a pressing process. During the pressing, the ceramic green sheet is bent by the pressing at the peripheral edge (edge) of the electrode end. The state of bending at the edge is almost determined by the extent of the ceramic green sheet. In general, in a multilayer ceramic capacitor, since the thickness of the ceramic green sheet is reduced to about 5 μm in order to improve the capacitor function, there is no room for the extension of the sheet. For this reason, the bent portion at the edge cannot be covered by the extension of the sheet, and a crack may occur at the edge. Since such cracks cause cracks during sintering and a decrease in electronic component function, it is preferable to prevent the occurrence of cracks. The countermeasures were not enough and there was room for improvement. Such crack generation is not limited to the case of using a ceramic green sheet, but can also occur in a laminated electronic component using a thermosetting resin sheet.
[0008]
In addition, in the case of using the ceramic green sheet, the following unique problems have been pointed out.
In a multilayer ceramic capacitor, a through-hole penetrating in the laminating direction is formed in the state of a laminated ceramic green sheet or after sintering for the sake of electrical connection between electrodes located via a ceramic green sheet, and the through-hole is formed. The hole is filled with a conductive material. In the above-mentioned patent documents, the conductive material filling is described in detail.
[0009]
By the way, in addition to the hole formation method using a mechanical punch or a drill, the formation of the above-mentioned through holes includes a hole formation method using thermal melting by laser irradiation, but it is produced in products that require a large number of through holes. From the viewpoint of efficiency, the latter method is frequently used.
[0010]
Since the through hole formed in the multilayer ceramic electronic component is filled with a conductive material as shown in the above patent document, the through hole should be as straight as possible from the viewpoint of ease of filling and reliability. It is desirable to be. However, it has been found that the through-hole forming method using laser irradiation causes a phenomenon that the through-hole swells in the center. Such a phenomenon is expected to occur for the following reasons.
[0011]
The through hole is formed by the deepening of the hole due to the progress of thermal melting by laser irradiation. Since the periphery of the laminated sheet is surrounded by the sheet (ceramic green sheet) and the electrode, heat is accumulated in the through hole forming process. In the sheet and the electrode layer, since the electrode layer usually has a lower melting point, the electrode layer is thermally melted first. The ceramic constituting the sheet usually has a higher melting point than the electrode layer, but becomes brittle because organic components such as the binder disappear. Each of the sheets of each layer has a thickness of only about several μm to several tens of μm, so that it becomes very easy to process when the electrode layer disappears, and the above-described swelling of the through-hole is considered to occur.
[0012]
The present invention has been made to solve the above-mentioned problems, and has an object to increase the reliability of avoiding cracks associated with sheet lamination in the production of laminated electronic components, and in particular to laminated electronic components having a ceramic layer as an insulating layer. In this case, the purpose is to bring the shape of the through-hole formed by laser irradiation closer to a straight shape.
[0013]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the problem, the laminated electronic component of the present invention is a laminated electronic component in which a plurality of electrode layers are laminated via an insulating layer,
Of the insulating layers, at least one insulating layer is thicker than the other insulating layers,
The gist of the invention is that the thick insulating layer is located in the middle of the lamination except for the upper and lower ends of the electrode layer lamination.
[0014]
In the laminated electronic component of the present invention having the above-described configuration, a thick insulating layer (hereinafter referred to as a thick insulating layer for convenience of description) is positioned in the middle of the lamination except for the upper and lower ends of the electrode layer lamination location. This thick insulating layer has a margin in the extension of the sheet due to its thickness. Therefore, when sheets are laminated and pressed in the laminating direction in the production of laminated electronic components, the thick insulation layer with sufficient margin for sheet extension increases the sheet extension due to compression during lamination, and other insulation layers The sheet extension at the can be reduced. As a result, it is possible to reduce the bending of the other insulating layer due to the pressing, and it is possible to improve the reliability of avoiding cracks at the bent portion.
[0015]
The multilayer electronic component of the present invention having the above-described configuration can be realized in various modes. For example, in addition to having a through hole along the stacking direction of the insulating layer and the electrode layer, the insulating layer may be a ceramic layer, and the through hole may be formed through laser irradiation. Thus, the laminated electronic component in which the insulating layer is a ceramic layer and the through holes are formed by laser irradiation has the following advantages. In the following description, the thick insulating layer is referred to as a thick ceramic layer.
[0016]
Even in the part of the thick ceramic layer located in the middle of the lamination of the electrode layer, when the through hole is formed by laser irradiation, it is exposed to the heat of the laser due to the thermal melting of the electrode layer. The progress of heat melting is suppressed. That is, the swelling of the hole is suppressed in the thick ceramic layer portion. Thus, while the thermal melting of the thick ceramic layer and the swelling of the hole are suppressed, the ceramic layer and the electrode layer below it are melted to form a through hole. As a result, when viewed as an entire laminated electronic component, the through hole penetrating the multilayer electronic component approximates a straight hole shape.
[0017]
The multilayer electronic component of the present invention having the above configuration is realized in another aspect. For example, the thick insulating layer can have a thickness approximately equal to about 20 times that of the other insulating layer. If it carries out like this, the thermal fusion accompanying the laser irradiation of a thick insulation layer (thick ceramic layer) can be suppressed more reliably, and a through-hole shape can be made more straight. In this case, since several tens of electrode layers are generally laminated, if the thick insulating layer is about 20 times thicker than other insulating layers, the ratio of the thickness occupied by the thick insulating layer in the laminated electronic component is Not significantly larger. Therefore, careless downsizing of electronic components is not significantly prevented.
[0018]
In addition, the thick insulating layer can be positioned at a substantially central portion of the electrode stack. In this way, the swelling of the hole at the substantially central portion of the electrode stack, where heat is most likely to be accumulated during the through hole formation process by laser irradiation, is suppressed, which is preferable for straightening the through hole shape.
[0019]
A plurality of thick insulating layers may be provided so that the electrode stack thickness is substantially divided into n (n is a natural number of 3 or more, for example, approximately 3, divided approximately 4, etc.). This is more preferable because it is possible to avoid the occurrence of sheet bending / cracking due to the margin of sheet extension described above for each thick insulating layer. In addition, each thick insulating layer can suppress the swelling of the through-hole, which is preferable because the shape of the through-hole as the entire laminated electronic component can be made even more straight. The upper limit of the division may be determined in consideration of the thickness of the laminated electronic component. If the thickness of the laminated electronic component is about 1 mm, the electrode laminated thickness is divided into about 3 to 5, It is possible to improve the reliability of avoiding the occurrence of cracks and sufficiently straighten the through holes.
[0020]
In providing a plurality of thick insulating layers in this way, the other insulating layers and the electrode layers are alternately stacked with a thickness equal to or greater than that of the thick insulating layers between the thick insulating layers. Preferably it is. In this way, even if there are a plurality of thick insulating layers, the electronic component function provided by the electrode layer can be prevented from being significantly reduced.
[0021]
In order to solve at least a part of the problems described above, in the manufacturing method of the present invention, in manufacturing a multilayer electronic component in which a plurality of electrode layers are stacked via a ceramic layer, the ceramic and the ceramic layer are stacked in the stacking direction of the electrode layers. Prior to the through hole forming step and the sintering step penetrating the electrode, the following steps are executed.
[0022]
First, a plurality of first ceramic green sheets having the electrode layer on the surface are laminated (step (a)). Next, a second ceramic green sheet thicker than the first ceramic green sheet is stacked on the first ceramic green sheet on which a plurality of layers have been laminated (step (b)). This second ceramic green sheet becomes a thick insulating layer (thick ceramic layer) in the multilayer electronic component of the present invention after firing.
[0023]
Thereafter, the first ceramic green sheet is stacked on the second ceramic green sheet and laminated in plural layers (step (c)). By doing so, a plurality of first ceramic green sheets having electrode layers are laminated on and under the second ceramic green sheet. Therefore, if laser irradiation is subsequently performed as a method of forming the through hole, thermal melting associated with laser irradiation is suppressed by the thickness of the second ceramic green sheet, and the through hole shape is straightened. it can. In this case, if the upper and lower first ceramic green sheets are stacked to the same extent, the second electronic green sheet can be a multilayer electronic component positioned at a substantially central portion of the electrode stack. The laser irradiation process can also be performed after the sintering process.
[0024]
The manufacturing method of the multilayer electronic component of the present invention having the above-described configuration can be realized in various modes. For example, following the steps (a) to (c), if the steps (b) and (c) are repeated twice or more, the laminated portion of the first ceramic green sheet, the second ceramic green sheet, the first ceramic green These are sequentially laminated such as a laminated portion of the sheet, a second ceramic green sheet, and a laminated portion of the first ceramic green sheet. Accordingly, when the steps (b) and (c) are repeated, if the stacking of the first ceramic green sheets having the electrode layers is made approximately the same, the electrode stacking thickness is divided into approximately three parts by the plurality of second ceramic green sheets. A multilayer ceramic electronic component divided into four parts can be obtained.
[0025]
In the step (b) in the production method of the present invention, the second ceramic green sheet can have a thickness approximately equal to about 20 times that of the first ceramic green sheet. Alternatively, the second ceramic green sheet may have an electrode layer on the surface. In this case, if the second ceramic green sheet is approximately the same thickness as the first ceramic green sheet, a thick sheet portion cannot be formed. Therefore, when the second ceramic green sheet has an electrode layer, the second ceramic green sheet may be about twice to about 20 times thicker than the first ceramic green sheet.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described based on the following procedure. This embodiment relates to a multilayer ceramic capacitor having an insulating layer made of ceramic.
A. Example
A-1. Overall configuration of multilayer ceramic capacitor 10
A-2. Manufacturing process of multilayer ceramic capacitor 10
A-3. Effect
B. Modified example
[0027]
A. Example:
A-1. Overall configuration of multilayer ceramic capacitor 10:
FIG. 1 is an explanatory view showing a longitudinal section of a multilayer ceramic capacitor 10 according to one embodiment of the present invention.
[0028]
As will be described later, the multilayer ceramic capacitor 10 is manufactured through lamination of ceramic green sheets. When firing is performed, each sheet is sintered and integrated. FIG. 1 shows the state after the sintering. As shown in FIG. 1, in the multilayer ceramic capacitor 10, a plurality of electrode layers 24 made of a conductive metal are laminated in a ceramic. Ceramic is interposed in the gap between the electrode layers 24, and the ceramic in the gap portion becomes a ceramic layer that functions as a derivative (insulating layer) between the electrode layers 24. In this embodiment, the ceramic layer is a thick ceramic layer 23 in a thick portion at a substantially central position of the electrode stack and a ceramic layer 22 thinner than the ceramic layer as shown in the figure.
[0029]
Each electrode layer 24 is electrically connected to a via electrode 28 that supplies a voltage from the outside every other layer. Therefore, when a voltage is applied from the via electrode 28 to each electrode layer 24, positive charge is accumulated on one side and negative charge is accumulated on the other side in the electrode layer 24 facing the ceramic layer 22 as a dielectric. Happens. Such a phenomenon occurs at the opposing electrodes, and the multilayer ceramic capacitor 10 functions as a capacitor. Moreover, in this multilayer ceramic capacitor 10, since the portion where the above charge accumulation occurs is in multiple layers, the multilayer ceramic capacitor 10 can provide a small-sized capacitor having a large capacitance.
[0030]
A-2. Manufacturing process of multilayer ceramic capacitor 10:
FIG. 2 is a process diagram showing the manufacturing process of the multilayer ceramic capacitor 10, and FIG. 3 is an explanatory diagram for explaining the state of the process of FIG. The multilayer ceramic capacitor 10 is manufactured through the steps S100 to S180 in FIG. The contents of each process will be described below in the order of the processes.
[0031]
A-2-1. Sheet formation on carrier film (step S100):
First, a ceramic slurry made of barium titanate or the like is uniformly and thinly applied to a long carrier film such as a PET (polyethylene terephthalate) film and dried. Thereby, the ceramic green sheet 22a is formed on the carrier film. The ceramic green sheet 22a becomes the ceramic layer 22 after firing.
[0032]
A-2-2. Formation of electrode layer on sheet (step S110):
Next, an electrode pattern made of Ag—Pd is printed on the dried ceramic green sheet 22a by a screen printing method or the like. As a result, the electrode layer 24 is formed on the surface of the ceramic green sheet 22a where the electrode pattern is printed. Further, there is a portion where the electrode pattern is not printed on the surface of the ceramic green sheet 22a, and the portion where the electrode layer 24 is not formed is referred to as a window portion 25 (see FIG. 3). In this embodiment, the electrode layer 24 has a thickness of about 2 to 3 μm and the ceramic green sheet 22a has a thickness of about 5 μm.
[0033]
A-2-3. Cutting out the ceramic sheet for lamination and peeling of the carrier film (steps S120 and S130):
Next, the ceramic green sheet 22a is cut out in a fixed shape together with the electrode layer 24 on the surface thereof while conveying the long carrier film on which the ceramic green sheet 22a is formed. The cut-out ceramic green sheet 22a is peeled off from the carrier film by winding the carrier film or the like. When cutting out such a ceramic green sheet 22a, as shown in FIGS. 3A and 3B, two types of ceramic green sheets 22a having different layouts of the electrode layer 24 and the window portion 25 are cut out.
[0034]
In parallel with the cutting of these two types of ceramic green sheets 22a, a thick ceramic green sheet 23a having no electrode layer and having a large thickness is cut out in the same shape as the ceramic green sheet 22a (FIG. 3 ( C)). The thick ceramic green sheet 23a becomes the thick ceramic layer 23 in the multilayer ceramic capacitor 10 after firing. In this case, the thickness d of the thick ceramic green sheet 23a is approximately equal to about 20 times the thickness d0 (about 5 μm) of the ceramic green sheet 22a. In this embodiment, the thickness d is about 50 μm. . That is, in this embodiment, the thickness d of the thick ceramic green sheet 23a is about 10 times the thickness d0 (about 5 μm) of the ceramic green sheet 22a.
[0035]
In setting the thickness d of the thick ceramic green sheet 23a, the thickness of the ceramic green sheet 22a in the multilayer ceramic capacitor 10 and the number of stacked layers may be taken into consideration. As described above, when the thickness d of the ceramic green sheet 22a is about 5 μm, the thickness of the thick ceramic green sheet 23a is approximately equal to about 20 times the thickness d (about 5 to about 100 μm). It was confirmed that the effect described later (straightening the through hole) could be obtained. If the thick ceramic green sheet 23a is thinner than the lower limit value of about 5 μm for the thickness d0, a slightly insufficient point for straightening the through-hole is observed. This is preferable because the capacitor 10 is not carelessly thickened. Considering this, when the ceramic green sheet 22a has a thickness d of about 5 μm, the thick ceramic green sheet 23a has a thickness d0 of about 20 to about 100 μm, which is about 4 to about 20 times the thickness d. Is preferred. The thickness d0 of the thick ceramic green sheet 23a can be changed as appropriate according to the thickness d of the ceramic green sheet 22a.
[0036]
A-2-4. Lamination of ceramic sheets (step S140):
FIG. 4 is an explanatory diagram schematically showing the situation when the lamination of sheets is completed and the state of laser irradiation in the steps described later.
Next, a plurality of ceramic green sheets 22a and thick ceramic green sheets 23a formed as described above are laminated. For this lamination, first, a dummy sheet 34 is laid in advance. The dummy sheet 34 has a base ceramic layer 32 formed by applying a thick ceramic slurry onto a release sheet 33 made of PET (polyethylene terephthalate) and drying it.
[0037]
Subsequently, the two types of ceramic green sheets 22a shown in FIGS. 3A and 3B are alternately formed on the base ceramic layer 32 of the laid dummy sheet 34 as shown in FIG. 20 to 200 positive numbers) are stacked. In this lamination, as shown in the figure, the lowermost ceramic green sheet 22a is brought into contact with the base ceramic layer 32, and then the next ceramic green sheet 22a is laminated with the electrode layer 24. It overlaps with the ceramic green sheet 22a.
[0038]
Following the lamination of m layers, a thick ceramic green sheet 23a shown in FIG. 3C is overlaid on the laminated ceramic green sheets 22a. Next, the two types of ceramic green sheets 22a shown in FIGS. 3A and 3B are alternately stacked as described above. By doing so, a ceramic sheet laminate in which 2 m layers of ceramic green sheets 22a are partitioned by thick ceramic green sheets 23a by half of the m layers is completed.
[0039]
In this laminated body, since the number of laminated ceramic green sheets 22a is the same above and below the thick ceramic green sheet 23a, the thick ceramic green sheet 23a is placed at a substantially central portion of the 2 m-layer electrode laminate in the laminated body. Will be located. In this case, the number of laminated ceramic green sheets 22a may be different between the upper and lower parts of the thick ceramic green sheet 23a. In this way, the position of the thick ceramic green sheet 23a is changed according to the difference in the number of laminated layers. can do.
[0040]
The thickness da of the entire ceramic sheet laminate including the dummy sheet 34 defines the thickness of the finished multilayer ceramic capacitor 10. The thickness d0 of the ceramic green sheet 22a that defines the thickness da, the total number of laminated layers 2m, the thickness d of the thick ceramic green sheet 23a, and the thickness of the dummy sheet 34 are determined by the desired specifications and size of the multilayer ceramic capacitor 10. In this example, the thickness da of the entire ceramic sheet laminate was about 1 mm.
[0041]
In the situation where the lamination is finished in this way, because of the green sheet, the green sheet on the upper portion of the window portion 25 bends and enters the window portion to some extent.
[0042]
A-2-5. Formation of through holes by laser irradiation (step S150):
Next, using a laser processing machine, the through hole 26 for filling the conductive material is formed in the laminated body as follows. In the present embodiment, the conductive material filled in the through hole 26 becomes the via electrode 28 shown in FIG. 1 after the product is completed.
As shown in FIG. 4, in the above laminate, the window portions 25 provided in the ceramic green sheet 22a are arranged one above the other in the sheet lamination direction. The laser beam machine irradiates a laser beam 50 along an axis line (one-dot chain line in FIG. 4) connecting the centers of the window portions 25 arranged vertically. As a result, the ceramic green sheet 22a, the electrode layer 24, the thick ceramic green sheet 23a, and the dummy sheet 34 located on the axis are melted by heat from laser irradiation, and penetrate the laminate up and down around the axis. A through hole 26 is formed. FIG. 5 is an explanatory view schematically showing the through-hole 26 formed in a penetrating manner, assuming that the shape is straight. As shown in FIG. 5, the through hole 26 is more than the window portion 25 in order to keep the electrode layer 24 surrounding the window portion 25 and the via electrode 28 filled in the through hole 26 in a non-conductive state. It is formed with a small hole diameter.
[0043]
The sheet laminated body shown in FIG. 4 has a rectangular shape when viewed from above, and thus has window portions 25 in a matrix. Therefore, the irradiation of the laser beam 50 is performed not only on the four places shown in FIG. 5 but also on the matrix-like individual window portions 25 from the upper surface of the rectangular sheet laminate. For this reason, many through-holes 26 are formed in a matrix form in a sheet | seat laminated body.
[0044]
As described above, in this embodiment, a so-called cycle processing method is employed as a method for forming the through holes 26 at a plurality of different positions of the sheet laminate. As shown in FIG. 4, the cycle processing method repeats the step CY of sequentially irradiating each through hole formation position with the laser beam 50 several times, gradually increasing the depth of the hole at each through hole formation position, This is a method of finally forming through holes at all through hole forming positions.
[0045]
In the present embodiment, the depth of the through hole is increased by the thickness of the thick ceramic green sheet 23a, so that the number of shots is increased while keeping the energy per time constant.
[0046]
In the process up to step S150 described above, before and after the process can be changed. For example, the carrier film peeling in step S130 and the sheet lamination in step S140 can be performed in reverse, or the sheet cutting in step S120 can be performed prior to the formation of the wiring layer in step S110. Note that the steps may be performed in the order of step S120 and step S110, and the steps may be further performed in the order of step S140 and step S130.
[0047]
A-2-6. Filling the through hole with the conductive material (step S160):
Next, a conductive material is filled in each through hole 26 of the sheet laminate. The filled conductive material reaches the electrode layer 24 from the inside of the through hole 26 and is solidified. The conductive material thus solidified functions as the above-described via electrode 28 (see FIG. 1).
[0048]
A-2-7. Main press-bonding / surface electrode formation (step S170):
Next, a base ceramic layer (not shown) is brought into contact with the opposite side of the dummy sheet 34 to the sheet laminate thus obtained, and these are pressure-bonded by a high temperature / high pressure press. By such pressure bonding, the ceramic green sheets 22a and the thick ceramic green sheets 23a included in the sheet laminate are in close contact with each other while being sandwiched between the dummy sheet 34 and the base ceramic layer. In the window portion 25, the upper and lower green sheets are pressed into the window portion, and the window portion 25 is almost buried.
[0049]
Subsequently, the release sheet 33 is peeled from the dummy sheet 34 on the surface of the sheet laminate. By such peeling, the sheet laminate causes the via electrode 28 of the portion solidified in the peeling sheet 33 to protrude to the outside. In this embodiment, the protruding portion of the via electrode 28 functions as a surface electrode connected to a power supply such as a battery, but a surface electrode may be separately provided by surface layer printing or the like.
[0050]
A-2-8. Grooving / Degreasing / Firing / Breaking (Step S180):
Next, a groove is formed in the multilayer body in accordance with the size of the multilayer ceramic capacitor 10 to be used, and the laminated body after grooving is degreased and fired. After such firing, the ceramic capacitor 10 as shown in FIG. 1 is formed. If the laminated body after firing is broken along a groove (not shown) inserted in the grooving step, a smaller ceramic capacitor 10 can be formed.
[0051]
A-3. Effects of the embodiment:
The effect obtained by taking the manufacturing process demonstrated above is demonstrated using drawing.
FIG. 6 is an explanatory view schematically showing the effect of the present embodiment in comparison with the conventional one.
In the process of forming the through hole 26, as described above, the laser beam 50 is repeatedly irradiated to the hole forming portion, and the hole depth increases each time. Now, assume a situation in which laser beam irradiation is reaching the periphery of the thick ceramic green sheet 23a as shown in FIG.
[0052]
The electrode layer 24, which is an Ag-Pd electrode pattern, has a lower melting point than the ceramic green sheet 22a and the thick ceramic green sheet 23a. . This melting state is indicated by a wavy arrow in the figure, and the end face 24a is retracted from the position where the through hole 26 is formed. On the other hand, the sheet becomes brittle due to the disappearance of organic components such as the binder, and the sheet having a thickness of only 5 μm becomes very easy to process due to the absence of the electrode layer. As described above, the electrode layer 24 and the ceramic green sheet 22a are sequentially processed, so that the end surface of the ceramic green sheet 22a recedes relatively greatly from the place where the through hole 26 is formed.
[0053]
Similarly, organic components such as binder disappear in ceramic green sheet 22a and thick ceramic green sheet 23a. However, thick ceramic green sheet 23a is thick enough to maintain a certain level of strength and suppress expansion of through holes. Is done.
[0054]
Further, as described above, the thick ceramic green sheet 23a is almost at the center position in the sheet laminate, so that heat is likely to be accumulated in the process of laser beam irradiation. Therefore, in the conventional product of FIG. 6B, the ceramic green sheet 22a and the electrode layer 24 are further melted by the accumulated heat, causing the through hole 26 to swell. However, in the example product of FIG. 6A, the thick ceramic green sheet 23a is thick, so that such melting is suppressed and middle swelling is also suppressed. Thus, while the thermal melting and the expansion of the hole in the thick ceramic green sheet 23a are suppressed, the ceramic green sheet 22a and the electrode layer 24 are thermally melted below to form the through hole 26.
[0055]
The example product and the conventional product in which the through-hole 26 was formed as described above were cut after firing, and the hole shape of the through-hole 26 was observed with a microscope. However, the degree of swelling in the example product was small. Further, in this example product, although there was a slight middle swelling in the laminated portions of the multilayer ceramic green sheets 22a above and below the thick ceramic green sheet 23a, it was compared with the middle swelling near the center of the through hole in the conventional product. The degree was small enough. And if it sees as a sheet | seat laminated body (the laminated ceramic capacitor 10 as a finished product), the hole shape of the through-hole 26 from the upper end to the lower end approximated a straight shape practically.
[0056]
In addition, according to the present embodiment, having the thick ceramic green sheet 23a has the following advantages when performing the main pressure bonding in step S170 described above.
First, the state of the main pressure bonding in this embodiment will be described. In this main pressure bonding, the sheet laminate is placed in a rectangular pressurized container when performing high-temperature and high-pressure pressing, and about 59 MPa (about 600 kgf / cm ² ) Under high pressure and heated through a pressing plate (about 80 ° C.). The pressure vessel functions so as not to break the rectangular shape of the sheet laminate, and also performs air bleeding from the side of the laminate.
[0057]
When this main pressure bonding is performed, as described above, the upper and lower green sheets are pressed into the window portion 25 and the electrode pattern end portion to enter. FIG. 7 is an explanatory view schematically showing the state of the ceramic green sheet 22a at the window 25 and the end of the electrode pattern at the time of the main pressure bonding, and FIG. 8 is a case having the ceramic green sheet 22a and the thick ceramic green sheet 23a. It is explanatory drawing which exaggerates and shows the state of the green sheet in the window part 25 and the electrode pattern edge part of this.
[0058]
As shown in the figure, although the electrode layers 24 and the ceramic green sheets 22a are alternately laminated, the window portions 25 leave gaps in the portions where the window portions 25 are arranged vertically, whereas between the window portions, There is no such void. Moreover, since the electrode layer 24 does not exist in each layer of the sheet lamination at the end portion of the electrode pattern, a gap is left for each sheet. Therefore, in the sheet laminated body before the main press bonding, there is a slight rise between the window portions as compared with the positions where the window portions 25 are formed, and at the electrode pattern end portions, the portions where the electrode layers 24 are present and the sheet end portions where there is no electrode pattern, Then, the difference of the excitement becomes remarkable. By performing the main pressure bonding in such a state, the ceramic green sheet 22a and the electrode layer 24 are in close contact with each other with the ceramic green sheet 22a entering the window 25 and the electrode pattern end.
[0059]
At this time, at the peripheral edge (edge) of the window portion 25, the ceramic green sheet 22 a entering the window portion 25 is bent by pressing. In addition, at the end portion of the electrode pattern, the above-described bulge is remarkable, so that bending due to a large pressure occurs as compared with the peripheral portion of the window portion 25. The bending at the window edge and the electrode pattern end is substantially determined by the extent of the ceramic green sheet 22a, and if there is a margin in the sheet extension, the bending at the window edge and the electrode pattern end is avoided. Covering the extension of the sheet does not inadvertently cause cracks at the bent portion.
[0060]
However, in the conventional product using only the ceramic green sheet 22a as shown in FIG. 6B, the ceramic green sheet 22a has a thin thickness of about 5 μm, so there is no margin for the extension of the sheet. For this reason, the bent portion at the window edge and the electrode pattern edge cannot be covered by the extension of the sheet, and a crack may be generated at the window edge or the electrode pattern edge, and the crack avoidance reliability is sufficient. That's not true. Since such cracks cause cracking during sintering and a decrease in electronic component function, it is preferable to prevent the occurrence of cracks.
[0061]
On the other hand, in the product of this example in which the thick ceramic green sheet 23a is interposed, there is a margin in the sheet extension of the thick ceramic green sheet 23a. Since the main compression is performed in the rectangular pressurized container, the thick ceramic green sheet 23a causes the sheet extension in a situation where the sheet extension in the outer shape direction is physically restricted. In other words, the thick ceramic green sheet 23a compresses itself and replaces the sheet extension into the window 25 and the electrode pattern end where there is a gap, as shown in FIG. For this reason, since the bending of the ceramic green sheet 22a in the window part 25 and the electrode pattern edge part is also small, the reliability of crack avoidance mentioned above can be improved.
[0062]
In the manufacturing process of the multilayer ceramic capacitor 10 of the above embodiment, the through holes 26 are formed in the sheet laminate before firing. Thereby, the unsintered ceramic green sheet 22a and the thick ceramic green sheet 23a may be thermally melted by the laser beam 50. For this reason, the through-hole 26 can be formed with a small irradiation amount.
[0063]
B. Variations:
As mentioned above, although embodiment of this invention was described using the Example, this invention is not restricted to the said Example, It is possible to implement in a various aspect in the range which does not deviate from the summary.
[0064]
FIG. 9 is an explanatory view schematically showing a monolithic ceramic capacitor 10A of a first modification.
As shown in the figure, in this modification, the thick ceramic layer 23 is formed at two locations so as to divide the entire thickness of the electrode layer 24 into approximately three. According to the multilayer ceramic capacitor 10 </ b> A of this modification, it is possible to suppress the swelling of the through-hole 26 as described above in the thick ceramic green sheet 23 a for forming each thick ceramic layer 23. Therefore, the through-hole shape as the whole multilayer ceramic electronic component can be made even more straight. In this case, the upper limit of division by the thick ceramic green sheet 23a may be determined in consideration of the thickness of the multilayer ceramic capacitor 10A. If the thickness of the multilayer ceramic electronic component is about 1 mm, the electrode stack thickness is about 3 If it is divided into ˜5, sufficient through holes can be straightened.
[0065]
In the production of the multilayer ceramic capacitor 10A of this modification, up to step S140 shown in FIG. 2, the lamination of the ceramic green sheet 22a and the superposition of the thick ceramic green sheet 23a and the ceramic thereon are performed in the lowermost layer region. The green sheets 22a may be stacked, and then the thick ceramic green sheets 23a may be overlapped again, and then the ceramic green sheets 22a may be stacked for the uppermost layer region. In this way, it is possible to easily manufacture a monolithic ceramic capacitor 10A in which the electrode lamination thickness is substantially divided into three by the thick ceramic layer 23 as shown in FIG.
[0066]
Further, it can be modified as follows.
FIG. 10 is an explanatory view showing a ceramic green sheet 22a and a thick ceramic green sheet 23a used in another modification.
As shown in the figure, in this modification, the thick ceramic green sheet 23a is the same as the ceramic green sheet 22a in that the electrode layer 24 is provided on the surface thereof by a screen printing method or the like and the window portion 25 is formed. Even if such a thick ceramic green sheet 23a is used, the multilayer ceramic capacitor 10 shown in FIG. 1 can be easily manufactured through the manufacturing steps described above.
[0067]
In addition, when using the thick ceramic green sheet 23a which has the electrode layer 24 in this way, it is preferable to make the thickness d into about 2 to 20 times the ceramic green sheet 22a. That is, if the thickness d is about twice the thickness d0 of the ceramic green sheet 22a, it is possible to reliably form the thick ceramic layer 23 that is thicker than the other portions.
[0068]
Further, in the above embodiment, the cycle processing method is adopted for the laser irradiation, but a burst processing method in which the laser beam is continuously irradiated can also be adopted. The shape of the through hole 26 can also be made straighter by laser irradiation in this burst processing method.
[0069]
Moreover, in the said Example, although the manufacturing process was demonstrated taking the case of the multilayer ceramic capacitor, it is also possible to apply said manufacturing process to other multilayer electronic components other than a multilayer ceramic capacitor. For example, even when the above manufacturing process is applied to a multilayer ceramic inductor, the reliability of crack avoidance can be improved.
[0070]
In the above-described embodiments and modifications, the one having a through hole has been described. However, the present invention can be applied to a laminated electronic component having no through hole. FIG. 11 is an explanatory view for explaining a multilayer ceramic capacitor 10B of another modification.
[0071]
As shown in the figure, this multilayer ceramic capacitor 10 is different from the above-described embodiment in that a plurality of electrode layers 24 are stacked via a ceramic layer 22 and a thick ceramic layer 23 is provided at a substantially central position of the electrode stack. Although it is not a thing, it differs in the point by which every other electrode layer is made to conduct | electrically_connect with the electroconductive external conduction metal fitting 40 with which the laminated body outer periphery was mounted | worn. That is, the multilayer ceramic capacitor 10B of this modification has no through hole. Even in this modified example, when the first and second ceramic green sheets are laminated to form these ceramic layers, the central portion in the figure is convex as shown in FIG. Based on the margin of sheet extension of the thick ceramic layer 23 (thick ceramic green sheet 23a) located in the middle, the reliability of crack avoidance can be improved as in the above embodiment.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a longitudinal section of a multilayer ceramic capacitor 10 according to an embodiment of the present invention.
FIG. 2 is a process diagram showing a manufacturing process of the multilayer ceramic capacitor 10;
FIG. 3 is an explanatory diagram for explaining a state of the process of FIG. 2;
FIG. 4 is an explanatory diagram schematically showing a situation when sheet lamination is completed and a state of laser irradiation in steps to be described later.
FIG. 5 is an explanatory view schematically showing a through-hole 26 formed so as to be formed on the assumption that the shape thereof is a straight shape.
FIG. 6 is an explanatory view schematically showing the effect of the present embodiment compared to the conventional one.
FIG. 7 is an explanatory view schematically showing exaggeratedly the appearance of the ceramic green sheet 22a at the window portion 25 and the end portion of the electrode pattern at the time of the main pressure bonding.
FIG. 8 is an explanatory view schematically showing exaggeratedly the appearance of the green sheet at the window portion 25 and the electrode pattern end when the ceramic green sheet 22a and the thick ceramic green sheet 23a are provided.
FIG. 9 is an explanatory view schematically showing a monolithic ceramic capacitor 10A of a first modified example.
FIG. 10 is an explanatory view showing a ceramic green sheet 22a and a thick ceramic green sheet 23a used in another modification.
FIG. 11 is an explanatory diagram for explaining a multilayer ceramic capacitor 10B of another modified example.
FIG. 12 is an explanatory diagram for explaining problems of a conventional multilayer electronic component.
[Explanation of symbols]
10 ... Multilayer ceramic capacitor
10A ... Multilayer ceramic capacitor
22 ... Ceramic layer
22a ... Ceramic green sheet
23 ... Thick ceramic layer
23a ... Thick ceramic green sheet
24 ... Electrode layer
24a ... end face
25 ... Window
26 ... through hole
28 ... via electrode
32 ... Base ceramic layer
33 ... Release sheet
34 ... Dummy sheet
40 ... External conducting metal fittings
50 ... Laser beam

Claims (9)

An electrode layer over the ceramic insulation layer a multilayer electronic component obtained by stacking a plurality
Wherein of the insulating layer, at least one insulating layer, and position the stacking middle portion except the upper and lower ends of the electrode layer laminated portion electrodeposition on the thickness than the other insulating layer is thicker,
The insulating layer and the electrode layer are provided with through holes formed so as to penetrate along the stacking direction,
The through-hole is a laminated electronic component that is formed by penetration by laser irradiation in a state before firing in which the insulating layer including the insulating layer having the increased thickness and the electrode layer are laminated . The multilayer electronic component according to claim 1,
The laminated electronic component, wherein the thick insulating layer has a thickness approximately equal to approximately 20 times that of the other insulating layer. A serial mounting multilayer electronic component in claim 1 or billed to claim 2,
The thick insulating layer is a laminated electronic component located at a substantially central portion of the electrode laminate. A serial mounting multilayer electronic component in claim 1 or billed to claim 2,
A multilayer electronic component in which the thick insulating layer is positioned in plural so that the electrode stack thickness is substantially divided into n (n is a natural number of 3 or more). A multilayer electronic component according to claim 4 Symbol mounting,
Between the thick insulating layers located at the n-divided portions, the other insulating layers and the electrode layers are alternately stacked with a thickness equal to or greater than the thickness of the thick ceramic. Electronic components. A method for producing a laminated electronic component in which a plurality of electrode layers are laminated via a ceramic layer,
As a step performed prior to a through hole forming step and a sintering step for forming a through hole penetrating the ceramic and the electrode in the stacking direction of the electrode layer,
A step (a) of laminating a plurality of first ceramic green sheets having the electrode layer on the surface;
After the step (a), a step (b) of stacking a second ceramic green sheet thicker than the first ceramic green sheet on the first ceramic green sheet on which a plurality of layers are laminated;
After the step (b), a step (c) of stacking a plurality of layers by stacking the first ceramic green sheet on the second ceramic green sheet is provided. A claim 6 Symbol mounting method of manufacturing a multilayer electronic component,
Subsequent to the steps (a) to (c), the step (b) and the step (c) are repeated twice or more times. 6. or the method of manufacturing a multilayer electronic component according to claim 7 Symbol mounting,
The method for manufacturing a laminated electronic component, wherein the second ceramic green sheet in the step (b) has a thickness approximately equal to approximately 20 times that of the first ceramic green sheet. A claim 6 Symbol mounting method of manufacturing a multilayer electronic component,
The method for producing a laminated electronic component, wherein the second ceramic green sheet in the step (b) includes the electrode layer on a surface thereof and has a thickness of about 2 to about 20 times that of the first ceramic green sheet.

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