JP2009283824A - Electronic component and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component which hardly provides the erroneous determination of exposure failure, and to provide a manufacturing method thereof. <P>SOLUTION: A layered product 12 is constituted by laminating a plurality of magnetic layers 16, 17. A plurality of coil electrodes 18 are laminated with the magnetic layer 16 to constitute a coil L. In the z axis direction of the layered product 12, within a range from surfaces positioned at both ends to at least 5 μm is constituted of a porous insulating layer 17 whose void ratio is ≥3.0% to t≤35.0%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic component and a manufacturing method thereof, and relates to an electronic component in which a coil is built in a laminate and a manufacturing method thereof.

  As a conventional electronic component, for example, a multilayer inductor described in Patent Document 1 is known. In the multilayer inductor, a plurality of insulating layers and a plurality of coil forming conductive patterns are alternately stacked. The plurality of coil forming conductive patterns are connected to each other to form one coil. The coil forming conductive patterns provided on the uppermost and lower sides in the laminating direction are drawn out to the side surface of the laminated body made of an insulating layer and connected to the external electrodes formed on the side surface of the laminated body. Has been.

  In the multilayer inductor configured as described above, appearance selection is performed after completion. More specifically, the upper surface of the multilayer inductor is photographed by an image pickup device such as a CCD, and the obtained image is analyzed to determine whether or not an appearance defect of the multilayer inductor has occurred. As the appearance defect of the multilayer inductor, for example, the uppermost coil-forming conductive pattern in the stacking direction breaks through the uppermost insulating layer in the stacking direction and is exposed to the outside in the crimping process or firing process (hereinafter referred to as the following) , Referred to as poor exposure).

  By the way, in the multilayer inductor, as described below, there is a risk of erroneous determination of poor exposure in appearance selection. More specifically, as the number of coil-forming conductive patterns increases, a number of coil-forming conductive patterns overlap in the stacking direction. Therefore, a difference in size occurs between the thickness in the stacking direction of the region where the coil forming conductive pattern is formed and the thickness in the stacking direction of the region where the coil forming conductive pattern is not formed. As a result, large irregularities occur along the shape of the coil-forming conductive pattern on the upper surface of the multilayer inductor.

Here, the upper surface of the multilayer inductor is a surface having a smooth gloss. Therefore, when such unevenness is generated, the protruding portion becomes brighter and the surrounding area becomes darker in the image obtained by the image sensor. As a result, in the appearance selection, there is a possibility that it may be erroneously determined that the coil forming electrode pattern is exposed in a bright portion even though no exposure failure has occurred.
JP 55-91103 A

  Accordingly, an object of the present invention is to provide an electronic component that is less prone to misjudgment of exposure failure and a method for manufacturing the same.

  An electronic component according to an aspect of the present invention includes: a stacked body in which a plurality of insulating layers are stacked; and a plurality of internal electrodes that are stacked together with the insulating layers to form a coil. In the direction, the range from the surface located at both ends to at least 5 μm is constituted by the porous insulating layer having a porosity of 3.0% or more and 35.0% or less.

  According to the present invention, the range from the surface located at both ends to at least 5 μm is constituted by the porous insulating layer having a porosity of 3.0% or more and 35.0% or less. Can be suppressed.

  Below, the electronic component which concerns on one Embodiment of this invention, and its manufacturing method are demonstrated.

(Configuration of electronic parts)
FIG. 1A is an external perspective view of the electronic component 10. FIG. 1B is a cross-sectional structure diagram taken along the line AA of the electronic component 10. FIG. 2 is an exploded perspective view of the multilayer body 12 of the electronic component 10. Hereinafter, the stacking direction of the electronic component 10 is defined as the z-axis direction, the direction along the long side of the electronic component 10 is defined as the x-axis direction, and the direction along the short side of the electronic component 10 is defined as the y-axis direction. To do. In addition, in FIG.1 (b), although the boundary line of each layer is shown with the dotted line, there may exist a boundary line which can be visually recognized actually.

  As shown in FIG. 1A, the electronic component 10 includes a rectangular parallelepiped laminated body 12 including a coil L therein, and two external electrodes formed on side surfaces of the laminated body 12 positioned at both ends in the x-axis direction. 14a, 14b.

  The laminated body 12 is configured by laminating a plurality of coil electrodes and a plurality of magnetic layers, as will be described below. As shown in FIGS. 1B and 2, the laminate 12 includes a plurality of insulating layers (magnetic layers 16 a to 16 a) made of ferromagnetic ferrite (for example, Ni—Zn—Cu ferrite or Ni—Zn ferrite). 16h, 17a, 17b) and coil electrodes 18a-18g are laminated. Hereinafter, when referring to the individual magnetic layers 16a to 16h, 17a and 17b and the coil electrodes 18a to 18g, an alphabet is added after the reference symbol, and when these are collectively referred to, Omit the alphabet.

  The magnetic layer 16 is a layer having a rectangular shape, and is a relatively densely structured layer that is not porous and has a porosity after firing of 0% to 0.5%. The porosity is defined by the pore area ratio. The pore area ratio means that the cross section defined by the width direction and the thickness direction of the laminated body 12 made of ferrite is mirror-polished, the surface subjected to focused ion beam processing (FIB processing) is observed with a scanning microscope (SEM), and sintered. The pore area ratio in the ferrite after sintering is measured. The most preferable value of the porosity of the magnetic layer 16 is 0%. As shown in FIGS. 1B and 2, the magnetic layers 16 a to 16 h are laminated from the top in this order.

  As shown in FIG. 2, via hole conductors b1 to b6 that penetrate the magnetic layers 16b to 16g in the z-axis direction are formed in the magnetic layers 16b to 16g, respectively.

  Furthermore, coil electrodes 18a to 18g constituting the coil L are formed on the main surfaces of the magnetic layers 16b to 16h, respectively, as shown in FIGS. Each coil electrode 18a-18g consists of an electroconductive material which consists of Ag, and has "U" shape. That is, the coil electrodes 18a to 18g have a length corresponding to 3/4 turns. The coil electrodes 18a and 18g formed on the lowermost side and the uppermost side in the stacking direction are connected to the external electrodes 14a and 14b, respectively. The coil electrodes 18a to 18g may be formed of a conductive material such as a noble metal mainly composed of Pd, Au, Pt or the like, or an alloy thereof. The coil electrodes 18a to 18g are not limited to 3/4 turns.

  When the magnetic layers 16a to 16h configured as described above are stacked in this order from the upper side in the stacking direction, the coil electrodes 18a to 18g are connected to each other by the via-hole conductors b1 to b6, A coil L is configured.

  As shown in FIG. 1A, the magnetic layer 17 is a layer having a rectangular shape with thicknesses D1 and D2 of 5 μm or more in the z-axis direction. Further, the magnetic layer 17 is a layer having a higher porosity than the magnetic layer 16, and specifically, a relatively sparse configuration in which the porosity after firing is 3% or more and 35.0% or less. It is a porous layer. As shown in FIGS. 1B and 2, the magnetic layer 17 a is laminated on the uppermost side in the z-axis direction. Further, the magnetic layer 17b is laminated on the lowermost side in the z-axis direction as shown in FIGS.

(effect)
According to the electronic component 10 configured as described above, it is possible to suppress misjudgment of exposure failure as described below. More specifically, when exposure failure occurs, the magnetic layer 17 is broken through and the coil electrode 18 is exposed to the outside. In this case, since the coil electrode 18 has a stronger gloss than the magnetic layer 17, a portion where the coil electrode 18 is exposed in the image obtained by the imaging element becomes brighter than the other portions. . Therefore, the determination of poor exposure is performed by determining whether a large contrast is generated in the image.

  However, in a conventional electronic component (for example, the multilayer inductor described in Patent Document 1), when a large number of coil electrodes overlap in the stacking direction, large irregularities are formed along the shape of the coil electrode on the upper surface of the electronic component. Will occur. As a result, in the image obtained by the image sensor, the protruding portion becomes bright and the surroundings become dark. As a result, in the appearance selection, there is a possibility that it may be erroneously determined that the coil electrode is exposed in a bright portion even though no exposure failure has occurred.

  On the other hand, in the electronic component 10 according to the present embodiment, the magnetic layer 17 disposed on the uppermost side in the z-axis direction and the lowermost side in the z-axis direction has a higher porosity than the magnetic layer 16. . Therefore, the magnetic layer 16 is less likely to reflect light than the magnetic layer 17. Therefore, even when the number of coil electrodes 18 increased and large irregularities occurred on the upper surface and the lower surface of the multilayer body 12, when no exposure failure occurred in the electronic component 10, it was obtained by the imaging device. In the image, the contrast between the protruding portion and the periphery thereof is suppressed to be small. As a result, in the appearance selection, it is suppressed that the coil electrode 18 is erroneously determined to be exposed in a bright portion even though no exposure failure has occurred.

  Further, when an exposure failure occurs in the electronic component 10, the glossy coil electrode 18 is exposed from the magnetic layer 17 that is relatively difficult to reflect light. Therefore, in the electronic component 10, compared with the case where the coil electrode is exposed from a magnetic layer that is relatively easy to reflect light as in the conventional electronic component, the portion where the coil electrode 18 is exposed and the rest A greater contrast is generated between these parts. As a result, in the electronic component 10, it is possible to determine the exposure failure with higher accuracy in the appearance selection as compared with the conventional electronic component.

  The external electrodes 14 a and 14 b are formed so as to contact the porous magnetic layer 17. Therefore, a part of the external electrodes 14a and 14b enters into the fine holes of the magnetic layer 17. That is, an anchor effect is generated between the external electrodes 14 a and 14 b and the magnetic layer 17. On the other hand, in the conventional electronic component, since the magnetic layer in contact with the external electrode is not porous, the anchor effect as described above does not occur. Therefore, in the electronic component 10, the external electrodes 14 a and 14 b are more firmly fixed to the multilayer body 12 than the conventional electronic component.

  Further, as will be described below, in the electronic component 10, it is possible to perform barrel processing for chamfering the laminated body 12 in a shorter time than in the conventional electronic component. More specifically, the porous magnetic layer 17 is used for the uppermost layer in the z-axis direction and the lowermost layer in the z-axis direction. Therefore, the ridge lines on the upper surface and the lower surface in the z-axis direction of the multilayer body 12 are formed by the porous magnetic layer 17. The porous magnetic layer 17 is easier to cut than a non-porous magnetic layer. Therefore, the electronic component 10 can be barreled in a shorter time than a conventional electronic component.

(First manufacturing method)
Below, the 1st manufacturing method of the said electronic component 10 is demonstrated, referring FIG.1 and FIG.2.

First, a ceramic green sheet to be the magnetic layer 16 is produced as follows. Each material weighed 45 mol% ferric oxide (Fe ₂ O ₃ ), 5 mol% zinc oxide (ZnO), 40 mol% nickel oxide (NiO), and 10 mol% copper oxide (CuO). Is put into a ball mill as a raw material and wet blended. The obtained mixture is dried and pulverized, and the obtained powder is calcined at 800 ° C. for 1 hour. The obtained calcined powder is wet pulverized by a ball mill, dried and crushed to obtain a ferrite ceramic powder having a particle diameter of 0.5 μm.

  A binder (vinyl acetate, water-soluble acrylic, etc.), a plasticizer, a wetting material, and a dispersing agent are added to the ferrite ceramic powder, followed by mixing with a ball mill, and then defoaming is performed under reduced pressure. The obtained ceramic slurry is formed into a sheet shape by the doctor blade method and dried to produce a ceramic green sheet to be the magnetic layer 16.

  On the other hand, in the production of the ceramic green sheet to be the magnetic layer 17, a binder (vinyl acetate, water-soluble acrylic, etc.), a plasticizer, a wetting material, a dispersing agent and resin beads are added to the ferrite ceramic powder. Mixing is performed with a ball mill, and then defoaming is performed under reduced pressure. The obtained ceramic slurry is formed into a sheet having a thickness of 5 μm or more by a doctor blade method and dried to produce a ceramic green sheet to be the magnetic layer 17.

  Next, via-hole conductors b1 to b6 are formed in the ceramic green sheets to be the magnetic layers 16b to 16g, respectively. Specifically, a via hole is formed by irradiating a ceramic green sheet to be the magnetic layers 16b to 16g with a laser beam. Next, the via hole is filled with a conductive paste such as Ag, Pd, Cu, Au or an alloy thereof by a method such as printing.

  Next, a conductive paste mainly composed of Ag, Pd, Cu, Au, or an alloy thereof is applied to the ceramic green sheets to be the magnetic layers 16b to 16h by a method such as a screen printing method or a photolithography method. By applying, the coil electrodes 18a to 18g are formed. The step of forming the coil electrodes 18a to 18g and the step of filling the via hole with the conductive paste may be performed in the same step.

  Next, each ceramic green sheet is laminated. Specifically, a ceramic green sheet to be the magnetic layer 17b is disposed. Next, the ceramic green sheet to be the magnetic layer 16h is disposed and temporarily pressed onto the ceramic green sheet to be the magnetic layer 17b. Thereafter, the ceramic green sheets to be the magnetic layers 16g, 16f, 16e, 16d, 16c, 16b, 16a, and 17a are similarly laminated and temporarily pressed in this order. Thereby, the magnetic layers 16 and 17 and the coil electrode 18 are laminated to form a mother laminated body. The mother laminate is subjected to main pressure bonding by a hydrostatic pressure press or the like.

  Next, the mother laminate is cut into a laminate 12 having dimensions of 0.6 mm × 0.3 mm × 0.3 mm by guillotine cutting. Thereby, the unfired laminated body 12 is obtained. The unfired laminate 12 is subjected to binder removal processing and firing. The binder removal treatment is performed, for example, in a low oxygen atmosphere at 500 ° C. for 2 hours. Firing is performed, for example, at 890 ° C. for 2.5 hours. At the time of firing, the resin beads contained in the ceramic green sheet to be the magnetic layer 17 are burned out. As a result, the magnetic layer 17 is a porous layer having a thickness in the z-axis direction of 5 μm or more and a porosity after firing of 3.0% or more and 35.0% or less.

  The fired laminated body 12 is obtained through the above steps. The laminated body 12 is subjected to barrel processing to be chamfered. Thereafter, an electrode paste whose main component is silver is applied and baked on the surface of the laminate 12 by, for example, a dipping method or the like, thereby forming silver electrodes to be the external electrodes 14a and 14b. The silver electrode is dried at 120 ° C. for 10 minutes, and the silver electrode is baked at 800 ° C. for 60 minutes.

  Finally, the external electrodes 14a and 14b are formed by performing Ni plating / Sn plating on the surface of the silver electrode. Through the above steps, the electronic component 10 as shown in FIG. 1 is completed.

(Second manufacturing method)
Next, a second manufacturing method of the electronic component 10 will be described. The first manufacturing method and the second manufacturing method are different only in the process of manufacturing the ceramic green sheet to be the magnetic layer 17. More specifically, in the second manufacturing method, the ceramic green sheet to be the magnetic layer 17 is made of a ferrite ceramic powder having a coarser particle diameter than the ceramic green sheet to be the magnetic layer 16. This will be described in detail below.

First, 45 mol% of ferric oxide (Fe ₂ O ₃ ), 5 mol% of zinc oxide (ZnO), 40 mol% of nickel oxide (NiO), and 10 mol% of copper oxide (CuO) were respectively weighed. This material is used as a raw material in a ball mill and wet blended. The obtained mixture is dried and pulverized, and the obtained powder is calcined at 800 ° C. for 1 hour. The obtained calcined powder is wet pulverized by a ball mill, dried and then pulverized to obtain a ferrite ceramic powder having a particle size larger than 0.5 μm.

  A binder (vinyl acetate, water-soluble acrylic, etc.), a plasticizer, a wetting material, and a dispersing agent are added to the ferrite ceramic powder, followed by mixing with a ball mill, and then defoaming is performed under reduced pressure. The obtained ceramic slurry is formed into a sheet shape by the doctor blade method and dried to produce a ceramic green sheet to be the magnetic layer 17.

  As described above, the particle size of the ferrite powder used for the ceramic green sheet to be the magnetic layer 17 produced by the second manufacturing method is the same as that for the ceramic green sheet to be the magnetic layer 16. Larger than the particle size (0.5 μm). Therefore, the ceramic of the magnetic layer 17 is sweeter than the ceramic of the magnetic layer 16 and the sintered density is lowered. Therefore, after firing, the magnetic layer 17 has a larger porosity than the magnetic layer 16.

(Examples and experiments)
In the following, experiments conducted using the first to fourth embodiments and the first to fourth embodiments of the electronic component 10 will be described.

  The electronic component 10 according to the first example was manufactured by the second manufacturing method. Specifically, the chip size was 0.6 mm × 0.3 mm × 0.3 mm, the number of turns was 19.5 turns, and the thickness of the magnetic layers 17a and 17b after firing was 5 μm. Further, the particle size of the ferrite powder of the ceramic green sheet to be the magnetic layer 16 was 0.5 μm, and the particle size of the ferrite powder of the ceramic green sheet to be the magnetic layer 17 was 1.4 μm. The magnetic layer 17 of the electronic component 10 according to the first example obtained under the above conditions had a porosity of 3.0%. The magnetic layer 16 had a porosity of 0.1%.

  The electronic component 10 according to the second example was manufactured by the first manufacturing method. Specifically, the chip size was 0.6 mm × 0.3 mm × 0.3 mm, the number of turns was 19.5 turns, and the thickness of the magnetic layers 17a and 17b after firing was 5 μm. Further, in the production of the ceramic green sheet to be the magnetic layer 17, the ferrite powder and the resin beads were mixed at a ratio of 8: 2. The magnetic layer 17 of the electronic component 10 according to the second example obtained under the above conditions had a porosity of 15.0%. The magnetic layer 16 had a porosity of 0.1%.

  The electronic component 10 according to the third example was manufactured by the second manufacturing method. Specifically, the chip size was 0.6 mm × 0.3 mm × 0.3 mm, the number of turns was 19.5 turns, and the thickness of the magnetic layers 17a and 17b after firing was 5 μm. Further, the particle size of the ferrite powder of the ceramic green sheet to be the magnetic layer 16 was 0.5 μm, and the particle size of the ferrite powder of the ceramic green sheet to be the magnetic layer 17 was 2.2 μm. The magnetic layer 17 of the electronic component 10 according to the third example obtained under the above conditions had a porosity of 25.0%. The magnetic layer 16 had a porosity of 0.1%.

  The electronic component 10 according to the fourth example was manufactured by the first manufacturing method. Specifically, the chip size was 0.6 mm × 0.3 mm × 0.3 mm, the number of turns was 19.5 turns, and the thickness of the magnetic layers 17a and 17b after firing was 5 μm. Further, in the production of the ceramic green sheet to be the magnetic layer 17, the ferrite powder and the resin beads were mixed at a ratio of 6: 4. The magnetic layer 17 of the electronic component 10 according to the fourth example obtained under the above conditions had a porosity of 35.0%. The magnetic layer 16 had a porosity of 0.1%.

  Next, in order to clarify the effect of the electronic component 10, the following experiment was performed. More specifically, 100,000 electronic parts 10 according to the first to fourth examples were produced. In addition, as an electronic component according to the comparative example, an electronic component in which the magnetic layer 17 of the electronic component 10 according to the first to fourth examples was replaced with the magnetic layer 16 was manufactured. More specifically, 100000 electronic parts having a chip size of 0.6 mm × 0.3 mm × 0.3 mm, a turn number of 19.5 turns, and all layers made of the magnetic layer 16 were produced. Then, the exposure failure rate was determined for the electronic component 10 according to the first to fourth examples and the electronic component according to the comparative example, and the exposure failure rate was measured. Further, the adhesion force between the external electrode and the laminate of these electronic components was measured. Furthermore, in barrel processing, the time required for the corners of the laminate to have a predetermined curvature was measured. Table 1 shown below is a table showing experimental results.

  From the experimental results shown in Table 1, by setting the porosity of the magnetic layer 17 to 3.0% or more and 35.0% or less, the first to fourth examples are compared with the electronic component according to the comparative example. It can be understood that the electronic component 10 according to the example has a lower exposure defect rate. As described below, this means that in the electronic component 10 according to the first to fourth examples, the accuracy of appearance selection is improved as compared with the electronic component according to the comparative example. ing. More specifically, in the electronic component according to the comparative example, among the electronic components determined to be poorly exposed, there are electronic components that were determined to be poorly exposed by misjudgment even though no poor exposure occurred. It is thought that it was included. On the other hand, in the electronic component 10 according to the first to fourth embodiments, the exposure failure rate is reduced. This means that, in the determination of the poor exposure of the electronic component 10, an electronic component that has been erroneously determined as an exposure failure in the past is now accurately determined as not being an exposure failure.

  In addition, according to the experimental results shown in Table 1, the electronic component 10 according to the first to fourth examples has improved adhesion of the external electrode compared to the electronic component according to the comparative example. Can understand. Similarly, according to the experimental results shown in Table 1, in the electronic component 10 according to the first to fourth embodiments, the time required for barrel processing is shortened as compared with the electronic component according to the comparative example. I can understand that.

(Other embodiments)
In the electronic component 10, the thickness of the magnetic layers 17 a and 17 b is 5 μm, but the thickness of the magnetic layers 17 a and 17 b is not limited to this. The thickness of the magnetic layers 17a and 17b may be at least 5 μm or more.

  Further, the magnetic layer 17 is laminated one by one at both ends in the z-axis direction of the laminate 12, but a plurality of the magnetic layers 17 may be laminated at both ends in the z-axis direction of the laminate 12. Good. In other words, in the electronic component 10, the magnetic layer 17 having a porosity of 3.0% or more and 35.0% or less is formed in the range from the surface located at both ends in the z-axis direction to at least 5 μm in the laminate 12. If so, the number of magnetic layers 17 may be any number.

  In addition, even when a plurality of magnetic layers 17 are stacked at both ends of the stacked body 12 in the z-axis direction, the coil electrode 18 is provided in the region where the magnetic layers 17 are stacked. Preferably not. Since the magnetic layer 17 is porous, it has a lower magnetic permeability than the magnetic layer 16. Therefore, if the coil electrode 18 is provided in the region where the magnetic layer 17 is laminated, the inductance of the coil L is reduced.

  Moreover, although the electronic component 10 is produced by the sheet | seat lamination method, the manufacturing method of this electronic component 10 is not restricted to this. The electronic component 10 may be produced by, for example, a transfer method or a printing method.

FIG. 1A is an external perspective view of an electronic component according to an embodiment. FIG. 1B is a cross-sectional structural view taken along line AA of the electronic component according to the embodiment. It is a disassembled perspective view of the laminated body of the electronic component shown in FIG.

Explanation of symbols

L coil 10 Electronic component 12 Laminated body 14a, 14b External electrode 16a-16h, 17a, 17b Magnetic body layer 18a-18g Coil electrode

Claims (5)

A laminate formed by laminating a plurality of insulating layers;
A plurality of internal electrodes laminated with the insulating layer to form a coil;
With
In the stacking direction of the stacked body, the range from the surface located at both ends to at least 5 μm is constituted by the porous insulating layer having a porosity of 3.0% or more and 35.0% or less,
Electronic parts characterized by Among the insulating layers constituting the laminate, the insulating layer that is not porous has a porosity of 0% or more and 0.5% or less,
The electronic component according to claim 1. The internal electrode is not provided in the region where the porous insulating layer is laminated,
The electronic component according to claim 1, wherein: Producing a first insulating layer;
A second insulating layer made of a raw material having a grain size coarser than that of the first insulating layer is prepared so that a porous layer having a porosity of 3.0% or more and 35.0% or less after firing is formed. And the process of
Laminating the first insulating layer and the internal electrode constituting the coil;
Laminating the second insulating layer on the upper side and the lower side in the laminating direction from the first insulating layer so that the thickness in the laminating direction after firing is 5 μm or more;
Firing a laminate comprising the first insulating layer, the second insulating layer, and the internal electrode;
Providing
A method of manufacturing an electronic component characterized by the above. Producing a first insulating layer;
Producing a second insulating layer made of a raw material mixed with resin beads so that a porous layer having a porosity after firing of 3.0% or more and 35.0% or less;
Laminating a plurality of first insulating layers and internal electrodes constituting a coil;
Laminating the second insulating layer on the upper side and the lower side of the laminating direction from the first insulating layer so that the thickness in the laminating direction after firing is 5 μm or more;
Firing a laminate comprising the first insulating layer, the second insulating layer, and the internal electrode;
Providing
A method of manufacturing an electronic component characterized by the above.

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