JP2017011256A - Method of manufacturing ceramic electronic component and ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method by which an electrode can be formed on an arbitrary portion of a surface of a sintered ceramic element body by a simple technique, and to provide a ceramic electronic component manufactured by the method.SOLUTION: A method of manufacturing a ceramic electronic component includes steps of: preparing a sintered ceramic element body 10 containing a metal oxide; forming a low resistance portion 40 from the ceramic element body 10 made by the irradiation of laser L on an electrode forming area on a surface of the ceramic element body 10 to make a part of the ceramic element body 10 have low resistance; and precipitating a plated metal 14a to be an electrode on the low resistance portion 40 by performing a plating on the ceramic element body to grow the plated metal so as to spread over the whole electrode forming area.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for manufacturing a ceramic electronic component and formation of an electrode of a ceramic electronic component, particularly a ceramic electronic component.

Conventionally, a method for forming an external electrode of a ceramic electronic component is to apply an electrode paste to both end faces of a sintered ceramic body and bake it to form a base electrode, and then perform plating on the base electrode. It is common to form an upper layer electrode. However, this method requires a paste application step and a heating step accompanying baking to form the base electrode, and thus there is a problem in that the manufacturing process becomes complicated and costs increase.

Furthermore, when applying the conductive paste in the formation of the base electrode, there is a problem that the application shape is limited. For example, when a conductive paste is formed by dipping on both ends of a rectangular parallelepiped ceramic body, the conductive paste is applied not only to both end faces of the ceramic body but also to four side faces adjacent to both end faces. . Therefore, the external electrode that is finally formed has a shape that extends to both end faces and four side faces adjacent thereto.

In place of such a conventional electrode forming method, a method of forming an external electrode only by plating is proposed (Patent Document 1). In this method, a plurality of ends of the internal electrode are exposed close to the end face of the ceramic body, and dummy terminals called anchor tabs are exposed close to the same end face as the end of the internal electrode. By performing electroless plating on the body, the plating metal is grown using the end portions of the internal electrodes and the anchor tabs as nuclei to form external electrodes.

However, in this method, the end portions of the plurality of internal electrodes and the anchor tabs must be exposed in close proximity to the external electrode forming portion of the ceramic body, which complicates the manufacturing process and disadvantageously increases costs. is there. In addition, since the surface on which the plated metal is formed is restricted to the surface where the end portion of the internal electrode and the anchor tab are exposed, the external electrode cannot be formed at an arbitrary portion.

On the other hand, Patent Documents 2, 3 and 4 disclose a method of forming a coil pattern by forming an electrode on the entire surface of a ferrite constituting an inductor and then burning the electrode by irradiating a laser. At that time, it is disclosed that the heat of the laser spreads not only to the electrode but also to the ferrite underneath it, and some properties of the ferrite change to make it conductive or low resistance (Patent Document 2). Paragraph 0005, Paragraph 0004 of Patent Document 3, Paragraph 0005 of Patent Document 4). However, these documents only disclose that the electrodes are burned out by irradiating a laser, and further, it is described that the heat of the laser adversely affects the characteristics as an inductor.

Japanese Patent Laid-Open No. 2004-40084 JP 2000-223342 A JP 2000-243629 A Japanese Patent Laid-Open No. 11-176585

Accordingly, an object of the present invention is to propose a manufacturing method capable of forming an electrode on an arbitrary portion of the surface of a sintered ceramic body by a simple method and a ceramic electronic component manufactured by the method.

In order to achieve the above object, the present invention provides a method for manufacturing a ceramic electronic component comprising the following steps.
A: a step of preparing a sintered ceramic body containing a metal oxide,
B: forming a low resistance portion in which a part of the ceramic body is reduced in resistance by locally heating an electrode formation region on the surface of the ceramic body;
C: A step of depositing a plating metal serving as an electrode on the low resistance portion by plating the ceramic body, and growing the plating metal so as to spread over the entire electrode formation region.

In the present invention, the electrode forming region on the surface of the sintered ceramic body is locally heated to reduce the resistance or conductor of the heated portion, and the ceramic body is plated to reduce the resistance. It pays attention to the point which can use a part as a deposition start point of plating metal. The low resistance portion (or conductor portion) refers to a portion in which the metal oxide constituting the ceramic body is altered by local heating and the resistance value is lower than that of the metal oxide. When the locally heated ceramic body is plated, the plated metal first deposits on the low-resistance part, and the plated metal grows rapidly with the deposited plated metal as the core, so that the electrode covering the entire electrode formation region can be efficiently formed. Can be formed. Therefore, a complicated process such as application and baking of a conductive paste as in the prior art is not required, and the electrode forming process is simplified. Furthermore, since it is not necessary to expose a plurality of internal electrodes and anchor tabs close to the end face of the ceramic body as in Patent Document 1, there is no restriction on the shape of the electrodes, and the manufacturing process is simplified and the cost is reduced. Can be reduced.

The low resistance portion may include a reduction layer in which a part of the metal oxide contained in the ceramic body is reduced. When a part of the metal oxide is reduced, the metal oxide becomes a conductor or a semiconductor, and the plated metal is easily deposited. Furthermore, it is good also as a structure by which one part or all part of the surface layer of a reduction | restoration layer is covered with the reoxidation layer. In the case where the reoxidation layer is formed, there is an effect that it is possible to suppress the oxidation of the reduction layer in the lower layer and to suppress the temporal change of the reoxidation layer itself. Further, since the reoxidized layer is a kind of semiconductor and has a resistance value lower than that of the metal oxide that is an insulator, the plating metal is likely to be deposited on the reoxidized layer. In addition, since the reoxidized layer is formed as a thin film of the order of nm, for example, a part of the reoxidized layer is peeled off when the media ball used for electroplating is reoxidized, or the plating solution is eroded in the reoxidized layer. In addition, there is a possibility that plating is provided on the reduction layer under the reoxidation layer.

The electrode of the present invention is not limited to an external electrode as long as it is an electrode formed on the surface of the ceramic body, and may be any electrode. For example, a coiled electrode or a wiring electrode may be used. As the local heating method, there are various methods such as laser irradiation, electron beam irradiation, or local heating using an image furnace. Of these, laser irradiation is advantageous in that the irradiation position of the laser on the ceramic body can be quickly changed.

In the present invention, since the electrode forming region is only locally heated and plated, an electrode can be formed at an arbitrary portion. For example, in a conventional method using a conductive paste, a deformed electrode, that is, an external electrode (L-shaped in a side view) is formed on both end surfaces and one side surface adjacent thereto, or a plurality of external electrodes are formed on one side surface. However, in the present invention, an external electrode having an arbitrary shape can be easily formed. Since the local heating may be performed only on the surface layer portion of the ceramic body, the characteristics as a ceramic electronic component (for example, an inductor) are not substantially affected.

As a plating method, either electrolytic plating or electroless plating is possible, but an electrolytic plating method is preferable. That is, in the electroplating method, conductivity is required for an object to be plated. Since the low resistance portion formed by the method of the present invention has conductivity, the current density flowing through the low resistance portion during electrolytic plating is higher than that of the other portions, and the plated metal is quickly deposited on the low resistance portion. In the conventional plating method, when it is not desired to perform plating on a part of the ceramic body, it is necessary to previously coat the part with a plating preventing material. In the present invention, the plating electrode spreads rapidly in the electrode formation region with the low resistance portion as a nucleus, whereas the portion other than the electrode formation region is insulative and has no conductive portion as a nucleus. slow. Therefore, the plating metal can be selectively grown in the electrode formation region without coating the plating preventing material. Furthermore, since the plating metal formed on the low resistance portion by electrolytic plating becomes thicker than other portions, there is an advantage that the adhesion strength of the plating electrode to the ceramic body is increased.

The present invention can also be applied to an electronic component having an internal electrode. For example, for a rectangular parallelepiped ceramic body, a low resistance portion is formed by laser irradiation or the like on the surface where the end portion of the internal electrode is exposed, and an external electrode is formed so as to cover the end portion of the internal electrode by plating. Good. An electrode can be formed on an arbitrary surface as long as it can be locally heated such as laser processing. For example, it is possible not to form electrodes on both side surfaces in the width direction. In an electronic component in which external electrodes are not formed on both side surfaces in the width direction, when the electronic component is mounted at a high density, an insulation distance from an electronic component adjacent in the width direction can be secured, and the risk of a short circuit can be reduced. As a result, higher density mounting is possible. Further, when the external electrode is formed only on the bottom surface (bottom surface) of the ceramic body, the external electrode is mounted only on the bottom surface, so that the risk of occurrence of a short circuit with surrounding electronic components can be further reduced.

The present invention can be applied to, for example, a wire-wound coil component. That is, the ceramic body is a ferrite core having a flange portion at both ends and a core portion between the ends. A coil-shaped low resistance portion is formed on the core portion of the ferrite core by laser processing or the like. A low resistance portion having an external electrode shape is formed on the flange portion by laser processing or the like, and the low resistance portion having a coil shape is connected to the low resistance portion having an external electrode shape. It is good also as a structure by which the plating electrode is continuously formed on the low resistance part of a shape. In this case, since both the coil part and the external electrode part can be formed by laser processing or the like, the manufacturing is further simplified. The electrode of the coil portion can be made thicker than the external electrode by adjusting the laser intensity.

Further, the ceramic body is a ferrite core having a flange portion at both ends and a winding core portion therebetween, a wire is wound around the peripheral surface of the winding core portion, and a low resistance is respectively applied to the surface of the flange portion. It is good also as a structure by which the part is formed, the electrode which consists of a plating metal is each formed on the low resistance part of a collar part, and the electrode is connected with the both ends of a wire. In this case, since the winding part is formed of a metal wire, the magnetic efficiency is high, and the external electrode can be a thin electrode according to the present invention. it can.

When a laser is used as a local heating method, the laser concentrates energy in a narrow area, so a part of the ceramic body melts and solidifies, and linear or dotted laser irradiation traces are formed on the surface of the ceramic body. And a low resistance portion is formed in the vicinity of the periphery. The depth and width of the laser irradiation trace and the low resistance portion can be adjusted by the laser irradiation energy (wavelength, output, etc.). Since the plating metal deposited on the low resistance portion adheres along the inner wall of the concave laser irradiation mark, the anchoring effect of the plating metal (electrode) to the ceramic body can be increased.

The electrode formation region may be densely irradiated so that the low resistance portion is present with almost no gap. In this case, since the low resistance portion is also formed continuously, the plating metal is rapidly deposited and grown, and the plating processing time can be shortened. Note that “densely radiate” means that the interval between the laser irradiation spot centers is equal to or narrower than the spread width of the low resistance portion. That is, D ≦ W, where D is the distance between the laser-irradiated spot centers and W is the spot diameter (width of the low-resistance portion).

As described above, when the laser is densely irradiated to the electrode formation region, a large number of shots are required, and processing time is required. Therefore, a plurality of low-resistance parts are dispersedly formed in the electrode formation region by irradiating the electrode formation region with a predetermined distance, and a plating metal deposited on the low-resistance part is grown as a nucleus. The plating process may be continued until the plated metals are connected to each other. Here, “dispersed and irradiated” means that the distance between the laser irradiation spot centers is wider than the spread width of the low resistance portion. That is, D> W, where D is the distance between the centers of laser irradiation spots, and W is the spot diameter (width of the low resistance portion). The advantage of the plating process is that if the plating metal is deposited on a part, the plating metal rapidly grows around the part as a nucleus. Taking advantage of this advantage, after plating metal deposits on a plurality of dispersed low resistance parts, the plating metal grows in areas other than the low resistance part using it as a nucleus, so a uniform electrode over the entire electrode formation area Can be formed. Therefore, a high-quality electrode can be formed without irradiating the laser densely, and the laser processing time can be shortened.

A typical ceramic material that can be reduced in resistance or conductor by irradiation with a laser is ferrite. Ferrite is a ceramic mainly composed of iron oxide, such as spinel ferrite, hexagonal ferrite, and garnet ferrite. When the laser is irradiated to the ferrite, the irradiated portion becomes high temperature, and the surface layer portion of the insulating ferrite changes in quality and becomes conductive. Examples of the ferrite used for the inductor include Ni—Zn ferrite and Ni—Cu—Zn ferrite. In the case of Ni—Zn-based ferrite, it is considered that a part of Fe contained in the ferrite is reduced by laser irradiation, and Ni and / or Zn may also be reduced. In the case of Ni—Cu—Zn based ferrite, Fe and / or Cu contained in the ferrite is considered to be reduced, and Ni and / or Zn may also be reduced.

As described above, according to the present invention, the electrode forming region of the sintered ceramic body is locally heated to form the low resistance portion, and the ceramic body is plated to form the low resistance portion. Since the plating metal is deposited and this plating electrode is grown over the entire electrode formation region, the electrode can be formed by a simple method. In addition, since an electrode can be formed at an arbitrary portion as long as it can be locally heated, an electrode having an arbitrary shape can be easily formed.

1 is a perspective view of a first embodiment of a ceramic electronic component according to the present invention. It is a disassembled perspective view of the ceramic electronic component shown in FIG. It is a perspective view which shows a mode that a laser is irradiated to an external electrode formation area. It is sectional drawing which shows the formation process of an external electrode. It is an expanded sectional view of an example of a low resistance part. It is a figure which shows the example of mounting of the ceramic electronic component which concerns on this invention. It is sectional drawing which shows the other example of the formation process of an external electrode. It is a perspective view which shows some examples of the ceramic electronic component which concerns on this invention. It is a figure which shows the winding type inductor which is an example of the ceramic electronic component which concerns on this invention. It is a figure which shows the other example of the winding type inductor which concerns on this invention. It is a figure which shows the vertical winding type coil component which is an example of the ceramic electronic component which concerns on this invention. It is a figure which shows the multi-terminal type electronic component which is an example of the ceramic electronic component which concerns on this invention.

FIG. 1 shows a chip inductor 1 which is an example of a ceramic electronic component according to the present invention. The inductor 1 includes a sintered ceramic body 10, and external electrodes 30 and 31 are formed at both ends in the length direction of the ceramic body 10. The shape of the inductor 1 of this embodiment is a rectangular parallelepiped having a longer dimension in the X-axis direction than that in the Y-axis and Z-axis directions, as shown in FIG.

As shown in FIG. 2, the ceramic body 10 is obtained, for example, by laminating and sintering insulator layers 12 a to 12 e mainly composed of Ni—Zn-based ferrite or Ni—Cu—Zn-based ferrite. The insulator layers 12a to 12e are sequentially stacked in the vertical direction (Z-axis direction). Coil conductors 21 to 23 constituting the internal electrode 20 are formed on the intermediate insulator layers 12b to 12d excluding the insulator layers 12a and 12e at the upper and lower ends, respectively. These three coil conductors 21 to 23 are connected to each other by via conductors 24 and 25, and are formed in a spiral shape as a whole. The coil conductors 21 to 23 and the via conductors 24 and 25 are made of a conductive material such as Au, Ag, Pd, Cu, or Ni. One end portion (leading portion) 21 a of the coil conductor 21 is exposed on one end surface in the X-axis direction of the ceramic body 10, and one end portion (leading portion) 23 a of the coil conductor 23 is exposed in the X-axis direction of the ceramic body 10. It is exposed on the other end surface. In this embodiment, the coil conductors 21 to 23 form a coil for two turns. However, the number of turns is arbitrary, and the shape of the coil conductor and the number of insulating layers are also arbitrarily selected. it can. Further, the number of the insulator layers 12a and 12e having no coil conductor is also arbitrary.

As shown in FIG. 1, the external electrodes 30 and 31 are formed in an L shape in side view so as to cover both end faces in the X-axis direction of the ceramic body 10 and a part of the top surface (bottom surface when mounted). That is, when the ceramic body 10 is viewed from the Y direction, the external electrodes 30 and 31 are each formed in an L shape. The external electrode 30 is connected to the lead portion 23 a of the coil conductor 23, and the external electrode 31 is connected to the lead portion 21 a of the coil conductor 21. The external electrodes 30 and 31 are formed by plating as will be described later, and materials such as Cu, Au, Ag, Pd, Ni, and Sn are used. In addition, the external electrodes 30 and 31 themselves may be composed of multilayer plated metals.

FIG. 3 shows a state in which the external electrode forming regions S1 and S2 are irradiated with the laser L before the formation of the external electrodes 30 and 31 on the ceramic body 10. FIG. 3A shows an example of scanning along the Y-axis direction while continuously irradiating the laser L (or an example in which the ceramic body 10 is moved in the Y-axis direction). The scanning direction is arbitrary and may be the X-axis direction (or Z-axis direction), zigzag shape, or circular shape. By irradiation with the laser L, a large number of linear laser irradiation marks 40 are formed on the surface of the ceramic body 10. 3A shows an example in which the linear laser irradiation marks 40 are formed at intervals in the X-axis direction, but the laser irradiation marks 40 may be densely formed so as to overlap each other. Good. FIG. 3B shows an example in which the laser L is irradiated in the form of dots. In this case, a large number of dot-like laser irradiation marks 41 are formed on the surface of the ceramic body 10 in a dispersed manner. FIG. 3C shows an example in which the laser L is irradiated in a broken line shape. In this case, a large number of broken laser irradiation marks 42 are formed on the surface of the ceramic body 10 in a dispersed manner. In any case, it is desirable to irradiate the laser L evenly over the entire area of the external electrode formation regions S1 and S2.

FIG. 4 shows an outline of an example of the formation process of the external electrode. In particular, the case where the laser L is irradiated linearly at a predetermined interval to the external electrode formation region is shown.

In FIG. 4A, first, a laser is irradiated on the external electrode forming region on the surface of the ceramic body 10, thereby forming a laser irradiation mark 40 having a V-shaped or U-shaped cross section on the surface of the ceramic body 10. Shows the state. Although FIG. 4A shows an example in which the laser L is focused at one point, the spot irradiated with the laser L may actually have a certain area. This laser irradiation mark 40 is a mark in which the surface layer portion of the ceramic body 10 is melted and solidified by laser irradiation. Since the center portion of the spot has the highest energy, the ceramic material in that portion is easily altered, and the cross section of the laser irradiation mark 40 is substantially V-shaped or substantially U-shaped. The insulating material (ferrite) constituting the ceramic body is altered around the periphery of the laser irradiation mark 40 including the inner wall surface, and a conductor portion or a low resistance portion 43 having a resistance value lower than that of the insulating material is formed. Specifically, when the ceramic body 10 is Ni—Zn-based ferrite, it is considered that a part of Fe contained in the ferrite is reduced by laser irradiation, and Ni and / or Zn is also reduced. There is a possibility. In the case of Ni—Cu—Zn based ferrite, Fe and / or Cu contained in the ferrite is considered to be reduced, and Ni and / or Zn may also be reduced. The depth and width of the low resistance portion 43 can be varied depending on the irradiation energy and irradiation range of the laser.

FIG. 4B shows a state in which a plurality of laser irradiation marks 40 are formed at intervals D in the external electrode formation region by repeating laser irradiation. In this example, since the interval D between the laser irradiation spot centers is wider than the spread width (for example, the average value of the diameter) W of the low resistance portion 43, there is an insulating region 44 other than the low resistance portion between the laser irradiation marks 40. Existing. The region 44 is a region where the original insulating material constituting the ceramic body is exposed without being altered.

FIG. 4C shows an initial state in which the ceramic body 10 in which the low resistance portion 43 is formed by laser irradiation as described above is immersed in a plating solution and electrolytic plating is performed. Since the current density in the conductive low resistance portion 43 is higher than that in other portions, the plating metal 45 a is deposited only on the surface of the low resistance portion 43, and has not yet deposited on the insulating region 44. That is, a continuous external electrode is not formed at this stage.

FIG. 4D shows the final state after electrolytic plating. By continuing the plating process, the plated metal 45 a deposited on the low resistance portion 43 grows to the periphery as a nucleus and spreads over the insulating region 44 adjacent to the low resistance portion 43. A continuous external electrode 45 can be formed by continuing the plating process until adjacent plating metals 45a are connected to each other. Compared to the growth rate of the plating metal in the external electrode formation region irradiated with the laser, the growth rate of the plating metal in the region other than the external electrode formation region is slow, so external electrode formation is possible without strictly controlling the plating time. Plating metal can be selectively grown in the region. By controlling the plating processing time, voltage or current, it is possible to control the formation time and thickness of the external electrode. Furthermore, an external electrode having a multilayer structure can be formed by performing an additional plating process on the external electrode 45 formed by the first plating process. In this case, since the external electrode 45 as the base has already been formed, the additional plating processing time can be shortened.

-Experimental example-
Hereinafter, experimental examples in which external electrodes are actually formed will be described.
(1) A sintered ceramic body made of Ni—Cu—Zn ferrite was irradiated while reciprocating a laser. The processing conditions are as follows, but the wavelength may be any range of 532 nm to 10620 nm, for example. The irradiation interval means the distance between the spot center of the forward path and the return path when the laser is reciprocally scanned.

上記のような条件でめっき処理を行った結果、セラミック素体の表面に平均厚さ２０μｍの良好なＣｕ外部電極を形成することができた。なお、同様の結果は、Ｎｉ−Ｚｎ系フェライトを用いた場合でも得られた。また、めっき液としては、ピロリン酸銅めっき液以外に、硫酸銅めっき液、シアン化銅めっき液なども使用可能である。 (2) Electroplating was performed on the ceramic body after laser irradiation under the following conditions. Specifically, barrel plating was used.

As a result of performing the plating process under the above conditions, a good Cu external electrode having an average thickness of 20 μm could be formed on the surface of the ceramic body. Similar results were obtained even when Ni—Zn ferrite was used. In addition to the copper pyrophosphate plating solution, a copper sulfate plating solution, a copper cyanide plating solution, and the like can be used as the plating solution.

-Evaluation-
K-edge of Fe, Cu, Zn using XPS (X-ray photoelectron spectroscopy) and conversion electron yield method for samples irradiated with laser to Ni-Cu-Zn-based ferrite and samples not irradiated with laser The valence of Fe, Cu, Zn on the sample surface was evaluated by XAFS (X-ray absorption fine structure). As a result of XPS, the metal component could not be detected in the surface layer portion of the sample irradiated with the laser, and the metal component could be detected in the lower layer. As a result of XAFS, the Cu metal component could be detected in the surface layer portion of the sample irradiated with the laser. On the other hand, as a result of XAFS, the Fe metal component could not be detected in the surface layer portion of the sample irradiated with the laser, but the Fe semiconductor component and the insulator component could be detected. It was also found that the lower layer had a larger ratio of Fe ₂ + to Fe ₃ + than that of the entire ceramic body. From the above, it is estimated that the metal oxide contained in ferrite was decomposed by the heat from laser processing, the metal element of ferrite was reduced in the lower layer of the ceramic body, and the surface layer portion of the ceramic body was reoxidized by residual heat. The

FIG. 5 shows an example of the cross-sectional structure of the low resistance portion 43 formed as described above. A reduction layer 43a is formed in the lower layer, and the surface layer is a reoxidation layer 43b made of a semiconductor and / or insulator component. Covered. These reduced layer and reoxidized layer constitute a low resistance portion. The laser irradiation is not limited to the atmosphere, may be irradiated with a laser beam in a vacuum and N ₂ atmosphere, to a case of performing laser irradiation in a vacuum and N ₂ atmosphere, be re-oxidized layer is not formed There is sex.

When the above-mentioned reoxidized layer is formed, the following effects can be considered. In other words, Fe ₃ O ₄ formed as a reoxidation layer has the property that reoxidation at room temperature is difficult to proceed, and it is possible to suppress the oxidation of the lower reduction layer and to suppress the temporal change of the reoxidation layer itself. There is also. The reoxidized layer is a kind of semiconductor and has a resistance value lower than that of ferrite as an insulator. Therefore, the plating metal tends to be deposited on the reoxidized layer.

In the present embodiment, the external electrodes 30 and 31 are formed in an L shape in a side view (when the ceramic body 10 is viewed from the Y direction). That is, the external electrodes 30 and 31 are formed only on both end surfaces and the bottom surface (when mounted) of the inductor 1 and are not formed on the top surface (when mounted) and both side surfaces in the Y direction. Therefore, as shown in FIG. 6A, the risk of occurrence of a short circuit can be reduced even when another electronic component 2 or a conductor is present close to the inductor 1 in the mounted state. Furthermore, even when another electronic component 3 is mounted adjacent to the Y direction of the inductor 1 as shown in FIG. 6B, the external electrodes 30 and 31 are formed on both side surfaces of the inductor 1 in the Y direction. Since it is not carried out, while being able to ensure the insulation distance with the adjacent electronic component 3, the distance of the solder apply | coated to an external electrode can also be ensured. Therefore, the risk of a short circuit with the adjacent electronic component 3 can be reduced. As a result, in the case of the inductor 1 having the L-shaped external electrode, further high-density mounting becomes possible. Furthermore, there is an effect of reducing stray capacitance as compared with the conventional external electrode.

FIG. 7 shows another example of the formation process of the external electrodes 30 and 31, and particularly shows a case where the laser L is irradiated densely to the external electrode formation region. “Dense irradiation” means that the distance D between the laser irradiation spot centers is equal to or narrower than the spread width W (for example, the average value of the diameter) W of the low resistance portion 43. This indicates a state where the low resistance portions 43 formed on the lower side are connected to each other (see FIG. 7B). However, it is not necessary that all the low resistance portions 43 are connected. Therefore, almost the entire region of the external electrode formation region of the ceramic body 10 is covered with the low resistance portion 43.

In this case, as shown in FIG. 7C, the plating metal 45a is deposited on the surface of the low resistance portion 43 in a short time from the start of the plating process, but these plating electrodes 45a are almost close to each other. Adjacent plating electrodes 45a are quickly connected to each other. Therefore, the continuous external electrode 45 can be formed in a shorter time than the case of FIG.

As shown in FIG. 7, when the external electrode forming region is irradiated with the laser L densely, the laser irradiation marks 40 are also formed densely, so that the surface of the ceramic body 10 is scraped. Since the plated metal 45 is formed on the surface thereof, it is possible to make the surface of the external electrode substantially the same as or lower than the surface of the ceramic body 10. Therefore, coupled with the fact that the thickness of the external electrode itself is small, the amount of protrusion of the external electrode can be suppressed, and a smaller chip component can be realized.

FIG. 8 shows various forms of external electrodes formed using the present invention. FIG. 8A shows a case in which U-shaped external electrodes 30 and 31 are formed at both ends of the ceramic body 10. As in the embodiment of FIG. 1, the lead portions 21 a and 23 a (21 a not shown) of the internal electrodes are exposed at both end faces in the X direction of the ceramic body 10 and are connected to the external electrodes 30 and 31. In this example, external electrodes 30 and 31 are formed on both end surfaces in the X direction and part of the upper and lower surfaces (both side surfaces in the Z direction) of the ceramic body 10, and external electrodes are formed on both side surfaces in the Y direction. Not formed. Therefore, the electronic component 1 can be mounted with high density adjacent to the Y direction.

FIG. 8B shows the case where the external electrodes 30 and 31 are formed only at both ends of the upper surface (bottom surface when mounted) of the ceramic body 10. External electrodes are not formed on the other surface. In this case, the end portions 21a and 23a of the internal electrodes are not exposed at both end surfaces of the ceramic body 10 in the X direction, and are exposed only on the upper surface in parallel with the X direction. The external electrodes 30 and 31 are connected to the end portions 23a and 21a of the internal electrodes, respectively. In this case, the insulator layers constituting the ceramic body 10 are laminated in the Y direction instead of the Z direction. Since the external electrode is formed only on the bottom surface of the ceramic body 10, an electronic component suitable for high-density mounting can be realized.

FIG. 8C shows a total of four external electrodes 30 to 33 formed at both ends in the X direction on the upper surface (bottom surface when mounted) of the ceramic body 10. Also in this case, the end portions (not shown) of the internal electrodes are not exposed at both end surfaces of the ceramic body 10 in the X direction, but are exposed only at the upper surface on which the external electrodes 30 to 33 are formed. As described above, the external electrode using the method of the present invention is not limited as long as it can be subjected to laser processing and plating treatment, and can be formed in any part.

FIG. 9 shows an example in which the present invention is applied to the formation of an electrode of a wire-wound inductor. The ceramic body 50 is a core having flange portions 51 and 52 at both ends and a core portion 53 therebetween. As the core material, Ni—Zn ferrite, Ni—Cu—Zn ferrite, or the like can be used. Low resistance portions are formed by laser processing in the external electrode formation regions on the upper surfaces and end surfaces of the flange portions 51 and 52 of the core 50, and external electrodes 54 and 55 are formed thereon by plating. A coil-shaped low resistance portion is formed on the peripheral surface of the core portion 53 by laser processing, and a coil electrode 56 is formed thereon by plating. Since both ends of the coil-shaped low resistance portion are laser processed so as to be continuous with the low resistance portion of the external electrode formation region, both ends 56a and 56b of the coil electrode 56 are connected to the external electrodes 54 and 55, respectively, by plating. The

In this embodiment, it is possible to continuously form a coil-like low resistance portion and a low resistance portion for external electrodes by laser processing. As the laser processing, for example, a method of fixing the laser position and rotating and moving the core 50 in the axial direction can be used. Since the coil electrode 56 and the external electrodes 54 and 55 can be formed simultaneously by plating, the inductor manufacturing process can be made more efficient and the manufacturing cost can be reduced. In addition, it can also be set as a multilayered structure by performing the plating process to the coil electrode 56 and the external electrodes 54 and 55 several times. In this embodiment, the coil electrode 56 and the external electrodes 54 and 55 are formed by plating. However, in the wound inductor (ferrite core) in which the wire is wound around the winding core, the external connected to the wire Only the electrodes can be formed by plating.

As described above, when the coil electrode 56 and the external electrodes 54 and 55 are formed by the same laser processing and plating, the electrodes 56, 54, and 55 may have a substantially constant thickness. In particular, when it is desired to increase the magnetic flux generated by the coil electrode 56, it is desirable to make the thickness of the coil electrode 56 larger than the thickness of the external electrodes 54 and 55. In that case, for example, the laser intensity of the laser applied to the core 53 may be higher than the laser intensity of the laser applied to the external electrode region, or the laser applied to the core 53 and the external electrode You may change the irradiation system (for example, intermittent irradiation and continuous irradiation, expansion / contraction of an irradiation range, etc.) with the laser irradiated to an area | region. By increasing the laser intensity, the resistance value of the coiled low resistance portion becomes lower than the resistance value of the low resistance portion of the external electrode forming region, or the depth of the coiled low resistance portion is lower than that of the external electrode forming region. It becomes larger than the depth of the low resistance part. Thereby, the thickness of the electrode 56 formed in the coil-like low resistance portion by the plating process can be made thicker than the thickness of the electrodes 54 and 55 formed in the low resistance portion of the external electrode formation region.

FIG. 10 shows another application example of the wound inductor. Parts that are the same as or corresponding to those in FIG. Low resistance portions are formed by laser processing in the external electrode forming regions on the upper surface, outer surface, and lower surface of the flange portions 51 and 52 of the core 50, and the external electrodes 54 and 55 are formed thereon by plating. Therefore, in this embodiment, U-shaped external electrodes 54 and 55 are formed as a whole. A wire 57 is wound around the peripheral surface of the core portion 53, and both ends 57a and 57b are connected to portions of external electrodes 54 and 55 formed on the upper surfaces of the flange portions 51 and 52, respectively. The portions of the external electrodes 54 and 55 formed on the lower surfaces of the flange portions 51 and 52 are used as mounting electrodes. The shape of the external electrodes 54 and 55 is not limited to the U-shape, and may be formed only on the upper surfaces (connection surfaces of the wires 57) of the flange portions 51 and 52, for example.

In this embodiment, since the outer electrodes 54 and 55 can be formed thinner than the wire 57, there is an effect of suppressing eddy current loss. In other words, a magnetic flux generated by the wire 57 (shown by a broken line arrow in FIG. 10) is linked to the external electrodes 54 and 55 to cause a loss due to an eddy current. Is proportional to the square of the thickness. Since the external electrodes 54 and 55 formed by the method of the present invention can be formed thinner than a general external electrode, eddy current loss can be suppressed. Further, if the wire 57 is used as the winding, the generated magnetic flux density increases, so that an inductor having a high Q value can be obtained.

FIG. 11 shows an example in which the present invention is applied to a vertically wound type coil component (inductor). The ceramic body 60 in this case is a ferrite core having flange portions 61 and 62 at both ends and a core portion 63 therebetween. A low resistance portion is formed by laser processing or the like in the external electrode formation region on the upper surface of one flange portion 61 of the core 60, and external electrodes 64 and 65 are formed thereon by plating. Further, a coated wire (not shown) is wound around the peripheral surface of the core part 63, and both ends thereof are connected to the external electrodes 64 and 65, respectively. 9 and 10 show an example in which two external electrodes 64 and 65 are formed, but when two wires are used, four external electrodes are formed on the flange 61. Also good.

FIG. 12 shows an example in which the present invention is applied to a multi-terminal electronic component. The electronic component main body 70 is formed of a ceramic body, and a plurality of (here, six) external electrodes 71 to 76 are formed on both side surfaces in the longitudinal direction. A part of the external electrodes 71 to 76 may extend to the upper surface or the lower surface of the ceramic body 70. The external electrodes 71 to 76 are connected to an internal electrode of the ceramic body 70 or a circuit portion formed on the outer surface. The external electrodes 71 to 76 in this case are also formed by local heating such as laser processing and subsequent plating.

Although the present invention shows an example applied to the formation of an external electrode of a laminated inductor and an electrode of a wound inductor (ferrite core), the present invention is not limited to this. The ceramic electronic component targeted by the present invention is not limited to an inductor, but can be applied to any electronic component that uses a ceramic body that is altered by laser irradiation and has a low resistance portion that is a deposition starting point of a plating electrode. Is possible. That is, the material of the ceramic body is not limited to ferrite. Furthermore, the structure of the electronic component is not limited to a structure having an internal electrode or a structure in which a plurality of insulating layers are stacked. Although the example using electrolytic plating was shown as the plating method, electroless plating may be used.

In the above embodiment, laser irradiation is used as a local heating method. However, irradiation with an electron beam, heating using an image furnace, or the like is also applicable. In either case, the energy of the heat source can be collected and the external electrode formation region of the ceramic body can be locally heated, so that the electrical characteristics of other regions are not impaired.

In the present invention, one laser beam may be dispersed and a plurality of locations may be irradiated with the laser beam at the same time.

Furthermore, in the present invention, the laser irradiation range may be widened by shifting the focus of the laser as compared with the case where the laser is in focus.

The present invention is not limited to the case where the lowermost layer of the plating metal is grown so as to spread over the entire electrode formation region when the plating metal is formed in a plurality of layers. The lowermost layer of the plating metal may be grown so as to spread over a part of the electrode formation region, and the upper layer of the plating metal may be grown so as to spread over the entire electrode formation region.

DESCRIPTION OF SYMBOLS 1 Ceramic electronic component 10 Ceramic body 20 Internal electrode 21-23 Coil conductor 21a, 23a One end part (drawing part)
30, 31 External electrode 40 Laser irradiation mark 43 Low resistance portion 44 Insulating region 45a Plating metal 45 External electrode L Laser

Claims (18)

A method for producing a ceramic electronic component comprising the following steps;
A: preparing a sintered ceramic body containing a metal oxide;
B: A step of forming a low resistance portion in which a part of the ceramic body is reduced in resistance by locally heating an electrode forming region on the surface of the ceramic body;
C: A step of depositing a plating metal serving as an electrode on the low resistance portion by plating the ceramic body, and growing the plating metal so as to spread over the entire electrode formation region. The method for manufacturing a ceramic electronic component according to claim 1, wherein the low resistance portion includes a reduction layer in which a part of the metal oxide included in the ceramic body is reduced. The method for manufacturing a ceramic electronic component according to claim 2, wherein a surface layer of the reduction layer is covered with a reoxidation layer. 4. The method of manufacturing a ceramic electronic component according to claim 1, wherein the method of locally heating is any one of laser irradiation, electron beam irradiation, and local heating by an image furnace. By irradiating a plurality of locations with a laser at a predetermined distance to the electrode formation region, a plurality of the low resistance portions are dispersedly formed in the electrode formation region,
Growing the plating metal with the plating metal deposited on the low resistance part as a nucleus, and continuing the plating process until the plating metals are connected to each other;
The method of manufacturing a ceramic electronic component according to claim 4. By irradiating the electrode formation region densely with a laser, the continuous low resistance portion is formed in the electrode formation region,
Growing the plating metal deposited on the low resistance portion as a nucleus, and continuing the plating treatment until the plating metal spreads over the entire electrode formation region,
The method of manufacturing a ceramic electronic component according to claim 4. The method for manufacturing a ceramic electronic component according to claim 1, wherein the plating treatment uses an electrolytic plating method. The method of manufacturing a ceramic electronic component according to claim 1, wherein the ceramic body is ferrite. The ceramic body is Ni-Zn based ferrite,
The low resistance portion is formed by reducing a part of Fe contained in the ferrite.
A method for manufacturing a ceramic electronic component according to claim 8. The ceramic body is Ni-Cu-Zn based ferrite,
The low resistance portion is formed by reducing at least one of Fe and Cu contained in the ferrite.
A method for manufacturing a ceramic electronic component according to claim 8. A sintered ceramic body containing a metal oxide;
A low resistance portion formed on the surface of the ceramic body, and a part of the metal oxide is altered to reduce the resistance;
And an electrode made of a plated metal formed on the low resistance portion. The ceramic electronic component according to claim 11, wherein the low resistance portion includes a reduction layer obtained by reducing a part of a metal oxide contained in the ceramic body. The ceramic electronic component according to claim 12, wherein a surface layer of the reduction layer is covered with a reoxidation layer. The ceramic electronic component according to claim 11, wherein the ceramic body is ferrite. The ceramic body has a rectangular parallelepiped shape,
An internal electrode is provided inside the ceramic body,
The end of the internal electrode is exposed on any surface of the ceramic body,
The low resistance portion is formed on the surface where the end portion of the internal electrode is exposed,
The ceramic electronic component according to claim 11, wherein an external electrode, which is the electrode, is formed on the low resistance portion so as to cover an end portion of the internal electrode. The ceramic body has a flange at both ends, and a ferrite core having a winding core in between.
The coil-shaped low resistance portion is formed on the peripheral surface of the core portion,
A low resistance portion connected to the coiled low resistance portion is formed on the surface of the flange portion,
The ceramic electronic component according to any one of claims 11 to 14, wherein an electrode made of the plating metal is continuously formed on the low resistance portion of the flange portion and the coil-shaped low resistance portion. The ceramic electronic component according to claim 16, wherein a film thickness of the electrode formed on the coiled low resistance portion is larger than a film thickness of the electrode formed on the low resistance portion of the flange portion. The ceramic body has a flange at both ends, and a ferrite core having a winding core in between.
A wire is wound around the circumferential surface of the core portion,
The low resistance part is formed on the surface of the flange part,
An electrode made of the plated metal is formed on the low resistance portion of the flange portion,
The ceramic electronic component according to claim 11, wherein the electrode is connected to both ends of the wire.

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