JP4604553B2 - Multilayer ceramic electronic component and manufacturing method thereof - Google Patents

Description

  The present invention relates to a multilayer ceramic electronic component, in particular, a multilayer ceramic electronic component such as a three-terminal multilayer capacitor or a multilayer LC component, and a method for manufacturing the same.

  In general, in the manufacture of multilayer ceramic electronic components such as three-terminal multilayer capacitors, a mother ceramic multilayer block in which a large number of ceramic multilayer bodies are assembled is formed, and then this mother ceramic multilayer block is arranged as an inner conductor such as a capacitor conductor. And cut out individual ceramic laminates. Then, after the cut ceramic laminate is fired, an external electrode is formed on the surface to obtain a product.

  By the way, the three-terminal multilayer capacitor has a smaller equivalent series inductance than the two-terminal multilayer capacitor, and is therefore suitable as a bypass capacitor that removes high-frequency noise from a power supply line by providing a bypass path, for example. This is because the deterioration of the insertion loss characteristic in the high frequency band can be reduced.

  However, in recent years, noise has been further increased in frequency, and it is necessary to further reduce the equivalent series inductance in order to prevent deterioration of insertion loss characteristics in a high frequency band even in a three-terminal multilayer capacitor. Further, in order to cope with noise having various frequencies and strengths, it is necessary to be able to arbitrarily set the capacitor capacity, so it is necessary to ensure a large capacitor capacity.

  As a countermeasure, for example, a three-terminal multilayer capacitor disclosed in Patent Document 1 is known. As shown in FIG. 10, this three-terminal multilayer capacitor 61 includes a dielectric sheet 62 provided with a large area internal signal conductor 63 on the surface and a dielectric sheet 62 provided with a large area internal ground conductor 64 on the surface. Are stacked alternately, and then outer layer dielectric sheets 62 are stacked on the upper and lower sides thereof. In this way, the internal signal conductor 63 and the internal ground conductor 64 form a capacitor capacity by sandwiching the dielectric sheet 62 therebetween.

  As shown in FIG. 11, external signal electrodes 71 and 72 are formed on the left and right side surfaces of the ceramic laminate 70 formed by laminating the dielectric sheets 62, and on the entire side surfaces on the near side and the back side, External ground electrodes 73 and 74 are formed.

  The three-terminal multilayer capacitor 61 having the above configuration can secure a large capacitor capacity because the facing area between the internal signal conductor 63 and the internal ground conductor 64 can be increased. Moreover, since the external ground electrodes 73 and 74 are formed on the entire front and back side surfaces of the ceramic laminate 70, the internal signal conductor 63 and the internal ground conductor 64 are opposed to each other from the external ground electrodes 73 and 74. The distance to the part can be shortened as a whole, and the equivalent series inductance can be reduced.

However, when the external ground electrodes 73 and 74 are formed on the entire front and back side surfaces of the ceramic laminate 70 as described above, the distance between the external ground electrodes 73 and 74 and the external signal electrodes 71 and 72 is reduced. Problems such as migration and solder bridges occur. Further, if the external signal electrodes 71 and 72 and the external ground electrodes 73 and 74 have a structure without a folded portion, solder wet-up and self-alignment properties are deteriorated, resulting in problems in mountability. Furthermore, the application position shift of the external ground electrodes 73 and 74 also reduces the distance between the external electrodes.
Japanese Patent Laid-Open No. 2003-100552

  SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer ceramic electronic component that is strong in reliability such as migration and maintains a high frequency characteristic while maintaining a sufficient interval between external electrodes, and a method for manufacturing the same.

In order to achieve the above object, a multilayer ceramic electronic component according to the present invention is provided on a surface of a rectangular ceramic laminate formed by laminating a plurality of internal conductors and a plurality of ceramic layers, and on the surface of the ceramic laminate. And an external electrode electrically connected to the lead portion of the internal conductor led to the side surface of the ceramic laminate, and the external electrode extends to the upper surface, the side surface, and the lower surface of the ceramic laminate. In addition, the strips connected to the respective portions of the lead portions of the inner conductor led out to the side surface of the ceramic laminate so as to cover the central portion of the lead portion in a strip shape and not to cover other portions than the central portion . A thick film conductor, and a portion of the internal conductor that extends to the side surface of the ceramic laminate and covers the thick film conductor, other than the portion covered with the thick film conductor, and the internal conductor While covering the gap between the lead portions cross directly, characterized in that comprising a plating film provided on a side surface of the ceramic laminate.

  With the above configuration, since the strip-shaped thick film conductor extends on the upper surface and the lower surface of the ceramic laminate, the external electrode has a structure with a folded portion. In addition, since each of the lead portions of the inner conductor led out to the side surface of the ceramic laminate is electrically connected by the strip-shaped thick film conductor, the plating film covering all of the strip-shaped thick film conductor and the lead portion of the inner conductor is ceramic. It is formed on the side surface of the laminate with a large area and high positional accuracy.

Further, the method for manufacturing a multilayer ceramic electronic component according to the present invention includes a step of laminating a plurality of internal conductors and a plurality of ceramic layers to form a rectangular ceramic laminate, an upper surface, a side surface of the ceramic laminate, and Connected to each of the lead portions of the inner conductor extended to the lower surface and led to the side surface of the ceramic laminate so as to cover the central portion of the lead portion in a band shape and not to cover other portions than the central portion. Forming a strip-shaped thick film conductor, and a lead-out portion of the inner conductor led out to a side surface of the thick film conductor and the ceramic laminate by electrolytic plating, other than a portion covered with the thick film conductor And the gap between the lead portions of the inner conductor is directly covered with the plating film by the growth of the plating film deposited on the lead portion of the inner conductor. Tsu forming a plated film on the side surface of the click laminate characterized by comprising a step of forming an external electrode composed of the plating film and the thick film conductor.

  By the above method, a multilayer ceramic electronic component that is strong in reliability such as migration and that maintains a high frequency characteristic and sufficiently secures an interval between external electrodes is easily manufactured.

According to the present invention, the external electrode extends on the upper surface, the side surface, and the lower surface of the ceramic laminate, and the central portion of the lead portion is provided on each part of the lead portion of the internal conductor led to the side surface of the ceramic laminate. This is a strip-shaped thick film conductor connected so as to cover the portion in a strip shape and not cover the other than the central portion , and an inner conductor lead-out portion that covers the thick film conductor and is led out to the side surface of the ceramic laminate. And a plating film provided on the side surface of the ceramic laminate in a state in which a portion other than the portion covered with the thick film conductor and a gap between the lead portions of the inner conductor are directly covered. Accordingly, the external electrode having a structure with the folded portion can be formed on the side surface of the ceramic laminate with a large area and with high positional accuracy. As a result, it is possible to obtain a multilayer ceramic electronic component that is strong in reliability such as migration and that maintains a high frequency characteristic and sufficiently secures an interval between external electrodes.

  Embodiments of a multilayer ceramic electronic component and a method for manufacturing the same according to the present invention will be described below with reference to the accompanying drawings. In the following examples, only one ceramic laminate is shown, but actually, after forming a mother ceramic laminate block in which a large number of ceramic laminates are assembled, It cuts according to arrangement | positioning of a conductor, and cuts out each ceramic laminated body.

[First embodiment, FIGS. 1 to 6]
As shown in FIG. 1, a three-terminal multilayer capacitor 1 includes a dielectric ceramic green sheet 12 having a large area internal signal conductor 2 on the surface and a dielectric ceramic having a large area internal ground conductor 3 on the surface. An arbitrary number of green sheets 12 are alternately stacked, and a protective dielectric ceramic green sheet 13 is further stacked on the top and bottom thereof. As described above, the internal signal conductor 2 and the internal ground conductor 3 form a capacitor capacitance by sandwiching the dielectric ceramic green sheet 12 therebetween.

The dielectric ceramic green sheets 12 and 13 are formed into a sheet shape (thickness: 2 to 6 μm) by a method such as a doctor blade method obtained by kneading ceramic powder mainly composed of BaTiO ₃ together with a binder, for example. Is. The internal signal conductor 2 and the internal ground conductor 3 are each formed on the dielectric ceramic green sheet 12 by a method such as screen printing. These conductors 2 and 3 are made of Ni, Ag, Pd, Cu, Au, alloys thereof, or the like. The thickness of the conductors 2 and 3 is about 0.5 to 1.5 μm.

  One lead portion 2 a of the internal signal conductor 2 is exposed on the front side of the sheet 12, and the other lead portion 2 a is exposed on the back side of the sheet 12. One lead portion 3 a of the internal ground conductor 3 is exposed on the left side of the sheet 12, and the other lead portion 3 a is exposed on the right side of the sheet 12.

  After the dielectric ceramic green sheets 12 and 13 having the above-mentioned configuration are laminated, they are pressed and integrally fired to obtain a laminated body 20 having a rectangular parallelepiped shape as shown in FIG. On the four side surfaces of the multilayer body 20, the lead portions 2 a and 3 a of the internal ground conductor 2 and the internal ground conductor 3 are exposed. The distance between the lead portions 2a of the internal signal conductor 2 and the distance between the lead portions 3a of the internal ground conductor 3 are set to be not more than twice the thickness of the plating film 46 of the external electrodes 21 to 24 described later.

  Next, as shown in FIG. 3, the laminate 20 is placed on a plate 40 provided with slit-like openings 41 in a laid state, and a conductive paste 45 is applied to the side surface of the laminate 20. That is, the plate 40 provided with the slit-shaped opening 41 is arranged on the upper surface of the metal tank in which the conductive paste 45 mainly containing Cu or the like is stored, and the conductive paste 45 is pushed up from below to open the opening. From 41, conductive paste 45 is extruded onto plate 40. Next, the side surface of the laminated body 20 is dipped into the extruded conductive paste so that the conductive paste 45 is applied to the side surface of the laminated body 20, and then dried, sintered, and fixed.

  Thus, as shown in FIG. 4, each of the lead portions 2 a and 3 a of the internal signal conductor 2 and the internal ground conductor 3 extending to the top surface, the side surface, and the bottom surface of the multilayer body 20 and leading to the side surface of the multilayer body 20. A strip-shaped thick film conductor 45 (having a thickness of 20 to 80 μm) is formed so as to be electrically connected to. Here, the thick film conductor 45 connected to the lead portion 2 a of the internal signal conductor 2 covers the whole lead portion 2 a of the internal signal conductor 2. On the other hand, the thick film conductor 45 connected to the lead portion 3 a of the internal ground conductor 3 is disposed at the center of the lead portion 3 a of the internal ground conductor 3 and covers only a part of the lead portion 3 a of the internal ground conductor 3.

  Next, the laminate 20 is put in a plating bath and wet plating (electrolytic plating) is performed to form a Ni and Sn plating film having a thickness of about 2 to 15 μm. At this time, as shown in FIG. 5A, the steel ball 50 functioning as a current-carrying medium in the plating bath is brought into contact with the surface of the thick film conductor 45 to form a plating film 46 on the surface of the thick film conductor 45. .

  Further, since the thick film conductor 45 is electrically connected to the lead portion 3a of the internal ground conductor 3 led out to the side surface of the multilayer body 20, it is covered with the thick film conductor 45 as shown in FIG. The plating film 46 is also deposited on the exposed portion of the undrawn portion 3a. Since the plating film 46 grows to the thickness of the plating film in all directions, it is grown from both sides of the drawing portion 3a by setting the distance d1 between the drawing portions 3a to be not more than twice the thickness d2 of the plating film 46. The plated film 46 thus covered covers the gap between the drawn portions 3a.

  When the thick film conductor 45 is not in an electrical connection between the lead portions 2a and the lead portions 3a, the steel ball 50 comes into contact with the lead portions 2a and 3a as shown in FIG. Since it is difficult, plating does not deposit uniformly on the surfaces of the drawn portions 2a and 3a.

  Thus, as shown in FIG. 6, the external signal electrodes 21 and 22 and the external ground electrodes 23 and 24 composed of the thick film conductor 45 and the plating film 46 are formed on the four side surfaces of the multilayer body 20. The external signal electrode 21 is electrically connected to one lead portion 2 a of the internal signal conductor 2, and the external signal electrode 22 is electrically connected to the other lead portion 2 a of the internal signal conductor 2. The external ground electrode 23 is electrically connected to one lead portion 3 a of the internal ground conductor 3, and the external ground electrode 24 is electrically connected to the other lead portion 3 a of the internal ground conductor 3.

  Here, in the external ground electrodes 23 and 24, the distance d3 between the plating film 46 formed by plating growth on the lead portion 3a of the internal ground conductor 3 and the bottom surface of the multilayer body 20 is determined by the three-terminal multilayer capacitor 1. It is preferable to set it to half or less of the thickness of the solder paste used when mounting on a printed circuit board. This is because if the distance d3 is larger than this, the solder wet-up may be deteriorated during mounting, which affects the high-frequency characteristics. For example, when the thickness of the solder paste is about 50 μm, the interval d3 is set to 25 μm or less.

  The three-terminal multilayer capacitor 1 having the above configuration can secure a large capacitor capacity because the facing area between the internal signal conductor 2 and the internal ground conductor 3 can be increased. In addition, since the strip-shaped thick film conductor 45 extends to the upper surface, the side surface, and the lower surface of the multilayer body 20, the external signal electrodes 21 and 22 and the external ground electrodes 23 and 24 have a structure with a folded portion. Therefore, when mounting the three-terminal multilayer capacitor 1 on a printed circuit board or the like, there is almost no concern that solder wetting or self-alignment will be a problem.

  In addition, since the external ground electrodes 23 and 24 are electrically connected to each other by the strip-shaped thick film conductor 45 in the lead portions 3a of the internal ground conductor 3 led out to the side surface of the multilayer body 20, the thick film conductor 45 In addition, the plating film 46 that covers all the lead portions 3 a of the internal ground conductor 3 led out to the side surface of the multilayer body 20 can be formed on the front and back side surfaces of the multilayer body 20 in a wide area with high positional accuracy. For this reason, the distance from the external ground electrodes 23 and 24 to the facing portion between the internal signal conductor 2 and the internal ground conductor 3 can be shortened as a whole, and the equivalent series inductance can be reduced.

  Further, the folded portions of the external ground electrodes 23 and 24 are formed with the minimum necessary size, and the external ground electrodes 23 and 24 can be formed on the side surface of the laminate 20 with a large area, so that high frequency characteristics are maintained. However, the space between the external electrodes 21 to 24 can be sufficiently secured, and the three-terminal multilayer capacitor 1 strong against reliability such as migration and solder bridge can be obtained.

[Second Embodiment, FIGS. 7 to 9]
As shown in FIG. 7, the three-terminal multilayer capacitor 1A according to the second embodiment is the same as the three-terminal multilayer capacitor 1 according to the first embodiment except that the internal signal conductor 2 is made wider and the capacitor is larger. The capacity can be obtained. Further, the three-terminal multilayer capacitor 1A is provided with dummy conductors 4 and 5 on the surface of a predetermined protective dielectric ceramic green sheet 13, and a plating film formed by plating growth on the lead portion 3a of the internal ground conductor 3. The distance d3 between the multilayer body 20 and the bottom surface of the multilayer body 20 is ensured to be less than half the thickness of the solder paste used when the three-terminal multilayer capacitor 1A is mounted on a printed circuit board or the like.

  After the dielectric ceramic green sheets 12 and 13 having the above-mentioned configuration are laminated, they are pressed and integrally fired to obtain a laminated body 20 having a rectangular parallelepiped shape as shown in FIG. On the four side surfaces of the laminate 20, the lead portions 2a and 3a of the internal ground conductor 2 and the internal ground conductor 3, and the dummy conductors 4 and 5 are exposed. The distance between the lead part 2a of the internal signal conductor 2 and the dummy conductor 4 and the distance between the lead part 3a of the internal ground conductor 3 and the dummy conductor 5 are the thicknesses of the plating films of the external electrodes 21 to 24, which will be described later, respectively. It is set to 2 times or less.

  Next, a conductive paste is applied to the side surface of the laminate 20 by the same dipping method as in the first embodiment, and then dried, sintered, and fixed. Thus, strips extending to the upper surface, the side surface, and the lower surface of the multilayer body 20 and electrically connected to the lead portions 2a and 3a of the internal signal conductor 2 and the internal ground conductor 3 led to the side surface of the multilayer body 20, respectively. The thick film conductor is formed. Here, the thick film conductor connected to the lead portion 2a and the dummy conductor 4 of the internal signal conductor 2 and the thick film conductor connected to the lead portion 3a and the dummy conductor 5 of the internal ground conductor 3 are the lead portions 2a, 3a and The dummy conductors 4 and 5 are arranged at the center and cover only the lead portions 2a and 3a and the dummy conductors 4 and 5.

  Next, as in the first embodiment, the laminate 20 is placed in a plating bath and wet plating (electrolytic plating) is performed to form Ni and Sn plating films having a thickness of about 2 to 15 μm. Since the thick film conductor is electrically connected to the lead portions 2a and 3a of the internal ground conductors 2 and 3 and the dummy conductors 4 and 5 led out to the side surface of the multilayer body 20, the lead portion not covered with the thick film conductor A plating film also deposits on the exposed portions of 2a, 3a and dummy conductors 4, 5. Since the plating film grows in all directions to the thickness of the plating film, the plating film grown from both sides of the lead portions 2a and 3a and the dummy conductors 4 and 5 is between the lead portions 2a and 3a and the dummy conductors 4 and 5. Cover the gap.

  In this way, as shown in FIG. 9, the external signal electrodes 21 and 22 and the external ground electrodes 23 and 24 made of the thick film conductor and the plating film are formed on the four side surfaces of the multilayer body 20.

  The three-terminal multilayer capacitor 1A having the above configuration can secure a large capacitor capacity because the opposing area of the internal signal conductor 2 and the internal ground conductor 3 can be made larger than that of the first embodiment. Moreover, since the external signal electrodes 21 and 22 are formed in a wide area, a three-terminal multilayer capacitor 1A having a low DC resistance and a high rated current can be obtained.

[Other Examples]
In addition, this invention is not limited to the said Example, It can change variously within the range of the summary. In addition to the three-terminal multilayer capacitor, the multilayer ceramic electronic component includes, for example, a multilayer LC filter, a multilayer impedance element, and a multilayer coil.

1 is an exploded perspective view showing an embodiment of a multilayer ceramic electronic component according to the present invention. The perspective view which shows the manufacturing method of the multilayer ceramic electronic component shown in FIG. Sectional drawing which shows the manufacturing process following FIG. The perspective view which shows the manufacturing process following FIG. The expanded sectional view which shows the manufacturing process following FIG. FIG. 2 is an external perspective view of the multilayer ceramic electronic component shown in FIG. 1. The disassembled perspective view which shows another Example of the multilayer ceramic electronic component which concerns on this invention. The perspective view which shows the manufacturing process following FIG. FIG. 8 is an external perspective view of the multilayer ceramic electronic component shown in FIG. 7. The disassembled perspective view which shows the conventional multilayer ceramic electronic component. FIG. 11 is an external perspective view of the multilayer ceramic electronic component illustrated in FIG. 10.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A ... Three terminal type | mold multilayer capacitor 2 ... Internal signal conductor 3 ... Internal ground conductor 4,5 ... Dummy conductor 12, 13 ... Dielectric ceramic green sheet 20 ... Multilayer body 21,22 ... External signal electrode 23, 24 ... External Ground electrode 45 ... Thick film conductor 46 ... Plating film

Claims (2)

A rectangular ceramic laminate formed by laminating a plurality of internal conductors and a plurality of ceramic layers;
An external electrode provided on the surface of the ceramic laminate and electrically connected to a lead portion of the internal conductor led to the side of the ceramic laminate,
The external electrode is
Extending to the upper surface, the side surface and the lower surface of the ceramic laminate, and covering each central portion of the lead portion of the inner conductor led out to the side surface of the ceramic laminate in a strip shape and covering the center So as not to cover other than the part, the connected strip-shaped thick film conductor,
Covering the thick film conductor and leading to the side of the ceramic laminate, the inner conductor lead-out portion other than the portion covered with the thick film conductor and the gap between the inner conductor lead-out portions Consisting of a plating film provided on the side surface of the ceramic laminate in a directly covered state,
Multilayer ceramic electronic parts characterized by A step of laminating a plurality of inner conductors and a plurality of ceramic layers to form a rectangular ceramic laminate;
Extending to the upper surface, the side surface and the lower surface of the ceramic laminate, and covering each central portion of the lead portion of the inner conductor led out to the side surface of the ceramic laminate in a strip shape and covering the center Forming a strip-shaped thick film conductor to be connected so as not to cover other than the portion ;
In the electrolytic plating method, the lead portion of the inner conductor led out to the side surface of the thick film conductor and the ceramic laminate and directly covering the portion other than the portion covered with the thick film conductor with the plating film, By the growth of the plating film deposited on the lead portion of the conductor, the gap between the lead portions of the inner conductor is directly covered with the plating film, and a plating film is formed on the side surface of the ceramic laminated body. Forming an external electrode made of a plating film;
A method for producing a multilayer ceramic electronic component comprising:

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