JP2014203862A - Ceramic electronic component and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic electronic component that is easily mounted, has sufficient strength, and exhibits high accuracy, even when being reduced in size.SOLUTION: A ceramic electronic component includes: a ceramic body 11 formed by simultaneously firing a ceramic element assembly and an internal electrode 12; an external electrode 13 provided at both end portions of the ceramic body 11. In the ceramic electronic component, a relation of 0.35<L1/L0<0.45 is satisfied, where, when an L direction is a direction in which both end surfaces provided with the external electrode 13 face each other, L0 represents a length of the ceramic electronic component in the L direction, and L1 represents a length of the external electrode 13 in the L direction on a surface 11a serving as a mounting surface of the ceramic electronic component.

Description

  The present invention relates to a surface mount ceramic electronic component used in various electronic devices and a method for manufacturing the same.

  In recent years, as electronic devices have become smaller and higher performance, various electronic components have been required to have small and high performance surface mount components. For example, chip thermistors for temperature compensation are also required to be small, low profile and high precision. For this reason, as shown in FIG. 5, the internal electrode 2 is formed between the ceramic bodies constituting the thermistor, and the external electrode 3 electrically connected to the internal electrode 2 is electrically connected to the end face of the simultaneously fired ceramic body 1. What was formed by apply | coating and baking a paste has been used.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

Japanese Patent Laid-Open No. 2004-311676

  When the miniaturized chip thermistor is mounted and reflow soldered, chip standing tends to occur. Furthermore, when the chip thermistor is reduced in size and height, the resistance value is not only the resistance value between the internal electrodes, but also the resistance value between the internal electrode and the external electrode on the opposite side affects the overall resistance value. It was difficult to improve accuracy.

  The present invention solves this problem, and an object of the present invention is to provide a ceramic electronic component that is small and low in profile and easy to mount with high accuracy.

  In order to solve the above-mentioned problems, the present invention provides a ceramic electronic component comprising a ceramic body formed by simultaneously firing a ceramic body and internal electrodes, and external electrodes provided at both ends of the ceramic body. Then, the direction in which both end surfaces provided with the external electrodes are opposed to each other is L direction, the length of the ceramic body in the L direction is L0, and the length of the external electrode on the surface to be the mounting surface of the ceramic electronic component is L1 Then, 0.35 <L1 / L0 <0.45.

  With the above configuration, when this ceramic electronic component is mounted and reflow soldered, the force pulled to the mounting substrate side by the external electrode on the mounting surface side becomes strong, and the chip standing can be made difficult to occur.

Sectional drawing of the chip thermistor in one embodiment of this invention The perspective view of the chip thermistor in one embodiment of the present invention Sectional drawing of another chip | tip thermistor in one embodiment of this invention The figure which shows the manufacturing method of the chip | tip thermistor in one embodiment of this invention. Cross section of conventional chip thermistor

  Hereinafter, a ceramic electronic component according to an embodiment of the present invention will be described with reference to the drawings, taking a chip thermistor as an example.

  FIG. 1 is a cross-sectional view of a chip thermistor according to an embodiment of the present invention, and FIG. 2 is a perspective view thereof. The inner layer of a ceramic body 11 whose main component is an oxide such as Mn, Ni, Co, etc. is made of Pd. The internal electrodes 12 are provided so as to face each other. External electrodes 13 electrically connected to the internal electrode 12 are provided at both ends of the ceramic body 11.

  The outer shape of this chip thermistor is about 0.4 mm in length, about 0.2 mm in width, and about 0.2 mm in height. Here, the direction in which both end surfaces 11b on which the external electrodes 13 are provided is opposed to the L direction, and the length (L1) in the L direction of the external electrode 13 on the surface 11a serving as the mounting surface is about 0.16 mm.

  When ceramic electronic components are miniaturized, the height of the ceramic electronic components becomes higher than the size, and chip standing tends to occur during solder reflow. In this chip standing, when the solder melts, the surface tension causes a pulling force in the direction of both end faces of the ceramic electronic component. When this force balance is lost, chip standing occurs. On the other hand, in this embodiment, since L1 is increased, the surface tension of the solder also works in the direction of the mounting substrate, so that chip standing is less likely to occur. In order to obtain this effect, it is desirable that the length of the ceramic electronic component in the L direction is L0, and 0.35 <L1 / L0 <0.45. When L1 / L0 is 0.35 or less, the effect of suppressing the chip standing is reduced, and when L1 / L0 is 0.45 or more, the interval between the external electrodes becomes too small, causing a short circuit or a change in resistance value due to leakage current, etc. This is because there is a possibility of occurrence.

  This phenomenon is particularly effective when L0 is 0.6 mm or less because the weight of the ceramic electronic component decreases as the size of the ceramic electronic component decreases.

  In order to realize the above configuration, the external electrode 13 is provided along the end face electrodes 15 provided on the both end faces 11b of the ceramic body 11 and the both end faces 11b of the ceramic body 11 on the face 11a to be the mounting surface of the chip thermistor. It is desirable that the lower electrode 14 is provided, and the plating electrode layer 16 is provided so as to cover the end face electrode 15 and the lower electrode 14.

  Here, the thickness of the internal electrode 12 and the bottom electrode 14 is about 1.5 μm, the thickness between the internal electrodes 12 is about 50 μm, the thickness of the end face electrode 15 is about 15 μm, and the thickness of the plating electrode layer 16 is Ni Is about 1.5 μm and Sn is about 2.5 μm.

  End face electrodes 15 are provided on both end faces 11 b of the ceramic body 11 and are electrically connected to the respective internal electrodes 12. A lower surface electrode 14 is provided along both end surfaces 11b of the surface 11a of the ceramic body 11 serving as a mounting surface of the chip thermistor, and the lower surface electrode 14 is electrically connected to each end surface electrode 15. The lower electrode 14 is formed by using the same material as that of the internal electrode 12 and simultaneously firing the ceramic body 11 and the internal electrode 12. Further, a plated electrode layer 16 of Ni and Sn is formed on the end face electrode 15 and the lower face electrode 14, thereby constituting the external electrode 13. The external electrode length (L1) of the external electrode 13 on the mounting surface side is about 0.16 mm. As shown in FIG. 2, a part of the end surface electrode wraps around the side surface 11c of the ceramic body 11. Except for, the external electrode is substantially not formed.

  A comparison is made between the chip thermistor configured as described above and a chip thermistor formed by applying an external electrode as in the prior art. If the external electric length is made to be about 0.16 mm by the conventional method, the interval between the external electrodes becomes too small to be stably formed. Therefore, for example, when the thickness is about 0.1 mm, the thickness on the end surface side is about 20 μm, and the thickness on the upper and lower surfaces and the side surface 11c is about 10 μm. If a plating electrode layer of Ni of about 1.5 μm and Sn of about 2.5 μm is further formed thereon, the thickness of the external electrode in the height direction is about 28 μm in total. On the other hand, in this embodiment, it is about 5.5 μm. In this way, the thickness due to the external electrode can be reduced by 20 μm or more (10% or more of the thickness of the ceramic body) compared to the conventional case. That is, if it is going to be a predetermined thickness, the thickness of the ceramic body can be increased by 10% or more, and the bending strength can be increased.

  In addition, the conventional external electrode by coating has a large thickness and a large gap with the ceramic body, so that it is easily broken when an impact is applied. On the other hand, in the present embodiment, the external electrode 13 on the mounting surface side can be flattened and the area is increased, so that it is strong against external impacts.

  Further, in the chip thermistor, the resistance value is basically determined by the resistance value between the internal electrodes, but the influence on the resistance value due to the leakage current between the internal electrode and the external electrode opposed thereto is also added. Therefore, when the external power length varies, the distance between the internal electrode and the external electrode facing the internal electrode varies, and this causes a variation in resistance value as a whole. If the external electrode is formed by coating as in the prior art, variations in the external power length are likely to occur. On the other hand, in the present embodiment, variations in the external power length can be suppressed by patterning the bottom electrode 14 by printing and performing simultaneous firing.

  In addition, since the external electrode is formed on the side surface in the conventional method, the distance between the internal electrode and the side surface decreases as the miniaturization progresses. To do. In the present embodiment, since the external electrode is not substantially formed on the side surface 11c of the ceramic body 11 except for a part of the end surface electrode that is wrapped around, the space between the internal electrode 12 and the side surface 11c is not formed. There is no leakage current.

  As described above, in this embodiment, the influence of the leakage current on the entire resistance value can be greatly reduced, and a highly accurate chip thermistor can be obtained.

  In the above embodiment, the lower surface electrode 14 is provided only on the surface 11a to be the mounting surface of the ceramic body 11, but the lower surface electrode 14 having the same size is also provided on the surface opposite to the mounting surface as shown in FIG. It may be provided. By doing so, the thickness of the external electrode 13 is slightly increased, but it is not necessary to distinguish between the upper and lower surfaces, so that the process can be simplified during the manufacturing process or mounting.

  Next, the manufacturing method of the chip thermistor of the present invention will be described.

First, oxide powders of starting raw materials Mn ₃ O ₄ , Co ₃ O ₄ , Fe ₂ O ₃ , and Al ₂ O ₃ are mixed and dried, then calcined and pulverized to obtain a negative electrode containing Mn ₃ O ₄ as a main component. A functional ceramic material having resistance characteristics is obtained. Next, an organic binder and a solvent are added to the powder of the functional ceramic material to produce a ceramic slurry.

  Next, using this ceramic slurry, a green sheet having a predetermined thickness is obtained by a doctor blade method or the like. Further, using a screen printing method, a Pd internal electrode paste is filled into the mesh openings of the screen, and the internal electrode paste is applied to the green sheet to form a conductor layer that becomes the internal electrode 12.

  Next, as shown in FIG. 4A, a predetermined number of green sheets 17a on which a conductor layer to be the internal electrode 12 is formed are stacked, and a predetermined number of green sheets 17b on which the conductor layer is not formed are stacked. Further, a green sheet 17c on which an electrode pattern to be the lower surface electrode 14 is formed with the same paste as the internal electrode paste for forming the internal electrodes on the upper and lower sides thereof is stacked and pressure-bonded to form a stacked block.

  Next, the laminated block is cut along the cutting line of FIG. Further, after exposing the end portions of the internal electrodes 12 to the both end faces 11b of the chip, the binder is removed, and firing is sequentially performed at 1200 ° C. to 1300 ° C., so that the ceramic body 11 of the ceramic sintered body as shown in FIG. obtain. Subsequently, the both end surfaces 11b of the ceramic body 11 are coated with a conductive paste containing Cu powder and glass frit that is electrically connected to the lower surface electrode 14, and baked at 800 ° C. to 900 ° C. An electrode 15 is formed, as shown in FIG. Further, an external electrode 13 is formed by forming a plated electrode layer 16 of Ni of about 1.5 μm and Sn of about 2.5 μm on the end face electrode 15 and the lower face electrode 14, and has a length of about about 4 mm as shown in FIG. A chip thermistor having a width of about 0.4 mm, a width of about 0.2 mm, and a height of about 0.2 mm is obtained.

  By forming the external electrode 13 as described above, the external electrode 13 can be formed only on the end surface and the upper and lower surfaces and not on the side surface (however, when applied to the end surface, Excludes bleeding.) Further, since the lower surface electrodes 14 formed on the upper and lower surfaces are formed by printing, the external power length can be made constant. Further, since the end face electrode 15 is also applied to such an extent that it is electrically connected to the lower face electrode 14, the amount of application can be reduced, and the influence on the outer shape can be minimized.

  The ceramic electronic component according to the present invention provides a ceramic electronic component that is easy to mount with high accuracy even if it is downsized, and is industrially useful.

DESCRIPTION OF SYMBOLS 11 Ceramic body 11a The surface used as a mounting surface 11b End surface 11c Side surface 12 Internal electrode 13 External electrode 14 Bottom electrode 15 End surface electrode 16 Plating electrode layer 17a Green sheet 17b which formed the conductor layer used as an internal electrode The conductor layer is formed No green sheet 17c Green sheet on which an electrode pattern to be the bottom electrode is formed

Claims (6)

A ceramic electronic component comprising a ceramic body formed by simultaneously firing a ceramic body and internal electrodes, and external electrodes provided at both ends of the ceramic body, wherein both end surfaces provided with the external electrodes are When the facing direction is the L direction, the length of the ceramic electronic component in the L direction is L0, and the length of the external electrode on the surface to be the mounting surface of the ceramic electronic component is L1. Ceramic electronic parts characterized by satisfying .35 <L1 / L0 <0.45. The ceramic electronic component according to claim 1, wherein the L1 is 0.6 mm or less. The external electrode is provided on a lower surface electrode in contact with the both end surfaces of a surface to be a mounting surface of the ceramic electronic component, and on both end surfaces of the ceramic body, and is electrically connected to the internal electrode and the lower surface electrode. 2. The ceramic electronic component according to claim 1, comprising an end face electrode and a plating electrode layer covering the end face electrode and the lower face electrode. 4. The ceramic electronic component according to claim 3, wherein the lower surface electrode is fired simultaneously with the ceramic body and the internal electrode. The ceramic electronic component according to claim 1, wherein the lower surface electrodes are formed on upper and lower surfaces of the ceramic body that face each other. A step of forming a laminated block by laminating a green sheet having a conductor layer to be an internal electrode and a green sheet having a conductor layer to be a bottom electrode, and cutting the laminated block into chips to be fired A step of obtaining a ceramic body, a step of forming end face electrodes electrically connected to the internal electrode and the lower face electrode on both end faces of the ceramic body, and a plating electrode covering the lower face electrode and the end face electrode Forming an external electrode by providing a layer, the length in the L direction of the ceramic body is L0, and the length in the L direction of the external electrode on the surface to be the mounting surface of the ceramic electronic component is When L1 is set, external electrodes are formed so that 0.35 <L1 / L0 <0.45. Method.

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