JP2012243998A - Chip-like electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip-like electronic component which has good moisture resistance and is suitable for miniaturization.SOLUTION: A chip-like electronic component 1 comprises a component body 10 having an internal electrode 11 embedded therein, and an external electrode 20 formed on an outer surface of the component body 10. The external electrode 20 is composed of a plurality of electrode layers including a hydrogen barrier layer 21 which is formed by a physical vapor deposition method or a chemical vapor deposition method and has electrical conductivity.

Description

  The present invention relates to a chip-shaped electronic component such as a multilayer ceramic capacitor, and more particularly to a structure of an external electrode.

  A chip-shaped electronic component such as a multilayer ceramic capacitor generally includes a rectangular parallelepiped component main body in which an internal electrode is embedded, and an external electrode formed on the outer surface of the component main body and electrically connected to the internal electrode. . The shape, number, and position of the external electrode vary depending on the type of chip-shaped electronic component. For example, in a general multilayer ceramic capacitor, external electrodes are formed from both longitudinal end surfaces of a rectangular parallelepiped component body to side surfaces adjacent to the end surfaces. As a general method of forming an external electrode, a paste is applied and fired by a dipping method or the like, and then one or more plating layers are formed by electrolytic plating for the purpose of improving solder wettability and preventing solder erosion. A forming method is known (see Patent Document 1).

JP 2008-28064 A

  However, in the conventional chip-shaped electronic component, moisture may enter the component main body during an electrolytic plating process or a moisture resistance test, leading to a decrease in reliability. Further, when Ni-based metal is used as the internal electrode, characteristic deterioration due to Ni hydrogen storage may occur. On the other hand, in recent years, there is an increasing demand for further miniaturization and thinning of chip-shaped electronic components, and as a result, the external electrodes are required to be thin and easy to process finely.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a chip-shaped electronic component that has good moisture resistance and is suitable for downsizing.

  In order to achieve the above object, the present invention provides a chip-like electronic component comprising a component main body in which an internal electrode is embedded and an external electrode formed on the outer surface of the component main body, wherein the external electrode is physically vapor-deposited. It is formed by a plurality of electrode layers including a hydrogen barrier layer formed by a chemical vapor deposition method or a chemical vapor deposition method and having conductivity.

  According to the present invention, the hydrogen barrier layer can prevent moisture from entering the component main body in the step of forming the electrode layer by electrolytic plating on the outer side of the hydrogen barrier layer or in the moisture resistance test. In addition, since the hydrogen barrier layer is formed by a physical vapor deposition method or a chemical vapor deposition method, it is preferable because moisture does not enter the component main body in the hydrogen barrier layer forming step. In addition, since the conductive hydrogen barrier layer is formed by physical vapor deposition or chemical vapor deposition, it can be formed thinner than the dip method, which is advantageous for downsizing of the component size.

  As an example of a preferable aspect of the present invention, the hydrogen barrier layer may be formed as an innermost layer in contact with the component main body. As another example of the preferred embodiment of the present invention, one characterized in that one or more electrode layers are formed on the outer layer side of the hydrogen barrier layer by electrolytic plating.

  As described above, according to the present invention, the hydrogen barrier layer prevents moisture from entering the component main body in the step of forming an electrode layer by electrolytic plating on the outer side of the hydrogen barrier layer or during a moisture resistance test. be able to. In addition, since the hydrogen barrier layer is formed by a physical vapor deposition method or a chemical vapor deposition method, it is preferable because moisture does not enter the component main body in the hydrogen barrier layer forming step. In addition, since the conductive hydrogen barrier layer is formed by physical vapor deposition or chemical vapor deposition, it can be formed thinner than the dip method, which is advantageous for downsizing of the component size.

Sectional drawing of the multilayer ceramic capacitor which concerns on 1st Embodiment Flowchart for explaining a method of manufacturing a multilayer ceramic capacitor according to the first embodiment Sectional drawing of the multilayer ceramic capacitor which concerns on 1st Embodiment Flowchart for explaining a method of manufacturing a multilayer ceramic capacitor according to the first embodiment

(First embodiment)
A chip-shaped electronic component according to a first embodiment of the present invention will be described with reference to the drawings. In this embodiment, a multilayer ceramic capacitor will be described as an example of a chip-shaped electronic component. FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor. It should be noted that in the present application, dimensions and shapes are appropriately modeled for simplicity of explanation.

  As shown in FIG. 1, the multilayer ceramic capacitor 1 includes a substantially rectangular parallelepiped laminated body 10 that is a component main body, and a pair of external electrodes 20 formed at both longitudinal ends of the laminated body 10.

  The laminate 10 is made of a ceramic sintered body in which a plurality of internal electrode layers 11 and dielectric layers 12 are alternately laminated. The internal electrode layers 11 are arranged so as to overlap each other with a predetermined interval, and the end portions thereof are alternately exposed at one end face of the laminate 10 and are electrically connected to the external electrode 20 at the end face. Yes. That is, every other internal electrode layer 11 is electrically connected to the same external electrode 20. The internal electrode layer 11 is made of a base metal such as Ni or Cu, a noble metal such as Pd or Ag, or a metal mainly composed of an Ag—Pd alloy, but Ni is preferable from the viewpoint of cost reduction. In the present embodiment, the multilayer ceramic capacitor 1 is of a high dielectric constant class 2, and the dielectric layer 12 is made of a dielectric ceramic based on barium titanate.

  The external electrode 20 is formed so as to wrap around from the both end surfaces in the longitudinal direction to the side surface adjacent to the end surface of the surface of the multilayer body 10. The external electrode 20 has a four-layer structure including a hydrogen barrier layer 21 formed in the innermost layer, that is, a portion in contact with the stacked body 10, and three electrode layers 22 to 24 formed in the outer layer of the hydrogen barrier layer 21. It has become.

  The hydrogen barrier layer 21 is an electrode layer for preventing moisture from entering the laminated body 10, and is made of a material having a hydrogen barrier function and conductivity. The material of the hydrogen barrier layer 21 is preferably a conductive material having a small hydrogen diffusion coefficient, and examples thereof include metal nitrides such as TaN and TiN. The hydrogen barrier layer 21 is formed of a thin film formed by a dry process such as a physical vapor deposition method such as sputtering, vacuum vapor deposition, or ion plating, or a chemical vapor deposition method such as thermal CVD, cold wall CVD, MOCVD, ALCVD, or plasma CVD. .

  The electrode layers 22-24 consist of a thin film formed by electrolytic plating. The electrode layer 22 is a layer for performing the main function as the external electrode 20, and it is preferable to select a material by paying attention to electrical characteristics. Specifically, it is preferable to select from base metals such as Cu and Ni, precious metals such as Ag and Au, and alloys thereof. In this embodiment, Cu is selected. The electrode layers 23 and 24 are layers for preventing erosion of solder and improving solder wettability. In the present embodiment, Ni is used for the electrode layer 23 and Sn is used for the electrode layer 24.

  Next, a method for manufacturing the multilayer ceramic capacitor 1 according to the present embodiment will be described with reference to the flowchart of FIG. First, a raw material powder for forming a dielectric ceramic, an organic binder, a solvent and other additives are mixed to prepare a ceramic slurry (step S1). Next, the ceramic slurry is formed and dried into a sheet shape by a doctor blade method or the like to obtain a ceramic green sheet (step S2). Next, the internal electrode paste is printed in a predetermined pattern shape on the ceramic green sheet (step S3). The paste is preferably mixed with a predetermined amount of ceramic raw material powder as a co-fabric. Next, the ceramic green sheets on which the paste is printed are laminated in a predetermined pattern and number, and then pressed to obtain a sheet laminate (step S4). Next, after cutting the sheet laminate into individual chips (step S5), the surface of the individual chips is polished by barrel polishing or the like (step S6). Next, the binder removal process is performed on the polished individual chips in the air or in a non-oxidizing gas such as nitrogen (step S7). Next, the individual chips after the binder removal treatment are fired in a nitrogen-hydrogen atmosphere at a predetermined temperature (step S8), and further, a reoxidation treatment is performed to obtain the laminate 10 (step S9).

  Next, the hydrogen barrier layer 21 is formed on the stacked body 10 by physical vapor deposition or chemical vapor deposition (step S10). For example, when sputtering is used, the laminate 10 placed on a predetermined jig is set on the stage of a sputtering apparatus, and an electrode material such as TaN or TiN is formed to a thickness of 1 μm. At this time, the laminated body 10 is installed so that the edge part opposes a sputtering target. Further, the jig may be swung together so that the hydrogen barrier layer 21 is also formed at the corners and sides of the laminate 10. Further, as sputtering conditions, for example, the film is formed at Ar 30 sccm, 1 Pa, DC 500 W. After film formation at one end, the jig is rotated 180 ° to form the hydrogen barrier layer 21 at the other end.

  Next, an electrode layer 22 made of Cu, an electrode layer 23 made of Ni, and an electrode layer 24 made of Sn are sequentially formed on the hydrogen barrier layer 21 by electrolytic plating (step S11). What should be noted here is that the hydrogen barrier layer 21 having a small hydrogen diffusion coefficient is densely formed on the surface of the stacked body 10, so that it is possible to prevent moisture and H or H + from entering the stacked body. Thus, characteristic deterioration can be prevented. The multilayer ceramic capacitor 1 was obtained through the above steps.

  Thus, in the multilayer ceramic capacitor according to the present embodiment, the external electrode 20 is formed of a plurality of electrode layers, and the hydrogen barrier layer 21 having a hydrogen barrier function is formed as the innermost electrode layer. Therefore, it is possible to prevent moisture from entering the laminated body 10 in the step of forming the electrode layers 22 to 24 by electrolytic plating on the outer layer side of the hydrogen barrier layer 21 or the moisture resistance test. In addition, since the hydrogen barrier layer 21 is formed by a physical vapor deposition method or a chemical vapor deposition method, it is preferable because moisture does not enter the laminated body 10 in the formation process of the hydrogen barrier layer 21. In addition, since the conductive hydrogen barrier layer 21 is formed by physical vapor deposition or chemical vapor deposition, it is advantageous for downsizing of the component size.

(Second Embodiment)
A chip-shaped electronic component according to a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, a multilayer ceramic capacitor will be described as an example of a chip-shaped electronic component. FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor, and FIG. 4 is a flowchart for explaining a method of manufacturing the multilayer ceramic capacitor.

  The multilayer ceramic capacitor according to the present embodiment is different from the first embodiment in the layer structure of the external electrode. Since other configurations are the same as those of the first embodiment, only the differences will be described here.

  In the multilayer ceramic capacitor 2 according to the present embodiment, the external electrode 30 includes an outermost inner layer, that is, a main electrode layer 31 formed in a portion in contact with the multilayer body 10, and a hydrogen barrier formed in the outer layer of the main electrode layer 31. It has a five-layer structure of a layer 32 and three electrode layers 33 to 35 formed on the outer layer of the hydrogen barrier layer 32. That is, the difference from the first embodiment is that the hydrogen barrier layer 32 is not the innermost layer of the external electrode 30 but an electrode layer is present on the inner layer side of the hydrogen barrier layer 32.

  The main electrode layer 31 is a layer for performing the main function as the external electrode 30, and it is preferable to select a material by paying attention to electrical characteristics, and also to select a material that provides good bonding with the internal electrode layer 11. Is preferred. Specifically, it is preferable to select from base metals such as Cu and Ni, precious metals such as Ag and Au, alloys thereof, and the like, and it is preferable to select the same material as the internal electrode layer 11. The main electrode layer 31 is formed by applying and baking a paste such as a dipping method or a printing method.

  The configuration, formation method, and the like of the hydrogen barrier layer 32 and the electrode layers 33 to 35 are the same as those in the first embodiment.

  In addition, as shown in FIG. 4, the method for manufacturing the multilayer ceramic capacitor 2 according to the present embodiment includes a main electrode layer for the polished individual chip between step S7 and step S8 in the first embodiment. What is necessary is just to provide the process (step S7a) of apply | coating or printing the paste for 31. The paste is fired together with the ceramic body and internal electrodes in the next firing step.

  The operations and effects of the multilayer ceramic capacitor according to the present embodiment are the same as those of the first embodiment.

  Although one embodiment of the present invention has been described in detail above, the present invention is not limited to this. For example, in the above embodiment, a multilayer ceramic capacitor has been described as an example of a chip-shaped electronic component. However, the present invention can also be implemented with other chip-shaped electronic components. That is, in the present invention, the material of the component main body is not required, and the shape and number of the external electrodes are not required.

  Further, in the above embodiment, the hydrogen barrier layers 21 and 32 are formed by using the sputtering method as an example of the physical vapor deposition method or the chemical vapor deposition method, but other physical vapor deposition methods or chemical vapor deposition methods may be used. Even if it uses, this invention can be implemented.

  DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor, 10 ... Laminated body, 11 ... Internal electrode layer, 12 ... Dielectric layer, 20, 30 ... External electrode, 21, 32 ... Hydrogen barrier layer, 22-24, 33-35 ... Electrode layer, 31 ... Main electrode layer

Claims (3)

In a chip-like electronic component comprising a component main body in which an internal electrode is embedded and an external electrode formed on the outer surface of the component main body,
The external electrode includes a plurality of electrode layers formed by physical vapor deposition or chemical vapor deposition and including a conductive hydrogen barrier layer. The chip-shaped electronic component according to claim 1, wherein the hydrogen barrier layer is formed in an innermost layer in contact with the component main body. The chip-shaped electronic component according to claim 1 or 2, wherein one or more electrode layers are formed by electrolytic plating on an outer layer side of the hydrogen barrier layer.

Images