Method of manufacturing a chip type electronic element

Details Method of manufacturing a chip type electronic element Method of manufacturing a chip type electronic element

1999-01-22

2001-01-09

Picardat, Kevin M. (Department: 2822)

Semiconductor device manufacturing: process

Making device or circuit responsive to nonelectrical signal

Responsive to electromagnetic radiation

C438S051000, C438S055000, C438S458000, C438S964000, C148SDIG001, C310S365000

Reexamination Certificate

active

06171884

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a chip type electronic component which includes a multilayer body formed by laminating a plurality of substrates and at least one internal electrode interposed between two of the substrates and an external electrode disposed on a side surface of the multilayer body and connected to the internal electrode.
2. Description of Related Art
A chip type electronic component described above is well known. Because the external electrode is connected to the internal electrode only at a small area, there is a risk that the internal and external electrodes are disconnected easily by variations in the substrate size, the position the internal electrode, and other factors.
One method of manufacturing a chip type electronic component to overcome the above problem is disclosed in Japanese Patent Publication No. 7-120913. The method includes the steps of forming a groove at a side surface of a multilayer body so as to expose an end of an internal electrode and forming an external electrode on the side surface of the multilayer body. The groove at the side surface of the multilayer body is formed via cutting using a cutting machine or via sand-blasting.
However, when the groove is formed at the side surface of the multilayer body via cutting using a cutting machine, because each chip component needs to be positioned and maintained accurately, the grooves in each chip component cannot be made efficiently and the process of manufacturing many chip components cannot be performed effectively. Moreover, it is difficult to utilize the cutting process using a cutting machine for forming the groove for microchip components because of the relatively small size of such components.
When sand-blasting is utilized for forming the groove at the side surface of the multilayer body, there is an advantage in that the side surface of the multilayer body can be roughened and thereby, the contact strength between the multilayer body and the external electrode improves.
However, it is difficult to form the groove having a depth such that the end of the internal electrode is exposed reliably when forming the groove via sandblasting. Moreover, the chip type electric components must be aligned with a pallet or a jig and the sand-blasting needs to be performed on all the respective side surfaces of the multilayer bodies where the respective internal electrodes are desired to be exposed. Therefore, the pallet and the jig prepared in accordance with each of the different size electric components are required, causing increased cost. Further, when the manufacturing processing step is required to be performed four times (i.e. sandblasting each side surface of the chip component), the processes for re-positioning and aligning the chip type electric components via a pallet or a jig are required to be performed three times.
Furthermore, in both of the above two processes (cutting and sand-blasting), only one side surface of the multilayer body can be processed at one time. When an external electrode is continuously formed at the side surface of the multilayer body and a surface adjacent to the side surface, since a sharp edge is formed at the boundary of these two surfaces, the film thickness of the external electrode can not be maintained and therefore, a disconnection between different portions of the external electrode easily occurs at the sharp edge causing a component to be defective.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide a method of manufacturing a chip type electric component in which a groove at a side surface of a multilayer body where an end of an internal electrode is exposed is formed effectively and inexpensively, and at the same time the side surface of the multilayer body is roughened and an edge portion of the multilayer body is formed to have a gradually curved shape.
According to one preferred embodiment of the present invention, a method of manufacturing a chip type electronic component includes the steps of forming a multilayer body including a major surface and a side surface by laminating a plurality of substrates and at least one internal electrode interposed between two of the substrates, forming a groove between the two substrates at the side surface of the multilayer body so as to expose an end of the at least one internal electrode, and making the side surface of the multilayer body rough by performing barrel polishing on the multilayer body, the barrel polishing being performed in a barrel pot in which water, media, an abrasive powder and the multilayer body are provided, and forming an external electrode on the side surface of the multilayer body, the external electrode being connected to the end of the at least one internal electrode exposed at the groove.
According to the above described method, because the barrel polishing is performed in a barrel pot in which water, the media, the abrasive powder and the multilayer body are provided, an unexpected synergistic effect is achieved. More specifically, a roughening effect of the abrasive powder and an effect of making an edge portion of the multilayer body curved and a cushion effect provided by the media, is obtained. As a result, the side surface of the multilayer body can be made sufficiently rough, and a groove having a curved portion and in which the end of the internal electrode is exposed can be formed easily and inexpensively.
Therefore, a sufficient contact strength between the side surface of the multilayer body and the external electrode is obtained when the external electrode is formed on the side surface of the multilayer body. Also, the internal electrode can be connected to the external electrode along a large area, and therefore, the reliability of the connection increases.
Moreover, when the barrel polishing is performed, an effect of making an edge portion of the multilayer body curved is also effective at the edge portion between the side surface and the surface adjacent to the side surface of the multilayer body. As a result, the edge portion has a gradually curved shape. When the external electrode is formed over the side surface and the adjacent surface of the multilayer body, the disconnection of the external electrode at the edge portion is prevented because the edge portion has the gradually curved shape.
If barrel polishing is performed on the multilayer body on which a thick-film electrode is formed, with water, media, and an abrasive powder as described above, the damage to the thick film is so low that it is negligible. In other words, a damage to the section which occupies a large area is extremely low. Therefore, an electrode does not need to be formed again on the multilayer body where the thick-film electrode was preformed, and consequently, productivity is high.
Further, barrel polishing of many multilayer bodies can be performed at the same time. Moreover, because there is no need to position each multilayer body and to change the electric element aligned with a pallet or a jig, productivity improves markedly compared with the above described cutting method or sand-blasting method.
In the above described method, the media inserted in the barrel pot has preferably more volume than the multilayer body, and the diameter of media is preferably less than about two times a length of the longest edge of the multilayer body. As a result, the effect of making an edge portion of the multilayer body curved is particularly effective, and defects such as splitting or chipping of the electrodes are prevented.
When preferred embodiments of the present invention are applied to a piezoelectric component, the external electrode is preferably formed by a thin-film forming method. If the external electrode is formed by a thick-film forming method, there is a possibility that a dipole may be generated in the case of a piezoelectric component. It should be noted that a contact strength between the external electrode and the multilayer body b

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