Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
1999-02-02
2001-10-16
Mai, Anh (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S083000, C336S223000, C336S232000, C029S602100
Reexamination Certificate
active
06304164
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multilayer electronic component, such as a laminated inductor, and a manufacturing method therefor.
2. Description of the Related Art
A conventional multilayer electronic component has a known structure in which a terminal electrode is formed at each end of a rectangular parallelepiped laminate. The multilayer electronic component is manufactured as follows: initially, ceramic green sheets are laminated so that a laminate of the sheets is formed. Then, the laminate of the sheets is cut to have a size of each of unit components. Then, each of the cut laminates of the sheets are baked and polished so that a laminate is obtained. Finally, a terminal electrode is formed at each end of the laminate so that a multilayer electronic component is manufactured.
A direction in which the green sheets are laminated is a direction perpendicular to a direction in which the two terminal electrode are connected to each other. However, the directions of internal electrodes of a multilayer electronic component of the foregoing type cannot be made constant, causing the characteristics of the multilayer electronic component to be instable. The foregoing fact becomes conspicuous especially for a laminated inductor which is an example of the multilayer electronic component.
Therefore, multilayer electronic components have appeared in recent years, each of which incorporates green sheets laminated in a direction in parallel with a direction of the connection between the terminal electrodes. A laminated inductor which is an example of the multilayer electronic component of the foregoing type will now be described. The laminated inductor is formed by laminating a green sheet having an internal conductor to be formed into a coil, and a green sheet having lead electrodes for establishing the connection between the internal conductor and a terminal electrode. Each green sheet has a via hole filled with a conductor for establishing the connection. Thus, the green sheets are electrically conducted to each other through the via holes. In the foregoing laminated inductor, the direction of the magnetic flux is in parallel to a direction in which the terminal electrodes are connected to each other. That is, the terminal electrodes are formed at two ends of the laminate in the direction of lamination. Therefore, the direction of the magnetic flux after a mounting operation is always in parallel with the surface of mounting. As a result, stable characteristics can be obtained.
However, the lead conductor of the laminated inductor cannot easily be formed. That is, the laminated inductor has the lead conductor which extends substantially straight from the internal conductor to the terminal electrode. Therefore, when the green sheets are laminated, a conductor for establishing the connection is undesirably deviated by a stress. Thus, the electrical conduction between the internal conductor and the terminal electrode is sometimes disconnected. The laminated inductor is formed such that the direction in which the terminal electrodes are connected to each other and that of the magnetic flux are in parallel with each other. Therefore, a larger number of green sheets must be laminated as compared with the conventional multilayer electronic component. Therefore, long time is required to complete the laminating process, thus causing the productivity to deteriorate. What is worse, the laminated inductor sometimes encounters a fact that a required shape cannot always be obtained because burrs and/or breakage occur, in particular, at two ends of the laminated inductor when the laminate is polished. As described above, the foregoing laminated inductor has been suffered from unsatisfactory manufacturing yield.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a multilayer electronic component and a manufacturing method therefor, which is capable of preventing defective connection of a lead conductor thereof and improving the manufacturing yield.
To achieve the above-mentioned object, according to one aspect of the present invention, there is provided a multilayer electronic component, comprising: a laminate with an electronic element embedded therein; and terminal electrodes formed at two ends of the laminate in laminating direction and connected to the electronic element, wherein said laminate incorporates lead electrodes for connecting said electronic element to said terminal electrodes, first insulating sheets each having an element conductor which constitutes said electronic element are laminated such that said element conductors are connected to one another through first via holes, a plurality of second insulating sheets each having a connecting conductor which constitutes said lead electrode are laminated such that said connecting conductors are connected to one another through second via holes, and a contact area of said connecting conductors between at least a portion of said second insulating sheets is made to be larger than a contact area of said element conductors between said first insulating sheets.
According to the present invention, when the second insulating sheets are laminated and pressed, a greater allowance is permitted for the position deviation between the second via holes in the upper and lower layers. As a result, the connection between the connecting conductors between the second insulating sheets can reliably be established.
According to another aspect of the present invention, there is provided a multilayer electronic component, comprising: a laminate with an electronic element embedded therein; and terminal electrodes formed at two ends of the laminate in laminating direction and connected to the electronic element, wherein said laminate incorporates lead electrodes for connecting said electronic element to said terminal electrodes, first insulating sheets each having an element conductor which constitutes said an electronic element are laminated such that said element conductors are connected to one another through first via holes, a plurality of second insulating sheets each having a connecting conductor which constitutes said lead electrode are laminated such that said connecting conductors are connected to one another through second via holes, said second via holes are formed on two or more different straight lines extending in a direction of lamination, and said connecting conductors are alternately connected through said second via holes formed on the two or more straight lines.
According to the present invention, when the second insulating sheets have been laminated, the positions of step portions formed by the connecting conductors are not concentrated on one straight line extending in the direction of lamination. Thus, stress produced by the stepped portion is dispersed and thus deviation of the positions of the second via holes can be reduced. Therefore, the connection of the connecting conductors between the second insulating sheets can reliably be established.
According to another aspect of the present invention, there is provided a multilayer electronic component, comprising: a laminate with an electronic element embedded therein; and terminal electrodes formed at two ends of the laminate in laminating direction and connected to the electronic element, wherein said laminate incorporates lead electrodes for connecting said electronic element to said terminal electrodes, first insulating sheets each having an element conductor which constitutes said an electronic element are laminated such that said element conductors are connected to one another through first via holes, a plurality of second insulating sheets each having a connecting conductor which constitutes said lead electrode are laminated such that said connecting conductors are connected to one another through second via holes, and said connecting conductor formed on said second insulating sheet is formed to project over said second via hole formed in said second insulating sheet.
According to the present invention, if
Ohno Syunichi
Yamagishi Masahiko
Lowe Hauptman & Gilman & Berner LLP
Mai Anh
Taiyo Yuden Co. Ltd.
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