News Column

"Monolithic Ceramic Electronic Component" in Patent Application Approval Process

August 21, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventors SASABAYASHI, Takehisa (Nagaokakyo-shi, JP); MOTOKI, Akihiro (Nagaokakyo-shi, JP); OGAWA, Makoto (Nagaokakyo-shi, JP), filed on January 22, 2014, was made available online on August 7, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Murata Manufacturing Co., Ltd.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to monolithic ceramic electronic components and particularly relates to a monolithic ceramic electronic component including inner electrodes containing Ni and outer electrodes which are electrically connected to the inner electrodes and which are formed by plating.

"Outer electrodes of a monolithic ceramic capacitor, which is an example of a monolithic ceramic electronic component, are usually formed in such a way that a conductive paste is applied to end portions of a component body and is then baked. However, the thickness of the outer electrodes, which are formed in the above way, is large, about tens to hundreds of micrometers. Therefore, in order to adjust the size of the monolithic ceramic capacitor to a certain standard size, the effective volume for ensuring the electrostatic capacity needs to be undesirably reduced because the volume of the outer electrodes needs to be ensured.

"In order to solve this problem, it has been proposed and has been in practical use that metal coatings are deposited directly on a component body so as to connect lead ends of inner electrodes to each other and each of the metal coatings is used as at least one portion of a corresponding one of the outer electrodes. For example, Japanese Unexamined Patent Application Publication No. 63-169014 discloses a method for forming outer electrodes in such a way that conductive metal layers are deposited by electroless Ni plating over side surfaces of a component body that have exposed inner electrodes such that the inner electrodes exposed on the side surfaces are shorted. According to the outer electrode-forming method, the volume of the outer electrodes can be reduced and therefore the effective volume for ensuring the electrostatic capacity can be increased.

"However, a metal coating formed directly on a certain surface of a body of a component has a problem that the anchoring force between the metal coating and the component body is low because there is no glass or the like therebetween, unlike the electrodes formed by baking the conductive paste as described above. When the anchoring force therebetween is low, the interface between the metal coating and the component body may possibly be cracked and suffer from the ingress of moisture. Furthermore, the ingress of moisture into interfaces between ceramic layers and inner electrodes may possibly cause electrical shorts between the inner electrodes, which have different potentials, which impairs functions of the component."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "Preferred embodiments of the present invention provide a monolithic ceramic electronic component capable of solving the above problem.

"According to a preferred embodiment of the present invention, a monolithic ceramic electronic component includes a component body and outer electrodes. The component body includes a plurality of stacked ceramic layers and a plurality of inner electrodes which extend between the ceramic layers, which contain Ni, and which have exposed ends exposed on predetermined surfaces of the component body. The outer electrodes are plated electrodes, i.e., the outer electrodes are formed on the predetermined surfaces of the component body by plating, and are electrically connected to the exposed ends of the inner electrodes. The inner electrodes include regions (hereinafter referred to as 'Mg--Ni coexistence regions') where Mg and Ni coexist.

"The Mg--Ni coexistence regions contain an Mg--Ni oxide. The ceramic layers are made of a ceramic which is an oxide. Therefore, the inner electrodes, which include the Mg--Ni coexistence regions, exert stronger anchoring forces on the ceramic layers as compared to regions containing no Mg--Ni oxide. This allows the interfacial delamination between the ceramic layers and the inner electrodes to be unlikely to occur.

"Each of the Mg--Ni coexistence regions is preferably present in at least a corresponding one of portions of the inner electrodes that are located in a peripheral section of a region containing the exposed ends. This allows the anchoring forces between the inner electrodes and the outer electrodes to be reliably increased and therefore allows the ingress of moisture through the interfaces between the component body and the outer electrodes to be reliably prevented.

"The Mg--Ni coexistence regions present in the portions of the inner electrodes that are located in the peripheral section of the region containing the exposed ends preferably have an Mg-to-Ni molar ratio of about 0.1 or greater and also preferably have an area fraction of about 25% or greater and more preferably about 70% or greater, for example. An increase in area fraction enables the anchoring forces between the inner electrodes and the outer electrodes to be increased.

"The Mg--Ni coexistence regions are preferably present in at least the inner electrodes that are at an outermost location when a region containing the inner electrodes is viewed in a stacking direction in which the ceramic layers are stacked. This allows the delamination of the ceramic layers located in outer portions of the component body to be significantly reduced or prevented.

"The Mg--Ni coexistence regions present in the inner electrodes that are at an outermost location when the region containing the inner electrodes is viewed in the stacking direction preferably have an Mg-to-Ni molar ratio of about 0.1 or greater and an area fraction of about 30% or greater, for example. This allows the effect of reducing or preventing the delamination of the ceramic layers located in outer portions of the component body to be reliably exhibited.

"According to preferred embodiments of the present invention, inner electrodes including Mg--Ni coexistence regions exert strong anchoring forces to ceramic layers. Therefore, the ingress of moisture into a component body is significantly reduced or prevented. Thus, the moisture resistance reliability of a monolithic ceramic electronic component is increased.

"The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a perspective view of a monolithic ceramic electronic component according to a first preferred embodiment of the present invention.

"FIG. 2 is a sectional view taken along the line I-I of FIG. 1.

"FIG. 3 is a sectional view taken along the line II-II of FIG. 2.

"FIG. 4 is a perspective view of a monolithic ceramic electronic component according to a second preferred embodiment of the present invention."

URL and more information on this patent application, see: SASABAYASHI, Takehisa; MOTOKI, Akihiro; OGAWA, Makoto. Monolithic Ceramic Electronic Component. Filed January 22, 2014 and posted August 7, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4303&p=87&f=G&l=50&d=PG01&S1=20140731.PD.&OS=PD/20140731&RS=PD/20140731

Keywords for this news article include: Murata Manufacturing Co. Ltd.

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Source: Politics & Government Week


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