US 7,808,770 B2
`(10) Patent No.:
`a2) United States Patent
`Itamuraet al.
`(45) Date of Patent:
`Oct. 5, 2010
`
`
`US007808770B2
`
`(54) MONOLITHIC CERAMIC CAPACITOR
`:
`
`(75)
`
`Inventors:
`
`tivote amare. eumID)Ye Nasaak
`
`aniguchi, Nyuu-gun
`Kawaguchi, Fukui (JP)
`
`; Yoshio
`
`6,388,864 BL*
`6,771,485 B2*
`
`6,773,827 B2*
`
`.......... 361/309
`5/2002 Nakagawaetal.
`8/2004 Yokoyamaetal. .......... 361/309
`
`8/2004 Higuchi ou... 428/646
`
`(73) Assignee: Ketpymmmacturing Co., Ltd.,
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 338 days.
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`
`2-116720 U
`
`9/1990
`
`(21) Appl. No.: 12/140,341
`
`(22)
`
`Filed:
`
`Jun. 17, 2008
`
`(65)
`
`Prior Publication Data
`
`US 2009/0002920 Al
`
`Jan. 1, 2009
`
`(Continued)
`OTHER PUBLICATIONS
`
`Partial English translation of JP 2-116720, published on Sep. 19,
`1990; Kind Code: U.
`
`Foreign Application Priority Data
`(30)
`Jun. 27,2007
`(IP)
`aeeecteeesecrseeteesees 2007-169175
`Mar. 28, 2008
`(IP)
`aeeceteeesecteesteesees 2008-085617
`
`(Continued)
`Primary Examiner—Eric Thomas
`(74) Attorney, Agent, or Firm—Keating & Bennett, LLP
`
`(51)
`
`Int. Cl.
`HOIG 4/228
`HOIG 1005
`
`(2006.01)
`(2006.01)
`
`(57)
`
`ABSTRACT
`
`boat aoeication eon seine|soe’
`Field
`of
`Classification
`Search
`...
`eats
`s
`lication
`file f
`1
`hho311, 303
`ee application
`hile
`tor complete search
`history.
`References Cited
`
`(58)
`
`(56)
`
`In an LW-reverse-type monolithic ceramic capacitor includ-
`ing external terminal electrodes each including a resistance
`component, internal electrodes include nickel or a nickel
`alloy, and the external terminal electrodes each includea first
`layer, a second layer provided on the first layer, and a third
`layer provided on the second layer. The first layer has a
`wrap-around portion extending from an end surface to prin-
`U.S. PATENT DOCUMENTS
`cipal surfaces and side surfaces ofa capacitor main body, and
`4.604.676 A
`8/1986 Sendaet al
`contains a glass component and a compound oxidethatreacts
`361/309
`5. 107.39.4A *
`4/1992 Naito etal ‘
`With Nior the Nialloy. The secondlayer coversthefirst layer
`5.496.560 A *
`6/1995 Amaya et al. 361/309
`
`such that the edgeofthe wrap-aroundportion ofthefirst layer
`5.712.758 A *
`1/1998 Amano etal...3561/3212
`remains exposed, and contains a metal. The third layer covers
`5,805,409 A *
`9/1908 Takahara etal. ............ 361/303
`
`6,259,593 BL* 7/2001 Moriwakiet al... 361/303__the edge of the wrap-aroundportion of the first layer and the
`6,310,757 BL* 10/2001 Tuzukietal.
`.....0.... 361/308.1
`Secondlayer, and is formed byplating.
`6,344,963 BL*
`2/2002 Moti... eee eeeeeeee 361/306.3
`6,381,118 BL*
`4/2002 Yokoyamaetal. ....... 361/308.1
`
`8 Claims, 4 Drawing Sheets
`
`<————1
`Ll
`>!
`27
`
`1
`
`12,13
`
`TH} &
`
`
`
`
`OOM!eeSSS
`
`
`
`
`
`
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`
`Exhibit 1004
`Exhibit 1004
`PGR2017-00010
`PGR2017-00010
`AVX CORPORATION
`AVX CORPORATION
`
`000001
`
`

`

`US 7,808,770 B2
`
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`5/2006 Ritter et al.
`7,054,136 B2
`7,304,831 B2* 12/2007 Yoshiietal.
`......0.... 361/321.2
`
`7,436,649 B2* 10/2008 Omura ....
`. 361/306.3
`2006/0234022 Al* 10/2006 Liuetal. wu... 428/210
`2007/0128794 Al
`6/2007 Kusanoetal.
`2007/0242416 Al* 10/2007 Saito etal... 361/321.1
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`JP
`JP
`JP
`wo
`
`08-097072 A
`09-148174 A
`2000-357627 A
`2002-217054 A
`2006/022258 Al
`
`4/1996
`6/1997
`12/2000
`8/2002
`3/2006
`
`OTHER PUBLICATIONS
`o.,
`.
`.
`.
`Official Communication issued in corresponding Japanese Patent
`Application No. 2008-085617, mailed on Oct. 6, 2009.
`
`JP
`
`06096986 A *
`
`4/1994
`
`* cited by examiner
`
`000002
`
`000002
`
`

`

`U.S. Patent
`
`Oct. 5, 2010
`
`Sheet 1 of 4
`
`US 7,808,770 B2
`
`FIG. 1
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`

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`U.S. Patent
`
`Oct. 5, 2010
`
`Sheet 2 of 4
`
`US 7,808,770 B2
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`U.S. Patent
`
`Oct. 5, 2010
`
`Sheet 3 of 4
`
`US 7,808,770 B2
`
`2
`
`4 1
`
`1
`
`2
`
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`

`U.S. Patent
`
`Oct. 5, 2010
`
`Sheet 4 of 4
`
`US 7,808,770 B2
`
`FIG. 4
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`US 7,808,770 B2
`
`2
`direction of the ceramic layers. In such LW-reverse-type
`monolithic ceramic capacitors, a current path of a capacitor
`main body is wide andshort, thereby decreasing the ESL.
`Another known example of a low-ESL monolithic ceramic
`capacitor is a multiterminal monolithic ceramic capacitor. In
`multiterminal monolithic ceramic capacitors, the current path
`inside a capacitor main bodyis separated into a plurality of
`paths, thereby decreasing the ESL.
`In low-ESL monolithic ceramic capacitors, the current
`path is wide and short or is separated as described above. As
`a result,
`the equivalent series resistance (ESR)
`is also
`decreased.
`
`10
`
`1
`MONOLITHIC CERAMIC CAPACITOR
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to a monolithic ceramic
`capacitor, and in particular, to an LW-reverse-type monolithic
`ceramic capacitor including external terminal electrodes each
`including a resistance component.
`2. Description of the Related Art
`In a power supply circuit, when a voltage variation in a
`powersupply line is increased by an impedancethatis present
`in the power supplyline or a ground, the operation of circuits
`to be driven becomesunstable, interference between the cir-
`cuits occurs due to the power supply circuit, or oscillation
`occurs. Consequently, a decoupling capacitor is usually con-
`nected between the power supply line and the ground. The
`decoupling capacitor decreases the impedance between the
`power supply line and the ground, thereby suppressing the
`variation in the power supply voltage and interference
`between the circuits.
`
`Onthe other hand, an increase in the capacitance ofmono-
`lithic ceramic capacitors has been required. In order to
`increase the capacitance of a monolithic ceramic capacitor,
`the number of ceramic layers and the number of laminated
`internal electrodes maybeincreased.In this case, the number
`of current paths is increased, thereby decreasing the ESR.
`Accordingly, in response to the requirements to decrease
`the ESL andincrease the capacitance, the ESR of monolithic
`ceramic capacitors tends to be further decreased.
`However, it is known that when the ESR of a capacitoris
`in communication equipment such as a cell
`Recently,
`excessively decreased, a mismatch of impedance occurs in a
`phone and information processing equipmentsuch as a per-
`circuit and a dampedoscillation called “ringing”in which the
`sonal computer, as the speed of signals has been increased in
`rising of a signal waveform deformseasily occurs. The ring-
`order to allow a large amount of informationto be processed,
`ing may cause a malfunction of an IC because of disordered
`the clock frequency of an IC used hasalso increased. Accord-
`signals.
`ingly, noise that primarily includes harmonic wave compo-
`In addition, when the ESR of a capacitor is excessively
`nents is often generated. Therefore, it has become necessary
`decreased,
`the impedance-frequency characteristic of the
`to provide stronger decoupling in an IC powersupplycircuit.
`capacitor becomes excessively steep near the resonancefre-
`In order to increase the decouplingeffect, it is effective to
`quency. Morespecifically, the valley of the impedance curve
`use a decoupling capacitor having an excellent impedance-
`becomesexcessively deep. Consequently, it may be difficult
`frequency characteristic. An example of such a decoupling
`to absorb noise over a wide frequency range.
`capacitor is a monolithic ceramic capacitor. Because ofits
`In order to prevent ringing or to broaden the impedance-
`low equivalent series inductance (ESL),
`the monolithic
`frequency characteristic, a resistance element may be con-
`ceramic capacitor has an excellent noise-absorbing effect
`nected in series to a line. In addition, recently, it has been
`over a wide frequency range as comparedto an electrolytic
`required that a capacitor itself includes a resistance compo-
`capacitor.
`nent, and thus, a method of controlling the ESR of such a
`Another function of a decoupling capacitor is to supply
`capacitor using this technique hasattracted attention.
`electric charges to an IC. A decoupling capacitor is usually
`For example, Japanese Unexamined Patent Application
`disposed in the vicinity of an IC. When a voltage variation
`Publication No. 2004-47983 (document’983) and PCT Pub-
`occurs in a power supply line, electric charges are rapidly
`lication No. WO 2006/022258 pamphlet (document ’258)
`supplied from the decoupling capacitor to the IC, thus pre-
`have disclosed that a resistance component is included in
`venting a delay of the IC.
`external terminal electrodesthat are electrically connected to
`When a charge and a discharge occur in a capacitor, a
`internal electrodes, thereby controlling the ESR. More spe-
`counter-electromotive force represented by a
`formula
`cifically, document °983 discloses a thick-film resistance
`dV=L-di/dt is generated in the capacitor. With a large dV, the
`including RuO,. Document ’258 discloses that paste includ-
`supply speed of electric charges to the IC is decreased. With
`ing a material having a relatively high specific resistance,
`an increase in the clock frequency of an IC, the amount of
`such as ITO,is baked on a capacitor main body. However, the
`current variation per unit time di/dt tends to increase. Accord-
`techniques described in documents ’983 and ’258 have prob-
`ingly, in order to decrease the value of dV, it is necessary to
`lemsto be solved as described below.
`decrease the inductanceL.Forthis purpose,it is desirable to
`According to the technique disclosed in document 983, a
`further decrease the ESL of a capacitor.
`plating film is formed directly on an underlayerincluding the
`A known example of a low-ESL monolithic ceramic
`resistance component. However, unlike metalparticles, neck-
`capacitor in which the ESL is further decreased is an LW-
`ing does not occur in metal oxide particles, such as RuO,
`reverse-type monolithic ceramic capacitor. In typical mono-
`particles, includedin the underlayer by baking. Therefore, the
`lithic ceramic capacitors, the dimension (dimension W) of
`density of the resulting film is not significantly high. Conse-
`each end surface of a capacitor main body in the extending
`quently, a plating solution or moisture easily intrudes into the
`direction of the ceramic layers, the end surface having an
`external terminal electrode thereon,is less than the dimension
`film, thus causing a problem of reducedreliability.
`In the technique disclosed in document’258, a first layer
`(dimension L) of each side surface ofthe capacitor main body
`including a resistance componentis completely covered with
`in the extending direction of the ceramic layers, the side
`a second layer composed ofa thick film including a metal
`surface being adjacent to the end surfaces. In contrast, in
`
`LW-reverse-type monolithic ceramic capacitors, the dimen- such as Cu, andaplating film is formed on the secondlayer.
`sion (dimension W) of each end surface in the extending
`In this configuration, since the first layer is covered with the
`direction of the ceramic layers, the end surface having an
`dense secondlayer, the reliability ofthe capacitor is improved
`external terminal electrode thereon, is greater than the dimen-
`as compared to the capacitor disclosed in document 983.
`However, since the entire thickness of each of the external
`sion (dimension L) of each side surface in the extending
`000007
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`US 7,808,770 B2
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`3
`4
`Furthermore, since the secondlayer is arranged such that
`terminal electrodesis increased by formingthefirst layer and
`the edge of the wrap-aroundportion ofthefirst layer remains
`the secondlayer, the dimensions of the monolithic ceramic
`exposed, a plating solution or moisture may easily intrude
`capacitor in the in-plane directions and the height direction
`from the edge of the wrap-around portion ofthe first layer.
`increase. Accordingly, it is difficult to reduce the size of the
`However, the distance between the edge of the wrap-around
`monolithic ceramic capacitor. This problem tends to be par-
`ticularly troublesome in LW-reverse-type monolithic ceramic
`portion and a capacitance-forming portion of the internal
`
`capacitors, which havealarge area of external terminal elec- electrodes is sufficiently large, and thus, the plating solution
`trodes.
`or moisture does not easily reach the capacitance-forming
`An external terminal electrode is formed on each end sur-
`portion. Therefore, the reliability of the monolithic ceramic
`capacitor is not significantly decreased.
`face ofa capacitor main body.In orderto achievesatisfactory
`In addition, since the second layer does not completely
`mountability, the external terminal electrode typically has a
`coverthe first layer and is formed such that the edge of the
`wrap-around portion which is formedso as to extend from an
`wrap-aroundportion remains exposed,this structure enables
`end surface to principal surfaces and side surfaces. As
`a decrease in the thickness of the external terminal electrode
`described in document ’258, when thefirst layer is com-
`pletely covered with the second layer, the second layer is
`affected by a variation in the thickness of the first layer.
`Therefore, it is difficult to stabilize the dimensions of the
`wrap-aroundportion. If the dimensions of the wrap-around
`portion vary, the mountability may be adversely affected.
`
`20
`
`SUMMARYOF THE INVENTION
`
`30
`
`45
`
`To overcome the problems described above, preferred
`embodiments of the present invention provide an LW-re-
`verse-type monolithic ceramic capacitor including external
`terminal electrodes each including a resistance component,
`the structure being suitable for improving the mountability of
`the LW-reverse-type monolithic ceramic capacitor without
`decreasing the reliability thereof.
`A monolithic ceramic capacitor according to a preferred
`embodimentof the present invention includes a substantially
`rectangular parallelepiped capacitor main body including a
`plurality of laminated ceramic layers and having a pair of
`principal surfaces facing each other, a pair of side surfaces
`facing each other, and a pair of end surfaces facing each other;
`at least one pair of internal electrodes provided inside the
`capacitor main body and each extending to one of the end
`surfaces; and a pair of external terminal electrodes provided
`on the end surfaces of the capacitor main body and each
`electrically connected to any of the internal electrodes,
`wherein the dimension of each end surface in the extending
`direction of the ceramic layers is greater than the dimension
`of each side surface in the extending direction of the ceramic
`layers.
`In order to solve the problemsdescribed above, the mono-
`lithic ceramic capacitor has the following uniquestructure.
`Specifically, the internal electrodes include nickel (Ni) ora
`nickel (Ni) alloy. Each of the external terminal electrodes
`includesa first layer, a second layer providedonthefirst layer,
`and a third layer provided on the second layer. Thefirst layer
`has a wrap-around portion extending from one of the end
`surfaces to the principal surfaces and the side surfaces, and
`includes a glass component and a compound oxidethat reacts
`with the Ni or the Ni alloy. The second layer covers thefirst
`layer suchthat the edge ofthe wrap-aroundportion ofthefirst
`layer remains exposed, and includes a metal. The third layer
`covers the edge of the wrap-aroundportion ofthe first layer
`and the secondlayer, and is formedbyplating.
`Accordingto a preferred embodimentofthe present inven-
`tion, since the secondlayer is arranged such that the edge of
`the wrap-around portion of thefirst layer remains exposed,
`the dimensions of the wrap-around portion of the external
`terminalelectrode are definedby thefirst layer. As a result, the
`dimensionsof the wrap-aroundportion of the external termi-
`nal electrode are consistent. Thus, satisfactory mountability
`of the monolithic ceramic capacitor can be reliably achieved.
`
`at the wrap-around portion. Consequently, the size of the
`monolithic ceramic capacitor can be reduced accordingly.
`In order to reduce the size of the monolithic ceramic
`
`capacitor, a first layer having a small thickness may be
`formed. However, it is difficult to use this structure from the
`standpoint ofthe ESR. Whenthe capacitor main bodyis cut in
`a direction substantially parallel to a side surface thereof and
`the cross section is viewed, the thickness at both ends of the
`first layer is less than the thickness at the center ofthe first
`layer. Therefore, the current path at both endsofthefirst layer
`is reduced.In addition to this structure, when the thickness of
`the first layer is reduced, the current path at both ends of the
`first layer is further reduced. Consequently, even though a
`material having a high specific resistance is used asthe first
`layer, current concentratesat an area in which the current path
`is short. In such a case, a desired ESR may notbe achieved.
`Furthermore, according to a preferred embodimentof the
`present invention, the internal electrodes include nickel (Ni)
`ora nickel (Ni)alloy, andthefirst layer of each ofthe external
`terminal electrodes includes a compound oxide that reacts
`with Ni or the Nialloy. Accordingly,a satisfactory connection
`state can be provided between the internal electrodes and the
`external terminalelectrodes.
`Other features, elements, characteristics and advantages of
`the present invention will become more apparent from the
`following detailed description of preferred embodiments of
`the present invention with referenceto the attached drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG.1 is a perspective view showing a monolithic ceramic
`capacitor according to a preferred embodimentofthe present
`invention.
`FIG.2 is a cross-sectional view of the monolithic ceramic
`capacitor taken along line A-A in FIG.1.
`FIG. 3A is a view showinga cross section through which a
`first internalelectrode in a capacitor main body shown in FIG.
`1 passes.
`FIG.3B is a view showing a cross section through which a
`secondinternal electrode in the capacitor main body shownin
`FIG.1 passes.
`FIG. 4 is a partially enlarged cross-sectional view of a
`second external terminal electrode includedin the monolithic
`
`ceramic capacitor shown in FIG.1.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`FIG.1 is a perspective view showing a monolithic ceramic
`capacitor 1 according to a preferred embodiment of the
`present invention. FIG. 2 is a cross-sectional view of the
`monolithic ceramic capacitor 1 taken along line A-A in FIG.
`1.
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`US 7,808,770 B2
`
`5
`The monolithic ceramic capacitor 1 includes a capacitor
`main body 3 including a plurality of laminated ceramic layers
`2, at least one pair of internal electrodes 4 and 5 provided
`inside the capacitor main body 3, a first external terminal
`electrode 6, and a second external terminal electrode 7. The
`first external terminal electrode 6 and the second external
`terminal electrode 7 are provided on outer surfaces of the
`capacitor main body 3 so as to face each other.
`Each of the ceramic layers 2 in the capacitor main body 3
`is preferably made of, for example, a dielectric ceramic
`including, as a main component, BaTiO,, CaTiO;, SrTi0,,
`CaZrO,, or other suitable material. An auxiliary component
`such as a manganese (Mn) compound, an iron (Fe) com-
`pound, a chromium (Cr) compound,a cobalt (Co) compound,
`or anickel (Ni) compound maybe added to the main compo-
`nent. The thickness of each of the ceramic layers 2 is prefer-
`ably, for example, in the range of about 1 um to about 10 um,
`for example.
`The capacitor main body 3 preferably has a substantially
`rectangular parallelepiped shape havinga first principal sur-
`face 8 and a second principal surface 9 facing each other, a
`first side surface 10 and a secondside surface 11 facing each
`other, and a first end surface 12 and a second end surface 13
`facing each other.
`In the capacitor main body 3, the dimension (dimension W)
`of eachofthe first end surface 12 and the second surface 13 in
`
`10
`
`15
`
`20
`
`25
`
`6
`capacitance provided by the monolithic ceramic capacitor 1.
`Thus, the ESR of the monolithic ceramic capacitor 1 can be
`increased.
`
`Note that the term “resistance component” means a com-
`ponent havinga relatively high specific resistance excluding
`metals and glass included in typical external terminal elec-
`trodes. Morespecifically, the resistance componentis prefer-
`ably a metal oxide excluding glass, for example. Examples of
`the metal oxide used in this preferred embodiment include
`compound oxides such as an In—Sn compoundoxide (ITO),
`a La—Cu compoundoxide, a Sr—Fe compoundoxide, anda
`Ca—Sr—Ru compound oxide. These compound oxides such
`as an In—Sn compound oxide (ITO), a La—Cu compound
`oxide, a Sr—Fe compound oxide, and a Ca—Sr—Ru com-
`pound oxide havesatisfactory reactivity with Ni. Therefore,
`as described above, a satisfactory connection between the
`internal electrodes 4 and 5 including Ni anda Ni alloy and the
`external terminal electrodes 6 and 7 can be achieved.
`Glass is preferably addedto thefirst layer 14. For example,
`B—Si glass, B—Si—Zn glass, B—Si—Zn—Baglass, or
`B—Si—7n—Ba—Ca—Alglass can be used as the glass.
`Whenglass is added tothefirst layer 14, the volumeratio of
`the resistance component to the glass is preferably in the
`range of about 30:70 to about 70:30, for example.
`The first layer 14 may include a metal such as Ni, Cu, Mo,
`Cr, or Nb and a metal oxide such as Al,O;, TiO,, ZrO,, or
`ZnO,. These substances adjust the specific resistance pro-
`vided bythefirst layer 14 and the density ofthefirst layer 14.
`Morespecifically, the addition of the above metal decreases
`the specific resistance, whereas the addition of the above
`metal oxide increases the specific resistance. The addition of
`Ni, Cu, Al,O,, or TiO, accelerates densification of thefirst
`layer 14. On the other hand,the addition of Mo, Cr, Nb, ZrO,,
`or ZnO, suppresses densification of the first layer 14. Note
`that suppression of densification means to prevent the gen-
`eration of a blister due to excessivefiring ofthe first layer 14.
`The first layer 14 includes a wrap-around portion 17
`extending from the end surface 12 or 13 to the principal
`surfaces 8 and 9 and the side surfaces 10 and 11. The edge of
`the wrap-aroundportion 17 is covered with the third layer 16
`as described below. Whenthe third layer 16 is formed by
`electrolytic plating, the first layer 14 preferably has a conduc-
`tivity to the extent that a plated film can be precipitated.
`Accordingly, whenelectrolytic plating is performed, a metal
`such as Niis preferably addedtothefirst layer 14 as described
`above. Morespecifically, the specific resistance of thefirst
`layer 14 is preferably in the range of about 0.1 Q-cm to about
`1.0 Q-cm, for example.
`In this preferred embodiment, the dimensionsof the wrap-
`around portion of the external terminal electrodes 6 and 7 are
`defined by the wrap-around portion 17 ofthe first layer 14.
`Accordingly, the dimensions of the wrap-around portion of
`the external terminal electrodes 6 and 7 are substantially
`consistent.
`
`the extending direction of the ceramic layers 2 is greater than
`the dimension (dimension L)of each ofthefirst side surface
`10 and the secondside surface 11 in the extending direction of
`the ceramic layers 2. The dimension W is preferably in the
`range of about 1.5 to about 2.5 times the dimension L, for
`example. The first external terminal electrode 6 is provided on
`the first end surface 12, and the second external terminal
`electrode 7 is provided on the second end surface 13.
`FIG. 3A is a view showing a cross section through which
`the first internal electrode 4 in the capacitor main body 3
`passes, and FIG.3B is a view showing a cross section through
`which the second internal electrode 5 in the capacitor main
`body 3 passes.
`As shown in FIG.3A,thefirst internal electrode 4 extends
`to the first end surface 12 of the capacitor main body 3.
`Accordingly, the first internal electrode 4 is electrically con-
`nectedto the first external terminal electrode 6. On the other
`hand, as shown in FIG.3B, the second internal electrode 5
`extends to the second end surface 13 of the capacitor main
`body 3. Accordingly, the second internal electrode 5 is elec-
`trically connected to the second external terminal electrode 7.
`Asis apparent from FIG.2, the first internal electrodes 4 and
`the secondinternal electrodes 5 are alternately disposed in the
`laminating direction, with the ceramic layers 2 therebetween.
`Nickel (Ni) or a nickel (Ni) alloy is preferably used as a
`conductive component included in the internal electrodes 4
`and 5. The thickness of eachofthe internal electrodes 4 and 5
`is preferably in the range of about 1 um to about 10 um, for
`The secondlayer 15 coversthefirst layer 14 such that the
`example.
`edge of the wrap-around portion 17 of the first layer 14
`Thefirst external terminal electrode 6 includesa first layer
`remains exposed. The second layer 15 improves moisture
`14 provided on thefirst end surface 12 of the capacitor main
`resistance anda plating film-forming property.
`body 3, a second layer 15 provided on the first layer 14, and a
`The second layer 15 primarily includes a metal and is
`third layer 16 provided on the secondlayer 15. Similarly, the
`formed by applying conductive paste including a metal pow-
`second external terminal electrode 7 includesa first layer 14
`der and baking the conductive paste. Examples of the metal
`provided on the second end surface 13 of the capacitor main
`included in the second layer 15 include Cu, Ni, Ag, Pd, a
`body 3, a second layer 15 provided on the first layer 14, and a
`Ag—Pd alloy, and Au, for example. In addition, glass is
`third layer 16 provided on the secondlayer 15.
`preferably added to the second layer 15. As this glass, the
`Thefirst layer 14 includes a resistance componentandis
`same glass as that included in the first layer 14 or glass
`formed by applyingresistance paste including the resistance
`including the same main componentas that included in the
`componentfollowed by baking. By formingthefirst layer 14,
`glassin the first layer 14 is preferably used.
`the resistance component
`is provided in series with the
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`Furthermore, the thickness T1 of the first layer 14 is pref-
`Since the secondlayer 15 is arranged such that the edge of
`erably in the range of about 20 um to about 30 um, for
`the wrap-around portion 17 of the first layer 14 remains
`example, the thickness T2 ofthe second layer 15 is preferably
`exposed,the size ofthe monolithic ceramic capacitor 1 can be
`in the range of about 20 um to about 30 um, for example, and
`reduced.In this structure, although a portionofthefirst layer
`the thickness T3 ofthe third layer 16 is preferably in the range
`14 is exposed, the position of the edge of the wrap-around
`ofabout 5 tum to about 15 um, for example. Ifthe thickness T1
`portion 17 is spaced from the positions of the internal elec-
`of thefirst layer 14 is outside of the above range of about 20
`trodes 4 and 5, which define a capacitance-forming portion.
`uum to about 30 um andless than about 20 um,the variation in
`Accordingly, even if a plating solution or moisture intrudes
`the film thickness ofthefirst layer 14 is increased, and thus,
`from the edge of the wrap-around portion 17, the plating
`the variation in the ESR is increased. Onthe other hand,ifthe
`solution or moisture does not reach the capacitance-forming
`thickness T1 ofthe first layer 14 is greater than about 30 um,
`portion. Therefore, this structure prevents a decrease in the
`in a production process described below,it is necessary to dip
`reliability.
`the capacitor main body 3 into resistance paste more deeply.
`Thethird layer 16 is arrangedso as to cover the edge of the
`In such a case,the resistance paste is applied on the capacitor
`wrap-around portion 17 of the first layer 14 and the second
`
`layer 15. The third layer 16 is preferably formedby plating. main body 3 inastate in which the capacitor main body 3 is
`When the monolithic ceramic capacitor 1 is mounted using
`slanted. Asa result, the length L1 of the wrap-aroundportion
`solder, the third layer 16 preferably has a two-layer structure
`17 ofthe first layer 14 mayvary.
`including a Niplating film and a Sn plating film disposed on
`An example of a method of producing the above mono-
`the Ni plating film, for example. When the monolithic
`lithic ceramic capacitor 1 will now be described.
`ceramic capacitor 1 is mounted with a conductive adhesive or
`First, ceramic green sheets used for the ceramic layers 2,
`by wire bonding,the third layer 16 preferably has a two-layer
`conductive paste for the internal electrodes 4 and 5, and
`structure including a Ni plating film and an Auplating film
`resistance paste and conductive paste for the external terminal
`disposed on the Niplatingfilm, for example. When the mono-
`electrodes 6 and 7 are prepared. The ceramic green sheets, the
`lithic ceramic capacitor 1 is embeddedin a resin substrate,at
`conductive paste for the internal electrodes 4 and 5, and the
`least the outermost layer of the third layer 16 is preferably
`conductive paste for the external terminal electrodes 6 and 7
`formed by copper (Cu) plating, for example.
`include binders and solvents. Known organic binders and
`The structure of the third layer 16 is not limited to the
`organic solvents can be used as the binders andthe solvents,
`two-layer structure described above. The third layer 16 may
`for example.
`includea single layer or three or more layers. Preferably, the
`Next, the conductive paste for the internal electrodes 4 and
`thickness of each layer of the plating films defining the third
`5 is printed on each of the ceramic green sheets so as to have
`layer 16 is in the range of about 1 um to about 10 um, for
`a predetermined pattern by, for example, a screen printing
`example. Furthermore, a resin layer for relieving stress may
`method. Accordingly, ceramic green sheets having a conduc-
`be provided between the secondlayer 15 andthe third layer
`tive paste film for eachof the inner electrodes 4 and 5 thereon
`16.
`are obtained.
`Next, a predetermined numberof ceramic green sheets on
`which the conductive paste film is formed as described above
`are laminated in a predetermined order. A predetermined
`numberof ceramic green sheets for outer layers, the green
`sheets not having conductive paste film thereon, are further
`laminated on the top and the bottom ofthe laminated ceramic
`green sheets. Thus, an unfired mother laminate is prepared.
`The unfired mother laminate is optionally pressure-bondedin
`the laminating direction by, for example, isostatic pressing.
`Next, the unfired mother laminate is cut so as to have a
`predeterminedsize, thus allowing an unfired capacitor main
`body 3 to be prepared.
`The unfired capacitor main body3 is then fired. The firing
`temperature depends on the ceramic material contained in the
`ceramic green sheets and the metal material contained in the
`conductive paste films, but is preferably selected from the
`range of about 900° C. to about 1,300° C., for example.
`Next, the resistance paste is applied on the first end surface
`12 and the second end surface 13 ofthe fired capacitor main
`body 3 and then baked to form thefirst layer 14 for thefirst
`external terminalelectrode 6 and the second external terminal
`electrode 7. This baking temperature is preferably in the
`range of about 700°C. to about 900° C., for example. Regard-
`ing the atmosphere during baking, an atmosphere such as air
`or N, is appropriately selected in accordance with the com-
`ponentof the resistance paste.
`Subsequently, the conductive paste for the external termi-
`nal electrodes 6 and 7 is applied onthefirst layer 14 and then
`baked to form the secondlayer 15. This baking temperatureis
`preferably in the range of about 700° C. to about 900° C., for
`example. Furthermore, this baking temperature of the con-
`ductive paste is preferably less than the baking temperature
`for formingthe first layer 14. Regarding the atmosphere dur-
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`FIG.4 is a partially enlarged cross-sectional view of the
`second external terminal electrode 7. Althoughthefirst exter-
`nal terminal electrode 6 is not shown in FIG.4, the first
`external terminalelectrode 6 has substantially the samestruc-
`ture as the second external terminal electrode 7.
`In FIG. 4, examples of dimensionsof the second external
`terminal electrode 7 are shown. Specifically, the length of the
`wrap-aroundportion 17 ofthe first layer 14 is denoted by L1,
`and the length of the exposed edge ofthe first layer 14 is
`denoted by L2. The thickness of the thickest portion of the
`fir