EP1281184A1 - Condensateur et procede de fabrication - Google Patents

Condensateur et procede de fabrication

Info

Publication number
EP1281184A1
EP1281184A1 EP01942990A EP01942990A EP1281184A1 EP 1281184 A1 EP1281184 A1 EP 1281184A1 EP 01942990 A EP01942990 A EP 01942990A EP 01942990 A EP01942990 A EP 01942990A EP 1281184 A1 EP1281184 A1 EP 1281184A1
Authority
EP
European Patent Office
Prior art keywords
electrode
capacitor
layers
ceramic material
electrode metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01942990A
Other languages
German (de)
English (en)
Inventor
Christl Mead
Peter Urdl
Günter Engel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TDK Electronics AG
Original Assignee
Epcos AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Epcos AG filed Critical Epcos AG
Publication of EP1281184A1 publication Critical patent/EP1281184A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
    • H01G4/1218—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates
    • H01G4/1227—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates based on alkaline earth titanates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material

Definitions

  • the invention relates to a capacitor with superimposed electrode layers which have an electrode metal and which are insulated from one another by dielectric layers made of ceramic material.
  • the electrode layers are sintered together with the dielectric layers.
  • the invention further relates to a method for producing the capacitor.
  • Capacitors of the type mentioned at the outset are known from US Pat. No. 4,027,209, in which the electrode layers have silver as the electrode metal. Silver is used in this case because of its excellent conductance. Furthermore, the electrode layers have an additional metal, which is usually palladium. By adding the palladium to silver, the melting point of the electrode layers is raised in a suitable manner, so that the electrode layers can be sintered together with the dielectric layers at a temperature exceeding the melting point of the electrode metal.
  • the known capacitors have the disadvantage that they are expensive to manufacture due to the relatively high proportion of palladium, since the palladium is very expensive to procure.
  • the known capacitors also have the disadvantage that the silver diffuses into the ceramic material due to the high temperature during sintering. As a result, the electrode layers are thinned out or even disappear completely in places. This leads to an increase in the effective resistance of the electrode layers and thus of the capacitor, as a result of which the losses generated in the capacitor increase. Since in the case of electrode layers that completely disappear in places, there are smaller electrode areas in the capacitor, the capacitance of the capacitor also drops significantly, which is undesirable due to the reduced volume utilization.
  • Capacitors are also known in which the disappearance of the electrode layers is countered by arranging the electrode layers with a large layer thickness of approximately 5 ⁇ m in the capacitor.
  • a thick electrode layer has the disadvantage that the capacitor has a larger volume without at the same time increasing the capacitance of the capacitor.
  • the capacitor provided with electrode layers of a greater layer thickness thus has a poorer volume utilization.
  • the aim of the present invention is therefore to provide a capacitor in which the diffusion of electrode metal from the electrode layer during sintering can be reduced.
  • the invention provides a capacitor with superimposed electrode layers which have an electrode metal and which are insulated from one another by dielectric layers, a ceramic material continuously doped with electrode metal being used as the dielectric layer.
  • the capacitor according to the invention has the advantage that a diffusion equilibrium can be set by the proportion of electrode metal in the ceramic material, which prevents the diffusion of electrode metal into the ceramic material during a sintering process necessary to complete the capacitor.
  • a suitable proportion of electrode metal is, for example, 0.01 to 5 percent by weight of the ceramic material.
  • dielectric layers are particularly advantageous which have a homogeneously distributed proportion of electrode metal.
  • the homogeneity of the distribution must be considered on a scale that cannot distinguish the individual crystallites that make up the ceramic.
  • a capacitor is particularly advantageous in which the ceramic material has a polycrystalline structure with crystallites and in which at least 90% of the electrode metal portion of the ceramic material is located within an edge layer of the crystallites, the thickness of which is a quarter of the greatest extent of the crystallites. This distribution of the electrode metal in the ceramic material brings about a particularly good reduction in the diffusion of electrode metal into the ceramic material.
  • the electrode metal is mainly between the grain boundaries of the crystallites forming the ceramic material place. This can also achieve a reduction in diffusion during sintering.
  • the reduced diffusion of electrode metal enables the production of capacitors in which, with a dielectric layer thickness between 5 and 60 ⁇ m, an electrode layer thickness of at most 1.5 ⁇ m is sufficient to keep a homogeneous, continuous electrode layer even after sintering.
  • Electrode layers have the advantage that, in addition to a reduced consumption of metal material, which plays a role in particular when using noble metals such as silver or palladium, a reduced delamination due to a reduced difference in the shrinkage behavior of the electrode and dielectric layer is observed.
  • an electrode layer of small thickness has the advantage of a higher utilization of the volume with the capacitance remaining the same.
  • the invention enables a capacitor in which the electrode layers melt at a temperature that differs only slightly from the sintering temperature.
  • the proportion of expensive additional metal in the electrode layers which increases the melting point of the electrode layers can be reduced. This results in an improved economy of the capacitor according to the invention.
  • silver can be considered as the electrode metal.
  • palladium is used particularly advantageously as the additional metal, since it can raise the melting point of the electrode layer in a suitable manner.
  • Weight ratio of silver / palladium is 70/30, a weight ratio is sufficient for the capacitor according to the invention. nis silver / palladium between 75/25 and 90/10.
  • the increased proportion of silver in the electrode layer has the advantage that the effective resistance of the capacitor is reduced by the better conductivity compared to palladium, which leads to lower losses in the capacitor. It also reduces the cost of the capacitor because silver is much cheaper than palladium.
  • the ceramic material of the capacitor can preferably contain barium titanate, which due to its high dielectric constant is very well suited as a dielectric for capacitors.
  • the ceramic material can contain between 0.1 and 15 percent by weight of B2O3, SiC> 2, AI2O3, ZnO, or also Bi2Ü3, Nb2Ü5 or Nd2Ü3.
  • a proportion of electrode metal in the ceramic material between 0.5 and 1.5 percent by weight has proven to be particularly suitable for establishing a diffusion equilibrium that prevents diffusion. This applies in particular if silver is used as the electrode metal.
  • the capacitor In order to achieve a good lamination of the electrode layers with the dielectric layers and thereby a high mechanical stability of the capacitor, it is particularly advantageous to sinter the capacitor at a temperature of more than 1000 ° C. In a particularly preferred embodiment, the sintering temperature is even higher; it is 1100 ° C.
  • the invention specifies a method for producing a capacitor, in which a liquid slip is first prepared from powdered ceramic material. Electrode metal in the form of electrode metal oxide grains is added to this slip. These electrode metal oxide grains can be Ag2 ⁇ grains, for example.
  • the method for producing the capacitor is particularly advantageous if the electrode metal is mixed uniformly with the slip, so that a diffusion equilibrium is set uniformly at all points.
  • the electrode metal with a grain size distribution that is adapted to the polycrystalline ceramic material.
  • the slip is processed into a dielectric layer in the form of a ceramic film. An electrode layer is then applied to this dielectric layer.
  • the electrode layer can be applied, for example, by screen printing a paste, which is the
  • the advantage is that the electrode layer can be applied in a structured manner to the dielectric layer, which enables the parallel production of several electrode layers / dielectric layer stacks.
  • the electrode layer is then sintered together with the dielectric layer.
  • each electrode layer borders on two dielectric layers, which increases the problem of diffusion.
  • the method according to the invention can therefore be used particularly advantageously here.
  • a method for producing a capacitor is advantageous in which the electrode layers and dielectric layers stacked one above the other are pressed together before sintering. Pressing the layers together creates a mechanically particularly stable structure for the capacitor.
  • a temperature of more than 1000 ° C., for example 1100 ° C. is selected in a particularly advantageous manner. This has the advantage that the capacitor produced with it has particularly good mechanical and electrical properties.
  • the figure shows a capacitor according to the invention in a schematic longitudinal section.
  • the figure shows a capacitor as an SMD-compatible component with electrode layers 1 lying one above the other
  • Electrode metal and which are separated from each other by dielectric layers 2 made of ceramic material.
  • Metallizations 3 are arranged on the end faces of the capacitor, each electrode layer 1 being electrically connected to exactly one of these metallizations 3.
  • the metallization 3 can be, for example, a layer stack made of silver, Nikkei and tin, which is particularly easy to solder.
  • the tin layer is the outermost layer that is electrodeposited on the nickel layer.
  • the capacitor shown in the figure is suitable for a voltage of 50 V and has a capacitance of 10 nF. It corresponds to the so-called X7R characteristic, which means that its capacity fluctuates by less than 15% within a temperature range from -55 ° C to 125 ° C.
  • the dielectric layers 2 used for the capacitor have a dielectric constant of 2500.
  • the geometric dimensions are approximately 2.0 mm in length, 1.6 mm in width and 0.8 mm in height.
  • the invention is not limited to the exemplary embodiment shown, but is defined in its most general form by claims 1 and 9.

Landscapes

  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Ceramic Capacitors (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)

Abstract

L'invention concerne un condensateur comportant des couches d'électrodes superposées (1) présentant un métal d'électrode, et isolées les unes par rapport aux autres au moyen de couches diélectriques (2) en matériau céramique. Selon l'invention, le matériau céramique présente une fraction de métal d'électrode et les couches d'électrodes (1) sont frittées avec les couches diélectriques (2). Le dopage à l'argent de la céramique X7R permet de réduire les pertes d'argent au niveau de l'électrode intérieure. En même temps, la teneur en palladium de l'électrode intérieure peut être réduite. L'invention concerne également un procédé de fabrication du condensateur selon l'invention.
EP01942990A 2000-05-12 2001-04-30 Condensateur et procede de fabrication Withdrawn EP1281184A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE2000123360 DE10023360A1 (de) 2000-05-12 2000-05-12 Kondensator und Verfahren zu dessen Herstellung
DE10023360 2000-05-12
PCT/DE2001/001628 WO2001086672A1 (fr) 2000-05-12 2001-04-30 Condensateur et procede de fabrication

Publications (1)

Publication Number Publication Date
EP1281184A1 true EP1281184A1 (fr) 2003-02-05

Family

ID=7641842

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01942990A Withdrawn EP1281184A1 (fr) 2000-05-12 2001-04-30 Condensateur et procede de fabrication

Country Status (4)

Country Link
EP (1) EP1281184A1 (fr)
AU (1) AU2001265761A1 (fr)
DE (1) DE10023360A1 (fr)
WO (1) WO2001086672A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10262778B2 (en) 2015-11-27 2019-04-16 Epcos Ag Multilayer component and process for producing a multilayer component

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4027209A (en) * 1975-10-02 1977-05-31 Sprague Electric Company Ceramic capacitor having a silver doped dielectric of (Pb,La)(Zr,Ti)O3
US4219866A (en) * 1979-01-12 1980-08-26 Sprague Electric Company Ceramic capacitor having a dielectric of (Pb,La) (Zr,Ti)O3 and BaTiO3
JPH0666219B2 (ja) * 1989-02-22 1994-08-24 株式会社村田製作所 積層セラミックスコンデンサ
JPH0719964B2 (ja) * 1990-08-08 1995-03-06 日本電気株式会社 銀系配線セラミック基板
DE4141648C2 (de) * 1990-12-17 1997-01-09 Toshiba Kawasaki Kk Keramischer Kondensator
DE4425815C1 (de) * 1994-07-21 1995-08-17 Demetron Gmbh Edelmetallhaltige Resinatpaste zur Herstellung von keramischen Vielschichtkondensatoren
JPH11171645A (ja) * 1997-12-09 1999-06-29 Hitachi Metals Ltd 電子部品

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0186672A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10262778B2 (en) 2015-11-27 2019-04-16 Epcos Ag Multilayer component and process for producing a multilayer component
US10566115B2 (en) 2015-11-27 2020-02-18 Epcos Ag Multilayer component and process for producing a multilayer component

Also Published As

Publication number Publication date
WO2001086672A1 (fr) 2001-11-15
AU2001265761A1 (en) 2001-11-20
DE10023360A1 (de) 2001-11-29

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