• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a ceramic material for capacitors. In order to achieve reduced self-heating when the material is used in multilayer capacitors with antiferroelectric behavior and high dielectric constant, a ceramic material of the formula [Pb (1-r) (BaxSryCaz) r] (1-1.5a-1.5b-0 , 5c) (XaYb) Ac (Zr1-dtid) O3 wherein X and Y are each a rare earth metal selected from the group consisting of La, Nd, Y, Eu, Gd, Tb, Dy, Ho, Er and / or Yb; A represents a monovalent ion; x + y + z = 1; x and / or y and / or z> 0; 0 <r≤0.3; 0 ≤ d ≤ 1; 0 ≤ a ≤ 0.2; 0 ≤ b ≤ 0.2; 0 ≤ c ≤ 0.2 proposed.
    公开号:AT515462A1
    申请号:T50116/2014
    申请日:2014-02-17
    公开日:2015-09-15
    发明作者:
    申请人:Engel Guenter Dipl Ing Dr；
    IPC主号:
    专利说明:

    Ceramic material and capacitor with the same
    The invention relates to a ceramic material.
    Furthermore, the invention relates to the use of such a material.
    Finally, the invention comprises a capacitor, in particular a multilayer capacitor.
    Capacitors are used in many areas of electrical engineering, for example in AC / DC converters for motor drives, but also, for example, for voltage increase, voltage reduction and / or voltage stabilization in DC / DC circuits. In such applications semiconductor switches with diodes (so-called "inverter circuit") and a further circuit are often provided, wherein a capacitor is arranged between these circuits, which is also referred to as a DC link capacitor. In this case, series or parallel circuits of several capacitors are possible to increase voltage and current characteristics.
    In the case of the mentioned intermediate circuit capacitors, the capacitor arranged between the other circuits has the task of keeping the intermediate circuit voltage constant both in the case of rapid and magnitude-dependent changes in the operating variables current and voltage. In general, the problem arises that the possibilities for a design of the capacitor due to its environment by the semiconductors and specifications by the substrate and required leads are limited. A particular problem in this connection is that in capacitors desired ideal characteristics of non-ideal secondary properties in circuits with semiconductor elements are accompanied or influenced, which can massively determine the limits of a design. These limiting secondary properties are also referred to as "parasitic" side properties. For semiconductors, there are several classes of different components, each of which has specific advantages and disadvantages. Are known semiconductor switches based on silicon, z. B. an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor
    Field effect transistor (MOSFET), and corresponding components with other base material instead of silicon, in particular gallium arsenide (GaAs), gallium nitride (GaN) or silicon carbide (SiC). All of the aforementioned components, despite specific advantages of the mentioned parasitic properties in common. These properties are usually complementary to the respective desired function. For example, results in a desired fast switching of high currents over the known formula
    a fast switching (small dt) of a high current (large dl), even with small inductance L, which is composed of the self-inductance and the line inductances, a high (over) voltage, which can lead to self-destruction of the semiconductor. Accordingly, appropriate design and countermeasures are required if such a requirement is to be managed permanently. To overcome this problem, usually the DC link capacitor is oversized to cut off on the one hand overvoltages and on the other to compensate for the reduced by the parasitic series resistances charging / discharging the gate capacitances of the semiconductor. The environment in the application thus determines the design of the capacitor.
    Another parasitic property are leakage currents, which practically always lead to considerable temperature increases, which are to be limited to a certain permissible level. Although just semiconductors are in this sense very robust and particularly efficient at higher temperatures, but too high temperatures and / or repeated material temperature changes can ultimately lead to material damage of those elements or at least limit their life, which connect to the semiconductor or in the vicinity as the substrate or connecting elements and in particular also capacitors.
    Capacitors have narrow limits in terms of temperature resistance, which are effective especially at high currents and voltages. As all capacitor technologies increase both the leakage currents and the breakdown voltages as the temperature increases, this must also be considered in the design. Because of the heat production of the semiconductors in a circuit and because of their own contribution to the temperature increase, the capacitors must be placed in addition to the already required oversizing already at some distance to the semiconductors to allow effective cooling and thus compliance with a predetermined temperature range. However, the spacing leads to the fact that the required longer electrical connections are always associated with corresponding inductance, which is counterproductive in the sense of the above formula and causes an additional oversizing of the capacitor.
    Various capacitor technologies are known from the prior art, in particular ceramic multilayer capacitors, aluminum electrolytic capacitors and metallized film capacitors. In particular, capacitance, voltage, ripple current, equivalent series resistance, loss factor, frequency response, capacity stability, voltage derating, but also temperature behavior, reliability, energy density and costs are used as evaluation parameters for the respective application. Taking into account these evaluation parameters or criteria, aluminum electrolytic capacitors and metallized film capacitors are used above all in the power range from about 1 kW, but ceramic capacitors in the power range below.
    The general trend towards miniaturization of components also concerns electromobility and thus also components such as the aforementioned AC / DC converters for motor drives. It is demanded that electronic components in the corresponding inverters should be made much smaller and more efficient. Concerning capacitors, it is noted that the properties of ceramic multilayer capacitors would be favorable over aluminum electrolytic capacitors or metallized film capacitors if the required high voltages in inverters would not decrease the capacitance of the X7R capacitors to be used with increasing voltage (M.March, ECPE Automotive Power Electronics Roadmap, ECPE-HOPE Symposium Automotive Power Electronics, Sindelfingen, October 7 to 8, 2008). For example, in conventional voltages of about 400 V, therefore, the capacity drops to z. B. 25% of the nominal value; In addition, energy storage takes place exclusively via the electric field strength and there are hardly any polarization components added. However, materials are known in which the capacity initially increases, reaches a maximum value, and only then decreases again (CK Campeil et al., IEEE Transactions on Component and Packaging Technologies, Vol. 25 (2), 2002, 211). , The energy storage is also at the use voltages with a high proportion of polarization energy. A very large advantage proves to be a high available capacity density under application conditions, which is in contrast to conventional ceramic capacitors. As a major disadvantage, however, the very expensive precious metal palladium or a silver / palladium alloy is used in these materials as the inner electrode, which is acceptable for individual applications such as in medical devices, but precludes a broad economic application.
    Instead of palladium or a silver / palladium alloy, copper for internal electrodes can also be used recently by adapting the composition of a ceramic material in capacitors (WO 2013/152887 A1). Such capacitors have excellent high-frequency characteristics. Copper is also inexpensive. Corresponding multilayer capacitors with copper as the inner electrode and a ceramic base component based on lead zirconate titanate (PZT) are already used in electronics, when high powers are required. The problem of self-heating is still given.
    Starting from the illustrated prior art, it is an object of the invention to provide a ceramic material having a high dielectric constant and is suitable for the production of capacitors with low self-heating, in particular multilayer capacitors, which can thus be arranged in the immediate vicinity of semiconductors.
    Furthermore, it is an object of the invention to represent a use of such a material.
    Finally, it is an object of the invention to provide a capacitor which has a low self-heating during operation with high performance.
    The first object is achieved by a ceramic material of the formula
    wherein X and Y are each a rare earth metal selected from the group consisting of lanthanum (La), neodymium (Nd), yttrium (Y), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium ( Ho), erbium (Er) and / or ytterbium (Yb); A represents a monovalent ion;
    x and / or y and / or z &gt;0;
    solved.
    In the conceptual framework of the invention, the consideration is given that the self-heating in the ceramic material when used in a capacitor can be reduced by the fact that the loading and unloading process is facilitated. The starting point of this consideration is that in an antiferroelectric material the dielectric shift depends on the structural state of the capacitor material and the macroscopic polarization is transferred to the microscopic alignment of ionic units and vice versa. In this picture, a charging or discharging process can be understood as a polarization wave whose carriers are lattice vibrations of the polarized grating. These lattice vibrations are structure-dependent and have certain frequencies and energy densities. The basic structure of antiferroelectric materials according to the prior art is a perovskite structure of the type AB03 with titanate octahedra linked to the corner points, the low-energy lattice vibrations representing, to a first approximation, a coupled torsional rocking vibration of these octahedrons. Depending on the state of the ceramic, the tilt angles of the octahedra determine the respective phase state (antiferro-, ferro- or paraelectric). The size of the dielectric constant and the loss angle correspond to the vibration amplitude or the vibration damping.
    According to the considerations, precisely those collective lattice vibrations should be excitable on a structural level, which is a first aspect of the theoretical considerations.
    A second aspect of the considerations is the desired use of cost-effective copper inner electrodes in multilayer capacitors. These additionally overcome the problem that only a low sintering temperature is permissible. The necessary defect structures for sintering support by sintering aids, however, can only be varied within narrow limits in terms of composition.
    For this purpose, according to the prior art monovalent doping ions are used, which are introduced approximately to the extent in which the relevant for the antiferroelectric phase ions are valence compensated. In the context of the invention, it has now been recognized that targeted control of the lattice dynamics opens up the possibility of reducing self-heating while maintaining conventional sintering aids. The invention is based on the concept that a self-heating will be lowest when the Drehkippschwingungen have an energetically flat course around a rest position. Translated to a perovskite structure, this means that a structural phase transition is approaching. This is inventively achieved by a partial replacement of the lead (Pb) by barium (Ba). By strontium (Sr) and calcium (Ca) lattice spacings can be compensated in a further embodiment. However, since a structural phase transition would prevent the formation of an antiferroelectric phase, which is why the phase transition can only be approximated, the contents of Ba, Sr and Ca should be adjusted so that
    The practical implementation of the above considerations shows that the partial substitution of Pb with Ba, Sr and / or Ca can be used to adjust the structure of the antiferroelectric ceramic material so that, on the one hand, self-heating when used in a capacitor is significantly reduced and, on the other hand, in use in multilayer capacitors, the preferred copper inner electrodes can be used. Tin (Sn), which could also replace Ba, is not provided, since Sn could indeed reduce the self-heating, but the likewise desired sinterability when using copper inner electrodes is then not given.
    Preferably, for a favorable effect on the grating or the formation of the material according to the invention, 0.01 &lt; r &lt; 0.2.
    It is particularly preferred that the ceramic material with values of
    is trained.
    If Ba is mandatory, due to an optimized structure, there is little self-heating of the material when used in a condenser. This is further enhanced by the possible presence of Sr and Ca to optimize lattice spacing.
    If only Ba is provided, then the material is with
    educated.
    If a training with 0 &lt; y &lt; 0.99 is provided, with a Ba content outweighs the Sr content, a loss angle of a multilayer capacitor and thus a self-heating can be kept particularly effective low. For further improvement, the presence of both Ba and Sr and / or Ca may be provided, wherein
    As a result, a loss angle and thus a self-heating when using the material in a multilayer capacitor can be reduced by up to 80%.
    With regard to the proportions of zirconium (Zr) and titanium (Ti), the preferred proviso is that 0.01 &lt; d &lt; 0.70, especially 0.03 &lt; d &lt; 0.52.
    The monovalent ion A is not critical per se, but is preferably selected from the group consisting of sodium (Na), potassium (K), lithium (Li) and / or silver (Ag), where Na is for lowering the sintering temperature and Thus, the sinterability with copper inner electrodes has been found to be particularly useful. The monovalent ion A, especially Na, may be present in low levels of 3% to 7%, or 0.03 &lt; c &lt; 0.07, preferably 0.04 &lt; c &lt; 0.06. Corresponding levels are already sufficient to lower the sintering temperature to at most 1050 ° C, which is the maximum temperature for sintering when using copper inner electrodes.
    Lanthanum (La) together with neodymium (Nd) is preferably used as the rare earth metal. In the perovskite structure, which can be generally indicated as AB03, where A and B stand for A and B sites respectively, the rare earth metals occupy A sites in place of the Pb. Since La and Nd are trivalent, as are the other rare earth metals listed, this is a donor dopant that is compensated by an acceptor doping with the monovalent ion A. This co-doping has a favorable effect on the highest possible dielectric constant.
    In accordance with the above-stated advantages of a ceramic material according to the invention, this is preferably used in a capacitor, in particular a multilayer capacitor.
    The invention is explained in more detail below with reference to exemplary embodiments.
    The ceramic materials described below can be obtained by conventional mixed oxide process by sintering of precursors on, for example, oxide, acetate, nitrate and / or carbonate in the temperature range of 1000 ° C to 1150 ° C. Alternatively, sol-gel methods can be used to first from solutions of acetates and / or alcoholates of the metals to form a sol by
    Drying and subsequent calcination is transferred to the final ceramic materials.
    The examples given below in Table 1 are prepared by the mixed oxide method, the general formula of the antiferroelectric material prepared being as follows:
    Ba, Sr and / or Ca are constituents of the starting materials to be sintered in various proportions and are thus introduced into the final material.
    Table 1: Exemplary embodiments
    As can be seen from Table 1, by adding Ba, Sr and / or Ca, the loss angles can be reduced by 70% to 80%, which results in a corresponding reduction of the self-heating of the material when used in a multilayer capacitor. Similar results can also be obtained if the contents of Zr and Ti are varied and the general formula for the ceramic material with Ba, Sr and / or Ca substitution e.g. B. is as follows:
    Multilayer capacitors with a ceramic material according to the invention and interposed copper inner electrodes are therefore particularly suitable for use in space-saving circuits, since the self-heating is largely suppressed. This makes it possible, for example, to place the multilayer capacitor between a plurality of semiconductor diodes and thus to create a space-optimized structure with the smallest possible losses and minimized electromagnetic radiation.
    权利要求:
    Claims (15)
    [1]
    Claims 1. Ceramic material of the formula

    wherein X and Y are each a rare earth metal selected from the group consisting of La, Nd, Y, Eu, Gd, Tb, Dy, Ho, Er and / or Yb; A represents a monovalent ion;

    x and / or y and / or z &gt;0;


    [2]
    2. Ceramic material according to claim 1, wherein


    [3]
    3. Ceramic material according to claim 1 or 2, wherein


    [4]
    4. Ceramic material according to claim 3, wherein


    [5]
    5. Ceramic material according to claim 3, wherein

    a Ba component outweighs the Sr component.
    [6]
    6. Ceramic material according to claim 3, wherein

    a Ba component outweighs the Sr component and a Sr component outweighs the Ca component.
    [7]
    The ceramic material according to any one of claims 1 to 6, wherein 0.01 &lt; d &lt; 0.70, especially 0.03 &lt; d &lt; 0.52.
    [8]
    8. A ceramic material according to any one of claims 1 to 7, wherein A is selected from the group consisting of Na, K, Li and / or Ag.
    [9]
    A ceramic material according to any one of claims 1 to 8, wherein X is La and Y is Nd.
    [10]
    10. A ceramic material according to any one of claims 1 to 9, wherein the material is antiferroelectric.
    [11]
    11. Use of a ceramic material according to one of claims 1 to 10 for a capacitor, in particular a multilayer capacitor.
    [12]
    12. Capacitor with a ceramic material according to one of claims 1 to 10.
    [13]
    13. Multilayer capacitor with at least one layer of a material according to one of claims 1 to 10.
    [14]
    14. A multilayer capacitor according to claim 11, wherein inner electrodes are formed of copper.
    [15]
    15. An inverter for a motor drive comprising a multilayer capacitor according to claim 13 or 14.
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    同族专利:
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50116/2014A|AT515462B1|2014-02-17|2014-02-17|Ceramic material and capacitor with the same|ATA50116/2014A| AT515462B1|2014-02-17|2014-02-17|Ceramic material and capacitor with the same|
    CN201580009101.8A| CN106029606B|2014-02-17|2015-02-13|Ceramic material and capacitor comprising the ceramic material|
    PCT/AT2015/050044| WO2015120501A1|2014-02-17|2015-02-13|Ceramic material and capacitor comprised thereof|
    EP15711642.7A| EP3107880B1|2014-02-17|2015-02-13|Ceramic material and capacitor comprised thereof|
    US15/112,917| US9878955B2|2014-02-17|2015-02-13|Ceramic material and capacitor comprised thereof|
    EP19209998.4A| EP3650422A1|2014-02-17|2015-02-13|Ceramic material and capacitor using the same|
    JP2016536974A| JP6495913B2|2014-02-17|2015-02-13|Ceramic material and capacitor including the same|
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