JP4376508B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

【００７８】
表１および図３に示すように、実施例１〜８でのコンデンササンプルのように、ＳｉのＣＶ値ｘ１と、前記誘電体粒子の平均粒径と１層あたりの前記誘電体層２の厚みとの比（誘電体粒子の平均粒径／１層あたりの誘電体層の厚み）ｙ１との関係が本発明の範囲内であるときに、高温負荷寿命が１時間以上となることが確認できた。
【００７９】
実施例９〜１４
主成分原料である誘電体酸化物の製造条件（仮焼条件、粉砕条件など）を様々に変えることにより、表２に示すような平均粒径およびＣＶ値を持つコンデンササンプルを得た。原料の製造条件、および一層あたりの誘電体層の厚み（層間厚み）を７μｍとした以外は実施例１と同様にした。なお、誘電体層を構成する誘電体粒子の平均粒径は実施例１と同様に算出した。得られたコンデンササンプルに対し、実施例１と同様にして高温負荷寿命を測定した。結果を表２に示す。
【００８０】
なお、実施例９〜１４における、ＳｉのＣＶ値と、誘電体層の厚みに対する誘電体粒子の平均粒径の比との関係を図４に示した。
【００８１】
【表２】

【００８２】
表２および図４に示すように、層間厚みを変えても、実施例９〜１４でのコンデンササンプルのように、ＳｉのＣＶ値ｘ１と、前記誘電体粒子の平均粒径と１層あたりの前記誘電体層２の厚みとの比（誘電体粒子の平均粒径／１層あたりの誘電体層の厚み）ｙ１との関係が本発明の範囲内であるときに、高温負荷寿命が１時間以上となることが確認できた。
【００８３】
実施例１５〜１６、比較例３
主成分原料である誘電体酸化物の製造条件（仮焼条件、粉砕条件など）を様々に変えることにより、表３に示すような平均粒径およびＣＶ値を持つコンデンササンプルを得た。原料の製造条件、およびｍ＝１．００５とした以外は実施例１と同様にした。なお、誘電体層を構成する誘電体粒子の平均粒径は実施例１と同様に算出した。得られたコンデンササンプルに対し、実施例１と同様にして高温負荷寿命を測定した。結果を表３に示す。
【００８４】
なお、実施例１５〜１６および比較例３における、ＳｉのＣＶ値と、誘電体層の厚みに対する誘電体粒子の平均粒径の比との関係を図５に示した。
【００８５】
【表３】

【００８６】
表３および図５に示すように、組成、即ちｍの値を変えても、実施例１５〜１６でのコンデンササンプルのように、ＳｉのＣＶ値ｘ１と、前記誘電体粒子の平均粒径と１層あたりの前記誘電体層２の厚みとの比（誘電体粒子の平均粒径／１層あたりの誘電体層の厚み）ｙ１との関係が本発明の範囲内であるときに、高温負荷寿命が１時間以上となることが確認できた。
【００８７】
なお、実施例２〜１６および比較例１〜３で得られたコンデンササンプルに対し、実施例１と同様に、比誘電率と比抵抗を算出した結果、いずれのサンプルについても、比誘電率は１８０以上、比抵抗は１×１０^１２Ωｃｍ以上を示した。また、２０〜８５℃の温度範囲内で、温度に対する静電容量変化率（基準温度２０℃）が−２０００〜０ｐｐｍ／℃を満足するかどうかを調べた結果、いずれのサンプルも満足することが確認された。
【図面の簡単な説明】
【図１】 図１は本発明の一実施形態に係る積層セラミックコンデンサの断面図である。
【図２】 図２はＳｉのＣＶ値と、誘電体層の厚みに対する誘電体粒子の平均粒径の比との関係を示すグラフである。
【図３】 図３は実施例１〜８および比較例１〜２における、ＳｉのＣＶ値と、誘電体層の厚みに対する誘電体粒子の平均粒径の比との関係を示すグラフである。
【図４】 図４は実施例９〜１４における、ＳｉのＣＶ値と、誘電体層の厚みに対する誘電体粒子の平均粒径の比との関係を示すグラフである。
【図５】 図５は実施例１５〜１６および比較例３における、ＳｉのＣＶ値と、誘電体層の厚みに対する誘電体粒子の平均粒径の比との関係を示すグラフである。
【符号の説明】
１… 積層セラミックコンデンサ
１０… コンデンサ素子本体
２… 誘電体層
３… 内部電極層
４… 外部電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric ceramic composition used as, for example, a dielectric layer of a multilayer ceramic capacitor, and an electronic component using the dielectric ceramic composition as a dielectric layer.
[0002]
[Prior art]
A multilayer ceramic capacitor which is an example of an electronic component is obtained by printing a conductive paste on a green sheet made of a predetermined dielectric ceramic composition, and laminating a plurality of green sheets on which the conductive paste is printed. And are integrally baked.
[0003]
In recent years, various dielectric ceramic compositions have been proposed in which inexpensive base metals (such as nickel and copper) can be used as internal electrode materials instead of expensive noble metals (such as palladium and platinum) (for example, patents). References 1-4).
[0004]
For example, in Patent Document 1, the composition formula (Sr_1-xCa_x)_m(Ti_1-yZr_y) O₃The main component is a dielectric oxide represented by the formula (where 0.30 ≦ x ≦ 0.50, 0.03 ≦ y ≦ 0.20, 0.95 ≦ m ≦ 1.08), and the weight of the main component is 100%. Mn as a subcomponent for MnO₂0.01 to 2.00 parts by weight in terms of conversion, SiO₂Has been proposed that contains 0.10 to 4.00 parts by weight of a dielectric ceramic composition. In Patent Document 2, the Mn and SiO with respect to the main component.₂In addition to the above, a dielectric ceramic composition further containing 0.01 to 1.00 parts by weight of ZnO has been proposed.
In Patent Document 3, the composition formula (Sr_1-xCa_x)_m(Ti_1-yZr_y) O₃The main component is a dielectric oxide (where 0.30 ≦ x ≦ 0.50, 0.00 ≦ y ≦ 0.20, 0.95 ≦ m ≦ 1.08), and the powder particle size is Dielectric ceramic compositions having a range of 0.1 to 1.0 μm have been proposed.
In Patent Document 4, the composition formula (MeO)_kTiO₂(Wherein Me is a metal selected from Sr, Ca and Sr + Ca, k is 1.00 to 1.04), and the glass component is used with respect to 100 parts by weight of the main component. As Li₂O, M (where M is at least one metal oxide selected from BaO, CaO and SrO) and SiO₂A dielectric porcelain composition containing 0.2 to 10.0 parts by weight of a material using a predetermined molar ratio is proposed.
[0005]
However, all of the dielectric ceramic compositions described in Patent Documents 1 to 4 have a short accelerated lifetime of insulation resistance after firing, and have an internal electrode made of a base metal such as nickel using the dielectric ceramic composition. When the multilayer ceramic capacitor is manufactured, there is a problem that the reliability of the obtained multilayer ceramic capacitor is lowered. In addition, there is no mention of the relationship between the microstructure of the dielectric ceramic composition and the reliability.
[Patent Document 1]
JP 63-224108 A
[Patent Document 2]
JP 63-224109 A
[Patent Document 3]
JP-A-4-206109
[Patent Document 4]
Japanese Patent Publication No.62-24388
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a dielectric ceramic composition that has excellent reduction resistance during firing and has an accelerated accelerated life of insulation resistance. It is another object of the present invention to provide an electronic component such as a multilayer ceramic capacitor manufactured using such a dielectric ceramic composition and having improved reliability.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the dielectric ceramic composition according to the present invention comprises:
A dielectric ceramic composition comprising dielectric particles composed of a dielectric oxide and Si,
The Si CV value x1 in the dielectric ceramic composition is represented on the X axis, and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric ceramic composition (average particle diameter of dielectric particles / dielectric) Thickness of porcelain composition) When y1 is represented on the Y axis,
The relationship between x1 and y1 is that four points A (x1 = 0, y1 = 0.1) and B (x1 = 0.9, y1 = 0.1) in the XY coordinates having the X axis and the Y axis. ), C (x1 = 0.9, y1 = 1.2), and D (x1 = 0, y1 = 1.2) (except on the line where y1 = 0.1) (Refer to the single hatched portion in FIG. 2).
[0008]
The electronic component according to the present invention is
An electronic component having dielectric particles composed of a dielectric oxide and a dielectric layer composed of a dielectric ceramic composition containing Si,
The CV value x1 of the Si in the dielectric layer is represented on the X axis, and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer per layer (average particle diameter of dielectric particles / 1 layer) Per dielectric layer thickness) y1 on the Y axis,
The relationship between x1 and y1 is that four points A (x1 = 0, y1 = 0.1) and B (x1 = 0.9, y1 = 0.1) in the XY coordinates having the X axis and the Y axis. ), C (x1 = 0.9, y1 = 1.2), and D (x1 = 0, y1 = 1.2) (except on the line where y1 = 0.1) (Refer to the single hatched portion in FIG. 2).
[0009]
Preferably, the relationship between x1 and y1 is four points A ′ (x1 = 0, y1 = 0.2), B ′ (x1 = 0.9, y1 = 0.5) in the XY coordinates, It is within a range surrounded by C (x1 = 0.9, y1 = 1.2) and D (x1 = 0, y1 = 1.2) (see the double hatched portion in FIG. 2).
[0010]
Preferably, the relationship between x1 and y1 is three points A ′ (x1 = 0, y1 = 0.2), C (x1 = 0.9, y1 = 1.2) in the XY coordinates, and It is within the range surrounded by D (x1 = 0, y1 = 1.2) (see the triple hatched portion in FIG. 2).
[0011]
Preferably, the dielectric oxide has a composition formula {(Sr_1-xCa_x) O}_m・ (Ti_1-yZr_y) O₂The symbols m, x, and y indicating the composition molar ratio in the formula are in a relationship of 0.94 <m <1.08, 0 ≦ x ≦ 1.00, and 0 ≦ y ≦ 0.20. is there.
[0012]
Operation and effect of the invention
In the conventional dielectric ceramic composition containing dielectric particles composed of dielectric oxide and Si, the accelerated life of insulation resistance is low, and as a result, the dielectric layer composed of this dielectric ceramic composition is In electronic parts such as a multilayer ceramic capacitor, the reliability could not be improved.
[0013]
The present inventor relates to a dielectric particle comprising a dielectric oxide and a dielectric ceramic composition containing Si, and the dielectric particles after firing with respect to the CV value of Si and the thickness of the dielectric ceramic composition Focusing on the relationship with the average particle size, it was found that the accelerated life of the insulation resistance can be increased when these relationships are within a predetermined range. It has also been found that when electronic parts such as multilayer ceramic capacitors are manufactured using such a dielectric ceramic composition having an accelerated accelerated life of insulation resistance, the reliability of the obtained electronic parts can be improved.
[0014]
That is, in the dielectric ceramic composition according to the present invention, the ratio between the CV value x1 of Si and the average particle diameter of the dielectric particles and the thickness of the dielectric ceramic composition (average particle diameter of dielectric particles / dielectric ceramic) The thickness of the composition) y1 is within the range surrounded by the four points A, B, C and D in the XY coordinates, so that the reduction resistance at the time of firing is excellent. The accelerated life of insulation resistance when measured at DC 8 V / μm is enhanced.
[0015]
Since the electronic component according to the present invention has the dielectric layer composed of the dielectric ceramic composition of the present invention, the accelerated life of the insulation resistance is enhanced, and as a result, the reliability is improved.
[0016]
Although it does not specifically limit as an electronic component, A multilayer ceramic capacitor, a piezoelectric element, a chip inductor, a chip varistor, a chip thermistor, a chip resistor, and other surface mount (SMD) chip type electronic components are illustrated.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
FIG. 2 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer;
FIG. 3 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of dielectric particles to the thickness of the dielectric layer in Examples 1 to 8 and Comparative Examples 1 and 2,
FIG. 4 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer in Examples 9 to 14,
FIG. 5 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of dielectric particles to the thickness of the dielectric layer in Examples 15 to 16 and Comparative Example 3.
[0018]
As shown in FIG. 1, a multilayer ceramic capacitor 1 as an electronic component according to an embodiment of the present invention includes a capacitor element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. At both ends of the capacitor element body 10, a pair of external electrodes 4 are formed which are electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Also, there is no particular limitation on the dimensions, and it may be an appropriate dimension according to the application. Usually, (0.6 to 5.6 mm) × (0.3 to 5.0 mm) × (0.3 ˜1.9 mm).
[0019]
The internal electrode layers 3 are laminated so that the end faces are alternately exposed on the surfaces of the two opposite ends of the capacitor element body 10. The pair of external electrodes 4 are formed at both ends of the capacitor element body 10 and are connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.
[0020]
The dielectric layer 2 is composed of a dielectric ceramic composition. The dielectric ceramic composition of the present embodiment has, for example, a composition formula {(Sr_1-xCa_x) O}_m・ (Ti_1-yZr_y) O₂It has the main component containing the dielectric particle comprised with the dielectric material oxide shown by these. At this time, the amount of oxygen (O) may be slightly deviated from the stoichiometric composition of the above formula.
[0021]
The symbol m indicating the composition molar ratio in the above formula is 0.94 <m <1.08, preferably 0.97 ≦ m ≦ 1.03. If m is more than 0.94, the lifetime can be extended if the oxygen partial pressure at the time of firing is lowered, and if m is less than 1.08, the denseness can be achieved without increasing the firing temperature. Can be obtained.
[0022]
The symbol x indicating the composition molar ratio in the above formula is 0 ≦ x ≦ 1.00, preferably 0.30 ≦ x ≦ 0.50. x represents the number of Ca atoms, and the phase transition point of the crystal can be arbitrarily shifted by changing x, that is, the Ca / Sr ratio. Therefore, the capacity temperature coefficient and the relative dielectric constant can be arbitrarily controlled. When x is in the above range, the phase transition point of the crystal exists near room temperature, and the temperature characteristics of the capacitance can be improved. However, in the present invention, the ratio of Sr and Ca is arbitrary, and only one of them may be contained.
[0023]
The symbol y indicating the composition molar ratio in the above formula is 0 ≦ y ≦ 0.20, preferably 0 ≦ y ≦ 0.10. By setting y to 0.20 or less, a decrease in the dielectric constant is prevented. y represents the number of Zr atoms, but TiO₂ZrO is less likely to be reduced than₂There is a tendency that reduction resistance further increases by substituting. However, in the present invention, Zr may not necessarily be included, and only Ti may be included.
[0024]
However, in the present invention, the composition of the dielectric layer 2 is not limited to the above.
[0025]
The dielectric ceramic composition of this embodiment also has a subcomponent containing Si. This Si mainly acts as a sintering aid.
[0026]
In the present invention, the CV value x1 of Si in the dielectric layer 2 and the ratio between the average particle diameter of the dielectric particles and the thickness of the dielectric layer 2 per layer (average particle diameter of dielectric particles / 1 The dielectric layer thickness per layer (y1) has a predetermined relationship.
[0027]
Specifically, when the CV value x1 is represented on the X axis and the ratio y1 is represented on the Y axis, the relationship between the x1 and y1 is four in the XY coordinates having the X axis and the Y axis. Points A (x1 = 0, y1 = 0.1), B (x1 = 0.9, y1 = 0.1), C (x1 = 0.9, y1 = 1.2), and D (x1 = 0) , Y1 = 1.2) (except for the y1 = 0.1 line) (single hatched portion in FIG. 2). Since x1 and y1 have such a relationship, the accelerated life of the insulation resistance is improved, and the multilayer ceramic capacitor 2 with improved reliability is obtained. Such a relationship between x1 and y1 can be obtained, for example, by variously changing the type of raw material powder, the pulverization conditions of the raw material, the firing conditions (such as firing atmosphere and firing temperature), and the like.
[0028]
The CV (coefficient of variation) value here is a coefficient of variation in X-ray intensity when an EPMA surface analysis of the cross section of the dielectric layer is performed. This is a numerical representation of the spread (variation) of the distribution of measurement data, and is a value obtained by CV value (no unit) = (standard deviation / average value).
[0029]
The CV value of Si is the degree of Si or Si oxide at the grain boundary part or triple point (grain boundary phase) existing between the crystal grains of the dielectric particles adjacent to each other inside the dielectric layer 2. It is a standard indicating whether or not segregation, that is, the segregation state of Si in the dielectric layer 2, and the smaller the value, the smaller the segregation of Si at the grain boundary portion. It is considered that as the CV value is smaller, the segregation of Si is suppressed and Si is uniformly distributed in the grain boundary phase and the grains.
[0030]
In the present invention, the relationship between x1 and y1 is that four points A ′ (x1 = 0, y1 = 0.2) and B ′ (x1 = 0.9, y1 = 0.5) in the XY coordinates. , C (x1 = 0.9, y1 = 1.2), and D (x1 = 0, y1 = 1.2) (indicated by the double hatched portion in FIG. 2). Preferably, it is surrounded by three points A ′ (x1 = 0, y1 = 0.2), C (x1 = 0.9, y1 = 1.2), and D (x1 = 0, y1 = 1.2) (The hatched portion in FIG. 2).
[0031]
In addition to Si, the dielectric ceramic composition of the present embodiment includes, for example, at least selected from oxides of Y, Gd, Tb, Dy, V, Mo, Zn, Cd, Sn, W, Mn, Mg, and P One subcomponent may be further added. By adding such a subcomponent, low temperature firing is possible without deteriorating the dielectric characteristics of the main component, and reliability failure when the dielectric layer 2 is thinned can be reduced, resulting in a long life. Can be achieved.
[0032]
The thickness (interlayer thickness) of the dielectric layer 2 per layer is, for example, about 0.5 to 40 μm, preferably about 1 to 10 μm.
[0033]
The dielectric layer 2 is composed of grains (dielectric particles) and a grain boundary phase, and the average particle diameter of the grains of the dielectric layer 2 is preferably about 0.05 to 48 μm, more preferably 0.1 to 12 μm. Degree. The optimum average particle diameter is appropriately changed depending on the thickness of the dielectric layer 2 (interlayer thickness). The grain boundary phase is usually composed of oxides of materials constituting the dielectric material or internal electrode material, oxides of materials added separately, and oxides of materials mixed as impurities during the process. It is composed of glass or glass.
[0034]
The conductive material contained in the internal electrode layer 3 is not particularly limited, but a base metal can be used because the constituent material of the dielectric layer 2 has reduction resistance. As the base metal used as the conductive material, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components, such as P, Fe, and Mg, may be contained by about 0.1 wt% or less. The thickness of the internal electrode layer may be appropriately determined according to the use and the like, but is usually preferably 0.5 to 5 μm, particularly preferably about 1 to 2.5 μm.
[0035]
The conductive material contained in the external electrode 4 is not particularly limited, but usually Cu, Cu alloy, Ni, Ni alloy or the like is used. Of course, Ag, an Ag—Pd alloy, or the like can also be used. In the present embodiment, inexpensive Ni, Cu, and alloys thereof are used. The thickness of the external electrode may be appropriately determined according to the use, etc., but is usually preferably about 10 to 50 μm.
[0036]
In the multilayer ceramic capacitor 1 having the dielectric layer 2 described above, as in the conventional multilayer ceramic capacitor, a green chip is produced by a normal printing method or sheet method using a paste, and this is fired. Manufactured by printing or transferring and firing. Hereinafter, the manufacturing method will be specifically described.
[0037]
First, a dielectric layer paste, an internal electrode paste, and an external electrode paste are manufactured.
[0038]
The dielectric layer paste may be an organic paint obtained by kneading a dielectric material and an organic vehicle, or may be a water-based paint. As the dielectric material, a main component material and a subcomponent material are used according to the composition of the dielectric ceramic composition according to the present embodiment described above.
[0039]
As the main component material, an oxide of Sr, Ca, Ti, Zr and / or a compound that becomes an oxide by firing is used. In the present embodiment, as the main component material, for example, the composition formula {(Sr_1-xCa_x) O}_m・ (Ti_1-yZr_y) O₂The dielectric oxide raw material shown by can be used. The main component material having such a composition may be obtained by a so-called liquid phase method in addition to a so-called solid phase method. The solid phase method is, for example, SrCO.₃, CaCO₃TiO₂, ZrO₂Is used as a starting material, a predetermined amount is weighed, mixed, calcined, and pulverized to obtain a raw material. Examples of the liquid phase synthesis method include an oxalate method, a hydrothermal synthesis method, and a sol-gel method.
[0040]
As the auxiliary component material, at least a Si oxide and / or a compound that becomes a Si oxide after firing is used. The amount of the Si oxide and / or compound added is preferably about 0 to 15 mol, more preferably about 0.2 to 6 mol, per 100 mol of the main component raw material. In addition, Y, Gd, Tb, Dy, V, Mo, Zn, Cd, Sn, W, Mn, Mg and P oxides and / or compounds that become these oxides after firing are selected as subcomponent materials. One or more kinds of single oxides or composite oxides may be used in combination.
[0041]
In addition, as a compound which becomes an oxide by baking, carbonate, nitrate, oxalate, an organometallic compound, etc. are illustrated, for example. Of course, you may use together an oxide and the compound which becomes an oxide by baking. What is necessary is just to determine content of each compound in a dielectric raw material so that it may become a composition of the above-mentioned dielectric ceramic composition after baking. As these raw material powders, those having an average particle diameter of about 0.0005 to 5 μm are usually used.
[0042]
The organic vehicle is obtained by dissolving a binder in an organic solvent, and the binder used in the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral. In addition, the organic solvent used at this time is not particularly limited, and may be appropriately selected from organic solvents such as terpineol, butyl carbitol, acetone, toluene and the like according to a method such as a printing method or a sheet method.
[0043]
The water-based paint is obtained by dissolving a water-soluble binder, a dispersant, etc. in water. The water-based binder is not particularly limited, and is appropriately selected from polyvinyl alcohol, cellulose, water-soluble acrylic resin, emulsion, and the like. do it.
[0044]
The internal electrode paste is prepared by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above or various oxides, organometallic compounds, resinates and the like that become the above-mentioned conductive materials after firing. The The external electrode paste is also prepared in the same manner as this internal electrode paste.
[0045]
The content of the organic vehicle in each paste described above is not particularly limited, and may be a normal content, for example, about 1 to 5% by weight for the binder and about 10 to 50% by weight for the solvent. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary.
[0046]
When using the printing method, the dielectric paste and the internal electrode paste are laminated and printed on a substrate such as polyethylene terephthalate, cut into a predetermined shape, and then peeled off from the substrate to obtain a green chip. On the other hand, when the sheet method is used, a green sheet is formed using a dielectric paste, an internal electrode paste is printed thereon, and these are stacked to form a green chip.
[0047]
Next, the green chip is subjected to binder removal processing and firing.
[0048]
The binder removal treatment may be performed under normal conditions. In particular, when a base metal such as Ni or Ni alloy is used as the conductive material of the internal electrode layer, the heating rate is 5 to 300 ° C./hour in an air atmosphere. More preferably, the holding temperature is 10 to 100 ° C./hour, the holding temperature is 180 to 400 ° C., more preferably 200 to 300 ° C., and the temperature holding time is 0.5 to 24 hours, more preferably 5 to 20 hours.
[0049]
The firing atmosphere of the green chip may be appropriately determined according to the type of the conductive material in the internal electrode layer paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen partial pressure of the firing atmosphere Preferably 10^-10-10^-3Pa, more preferably 10^-10~ 6 × 10^-5Pa, more preferably 10^-6~ 6 × 10^-5Pa. If the oxygen partial pressure during firing is too low, the conductive material of the internal electrode may be abnormally sintered and interrupted, and if the oxygen partial pressure is too high, the internal electrode may be oxidized. Oxygen partial pressure of 10^-10~ 6 × 10^-5By adjusting to Pa, it has excellent capacity-temperature characteristics, and further, the accelerated life of the insulation resistance is improved, and the reliability of the obtained multilayer ceramic capacitor 1 can be enhanced. Especially the oxygen partial pressure is 10^-6~ 6 × 10^-5By adjusting to Pa, the capacitor is obtained even when the dielectric layer 2 is thinned to about 4 μm, for example, while maintaining the reliability required for the multilayer ceramic capacitor 1 with excellent capacitance-temperature characteristics. It is difficult for the insulation resistance of 1 to deteriorate, and the occurrence of a defect rate of the initial insulation resistance can be reduced.
[0050]
The holding temperature of baking is 1000-1400 degreeC, More preferably, it is 1200-1380 degreeC. This is because if the holding temperature is too low, the densification is insufficient, and if the holding temperature is too high, the capacity-temperature characteristics deteriorate due to electrode discontinuity due to abnormal sintering of the internal electrode or diffusion of the internal electrode material.
[0051]
As other firing conditions, the heating rate is 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, the temperature holding time is 0.5 to 8 hours, more preferably 1 to 3 hours, and the cooling rate. Is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the firing atmosphere is desirably a reducing atmosphere. As the atmosphere gas, for example, a mixed gas of nitrogen gas and hydrogen gas is humidified. It is desirable to use it.
[0052]
When firing in a reducing atmosphere, it is desirable to anneal (heat treat) the sintered body of the capacitor chip. Annealing is a process for re-oxidizing the dielectric layer, thereby increasing the insulation resistance. The oxygen partial pressure in the annealing atmosphere is preferably 10^-4Pa or more, more preferably 10^-110 Pa. If the oxygen partial pressure is too low, reoxidation of the dielectric layer 2 becomes difficult, and if the oxygen partial pressure is too high, the internal electrode layer 3 may be oxidized.
[0053]
The holding temperature during annealing is 1100 ° C. or lower, more preferably 500 to 1100 ° C. If the holding temperature is too low, reoxidation of the dielectric layer is insufficient, the insulation resistance is deteriorated, and the accelerated life tends to be shortened. On the other hand, if the holding temperature is too high, the internal electrode is oxidized and the capacity is lowered, and it reacts with the dielectric substrate, so that the capacity-temperature characteristic, the insulation resistance, and its accelerated life tend to deteriorate. Note that the annealing can be composed of only the temperature increasing process and the temperature decreasing process. In this case, the temperature holding time is zero, and the holding temperature is synonymous with the maximum temperature.
[0054]
Other annealing conditions include a temperature holding time of 0 to 20 hours, more preferably 6 to 10 hours, a cooling rate of 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour, and an annealing atmosphere gas. For example, it is desirable to humidify and use nitrogen gas.
[0055]
In addition, in the said binder removal process and annealing process similarly to the baking mentioned above, in order to humidify nitrogen gas and mixed gas, a wetter etc. can be used, for example, The water temperature in this case shall be 5-75 degreeC. It is desirable.
[0056]
Moreover, these binder removal processing, firing and annealing may be performed continuously or independently of each other. When these are performed continuously, the atmosphere is changed without cooling after the binder removal treatment, and then the firing is performed by raising the temperature to the holding temperature at the time of firing, followed by cooling and the annealing holding temperature. It is more preferable to perform the annealing process by changing the atmosphere when the temperature reaches. On the other hand, when these are performed independently, after firing, the temperature can be raised in a nitrogen gas or humidified nitrogen gas atmosphere up to the holding temperature at the time of the binder removal, and then the temperature can be further increased by changing the atmosphere. Preferably, after cooling to the annealing holding temperature, it is preferable to continue cooling by changing to a nitrogen gas or humidified nitrogen gas atmosphere again. As for annealing, the temperature may be changed after raising the temperature to a holding temperature in a nitrogen gas atmosphere, or a humidified nitrogen gas atmosphere may be used for all the annealing steps.
[0057]
The capacitor fired body obtained as described above is subjected to end face polishing by, for example, barrel polishing or sand blasting, and the external electrode paste is printed or transferred and fired to form the external electrode 4. The firing conditions of the external electrode paste are preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a mixed gas of humidified nitrogen gas and hydrogen gas. Then, if necessary, a coating layer (pad layer) is formed on the surface of the external electrode 4 by plating or the like.
[0058]
The multilayer ceramic capacitor 1 of the present embodiment manufactured as described above has excellent capacity-temperature characteristics and has an improved accelerated life of insulation resistance, and as a result, its reliability is improved.
[0059]
Further, the ceramic capacitor 1 of the present embodiment manufactured in this way is mounted on a printed board by soldering or the like and used for various electronic devices.
[0060]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various modes without departing from the gist of the present invention.
[0061]
For example, in the above-described embodiment, the multilayer ceramic capacitor 1 is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to this, and any electronic component having the dielectric layer 2 may be used. .
[0062]
【Example】
Next, the present invention will be described in more detail with reference to examples that further embody the embodiment of the present invention. However, the present invention is not limited to these examples.
[0063]
Example 1
As a main component material, a composition formula {(Sr_1-xCa_x) O}_m・ (Ti_1-yZr_y) O₂A dielectric oxide having a relationship of m = 0.919, x = 0.36, and y = 0 was prepared.
[0064]
V as the first subcomponent raw material with respect to 100 mol of the main component raw material.₂O₅Of 0.2 mol in terms of V, MnCO as the second subcomponent raw material₃0.37 mol in terms of Mn, (SiO2 as the third subcomponent raw material₂+ CaO) is (0.4 + 0.4) mol, Y as the fourth subcomponent raw material₂O₃0.07 mol in terms of Y was weighed, these were wet mixed by a ball mill, and then dried to obtain a dielectric material.
[0065]
100 parts by weight of the obtained dielectric material, 4.8 parts by weight of acrylic resin, 40 parts by weight of methylene chloride, 20 parts by weight of ethyl acetate, 6 parts by weight of mineral spirit, and 4 parts by weight of acetone are mixed by a ball mill. Thus, a dielectric layer paste was obtained.
[0066]
100 parts by weight of Ni particles having an average particle size of 0.2 to 0.8 μm, 40 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose dissolved in 92 parts by weight of butyl carbitol), and 10 parts by weight of butyl carbitol A paste for an internal electrode layer was obtained by kneading with three rolls to obtain a paste.
[0067]
Paste obtained by kneading 100 parts by weight of Cu particles having an average particle diameter of 0.5 μm, 35 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose resin dissolved in 92 parts by weight of butyl carbitol) and 7 parts by weight of butyl carbitol Thus, an external electrode paste was obtained.
[0068]
Using the obtained dielectric layer paste, a green sheet having a thickness of 6 μm was formed on the PET film. After the internal electrode layer paste was printed thereon, the green sheet was peeled off from the PET film. Next, these green sheets and protective green sheets (not printed with internal electrode layer paste) were laminated and pressure-bonded to obtain green chips. The number of laminated sheets having internal electrodes was four.
[0069]
Next, the green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing (heat treatment) to obtain a multilayer ceramic fired body. After polishing the end face of the obtained multilayer ceramic fired body by sand blasting, the external electrode paste was transferred to the end face and baked to form external electrodes, and the multilayer ceramic capacitor sample shown in FIG. 1 was obtained. The size of the obtained capacitor sample is 3.2 mm long × 1.6 mm wide × 0.6 mm thick, and the thickness of the dielectric layer sandwiched between the internal electrode layers (interlayer thickness) is 4 μm. The thickness was 2 μm.
The average particle diameter of the fired dielectric particles constituting the dielectric layer was 1.12 μm. The average particle diameter of the dielectric particles was calculated from the SEM photograph assuming that the shape of the dielectric particles was a sphere by the code method. The field of view of SEM is 23 μm × 30 μm, and each particle size was calculated using 5 to 6 photographs per sample, and the average value thereof was taken as the average particle size.
[0070]
Using the obtained capacitor sample, the CV value of Si in the dielectric layer was calculated. The CV value of Si was EPMA (X-ray microanalyzer, spectroscopic crystal: under conditions of acceleration voltage: 20 kV, irradiation current: 0.1 μA, measurement time: 30 msec / point, electron beam diameter: spot, range: 26 μm × 23 μm: Data was collected using TAP, manufactured by JOEL, JXA-8800RL, and calculated according to the formula: CV value (no unit) = (standard deviation / average value). As a result, the CV value of Si was 0.25.
[0071]
A high temperature load life was measured by maintaining a DC voltage of 8 V / μm at 200 ° C. with respect to such a capacitor sample. This high temperature load life is particularly important when the dielectric layer is thinned. In this embodiment, the time from the start of application until the resistance drops by an order of magnitude is defined as the lifetime, and this is performed for 10 capacitor samples (dielectric layer thickness 4 μm), and the average lifetime is calculated. Over time was considered good. The results are shown in Table 1.
[0072]
In addition to the above high temperature load life, the sample of the obtained capacitor was subjected to a condition of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms with a digital LCR meter (YHP 4274A) at a reference temperature of 25 ° C. Then, the capacitance was measured. Then, the relative dielectric constant (no unit) was calculated from the obtained capacitance, the electrode dimensions of the capacitor sample, and the distance between the electrodes. The relative dielectric constant εr is an important characteristic for producing a small and high dielectric constant capacitor. In this example, the value of the relative dielectric constant εr was an average value of values measured using n = 10 capacitor samples, and 180 or more was good. As a result, the relative dielectric constant was 180 or more.
[0073]
Thereafter, using an insulation resistance meter (R8340A manufactured by Advantest Corp.), the insulation resistance IR after applying DC 50 V to the capacitor sample for 60 seconds at 25 ° C. was measured, and this measured value, the electrode area and thickness of the capacitor sample, From this, the specific resistance ρ (unit: Ωcm) was obtained by calculation. In this embodiment, the specific resistance ρ is an average value of ten specific resistances, and 1 × 10¹²Ωcm or more was considered good. As a result, the specific resistance is 1 × 10¹²It showed Ωcm or more.
[0074]
Moreover, with respect to the obtained capacitor sample, using an LCR meter, the capacitance at a voltage of 1 kHz and 1 V was measured, and when the reference temperature was 20 ° C., within a temperature range of 20 to 85 ° C., It was investigated whether the capacitance change rate with respect to temperature satisfied −2000 to 0 ppm / ° C. As a result, it was confirmed that they were satisfied.
[0075]
Examples 2-8, Comparative Examples 1-2
Capacitor samples having average particle diameters and CV values as shown in Table 1 were obtained by variously changing the production conditions (calcination conditions, pulverization conditions, etc.) of the dielectric oxide as the main component material. The same procedure as in Example 1 was performed except for the manufacturing conditions of the raw materials. The average particle size of the dielectric particles constituting the dielectric layer was calculated in the same manner as in Example 1. For the obtained capacitor sample, the high temperature load life was measured in the same manner as in Example 1. The results are shown in Table 1.
[0076]
The relationship between the CV value of Si and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer in Examples 1 to 8 and Comparative Examples 1 and 2 is shown in FIG.
[0077]
[Table 1]

[0078]
As shown in Table 1 and FIG. 3, like the capacitor samples in Examples 1 to 8, the CV value x1 of Si, the average particle diameter of the dielectric particles, and the thickness of the dielectric layer 2 per layer When the relationship with the ratio y1 (average particle diameter of dielectric particles / dielectric layer thickness per layer) y1 is within the range of the present invention, it can be confirmed that the high temperature load life is 1 hour or more. It was.
[0079]
Examples 9-14
Capacitor samples having average particle diameters and CV values as shown in Table 2 were obtained by variously changing the production conditions (calcination conditions, pulverization conditions, etc.) of the dielectric oxide as the main component raw material. The same procedure as in Example 1 was conducted, except that the raw material production conditions and the thickness of the dielectric layer per layer (interlayer thickness) were set to 7 μm. The average particle size of the dielectric particles constituting the dielectric layer was calculated in the same manner as in Example 1. For the obtained capacitor sample, the high temperature load life was measured in the same manner as in Example 1. The results are shown in Table 2.
[0080]
The relationship between the CV value of Si and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer in Examples 9 to 14 is shown in FIG.
[0081]
[Table 2]

[0082]
As shown in Table 2 and FIG. 4, even if the interlayer thickness is changed, like the capacitor samples in Examples 9 to 14, the CV value x1 of Si, the average particle diameter of the dielectric particles, and the per layer When the relationship with the ratio of the dielectric layer 2 thickness (average particle diameter of dielectric particles / dielectric layer thickness per layer) y1 is within the scope of the present invention, the high temperature load life is 1 hour. It was confirmed that this was the case.
[0083]
Examples 15 to 16, Comparative Example 3
Capacitor samples having average particle diameters and CV values as shown in Table 3 were obtained by variously changing the production conditions (calcination conditions, pulverization conditions, etc.) of the dielectric oxide as the main component material. Example 1 was repeated except that the raw material production conditions and m = 1.005 were set. The average particle size of the dielectric particles constituting the dielectric layer was calculated in the same manner as in Example 1. For the obtained capacitor sample, the high temperature load life was measured in the same manner as in Example 1. The results are shown in Table 3.
[0084]
The relationship between the CV value of Si and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer in Examples 15 to 16 and Comparative Example 3 is shown in FIG.
[0085]
[Table 3]

[0086]
As shown in Table 3 and FIG. 5, even if the composition, that is, the value of m is changed, like the capacitor samples in Examples 15 to 16, the CV value x1 of Si and the average particle diameter of the dielectric particles When the relationship with the ratio of the dielectric layer 2 per layer to the thickness (average particle diameter of dielectric particles / dielectric layer thickness per layer) y1 is within the scope of the present invention, It was confirmed that the lifetime was 1 hour or more.
[0087]
As a result of calculating the relative dielectric constant and specific resistance of the capacitor samples obtained in Examples 2 to 16 and Comparative Examples 1 to 3 in the same manner as in Example 1, the relative dielectric constant of each sample is 180 or more, specific resistance is 1 × 10¹²It showed Ωcm or more. In addition, as a result of investigating whether the rate of change in capacitance with respect to temperature (reference temperature 20 ° C.) satisfies −2000 to 0 ppm / ° C. within a temperature range of 20 to 85 ° C., any sample may be satisfied. confirmed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
FIG. 2 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of dielectric particles to the thickness of the dielectric layer.
FIG. 3 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of dielectric particles to the thickness of the dielectric layer in Examples 1 to 8 and Comparative Examples 1 and 2.
FIG. 4 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of dielectric particles to the thickness of the dielectric layer in Examples 9 to 14;
FIG. 5 is a graph showing the relationship between the CV value of Si and the ratio of the average particle diameter of dielectric particles to the thickness of the dielectric layer in Examples 15 to 16 and Comparative Example 3.
[Explanation of symbols]
1 ... Multilayer ceramic capacitor
10 ... Capacitor element body
2 ... Dielectric layer
3 ... Internal electrode layer
4 ... External electrode

Claims (1)

An electronic component having dielectric particles composed of a dielectric oxide and a dielectric layer composed of a dielectric ceramic composition containing Si,
The dielectric oxide is represented by a compositional formula {(Sr _1-x Ca _x ) O} _m · (Ti _1-y Zr _y ) O ₂ , and symbols m, x, and y is in a relationship of 0.991 ≦ m ≦ 1.005, 0.30 ≦ x ≦ 0.50, and 0 ≦ y ≦ 0.10.
The CV value x1 of the Si in the dielectric layer is represented on the X axis, and the ratio of the average particle diameter of the dielectric particles to the thickness of the dielectric layer per layer (average particle diameter of dielectric particles / 1 layer) Per dielectric layer thickness) y1 on the Y axis,
The relationship between x1 and y1 is that three points A ′ (x1 = 0, y1 = 0.2) and C (x1 = 0.9, y1 = 1.x) in the XY coordinates having the X axis and the Y axis. 2) and D (x1 = 0, y1 = 1.2) .

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