JP5251993B2 - Laminated electronic components - Google Patents

Description

  The present invention relates to a multilayer electronic component such as a multilayer ceramic capacitor in which electrode layers and dielectric layers are alternately stacked.

  Multilayer ceramic capacitors as electronic components are used in various applications as small, large-capacity, and highly reliable electronic components. Therefore, the temperature environment in which the multilayer ceramic capacitor is used also varies widely. For example, the temperature environment where various electronic devices such as an engine electronic control unit (ECU), a crank angle sensor, and an antilock brake system (ABS) mounted in an engine room of an automobile are placed is about -20 ° C to about + 130 ° C. Electronic components installed in various electronic components over a wide range are also exposed to a wide range of temperature environments.

  Electronic parts such as capacitors used in these electronic devices are machines that can withstand repeated thermal shocks from low to high temperatures in addition to electrical characteristics such as the temperature dependence of capacitance being flat over a wide range. Strength is required.

  Examples of conventional techniques for improving the mechanical strength of multilayer electronic components such as ceramic capacitors include those described in Patent Document 1. The conventional technology represented by Patent Document 1 is a method in which a needle-like secondary phase is formed in a dielectric layer of a ceramic capacitor, and contributes to improving the strength of the boundary phase between ceramic grains.

  Further, for example, Patent Document 2 discloses a conventional technique for forming coarse particles of dielectric on the internal electrode layer. In such a prior art, coarse particles improve the peel strength between layers to some extent. However, since the shape of the coarse particles is an isotropic shape close to a sphere or regular polyhedron, the contact area with the dielectric layer is small. Therefore, the connection force between the dielectric layers was weak for the size of the grains, and the peel strength was insufficient.

  Furthermore, in Patent Document 3, the mechanical strength is improved without impairing the capacitance by forming a needle-like segregated material (based on Ba and Ti) that penetrates the discontinuous portion of the internal electrode layer. It has been proposed to let In the electronic component described in Patent Document 3, it has been confirmed that the mechanical strength is improved, but further improvement in capacitance and reliability are desired.

JP-A-8-22929 JP 2003-77761 A JP 2008-258190 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a laminated electronic component capable of improving mechanical strength and improving reliability.

In order to achieve the above object, the multilayer electronic component according to the present invention is
A laminated electronic component having a laminate in which internal electrode layers and dielectric layers are alternately laminated,
The internal electrode layer has a discontinuous portion;
At the interface between the dielectric layer and the internal electrode layer, there is an acicular segregated material containing Mg and Cr as main components,
The acicular segregated material is arranged so as to block the discontinuous portion along the internal electrode layer.

  The multilayer electronic component of the present invention has an internal electrode having a discontinuous portion, and there is a needle-like segregated material arranged along the internal electrode layer so as to close the discontinuous portion. The acicular segregated material contains Mg and Cr as main components and is arranged along the internal electrode layer so as to close the discontinuous portion. For this reason, it is possible to improve mechanical strength and suppress progressive cracks, and to improve capacitance and reliability.

  In the present invention, the reason why it is possible not only to improve the mechanical strength and suppress progressive cracks, but also to improve the capacitance and reliability can be considered as follows. Since Cr has a higher hardness than Si and Mn, it is considered that the effect of suppressing progressive cracking is high. In addition, compared to Si and Mn, Mg and Cr have higher conductivity and a higher effect of increasing the capacity acquisition rate. Therefore, the segregation component is Mg-Cr, which is superior to the segregation of other components. Yes.

Preferably, the dielectric layer is composed of a dielectric ceramic composition represented by the general formula ABO ₃ and having a main component having a perovskite crystal structure and a subcomponent containing at least Mg and Cr. Preferably, Mg is contained in an amount of 0.5 to 4 mol, more preferably 1.0 to 1.9 mol, and Cr is preferably 0.1 to 0 mol in terms of oxide with respect to 100 mol of the main component. 0.5 mol, more preferably 0.1 to 0.3 mol, and the ratio of the number of moles of Mg and Cr (Mg / Cr) is preferably 2.5 to 20, more preferably 5 to 19. By setting the ratio of Mg, Cr and Mg / Cr within such a range, it is possible to more reliably form needle-like segregated materials containing Mg—Cr as a main component.

  Preferably, the total length (Lt) of the discontinuous portions in a cross section having a predetermined area perpendicular to the internal electrode layer is equal to the length of the discontinuous portions blocked by the acicular segregated matter. The ratio (mt / Lt) of the total (mt) is 40% or more. By increasing mt / Lt, the mechanical strength can be improved while improving the capacitance of the multilayer electronic component.

  Preferably, among the acicular segregated matter arranged so as to close the discontinuous portion, the dielectric layer and the internal electrode layer are formed so as to close the discontinuous portion without penetrating the discontinuous portion. The ratio of the needle-like segregated matter arranged along the internal electrode layer at the interface is 30% or more.

  Compared to the case where there are many segregated materials that pass through the discontinuous portions and block the discontinuous portions, the mechanical strength (peeling) It has been confirmed by the present inventors that the strength is equal to or greater than that and is excellent in terms of reliability. The occurrence of an initial failure is considered as one of the causes due to the occurrence of progressive cracks. Since segregation, which is a metal, has a higher conductivity than dielectric, which is an insulator, it bridges more than the form of needle-like segregation, which penetrates the discontinuity and closes the discontinuity to bridge the dielectric layers. It is considered that the acicular segregated material that fills the discontinuous portion in a form that does not pass (closes the discontinuous portion without penetrating the discontinuous portion) can increase the strength while maintaining the distance between the insulating layers.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the dielectric layer shown in FIG. FIG. 3 is a schematic diagram for obtaining a blocking ratio at which the needle-like segregation shown in FIG. FIG. 4 is a schematic diagram of a peel strength test.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

<Multilayer ceramic capacitor 1>
As shown in FIG. 1, a multilayer ceramic capacitor 1 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 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. Although there is no restriction | limiting in particular in the shape of the element main body 10, Usually, it is set as a rectangular parallelepiped shape. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

<Dielectric layer 2>
The dielectric layer 2 is composed of a dielectric ceramic composition. The dielectric ceramic composition has, as a main component, a general formula ABO ₃ (A is at least one selected from the group consisting of Ba, Ca and Sr, and B is selected from the group consisting of Ti, Zr and Hf. And a main component made of a compound having a perovskite crystal structure. Furthermore, Mg oxide, Cr oxide, R element oxide, and Si-containing oxide are contained as subcomponents, if necessary. The amount of oxygen (O) may be slightly deviated from the stoichiometric composition of the above formula.

Compound constituting the main component, in the present embodiment is represented by a composition formula _{(Ba 1-x-y Ca} x Sr y) TiO 3. That is, the B site atom is composed of Ti.

  In this embodiment, the B site atom is only Ti, but an element other than Ti (for example, Zr or Hf) may be contained in the B site atom as long as the amount of impurities is about. In this case, if the content of atoms other than Ti is 0.3 atomic% or less with respect to 100 atomic% of B site atoms, it can be regarded as the amount of impurities.

  In addition, the molar ratio between the A site atoms (Ba, Sr and Ca) and the B site atoms (Ti) is expressed as an A / B ratio. In this embodiment, the A / B ratio is 0.98 to 1.02 is preferred. In addition, although both x and y are arbitrary ranges, it is preferable that it is the following ranges.

  In the present embodiment, x in the above formula is preferably 0 ≦ x ≦ 0.5. x represents the number of Ca atoms, and by setting x to the above range, the capacity temperature coefficient and the relative dielectric constant can be controlled. In the present embodiment, Ca may not necessarily be included.

  In the present embodiment, y in the above formula is preferably 0 ≦ y ≦ 0.5. y represents the number of Sr atoms, and the relative permittivity at room temperature can be improved by setting y within the above range. In the present embodiment, Sr does not necessarily have to be included.

The content of the Mg oxide may be determined according to the desired characteristics, but is preferably 0.5 to 4.0 mol, more preferably 1.0 in terms of MgO with respect to 100 mol of ABO _3. -1.9 mol. By containing the oxide, desired capacitance-temperature characteristics and IR lifetime can be obtained, and needle-like segregated materials mainly composed of Mg and Cr are formed at the interface between the dielectric layer 2 and the internal electrode layer 3. It becomes easy to do.

The content of the Cr oxide may be determined according to desired characteristics, but is preferably 0.1 to 0.5 mol, more preferably in terms of Cr ₂ O _{3 with} respect to 100 mol of ABO _3. 0.1 to 0.3 mol. By containing the oxide, the lifetime is extended, and it becomes easy to form a needle-like segregated material mainly composed of Mg and Cr at the interface between the dielectric layer 2 and the internal electrode layer 3.

  The ratio of the number of moles of Mg and Cr (Mg / Cr) contained in the dielectric ceramic composition is preferably 2.5 to 20, and more preferably 5 to 19. By setting the ratio of Mg, Cr and Mg / Cr within such a range, it is possible to more reliably form needle-like segregated materials containing Mg—Cr as a main component.

The content of the oxide containing Si may be determined according to desired characteristics, but is preferably 0.1 to 4.0 mol in terms of SiO _{2 with} respect to 100 mol of ABO ₃ . Inclusion of the oxide mainly improves the sinterability of the dielectric ceramic composition. The oxide containing Si may be a composite oxide of Si and another metal element (for example, an alkali metal or an alkaline earth metal). In this embodiment, Si, Ba, and Ca are used. (Ba, Ca) SiO ₃ is preferable.

  The mole ratio (Cr / Si) of Cr and Si contained in the dielectric ceramic composition is preferably 0.19 to 0.96. If this ratio is too small, it tends to be difficult to form a needle-like segregated material containing Mg-Cr as a main component, and if it is too large, it tends to be difficult to control the shape and orientation of the segregated material. is there.

The content of the R element oxide may be determined according to desired characteristics, but is preferably 0.2 to 2.5 mol in terms of R ₂ O _{3 with} respect to 100 mol of ABO ₃ . The inclusion of the oxide has the advantage of improving the IR life. The R element is at least one selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; It is preferably at least one selected from the group consisting of Dy, Gd and Ho.

  In the present embodiment, the above dielectric ceramic composition may further contain other subcomponents according to desired characteristics.

For example, the dielectric ceramic composition according to the present embodiment may contain an oxide of Mn. The content of the _oxide, based on ABO 3 100 moles, each in terms of oxide is preferably 0.02 to 0.30 mol.

The dielectric ceramic composition according to the present embodiment may contain an oxide of at least one element selected from V, Ta, Nb, Mo, and W. The content of the _oxide, based on ABO 3 100 moles, each in terms of oxide is preferably 0.02 to 0.30 mol.

  The thickness of the dielectric layer 2 is not particularly limited, and may be determined as appropriate according to desired characteristics and applications. The number of laminated dielectric layers 2 is not particularly limited, but is preferably 20 or more, more preferably 50 or more, and particularly preferably 100 or more.

The dielectric layer 2 includes dielectric particles (not shown), grain boundaries (not shown) formed between a plurality of adjacent dielectric particles, and segregated materials 2, 2a1, 2a2, and 2a3 described later. In the present embodiment, the dielectric particles may be the main component particles (ABO ₃ particles) alone, and the subcomponent elements such as R element, Mg and Si are dissolved in the main component particles (ABO ₃ particles). It may be (diffused) particles.

  The crystal particle diameter of the dielectric particles is not particularly limited, but is preferably 0.1 to 0.5 μm. The crystal particle diameter of the dielectric particles is measured, for example, as follows. That is, the element body 10 is cut in the stacking direction of the dielectric layer 2 and the internal electrode layer 3, the average area of the dielectric particles is measured in the cross section, the diameter is calculated as the equivalent circle diameter, and the value is 1.27 times is there. Then, the crystal particle diameter may be measured for 200 or more dielectric particles, and the value at which the accumulation is 50% from the cumulative frequency distribution of the obtained crystal particle diameter may be the average crystal particle diameter (unit: μm). The crystal particle diameter may be determined according to the thickness of the dielectric layer 2 and the like.

<Internal electrode layer 3 and needle-like segregation>
The conductive material contained in the internal electrode layer 3 is not particularly limited, but Ni or Ni alloy is preferable in the present embodiment. 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, may be contained about 0.1 wt% or less. What is necessary is just to determine the thickness of the internal electrode layer 3 suitably according to a use etc.

  FIG. 2 is an enlarged view of the cross section of the central portion S1, the first overlapping portion S2 of the internal electrode layer 3, or the lead portion S3 of the internal electrode layer 3 in the cross section of the multilayer ceramic capacitor 1 shown in FIG. As shown in FIG. 2, when the internal electrode layer 3 is enlarged, a portion where the internal electrode is not actually formed (discontinuous portion 3a) exists in the portion where the internal electrode is to be formed. This discontinuous portion 3a is a region where conductive material particles (mainly Ni particles) are spheroidized by grain growth during firing, resulting in a gap between adjacent conductive material particles and no conductive material. It is.

  In the cross section shown in FIG. 2, the discontinuous portions 3 a make the internal electrode layer 3 appear discontinuous, but the discontinuous portions 3 a are scattered on the main surface of the internal electrode layer 3. Therefore, even if the internal electrode layer 3 is discontinuous in the cross section shown in FIG. 2, it is continuous in the other cross sections, and conduction of the internal electrode layer 3 is ensured. The discontinuous portion 3a is usually formed in the internal electrode layer 3 at a ratio of 3 to 35% with respect to the ideal length (for example, the length of the internal electrode layer 3 before firing).

  In the present embodiment, needle-like segregated substances 2a, 2a1, and 2a2 containing Mg and Cr as main components exist at the interface between the dielectric layer 2 and the internal electrode layer 3. The needle-like segregated materials 2 a, 2 a 1 and 2 a 2 are arranged at the interface between the dielectric layer 2 and the internal electrode layer 3 so as to block the discontinuous portion 3 a along the internal electrode layer 3. In the present embodiment, there may be acicular segregated materials 2a3 arranged so as not to contact the internal electrode layer 3 except at the interface between the dielectric layer 2 and the internal electrode layer 3, but the number (n3) ) Is preferably smaller than the number (n1) of acicular segregated materials 2a, 2a1, 2a2 present at positions so as to block the discontinuous portion 3a at the interface between the dielectric layer 2 and the internal electrode layer 3. . The ratio (n1 / n0) of the number (n1) of needle-like segregated materials 2a, 2a1, 2a2 present at the interface so as to block the discontinuous portion 3a with respect to the number (n0) of all needle-like segregated materials in a predetermined visual field area. ) Is preferably 0.3 or more, more preferably 0.5 or more.

  In the present embodiment, the acicular segregated material 2a existing at the interface between the dielectric layer 2 and the internal electrode layer 3 is removed except for the acicular segregated material 2a3 that exists at a location other than the interface between the dielectric layer 2 and the internal electrode layer 3. The blockage ratio at which 2a1 and 2a2 block the discontinuous portion 3a of the internal electrode layer 3 is defined as follows.

  For example, as shown in FIG. 3, in a cross-sectional photograph of a predetermined field area perpendicular to the internal electrode layer 3, first, the lengths L1, L2, L3, L4, L5, L6,. Is obtained (Lt). Next, the sum (mt) of the lengths m1, m2, m3, m4... Of the discontinuous portions 3a closed by the needle-like segregated materials 2a, 2a1, 2a2 in the cross-sectional photographs having the same visual field area is obtained. At that time, not only the needle-like segregated material 2a that completely blocks the discontinuous portion 3a, but also the needle-like segregated material 2a1 that blocks only a part of the discontinuous portion 3a and the discontinuous portion 3a. The lengths m3 and m4 of the discontinuous portions 3a that are closed are counted for the needle-like segregated material 2a2 that straddles the adjacent dielectric layer 2.

  Then, the ratio (mt / Lt) of the total length (mt) of the discontinuous portions 3a that are blocked with respect to the total length (Lt) of these discontinuous portions 3a is obtained, and is calculated as the blocking ratio. Define as In this embodiment, the occlusion ratio (mt / Lt) is 40% or more, more preferably 47% or more, and particularly preferably 67% or more. The upper limit of the blocking rate is 100%. By increasing mt / Lt, it is possible to improve the mechanical strength while improving the capacitance of the multilayer ceramic capacitor 1. The mt / Lt can be controlled, for example, by changing the firing conditions when firing the element body 10, the annealing temperature after firing, the added amounts of Mg, Cr, Si as subcomponents, and the like.

  The predetermined visual field area is preferably, for example, an average value when a plurality of visual fields are measured at a magnification of 7000 times. Further, the magnification is not particularly limited and may be set as appropriate. However, a magnification in which at least a pair of internal electrode layers 3 is included in one field of view is preferable. This is because, by setting such a magnification, it is possible to observe including the ratio of the segregated material 2 a existing in a form in contact with the internal electrode layer 3.

  In the present embodiment, the total area ratio of the acicular segregated materials 2a and 2a1 to 2a3 observed in a specific visual field area is preferably 0.05 to 3.0 with respect to the area 100% of the dielectric layer 2. %, More preferably 0.5 to 3.0%. The method for calculating the area ratio of the segregated material is not particularly limited, but in the above field of view, a region having a contrast different from that of the dielectric layer 2 and the internal electrode layer 3 is set as the segregated material 2a, and visual or image processing is performed. The area ratio may be calculated by software or the like.

  In the present embodiment, the discontinuous portion 3a without penetrating the discontinuous portion 3a among the needle-like segregated materials 2, 2a, 2a1 and 2a2 arranged so as to close the discontinuous portion 3a in a specific visual field area. The ratio of the acicular segregated materials 2, 2a, 2a1 arranged along the internal electrode layer 3 at the interface between the dielectric layer 2 and the internal electrode layer 3 is preferably 30% or more, Preferably it is 50% or more, particularly preferably 70% or more.

  Compared with the case where there are many segregated substances 2a2 penetrating the discontinuous part 3a and blocking the discontinuous part 3a, there are many segregated substances 2a and 2a1 blocking the discontinuous part 3a without penetrating the discontinuous part 3a. It was confirmed by the present inventors that the mechanical strength (peel strength) is equal to or higher than that and excellent in terms of reliability. The occurrence of an initial failure is considered as one of the causes due to the occurrence of progressive cracks. Since the segregation that is a metal has a higher conductivity than the dielectric that is an insulator, the needle-like segregation 2a2 that penetrates the discontinuous portion 3a and blocks the discontinuous portion 3a and bridges between the dielectric layers 2 is used. The needle-like segregated materials 2a and 2a1 that fill the discontinuous part 3a in a form that does not bridge (close the discontinuous part without penetrating the discontinuous part) are stronger than the form, while maintaining the thickness of the dielectric layer 2. This is considered to be possible to increase

  The presence or absence of the needle-like segregated materials 2a, 2a1-2a3 can be confirmed from the difference in contrast as compared with an electrode or a dielectric, for example, in a secondary electron image or reflected electron image of an electron microscope (SEM). The determination of whether or not the contrast is different may be made by visual observation, or may be made by software or the like that performs image processing. Moreover, it can be confirmed using, for example, an electron beam microanalyzer (EPMA) that the main components of the needle-like segregated materials 2a, 2a1-2a3 are Mg and Cr. Moreover, it can also confirm simply using an energy dispersive detector (EDS). The needle-like segregated materials 2a, 2a1-2a3 of the present embodiment are mainly composed of Mg and Cr and may contain other trace components, but the trace components are the entire needle-like segregated materials 2a, 2a1-2a3. Is 15 mol% or less.

  In the present embodiment, the needle-like segregated matter 2a, 2a1-2a3 is the length of the longest segment of the segregated matter when the cross section of the segregated matter sample is confirmed with an electron microscope or the like. When the distance perpendicular to the thickness and the line segment at the intersection of the sample is the longest is the thickness, the sample whose length is 1.8 times or more of the thickness is regarded as a needle-like segregated material. In the present embodiment, the thicknesses of the needle-like segregated materials 2a and 2a1 to 2a3 are preferably 0.1 to 0.5 times the thickness of the internal electrode layer 3.

<External electrode 4>
The conductive material contained in the external electrode 4 is not particularly limited, but in the present invention, inexpensive Ni, Cu, and alloys thereof can be used. What is necessary is just to determine the thickness of the external electrode 4 suitably according to a use etc.

<Method for Manufacturing Multilayer Ceramic Capacitor 1>
In the multilayer ceramic capacitor 1 of this embodiment, a green chip is produced by a normal printing method or a sheet method using a paste, and fired, and then printed or transferred an external electrode, similarly to a conventional multilayer ceramic capacitor. It is manufactured by baking. Hereinafter, the manufacturing method will be specifically described.

  First, a dielectric material for forming a dielectric layer is prepared, and this is made into a paint to prepare a dielectric layer paste.

As dielectric materials, first, an ABO ₃ material, an Mg oxide material, an R oxide material, and an Si-containing oxide material are prepared. As these raw materials, oxides of the above-described components, mixtures thereof, and composite oxides can be used. In addition, various compounds that become the above-described oxides or composite oxides by firing, such as carbonates and oxalic acid. They can be appropriately selected from salts, nitrates, hydroxides, organometallic compounds, and the like, and can be used as a mixture.

In addition to the so-called solid phase method, the raw material of ABO ₃ can be produced by various methods such as those produced by various liquid phase methods (for example, oxalate method, hydrothermal synthesis method, alkoxide method, sol-gel method, etc.). What was manufactured can be used.

  Further, when the dielectric layer contains components other than the main component and subcomponents, as described above, oxides of these components, mixtures thereof, and composite oxides are used as the raw materials of the components. Can be used. In addition, various compounds that become oxides or composite oxides by firing can be used.

  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 dielectric ceramic composition mentioned above after baking. In the state before forming a paint, the particle size of the dielectric material is usually about 0.1 to 1 μm in average particle size.

  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.

  An organic vehicle is obtained by dissolving a binder in an organic solvent. A binder is not specifically limited, What is necessary is just to select suitably from normal various binders, such as an ethyl cellulose and polyvinyl butyral. The organic solvent is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, and toluene depending on the printing method, the sheet method, and the like.

  Further, when the dielectric layer paste is used as a water-based paint, a water-based vehicle in which a water-soluble binder or a dispersant is dissolved in water and a dielectric material may be kneaded. The water-soluble binder is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, etc. may be used.

  The internal electrode layer paste is obtained by kneading the above-described organic vehicle with the above-described conductive material made of Ni or Ni alloy, or various oxides, organometallic compounds, resinates, etc. that become Ni or Ni alloy after firing. What is necessary is just to prepare. The internal electrode layer paste may contain a common material. The common material is not particularly limited, but preferably has the same composition as the main component.

  The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

  There is no restriction | limiting in particular in content of the organic vehicle in each above-mentioned paste, For example, what is necessary is just about 1-5 weight% of binders, for example, about 10-50 weight% of binders. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary. The total content of these is preferably 10% by weight or less.

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste are printed and laminated on a substrate such as PET, cut into a predetermined shape, and then peeled from the substrate to obtain a green chip.

  In the case of using the sheet method, a green sheet is formed using a dielectric layer paste, and after printing the internal electrode layer paste thereon, these are stacked, cut into a predetermined shape, and formed into a green chip. .

  Before firing, the green chip is subjected to binder removal processing. As binder removal conditions, the temperature rising rate is preferably 5 to 300 ° C./hour, the holding temperature is preferably 180 to 400 ° C., and the temperature holding time is preferably 0.5 to 24 hours. The atmosphere in the binder removal process is air or a reducing atmosphere.

  After removing the binder, the green chip is fired. In the firing step of the present embodiment, the rate of temperature rise is preferably 200 ° C./hour or more. The holding temperature during firing is preferably 1000 to 1300 ° C., and the holding time is preferably 0.1 to 4 hours.

The atmosphere during firing is preferably a reducing atmosphere, and as the atmosphere gas, for example, a mixed gas of N ₂ and H ₂ can be used by humidification.

In addition, the oxygen partial pressure during firing 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, oxygen in the atmosphere The partial pressure is preferably 1.0 × 10 ^{−8 to} 1.0 × 10 ⁻² Pa. The temperature lowering rate is preferably 50 ° C./hour or more.

In this embodiment, it is preferable to perform an annealing process (dielectric layer oxidation process) on the element body after firing. Specifically, the holding temperature in the annealing treatment is preferably 950 to 1250 ° C, more preferably 1060 to 1250 ° C, and the holding time is preferably 0.1 to 4 hours. Further, the atmosphere during the oxidation treatment is preferably humidified N ₂ gas (oxygen partial pressure: 1.0 × 10 ^{−3 to} 1.0 Pa).

In the above-described binder removal treatment, firing and oxidation treatment, for example, a wetter or the like may be used when humidifying N ₂ gas, mixed gas, or the like. In this case, the water temperature is preferably about 5 to 75 ° C.

  The binder removal treatment, firing and oxidation treatment may be performed continuously or independently.

  By controlling the firing conditions and the oxidation treatment conditions as described above, it becomes easy to dispose the needle-like segregated materials containing Mg and Cr as main components so as to block the discontinuous portions along the internal electrode layers. . In addition, the ratio (mt / Lt) of the total length (mt) of the discontinuous portions blocked by the acicular segregated matter to the total length (Lt) of the discontinuous portions is 40 It becomes easy to control to more than%. Furthermore, among the needle-like segregated matter arranged so as to close the discontinuous portion, the ratio of the needle-like segregated matter arranged so as to close the discontinuous portion without penetrating the discontinuous portion can be controlled. It becomes easy.

  The capacitor element main body obtained as described above is subjected to end face polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is applied and fired to form the external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

  The multilayer ceramic capacitor of this embodiment manufactured in this way is mounted on a printed circuit board or the like by soldering or the like and used for various electronic devices.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  In the above-described embodiment, the multilayer ceramic capacitor is exemplified as the multilayer ceramic electronic component according to the present invention. However, the multilayer ceramic electronic component according to the present invention is not limited to the multilayer ceramic capacitor, and the electronic component having the above configuration. Anything is fine.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

<Experimental example 1>
First, BaTiO ₃ powder was prepared as a raw material for ABO _{3 as} a main component. In addition, the secondary component materials include MgCO ₃ powder as the Mg oxide material, Cr ₂ O ₃ powder as the Cr oxide material, R ₂ O ₃ powder and Si as the R element oxide material. (Ba _0.6 Ca _0.4 ) SiO ₃ (hereinafter also referred to as BCG) powder as an oxide raw material, MnO powder as an Mn oxide raw material, V ₂ O ₅ powder as a V oxide raw material, Prepared each. Incidentally, MgCO _3, after firing, and thus included in the dielectric ceramic composition as MgO.

Next, the BaTiO ₃ powder prepared above (average particle size: 0.3 μm) and the raw material of the accessory component were wet pulverized with a ball mill for 15 hours and dried to obtain a dielectric raw material. In addition, the addition amount of each subcomponent is the mol shown in Table 1 for MgO, Cr ₂ O ₃ and BCG in terms of each element with respect to 100 mol of BaTiO ₃ which is the main component in the fired dielectric ceramic composition. In terms of the number and each oxide, Y ₂ O ₃ was 1.0 mol, MnO was 0.1 mol, and V ₂ O ₅ was 0.1 mol.

  Next, the obtained dielectric material: 100 parts by weight, polyvinyl butyral resin: 10 parts by weight, dioctyl phthalate (DOP) as a plasticizer: 5 parts by weight, and alcohol as a solvent: 100 parts by weight with a ball mill The mixture was made into a paste to obtain a dielectric layer paste.

  In addition to the above, Ni powder: 44.6 parts by weight, terpineol: 52 parts by weight, ethyl cellulose: 3 parts by weight, and benzotriazole: 0.4 parts by weight are kneaded by three rolls to form a slurry. To prepare an internal electrode layer paste.

  And the green sheet was formed on PET film using the dielectric layer paste produced above. Next, the electrode layer was printed in a predetermined pattern using the internal electrode layer paste thereon, and then the sheet was peeled off from the PET film to produce a green sheet having the electrode layer. Next, a plurality of green sheets having electrode layers were laminated and pressure-bonded to obtain a green laminated body, and the green laminated body was cut into a predetermined size to obtain a green chip.

  Next, the obtained green chip was subjected to binder removal treatment, firing and oxidation treatment under the following conditions to obtain an element body as a sintered body.

  The binder removal treatment conditions were temperature rising rate: 15 ° C./hour, holding temperature: 280 ° C., temperature holding time: 8 hours, and atmosphere: air.

The firing conditions were temperature rising rate: 200 to 2000 ° C./hour, holding temperature: 1000 to 1300 ° C., holding time was 0.5 to 2 hours, cooling rate: 200 to 2000 ° C./hour, and atmospheric gas: humidified. N ₂ + H ₂ mixed gas (oxygen partial pressure of 1.0 × 10 ^{−10 to} 1.0 × 10 ⁻⁷ Pa) was used.

The annealing treatment conditions were as follows: heating rate: 250 ° C./hour, holding temperature: 950 to 1250 ° C., preferably 1060 to 1250 ° C., holding time: 2 hours, cooling rate: 150 ° C./hour, atmospheric gas: humidified N 2 gas (oxygen partial pressure: 1.0 × 10 ⁻³ Pa) was used.

  A wetter was used for humidifying the atmospheric gas during firing and oxidation treatment.

  Next, after polishing the end face of the obtained element body by sandblasting, Cu was applied as an external electrode to obtain a sample of the multilayer ceramic capacitor shown in FIG. The size of the obtained capacitor sample was 1.6 mm × 0.8 mm × 0.8 mm, the thickness of the dielectric layer was 1.0 μm, and the thickness of the internal electrode layer was 1.0 μm. The number of dielectric layers sandwiched between internal electrode layers was 350.

  As shown in Table 1, the obtained capacitor samples 1 to 14 were tested for the presence or absence of Mg—Cr segregation, mechanical strength, capacity increase rate, and reliability by the methods shown below.

<Presence / absence of Mg-Cr acicular segregates>
First, as shown in FIG. 1, the capacitor sample was cut along a plane perpendicular to the dielectric layer 2 and the internal electrode layer 3. A secondary electron image or reflected electron image of an electron microscope (SEM) is taken for the central portion S1 of the cut surface, the overlapping portion S2 of the internal electrode layer 3, or the extraction portion S3 of the internal electrode layer 3, and acicular segregation is performed. The presence or absence of the objects 2a, 2a1-2a3 was judged. The presence or absence of needle-like segregated materials 2a, 2a1-2a3 could be confirmed from the difference in contrast as compared with the electrodes and dielectric.

  When the cross section of the segregated material sample is confirmed with an electron microscope or the like, the distance of the longest segment of the segregated material is taken as the length, and the line segment at the intersection of the sample is the most perpendicular to the length. When the longer distance was defined as the thickness, a sample having a length of 1.8 times or more of the thickness was regarded as a needle-like segregated material. Further, whether or not the segregated material is a needle-like segregated material containing Mg and Cr as main components was confirmed using an electron beam microanalyzer (EPMA).

  As shown in FIG. 2, at the interface between the dielectric layer 2 and the internal electrode layer 3, a needle-like structure containing Mg and Cr as main components arranged so as to block the discontinuous portion 3a along the internal electrode layer 3 Whether or not the segregated materials 2a, 2a1, and 2a2 are present was determined as follows. First, in the specific visual field area of the electron micrograph, as shown in FIG. 2, the number (n0) of all the needle-like segregated materials 2a, 2a1, 2a2, and 2a3 and the interface between the dielectric layer 2 and the internal electrode layer 3 Thus, the number (n1) of needle-like segregated materials 2a, 2a1, 2a2 arranged so as to block the discontinuous portion 3a of the internal electrode layer 3 was measured. When the ratio (n1 / n0) is 0.05 or more, it is arranged so as to block the discontinuous portion 3a along the internal electrode layer 3 at the interface between the dielectric layer 2 and the internal electrode layer 3. It was judged that there existed acicular segregated materials 2a, 2a1, 2a2 containing certain Mg and Cr as main components. In Table 1, when the needle-like segregated materials 2a, 2a1, and 2a2 exist, the presence or absence of Mg—Cr segregation is indicated as “◯”, and when the above conditions are not satisfied, “x” is indicated.

<Mechanical strength>
The mechanical strength (peel strength) of each capacitor sample was measured using a load measuring instrument (INSTORN 5864). As shown in FIG. 4, first, the chip sample 10a after the annealing treatment is placed on a mount-only table 20 that is convex with half the short side of the chip sample 10a, and the stacking direction is the ground. The sample was placed vertically, and the vicinity of the center of the flat surface (lid surface) of the chip sample 10a was sucked and fixed by the suction device 22. And the internal electrode of the chip sample 10a is used by using the blade 24 that can push the surface where the convex part of the table 20 and the chip sample 10a do not overlap from the opposite (upper) direction of the chip sample 10a on the table 20. It pushes so that the laminated structure of a layer and a dielectric material layer may be peeled off. At that time, the maximum load value (peeling strength) received by the blade 24 was measured for 100 samples using a 5864 tester manufactured by INSTORN, and an average value of 50 samples having low strength was obtained. The results are shown in Table 1. The peel strength is preferably 90N or more, and more preferably 105N or more.

<Reliability>
Each capacitor sample was subjected to a high temperature load reliability test to measure the reliability. Specifically, for each capacitor sample, 2000 non-defective chips were prepared, 10 in parallel, 200 ch (2,000 in total) were mounted on the substrate, and a voltage of 6.3 V (rated) was applied at 160 ° C. A failure was determined when the leakage current in the state became two orders of magnitude lower than the value one minute after applying the voltage. The time until failure (hr) was measured. Among 200 samples, an average value was obtained for 10 ch samples having a short time to failure (hr). The results are shown in Table 1. The reliability is preferably 2 hours (hr) or longer, and more preferably 3 hours or longer.

<Capacitance increase rate>
For each capacitor sample, the rate of increase in capacitance was determined as follows. First, for each capacitor sample, the capacitance was measured 10 hours after the heat treatment using an LCR meter 4980A (Agilent Technology), and the measured capacitance CR after 1000 hours was obtained from a known aging coefficient. .

  Each capacitor sample was polished from the side surface so that the laminated state could be seen, photographed with a lens of × 100 using a laser microscope (Keyence VK-8710), and the coverage was determined by image processing. Here, the coverage is the ratio that actually exists on the line where the internal Ni electrode should be. Since the capacitance of the capacitor is proportional to the area of the internal electrode, the capacitance of the capacitor is lost when the internal electrode layer is interrupted. Therefore, in order to ignore the discontinuity of the internal electrode layer (discontinuous portion 3a), it is possible to compare the capacitance lost by the electrode discontinuity by dividing the actual capacitance by the coverage value. it can.

  In the embodiment, the above-described actually measured capacitance CR is related to the blockage rate mt / Lt in which the segregation of Mg—Cr fills the discontinuous portion and the discontinuous portion ratio U. That is, CR is a function of the blockage ratio mt / Lt and U, and is represented by CR (mt / Lt, U). In order to obtain a capacitance value (capacity increase rate%) that has been changed by being buried by Mg-Cr segregation, the capacity when not filled by Mg-Cr segregation is assumed to be CI. Since the capacity increase rate is substantially proportional to the blockage rate mt / Lt due to segregation, CI is an approximate predicted value obtained by extrapolating from a plurality of blockage rates mt / Lt. The capacitance CI is a function of U and is represented by CI (U).

  Next, in order to consider the capacity change due to the ratio of the discontinuous portions, CR and CI are divided by the coverage ratio (1-U) to obtain CRU and CIU. That is, CRU and CIU are represented by CRU = CR / (1-U) and CIU = CI / (1-U), respectively. Here, it is assumed that the ratio U of the discontinuous portions of CRU and CIU to be compared in the next evaluation of the capacity change rate is the same. The discontinuous portion ratio U can be appropriately adjusted depending on the annealing temperature, firing conditions, paste thickness at the time of printing the internal electrode layer paste, and the like.

  From the above, the capacity changed by filling the discontinuous portion due to the segregation of Mg—Cr is represented by CRU-CIU. In order to obtain the change rate of the capacity, a value x obtained by dividing the changed capacity by the CRU is defined as a capacity change rate (capacity increase rate). That is, x = (CRU−CIU) × 100 / CRU. The results are shown in Table 1. The capacity increase rate (%) is preferably 1% or more, more preferably 2% or more, and particularly preferably 3% or more.

  From Table 1, Mg—Cr segregation is deposited to cover the discontinuity of the internal electrode layer at the interface between the internal electrode layer and the dielectric layer, and sufficient mechanical strength, capacity increase rate and reliability are obtained. It was confirmed that it is preferable to satisfy the following conditions. That is, with respect to 100 mol of the main component, Mg is preferably 0.5 to 4 mol, more preferably 1 to 1.9 mol, and Cr is preferably 0.1 to 0.5 mol, more preferably Is 0.1 to 0.3 mol, Mg / Cr is preferably 2.5 to 20, more preferably 5 to 19, and Cr / Si is preferably 0.19 to 0.96.

<Experimental example 2>
A capacitor sample 20 was prepared in the same manner as the sample 6 of Experimental Example 1 except that the cooling rate during firing was 20 ° C./hour, and a similar experiment was performed. Further, a capacitor sample 21 was prepared and a similar experiment was performed in the same manner as the sample 6 of Experimental Example 1 except that annealing was performed at 700 to 900 ° C. and Cr / Si = 0.2. . Further, a capacitor sample 22 was prepared in the same manner as the sample 6 of Experimental Example 1 except that the firing holding temperature was 1150 ° C. and the holding time was 0.4 hour, and a similar experiment was performed. Further, a capacitor sample 23 was prepared in the same manner as the sample 6 of Experimental Example 1 except that the firing temperature was 1350 ° C., and a similar experiment was performed. The results are shown in Table 2.

  As shown in Table 2, by depositing Mg-Cr segregation so as to cover the discontinuity of the internal electrode layer at the interface between the internal electrode layer and the dielectric layer, sufficient mechanical strength, capacity increase rate and It was confirmed that reliability could be obtained.

<Experimental example 3>
Except for changing the annealing temperature in the range of 700 ° C. to 1250 ° C., capacitor samples 30 to 36 were prepared in the same manner as the sample 6 of Experimental Example 1, and the same experiment was performed. However, in Experimental Example 3, the total length (mt) of the discontinuous portions 3a that are closed is compared to the total length (Lt) of the discontinuous portions 3a of the internal electrode layer 3 by the method described above. The ratio (mt / Lt) was determined and defined as the blocking ratio, and the blocking ratio (mt / Lt) was determined for each sample 30-36. The results are shown in Table 3.

  From Table 3, it was confirmed that the occlusion ratio (mt / Lt) was 40% or more, more preferably 47% or more, and particularly preferably 67% or more.

<Experimental example 4>
Capacitor samples 41 to 49 were prepared in the same manner as Sample 6 of Experimental Example 1, except that the cooling rate during firing was changed between 200 ° C./hour and 2000 ° C./hour, and similar experiments were performed. . However, in Experimental Example 4, among the needle-like segregated materials 2, 2a, 2a1, and 2a2 arranged so as to close the discontinuous portion 3a, the discontinuous portion 3a passes between the adjacent dielectric layers 2. The ratio of the needle-like segregated material 2a2 arranged so as to straddle (A particle ratio) was determined. Furthermore, among the needle-like segregated matter 2, 2a, 2a1, 2a2 arranged so as to close the discontinuous portion 3a, the dielectric layer 2 is formed so as to close the discontinuous portion 3a without penetrating the discontinuous portion 3a. The ratio of needle segregated materials 2, 2a, 2a1 arranged along the internal electrode layer 3 at the interface between the internal electrode layer 3 and the internal electrode layer 3 was also determined. The results are shown in Table 4.

  From Table 4, it was confirmed that the proportion of B particles was preferably 30% or more, more preferably 50% or more, and particularly preferably 70% or more.

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Element main body 2 ... Dielectric layer 2a, 2a1, 2a2, 2a3 ... Needle segregation 3 ... Internal electrode layer 3a ... Discontinuous part 4 ... External electrode

Claims (3)

A laminated electronic component having a laminate in which internal electrode layers and dielectric layers are alternately laminated,
The internal electrode layer has a discontinuous portion;
At the interface between the dielectric layer and the internal electrode layer, there is an acicular segregated material containing Mg and Cr as main components,
The acicular segregated material is disposed so as to block the discontinuous portion along the internal electrode layer ,
The total length (mt) of the discontinuous portions blocked by the needle-like segregated material with respect to the total length (Lt) of the discontinuous portions in a cross section having a predetermined area perpendicular to the internal electrode layer. ) Ratio (mt / Lt) is 40% or more . Of the acicular segregated matter arranged so as to close the discontinuous portion, the interface between the dielectric layer and the internal electrode layer so as to close the discontinuous portion without penetrating the discontinuous portion. 2. The multilayer electronic component according to claim 1 , wherein a ratio of the needle-like segregated matter arranged along the internal electrode layer is 30% or more. The dielectric layer is composed of a dielectric ceramic composition represented by the general formula ABO ₃ and having a main component having a perovskite crystal structure and a subcomponent containing at least Mg and Cr,
100 to 100 mol of the main component contains 0.5 to 4 mol of Mg, 0.1 to 0.5 mol of Cr in terms of oxide, and the ratio of the number of moles of Mg and Cr (Mg / Cr) The laminated electronic component according to claim 1 or 2 , wherein is 2.5 to 20 .

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