JP4385381B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor.

  A multilayer ceramic capacitor as an example of a multilayer ceramic electronic component includes an element body having a structure in which a plurality of dielectric layers and internal electrode layers are alternately stacked, and a pair of external terminal electrodes formed at both ends of the element body. Consists of. In this multilayer ceramic capacitor, first, a pre-firing dielectric layer and a pre-firing internal electrode layer are alternately laminated in a necessary number to produce a pre-firing element body, and then, after firing this, the post-firing element body It is manufactured by forming a pair of external terminal electrodes at both ends.

  In the production of the multilayer ceramic capacitor, since the pre-firing dielectric layer and the pre-firing internal electrode layer are fired simultaneously, the conductive material contained in the pre-firing internal electrode layer includes a dielectric material contained in the pre-firing dielectric layer. It is required to have a melting point higher than the sintering temperature of the powder, not to react with the dielectric raw material powder, and not to diffuse into the dielectric layer after firing.

  In recent years, in order to satisfy these requirements, the conductive material contained in the internal electrode layer before firing is replaced with a noble metal such as Pt or Pd that has been conventionally used, and the sintering temperature of the dielectric material powder is lowered. Developed by using an Ag-Pd alloy as the conductive material contained in the internal electrode layer before firing, or using an inexpensive base metal such as Ni that can be fired in a reducing atmosphere by imparting reduction resistance to the dielectric material. Has been.

  The case where Ni is used for the conductive material contained in the internal electrode layer before firing is illustrated. Ni has a lower melting point than the dielectric raw material powder contained in the pre-firing dielectric layer. Therefore, when the pre-fired dielectric layer and the pre-fired internal electrode layer containing Ni as the conductive material are fired simultaneously, the firing of the dielectric raw material powder is caused by the difference in the sintering start temperature between the dielectric raw material powder and Ni. The Ni internal electrode becomes thicker as the crystallization progresses and eventually tends to be interrupted. Therefore, there is a technique for adding a dielectric material for addition as a sintering inhibitor to the internal electrode layer paste for forming the internal electrode layer for the purpose of suppressing discontinuity and sintering suppression due to this kind of firing. It has been proposed (see Patent Documents 1 to 5). This additive dielectric material has the property of diffusing from the internal electrode layer side to the interlayer dielectric layer side during simultaneous firing of the pre-fired interlayer dielectric layer and the pre-fired internal electrode layer.

  By the way, in recent years, with the miniaturization of various electronic devices, it has been required to realize a reduction in size / capacity, a reduction in price, and a high reliability of a multilayer ceramic capacitor mounted inside the electronic device. In order to meet such a demand, the thickness of the fired internal electrode layer and the fired interlayer dielectric layer disposed between the opposed fired internal electrode layers has been reduced. Specifically, the fired thickness per layer of the interlayer dielectric layer after firing has been reduced to about 1 μm, and accordingly the thickness before firing per layer of the interlayer dielectric layer before firing is also reduced. Layered.

  As the pre-firing interlayer dielectric layer is thinned, the content of the dielectric material per dielectric layer for forming it is reduced.

  For example, an internal electrode layer paste in which a dielectric material for addition is added at a predetermined weight ratio with respect to Ni as a conductive material is prepared, and the paste is made into a plurality of layers whose thickness before firing is gradually reduced. Consider a case where the pre-firing interlayer dielectric layer is applied and formed with a predetermined thickness. At this time, the weight ratio of the content of the dielectric material for addition in the internal electrode layer to the content of the dielectric material in the interlayer dielectric layer before firing (content of the dielectric material for addition in the internal electrode layer / firing) The content of the dielectric material in the previous interlayer dielectric layer) increases stepwise as the thickness of the pre-fired interlayer dielectric layer on which the internal electrode layer paste is applied and formed decreases. Become. This is because as the thickness of the interlayer dielectric layer before firing becomes thinner, the content of the dielectric material in the interlayer dielectric layer before firing decreases, and the denominator of the above weight ratio formula becomes smaller. As a result, the value of the weight ratio increases.

  This means that, when considered from the side of the interlayer dielectric layer before firing, the thinner the thickness, the relatively larger the amount of dielectric material for addition diffused from the internal electrode layer side. . That is, the relative diffusion amount from the internal electrode layer side to the interlayer dielectric layer side increases.

  In addition, along with the thinning of the interlayer dielectric layer before firing described above, the internal electrode layer before firing is also required to be thinned. In order to thin the internal electrode layer before firing, this is formed. In addition to the conductive material such as Ni in the internal electrode layer paste to be made, miniaturization of the dielectric material for addition is required.

  However, if the additive dielectric material diffusing from the internal electrode layer side to the interlayer dielectric layer side is miniaturized during firing, it promotes the grain growth of the dielectric particles constituting the interlayer dielectric layer. May affect the microstructure of the interlayer dielectric layer. This is especially true when the diffusion amount of the dielectric material for addition from the internal electrode layer side to the interlayer dielectric layer side increases. When the thickness of the interlayer dielectric layer after firing was 2.0 μm or more, the influence on the microstructure could be ignored, but when the thickness of the interlayer dielectric layer after firing was reduced to less than 2.0 μm The influence on the fine structure increases, and with the influence of the fine structure, various characteristics such as bias characteristics and reliability of the obtained multilayer ceramic capacitor may be deteriorated.

As a solution to these problems, Patent Document 6 proposes a technique for adjusting the additive composition to the internal electrode layer paste. According to the technique described in Patent Document 6, the dielectric layer can be thinned without deteriorating the temperature characteristics, tan δ, and lifetime, but there is a problem that the improvement of the bias characteristics is not sufficient. Was.
JP-A-5-62855 JP 2000-277369 A JP 2001-307939 A JP 2003-77761 A Japanese Patent Application Laid-Open No. 2003-100544 JP 2003-1224049 A

  It is an object of the present invention to produce multilayer ceramic electronic components such as multilayer ceramic capacitors that have various electrical characteristics, particularly a sufficient dielectric constant and improved TC bias characteristics even when the interlayer dielectric layer is thinned. Is to provide a way to do.

In order to achieve the above object, according to a first aspect of the present invention,
A method of manufacturing a multilayer ceramic electronic component having an internal electrode layer and a dielectric layer having a thickness of less than 2 μm,
Firing a laminate formed using a dielectric layer paste containing a dielectric material and an internal electrode layer paste containing a dielectric material for addition,
The dielectric material in the dielectric layer paste includes a main component material and a subcomponent material,
The dielectric material for addition in the internal electrode layer paste includes at least a main component material for addition,
The main component material for addition has substantially the same composition system as the main component material contained in the dielectric material in the dielectric layer paste, and has a lattice constant of more than 3.991% and less than 4.064%. A method for producing a multilayer ceramic electronic component is provided.
Preferably, the main component material for addition has an OH group release amount of more than 10 and less than 266.

According to a second aspect, there is provided a method of manufacturing a multilayer ceramic electronic component having an internal electrode layer and a dielectric layer having a thickness of less than 2 μm,
Firing a laminate formed using a dielectric layer paste containing a dielectric material and an internal electrode layer paste containing a dielectric material for addition,
The dielectric material in the dielectric layer paste includes a main component material and a subcomponent material,
The dielectric material for addition in the internal electrode layer paste includes at least a main component material for addition,
The main component material for addition has substantially the same composition system as the main component material contained in the dielectric material in the dielectric layer paste, and has an OH group emission amount of more than 10 and less than 266 A method for manufacturing a multilayer ceramic electronic component is provided.

  Preferably, the main component material for addition has a lattice constant of more than 3.991 and less than 4.064.

According to the third aspect,
A method of manufacturing a multilayer ceramic electronic component having an internal electrode layer and a dielectric layer having a thickness of less than 2 μm,
Firing a laminate formed using a dielectric layer paste containing a dielectric material and an internal electrode layer paste containing a dielectric material for addition,
The dielectric material in the dielectric layer paste includes a main component material and a subcomponent material,
The dielectric material for addition in the internal electrode layer paste includes at least a main component material for addition,
The additive main component material has substantially the same composition system as the main component material contained in the dielectric material in the dielectric layer paste, and has a lattice constant of more than 3.991% and less than 4.064%, Provided is a method for producing a multilayer ceramic electronic component characterized by having an OH group emission amount of more than 10 and less than 266.

In the method of the present invention, “substantially the same composition system” means that the type of each element and the type of each element are the same in addition to the case where the composition molar ratio of each element completely matches. However, it is intended to include the case where the composition molar ratio is slightly different. In the former case, for example, when the main component material contained in the dielectric material in the dielectric layer paste is (BaO) _m TiO ₂ (where m = 1), the addition in the internal electrode layer paste This is a case where the main component raw material for addition contained in the dielectric raw material is (BaO) _{m ′} TiO ₂ (where m ′ = 1). In the latter case, for example, when the main component material is (BaO) _m TiO ₂ (where m = 1), the main component material for addition is (BaO) _{m ′} TiO ₂ (where m ′ = 0. 990 to 1.050).

Preferably, the main component material is represented by a composition formula (AO) _m · BO ₂ , the symbol A in the formula is at least one element selected from Sr, Ca, and Ba, and the symbol B is Ti and Zr. A dielectric oxide having a molar ratio m in the above formula of m = 0.990 to 1.035. More preferably, the main component material is barium titanate represented by a composition formula (BaO) _m · TiO ₂ and a molar ratio m in the formula is m = 0.990 to 1.035.

Preferably, the additive main component material is represented by a composition formula (AO) _{m ′} · BO ₂ , wherein the symbol A is at least one element selected from Sr, Ca and Ba, and the symbol B is The dielectric oxide is at least one element of Ti and Zr, and the molar ratio m ′ in the above formula is 0.993 <m ′ <1.050. More preferably, the main component material for addition is barium titanate represented by a composition formula (BaO) _{m ′} · TiO ₂ , and the molar ratio m ′ in the formula is 0.993 <m ′ <1.050. is there.

  The additive dielectric material used in the method of the present invention may be any material as long as it contains “at least the main component material for addition”, and may further contain a subcomponent material for addition. In this case, the subcomponent raw material for addition may be the same as or different from the composition of the subcomponent raw material contained in the dielectric raw material in the dielectric layer paste.

  In the method of the present invention, at least if the main component material for addition contained in the dielectric material for addition and the main component material contained in the dielectric material in the dielectric layer paste are substantially the same composition system Good. Accordingly, when the additive dielectric material includes an additive subcomponent material in addition to the additive main component material, (1) only the additive main component material that is a part of the additive dielectric material is dielectric. The composition system may be substantially the same as the main component material contained in the dielectric material in the body layer paste. In other words, the composition of the additive subcomponent material that is the balance of the additive dielectric material may be different from the composition of the subcomponent material contained in the dielectric material in the dielectric layer paste. (2) All of the dielectric material for addition (which naturally includes the main component material for addition) is substantially the same as all of the dielectric material (which naturally includes the main component material) in the dielectric layer paste. The same composition system may be used.

  The material constituting the internal electrode layer of the multilayer ceramic capacitor is not particularly limited in the present invention, and a noble metal can be used in addition to the base metal. When the internal electrode layer is made of a base metal, the dielectric layer includes Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and R (R) in addition to the main component such as barium titanate. May contain subcomponents including one or more kinds of oxides of one or more rare earth elements such as Y) and compounds that become these oxides upon firing. By containing an auxiliary component, even if baked in a reducing atmosphere, it is not made into a semiconductor, and the characteristics as a capacitor can be maintained. Thus, when manufacturing a multilayer ceramic capacitor having a dielectric layer containing subcomponents in addition to the main component, the dielectric material contained in the dielectric layer paste contains the main component and subcomponents after firing. Contains the main component raw material and subcomponent raw material to be formed. In this case, as described above, the additive dielectric material contained in the internal electrode layer paste contains the additive subcomponent material in addition to the additive main component material.

Preferably, the dielectric layer contains barium titanate represented by a composition formula (BaO) _m · TiO ₂ as a main component, wherein the molar ratio m is m = 0.990 to 1.035. It contains magnesium oxide and rare earth element oxide as components, and is further selected from at least one selected from barium oxide and calcium oxide as another accessory component, and from silicon oxide, manganese oxide, vanadium oxide, and molybdenum oxide. Containing at least one species.

At this time, the dielectric material for addition contained in the internal electrode layer paste is represented by the composition formula (BaO) _{m ′} · TiO ₂ as the main component material for addition, and the molar ratio m ′ in the formula is 0.993. <M ′ <1.050, further containing a barium titanate having a lattice constant of more than 3.991 Å and less than 4.064 及 び and / or an OH group emission amount of more than 10 and less than 266, Containing magnesium oxide (including a compound that becomes magnesium oxide after firing) and an oxide of a rare earth element, and as other subcomponents barium oxide (including a compound that becomes barium oxide after firing) and calcium oxide (after firing) At least one selected from calcium oxide compounds), silicon oxide, manganese oxide (including compounds that become manganese oxide after firing), vanadium oxide Preferably contains at least one selected from the presence and molybdenum oxide.

  In the present invention, the dielectric layer simply expressed as “dielectric layer” means one or both of the interlayer dielectric layer and the outer dielectric layer.

According to the present invention, the composition system of the main component material for addition contained in the dielectric material for addition in the internal electrode layer paste (for example, so-called A / B, that is, the A site (“(BaO)” in the above formula)). Part) and the B site (the part of “TiO ₂ ” in the above formula) m ′), the lattice constant, and the amount of OH group released. By using barium titanate with various conditions controlled as described above as the main component material for addition, the presence state of the dielectric particles constituting the interlayer dielectric layer after firing is suitably controlled. As a result, even when the thickness of the interlayer dielectric layer is reduced to less than 2 μm, various electrical characteristics, in particular, TC bias characteristics are more preferably improved while having a sufficient dielectric constant (specifically, TC measured at a bias voltage of 120 Hz, 0.5 Vrms, 2 V / μm in a constant temperature bath maintained at 85 ° C., and the capacity change rate from the measured value when no bias voltage was applied at 20 ° C. was −20% or more. With bias characteristics).

  Although it does not specifically limit as a multilayer ceramic electronic component, Surface mount (SMD) chip-type electronic components, such as a multilayer ceramic capacitor, a piezoelectric laminated body component, a chip varistor, a chip thermistor, are illustrated.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention, and FIG. 2 is a graph showing temperature changes during binder removal, firing and annealing in the examples.

  In the present embodiment, as the multilayer ceramic electronic component, a plurality of internal electrode layers and interlayer dielectric layers are alternately stacked, and outer dielectric layers are formed at both outer ends of the internal electrode layers and interlayer dielectric layers in the stacking direction. A multilayer ceramic capacitor in which is disposed will be described as an example.

Multilayer Ceramic Capacitor 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 interlayer dielectric layers 2 and internal electrode layers 3 are alternately stacked. A pair of external electrodes 4 are formed at both ends of the capacitor element body 10 so as to be electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. The internal electrode layers 3 are laminated such that the side 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.

  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, however, the length (0.4 to 5.6 mm) × width (0.2 to 5.0 mm) × height It is about (0.2-1.9 mm).

  In the capacitor element body 10, outer dielectric layers 20 are disposed at both outer end portions in the stacking direction of the internal electrode layer 3 and the interlayer dielectric layer 2 to protect the inside of the element body 10.

The composition of the interlayer dielectric layer 2 and the outer dielectric layer 20 is not particularly limited in the present invention, and is composed of, for example, the following dielectric ceramic composition.
The dielectric ceramic composition of the present embodiment contains, as a main component, barium titanate represented by a composition formula (BaO) _m · TiO ₂ and having a molar ratio m of m = 0.990 to 1.035. To do.

  The dielectric ceramic composition of the present embodiment contains subcomponents together with the main component. As subcomponents, there are oxides of Mn, Cr, Ca, Ba, Mg, V, W, Ta, Nb and R (R is one or more of rare earth elements such as Y) and compounds that become oxides by firing. What contains more than a kind is illustrated. By adding the subcomponent, the characteristics as a capacitor can be obtained even in firing in a reducing atmosphere. As impurities, trace components such as C, F, Li, Na, K, P, S, and Cl may be contained in an amount of about 0.1 wt% or less. However, in the present invention, the composition of the interlayer dielectric layer 2 and the outer dielectric layer 20 is not limited to the above.

In the present embodiment, as the interlayer dielectric layer 2 and the outer dielectric layer 20, those having the following compositions are preferably used. The composition is represented by a composition formula (BaO) _m · TiO ₂ as a main component, and contains barium titanate having a molar ratio m of m = 0.990 to 1.035, and magnesium oxide as an accessory component. And at least one selected from the group consisting of barium oxide and calcium oxide, and at least one selected from silicon oxide, manganese oxide, vanadium oxide, and molybdenum oxide. It contains. Then, barium titanate is [(BaO) _{0.990 to 1.035} · TiO ₂ ], magnesium oxide is MgO, rare earth oxide is R ₂ O ₃ , barium oxide is BaO, and calcium oxide is to CaO, silicon oxide to SiO _2, manganese oxide to MnO, vanadium oxide to _V 2 _{O 5,} when converted respectively molybdenum oxide to _{MoO 3, [(BaO) 0.990~1.035} · TiO 2 The ratio to 100 mol is MgO: 0.1 to 3 mol, R ₂ O ₃ : more than 0 mol to 5 mol or less, BaO + CaO: 0.5 to 12 mol, SiO ₂ : 0.5 to 12 mol, MnO: 0 mol More than 0.5 mol, V ₂ O ₅ : 0 to 0.3 mol, MoO ₃ : 0 to 0.3 mol.

  Various conditions such as the number of laminated layers and thickness of the interlayer dielectric layer 2 may be appropriately determined according to the purpose and application. In this embodiment, the thickness of the interlayer dielectric layer 2 is preferably less than 2 μm, more preferably The layer is thinned to 1.5 μm or less, more preferably 1 μm or less. In the present embodiment, even when the thickness of the interlayer dielectric layer 2 is reduced as described above, various electrical characteristics of the capacitor 1, particularly TC bias characteristics are improved while having a sufficient dielectric constant. The thickness of the outer dielectric layer 20 is, for example, about 30 μm to several hundred μm.

  The interlayer dielectric layer 2 and the outer dielectric layer 20 are configured to include a plurality of dielectric particles and a grain boundary phase formed between a plurality of adjacent dielectric particles. The grain boundary phase usually includes an oxide of a material constituting the dielectric material or the internal electrode material, an oxide of a material added separately, or an oxide of a material mixed as an impurity during the process.

  The internal electrode layer 3 is made of a base metal conductive material that substantially functions as an electrode. 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 selected from Mn, Cr, Co, Al, Ru, Rh, Ta, Re, Os, Ir, Pt and W, and the Ni content in the alloy is It is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components such as P, C, Nb, Fe, Cl, B, Li, Na, K, F, and S may be contained in an amount of about 0.1% by weight or less. .

  In the present embodiment, the thickness of the internal electrode layer 3 is preferably reduced to less than 2 μm, more preferably 1.5 μm or less.

  As the external electrode 4, at least one of Ni, Pd, Ag, Au, Cu, Pt, Rh, Ru, Ir, or an alloy thereof can be used. Usually, Cu, Cu alloy, Ni, Ni alloy, etc., Ag, Ag—Pd alloy, In—Ga alloy, etc. are used. Although the thickness of the external electrode 4 should just be determined timely according to a use, it is preferable that it is normally about 10-200 micrometers.

Method for Manufacturing Multilayer Ceramic Capacitor Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 according to this embodiment will be described.

(1) First, the dielectric layer paste that will form the interlayer dielectric layer 2 and the outer dielectric layer 20 shown in FIG. 1 after firing, and the internal electrode layer 3 shown in FIG. 1 after firing. An internal electrode layer paste is prepared.
Dielectric layer paste
The dielectric layer paste is prepared by kneading a dielectric material and an organic vehicle.

  The dielectric material includes a main component material and a subcomponent material that form the main component and subcomponents constituting the dielectric layers 2 and 20 after firing. Each of these component raw materials can be appropriately selected from various compounds to be composite oxides and oxides, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like, and can be used in combination.

  The dielectric material is usually used as a powder having an average particle size of 0.4 μm or less, preferably about 0.05 to 0.35 μm. Here, the average particle diameter is a value obtained by observing the raw material grains with an SEM and converting them to equivalent circle diameters.

  The organic vehicle contains a binder and a solvent. As a binder, various usual binders, such as ethyl cellulose, polyvinyl butyral, an acrylic resin, can be used, for example. The solvent is not particularly limited, and organic solvents such as terpineol, butyl carbitol, acetone, toluene, xylene and ethanol are used.

  The dielectric layer paste can also be formed by kneading a dielectric material and a vehicle in which a water-soluble binder is dissolved in water. The water-soluble binder is not particularly limited, and polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, water-soluble acrylic resin, emulsion and the like are used.

  The content of each component in the dielectric layer paste is not particularly limited. For example, the dielectric layer paste can be prepared so as to contain about 1 to about 50% by weight of a solvent.

  The dielectric layer paste may contain additives selected from various dispersants, plasticizers, dielectrics, subcomponent compounds, glass frit, insulators, and the like, if necessary. When these additives are added to the dielectric layer paste, the total content is desirably about 10% by weight or less.

Internal Electrode Layer Paste In this embodiment, the internal electrode layer paste is prepared by kneading a conductive material, an additive dielectric material, and an organic vehicle.

  As the conductive material, Ni, Ni alloy, or a mixture thereof is used. There are no particular restrictions on the shape of such a conductive material, such as a spherical shape or a flake shape, and a mixture of these shapes may be used. In addition, the particle diameter of the conductive material is usually a spherical one having an average particle diameter of 0.5 μm or less, preferably about 0.01 to 0.4 μm. This is because a more advanced thinning can be realized. The conductive material is preferably contained in the internal electrode layer paste in an amount of 35 to 60% by weight.

  The dielectric material for addition has an effect of suppressing sintering of the internal electrode (conductive material) during the firing process.

  In this embodiment, the dielectric material for addition contains the main component material for addition and the subcomponent material for addition. In the present embodiment, at least the main component material for addition contained in the dielectric material for addition and the main component material contained in the dielectric material in the dielectric layer paste have substantially the same composition system. That's fine. Therefore, only the main component material for addition that is a part of the dielectric material for addition may be substantially the same composition system as the main component material contained in the dielectric material in the dielectric layer paste. Further, all of the dielectric material for addition may be substantially the same composition system as all of the dielectric material in the dielectric layer paste. In this way, by making at least the main component material for addition and the main component material substantially the same composition system, the dielectric layers 2 and 20 by diffusion from the internal electrode layer 3 to the dielectric layers 2 and 20 can be obtained. Does not change the composition.

In this embodiment, the main component material for addition is represented by the composition formula (BaO) _{m ′} · TiO ₂ , and the molar ratio m ′ in the formula is 0.993 <m ′ <1.050, preferably 0.8. Barium titanate satisfying 995 ≦ m ′ ≦ 1.035, more preferably 1.000 ≦ m ′ ≦ 1.020 is used. By using barium titanate in which the value of m ′ of the main component material for addition is adjusted, the presence state of the dielectric particles constituting the interlayer dielectric layer 2 after firing is controlled. The electrical characteristics, particularly the TC bias characteristics are improved while having a sufficient dielectric constant. If m ′ becomes too large, there is a tendency for sintering to be insufficient.

  In the first aspect of the present embodiment, a material having a specific lattice constant is used as the main component material for addition in the dielectric material for addition. By using a main component material having a specific lattice constant as an additive, various electrical characteristics of the finally obtained capacitor 1 can be improved. The lattice constant of the main component raw material for addition is more than 3.991 Å and less than 4.064 、, preferably more than 4.0000 Å and less than 4.057 、, more preferably 4.004 Å to 4.0475 Å. If the lattice constant is too small or too large, there is a tendency that various electrical characteristics cannot be improved.

  In the second aspect of the present embodiment, a material having a specific OH group emission amount is used as the main component material for addition in the dielectric material for addition. By using a main component material having a specific OH group emission amount for addition, various electrical characteristics of the finally obtained capacitor 1 can be improved. The amount of OH group released from the main ingredient for addition is more than 10 and less than 266, preferably 25 to 250, more preferably 25 to 150. If the amount of OH group released is too small or too large, there is a tendency that various electrical characteristics cannot be improved.

  The average particle size of the main component material for addition may be the same as the particle size of the main component material contained in the dielectric material in the dielectric layer paste, but is preferably smaller, more preferably 0.01-0. .2 μm, particularly preferably 0.01 to 0.15 μm. In addition, it is known that the value of an average particle diameter has a correlation with a specific surface area (SSA).

  The dielectric material for addition (in some cases, only the main component material for addition or in some cases includes both the main component material for addition and the subcomponent material for addition. The same applies hereinafter unless otherwise specified) However, it is preferably produced through steps such as an oxalate method, a hydrothermal synthesis method, a sol-gel method, a hydrolysis method, and an alkoxide method. By using this method, a dielectric material having the above lattice constant and OH group emission amount can be efficiently produced.

  The dielectric material for addition is contained in the internal electrode layer paste in an amount of preferably 10 to 30% by weight, more preferably 15 to 20% by weight, based on the conductive material. If the content of the dielectric material for addition is too small, the effect of suppressing the sintering of the conductive material is lowered, and if it is too much, the continuity of the internal electrode is lowered. That is, if the amount of the dielectric material for addition is too small or too large, inconveniences such as inability to secure a sufficient capacitance as a capacitor can occur.

  The organic vehicle contains a binder and a solvent.

  Examples of the binder include ethyl cellulose, acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, and copolymers thereof. The binder is preferably contained in the internal electrode layer paste in an amount of 1 to 5% by weight with respect to the mixed powder of the conductive material and the dielectric material for addition. If the amount of the binder is too small, the strength tends to decrease. If the amount is too large, the metal filling density of the electrode pattern before firing decreases, and it becomes difficult to maintain the smoothness of the internal electrode layer 3 after firing. is there.

  As the solvent, any known solvent such as terpineol, dihydroterpineol, butyl carbitol, and kerosene can be used. The solvent content is preferably about 20 to 50% by weight with respect to the entire paste.

  The internal electrode layer paste may contain a plasticizer. Examples of the plasticizer include phthalic acid esters such as benzylbutyl phthalate (BBP), adipic acid, phosphoric acid esters, glycols, and the like.

  (2) Next, a green chip is produced using the dielectric layer paste and the internal electrode layer paste. When the printing method is used, the dielectric layer paste and the internal electrode layer paste having a predetermined pattern are stacked and printed on the carrier sheet, cut into a predetermined shape, and then peeled off from the carrier sheet to obtain a green chip. When using the sheet method, a dielectric layer paste is formed on a carrier sheet with a predetermined thickness to form a green sheet, and the internal electrode layer paste is printed in a predetermined pattern on the green sheet. Laminate to make a green chip.

  (3) Next, the obtained green chip is debindered. For example, as shown in FIG. 2, the debinder increases the ambient temperature T0 from, for example, room temperature (25 ° C.) toward the debuy holding temperature T1 at a predetermined heating rate, and holds the T1 for a predetermined time. Thereafter, the temperature is lowered at a predetermined temperature lowering rate.

In the present embodiment, the rate of temperature rise is preferably 5 to 300 ° C./hour, more preferably 10 to 100 ° C./hour. The de-bye holding temperature T1 is preferably 200 to 400 ° C, more preferably 220 to 380 ° C,
The T1 holding time is preferably 0.5 to 24 hours, more preferably 2 to 20 hours. The temperature lowering rate is preferably 5 to 300 ° C./hour, more preferably 10 to 100 ° C./hour. The treatment atmosphere of the binder removal is preferably air or a reducing atmosphere. As the atmosphere gas in the reducing atmosphere, it is preferable to use, for example, a wet mixed gas of N ₂ and H ₂ . The oxygen partial pressure in the treatment atmosphere is preferably 10 ⁻⁴⁵ to 10 ⁵ Pa. If the oxygen partial pressure is too low, the binder removal effect is reduced, and if it is too high, the internal electrode layer tends to be oxidized.

  (4) Next, the green chip is fired. For example, as shown in FIG. 2, the firing is performed by increasing the ambient temperature T0 from a room temperature (25 ° C.) toward a firing holding temperature T2, for example, at a predetermined heating rate, and holding the T2 for a predetermined time. This is a step of lowering the ambient temperature at a predetermined temperature drop rate.

  In the present embodiment, the rate of temperature rise is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. The firing holding temperature T2 is preferably 1100 to 1350 ° C, more preferably 1100 to 1300 ° C, still more preferably 1150 to 1250 ° C, and the holding time of T2 is preferably 0.5 to 8 hours, more preferably 1 to 3 hours. If T2 is too low, densification will be insufficient even if the holding time of T2 is lengthened. If it is too high, discontinuity of the electrode due to abnormal sintering of the internal electrode layer, or diffusion of the conductive material constituting the internal electrode layer Deterioration of the capacitance-temperature characteristics due to the above, and reduction of the dielectric ceramic composition constituting the dielectric layer is likely to occur.

The temperature lowering rate is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour. The treatment atmosphere for firing is preferably a reducing atmosphere. As the atmosphere gas in the reducing atmosphere, it is preferable to use, for example, a wet mixed gas of N ₂ and H ₂ .

The oxygen partial pressure in the firing atmosphere is preferably 6 × 10 ⁻⁹ to 10 ⁻⁴ Pa. If the oxygen partial pressure is too low, the conductive material of the internal electrode layer may be abnormally sintered and interrupted, and if it is too high, the internal electrode layer tends to oxidize.

  (5) Next, when the green chip is fired in a reducing atmosphere, it is preferable to perform a heat treatment (annealing) subsequently. Annealing is a process for re-oxidizing the dielectric layer, thereby obtaining the characteristics of the final capacitor.

  For example, as shown in FIG. 2, the annealing is performed by increasing the ambient temperature T0 from, for example, room temperature (25 ° C.) toward the annealing holding temperature T3 at a predetermined heating rate, and holding T3 for a predetermined time. This is a step of lowering the ambient temperature T0 at a predetermined temperature drop rate.

  In the present embodiment, the rate of temperature rise is preferably 100 to 300 ° C./hour, more preferably 150 to 250 ° C./hour. The annealing holding temperature T3 is preferably 800 to 1100 ° C., more preferably 900 to 1100 ° C., and the holding time of T3 is preferably 0 to 20 hours, more preferably 2 to 10 hours. If T3 is too low, oxidation of the dielectric layer 2 becomes insufficient, so the IR is low and the IR life tends to be short. If T3 is too high, not only will the internal electrode layer 3 oxidize and the capacity will decrease, but the internal electrode layer 3 will react with the dielectric substrate, causing deterioration in capacity-temperature characteristics, IR, and IR life. Is likely to occur.

The temperature lowering rate is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. The annealing treatment atmosphere is preferably a neutral atmosphere. As the atmospheric gas in the neutral atmosphere, for example, it is preferable to use humidified N ₂ gas. In the annealing, the temperature may be changed to the holding temperature T3 in an N ₂ gas atmosphere, and the atmosphere may be changed, or the entire annealing process may be a humidified N ₂ gas atmosphere. The oxygen partial pressure in the annealing atmosphere is preferably 2 × 10 ^{−4 to 1} Pa. If the oxygen partial pressure is too low, reoxidation of the dielectric layer 2 is difficult, and if it is too high, the internal electrode layer 3 tends to oxidize.

  In the present embodiment, the annealing may be composed of only a temperature raising process and a temperature lowering process. That is, the temperature holding time may be zero. In this case, the holding temperature T3 is synonymous with the maximum temperature.

In the above-described binder removal processing, firing and annealing, for example, a wetter or the like may be used to wet the N ₂ gas or mixed gas. In this case, the water temperature is preferably about 0 to 75 ° C.

  The binder removal, firing, and annealing may be performed continuously or may be performed separately.

  The capacitor element body 10 made of a sintered body is formed by the above processes.

  (6) Next, the external electrode 4 is formed on the obtained capacitor element body 10. The external electrode 4 is formed by polishing the end face of the capacitor element body 10 composed of the sintered body by, for example, barrel polishing or sand blasting, and then, generally, Ni, Pd, Ag, Au, Cu, It can be formed by a known method such as baking an external electrode paste containing at least one of Pt, Rh, Ru, Ir, or an alloy thereof, or applying an In—Ga alloy. If necessary, a coating layer may be formed on the surface of the external electrode 4 by plating or the like.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  For example, in the above-described embodiment, the binder removal processing, firing, and annealing are performed independently, but the present invention is not limited to this, and at least two steps may be performed continuously. In the case of performing continuously, after removing the binder, the atmosphere is changed without cooling, the temperature is raised to the holding temperature T2 at the time of firing, firing is performed, and then the temperature is lowered to reach the annealing holding temperature T3. Sometimes it is preferable to perform annealing by changing the atmosphere.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.

Example 1
Preparation of Dielectric Layer Paste First, a dielectric material, PVB (polyvinyl butyral) resin as a binder, DOP (dioctyl phthalate) as a plasticizer, and ethanol as a solvent were prepared. As the dielectric material, a plurality of BaTiO ₃ having an average particle diameter of about 0.2 μm as a main component material is prepared, and for each BaTiO ₃ , MnCO ₃ : 0.2 mol%, MgO: 0.5 _{mol%, V} 2 O 5: 0.3 _mol%, Y _{2 O} 3: 2 mol%, CaCO _3: 3 mol%, BaCO _3: 3 mol%, _SiO 2: 3 mol%, a ball mill It was produced by wet mixing for 16 hours and drying.

  Next, 10% by weight of binder, 5% by weight of plasticizer, and 150% by weight of solvent are weighed with respect to the dielectric material, kneaded with a ball mill, and slurried to obtain a dielectric layer paste. Obtained.

Preparation of Internal Electrode Layer Paste Ni particles having an average particle diameter of 0.4 μm as a conductive material, an additive dielectric material, an ethyl cellulose resin as a binder, and terpineol as a solvent were prepared.

Examples of the dielectric material for addition include BaTiO ₃ as the main component material for addition and MnCO ₃ , MgO as the subcomponent material for addition, having the same composition system as the dielectric material in the dielectric layer paste. , V ₂ O ₅ , Y ₂ O ₃ , CaCO ₃ , BaCO ₃ and SiO ₂ were used. However, for BaTiO ₃ as the main ingredient material for addition, a material in which the lattice constant and the amount of OH group released were changed for each sample as shown in each table.

  The lattice constant of the main component raw material for addition in each table is obtained by measuring the angle range of 10 to 85 degrees using XRD (Rent 2000 manufactured by Rigaku Corporation) in which the current is set to 300 mA and the acceleration voltage is set to 50 kV. It is a value calculated as a cubic lattice constant from the obtained peak position (unit: Å).

Moreover, the OH group release amount of the main ingredient for addition in each table is FT-IR (Fourier transform infrared spectroscopy) using a sample obtained by diluting about 5 mg of the main ingredient for addition with about 100 mg of KBr. It is a peak intensity of 3510 cm ⁻¹ due to —OH stretching vibration by a diffuse reflection method.

  Next, 20% by weight of dielectric material for addition was added to the conductive material. 5% by weight of binder and 35% by weight of solvent are weighed and added to the mixed powder of conductive material and dielectric material for addition, kneaded with a ball mill, and slurried to obtain an internal electrode layer paste. It was.

Production of Multilayer Ceramic Chip Capacitor Sample Using the obtained dielectric layer paste and internal electrode layer paste, a multilayer ceramic chip capacitor 1 shown in FIG. 1 was produced as follows.

  First, a dielectric layer paste was applied to a predetermined thickness on a PET film by a doctor blade method and dried to form a ceramic green sheet having a thickness of 2 μm. In this example, this ceramic green sheet was used as the first green sheet, and a plurality of these were prepared.

  On the obtained first green sheet, the internal electrode layer paste was formed in a predetermined pattern by screen printing to obtain a ceramic green sheet having an electrode pattern with a thickness of about 1 μm. In this example, this ceramic green sheet was used as the second green sheet, and a plurality of these were prepared.

The first green sheets were laminated to a thickness of 300 μm to form a green sheet group. On the green sheet group, the second green sheets were stacked 11 sheets, this on the further the same green sheet group laminated form, and heating at a temperature of 80 ° C. and a pressure 1 ton / cm ² Pressurized to obtain a green laminate.

  Next, the obtained laminate was cut into a size of 3.2 mm in length, 1.6 mm in width, and 1.0 mm in height, and then subjected to binder removal treatment, firing and annealing under the following conditions to obtain a sintered body. Obtained. FIG. 2 shows a graph showing each temperature change of the binder removal processing, firing and annealing.

  The binder removal was performed under the conditions of a temperature rising rate: 30 ° C./hour, a holding temperature T1: 250 ° C., a holding time: 8 hours, a temperature falling rate: 200 ° C./hour, and a processing atmosphere: an air atmosphere.

Firing is performed at a heating rate of 200 ° C./hour, a holding temperature T2: 1240 ° C., a holding time of 2 hours, a cooling rate of 200 ° C./hour, a processing atmosphere: a reducing atmosphere (oxygen partial pressure: 10 ⁻⁶ Pa to N ₂ And a mixed gas of H ₂ was adjusted by passing water vapor).

As for annealing, temperature rising rate: 200 ° C./hour, holding temperature T3: 1050 ° C., holding time: 2 hours, cooling rate: 200 ° C./hour, treatment atmosphere: neutral atmosphere (oxygen partial pressure: 0.1 Pa to N ₂ The gas was adjusted by passing water vapor).

  A wetter was used to wet the gas during firing and annealing, and the water temperature was 20 ° C.

  After polishing the end surface of the obtained sintered body with sand blasting, an In—Ga alloy was applied to form a test electrode, and a multilayer ceramic chip capacitor sample was obtained. The size of the capacitor sample is 3.2 mm long × 1.6 mm wide × 1.0 mm high, the thickness x of the interlayer dielectric layer 2 is about 1.3 μm, and the thickness of the internal electrode layer 3 is 0.9 μm. It was. Similarly, a capacitor sample in which the thickness x of the interlayer dielectric layer 2 was about 1.1 μm was also produced.

  TC bias characteristics, temperature characteristics, and relative dielectric constant ε of the obtained capacitor samples were evaluated. However, only the TC bias characteristic and the relative dielectric constant were evaluated for the capacitor sample having the thickness x of the interlayer dielectric layer 2 of about 1.3 μm.

  Regarding the TC bias characteristics, the capacitor sample was measured with a LCR meter at a constant voltage of 120 Hz, 0.5 Vrms, 2 V / μm in a constant temperature bath maintained at 85 ° C., and a 20 ° C. bias voltage was not applied. The capacity change rate from the measured value was calculated and evaluated. The evaluation criteria were good when the dielectric thickness was 1.3 μm and larger than −23% and when the dielectric thickness was 1.1 μm and larger than −25%.

  For temperature characteristics (TC), measure with a LCR meter at 120 Hz, 0.5 Vrms, 0.5 V / μm in a constant temperature bath at 85 ° C., and calculate the capacity change rate from the measured value at 20 ° C. evaluated. The evaluation criteria was good to be greater than -7.0%.

  The relative dielectric constant ε was measured with respect to a capacitor sample at a reference temperature of 25 ° C. with a digital LCR meter (YHP 4274A) under a frequency of 1 kHz and an input signal level (measurement voltage) of 1.0 Vrms. Calculated from capacitance (no unit). The evaluation criteria were 1800 or more when the dielectric thickness was 1.3 μm and 1700 or more when the dielectric thickness was 1.1 μm.

The results are shown in Tables 1-2.

As shown in Table 1, in the capacitor sample having an interlayer dielectric layer thickness of 1.3 μm, Sample 1 in which the lattice constant of BaTiO ₃ as the main component material for addition is 3.991 Å or less has good TC bias characteristics. Although the value is shown, the relative dielectric constant ε is inferior. In the sample 7 having a lattice constant of 4.064Å or more, both the TC bias characteristics and ε are inferior. On the other hand, it was confirmed that Samples 2 to 6 within the scope of the present invention having a lattice constant of more than 3.991 mm and less than 4.064 mm have excellent TC bias characteristics as well as ε.

In the sample 1 in which the amount of released OH groups of BaTiO ₃ is 10 or less, the TC bias characteristic shows a good value, but the relative dielectric constant ε is inferior. In Sample 7 in which the amount of OH group released is 266 or more, both the TC bias characteristics and ε are inferior. On the other hand, it was confirmed that Samples 2 to 6 within the scope of the present invention having an OH group release amount of more than 10 and less than 266 have excellent TC bias characteristics as well as ε.

In particular, Samples 2 to 4 have a TC bias characteristic of −20% or more, and it can be confirmed that this characteristic is extremely improved.

As shown in Table 2, in the capacitor sample having an interlayer dielectric layer thickness of 1.1 μm, in the sample 8 in which the lattice constant of BaTiO ₃ as the main component material for addition is 3.991 mm or less, the TC bias characteristics and the temperature characteristics Although TC shows a good value, the relative dielectric constant ε is inferior. In the sample 13 having a lattice constant of 4.064Å or more, both the TC bias characteristics and the temperature characteristics TC and ε are inferior. On the other hand, it was confirmed that Samples 9 to 13 within the scope of the present invention having a lattice constant of more than 3.991 mm and less than 4.064 mm have excellent TC bias characteristics and temperature characteristics TC as well as ε.

In the sample 8 in which the amount of released OH groups of BaTiO ₃ is 10 or less, the TC bias characteristic and the temperature characteristic TC show good values, but the relative dielectric constant ε is inferior. In the sample 13 in which the amount of OH group released is 266 or more, both the TC bias characteristics and the temperature characteristics TC and ε are inferior. On the other hand, it was confirmed that Samples 9 to 12 within the scope of the present invention having an OH group release amount of more than 10 and less than 266 have excellent TC bias characteristics and temperature characteristics TC as well as ε.

Example 2
Capacitor samples were prepared and evaluated in the same manner as in Example 1 except that the thickness of the interlayer dielectric layer 2 was changed to 1.9 μm, 1.7 μm, 1.5 μm, and 0.9 μm. As a result, similar results were obtained.

Comparative Example 1
A capacitor sample was prepared in the same manner as in Example 1 except that the thickness of the interlayer dielectric layer 2 was changed to 2.0 μm and 2.2 μm, and the same evaluation was performed.
As a result, when the thickness of the interlayer dielectric layer 2 is 2 μm or more, since the influence of the dielectric material for addition is small, almost no grain growth of the dielectric layer is observed, and ceramic particles in the internal electrode layer (for addition) Almost no difference was observed in the average particle size of the dielectric particles of the interlayer dielectric layer 2 due to the dielectric material).

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a graph showing temperature changes in the binder removal processing, firing, and annealing in the examples.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor element main body 2 ... Interlayer dielectric layer 20 ... Outer dielectric layer 3 ... Internal electrode layer 4 ... External electrode

Claims (1)

A method of manufacturing a multilayer ceramic electronic component having an internal electrode layer and a dielectric layer having a thickness of less than 2 μm,
The dielectric layer is represented by a composition formula as a main component (BaO) m · TiO _2, the mole ratio m in the formula is contained barium titanate m = 0.990 to 1.035, titanate when converted the barium to _{[(BaO) 0.990~1.035 · TiO 2} ], to the _{[(BaO) 0.990~1.035 · TiO 2} ] 100 moles, as a sub-component,
Magnesium oxide in terms of MgO, 0.1-3 mol,
Rare earth element oxide, more than 0 mol 5 mol or less in terms of R ₂ O ₃ ,
At least one selected from barium oxide and calcium oxide in terms of BaO and CaO, BaO + CaO: 0.5 to 12 mol,
Silicon oxide, in terms of SiO _2, 0.5 to 12 mol,
Manganese oxide, more than 0 mol 0.5 mol or less in terms of MnO,
0 to 0.3 mol of vanadium oxide in terms of V ₂ O ₅ ,
It is composed of a dielectric ceramic composition containing 0 to 0.3 mol of molybdenum oxide in terms of MoO ₃ ,
Firing a laminate formed using a dielectric layer paste containing a dielectric material and an internal electrode layer paste containing an additive dielectric material,
The dielectric material in the dielectric layer paste includes a main component material and a subcomponent material,
Main ingredient material is represented by a composition formula (BaO) m · TiO _2, the mole ratio m in the formula is a barium titanate m = 0.990 to 1.035,
The dielectric material for addition in the internal electrode layer paste includes at least a main component material for addition,
The additive main component material is represented by the composition formula (BaO) _{m ′} · TiO ₂ , the molar ratio m ′ in the formula is 0.995 ≦ m ′ ≦ 1.035, and 4.019 to 4 A method for producing a multilayer ceramic electronic component, characterized by being barium titanate having a lattice constant of 0.046 mm or less and an OH group emission amount of 28 or more and 220 or less .

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