JP2005142222A - Stacked dielectric element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stacked dielectric element of high quality which is free from delamination, and to provide its manufacturing method. <P>SOLUTION: The manufacturing method manufactures a stacked dielectric element 1 in which a dielectric ceramic layer 12 and a base metal electrode layer 13 are laminated alternately, and is provided with an electrode printing process for applying paster material for base metal electrode to at least one surface of the ceramic green sheet; a crimping process for laminating the ceramic green sheets, sticking them by pressure, and producing lamination; a cleaning process for degreasing the lamination; an electrode reduce process for heating the lamination under circulation of controlled atmosphere, reducing the paste material for base metal electrode, and obtaining the base metal electrode layer; and a calcination process for calcinating the lamination. In the electrode reduce process, the paste material for base metal electrode is reduced in such a manner that the amount of survival of base metal oxide contained in the base metal electrode layer is at most 20 wt%, and the amount of material isolated from the ceramic material becomes at most 30 atomic% from a surface of base material electrode layer in at most 5000 Å. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer dielectric element such as a multilayer ceramic capacitor and a multilayer piezoelectric actuator, and a method for manufacturing the same.

Conventionally, a multilayer dielectric element formed by alternately laminating a dielectric ceramic layer made of a PZT material having various excellent dielectric properties and a base metal electrode layer made of a base metal such as copper has been widely used for capacitors and actuators. It's being used.
A method of manufacturing such a laminated dielectric element is usually performed in a plurality of steps as described below.

First, a green sheet made of a ceramic material such as PZT is prepared, and an electrode paste material made of a metal oxide is applied to the green sheet by screen printing or the like. Subsequently, the green sheets coated with the electrode paste material are laminated to produce a laminate, and the laminate is further degreased.
Next, by heating the degreased laminate in a heating furnace under reducing conditions, the metal oxide in the electrode paste material is reduced to form a conductive metal electrode layer (electrode reduction step). Thereafter, the multilayer body is fired to densify the ceramic material, and a final multilayer dielectric element is obtained (firing step).

  However, in the firing step, the electrode paste material and the ceramic material require conflicting atmospheric conditions. That is, for example, a ceramic material such as PZT is preferably an oxide because it is an oxide, whereas the paste material has a reducing atmosphere in order to maintain the conductivity obtained in the electrode reduction process. It is preferable to perform firing at.

  Therefore, when firing in an oxidizing atmosphere in order to sufficiently fire the ceramic material in the firing step, the metal electrode layer made of copper or the like previously reduced in the electrode reduction step is oxidized again and becomes conductive. May decrease. On the other hand, when firing in a reducing atmosphere, the ceramic material is reduced, and there is a problem in that the characteristics of the laminated body after firing are degraded.

  In order to solve such a problem, after reducing the conductive paste in an atmosphere containing hydrogen gas, in the subsequent firing step, the laminate is fired in an atmosphere in which the oxygen partial pressure is controlled within a specific range. There is a method to do (see Patent Document 1).

Further, the conductive paste was reduced at a temperature lower than the firing temperature, and in the subsequent firing step, a mixed gas of N ₂ —H ₂ —H ₂ O—O ₂ was used, and the O ₂ partial pressure was controlled within a specific range. A method for firing the laminate in an atmosphere is disclosed (see Patent Document 2).

  According to such a conventional method, it is possible to densify the ceramic material without substantially oxidizing the metal electrode made of copper or the like reduced in the electrode reduction step even in the firing step.

JP-A-5-82387 Japanese Patent Publication No. 7-34417

However, in the above electrode reduction step, the two methods of chemical equilibrium reduction and reaction kinetic reduction coexist, so the above conventional method is not sufficient.
For example, in the case of producing using a conductive paste containing Cu oxide and a ceramic material made of a PZT-based material, in the electrode reduction step, a chemical equilibrium reduction reaction of Cu oxide ( 2Cu _x O⇔2xCu + and O _2), the reduction reaction of reaction kinetic Cu oxides by hydrogen gas and _{(Cu x O + H 2 ⇒xCu} + H 2 O) coexist.

  According to the reaction kinetic reaction among the above two reactions, when the hydrogen gas concentration or amount is small, the Cu oxide is not reduced but remains in the conductive paste. On the other hand, when the amount is large, Cu oxide is reduced, but PZT in the ceramic material is also reduced, and Pb and the like in the composition are liberated.

As described above, when Cu oxide remains without being reduced, Cu ₂ O of the remaining Cu oxide remains slightly in the ceramic material such as PZT during the firing step. It reacts with PbO or the like to form a liquid phase eutectic substance, and this liquid phase diffuses into the ceramic material. As a result, the problem that the insulation resistance after baking falls will generate | occur | produce. Furthermore, since the portion where the liquid phase is generated is more likely to shrink than the surroundings, there is a problem that delamination occurs during firing.

On the other hand, when PZT is reduced and Pb in the composition is liberated, the liberated Pb and Cu produced by the reduction in the electrode reduction step are liquid at a temperature of 327 ° C. or more at their eutectic point. There is a risk of forming a phase eutectic material. Therefore, there is a possibility that the metal electrode is melted during the firing step in which the high temperature heat treatment is performed. In addition, as described above, the portion where the liquid phase is formed is more likely to shrink than the surroundings, and thus there is a problem that delamination occurs during the firing process.
The occurrence of such delamination deteriorates important characteristics of the laminated dielectric element such as Young's modulus and insulation resistance.

  The present invention has been made in view of such conventional problems, and is intended to provide a high-quality multilayer dielectric element and a method for manufacturing the same without delamination.

A first invention is a method of manufacturing a laminated dielectric element in which a dielectric ceramic layer containing lead in a composition and a base metal electrode layer made of a base metal are alternately laminated,
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide on at least one surface of a ceramic green sheet formed by forming a ceramic material made of a metal oxide containing lead oxide into a sheet; ,
A pressure bonding step in which a ceramic green sheet coated with the above base metal electrode paste material is laminated and pressure bonded to produce a laminate;
An electrode reduction step of heating the laminated body in a heating furnace under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
In the electrode reduction step, the amount of lead liberated from the ceramic material is less than 20% by weight of the base metal oxide contained in the base metal electrode layer and within 5000 mm from the surface of the base metal electrode layer. , 30 atomic% or less, the base metal electrode paste material is reduced. A method for producing a multilayer dielectric element according to claim 1.

  In the first invention, attention is paid to the fact that one of the causes of delamination generated during the firing step is the electrode reduction step performed before the firing step, and the base metal electrode paste material in the electrode reduction step. Is reduced under the specific conditions as described above.

  Specifically, in the electrode reduction step, the residual amount of the base metal oxide contained in the base metal electrode layer is 20 wt% or less and is released from the ceramic material within 5000 mm from the surface of the base metal electrode layer. The base metal electrode paste material is reduced so that the amount of lead is 30 atomic% or less.

  By reducing the residual amount of the base metal oxide in the electrode reduction step to 20 wt% or less, the remaining base metal oxide reacts with the metal oxide containing lead oxide in the ceramic material, so that the liquid phase coexists. Formation of a crystal substance can be prevented. For this reason, the liquid phase diffuses into the ceramic material, and it is difficult to reduce the insulation resistance after firing. Also, delamination can be prevented.

  Further, by suppressing the amount of lead released from the ceramic material within 5000 mm from the surface of the base metal electrode layer to a small amount of 30 atomic% or less, the lead released from the ceramic material and the base metal contained in the base metal electrode layer can be reduced. , It is possible to prevent a problem that the base metal electrode layer is melted by reacting during the firing step.

Here, the residual amount of the base metal oxide in the electrode reduction step is set to 20 wt% or less.
When the remaining amount of the base metal oxide exceeds 20 wt%, the remaining base metal oxide reacts with the metal oxide containing lead oxide contained in the ceramic material, and a liquid phase eutectic substance is formed. There is a risk of forming. As a result, the insulation resistance of the laminate after the firing process is lowered, and delamination may occur.

Further, the amount of lead released from the ceramic material within 5000 mm from the surface of the base metal electrode layer is set to 30 atomic% or less.
When the amount of lead liberated from the ceramic material within the above range exceeds 30 atomic%, the liberated lead may react with the base metal in the base metal electrode layer, and the base metal electrolytic layer may melt. Therefore, the conductivity of the base metal electrode layer is impaired and delamination may occur due to the formation of a liquid phase.

  Thus, according to the present invention, it is possible to provide a method for manufacturing a high-quality multilayer dielectric element without delamination.

According to a second aspect of the present invention, there is provided a method for manufacturing a multilayer dielectric element in which a dielectric ceramic layer containing lead in a composition and a base metal electrode layer made of a base metal are alternately stacked.
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide to at least one surface of a ceramic green sheet formed by forming a ceramic material made of a metal oxide containing lead oxide into a sheet; ,
A pressure bonding step in which a ceramic green sheet coated with the base metal electrode paste material is stacked and pressure bonded to produce a laminate,
An electrode reduction step of heating the laminate in a heating furnace under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
In the electrode reduction step, the remaining amount of the base metal oxide contained in the base metal electrode layer is M (wt%) (where the remaining amount M is a value determined by thin film X-ray diffraction method),
And the amount of lead liberated from the ceramic material within 5000 mm from the surface of the base metal electrode layer is N (atomic%) (however, the amount of lead N is within the range of 5000 mm from the surface of the base metal electrode layer). (Quantitatively determined by spectroscopy)
Between M (wt%) and N (atomic%),
The relationship N = C × M + D and 0 ≦ M <20 holds (where C and D are values independent of M and N, and −1.5 ≦ C <−1.0 and 30 ≦ D <, respectively). 36). A manufacturing method of a laminated dielectric element characterized in that it is in the range of 36).

  In the first invention, it is noted that one of the causes of delamination that occurs during the firing step is the electrode reduction step performed before the firing step, and the base metal electrode paste material in the electrode reduction step Is reduced under the specific conditions as described above.

Specifically, in the electrode reduction step, the residual amount N of the base metal oxide contained in the base metal electrode layer is less than 20 wt% and is free from the ceramic material within 5000 mm from the surface of the base metal electrode layer. The base metal electrode paste material is reduced so that the amount of lead M is equal to C × N + D. Here, C takes an appropriate value within the range of −1.5 ≦ C <−1.0, and D takes the range of 30 ≦ D <36.
Further, the residual amount N is a value determined by thin film X-ray diffraction, and the lead amount M is a value determined by X-ray photoelectron spectroscopy. As a measuring instrument used for the thin film X-ray diffraction method, XRD6100 manufactured by Shimadzu Corporation can be used. Moreover, the measuring instrument made from VG Systems Japan Co., Ltd. can be used as a measuring instrument used for X-ray photoelectron spectroscopy.

  By setting the residual amount of the base metal oxide in the electrode reduction step to less than 20 wt%, the remaining base metal oxide reacts with the metal oxide containing lead oxide in the ceramic material, so Formation of a crystal substance can be prevented. Therefore, this liquid phase is diffused in the ceramic material, and it is difficult for the insulation resistance after firing to decrease. Moreover, the occurrence of delamination can be prevented.

  In addition, the amount M of lead liberated from the ceramic material within 5000 mm from the surface of the base metal electrode layer is equal to C × N + D (atomic%). The base metal contained in can react during the firing step and melt the base metal electrode layer.

Here, the residual amount of the base metal oxide in the electrode reduction step is less than 20 wt%.
When the residual amount of the base metal oxide is 20 wt% or more, the residual base metal oxide reacts with the metal oxide containing lead oxide contained in the ceramic material, and a liquid phase eutectic substance. May be formed. As a result, the insulation resistance of the laminate after the firing step is reduced, and delamination may occur.

Further, the amount M of lead liberated from the ceramic material within 5000 mm from the surface of the base metal electrode layer is made equal to C × N + D (atomic%), and −1.5 ≦ C <−1.0, 30 ≦ D <36.
When the amount of lead liberated from the ceramic material within the above range is not equal to C × N + D (atomic%), the liberated lead reacts with the base metal in the base metal electrode layer, and the base metal electrolytic layer melts. There is a risk that. Therefore, the conductivity of the base metal electrode layer is impaired, and delamination may occur due to the formation of the liquid phase.

  Thus, according to the present invention, it is possible to provide a method for manufacturing a high-quality multilayer dielectric element without delamination.

According to a third aspect of the present invention, there is provided a method for manufacturing a multilayer dielectric element in which dielectric ceramic layers and base metal electrode layers made of a base metal are alternately stacked.
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide on at least one surface of a ceramic green sheet formed by forming a ceramic material into a sheet;
A pressure bonding step in which a ceramic green sheet coated with the base metal electrode paste material is stacked and pressure bonded to produce a laminate,
An electrode reduction step in which the laminate is heated under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
The atmosphere gas in the electrode reduction step contains a reducing gas for reducing the base metal electrode paste material and an oxidizing gas composed of oxygen or / and a gas forming oxygen,
The heating in the electrode reduction step is performed at a temperature near the eutectic point between the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet as a maximum holding temperature, and the maximum holding temperature. In the method of manufacturing a multilayer dielectric element, the reducing gas in is contained in the atmospheric gas in an amount of more than 0.2% by volume and less than 3% by volume.

  The most notable point in the present invention is that in the electrode reduction step, the temperature near the eutectic point of the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet is set as the maximum holding temperature. Heating is performed and the reducing gas at the maximum holding temperature is set so as to be contained in the atmospheric gas in an amount of more than 0.2% by volume and less than 3% by volume.

In the electrode reduction step, the laminate is heated, for example, at a constant rate of temperature increase under the circulation of the atmospheric gas. When a certain temperature (maximum holding temperature) is reached, this temperature is held and the base metal electrode paste material is reduced.
In the present invention, the maximum holding temperature is set in the vicinity of the eutectic point of the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet. And content in the atmospheric gas of the said reducing gas is prescribed | regulated to the said range.

By having these two requirements at the same time, the base metal in the base metal electrode paste material reacts with at least one metal in the ceramic green sheet, so that the liquid phase (eutectic substance) ) Is rarely formed. Therefore, occurrence of delamination can be prevented.
Further, by controlling the reducing gas within the above range, the base metal electrode paste material can be sufficiently reduced in the electrode reduction step, and on the other hand, the ceramic material can also be reduced. Can be prevented. Therefore, the eutectic material is hardly formed and the properties of the dielectric ceramic layer are hardly deteriorated. Therefore, a laminated dielectric element having excellent characteristics such as Young's modulus and insulation resistance can be manufactured.

Here, the reducing gas at the maximum holding temperature is contained in the atmospheric gas in an amount of more than 0.2% by volume and less than 3% by volume.
When the reducing gas is 0.2% by volume or less, the base metal electrode paste material is not sufficiently reduced, and there is a possibility that a conductive base metal electrode layer cannot be formed. Further, the base metal oxide remains in the base metal electrode paste material, and this base metal oxide may form a eutectic substance with the metal oxide in the ceramic material.

  On the other hand, in the case of 3% by volume or more, the metal oxide in the ceramic material is also reduced, which may impair the dielectric properties and piezoelectricity. Further, when the metal oxide in the ceramic material is reduced and the metal is liberated in this manner, the liberated metal and the metal in the base metal electrode layer are melted at a low temperature by a eutectic reaction, and the island is melted. There is a risk that the electrode will become a shaped electrode.

4th invention is the method of manufacturing the laminated dielectric element which laminated | stacked alternately the dielectric ceramic layer and the base metal electrode layer which consists of base metals,
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide on at least one surface of a ceramic green sheet formed by forming a ceramic material into a sheet;
A pressure bonding step in which a ceramic green sheet coated with the base metal electrode paste material is stacked and pressure bonded to produce a laminate,
An electrode reduction step in which the laminate is heated under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
The atmosphere gas in the electrode reduction step contains a reducing gas for reducing the base metal electrode paste material and an oxidizing gas composed of oxygen or / and a gas forming oxygen,
The heating in the electrode reduction step is performed at a temperature near the eutectic point between the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet as a maximum holding temperature, and the maximum holding temperature. In the method for manufacturing a multilayer dielectric element, the reducing gas in the atmospheric gas is circulated at a linear density greater than 0.0376 cm / min and less than 0.564 cm / min.

In the fourth aspect of the invention, the maximum holding temperature in the electrode reduction step is set to a temperature in the vicinity of the eutectic point, and the reducing gas in the atmospheric gas is greater than 0.0376 cm / min, It is set to circulate at a linear density lower than 564 cm / min.
By controlling to satisfy these two requirements at the same time, it is possible to sufficiently reduce the base metal electrode paste material in the electrode reduction step, while preventing the ceramic material from being reduced. can do. Therefore, the eutectic material is hardly formed and the properties of the dielectric ceramic layer are hardly deteriorated.
Therefore, it is possible to manufacture a laminated dielectric element having excellent characteristics such as Young's modulus and insulation resistance.

Here, the reducing gas in the atmospheric gas is circulated at a linear density of more than 0.0376 cm / min and less than 0.564 cm / min.
When the linear density is 0.0376 cm / min or less, the base metal electrode paste material is not sufficiently reduced in the electrode reduction step, and the base metal oxide may remain. Further, at this time, the remaining base metal oxide and the metal oxide contained in the ceramic material form a eutectic substance, which may reduce the piezoelectric characteristics of the dielectric ceramic layer.

  On the other hand, in the case of 0.564 cm / min or more, not only the base metal electrode paste material but also the metal oxide in the ceramic material is reduced in the electrode reduction step, and the characteristics of the dielectric ceramic layer are deteriorated. There is a fear. In addition, there is a possibility that the metal produced by reduction of the metal oxide in the ceramic material reacts with the base metal produced by reduction of the paste material for the base metal electrode to form a liquid-phase eutectic substance and cause delamination. is there.

  In the fourth invention, even if the laminate is relatively large, the internal base metal electrode paste material can be sufficiently reduced without depending on the size.

  That is, generally, the larger the size of the laminate, the more difficult it is to reduce the base metal electrode paste material inside the laminate. In the case of such a large laminate, if the base metal electrode paste material inside the laminate is sufficiently reduced, the outer peripheral portion of the laminate exposed to the atmosphere gas having good fluidity is more easily reduced. There is a possibility that the ceramic material in the outer peripheral portion is reduced.

  In general, the reaction amount when the atmospheric gas passes in the vicinity of the laminate is affected by the flow rate of the atmospheric gas. That is, when the atmospheric gas flow rate is high, the reaction of the entire system is delayed, and when the atmospheric gas flow rate is low, the reaction of the entire system becomes fast. In particular, for example, when the atmospheric gas flows from the lower part of the heating furnace in a heating furnace, a troposphere is formed when the flow rate of the atmospheric gas is increased, and a portion where the fluidity of the atmospheric gas is relatively lowered occurs. The size of the troposphere also depends on the flow rate of the atmospheric gas, and becomes relatively wide as the flow rate of the atmospheric gas increases.

  In the fourth aspect of the invention, the reducing gas is circulated with the linear density in the specific range. Therefore, even if it is a comparatively big laminated body, the paste material for base metal electrodes can fully be reduced, suppressing the reduction | restoration of the said ceramic layer.

  According to a fifth aspect of the present invention, there is provided a multilayer dielectric element manufactured by the manufacturing method according to the first to fourth aspects of the present invention.

The laminated dielectric element of the fifth invention is the first invention (invention 1), the second invention (invention 2), the third invention (invention 11), or the fourth invention (invention). Item 12) is produced by the manufacturing method.
Therefore, the multilayer dielectric element has almost no delamination between the dielectric ceramic layer and the base metal electrode layer, and has high Young's modulus and insulation resistance and high quality.

First, a preferred embodiment of the first invention (claim 1) will be described.
In the first invention, the ceramic material is preferably a PZT material.
In this case, it is possible to produce a multilayer dielectric element that can be used for a high-performance multilayer ceramic capacitor, a multilayer piezoelectric actuator, and the like by utilizing the excellent piezoelectric and dielectric properties of the PZT material.

Next, the atmosphere gas in the electrode reduction step preferably contains a reducing gas for reducing the base metal electrode paste material and an oxidizing gas composed of oxygen or / and a gas forming oxygen. ).
In this case, in the electrode reduction step, the reducing power of the reducing gas is moderately suppressed by the oxidizing gas, and the base metal electrode paste material can be sufficiently reduced. Reduction of the metal oxide can be prevented.

  In general, ceramic materials are less likely to be reduced than base metal electrode pastes. Therefore, as described above, the base metal electrode paste material is preferentially used in the electrode reduction process by controlling the reducing gas reducing power by using two gases, a reducing gas and an oxidizing gas, as an atmospheric gas. It can be reduced.

Moreover, as said reducing gas, hydrogen, carbon monoxide, ammonia, hydrazine etc. can be used, for example.
As the oxidizing gas, for example, oxygen, water, or the like can be used.

Next, it is preferable that the reducing gas is hydrogen and the oxidizing gas is oxygen.
In this case, the effect of containing both the reducing gas and the oxidizing gas can be obtained more effectively.

Next, in the electrode reduction step, heating is started at a rate of temperature increase of 200 ° C./h or less, followed by holding at a maximum holding temperature of 300 ° C. to 400 ° C. for 0.5 to 15 hours, and then furnace cooling. The partial pressure of oxygen in the atmospheric gas from when the laminated body is taken out from the heating furnace at a temperature of 90 ° C. or less and when the laminated body is taken out from the heating furnace after the start of heating is 1 It is preferable to set it to * 10 ^{<-2> 3.9} to 1 * 10 ^{< -22 >} atm.

In this case, oxygen as the oxidizing gas and hydrogen as the reducing gas reach a parallel atmosphere represented by the following formula (1) in the heating furnace.
H ₂ + 1 / 2O ₂ ⇔H ₂ O (1)
Therefore, a stable oxygen partial pressure can be realized. Therefore, in the electrode reduction step, the residual amount of the base metal oxide contained in the base metal electrode layer is 20 wt% or less, and the lead released from the ceramic material is within 5000 mm from the surface of the base metal electrode layer. It becomes easy to make the amount 30 atomic% or less.

Further, as can be seen from the above formula (1), water vapor is generated in the heating furnace. Therefore, for example, when using lead-containing ceramic materials such as PZT-based materials, it is possible to suppress excessive metallization of lead and the like existing as oxides in the ceramic materials. Can do.
In addition, the said furnace cooling is hold | maintaining a processing material in a furnace even after a heating is stopped, and cooling the processing material more slowly than natural cooling.

When the partial pressure of oxygen in the atmosphere gas exceeds 1 × 10 ⁻²² atm, the oxygen partial pressure in the atmosphere is high, so that the base metal oxide cannot be sufficiently reduced, and unreduced base metal oxidation is performed during firing. Objects may diffuse into the dielectric ceramic layer.
On the other hand, in the case of less than 1 × 10 ^−23.9 atm, the base metal oxide in the base metal electrode paste material is reduced, and at the same time, the metal oxide containing lead in the ceramic material is also reduced. Lead may be liberated. This liberated lead may react with a base metal such as copper in the base metal electrode layer to melt the base metal electrode layer.

  Moreover, when the said temperature increase rate exceeds 200 degrees C / h, there exists a possibility that the said laminated body may be received by a thermal shock during the said electrode reduction process.

When the maximum holding temperature is less than 300 ° C., the base metal electrode paste material cannot be sufficiently reduced, and a large amount of base metal oxide may remain.
On the other hand, when it exceeds 400 ° C., lead liberated from the ceramic material and the metal of the base metal electrode layer may react to melt the base metal electrode layer.

Further, when the holding time at the maximum holding temperature is less than 0.5 hour, the base metal electrode paste material may not be sufficiently reduced.
On the other hand, if it exceeds 15 hours, the ceramic material may be reduced during the electrode reduction step, and the piezoelectric material and dielectric properties of the ceramic material may be impaired.

  In addition, when the temperature at which the laminate is taken out exceeds 90 ° C., the base metal electrode layer reduced in the electrode reduction step may be oxidized by oxygen in the atmosphere at the exposed portion in contact with the atmosphere. There is.

Next, the oxygen flow rate f _O (ml / min) and the hydrogen flow rate f _H (ml / min) in the electrode reduction step are the total flow rate F (ml / min) of each gas constituting the atmospheric gas. min)), the relationship of oxygen flow rate f _O = A × hydrogen flow rate f _H / total flow rate FB (where 20 ≦ A ≦ 24, 12 ≦ B ≦ 16, 8 ≦ A−B ≦ 8.22) (Claim 6).
In this case, in the electrode reduction step, the ceramic material can be prevented from being excessively reduced, while the base metal electrode paste material can be sufficiently reduced.

  That is, in this case, in the electrode reduction step, the residual amount of the base metal oxide contained in the base metal electrode layer is 20 wt% or less and is free from the ceramic material within 5000 mm from the surface of the base metal electrode layer. It becomes easy to make the amount of lead to be 30 atomic% or less.

When the oxygen flow rate f _O exceeds the above range and oxygen becomes excessive, the reduction of the base metal electrode paste becomes insufficient, and the non-metal oxide remains. And in the case of the said baking process, there exists a possibility that the remaining nonmetallic oxide may diffuse in ceramic material. On the other hand, when the oxygen flow rate f _O is smaller than the above range and oxygen becomes insufficient, even the metal oxide in the ceramic material may be reduced.

Next, assuming that the molar flow rate of water produced by the reaction of hydrogen and oxygen when the electrode reduction step is maintained at the maximum temperature is W, and the molar flow rate of the remaining surplus hydrogen is H, both values are It is preferable to be within the following range (claim 7).
0.0012 ≦ H ≦ 0.0018 (H: mol / min)
0.0002 ≦ W ≦ 0.001 (W: mol / min)
Thereby, the laminated body using the dielectric material containing lead oxide can suppress the phenomenon that lead is precipitated by being reduced by hydrogen, and the base metal oxide in the base metal electrode layer can be reduced.
If H is less than 0.0012, there is a possibility that the time required for reducing the base metal oxide in the base metal electrode layer may be increased. If H is greater than 0.0018, the dielectric material may be used. However, the amount of lead that is reduced by hydrogen and precipitates lead to a problem that the electrode layer cannot be formed by reacting with the base metal electrode layer during firing.

Next, when the maximum temperature is maintained in the electrode reduction step, the integral value h of the hydrogen molar flow rate during the retention time is preferably within the following range (claim 8).
29000 ≦ h ≦ 31000 (h: mol / min)
As a result, the base metal electrode layer of the laminate using a dielectric material containing lead oxide does not react with the base metal electrode layer during firing, and the base metal oxide in the base metal electrode layer is being fired with a minimum remaining amount. In addition, the amount of base metal oxide that reacts with the dielectric material can be minimized.
If h is less than 29000, there is a possibility that an unreduced base metal oxide remains in an amount of 20 wt% or more in the base metal electrode layer.
When h is greater than 31000, the amount of lead that is reduced from the dielectric material by hydrogen and deposits lead from the dielectric material exceeds 5000 atomic% from the surface of the base metal electrode layer, and the amount of lead exceeds 30 atomic%. There is a possibility that the electrode layer cannot be formed by reaction.

Next, in the electrode printing step, the base metal electrode paste material is preferably applied in a thickness of 2 to 14 μm.
In this case, in the electrode reduction step, the base metal electrode paste material can be sufficiently reduced, and a base metal electrode layer having sufficient conductivity can be produced. In this case, when the electrode reduction process is performed, the ceramic material is hardly reduced, while the base metal electrode paste material can be sufficiently reduced.

When the thickness of the base metal electrode paste material is less than 2 μm, the base metal electrode layer may be easily broken during the electrode reduction step or the firing step.
On the other hand, if it exceeds 14 μm, the base metal electrode paste material becomes difficult to be reduced in the electrode reduction step, the remaining base metal oxide forms a liquid phase with the metal oxide in the ceramic material, and delamination occurs. May occur.

Next, the electrode reduction step and the firing step can be performed simultaneously by one heating (claim 10).
In this case, the manufacturing process is simplified, and the laminated dielectric element can be easily manufactured.

Next, a preferred embodiment of the third or fourth invention will be described.
In the third or fourth invention, as the reducing gas, for example, hydrogen, carbon monoxide, ammonia, hydrazine, or the like can be used.
Further, as the gas for forming oxygen, for example, oxygen, water, or the like can be used.

Moreover, the said electrode reduction process and the said baking process can be performed simultaneously by one heating (Claim 13).
In this case, the manufacturing process of the multilayer dielectric element is simplified, and the multilayer dielectric element can be easily manufactured.

In the third invention, as described above, the atmosphere gas contains the oxidizing gas and the reducing gas, and the concentration of the reducing gas is controlled within the above range. In the fourth aspect of the invention, the linear density of the reducing gas is controlled within the above range.
Therefore, in the third and fourth inventions, even if the electrode reduction step and the firing step are performed simultaneously by one heating, the base metal electrode paste material is given priority without substantially reducing the ceramic material. Reduction can be achieved. This is because ceramic materials are generally less likely to be reduced than base metal electrode paste materials.

Next, the atmospheric gas further contains an inert gas, and the total amount of the reducing gas, the oxidizing gas, and the inert gas is preferably 99% by volume or more of the atmospheric gas. (Claim 14).
In this case, impurity gases other than the reducing gas, oxidizing gas, and inert gas can be suppressed to less than 1% by volume, and the problem of an increase in oxidizing gas and reducing gas contained in the impurity gas can be prevented. it can. That is, for example, when the oxidizing gas or the reducing gas is included in the impurity gas, it is possible to prevent the total amount of the oxidizing gas or the reducing gas from being additively increased.
Examples of the inert gas include Ar, Ne, N ₂ , and He.

Next, it is preferable that the reducing gas is hydrogen and the oxidizing gas is oxygen (claim 15).
In this case, the effects of the above-described invention can be obtained more effectively.

  Next, the maximum holding temperature T (° C.) in the electrode reduction step is tm (° C.) as the eutectic point of the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet. It is preferable that tm-16 <T <tm + 14 is satisfied (claim 16).

When the maximum holding temperature T (° C.) is tm−16 (° C.) or less, the base metal electrode paste material cannot be sufficiently reduced, and a base metal electrode layer having sufficient conductivity is formed. You may not be able to.
On the other hand, when the maximum holding temperature T (° C.) is equal to or higher than tm + 14 (° C.), a part of the ceramic material is reduced and released from the ceramic material in the electrode reduction step, and the base metal electrode There is a possibility that the base metal generated by reducing the paste material for the reaction reacts and dissolves the base metal electrode layer.

The ceramic material preferably contains lead as a component element (claim 17).
In this case, a dielectric ceramic layer containing lead is formed, and the excellent dielectric properties of the dielectric ceramic layer containing lead can be utilized.
Such a dielectric ceramic layer is preferably a PZT material.
In this case, it is possible to produce a multilayer dielectric element that can be used for a high-performance multilayer ceramic capacitor, a multilayer piezoelectric actuator, and the like by utilizing the excellent piezoelectric and dielectric properties of the PZT material.

Next, in all of the first to fourth inventions, the base metal is preferably copper.
In this case, the base metal electrode layer having excellent conductivity can be produced at a low cost, and the effects of the invention described above can be made more remarkable.

Next, in all of the first to fourth inventions, it is preferable to perform a degreasing step for removing organic substances contained in the laminate after the crimping step (claim 19).
Thereby, an organic substance can be removed and electrode reduction and reduction | restoration baking can be enabled.

(Example 1)
Next, a method for manufacturing a laminated dielectric element according to an embodiment of the first invention will be described with reference to FIGS.
In this example, as shown in FIG. 1, a multilayer dielectric element 1 in which dielectric ceramic layers 12 and base metal electrode layers 13 made of a base metal are alternately stacked is manufactured.
And the manufacturing method of this example has an electrode printing process, a crimping | compression-bonding process, a degreasing process, an electrode reduction process, and a baking process so that it may mention later.

In the electrode printing step, a base metal electrode paste material containing a base metal oxide is formed on at least one surface of a ceramic green sheet formed by forming a ceramic material made of a metal oxide containing lead oxide into a sheet shape. It is a process of applying.
Moreover, the said crimping | compression-bonding process is a process of producing the laminated body by laminating | stacking and crimping | bonding the ceramic green sheet with which the said paste material for base metal electrodes was apply | coated.
Moreover, a degreasing process is a process of degreasing the said laminated body.

The electrode reduction step is a step of heating the laminated body in a heating furnace under a flow of atmospheric gas to reduce the base metal electrode paste material to form a base metal electrode layer.
Moreover, the said baking process is a process of baking the said laminated body.

  In the electrode reduction step of the present example, the residual amount of the base metal oxide contained in the base metal electrode layer is 20 wt% or less and is free from the ceramic material within 5000 mm from the surface of the base metal electrode layer. The base metal electrode paste material is reduced so that the amount of the obtained metal is 30 atomic% or less.

Hereinafter, the manufacturing method of this example will be described in detail.
First, a ceramic material is produced as follows.
Auxiliary agent in which lead oxide and tungsten oxide were weighed 83.5 mol% and 16.5 mol%, respectively, dry-mixed, and then calcined at 500 ° C. for 2 hours to react part of lead oxide and tungsten oxide. Oxide powder (chemical formula: Pb _0.835 W _0.165 O _1.33 ) was produced. Next, the auxiliary oxide powder was atomized by a medium stirring mill and dried to increase the reactivity.

On the other hand, PbO, SrCO ₃ , ZrO ₂ , TiO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ , Mn ₂ O ₃ metal oxides were mixed, these were dry-mixed, and then fired at 890 ° C. for 7 hours. As a result, a dielectric calcined powder was produced.

  Next, 5.5 L of water is added to 4.7 kg of the dielectric calcined powder, and D134 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersant is 5 wt% with respect to the dielectric calcined powder. And mixed for 1 hour to prepare a slurry for pulverizing the dielectric calcined powder.

  The slurry for pulverization was pulverized for 8 hours by a medium stirring mill so that the median diameter was 0.2 μm or less. Further, this pulverizing slurry was dried at 220 ° C. with a spray dryer to obtain a pulverized dielectric calcined powder. Since the dispersant remains in the pulverized portion, the pulverized portion was further heat treated at 650 ° C. for 5 hours to degrease the dispersant and obtain a dielectric calcined powder.

  Next, 3.5 g of the auxiliary oxide prepared in advance as described above is added to 700 g of the dielectric calcined powder to produce a raw material powder. Further, 16 wt% ethanol as a solvent is added to the raw material powder, 16 wt% of 2-butanol, 16 wt% of isoamyl acetate, 0.6 wt% of sorbitan trioleate as a dispersant, 5 wt% of BBP (benzylbutyl phthalate, manufactured by Wako Pure Chemical Industries, Ltd.) as a plasticizer, 7.5 wt% of PVB (polyvinyl butyral Denki Kagaku Kogyo Co., Ltd.) as a binder was added and mixed with a ball mill for 72 hours to obtain a dielectric ceramic material slurry.

  Next, the ceramic material slurry was formed into a sheet with a blade interval of 125 μm by the doctor blade method. Then, after drying at 80 degreeC, it cut | disconnected to 100 mm x 150 mm with the sheet cutter, and was set as the ceramic green sheet.

Next, the electrode printing process and the pressure bonding process will be described with reference to FIGS.
First, a base metal electrode paste material is prepared as follows.
In preparing the base metal electrode paste material, first, the solid content of the base metal electrode paste material is prepared. As the composition of the solid content, CuO powder (specific surface area of 10-15 m ² / g, manufactured by Kojundo Chemical Co., Ltd.) as the base metal oxide is 28 wt%, Cu powder (average particle size of 0.5 μm or less, Mitsubishi Materials Corporation) Manufactured) is 56.6 wt%, and the co-powder having the same composition as the dielectric calcined powder and having a particle diameter of 20 μm or less is 15 wt%.

  Next, 5.5 to 15 wt% of cellulose as a binder, 0.7 to 2 wt% of higher fatty acid as a dispersant, and butyl carbitol as a solvent as the remaining components, the total of these being 22 wt% Thus, it added with respect to the said solid content 78 wt%, and mixed with the centrifugal force stirring deaerator, and produced the paste material for base metal electrodes.

  Next, as shown in FIG. 2, the base metal electrode paste material 23 is applied to the plurality of ceramic green sheets 22. At this time, the base metal electrode paste material 23 was applied to one surface of the ceramic green sheet 22 by screen printing. The printing thickness was 6 μm. In the figure, an example of the green sheet after printing is shown.

Subsequently, as shown in FIG. 3, the ceramic green sheets 22 on which the base metal electrode paste material 23 is printed are laminated. At this time, the base metal electrode paste material 23 alternately reached the left and right side surfaces. In this way, the ceramic green sheets 22 were sequentially laminated to obtain a unit 25 in which a total of 26 ceramic green sheets 22 were laminated as shown in FIG. Further, ten ceramic green sheets were laminated in the same manner, and ten units 25 formed by laminating 26 ceramic green sheets 22 were produced.
One of the 10 units 25 is prepared by laminating the ceramic green sheets 22 with one ceramic green sheet on which the base metal electrode paste material is not printed. It is a laminate of ceramic green sheets that are not printed.

  The ten units 25 were each fixed to a crimping jig and thermocompression bonded at 110 ° C. for 1 minute at 16 MPa. Each unit 25 subjected to thermocompression bonding was cut into a size of 9 mm in length and 9.5 mm in width with a sheet cutter, and then flattened by pressing in the laminating direction at a normal pressure with a pressing force of 7.8 MPa.

Further, as shown in FIG. 5, the above ten units 25 are stacked and thermocompression bonded with a laminating apparatus at 125 ° C. for 10 minutes with a pressure of 1.6 kN (16.5 MPa), and the length is 10.2 mm, A laminate 27 having a height of 9.5 mm and a height of 20 mm was produced. In addition, when stacking the ten units, the base metal electrode paste material 23 was stacked so as not to be exposed on the surfaces of the uppermost end and the lowermost end.
Subsequently, the laminate 27 was put in a gas circulation degreasing furnace, and the laminate 27 was heated at a temperature setting as shown in FIG. 6 to perform degreasing. In FIG. 6, the horizontal axis represents the elapsed time (h), and the vertical axis represents the temperature (° C.) in the vicinity of the laminate, and shows the temperature pattern P1.

Next, the base metal electrode paste material 23 of the laminate 27 is reduced (electrode reduction step).
This electrode reduction process is performed by a heating furnace 3 as shown in FIG.
As shown in FIG. 7, the heating furnace 3 includes a furnace chamber 30 in which the laminated body 27 is placed and heated, an in-furnace oxygen partial pressure sensor 315 inserted into the furnace chamber 30, and the sensor 315. A mass flow controller 311, 312, 313 for introducing Ar—H ₂ (or Ar—CO), CO ₂ , O ₂ into the furnace chamber 30, respectively. It has a flow path 31 provided with an electromagnetic valve 314 for appropriately switching the flow path from the mass flow controllers 311, 312, 313 to the furnace chamber 30.

Further, an out-of-furnace oxygen partial pressure sensor 317 and an out-of-furnace oxygen partial pressure meter 318 for obtaining an output value from the sensor 317 are installed in the middle of the exhaust meter 310 from the furnace chamber 30 to the outside of the furnace.
Then, the oxygen partial pressure in the furnace chamber 30 is controlled by the outside oxygen partial pressure sensor 317 and the partial pressure gauge 318, the in-furnace oxygen partial pressure sensor 315 and the partial pressure gauge 316.

The out-of-furnace oxygen partial pressure sensor 317 is a zirconia O ₂ sensor, and the sensor is constantly heated to 600 ° C. or higher by a built-in heater, and the oxygen partial pressure in the gas introduced into the out-of-furnace oxygen partial pressure sensor 317 is completely Measure in the temperature range.
On the other hand, the in-furnace oxygen partial pressure sensor 315 is a zirconia O ₂ sensor, but does not include a heater, and the oxygen content in the furnace chamber 30 when the temperature of the furnace chamber of the firing furnace 3 is heated to about 400 to 500 ° C. or higher. Pressure can be measured. Therefore, in this firing furnace, the in-furnace oxygen partial pressure sensor 317 was used when the in-furnace temperature was out of the measurement temperature range of the in-furnace oxygen partial pressure sensor 315.

  In the electrode reduction step, first, the laminate 27 is placed in the furnace chamber 30, and heating is started at a temperature increase rate of 180 ° C./h (the vicinity of the laminate is 155 ° C./h). The maximum holding temperature in the vicinity was set to 330 ° C. and heated for 14 hours. And when the temperature was lowered at the furnace cooling rate and the temperature in the furnace chamber 30 was cooled to 90 ° C., the laminate was taken out. The state of temperature control at this time is shown in FIG. In FIG. 8, the horizontal axis represents the time from the start of heating, and the vertical axis represents the temperature in the vicinity of the laminate, showing a temperature pattern P2.

In addition, during the heating, Ar—H ₂ , which is a mixed gas of Ar and hydrogen, and O ₂ were introduced as an atmospheric gas in order to adjust the oxygen partial pressure. The concentration of hydrogen gas in Ar—H ₂ gas is 0.99 (%). The flow rate of Ar—H ₂ at the time of introducing the atmospheric gas is 5000 ml / min, and the flow rate of O ₂ is 8.0 ml / min. At this time, the oxygen partial pressure gauge 318 outside the furnace maintained the vicinity of 1 × 10 ^−23.7 atm.

In determining the oxygen flow rate, an equation of oxygen flow rate f _O = A × hydrogen flow rate f _H / total flow rate FB (where 20 ≦ A ≦ 24, 12 ≦ B ≦ 16) was applied. In this example, the oxygen flow rate f _o was determined with the values of A and B in the above formula being A = 22.22 and B = 14.
In this manner, CuO contained in the base metal electrode paste material was reduced to Cu to form a base metal electrode layer.

Next, the laminate was fired using the same heating furnace 3 as the electrode reduction step (firing step). Hereinafter, this firing step will be described with reference to FIG.
In the firing step, the laminated body 27 after the electrode reduction step is placed in the furnace chamber 30 of the heating furnace 3, heating is started at a temperature rising rate of 300 ° C./h, and a maximum holding temperature 970 is achieved. Heated at 0 ° C. for 2 hours. At this time, as the atmospheric gas, CO ₂ (base gas), Ar—CO (CO concentration is 10% by volume) composed of Ar as an inert gas and CO as a reducing gas, and the oxygen partial pressure are adjusted. O ₂ (oxidizing gas) was introduced into the furnace chamber 30 at a constant flow rate. The CO ₂ and Ar—CO flow rates at this time were 5000 ml / min and 150 ml / min, respectively, and the O ₂ flow rate was in the range of _{2 to 8} ml / min.

The oxygen partial pressure was controlled by the outside oxygen partial pressure sensor 317 and the partial pressure gauge 318 from room temperature to around 600 ° C., and the indicated value of the outside oxygen partial pressure sensor 317 was set to 10 ^−12.9 to 10 ^−16.0 atm. .
On the other hand, from 600 ° C. or higher, the oxygen partial pressure was controlled by switching to the in-furnace oxygen partial pressure sensor 315 and the partial pressure gauge 316. The indicated value of the in-furnace oxygen partial pressure sensor 315 at the time of switching was 10 ⁻¹⁰ to 10 ⁻¹⁴ atm. From the switching to the maximum holding temperature, the oxygen partial pressure was increased linearly, and at the maximum holding temperature, the oxygen partial pressure was maintained in the range of 10 ^−6.0 to 10 ^−8.0 atm to control the atmosphere.

The state of this control is shown in FIG. 9 as the relationship between time, temperature, and oxygen partial pressure (values indicated by the oxygen partial pressure sensor inside the furnace and the oxygen partial pressure sensor outside the furnace). In FIG. 9, the horizontal axis represents time, the left vertical axis represents temperature, and the right vertical axis represents the value of x when the oxygen partial pressure is represented by 10 ^× atm. The target oxygen partial pressure S2, the out-furnace oxygen partial pressure S3, and the temperature pattern P3 are shown. Note that 10 ^x atm is equal to 1.013 × 10 ⁵ × 10 ^x Pa.
Thus, the multilayer body 27 was fired to obtain the multilayer dielectric element 1 according to this example as shown in FIG. This was designated as Sample E1.

  As shown in FIG. 1, the multilayer dielectric element 1 of this example is formed by alternately laminating dielectric ceramic layers 12 and base metal electrode layers 13 made of a base metal. 240 dielectric ceramic layers 12 are laminated in the multilayer dielectric element 1, and the thickness per layer is 90 μm.

Further, in this example, the laminated dielectric element was manufactured by changing the control conditions of the atmospheric gas in the electrode reduction step from that when the sample E1 was manufactured. These are designated as Samples E2 to E4 and Samples C1 to C3.
And when preparing each of these samples E1-E4 and samples C1-C3, the sample after completion | finish of an electrode reduction process was prepared separately, respectively, and these were made into sample E1a-E2a and sample C1a-C3a.

The control conditions of the atmospheric gas of each sample are as shown in Table 1 described later. Among the control conditions of the atmospheric gas, the oxygen flow rate for the samples E1 to E4 is oxygen flow rate f _O = A × hydrogen flow rate f _H / total flow rate FB (where 20 ≦ A ≦ 24, 12 ≦ B ≦ 16) Was used to determine. At this time, the values of A and B are A = 22.22, B = 14 for the sample E2, A = 20.22, B = 12, for the sample E3, and A = for the sample E4. 24.22, B = 16 was adopted.
Samples C1 to C3 were prepared at an oxygen flow rate outside the range of the above formula.

  Next, regarding the samples E1a to E4a and samples C1a to C3a obtained immediately after the electrode reduction step, the amount of Cu oxide remaining in the base metal electrode layer was determined by a thin film X-ray diffraction method. Further, the concentration of lead released from the ceramic green sheet to the base metal electrode layer was measured.

First, the sample E1a was disassembled so as to be peeled off at the interface between the base metal electrode layer and the ceramic green sheet, and one base metal electrode layer was transferred onto a double-sided tape. The transferred base metal electrode layer was measured by a thin film X-ray diffraction method using an X-ray diffractometer (XRD6100 manufactured by Shimadzu Corporation).
As a result, as shown in FIGS. 16 and 17, X-ray diffraction spectra of components contained in the base metal electrode layer were obtained. From this spectrum, the components contained in the base metal electrode layer are rarely composed of a dielectric ceramic material that is a co-powder, Cu that is a conductive component reduced in the electrode reduction process, and Cu ₂ O that is an unreduced Cu oxide. It was found that CuO was detected.
From this result, the remaining amount of Cu oxide was determined from the corundum ratio, and the reduced amount of Cu (wt%) was determined from the remaining amount of Cu oxide.
16 is a diagram showing a spectrum, and FIG. 17 is a diagram showing a peak position in FIG.

  As the quantification means at this time, there are a simple quantification means based on the corundum ratio as described above, and a quantification means excellent in quantification accuracy for examining the concentration of the test sample. In this example, since the Cu concentration contained in the base metal electrode layer is a high concentration of at least 50 wt% or more, the quantitative accuracy is not a problem. Therefore, quantification by corundum ratio was employed as described above.

Next, the sample E1a used in the X-ray diffraction was processed into an 8 mm square to prepare a sample for X-ray photoelectron spectroscopy analysis (XPS: VG Systems Japan, Inc., X-ray beam diameter φ2 mm). Then, the atomic ratio of Cu and Pb contained in 5000 mm from the outermost surface of the exposed surface of the base metal electrode layer was measured. And the result concerning X-ray photoelectron spectroscopic analysis was described in the diagram concerning FIG. Here, the vertical axis represents frequency (cps) and the horizontal axis represents energy (eV).
Further, the range 970 to 920 eV and the range 150 to 130 eV were scanned more precisely to measure the atomic ratio of Cu and Pb, and the results are shown in FIGS. 19 and 20, respectively.
From this detection result, the ratio of the Pb detection peak area to the Cu detection peak area was determined, and the Pb generation amount (atomic%) was calculated. In addition, since the said base metal electrode layer and the ceramic green sheet are contacting, there exists a possibility that interference may arise in an analysis result. In order to avoid this, the surface of the base metal electrode layer was previously etched with Ar for about 30 seconds.
Furthermore, the same operation as described above was performed on E2a to E4a and C1a to C3a.

And the result of Pb production | generation amount and copper reduction amount of each sample E1a-E4a and sample C1a-C3a was plotted in FIG.
In FIG. 10, the horizontal axis represents the amount of Cu reduction (wt%), and the vertical axis represents the amount of Pb produced (atomic%).

  As can be seen from FIG. 10, in Samples E1a to E4a, CuO was reduced by 85 wt% or more, indicating that the base metal electrode paste material was sufficiently reduced. Further, the amount of lead liberated from the ceramic green sheet at this time was 30 atomic% or less.

On the other hand, in the samples C1a and C2a, the base metal electrode paste material is sufficiently reduced, while the ceramic green sheet is also reduced, and lead is liberated in excess of 30 atomic%.
In Sample C3a, the amount of lead produced is suppressed to a low level, but the base metal electrode paste material is not sufficiently reduced, and the amount of Cu reduction is less than 80 wt%.

Next, among the samples E1 to E4 and samples C1 to C3 obtained by baking the samples E1a to E4a and the samples C1a to C3a by the baking step, the sample E1 and the sample C
In order to clarify the Cu distribution inside the sample 3, the Cu distributions of the sample E1 and the sample C3 were examined by EPMA (Electron probe microanalyzer) which is a kind of X-ray microanalyzer.
The results are shown in FIG. 11 (Sample E1) and FIG. 12 (Sample C3). In FIG. 15, FIG. 23, and FIG. 24, which will be described later, the distribution of Cu or O atoms represents the magnitude of the distribution amount with five types of hatching patterns. The type of hatching pattern is shown in the lower right square of each figure, and the top hatching pattern indicates the portion with the largest distribution amount, and the distribution amount decreases in order from the top.

As known from FIGS. 11 and 12, in the sample E1, the Cu distribution is only in the base metal electrode layer 13, whereas in the sample C3, Cu is diffused and distributed in the dielectric ceramic layer 12.
Further, in the sample C3, as shown in FIG. 13, a large delamination 9 was generated in the multilayer dielectric element 1. In the delamination 9, the base metal electrode layer 13 and the dielectric ceramic layer 12 are separated at the interface to form an opening 95.

Further, with respect to the sample C3, a portion where the delamination 9 was generated was observed with a scanning electron microscope (SEM). The result is shown in FIG. The middle figure of FIG. 14 is the result of observing the lower side of the opening 95 that occurs when delamination occurs. In the figure, the portion above the boundary line obliquely shown in the lower right direction is an opening generated by delamination, and the lower portion is the dielectric ceramic layer 12. The right side is a result of observing the upper side of the opening 95. In addition, the figure on the left side of FIG. 14 is a result of observing a normal part where delamination 9 does not occur for comparison.
Further, FIG. 15 shows the state of Cu distribution in the same part as observed by the SEM.

As shown in FIGS. 14 and 15, in the portion where the delamination of the sample C3 occurred, the ball-shaped Cu was present on the surface of the dielectric ceramic layer 12 on the opening 95 side.
Note that the oblique solid lines shown in the middle and right diagrams of FIG. 15 indicate the approximate position of the boundary between the dielectric ceramic layer 12 and the opening 95.

Next, the capacitances and insulation resistances of E1 to E4 and C1 to C3 were measured.
(Capacitance)
The capacitance was measured using an impedance analyzer at a measurement frequency of 1 kHz with a temperature condition of room temperature. The results are shown in Table 1.

(Insulation resistance)
The insulation resistance was measured by applying a voltage of 150 V at room temperature and measuring the resistance 2 minutes after application using an insulation resistance meter. The results are shown in Table 1.

As is known from Table 1, all of the samples E1 to E4 of this example had a high capacitance exceeding 1300 nF, and the insulation resistance was excellent exceeding 550 MΩ per dielectric ceramic layer.
On the other hand, Sample C1 to Sample C3 had a small capacitance of less than 900 μF. Samples C3 and 4 had very low insulation resistance, both of which were 13 MΩ or less.

(Example 2)
In this example, a laminated dielectric element similar to that of Example 1 was produced by changing the thickness of the base metal electrode paste material applied in the electrode printing step and the atmospheric gas control conditions in the electrode reduction step. Capacitance, insulation resistance and yield were measured.

First, 26 types of laminated dielectric elements were fabricated in the same manner as in Example 1 except that the above various conditions were changed. Specifically, the thickness (printing thickness) for applying the base metal electrode paste material in the electrode printing step, the hydrogen gas concentration in Ar-H ₂ in the electrode reduction step, the flow rate of oxygen as the oxidizing gas, the maximum holding temperature A plurality of stacked dielectric elements were manufactured by changing the holding time as shown in Table 2 to be described later. At this time, the obtained multilayer dielectric elements were designated as Sample E5 to Sample E18 and Sample C5 to Sample C16.

In addition, the yield under the conditions for producing Samples E5 to E18 and Samples C5 to C16 was examined.
For the yield, 40 similar samples were produced under the same conditions as the respective samples, and the yield was calculated assuming that a delamination of these samples was a defective product.
The results are shown in Table 2.

Next, the capacitance and insulation resistance of Sample E5 to Sample E18 and Sample C5 to Sample C16 were measured. These measurement methods are the same as those in Example 1. The results are shown in Table 2.
For comparison, the capacitance, insulation resistance, and yield of the sample E1 obtained in Example 1 were measured, and the results are shown in Table 2.

As is known from Table 2, Samples E5 to E18 had the same capacitance and insulation resistance as Sample E1, and the yield was excellent at 80% or more.
On the other hand, in Sample C5 to Sample C16, the capacitance and insulation resistance deteriorated.
In particular, as in sample C14 to sample C16, those with a printing thickness exceeding 16 μm caused frequent delamination and poor yield. This is presumably because the base metal electrode paste material is less likely to be reduced in the electrode reduction step, and the residual Cu oxide diffuses into the dielectric ceramic layer.

  Further, although not shown in Table 2, when the printing thickness is less than 2 μm, the base metal electrode layer 13 is interrupted after firing as shown in FIG. This is presumably because the electrode was melted by lead released from the ceramic material.

Although not shown in Table 2, in the samples E5 to E18, the residual amount of the base metal oxide contained in the base metal electrode layer 13 is 20 wt% or less, and from the surface of the base metal electrode layer 13 The amount of lead liberated from the ceramic material within 5000 kg was 30 atomic% or less.
On the other hand, the samples C5 to C16 were released from the ceramic material in which the residual amount of the base metal oxide contained in the base metal electrode layer 13 exceeded 20 wt%, or within 5000 mm from the surface of the base metal electrode layer 13. The amount of lead exceeded 30 atomic%.

(Example 3)
Next, a method for manufacturing a multilayer dielectric element according to an embodiment of the second invention will be described.
In this example, as shown in FIG. 22, a laminated dielectric element 6 in which dielectric ceramic layers 62 and base metal electrode layers 63 made of a base metal are alternately laminated is manufactured.
And the manufacturing method of this example has an electrode printing process, a crimping | compression-bonding process, a degreasing process, an electrode reduction process, and a baking process so that it may mention later.

The electrode printing step is a step of applying a base metal electrode paste material containing a base metal oxide to at least one surface of a ceramic green sheet formed by forming a ceramic material made of a metal oxide into a sheet shape. .
Moreover, the said crimping | compression-bonding process is a process of producing the laminated body by laminating | stacking and crimping | bonding the ceramic green sheet with which the said paste material for base metal electrodes was apply | coated.
Moreover, a degreasing process is a process of degreasing the said laminated body.

The electrode reduction step is a step of heating the laminated body in a heating furnace under a flow of atmospheric gas to reduce the base metal electrode paste material to form a base metal electrode layer.
Moreover, the said baking process is a process of baking the said laminated body.

And in the electrode reduction process of this example, the atmosphere gas in the electrode reduction process contains a reducing gas for reducing the paste material for base metal electrode and an oxidizing gas comprising oxygen and / or a gas for forming oxygen. To do.
The heating in the electrode reduction step is performed at a temperature near the eutectic point between the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet as a maximum holding temperature, and the maximum The reducing gas at the holding temperature is contained by 0.2 to 0.3% by volume in the atmospheric gas.

Hereinafter, the manufacturing method of this example will be described in detail.
First, a base metal electrode paste material is prepared as follows.
A substantially spherical Cu powder having an average particle diameter of 0.5 μm was pressed to prepare a plate-like Cu powder and a substantially spherical CuO powder having an average particle diameter of 1 to 2 μm.
Further, a co-material made of a material obtained by reducing the Pb amount by 2 atomic% from the same material as the ceramic material of Example 1 was prepared.

Next, 18.3 wt% of ethyl cellulose as a resin material, 79.3 wt% of butyl carbitol as a solvent, and 0.7 wt% of a higher fatty acid as a dispersing material are mixed to form a base material for a base metal electrode paste material It was.
To this base material, CuO powder (average particle diameter of 1 to 2 μm, approximately spherical) prepared in advance as described above, plate-like Cu powder (average particle diameter of 0.5 μm, approximately spherical), and co-material are prepared. It added in the ratio shown in the following Table 3, and knead | mixed, and produced the paste material for base metal electrodes.

  Next, a slurry of a ceramic material having the same composition as in Example 1 was prepared in the same manner as in Example 1. Using this ceramic material slurry, it was molded into a sheet by the same doctor blade method as in Example 1 to produce a ceramic green sheet.

Subsequently, as in Example 1, the base metal electrode paste material is printed on a ceramic green sheet. Further, the ceramic green sheet on which the base metal electrode paste material was printed was laminated and pressure-bonded so that the base metal paste material alternately reached the left and right side surfaces in the same manner as in Example 1, and cut into predetermined dimensions. In this example, in order to shorten the degreasing time in the degreasing step, a 2 mm laminated body (80 μm / layer) in which the number of laminated layers was suppressed to 25 was produced.
The laminate was degreased in the same manner as in Example 1.

Next, the electrode reduction process is performed.
The electrode reduction process of this example was performed using the heating furnace 3 similar to Example 1 as shown in FIG. In this example, the ceramic green sheet contains lead in the composition, and the base metal electrode paste material contains copper. Therefore, the maximum temperature is around 326 ° C., which is the eutectic point of lead and copper. The holding temperature was set and heated for 12 hours.

In addition, an atmospheric gas was introduced into the furnace chamber 30 of the heating furnace 3 during the heating. Ar-H ₂ and O ₂ were used as the atmosphere gas to be introduced. The concentration of hydrogen gas in Ar—H ₂ is 1%. The flow rate of Ar—H ₂ when introducing the atmospheric gas was 5000 ml / min, and the flow rate of O ₂ was 5 to 10 ml / min. By this electrode reduction process, the base metal electrode paste material printed on the ceramic green sheet is reduced to form a base metal electrode layer.
The oxygen partial pressure in the electrode reduction step was set to 10 ^−23.8 atm at the maximum holding temperature.

Next, the laminated body after the electrode reduction step was baked using the same heating furnace 3 as in the electrode reduction step.
In this example, the laminate was fired at a firing temperature of 950 ° C. for 4 hours under a flow of atmospheric gas. At this time, Ar—H ₂ (reducing gas) and O ₂ (oxidizing gas) were used as the atmospheric gas as in the electrode reduction step. In this example, the dielectric ceramic layer is not reduced. Adjusted to atmosphere. The oxygen partial pressure during firing was set to be about 10 ⁻⁶ at a temperature of 950 ° C.
In this way, as shown in FIG. 22, a laminated dielectric element 6 was produced in which dielectric ceramic layers 62 and base metal electrode layers 63 made of a base metal were alternately laminated. This was designated as Sample X1.

In this example, for comparison, in the above electrode reduction step, Ar—H ₂ containing 1% hydrogen gas, O ₂ , and N ₂ are used as the atmospheric gas, and the others are the same as in the sample X1. Thus, a comparative laminated dielectric element (sample Y1) was produced. In preparing the sample Y1, the electrode reduction step was performed with an Ar—H ₂ flow rate of 1000 ml / min, an O ₂ flow rate of 5 to 10 ml / min, and an N ₂ flow rate of 4000 ml / min.

Next, the sample X1 and the sample Y1 were cut along a plane perpendicular to each dielectric ceramic layer, and the distribution of copper and oxygen atoms in each cross section was analyzed by EPMA and compared.
The results are shown in FIG. 23 (sample X1) and FIG. 24 (sample Y1), respectively.

As is known from FIG. 23, in the sample X1, almost no O is distributed in the base metal electrode layer 63 in which Cu is distributed. That is, it can be seen that the base metal electrode paste material was sufficiently reduced in the electrode reduction step. Further, no delamination occurred in the sample X1.
On the other hand, in the sample Y1, as is known from FIG. 24, O is also distributed in the base metal electrode layer 63 in which Cu is distributed. That is, it can be seen that Sample Y1 has an extremely low reduction degree of the base metal electrode paste material compared to Sample X1.
Thus, according to the manufacturing method of this example, there is no delamination and a high-quality multilayer dielectric element can be manufactured.

Example 4
In this example, the temperature and the atmospheric gas conditions in the electrode reduction process of Example 3 are changed, and a multilayer dielectric element similar to that of Example 3 is produced.
First, six 2 mm laminates were produced in the same manner as in Example 3, and degreasing was performed in the same manner as in Example 3.
Subsequently, an electrode reduction step and a firing step were performed on the six degreased laminates in the same manner as in Example 3 to produce a multilayer dielectric element.

  In the above electrode reduction step of this example, the maximum holding temperature was set to 330 ° C. and heated for 12 hours. At the time of heating, the atmospheric gas was circulated in the same manner as in Example 3. In this example, the total flow rate of the atmosphere gas at this time is set to 5005 to 5010 ml / min, and each of the above six laminates is heated by changing the ratio of the hydrogen gas in the atmosphere gas. In the same manner, firing was performed to obtain six laminated dielectric elements. These were designated as Samples X2 to X5, Sample Y2, and Sample Y3, respectively. Note that the ratio of hydrogen gas when the samples X2 to X5, the sample Y2, and the sample Y3 are respectively produced is as shown in Table 4 described later.

The atmosphere gas is composed of Ar ₂ H ₂ gas and oxygen gas as the atmosphere gas for the sample X 2, sample X 5, and sample Y 2 manufactured under the atmospheric condition that the H ₂ gas ratio is 1% or more. Using. Then, the flow rate of Ar-H ₂ gas in the atmospheric gas, or allowed to flow by adjusting the flow rate 5000 ml / min the ratio of the Ar gas and H ₂ gas Ar-H ₂ gas, H ₂ in the atmospheric gas The atmospheric condition was set so that the gas ratio was 1% or more. In this atmosphere gas, oxygen gas was circulated in an amount of 5 to 10 ml / min, and the flow rate of all the atmosphere gases was set to 5005 to 5010 ml / min.

On the other hand, for the sample X3, the sample X4, and the sample Y1 manufactured under the atmospheric condition that the H ₂ gas ratio is less than 1%, Ar—H ₂ gas, oxygen gas, and N ₂ gas were used as the atmospheric gas. . Then adjust the Ar-H ₂ gas and N ₂ gas in the atmospheric gas, the ratio of the H ₂ gas in the atmospheric gas is set to atmospheric conditions such that less than 1%. Further, the total flow rate of these Ar—H ₂ gas and N ₂ gas is set to 5000 ml / min, oxygen gas is circulated at 5 to 10 ml / min, and the flow rate of the total atmosphere gas is set to 5005 to 5010 ml / min. It was set to min.

  For the samples X2 to X5, the sample Y1, and the sample Y2 produced as described above, the residual ratio of Cu oxide in the base metal electrode layer and the eutectic material formation ratio in the dielectric ceramic layer were examined.

  The residual rate of Cu oxide indicates the residual rate of Cu oxide contained in the base metal electrode layer after the electrode reduction step. When the residual ratio of Cu oxide is large, the conductivity of the base metal electrode layer is lowered, and there is a possibility that it cannot be used as a dielectric element.

Further, during the electrode reduction step and the firing step, Cu, CuO or Cu ₂ O contained in the base metal electrode layer reacts with Pb, PbO or PbO ₂ released from the dielectric ceramic layer, and Cu and Pb The eutectic material Cu ₆ PbO _{8 and the} like may be formed. If the eutectic material formation rate is high, the eutectic material penetrates into the dielectric ceramic layer. Since this eutectic substance is not a piezoelectric material in many cases, the piezoelectric characteristics are deteriorated. It can also be a cause of occurrence during driving.
Hereinafter, a method for measuring the residual ratio of Cu oxide and the formation ratio of eutectic substance will be described.

(Residual ratio of Cu oxide)
The laminated dielectric element (samples X2 to X5, sample Y1 and sample Y2) after firing is peeled off at the interface between the dielectric ceramic layer and the base metal electrode layer, the base metal electrode layer film is attached to a tape, and an X-ray diffractometer ( It is measured by Shimadzu Corporation XRD-6100). The measurement was performed by simple quantitative calculation (calculated for the identified compound having a corundum ratio), and the result was obtained as the ratio of the Cu amount and the Cu oxide amount.
Thus, the residual rate of Cu oxide was measured, and the results are shown in Table 4.

(Eutectic material formation rate)
Similarly to the measurement of the Cu oxide residual ratio, after the base metal electrode layer film is attached with a tape, the dielectric ceramic layer side is measured using the X-ray diffractometer. The measurement was performed by the above simple quantitative calculation, and the result was obtained as the ratio of the Cu ₆ PbO ₈ amount and the Pb oxide amount.
Thus, the formation rate of eutectic substances (Cu ₆ PbO _{8 and the} like) was measured, and the results are shown in Table 4.
In Table 4, the Cu oxide residual rate and the eutectic material formation rate are both expressed as the ratio of the number of atoms (atomic%).

As known from Table 4, with respect to Sample X2 to Sample X5, the Cu oxide residual rate and the eutectic substance formation rate were very low.
On the other hand, Sample Y1 has a very high Cu oxide formation rate in the base metal electrode layer, and a high eutectic material formation rate of Pb and Cu. Further, in the sample Y2, the eutectic substance formation rate was large.
These results will be discussed below.

In this example, the sample X2 to the sample X5, the sample Y1, and the sample Y2 are each produced by changing the ratio of H ₂ gas in the atmospheric gas in the electrode reduction process.
Here, the sample Y1 was produced under the condition of a low H ₂ gas ratio of 0.2%. When such a low hydrogen gas concentration is used, the base metal electrode paste material is not sufficiently reduced in the electrode reduction step, and Cu oxide remains as shown in Table 4. Further, the remaining Cu oxide such as CuO forms a eutectic substance with PbO in the dielectric ceramic layer in a firing step performed after the electrode reduction step. As a result, as shown in Table 4, the eutectic material formation rate is also increased.

Sample Y2 was produced under the condition of a high H ₂ gas ratio of 3.0%. When such a high hydrogen gas concentration is used, not only the base metal electrode paste material but also the ceramic green sheet is reduced in the electrode reduction step, and Pb is liberated. Since this liberated Pb forms a eutectic material with Cu in the base metal electrode layer, as shown in Table 4, the eutectic material formation rate becomes high.
As described above, the formation of the eutectic substance is considered to occur in the electrode reduction step regardless of whether the reduction conditions are stricter or weaker. As can be seen from Table 4, in the electrode reduction step, the ratio of H ₂ gas in the atmospheric gas is preferably set to be larger than 0.2% and smaller than 3.0%. .

Further, as shown in FIG. 7, the heating furnace 3 used in the above electrode reduction process of this example has a furnace chamber 30 having a cylindrical shape, and a cross-sectional shape of a cylinder having a perpendicular to the traveling direction of the atmospheric gas has a diameter of 184 mm. It is a substantially circular shape. Thus, the H ₂ gas ratio in the atmospheric gas can be converted into as shown in Table 4 above, the linear density of the H ₂ gas (H ₂ gas flow rate ÷ passage to medium (the cross-sectional area of the furnace chamber)) . However, in Table 4, the flow rate of oxygen contained in a very small amount in the atmospheric gas is not considered.
When considering the results in Table 4 in terms of linear density of the H ₂ gas, in the electrode reduction step, the linear density of the H ₂ gas in the atmospheric gas is greater than 0.0376cm / min, 0.564cm / It can be seen that it is preferable to set a range smaller than min.

(Example 5)
In this example, the range of the preferable ratio of the hydrogen gas in the atmospheric gas examined in Example 4 is further examined.
First, in the same manner as in Example 3 and Example 4, two 2 mm laminates were produced and further degreased.
Next, an electrode reduction process and a firing process are performed on the two degreased laminates in the same manner as in Examples 3 and 4 to produce a multilayer dielectric element.

  In the electrode reduction step of this example, the atmospheric gas was circulated in the same manner as in Example 3 above during heating. At this time, in this example, each of the two laminated bodies was heated by changing the linear density of hydrogen gas in the atmospheric gas as follows.

In the first electrode stacking step, Ar-H ₂ gas containing 1% hydrogen gas as the atmosphere gas is 1000 ml / min, and oxygen gas for adjusting the oxygen partial pressure is 1 to 4 ml / min. Heating was performed at a maximum holding temperature of 320 ° C. for 8 hours under conditions of circulation at min (the flow rate of all atmospheric gases was 1001 to 1004 ml / min). Since the heating furnace at this time is the same as that in Example 4, the linear density of hydrogen gas in the atmospheric gas is 0.0376 cm / min. Then, firing was performed in the same manner as in Examples 3 and 4 to obtain a multilayer dielectric element. This was designated as Sample X6.

Further, the other laminated body has a condition in which Ar—H ₂ gas containing 2% hydrogen gas as an atmospheric gas is circulated at 7500 ml / min and oxygen gas at 8 to 15 / min (the flow rate of all atmospheric gases is 7508-7515 ml / min) and the maximum holding temperature was 330 ° C. for 12 hours. Since the heating furnace at this time is the same as that in Example 4, the linear density of hydrogen gas in the atmospheric gas is 0.564 cm / min. Thereafter, firing and multilayer dielectric elements were obtained in the same manner as in Examples 3 and 4. This was designated as Sample X7.

Next, with respect to Sample X8 and Sample X9, similarly to Example 4, the Cu oxide remaining rate in the base metal electrode layer and the eutectic material formation rate of Pb and Cu were measured.
The results are shown in Table 4 above.
The method for calculating the linear density of H ₂ gas in Table 4 was the same as in Example 4 above, and was calculated without considering the flow rate of a trace amount of oxygen gas contained in the atmospheric gas.

As can be seen from Table 4, Sample X6 and Sample X7 in this example both had 0% Cu oxide and a relatively small amount of eutectic material.
In Example 4 above, the preferable range of the linear density of H ₂ gas was 0.0376 cm / min, and the upper limit was 0.564 cm / min. Sample X6 and Sample X7 of this example have this range. It was made with a deviating linear density H ₂ gas. Nevertheless, the formation rates of the Cu oxide and eutectic material of Sample X6 and Sample X7 are kept low as shown in Table 4 because the H ₂ ratio in the atmospheric gas is 0, as described above. This is because it is set in a range of more than 2 and less than 3.0.

  Thus, according to this example, in the electrode reduction step, the content of hydrogen gas as the reducing gas in the atmospheric gas can be set to a range of more than 0.2% and less than 3.0%. It turns out to be important.

(Example 6)
In this example, the preferred range of the linear density of the hydrogen gas is further examined.
First, in the same manner as in Example 5 above, two 2 mm laminates were prepared and further degreased.
Next, an electrode reduction step and a firing step are performed on the two degreased laminates in the same manner as in Example 5 to produce a multilayer dielectric element.

  In the electrode reduction process of the present example, during the heating, each of the two laminated bodies was heated by changing the ratio of hydrogen gas in the atmospheric gas as follows.

The first laminate is a mixture in which N ₂ gas is mixed with Ar—H ₂ gas containing 1% hydrogen gas as an atmospheric gas so that the hydrogen gas ratio is 0.2% in the electrode reduction step. The gas was circulated at 10,000 ml / min and oxygen gas for adjusting the oxygen partial pressure at 10-20 ml / min (the flow rate of all atmosphere gases was 10010-10020 ml / min), and the maximum holding temperature was 332 ° C. Heated for 16 hours. As the heating furnace at this time, since the same furnace as in Example 4 is used, the linear density of hydrogen gas in the atmospheric gas is 0.0752 cm / min. Then, firing was performed in the same manner as in Examples 3 and 4 to obtain a multilayer dielectric element. This was designated as Sample X8.

Further, the other laminated body has a condition of flowing Ar—H ₂ gas containing 3% hydrogen gas as an atmosphere gas at 2000 ml / min and oxygen gas at 2 to 5 / min (flow rate of all atmosphere gases). Was heated at a maximum holding temperature of 330 ° C. for 12 hours. Since the heating furnace at this time is the same as that in Example 4, the linear density of hydrogen gas in the atmospheric gas is 0.226 cm / min. Thereafter, firing was performed in the same manner as in Examples 3 and 4 to obtain a multilayer dielectric element. This was designated as Sample X9.

Next, with respect to the sample X6 and the sample X7, the Cu oxide remaining rate in the base metal electrode layer and the eutectic material formation rate of Pb and Cu were measured in the same manner as in Example 4.
The results are shown in Table 4 above.
The method for calculating the linear density of H ₂ gas in Table 4 was the same as in Example 4 above, and was calculated without considering the flow rate of a trace amount of oxygen gas contained in the atmospheric gas.

  As can be seen from Table 4, Sample X8 and Sample X9 of this example were very small with Cu oxide formation rates of 1% and 0%, respectively, and the formation of eutectic material was relatively small.

In Example 4 above, a range of more than 0.2% and less than 3% was set as a preferable range of the H ₂ gas ratio in the atmospheric gas, but this range is set for Sample X8 and Sample X9 of this example. It was produced at a deviating H ₂ gas ratio. Nevertheless, the formation rates of the Cu oxide and eutectic material of Sample X8 and Sample X9 are kept low as shown in Table 4 because the linear density of H ₂ gas in the atmospheric gas is as described above. This is because it is set in a range of more than 0.0376 cm / min and less than 0.564 cm / min.

Thus, according to this example, in the electrode reduction step, the linear density of hydrogen gas as the reducing gas in the atmospheric gas is set to a range greater than 0.0376 cm / min and less than 0.564 cm / min. It turns out that is important.
And from the results of Example 5 and Example 6, in the electrode reduction step, the ratio of hydrogen gas in the atmospheric gas is set to a range exceeding 0.2% and less than 3%, or in the atmospheric gas. It can be seen that it is important to set the linear density of hydrogen gas in a range higher than 0.0376 cm / min and lower than 0.564 cm / min.

(Example 7)
In this example, the heating temperature in the electrode reduction step is examined.
First, in this example, a laminated dielectric element was produced by the same production method and conditions as those of Sample X9 in Example 6 except that the maximum holding temperature in the electrode reduction step was 310 ° C. and the heating time was 12 hours. did. This was designated as Sample Y3.
In addition, a similar multilayer dielectric element was manufactured under the condition that only the maximum holding temperature in the electrode reduction process was different from that of the sample Y3. This was designated as Sample Y4. Note that. In sample Y4, the maximum holding temperature was 340 ° C.

Next, for the samples Y3 and Y4, as in Examples 4 to 6, the Cu oxide remaining rate in the base metal electrode layer and the eutectic material formation rate of Pb and Cu were measured.
As a result, in the sample Y3, almost 100% of Cu oxide remained in the base metal electrode layer.
Further, when the sample Y4 was visually observed, the base metal electrode layer had already disappeared after the electrode reduction step, and only the dielectric ceramic layer was laminated.

  Thus, in the electrode reduction step, it is preferable that the temperature near the eutectic point of the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet is set as the maximum holding temperature. In particular, when a PZT-based material is used as the ceramic material and copper is used as the base metal electrode layer, the maximum holding temperature is 310 ° C. lower than 326 ° C., which is the eutectic point of Pb and Cu, and the lower limit. The upper limit can be 340 ° C., which is 14 ° C. higher.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory perspective view illustrating an entire laminated dielectric element according to a first embodiment. Explanatory drawing which shows the state which printed the paste material for base metal electrodes on the ceramic green sheet concerning Example 1. FIG. Explanatory drawing which shows a mode that the ceramic green sheet concerning the said crimping | compression-bonding process concerning Example 1 is laminated | stacked. FIG. 3 is an explanatory diagram showing a unit of the ceramic green sheet according to the first embodiment. Explanatory drawing which shows the laminated body after the said crimping | compression-bonding process concerning Example 1. FIG. Explanatory drawing which shows the temperature setting conditions of the said degreasing process concerning Example 1. FIG. Explanatory drawing which shows the structure of the said heating furnace concerning Example 1. FIG. Explanatory drawing which shows the mode of the temperature control in the said electrode reduction process concerning Example 1. FIG. Explanatory drawing which shows the mode of control of the temperature and oxygen partial pressure in the said baking process concerning Example 1. FIG. Explanatory drawing which shows the result of Cu generation amount of each sample Ea1-Ea4 and sample Ca1-Ca4 concerning Example 1, and a copper reduction amount. Explanatory drawing which shows the mode of Cu distribution in the sample E1 concerning Example 1. FIG. Explanatory drawing which shows the mode of Cu distribution in the sample C3 concerning Example 1. FIG. Explanatory drawing which shows the mode of the delamination which generate | occur | produced in the sample C3 concerning Example 1. FIG. The figure (left) which shows a mode when a normal part is observed when the sample C3 concerning Example 1 is observed with a scanning microscope, The mode when the lower side of the opening of a delamination is observed Explanatory drawing (middle) shown and explanatory drawing (right) which shows a mode when the upper side of the opening part of delamination is observed. Explanatory drawing which shows the mode of Cu distribution in the part same as the part observed with the scanning microscope shown in FIG. 14 concerning Example 1. FIG. The diagram which shows the X-ray-diffraction spectrum of the component concerning Example 1 contained in a base metal electrode layer. Explanatory drawing which shows the peak position and peak intensity | strength of each component in FIG. 16 concerning Example 1. FIG. FIG. 3 is a diagram showing measurement results in X-ray photoelectron spectroscopy analysis according to Example 1; The enlarged view of the range 970-920 in FIG. 18 concerning Example 1. FIG. The enlarged view of the ranges 150-130 in FIG. 18 concerning Example 1. FIG. FIG. 6 is an explanatory diagram showing a state in which the base metal electrode layer is broken in the multilayer dielectric element according to Example 2. FIG. 6 is an explanatory view showing the entire laminated dielectric element according to Example 3; Explanatory drawing which shows the distribution state of copper and an oxygen atom in the sample X1 concerning Example 3. FIG. Explanatory drawing which shows the distribution state of copper and an oxygen atom in the sample Y1 concerning Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminated type dielectric element 12 Dielectric ceramic layer 13 Base metal electrode layer

Claims (20)

In a method of manufacturing a laminated dielectric element in which a dielectric ceramic layer containing lead in a composition and a base metal electrode layer made of a base metal are alternately laminated,
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide on at least one surface of a ceramic green sheet formed by forming a ceramic material made of a metal oxide containing lead oxide into a sheet; ,
A pressure bonding step in which a ceramic green sheet coated with the above base metal electrode paste material is laminated and pressure bonded to produce a laminate;
An electrode reduction step of heating the laminated body in a heating furnace under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
In the electrode reduction step, the amount of lead liberated from the ceramic material is less than 20% by weight of the base metal oxide contained in the base metal electrode layer and within 5000 mm from the surface of the base metal electrode layer. , 30 atomic% or less of the base metal electrode paste material is reduced. In the method of manufacturing a laminated dielectric element in which a dielectric ceramic layer containing lead in the composition and a base metal electrode layer made of a base metal are alternately laminated,
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide to at least one surface of a ceramic green sheet formed by forming a ceramic material made of a metal oxide containing lead oxide into a sheet; ,
A pressure bonding step in which a ceramic green sheet coated with the base metal electrode paste material is stacked and pressure bonded to produce a laminate,
An electrode reduction step of heating the laminate in a heating furnace under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
In the electrode reduction step, the remaining amount of the base metal oxide contained in the base metal electrode layer is M (wt%) (where the remaining amount M is a value determined by thin film X-ray diffraction method),
And the amount of lead liberated from the ceramic material within 5000 mm from the surface of the base metal electrode layer is N (atomic%) (however, the amount of lead N is within the range of 5000 mm from the surface of the base metal electrode layer). (Quantitatively determined by spectroscopy)
Between M (wt%) and N (atomic%),
The relationship N = C × M + D and 0 ≦ M <20 holds (where C and D are values independent of M and N, and −1.5 ≦ C <−1.0 and 30 ≦ D <, respectively). A range of 36.) A method of manufacturing a laminated dielectric element, wherein:   3. The atmosphere gas in the electrode reduction step according to claim 1, wherein the atmosphere gas contains a reducing gas for reducing the base metal electrode paste material and an oxidizing gas comprising oxygen or / and a gas forming oxygen. A method for manufacturing a laminated dielectric element.   4. The method of manufacturing a multilayer dielectric element according to claim 3, wherein the reducing gas is hydrogen and the oxidizing gas is oxygen. In Claim 4, in the said electrode reduction process, a heating is started at a temperature increase rate of 200 degrees C / h or less, and it hold | maintains at the maximum holding temperature of 300 to 400 degreeC for 0.5 to 15 hours after that, and a furnace The partial pressure of oxygen in the atmosphere gas from cooling to taking out the laminated body from the heating furnace at a temperature of 90 ° C. or less and starting the heating to taking out the laminated body from the heating furnace ^Is 1 × 10 ^−23.9 to 1 × 10 ⁻²² atm. According to claim 4 or 5, and the oxygen flow rate f _O (ml / min) and hydrogen flow rate f _H (ml / min) in the electrode reduction step, the total amount of the flow rate of the gas constituting the ambient gas total flow rate F (ml / min), oxygen flow rate f _O = A × hydrogen flow rate f _H / total flow rate FB (where 20 ≦ A ≦ 24, 12 ≦ B ≦ 16, 8 ≦ A−B ≦ 8. 22) A method for manufacturing a laminated dielectric element, characterized by having the relationship 22). In claim 6, when maintaining the maximum temperature in the electrode reduction step, if the molar flow rate of water produced by the reaction of hydrogen and oxygen is W, and the molar flow rate of the surplus hydrogen remaining is H, A method for producing a laminated dielectric element, characterized in that the value is within the following range.
0.0012 ≦ H ≦ 0.0018 (H: mol / min)
0.0002 ≦ W ≦ 0.001 (W: mol / min) 8. The multilayer dielectric element according to claim 6, wherein the integrated value h of the hydrogen molar flow rate during the holding time is within the following range when the electrode reduction step is held at the maximum temperature. Method.
29000 ≦ h ≦ 31000 (h: mol / min)   9. The method for manufacturing a multilayer dielectric element according to claim 1, wherein, in the electrode printing step, the base metal electrode paste material is applied in a thickness of 2 to 14 [mu] m.   The method for manufacturing a multilayer dielectric element according to claim 1, wherein the electrode reduction step and the firing step are performed simultaneously by one heating. In a method of manufacturing a laminated dielectric element in which a dielectric ceramic layer and a base metal electrode layer made of a base metal are alternately laminated,
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide on at least one surface of a ceramic green sheet formed by forming a ceramic material into a sheet;
A pressure bonding step in which a ceramic green sheet coated with the base metal electrode paste material is stacked and pressure bonded to produce a laminate,
An electrode reduction step in which the laminate is heated under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
The atmosphere gas in the electrode reduction step contains a reducing gas for reducing the base metal electrode paste material and an oxidizing gas composed of oxygen or / and a gas forming oxygen,
The heating in the electrode reduction step is performed at a temperature near the eutectic point of the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet as a maximum holding temperature, and the maximum holding temperature. The method for producing a multilayer dielectric element according to claim 1, wherein the reducing gas is contained in the atmospheric gas in an amount of more than 0.2% by volume and less than 3% by volume. In a method of manufacturing a laminated dielectric element in which a dielectric ceramic layer and a base metal electrode layer made of a base metal are alternately laminated,
An electrode printing step of applying a base metal electrode paste material containing a base metal oxide on at least one surface of a ceramic green sheet formed by forming a ceramic material into a sheet;
A pressure bonding step in which a ceramic green sheet coated with the base metal electrode paste material is stacked and pressure bonded to produce a laminate,
An electrode reduction step in which the laminate is heated under a flow of atmospheric gas to reduce the base metal electrode paste material to a base metal electrode layer;
A firing step of firing the laminate,
The atmosphere gas in the electrode reduction step contains a reducing gas for reducing the base metal electrode paste material and an oxidizing gas composed of oxygen or / and a gas forming oxygen,
The heating in the electrode reduction step is performed at a temperature near the eutectic point of the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet as a maximum holding temperature, and the maximum holding temperature. Wherein the reducing gas in the atmospheric gas is circulated at a linear density greater than 0.0376 cm / min and less than 0.564 cm / min.   13. The method for manufacturing a laminated dielectric element according to claim 11, wherein the electrode reduction step and the firing step are performed simultaneously by one heating.   14. The atmosphere gas according to claim 11, wherein the atmospheric gas further contains an inert gas, and a total amount of the reducing gas, the oxidizing gas, and the inert gas is equal to that of the atmospheric gas. A method for producing a laminated dielectric element, characterized by being 99% by volume or more.   The method of manufacturing a multilayer dielectric element according to claim 11, wherein the reducing gas is hydrogen, and the oxidizing gas is oxygen.   16. The maximum holding temperature T (° C.) in the electrode reduction step according to any one of claims 11 to 15, wherein the base metal in the base metal electrode paste material and at least one metal in the ceramic green sheet are the same. A manufacturing method of a laminated dielectric element, wherein a relationship of tm-16 <T <tm + 14 is satisfied when a crystal point is tm (° C.).   The method of manufacturing a multilayer dielectric element according to any one of claims 11 to 16, wherein the ceramic material contains lead as a component element.   The method for manufacturing a multilayer dielectric element according to claim 1, wherein the base metal is copper.   The method for manufacturing a multilayer dielectric element according to any one of claims 1 to 18, wherein a degreasing step for removing organic substances contained in the multilayer body is performed after the crimping step. A multilayer dielectric element manufactured by the manufacturing method according to claim 1.

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