JP2016163022A - Method of manufacturing capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a capacitor capable of ensuring a high electric capacitance with low dielectric loss.SOLUTION: A method of manufacturing a capacitor 1 including a solid electrolyte body 3 mainly composed of a solid electrolyte having lithium ion conductivity, and a pair of internal electrodes 7 consisting of a first internal electrode 7a formed in the solid electrolyte body 3 and a second internal electrode 7b disposed oppositely to the first internal electrode 7a via the solid electrolyte body 3, has a preparation step of preparing a capacitor formation body 1a including the solid electrolyte body 3 and the pair of internal electrodes 7, and a first voltage application step of applying a voltage of 2.5 V or more between the pair of internal electrodes 7 of the capacitor formation body 1a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a capacitor (capacitor) that stores and discharges electric charges, and more particularly, to a method for manufacturing a capacitor using a solid electrolyte having lithium ion conductivity.

  Conventionally, a capacitor using an electrolyte material is known as a capacitor using an electrolyte material. However, in recent years, various solid capacitors having a pair of electrodes provided on the surface of a solid electrolyte have been disclosed. ing.

  As this type of solid capacitor (solid electrolyte capacitor), for example, the following Patent Document 1 discloses the basic structure and characteristics of an electric double layer capacitor using a solid electrolyte between electrodes.

Patent Document 2 below discloses an advantage of improving the electric capacity when the thickness of the solid electrolyte is reduced in the solid electrolyte capacitor.
Furthermore, in Patent Document 3 below, in a decoupling capacitor (solid electrolyte capacitor) using a dielectric layer containing a Li ion conductive compound, the frequency characteristics are improved by making the thickness of the solid electrolyte thinner than a predetermined thickness. Advantages that can be disclosed are disclosed.

  In Patent Document 4 below, a capacitor having a high leakage voltage, a low dielectric loss tangent (tan δ), and a high withstand voltage is manufactured by disposing a titanate compound layer having titanium dioxide and a perovskite crystal between a pair of electrodes. It is disclosed that it can be done.

JP 2008-130844 A International Publication No. 2013/111804 JP 2013-225534 A International Publication No. 2008/090985

However, the above-described prior art has the following problems, and improvements are desired.
Although not described in detail in the prior art described above, in the case of a capacitor in which a solid electrolyte is disposed between electrodes, the relaxation frequency of the grain boundary of the solid electrolyte is generally several Hz to 1 MHz and is practically used. The loss (dielectric loss) is expected to be large in a certain frequency region.

  Further, in the technique using the Li ion conductive compound, the rate of change of the capacity (electric capacity) with respect to the frequency is large. For example, in Patent Document 3, when the dielectric film thickness is 20 μm, the electric capacity at 100 kHz is 1 kHz. There is a description of the content that it falls to 10% or less.

  Furthermore, the technique described in Patent Document 4 has a problem that the relative dielectric constant of titanium dioxide used for the main capacitance forming layer is as low as about 100, and it is not possible to efficiently form electric capacitance.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a capacitor that can secure a high electric capacity and has a low dielectric loss.

  (1) The present invention provides, as a first aspect, a solid electrolyte body mainly composed of a solid electrolyte having lithium ion conductivity, the first electrode formed on the solid electrolyte body, the first electrode, A capacitor manufacturing method including a pair of electrodes each including a second electrode disposed so as to face each other with a solid electrolyte body interposed therebetween, and preparing a capacitor forming body including the solid electrolyte body and the pair of electrodes And a first voltage applying step of applying a voltage of 2.5 V or more between the pair of electrodes of the capacitor forming body.

  In the first aspect, since a voltage of 2.5 V or more is applied between the pair of electrodes of the capacitor forming body, a high electric capacity can be secured and the dielectric loss is low, as will be apparent from an experimental example described later. Capacitors can be manufactured.

  Specifically, a high electric capacity can be ensured by using a solid electrolyte body mainly composed of a solid electrolyte having lithium ion conductivity as a dielectric. Further, as will be apparent from the experimental examples described later, when the voltage applied to the capacitor forming body exceeds 2.5 V, a change is seen in the impedance characteristics of the capacitor, and the dielectric loss is reduced. It should be noted that the impedance characteristics of the capacitor change more greatly when the voltage applied to the capacitor forming body exceeds 5V.

  The reason for this is that a voltage higher than the reduction potential of lithium ions (about 3 V) (that is, a voltage of 2.5 V or more) is applied to the solid electrolyte capacitor, whereby the interface between the electrode and the solid electrolyte body (hereinafter referred to as the electrode interface). It is presumed that a phase in which lithium ions cannot move or hardly move is formed in the vicinity and physically blocks (suppresses) the movement of lithium ions to the electrode interface.

  As a result, the influence of the impedance of the electrode interface having a large dielectric loss can be reduced, and it is estimated that the dielectric loss of the capacitor is reduced. Here, 2.5 V is the maximum voltage to be applied.

(2) In the present invention, as a second aspect, the voltage applied in the first voltage application step is an alternating voltage.
In this 2nd aspect, the kind (AC voltage) of the voltage to apply is illustrated.

(3) In the present invention, as a third aspect, the voltage applied in the first voltage application step is a DC voltage.
In the third aspect, the type of voltage to be applied (DC voltage) is illustrated.

  (4) In the present invention, as a fourth aspect, after the first voltage application step, a second voltage is applied between the pair of electrodes in a direction opposite to the voltage applied in the first voltage application step. A voltage applying step;

In the fourth aspect, the type of voltage to be applied (DC voltage) is illustrated. Specifically, the direction in which the DC voltage is applied is not only from one direction but also from both directions.
Thereby, dielectric loss can be further reduced.

(5) In the present invention, as a fifth aspect, the voltage applied in the first voltage application step is a voltage of 2.5 V or more and 10 V or less.
When the applied voltage (maximum voltage) exceeds 10 V, the applied voltage becomes excessive and cracks may occur in the solid electrolyte body. Therefore, the applied voltage is preferably 2.5 V or more and 10 V or less.

(6) As a sixth aspect of the present invention, in the first voltage application step, a voltage is applied between the pair of electrodes in a vacuum atmosphere or an inert gas atmosphere.
When a voltage is applied to the capacitor forming body, components in the atmosphere (for example, oxygen) react with lithium in the solid electrolyte body to decrease the performance of the capacitor (for example, decrease in electric capacity or increase in dielectric loss). )

Therefore, in the sixth aspect, since the voltage is applied in a vacuum atmosphere or an inert gas atmosphere, it is possible to suppress a decrease in the performance of the capacitor.
(7) As a seventh aspect of the present invention, the solid electrolyte is Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ (x is 0 <x ≦ 1).

  In the seventh aspect, a preferable example is given as a material of the solid electrolyte body, and a capacitor using this material can achieve both high electric capacity and low dielectric loss.

BRIEF DESCRIPTION OF THE DRAWINGS The capacitor of embodiment is shown, (a) is the perspective view, (b) is sectional drawing (AA sectional drawing) which fractures | ruptures and shows a capacitor in the thickness direction. It is sectional drawing which fractures | ruptures and shows the sample produced in Example 1 in the thickness direction. It is a graph which shows the experimental result in Example 1, and shows the Cole-Cole plot before and behind an alternating voltage application process. It is a graph which shows the experimental result in Example 1, and shows the relationship between the frequency before and behind an alternating voltage application process, and a dielectric loss tangent (tan-delta). It is a graph which shows the experimental result in Example 1, and shows the relationship between the frequency before and behind an alternating voltage application process, and an electrical capacitance (C). It is a graph which shows the experimental result in Example 2, and shows the Cole-Cole plot before and behind a DC voltage application process. It is a graph which shows the experimental result in Example 2, and shows the relationship between the frequency before and behind a DC voltage application process, and a dielectric loss tangent (tan-delta). It is a graph which shows the experimental result in Example 2, and shows the relationship between the frequency before and behind a DC voltage application process, and an electrical capacitance (C). It is a graph which shows the experimental result in Example 3, and shows the Cole-Cole plot before and behind a pulse voltage application process. It is a graph which shows the experimental result in Example 3, and shows the relationship between the frequency before and behind a pulse voltage application process, and a dielectric loss tangent (tan-delta). It is a graph which shows the experimental result in Example 3, and shows the relationship between the frequency before and behind a pulse voltage application process, and an electrical capacitance (C). It is sectional drawing which fractures | ruptures and shows the sample produced in Example 4 in the thickness direction. It is a graph which shows the experimental result in Example 4, and shows the Cole-Cole plot before and behind an alternating voltage application process. It is a graph which shows the experimental result in Example 4, and shows the relationship between the frequency before and behind an alternating voltage application process, and a dielectric loss tangent (tan-delta). It is a graph which shows the experimental result in Example 4, and shows the relationship between the frequency before and behind an alternating voltage application process, and an electrical capacitance (C).

[Embodiment]
Hereinafter, a method for manufacturing a capacitor according to an embodiment of the present invention will be described.
a) First, the configuration of a capacitor manufactured by the capacitor manufacturing method of the present embodiment will be described.

  As schematically shown in FIG. 1, a capacitor 1 in this embodiment is a rectangular parallelepiped multilayer ceramic chip capacitor, and a solid electrolyte multilayer body 5 in which a plurality of (for example, three layers) solid electrolyte bodies 3 are laminated, and Each internal electrode 7 disposed between the solid electrolyte bodies 3 and a pair of external electrodes 9 provided at both ends in the longitudinal direction of the solid electrolyte laminate 5 (left and right direction in FIG. 1B). Has been.

  Among these, the internal electrode 7 includes a first internal electrode 7a connected to one first external electrode 9a and a second internal electrode 7b connected to the other second external electrode 9b. 7a and the 2nd internal electrode 7b are arrange | positioned so that the center solid electrolyte body 3 may be pinched | interposed.

Hereinafter, a configuration other than the external electrode 9 in the capacitor 1, that is, a sintered body in which the solid electrolyte body 3 and the internal electrode 7 are alternately stacked is referred to as a composite body 11.
The solid electrolyte body 3 is mainly composed of a lithium ion conductive solid electrolyte. For example, Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ (x is 0 <x ≦ 1) (hereinafter referred to as LAGP). There are also).

The internal electrode 7 can employ an electrode made of Pt, for example, and the external electrode 9 can adopt an electrode made of Ag, for example.
b) Next, a method for manufacturing the capacitor 1 of the present embodiment will be described.

Although the manufacturing procedure of the capacitor 1 will be described in detail in an embodiment described later, for example, the following procedures (1) to (10) can be adopted.
Here, a case where each composite 11 is manufactured separately from a flat base material having a plurality of composites 11 will be described as an example.

(1) First, a green sheet is produced using the material of the solid electrolyte body 3 (LAGP).
(2) The green sheet is punched into a predetermined size.
(3) A paste of a material (for example, Pt) of the internal electrode 7 is screen-printed on the punched green sheet. In this case, as electrode shapes, two types of electrode patterns corresponding to the first internal electrode 7a and the second internal electrode 7b are formed. That is, two types of green sheets on which each electrode pattern is formed are produced.

  (4) Each green sheet on which each electrode pattern is formed is laminated so as to correspond to the structure of the composite 11 to produce a laminate. In addition, only the green sheet is laminated | stacked on the uppermost stage of FIG.1 (b).

(5) The laminate is high-pressure pressed by WIP (Warm Isostatic Press) to produce a base material.
(6) A break groove is formed on the base material along the product shape (the shape of each composite 11) using a CO ₂ laser processing machine (break processing is performed).

(7) The base material is cut along the break grooves to produce each unfired composite.
(8) The unfired composite is fired under predetermined conditions to produce a sintered body (composite 11).
(9) A paste of a material (for example, Ag) of the external electrode 9 is applied to the side surface of each composite 11 and baked under a predetermined condition to produce the external electrode 9. Thereby, the capacitor before voltage application (namely, capacitor formation body 1a) is obtained.

  (10) Next, the capacitor formed body 1a is placed in a predetermined atmosphere, and a direct current or a current is formed between the external electrodes 9 (and hence the first internal electrode 7a and the second internal electrode 7b) of the capacitor formed body 1a. A predetermined AC voltage is applied. Specifically, a voltage having a maximum voltage of 2.5 V or more (preferably 10 V or less) is applied. Thereby, the capacitor 1 is completed.

The capacitor 1 manufactured by such a manufacturing method has a high electric capacity and a low dielectric loss, as will be apparent from examples described later.
c) Next, each configuration of the capacitor 1 and the like described above will be described.

As the solid electrolyte, not only Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ (x is 0 <x ≦ 1) but also other solid electrolytes can be adopted. For _{example, Li 1.3 Al 0.3 Ti 1.7 (} PO 4) 3 (LATP), Li x Zr y Nb z (PO 4) 3 (LZNP), Li 1.2 Zr 1.9 Ca 0.1 (PO ₄ ) ₃ (LZCP), Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ), Li _7-x La ₃ Zr _2-x Nb _x O ₁₂ (LLZN), Li _7-x La ₃ Zr _2-x Ta _{x O 12, Li 3x La 2} / 3x Ti 1 / 3x O 3 (LLT), Li 6 BaLa 2 Ta 2 O 12 (LBLT), Li 3 BO 3, Li 3 PO 4 (LiPON), LiS _{-P 2 S 5 (LPS),} Li 10 GeP 2 S 12 (LGPS), Li 1 + x + y Al x (Ti, Ge) 2-x Si y P 3-y O 12 adopts the lithium ion conductor such as (LICGC) It can be.

The solid electrolyte body 3 is preferably composed only of the above-described solid electrolyte having lithium ion conductivity. However, the solid electrolyte body 3 containing a material other than the solid electrolyte in a range of less than 50% by volume is also employed. it can. That is, the solid electrolyte is included in the solid electrolyte layer in a range exceeding 50% by volume.
In addition, as materials other than the solid electrolyte contained in the solid electrolyte layer, for example, a material having electrical insulation (that is, electrical insulation related to electron conductivity and ion conductivity) such as barium titanate (BT) can be employed. Examples of the material having electrical insulation include metal oxides such as strontium titanate, alumina, zirconia, and silica, and resins such as polyethylene, polypropylene, ABS, acrylic, epoxy, and polyimide.
Furthermore, oxides of elements constituting the solid electrolyte can be employed as materials other than the solid electrolyte contained in the solid electrolyte body. Examples of the oxide material of the element constituting the solid electrolyte include AlPO ₄ , TiO ₂ , LaTiO _{3 and the} like.

  As a method of forming the solid electrolyte body 3, a green sheet is produced using the slurry containing the above-described solid electrolyte material, and the green sheet is fired under predetermined conditions to obtain the solid electrolyte body 3 (accordingly, the solid electrolyte laminate). Various known methods such as the method of the body 5) can be adopted. In addition, as predetermined baking conditions, the conditions baked for 1 to 72 hours, for example at 400-1300 degreeC are employable.

  As the material of the internal electrode 7, various known conductive materials such as Au, Pt, Pd, Ag, Ni, Cu can be adopted. As a method of forming the internal electrode 7, various known methods such as a screen printing method using a slurry or paste containing the conductive material can be employed. For example, a thin film method, a coating method, a thermal spraying method, a sputtering method, a plating method, or the like can be adopted. Note that the same material and the same formation method as the internal electrode 7 can be adopted for the external electrode 9.

  As a voltage applied to the capacitor formed body 1a, a range of 2.5V to 10V can be employed. In addition, an AC voltage or a DC voltage can be adopted as the voltage to be applied. In the case of applying a direct current, first, a direct current voltage is applied in a predetermined direction (for example, the direction in which current flows from the first internal electrode 7a to the second internal electrode 7b), and then the reverse direction (for example, the second internal electrode). A DC voltage may be applied in a direction in which a current flows from 7b to the first internal electrode 7a.

An air atmosphere can be adopted as the predetermined atmosphere when applying the voltage. Further, a vacuum atmosphere or an inert gas atmosphere can be employed, and Ar, He, or N ₂ can be employed as the kind of inert gas.

Next, an embodiment of a capacitor manufacturing method will be described in detail.
[Example 1]
a) First, a method for manufacturing the capacitor of Example 1 will be described.

<Calcined powder production process>
First, in order to produce LAGP which is a solid electrolyte, lithium carbonate, zirconium oxide, and aluminum oxide are added in a predetermined amount so as to have a molar ratio of Li _1.5 Al _0.5 Ge _0.5 (PO ₄ ) _3. A mixed material was weighed and mixed. The mixed material was mixed with ethyl alcohol using a nylon pot and zirconia cobblestone. The mixture was dried and calcined with an alumina crucible in an air atmosphere at a maximum temperature of 900 ° C. for 2 hours to prepare a LAGP calcined powder.

<Crushed powder preparation process>
Next, the calcined powder was pulverized for 36 hours together with ethyl alcohol using a nylon pot and zirconia spherulite, and dried to prepare a pulverized powder of LAGP.

<Slurry production process>
Next, the pulverized powder, a binder (acrylic resin), and a plasticizer (dioctyl phthalate) were mixed in a methyl ethyl ketone / toluene mixed solvent to prepare a slurry of LAGP.

<Sheet preparation process>
Next, the slurry was applied to a PET carrier film Si-treated on one side by a doctor blade method to produce a 30 μm thick sheet.

<Internal electrode printing process>
Next, this sheet is punched into a predetermined size, and a Pt electrode material that becomes an internal electrode is formed on one surface of the sheet so as to form a predetermined electrode pattern (the above-described two types of electrode patterns) by screen printing. Printed. The material of the Pt electrode is a paste formed by adding a binder and a solvent to Pt powder.

<Laminated body production process>
Next, a structure (laminated structure) schematically shown in FIG. 2 using two sheets of the Pt electrode material screen-printed (that is, two kinds of sheets having different electrode patterns) and a sheet just punched out, Thus, a laminate of LAGP (matrix of the base material) was produced, and heated to 80 ° C. with WIP and held at 196 MPa for 1000 seconds to perform high pressure pressing to produce a base material.

Thereafter, the base material was subjected to break processing along the product shape with a CO ₂ laser processing machine, and separated into pieces along the break grooves, thereby producing a LAGP laminate (unfired composite).
<Baking process>
Next, the singulated laminate is heated to 280 ° C. in an air atmosphere to remove the binder, and then fired in the air atmosphere by holding at a maximum temperature of 850 ° C. for 20 hours. 11 was produced.

<External electrode manufacturing process>
Next, a silver paste for secondary metallization was applied to the side surface of the composite 11 where the internal electrode 7 was exposed, heated to 350 ° C., held for 15 minutes, and baked to form the external electrode 9.

Thereby, capacitor formation bodies 1a of samples 1 to 6 to be subjected to the following evaluation were obtained.
That is, as shown in FIG. 2, a solid electrolyte laminate 5 in which three layers of solid electrolyte bodies 3 are laminated, a pair of internal electrodes 7 arranged in the solid electrolyte laminate 5, and a side surface of the composite 11. A capacitor 1 (that is, a capacitor forming body 1a) including the formed external electrode 9 and before voltage application was obtained.

Here, the thickness of each solid electrolyte body 3 is, for example, from the top of FIG. 2, T ₁ is 150 μm, T ₂ is 16.5 μm, and T ₃ is 150 μm.
b) Next, evaluation (experimental example) for confirming the performance of the capacitor will be described.

  Among samples 1 to 6, sample 1 was subjected to AC impedance measurement under the following condition (A) and used as comparison data. Samples 2 to 6 were subjected to an AC voltage application process in which an AC voltage was applied under the conditions of the following (B) with the applied voltage shown in the evaluation flow below (that is, the capacitor was formed by applying a voltage to the capacitor forming body). After that, AC impedance measurement was performed under the following conditions (A), and the influence of AC voltage application on the impedance characteristics was investigated.

[Evaluation Flow]
Sample 1: A (no voltage applied)
Sample 2: B (effective value 1 V, maximum voltage about 1.4 V) → A
Sample 3: B (effective value 2 V, maximum voltage about 2.8 V) → A
Sample 4: B (effective value 3 V, maximum voltage about 4.2 V) → A
Sample 5: B (effective value 4 V, maximum voltage about 5.6 V) → A
Sample 6: B (effective value 5 V, maximum voltage about 7 V) → A
A. AC impedance measurement (using Agilent 4294A)
Measurement voltage (effective value): 0.1V
Measurement frequency: 40Hz ~ 110MHz
B. AC voltage application process (using Solartron 1296 and 1255B)
Applied voltage (effective value): 1V, 2V, 3V, 4V, 5V
Applied voltage (maximum value): 1.4V, 2.8V, 4.2V, 5.6V, 7V
Applied frequency: 100Hz
Application time: 1 min
Applied atmosphere: in air From (B) AC impedance measurement after (B) AC voltage application processing described above, the results shown in FIGS. 3 to 5 and Table 1 below were obtained.

  The vertical axis in FIG. 3 is a value obtained by multiplying the imaginary component of the impedance by −1, the horizontal axis is the real component, the vertical axis in FIG. 4 is the dielectric loss tangent (tan δ), and the horizontal axis is the frequency (logarithmic scale only on the horizontal axis). 5 is the electric capacity (C), the horizontal axis is the frequency (the vertical axis and the horizontal axis are logarithmic scales) (the same applies to the same figures in other embodiments).

  Here, Samples 3 to 6 in Table 1 below are examples of the present invention to which a voltage of 2.5 V or more was applied.

なお、前記表１において、比誘電率ε_ｒは、１０ｋＨｚにおける電気容量Ｃと固体電解質体の厚み（Ｔ_２）と電極面積Ｓ（即ち１対の内部電極の互いに対向して重なっている部分の面積）とを用いて計算した見かけの比誘電率である。即ち、比誘電率ε_ｒは、ε_ｒ＝Ｃ・Ｔ_２／（Ｓ・ε_０）の関係から算出した。ここで、ε_０は真空の誘電率であり、８．８５４×１０^−１２（Ｆ／ｍ）である。
誘電損失は、１０ｋＨｚにおけるインピーダンスの（実数成分）／（虚数成分）の絶対値である。誘電損失の変化率は、１０ｋＨｚにおける電圧印加なしの誘電損失に対する電圧印加後の誘電損失の割合である。低損失化の評価の判定基準は、誘電損失の変化率が、「◎：５０％未満」、「○：５０％以上９５％未満」、「×：９５％以上」である。なお、この表１の意味については、以下の表２〜表４についても同様である。

In Table 1, the relative dielectric constant ε _r is the capacitance C at 10 kHz, the thickness (T ₂ ) of the solid electrolyte body, and the electrode area S (that is, the portion of the pair of internal electrodes facing each other and overlapping each other). Area) and the apparent relative dielectric constant. That is, the relative dielectric constant ε _r was calculated from the relationship ε _r = C · T ₂ / (S · ε ₀ ). Here, ε ₀ is the dielectric constant of vacuum and is 8.854 × 10 ⁻¹² (F / m).
The dielectric loss is an absolute value of (real component) / (imaginary component) of impedance at 10 kHz. The rate of change of dielectric loss is the ratio of dielectric loss after voltage application to dielectric loss without voltage application at 10 kHz. The criteria for evaluating the reduction of loss are the rate of change of dielectric loss: “◎: less than 50%”, “◯: 50% or more and less than 95%”, “×: 95% or more”. The meaning of Table 1 is the same for Tables 2 to 4 below.

  As is apparent from the above-described experiment, the impedance characteristic is changed by applying an AC voltage of 2 V (effective value: maximum value is 2.8 V), and the applied voltage is further increased to 4 V (effective value: maximum value). Is about 5.6 V), it can be seen that the impedance characteristics change greatly.

  Further, when the applied voltage is increased, the peak of dielectric loss (tan δ) due to the grain boundary is lowered and C (electric capacity) is reduced, but the apparent dielectric constant of the capacitor is 6000 or more even though it is low. The dielectric constant is equal to or higher than that of barium titanate (BT), which is a general MLCC material that satisfies the well-known B characteristics (standard of temperature characteristics of a high dielectric constant capacitor (Class 2)).

  That is, in the samples 3 to 6 of the example of the present invention in which a voltage of 2.5 V or more is applied by the alternating voltage application process of (B), a high relative dielectric constant (thus high electric capacity) and low dielectric loss are obtained. You can see that both are compatible.

  Although not shown in the table, when the applied voltage is increased, the rate of change of C in a practical frequency band (for example, 1 kHz to 100 kHz) decreases. Further, C at 100 kHz with respect to 1 kHz decreases to about 18% before voltage application, but improves to 50% or more after application of 5 V (effective value: maximum value is about 7 V).

According to the study by the present inventors, in the conventional technique disclosed in Japanese Patent Application Laid-Open No. 2013-225534, when the interlayer thickness is the same as that of the first embodiment, the electric capacity of 100 kHz with respect to 1 kHz is about 10%. It has been confirmed that the value is lowered, and it can be seen that the effect of the present invention is excellent.
[Example 2]
a) First, a method for manufacturing the capacitor of the second embodiment will be described.

In the method for manufacturing a capacitor of Example 2, a capacitor formed body was manufactured through the same steps as in Example 1.
However, there are only differences structure laminated in <laminate manufacturing step> In this step, the thickness T ₂ of the central solid electrolyte body 3 after firing was 33 .mu.m.

By this manufacturing method, capacitor formed bodies of Samples 7 to 12 for the following evaluation were produced.
b) Next, evaluation (experimental example) for confirming the performance of the capacitor will be described.

  Among the samples 7 to 12, the sample 7 was subjected to AC impedance measurement under the following condition (A) and used as comparison data. For Samples 8 to 12, after performing a DC voltage application process of applying a DC voltage under the following condition (C) with the voltage shown in the evaluation flow below, an AC impedance measurement was performed under the following condition (A), The effect of DC voltage application on the impedance characteristics was investigated. For sample 12, a DC voltage application process of 5.6 V was performed, and then a reverse DC voltage application process (DC reverse voltage application process) was performed, and an AC impedance measurement was performed under the following conditions (A) did.

[Evaluation Flow]
Sample 8: C (1.4 V) → A
Sample 9: C (2.8 V) → A
Sample 10: C (4.2 V) → A
Sample 11: C (5.6 V) → A
Sample 12: C (5.6 V) → C (−5.6 V) → A
A. AC impedance measurement (using Agilent 4294A)
Measurement voltage (effective value): 0.1V
Measurement frequency: 40Hz ~ 110MHz
C. DC voltage application processing (using ADC R8340A)
Applied voltage: 1.4V, 2.8V, 4.2V, 5.6V, 5.6V, -5.6V
Application time: 1h
Applied atmosphere: in vacuum After the voltage application, discharge treatment was performed until the voltage of the capacitor became 50 mV or less.

The results shown in FIGS. 6 to 8 and Table 2 below were obtained from (A) AC impedance measurement after the DC voltage application process described above.
Here, Samples 9 to 12 in Table 2 below are examples of the present invention to which a voltage of 2.5 V or higher was applied.

上述した実験の結果から明らかなように、（Ｃ）の直流電圧印加処理により、２．５Ｖ以上の直流電圧を印加した本発明例の試料９〜１２においては、高い比誘電率（従って高い電気容量）と低い誘電損失とを両立できることが分かる。

As is clear from the results of the above-described experiment, in the samples 9 to 12 of the present invention in which a DC voltage of 2.5 V or more was applied by the DC voltage application process of (C), a high relative dielectric constant (thus, a high electrical conductivity). It can be seen that both (capacity) and low dielectric loss can be achieved.

  In particular, by applying a voltage of 5.6 V in the DC voltage application process of (C), the impedance characteristics of the capacitor change to the same extent as when the above-described AC voltage application process is performed, although the degree is small. You can see that

Moreover, about the sample 12, it turns out that a dielectric loss becomes still lower by DC reverse voltage application process (refer Table 2).
[Example 3]
a) First, a method for manufacturing the capacitor of the third embodiment will be described.

In the method for manufacturing a capacitor of Example 3, capacitor formed bodies of Samples 13 to 15 for the following evaluation were manufactured in the same process as in Example 2.
b) Next, evaluation (experimental example) for confirming the performance of the capacitor will be described.

  The samples 13 to 15 were subjected to a pulse voltage application process in which a voltage was applied in a pulse shape (rectangular shape) under the following condition (D), and then an AC impedance measurement was performed under the following condition (A) to obtain impedance characteristics. The effect of the voltage application time on the The sample 7 was also evaluated under the conditions of Example 3.

[Evaluation Flow]
Sample 13: D (5.6 V × 1 second) → A
Sample 14: D (5.6 V × 2.5 seconds) → A
Sample 15: D (5.6 V × 10 seconds) → A
A. AC impedance measurement (using Agilent 4294A)
Measurement voltage (effective value): 0.1V
Measurement frequency: 40Hz ~ 110MHz
D. Pulse voltage application process (using ADC R8340A)
Applied voltage: 5.6V
Application time: 1 second, 2.5 seconds, 10 seconds Applied atmosphere: in vacuum
The results shown in FIGS. 9 to 11 and Table 3 below were obtained from (A) AC impedance measurement after the pulse voltage application process described above.

  Here, Samples 13 to 15 in Table 3 below are examples of the present invention to which a voltage of 2.5 V or higher was applied.

上述した実験の結果から明らかなように、（Ｄ）のパルス電圧印加処理により、２．５Ｖ以上のパルス電圧を印加した本発明例の試料１３〜１５においては、高い比誘電率（従って高い電気容量）と低い誘電損失とを両立できることが分かる。

As is clear from the results of the above-described experiment, the samples 13 to 15 of the present invention to which a pulse voltage of 2.5 V or more was applied by the pulse voltage application process of (D) had a high relative dielectric constant (thus, a high electrical conductivity). It can be seen that both (capacity) and low dielectric loss can be achieved.

It can also be seen that the change in impedance characteristics increases with the application time. That is, as the application time increases, the dielectric loss also decreases (see Table 3), and it is considered that the reforming of the solid electrolyte body is progressing as the application time elapses.
[Example 4]
a) First, a method for manufacturing the capacitor of the fourth embodiment will be described.

Example 4 uses LLZ as the solid electrolyte.
<Calcined powder production process>
First, in order to produce LLZ which is a solid electrolyte, a mixed material in which a predetermined amount of lithium carbonate, lanthanum hydroxide and zirconium oxide is weighed and mixed so as to have a molar ratio of Li ₇ La ₃ Zr ₂ O ₁₂ is prepared. Produced. The mixed material was mixed with ethyl alcohol using a nylon pot and zirconia cobblestone. After the mixture was dried, it was calcined by using an alumina crucible in an air atmosphere at a maximum temperature of 1100 ° C. for 10 hours to prepare a LLZ calcined powder.

<Crushed powder preparation process>
Next, the calcined powder was pulverized for 36 hours together with methyl ethyl ketone using a nylon pot and zirconia spherulite, and dried to prepare LLZ pulverized powder.

<Slurry production process>
Next, the pulverized powder, a binder (butyral resin), and a plasticizer (dioctyl phthalate) were mixed in a methyl ethyl ketone / toluene mixed solvent to prepare an LLZ slurry.

<Sheet preparation process>
Next, the slurry was applied to a PET carrier film Si-treated on one side by a doctor blade method to produce a 20 μm thick sheet.

<Internal electrode printing process>
Next, the sheet is punched into a predetermined size, and a Ni electrode material to be an internal electrode is formed on one surface of the sheet by screen printing to form a predetermined electrode pattern (two types of electrode patterns similar to those in Example 1). ) Was printed. The material for the Ni electrode is a paste obtained by adding a binder and a solvent to Ni powder.

<Laminated body production process>
Next, a structure (laminated structure) schematically shown in FIG. 13 is obtained by using two sheets of Ni electrode material screen-printed (two kinds of sheets similar to Example 1) and a sheet that has been punched out. Then, a laminate of LLZ (matrix of the base material) was produced, and heated to 80 ° C. with WIP and held at 196 MPa for 1000 seconds to perform high pressure pressing to produce a base material.

Thereafter, the base material was subjected to break processing along the product shape with a CO ₂ laser processing machine, and was cut into pieces along the break grooves to produce an LLZ laminate (unfired composite).
<External electrode manufacturing process>
Next, a material for a Ni electrode serving as an external electrode was applied to the side surface where the internal electrode was exposed to the separated laminate.

<Baking process>
Next, the laminate to which the Ni electrode material is applied is heated to 320 ° C. in an air atmosphere to remove the binder, and then a mixed gas atmosphere of 0.13 (volume)% H ₂ / N ₂ ( In a reducing atmosphere, firing was performed at a maximum temperature of 1200 ° C. for 2 hours.

Thereby, samples 16 to 17 of the capacitor formed body 1a to be subjected to the following evaluation were obtained.
That is, as shown in FIG. 12, a solid electrolyte laminate 5 in which three layers of solid electrolyte bodies 3 are laminated, a pair of internal electrodes 7 arranged in the solid electrolyte laminate 5, and a side surface of the composite 11. A capacitor 1 (that is, a capacitor forming body 1a) including the formed external electrode 9 and before voltage application was obtained.

Here, the thickness of each solid electrolyte body 3 is, for example, from the top of FIG. 12, T ₁ is 150 μm, T ₂ is 10 μm, and T ₃ is 150 μm.
b) Next, evaluation (experimental example) for confirming the performance of the capacitor will be described.

  Among the samples 16 and 17, the sample 16 was subjected to AC impedance measurement under the following condition (A) and used as comparison data. For sample 17, the AC voltage was applied under the condition (B) below after applying the AC voltage application process under the condition (B) below with the applied voltage shown in the evaluation flow below, and the AC voltage applied to the impedance characteristics. The effect of application was investigated.

[Evaluation Flow]
Sample 16: A (no voltage applied)
Sample 17: B (effective value 4 V, maximum voltage about 5.6 V) → A
A. AC impedance measurement (using Agilent 4294A)
Measurement voltage (effective value): 0.1V
Measurement frequency: 40Hz ~ 110MHz
B. AC voltage application process (using Solartron 1296 and 1255B)
Applied voltage (effective value): 4V
Applied voltage (maximum value): 5.6V
Applied frequency: 100Hz
Application time: 1 min
Applied atmosphere: in the air The results shown in FIGS. 13 to 15 and Table 4 below were obtained from (A) AC impedance measurement after the above-described (B) AC voltage application process.

  Here, Sample 17 in Table 4 below is an example of the present invention in which a voltage of 2.5 V or higher was applied.

上述した実験の結果から明らかなように、固体電解質としてＬＬＺを用いた場合でも、（Ｂ）の交流電圧印加処理により、２．５Ｖ以上の交流電圧を印加した本発明例の試料１７においては、高い比誘電率（従って高い電気容量）と低い誘電損失とを両立できることが分かる。

As is clear from the results of the above-described experiment, even when LLZ is used as the solid electrolyte, in the sample 17 of the present invention in which an AC voltage of 2.5 V or more was applied by the AC voltage application process of (B), It can be seen that both a high dielectric constant (and hence high electric capacity) and a low dielectric loss can be achieved.

  That is, even when LLZ is used as the solid electrolyte, a change in impedance can be seen by applying an AC voltage of 4 V (effective value: maximum value is about 5.6 V), and although C is lowered, dielectric loss is reduced. It can be seen that the same effect as in the case of LAGP can be obtained.

In addition, this invention is not limited to the said embodiment and Example at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
For example, as a form different from the structure of the capacitor of the above embodiment, a structure in which four or more layers of solid electrolyte bodies are stacked is provided, and a plurality of first internal electrodes and a plurality of second internal electrodes are provided, and they enter each other. You may arrange in a comb-tooth shape so that it may assemble.

DESCRIPTION OF SYMBOLS 1 ... Capacitor 1a ... Capacitor formation body 3 ... Solid electrolyte body 5 ... Solid electrolyte laminated body 7, 7a, 7b ... Internal electrode 9, 9a, 9b ... External electrode 11 ... Composite

Claims (7)

A solid electrolyte body mainly composed of a solid electrolyte having lithium ion conductivity;
A pair of electrodes composed of a first electrode formed on the solid electrolyte body and a second electrode disposed opposite to the first electrode with the solid electrolyte body interposed therebetween;
A method of manufacturing a capacitor including:
Preparing a capacitor forming body including the solid electrolyte body and the pair of electrodes;
A first voltage applying step of applying a voltage of 2.5 V or more between the pair of electrodes of the capacitor forming body;
A method for producing a capacitor, comprising:   The method for manufacturing a capacitor according to claim 1, wherein the voltage applied in the first voltage application step is an alternating voltage.   The method for manufacturing a capacitor according to claim 1, wherein the voltage applied in the first voltage applying step is a direct current voltage.   The second voltage application step of applying a voltage in a direction opposite to the voltage applied in the first voltage application step between the pair of electrodes after the first voltage application step. 4. A method for producing a capacitor according to 3.   5. The method of manufacturing a capacitor according to claim 1, wherein the voltage applied in the first voltage application step is a voltage of 2.5 V or more and 10 V or less.   6. The capacitor according to claim 1, wherein in the first voltage application step, a voltage is applied between the pair of electrodes in a vacuum atmosphere or an inert gas atmosphere. Manufacturing method. The solid _{electrolyte, Li 1 + x Al x Ge} 2-x (PO 4) 3 (x is, 0 <x ≦ 1) of the capacitor according to any one of claims 1 to 6, characterized in that it is Production method.

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