JP2000243651A - Multilayer ceramic electronic component and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer ceramic electronic component, in which deterioration of insulation resistance in high humidity is small and reliability is superior. SOLUTION: Electrode paste turning to inner electrode layers 2 are formed in desired inner electrode layer patterns on a green sheet which turns into ceramic layers 1, baking is performed after laminating the inner electrode layers, and glass layers 3 are formed on interfaces of the ceramic layers 1 and the inner electrode layers 2. After that, an external electrode 4 is formed on the exposed end surfaces of the inner electrode layers 2. Thereby the deterioration of insulation resistance at a high temperature and a high humidity can be restrained, and a multilayer ceramic electronic component whose reliability is improved can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component in which ceramic layers such as a multilayer ceramic capacitor and internal electrode layers are alternately laminated, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor has a structure in which dielectric layers and internal electrode layers are alternately laminated to form a laminate, which is fired, and then external electrodes are formed on the end faces thereof. There is a strong demand for capacitance, and the purpose is to be achieved by making the dielectric layer thinner. At present, multilayer ceramic capacitors having a sintered dielectric layer having a thickness of 5 μm or less are being achieved.

[0003]

However, as the thickness of the dielectric layer becomes thinner, defects in the electrical characteristics may occur due to defects such as voids existing in the dielectric layer. In particular, during a continuous load test in high temperature and high humidity,
When moisture penetrates along the interface between the internal electrode layer and the dielectric layer and reaches structural defects such as voids in the dielectric layer, there is a problem that the insulation resistance is deteriorated.
This problem arises because moisture easily penetrates along the interface because the bonding force between the dielectric layer and the internal electrode layer is small and adhesion is poor.

Accordingly, an object of the present invention is to provide a multilayer ceramic electronic component capable of improving the adhesion between an internal electrode layer and a ceramic layer and preventing moisture from penetrating into the ceramic layer.

[0005]

In order to achieve this object, a multilayer ceramic electronic component according to the present invention comprises a laminate in which ceramic layers and internal electrode layers are alternately laminated, and a method for exposing the internal electrode layers of the laminate. An external electrode provided on the end face,
The internal electrode layer is formed of an electrode paste obtained by mixing a metal component and a glass component.

With the above structure, the glass component added to the electrode paste forming the internal electrode layer precipitates between the ceramic layer and the internal electrode layer to form a glass layer.
It is possible to improve the adhesion between the two, suppress the intrusion of moisture, and prevent the insulation resistance from deteriorating.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a laminated body in which ceramic layers and internal electrode layers are alternately laminated, and an external layer provided on an exposed end face of the internal electrode layer of the laminated body. The internal electrode layer is formed of an electrode paste obtained by mixing a metal component and a glass component. The internal electrode layer improves the adhesion between the ceramic layer and the internal electrode layer, prevents infiltration of moisture, prevents insulation resistance. Degradation can be prevented.

According to a second aspect of the present invention, the glass component in the electrode paste is deposited on the interface between the ceramic layer and the internal electrode layer by firing, and the ceramic layer and the internal electrode layer are firmly bonded. become.

According to a third aspect of the present invention, the glass component in the electrode paste is the same as the glass component used for the material for forming the ceramic layer, so that the bonding between the ceramic layer and the internal electrode layer becomes stronger, and Characteristic deterioration can be prevented.

According to a fourth aspect of the present invention, the glass component in the electrode paste is 25% when the metal component is 100% by weight.
wt% or less, and a multilayer ceramic electronic component having a sufficient capacitance can be obtained.

According to a fifth aspect of the present invention, the glass component in the electrode paste has an average particle diameter smaller than the thickness of the internal electrode layer, so that the internal electrode layer is not broken. .

According to a sixth aspect of the present invention, the glass component used for the electrode paste has a softening point higher than the sintering temperature of the metal component and lower than the sintering temperature of the ceramic layer. It is easy to form a glass layer at the interface between the substrate and the internal electrode layer.

According to a seventh aspect of the present invention, the glass component used in the electrode paste has an average particle size larger than the average particle size of the glass component used in the material for forming the ceramic layer. Is excessively diffused into the ceramic layer.

According to the present invention, the ceramic layer is a dielectric ceramic composition represented by the following chemical formula (2), and the metal component of the internal electrode layer is mainly composed of Ni, so that the insulation deterioration is small. It can be highly reliable.

[0015]

Embedded image

According to a ninth aspect of the present invention, there is provided a laminated body in which ceramic layers and internal electrode layers are alternately laminated, an external electrode provided on an exposed end face of the internal electrode layer of the laminated body, The ceramic layer includes a glass layer provided at an interface between the ceramic layer and the internal electrode layer, and the ceramic layer is formed using the same glass component as the glass layer. It can be excellent.

According to a tenth aspect of the present invention, there is provided a process for forming a laminated body in which ceramic layers and internal electrode layers are alternately laminated, a step of firing the laminated body, and a step of firing the laminated internal electrode layer. Forming an external electrode on both end surfaces where the electrodes are exposed, wherein the internal electrode layer is formed using an electrode paste composed of a metal component and a glass component. Can be provided.

An eleventh aspect of the present invention is a method wherein a step of exposing an internal electrode layer by polishing the surface of a laminate is provided between a firing step and a step of forming an external electrode. The layer and the external electrode can be reliably connected.

Hereinafter, an embodiment of the present invention will be described by taking a multilayer ceramic capacitor as an example.

FIG. 1 is a cross-sectional view showing a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component in the present embodiment, wherein 1 is a ceramic layer made of a dielectric, 2 is an internal electrode layer, 3 is a glass layer, and 4 is a glass layer. External electrodes.

First, as a starting material of the ceramic layer 1, high purity
BaCO of degree_Three, CaCO_Three, TiO _Two, ZrO_Two, Y
_TwoO_Three, Mn_ThreeO_Four, Dy_TwoO_Three, V_TwoO_Five, NiO, BaO-
Al_TwoO_Three-SiO_TwoIs shown in (Chemical formula 2)
Thus, carbonate is converted into oxide and the composition falls within the scope of the present invention.
Weighed to ratio.

Next, it was put into a ball mill equipped with zirconia balls together with pure water, wet-mixed, and dehydrated and dried. Next, the dried powder was put into a high-purity alumina crucible and calcined in air at 1100 ° C. for 2 hours. Thereafter, the calcined powder was put together with pure water into a ball mill equipped with zirconia balls, wet-pulverized, and then dehydrated and dried. At this time, the average particle size of the pulverized powder was adjusted to 2 μm or less.

Next, a polyvinyl butyral resin as an organic binder, BBP (benzyl butyl phthalate) as a plasticizer, and n-butyl acetate as a solvent were added to the ground powder and mixed in a ball mill equipped with zirconia to prepare a slurry. Next, the slurry was vacuum-defoamed, and then formed into a film by a doctor blade method, thereby producing a green sheet to be the ceramic layer 1. At this time, the thickness of the green sheet after drying was set to about 15 μm.

On the other hand, with respect to a commercially available electrode paste made of Ni powder having an average particle size of about 1 μm, the average particle size is about 1 μm.
To those without the addition of ternary glass of _{BaO-Al 2 O 3 -SiO 2} , Ni powder 100 wt% for each 0.001wt%, 0.01wt%, 0.1wt% , 1
Rolls kneaded with wt%, 2 wt% and 2.5 wt% were added, respectively, to uniformly disperse the glass component to obtain an electrode paste for an internal electrode layer.

Next, the electrode paste for an internal electrode layer was screen-printed on a green sheet so as to form a desired internal electrode layer pattern. After drying, 80 pieces of the internal electrode layer pattern were overlapped so that they face each other with a green sheet interposed therebetween. After heating and pressurizing, they were integrated, then cut into dimensions of 2.2 mm in length and 1.3 mm in width. A laminate was prepared.

Next, this unsintered laminate is placed in a zirconia sheath covered with zirconia powder, heated to 350 ° C. in the air to burn the organic binder, and then in N ₂ + H ₂ ,
The sintered body was obtained by firing at 1300 ° C. for 2 hours. Next, after chamfering the obtained sintered body, a commercially available 9
A copper paste for firing in a nitrogen atmosphere at 00 ° C. was applied and baked in a continuous belt furnace of a mesh type to obtain a multilayer ceramic capacitor. The thickness of the ceramic layer 1 is about 10 μm.
m, and the thickness of the internal electrode layer 2 was about 2 to 2.5 μm.

Next, the capacitance, dielectric loss, and insulation resistance of the obtained multilayer ceramic capacitor were measured. Capacitance,
The dielectric loss was measured at a frequency of 1 kHz and an input signal level of 1.0 Vrms in a thermostat at 20 ° C., and the insulation resistance was measured after loading at 16 V for 1 minute. Thereafter, 100 laminated ceramic capacitors formed using the electrode pastes for the internal electrode layers having different amounts of added glass were prepared, each of which was 100 pieces.
85 ° C, 85% high temperature and high humidity in a constant temperature bath, 16V
After applying a DC voltage, the change in insulation resistance was measured periodically. Table 1 shows the initial electrical characteristics of each multilayer ceramic capacitor and the number of insulation resistance deteriorations in a wet and medium load test.

[0028]

[Table 1]

According to Table 1, in the initial electrical characteristics, it is found that if the glass addition amount exceeds 2.5 wt%, a sufficient capacitance cannot be obtained, which is not preferable. Further, the deterioration of the insulation resistance in the wet and medium load test occurs only in the multilayer ceramic capacitor to which no glass is added. Further, when the interface between the internal electrode layer 2 and the ceramic layer 1 of the multilayer ceramic capacitor in which glass is added to the electrode paste for the internal electrode layer is observed with a scanning electron microscope, a glass layer 3 is present at the interface. This improves the adhesion between the layer 2 and the ceramic layer 1 and suppresses the intrusion of moisture. This indicates that the addition of glass to the electrode paste for the internal electrode layer has a great effect on the deterioration of insulation resistance in a wet and medium load test.

The points in the present embodiment will be described below.

(1) B as a starting material of the ceramic layer 1
aCO ₃ , CaCO ₃ , TiO ₂ , ZrO ₂ , Y ₂ O ₃ , Dy
_Although 2O ₃ , Mn ₃ O ₄ , V ₂ O ₅ , and NiO were used, BaO, a compound such as BaTiO ₃ , or a carbonate, a hydroxide, or the like was heated in air to obtain a desired composition ratio. C
Even when a compound that becomes aO, TiO ₂ , ZrO ₂ , Y ₂ O _3, and Dy ₂ O ₃ is used, characteristics similar to those of the present embodiment can be obtained.

Ba and Ti as main components are BaTi
By adding the compound of O ₃ , Tan δ can be improved. The reason for this is that the crystallinity of BaTiO ₃ , which is the main component of the ceramic layer 1, is improved and the variation in the particle diameter is also reduced. Therefore Ba
TiO ₃ is most preferably formed by an oxalate method, and then preferably formed by a sol-gel method and subsequently by a solid phase method. In addition, powders were used for all starting materials, but Y ₂ O _3, Dy ₂ O ₃ , Mn ₃
O ₄ may be added as a liquid in order to improve dispersibility.

Further, when barium titanate is used as a starting material, its specific surface area is higher than that of barium titanate in CaCO ₃ , Mn ₃ O ₄ , Y ₂ O ₃ , Dy ₂ O ₃ , V ₂ O ₅ ,
By making the subcomponent of NiO larger, the reactivity between the main component barium titanate and the subcomponent is improved, and the insulation resistance is improved. Specifically, the specific surface area of barium titanate is 3 m ² / g or more, and CaCO ₃ , Mn ₃ O ₄ ,
It is preferable to use Y ₂ O ₃ , Dy ₂ O ₃ , V ₂ O ₅ , and a subcomponent of NiO having a specific surface area of 5 m ² / g or more.

(2) Although Ni is used for the internal electrode layer 2, any metal containing Ni such as Ni—Cu and having a melting point higher than the firing temperature of the ceramic layer 1 is used as the internal electrode layer 2. be able to. Specifically, 135
Those at 0 ° C. or higher are preferred.

(3) The binder removal and firing conditions are fixed, but the binder removal step may be performed by optimally selecting the heat treatment condition according to the combustion temperature of the organic binder to be used. The firing step is N ₂ + H _2. The atmosphere is not limited to firing in the atmosphere, and any atmosphere may be used as long as the ceramic layer 1 is not reduced and the internal electrode layer 2 is not excessively oxidized, that is, the atmosphere can be fired so as to function as the internal electrode layer 2.

However, when firing a large number of laminates at once, the binder in the laminates may not be completely decomposed in the binder removal step. If the undecomposed binder remains during the sintering of the ceramic layer 1,
There is a possibility that the ceramic layer 1 is reduced or a structural defect is caused. Therefore, in the firing step, the temperature increase is temporarily stopped in a temperature range equal to or higher than the binder decomposition temperature and lower than the sintering start temperature of the ceramic layer 1, and a holding process at this temperature is provided to decompose the residual organic matter in the laminate. It is desirable.
In particular, near the maximum temperature during firing, a sufficient relative dielectric constant and insulation resistance can be obtained at a low oxygen partial pressure of 1/20 to 1/10000 from the equilibrium oxygen partial pressure of Ni.

However, 1/100 of the equilibrium oxygen partial pressure
When firing is performed at an oxygen partial pressure lower than 00, the ceramic layer 1 is reduced, and the insulation resistance may decrease. At this time,
The insulation resistance can be recovered by performing a heat treatment in an atmosphere at or above the equilibrium oxygen partial pressure of Ni after the temperature step of firing or after firing. The maximum temperature during firing is 1250 ° C
A sufficient relative dielectric constant is obtained at a temperature in the range of 1350 ° C.

(4) BaCO_Three, CaCO_Three, TiO_Two,
ZrO_Two, Y_TwoO_Three, Mn_ThreeO_Four, Dy_TwoO_ThreeOf Ni and NiO
Sometimes BaO-Al_TwoO_Three-SiO_TwoTernary glass
It was mixed with BaCO_Three, CaCO_Three, TiO_Two, Z
rO_Two, Y_TwoO_Three, Mn_ThreeO_Four, Dy _TwoO_Three, NiO calcined
BaO-Al_TwoO_Three-SiO_TwoTernary system
Even if glass is added and mixed, the same effect as above can be obtained.
it can.

(5) Since the amount of Mn that causes a decrease in the dielectric constant can be reduced by adding Mn ₃ O ₄ , the original dielectric constant of the dielectric ceramic composition represented by the chemical formula (2) can be reduced. Since the Curie point is high, even if the Curie point is shifted to a lower temperature side, the capacitance is less reduced due to deterioration with time. Therefore, even if the ceramic layer 1 is made thinner and more highly laminated, a multilayer ceramic capacitor with less deterioration with time of the capacitance is obtained.

(6) As for the Ni component, NiO may be added as a subcomponent to the starting material of the ceramic layer 1. However, when Ni is used as the internal electrode layer 2, NiO is used as the starting material of the ceramic layer 1. May be added and Ni may be oxidized at the time of firing and diffused into the ceramic layer 1 as NiO. In each case, the ceramic layer 1
Ni component in the material is converted to NiO, and the main component is 100% by weight.
It is important to control the firing conditions so as not to exceed 0.2% by weight, and not to reduce the ceramic layer 1 too much and not to oxidize the internal electrode layer 2 too much.

(7) It is desirable that the glass component to be added to the electrode paste forming the internal electrode layer 2 is added in an amount of 0.001 wt% to 2 wt% with respect to 100 wt% of the metal component in the electrode paste. Internal electrode layer 2 and ceramic layer 1
Although the adhesiveness of is surely improved at 0.001 wt% or more,
This is because if added in excess of 2 wt%, the continuity of the internal electrode layer 2 is impaired, and a problem such as a decrease in capacitance occurs.

The points of the whole invention will be described.

(1) In the above embodiment, the ceramic layer 1 is made of the dielectric ceramic composition represented by Chemical Formula 2, and the internal electrode layer 2 is made of Ni. However, the composition is not limited to this. .

(2) When the laminate is fired, the internal electrode layer 2
The glass layer 3 is deposited not only on the interface between the metal layer and the ceramic layer 1 but also on the internal electrode layer 2 exposed at the end face of the laminate. Therefore, in order to secure the electrical connection between the internal electrode layer 2 and the external electrode 4, the surface of the laminate is polished to remove the glass layer on the surface of the laminate, and the internal electrode layer 2 is laminated. The external electrode 4 is formed after being exposed to the end face of the body.

(3) The same glass component as that used for the material for forming the ceramic layer 1 is used as the glass component to be added to the electrode paste for forming the internal electrode layer 2 so that the ceramic layer 1 and the internal electrode layer 2 The bonding strength is further improved. In addition, some inorganic components that contribute as glass components, even when added to the internal electrode layer 2, diffuse in a large amount into the ceramic layer 1 during firing, thereby alienating the electrical characteristics of the ceramic layer 1. Therefore, by using the same glass component as the glass component contained in the ceramic layer 1,
Even if the glass component used to form the internal electrode layer 2 diffuses into the ceramic layer 1, the electrical characteristics of the ceramic layer 1 are not significantly impaired. However, even if the same glass component as the glass material of the material for forming the ceramic layer 1 is added to the electrode paste forming the internal electrode layer, the glass component from the internal electrode layer 2 is taken into account in consideration of the glass component from the internal electrode layer 2. Since it is difficult to determine the formulation,
It is preferable that diffusion of the glass component from the internal electrode layer 2 to the ceramic layer 1 is suppressed as much as possible, and that the glass component is precipitated at the interface between the ceramic layer 1 and the internal electrode layer 2.

Therefore, the following method is conceivable for effectively depositing at the interface.

The softening point of the glass component used for the electrode paste forming the internal electrode layer 2 is higher than the sintering temperature of the metal component forming the internal electrode layer 2 and lower than the sintering temperature of the ceramic layer 1. Used. This is because if the softening point is too high, the fluidity of the glass component is so small that it hardly precipitates at the interface, does not contribute to the adhesion between the internal electrode layer 2 and the ceramic layer 1 at all, and if the softening point is too low, it diffuses into the ceramic layer 1. This is because it is easy to do. In the above embodiment, the glass component has a softening point higher than the sintering temperature of Ni and the ceramic layer 1
The temperature range of 900 to 1350 ° C. lower than the sintering temperature was used.

The glass component used for the electrode paste for forming the internal electrode layer 2 is larger than the average particle diameter of the glass component used for the material for forming the ceramic layer 1.
This is because, when the glass contained in the internal electrode layer 2 is smaller than the glass contained in the ceramic layer 1, the glass may diffuse into the ceramic layer 1 during the sintering process and may not be easily present at the interface. .

(4) The glass component used for the electrode paste forming the internal electrode layer 2 is equal to or more than the average particle diameter of the metal component forming the internal electrode layer 2 and is larger than the thickness of the internal electrode layer 2 to be formed. Use particles having a small average particle size.
This is because, when the average particle diameter of the glass component is extremely small, the glass component is easily diffused into the ceramic layer 1, and when the average particle diameter is extremely large, delamination is easily generated.

(5) Even if the glass layer 3 at the interface between the ceramic layer 1 and the internal electrode layer 2 exists only on a part of the surface of the internal electrode layer 2 in contact with the ceramic layer 1, the effect of suppressing the deterioration of insulation resistance is obtained. However, it is preferably present throughout. However, when the glass layer 3 is to be formed on the entire surface of the internal electrode layer 2, problems such as the glass layer 3 being too thick to obtain a desired capacitance are caused. On the other hand, it is very difficult to form a thin glass layer 3 on the entire surface of the internal electrode layer 2. Therefore, as thin a glass layer as possible,
The internal electrode layer 2 can be formed so as to cover the surface as widely as possible.

(6) If the amount of glass added to the electrode paste for forming the internal electrode layer 2 is too large, the internal electrode layer 2 is cut and the capacitance is reduced. Therefore, it is important that the addition amount is such that the adhesiveness of the ceramic layer 1 and the internal electrode layer 2 is improved and the electrical characteristics such as the desired capacitance can be obtained in accordance with the material of the formation. is there.

(7) In the above embodiments, the multilayer ceramic capacitor has been described. However, a multilayer ceramic electronic component in which ceramic layers and metal layers are alternately laminated such that a problem may occur when moisture enters the ceramic layers. It can easily be inferred that the same effect can be obtained also for.

[0053]

As described above, according to the present invention, deterioration of insulation resistance in high temperature and high humidity can be suppressed, and a multilayer ceramic electronic component with improved reliability can be obtained. In particular, a large-capacity multilayer ceramic capacitor having a large number of layers can exert a great effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multilayer ceramic electronic component according to an embodiment of the present invention.

[Explanation of symbols]

 1 ceramic layer 2 internal electrode layer 3 glass layer 4 external electrode

Claims (11)

[Claims] 1. A laminate comprising a ceramic layer and an internal electrode layer alternately laminated, and an external electrode provided on an exposed end face of the internal electrode layer of the laminate, wherein the internal electrode layer comprises a metal component and glass. A multilayer ceramic electronic component composed of an electrode paste obtained by mixing components. 2. The multilayer ceramic electronic component according to claim 1, wherein the glass component in the electrode paste is deposited on the interface between the ceramic layer and the internal electrode layer by firing. 3. The multilayer ceramic electronic component according to claim 1, wherein the glass component in the electrode paste is the same as the glass component used for the material for forming the ceramic layer. 4. The multilayer ceramic electronic component according to claim 1, wherein the glass component in the electrode paste is 25 wt% or less when the metal component is 100 wt%. 5. The glass component in the electrode paste has an average particle diameter smaller than the thickness of the internal electrode layer.
3. The multilayer ceramic electronic component according to item 1. 6. The multilayer ceramic electronic component according to claim 1, wherein the glass component used for the electrode paste has a softening point higher than the sintering temperature of the metal component and lower than the sintering temperature of the ceramic layer. 7. The multilayer ceramic electronic component according to claim 1, wherein the glass component used for the electrode paste has an average particle size larger than the average particle size of the glass component used for the material for forming the ceramic layer. 8. The multilayer ceramic electronic component according to claim 1, wherein the ceramic layer is a dielectric ceramic composition represented by Chemical Formula 1, and a metal component of the internal electrode layer is mainly composed of Ni. Embedded image 9. A laminate in which ceramic layers and internal electrode layers are alternately laminated, an external electrode provided on an exposed end face of the internal electrode layer of the laminate, and a ceramic layer and an internal electrode layer in the laminate. And a glass layer provided at an interface of the multilayer ceramic electronic component, wherein the ceramic layer is formed using the same glass component as the glass layer. 10. A step of forming a laminated body in which ceramic layers and internal electrode layers are alternately laminated, a step of firing the laminated body, and a step of forming external layers on both end surfaces of the fired laminated body where the internal electrode layers are exposed. Forming an electrode, wherein the internal electrode layer is formed using an electrode paste comprising a metal component and a glass component. 11. The method for manufacturing a multilayer ceramic electronic component according to claim 10, wherein a step of exposing the internal electrode layer by polishing the surface of the laminate is provided between the firing step and the step of forming the external electrodes. .