JP2008130770A - Electronic component and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a CR composite component having less variation in the resistance value by improving the resistance of a resistor layer against a plating liquid in the CR composite component. <P>SOLUTION: In the electronic component (CR composite component), the resistor layer 4 and an external electrode layer 5 are formed on a ground electrode layer 3 in a laminated ceramic capacitor 2. The resistor layer contains a glass constituent. The glass constitute contains compositions, such as 20 to 35 wt.% BaO, 10 to 20 wt.% B<SB>2</SB>O<SB>3</SB>, 30 to 40 wt.% SiO<SB>2</SB>, 5 to 25 wt.% ZnO, and 10 wt.% or less alkali metal oxide. The resistor layer may further contain NiO. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component (CR composite component) in which a resistor layer is formed on an electrode portion of a multilayer ceramic capacitor, and further relates to a manufacturing method thereof.

  For example, in a secondary side circuit such as a DC-DC converter or a switching power supply, the equivalent series resistance (ESR) of the smoothing circuit greatly affects the phase characteristics of the feedback loop, and a problem may occur particularly when the ESR becomes extremely low. . That is, when a multilayer ceramic capacitor having a low ESR is used as the smoothing capacitor, the secondary side smoothing circuit is equivalently composed of only the L and C components, and the phase components existing in the circuit are only ± 90 ° and 0 °. Thus, there is no phase margin and oscillation easily occurs. A similar phenomenon appears as an oscillation phenomenon when the load fluctuates even in a power supply circuit using a three-terminal regulator.

  Or, in the CR circuit or the like, the problem is that the impedance varies depending on the frequency and the voltage fluctuates as the current decreases. For example, with recent dual-core CPUs and the like, current fluctuations occur with a period of several kHz to 100 MHz, and voltage fluctuations occur due to the impedance of the power supply. Therefore, in order to cope with these disadvantages, electronic components such as CR composite components have been proposed in which a resistance layer is formed on the base electrode of the multilayer ceramic capacitor and this is functioned as a resistor so that ESR is increased to some extent. (See, for example, Patent Document 1).

In Patent Document 1, a multilayer ceramic capacitor element body in which an internal electrode is formed, a base electrode layer provided on the end face where the internal electrode of the capacitor element body is exposed so as to be electrically connected to the internal electrode, A CR element is disclosed that includes a resistance layer provided on a base electrode layer and a base electrode layer provided on the resistance layer and not in contact with the base electrode layer. By using such a CR element and appropriately controlling the resistance value of the resistance layer, voltage fluctuation can be suppressed regardless of the frequency.
Japanese Patent Laid-Open No. 10-303066

  By the way, in the CR composite part, it is necessary to form an external electrode on the resistor layer, and for this purpose, a plating step after the resistor layer is formed is necessary. In this plating process, the multilayer ceramic capacitor with the resistor layer formed is immersed in the plating solution. However, when the resistor layer is immersed in the plating solution, the glass contained in the resistor layer is melted and the resistance is increased. The problem arises that the value fluctuates.

  The present invention has been proposed in view of such a conventional situation, and an object of the present invention is to provide an electronic component (CR composite component) with improved resistance to plating solution and less resistance value fluctuation. Furthermore, it aims at providing the manufacturing method.

In order to achieve the above object, an electronic component of the present invention is an electronic component in which a resistor layer and an external electrode are formed on a base electrode of a multilayer ceramic capacitor, and the resistor layer includes a glass component. The composition of the glass component is
BaO 20 mass%-35 mass%
B ₂ O ₃ 10 wt% to 20 wt%
SiO ₂ 30% by mass to 40% by mass
ZnO 5 mass% to 25 mass%
The alkali metal oxide is 10% by mass or less.

  The glass component having the above-described composition has high resistance to the plating solution, and when the glass component is immersed in the plating solution, the glass component is prevented from being melted and the resistance value of the resistor layer is prevented from fluctuating.

  In addition, the inclusion of NiO in the resistor layer is also effective in improving the resistance to the plating solution of the resistor layer. This is defined by the invention according to claim 3 of the present application, wherein the glass component contains NiO, and the content of NiO is 30% by mass or less of the glass component.

The aforementioned resistor layer is formed by baking a resistor paste containing the glass component. That is, the method for manufacturing an electronic component of the present invention is a method for manufacturing an electronic component in which a resistor layer and an external electrode are formed on a base electrode of a multilayer ceramic capacitor, and the resistor layer has a glass component having the following composition: It is characterized by applying a resistor paste containing sinter and firing in the atmosphere.
BaO 20 mass%-35 mass%
B ₂ O ₃ 10 wt% to 20 wt%
SiO ₂ 30% by mass to 40% by mass
ZnO 5 mass% to 25 mass%
Alkali metal oxide 10% by mass or less

  In order to contain NiO in the resistor layer, for example, when the internal electrode of the multilayer ceramic capacitor contains Ni, after forming the base electrode so that Ni exists on the surface, the resistor layer is formed thereon Form. Alternatively, after forming a base electrode containing Ni, the resistor layer is formed thereon.

  According to the present invention, it is possible to significantly improve the plating solution resistance of the resistor layer, and it is possible to form a resistor layer with little resistance value change. Therefore, it is possible to provide a highly reliable electronic component (CR composite component) with little change in performance.

  Hereinafter, an electronic component (CR composite component) to which the present invention is applied and a manufacturing method thereof will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a CR composite part. The CR composite component 1 includes a multilayer ceramic capacitor 2 that is a ceramic multilayer body as an element body, and a base electrode layer 3, a resistor layer 4, and an external electrode layer 5 are formed on the side surfaces thereof.

  In the multilayer ceramic capacitor 2, a plurality of dielectric ceramic layers 21 and internal electrode layers 22 are alternately stacked. The internal electrode layer 22 is laminated so that the side end faces are alternately exposed on the two opposing end faces of the element body, and a pair of base electrodes 3 are provided on both side ends of the element body. It is formed so as to be electrically connected. The shape of the element body is not particularly limited, but is usually a rectangular parallelepiped shape. The dimensions are not particularly limited, and may be set to appropriate dimensions according to the application.

The dielectric ceramic layer 21 constituting the multilayer ceramic capacitor 2 is made of a dielectric ceramic composition, and is formed by sintering powder (ceramic powder) of the dielectric ceramic composition. The dielectric ceramic composition includes, for example, a composition formula ABO ₃ (wherein the A site is composed of at least one element selected from Sr, Ca and Ba. The B site is at least selected from Ti and Zr). And the like containing a dielectric oxide having a perovskite crystal structure represented by the following formula: Among the dielectric oxides, barium titanate or the like in which the A site element is Ba and the B site element is Ti is preferable.

  The dielectric ceramic composition may contain various subcomponents in addition to the main component. Subcomponents are selected from oxides of Sr, Zr, Y, Gd, Tb, Dy, V, Mo, Zn, Cd, Ti, Sn, W, Ba, Ca, Mn, Mg, Cr, Si and P. At least one is exemplified. By adding the subcomponent, for example, low temperature firing is possible without deteriorating the dielectric characteristics of the main component. Further, the occurrence of defects when the dielectric ceramic layer 21 is thinned is reduced, and the life can be extended.

  Various conditions such as the number and thickness of the dielectric ceramic layers 21 may be appropriately determined according to required characteristics and applications. The thickness of the dielectric ceramic layer 21 is about 1 μm to 50 μm and is usually about 5 μm to 20 μm, but may be 5 μm or less. For example, from the viewpoint of reducing the size and capacity of the multilayer ceramic capacitor 2, the thickness of the dielectric ceramic layer 21 is preferably 3 μm or less. The number of laminated dielectric ceramic layers 2 is about 2 to 300, but is preferably 150 or more in consideration of characteristics.

  The internal electrode layer 22 can be made of any metal material. For example, by using a base metal such as Ni, Cu, Ni alloy or Cu alloy for the internal electrode layer 22, the manufacturing cost is higher than when noble metal is used. Can be reduced. In addition, the thickness of the internal electrode layer 22 may be appropriately determined according to the use and the like, and is, for example, about 0.5 μm to 5 μm, and preferably 1.5 μm or less.

  The base electrode layer 3 formed on the side surface of the multilayer ceramic capacitor 2 functions as a base electrode layer and is electrically connected to the internal electrode layer 22 of the multilayer ceramic capacitor 2. For the formation of the base electrode layer 3, an electrode forming composition containing a conductive metal material and a glass component is used. Here, as the conductive metal material, any metal material can be used as long as it can conduct electricity. However, it is possible to form a dense base electrode layer 3 having excellent oxidation resistance and an internal electrode layer. A noble metal material having an excellent protection function of 22 is suitable. Specific examples include Ag, Pd, Au, Pt, and alloys thereof.

  A resistor layer 4 is formed on the base electrode layer 3 described above. As a result, a capacitor C (multilayer ceramic capacitor 2) and a resistor R (resistor layer 4) are connected in series, and a CR composite component As a function.

The resistance material used for the resistor layer 4 is arbitrary, and for example, it is preferable to use a mixture (so-called metal glaze) of a glass component and a Ru-based oxide which is a conductive material. Examples of the Ru-based oxide include CaRuO ₃ , SrRuO ₃ , BaRuO ₃ , RuO ₂ , Bi ₂ Ru ₂ O _{7 and the} like. The ratio between the glass component and the conductive material may be set according to a desired resistance value. When the ratio of the glass component increases, the resistance value increases, and when the ratio of the glass component decreases, the resistance value decreases.

On the other hand, as the glass component constituting the resistor layer 4, it is necessary to use a glass component excellent in plating solution resistance. As a result of various studies, the inventors have come to the conclusion that a glass component having the following composition is effective in obtaining plating solution resistance.
BaO 20 mass%-35 mass%
B ₂ O ₃ 10 wt% to 20 wt%
SiO ₂ 30% by mass to 40% by mass
ZnO 5 mass% to 25 mass%
Alkali metal oxide 10% by mass or less

  The glass component used for the resistor layer 4 has an insulating function of adjusting the resistance value by adjusting the mixing ratio with the conductive material, as well as improved sinterability and adhesion to the base electrode layer 3. Various characteristics are required, such as ensuring the above. The glass component having the above-described composition has the characteristics that it has excellent plating solution resistance while having these characteristics. Therefore, by using the glass component having the above composition for the resistor layer 4, for example, even when the external electrode layer 5 is formed by plating, the glass component does not melt and the fluctuation of the resistance value is suppressed.

  Moreover, the further improvement of the plating solution tolerance of a glass component can be aimed at by including NiO as a glass component which comprises the resistor layer 4. FIG. In this case, NiO may be added to the glass component in advance, or may be derived from the internal electrode layer 22 or the base electrode layer 3. For example, by selecting the firing conditions of the base electrode layer 3 and the resistor layer 4, Ni contained in the internal electrode layer 22 and the base electrode layer 3 is diffused into the resistor layer 4, and the resistor layer 4 is fired. Sometimes it can be NiO.

  The NiO content is preferably 30% by mass or less of the glass component. If the content of NiO contained in the glass component exceeds 30% by mass, the insulating property becomes too high, and the resistance value of the resistor layer 4 may become too large.

  On the resistor layer 4, the external electrode layer 5 is formed as the outermost electrode layer. The external electrode layer 5 functions as an external terminal of the CR composite component 1 and has a small resistance value and good solder wettability in consideration of lead wire attachment and soldering during mounting. Is preferred. Therefore, it is preferable that at least a part (surface portion) of the external electrode layer 5 is formed of a plating film. For example, an Ag paste or the like is fired to form the sintered metal layer 5a, and further plated with Ni, Sn, tin-lead alloy solder or the like to form a plated film 5b. The sintered metal layer 5a and the plated film 5b May be used as the external electrode layer 5. As for the plating film 5b, for example, the inner side can be a Ni plating film and the outer side can be a tin-lead alloy solder plating film. The thickness of the plating film 5b is, for example, about 0.1 μm to 20 μm.

  In the electronic component (CR composite component) of the present embodiment having the above-described configuration, it is possible to realize a highly reliable electronic component with little variation in the resistance value of the resistor layer 4. Next, a method for forming the above-described CR composite component 1 manufacturing method will be described.

  For example, in the CR composite component 1 in which the internal electrode layer 22 is formed of Ni which is a base metal, in order to form the base electrode layer 3 on the multilayer ceramic capacitor 2, first, in the base electrode precursor layer forming step, A base electrode precursor layer is formed on the side surface of a certain multilayer ceramic capacitor 2. The base electrode precursor layer is formed by applying a conductive paste containing a conductive metal material and a glass component to the end face of the multilayer ceramic capacitor 2 using a technique such as dipping or printing.

  Next, the base electrode precursor layer is reduced and fired to form the base electrode layer 3. Since the organic material such as an organic vehicle is contained, the organic matter contained in the base electrode precursor layer is first included in the reduction firing. A binder removal step for decomposing and removing the substrate is performed. The binder removal step may be performed in the atmosphere, for example, at a temperature of about 400 ° C.

After the binder removal step, the base electrode precursor layer is reduced in a reduction treatment step. The reduction treatment is performed by heating to a predetermined reduction temperature in an atmosphere containing a reducing gas such as hydrogen. In this reduction treatment step, when hydrogen reduction treatment is performed, the sample is set in a reaction furnace capable of atmospheric firing at room temperature and sealed. The atmosphere in the furnace is replaced with a hydrogen-containing atmosphere, for example, 95% N ₂ -5% H ₂ mixed gas (N ₂ -5% H ₂ ), the temperature is raised to a predetermined temperature, and after a predetermined time, the temperature is lowered. The hydrogen concentration may be set to about 0.1% to 10%. Although the internal electrode layer 22 formed of the base metal is oxidized by the previous binder removal step, it is reduced by performing this reduction treatment step, and the original function of the internal electrode layer 22 is restored.

  In addition, it is preferable that the reduction temperature in the said reduction process process shall be 250 to 500 degreeC. If the reduction temperature is less than 250 ° C., the reduction of the internal electrode layer 22 may not proceed sufficiently. On the contrary, if the reduction temperature exceeds 500 ° C., the dielectric ceramic layer 21 constituting the multilayer ceramic capacitor 2 may be reduced and the characteristics may be deteriorated.

  After the reduction treatment step, a baking step is performed. This baking process is a process for baking the base electrode precursor layer onto the multilayer ceramic capacitor 2 to form the base electrode layer 3. The baking process is performed in an inert gas atmosphere such as a nitrogen atmosphere or an Ar gas atmosphere. The temperature may be set to a temperature necessary for baking, and is preferably set to, for example, 850 ° C. or higher in order to make the formed base electrode layer 3 dense.

  The reduction firing process for forming the base electrode layer 3 includes the above-described three processes of the binder removal process, the reduction process, and the baking process. After these processes, the formation of the resistor layer 4 and the external electrode layer 5 is performed. I do.

  In the resistor precursor layer forming step, the resistor paste is printed to form a resistor precursor layer, and the resistor layer 4 is formed by firing in the firing step. As the resistor paste, a resistor paste including a conductive material (Ru-based oxide or the like) and a glass component is used, and a glass component having the above-described composition is used as the glass component. For example, when a metal glaze containing a Ru-based oxide is used as a resistance material, firing is performed in the atmosphere at a temperature of about 850 ° C. in order to prevent reduction of the Ru oxide. Thereby, the resistor layer 4 is baked and formed on the base electrode layer 3. At this time, since the base electrode layer 3 formed by the reduction firing process functions as an oxygen permeation preventive film, oxygen in the atmosphere does not enter and oxidize the internal electrode layer 22.

  After the formation of the resistor layer 4, a conductive paste such as an Ag paste is applied by a technique such as dipping in the external electrode precursor layer forming step, and the external electrode layer 5 is formed by baking this in the baking step. The baking process may be performed at a temperature of about 750 ° C. in the atmosphere, for example. A plating film is formed outside the external electrode layer 5. Although the plating film is formed by wet plating, even if the resistor layer 4 is formed and then immersed in the plating solution, the glass component is prevented from being melted, and the resistance value fluctuation of the resistor layer 4 is minimized. It is possible to suppress.

  The above is the basic method for manufacturing a CR composite part. In the above-described manufacturing method, even when NiO is contained in the resistor layer 4, it is possible to cope with simple process changes. As a specific method for adding NiO to the resistor layer 4, first, a method of adding NiO to the resistor paste used when forming the resistor layer 4 can be mentioned. In this case, when adjusting the glass component, it may be added as one of the oxide components constituting the glass, or separately from the glass component in the form of a single oxide (or in the form of metal Ni) to the resistor paste. May be added. When added in the form of metallic Ni, it is oxidized into NiO when the resistor layer 4 is fired.

  Second, Ni constituting the internal electrode layer 22 of the multilayer ceramic capacitor 2 can be diffused into the resistor layer 4 to form NiO. In this case, Ni in the internal electrode layer 22 is diffused into the base electrode layer 3 by adjusting the firing conditions of the base electrode layer 3 so that Ni exists on the surface of the base electrode layer 3. For example, the Ni of the internal electrode layer 22 can be diffused to the surface of the base electrode layer 3 by lengthening the holding time at the ultimate temperature during the firing. After confirming that Ni is present on the surface of the base electrode layer 3, the resistor layer 4 is formed by baking. This makes it possible to introduce NiO into the resistor layer 4. The presence of Ni on the surface of the base electrode layer 3 can be easily performed using a well-known analysis technique, and can be grasped by, for example, fluorescent X-ray analysis. If conditions under which Ni is present on the surface of the base electrode layer 3 can be confirmed, the base electrode layer 3 may be fired under those conditions thereafter.

  Third, Ni can be added to the conductive material of the base electrode layer 3 and diffused into the resistor layer 4. If the base electrode layer 3 contains Ni, Ni diffuses into the resistor layer 4 when the resistor layer 4 is fired, and is oxidized by firing to become NiO.

  Hereinafter, specific examples of the present invention will be described based on experimental results.

A conductive paste using an AgPd alloy (containing 30% by mass of Pd) as a conductive metal material is printed on the base electrode forming portion of a chip capacitor (capacitance 1 μF ± 20%) having a Ni internal electrode, which is a base metal, and removed at 350 ° C. in the atmosphere. Binder went. Further, hydrogen reduction treatment was performed at 320 ° C., and baking was performed at 950 ° C. in nitrogen to form a base electrode layer. The ratio of the glass component contained in the conductive paste was 10% by mass. Next, a resistor paste (Ru-based oxide metal glaze paste) was printed on the AgPd alloy electrode (underlying electrode layer) and fired at 850 ° C. in the atmosphere. CaRuO ₃ was used as the conductive material of the resistor paste, and the ratio of the glass component to the conductive material was 80:20 (volume ratio). Further, an Ag paste was applied and baked on the resistor layer to form an Ag sintered layer, and an Ni plated film and an Sn plated film were formed on the Ag sintered layer by a wet plating method.

  The composition of the glass component contained in the resistor paste was changed as shown in Table 1 to prepare various samples (Sample 1 to Sample 25). In Table 1, a component outside the composition range defined in the present invention is marked with *. In Samples 1 to 10, any component is out of the composition range defined in the present invention and corresponds to a comparative example. In Samples 22 to 25, NiO is included in the resistor layer by changing the baking condition of the base electrode layer. The changed firing condition is a holding time (stable time) after reaching a predetermined firing temperature (950 ° C.).

  ESR and resistance change rate were measured for these samples. The results are shown in Table 1.

  As apparent from Table 1, the rate of change in resistance is greatly suppressed by setting the composition of the glass component contained in the resistor layer within the composition range defined in the present invention. When NiO was contained in the resistor layer, the rate of change in resistance was further suppressed, and the rate of change in resistance was almost zero. On the other hand, in the samples 1 to 10 in which the composition of the glass component contained in the resistor layer is out of the composition range defined in the present invention, the resistance change rate is a large value.

It is a schematic sectional drawing which shows an example of CR composite component.

Explanation of symbols

1 CR composite component, 2 multilayer ceramic capacitor, 3 ground electrode layer, 4 resistor layer, 5 external electrode layer, 21 dielectric ceramic layer, 22 internal electrode layer

Claims (9)

An electronic component in which a resistor layer and an external electrode are formed on a base electrode of a multilayer ceramic capacitor,
The resistor layer includes a glass component, and the composition of the glass component is
BaO 20 mass%-35 mass%
B ₂ O ₃ 10 wt% to 20 wt%
SiO ₂ 30% by mass to 40% by mass
ZnO 5 mass% to 25 mass%
An electronic component, wherein the alkali metal oxide is 10% by mass or less. 2. The electron according to claim 1, wherein the resistor layer contains one or more selected from CaRuO ₃ , SrRuO ₃ , BaRuO ₃ , RuO ₂ , and Bi ₂ Ru ₂ O ₇ as a conductive material. parts.   The electronic component according to claim 1, wherein the glass component contains NiO, and the content of NiO is 30% by mass or less of the glass component.   4. The electronic component according to claim 1, wherein at least one of the internal electrode of the multilayer ceramic capacitor and the base electrode contains Ni. 5.   The electronic component according to claim 1, wherein at least a part of the external electrode is formed of a plating film. A method of manufacturing an electronic component in which a resistor layer and an external electrode are formed on a base electrode of a multilayer ceramic capacitor,
The method of manufacturing an electronic component, wherein the resistor layer is coated with a resistor paste containing a glass component having the following composition and fired in the air.
BaO 20 mass%-35 mass%
B ₂ O ₃ 10 wt% to 20 wt%
SiO ₂ 30% by mass to 40% by mass
ZnO 5 mass% to 25 mass%
Alkali metal oxide 10% by mass or less   7. The resistor layer according to claim 6, wherein when the internal electrode of the multilayer ceramic capacitor contains Ni, the resistor layer is formed thereon after forming the base electrode so that Ni is present on the surface. Manufacturing method of electronic components.   7. The method of manufacturing an electronic component according to claim 6, wherein after forming a base electrode containing Ni, the resistor layer is formed thereon.   9. The method of manufacturing an electronic component according to claim 6, further comprising a plating step for forming an external electrode after forming the resistor layer.

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