JPH11121276A - Electronic component and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component which is manufactured in a simple process at low cost and whose resistance is easily controlled, and a manufacturing method therefor. SOLUTION: This electronic component is a laminate formed of dielectric layers and internal electrodes which are laminated alternately and the internal electrodes are connected electrically to a terminal electrode formed at the end of the laminate and an intermetallic compound of the conductive metal of a terminal electrode and Sn is formed on the surface of the terminal electrode. The electronic component is manufactured by plating the surface of the terminal electrode with Sn so as to form a Sn film and then having the Sn diffuse into the terminal electrode through heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CR composite electronic component in which a resistance or impedance element is added to a multilayer capacitor having a nonmagnetic ceramic dielectric layer.

[0002]

2. Description of the Related Art Conventionally, switching power supplies and DC-DC converters have been used as power supplies in many electronic devices. These power supply capacitors include a power supply bypass capacitor. For the power supply bypass capacitor, a low-capacity multilayer ceramic capacitor and a high-capacity electrolytic capacitor such as aluminum or tantalum have been used according to the power supply capacity, switching frequency, and circuit parameters such as a smoothing coil used in combination. Was. By the way, in recent multilayer ceramic capacitors, the capacitance of multilayer ceramic capacitors has become equivalent to that of electrolytic capacitors with the progress of thinning of dielectrics and internal conductors and development of lamination technology. Attempts have been made to replace them with capacitors. However, when the multilayer ceramic capacitor is replaced with an electrolytic capacitor, the impedance of the multilayer ceramic capacitor in the operating frequency band is too low, that is, the equivalent series resistance (ESR) is too low, so that the step voltage of the input voltage of the three-terminal regulation changes. As a result, the waveform of the output power is disturbed. When an electrolytic capacitor is used, although the impedance is larger than that of the multilayer ceramic capacitor, heat is easily generated because the impedance is too large, and the smoothness of the power supply line is also deteriorated.

Therefore, a CR composite component has been proposed in which a resistance component is added to a normal multilayer ceramic capacitor. For example, JP-A-55-82430 and JP-A-3-20
In JP-A-32020 and JP-A-5-135903, a resistor is formed on the outer surface of a multilayer ceramic capacitor. However, the chip components manufactured by these methods cannot be plated in this state, so that the terminal components are directly soldered.
However, in this case, the soldering is not so good, and the current situation is that it does not reach plating. When plating, to protect the resistor on the outer surface from the plating solution,
It was necessary to cover the resistor with a so-called coating material such as resin or glass. This method has problems that the number of steps is increased and that a resistor is cracked depending on a coating material. When glass is used as the coating material, the resistor and the glass of the coating material react by heat treatment during coating,
A change in the resistance value occurs. Further, when the CR composite chip is mounted on a substrate or the like, the surface on which the resistor is formed must always be the upper surface. This is because, if the resistor is grounded on the substrate surface, a crack or the like occurs in the resistor.

Further, Japanese Patent No. 2578264 discloses a CR composite electronic component in which a metal oxide film is formed on the surface of an external electrode to obtain a desired equivalent series resistance. However, in the manufacturing method described in the example of the publication, a metal oxide film is formed by heating a Ni terminal electrode, and the resistance value is adjusted by barrel polishing. It is done by. In this method, it is difficult to obtain a desired resistance value, the adjustment of the resistance value is complicated, and the mass productivity is not excellent. Further, a Ni layer is further provided on the formed metal oxide film by electroless plating. In this method, it is necessary to provide a mask or the like so that plating does not adhere to portions other than the terminal electrode portion. Becomes very complicated. Further, the adhesion between the plated film and the metal oxide film is very brittle, and when a lead wire is provided on the Ni plating film, the lead wire is easily peeled off.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances. An Sn film is formed on the surface of a terminal electrode formed on a multilayer ceramic capacitor, and the Sn film is formed on the terminal electrode by heat treatment. By diffusing into
n forms an intermetallic compound having a relatively high resistance with the terminal electrode component. The intermetallic compound can function as a resistor. Also, an electrolytic plating film can be formed on this,
E to be a mounted component (SMD) that does not have the direction of the chip
An electronic component with easy SR control and a method for manufacturing the same can be realized.

[0006]

This object is achieved by the following (1) to (6).

(1) Dielectric layers and internal electrodes are alternately laminated to form a laminate, and the internal electrodes are electrically connected to terminal electrodes formed at the ends of the laminate. An electronic component, wherein an intermetallic compound of a conductive metal of the terminal electrode and Sn is formed on a surface of the terminal electrode.

(2) The conductive material of the terminal electrode is Cu,
Ni or a Cu—Ni alloy, wherein the intermetallic compound with Sn is Cu ₃ Sn, Cu ₆ Sn
₅ , at least one selected from Ni ₃ Sn and Ni ₃ Sn ₄
The electronic component according to (1), wherein the electronic component comprises at least one kind.

(3) The equivalent circuit is CR or (LC) R
The electronic component according to (1) or (2), including a series circuit.

(4) The electronic component according to (1) to (3), wherein the conductive material of the internal electrode contains Ni.

(5) An electronic component, wherein the electronic component according to (1) to (4) is plated.

(6) The method for manufacturing an electronic component according to (1) to (5), wherein after forming an Sn film on the surface of the terminal electrode by plating, Sn is diffused into the terminal electrode by heat treatment.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below.

According to the present invention, there is provided a method of manufacturing a potential component capable of increasing the resistance of a terminal electrode and having the function of a resistance at the same time that the terminal electrode serves as a conductor and thereby control the ESR. Electronic components. The configuration is such that in a multilayer chip capacitor in which dielectric layers and internal electrode layers are alternately stacked, an intermetallic compound layer of a conductive metal contained in the terminal electrode and Sn is uniformly formed on the surface of the terminal electrode. Is what you do. The resistance of the thus formed intermetallic compound is relatively high, and by forming this in a layer on the terminal electrode surface, the CR or (L
C) An R series circuit is easily obtained.

Further, it is preferable to form a plating film on the intermetallic compound in order to improve solder wettability and solder erosion.

Although the conductive metal of the terminal electrode is not particularly limited, it is preferable to use Cu,
A material mainly composed of Ni or Cu-Ni alloy is used. In this case, C is used as the intermetallic compound with Sn.
u ₃ Sn, Cu ₆ Sn ₅ , Ni ₃ Sn, and Ni ₃ Sn ₄ are formed.

With such a configuration, it is possible to obtain a CR composite electronic component to which ESR is added. The ESR is not particularly limited, but is about 1 to 2000 mΩ, preferably 10 to 1000 mΩ. By having the ESR in this range, sufficient performance can be exhibited as a power supply bypass capacitor of the power supply circuit.

Next, a method for manufacturing an electronic component according to the present invention will be described.

In the electronic component of the present invention, a green chip is produced by a normal printing method or a sheet method using a paste,
After firing, a terminal electrode is formed. Thereafter, a Sn film is formed on the surface of the terminal electrode, and an intermetallic compound of the conductive material of the terminal electrode and Sn is formed by heat treatment. If necessary,
A plating film is formed thereon.

<Paste for Dielectric Layer> The dielectric material constituting the dielectric layer is not particularly limited.
Although various dielectric materials may be used, for example, titanium oxide, a titanate-based composite oxide, or a mixture thereof is preferable. As the titanium oxide type, if necessary, Ni
TiO ₂ containing O, CuO, Mn ₃ O ₄ , Al ₂ O ₃ , MgO, SiO _2, etc.
Barium titanate Ba is used as the titanate-based composite oxide.
TiO _{3 and the} like. The atomic ratio of Ba / Ti is 0.9
About 5 to 1.20 is good, the BaTiO _3, MgO,
_{CaO, Mn 3 O 4, Y} 2 O 3, V 2 O 5, ZnO, Zr
O ₂ , Nb ₂ O ₅ , Cr ₂ O ₃ , Fe ₂ O ₃ , P ₂ O ₅ , Na
₂ O, K ₂ O and the like may be contained in a total amount of about 0.001 to 30 wt%. Further, a glass such as (BaCa) SiO ₂ glass may be contained for adjusting the firing temperature and the coefficient of linear expansion.

The method for producing the dielectric material is not particularly limited.
For example, when a titanate-based oxide and barium titanate are used, a method of mixing a subcomponent material with hydrothermally synthesized BaTiO ₃ can be used. BaCO ₃ and Ti
A dry synthesis method in which a mixture of O ₂ and the auxiliary component raw material is calcined to cause a solid phase reaction may be used. Further, a mixture of a precipitate obtained by a coprecipitation method, a sol-gel method, an alkali hydrolysis method, a precipitation mixing method, and the like and a subcomponent material may be calcined to synthesize.
In addition, as an auxiliary component, an oxide or various compounds that become an oxide upon firing, for example, at least one of a carbonate, an oxalate, a nitrate, a hydroxide, an organometallic compound, and the like can be used.

The average grain size of the dielectric material may be determined according to the average grain size of the target dielectric layer.
A powder having an average particle diameter of about 0.3 to 1.0 μm is used.

The dielectric paste is produced by kneading a dielectric material and an organic vehicle.

The organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from ordinary various binders such as ethyl cellulose. The organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, and toluene according to a printing method, a sheet method, and a method to be used.

The thickness of one dielectric layer is not particularly limited, but is usually about 5 to 20 μm. The number of stacked dielectric layers is usually about 2 to 300.

<Paste for Internal Electrode> Although the conductive material of the paste for internal electrode is not particularly limited, Ag, Pd, Pt,
It is preferable that it be made of at least one selected from Ni, Cu, and Au. In addition, by using a material having reduction resistance as the dielectric layer constituting material, an inexpensive base metal can be used. Therefore, Ni or Ni alloy is particularly preferable as the conductive material. As the Ni alloy, Mn,
One or more elements selected from Cr, Co, Al, etc. and N
i is preferable, and the Ni content in the alloy is 95 wt%.
It is preferable that it is above. In addition, various trace components such as P may be contained in Ni or Ni alloy in an amount of about 0.1 wt% or less.

The above-mentioned organic vehicle is adjusted by kneading the above-mentioned various conductive metals and alloys, or the above-mentioned various oxides, organometallic compounds, resinates, etc. which become the above-mentioned conductive materials after firing.

The thickness of the internal electrode layer may be appropriately determined according to the intended use, but is usually preferably about 0.5 to 5 μm.

<Paste for Terminal Electrode> The paste for terminal electrode is composed of a conductive material, glass frit, and an organic vehicle. The conductive material of the terminal electrode paste is Ag, Au, P
At least one is selected from t, Pd, Cu, and Ni. Preferably, Cu, Ni, or an alloy thereof is used because it is inexpensive, and Cu is more preferable. A sintering aid or a glass frit is added to these conductive materials to ensure adhesion to the chip body. The average particle size of the conductive material is 0.01 to 10 μm. When the particle size is smaller than this, the conductive material particles are strongly agglomerated, and the terminal electrode is easily cracked during application, drying, or firing of the terminal electrode paste. Becomes difficult. The average particle size of the glass frit is 0.01 to 30 μm. If the particle size is smaller than this, cracks of the glass may be caused. If the particle size is larger than this, the dispersion of the glass becomes worse, and the adhesion between the terminal electrode and the element body is reduced.

The conductive material and the glass frit are dispersed in a vehicle to obtain a terminal electrode paste.

The composition of the glass frit is not particularly limited, but any material may be used as long as the terminal electrode must be fired in a neutral or reducing atmosphere, and the function of the glass can be achieved even in such an atmosphere. For example, one or two or more of glass frit selected from silicate glass, borosilicate glass, and alumina silicate glass are used, and if necessary, CaO, SrO, BaO, MgO, Zn
A mixture of additives such as O, PbO, Na ₂ O, K ₂ O, and MnO ₂ so as to have a predetermined composition ratio may be used.
The content of glass is not particularly limited, but is usually about 0.5 to 15% by weight based on the metal component.

As the organic vehicle, those described above may be used.

<Content of Organic Vehicle> The content of the organic vehicle in each of the above-mentioned pastes is not particularly limited. If the usual content, for example, the binder is about 1 to 5 wt% and the solvent is 10 to 50 wt%, Good. Further, each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like, as necessary. The total content of these is preferably set to 10 wt% or less.

<Preparation of Green Chip> When a printing method is used, a paste for a dielectric layer and a paste for an internal electrode are printed on a substrate such as PET. These are alternately stacked, thermocompression bonded, cut into a predetermined shape and made into chips,
Peeled from the substrate to form a green chip.

When the sheet method is used, a green sheet is formed by using a dielectric layer paste, an internal electrode layer paste is printed on the green sheet, and these are alternately and repeatedly laminated to form a predetermined shape. Into green chips.

<Binder Removal Step> The conditions for the binder removal treatment performed before firing may be ordinary conditions. However, when a base metal such as Ni or a Ni alloy is used as the conductive material of the internal electrode layer, the following conditions are particularly preferred. It is preferable to carry out under conditions.

Heating rate: 5 to 300 ° C./hour, especially 10
１００100 ° C./hour Holding temperature: 200 to 400 ° C., especially 250 to 300 ° C. Temperature holding time: 0.5 to 24 hours, especially 5 to 20 hours Atmosphere: in air <Firing step> It may be appropriately selected according to the type of the conductive material of the paste for the internal electrode. However, when a base metal such as Ni or a Ni alloy is used as the conductive material, the firing atmosphere is mainly composed of N ₂ , and H ₂ is 1 to ₂ . 1
A mixture of 0% and H ₂ O gas obtained by a steam pressure at 10 to 35 ° C. is preferable. Oxygen partial pressure is 1
The pressure is preferably from 0 ^-8 to 10 ^-12 atm. If the oxygen partial pressure is less than the above range, the conductive material of the internal electrode may be abnormally sintered and may be interrupted. If the oxygen partial pressure exceeds the above range, the internal electrodes will be oxidized.

The holding temperature during firing is from 1100 to 1400
° C, particularly preferably 1200 to 1300 ° C.
When the holding temperature is lower than the above range, the densification is insufficient, and when the holding temperature is higher than the above range, the internal electrode is easily broken. Further, the temperature holding time during firing is 0.5 to 8 hours,
Particularly, 1 to 3 hours is preferable.

<Annealing Step> When firing in a reducing atmosphere, the multilayer ceramic capacitor is preferably annealed. Annealing is a process for reoxidizing the dielectric layer, which can significantly increase the accelerated life of the insulation resistance.

The oxygen partial pressure of the annealing atmosphere is preferably 10 ^-6 atm or more, particularly preferably 10 ^-6 to 10 ^-8 atm.
When the oxygen partial pressure is less than the above range, it is difficult to reoxidize the dielectric layer, and when the oxygen partial pressure exceeds the above range, the internal electrode is oxidized.

The holding temperature at the time of annealing is preferably 1100 ° C. or less, particularly preferably 500 to 1000 ° C. When the holding temperature is less than the above range, the oxidation of the dielectric layer becomes insufficient, and the accelerated life of the insulation resistance tends to be shortened,
If the ratio exceeds the above range, the internal electrodes are oxidized, and not only the capacity is reduced, but also reacts with the dielectric base material, and the accelerated life is shortened. Note that the annealing step may be configured only by raising and lowering the temperature. In this case, it is not necessary to take a temperature holding time, and the holding temperature is synonymous with the maximum temperature. Further, the temperature holding time is preferably 0 to 20 hours, particularly preferably 2 to 10 hours.
It is preferable to use a humidified N ₂ gas as the atmosphere gas.

In each of the above-described steps of the binder removal treatment, firing and annealing, for example, a wetter may be used to humidify N ₂ , H ₂ , O and a mixed gas. The water temperature in this case is preferably about 5 to 75C.

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

In the case where these steps are continuously performed, the atmosphere may be changed without cooling after the binder removal treatment, and the steps may be performed independently. When performing these continuously, after debinding,
It is preferable that the atmosphere is changed without cooling, then the temperature is raised to the holding temperature for firing to perform firing, then the cooling is performed, and the annealing is performed by changing the atmosphere when the temperature reaches the holding temperature in the annealing step.

In the case where these steps are performed independently, in the binder removal treatment step, the temperature is raised to a predetermined holding temperature, held for a predetermined time, and then lowered to room temperature. At that time, the debinding atmosphere is the same as in the case where the debinding is performed continuously. Further, in the annealing step, the temperature is raised to a predetermined holding temperature, held for a predetermined time, and then lowered to room temperature. The annealing atmosphere at that time is the same as in the case of performing the annealing continuously. Also, the binder removal step and the firing step are performed continuously,
Only the annealing step may be performed independently, or only the binder removal step may be performed independently, and the firing step and the annealing step may be performed continuously.

<Step of Applying Terminal Electrode Layer Paste> The terminal electrode paste prepared as described above is applied to a sintered chip. The application step is not particularly limited, but may be a dip method or the like. The amount of the terminal electrode paste applied is not particularly limited, and may be appropriately adjusted depending on the size of the sintered chip to be applied, but is usually about 5 to 100 μm. After applying the terminal electrode paste, it is dried. Drying is preferably performed at about 60 to 150 ° C. for about 10 minutes to 1 hour.

<Baking of Terminal Electrode Layer> After the paste for the terminal electrode layer is applied and dried as described above, baking (firing) on the chip body is performed. Baking conditions, for example, a neutral atmosphere of N ₂ or is preferably set to 0 to 1 hour or so at 600 to 1000 ° C. at a reducing atmosphere such as a mixed gas of N ₂ and H _2.

<Formation of Intermetallic Compound Layer> An intermetallic compound of a conductive metal of the terminal electrode and Sn is formed on the surface of the terminal electrode. In this method, for example, a uniform intermetallic compound layer can be obtained by forming a Sn film by a wet plating method and causing Sn to diffuse into a terminal electrode by heat treatment.

The thickness of the Sn film is not particularly limited, but is usually about 0.1 to 20 μm. The heat treatment conditions are not particularly limited, but are usually about 120 to 200 ° C.

The intermetallic compound formed particularly has a terminal electrode of C
When u, it is at least one of Cu ₃ Sn and Cu ₆ Sn ₅ , and when it is Ni, it is at least one of Ni ₃ Sn and Ni ₃ Sn ₄ , and Cu—Ni
They coexist in the alloy system.

The thickness of the intermetallic compound layer is not particularly limited, but is usually about 0.1 to 20 μm.

<Plating Layer> If necessary, Ni, Sn,
A metal plating layer of solder or the like, in particular, Ni or Sn can be provided. Providing the metal plating layer improves solder wettability and solder erosion. The metal plating layer may be provided as one layer or two or more layers.
Those formed in layers in the order of i and Sn are preferred.

By the method as described above, a CR composite electronic component to which a preferable range of ESR is added can be obtained.

[0054]

The present invention will be described more specifically with reference to the following examples.

Example 1 Ba was used as a main material of the dielectric layer.
CO ₃ (average particle size: 2.0 μm) and TiO ₂ (average particle size: 2.0 μm) were prepared. The atomic ratio of Ba / Ti is 1.00. In addition to this, 0.2 wt% of MnCO ₃ as an additive to BaTiO ₃ and MgC
O ₃ and 0.2 wt%, 2.1 wt% of Y ₂ O _3, (Bac
a) 2.2 wt% of SiO ₃ was prepared. Each raw material powder was mixed with an underwater ball mill and dried. The obtained mixed powder was calcined at 1250 ° C. for 2 hours. This calcined powder was pulverized with an underwater ball mill and dried. To the obtained calcined powder, an acrylic resin as an organic binder and methylene chloride and acetone as an organic solvent were added and mixed to obtain a dielectric slurry. The obtained dielectric slurry was used as a dielectric green sheet using a doctor blade method.

Ni powder (average particle size: 0.8 μm) was prepared as an internal electrode material, and ethyl cellulose as an organic binder and terpineol as an organic solvent were added thereto and kneaded using a three-roll mill. And

As a terminal electrode material, 7 wt% of strontium borosilicate glass was prepared with respect to Cu powder (average particle size: 0.5 μm) and Cu powder, and an acrylic resin as an organic binder and terpineol as an organic solvent were added thereto. And kneaded using a three-roll mill to obtain a terminal electrode paste.

In order to obtain a predetermined thickness, several green sheets were laminated on the dielectric, an internal electrode paste was printed thereon by a screen printing method, and a green sheet was laminated thereon, and thus the internal electrodes were printed. Sheets and green sheets are alternately stacked, and finally, a predetermined number of green sheets are stacked and thermocompression bonded, and a predetermined chip shape is fired to a height of 3.2 × 1.6 × 1.0 mm after baking. To obtain a green chip.

The obtained green chip was moistened with N ₂ +
In a H ₂ (N ₂ 3%) reducing atmosphere, baking is carried out at 1300 ° C. for 3 hours, and further kept at 1000 ° C. for 2 hours in a humidified N ₂ oxygen partial pressure of 10 ⁻⁷ atm. I got a body. A terminal electrode paste mainly composed of Cu was applied to both ends of the obtained sintered body, dried, and baked at 770 ° C. for 10 minutes in N ₂ to form a terminal electrode.

An Sn film is formed on the terminal electrodes by electrolytic plating.
μm, then 120, 150, 180, 200 ° C
For 10 hours to form an intermetallic compound on the surface of the terminal electrode. The intermetallic compound is Cu ₆ Sn _{5 in} the sample at 200 ° C.
And Cu ₃ Sn were generated, and the other samples were Cu ₃ S
X was confirmed by X-ray diffraction.

Further, Ni plating and solder plating were performed to obtain an electronic component. The capacitance of the obtained sample is 1 μF
Met. Table 1 shows the results obtained by measuring the thickness and ESR of these electronic components. The thickness was measured by arbitrarily polishing 10 samples and observing them by SEM.
Their average was used. For the ESR, an average value of 40 samples was used.

[0062]

[Table 1]

As is clear from Table 1, the ESR is higher than that of the conventional capacitor, and it can be seen that the ESR can be controlled by the heat treatment conditions.

The electronic parts having these ESRs are DC
-When used as a bypass capacitor of a DC converter and operated while changing the switching frequency from 100 kHz to 40 MHz, it was confirmed that the operation was normal without causing a voltage fluctuation phenomenon of the input voltage due to oscillation or the like.

[0065]

As described above, according to the present invention, by forming an intermetallic compound layer on the surface of a terminal electrode, an electronic component having a simple manufacturing process, low production cost, and easy control of resistance value can be obtained. The manufacturing method can be realized.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasunori Tokuoka 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (6)

[Claims] An electronic device in which dielectric layers and internal electrodes are alternately laminated to form a laminate, and wherein the internal electrodes are electrically connected to terminal electrodes formed at ends of the laminate. An electronic component, wherein an intermetallic compound of a conductive metal of the terminal electrode and Sn is formed on the surface of the terminal electrode. 2. The conductive material of the terminal electrode is Cu, Ni,
Alternatively, it is mainly composed of a Cu—Ni alloy, and the intermetallic compound with Sn is Cu ₃ Sn, Cu ₆ Sn ₅ , N
i ₃ Sn, electronic component according to claim 1, characterized in that it consists of at least one selected from Ni ₃ Sn _4. 3. The electronic component according to claim 1, wherein the equivalent circuit includes a CR or (LC) R series circuit. 4. The electronic component according to claim 1, wherein the conductive material of the internal electrode contains Ni. 5. An electronic component, wherein the electronic component according to claim 1 is plated. 6. The plating of Sn on the surface of the terminal electrode by plating.
6. The method according to claim 1, wherein after forming the film, Sn is diffused into the terminal electrode by heat treatment.