JP2008226670A - Copper-nickel-containing paste, laminated ceramic electronic component, and manufacturing method of copper-nickel-containing paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external electrode paste formed into a thin film in a micron range by using a copper-nickel-containing paste without using an electrode paste using metal fine particles. <P>SOLUTION: Copper acetate (CuAc) and tetraethylene glycol (TEG) are mixed with each other, agitated over a long time until a viscosity increase phenomenon is exhibited, and heat-treated, whereby a copper precursor is provided. Similarly, nickel acetate (NiAc) and tetraethylene glycol (TEG) are mixed with each other, agitated over a long time until a viscosity increase phenomenon is exhibited, and heat-treated, whereby a nickel precursor is provided. The copper precursor and the nickel precursor are mixed with each other, whereby a copper-nickel-containing paste is provided. In addition, the copper-nickel-containing paste is applied to a substrate, and heat-treated in a nitrogen gas flow, whereby a copper-nickel alloy film is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Cu-Ni-containing paste for external electrodes of a multilayer ceramic capacitor (hereinafter referred to as MLCC). Moreover, this invention relates to the manufacturing method of the MLCC external electrode formed using this paste, the MLCC provided with this external electrode, and the copper-nickel containing paste for the external electrodes of a laminated ceramic component.

Multilayer ceramic parts including MLCC are indispensable as electronic parts, and the number of them reaches a production volume of 100 billion pieces / month worldwide. Currently, as the production volume further expands, miniaturization, high functionality, high performance, and high reliability of products are required.
The present invention is intended to be used as an external electrode of a multilayer ceramic component including MLCC, and realizes thinning, high density uniformity, and high reliability of the external electrode.
The current MLCC electrode configuration uses Ni metal as the internal electrode and Ni or Cu as the external electrode. In forming these electrodes, a paste is obtained by mixing and dispersing a polymer material consisting of metal fine particles, a solvent and a binder, then forming with a coating technique such as printing, and firing to form an external electrode. and so on.

When trying to achieve further miniaturization, higher functionality, higher performance, and higher reliability of multilayer ceramic parts including MLCC, a thin, high-density, defect-free metal film is formed on both the internal and external electrodes. Things are needed. However, in the electrode formation using the paste electrode solution based on the metal fine particles, it is difficult to form a submicron thin metal film having a thickness of 1 μm or less.
Furthermore, in the configuration of the internal electrode Ni metal and the external electrode Cu, mass transfer occurs in the alloying process during sintering, and voids are generated in the MLCC external electrode and internal electrode joint, causing a decrease in reliability. It has become. The main cause of the decrease in reliability is the deterioration of insulation resistance caused by the wet plating solution entering the generated voids in the production process. In order to cover this defect, it is avoided by a method of forming a thick external electrode. Therefore, in the formation of the internal electrode, the external electrode has a thickness of 50 to 100 μm with respect to a thickness of 2 μm or less.
Japanese Patent Laid-Open No. 2005-340666 JP 2004-265826 A JP 2006-286145 A Japanese Patent Laid-Open No. 10-072673 JP-A-11-39944 Masahiro Kitamura, Michinori Komagata, Hideki Takamatsu, Ken-Ichi Suzuki; Proceedings of IPACK'01, The Pacific Rim / ASME Electronic Packaging Technical Conference and Exhibition July8-13,2001, Kauai.Hawaii, USA.pp 207-211

The problem-solving means of the present invention is to provide an external electrode paste that becomes a thin film of a micron unit using a copper-nickel-containing paste without using an electrode paste using metal fine particles.
Furthermore, this invention is providing the laminated ceramic component containing MLCC formed using this paste.

It is a means by a metal paste which consists of copper acetate and nickel acetate as an organometallic compound and uses tetraethylene glycol (TEG) as a medium.
Specifically, a copper-containing precursor obtained by mixing and dispersing copper acetate and tetraethylene glycol (TEG) and a nickel-containing precursor obtained by mixing nickel acetate and tetraethylene glycol (TEG) are individually provided. Create and add thickening and crystal water removal processes by heat treatment, respectively, and then mix and disperse copper-containing precursor and nickel-containing precursor as stable copper-containing precursor and nickel-containing precursor A paste containing copper-nickel is used. Furthermore, a multilayer ceramic component including a multilayer ceramic capacitor (MLCC) including an external electrode used as a Cu-Ni alloy by applying a copper-nickel-containing paste to a multilayer ceramic electronic component such as a ceramic multilayer capacitor and firing the paste. .

The following effects can be obtained by generating the external electrode with this process.
(1) [Formation of thin-film alloy electrode] By forming a film with a metal paste using an organometallic compound and tetraethylene glycol (TEG), a Cu-Ni alloy of micron to submicron (1 μm or less) without using a vacuum film forming technique, Thin film external electrodes can be formed. The effective utilization rate of the metal material can be reduced to 1/10 or less.
(2) [Improvement of reliability] By forming an external electrode to be a Cu-Ni alloy, there is a gap in the joint between the external electrode and the internal electrode of the multilayer ceramic electronic component, such as MLCC, which has occurred in the past, which occurs during sintering. Therefore, the cause of deterioration in reliability is solved.
(3) [Shortening of process] The manufacturing process can be shortened from the process of forming the external electrode by the electrode paste using the metal fine powder.

The basic configuration of the present invention is as follows.
(1) Using Cu-Ni component as an external electrode material, copper acetate and nickel acetate as organometallic compounds.
(2) Use tetraethylene glycol (TEG) as the mixing medium. A mixture comprising copper acetate (CuAc) and nickel acetate (NiAc) as the organometallic compound, tetraethylene glycol (TEG) as the medium, and a molar ratio of the acetate to the medium being 1: 1 to 1: 5 Use that.
(3) Furthermore, the important thing is that a stable copper-containing precursor obtained by heat-treating a mixed dispersion of copper acetate and tetraethylene glycol (TEG) and adding a thickening process and a crystallization water removal process; Heating a mixed dispersion of nickel and tetraethylene glycol (TEG) to individually create a stable nickel-containing precursor obtained by adding a thickening and water removal process.
(4) To obtain a copper-nickel-containing paste prepared by mixing and dispersing a separately prepared stable copper-containing precursor and a stable nickel-containing precursor in a desired ratio.
(5) Further, a copper-nickel-containing paste is applied to the ceramic multilayer capacitor and fired to form an external electrode of a Cu-Ni alloy, and a multilayer ceramic capacitor (MLCC) is obtained.

The "stable precursor" shown here is a uniform dispersion until a thickening phenomenon is observed in the mixed dispersion of copper acetate and tetraethylene glycol (TEG) and the mixed dispersion of nickel acetate and tetraethylene glycol (TEG). This refers to a mixture obtained by dispersing and heating to add a thickening and crystallization removal process.
When a mixture at a stage where the mixing and dispersion time is short and the thickening phenomenon does not occur is used, the metal component becomes an oxide in the sintering process, and it is difficult to form a good electrode film.
Furthermore, when copper acetate, nickel acetate, and tetraethylene glycol (TEG) are mixed together at the same time without going through a stable precursor process, the metal component becomes an oxide during the sintering process, and a good electrode film It is difficult to form.

The wet synthesis process for obtaining a thin layer Cu—Ni alloy for the purpose of forming the external electrode of the multilayer ceramic component in the present invention will be described in more detail by the following examples. FIG. 1 shows the process flow.
On the left side of the flow diagram, copper acetate (CuAc) and tetraethylene glycol (TEG) are mixed, stirred for a long time until a thickening phenomenon is observed, and heat-treated to obtain a copper precursor. On the other hand, on the right side of the flow chart, nickel acetate (NiAc) and tetraethylene glycol (TEG) are similarly mixed, stirred for a long time until a thickening phenomenon is observed, and heat-treated to obtain a nickel precursor.
The copper precursor and the nickel precursor are mixed to obtain a copper-nickel-containing paste. Further, the copper-nickel-containing paste is applied to a substrate and heat-treated in a nitrogen stream to form a copper-nickel alloy film.

  Copper acetate (CuAc) and tetraethylene glycol (TEG) were mixed at a molar ratio of 1: 4, and stirred at room temperature for 120 hours with a magnetic stirrer to obtain a CuAc-TEG mixed dispersion. Similarly, nickel acetate (NiAc) and tetraethylene glycol (TEG) were mixed at a molar ratio of 1: 4, and stirred with a magnetic stirrer at room temperature for 120 hours to obtain a NiAc-TEG mixed dispersion.

  The CuAc-TEG mixed dispersion and the NiAc-TEG mixed dispersion were each heat-treated at 120 ° C. for 1 hour to obtain a copper precursor and a nickel precursor.

  The prepared copper precursor and nickel precursor were mixed in such a ratio that the molar ratio of copper and nickel was 1: 1, and stirred with a magnetic stirrer for 1 hour or more to obtain a copper-nickel-containing paste.

  The copper-nickel-containing paste is applied to a glass rod by dropping the paste into a groove created by sticking a mending tape (thickness: 58 μm) having a size of 5 × 10 mm to a substrate (slide glass). It was carried out by uniformly stretching with. And the paste film | membrane maintained by the magnitude | size of the groove | channel was obtained by peeling off a tape.

  The substrate on which this paste was applied was placed in an infrared reflecting furnace (RHL-E44VHT manufactured by Vacuum Riko Co., Ltd.) and replaced by flowing nitrogen into the quartz reaction tube for 20 minutes, and then in a nitrogen stream (1 liter / minute). The temperature was raised at 120 ° C./min and held at 500 ° C. for 60 minutes to form a copper-nickel alloy film (Cu—Ni film), and then naturally cooled after completion.

The prepared Cu—Ni alloy film was confirmed to have a metallic luster as shown in the photograph of FIG. 2, and the presence of oxide was not confirmed as shown in the X-ray diffraction diagram of FIG.
Moreover, as shown in the FE-SEM photograph of FIG. 4, the dense film formation situation was confirmed. Furthermore, the measurement result with a confocal laser microscope was an average film thickness of 0.75 μm.

  The importance of homogeneous mixing and dispersion of acetate and tetraethylene glycol (TEG) in the synthesis of the thin layer Cu—Ni alloy in the present invention will be explained in more detail by the following examples.

  Copper acetate (CuAc) and tetraethylene glycol (TEG) are mixed at a molar ratio of 1: 4, and stirred for 1, 24, 120 hours at room temperature with a magnetic stirrer to obtain three CuAc-TEG mixed dispersion Cu -1 and Cu-24 and Cu-120 were obtained. Similarly, nickel acetate (NiAc) and tetraethylene glycol (TEG) are mixed at a molar ratio of 1: 4, and the mixture is stirred for 1, 24, 120 hours at room temperature with a magnetic stirrer to mix three NiAc-TEG. Dispersions Ni-1 and Ni-24, Ni-120 were obtained.

  Three CuAc-TEG mixed dispersions and three NiAc-TEG mixed dispersions were respectively heat-treated at 120 ° C. for 1 hour to obtain three copper precursors and nickel precursors, respectively.

  The copper precursor obtained from Cu-1 and the nickel precursor obtained from Ni-1 were mixed at a ratio in which the ratio of copper and nickel was 1: 1, and stirred with a magnetic stirrer for 1 hour or more. A copper-nickel-containing paste Cu-Ni-1 was obtained. In the same manner, Cu-Ni-24 was obtained from Cu-24 and Ni-24, and Cu-Ni-120 was obtained from Cu-120 and Ni-120.

  The copper-nickel-containing paste is applied by hanging a paste in a groove created by pasting a mending tape (thickness 58 μm) with a hole of 5 × 10 mm on a substrate (slide glass), and using a glass rod. Performed by uniformly stretching. And the paste film | membrane maintained by the magnitude | size of the groove | channel was obtained by peeling off a tape.

  The substrate on which this paste was applied was placed in an infrared reflection furnace and replaced by flowing nitrogen into the quartz reaction tube for 20 minutes, and then heated at 120 ° C./minute in a nitrogen stream (1 liter / minute) to 500 ° C. The sample was held for a predetermined time and naturally cooled after completion.

  Table 1 shows the state of three CuAc-TEG mixed dispersions and the copper film synthesized based on them.

同様に、表２には３つのＮｉＡｃ‐ＴＥＧ混合分散体ならびに、それをもとに合成したニッケル膜の状態を記した。

Similarly, Table 2 shows three NiAc-TEG mixed dispersions and the state of a nickel film synthesized based on them.

表３には３つの銅-ニッケル含有ペーストならびに、それをもとに調製した膜について記した。

Table 3 shows three copper-nickel-containing pastes and films prepared based thereon.

撹拌時間を短くして調製した銅-ニッケル含有ペーストＣｕ‐Ｎｉ‐１およびＣｕ‐Ｎｉ‐２４は粘性が低いものであり、それを用いて作成した膜は、片寄りが見られるほか酸化物の形成が確認されたが、撹拌時間を長くして調製した銅‐ニッケル含有ペーストＣｕ‐Ｎｉ‐１２０は粘性が高く、それを用いて作成した膜は均一であり、酸化物の形成が無かった。

The copper-nickel-containing pastes Cu-Ni-1 and Cu-Ni-24 prepared by shortening the stirring time are low in viscosity, and the film made using the paste is not only offset but also has oxides. Although formation was confirmed, the copper-nickel-containing paste Cu-Ni-120 prepared by increasing the stirring time was highly viscous, and the film produced using the paste was uniform and no oxide was formed.

  The thin film Ni-Cu alloy can be synthesized by the copper-nickel-containing paste obtained by mixing and dispersing the copper precursor and the nickel precursor at a predetermined composition ratio according to the present invention. Explained.

  Copper acetate (CuAc) and tetraethylene glycol (TEG) were mixed at a molar ratio of 1: 3, and stirred with a magnetic stirrer at room temperature for 120 hours to obtain a CuAc-TEG mixed dispersion. Similarly, nickel acetate (NiAc) and tetraethylene glycol (TEG) were mixed at a molar ratio of 1: 3, and stirred with a magnetic stirrer at room temperature for 120 hours to obtain a NiAc-TEG mixed dispersion.

  The CuAc-TEG mixed dispersion and the NiAc-TEG mixed dispersion were heat-treated at 120 ° C. for 1 hour to obtain a copper precursor and a nickel precursor.

  The prepared copper precursor and nickel precursor were mixed at a predetermined composition ratio (shown in Table 4) (sample A1 = 2: 1, sample A2 = 1: 1, sample A3 = 1: 2), and magnetized for 1 hour or more. Stirring with a tic stirrer was performed to obtain three copper-nickel-containing pastes.

  The copper-nickel-containing paste is applied with a glass rod by dropping the paste into a groove created by pasting a mending tape (thickness 58 μm) with a hole of 5 × 10 mm on the substrate (slide glass). Performed by uniformly stretching. And the paste film | membrane maintained by the magnitude | size of the groove | channel was obtained by peeling off a tape.

  The substrate coated with this paste was placed in an infrared reflection furnace and replaced by flowing nitrogen into the quartz reaction tube for 20 minutes, and then heated at 120 ° C./minute in a nitrogen stream (1 liter / minute) to 500 ° C. Was held for 10 minutes, and naturally cooled after completion.

  As shown in the photograph of FIG. 5, metallic luster was confirmed in the synthesized Cu—Ni alloy films A1, A2, and A3. In addition, as shown in the X-ray diffraction diagram of the alloy film in FIG. 6, these compositions are similar to the metal ratio of the copper-nickel-containing paste used for the preparation, A1 is a copper-rich composition, A2 is nickel and copper It was confirmed that the composition of almost the same ratio and A3 was a nickel-rich composition.

[Comparative Example 1]
The problems that occur when the synthesis process according to the present invention is not followed will be described in more detail by the following comparative example. FIG. 7 shows the flow of the implementation process.

  NiAc, CuAc, and TEG were mixed at a molar ratio of 1: 1: 4 to obtain a NiAc-CuAc-TEG mixture.

  The NiAc-CuAc-TEG mixture was heated to reflux at 120 ° C. for 1 hour to obtain a copper-nickel-containing paste.

  The copper-nickel-containing paste is applied with a glass rod by dropping the paste into a groove created by pasting a mending tape (thickness 58 μm) with a hole of 5 × 10 mm on the substrate (slide glass). Performed by uniformly stretching. And the paste film | membrane was obtained by peeling off a tape.

  The substrate coated with this paste was placed in a horizontal tube furnace and replaced by flowing nitrogen into the quartz reaction tube for 20 minutes, and then heated up to 500 ° C. at 10 ° C./minute in a nitrogen stream (1 liter / minute). As soon as it arrived, it was allowed to cool naturally.

  The copper-nickel-containing paste prepared by the procedure shown in FIG. 7 was a non-homogeneous mixture having a low viscosity and a size such that the settled particles were visually observed. In addition, as shown in the X-ray diffraction pattern of FIG. 8, the film prepared using this was confirmed to have a Cu—Ni alloy and an oxidized alloy form.

Using the copper-nickel-containing paste for external electrodes produced in Example 1, it was applied to the sintered body of the multilayer ceramic capacitor to be MLCC, and overheated to form Cu-Ni alloy external electrodes.
It was confirmed that the formed external electrode formed a Cu—Ni alloy of 1 μm or less. Thereafter, tin plating was performed, and characteristics evaluation and reliability evaluation as a multilayer ceramic capacitor were performed, and it was confirmed that there was no problem in reliability results.

The copper-nickel-containing paste for external electrodes and the copper-nickel alloy film manufacturing method of the present invention can form micron to submicron (1 μm or less) Cu-Ni alloys and thin film external electrodes in forming MLCC external electrodes. The effective utilization rate of the metal material can be increased.
Further, it is possible to solve the generation of the gap between the external electrode and the internal electrode joint, which causes a decrease in reliability, and to achieve a shortened manufacturing process, which is extremely useful industrially.

It is a flowchart which shows the implementation process of the thin layer Cu-Ni alloy synthesis | combination in this invention. It is a photograph of a Cu-Ni alloy film. It is an X-ray diffraction pattern of a Cu-Ni alloy film. It is a FE-SEM photograph of a Cu-Ni alloy film. It is a photograph (A1, A2, A3) of a Cu-Ni alloy film. It is an X-ray diffraction diagram (A1, A2, A3) of the alloy film. It is a flowchart which shows the implementation process which did not become a favorable Cu-Ni alloy film. FIG. 6 is an X-ray diffraction diagram that does not provide a good Cu—Ni alloy film.

Claims (3)

  Cu-Ni alloy consisting of copper acetate and nickel acetate as the organometallic compound, tetraethylene glycol as the medium, and a mixture of the acetic acid compound and tetraethylene glycol in a molar ratio range of 1: 1 to 1: 5 A copper-nickel-containing paste having a composition range of Cu (1-x) -Nix (excluding X = 1 and X = 0).   A multilayer ceramic electronic component comprising an external electrode that is applied as a Cu-Ni alloy by applying a copper-nickel-containing paste to a multilayer ceramic capacitor and firing it.   Copper-containing precursor obtained by mixing and dispersing copper acetate and tetraethylene glycol, stirring for a long time and heat treatment, and nickel containing obtained by mixing and dispersing nickel acetate and tetraethylene glycol, stirring for a long time and heat treatment A method for producing a copper-nickel-containing paste, wherein a precursor is prepared separately, and the copper-containing precursor and the nickel-containing precursor are mixed and dispersed.

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