JPH1171601A - Powder material and its production - Google Patents

Powder material and its production

Info

Publication number
JPH1171601A
JPH1171601A JP9247608A JP24760897A JPH1171601A JP H1171601 A JPH1171601 A JP H1171601A JP 9247608 A JP9247608 A JP 9247608A JP 24760897 A JP24760897 A JP 24760897A JP H1171601 A JPH1171601 A JP H1171601A
Authority
JP
Japan
Prior art keywords
particles
grain
silicon oxide
powder material
reaction tube
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP9247608A
Other languages
Japanese (ja)
Inventor
Seirai Kuruma
声雷 車
Osamu Sakurai
修 桜井
Takuo Yasuda
拓夫 安田
Kazuo Shinozaki
和夫 篠崎
Koreyasu Mizutani
惟恭 水谷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Metal Mining Co Ltd
Original Assignee
Sumitomo Metal Mining Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sumitomo Metal Mining Co Ltd filed Critical Sumitomo Metal Mining Co Ltd
Priority to JP9247608A priority Critical patent/JPH1171601A/en
Publication of JPH1171601A publication Critical patent/JPH1171601A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To make a crystalline Pd grain difficult to be oxidized by coating the grain surface with amorphous silicon oxide by spraying a raw soln. prepared by dispersing the superfine grain of silicon oxide in an aq. Pd salt soln. into the droplets and passing the droplets through the three temp. regions in a reaction tube to be subjected to drying, pyrolyzing and crystallizing. SOLUTION: The droplet of a raw soln. prepared by dispersing the superfine grains of silicon oxide in an aq. Pd salt soln. generated by a mist generating part 10 is introduced into a heated reaction tube 12 by a carrier gas. The droplet is dried in a low-temp. heating furnace 13 of the reaction tube 12, and the solid grain of the dried mixture (PDO.xH2 O+SiO2 ) is produced by the hydrolysis of Pd(NO3 )2 and the pyrolysis of the formed Pd(OH)2 . The grain is then reheated in a medium-temp. heating furnace 14, and the PdO is partly decomposed into metallic Pd. The grain is further heated in a high-temp. heating furnace 15, the PdO is decomposed, and the composite grain in which the superfine crystal grains of Pd are dispersed in the superfine grain of SiO2 is obtained.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、粉体材料とその製
造方法に係り、特に、積層セラミックコンデンサにおけ
る内部電極用ペーストの構成材料として有用な粉体材料
とその製造方法に関するものである。The present invention relates to a powder material and a method for producing the same, and more particularly to a powder material useful as a constituent material of a paste for an internal electrode in a multilayer ceramic capacitor and a method for producing the same.

【０００２】[0002]

【従来の技術】近年、電子部品の軽薄短小化が進み、チ
ップ部品である積層セラミックコンデンサ（以下、ＭＬ
ＣＣと略称する）に関しても小型化、高容量化の要求が
ますます高まりつつある。そして、ＭＬＣＣの小型化と
高容量化を図る最も効果的な手法は誘電体層と内部電極
を薄くして多層化を図ることである。2. Description of the Related Art In recent years, electronic components have become lighter and thinner and smaller, and multilayer ceramic capacitors (hereinafter, ML) as chip components have been developed.
(Hereinafter abbreviated as CC), there is an increasing demand for miniaturization and high capacity. The most effective way to reduce the size and increase the capacity of the MLCC is to reduce the thickness of the dielectric layer and the internal electrodes to achieve a multilayer structure.

【０００３】ところで、この種のＭＬＣＣとして、例え
ば、図２（Ａ）〜（Ｂ）に示すような構造のものが従来
知られている。すなわち、このＭＬＣＣ（積層セラミッ
クコンデンサ）ａは、複数の誘電体層ｂと内部電極ｃが
交互に積層されたコンデンサ本体ｄと、このコンデンサ
本体ｄの外側に設けられその一方が奇数番目の内部電極
c1群に接続され他方が偶数番目の内部電極c2群に接続さ
れた一対の外部電極e1、e2とでその主要部が構成されて
いるものである。By the way, as this kind of MLCC, for example, one having a structure as shown in FIGS. 2A and 2B is conventionally known. That is, this MLCC (multilayer ceramic capacitor) a has a capacitor body d in which a plurality of dielectric layers b and internal electrodes c are alternately laminated, and one of the capacitor electrodes is provided outside the capacitor body d and one of them is an odd-numbered internal electrode.
The main part is constituted by a pair of external electrodes e1 and e2 connected to the group c1 and the other connected to the group of even-numbered internal electrodes c2.

【０００４】そして、このＭＬＣＣは、従来、以下のよ
うにして製造されている。まず、粉末化されたチタン酸
バリウム（ＢａＴｉＯ3 ）、鉛を含むペロブスカイト型
酸化物等の誘電体と、ポリビニルブチラール樹脂あるい
はブチルメタクリレートやメチルメタクリレート等のア
クリル系樹脂から成る有機バインダーを含む誘電体シー
ト（一般に、誘電体グリーンシートと称される）表面に
内部電極用ペーストをスクリーン印刷法にて製膜しかつ
乾燥させる。The MLCC is conventionally manufactured as follows. First, a dielectric sheet containing powdered barium titanate (BaTiO 3 ), a dielectric material such as a perovskite oxide containing lead, and an organic binder made of polyvinyl butyral resin or an acrylic resin such as butyl methacrylate or methyl methacrylate. A paste for an internal electrode is formed on a surface (generally called a dielectric green sheet) by a screen printing method and dried.

【０００５】次に、上記内部電極用ペーストが製膜され
た誘電体シートを所定の枚数重ね合せると共にこれ等を
熱圧着させた後、この熱圧着体を目的の大きさに切断す
る。続いて、上記誘電体シート内の有機バインダーや内
部電極用ペースト内の有機ビヒクル等のバーンアウト
（完全燃焼）と内部電極及び誘電体の同時焼結を目的と
して１３００℃程度の条件で上記熱圧着体を焼成する。[0005] Next, a predetermined number of dielectric sheets on which the above-mentioned internal electrode paste is formed are laminated and thermocompressed, and then the thermocompressed body is cut into a desired size. Subsequently, the thermocompression bonding is performed at about 1300 ° C. for the purpose of burnout (complete combustion) of the organic binder in the dielectric sheet or the organic vehicle in the internal electrode paste and simultaneous sintering of the internal electrode and the dielectric. Fire the body.

【０００６】次に、この様にして得られた複数の誘電体
層と内部電極が交互に積層されかつ焼成された積層体
（コンデンサ本体）の両端を磨き、その一端側では奇数
番目の内部電極群の端面をまた他端側では偶数番目の内
部電極群の端面をそれぞれ露出させた後、その磨かれた
両端面にＭＬＣＣと外部のデバイスを結合させるための
一対の外部電極を取り付けて上記積層セラミックコンデ
ンサ（ＭＬＣＣ）が完成される。Next, a plurality of dielectric layers and internal electrodes thus obtained are alternately laminated and polished at both ends of a fired laminated body (capacitor body), and odd-numbered internal electrodes are formed at one end thereof. After exposing the end face of the group and the end face of the even-numbered internal electrode group on the other end side, a pair of external electrodes for connecting the MLCC and an external device are attached to the polished end faces, and the above-described lamination is performed. The ceramic capacitor (MLCC) is completed.

【０００７】ところで、上記誘電体シート表面上に製膜
される内部電極用ペーストとしては、従来、金属粉末と
有機ビヒクルを主成分とし必要に応じて粘度調整用の希
釈溶剤等が配合された組成物が適用されている。[0007] By the way, as a paste for an internal electrode formed on the surface of the dielectric sheet, there has hitherto been used a composition comprising a metal powder and an organic vehicle as main components and, if necessary, a diluting solvent or the like for adjusting viscosity. Things have been applied.

【０００８】そして、ＭＬＣＣの内部電極に要求される
上記金属粉末の性質として、セラミック誘電体と反応し
ないこと、粉末自体が溶融しないこと、焼結時のセラミ
ック誘電体への拡散が少ないこと、及び、電気抵抗が小
さいこと等が挙げられる。[0008] The properties of the metal powder required for the internal electrode of the MLCC are that it does not react with the ceramic dielectric, that the powder itself does not melt, that there is little diffusion into the ceramic dielectric during sintering, and that And low electrical resistance.

【０００９】この様な観点から、上記金属粉末として、
Ｐｄ粉末等の貴金属粉末が従来適用されている。From such a viewpoint, as the metal powder,
Noble metal powders such as Pd powder have been conventionally used.

【００１０】[0010]

【発明が解決しようとする課題】ところで、上記ＭＬＣ
Ｃの同時焼成（Cofiring）プロセスにおいて、Ｐｄ粒子
に起因した構造欠陥を生じ易い問題点があった。すなわ
ち、上記Ｐｄ粒子が金属粉末として適用された場合、焼
成中、Ｐｄ粒子は溶融せずかつセラミック誘電体との反
応も少ない特性を有するが、空気中で加熱されると酸化
して黒色の酸化物（ＰｄＯ）になり、生成したＰｄＯは
８００℃付近で分解してＰｄに戻り、これ等一連の酸化
・還元反応により体積の膨張と収縮が起こる。By the way, the above MLC
In the cofiring process of C, there was a problem that structural defects caused by Pd particles were apt to occur. That is, when the Pd particles are applied as a metal powder, the Pd particles do not melt and have little reaction with the ceramic dielectric during sintering. The resulting PdO is decomposed at around 800 ° C. and returns to Pd, and the series of oxidation and reduction reactions causes expansion and contraction of the volume.

【００１１】すなわち、内部電極と誘電体の同時焼結
中、内部電極用ペーストの方では５００〜８００℃の間
にＰｄの酸化による約６８％の体積膨張または約１９％
の線膨張が起こり、そしてＰｄＯの還元による同量の収
縮が発生すると共に、更に、９００℃前後においてＰｄ
の焼結による急激な収縮を引き起こす。That is, during the simultaneous sintering of the internal electrode and the dielectric, the internal electrode paste has a volume expansion of about 68% or about 19% due to oxidation of Pd between 500 and 800 ° C.
And the same amount of shrinkage due to the reduction of PdO occurs, and at around 900 ° C., Pd
Causes rapid shrinkage due to sintering.

【００１２】他方、誘電体層の膨張・収縮現象は、１２
００〜１３００℃付近の焼結による収縮のみである。On the other hand, the expansion and contraction phenomenon of the dielectric layer is caused by 12
There is only shrinkage due to sintering around 00 to 1300 ° C.

【００１３】従って、内部電極とセラミック誘電体の膨
張と収縮挙動が異なるため、セラミック誘電体と内部電
極の層間に引っ張り応力や圧縮応力が発生し、完成され
たＭＬＣＣにデラミネーション（Delamination，層間剥
離現象）やクラック等の構造欠陥が誘発され易い問題点
を有していた。Therefore, since the expansion and contraction behaviors of the internal electrode and the ceramic dielectric are different, a tensile stress or a compressive stress is generated between the layers of the ceramic dielectric and the internal electrode, and the completed MLCC is delaminated. Phenomenon) and structural defects such as cracks are easily induced.

【００１４】尚、ＭＬＣＣのこの様な構造欠陥を防止す
るため、セラミック誘電体と同質の誘電体微粒子や粘土
鉱物、有機ペントナイト等を内部電極用ペースト内に添
加してＰｄ粒子の過焼結を抑制する等の工夫も従来なさ
れているが、セラミック誘電体の特性や電極膜の連続性
に悪影響を及ぼす恐れがあるため未だ有効な防止方法と
はなり得ていない。In order to prevent such structural defects of the MLCC, dielectric fine particles of the same quality as the ceramic dielectric, clay minerals, organic pentonite, etc. are added to the internal electrode paste to oversinter Pd particles. Although some measures have been conventionally taken, such as suppression of the effect, there is a possibility that the characteristics of the ceramic dielectric and the continuity of the electrode film may be adversely affected.

【００１５】本発明はこの様な問題点に着目してなされ
たもので、その課題とするところは、金属粉末としての
上記Ｐｄ粒子に代えて、ＭＬＣＣの上述した構造欠陥を
引き起こし難い内部電極用ペーストの構成材料に適用で
きる粉体材料とその製造方法を提供することにある。The present invention has been made in view of such a problem, and an object of the present invention is to replace the above-mentioned Pd particles as a metal powder with an internal electrode for an MLCC which is unlikely to cause the above-mentioned structural defects. An object of the present invention is to provide a powder material applicable to a constituent material of a paste and a method for producing the same.

【００１６】[0016]

【課題を解決するための手段】すなわち、請求項１に係
る粉体材料は、結晶性Ｐｄ粒子を芯材としこの外表面を
一様に被覆する非晶質酸化ケイ素の表面層とで構成され
ることを特徴とし、また、請求項２に係る粉体材料は、
酸化ケイ素微粒子のマトリックス中に複数の結晶性Ｐｄ
微粒子が均一に分散された複合粒子にて構成されること
を特徴とするものである。That is, the powder material according to the first aspect comprises a crystalline Pd particle as a core material and a surface layer of amorphous silicon oxide which uniformly covers the outer surface thereof. Characterized in that, the powder material according to claim 2,
Multiple crystalline Pd in a matrix of silicon oxide fine particles
It is characterized by being composed of composite particles in which fine particles are uniformly dispersed.

【００１７】そして、請求項１記載の粉体材料は、芯材
である結晶性Ｐｄ粒子の外表面が非晶質酸化ケイ素の表
面層で覆われており、また、請求項２記載の粉体材料
は、複数の結晶性Ｐｄ微粒子が酸化ケイ素微粒子のマト
リックス中に均一に分散された複合粒子で構成されてい
ることから、上記結晶性Ｐｄ粒子若しくは結晶性Ｐｄ微
粒子が酸化され難くなり、かつ、非晶質酸化ケイ素の表
面層並びに酸化ケイ素微粒子のマトリックスの作用によ
り結晶性Ｐｄ粒子若しくは結晶性Ｐｄ微粒子が表面改質
されてその分散性も改善される。In the powder material according to the first aspect, the outer surface of the crystalline Pd particles as the core material is covered with a surface layer of amorphous silicon oxide. Since the material is composed of composite particles in which a plurality of crystalline Pd fine particles are uniformly dispersed in a matrix of silicon oxide fine particles, the crystalline Pd particles or the crystalline Pd fine particles are hardly oxidized, and The crystalline Pd particles or the crystalline Pd fine particles are surface-modified by the action of the surface layer of the amorphous silicon oxide and the matrix of the silicon oxide fine particles, and the dispersibility thereof is also improved.

【００１８】そして、請求項１または請求項２記載の粉
体材料が内部電極用ペーストの金属粉末として適用され
た場合、その結晶性Ｐｄ粒子若しくは結晶性Ｐｄ微粒子
表面の酸化が上記表面層若しくはマトリックスの作用で
防止されることに伴い、Ｐｄの酸化反応、ＰｄＯの還元
反応が起こる９００℃未満における内部電極用ペースト
の膨張・収縮現象が抑制されるため、ＭＬＣＣの構成層
である内部電極と誘電体層の膨張と収縮挙動を略一致さ
せることが可能となる。When the powder material according to claim 1 or 2 is applied as a metal powder of an internal electrode paste, the oxidation of the surface of the crystalline Pd particles or the crystalline Pd fine particles is caused by the surface layer or the matrix. , The expansion and contraction of the internal electrode paste at a temperature of less than 900 ° C., at which the oxidation reaction of Pd and the reduction reaction of PdO occur, is suppressed. It becomes possible to make the expansion and contraction behavior of the body layer substantially coincide.

【００１９】ところで、請求項１記載の粉体材料等を製
造する場合、これ等粉体材料と類似の構造を有する粉体
材料の製造方法として、従来、以下のような手法が知ら
れている。例えば、事前に調製されたＡｇ粒子の表面に
ＣＶＤ法によりＳｉＯ2 層を製膜したり、あるいは、事
前に調製されたコア粒子の表面に界面反応法やゾルゲル
法、機械混合法等によりコーティング層を形成する方法
等が報告されている。しかし、これ等の従来法はコア粒
子の調製とコーティング層の形成とを二段階に分けて行
う必要があり、その分、製造効率は余り良好でない方法
であった。そこで、請求項３と請求項４に係る発明は、
請求項１及び請求項２に係る粉体材料を噴霧熱分解法に
より一段階で製造してその効率を改善させた発明に関す
る。In the meantime, in the case of producing the powder material according to the first aspect, the following method is conventionally known as a method for producing a powder material having a structure similar to the powder material. . For example, a SiO 2 layer is formed on a surface of a previously prepared Ag particle by a CVD method, or a coating layer is formed on a surface of a previously prepared core particle by an interface reaction method, a sol-gel method, a mechanical mixing method, or the like. And the like have been reported. However, in these conventional methods, the preparation of the core particles and the formation of the coating layer must be performed in two steps, and the production efficiency is not so good. Therefore, the invention according to claim 3 and claim 4
The present invention relates to an invention in which the powder material according to claim 1 and claim 2 is manufactured in one step by a spray pyrolysis method to improve the efficiency.

【００２０】すなわち、請求項３に係る発明は、酸化ケ
イ素の超微粒子をＰｄ塩の水溶液中に分散させて原料溶
液を調製し、かつ、この原料溶液を噴霧して液滴とした
後、低温、中温及び高温の３つの温度領域を有する反応
管内に上記液滴を搬入し、この反応管内において乾燥、
熱分解及び結晶化処理して請求項１又は２記載の粉体材
料を製造することを特徴とし、また、請求項４に係る発
明は、請求項３記載の発明に係る請求項１の粉体材料の
製造方法を前提とし、上記酸化ケイ素超微粒子のＰｄに
対する割合が１０mass％、上記Ｐｄ塩の水溶液が０．５
mol/dm3 のＰｄ（ＮＯ3 ）2 水溶液、及び、上記低温、
中温及び高温の３つの温度領域が３００℃、６００℃及
び１４００℃であることを特徴とするものである。That is, the invention according to claim 3 is to prepare a raw material solution by dispersing ultrafine particles of silicon oxide in an aqueous solution of a Pd salt, spray the raw material solution to form droplets, Transporting the droplets into a reaction tube having three temperature regions of medium temperature and high temperature, and drying in the reaction tube;
The powder material according to claim 1 or 2 is manufactured by a thermal decomposition and crystallization treatment, and the invention according to claim 4 is the powder according to claim 1 according to the invention according to claim 3 Assuming the method of producing the material, the ratio of the ultrafine silicon oxide particles to Pd is 10 mass%, and the aqueous solution of the Pd salt is 0.5 mass%.
mol / dm 3 Pd (NO 3 ) 2 aqueous solution
The three temperature ranges of medium temperature and high temperature are 300 ° C., 600 ° C., and 1400 ° C.

【００２１】[0021]

【発明の実施の形態】以下、本発明の実施の形態につい
て図面を参照して詳細に説明する。Embodiments of the present invention will be described below in detail with reference to the drawings.

【００２２】図１は、本発明に係る粉体材料を噴霧熱分
解法により製造する際に適用される噴霧熱分解製造装置
の概略構成を示す説明図である。FIG. 1 is an explanatory view showing a schematic configuration of a spray pyrolysis production apparatus applied when producing a powder material according to the present invention by a spray pyrolysis method.

【００２３】すなわち、この噴霧熱分解製造装置１は、
ミスト発生部（超音波噴霧器、二流体ノズル、静電噴霧
器等）１０と、空気、窒素等キャリアガス混合・供給系
１１と、反応管１２と、この反応管１２の長さ方向に亘
り配置された低温加熱炉１３、中温加熱炉１４、高温加
熱炉１５と、これ等加熱炉の温度制御・記録系（図示せ
ず）と、粉体材料の回収部（サイクロン、フィルタ、静
電集塵器等）１６と、排気ガス処理部１７とでその主要
部が構成されている。That is, this spray pyrolysis production apparatus 1
A mist generator (ultrasonic atomizer, two-fluid nozzle, electrostatic atomizer, etc.) 10, a carrier gas mixing / supply system 11 such as air and nitrogen, a reaction tube 12, and a reaction tube 12 are arranged in the longitudinal direction. The low-temperature heating furnace 13, the medium-temperature heating furnace 14, the high-temperature heating furnace 15, the temperature control / recording system (not shown) of these heating furnaces, and the powder material recovery unit (cyclone, filter, electrostatic precipitator) Etc.) and the exhaust gas processing unit 17 constitute the main part.

【００２４】以下、酸化ケイ素（ＳｉＯ2 ）の超微粒子
をＰｄ塩であるＰｄ（ＮＯ3 ）2 水溶液に分散させた原
料溶液から、請求項１及び請求項２に係る粉体材料を合
成する場合を例としてこれ等材料の生成機構を説明す
る。In the following, the powder material according to claim 1 or 2 is synthesized from a raw material solution in which ultrafine particles of silicon oxide (SiO 2 ) are dispersed in an aqueous solution of Pd (NO 3 ) 2 as a Pd salt. The generation mechanism of these materials will be described as an example.

【００２５】まず、ミスト発生部１０によって発生した
液滴は加熱された反応管１２内にキャリアガスによって
導入されると、低温加熱炉１３に位置された反応管１２
内において乾燥しかつＰｄ（ＮＯ3 ）2 の加水分解や生
成されたＰｄ（ＯＨ）2 等の熱分解等により各成分の原
料の乾燥混合物（ＰｄＯ・ｘＨ2Ｏ＋ＳｉＯ2）の固体粒
子を作る。この固体粒子の中ではＰｄＯ・ｘＨ2ＯとＳ
ｉＯ2が均一に混合している。First, when the droplets generated by the mist generating section 10 are introduced into the heated reaction tube 12 by the carrier gas, the reaction tube 12 located in the low-temperature heating furnace 13
Then, solid particles of a dry mixture (PdO.xH 2 O + SiO 2 ) of the raw materials of each component are produced by drying in the inside and hydrolyzing Pd (NO 3 ) 2 and thermal decomposition of generated Pd (OH) 2 and the like. Among these solid particles, PdO.xH 2 O and S
iO 2 is uniformly mixed.

【００２６】次に、中温加熱炉１４に位置された反応管
１２内において更に加熱されると、温度の上昇に従って
粒子中のＰｄＯの一部は分解されて金属（Ｐｄ）とな
る。Next, when the reaction tube 12 is further heated in the reaction tube 12 located in the intermediate temperature heating furnace 14, part of PdO in the particles is decomposed into metal (Pd) as the temperature rises.

【００２７】次に、高温加熱炉１５に位置された反応管
１２内において更に高温（７００℃以上）で加熱される
とＰｄＯが分解し、生成したナノオーダーのＰｄ超微粒
結晶粒子がＳｉＯ2 の超微粒子から成るマトリックス中
に均一に分散した構造の複合粒子である粉体材料（請求
項２に係る材料）が得られる。この温度はＰｄの焼結温
度（約３００℃）よりかなり高いので、生成したＰｄ超
微粒結晶粒子が合体しながら成長し、粒子の中央に集ま
ることによってＰｄだけのコア（芯材）を形成する。一
方、ＳｉＯ2 は焼結しないので粒子のマトリックスはほ
とんど収縮せず、複合粒子の粒径は変化しない。そし
て、上記高温加熱炉１５の温度が請求項２に係る粉体材
料を得る温度条件より高く設定されあるいは高温加熱炉
１５に位置された反応管１２内に上記複合粒子が長時間
浮遊して存在するとＰｄの焼結が更に進み、複合粒子内
部での再配列によって中心部にあったＳｉＯ2 も粒子表
面に押し出され、Ｐｄが粒子の真ん中に集まり、中実で
単結晶に近いコア粒子すなわち結晶性Ｐｄ粒子を芯材と
しこの外表面を一様に被覆する非晶質酸化ケイ素の表面
層とで構成された請求項１に係る粉体材料が得られる。Next, when the PdO is heated at a higher temperature (700 ° C. or more) in the reaction tube 12 located in the high-temperature heating furnace 15, PdO is decomposed, and the generated nano-order Pd ultrafine crystal particles are formed of SiO 2 . A powder material (material according to claim 2), which is a composite particle having a structure uniformly dispersed in a matrix composed of ultrafine particles, is obtained. Since this temperature is much higher than the sintering temperature of Pd (about 300 ° C.), the generated ultrafine crystal grains of Pd grow while uniting, and gather at the center of the grains to form a Pd-only core. . On the other hand, since SiO 2 is not sintered, the particle matrix hardly shrinks, and the particle size of the composite particles does not change. Then, the temperature of the high-temperature heating furnace 15 is set higher than the temperature condition for obtaining the powder material according to claim 2, or the composite particles are suspended in the reaction tube 12 positioned in the high-temperature heating furnace 15 for a long time. Then, the sintering of Pd proceeds further, and the SiO 2 at the center is also pushed out to the particle surface by the rearrangement inside the composite particles, Pd gathers in the center of the particles, and the core particles, which are solid and close to a single crystal, that is, crystals, The powder material according to claim 1, comprising an amorphous Pt particle as a core material and a surface layer of amorphous silicon oxide uniformly covering the outer surface.

【００２８】尚、この製造プロセスでは、生成されるＰ
ｄ粒子の構造や結晶性は液滴／粒子の加熱条件（加熱温
度、加熱時間、加熱速度等）に影響されるので、目的と
する粉体材料に合わせた上記加熱条件の設定が重要であ
る。In this manufacturing process, the generated P
Since the structure and crystallinity of the d-particles are affected by the droplet / particle heating conditions (heating temperature, heating time, heating rate, etc.), it is important to set the above-mentioned heating conditions according to the target powder material. .

【００２９】[0029]

【実施例】以下、本発明の実施例について説明する。Embodiments of the present invention will be described below.

【００３０】［実施例１］Ｐｄの原料はＰｄ（ＮＯ3 ）
2 （東洋化学工業製）を用い、ＳｉＯ2 の原料は火炎中
加水分解法で合成したＳｉＯ2 超微粒子（純度９９．９
％、和光純薬工業製）を用いた。[Example 1] The raw material of Pd is Pd (NO 3 )
2 used (Toyo Chemical Industries, Ltd.), SiO 2 ultrafine particles (purity 99.9 of SiO 2 raw material synthesized in the flame hydrolysis method
%, Manufactured by Wako Pure Chemical Industries, Ltd.).

【００３１】そして、ＳｉＯ2 超微粒子をＰｄに対して
１０mass％（質量％）の割合で０．５mol/dm3 のＰｄ
（ＮＯ3 ）2 水溶液中に混合し、超音波で分散させて出
発溶液（原料溶液）を調製した。Then, the SiO 2 ultrafine particles were added at a rate of 10 mass% (mass%) with respect to Pd to 0.5 mol / dm 3 of Pd.
A (NO 3 ) 2 aqueous solution was mixed and dispersed with ultrasonic waves to prepare a starting solution (raw material solution).

【００３２】尚、原料に用いたＳｉＯ2 粒子は粒径２０
ｎｍ前後の球状であり、実測した比表面積は１８４．７
ｍ2 ／ｇである。ＸＲＤ分析によりＳｉＯ2 粒子は非晶
質であり、ＴＧ−ＤＴＡ測定より空気中１２００℃まで
熱の出入りと重量変化はほとんどないことが分かった。The SiO 2 particles used as the raw material had a particle size of 20.
nm, and the measured specific surface area was 184.7.
m 2 / g. XRD analysis showed that the SiO 2 particles were amorphous, and TG-DTA measurement showed that there was almost no change in heat and no change in weight up to 1200 ° C. in air.

【００３３】次に、図１に示した噴霧熱分解製造装置に
上記出発溶液（原料溶液）を導入して、結晶性Ｐｄ粒子
を芯材としこの外表面を一様に被覆する非晶質酸化ケイ
素の表面層とで構成された粉体材料すなわちＳｉＯ2 被
覆Ｐｄ粒子を合成した。Next, the starting solution (raw material solution) is introduced into the spray pyrolysis production apparatus shown in FIG. 1, and the amorphous Pd particles are used as a core material to uniformly coat the outer surface thereof. A powder material composed of a silicon surface layer, that is, SiO 2 -coated Pd particles was synthesized.

【００３４】尚、上記噴霧熱分解製造装置において低温
加熱炉１３である乾燥炉の温度は３００℃、中温加熱炉
１４である熱分解炉の温度は６００℃、及び、高温加熱
炉１５である結晶化炉の温度は１４００℃にそれぞれ設
定されている。The temperature of the drying furnace as the low-temperature heating furnace 13 is 300 ° C., the temperature of the pyrolysis furnace as the medium-temperature heating furnace 14 is 600 ° C., and the temperature of the high-temperature heating furnace 15 is the crystal. The temperature of the gasification furnace is set to 1400 ° C.

【００３５】また、合成した粒子の形態は、電界放射型
走査型電子顕微鏡（ＦＥ−ＳＥＭ；日立製作所製，Ｓ−
８００）で観察した。また、粒子をエポキシ樹脂に包理
してミクロトーム（Reichert-Nissei製，Ultracut Ｎ）
で５０〜８０ｎｍの厚さの薄片に切り、透過型電子顕微
鏡（ＴＥＭ；日本電子製，JEM-200CX）で粒子の内部構
造を観察し、付属のエネルギー分散型Ｘ線分析装置（Ｅ
ＤＳ；Philips製，EDAX-PV9900）で組成分析を行った。
これ等の観察結果を以下の『結果』の欄において実施例
２並びに比較例の結果と共に詳細に説明する。The form of the synthesized particles is determined by using a field emission scanning electron microscope (FE-SEM;
800). Also, the particles are wrapped in epoxy resin and a microtome (Reichert-Nissei, Ultracut N)
And cut into thin pieces having a thickness of 50 to 80 nm with a transmission electron microscope (TEM; manufactured by JEOL Ltd., JEM-200CX) to observe the internal structure of the particles. The attached energy dispersive X-ray analyzer (E
DS; EDAX-PV9900, manufactured by Philips).
The results of these observations will be described in detail in the following “Results” section together with the results of Example 2 and Comparative Example.

【００３６】次に、粒子の比表面積はＢＥＴ法（Microm
eritics製，Flowsorb II）で測定し、また、粒子の熱分
析（ＴＧ−ＤＴＡ；理学電気製，TAS-200）は窒素中で
２０Ｋ・min-1の加速速度で行った。Next, the specific surface area of the particles is determined by the BET method (Microm
The thermal analysis of the particles (TG-DTA; TAS-200, manufactured by Rigaku Denki) was performed in nitrogen at an acceleration rate of 20 K · min −1 .

【００３７】［実施例２］ＳｉＯ2 超微粒子をＰｄに対
し１mass％（質量％）の割合で０．５mol/dm3 のＰｄ
（ＮＯ3 ）2 水溶液中に混合して出発溶液（原料溶液）
を調製している点を除き実施例１と略同一の条件でＳｉ
Ｏ2 被覆Ｐｄ粒子を合成した。Example 2 0.5 mol / dm 3 of Pd was added at a ratio of 1 mass% (mass%) of Pd to SiO 2 ultrafine particles.
(NO 3 ) 2 Starting solution mixed with an aqueous solution (raw material solution)
Under substantially the same conditions as in Example 1 except that
O 2 -coated Pd particles were synthesized.

【００３８】［比較例］ＳｉＯ2 超微粒子が無添加の
０．５mol/dm3 のＰｄ（ＮＯ3 ）2 水溶液を出発溶液
（原料溶液）としている点を除き実施例１と略同一の条
件でＰｄ粒子を合成した。Comparative Example Under substantially the same conditions as in Example 1 except that a 0.5 mol / dm 3 aqueous solution of Pd (NO 3 ) 2 to which no ultrafine SiO 2 particles were added was used as a starting solution (raw material solution). Pd particles were synthesized.

【００３９】『結果』合成された粒子のＳＥＭ写真と粒
子の薄片のＴＥＭ写真から以下のことが確認された。[Results] From the SEM photograph of the synthesized particles and the TEM photograph of the flakes of the particles, the following was confirmed.

【００４０】すなわち、ＳｉＯ2 超微粒子が無添加の比
較例に係るＰｄ粒子では表面は非常に平滑であるのと比
較すると、ＳＥＭ写真から合成された実施例１に係る粒
子の表面に凹凸があり、ＳｉＯ2 超微粒子で覆われてい
ることが分かる。粒子の薄片のＴＥＭ写真にはコントラ
ストの著しく異なる二相が観察された。That is, when the surface of the Pd particle according to the comparative example to which no ultrafine SiO 2 particles were added was very smooth, the surface of the particle according to the example 1 synthesized from the SEM photograph had irregularities. It can be seen that the particles are covered with ultrafine SiO 2 particles. Two phases with significantly different contrast were observed in the TEM photograph of the flakes of the particles.

【００４１】そして、ＴＥＭ−ＥＤＳ分析より、透明に
見える表面部にはＳｉ元素が、粒子内部の不透明な部分
にはＰｄが検出された。また、電子線回折により表面部
は非晶質を示すブロードなリングパターンが、Ｐｄの部
分は立方晶を示す回折パターンが認められた。試料のＸ
ＲＤパターンには立方晶Ｐｄの鋭いピークのみが認めら
れ、ＳｉＯ2 に帰属されるピークは現れなかった。From the TEM-EDS analysis, Si element was detected on the transparent surface, and Pd was detected on the opaque part inside the particle. Further, a broad ring pattern showing amorphous on the surface portion and a diffraction pattern showing cubic crystal on the Pd portion were recognized by electron beam diffraction. X of sample
Only a sharp peak of cubic Pd was observed in the RD pattern, and no peak attributed to SiO 2 appeared.

【００４２】これ等の結果から、ＳｉＯ2 超微粒子が１
０mass％添加された実施例１の場合、結晶性の高いＰｄ
粒子のコア（芯材）と、厚さがほぼ均一なＳｉＯ2 の表
面層からなるマイクロカプセル粒子（粉体材料）が得ら
れることが確認された。From these results, it was found that ultrafine SiO 2 particles
In the case of Example 1 in which 0 mass% is added, Pd having high crystallinity
It was confirmed that microcapsule particles (powder material) comprising a particle core (core material) and a surface layer of SiO 2 having a substantially uniform thickness were obtained.

【００４３】計算では、添加量が１０mass％の実施例１
と添加量が１mass％の実施例２の場合、ＳｉＯ2 の体積
分率はそれぞれ約３５％と５．２％で、０．５μｍの球
状Ｐｄ粒子表面にはそれぞれ４６ｎｍと４．６ｎｍの被
覆層が形成される。In the calculation, Example 1 in which the amount of addition was 10 mass% was used.
In the case of Example 2 where the addition amount is 1 mass%, the volume fraction of SiO 2 is about 35% and 5.2%, respectively, and the coating layer of 46 nm and 4.6 nm respectively is formed on the surface of the 0.5 μm spherical Pd particle. Is formed.

【００４４】粒子内部構造の観察ではＳｉＯ2 層がポー
ラスなので少し厚めに見えるが、添加量が１mass％の実
施例２の場合、ＳｉＯ2 による被覆は若干不完全でＰｄ
粒子の一部が露出していることが観察された。In the observation of the internal structure of the particles, the SiO 2 layer is porous and looks slightly thicker, but in the case of Example 2 where the addition amount is 1 mass%, the coating with SiO 2 is slightly incomplete and Pd
It was observed that some of the particles were exposed.

【００４５】また、ＥＤＳ分析と電子線回折により、Ｓ
ｉＯ2 超微粒子の集まった表面層の中に少量の細かい球
状Ｐｄ超微粒子が混入することもあったが、逆にＳｉＯ
2 が内部のＰｄ粒子中に存在することはなかった。Further, by EDS analysis and electron diffraction, S
A small amount of fine spherical Pd ultra-fine particles sometimes mixed into the surface layer where the iO 2 ultra-fine particles were gathered.
2 was not present in the internal Pd particles.

【００４６】そして、実施例１及び実施例２に係る粉体
材料（ＳｉＯ2 被覆Ｐｄ粒子）を適用して内部電極用ペ
ーストを調製し、かつ、この内部電極用ペーストを用い
てＭＬＣＣを製造したところ、比較例のＰｄ粒子が適用
された内部電極用ペーストを用いた場合に較べてデラミ
ネーションやクラック等の構造欠陥が少なかった。Then, a paste for an internal electrode was prepared by applying the powder material (SiO 2 -coated Pd particles) according to Examples 1 and 2, and an MLCC was manufactured using the paste for an internal electrode. However, there were fewer structural defects such as delamination and cracks as compared with the case of using the internal electrode paste to which the Pd particles of the comparative example were applied.

【００４７】[0047]

【発明の効果】請求項１記載の発明に係る粉体材料は、
芯材である結晶性Ｐｄ粒子の外表面が非晶質酸化ケイ素
の表面層で覆われており、また、請求項２記載の発明に
係る粉体材料は、複数の結晶性Ｐｄ微粒子が酸化ケイ素
微粒子のマトリックス中に均一に分散された複合粒子で
構成されていることから、上記結晶性Ｐｄ粒子若しくは
結晶性Ｐｄ微粒子が酸化され難くなり、かつ、非晶質酸
化ケイ素の表面層並びに酸化ケイ素微粒子のマトリック
スの作用により結晶性Ｐｄ粒子若しくは結晶性Ｐｄ微粒
子が表面改質されてその分散性も改善される。The powder material according to the first aspect of the present invention is
The outer surface of the crystalline Pd particles as the core material is covered with a surface layer of amorphous silicon oxide, and the powder material according to the invention according to claim 2, wherein the plurality of crystalline Pd fine particles are silicon oxide. Since it is composed of composite particles uniformly dispersed in a matrix of fine particles, the crystalline Pd particles or the crystalline Pd fine particles are hardly oxidized, and a surface layer of amorphous silicon oxide and silicon oxide fine particles The surface of the crystalline Pd particles or crystalline Pd fine particles is modified by the action of the matrix described above, and the dispersibility thereof is also improved.

【００４８】従って、これ等粉体材料が内部電極用ペー
ストの金属粉末として適用された場合、その結晶性Ｐｄ
粒子若しくは結晶性Ｐｄ微粒子表面の酸化が上記表面層
若しくはマトリックスの作用で防止されることに伴い、
Ｐｄの酸化反応、ＰｄＯの還元反応が起こる９００℃未
満における内部電極用ペーストの膨張・収縮現象が抑制
されるため、ＭＬＣＣの構成層である内部電極と誘電体
層の膨張と収縮挙動を略一致させることが可能となる効
果を有する。Therefore, when these powder materials are applied as the metal powder of the internal electrode paste, their crystalline Pd
With the oxidation of the surface of the particles or crystalline Pd fine particles being prevented by the action of the surface layer or matrix,
Since the expansion and shrinkage of the internal electrode paste is suppressed below 900 ° C where the oxidation reaction of Pd and the reduction reaction of PdO occur, the expansion and shrinkage behavior of the internal electrode and the dielectric layer, which are the constituent layers of the MLCC, almost match. This has the effect of being able to cause

【００４９】また、請求項３及び請求項４記載の発明に
係る粉体材料の製造方法によれば、一段階で請求項１及
び請求項２に係る粉体材料を製造できるためその効率の
改善が図れる効果を有している。Further, according to the method of manufacturing a powder material according to the third and fourth aspects of the present invention, the powder material according to the first and second aspects can be manufactured in one step, so that the efficiency is improved. This has the effect of achieving the following.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明に係る粉体材料を製造するための噴霧熱
分解製造装置の概略構成を示す説明図。FIG. 1 is an explanatory view showing a schematic configuration of a spray pyrolysis production apparatus for producing a powder material according to the present invention.

【図２】図２（Ａ）は積層セラミックコンデンサの概略
斜視図であり、図２（Ｂ）は図２（Ａ）の一部切欠断面
図である。2 (A) is a schematic perspective view of a multilayer ceramic capacitor, and FIG. 2 (B) is a partially cutaway sectional view of FIG. 2 (A).

【符号の説明】[Explanation of symbols]

１ 噴霧熱分解製造装置 １０ ミスト発生部 １１ キャリアガス混合・供給系 １２ 反応管 １３ 低温加熱炉 １４ 中温加熱炉 １５ 高温加熱炉 １６ 回収部 １７ 排気ガス処理部 DESCRIPTION OF SYMBOLS 1 Spray pyrolysis manufacturing apparatus 10 Mist generation part 11 Carrier gas mixing / supply system 12 Reaction tube 13 Low temperature heating furnace 14 Medium temperature heating furnace 15 High temperature heating furnace 16 Recovery part 17 Exhaust gas processing part

フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｈ０１Ｇ 4/12 ３６１ Ｈ０１Ｇ 1/01 (72)発明者 篠崎 和夫 東京都稲城市大丸13−６ (72)発明者 水谷 惟恭 東京都品川区荏原７−16−12Continued on the front page (51) Int.Cl. 6 Identification symbol FI H01G 4/12 361 H01G 1/01 (72) Inventor Kazuo Shinozaki 13-6 Daimaru, Inagi-shi, Tokyo (72) Inventor Nobutasu Mizutani Shinagawa-ku, Tokyo EBARA 7-16-12

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】結晶性Ｐｄ粒子を芯材としこの外表面を一
様に被覆する非晶質酸化ケイ素の表面層とで構成される
ことを特徴とする粉体材料。1. A powder material comprising a crystalline Pd particle as a core material and an amorphous silicon oxide surface layer uniformly covering the outer surface thereof. 【請求項２】酸化ケイ素微粒子のマトリックス中に複数
の結晶性Ｐｄ微粒子が均一に分散された複合粒子にて構
成されることを特徴とする粉体材料。2. A powder material comprising a composite particle in which a plurality of crystalline Pd fine particles are uniformly dispersed in a matrix of silicon oxide fine particles. 【請求項３】酸化ケイ素の超微粒子をＰｄ塩の水溶液中
に分散させて原料溶液を調製し、かつ、この原料溶液を
噴霧して液滴とした後、低温、中温及び高温の３つの温
度領域を有する反応管内に上記液滴を搬入し、この反応
管内において乾燥、熱分解及び結晶化処理して請求項１
又は２記載の粉体材料を製造することを特徴とする粉体
材料の製造方法。3. A raw material solution is prepared by dispersing ultrafine particles of silicon oxide in an aqueous solution of a Pd salt, and the raw material solution is sprayed to form droplets. 2. The method according to claim 1, wherein the droplets are carried into a reaction tube having a region, and dried, thermally decomposed, and crystallized in the reaction tube.
Or a method for producing a powder material, characterized by producing the powder material according to 2. 【請求項４】上記酸化ケイ素超微粒子のＰｄに対する割
合が１０mass％、上記Ｐｄ塩の水溶液が０．５mol/dm3
のＰｄ（ＮＯ3 ）2 水溶液、及び、上記低温、中温及び
高温の３つの温度領域が３００℃、６００℃及び１４０
０℃であることを特徴とする請求項１記載の粉体材料を
製造する請求項３記載の製造方法。4. The ratio of the ultrafine silicon oxide particles to Pd is 10 mass%, and the aqueous solution of the Pd salt is 0.5 mol / dm 3.
Pd (NO 3 ) 2 aqueous solution, and the three temperature ranges of low, medium and high temperatures of 300 ° C., 600 ° C. and 140 ° C.
The method according to claim 3, wherein the temperature is 0 ° C.
JP9247608A 1997-08-29 1997-08-29 Powder material and its production Pending JPH1171601A (en)

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US7615939B2 (en) 2003-03-17 2009-11-10 C&D Zodiac, Inc. Spectrally calibratable multi-element RGB LED light source
KR100658113B1 (en) 2005-04-27 2006-12-14 한국기계연구원 A production process of Fe nano powder with silica coating by Chemical Vapor Condensation
KR100925150B1 (en) 2008-05-29 2009-11-05 한국세라믹기술원 Ultrasonic spray pyrolysis apparatus
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