JP4480884B2 - Method for producing surface-modified silver powder - Google Patents
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- JP4480884B2 JP4480884B2 JP2000385067A JP2000385067A JP4480884B2 JP 4480884 B2 JP4480884 B2 JP 4480884B2 JP 2000385067 A JP2000385067 A JP 2000385067A JP 2000385067 A JP2000385067 A JP 2000385067A JP 4480884 B2 JP4480884 B2 JP 4480884B2
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Description
【０００１】
【発明の属する技術分野】
本発明は表面修飾銀粉の製造方法に関し、詳しくは、金属銀粒子表面に特定の金属元素の酸化物及び／又は複合酸化物が固着しており、銀の融点未満の温度で用いる回路形成用焼成型ペースト、特にＬＴＣＣ（low-temperature cofired ceramic 、低温同時焼結セラミック）回路基板形成用焼成型ペーストに用いるのに適している表面修飾銀粉の製造方法に関する。
【０００２】
【従来の技術】
携帯通信端末及び BluetoothのＲＦ回路については、小型・高密度化並びに近い将来の１チップ化をにらみ、近年ＬＴＣＣパッケージが主流になりつつある。ＬＴＣＣパッケージでは、セラミック多層基板内部に受動部品を作り込み、半導体を実装することでＲＦ回路全体を一つの部品に集約することが可能となる。
【０００３】
現在既に実用化されているＬＴＣＣパッケージでは、その配線材料として電気的特性を重視しているために銀又は銅が主流であり、それらの金属粉と有機バインダーとを混練して得た焼成型ペーストを用いてスクリーン印刷によりグリーンシート上に印刷し、同時焼成するプロセスによって一般的に製作されている。
【０００４】
上記の焼成型ペーストに用いる金属粉に要求される特性としては、スクリーン印刷の精度を上げるために且つ焼成型ペーストの調製が容易になるように、凝集が少なく、粒径が均一であることが求められ、それと共に、焼成の際に熱収縮が小さいことが求められる。金属粉が銀である場合には、銀粉はその融点が９６０℃であるが、５００℃程度から焼結が開始され、それに伴って収縮が始まる。このため、銀粉を配線材料として用いる場合には、形成される銀配線とその下側の部材との熱収縮挙動の差異を考慮しなければならない。銀粉の焼結開始温度を十分に上昇させ且つ焼結による熱収縮を抑制する目的で、銀粉と共に無機酸化物粒子を混入させて焼成型ペーストを調製し、これにより熱収縮を抑制することが試みられている。しかしながら、この方法では多量の無機酸化物粒子を添加する必要があり、その結果として、形成された配線の電気特性が損なわれる傾向があった。
【０００５】
【発明が解決しようとする課題】
本発明は、個々の銀粉粒子の表面に均一に金属酸化物及び／又は複合酸化物を固着させることにより、必要最少限の金属酸化物及び／又は複合酸化物量で銀粉の電気特性を損なうことなしで、焼結による熱収縮を最大に抑制する効果が得られ、銀の融点未満の温度で用いる回路形成用焼成型ペースト、特にＬＴＣＣ回路基板形成用焼成型ペーストに用いるのに適している表面修飾銀粉の製造方法を提供することを課題としている。
【０００６】
【課題を解決するための手段】
本発明者は、上記の課題を達成するために鋭意検討した結果、金属銀粒子表面に、特定の金属元素の酸化物及び／又は複合酸化物を固着させて表面修飾銀粉とすることにより上記の課題が達成されることを見出し、本発明を完成した。
【０００９】
即ち、本発明の表面修飾銀粉の製造方法は、金属銀粒子の表面に、原子番号１２〜８２の範囲内で周期表の２〜１４族に属する金属元素の少なくとも１種を含む酸化物及び複合酸化物の超微粒子からなる群より選ばれる少なくとも１種を付着させ、該超微粒子の付着している金属銀粒子を相互に又は他物体と衝突させて該金属銀粒子の表面に該超微粒子を固着させることを特徴とする。
【００１０】
また、本発明の表面修飾銀粉の製造方法は、原子番号１２〜８２の範囲内で周期表の２〜１４族に属する金属元素の少なくとも１種を含む酸化物及び複合酸化物の超微粒子からなる群より選ばれる少なくとも１種を懸濁させた懸濁液と、金属銀粒子とを混合しながら加熱し、該懸濁液の媒体を除去して、該金属銀粒子の表面に該超微粒子を付着させ、該超微粒子の付着している金属銀粒子を相互に又は他物体と衝突させて該金属銀粒子の表面に該超微粒子を固着させることを特徴とする。
【００１１】
【発明の実施の形態】
本発明の表面修飾銀粉の製造方法で得られる表面修飾銀粉（以下、本発明の表面修飾銀粉と略記する）は、回路の形成、例えばチップ部品（チップインダクタ、コンデンサ等）の内部電極及び外部電極等の形成、特にＬＴＣＣ回路基板の形成に用いる焼成型ペーストに用いることを主目的としているので、芯となる金属銀粒子の平均粒子径が１０μｍ以下、好ましくは０．１〜１μｍで、好ましくは球状のものを対象としている。そのような芯となる金属銀粒子の製造方法については何ら制限されることはなく、如何なる製造方法によって得られたものでも使用できる。
【００１２】
本発明の表面修飾銀粉においては、上記のような金属銀粒子表面に、原子番号１２〜８２の範囲内で周期表の２〜１４族に属する金属元素の少なくとも１種を含む酸化物及び複合酸化物からなる群より選ばれる少なくとも１種が固着している。本発明の表面修飾銀粉においては、該酸化物及び複合酸化物が原子番号１２〜７４の範囲内で周期表の２〜４族、７族、１３族及び１４族に属する金属元素の少なくとも１種を含む酸化物及び複合酸化物であることが好ましく、酸化物及び複合酸化物がアルミニウム、ケイ素、ジルコニウム、イットリウム、マグネシウム、及びランタノイド元素の少なくとも１種を含む酸化物及び複合酸化物であることが更に好ましい。
【００１３】
上記の酸化物及び複合酸化物としては、例えば、ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯ、ＺｎＯ、Ａｌ2 Ｏ3 、Ｇａ2 Ｏ3 、Ｙ2 Ｏ3 、ＳｉＯ2 、ＴｉＯ2 、ＺｒＯ2 、Ｃｒ2 Ｏ3 、ＭｎＯ2 、Ｍｎ3 Ｏ4 、Ｎｂ2 Ｏ5 、ＢａＴｉＯ3 、ＣａＴｉＯ3 、ＳｒＴｉＯ3 、ＢａＺｒＯ3 、ＣａＺｒＯ3 、ＳｒＺｒＯ3 、（Ｍｇ，Ｃａ）ＴｉＯ3 、（Ｂａ，Ｃａ）（Ｔｉ，Ｚｒ）Ｏ3 、ＰｂＴｉＯ3 、Ｐｂ（Ｚｒ，Ｔｉ）Ｏ3 、（Ｐｂ，Ｃａ）ＴｉＯ3 、ＭｇＡｌ2 Ｏ4 、ＢａＴｉ4 Ｏ9 、Ｎｄ2 Ｏ3 、Ｓｍ2 Ｏ3 、Ｄｙ2 Ｏ3 、Ｅｒ2 Ｏ3 、Ｈｏ2 Ｏ3 等を挙げることができ、更にこれらの酸化物及び／又は複合酸化物はＮｂ、Ｗ、Ｌａ、Ｙ、Ｍｏ等の金属の酸化物でドープされていてもよい。それらの酸化物及び複合酸化物は単独で用いることも、混合物として用いることもできる。
【００１４】
本発明の表面修飾銀粉においては、固着される酸化物及び／又は複合酸化物の好ましい固着量は金属銀粒子の粒径の違いによって変化するが、酸化物及び／又は複合酸化物の固着量（混合物として用いる場合には合計固着量）（本明細書においてはその両方を含めて合計固着量と記載する）が金属銀粒子の質量に対して好ましくは０．１〜１０質量％であり、より好ましくは０．５〜８質量％であり、更に好ましくは１〜７質量％である。合計固着量が０．１質量％未満の場合には、酸化物及び／又は複合酸化物の固着によって達成される本発明の効果が不十分となる傾向があり、逆に１０質量％を越える場合には、そのような表面修飾銀粉を用いて配線を形成した場合に、その配線の導電性に悪影響を及ぼす傾向がある。
【００１５】
本発明の表面修飾銀粉は回路形成用焼成型ペースト用として、特にＬＴＣＣ回路基板形成用焼成型ペースト用として適している。本発明の表面修飾銀粉を含有するペーストは銀の融点未満の温度で用いる必要があり、また５００℃以上の温度で焼成する場合に有効に機能する。またＬＴＣＣ回路基板形成用焼成型ペーストに用いる場合には、金属銀粒子の表面に固着している酸化物及び／又は複合酸化物がＬＴＣＣの基板の組成物と同一であることが特に好ましい。
【００１６】
本発明の製造方法は、乾式固着法、又は金属酸化物又は複合酸化物の超微粒子の水性懸濁液を金属銀粒子に固着させて乾燥する半乾式固着法である。
【００１７】
乾式固着法に従って実施する場合の本発明の表面修飾銀粉の製造方法においては、金属銀粒子の表面に原子番号が１２〜８２の範囲内で周期表の２〜１４族に属する金属元素の少なくとも１種を含む酸化物及び複合酸化物の超微粒子からなる群より選ばれる少なくとも１種を付着させ、該超微粒子の付着している金属銀粒子を相互に又は他物体と衝突させて該金属銀粒子の表面に該超微粒子を固着させることができる。
【００１８】
酸化物、複合酸化物の超微粒子は、粒径が小さいほど少量で金属銀粒子の表面に均一に固着させることができるので、粒径が０．５μｍ以下であることが好ましく、０．１μｍ以下であることがより好ましく、０．０５μｍ以下であることが最も好ましい。
【００１９】
金属銀粒子の表面に酸化物及び／又は複合酸化物の超微粒子を固着させる方法としては、金属銀粒子と酸化物及び／又は複合酸化物の超微粒子とを混合した後、該超微粒子の付着している金属銀粒子を、例えば、オングミル、ハイブリタイザー、メカノフュージョン、コートマイザー、ディスパーコート、ジェットマイザー、サンドミル、ミックスマーラー等の装置中に装入して、相互に又は他物体と衝突させて該金属銀粒子の表面に該超微粒子を固着させることができる。
【００２０】
半乾式固着法に従って実施する場合の本発明の表面修飾銀粉の製造方法においては、原子番号１２〜８２の範囲内で周期表の２〜１４族に属する金属元素の少なくとも１種を含む酸化物及び複合酸化物の超微粒子からなる群より選ばれる少なくとも１種を懸濁させた懸濁液と、金属銀粒子とを混合しながら加熱し、該懸濁液の媒体を除去して、該金属銀粒子の表面に該超微粒子を付着させ、該超微粒子の付着している金属銀粒子を相互に又は他物体と衝突させて該金属銀粒子の表面に該超微粒子を固着させることができる。
【００２１】
上記の半乾式固着法で用いる金属銀粒子、並びに酸化物及び複合酸化物の超微粒子は上記の乾式固着法で用いるものと同一でよい。また、超微粒子を懸濁させる媒体は特には限定されず、一般的には水、酸性水溶液、塩基性水溶液、アルコール、有機溶媒等を用いることができる。この製造方法においては所定固形分濃度の懸濁液を調製して用いても、或いは、市販品のシリカゾル、アルミナゾル、チタニアゾル、チタン酸バリウムゾル等を用い、必要に応じて希釈などを行って濃度を調整して用いてもよい。
【００２６】
以下に、実施例及び比較例によって本発明を具体的に説明するが、本発明はかかる事例に限定されるものではない。
実施例１
銀粉（ＳＥＭ観察平均粒子径約０．５μｍ）１００質量部に酸化アルミニウム（平均１次粒子径約１５ｎｍ、比表面積約１００ｍ2 ／ｇ）５質量部を添加し、充分に攪拌混合した。これにより金属銀粒子の表面に微粒の酸化アルミニウムが付着している金属銀粒子を得た。次にこれをハイブリタイザー（奈良機械製作所製）に投入し、８０００ｒｐｍで５分間循環させて、金属銀粒子表面に微粒の酸化アルミニウムが固着された表面修飾銀粉を得た。この表面修飾銀粉を溶媒中に入れて攪拌しても、微粒の酸化アルミニウムが金属銀粒子から剥離することはなかった。
【００２７】
この表面修飾銀粉０．５ｇに９８ＭＰａの圧力を加えて直径５ｍｍ、高さ約５ｍｍのペレットに成形した。このペレットを熱機械分析（ＴＭＡ）装置（セイコー電子工業製ＴＭＡ／ＳＳ６０００）を用いて窒素ガス雰囲気中、昇温速度２０℃／分で９００℃まで加熱して収縮率を測定した。その結果は、加熱前の圧粉体の厚さを基準にして、図１に示す通りであった。図１から分かるように、８５０℃でも収縮率は１％程度であった。
【００２８】
実施例２
実施例１で用いた微粒の酸化アルミニウムの代わりに微粒の酸化硅素（平均１次粒子径約７ｎｍ、比表面積約３００ｍ2 ／ｇ）を用い、実施例１と同様に処理して、金属銀粒子表面に微粒の酸化硅素が固着された表面修飾銀粉を得た。
【００２９】
この表面修飾銀粉０．５ｇに９８ＭＰａの圧力を加えて直径５ｍｍ、高さ約５ｍｍのペレットに成形した。このペレットを実施例１の場合と同じ装置及び条件を用いて９００℃まで加熱して収縮率を測定した。その結果は、加熱前の圧粉体の厚さを基準にして、図１に示す通りであった。図１から分かるように、８５０℃でも収縮率は３％程度であった。
【００３２】
実施例３
銀粉（ＳＥＭ観察平均径約１μｍ）５００ｇとシリカゾル（日産化学製スノーテックスＯ、ＳｉＯ2 含有率２０質量％、平均粒子径１０ｎｍ）５０ｇとを湿式分散機を用いて充分に分散・混合させた。次いで、加熱しながら良く攪拌し、水分を徐々に気化させ、最後に乾燥粉体を得た。これにより表面にＳｉＯ2 超微粒子が付着している金属銀粒子を得た。これを更にハイブリタイザー（奈良機械製作所製）に投入し、８０００ｒｐｍで５分間循環させて、金属銀粒子表面にＳｉＯ2 超微粒子が固着している表面修飾銀粉を得た。
【００３３】
この表面修飾銀粉０．５ｇに９８ＭＰａの圧力を加えて直径５ｍｍ、高さ約５ｍｍのペレットに成形した。このペレットを実施例１の場合と同じ装置及び条件を用いて９００℃まで加熱して収縮率を測定した。その結果は、加熱前の圧粉体の厚さを基準にして、８５０℃でも収縮率は２％程度であった。
【００３４】
比較例１
実施例１で用いた銀粉と同一の銀粉で、その表面に酸化物又は複合酸化物が固着していない銀粉０．５ｇに９８ＭＰａの圧力を加えて直径５ｍｍ、高さ約５ｍｍのペレットに成形した。このペレットを実施例１の場合と同じ装置及び条件を用いて９００℃まで加熱して収縮率を測定した。その結果は、加熱前の圧粉体の厚さを基準にして、図１に示す通りであった。図１から分かるように、５５０℃付近から熱収縮が生じ、８５０℃では収縮率は６％程度であった。
【００３５】
【発明の効果】
上記のように本発明の表面修飾銀粉は、焼結開始温度が上昇していると共に焼結による熱収縮率が低下しており、ＬＴＣＣ回路基板の形成に用いるのに特に適している。
【図面の簡単な説明】
【図１】 実施例１、実施例２及び比較例１で熱機械分析装置で測定した温度と収縮率との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
Relates to a manufacturing method of the present invention is a surface-modified silver powder, particularly, oxides of certain metallic elements to metallic silver particle surface and / or the composite oxide has adhered, circuit formation using at a temperature below the melting point of silver cermet type paste, in particular LTCC (low-temperature cofired ceramic, low temperature co-fired ceramic) relates to a method for manufacturing a surface-modified silver powder suitable for use in a circuit board forming cermet type paste.
[0002]
[Prior art]
With regard to portable communication terminals and Bluetooth RF circuits, LTCC packages are becoming mainstream in recent years with the aim of miniaturization, high density, and one chip in the near future. In the LTCC package, it is possible to integrate the entire RF circuit into one component by forming passive components inside the ceramic multilayer substrate and mounting the semiconductor.
[0003]
In LTCC packages that are already in practical use, silver or copper is the mainstream because of the importance of electrical characteristics as the wiring material, and a fired paste obtained by kneading these metal powders and organic binders. Generally, it is manufactured by a process of printing on a green sheet by screen printing and simultaneously firing.
[0004]
The characteristics required for the metal powder used in the above-mentioned firing type paste include that there is little aggregation and a uniform particle size so as to increase the accuracy of screen printing and to facilitate the preparation of the firing type paste. In addition, it is required that the thermal shrinkage is small during firing. When the metal powder is silver, the melting point of the silver powder is 960 ° C., but sintering starts from about 500 ° C., and shrinkage starts accordingly. For this reason, when using silver powder as a wiring material, it is necessary to consider the difference in thermal shrinkage behavior between the silver wiring to be formed and the member below it. For the purpose of sufficiently raising the sintering start temperature of silver powder and suppressing thermal shrinkage due to sintering, an inorganic oxide particle is mixed with silver powder to prepare a calcined paste, thereby trying to suppress thermal shrinkage It has been. However, this method requires the addition of a large amount of inorganic oxide particles, and as a result, the electrical characteristics of the formed wiring tend to be impaired.
[0005]
[Problems to be solved by the invention]
In the present invention, the metal oxide and / or composite oxide is uniformly fixed on the surface of each silver powder particle, so that the electric characteristics of the silver powder are not impaired with the minimum amount of metal oxide and / or composite oxide. Surface modification suitable for use in firing pastes for circuit formation, particularly LTCC circuit board formation, which has the effect of suppressing thermal shrinkage due to sintering to the maximum and is used at temperatures below the melting point of silver It has an object to provide a method for producing a silver powder.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above-mentioned problems, the present inventor fixed the above-mentioned surface-modified silver powder by fixing an oxide and / or composite oxide of a specific metal element to the surface of the metal silver particles. The present invention has been completed by finding that the problems can be achieved.
[0009]
That is , the method for producing a surface-modified silver powder of the present invention comprises an oxide and a composite containing at least one metal element belonging to groups 2 to 14 of the periodic table in the range of atomic numbers 12 to 82 on the surface of metal silver particles. At least one selected from the group consisting of oxide ultrafine particles is adhered, and the metallic silver particles to which the ultrafine particles are adhered collide with each other or with other objects to attach the ultrafine particles to the surface of the metallic silver particles. It is made to adhere.
[0010]
Moreover, the method for producing the surface-modified silver powder of the present invention comprises ultrafine particles of an oxide and a composite oxide containing at least one metal element belonging to groups 2 to 14 of the periodic table within the range of atomic numbers 12 to 82. A suspension in which at least one selected from the group is suspended and metallic silver particles are heated while mixing, the medium of the suspension is removed, and the ultrafine particles are deposited on the surface of the metallic silver particles. The ultrafine particles are adhered to the surface of the metallic silver particles by causing the metallic silver particles to which the ultrafine particles are adhered to collide with each other or another object.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The surface-modified silver powder (hereinafter abbreviated as the surface-modified silver powder of the present invention) obtained by the method for producing surface-modified silver powder of the present invention is used to form circuits, for example, internal electrodes and external electrodes of chip components (chip inductors, capacitors, etc.) The average particle diameter of the metallic silver particles as a core is 10 μm or less, preferably 0.1 to 1 μm. Intended for spherical objects. There is no limitation on the method for producing such metal silver particles as the core, and any metal silver particles obtained by any method can be used.
[0012]
In the surface-modified silver powder of the present invention, an oxide containing at least one metal element belonging to Group 2-14 of the periodic table within the range of atomic number 12-82 on the surface of the metal silver particle as described above and composite oxidation At least one selected from the group consisting of objects is fixed. In the surface-modified silver powder of the present invention, the oxide and composite oxide are at least one of metal elements belonging to groups 2-4, 7, 13, and 14 of the periodic table within the range of atomic numbers 12 to 74. Preferably, the oxide and the composite oxide are oxides and composite oxides containing at least one of aluminum, silicon, zirconium, yttrium, magnesium, and lanthanoid elements. Further preferred.
[0013]
Examples of the oxide and composite oxide include MgO, CaO, SrO, BaO, ZnO, Al 2 O 3 , Ga 2 O 3 , Y 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , and Cr 2 O. 3 , MnO 2 , Mn 3 O 4 , Nb 2 O 5 , BaTiO 3 , CaTiO 3 , SrTiO 3 , BaZrO 3 , CaZrO 3 , SrZrO 3 , (Mg, Ca) TiO 3 , (Ba, Ca) (Ti, Zr) ) O 3 , PbTiO 3 , Pb (Zr, Ti) O 3 , (Pb, Ca) TiO 3 , MgAl 2 O 4 , BaTi 4 O 9 , Nd 2 O 3 , Sm 2 O 3 , Dy 2 O 3 , Er 2 O 3 , Ho 2 O 3 and the like can be mentioned, and these oxides and / or composite oxides may be doped with metal oxides such as Nb, W, La, Y, and Mo. These oxides and composite oxides can be used alone or as a mixture.
[0014]
In the surface-modified silver powder of the present invention, the preferred fixing amount of the oxide and / or composite oxide to be fixed varies depending on the difference in the particle size of the metal silver particles, but the fixing amount of the oxide and / or composite oxide ( When used as a mixture, the total fixed amount) (in the present specification, including both of them) is preferably 0.1 to 10% by mass relative to the mass of the metallic silver particles, and more Preferably it is 0.5-8 mass%, More preferably, it is 1-7 mass%. When the total fixing amount is less than 0.1% by mass, the effect of the present invention achieved by the fixing of the oxide and / or composite oxide tends to be insufficient, and conversely exceeds 10% by mass. However, when a wiring is formed using such surface-modified silver powder, the conductivity of the wiring tends to be adversely affected.
[0015]
The surface-modified silver powder of the present invention is suitable for a baking paste for circuit formation, particularly for a baking paste for LTCC circuit board formation. The paste containing the surface-modified silver powder of the present invention must be used at a temperature lower than the melting point of silver, and functions effectively when fired at a temperature of 500 ° C. or higher. Further, when used as a firing paste for forming an LTCC circuit board, it is particularly preferable that the oxide and / or composite oxide fixed to the surface of the metallic silver particles is the same as the composition of the LTCC substrate.
[0016]
The production method of the present invention is a dry fixing method or a semi-dry fixing method in which an aqueous suspension of ultrafine particles of metal oxide or composite oxide is fixed to metal silver particles and dried.
[0017]
In the method for producing the surface-modified silver powder of the present invention when carried out according to the dry fixing method, at least one of the metal elements belonging to Group 2-14 of the periodic table within the atomic number range of 12-82 on the surface of the metal silver particles. At least one selected from the group consisting of oxides containing seeds and ultrafine particles of composite oxide is adhered, and the metallic silver particles to which the ultrafine particles are adhered collide with each other or with other objects. The ultrafine particles can be fixed to the surface of the film.
[0018]
The ultrafine particles of oxides and composite oxides can be uniformly fixed to the surface of the metallic silver particles with a smaller amount as the particle size is smaller. It is more preferable that the thickness is 0.05 μm or less.
[0019]
As a method for fixing ultrafine particles of oxide and / or composite oxide to the surface of metallic silver particles, after mixing metallic silver particles and ultrafine particles of oxide and / or composite oxide, the ultrafine particles are adhered. The metallic silver particles are placed in a device such as an ong mill, a hybridizer, a mechanofusion, a coater, a disperse coat, a jet mizer, a sand mill, or a mix muller, and collide with each other or other objects. The ultrafine particles can be fixed to the surface of the metallic silver particles.
[0020]
In the method for producing the surface-modified silver powder of the present invention when carried out according to the semi-dry fixing method, an oxide containing at least one metal element belonging to Group 2-14 of the periodic table within the range of atomic number 12-82, and A suspension in which at least one selected from the group consisting of ultrafine composite oxide particles is suspended and metallic silver particles are heated while mixing, the medium of the suspension is removed, and the metallic silver The ultrafine particles can be adhered to the surface of the particles, and the metallic silver particles to which the ultrafine particles are adhered can collide with each other or with other objects to fix the ultrafine particles to the surface of the metallic silver particles.
[0021]
The metallic silver particles used in the semi-dry fixing method and the ultrafine particles of oxide and composite oxide may be the same as those used in the dry fixing method. The medium in which the ultrafine particles are suspended is not particularly limited, and generally water, acidic aqueous solution, basic aqueous solution, alcohol, organic solvent, or the like can be used. In this production method, a suspension having a predetermined solid content concentration may be prepared and used, or commercially available silica sol, alumina sol, titania sol, barium titanate sol, etc. may be used to dilute the concentration as necessary. You may adjust and use.
[0026]
EXAMPLES Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to such examples.
Example 1
5 parts by mass of aluminum oxide (average primary particle diameter of about 15 nm, specific surface area of about 100 m 2 / g) was added to 100 parts by mass of silver powder (SEM observation average particle diameter of about 0.5 μm), and the mixture was sufficiently stirred and mixed. As a result, metal silver particles having fine aluminum oxide adhered to the surface of the metal silver particles were obtained. Next, this was put into a hybridizer (manufactured by Nara Machinery Co., Ltd.) and circulated at 8000 rpm for 5 minutes to obtain surface-modified silver powder in which fine aluminum oxide was fixed on the surface of metal silver particles. Even when the surface-modified silver powder was placed in a solvent and stirred, the fine aluminum oxide did not peel from the metal silver particles.
[0027]
A pressure of 98 MPa was applied to 0.5 g of this surface-modified silver powder to form a pellet having a diameter of 5 mm and a height of about 5 mm. The pellets were heated to 900 ° C. at a heating rate of 20 ° C./min in a nitrogen gas atmosphere using a thermomechanical analysis (TMA) apparatus (TMA / SS6000 manufactured by Seiko Denshi Kogyo Co., Ltd.), and the shrinkage rate was measured. The result was as shown in FIG. 1 on the basis of the thickness of the green compact before heating. As can be seen from FIG. 1, the shrinkage rate was about 1% even at 850 ° C.
[0028]
Example 2
Metal silver particles were treated in the same manner as in Example 1 using fine silicon oxide (average primary particle diameter of about 7 nm, specific surface area of about 300 m 2 / g) instead of fine aluminum oxide used in Example 1. A surface-modified silver powder having fine particles of silicon oxide fixed on the surface was obtained.
[0029]
A pressure of 98 MPa was applied to 0.5 g of this surface-modified silver powder to form a pellet having a diameter of 5 mm and a height of about 5 mm. The pellets were heated to 900 ° C. using the same apparatus and conditions as in Example 1 and the shrinkage was measured. The result was as shown in FIG. 1 on the basis of the thickness of the green compact before heating. As can be seen from FIG. 1, the shrinkage rate was about 3% even at 850 ° C.
[0032]
Example 3
Silver powder (SEM observation average diameter of about 1 μm) 500 g and silica sol (Nissan Chemical Snowtex O, SiO 2 content 20 mass%, average particle diameter 10 nm) 50 g were sufficiently dispersed and mixed using a wet disperser. Next, the mixture was stirred well while being heated to gradually evaporate water, and finally a dry powder was obtained. As a result, metallic silver particles having SiO 2 ultrafine particles adhered to the surface were obtained. This was further put into a hybridizer (manufactured by Nara Machinery Co., Ltd.) and circulated at 8000 rpm for 5 minutes to obtain surface-modified silver powder having SiO 2 ultrafine particles fixed on the surface of metal silver particles.
[0033]
A pressure of 98 MPa was applied to 0.5 g of this surface-modified silver powder to form a pellet having a diameter of 5 mm and a height of about 5 mm. The pellets were heated to 900 ° C. using the same apparatus and conditions as in Example 1 and the shrinkage was measured. As a result, the shrinkage was about 2% even at 850 ° C., based on the thickness of the green compact before heating.
[0034]
Comparative Example 1
The same silver powder as used in Example 1 was formed into pellets having a diameter of 5 mm and a height of about 5 mm by applying a pressure of 98 MPa to 0.5 g of silver powder with no oxide or composite oxide fixed on the surface thereof. . The pellets were heated to 900 ° C. using the same apparatus and conditions as in Example 1 and the shrinkage was measured. The result was as shown in FIG. 1 on the basis of the thickness of the green compact before heating. As can be seen from FIG. 1, thermal shrinkage occurred around 550 ° C., and at 850 ° C., the shrinkage rate was about 6%.
[0035]
【The invention's effect】
As described above, the surface-modified silver powder of the present invention is particularly suitable for use in forming an LTCC circuit board because the sintering start temperature is increased and the thermal shrinkage rate due to sintering is decreased.
[Brief description of the drawings]
1 is a graph showing the relationship between temperature and shrinkage measured by a thermomechanical analyzer in Example 1, Example 2, and Comparative Example 1. FIG.
Claims (2)
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| JP2000385067A JP4480884B2 (en) | 1999-12-22 | 2000-12-19 | Method for producing surface-modified silver powder |
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| JP11-364407 | 1999-12-22 | ||
| JP36440799 | 1999-12-22 | ||
| JP2000385067A JP4480884B2 (en) | 1999-12-22 | 2000-12-19 | Method for producing surface-modified silver powder |
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| JP4150638B2 (en) * | 2002-06-28 | 2008-09-17 | 三井金属鉱業株式会社 | Inorganic oxide-coated metal powder and method for producing the inorganic oxide-coated metal powder |
| JP4665130B2 (en) * | 2003-03-03 | 2011-04-06 | 旭硝子株式会社 | Conductive paste and method for manufacturing substrate with conductive layer |
| JP4197151B2 (en) * | 2003-11-27 | 2008-12-17 | 三井金属鉱業株式会社 | Two-layer coated copper powder, method for producing the two-layer coated copper powder, and conductive paste using the two-layer coated copper powder |
| JP4659463B2 (en) * | 2004-01-30 | 2011-03-30 | 東光株式会社 | Multilayer inductor and manufacturing method thereof |
| JP5337928B2 (en) * | 2005-01-05 | 2013-11-06 | ホラデイ、ロバート | Silver / water, silver gel, and silver-based compositions and methods for making and using them |
| JP4694860B2 (en) * | 2005-02-28 | 2011-06-08 | 東光株式会社 | Method for producing laminated beads |
| JP5376109B2 (en) * | 2007-03-30 | 2013-12-25 | 三菱マテリアル株式会社 | Method for producing silver fine particles |
| WO2009054386A1 (en) * | 2007-10-22 | 2009-04-30 | Nippon Chemical Industrial Co., Ltd. | Coated conductive powder and conductive adhesive using the same |
| JP5526698B2 (en) | 2009-10-16 | 2014-06-18 | デクセリアルズ株式会社 | Light reflective conductive particles, anisotropic conductive adhesive, and light emitting device |
| US10636540B2 (en) | 2015-03-27 | 2020-04-28 | Heraeus Deutschland GmbH & Co. KG | Electro-conductive pastes comprising an oxide additive |
| US10056508B2 (en) | 2015-03-27 | 2018-08-21 | Heraeus Deutschland GmbH & Co. KG | Electro-conductive pastes comprising a metal compound |
| JP7109222B2 (en) * | 2018-03-27 | 2022-07-29 | Ｊｘ金属株式会社 | Coated metal powder, method for producing the same, and laminate-molded article using the metal powder |
| CN115815587B (en) * | 2022-12-05 | 2023-11-28 | 深圳众诚达应用材料股份有限公司 | Modified silver powder for laminated inductor inner electrode silver paste and preparation method thereof |
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