JP2002266079A - Method for manufacturing silver coated conductive powder, silver coated conductive powder and electroless plating bath for coating conductive powder - Google Patents

Method for manufacturing silver coated conductive powder, silver coated conductive powder and electroless plating bath for coating conductive powder

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Publication number
JP2002266079A
JP2002266079A JP2001066073A JP2001066073A JP2002266079A JP 2002266079 A JP2002266079 A JP 2002266079A JP 2001066073 A JP2001066073 A JP 2001066073A JP 2001066073 A JP2001066073 A JP 2001066073A JP 2002266079 A JP2002266079 A JP 2002266079A
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JP
Japan
Prior art keywords
silver
conductive powder
electroless
nickel
coated conductive
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
JP2001066073A
Other languages
Japanese (ja)
Inventor
Masami Kaneyoshi
正実 金吉
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.)
Shin Etsu Chemical Co Ltd
Original Assignee
Shin Etsu Chemical 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 Shin Etsu Chemical Co Ltd filed Critical Shin Etsu Chemical Co Ltd
Priority to JP2001066073A priority Critical patent/JP2002266079A/en
Publication of JP2002266079A publication Critical patent/JP2002266079A/en
Pending legal-status Critical Current

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Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing silver coated conductive powder which is capable of forming a uniform silver plating layer having a high adhesion property on a nickel alloy plating layer formed on the surface of a powdery core material even if a cyano compound is not used. SOLUTION: In this method for manufacturing the silver coated conductive powder by treating the surface of the core material consisting of an organic material or inorganic material with an electroless nickel-phosphorus plating liquid, then treating the surface with an electroless silver plating liquid containing a water-soluble silver salt and a complexing agent, an organic compound containing sulfurous acid or a sulfite or imide group or amide group is used as the complexing agent for the electroless silver plating liquid.

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、導電性充填材料等
として使用される、最表面に銀メッキ層を有する銀被覆
導電性粉末およびその製造方法、ならびに導電性粉末被
覆用無電解銀メッキ浴に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver-coated conductive powder having a silver plating layer on the outermost surface, a method for producing the same, and an electroless silver plating bath for coating the conductive powder, which is used as a conductive filling material or the like. About.

【0002】[0002]

【従来の技術】従来から、シリコーンゴム組成物等のゴ
ム組成物と導電性を有する充填材料との混練物を成形す
ることで、当該成形体に導電性を付与する技術が知られ
ている。このような目的で使用される導電性を有する充
填材料として、樹脂粉末や、セラミックス粉末からなる
芯材に、金属の被覆を施したものが開発されており、金
属被膜の形成方法には、主として無電解メッキ法が用い
られている。また、金属被膜の酸化劣化により充填材料
の導電性が低下することを抑制する目的で、金属被膜の
最表面に、さらに金、銀等の酸化されにくい金属の被覆
を形成する試みもなされており、このような例として、
(1)樹脂等の芯材にニッケル被覆を施した後、最表面
に金被覆を施したもの(商品名ブライト、日本化学工業
製)、(2)ガラスビーズに銀メッキを施したもの(東
芝バロティーニ社販売)等が知られている。
2. Description of the Related Art Conventionally, there has been known a technique of imparting conductivity to a molded product by molding a kneaded product of a rubber composition such as a silicone rubber composition and a filler material having conductivity. As a conductive filling material used for such a purpose, a resin powder or a core material made of ceramic powder coated with a metal has been developed. An electroless plating method is used. Attempts have also been made to form a coating of a hard-to-oxidize metal such as gold or silver on the outermost surface of the metal coating for the purpose of suppressing a decrease in the conductivity of the filling material due to oxidative deterioration of the metal coating. For example,
(1) A core material such as resin is coated with nickel and then the outermost surface is coated with gold (trade name: Bright, manufactured by Nippon Chemical Industry). (2) A glass bead is plated with silver (Toshiba Barotini Co.) is known.

【0003】ところで、金被覆を有する充填材料は一般
的に高価であるため、銀被覆の充填材料が望まれている
が、絶縁体(芯材)に触媒付着処理後、直接無電解銀メ
ッキを施したものは、前述のガラスビーズに銀メッキを
施す場合も含めて、銀被覆が不均一になりやすいうえ、
被膜の密着力が弱い等の問題を有している。この問題の
解決策として、芯材表面に他の金属被覆の下地を形成し
た後、その上に無電解銀メッキを行う手法が挙げられ
る。この場合、下地に用いる他の金属としては、ニッケ
ル、銅等が考えられるが、銅と銀とは相互拡散し易いと
いう性質があり、特に、粉末に無電解銀メッキを施す場
合、銀被覆の厚みが薄いため、長期に亘る使用や処理工
程上の加熱等により、銅が表面にまで拡散し、その結
果、表面の銅が酸化されて導電性の低下を招きやすいと
いう問題がある。
[0003] Since a filling material having a gold coating is generally expensive, a filling material having a silver coating is desired. However, after a catalyst is attached to an insulator (core material), electroless silver plating is directly performed. The silver coating tends to be non-uniform, including the case where silver plating is applied to the glass beads described above,
There are problems such as weak adhesion of the coating. As a solution to this problem, there is a method of forming a base of another metal coating on the surface of the core material and then performing electroless silver plating thereon. In this case, nickel, copper, and the like can be considered as other metals used for the underlayer, but copper and silver have a property of easily diffusing each other. Particularly, when electroless silver plating is performed on the powder, silver-coated silver is used. Since the thickness is thin, there is a problem that copper is diffused to the surface due to long-term use or heating in a processing step, and as a result, the copper on the surface is oxidized, which tends to cause a decrease in conductivity.

【0004】このような点から、下地金属としては、銅
に比べて銀との拡散が起こりにくいニッケル(ニッケル
合金)を用いることが好ましいが、ニッケル上に施され
る銀メッキは、一般的に密着性が低いという問題があ
る。このため、上述のような問題があるにも拘わらず、
下地金属には主として銅が用いられているのが現状であ
る。
[0004] From such a point, it is preferable to use nickel (nickel alloy), which is less likely to diffuse with silver than copper, as a base metal, but silver plating applied on nickel is generally used. There is a problem that adhesion is low. For this reason, despite the above-mentioned problems,
At present, copper is mainly used as the base metal.

【0005】一方、上述したニッケル被膜上の銀メッキ
被膜の密着性が低いという問題を解決する方法として、
銀メッキ工程にシアン化銀を用い、銀被覆導電性粉末を
得る方法が、特公平2−47549号公報に開示されて
いる。しかしながら、シアン化合物は、一般的に毒性が
強いため、排水に関する環境保全上の問題、作業者の労
働衛生上の問題等が懸念される。このため、シアン化合
物を用いなくともニッケル合金被覆上に、均一で密着性
の高い無電解銀メッキを行って、銀被覆を有する導電性
粉末を製造できる手法が望まれている。
On the other hand, as a method for solving the problem that the adhesion of the silver plating film on the nickel film is low,
Japanese Patent Publication No. 2-47549 discloses a method for obtaining silver-coated conductive powder using silver cyanide in the silver plating step. However, since cyan compounds are generally highly toxic, there are concerns about environmental issues related to wastewater, occupational health issues for workers, and the like. Therefore, there is a demand for a method capable of producing a conductive powder having a silver coating by performing electroless silver plating with high uniformity on a nickel alloy coating without using a cyanide compound.

【0006】ところで、無電解銀メッキ法のうち、シア
ン化合物を含まないものとしては、(1)硝酸銀および
錯化剤としてアンモニアまたはチオ硫酸イオンの少なく
とも一方を含む、いわゆる置換銀メッキ浴を用いる方
法、(2)硝酸銀、アンモニアに還元剤として酒石酸
塩、糖類等を加える、自己触媒型無電解銀メッキ浴を用
いる方法等が知られている。
Among the electroless silver plating methods, those containing no cyanide include (1) a method using a so-called substituted silver plating bath containing silver nitrate and at least one of ammonia and thiosulfate ion as a complexing agent. (2) A method using an autocatalytic electroless silver plating bath in which a tartrate salt, a saccharide, or the like is added as a reducing agent to silver nitrate or ammonia is known.

【0007】[0007]

【発明が解決しようとする課題】しかしながら、上述の
シアン化合物を用いない無電解銀メッキ手法を、ニッケ
ル被膜を有する粉末状芯材に用いた場合、浴分解を起こ
して芯材表面以外のところに銀が析出したり、銀の析出
が実質的にきわめて起こりにくいという問題があった。
また、たとえ銀が芯材表面に均一に析出したとしても、
シアン化銀を使用したものに比べ、銀メッキ被膜とニッ
ケル被膜との密着性が著しく低いという問題があった。
However, when the above-described electroless silver plating method without using a cyanide is used for a powdery core material having a nickel coating, bath decomposition occurs to cause a problem other than the surface of the core material. There has been a problem that silver is deposited or silver deposition is extremely unlikely to occur.
Also, even if silver is uniformly deposited on the surface of the core material,
There was a problem that the adhesion between the silver plating film and the nickel film was significantly lower than that using silver cyanide.

【0008】本発明は、このような事情に鑑みてなされ
たものであり、シアン化合物を使用しなくとも粉末状の
芯材表面に形成されたニッケル−リンメッキ層上に均一
で密着性の高い銀メッキ層を形成できる銀被覆導電性粉
末の製造方法、これによって得られる銀被覆導電性粉
末、および導電性粉末被覆用無電解銀メッキ浴を提供す
ることを目的とする。
The present invention has been made in view of such circumstances, and a silver alloy having a uniform and high adhesion on a nickel-phosphorus plating layer formed on a powdery core material surface without using a cyanide compound. An object of the present invention is to provide a method for producing a silver-coated conductive powder capable of forming a plating layer, a silver-coated conductive powder obtained by the method, and an electroless silver plating bath for coating the conductive powder.

【0009】[0009]

【課題を解決するための手段及び発明の実施の形態】本
発明者らは、上記目的を達成するために鋭意検討を行っ
た結果、芯材表面を無電解ニッケル−リンメッキ液で処
理した後、水溶性銀塩、および錯化剤として、亜硫酸も
しくはその塩、またはアミド基もしくはイミド基を有す
る有機化合物を含有する無電解銀メッキ液で処理するこ
とで、シアン化合物を使用しなくともニッケル−リン合
金メッキ層上に均一で密着性の高い無電解銀メッキ層を
形成できることを見いだすとともに、これにより表面に
銀メッキ層を有し、導電性に優れる銀被覆導電性粉末を
得ることができることを見いだし、本発明を完成した。
Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, after treating the surface of the core material with an electroless nickel-phosphorus plating solution, By treating with a water-soluble silver salt and, as a complexing agent, an electroless silver plating solution containing sulfurous acid or a salt thereof, or an organic compound having an amide group or an imide group, nickel-phosphorus can be obtained without using a cyanide compound. We have found that a uniform and highly adherent electroless silver plating layer can be formed on the alloy plating layer, and that it is possible to obtain a silver-coated conductive powder having a silver plating layer on the surface and excellent conductivity. Thus, the present invention has been completed.

【0010】すなわち、本発明は、(1)有機材料また
は無機材料からなる芯材表面を無電解ニッケル−リンメ
ッキ液で処理した後、水溶性銀塩および錯化剤を含有す
る無電解銀メッキ液で処理する銀被覆導電性粉末の製造
方法であって、前記無電解銀メッキ液の錯化剤は、亜硫
酸もしくは亜硫酸塩、またはイミド基もしくはアミド基
を有する有機化合物であることを特徴とする銀被覆導電
性粉末の製造方法、(2)前記無電解銀メッキ液中にホ
スフィン酸、ホスフィン酸塩、またはヒドラジンを含む
ことを特徴とする上記銀被覆導電性粉末の製造方法、
(3)有機材料または無機材料からなる芯材表面に形成
されたニッケル−リンメッキ層と、このニッケル−リン
メッキ層の上に形成された銀メッキ層とを有し、上記方
法によって得られる体積抵抗率が20mΩcm以下であ
ることを特徴とする銀被覆導電性粉末、(4)前記銀メ
ッキ層の厚みが100nm以下であることを特徴とする
上記銀被覆導電性粉末、(5)水溶性銀塩および錯化剤
を含んでなる導電性粉末被覆用無電解銀メッキ浴であっ
て、前記錯化剤が亜硫酸もしくは亜硫酸塩、またはイミ
ド基もしくはアミド基を有する有機化合物であることを
特徴とする導電性粉末被覆用無電解銀メッキ浴を提供す
る。
That is, the present invention provides (1) an electroless silver plating solution containing a water-soluble silver salt and a complexing agent after treating the surface of a core material made of an organic material or an inorganic material with an electroless nickel-phosphorus plating solution. Wherein the complexing agent for the electroless silver plating solution is a sulfurous acid or a sulfite, or an organic compound having an imide group or an amide group. (2) a method for producing the silver-coated conductive powder, wherein the electroless silver plating solution contains phosphinic acid, a phosphinate, or hydrazine;
(3) Volume resistivity obtained by the above method, having a nickel-phosphorus plating layer formed on the surface of a core material made of an organic material or an inorganic material, and a silver plating layer formed on the nickel-phosphorus plating layer Is not more than 20 mΩcm, (4) the silver-coated conductive powder is characterized in that the thickness of the silver plating layer is 100 nm or less, (5) a water-soluble silver salt, An electroless silver plating bath for coating a conductive powder comprising a complexing agent, wherein the complexing agent is an organic compound having a sulfite or a sulfite, or an imide group or an amide group. An electroless silver plating bath for powder coating is provided.

【0011】以下、本発明について更に詳しく説明す
る。本発明に係る銀被覆導電性粉末の製造方法は、有機
材料または無機材料からなる芯材表面を無電解ニッケル
−リンメッキ液で処理した後、水溶性銀塩および錯化剤
を含有する無電解銀メッキ液で処理する銀被覆導電性粉
末の製造方法であって、前記錯化剤が、亜硫酸もしくは
亜硫酸塩、またはイミド基もしくはアミド基を有する有
機化合物であることを特徴とする。
Hereinafter, the present invention will be described in more detail. The method for producing a silver-coated conductive powder according to the present invention comprises the steps of: treating a surface of a core material made of an organic material or an inorganic material with an electroless nickel-phosphorus plating solution, and then electroless silver containing a water-soluble silver salt and a complexing agent. A method for producing a silver-coated conductive powder to be treated with a plating solution, wherein the complexing agent is sulfurous acid or a sulfite, or an organic compound having an imide group or an amide group.

【0012】ここで、芯材としては、特に限定はなく、
金属、樹脂、無機物等の有機材料または無機材料の中か
ら、任意に選択することができる。この際、製品である
充填材料の用途、使用形態等を考慮して最適なものを選
択することとなる。例えば、比重が小さいことが重要で
ある場合、樹脂、または酸化珪素もしくは酸化アルミニ
ウム等の軽元素無機化合物を用いることが好適である。
また、導電性を重視する場合、金属粉を用いることが好
適である。さらに、ゴム組成物や樹脂組成物に混練して
用いる充填材料において、ある程度の弾性を有すること
が必要な用途、使用形態の場合には、樹脂を用いること
が好適であり、一方、剛性を有することが必要な用途等
であり、しかも比重が小さい方がよい場合には、無機化
合物を用いることが好適である。
Here, the core material is not particularly limited.
The material can be arbitrarily selected from organic materials or inorganic materials such as metals, resins, and inorganic substances. At this time, the most suitable one will be selected in consideration of the use of the filling material, which is the product, the form of use, and the like. For example, when it is important that the specific gravity is small, it is preferable to use a resin or a light element inorganic compound such as silicon oxide or aluminum oxide.
When importance is placed on conductivity, it is preferable to use metal powder. Furthermore, in a filling material used by kneading with a rubber composition or a resin composition, in applications where it is necessary to have a certain degree of elasticity, in the case of a use form, it is preferable to use a resin, while having a rigidity. It is preferable to use an inorganic compound when it is a use or the like in which the specific gravity is required to be small.

【0013】上記芯材の粒径は、用途、使用形態等に応
じて適宜設定すればよく、例えば、ゴム組成物等に混練
して用いる場合、150μmを超える粒子はゴムや樹脂
からの脱落を起こしやすいため、平均粒径150μm以
下が好ましく、より好ましくは、5〜100μmの平均
粒径のものである。また、芯材の形状も、用途、使用形
態等に応じて適宜設定すればよく、例えば、導電性塗料
の充填材料として用いる場合には、扁平形状のものが好
ましく、ゴム等の充填材料として用いる場合には、混練
の際に均一に分散させるということを考慮すると、球ま
たは球に近い形状のものが好ましい。
The particle size of the above-mentioned core material may be appropriately set according to the intended use, use form and the like. For example, when kneaded with a rubber composition or the like, particles exceeding 150 μm will not fall off from the rubber or resin. The average particle diameter is preferably 150 μm or less, more preferably 5 to 100 μm, because it easily occurs. In addition, the shape of the core material may be appropriately set according to the application, the usage form, and the like. For example, when used as a filling material for a conductive paint, a flat shape is preferable and used as a filling material such as rubber. In this case, a sphere or a shape close to a sphere is preferable in consideration of uniform dispersion during kneading.

【0014】芯材の表面には、無電解メッキ法によりニ
ッケル−リン合金メッキ層を形成するが、この際、後述
する無電解ニッケルメッキ液に所定温度で触れさせるだ
けで無電解メッキ反応が開始されにくい場合には、パラ
ジウム等の触媒活性を持つ金属を微量担持処理する等の
前処理を行うことにより、メッキ反応が起こり易いよう
にすることが好ましい。このような触媒金属の担持にあ
たっては、公知の方法を採用し得、被メッキ物に用いら
れる公知の活性化処理を芯材の種類に応じて適宜選択し
て行えばよい。
A nickel-phosphorus alloy plating layer is formed on the surface of the core material by an electroless plating method. At this time, the electroless plating reaction is started only by touching an electroless nickel plating solution described later at a predetermined temperature. If it is difficult to carry out the plating, it is preferable to perform a pretreatment such as carrying a trace amount of a metal having catalytic activity such as palladium so that the plating reaction can easily occur. In carrying such a catalyst metal, a known method can be adopted, and a known activation treatment used for the object to be plated may be appropriately selected and performed according to the type of the core material.

【0015】具体例を挙げれば、芯材として絶縁体を用
いる場合には、(1)従来公知の塩化スズ(II)溶液
に芯材を浸した後、塩化パラジウム(II)溶液に浸す
方法、(2)塩化スズ(II)と塩化パラジウム(I
I)の混合溶液を用いる方法等を採用することができ
る。また、上述した触媒を芯材に付着し易くする方法と
しては、(1)芯材を適当な薬剤、例えば、強アルカ
リ、鉱酸、またはクロム酸等、で短時間エッチングする
方法、(2)触媒金属に対して親和性を有する官能基
と、芯材に対して親和性を有する官能基との両方を有す
る薬剤、例えば、アミノ基を有するシランカップリング
剤等、で処理する方法、(3)プラズマ処理等の機械的
処理を行う方法、等を適宜採用することもできる。
[0015] Specifically, when an insulator is used as the core material, (1) a method in which the core material is immersed in a conventionally known tin (II) chloride solution and then immersed in a palladium (II) chloride solution; (2) Tin (II) chloride and palladium chloride (I
A method using the mixed solution of I) and the like can be adopted. Further, as a method for making the above-mentioned catalyst easily adhere to the core material, (1) a method in which the core material is etched for a short time with an appropriate agent, for example, a strong alkali, a mineral acid, or chromic acid; A method of treating with a chemical having both a functional group having an affinity for a catalytic metal and a functional group having an affinity for a core material, for example, a silane coupling agent having an amino group, (3) ) A method of performing a mechanical treatment such as a plasma treatment may be appropriately adopted.

【0016】ニッケル−リン合金メッキ層を形成するた
めに用いられる無電解ニッケルメッキ液としては、ホス
フィン酸またはその塩を還元剤として含有する公知の組
成のものを使用することができ、市販品も使用すること
ができる。また、メッキ条件も公知の条件を採用するこ
とができる。上記無電解ニッケル液から得られるニッケ
ル−リン合金メッキ層中のリン含有量は、0〜20重量
%の範囲で任意に設定することができるが、2〜15重
量%であることが好ましく、6〜14重量%であること
がより好ましい。また、ニッケル−リン合金メッキ層の
厚みは50〜500nmが好ましく、より好ましくは7
5〜400nmである。上記厚みが50nmより薄い場
合、十分な強度のメッキ層が得られない虞があり、一
方、500nmより厚くしても利点は少なく、原料費が
増えるため、コスト的に得策と言い難い。
As the electroless nickel plating solution used for forming the nickel-phosphorus alloy plating layer, a known composition containing phosphinic acid or a salt thereof as a reducing agent can be used, and commercially available products are also available. Can be used. Known plating conditions can also be adopted. The phosphorus content in the nickel-phosphorus alloy plating layer obtained from the electroless nickel solution can be arbitrarily set in the range of 0 to 20% by weight, but is preferably 2 to 15% by weight, and is preferably 6 to 15% by weight. More preferably, it is で 14% by weight. The thickness of the nickel-phosphorus alloy plating layer is preferably 50 to 500 nm, more preferably 7 to 500 nm.
5 to 400 nm. When the thickness is less than 50 nm, there is a possibility that a plating layer with sufficient strength may not be obtained. On the other hand, when the thickness is more than 500 nm, there are few advantages and the cost of raw materials increases.

【0017】本発明の無電解銀メッキ液(導電性粉末被
覆用無電解メッキ浴)としては、一般の無電解銀メッキ
液と同様に、銀イオン源としての水溶性銀塩と、銀イオ
ンを安定して溶解させるための錯化剤とを含むものを用
いる。ここで、水溶性銀塩としては、水溶性を示すもの
であれば特に限定はなく、公知の硝酸銀、硫酸銀等を用
いることができるが、水への溶解性を考慮すると、硝酸
銀を用いることが好ましい。なお、銀イオンの濃度は、
0.005〜0.2mol/dm3程度であり、特に
0.01〜0.1mol/dm3が好ましい。銀イオン
濃度が0.2mol/dm3より高い場合、被メッキ粉
体の表面以外に金属銀の析出がおこり易くなる虞があ
る。一方、銀イオン濃度が0.005mol/dm3
り低い場合、液量が多くなりすぎて生産性の低下を招く
虞があるとともに、反応速度の低下を招く虞がある。
As the electroless silver plating solution of the present invention (electroless plating bath for coating conductive powder), a water-soluble silver salt as a silver ion source and a silver ion are used in the same manner as a general electroless silver plating solution. One containing a complexing agent for stably dissolving is used. Here, the water-soluble silver salt is not particularly limited as long as it shows water solubility, and known silver nitrate, silver sulfate and the like can be used.However, in consideration of solubility in water, silver nitrate is used. Is preferred. The concentration of silver ions is
It is about 0.005 to 0.2 mol / dm 3 , and particularly preferably 0.01 to 0.1 mol / dm 3 . When the silver ion concentration is higher than 0.2 mol / dm 3, there is a possibility that deposition of metallic silver is likely to occur on the surface of the powder to be plated. On the other hand, when the silver ion concentration is lower than 0.005 mol / dm 3 , the amount of the solution becomes too large, which may cause a decrease in productivity and a decrease in the reaction rate.

【0018】また、錯化剤としては、亜硫酸もしくは亜
硫酸塩、またはイミド基もしくはアミド基を有する有機
化合物を用いることが必要である。ここで、亜硫酸塩
は、亜硫酸水素イオン源となるものである。亜硫酸塩と
しては、亜硫酸アルカリ塩(正塩および酸性塩)を用い
ることができ、取り扱い易さおよびコスト等を考慮する
と、特に亜硫酸ナトリウムを用いることが好ましい。
As the complexing agent, it is necessary to use sulfurous acid or a sulfite, or an organic compound having an imide group or an amide group. Here, the sulfite serves as a hydrogen sulfite ion source. Alkali sulfites (normal and acidic salts) can be used as the sulfite, and sodium sulfite is particularly preferably used in consideration of ease of handling and cost.

【0019】一方、イミド基またはアミド基を有する有
機化合物としては、錯化剤として作用するものであれば
特に限定はなく、ホルムアミド、アセトアミド、オキサ
ミン酸、コハク酸イミド等を用いることができ、このう
ちアセトアミド、コハク酸イミドが好ましく、特にコハ
ク酸イミドが最適である。上記錯化剤の配合量として
は、銀イオンに対して、0.8〜10倍モルが好まし
く、より好ましくは2〜6倍モルである。錯化剤の量が
0.8倍モルより少ない場合、銀イオンを安定に溶解さ
せる効果が不十分となる虞があり、一方、10倍モルよ
り多くしても、それ以上の効果が得られない虞があるば
かりか、コスト高につながり不経済となる。
On the other hand, the organic compound having an imide group or an amide group is not particularly limited as long as it functions as a complexing agent. For example, formamide, acetamide, oxamic acid, succinimide and the like can be used. Of these, acetamide and succinimide are preferred, and succinimide is particularly optimal. The amount of the complexing agent is preferably 0.8 to 10 moles, more preferably 2 to 6 moles, per silver ion. When the amount of the complexing agent is less than 0.8 mole, the effect of stably dissolving silver ions may be insufficient. On the other hand, when the amount is more than 10 moles, a further effect can be obtained. Not only is there a possibility that it will not occur, but it will also lead to higher costs and become uneconomical.

【0020】なお、上述した錯化剤と併用して、クエン
酸、リンゴ酸、グリコール酸等のオキシカルボン酸やそ
の水溶性塩、イミダゾールおよびその誘導体等のその他
の錯化剤を用いてもよく、その配合量としては、銀イオ
ンに対して10倍モル以下が好ましく、特に0.1〜6
倍モルがより好ましい。これらは、置換型無電解銀メッ
キにおけるニッケルの溶出をほどよく、しかも穏やかに
促進するとともに、溶出後のニッケルを安定化させて共
析するのを防ぐのに有効である。
In addition, other complexing agents such as oxycarboxylic acids such as citric acid, malic acid and glycolic acid, water-soluble salts thereof, imidazole and derivatives thereof may be used in combination with the above-mentioned complexing agents. The compounding amount thereof is preferably not more than 10 times mol with respect to silver ions, particularly 0.1 to 6 mol.
Double molar is more preferred. These are effective in moderately and moderately promoting the elution of nickel in the substitutional electroless silver plating, and are effective in stabilizing the eluted nickel to prevent eutectoid.

【0021】さらに、上記無電解銀メッキ液には、水溶
性銀塩および錯化剤に加えて還元剤として、ホスフィン
酸、ホスフィン酸塩、またはヒドラジンを含むことが好
ましい。ここで、ホスフィン酸またはホスフィン酸塩と
しては、特に限定はないが、ホスフィン酸ナトリウムが
最適であり、その配合量としては、銀イオンに対して5
倍モル以下が好ましく、特に0.1〜3倍モルがより好
ましい。一方、ヒドラジンの配合量としては、銀イオン
に対して20倍モル以下、特に0.1〜15倍モルがよ
り好ましい。これらの還元剤の配合量が上記上限値を超
えると、メッキ液が不安定になる虞がある。これらの還
元剤は、下地であるニッケル−リン合金の触媒作用の下
に、溶液中の銀イオンを還元して金属銀を析出し易くす
る作用をし、ニッケル−リン合金メッキ層上を均一に銀
メッキ層で覆うのに好適なものである。すなわち、析出
した金属銀よりもニッケル−リン合金の方が還元剤に対
する触媒作用が強いので、ニッケル−リン合金メッキ層
上に均一な銀メッキ層が形成されることとなる。
Further, the electroless silver plating solution preferably contains a phosphinic acid, a phosphinate, or hydrazine as a reducing agent in addition to the water-soluble silver salt and the complexing agent. Here, the phosphinic acid or phosphinate is not particularly limited, but sodium phosphinate is most suitable.
The molar amount is preferably not more than 1 mole, and particularly preferably 0.1 to 3 moles. On the other hand, the amount of hydrazine to be added is preferably 20 times or less, more preferably 0.1 to 15 times, the mole of silver ions. If the amount of these reducing agents exceeds the above upper limit, the plating solution may become unstable. These reducing agents act to reduce silver ions in the solution and facilitate the precipitation of metallic silver under the catalytic action of the underlying nickel-phosphorus alloy, and to uniformly deposit on the nickel-phosphorus alloy plating layer. It is suitable for covering with a silver plating layer. That is, since the nickel-phosphorus alloy has a stronger catalytic effect on the reducing agent than the precipitated metallic silver, a uniform silver plating layer is formed on the nickel-phosphorus alloy plating layer.

【0022】上記無電解銀メッキ液には、さらに必要に
応じ、緩衝剤などの公知の成分を配合することができる
が、本発明の無電解銀メッキはシアン化合物を含まない
ものである。また、本発明の無電解銀メッキ液のpH
は、5.0〜10.0、特に6.0〜9.0とすること
が好ましい。pHが低すぎると、反応が起こりにくい虞
があり、pHが高すぎると、メッキ液が不安定になる虞
がある。
The electroless silver plating solution may further contain a known component such as a buffer, if necessary. However, the electroless silver plating of the present invention does not contain a cyanide compound. Further, the pH of the electroless silver plating solution of the present invention
Is preferably 5.0 to 10.0, particularly preferably 6.0 to 9.0. If the pH is too low, the reaction may not easily occur, and if the pH is too high, the plating solution may be unstable.

【0023】上記無電解銀メッキを行う温度は、0〜8
0℃が好ましく、より好ましくは15〜70℃である。
銀メッキ温度が0℃よりも低い場合、析出速度が遅すぎ
て生産性が低下する虞があり、一方、銀メッキ温度が8
0℃よりも高い場合、反応が激しすぎて均一な銀メッキ
層が得られない虞がある。また、この際の反応時間は、
予め実験等を行って所望の析出量が得られる時間に設定
すればよいが、通常5〜60分程度であり、好ましくは
7〜40分である。
The temperature at which the electroless silver plating is performed is 0 to 8
0 ° C is preferable, and more preferably 15 to 70 ° C.
If the silver plating temperature is lower than 0 ° C., the deposition rate may be too slow and the productivity may be reduced.
If the temperature is higher than 0 ° C., the reaction may be so vigorous that a uniform silver plating layer may not be obtained. The reaction time at this time is
The time may be set in advance by conducting an experiment or the like to obtain a desired amount of deposition, but is usually about 5 to 60 minutes, preferably 7 to 40 minutes.

【0024】上記無電解銀メッキ液を用いて被メッキ粉
体(ニッケル−リン合金メッキが施された芯材)をメッ
キする方法は、特に限定されるものではない。例えば、
(1)予め金属イオン、還元剤、錯化剤、および緩衝剤
等を混合し、pHおよび温度を調整した無電解銀メッキ
液に被メッキ粉体を直接投入する方法、(2)同様にし
て調整した無電解銀メッキ液に、被メッキ粉体を水に分
散させたスラリーを投入する方法、(3)メッキ成分の
一部を除いて調整した溶液に、被メッキ粉体を分散させ
た後、残りのメッキ成分を添加する方法、等を適宜選択
することができる。
The method of plating the powder to be plated (core material plated with nickel-phosphorus alloy) using the above electroless silver plating solution is not particularly limited. For example,
(1) A method of mixing a metal ion, a reducing agent, a complexing agent, a buffering agent, and the like in advance, and directly charging the powder to be plated into an electroless silver plating solution whose pH and temperature have been adjusted; A method in which a slurry obtained by dispersing the powder to be plated in water is added to the adjusted electroless silver plating solution. (3) After dispersing the powder to be plated in the adjusted solution by removing some of the plating components The method of adding the remaining plating components can be appropriately selected.

【0025】上記方法により得られた銀被覆導電性粉末
は、体積抵抗率が20mΩcm以下と導電性に優れてお
り、シリコーンゴム組成物、エポキシ樹脂組成物等の各
種ゴム、樹脂組成物の導電性充填材料、導電性塗料の分
散質として好適に使用することができる。
The silver-coated conductive powder obtained by the above method has excellent volume conductivity of not more than 20 mΩcm, and is excellent in conductivity of various rubbers such as silicone rubber composition and epoxy resin composition, and resin composition. It can be suitably used as a filler or as a dispersoid in a conductive paint.

【0026】なお、体積抵抗率が20mΩcmを超える
と、導電性に劣るため、導電性粉末として適さないこと
となる。また、体積抵抗率の下限値は、特に限定され
ず、導電性の点からは低いほど好ましいが、通常0.1
mΩcm以上である。
When the volume resistivity exceeds 20 mΩcm, the conductivity is poor, so that it is not suitable as a conductive powder. The lower limit of the volume resistivity is not particularly limited, and is preferably lower from the viewpoint of conductivity.
mΩcm or more.

【0027】また、上記銀被覆導電性粉末の銀メッキ層
の厚みは、粉末の粒径、形状、化学分析による銀の含有
量、各メッキ層構成成分および芯材の比重から計算され
る厚みで100nm以下であることが好ましく、より好
ましくは5〜100nm、特に10〜100nmである
ことが好ましい。銀メッキ層の厚みが100nmを超え
ると、比重が大きくなる上、高価格にならざるを得ない
ため、コスト的に不利である。また、5nm未満の場
合、緻密で連続した銀メッキ層が得られない虞があり、
その結果、十分な耐酸化性および導電性が発揮されない
虞がある。
The thickness of the silver plating layer of the silver-coated conductive powder is a thickness calculated from the particle size and shape of the powder, the silver content by chemical analysis, the components of each plating layer and the specific gravity of the core material. It is preferably 100 nm or less, more preferably 5 to 100 nm, particularly preferably 10 to 100 nm. If the thickness of the silver plating layer exceeds 100 nm, the specific gravity increases and the price must be high, which is disadvantageous in terms of cost. If it is less than 5 nm, a dense and continuous silver plating layer may not be obtained,
As a result, sufficient oxidation resistance and conductivity may not be exhibited.

【0028】[0028]

【実施例】以下、実施例および比較例を挙げて、本発明
をより具体的に説明するが、本発明は、下記の実施例に
限定されるものではない。
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

【0029】[実施例1] [1]触媒付着 平均粒径約10μmの球状酸化珪素粉末(商品名シリカ
エースUS−10、三菱レイヨン製)30gを秤量し、
アミノアルキルシランカップリング剤(商品名KBE9
03、信越化学工業製)0.3gを溶解した水溶液12
0cm3に添加し、室温で10分間撹拌した。ここへ、
濃塩酸30cm3、および塩化パラジウム(PdCl2
0.09mol/dm3、塩化スズ(SnCl2)2.6
mol/dm3、塩化水素3.5mol/dm3を含む水
溶液0.15cm3を加え、さらに10分間撹拌を続け
た。この混合物から粉末成分をブフナー漏斗で濾別し、
濾別した粉末に濃度1mol/dm3の希塩酸150c
3を振り掛け洗浄した後、さらに水100cm3で洗浄
し、触媒が付着した酸化珪素粉末を得た。
[Example 1] [1] Attachment of catalyst 30 g of spherical silicon oxide powder (trade name: Silica Ace US-10, manufactured by Mitsubishi Rayon) having an average particle diameter of about 10 µm was weighed,
Aminoalkylsilane coupling agent (brand name KBE9)
03, manufactured by Shin-Etsu Chemical Co., Ltd.)
0 cm 3 and stirred at room temperature for 10 minutes. Here,
Concentrated hydrochloric acid 30 cm 3 , and palladium chloride (PdCl 2 )
0.09 mol / dm 3 , tin chloride (SnCl 2 ) 2.6
mol / dm 3, an aqueous solution 0.15 cm 3 containing hydrogen chloride 3.5 mol / dm 3 was added, stirring was continued for an additional 10 minutes. The powder component was filtered from this mixture with a Buchner funnel,
Dilute hydrochloric acid 150c with a concentration of 1 mol / dm 3 was added to the filtered powder.
After washing by spraying with m 3 , washing was further performed with 100 cm 3 of water to obtain a silicon oxide powder to which a catalyst had adhered.

【0030】[2]ニッケルメッキ 上述のようにして得られた触媒付着粉末を、水135c
3に加えて撹拌分散し、スラリーとした。これとは別
に、5リットルビーカーに無電解ニッケルメッキ液濃縮
液A(商品名トップニコロンF−153A、奥野製薬工
業製)333cm3、同濃縮液B(商品名トップニコロ
ンF−153B、奥野製薬工業製)667cm3、純水
3.0dm3を加えて混合し、温度を63℃に調整して
メッキ浴とした。このメッキ浴を撹拌した状態で、上記
で調製したスラリーを添加した。撹拌を続け、温度を保
ったまま20分間反応させた。反応後、ブフナー漏斗で
ニッケル−リンメッキ層が形成された粉末を濾別し、水
約1dm3を振り掛け洗浄した後、当該粉末をかき集
め、再び水105cm3を加えて撹拌分散し、スラリー
とした。
[2] Nickel plating The catalyst-adhered powder obtained as described above was
m 3 , and dispersed by stirring. Separately, in a 5 liter beaker, 333 cm 3 of electroless nickel plating solution concentrate (trade name: Top Nicolon F-153A, manufactured by Okuno Pharmaceutical), and the concentrate B (trade name: Top Nicolon F-153B, Okuno) 667 cm 3 and pure water 3.0 dm 3 were added and mixed, and the temperature was adjusted to 63 ° C. to form a plating bath. While the plating bath was being stirred, the slurry prepared above was added. Stirring was continued, and the reaction was continued for 20 minutes while maintaining the temperature. After the reaction, the nickel on a Buchner funnel - was filtered off powder phosphorous plating layer is formed, after washing sprinkled water about 1 dm 3, raking the powder, and stirred dispersion was added again water 105 cm 3, to form a slurry.

【0031】[3]銀メッキ 硝酸銀4.25gを純水1.18dm3に室温で溶解し
た溶液に、亜硫酸ナトリウム16.8gを加えて溶解し
た。当初生成した沈殿が完全に溶解したのを確認した
後、クエン酸三ナトリウム2水和物35.3g、クエン
酸1水和物2.80gを溶解した。この溶液を撹拌しな
がら加熱して温度を66℃に保った。ここへ、上記
[2]で得られたスラリーを注ぎ、13分間撹拌し続け
た。その後、ブフナー漏斗で濾別して粉末を分離し、分
離した粉末に純水約1dm3を振り掛け洗浄した。洗浄
後、粉末をかき集めてシャーレにとり、庫内温度40℃
の真空乾燥機で2時間乾燥し、銀被覆導電性粉末40.
4gを得た。
[3] Silver plating To a solution of 4.25 g of silver nitrate dissolved in 1.18 dm 3 of pure water at room temperature, 16.8 g of sodium sulfite was added and dissolved. After confirming that the initially generated precipitate was completely dissolved, 35.3 g of trisodium citrate dihydrate and 2.80 g of citric acid monohydrate were dissolved. The solution was heated with stirring to maintain the temperature at 66 ° C. To this, the slurry obtained in the above [2] was poured, and stirring was continued for 13 minutes. Thereafter, the powder was separated by filtration with a Buchner funnel, and the separated powder was sprinkled with about 1 dm 3 of pure water for washing. After washing, scrape the powder, put it in a petri dish, and keep the inside temperature at 40 ° C.
Dried in a vacuum dryer for 2 hours to obtain a silver-coated conductive powder.
4 g were obtained.

【0032】[実施例2] [1]触媒付着、[2]ニッケルメッキを実施例1と同
様に行った。 [3]銀メッキ 硝酸銀4.72gを純水1.16dm3に室温で溶解し
た溶液に、亜硫酸ナトリウム19.1gを加えて溶解し
た。当初生成した沈殿が完全に溶解したのを確認した。
この液を撹拌しながら加熱して46℃に保った。ここ
へ、上記実施例1[2]で得られたスラリーを注ぎ、均
一化したところで直ちに3.6mol/dm3のヒドラ
ジン水溶液133cm3を加え、温度を保ちながら13
分間撹拌し続けた。その後、実施例1と同様に濾過、水
洗、真空乾燥し、銀被覆導電性粉末44.6gを得た。
[Example 2] [1] Catalyst deposition and [2] nickel plating were performed in the same manner as in Example 1. [3] Silver plating To a solution of 4.72 g of silver nitrate in 1.16 dm 3 of pure water at room temperature, 19.1 g of sodium sulfite was added and dissolved. It was confirmed that the initially formed precipitate was completely dissolved.
The solution was heated with stirring and maintained at 46 ° C. To this, the slurry obtained in Example 1 [2] was poured, and immediately after the mixture was homogenized, 133 cm 3 of a 3.6 mol / dm 3 hydrazine aqueous solution was added.
Stirring continued for minutes. Thereafter, filtration, washing with water, and vacuum drying were performed in the same manner as in Example 1 to obtain 44.6 g of a silver-coated conductive powder.

【0033】[実施例3] [1]触媒付着、[2]ニッケルメッキを実施例1と同
様に行った。 [3]銀メッキ 硝酸銀4.72gを純水2.14dm3に室温で溶解し
た溶液に、コハク酸イミド13.9g、およびイミダゾ
ール9.53gを加えて溶解した。当初生成した沈殿が
完全に溶解したのを確認した。この液を撹拌しながら加
熱して46℃に保った。ここへ、上記実施例1[2]で
得られたスラリーを注ぎ、さらに温度を保ちながら15
分間撹拌し続けた。その後、実施例1と同様に濾過、水
洗、真空乾燥し、銀被覆導電性粉末38.4gを得た。
Example 3 [1] Catalyst deposition and [2] Nickel plating were performed in the same manner as in Example 1. [3] Silver plating To a solution of 4.72 g of silver nitrate in 2.14 dm 3 of pure water at room temperature, 13.9 g of succinimide and 9.53 g of imidazole were added and dissolved. It was confirmed that the initially formed precipitate was completely dissolved. The solution was heated with stirring and maintained at 46 ° C. To this, the slurry obtained in Example 1 [2] was poured, and while keeping the temperature,
Stirring continued for minutes. Thereafter, filtration, washing with water and vacuum drying were performed in the same manner as in Example 1 to obtain 38.4 g of silver-coated conductive powder.

【0034】[実施例4] [1]触媒付着を実施例1と同様に行った。 [2]ニッケルメッキ 上述のようにして得られた触媒付着酸化珪素粉末を、水
135cm3に加えて撹拌分散し、スラリーとした。こ
れとは別に、5リットルビーカーに無電解ニッケルメッ
キ液濃縮液(商品名シューマーS−680、日本カニゼ
ン製)850cm3、純水3.96dm3を加えて混合
し、温度を43℃に調整してメッキ浴とした。このメッ
キ浴を撹拌した状態で、上記で調製したスラリーを添加
した。撹拌を続け、温度を保ったまま40分間反応させ
た。反応後、ブフナー漏斗でニッケル−リンメッキ層が
形成された粉末を濾別し、水約1dm3を振り掛け洗浄
した後、当該粉末をかき集め、再び水105cm3を加
えて撹拌分散し、スラリーとした。
Example 4 [1] The catalyst was deposited in the same manner as in Example 1. [2] Nickel Plating The catalyst-adhered silicon oxide powder obtained as described above was added to 135 cm 3 of water and dispersed by stirring to obtain a slurry. Separately, 850 cm 3 of electroless nickel plating solution concentrate (trade name: Schumer S-680, manufactured by Nippon Kanigen) and 3.96 dm 3 of pure water are added to a 5 liter beaker and mixed, and the temperature is adjusted to 43 ° C. To make a plating bath. While the plating bath was being stirred, the slurry prepared above was added. The stirring was continued, and the reaction was performed for 40 minutes while maintaining the temperature. After the reaction, the nickel on a Buchner funnel - was filtered off powder phosphorous plating layer is formed, after washing sprinkled water about 1 dm 3, raking the powder, and stirred dispersion was added again water 105 cm 3, to form a slurry.

【0035】[3]銀メッキ硝酸銀4.59gを純水
1.33dm3に室温で溶解した溶液に、コハク酸イミ
ド6.69gを加えて溶解した。別に、ホスフィン酸ナ
トリウム2.86gを純水50cm3に溶解した液を用
意した。上記硝酸銀溶液を撹拌しながら加熱して46℃
に保った。ここへ、上記[2]で得られたスラリーを注
ぎ、均一化したところで、直ちにホスフィン酸ナトリウ
ム溶液を少しずつ加えた。さらに温度を保ちながら30
分間撹拌し続けた。その後、実施例1と同様に濾過、水
洗、真空乾燥し、銀被覆導電性粉末38.6gを得た。
[3] Silver plating To a solution of 4.59 g of silver nitrate in 1.33 dm 3 of pure water at room temperature, 6.69 g of succinimide was added and dissolved. Separately, a solution prepared by dissolving 2.86 g of sodium phosphinate in 50 cm 3 of pure water was prepared. The silver nitrate solution is heated with stirring to 46 ° C.
Kept. To this, the slurry obtained in the above [2] was poured, and when the mixture was homogenized, a sodium phosphinate solution was immediately added little by little. 30 while maintaining the temperature
Stirring continued for minutes. Thereafter, filtration, washing with water, and vacuum drying were performed in the same manner as in Example 1 to obtain 38.6 g of a silver-coated conductive powder.

【0036】[実施例5] [1]触媒付着を実施例1と同様に行い、[2]ニッケ
ルメッキを実施例4と同様に行った。 [3]銀メッキ 純水1.1dm3に、コハク酸イミド4.46g、イミ
ダゾール6.13gを加え、撹拌しながら温度を45℃
まで加温した(A液とする)。また、ホスフィン酸ナト
リウム2.86gを純水50cm3に溶解した液(B液
とする)、ならびに硝酸銀4.59gおよびコハク酸イ
ミド4.46gを純水200cm3に溶解した液(C液
とする)を用意した。上記A液を撹拌しながら、上記実
施例4[2]で得られたスラリーを注ぎ、3分間撹拌し
て均一な溶液とした。この溶液を撹拌した状態で、B液
を加えた後、C液を少しずつ連続的に1分間程度かけて
加えた。この時点における溶液の温度は40℃であっ
た。さらに加温しながら10分間撹拌し続けた。この時
点における溶液の温度は44℃であった。その後、実施
例1と同様に濾過、水洗、真空乾燥し、銀被覆導電性粉
末38.1gを得た。
Example 5 [1] Catalyst deposition was performed in the same manner as in Example 1, and [2] Nickel plating was performed in the same manner as in Example 4. [3] Silver plating To 1.1 dm 3 of pure water, 4.46 g of succinimide and 6.13 g of imidazole were added, and the temperature was raised to 45 ° C. while stirring.
The mixture was heated until the temperature reached A (liquid A). Further, a liquid (solution B) in which 2.86 g of sodium phosphinate was dissolved in 50 cm 3 of pure water, and a liquid (solution C in which 4.59 g of silver nitrate and 4.46 g of succinimide were dissolved in 200 cm 3 of pure water) ) Was prepared. While stirring the solution A, the slurry obtained in Example 4 [2] was poured and stirred for 3 minutes to obtain a uniform solution. After the solution B was added while the solution was stirred, the solution C was added little by little continuously over about 1 minute. The temperature of the solution at this point was 40 ° C. Stirring was continued for 10 minutes while further heating. The temperature of the solution at this point was 44 ° C. Thereafter, filtration, washing with water, and vacuum drying were performed in the same manner as in Example 1 to obtain 38.1 g of a silver-coated conductive powder.

【0037】[比較例1] [1]触媒付着、[2]ニッケルメッキを実施例1と同
様に行った。 [3]銀メッキ 硝酸銀4.73gを純水1.11dm3に室温で溶解し
た溶液に、28%アンモニア水18.7cm3を少しず
つ加えていき、当初生成した沈殿が完全に溶解したのを
確認した。その後、この溶液にロッシェル塩(酒石酸カ
リウムナトリウム4水和物)2.62gを加えて溶解し
た。上記溶液を引き続き撹拌しながら、実施例1[2]
で得られたスラリーを注ぎ、10分間撹拌し続けた。そ
の後、実施例1と同様に濾過、水洗、真空乾燥し、銀被
覆導電性粉末39.1gを得た。
COMPARATIVE EXAMPLE 1 [1] Catalyst deposition and [2] Nickel plating were performed in the same manner as in Example 1. [3] Silver plated silver nitrate 4.73g to a solution at room temperature in pure water 1.11Dm 3, we added 28% aqueous ammonia 18.7cm 3 little by little, that the precipitate produced initially completely dissolved confirmed. Thereafter, 2.62 g of Rochelle salt (potassium sodium tartrate tetrahydrate) was added to the solution and dissolved. Example 1 [2] while continuously stirring the above solution
The slurry obtained in was poured, and stirring was continued for 10 minutes. Thereafter, filtration, washing with water, and vacuum drying were performed in the same manner as in Example 1 to obtain 39.1 g of a silver-coated conductive powder.

【0038】[比較例2] [1]触媒付着、[2]ニッケルメッキを実施例1と同
様に行った。 [3]銀メッキ 硝酸銀4.73gを純水1.07dm3に室温で溶解し
た溶液に、28%アンモニア水18.7cm3を少しず
つ加えていき、当初生成した沈殿が完全に溶解したのを
確認した。その後、この溶液にチオ硫酸ナトリウム3
0.5gを純水1.10dm3に溶解しておいた溶液を
ゆっくり注ぎ込んだ。溶液中には沈殿が生じていないの
を確認した。この溶液を撹拌しながら加温して44℃に
保った。上記溶液を引き続き撹拌しながら、上記実施例
1[2]で得られたスラリーを注ぎ、20分間撹拌し続
けた。その後、実施例1と同様に濾過、水洗、真空乾燥
し、銀被覆導電性粉末37.7gを得た。
[Comparative Example 2] [1] Catalyst deposition and [2] nickel plating were performed in the same manner as in Example 1. [3] Silver plated silver nitrate 4.73g to a solution at room temperature in pure water 1.07Dm 3, we added 28% aqueous ammonia 18.7cm 3 little by little, that the precipitate produced initially completely dissolved confirmed. Then, the solution was added with sodium thiosulfate 3
A solution in which 0.5 g was dissolved in 1.10 dm 3 of pure water was slowly poured. It was confirmed that no precipitation occurred in the solution. The solution was warmed with stirring and kept at 44 ° C. While continuously stirring the solution, the slurry obtained in Example 1 [2] was poured, and stirring was continued for 20 minutes. Thereafter, filtration, washing with water, and vacuum drying were performed in the same manner as in Example 1 to obtain 37.7 g of a silver-coated conductive powder.

【0039】[比較例3] [1]触媒付着を実施例1と同様に行った。 [2]銅メッキ 上述のようにして得られた触媒付着粉末を、水135c
3に加えて撹拌分散し、スラリーとした。これとは別
に、5リットルビーカーに無電解銅メッキ液濃縮液(商
品名スルカップPSY−1A、上村工業製)400cm
3、水酸化ナトリウム33.6g、37%ホルムアルデ
ヒド水溶液40cm3、純水3.30dm3を加えて混合
し、温度を33℃に調整してメッキ浴とした。このメッ
キ浴を撹拌した状態で、上記で調製したスラリーを添加
した。撹拌を続け、温度を保ったまま30分間反応させ
た。反応後、ブフナー漏斗で銅メッキ層が形成された粉
末を濾別し、水約1dm3を振り掛け洗浄した後、当該
粉末をかき集め、再び水105cm3を加えて撹拌分散
し、スラリーとした。 [3]銀メッキ 上記[2]で得られた銅メッキ粉末含有スラリーを用い
た以外は、比較例2と同様の操作を行い、銀被覆導電性
粉末38.5gを得た
Comparative Example 3 [1] The catalyst was attached in the same manner as in Example 1. [2] Copper plating The catalyst-adhered powder obtained as described above was treated with water 135c.
m 3 , and dispersed by stirring. Separately, in a 5 liter beaker, 400 cm of electroless copper plating solution concentrate (trade name: Sulcup PSY-1A, manufactured by Uemura Kogyo)
3 , 33.6 g of sodium hydroxide, 40 cm 3 of a 37% aqueous formaldehyde solution and 3.30 dm 3 of pure water were added and mixed, and the temperature was adjusted to 33 ° C. to form a plating bath. While the plating bath was being stirred, the slurry prepared above was added. The stirring was continued, and the reaction was performed for 30 minutes while maintaining the temperature. After the reaction, the powder on which the copper plating layer was formed was filtered off with a Buchner funnel, sprinkled and washed with about 1 dm 3 of water, and then the powder was scraped, added again with 105 cm 3 of water, stirred and dispersed to form a slurry. [3] Silver plating Except for using the copper plating powder-containing slurry obtained in [2] above, the same operation as in Comparative Example 2 was performed to obtain 38.5 g of silver-coated conductive powder.

【0040】[組成分析]上記各実施例および比較例で
得られた銀被覆導電性粉末の一部を、フッ化水素酸と硝
酸とを用いて完全に分解し、化学分析を行い粉末の組成
を調べた。結果を表1に示す。
[Composition Analysis] A part of the silver-coated conductive powder obtained in each of the above Examples and Comparative Examples was completely decomposed using hydrofluoric acid and nitric acid, and subjected to chemical analysis to determine the composition of the powder. Was examined. Table 1 shows the results.

【0041】[0041]

【表1】 [Table 1]

【0042】[粉末の特性、性状]上記各実施例および
比較例で得られた銀被覆導電性粉末について、電子顕微
鏡で粒子形状、表面状態を観察した。その結果を表2に
示す。また、各粉末をセルに充填し、いわゆる4端子法
で定電流下の電位差を測定して抵抗率(導電率)を測定
した(電流源SMU−257およびナノボルトメータ2
000、ともにケースレ社製を使用)。この際、測定対
象となる抵抗は小さく、接触抵抗、接点間の熱電位差等
が無視できない誤差要因となるので、それらを防止・補
償するようにした。測定した値から計算した体積抵抗率
(mΩcm)を併せて表2に示す。
[Characteristics and Properties of Powder] With respect to the silver-coated conductive powder obtained in each of the above Examples and Comparative Examples, the particle shape and surface state were observed with an electron microscope. Table 2 shows the results. Also, each powder was filled in a cell, and the resistivity (conductivity) was measured by measuring the potential difference under a constant current by a so-called four-terminal method (current source SMU-257 and nanovoltmeter 2).
000, both manufactured by Keithle Co.). At this time, the resistance to be measured is small, and the contact resistance, the thermal potential difference between the contacts, and the like are non-negligible error factors. Therefore, they are prevented and compensated. Table 2 also shows the volume resistivity (mΩcm) calculated from the measured values.

【0043】[0043]

【表2】 [Table 2]

【0044】表1および表2に示されるように、実施例
1〜5および比較例1は、芯材が同じで、銀の量などの
組成もほぼ同じであるにも拘わらず、銀の析出状態には
大きな違いがあることがわかる。すなわち、実施例1〜
5では、粒子表面以外への銀の析出および粒子表面への
銀の不析出が生じていないのに対し、比較例1では微粉
として芯材粒子から離れて析出し、容器の内壁等に付着
するなど粒子表面以外への銀の析出が起こり、これらを
反映して体積抵抗率も各実施例の方が大幅に低くなって
いることがわかる。
As shown in Tables 1 and 2, Examples 1 to 5 and Comparative Example 1 had the same core material and substantially the same composition such as the amount of silver. It turns out that there is a big difference in the state. That is, Examples 1 to
In No. 5, silver was not deposited on the surface other than the particle surface and no silver was not precipitated on the particle surface, whereas in Comparative Example 1, the powder was separated away from the core material particles as fine powder and adhered to the inner wall of the container. For example, it can be seen that silver precipitation occurs on the surface other than the particle surface, and the volume resistivity is significantly lower in each of the examples, reflecting the above.

【0045】また、比較例2は、各実施例および比較例
1と同程度の銀を仕込んでいるにも拘わらず、銀の析出
量が少なく、しかも、表面以外への銀の析出が多いの
で、単に反応時間を長くしたところで、析出状態の改善
は期待できない。さらに、銅を下地金属とする比較例3
は、製造直後においては、各実施例と同等以上の導電性
を示していることがわかる。なお、比較例3の銀不析出
部分は、下地の銅層が不析出か、析出後に剥離して生じ
たものであると考えられる。
In Comparative Example 2, the amount of silver deposited was small and the amount of silver deposited on the surface other than the surface was large, although the same amount of silver was used as in each Example and Comparative Example 1. However, simply increasing the reaction time cannot be expected to improve the precipitation state. Comparative Example 3 using copper as a base metal
It can be seen that immediately after the production, it shows conductivity equal to or higher than that of each example. In addition, it is considered that the silver non-precipitated portion in Comparative Example 3 was generated by the non-precipitation of the underlying copper layer or the separation after the deposition.

【0046】[耐久試験]下地金属がニッケル合金であ
る場合と、銅である場合とによる銀メッキ層の耐久性の
違いを調べるために、以下に示す耐久性試験を行った。 (処理1) 製造、回収後の試料をシャーレにとり、加
熱炉中、アルゴン流通雰囲気下、内温150℃にて2時
間加熱後、アルゴン雰囲気下で室温まで冷却した。 (処理2) 処理1を施した後、10日間、室温、大気
中で放置した。 (処理3) 製造、回収後の試料をシャーレにとり、乾
燥機中、大気雰囲気下100℃にて5時間加熱した。上
記各処理を行った後の各試料について、上述と同様の方
法で体積抵抗率(mΩcm)を測定した。結果を表3に
示す。
[Durability Test] In order to examine the difference in durability of the silver plating layer between the case where the base metal is a nickel alloy and the case where the base metal is copper, the following durability test was performed. (Treatment 1) The sample after production and collection was placed in a petri dish, heated in an oven under an argon flowing atmosphere at an internal temperature of 150 ° C. for 2 hours, and then cooled to room temperature in an argon atmosphere. (Treatment 2) After the treatment 1, the mixture was allowed to stand in the air at room temperature for 10 days. (Treatment 3) The sample after production and collection was placed in a Petri dish and heated in a dryer at 100 ° C. for 5 hours under an air atmosphere. The volume resistivity (mΩcm) of each sample after performing each of the above processes was measured in the same manner as described above. Table 3 shows the results.

【0047】[0047]

【表3】 [Table 3]

【0048】表3に示されるように、比較例3の大気中
(処理2、3)での導電率の耐久性は、実施例1〜5と
比較して、かなり劣っていることがわかる。さらに詳し
く見ると、各実施例では、肉眼で見た外観の色にそれほ
ど変化がないのに対して、比較例3では、処理1で黄色
に変色し、処理2で茶色に変色し、処理3で黒褐色に変
色した。つまり、雰囲気中の酸素の有無に拘わらず、加
熱によって銅と銀との拡散が容易に進行し、その結果、
表面に拡散してきた銅が徐々に酸化されることにより、
導電性が低下していくものと考えられる。一方、各実施
例の試料は、下地がニッケル−リン合金であるため、拡
散が起こりにくく、その結果、表面がほぼ銀である状態
に保たれるので、導電性の耐久性が高くなるものと考え
られる。
As shown in Table 3, it can be seen that the durability of the conductivity in the atmosphere of Comparative Example 3 (Treatments 2 and 3) is considerably inferior to those of Examples 1 to 5. More specifically, in each of the examples, the color of the appearance as seen with the naked eye did not change much, whereas in Comparative Example 3, the color changed to yellow in the processing 1, the color changed to brown in the processing 2, and the processing 3 Discolored to black-brown. In other words, regardless of the presence or absence of oxygen in the atmosphere, the diffusion of copper and silver easily proceeds by heating, and as a result,
By gradually oxidizing copper that has diffused to the surface,
It is considered that the conductivity decreases. On the other hand, in the samples of the respective examples, since the base is made of a nickel-phosphorus alloy, diffusion hardly occurs, and as a result, the surface is kept almost in silver, so that the durability of the conductivity is increased. Conceivable.

【0049】[0049]

【発明の効果】以上に述べたように、本発明によれば、
水溶性銀塩と、亜硫酸もしくは亜硫酸塩、またはイミド
基もしくはアミド基を有する有機化合物からなる錯化剤
とを用いてニッケル合金上に無電解銀メッキを行ってい
る。したがって、シアン化合物を用いなくとも、ニッケ
ル合金上に均一で密着性のよい無電解銀メッキ層を形成
することができるとともに、耐久性に優れた銀被覆導電
性粉末を得ることができ、導電性を付与するためにゴ
ム、樹脂などに混練する等の目的に用いる導電性充填材
料の製造方法として有用である。
As described above, according to the present invention,
Electroless silver plating is performed on a nickel alloy using a water-soluble silver salt and a complexing agent comprising sulfurous acid, a sulfite, or an organic compound having an imide group or an amide group. Therefore, it is possible to form a uniform and highly adherent electroless silver plating layer on a nickel alloy without using a cyanide compound, and to obtain a silver-coated conductive powder having excellent durability. This is useful as a method for producing a conductive filler material used for the purpose of kneading rubber, resin, or the like in order to impart.

Claims (5)

【特許請求の範囲】[Claims] 【請求項1】 有機材料または無機材料からなる芯材表
面を無電解ニッケル−リンメッキ液で処理した後、水溶
性銀塩および錯化剤を含有する無電解銀メッキ液で処理
する銀被覆導電性粉末の製造方法であって、 前記無電解銀メッキ液の錯化剤は、亜硫酸もしくは亜硫
酸塩、またはイミド基もしくはアミド基を有する有機化
合物であることを特徴とする銀被覆導電性粉末の製造方
法。
1. A silver-coated conductive material in which a surface of a core material made of an organic material or an inorganic material is treated with an electroless nickel-phosphorous plating solution and then treated with an electroless silver plating solution containing a water-soluble silver salt and a complexing agent. A method for producing a powder, wherein the complexing agent of the electroless silver plating solution is sulfurous acid or a sulfite, or an organic compound having an imide group or an amide group. .
【請求項2】 前記無電解銀メッキ液中にホスフィン
酸、ホスフィン酸塩、またはヒドラジンを含むことを特
徴とする請求項1記載の銀被覆導電性粉末の製造方法。
2. The method for producing a silver-coated conductive powder according to claim 1, wherein the electroless silver plating solution contains phosphinic acid, a phosphinate, or hydrazine.
【請求項3】 有機材料または無機材料からなる芯材表
面に形成されたニッケル−リンメッキ層と、このニッケ
ル−リンメッキ層の上に形成された銀メッキ層とを有
し、請求項1または請求項2記載の方法によって得られ
る体積抵抗率が20mΩcm以下であることを特徴とす
る銀被覆導電性粉末。
3. A nickel-phosphorous plating layer formed on the surface of a core material made of an organic material or an inorganic material, and a silver plating layer formed on the nickel-phosphorous plating layer. 3. A silver-coated conductive powder having a volume resistivity of 20 mΩcm or less obtained by the method described in 2 above.
【請求項4】 前記銀メッキ層の厚みが100nm以下
であることを特徴とする請求項3記載の銀被覆導電性粉
末。
4. The silver-coated conductive powder according to claim 3, wherein the thickness of the silver plating layer is 100 nm or less.
【請求項5】 水溶性銀塩および錯化剤を含んでなる導
電性粉末被覆用無電解銀メッキ浴であって、 前記錯化剤が亜硫酸もしくは亜硫酸塩、またはイミド基
もしくはアミド基を有する有機化合物であることを特徴
とする導電性粉末被覆用無電解銀メッキ浴。
5. An electroless silver plating bath for coating a conductive powder, comprising a water-soluble silver salt and a complexing agent, wherein the complexing agent is a sulfurous acid or a sulfite, or an organic compound having an imide group or an amide group. An electroless silver plating bath for coating a conductive powder, which is a compound.
JP2001066073A 2001-03-09 2001-03-09 Method for manufacturing silver coated conductive powder, silver coated conductive powder and electroless plating bath for coating conductive powder Pending JP2002266079A (en)

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Application Number Priority Date Filing Date Title
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Publications (1)

Publication Number Publication Date
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Cited By (7)

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WO2006018995A1 (en) * 2004-08-05 2006-02-23 Sekisui Chemical Co., Ltd. Conductive fine particle, method for producing conductive fine particle and electroless silver plating liquid
KR100719802B1 (en) * 2005-12-28 2007-05-18 제일모직주식회사 Highly reliable conductive particles for anisotropic conductive interconnection
JP2013510953A (en) * 2009-11-16 2013-03-28 ビーエーエスエフ ソシエタス・ヨーロピア Island metal coating and synthesis method
WO2014140430A2 (en) 2013-03-15 2014-09-18 Inkron Ltd Multi shell metal particles and uses thereof
WO2020171030A1 (en) * 2019-02-19 2020-08-27 関東化学株式会社 Silver plating solution composition
WO2021182423A1 (en) * 2020-03-10 2021-09-16 大同メタル工業株式会社 Sliding member, method for manufacturing same, and method for manufacturing hard material
TWI741023B (en) * 2016-08-31 2021-10-01 日商同和電子科技股份有限公司 Silver coated alloy powder, conductive paste, electronic component and electrical device

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006018995A1 (en) * 2004-08-05 2006-02-23 Sekisui Chemical Co., Ltd. Conductive fine particle, method for producing conductive fine particle and electroless silver plating liquid
KR100719802B1 (en) * 2005-12-28 2007-05-18 제일모직주식회사 Highly reliable conductive particles for anisotropic conductive interconnection
WO2007074962A1 (en) * 2005-12-28 2007-07-05 Cheil Industries Inc. Conductive particles for anisotropic conductive interconnection
JP2013510953A (en) * 2009-11-16 2013-03-28 ビーエーエスエフ ソシエタス・ヨーロピア Island metal coating and synthesis method
WO2014140430A2 (en) 2013-03-15 2014-09-18 Inkron Ltd Multi shell metal particles and uses thereof
TWI741023B (en) * 2016-08-31 2021-10-01 日商同和電子科技股份有限公司 Silver coated alloy powder, conductive paste, electronic component and electrical device
JP7249804B2 (en) 2019-02-19 2023-03-31 関東化学株式会社 Silver plating solution composition
JP2020132940A (en) * 2019-02-19 2020-08-31 関東化学株式会社 Silver plating solution composition
WO2020171030A1 (en) * 2019-02-19 2020-08-27 関東化学株式会社 Silver plating solution composition
JP7249804B6 (en) 2019-02-19 2023-04-21 関東化学株式会社 Silver plating solution composition
WO2021182423A1 (en) * 2020-03-10 2021-09-16 大同メタル工業株式会社 Sliding member, method for manufacturing same, and method for manufacturing hard material
JP2021143355A (en) * 2020-03-10 2021-09-24 大同メタル工業株式会社 Sliding member and manufacturing method thereof and manufacturing method of hard material
JP7143356B2 (en) 2020-03-10 2022-09-28 大同メタル工業株式会社 Sliding member, its manufacturing method, and hard material manufacturing method
KR20220133931A (en) * 2020-03-10 2022-10-05 다이도 메탈 고교 가부시키가이샤 Sliding member, manufacturing method thereof, and manufacturing method of hard material
KR102634215B1 (en) * 2020-03-10 2024-02-07 다이도 메탈 고교 가부시키가이샤 Sliding member and its manufacturing method and hard material manufacturing method
US12000051B2 (en) 2020-03-10 2024-06-04 Daido Metal Company Ltd. Sliding member, method for manufacturing same, and method for manufacturing hard material

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