JP5394084B2 - Silver-plated copper fine powder, conductive paste produced using silver-plated copper fine powder, and method for producing silver-plated copper fine powder - Google Patents
Silver-plated copper fine powder, conductive paste produced using silver-plated copper fine powder, and method for producing silver-plated copper fine powder Download PDFInfo
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Description
本発明は銀メッキ銅微粉及び銀メッキ銅微粉を用いて製造した導電ペースト並びに銀メッキ銅微粉の製造方法に関するものであり、特に、導電性と銀メッキ反応時の再現性に優れ、かつ、銀メッキ銅微粉の表面に機械的な変形痕のない、フレーク状の銀メッキ銅微粉及びその製造方法に関する。 The present invention relates to a silver-plated copper fine powder, a conductive paste produced using silver-plated copper fine powder, and a method for producing a silver-plated copper fine powder. In particular, the present invention is excellent in conductivity and reproducibility during silver plating reaction, and silver The present invention relates to a flaky silver-plated copper fine powder having no mechanical deformation marks on the surface of the plated copper fine powder and a method for producing the same.
従来、銅微粉は導電ペーストの原料として広く用いられてきた。導電ペーストは、その取り扱いの容易さ故に、実験目的なものから電子産業用途に到るまで広範に使用されている。 Conventionally, copper fine powder has been widely used as a raw material for conductive paste. Conductive pastes are widely used because of their ease of handling, from experimental purposes to applications in the electronics industry.
なかでも、銀層を表面に被覆した銀メッキ銅微粉は、導電ペーストに加工され、スクリーン印刷法を用いたプリント配線板の回路形成、各種電気的接点部等に応用され、電気的導通確保の材料として用いられてきた。
これは、表面に銀層を被覆しない通常の銅微粉と比較したとき、銀メッキ銅微粉は銅微粉よりも電気的導電性に優れるからである。
また、銀粉のみでは高価になるが、銅に銀をめっきすれば、導電性粉末全体としては安価になり、製造コストを大幅に低減できるからである。したがって、導電特性により優れている銀をメッキした銅微粉からなる導電ペーストは、低抵抗の導体を低コストで製造できるという大きなメリットが得られる。
Among them, silver-plated copper fine powder with a silver layer coated on its surface is processed into a conductive paste and applied to the formation of printed wiring board circuits using screen printing, various electrical contact points, etc., to ensure electrical continuity. It has been used as a material.
This is because silver-plated copper fine powder is more excellent in electrical conductivity than copper fine powder when compared with normal copper fine powder that does not cover the surface with a silver layer.
Moreover, although it will become expensive only by silver powder, if silver is plated on copper, it will become cheap as the whole electroconductive powder, and manufacturing cost can be reduced significantly. Therefore, a conductive paste made of copper fine powder plated with silver, which is superior in conductive properties, has a great merit that a low-resistance conductor can be manufactured at low cost.
ところで、このような導電ペースト用の銀メッキ銅微粉は、一般的に銅と銀との置換反応を利用した無電解置換メッキ法により製造する技術が知られている。特許文献１には、硝酸銀、炭酸アンモニウム塩、エチレンジアミン四酢酸塩の銀錯塩溶液を用いて金属銅粉の表面に銀を置換析出させる方法についての記載がある。 By the way, the technique of manufacturing such a silver plating copper fine powder for electrically conductive paste by the electroless displacement plating method using the substitution reaction of copper and silver is generally known. Patent Document 1 describes a method of substituting and depositing silver on the surface of metallic copper powder using a silver complex solution of silver nitrate, ammonium carbonate, and ethylenediaminetetraacetate.
また、特許文献２には、キレート化剤溶液に銅粉を分散し、該銅粉分散液に硝酸銀溶液を加え、次いで還元剤を添加して銅粉表面へ銀被膜を析出させる方法が開示されている。 Patent Document 2 discloses a method of dispersing a copper powder in a chelating agent solution, adding a silver nitrate solution to the copper powder dispersion, and then adding a reducing agent to deposit a silver coating on the surface of the copper powder. ing.
さらに、特許文献３には、銅粉分散液にキレート化剤を加えて銅粉スラリーを作製し、これに緩衝剤を添加してｐＨ調整を行い、これに銀イオンを添加して置換反応により銀コート銅粉とする技術が開示されている。
そして、特許文献４には、銅粉の表面に銀を被覆した後、この銀メッキ銅粉をメカニカルアロイング装置に投入し、機械的なエネルギーを加えることにより、扁平状に変形した銀メッキ銅粉を製造する技術が開示されている。
Furthermore, in Patent Document 3, a chelating agent is added to a copper powder dispersion to prepare a copper powder slurry, a pH is adjusted by adding a buffer to the slurry, and silver ions are added thereto to perform substitution reaction. A technique for producing silver-coated copper powder is disclosed.
And in patent document 4, after covering the surface of copper powder with silver, this silver plating copper powder is thrown into a mechanical alloying apparatus, and mechanical energy is added, and silver plating copper deformed into a flat shape Techniques for producing flour are disclosed.
これらの製造方法で得られる銀メッキ銅微粉は、導電性や耐湿性の特性に優れ、導電ペースト材料としては好適な材料として利用されてきた。
しかし、これらの製造方法で得られた銀メッキ銅微粉は、銀メッキ前の銅微粉の酸化状態によって銀メッキ反応後の色調にバラツキが生じる等の問題点を抱えていた。
また、表面貴金属層（銀）と非貴金属層（銅）とを緻密化するために、銅粉の表面に銀を被覆した後、機械的なエネルギーを加えた場合は、銀メッキ銅粉の表面に機械的な変形痕が生じるといる問題点を抱えていた。
Silver-plated copper fine powder obtained by these production methods is excellent in conductivity and moisture resistance characteristics, and has been used as a suitable material as a conductive paste material.
However, the silver-plated copper fine powder obtained by these production methods has problems such as variations in the color tone after the silver plating reaction due to the oxidation state of the copper fine powder before silver plating.
In addition, in order to make the surface noble metal layer (silver) and non-noble metal layer (copper) dense, if the surface of the copper powder is coated with silver and then mechanical energy is applied, the surface of the silver-plated copper powder Had a problem that mechanical deformation marks were generated.
本発明は、上記の問題点を解決することを目的とし、導電性と銀メッキ反応時の再現性に優れ、かつ、銀メッキ銅微粉の表面に機械的な変形痕のない、フレーク状の銀メッキ銅微粉及びその製造方法を提供する。 The object of the present invention is to solve the above problems, and is excellent in conductivity and reproducibility at the time of silver plating reaction, and there is no mechanical deformation trace on the surface of the silver-plated copper fine powder. A plated copper fine powder and a method for producing the same are provided.
本発明者等は、上記課題を解決するために鋭意研究した結果、フレーク状の銀メッキ銅微粉において、フレーク状に加工した銅微粉を熱処理して銅微粉表面を酸化し、この銅微粉表面の酸化物を酸洗において十分に除去してから、銀メッキすることにより、導電性と銀メッキ反応時の再現性に優れ、かつ、銀メッキ銅微粉の表面に機械的な変形痕のない、フレーク状の銀メッキ銅微粉を得られることを見出した。 As a result of diligent research to solve the above problems, the inventors of the present invention, in the flaky silver-plated copper fine powder, heat-treat the copper fine powder processed into a flaky shape to oxidize the copper fine powder surface, Flakes that have excellent conductivity and reproducibility during silver plating reaction, and have no mechanical deformation marks on the surface of the silver-plated copper fine powder by sufficiently removing the oxide in pickling and then silver-plating It has been found that a silver-plated copper fine powder can be obtained.
これらの知見に基づき、本発明は
１）銅微粉の表面に銀層を形成する銀メッキ銅微粉の製造方法において、フレーク状に加工した銅微粉を熱処理して銅微粉表面を酸化し、次に、銅微粉をアルカリ性溶液中で銅微粉表面の有機物を除去・水洗した後、酸性溶液中で銅微粉表面の酸化物を酸洗・水洗し、その後、この銅微粉を分散させた酸性溶液中に還元剤を添加しｐＨを調整して銅微粉スラリーを作成し、この銅微粉スラリーに銀イオン溶液を連続的に添加することにより、無電解置換メッキと還元型無電解メッキにより銅微粉表面に銀層を形成することを特徴とする銀メッキ銅微粉の製造方法、を提供するものである。
Based on these findings, the present invention is 1) In the method for producing silver-plated copper fine powder in which a silver layer is formed on the surface of the copper fine powder, the copper fine powder processed into flakes is heat treated to oxidize the copper fine powder surface, After removing the organic matter on the surface of the copper fine powder in an alkaline solution and washing with water, the copper fine powder is pickled and washed with an oxide on the surface of the copper fine powder in an acidic solution, and then in an acidic solution in which the copper fine powder is dispersed. A copper fine powder slurry is prepared by adding a reducing agent and adjusting the pH, and a silver ion solution is continuously added to the copper fine powder slurry, so that the surface of the copper fine powder is electrolessly replaced by electroless displacement plating and reduced electroless plating. A method for producing a silver-plated copper fine powder characterized by forming a layer.
また、本発明は、
２）フレーク状銅微粉を大気中で１５０〜３５０℃、３〜７分間、熱処理を行うことを特徴とする上記１記載の銀メッキ銅微粉の製造方法
３）フレーク状銅微粉を大気中で２００〜３００℃、５〜７分間、熱処理を行うことを特徴とする上記１記載の銀メッキ銅微粉の製造方法
４）フレーク状銅微粉を酸化した後、さらに、この銅微粉を粗砕することを特徴とすることを特徴とする上記１〜３のいずれかに記載の銀メッキ銅微粉の製造方法
５）酸性溶液中で銅微粉表面の酸化物を２回以上酸洗し、銅微粉表面の酸化銅を除去することを特徴とする上記１〜４のいずれかに記載の銀メッキ銅微粉の製造方法、を提供するものである。
The present invention also provides:
2) The method for producing a silver-plated copper fine powder according to 1 above, wherein the flaky copper fine powder is heat-treated at 150 to 350 ° C. for 3 to 7 minutes in the air. 3) The flaky copper fine powder is 200 in the air. The method for producing silver-plated copper fine powder according to 1 above, wherein heat treatment is performed at ~ 300 ° C for 5 to 7 minutes. 4) After oxidizing the flaky copper fine powder, the copper fine powder is further crushed. The method for producing a silver-plated copper fine powder according to any one of the above 1 to 3 characterized in that it is characterized in that the oxide on the surface of the copper fine powder is pickled twice or more in an acidic solution to oxidize the surface of the copper fine powder. Copper is removed, The manufacturing method of the silver plating copper fine powder in any one of said 1-4 characterized by the above-mentioned is provided.
また、本発明は、
６）平均粒径が５〜１５μｍ、銀量が１０〜２５ｗｔ％、フレーク状であって、銅微粉表面に機械的な変形痕がないことを特徴とする銀メッキ銅微粉
７）平均粒径が７〜１３μｍ、銀量が１０〜２０ｗｔ％、フレーク状であって、銅微粉表面に機械的な変形痕がないことを特徴とする上記６記載の銀メッキ銅微粉
８）体積固有抵抗が７．０×１０−４〜１．３×１０−３Ω・ｃｍであり、８５℃８５％ＲＨ（相対湿度）の条件下で１２５時間後に測定した体積固有抵抗の抵抗変化率が１００％以下であることを特徴とする上記６〜７のいずれかに記載の銀メッキ銅微粉
９）体積固有抵抗が８．０×１０−４〜１．１×１０−３Ω・ｃｍであり、８５℃８５％ＲＨ（相対湿度）の条件下で１２５時間後に測定した体積固有抵抗の抵抗変化率が７０％以下であることを特徴とする上記６〜８のいずれかに記載の銀メッキ銅微粉
１０）上記６〜９のいずれかに記載の銀メッキ銅微粉を用いて製造した導電ペースト、を提供するものである。
The present invention also provides:
6) Silver-plated copper fine powder, characterized in that the average particle diameter is 5 to 15 μm, the silver amount is 10 to 25 wt%, and the surface of the copper fine powder has no mechanical deformation marks. The silver-plated copper fine powder according to 6 above, having a volume resistivity of 7 to 13 μm, a silver amount of 10 to 20 wt%, having a flaky shape and no mechanical deformation trace on the surface of the copper fine powder. 0 × 10 −4 to 1.3 × 10 −3 Ω · cm, and the resistance change rate of the volume resistivity measured after 125 hours under the condition of 85 ° C. and 85% RH (relative humidity) is 100% or less. The silver-plated copper fine powder according to any one of the above 6 to 7, characterized in that the volume specific resistance is 8.0 × 10 −4 to 1.1 × 10 −3 Ω · cm, and 85 ° C. and 85%. The resistance change rate of the volume resistivity measured after 125 hours under the condition of RH (relative humidity) is 7 The silver-plated copper fine powder according to any one of 6 to 8 above, wherein the conductive paste is produced using the silver-plated copper fine powder according to any one of 6 to 9 above. Is.
フレーク状に加工した銅微粉を熱処理して銅微粉表面を酸化し、この銅微粉表面の酸化物を酸洗において十分に除去してから、銀メッキすることにより、銀メッキ銅微粉の表面に機械的な変形痕のない、フレーク状の銀メッキ銅微粉を形成することが可能となり、その結果、酸化物や変形痕による導電性の低下がなく、優れた導電性を有する銀メッキ銅微粉となり、導電ペーストに使用した際に安定的な導電性を達成することができるという優れた効果を有する。 The copper fine powder processed into flakes is heat-treated to oxidize the copper fine powder surface, and the oxide on the copper fine powder surface is sufficiently removed by pickling, and then silver plating is performed on the surface of the silver-plated copper fine powder. It is possible to form flaky silver-plated copper fine powder without a typical deformation mark, and as a result, there is no decrease in conductivity due to oxides and deformation marks, resulting in silver-plated copper fine powder having excellent conductivity, When used in a conductive paste, it has an excellent effect that stable conductivity can be achieved.
従来は、銅粉の表面に銀を被覆した後に、この銀メッキ銅粉をメカニカルアロイング装置等に投入し、機械的なエネルギーを加えることにより、フレーク状に変形した銀メッキ銅粉を製造していたため、銀メッキ銅微粉の表面に機械的な変形痕が生じるといる問題点を抱えていた。 Conventionally, after coating the surface of the copper powder with silver, this silver-plated copper powder is put into a mechanical alloying device or the like, and mechanical energy is applied to produce a silver-plated copper powder deformed into flakes. For this reason, there was a problem that mechanical deformation marks were generated on the surface of the silver-plated copper fine powder.
また、銅粉の表面に銀を被覆した後に、メカニカルアロイング装置、乾式ボールミリング装置、ロール等による圧縮装置又は高速で固い物質に粉体を吹き付ける装置等を用いていたため、機械装置から銀メッキ銅微粉の表面にパーティクルが付着することも考えられた。 Also, after coating the surface of the copper powder with silver, a mechanical alloying device, a dry ball milling device, a compression device using a roll or the like, or a device that sprays powder onto a hard substance at high speed, etc. was used. It was also considered that particles adhered to the surface of the copper fine powder.
これに対し本発明は、フレーク状に加工した銅微粉を熱処理して銅微粉表面を酸化し、この銅微粉表面の酸化物を酸洗において十分に除去してから、銀メッキすることを特徴としているため、銀メッキ銅微粉の表面に機械的な変形痕のない、フレーク状の銀メッキ銅微粉を得ることができる。
銅微粉をフレーク状に加工する方法としては、一般に固体の粉砕による生成法が一般的な手法である。固体に圧縮、衝撃、摩擦等の力を加え、細分化することで粉体を生成する。具体的な手法としては、ボールミルやスタンプミル等を使用した機械加工によるフレーク化が挙げられるが、このフレーク状に加工する条件には特に制限はない。
On the other hand, the present invention is characterized in that the copper fine powder processed into flakes is heat-treated to oxidize the surface of the copper fine powder, the oxide on the surface of the copper fine powder is sufficiently removed by pickling, and then silver-plated. Therefore, flaky silver-plated copper fine powder having no mechanical deformation marks on the surface of the silver-plated copper fine powder can be obtained.
As a method for processing copper fine powder into flakes, a production method by pulverization of a solid is a general technique. Powders are generated by applying force such as compression, impact, friction, etc. to a solid and then subdividing it. As a specific method, flaking by machining using a ball mill, a stamp mill or the like can be mentioned, but there is no particular limitation on the conditions for processing into a flake shape.
本発明の製造方法に用いるフレーク状に加工した銅微粉は、酸素雰囲気中で１５０〜３５０℃、３〜７分間で熱処理を行う。好ましくは２００〜３００℃、５〜７分間で熱処理を行い、この熱処理によりフレーク状に加工した銅微粉の表面を酸化銅とする。 The copper fine powder processed into flakes used in the production method of the present invention is heat-treated in an oxygen atmosphere at 150 to 350 ° C. for 3 to 7 minutes. Preferably, heat treatment is performed at 200 to 300 ° C. for 5 to 7 minutes, and the surface of the copper fine powder processed into flakes by this heat treatment is made copper oxide.
この熱処理により、銅微粉の表面に付着したステアリン酸を除去することができる。また、この銅微粉表面の酸化膜を酸洗浄およびアルカリ洗浄することにより銅の地肌を出すことが可能であり、その後の銀メッキが良好に行うことが可能となる。このような酸化処理した銅微粉を、さらに粗砕することが好ましい。 By this heat treatment, stearic acid adhering to the surface of the copper fine powder can be removed. Further, the oxide film on the surface of the copper fine powder can be subjected to acid cleaning and alkali cleaning so that a copper background can be obtained, and subsequent silver plating can be performed satisfactorily. Such oxidized copper fine powder is preferably further crushed.
アルカリ性溶液として、水酸化ナトリウム、水酸化カリウム等を用いる。置換反応させる前に銅微粉表面の有機物を確実に除去できるアルカリ性溶液であればよい。 As the alkaline solution, sodium hydroxide, potassium hydroxide or the like is used. What is necessary is just an alkaline solution which can remove the organic substance on the surface of copper fine powder reliably before carrying out a substitution reaction.
酸性溶液にあっては、硫酸、塩酸、リン酸等を用いる。置換反応をさせる前に銅微粉表面の銅酸化物を確実に除去できる酸性溶液であればよいが、その選択する種類や濃度は過剰に銅微粉の銅自体を溶解しないようにする必要がある。
また、熱処理により銅微粉の表面は酸化銅となっているので、このような酸性溶液を用いた酸洗は、好ましくは２回以上行い、銅微粉の表面に形成した酸化銅を十分に除去する必要がある。これにより、銀めっき反応後の色調にバラツキを生じることはなく、導電性と銀メッキ反応時の再現性に優れた銀メッキ銅微粉を得ることができる。
In an acidic solution, sulfuric acid, hydrochloric acid, phosphoric acid or the like is used. Any acidic solution that can reliably remove the copper oxide on the surface of the copper fine powder before the substitution reaction may be used, but the type and concentration to be selected should not excessively dissolve the copper itself of the copper fine powder.
Moreover, since the surface of the copper fine powder is made of copper oxide by the heat treatment, pickling using such an acidic solution is preferably performed twice or more to sufficiently remove the copper oxide formed on the surface of the copper fine powder. There is a need. Thereby, there is no variation in the color tone after the silver plating reaction, and a silver-plated copper fine powder excellent in conductivity and reproducibility during the silver plating reaction can be obtained.
酸性溶液のｐＨは２．０〜５．０の酸性領域とする。ｐＨが５．０を越えると銅微粉の酸化物を十分に溶解除去できなくなり、ｐＨが２．０より小さくなると銅微粉の溶解が生じ、銅微粉自体の凝集も進行し易くなる。 The pH of the acidic solution is in the acidic range of 2.0 to 5.0. When the pH exceeds 5.0, it becomes impossible to sufficiently dissolve and remove the oxide of the copper fine powder. When the pH is lower than 2.0, the copper fine powder is dissolved, and the aggregation of the copper fine powder itself easily proceeds.
また、キレート化剤は、ＥＤＴＡやアンモニア等を用いることができる。硝酸銀溶液にアンモニア水を加えると、沈殿を生じるが、過剰のアンモニア水を加えると、透明なアンモニア性硝酸銀溶液（この中に［Ａｇ（ＮＨ３）２］＋を含む）が得られる。これに酒石酸ナトリウムカリウムなどの還元剤を加えると銅微粉の表面に銀が析出し、銀メッキ銅微粉が形成される。 Moreover, EDTA, ammonia, etc. can be used for a chelating agent. When ammonia water is added to the silver nitrate solution, precipitation occurs, but when excess ammonia water is added, a clear ammoniacal silver nitrate solution (containing [Ag (NH 3 ) 2 ] + therein) is obtained. When a reducing agent such as sodium potassium tartrate is added thereto, silver is deposited on the surface of the copper fine powder, and silver-plated copper fine powder is formed.
また、還元剤は、多価カルボン酸、多価カルボン酸塩類、ホルムアルデヒド等を用いることができる。例えば、酒石酸ナトリウムカリウム（ロッシェル塩）やブドウ糖（グルコース）などが挙げられる。還元剤は、弱い還元力を示し、置換反応の副生物として生成する酸化物（ＣｕＯ、Ｃｕ２Ｏ、ＡｇＯ、Ａｇ２Ｏ）のみを還元し、銅の錯イオンまでは還元させない。 Moreover, polyvalent carboxylic acid, polyvalent carboxylate, formaldehyde, etc. can be used for a reducing agent. Examples include sodium potassium tartrate (Rochelle salt) and glucose (glucose). The reducing agent exhibits a weak reducing power and reduces only oxides (CuO, Cu 2 O, AgO, Ag 2 O) produced as a by-product of the substitution reaction, and does not reduce copper complex ions.
そして、銀イオン溶液は、硝酸銀溶液を用いる。この硝酸銀溶液は硝酸銀濃度２０〜３００ｇ／Ｌとする。
また、銅微粉スラリーに添加する銀イオン溶液の速度は、２００ｍＬ／ｍｉｎ以下とする。上記濃度範囲の硝酸銀溶液を比較的ゆっくりとした添加速度、実用的には２０〜２００ｍＬ／ｍｉｎで添加することで、銅微粉表面に均一な銀層を被覆することが確実に行うことができる。
A silver nitrate solution is used as the silver ion solution. The silver nitrate solution has a silver nitrate concentration of 20 to 300 g / L.
Moreover, the speed | rate of the silver ion solution added to a copper fine powder slurry shall be 200 mL / min or less. By adding a silver nitrate solution in the above concentration range at a relatively slow addition rate, practically at 20 to 200 mL / min, it is possible to reliably coat a uniform silver layer on the copper fine powder surface.
さらに、酸性溶液中に銅微粉を分散した後、デカンテーション処理を行う。デカンテーション処理は、傾斜法とも呼ばれ、酸性溶液に銅微粉を分散させた後、溶液を静置することで銅微粉もしくは銀メッキ銅微粉を沈降させた後、上澄み液を静かに傾斜して分離採取する操作をいう。これによれば、銅微粉もしくは銀メッキ銅微粉が大気と接触することがないので、銅微粉もしくは銀メッキ銅微粉の再酸化を防止した状態で次工程に移行することが可能となる。 Further, after the copper fine powder is dispersed in the acidic solution, a decantation treatment is performed. The decantation process is also called a gradient method. After copper fine powder is dispersed in an acidic solution, the solution is allowed to stand to settle copper fine powder or silver-plated copper fine powder, and then the supernatant is gently inclined. An operation to separate and collect. According to this, since copper fine powder or silver plating copper fine powder does not contact air | atmosphere, it becomes possible to transfer to the following process in the state which prevented reoxidation of copper fine powder or silver plating copper fine powder.
本発明の製造方法に用いる後処理として、水素気流下の還元性雰囲気中で１５０〜２２０°Ｃ、３０〜９０分間で熱処理を行う。この熱処理により銅微粉と銀層の界面を一部合金化することで、界面の結合力を高めることができる。
銀メッキ銅微粉は導電性ペーストとする際に、樹脂や溶剤と混合して混練りするが、界面の結合力が弱いと、機械的摩擦を受けた時に銀層の剥離が生じてしまう。そこで、低温短時間での熱処理が有効となる。ただし、熱処理をあまり高温下や長時間行うと銀が銅に完全に拡散してしまう虞がある。
As a post-treatment used in the production method of the present invention, heat treatment is performed at 150 to 220 ° C. for 30 to 90 minutes in a reducing atmosphere under a hydrogen stream. By partially alloying the interface between the copper fine powder and the silver layer by this heat treatment, the bonding force at the interface can be increased.
Silver-plated copper fine powder is mixed with a resin or solvent and kneaded when making a conductive paste, but if the bonding force at the interface is weak, the silver layer will be peeled off when subjected to mechanical friction. Therefore, heat treatment at low temperature and short time is effective. However, if the heat treatment is performed at a very high temperature or for a long time, silver may be completely diffused into copper.
本発明の製造方法に用いる後処理として、０．０１〜５．０重量％の脂肪酸を含むアルコール溶液中に銀メッキ銅微粉を浸漬し、３０分間程度の攪拌後に濾過、乾燥する。脂肪酸はステアリン酸を用いる。脂肪酸被覆は、脂肪酸が銀メッキ銅微粉表面の凹凸に被覆されることにより表面が平滑化されることや脂肪酸自体が潤滑剤の役割を果たし銀メッキ銅微粉の充填性が高まることという優れた効果を有する。
これら後処理により銀メッキ反応により低下した銀メッキ銅微粉のタップ密度を原料銅微粉並みに高めることができ、高充填性を要求されるビアホール用途で有利となるのである。
As a post-treatment used in the production method of the present invention, silver-plated copper fine powder is immersed in an alcohol solution containing 0.01 to 5.0% by weight of a fatty acid, and is filtered and dried after stirring for about 30 minutes. As the fatty acid, stearic acid is used. Fatty acid coating is an excellent effect that the surface is smoothed by the fatty acid being coated on the irregularities of the silver-plated copper fine powder surface, and that the fatty acid itself acts as a lubricant and the filling property of the silver-plated copper fine powder is increased. Have
By these post-treatments, the tap density of the silver-plated copper fine powder lowered by the silver plating reaction can be increased to the same level as the raw material copper fine powder, which is advantageous for via hole applications that require high filling properties.
上記に示した銀メッキ銅微粉及びその製造方法に用いられる銅微粉は、その種類、製法等に特に制限がなく、通常の電解法、還元法、アトマイズ法、機械的粉砕等から得られる銅微粉が用いることができる。また、その銅粉形状は、フレーク状のものを用いる。
以上によって、平均粒径が５〜１５μｍ、銀量が１０〜２５ｗｔ％、フレーク状であって、銅微粉表面に機械的な変形痕がない銀メッキ銅微粉を得ることができる。
The copper fine powder used in the silver-plated copper fine powder and the production method thereof shown above is not particularly limited in the type, production method, etc., and is obtained from a normal electrolytic method, reduction method, atomizing method, mechanical grinding, etc. Can be used. The copper powder is flaky.
By the above, it is possible to obtain silver-plated copper fine powder having an average particle diameter of 5 to 15 μm, a silver amount of 10 to 25 wt%, and having a flake shape and no mechanical deformation trace on the surface of the copper fine powder.
この銀メッキ銅微粉は、さらに、平均粒径が７〜１３μｍ、銀量が１０〜２０ｗｔ％、フレーク状であって、銅微粉表面に機械的な変形痕がない銀メッキ銅微粉を達成することができる、これらの銀メッキ銅微粉は導電ペーストとして有用である。本願発明は、これらの銅粉を用いて製造した導電性ペーストを含むものである。 This silver-plated copper fine powder further achieves a silver-plated copper fine powder having an average particle diameter of 7 to 13 μm, a silver amount of 10 to 20 wt% and a flake shape, and having no mechanical deformation marks on the surface of the copper fine powder. These silver-plated copper fine powders are useful as a conductive paste. The present invention includes a conductive paste produced using these copper powders.
次に実施例に基づいて本発明を説明する。以下に示す実施例は、本発明の理解を容易にするためのものであり、これらの実施例によって本発明を制限するものではない。すなわち、本発明の技術思想に基づく変形及び他の実施例は、本発明に含まれるものである。 Next, this invention is demonstrated based on an Example. The following examples are for facilitating the understanding of the present invention, and the present invention is not limited by these examples. That is, modifications and other examples based on the technical idea of the present invention are included in the present invention.
（実施例１）
本実施例１においては、いわゆるアトマイズ法と呼ばれる製法により得られたアトマイズ銅粉を、さらに機械的粉砕を施して得られた銅微粉を使用した。なお、機械的粉砕時には、銅粉同士の凝集による粗大化を防止する目的で脂肪酸が添加されていると推察される。具体的には日本アトマイズ加工（株）製フレーク銅微粉（型番：ＡＦＳ−Ｃｕ ７μｍ）を使用した。この銅微粉はレーザー回折散乱式粒度分布測定法による重量累積粒径D５０は７．９μｍであった。
Example 1
In the present Example 1, the copper fine powder obtained by further performing mechanical grinding | pulverization was used for the atomized copper powder obtained by the manufacturing method called what is called the atomizing method. In addition, at the time of mechanical grinding | pulverization, it is guessed that the fatty acid is added in order to prevent the coarsening by aggregation of copper powder. Specifically, flake copper fine powder (model number: AFS-Cu 7 μm) manufactured by Nippon Atomizing Co., Ltd. was used. This copper fine powder had a weight cumulative particle size D 50 of 7.9 μm as measured by a laser diffraction / scattering particle size distribution measurement method.
このフレーク状の銅微粉５００ｇを大気中で２５０℃、５分間、熱処理した、その後、酸化処理した銅微粉を乳鉢にて粗砕した。
この銅微粉５００ｇを１％水酸化カリウム水溶液１０００ｍｌに加えて２０分間攪拌し、続いて一次デカンテーション処理を行い、さらに純水１０００ｍｌを加えて数分間攪拌した。
500 g of this flaky copper fine powder was heat treated in the atmosphere at 250 ° C. for 5 minutes, and then the oxidized copper fine powder was coarsely crushed in a mortar.
500 g of this copper fine powder was added to 1000 ml of 1% aqueous potassium hydroxide solution and stirred for 20 minutes, followed by primary decantation treatment, and further 1000 ml of pure water was added and stirred for several minutes.
その後、二次デカンテーション処理を行い、硫酸濃度１５ｇ／Ｌの硫酸水溶液２５００ｍｌを加えて３０分間攪拌した。さらに、硫酸水溶液による酸洗浄をもう１回繰り返した。
さらに、三次デカンテーション処理を行い、純水２５００ｍｌを加えて数分間攪拌した。そして、四次デカンテーション処理を行い、濾過洗浄、吸引脱水することでフレーク状の銅微粉と溶液とを濾別し、フレーク状の銅微粉を９０°Ｃの温度で２時間の乾燥を行った。
Then, the secondary decantation process was performed, 2500 ml of sulfuric acid aqueous solution with a sulfuric acid concentration of 15 g / L was added, and it stirred for 30 minutes. Further, the acid washing with the sulfuric acid aqueous solution was repeated once more.
Further, tertiary decantation treatment was performed, 2500 ml of pure water was added, and the mixture was stirred for several minutes. Then, quaternary decantation treatment was performed, filtration washing, suction dehydration was performed to separate the flaky copper fine powder and the solution, and the flaky copper fine powder was dried at a temperature of 90 ° C. for 2 hours. .
次いで、乾燥済みのフレーク状の銅微粉に硫酸濃度７．５ｇ／Ｌの硫酸水溶液２５００ｍｌを加えて３０分間攪拌した。
さらに、五次デカンテーション処理を行い、純水２５００ｍｌを加えて数分間攪拌した。
Next, 2500 ml of sulfuric acid aqueous solution having a sulfuric acid concentration of 7.5 g / L was added to the dried flaky copper fine powder and stirred for 30 minutes.
Further, a fifth decantation treatment was performed, 2500 ml of pure water was added, and the mixture was stirred for several minutes.
さらに、六次デカンテーション処理を行い、１％酒石酸ナトリウムカリウム溶液２５００ｍｌを加えて数分間攪拌し、銅スラリーを形成させた。
該銅スラリーに希硫酸又は水酸化カリウム溶液を加えて、銅スラリーのｐHを３．５〜４．５になるように調整した。
Further, a sixth decantation treatment was performed, and 2500 ml of 1% sodium potassium tartrate solution was added and stirred for several minutes to form a copper slurry.
A dilute sulfuric acid or potassium hydroxide solution was added to the copper slurry to adjust the pH of the copper slurry to 3.5 to 4.5.
ｐＨを調整した銅スラリーに硝酸銀アンモニア溶液１０００ｍｌ（硝酸銀８７．５ｇを水に添加してアンモニア水を加え、１０００ｍｌとして調整したもの）を、３０分間の時間をかけてゆっくりと添加しながら置換反応処理及び還元反応処理を行い、さらに３０分間の攪拌をして銀メッキ銅微粉を得た。 Substitution reaction treatment while adding 1000 ml of silver nitrate ammonia solution (adjusted to 1000 ml of silver nitrate by adding 87.5 g of silver nitrate to water and adjusting to 1000 ml) to copper slurry adjusted in pH over 30 minutes. Then, a reduction reaction treatment was performed, and the mixture was further stirred for 30 minutes to obtain silver-plated copper fine powder.
その後、七次デカンテーション処理を行い、純水３５００ｍｌを加えて数分間攪拌した。さらに八次デカンテーション処理を行い、純水３５００ｍｌを加えて数分間攪拌した。そして、濾過洗浄、吸引脱水することで銀メッキ銅微粉と溶液とを濾別し、銀メッキ銅微粉を９０°Ｃの温度で２時間の乾燥を行った。 Thereafter, a seventh decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Further, an eighth decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Then, the silver-plated copper fine powder and the solution were separated by filtration, washing and dehydrating, and the silver-plated copper fine powder was dried at a temperature of 90 ° C. for 2 hours.
上記の銀メッキ銅微粉５００ｇを管状炉に入れ、水素気流下（３．０〜３．５ｌ／ｍｉｎ）の還元性雰囲気中で２００°Ｃ、３０分間熱処理した。熱処理済みの銀メッキ銅微粉を乳鉢で粉砕した。 500 g of the above silver-plated copper fine powder was placed in a tubular furnace and heat-treated at 200 ° C. for 30 minutes in a reducing atmosphere under a hydrogen stream (3.0 to 3.5 l / min). The heat-treated silver-plated copper fine powder was pulverized in a mortar.
上記の熱処理済みの銀メッキ銅微粉５００ｇを０．５％ステアリン酸イソピルアルコール溶液１０００ｍｌに分散させ、３０分間攪拌した。
そして、濾過洗浄、吸引脱水することで熱処理済みのステアリン酸被覆銀メッキ銅微粉と溶液とを濾別し、熱処理済みのステアリン酸被覆銀メッキ銅微粉を９０°Ｃの温度で２時間の乾燥を行い、熱処理済みのステアリン酸被覆銀メッキ銅微粉を得た。
このようにして製造した実施例１の銀メッキ銅微粉の２０００倍のＳＥＭ画像、および１００００倍のＳＥＭ画像とＥＤＡＸ面分析により測定した銀と銅の濃度分布を図１に示す。ＥＤＡＸ面分析から微粉の全面が銀で均一に被覆されていることが確かめられた。
500 g of the above-mentioned heat-treated silver-plated copper fine powder was dispersed in 1000 ml of a 0.5% isopropyl alcohol stearate solution and stirred for 30 minutes.
Then, the heat-treated stearic acid-coated silver-plated copper fine powder and the solution are separated by filtration, washing and dehydrating, and the heat-treated stearic acid-coated silver-plated copper fine powder is dried at a temperature of 90 ° C. for 2 hours. A heat-treated stearic acid-coated silver-plated copper fine powder was obtained.
FIG. 1 shows the 2000-fold SEM image of the silver-plated copper fine powder of Example 1 produced in this way, and the 10,000-fold SEM image and silver and copper concentration distributions measured by EDAX surface analysis. From the EDAX surface analysis, it was confirmed that the entire surface of the fine powder was uniformly coated with silver.
（実施例２）
実施例１と同じフレーク状の銅微粉５００ｇを大気中で２５０℃、５分間、熱処理した、その後、酸化処理した銅微粉を乳鉢にて粗砕した。
この銅微粉５００ｇを１％水酸化カリウム水溶液１０００ｍｌに加えて２０分間攪拌し、続いて一次デカンテーション処理を行い、さらに純水１０００ｍｌを加えて数分間攪拌した。
(Example 2)
The same flaky copper fine powder 500 g as in Example 1 was heat-treated in the atmosphere at 250 ° C. for 5 minutes, and then the oxidized copper fine powder was coarsely crushed in a mortar.
500 g of this copper fine powder was added to 1000 ml of 1% aqueous potassium hydroxide solution and stirred for 20 minutes, followed by primary decantation treatment, and further 1000 ml of pure water was added and stirred for several minutes.
その後、二次デカンテーション処理を行い、硫酸濃度１５ｇ／Ｌの硫酸水溶液２５００ｍｌを加えて３０分間攪拌した。さらに、硫酸水溶液による酸洗浄をもう１回繰り返した。
さらに、三次デカンテーション処理を行い、純水２５００ｍｌを加えて数分間攪拌した。
Then, the secondary decantation process was performed, 2500 ml of sulfuric acid aqueous solution with a sulfuric acid concentration of 15 g / L was added, and it stirred for 30 minutes. Further, the acid washing with the sulfuric acid aqueous solution was repeated once more.
Further, tertiary decantation treatment was performed, 2500 ml of pure water was added, and the mixture was stirred for several minutes.
次いで、四次デカンテーション処理を行い、１％酒石酸ナトリウムカリウム溶液２５００ｍｌを加えて数分間攪拌し、銅スラリーを形成させた。
該銅スラリーに希硫酸又は水酸化カリウム溶液を加えて、銅スラリーのｐHを３．５〜４．５になるように調整した。
Next, quaternary decantation treatment was performed, and 2500 ml of 1% sodium potassium tartrate solution was added and stirred for several minutes to form a copper slurry.
A dilute sulfuric acid or potassium hydroxide solution was added to the copper slurry to adjust the pH of the copper slurry to 3.5 to 4.5.
ｐＨを調整した銅スラリーに硝酸銀アンモニア溶液１０００ｍｌ（硝酸銀８７．５ｇを水に添加してアンモニア水を加え、１０００ｍｌとして調整したもの）を、３０分間の時間をかけてゆっくりと添加しながら置換反応処理及び還元反応処理を行い、さらに３０分間の攪拌をして銀メッキ銅微粉を得た。 Replacement reaction treatment while adding silver nitrate ammonia solution 1000ml (added 87.5g of silver nitrate to water and adding ammonia water to 1000ml) to pH adjusted copper slurry slowly over 30 minutes Then, a reduction reaction treatment was performed, and the mixture was further stirred for 30 minutes to obtain silver-plated copper fine powder.
その後、五次デカンテーション処理を行い、純水３５００ｍｌを加えて数分間攪拌した。さらに六次デカンテーション処理を行い、純水３５００ｍｌを加えて数分間攪拌した。そして、濾過洗浄、吸引脱水することで銀メッキ銅微粉と溶液とを濾別し、銀メッキ銅微粉を９０°Ｃの温度で２時間の乾燥を行った。 Then, the fifth decantation process was performed, 3500 ml of pure water was added, and it stirred for several minutes. Further, a sixth decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Then, the silver-plated copper fine powder and the solution were separated by filtration, washing and dehydrating, and the silver-plated copper fine powder was dried at a temperature of 90 ° C. for 2 hours.
上記の銀メッキ銅微粉５００ｇを管状炉に入れ、水素気流下（３．０〜３．５ｌ／ｍｉｎ）の還元性雰囲気中で２００°Ｃ、３０分間熱処理した。熱処理済みの銀メッキ銅微粉を乳鉢で粉砕した。 500 g of the above silver-plated copper fine powder was placed in a tubular furnace and heat-treated at 200 ° C. for 30 minutes in a reducing atmosphere under a hydrogen stream (3.0 to 3.5 l / min). The heat-treated silver-plated copper fine powder was pulverized in a mortar.
上記の熱処理済みの銀メッキ銅微粉５００ｇを０．５％ステアリン酸イソピルアルコール溶液１０００ｍｌに分散させ、３０分間攪拌した。そして、濾過洗浄、吸引脱水することで熱処理済みのステアリン酸被覆銀メッキ銅微粉と溶液とを濾別し、熱処理済みのステアリン酸被覆銀メッキ銅微粉を９０°Ｃの温度で２時間の乾燥を行った。
このようにして製造した実施例２の銀メッキ銅微粉の２０００倍及び１００００倍のＳＥＭ画像を図２に示す。実施例１と同様に、ＥＤＡＸ面分析から微粉の全面が銀で均一に被覆されていることが確かめられた。
500 g of the above-mentioned heat-treated silver-plated copper fine powder was dispersed in 1000 ml of a 0.5% isopropyl alcohol stearate solution and stirred for 30 minutes. Then, the heat-treated stearic acid-coated silver-plated copper fine powder and the solution are separated by filtration, washing and dehydrating, and the heat-treated stearic acid-coated silver-plated copper fine powder is dried at a temperature of 90 ° C. for 2 hours. went.
FIG. 2 shows SEM images of 2000 times and 10,000 times the silver-plated copper fine powder of Example 2 produced in this way. As in Example 1, it was confirmed from the EDAX surface analysis that the entire surface of the fine powder was uniformly coated with silver.
（実施例３）
ｐＨを調整した銅スラリーに硝酸銀アンモニア溶液１５００ｍｌ（硝酸銀１３８．９５ｇを水に添加してアンモニア水を加え、１５００ｍｌとして調整したもの）を、３０分間の時間をかけてゆっくりと添加しながら置換反応処理及び還元反応処理を行い、さらに３０分間の攪拌をして銀メッキ銅微粉を得た点以外は実施例１と同様に処理を行い、熱処理済みのステアリン酸被覆銀メッキ銅微粉を得た。
このようにして製造した実施例３の銀メッキ銅微粉の２０００倍および１００００倍のＳＥＭ画像を図３に示す。実施例１と同様に、ＥＤＡＸ面分析から微粉の全面が銀で均一に被覆されていることが確かめられた。
(Example 3)
Replacement reaction treatment while adding 1500 ml of silver nitrate ammonia solution to the copper slurry adjusted in pH (added to the water by adding 138.95 g of silver nitrate to water and adjusting to 1500 ml) over 30 minutes. Then, a reduction reaction treatment was performed, and the mixture was further stirred for 30 minutes to obtain silver-plated copper fine powder. The same treatment as in Example 1 was performed to obtain a heat-treated stearic acid-coated silver-plated copper fine powder.
The SEM images of 2000 times and 10,000 times the silver-plated copper fine powder of Example 3 produced in this way are shown in FIG. As in Example 1, it was confirmed from the EDAX surface analysis that the entire surface of the fine powder was uniformly coated with silver.
（実施例４）
ｐＨを調整した銅スラリーに硝酸銀アンモニア溶液１５００ｍｌ（硝酸銀１３８．９５ｇを水に添加してアンモニア水を加え、１５００ｍｌとして調整したもの）を、３０分間の時間をかけてゆっくりと添加しながら置換反応処理及び還元反応処理を行い、さらに３０分間の攪拌をして銀メッキ銅微粉を得た点以外は実施例２と同様に処理を行い、熱処理済みのステアリン酸被覆銀メッキ銅微粉を得た。
このようにして製造した実施例４の銀メッキ銅微粉の２０００倍および１００００倍のＳＥＭ画像を図４に示す。実施例１と同様に、ＥＤＡＸ面分析から微粉の全面が銀で均一に被覆されていることが確かめられた。
Example 4
Replacement reaction treatment while adding 1500 ml of silver nitrate ammonia solution to the copper slurry adjusted in pH (added to the water by adding 138.95 g of silver nitrate to water and adjusting to 1500 ml) over 30 minutes. And the reduction reaction process was performed, and also the process was performed in the same manner as in Example 2 except that the silver-plated copper fine powder was obtained by stirring for 30 minutes to obtain a heat-treated stearic acid-coated silver-plated copper fine powder.
FIG. 4 shows SEM images of 2000 times and 10,000 times the silver-plated copper fine powder of Example 4 produced in this way. As in Example 1, it was confirmed from the EDAX surface analysis that the entire surface of the fine powder was uniformly coated with silver.
（比較例１）
銀メッキ前の酸化処理と銀メッキ後の熱処理を行わないこと以外は、実施例２と同様に処理し、ステアリン酸被覆銀メッキ銅微粉を得た。
このようにして製造した比較例１の銀メッキ銅微粉の２０００倍および１００００倍のＳＥＭ画像を図５に示す。ＳＥＭ画像およびＥＤＡＸ面分析から、銀めっきが一部に凝集し、均一にめっきできないことが確かめられた。
（比較例２）
銀メッキ前の酸化処理を行わないこと以外は、実施例２と同様に処理し、熱処理済みのステアリン酸被覆銀メッキ銅微粉を得た。
このようにして製造した比較例２の銀メッキ銅微粉の２０００倍および１００００倍のＳＥＭ画像を図６に示す。ＳＥＭ画像およびＥＤＡＸ面分析から、銀めっきが一部に凝集し、均一にめっきできないことが確かめられた。
(Comparative Example 1)
A stearic acid-coated silver-plated copper fine powder was obtained in the same manner as in Example 2 except that the oxidation treatment before silver plating and the heat treatment after silver plating were not performed.
FIG. 5 shows SEM images of 2000 times and 10,000 times the silver-plated copper fine powder of Comparative Example 1 produced as described above. From the SEM image and EDAX surface analysis, it was confirmed that the silver plating agglomerated in part and could not be uniformly plated.
(Comparative Example 2)
Except not performing the oxidation process before silver plating, it processed similarly to Example 2, and obtained the heat-treated stearic acid coating silver plating copper fine powder.
The SEM images of 2000 times and 10,000 times the silver-plated copper fine powder of Comparative Example 2 produced in this way are shown in FIG. From the SEM image and EDAX surface analysis, it was confirmed that the silver plating agglomerated in part and could not be uniformly plated.
上述の実施例に係る銀メッキ銅微粉に関し、その平均粒径、体積固有抵抗、銀量を測定した。平均粒径はレーザー回折散乱式粒度分布測定法によるもので、重量累積粒径D50の値を採用した。その結果を表１に示す。 Regarding the silver-plated copper fine powder according to the above-described Examples, the average particle diameter, volume resistivity, and silver amount were measured. The average particle diameter was determined by a laser diffraction / scattering particle size distribution measurement method, and the value of weight cumulative particle diameter D 50 was adopted. The results are shown in Table 1.
この表１に示すように、実施例１では、平均粒径は７．９μｍ、銀量は１０．５ｗｔ％、体積固有抵抗は８．３×１０−４Ω・cm、８５℃８５％ＲＨの条件下１２５時間後の抵抗変化率が３０％となった。 As shown in Table 1, in Example 1, the average particle size was 7.9 μm, the silver amount was 10.5 wt%, the volume resistivity was 8.3 × 10 −4 Ω · cm, and 85 ° C. and 85% RH. Under the conditions, the resistance change rate after 125 hours was 30%.
実施例２では、平均粒径は８．０μｍ、銀量は１３．０ｗｔ％、体積固有抵抗は１．３×１０−３Ω・cm、８５℃８５％ＲＨの条件下１２５時間後の抵抗変化率が６２％となった。 In Example 2, the average particle diameter is 8.0 μm, the silver amount is 13.0 wt%, the volume resistivity is 1.3 × 10 −3 Ω · cm, and the resistance change after 125 hours at 85 ° C. and 85% RH. The rate was 62%.
実施例３では、平均粒径は１０．１μｍ、銀量は１７．２ｗｔ％、体積固有抵抗は１．１×１０−３Ω・cm、８５℃８５％ＲＨの条件下１２５時間後の抵抗変化率が５８％となった。 In Example 3, the average particle diameter was 10.1 μm, the amount of silver was 17.2 wt%, the volume resistivity was 1.1 × 10 −3 Ω · cm, and the resistance change after 125 hours at 85 ° C. and 85% RH. The rate was 58%.
実施例４では、平均粒径は１０．４μｍ、銀量は１９．１ｗｔ％、体積固有抵抗は９．９×１０−４Ω・cm、８５℃８５％ＲＨの条件下１２５時間後の抵抗変化率が４７％となった。 In Example 4, the average particle size was 10.4 μm, the amount of silver was 19.1 wt%, the volume resistivity was 9.9 × 10 −4 Ω · cm, and the resistance change after 125 hours at 85 ° C. and 85% RH. The rate was 47%.
これらは、平均粒径が５〜１５μｍ、銀量が１０〜２５ｗｔ％、体積固有抵抗が７．０×１０−４〜１．３×１０−３Ω・ｃｍである本願発明の銀メッキ銅微粉の範囲に入るもので、好適な銀メッキ銅微粉であった。また、図１の実施例１、図２の実施例２、図３の実施例３、図４の実施例４に示す通り、いずれも表面に機械的な変形痕がない、滑らかなフレーク（扁平）状の粒子からなる銅微粉銀メッキ銅微粉であった。 These are silver-plated copper fine powders of the present invention having an average particle size of 5 to 15 μm, a silver amount of 10 to 25 wt%, and a volume resistivity of 7.0 × 10 −4 to 1.3 × 10 −3 Ω · cm. Thus, it was a suitable silver-plated copper fine powder. In addition, as shown in Example 1 in FIG. 1, Example 2 in FIG. 2, Example 3 in FIG. 3, and Example 4 in FIG. ) Copper fine powder consisting of silver-like particles.
これに対して、比較例１の平均粒径は７．３μｍ、銀量は１０．５ｗｔ％であるが、体積固有抵抗は、＞１０３と他の実施例と比較して導電性が低下した。 On the other hand, the average particle size of Comparative Example 1 is 7.3 μm and the silver amount is 10.5 wt%, but the volume resistivity is> 10 3, which is less conductive than the other examples. .
比較例２の平均粒径は８．１μｍ、銀量は１０．５ｗｔ％で、体積固有抵抗は、１．２×１０−３Ω・ｃｍであるが、８５℃８５％ＲＨの条件下１２５時間後の抵抗変化率が５６０％と大幅に悪化した。 The average particle diameter of Comparative Example 2 is 8.1 μm, the silver amount is 10.5 wt%, and the volume resistivity is 1.2 × 10 −3 Ω · cm, but the condition is 125 hours at 85 ° C. and 85% RH. Later, the rate of change in resistance greatly deteriorated to 560%.
また、図５の比較例１、図６の比較例２に示す通り、銀メッキ銅微粉の粒子表面に凹凸が多く、機械的な変形痕が見られ、銀メッキ表面の色調が悪く、本願発明の目的を達成することができず、好ましくない結果となった。 In addition, as shown in Comparative Example 1 in FIG. 5 and Comparative Example 2 in FIG. 6, the surface of the silver-plated copper fine particles has many irregularities, mechanical deformation marks are seen, and the color of the silver-plated surface is poor. The above-mentioned purpose could not be achieved, resulting in an unfavorable result.
本発明に係る銅微粉表面に銀層を均一に被覆した銀メッキ銅微粉は、優れた導電性を有するとともに銀メッキ反応時の再現性に優れ、フレーク状であって、銅微粉表面に機械的な変形痕がないため、導電ペーストなどの電気的導通確保の材料に最適である。 The silver-plated copper fine powder uniformly coated with a silver layer on the surface of the copper fine powder according to the present invention has excellent conductivity and excellent reproducibility at the time of silver plating reaction, is flaky, and mechanically applied to the surface of the copper fine powder. Therefore, it is most suitable as a material for ensuring electrical continuity such as a conductive paste.
Claims (9)
銅微粉表面に機械的な変形痕がないことを特徴とする請求項６記載の銀メッキ銅微粉。 The average particle size is 7 to 13 μm, the amount of silver is 10 to 20 wt%, flake shape,
The silver-plated copper fine powder according to claim 6, wherein there is no mechanical deformation mark on the surface of the copper fine powder.
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