JP5480576B2 - Conductive fine particles, anisotropic conductive material, and connection structure - Google Patents

Conductive fine particles, anisotropic conductive material, and connection structure Download PDF

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JP5480576B2
JP5480576B2 JP2009221275A JP2009221275A JP5480576B2 JP 5480576 B2 JP5480576 B2 JP 5480576B2 JP 2009221275 A JP2009221275 A JP 2009221275A JP 2009221275 A JP2009221275 A JP 2009221275A JP 5480576 B2 JP5480576 B2 JP 5480576B2
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fine particles
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layer
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JP2011070943A (en
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拓 佐々木
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Sekisui Chemical Co Ltd
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Description

本発明は、保管時における黒化現象の発生を抑制して、高い接続信頼性を実現することが可能な導電性微粒子、該導電性微粒子を用いてなる異方性導電材料、及び、接続構造体に関する。 The present invention relates to conductive fine particles capable of suppressing the occurrence of a blackening phenomenon during storage and realizing high connection reliability, an anisotropic conductive material using the conductive fine particles, and a connection structure About the body.

従来、電子回路基板において、ICやLSIは、電極をプリント基板にハンダ付けすることによって接続されていた。しかし、ハンダ付けでは、プリント基板と、ICやLSIとを効率的に接続することはできなかった。また、ハンダ付けでは、ICやLSIの実装密度を向上させることが困難であった。
これを解決するためにハンダを球状にした、いわゆる「ハンダボール」でICやLSIを基板に接続するBGA(ボールグリッドアレイ)が開発された。この技術によれば、チップ又は基板上に実装されたハンダボールを高温で溶融し基板とチップとを接続することで高生産性、高接続信頼性を両立した電子回路を構成することができる。
Conventionally, in an electronic circuit board, ICs and LSIs are connected by soldering electrodes to a printed circuit board. However, soldering cannot efficiently connect the printed circuit board to the IC or LSI. In addition, it is difficult to improve the mounting density of ICs and LSIs by soldering.
In order to solve this problem, a BGA (ball grid array) has been developed in which the solder is made into a spherical shape, so-called “solder balls” that connect the IC or LSI to the substrate. According to this technique, an electronic circuit that achieves both high productivity and high connection reliability can be configured by melting a solder ball mounted on a chip or a substrate at a high temperature and connecting the substrate and the chip.

しかし、近年、基板の多層化が進み、多層基板は使用環境の影響を受けやすいことから、基板に歪みや伸縮が発生し、基板間の接続部に断線が発生するという問題があった。 However, in recent years, since the number of substrates has been increased and multilayer substrates are easily affected by the use environment, there has been a problem that distortion and expansion / contraction occur in the substrates and disconnection occurs in the connection portion between the substrates.

このような問題に対し、特許文献1には、樹脂微粒子の表面に、導電性の高い金属が含まれる金属層(導電層)が形成され、さらに、金属層の表面に、錫等の金属からなる低融点金属層(ハンダ層)が形成された導電性微粒子が開示されている。このような導電性微粒子を用いれば、柔軟な樹脂微粒子が導電性微粒子に加わる応力を緩和でき、かつ、最表面に低融点金属層を形成することにより、電極間を容易に導電接続することができる。 For such a problem, Patent Document 1 discloses that a metal layer (conductive layer) containing a highly conductive metal is formed on the surface of resin fine particles, and further, a metal such as tin is formed on the surface of the metal layer. A conductive fine particle having a low melting point metal layer (solder layer) formed thereon is disclosed. If such conductive fine particles are used, the stress applied to the conductive fine particles by the flexible resin fine particles can be relaxed, and the low melting point metal layer can be formed on the outermost surface to easily conduct conductive connection between the electrodes. it can.

しかしながら、電解めっき等の方法によって金属層の表面に低融点金属層を形成した場合は、得られる低融点金属層は、結晶状に低融点金属が析出し、表面に微小な凹凸が存在する構造となる。低融点金属層がこのような形状である場合、保管時に導電性微粒子同士が擦れ合うことによって、低融点金属の一部が削り取られ、削り取られた金属片が酸化することで黒色の微粉末に変化した後、再度へテロ凝集により導電性微粒子表面に付着するという、いわゆる黒化現象が発生していた。黒化現象が生じると、導電性微粒子を溶融させて、実装を行う場合に低融点金属の溶融性が阻害され、実装不良が生じていた。 However, when a low melting point metal layer is formed on the surface of the metal layer by a method such as electrolytic plating, the resulting low melting point metal layer has a structure in which the low melting point metal is precipitated in a crystalline form and minute irregularities exist on the surface. It becomes. When the low melting point metal layer has such a shape, the conductive fine particles rub against each other during storage, so that a part of the low melting point metal is scraped off, and the scraped metal piece is oxidized to change into a black fine powder. After that, a so-called blackening phenomenon occurred, in which the particles again adhere to the surface of the conductive fine particles due to heteroaggregation. When the blackening phenomenon occurs, when the conductive fine particles are melted and mounted, the meltability of the low melting point metal is hindered, resulting in a mounting failure.

このような黒化現象による問題を解決するため、特許文献1には、表面に滑剤が均一に被覆された導電性微粒子が記載されているが、このような導電性微粒子を用いた場合は、導電性微粒子同士が表面の滑剤により微接着して、凝集しやすくなるという問題があった。
これに対して、特許文献2及び特許文献3には、表面に金属石鹸分子膜や有機皮膜を形成した導電性微粒子を用いる方法が記載されているが、これらの方法では、金属石鹸分子膜や有機皮膜に起因する不純物が発生することで、低融点金属の溶融性が阻害されるという新たな問題が生じていた。
In order to solve the problem caused by such a blackening phenomenon, Patent Document 1 describes conductive fine particles whose surface is uniformly coated with a lubricant, but when such conductive fine particles are used, There is a problem that the conductive fine particles are slightly adhered to each other by the lubricant on the surface and are easily aggregated.
On the other hand, Patent Document 2 and Patent Document 3 describe a method using conductive fine particles having a metal soap molecular film or an organic film formed on the surface. In these methods, the metal soap molecular film or The generation of impurities due to the organic film has caused a new problem that the melting property of the low melting point metal is inhibited.

特開2000−288771号公報Japanese Patent Laid-Open No. 2000-287771 特開2006−9112号公報JP 2006-9112 A 特開2005−254246号公報JP 2005-254246 A

本発明は、保管時における黒化現象の発生を抑制して、高い接続信頼性を実現することが可能な導電性微粒子、該導電性微粒子を用いてなる異方性導電材料、及び、接続構造体を提供することを目的とする。 The present invention relates to conductive fine particles capable of suppressing the occurrence of a blackening phenomenon during storage and realizing high connection reliability, an anisotropic conductive material using the conductive fine particles, and a connection structure The purpose is to provide a body.

本発明は、基材微粒子の表面に、導電層及び低融点金属層が順次形成されている導電性微粒子であって、前記低融点金属層表面の算術平均粗さが50nm以下である導電性微粒子である。
以下に本発明を詳述する。
The present invention relates to a conductive fine particle in which a conductive layer and a low-melting point metal layer are sequentially formed on the surface of a base particle, wherein the low-melting point metal layer has an arithmetic average roughness of 50 nm or less. It is.
The present invention is described in detail below.

本発明者らは、鋭意検討した結果、低融点金属層表面の算術平均粗さが50nm以下とすることで、保管時において、低融点金属が削り取られることによって発生する黒化現象を抑制し、導電性微粒子の接続信頼性を大幅に改善できることを見出し、本発明を完成させるに至った。 As a result of intensive studies, the inventors have suppressed the blackening phenomenon that occurs when the low melting point metal is scraped off during storage by setting the arithmetic average roughness of the surface of the low melting point metal layer to 50 nm or less. The inventors have found that the connection reliability of the conductive fine particles can be greatly improved, and have completed the present invention.

本発明の導電性微粒子は、基材微粒子の表面に、導電層及び低融点金属層が順次形成されている導電性微粒子であって、前記低融点金属層表面の算術平均粗さが50nm以下である。 The conductive fine particles of the present invention are conductive fine particles in which a conductive layer and a low melting point metal layer are sequentially formed on the surface of the substrate fine particles, and the arithmetic average roughness of the surface of the low melting point metal layer is 50 nm or less. is there.

上記基材微粒子は特に限定されず、例えば、樹脂微粒子、無機微粒子、有機無機ハイブリッド微粒子、金属微粒子等が挙げられる。上記基材微粒子としては、特に樹脂微粒子が好ましい。 The substrate fine particles are not particularly limited, and examples thereof include resin fine particles, inorganic fine particles, organic-inorganic hybrid fine particles, and metal fine particles. As the substrate fine particles, resin fine particles are particularly preferable.

上記樹脂微粒子は特に限定されず、例えば、ポリオレフィン樹脂、アクリル樹脂、ポリアルキレンテレフタレート樹脂、ポリスルホン樹脂、ポリカーボネート樹脂、ポリアミド樹脂、フェノールホルムアルデヒド樹脂、メラミンホルムアルデヒド樹脂、ベンゾグアナミンホルムアルデヒド樹脂、尿素ホルムアルデヒド樹脂等で構成される樹脂微粒子が挙げられる。
上記ポリオレフィン樹脂は特に限定されず、例えば、ポリエチレン樹脂、ポリプロピレン樹脂、ポリスチレン樹脂、ポリイソブチレン樹脂、ポリブタジエン樹脂等が挙げられる。上記アクリル樹脂は特に限定されず、例えば、ポリメチルメタクリレート樹脂、ポリメチルアクリレート樹脂等が挙げられる。これらの樹脂は、単独で用いられてもよいし、2種以上が併用されてもよい。
The resin fine particles are not particularly limited, and include, for example, polyolefin resin, acrylic resin, polyalkylene terephthalate resin, polysulfone resin, polycarbonate resin, polyamide resin, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, and the like. Resin fine particles.
The polyolefin resin is not particularly limited, and examples thereof include polyethylene resin, polypropylene resin, polystyrene resin, polyisobutylene resin, and polybutadiene resin. The acrylic resin is not particularly limited, and examples thereof include polymethyl methacrylate resin and polymethyl acrylate resin. These resins may be used alone or in combination of two or more.

上記樹脂微粒子を作製する方法は特に限定されず、例えば、重合法による方法、高分子保護剤を用いる方法、界面活性剤を用いる方法等が挙げられる。
上記重合法は特に限定されず、乳化重合、懸濁重合、シード重合、分散重合、分散シード重合等の重合法が挙げられる。
The method for producing the resin fine particles is not particularly limited, and examples thereof include a polymerization method, a method using a polymer protective agent, and a method using a surfactant.
The polymerization method is not particularly limited, and examples thereof include emulsion polymerization, suspension polymerization, seed polymerization, dispersion polymerization, and dispersion seed polymerization.

上記無機微粒子は特に限定されず、例えば、シリカ、アルミナ等の金属酸化物で構成される微粒子が挙げられる。上記有機無機ハイブリッド微粒子は特に限定されず、例えば、オルガノシロキサン骨格の中にアクリルポリマーを含有するハイブリッド微粒子が挙げられる。
上記金属微粒子は特に限定されず、例えば、アルミニウム、銅、ニッケル、鉄、金、銀等の金属からなる微粒子が挙げられる。なかでも、銅微粒子が好ましい。上記銅微粒子は、実質的に銅金属のみで形成された銅微粒子であってもよく、銅金属を含有する銅微粒子であってもよい。なお、上記基材微粒子が銅微粒子である場合は、後述する導電層を形成しなくてもよい。
The inorganic fine particles are not particularly limited, and examples thereof include fine particles composed of metal oxides such as silica and alumina. The organic-inorganic hybrid fine particles are not particularly limited, and examples thereof include hybrid fine particles containing an acrylic polymer in an organosiloxane skeleton.
The metal fine particles are not particularly limited, and examples thereof include fine particles made of metals such as aluminum, copper, nickel, iron, gold, and silver. Of these, copper fine particles are preferred. The copper fine particles may be copper fine particles formed substantially only of copper metal, or may be copper fine particles containing copper metal. In addition, when the said base material microparticles | fine-particles are copper microparticles | fine-particles, it is not necessary to form the conductive layer mentioned later.

上記基材微粒子が樹脂微粒子である場合、上記樹脂微粒子の10%K値の好ましい下限は1000MPa、好ましい上限は15000MPaである。上記10%K値が1000MPa未満であると、樹脂微粒子を圧縮変形させると、樹脂微粒子が破壊されることがある。上記10%K値が15000MPaを超えると、導電性微粒子が電極を傷つけることがある。上記10%K値のより好ましい下限は2000MPa、より好ましい上限は10000MPaである。 When the substrate fine particles are resin fine particles, the preferred lower limit of the 10% K value of the fine resin particles is 1000 MPa, and the preferred upper limit is 15000 MPa. If the 10% K value is less than 1000 MPa, the resin fine particles may be destroyed when the resin fine particles are compressed and deformed. When the 10% K value exceeds 15000 MPa, the conductive fine particles may damage the electrode. The more preferable lower limit of the 10% K value is 2000 MPa, and the more preferable upper limit is 10,000 MPa.

なお、上記10%K値は、微小圧縮試験器(例えば、島津製作所社製「PCT−200」)を用い、樹脂微粒子を直径50μmのダイアモンド製円柱の平滑圧子端面で、圧縮速度2.6mN/秒、最大試験荷重10gの条件下で圧縮した場合の圧縮変位(mm)を測定し、下記式により求めることができる。
K値(N/mm)=(3/√2)・F・S−3/2・R−1/2
F:樹脂微粒子の10%圧縮変形における荷重値(N)
S:樹脂微粒子の10%圧縮変形における圧縮変位(mm)
R:樹脂微粒子の半径(mm)
The 10% K value is obtained by using a micro compression tester (for example, “PCT-200” manufactured by Shimadzu Corporation), and using a smooth indenter end face of a diamond cylinder having a diameter of 50 μm and a compression speed of 2.6 mN / The compression displacement (mm) when compressed under conditions of seconds and a maximum test load of 10 g can be measured and determined by the following equation.
K value (N / mm 2) = ( 3 / √2) · F · S -3/2 · R -1/2
F: Load value at 10% compression deformation of resin fine particles (N)
S: Compression displacement (mm) in 10% compression deformation of resin fine particles
R: radius of resin fine particles (mm)

上記基材微粒子の平均粒子径は特に限定されないが、好ましい下限は1μm、好ましい上限は2000μmである。上記基材微粒子の平均粒子径が1μm未満であると、基材微粒子が凝集しやすく、凝集した基材微粒子の表面に低融点金属層を形成した導電性微粒子を用いると、隣接する電極間を短絡させることがある。上記基材微粒子の平均粒子径が2000μmを超えると、回路基板等の電極間の接続に適した範囲を超えることがある。上記基材微粒子の平均粒子径のより好ましい下限は3μm、より好ましい上限は1000μmである。
なお、上記基材微粒子の平均粒子径は、光学顕微鏡又は電子顕微鏡を用いて無作為に選んだ50個の基材微粒子の粒子径を測定し、測定した粒子径を算術平均することにより求めることができる。
The average particle diameter of the substrate fine particles is not particularly limited, but a preferable lower limit is 1 μm and a preferable upper limit is 2000 μm. When the average particle diameter of the above-mentioned substrate fine particles is less than 1 μm, the substrate fine particles are likely to aggregate. When conductive fine particles in which a low melting point metal layer is formed on the surface of the aggregated substrate fine particles are used, a gap between adjacent electrodes can be obtained. May cause a short circuit. When the average particle diameter of the base material fine particles exceeds 2000 μm, the range suitable for connection between electrodes such as a circuit board may be exceeded. The more preferable lower limit of the average particle diameter of the substrate fine particles is 3 μm, and the more preferable upper limit is 1000 μm.
The average particle size of the above-mentioned substrate fine particles is obtained by measuring the particle size of 50 randomly selected substrate fine particles using an optical microscope or an electron microscope and arithmetically averaging the measured particle sizes. Can do.

上記基材微粒子の平均粒子径の変動係数は特に限定されないが、10%以下であることが好ましい。上記変動係数が10%を超えると、導電性微粒子の接続信頼性が低下することがある。なお、上記変動係数とは、粒子径分布から得られる標準偏差を平均粒子径で除して得られる値を百分率(%)で示した数値である。 The coefficient of variation of the average particle diameter of the substrate fine particles is not particularly limited, but is preferably 10% or less. If the coefficient of variation exceeds 10%, the connection reliability of the conductive fine particles may be lowered. The coefficient of variation is a numerical value obtained by dividing the standard deviation obtained from the particle size distribution by the average particle size and expressed as a percentage (%).

上記基材微粒子の形状は、対向する電極の間隔を維持できる形状であれば特に限定されないが、真球形状であることが好ましい。また、上記基材微粒子の表面は平滑であってもよいし、突起を有していてもよい。 The shape of the substrate fine particles is not particularly limited as long as the distance between the opposing electrodes can be maintained, but a true spherical shape is preferable. Further, the surface of the substrate fine particles may be smooth or may have a protrusion.

本発明の導電性微粒子は、上記基材微粒子の表面に、導電層が形成されている。上記導電層は、下地金属層としての役割を有する。
上記導電層を形成する金属は特に限定されず、例えば、金、銀、銅、亜鉛、鉄、鉛、錫、アルミニウム、コバルト、インジウム、ニッケル、クロム、アンチモン、ビスマス、ゲルマニウム、カドミウム等が挙げられる。なかでも、導電性に優れることから、上記導電層を形成する金属は、金、銅又はニッケルであることが好ましい。
In the conductive fine particles of the present invention, a conductive layer is formed on the surface of the substrate fine particles. The conductive layer serves as a base metal layer.
The metal forming the conductive layer is not particularly limited, and examples thereof include gold, silver, copper, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, antimony, bismuth, germanium, and cadmium. . Especially, since it is excellent in electroconductivity, it is preferable that the metal which forms the said conductive layer is gold, copper, or nickel.

上記基材微粒子の表面に、上記導電層を形成させる方法は特に限定されず、例えば、無電解メッキ法、電解メッキ法、真空蒸着法、イオンプレーティング法、イオンスパッタリング法等が挙げられる。 The method for forming the conductive layer on the surface of the substrate fine particles is not particularly limited, and examples thereof include an electroless plating method, an electrolytic plating method, a vacuum deposition method, an ion plating method, and an ion sputtering method.

上記導電層の厚さは特に限定されないが、好ましい下限は0.1μm、好ましい上限は100μmである。上記導電層の厚さが0.1μm未満であると、導電性が充分に得られないことがある。上記導電層の厚さが100μmを超えると、導電性微粒子の柔軟性が低下することがある。上記導電層の厚さのより好ましい下限は0.2μm、より好ましい上限は50μmである。
なお、上記導電層の厚さは、無作為に選んだ10個の導電性微粒子の断面を走査型電子顕微鏡(SEM)により観察して測定し、これらを算術平均した厚さである。
Although the thickness of the said conductive layer is not specifically limited, A preferable minimum is 0.1 micrometer and a preferable upper limit is 100 micrometers. If the thickness of the conductive layer is less than 0.1 μm, sufficient conductivity may not be obtained. When the thickness of the conductive layer exceeds 100 μm, the flexibility of the conductive fine particles may be lowered. A more preferable lower limit of the thickness of the conductive layer is 0.2 μm, and a more preferable upper limit is 50 μm.
The thickness of the conductive layer is a thickness obtained by observing and measuring a section of 10 randomly selected conductive fine particles with a scanning electron microscope (SEM) and arithmetically averaging them.

本発明の導電性微粒子は、低融点金属を有する。上記低融点金属層は、リフロー工程により溶融して電極に接合し、電極間を導通させる役割を有する。 The conductive fine particles of the present invention have a low melting point metal. The low-melting-point metal layer has a role of melting and joining the electrodes by a reflow process and conducting between the electrodes.

本発明において、上記低融点金属層表面の算術平均粗さは50nm以下である。上記算術平均粗さが50nmを超えると、保管時において低融点金属の一部が削り取られることで、黒化現象が発生する。上記算術平均粗さは、45nm以下であることが好ましく、25nm以下であることがより好ましい。
なお、本明細書において、算術平均粗さ(Ra)は、JIS B0601に準拠した方法で測定されたものである。
In the present invention, the arithmetic average roughness of the surface of the low melting point metal layer is 50 nm or less. When the arithmetic average roughness exceeds 50 nm, a part of the low melting point metal is scraped off during storage, and a blackening phenomenon occurs. The arithmetic average roughness is preferably 45 nm or less, and more preferably 25 nm or less.
In addition, in this specification, arithmetic mean roughness (Ra) is measured by the method based on JIS B0601.

上記低融点金属層を構成する低融点金属は特に限定されないが、錫、又は錫を含有する合金であることが好ましい。上記合金は、錫−銀合金、錫−銅合金、錫−銀−銅合金、錫−ビスマス合金、錫−亜鉛合金等が挙げられる。
なかでも、各電極材料に対し濡れ性が優れることから、低融点金属は、錫、錫−銀合金、錫−銀−銅合金が好適である。
The low melting point metal constituting the low melting point metal layer is not particularly limited, but is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, and a tin-zinc alloy.
Among them, tin, tin-silver alloy, and tin-silver-copper alloy are suitable as the low melting point metal because wettability is excellent for each electrode material.

更に、上記低融点金属層と電極との接合強度を向上させるために、上記低融点金属層に、ニッケル、銅、アンチモン、アルミニウム、亜鉛、鉄、金、チタン、リン、ゲルマニウム、テルル、コバルト、ビスマス、マンガン、クロム、モリブデン、パラジウム等の金属を含有させてもよい。なかでも、上記低融点金属層と電極との接合強度を向上させる効果に優れていることから、上記低融点金属層に、ニッケル、銅、アンチモン、アルミニウム、亜鉛を含有させることが好適である。
上記低融点金属層中に含有される金属の合計に占める上記金属の含有量は特に限定されないが、好ましい下限は0.0001重量%、好ましい上限は1重量%である。上記低融点金属層中に含有される金属の合計に占める上記金属の含有量が、0.0001〜1重量%の範囲内であることにより、上記低融点金属層と電極との接合強度をより向上させることができる。
Furthermore, in order to improve the bonding strength between the low-melting-point metal layer and the electrode, the low-melting-point metal layer includes nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, Metals such as bismuth, manganese, chromium, molybdenum, and palladium may be included. Especially, since it is excellent in the effect which improves the joining strength of the said low melting metal layer and an electrode, it is suitable to make the said low melting metal layer contain nickel, copper, antimony, aluminum, and zinc.
The content of the metal in the total of metals contained in the low melting point metal layer is not particularly limited, but a preferable lower limit is 0.0001% by weight and a preferable upper limit is 1% by weight. When the content of the metal in the total of metals contained in the low-melting-point metal layer is within the range of 0.0001 to 1% by weight, the bonding strength between the low-melting-point metal layer and the electrode is further increased. Can be improved.

上記低融点金属層における上記錫の含有量は、40重量%以上であることが好ましい。上記含有量が40重量%未満であると、本発明の効果が充分に得られず、実装不良を招くことがある。なお、上記低融点金属層における錫の含有量とは、低融点金属層に含有される元素の合計に占める錫の割合を意味し、上記低融点金属層の錫含有量は、高周波誘導結合プラズマ発光分光分析装置(堀場製作所社製「ICP−AES」)、蛍光X線分析装置(島津製作所社製「EDX−800HS」)等を用いて測定することができる。 The tin content in the low melting point metal layer is preferably 40% by weight or more. When the content is less than 40% by weight, the effects of the present invention cannot be sufficiently obtained, and mounting defects may be caused. The tin content in the low melting point metal layer means the ratio of tin to the total of the elements contained in the low melting point metal layer, and the tin content in the low melting point metal layer is the high frequency inductively coupled plasma. It can be measured using an emission spectroscopic analyzer (“ICP-AES” manufactured by Horiba, Ltd.), a fluorescent X-ray analyzer (“EDX-800HS” manufactured by Shimadzu).

上記低融点金属層の厚さは特に限定されないが、好ましい下限は0.1μm、好ましい上限は200μmである。上記低融点金属層の厚さが0.1μm未満であると、リフローして溶融させても充分に電極に接合できないことがあり、上記低融点金属層の厚さが200μmを超えると、上記低融点金属層を形成する際に凝集が生じやすく、凝集した導電性微粒子は隣接電極間の短絡を引き起こすことがある。上記低融点金属層の厚さのより好ましい下限は0.2μm、より好ましい上限は50μmである。
なお、上記低融点金属層の厚さは、無作為に選んだ10個の導電性微粒子の断面を走査型電子顕微鏡(SEM)により観察して測定し、測定値を算術平均した厚さである。
Although the thickness of the said low melting metal layer is not specifically limited, A preferable minimum is 0.1 micrometer and a preferable upper limit is 200 micrometers. When the thickness of the low-melting-point metal layer is less than 0.1 μm, it may not be able to be sufficiently bonded to the electrode even when reflowed and melted. When the thickness of the low-melting-point metal layer exceeds 200 μm, Aggregation tends to occur when the melting point metal layer is formed, and the aggregated conductive fine particles may cause a short circuit between adjacent electrodes. The minimum with more preferable thickness of the said low melting metal layer is 0.2 micrometer, and a more preferable upper limit is 50 micrometers.
The thickness of the low-melting-point metal layer is a thickness obtained by observing and measuring the cross section of 10 randomly selected conductive fine particles with a scanning electron microscope (SEM) and arithmetically averaging the measured values. .

上記低融点金属層は、上記導電層側に密着層を有する構成であってもよい。
上記密着層は、置換めっきによって形成されていることが好ましい。これにより、導電層と低融点金属層との密着性が大幅に向上するため、一次実装後に導電層が露出することに起因する接合不良の発生を効果的に防止できる。
The low melting point metal layer may have a close contact layer on the conductive layer side.
The adhesion layer is preferably formed by displacement plating. As a result, the adhesion between the conductive layer and the low-melting-point metal layer is greatly improved, so that it is possible to effectively prevent the occurrence of poor bonding due to the exposure of the conductive layer after the primary mounting.

上記密着層を形成する金属は、錫が好ましいが、錫以外の元素を含有してもよく、錫と他の金属との合金としてもよい。上記合金は特に限定されず、例えば、錫−銅合金、錫−銀合金、錫−ビスマス合金、錫−亜鉛合金、錫−インジウム合金等が挙げられる。 The metal forming the adhesion layer is preferably tin, but may contain an element other than tin, or may be an alloy of tin and another metal. The said alloy is not specifically limited, For example, a tin-copper alloy, a tin-silver alloy, a tin-bismuth alloy, a tin-zinc alloy, a tin-indium alloy etc. are mentioned.

上記置換めっきとは、金属塩溶液を含有するめっき液に被めっき物を浸漬し、被めっき物の素地金属と置換めっき液中の金属イオンとのイオン化傾向の差を利用して素地金属に金属イオンを析出させる方法である。例えば、イオン化傾向の小さい金属イオンを含有するめっき液に、イオン化傾向の大きい金属からなる導電層が形成された基材微粒子を浸漬させることで、イオン化傾向の大きい金属を溶解させ、イオン化傾向の小さい金属からなる密着層を形成することができる。
なお、上記置換めっきは、金属イオンを含有するめっき液中で被めっき物の素地金属を陰極として通電し、表面に金属被膜を析出させる電気めっきとは異なるめっき方法であり、また、還元補助剤を加えることで、めっき液中の金属イオンを化学的に還元析出させ、素地金属表面に金属被膜を形成する無電解還元めっきとも異なるめっき方法である。
The above displacement plating is a method of immersing an object to be plated in a plating solution containing a metal salt solution, and using the difference in ionization tendency between the substrate metal of the object to be plated and the metal ion in the displacement plating solution, This is a method for precipitating ions. For example, by immersing a substrate fine particle on which a conductive layer made of a metal having a high ionization tendency is formed in a plating solution containing metal ions having a low ionization tendency, the metal having a high ionization tendency is dissolved and the ionization tendency is low. An adhesion layer made of metal can be formed.
The above displacement plating is a plating method different from electroplating in which a base metal of an object to be plated is energized as a cathode in a plating solution containing metal ions, and a metal film is deposited on the surface. Is different from electroless reduction plating in which metal ions in the plating solution are chemically reduced and deposited to form a metal film on the surface of the base metal.

上記置換めっき工程において使用する置換めっき液については、金属イオンを含有するものであれば特に限定されず、例えば、錫イオンや銀イオン等を含有するもの等が挙げられる。また、金属イオンの濃度は、導電層の材質に応じて適宜変更することが好ましい。
また、上記置換めっき液には、素地金属の電位を下げ、素地金属よりイオン化傾向が高いめっき液中の金属イオンでも析出が可能となることを目的として、各種の酸や錯化剤、その他添加剤を加えてもよい。更に、上記金属イオンの対イオンとして、硫酸イオン、硝酸イオン、ハロゲン化物イオン等の各種対イオンを含有していてもよい。
The substitution plating solution used in the substitution plating step is not particularly limited as long as it contains metal ions, and examples thereof include those containing tin ions and silver ions. In addition, it is preferable that the concentration of metal ions is appropriately changed according to the material of the conductive layer.
In addition, various acids, complexing agents, and other additives are added to the above replacement plating solution for the purpose of lowering the potential of the base metal and allowing precipitation of metal ions in the plating solution, which has a higher ionization tendency than the base metal. An agent may be added. Furthermore, various counter ions such as sulfate ions, nitrate ions, halide ions may be contained as counter ions of the metal ions.

本発明の導電性微粒子の製造方法は、上述のような形状を有する低融点金属層が得られる方法であれば特に限定されないが、例えば、基材微粒子の表面に無電解めっき法等により銅を含有する導電層を形成する工程と、上記導電層上に、錫又は錫と他の金属との合金からなる低融点金属層を形成する工程を有する方法が好ましい。
また、上記導電層上に置換めっきにより錫等を含有する密着層を形成する工程を行った後、更に、錫又は錫と他の金属との合金からなる層を形成することにより、低融点金属層を形成してもよい。
The method for producing the conductive fine particles of the present invention is not particularly limited as long as the low melting point metal layer having the shape as described above can be obtained. For example, the surface of the substrate fine particles is coated with copper by an electroless plating method or the like. A method having a step of forming a conductive layer to be contained and a step of forming a low melting point metal layer made of tin or an alloy of tin and another metal on the conductive layer is preferable.
Moreover, after performing the process of forming the contact | adherence layer containing a tin etc. by displacement plating on the said conductive layer, further, by forming the layer which consists of an alloy of tin or tin, and another metal, low melting-point metal A layer may be formed.

本発明の導電性微粒子を製造する方法において、上記銅等の金属を含有する導電層を形成する工程には、従来公知の方法を用いることができる。また、密着層を形成する工程としては、上述した方法を用いることができる。 In the method for producing conductive fine particles of the present invention, a conventionally known method can be used in the step of forming the conductive layer containing the metal such as copper. In addition, as the step of forming the adhesion layer, the above-described method can be used.

上記低融点金属層を形成する工程としては、導電層が形成された基材微粒子に、錫又は錫と他の金属との合金を含有する低融点金属微粒子を接触させ、せん断圧縮によって低融点金属微粒子を溶融させることにより、低融点金属層を形成する工程を有する方法(乾式被覆法)を用いた場合、低融点金属層表面の算術平均粗さが50nm以下である導電性微粒子を好適に製造することができる。 As the step of forming the low melting point metal layer, the low melting point metal fine particles containing tin or an alloy of tin and another metal are brought into contact with the base material fine particles on which the conductive layer is formed, and the low melting point metal is formed by shear compression. When a method having a step of forming a low melting point metal layer by melting the fine particles (dry coating method) is used, conductive fine particles having an arithmetic average roughness of the surface of the low melting point metal layer of 50 nm or less are preferably produced. can do.

上記乾式被覆法では、例えば、シータコンポーザ(徳寿工作所社製)を用いる方法等が挙げられる。上記シータコンポーザは、楕円形のキャビティを備えるベッセルと、キャビティ内でこのベッセルと同一軸上において別個に回転されるローターとを備えており、混合に際しては、ベッセルとローターとを逆回転させることにより、キャビティの短径とローターの長径とが一致する付近の間隙内で、せん断圧縮力を作用することができる。このせん断圧縮によって低融点金属微粒子を溶融軟化させ、低融点金属微粒子を基材微粒子に付着させることを繰り返すことにより、基材微粒子の導電層の表面に低融点金属層が形成された導電性微粒子を製造することができる。 Examples of the dry coating method include a method using a theta composer (manufactured by Tokuju Kogakusho Co., Ltd.). The theta composer includes a vessel having an elliptical cavity and a rotor that is separately rotated on the same axis as the vessel in the cavity. During mixing, the vessel and the rotor are rotated in reverse. A shear compressive force can be applied in the gap in the vicinity where the minor axis of the cavity and the major axis of the rotor coincide. Conductive fine particles in which a low-melting-point metal layer is formed on the surface of the conductive layer of the base particle by repeatedly melting and softening the low-melting-point metal fine particle by this shear compression and attaching the low-melting-point metal fine particle to the base particle. Can be manufactured.

上記低融点金属層を形成するときに用いる低融点金属微粒子の平均粒子径は特に限定されないが、好ましい下限は0.1μm、好ましい上限は100μmである。上記低融点金属微粒子の平均粒子径が0.1μm未満であると、低融点金属微粒子が凝集しやすくなるため、低融点金属層を形成することが困難となることがある。上記低融点金属微粒子の平均粒子径が100μmを超えると、せん断圧縮時に溶融軟化しきらず、低融点金属層を形成することが困難となるときがある。なお、上記低融点金属微粒子の平均粒子径は、光学顕微鏡又は電子顕微鏡を用いて無作為に選んだ50個の低融点金属微粒子の粒子径を測定し、測定した粒子径を算術平均することにより求めることができる。
また、上記低融点金属微粒子の平均粒子径は、上記基材微粒子の平均粒子径の1/10以下であることが好ましい。上記低融点金属微粒子の平均粒子径が、上記基材微粒子の平均粒子径の1/10を超えると、せん断圧縮時に上記低融点金属微粒子を上記基材微粒子の導電層に付着、皮膜化させることができないことがある。
The average particle diameter of the low melting point metal fine particles used when forming the low melting point metal layer is not particularly limited, but the preferred lower limit is 0.1 μm and the preferred upper limit is 100 μm. When the average particle diameter of the low melting point metal fine particles is less than 0.1 μm, the low melting point metal fine particles are likely to aggregate, and it may be difficult to form the low melting point metal layer. When the average particle diameter of the low melting point metal fine particles exceeds 100 μm, it may be difficult to form a low melting point metal layer without being melted and softened during shear compression. The average particle size of the low-melting-point metal fine particles is obtained by measuring the particle sizes of 50 low-melting-point metal fine particles selected at random using an optical microscope or an electron microscope, and arithmetically averaging the measured particle sizes. Can be sought.
Moreover, it is preferable that the average particle diameter of the said low melting metal fine particle is 1/10 or less of the average particle diameter of the said base particle. When the average particle size of the low-melting-point metal fine particles exceeds 1/10 of the average particle size of the substrate fine particles, the low-melting-point metal fine particles adhere to the conductive layer of the substrate fine particles and form a film during shear compression. May not be possible.

本発明の導電性微粒子をバインダー樹脂に分散させることにより異方性導電材料を製造することができる。このような異方性導電材料もまた、本発明の1つである。 An anisotropic conductive material can be produced by dispersing the conductive fine particles of the present invention in a binder resin. Such an anisotropic conductive material is also one aspect of the present invention.

本発明の異方性導電材料として、例えば、異方性導電ペースト、異方性導電インク、異方性導電接着剤、異方性導電フィルム、異方性導電シート等が挙げられる。 Examples of the anisotropic conductive material of the present invention include anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, anisotropic conductive film, and anisotropic conductive sheet.

上記バインダー樹脂は特に限定されないが、絶縁性の樹脂が用いられ、例えば、ビニル樹脂、熱可塑性樹脂、硬化性樹脂、熱可塑性ブロック共重合体、エラストマー等が挙げられる。
上記ビニル樹脂は特に限定されないが、例えば、酢酸ビニル樹脂、アクリル樹脂、スチレン樹脂等が挙げられる。
上記熱可塑性樹脂は特に限定されないが、例えば、ポリオレフィン樹脂、エチレン−酢酸ビニル共重合体、ポリアミド樹脂等が挙げられる。
上記硬化性樹脂は特に限定されないが、例えば、エポキシ樹脂、ウレタン樹脂、ポリイミド樹脂、不飽和ポリエステル樹脂等が挙げられる。なお、上記硬化性樹脂は、常温硬化型樹脂、熱硬化型樹脂、光硬化型樹脂、湿気硬化型樹脂であってもよい。上記硬化性樹脂は硬化剤と併用してもよい。
上記熱可塑性ブロック共重合体は特に限定されないが、例えば、スチレン−ブタジエン−スチレンブロック共重合体、スチレン−イソプレン−スチレンブロック共重合体、スチレン−ブタジエン−スチレンブロック共重合体の水素添加物、スチレン−イソプレン−スチレンブロック共重合体の水素添加物等が挙げられる。
上記エラストマーは特に限定されないが、例えば、スチレン−ブタジエン共重合ゴム、アクリロニトリル−スチレンブロック共重合ゴム等が挙げられる。
これらの樹脂は、単独で用いられてもよいし、2種以上が併用されてもよい。
The binder resin is not particularly limited, but an insulating resin is used, and examples thereof include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, and an elastomer.
Although the said vinyl resin is not specifically limited, For example, a vinyl acetate resin, an acrylic resin, a styrene resin etc. are mentioned.
Although the said thermoplastic resin is not specifically limited, For example, polyolefin resin, ethylene-vinyl acetate copolymer, a polyamide resin etc. are mentioned.
Although the said curable resin is not specifically limited, For example, an epoxy resin, a urethane resin, a polyimide resin, an unsaturated polyester resin etc. are mentioned. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent.
The thermoplastic block copolymer is not particularly limited. For example, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated product of styrene-butadiene-styrene block copolymer, styrene -Hydrogenated product of isoprene-styrene block copolymer.
The elastomer is not particularly limited, and examples thereof include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.
These resins may be used alone or in combination of two or more.

本発明の異方性導電材料は、本発明の導電性微粒子、及び、上記バインダー樹脂の他に、本発明の課題達成を阻害しない範囲で、例えば、増量剤、可塑剤、粘接着性向上剤、酸化防止剤、熱安定剤、光安定剤、紫外線吸収剤、着色剤、難燃剤、有機溶媒等を含有してもよい。 In addition to the conductive fine particles of the present invention and the above-mentioned binder resin, the anisotropic conductive material of the present invention is, for example, an extender, a plasticizer, and improved adhesiveness within a range that does not hinder the achievement of the present invention. Agents, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, flame retardants, organic solvents, and the like.

本発明の異方性導電材料の製造方法は特に限定されず、例えば、上記バインダー樹脂に本発明の導電性微粒子を添加し、均一に混合して分散させ、例えば、異方性導電ペースト、異方性導電インク、異方性導電接着剤等を製造する方法が挙げられる。また、上記バインダー樹脂に本発明の導電性微粒子を添加し、均一に分散させるか、又は、加熱溶解させて、離型紙や離型フィルム等の離型材の離型処理面に所定のフィルム厚さとなるように塗工し、例えば、異方性導電フィルム、異方性導電シート等を製造する方法も挙げられる。
また、上記バインダー樹脂と、本発明の導電性微粒子とを混合することなく、別々に用いて異方性導電材料としてもよい。
The method for producing the anisotropic conductive material of the present invention is not particularly limited. For example, the conductive fine particles of the present invention are added to the binder resin, and the mixture is uniformly mixed and dispersed. Examples thereof include a method for producing an anisotropic conductive ink, an anisotropic conductive adhesive and the like. Further, the conductive fine particles of the present invention are added to the binder resin and uniformly dispersed or dissolved by heating, and a predetermined film thickness is applied to a release treatment surface of a release material such as release paper or release film. For example, a method for producing an anisotropic conductive film, an anisotropic conductive sheet or the like by coating may be used.
Moreover, it is good also as an anisotropic conductive material by using separately the said binder resin and the electroconductive fine particles of this invention, without mixing.

本発明の導電性微粒子又は本発明の異方性導電材料を用いてなる接続構造体もまた、本発明の1つである。 A connection structure using the conductive fine particles of the present invention or the anisotropic conductive material of the present invention is also one aspect of the present invention.

本発明の接続構造体は、一対の回路基板間に、本発明の導電性微粒子又は本発明の異方性導電材料を充填することにより、一対の回路基板間を接続させた導電接続構造体である。 The connection structure of the present invention is a conductive connection structure in which a pair of circuit boards are connected by filling the pair of circuit boards with the conductive fine particles of the present invention or the anisotropic conductive material of the present invention. is there.

本発明によれば、保管時における黒化現象の発生を抑制して、高い接続信頼性を実現することが可能な導電性微粒子、該導電性微粒子を用いてなる異方性導電材料、及び、接続構造体を提供することができる。 According to the present invention, conductive fine particles capable of suppressing the occurrence of blackening phenomenon during storage and realizing high connection reliability, an anisotropic conductive material using the conductive fine particles, and A connection structure can be provided.

実施例1で得られた導電性微粒子表面の原子間力顕微鏡画像である。2 is an atomic force microscope image of the surface of conductive fine particles obtained in Example 1. FIG. 比較例1で得られた導電性微粒子表面の原子間力顕微鏡画像である。2 is an atomic force microscope image of the surface of conductive fine particles obtained in Comparative Example 1.

以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されない。 Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(実施例1)
テトラメチロールメタンテトラアクリレートとジビニルベンゼンとの共重合体からなる樹脂微粒子(平均粒子径240μm)の表面に、電気めっきにより厚さ10μmの銅層を形成し、基材微粒子を得た。
次いで、得られた銅層形成基材微粒子90gに対して、下記組成の錫めっき液(めっき液温20℃)500gを用いて置換めっきを行い、銅層形成樹脂微粒子の表面に厚さ0.5μmの錫層を形成した。
Example 1
A copper layer having a thickness of 10 μm was formed by electroplating on the surface of resin fine particles (average particle diameter of 240 μm) made of a copolymer of tetramethylolmethane tetraacrylate and divinylbenzene to obtain substrate fine particles.
Subsequently, substitution plating was performed on 90 g of the obtained copper layer forming substrate fine particles using 500 g of a tin plating solution (plating solution temperature 20 ° C.) having the following composition, and a thickness of 0. A 5 μm tin layer was formed.

(錫めっき液組成)
硫酸錫 15g
メタンスルホン酸 75g
チオ尿素 45g
水 365g
(Tin plating solution composition)
15 g of tin sulfate
Methanesulfonic acid 75g
Thiourea 45g
365g of water

次いで、銅層及び錫層を形成した樹脂微粒子と、錫96.5銀3.5合金微粒子(粒子径分布5〜15μm)165gとをシータコンポーザ(徳寿工作所社製)に投入して混合した。これにより、錫96.5銀3.5合金微粒子を銅層及び錫層を形成した樹脂微粒子に付着、皮膜化させて、厚さ25μmの錫96.5銀3.5合金層を形成し、導電性微粒子を得た。なお、シータコンポーザを用いて混合する際には、回転容器(ベッセル)を35rpm、回転翼(ローター)を3500rpmで逆回転させ、せん断圧縮力が作用するようにした。混合時間は300分間とした。 Next, resin fine particles on which a copper layer and a tin layer were formed and 165 g of tin 96.5 silver 3.5 alloy fine particles (particle size distribution: 5 to 15 μm) were put into a Theta composer (manufactured by Tokuju Kogakusha Co., Ltd.) and mixed. . Thereby, the tin 96.5 silver 3.5 alloy fine particles were adhered to the resin fine particles on which the copper layer and the tin layer were formed and formed into a film to form a tin 96.5 silver 3.5 alloy layer having a thickness of 25 μm. Conductive fine particles were obtained. When mixing using a theta composer, the rotating container (vessel) was rotated in reverse at 35 rpm and the rotating blade (rotor) was rotated in reverse at 3500 rpm so that the shear compression force was applied. The mixing time was 300 minutes.

(実施例2)
実施例1において、樹脂微粒子(平均粒子径240μm)に代えて、銅微粒子(平均粒子径260μm)を用い、銅層を形成しなかった以外は実施例1と同様にして導電性微粒子を作製した。
(Example 2)
In Example 1, conductive fine particles were produced in the same manner as in Example 1 except that copper fine particles (average particle size 260 μm) were used instead of resin fine particles (average particle size 240 μm) and no copper layer was formed. .

(実施例3)
実施例1において、錫96.5銀3.5合金微粒子(粒子径分布5〜15μm)に代えて、錫96.5銀3.0銅0.5合金微粒子(粒子径分布5〜15μm)を用いた以外は実施例1と同様にして導電性微粒子を作製した。
(Example 3)
In Example 1, instead of tin 96.5 silver 3.5 alloy fine particles (particle size distribution 5-15 μm), tin 96.5 silver 3.0 copper 0.5 alloy fine particles (particle size distribution 5-15 μm) were used. Conductive fine particles were produced in the same manner as in Example 1 except that they were used.

(実施例4)
実施例1において、錫96.5銀3.5合金微粒子(粒子径分布5〜15μm)に代えて、錫42.0ビスマス58.0合金微粒子(粒子径分布5〜15μm)を用いた以外は実施例1と同様にして導電性微粒子を作製した。
Example 4
In Example 1, tin 42.0 bismuth 58.0 alloy fine particles (particle size distribution 5 to 15 μm) were used in place of tin 96.5 silver 3.5 alloy fine particles (particle size distribution 5 to 15 μm). Conductive fine particles were produced in the same manner as in Example 1.

(比較例1)
実施例1と同様の方法で、テトラメチロールメタンテトラアクリレートとジビニルベンゼンとの共重合体からなる樹脂微粒子(平均粒子径240μm)の表面に、銅層及び錫層を形成した。
次いで、得られた銅層及び錫層を形成した樹脂微粒子の表面に電気めっきにより厚さ25μmの錫96.5銀3.5合金層を形成し、導電性微粒子を得た。
(Comparative Example 1)
In the same manner as in Example 1, a copper layer and a tin layer were formed on the surface of resin fine particles (average particle size 240 μm) made of a copolymer of tetramethylolmethane tetraacrylate and divinylbenzene.
Next, a tin 96.5 silver 3.5 alloy layer having a thickness of 25 μm was formed by electroplating on the surface of the resin fine particles on which the obtained copper layer and tin layer were formed, and conductive fine particles were obtained.

(比較例2)
比較例1と同様の方法で得られた導電性微粒子を5wt%の硫酸水溶液に60分間分散し、ろ過及び水洗後、乾燥させることで、表面の微細な凹凸形状を溶解し、平滑化させた導電性微粒子を得た。
(Comparative Example 2)
Conductive fine particles obtained by the same method as in Comparative Example 1 were dispersed in a 5 wt% sulfuric acid aqueous solution for 60 minutes, filtered, washed with water, and dried to dissolve and smooth the fine irregularities on the surface. Conductive fine particles were obtained.

<評価>
実施例及び比較例で得られた導電性微粒子について、以下の評価を行った。結果を表1に示した。
<Evaluation>
The following evaluation was performed about the electroconductive fine particles obtained by the Example and the comparative example. The results are shown in Table 1.

(1)表面粗さ測定
原子間力顕微鏡(VN−8000:キーエンス社製)を用い、得られた導電性微粒子表面の算術平均粗さをJIS B0601−1994に準拠した方法で測定した。なお、測定においては、2次曲面補正(自動)を行い、断面形状についても同様の補正を行った。
なお、実施例1で得られた導電性微粒子表面の原子間力顕微鏡画像を図1、比較例1で得られた導電性微粒子表面の原子間力顕微鏡画像を図2に示した。
(1) Surface roughness measurement Using an atomic force microscope (VN-8000: manufactured by Keyence Corporation), the arithmetic average roughness of the surface of the obtained conductive fine particles was measured by a method based on JIS B0601-1994. In the measurement, quadratic curved surface correction (automatic) was performed, and the same correction was performed for the cross-sectional shape.
An atomic force microscope image of the surface of the conductive fine particles obtained in Example 1 is shown in FIG. 1, and an atomic force microscope image of the surface of the conductive fine particles obtained in Comparative Example 1 is shown in FIG.

(2)黒化加速試験
得られた導電性微粒子を、ガラス製容器内に入れ、振動機(シェーカー)にて1時間振動した。その後、これらの導電性微粒子を、銅電極を有するシリコンチップ上に112個搭載し、270℃に設定したリフロー炉に投入し溶融させた。次いで、走査型電子顕微鏡を用いて実装表面を観察し、銅電極上に低融点金属層が濡れ広がり、バンプ形成しているものの総数を計測した。
(2) Blackening acceleration test The obtained conductive fine particles were put in a glass container and vibrated for 1 hour with a vibrator (shaker). Thereafter, 112 of these conductive fine particles were mounted on a silicon chip having a copper electrode, and charged into a reflow furnace set at 270 ° C. to melt. Subsequently, the mounting surface was observed using a scanning electron microscope, and the total number of the low melting point metal layer wetted and spread on the copper electrode and bumps formed was measured.

本発明によれば、保管時における黒化現象の発生を抑制して、高い接続信頼性を実現することが可能な導電性微粒子、該導電性微粒子を用いてなる異方性導電材料、及び、接続構造体を提供することができる。 According to the present invention, conductive fine particles capable of suppressing the occurrence of blackening phenomenon during storage and realizing high connection reliability, an anisotropic conductive material using the conductive fine particles, and A connection structure can be provided.

Claims (6)

基材微粒子の表面に、導電層及び錫又は錫と他の金属との合金からなる低融点金属層が順次形成されている導電性微粒子であって、
前記低融点金属層は、前記導電層側に置換めっきによって形成された、錫又は錫と他の金属との合金からなる密着層を有し、
前記低融点金属層表面の算術平均粗さが50nm以下である
ことを特徴とする導電性微粒子。
Conductive fine particles in which a conductive layer and a low melting point metal layer composed of tin or an alloy of tin and other metals are sequentially formed on the surface of the base fine particles,
The low-melting-point metal layer has an adhesion layer made of tin or an alloy of tin and another metal formed by displacement plating on the conductive layer side,
Conductive fine particles, wherein the low melting point metal layer surface has an arithmetic average roughness of 50 nm or less.
導電層は、銅からなることを特徴とする請求項1記載の導電性微粒子。 2. The conductive fine particle according to claim 1 , wherein the conductive layer is made of copper. 基材微粒子は、樹脂微粒子であることを特徴とする請求項1又は2記載の導電性微粒子。 The conductive fine particles according to claim 1 , wherein the substrate fine particles are resin fine particles. 基材微粒子は、銅微粒子であることを特徴とする請求項1又は2記載の導電性微粒子。 The conductive fine particles according to claim 1 , wherein the substrate fine particles are copper fine particles. 請求項1、2、3又は4記載の導電性微粒子がバインダー樹脂に分散されてなることを特徴とする異方性導電材料。 An anisotropic conductive material, wherein the conductive fine particles according to claim 1, 2, 3, or 4 are dispersed in a binder resin. 請求項1、2、3或いは4記載の導電性微粒子、又は、請求項5記載の異方性導電材料を用いてなることを特徴とする接続構造体。 A connection structure comprising the conductive fine particles according to claim 1, 2, 3 or 4 , or the anisotropic conductive material according to claim 5 .
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