JP4674096B2 - Conductive fine particles and anisotropic conductive materials - Google Patents
Conductive fine particles and anisotropic conductive materials Download PDFInfo
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Description
本発明は、異方性導電フィルム等により電極に熱圧着した際に、樹脂排除性に優れ、かつ電極との接続面積が多く接続信頼性が優れた導電性微粒子、及び該導電性微粒子を用いた異方性導電材料に関する。 The present invention uses conductive fine particles that are excellent in resin rejection and have a large connection area with an electrode and excellent connection reliability when thermocompression bonded to the electrode with an anisotropic conductive film or the like, and the conductive fine particles. The present invention relates to an anisotropic conductive material.
導電性微粒子は、バインダー樹脂や粘接着剤等と混合、混練することにより、例えば、異方性導電ペースト、異方性導電インク、異方性導電粘接着剤、異方性導電フィルム、異方性導電シート等の異方性導電材料として広く用いられている。
これらの異方性導電材料は、例えば、液晶ディスプレイ、パーソナルコンピュータ、携帯電話等の電子機器において、基板同士を電気的に接続したり、半導体素子等の小型部品を基板に電気的に接続したりするために、相対向する基板や電極端子の間に挟み込んで使用されている。
The conductive fine particles are mixed and kneaded with a binder resin or an adhesive, for example, an anisotropic conductive paste, an anisotropic conductive ink, an anisotropic conductive adhesive, an anisotropic conductive film, Widely used as anisotropic conductive materials such as anisotropic conductive sheets.
These anisotropic conductive materials are, for example, for electrically connecting substrates in electronic devices such as liquid crystal displays, personal computers, and mobile phones, and electrically connecting small components such as semiconductor elements to the substrate. In order to do so, it is used by being sandwiched between opposing substrates and electrode terminals.
上記異方性導電材料に用いられる導電性微粒子としては、従来から、粒子径が均一で、適度な強度を有する樹脂微粒子等の非導電性微粒子の表面に、導電性膜として例えば金属メッキ層を形成させた導電性微粒子が用いられてきている。しかしながら、近年の電子機器の急激な進歩や発展に伴って、異方性導電材料として用いられる導電性微粒子の接続信頼性の更なる向上が求められてきている。
上記導電性微粒子の接続信頼性を向上させるためには、例えば表面に突起を有する導電性微粒子が報告されている（例えば、特許文献１、特許文献２参照）。
Conventionally, as the conductive fine particles used in the anisotropic conductive material, for example, a metal plating layer is used as a conductive film on the surface of non-conductive fine particles such as resin fine particles having a uniform particle size and appropriate strength. The formed conductive fine particles have been used. However, with rapid progress and development of electronic devices in recent years, further improvement in connection reliability of conductive fine particles used as anisotropic conductive materials has been demanded.
In order to improve the connection reliability of the conductive fine particles, for example, conductive fine particles having protrusions on the surface have been reported (see, for example, Patent Document 1 and Patent Document 2).
特許文献１には、非導電性微粒子に、無電解ニッケルメッキ法におけるニッケルメッキ液の自己分解を利用して、ニッケルの微小突起とニッケル被膜を同時に形成させ、導電性無電解メッキ粉体を製造する方法が記載されている。しかしながら、この製造方法では、その突起部分はニッケル塊からなる突起であり、その大きさ、形状、個数等を制御することは極めて困難であって、この突起による樹脂排除性は十分ではなかった。
また、特許文献２には、高さ０．１μｍ以下の微小突起の個数割合が８０％以上を占める導電性微粒子が記載されている。しかしながら、この微小突起は突起の大部分が０．１μｍ以下の高さであり、大きな突起に比べて、弱い荷重で圧縮される液晶表示素子の上下基板電極間の導通用途では微小突起のみが接触する点接触状態にならず接続安定性がよいとされるが、樹脂排除性に関しては、やはりこの微小突起では十分ではなかった。
In Patent Document 1, a non-conductive fine particle and a nickel coating are simultaneously formed on a non-conductive fine particle by utilizing the self-decomposition of a nickel plating solution in an electroless nickel plating method, thereby producing a conductive electroless plating powder. How to do is described. However, in this manufacturing method, the protruding portion is a protrusion made of a nickel lump, and it is extremely difficult to control the size, shape, number, and the like, and the resin exclusion property by the protrusion is not sufficient.
Patent Document 2 describes conductive fine particles in which the number ratio of microprojections having a height of 0.1 μm or less accounts for 80% or more. However, most of the microprotrusions have a height of 0.1 μm or less, and only the microprotrusions are in contact with each other between the upper and lower substrate electrodes of the liquid crystal display element that is compressed with a weaker load than the large protrusions. It is said that the connection stability is good without becoming a point contact state.
本発明の目的は、上述した現状に鑑み、異方性導電フィルム等により電極に熱圧着した際に、樹脂排除性に優れ、かつ電極との接続面積が多く接続信頼性が優れた導電性微粒子、及び該導電性微粒子を用いた異方性導電材料を提供することである。 An object of the present invention is to provide a conductive fine particle that is excellent in resin rejection and has a large connection area with an electrode and excellent connection reliability when thermally bonded to an electrode with an anisotropic conductive film or the like in view of the above-described situation And an anisotropic conductive material using the conductive fine particles.
上記目的を達成するために請求項１記載の発明は、基材微粒子の表面が導電性膜で被覆されており、前記導電性膜は表面に隆起した突起を有する導電性微粒子であって、導電性微粒子の表面積の７０〜９０％が隆起した突起で覆われており、突起の外径が１００〜４００ｎｍである突起の個数割合が、８０％以上である導電性微粒子を提供する。 In order to achieve the above object, according to the first aspect of the present invention, the surface of the substrate fine particles is coated with a conductive film, and the conductive film is a conductive fine particle having protrusions raised on the surface, 70% to 90% of the surface area of sex particles is covered with raised protrusions, the ratio of the number of projections having an outer diameter of 100~400nm projections provide der Ru conductive fine particles more than 80%.
また、請求項２記載の発明は、突起の平均高さが、導電性微粒子の平均粒子径の２〜１０％である請求項１記載の導電性微粒子を提供する。 The invention according to claim 2 provides the conductive fine particles according to claim 1, wherein the average height of the protrusions is 2 to 10% of the average particle diameter of the conductive fine particles.
また、請求項３記載の発明は、突起の高さが１００〜４００ｎｍである突起の個数割合が、８０％以上である請求項１又は２記載の導電性微粒子を提供する。 The invention according to claim 3 provides the conductive fine particles according to claim 1 or 2, wherein the ratio of the number of protrusions having a protrusion height of 100 to 400 nm is 80% or more.
また、請求項４記載の発明は、突起は、導電性物質を芯物質とする請求項１〜３のいずれか１項に記載の導電性微粒子を提供する。 The invention according to claim 4 provides the conductive fine particles according to any one of claims 1 to 3 , wherein the protrusion has a conductive substance as a core substance.
また、請求項５記載の発明は、突起は、ニッケル、銅、金、銀、及び亜鉛から選ばれる少なくとも１種の金属からなる金属粒子を芯物質とする請求項１〜４のいずれか１項に記載の導電性微粒子を提供する。 The invention of claim 5, wherein the protrusions are nickel, copper, gold, silver, and any one of claims 1 to 4, the metal particles consisting of at least one metal selected from zinc and core substance The conductive fine particles described in 1. are provided.
また、請求項６記載の発明は、基材微粒子は、樹脂微粒子である請求項１〜５のいずれか１項に記載の導電性微粒子を提供する。 The invention according to claim 6 provides the conductive fine particles according to any one of claims 1 to 5 , wherein the substrate fine particles are resin fine particles.
また、請求項７記載の発明は、最表面を金層とする導電性膜が形成されてなる請求項１〜６のいずれか１項に記載の導電性微粒子を提供する。 The invention according to claim 7 provides the conductive fine particles according to any one of claims 1 to 6 , wherein a conductive film having an outermost surface as a gold layer is formed.
また、請求項８記載の発明は、請求項１〜７のいずれか１項に記載の導電性微粒子が樹脂バインダーに分散されてなる異方性導電材料を提供する。 The invention according to claim 8 provides an anisotropic conductive material in which the conductive fine particles according to any one of claims 1 to 7 are dispersed in a resin binder.
以下、本発明の詳細を説明する。
本発明の導電性微粒子は、基材微粒子の表面が導電性膜で被覆されており、前記導電性膜は表面に隆起した突起を有するものである。
従って、本発明においては、突起は、導電性膜の表面に隆起したものとして現れ、この突起の存在により、異方性導電フィルム等により電極間を熱圧着する際に、突起が絶縁性樹脂の排除効果により、接続抵抗値が低く接続信頼性に優れた導電接続を得ることができる。
Details of the present invention will be described below.
In the conductive fine particles of the present invention, the surface of the substrate fine particles is coated with a conductive film, and the conductive film has protrusions protruding on the surface.
Therefore, in the present invention, the protrusion appears as a protrusion on the surface of the conductive film. Due to the presence of this protrusion, the protrusion is made of an insulating resin when thermocompression bonding between the electrodes is performed using an anisotropic conductive film or the like. Due to the exclusion effect, a conductive connection having a low connection resistance value and excellent connection reliability can be obtained.
本発明の導電性微粒子は、導電性微粒子の表面積の７０〜９０％が隆起した突起で覆われていることが必要である。導電性微粒子の表面積の７０〜９０％が隆起した突起で覆われていることにより、表面上の突起の個数が十分となり、電極間に熱圧着して用いられた際に、樹脂排除性に優れ、電極に十分な個数の突起が接続され電極との接続面積が多くなり、接続抵抗値が低く接続信頼性に優れた導電接続を得ることができる。 In the conductive fine particles of the present invention, it is necessary that 70 to 90% of the surface area of the conductive fine particles is covered with raised protrusions. 70 to 90% of the surface area of the conductive fine particles is covered with raised protrusions, so that the number of protrusions on the surface is sufficient, and when used by thermocompression bonding between electrodes, it is excellent in resin rejection. A sufficient number of protrusions are connected to the electrode, the connection area with the electrode is increased, and a conductive connection having a low connection resistance value and excellent connection reliability can be obtained.
上記突起で覆われる面積が導電性微粒子の表面積の７０％未満であると、電極に接続される突起の個数が少なく、突起による樹脂排除効果が十分得られなかったり、電極との接続面積が十分得られなかったりすることがある。また、突起で覆われる面積が導電性微粒子の表面積の９０％を超えると、突起の個数が多くなり過ぎて、逆に突起による樹脂排除効果が得られなくなったりすることがある。 If the area covered by the protrusion is less than 70% of the surface area of the conductive fine particles, the number of protrusions connected to the electrode is small, and the resin removal effect by the protrusion cannot be obtained sufficiently, or the connection area with the electrode is sufficient. It may not be obtained. On the other hand, if the area covered by the protrusions exceeds 90% of the surface area of the conductive fine particles, the number of protrusions may increase so that the resin removal effect by the protrusions may not be obtained.
本発明における突起の平均高さは、導電性微粒子の平均粒子径（直径）の２〜１０％であることが好ましい。
上記突起の平均高さは、導電性微粒子の平均粒子径の２％未満であると、突起の効果が得られにくく、１０％を超えると、電極に深くめり込み電極を破損させる恐れがある。
なお、上記突起の高さは、導電性微粒子において最表面を形成する導電性膜の基準表面から突起として現れている高さを測定したものとする。また、突起の高さは、後述する電子顕微鏡による測定方法により求めることができる。
The average height of the protrusions in the present invention is preferably 2 to 10% of the average particle diameter (diameter) of the conductive fine particles.
If the average height of the protrusions is less than 2% of the average particle diameter of the conductive fine particles, it is difficult to obtain the effect of the protrusions, and if it exceeds 10%, the electrodes may be deeply sunk and damage the electrodes.
In addition, the height of the said protrusion shall measure the height which appears as a protrusion from the reference | standard surface of the electroconductive film which forms the outermost surface in electroconductive fine particles. Further, the height of the protrusion can be obtained by a measuring method using an electron microscope described later.
本発明においては、突起の高さが１００〜４００ｎｍである突起の個数割合が、８０％以上であることが好ましい。
上記の、突起の高さが１００〜４００ｎｍである突起の個数割合が、８０％未満であると、適度な高さのものが少なく突起の効果が得にくいことがある。また、突起の高さが１００ｎｍ未満であると、樹脂排除性が得られにくく、突起の高さが４００ｎｍを超えると、電極に深くめり込み電極を破損させる恐れがある。
In the present invention, the number ratio of protrusions having a protrusion height of 100 to 400 nm is preferably 80% or more.
When the ratio of the number of protrusions having a protrusion height of 100 to 400 nm is less than 80%, there are few protrusions having an appropriate height, and it may be difficult to obtain the protrusion effect. Further, if the height of the protrusion is less than 100 nm, it is difficult to obtain resin exclusion, and if the height of the protrusion exceeds 400 nm, the electrode may be deeply sunk and damage the electrode.
本発明においては、突起の外径が１００〜４００ｎｍである突起の個数割合が、８０％以上であることが好ましい。
上記の、突起の外径が１００〜４００ｎｍである突起の個数割合が、８０％未満であると、適度な外径のものが少なく突起の効果が得にくいことがある。また、突起の外径が１００ｎｍ未満であると、突起が小さ過ぎて強度が不足したり樹脂排除性が得られにくく、突起の外径が４００ｎｍを超えると、突起が大き過ぎて逆に樹脂排除性が得られなくなったり電極に深くめり込み電極を破損させたりする恐れがある。
なお、上記突起の外径は、導電性微粒子の正投影面において突起として現れている外径を測定したものとする。また、突起の外径は、後述する電子顕微鏡による測定方法により求めることができる。
In the present invention, the number ratio of protrusions having an outer diameter of protrusions of 100 to 400 nm is preferably 80% or more.
When the ratio of the number of protrusions having an outer diameter of the protrusions of 100 to 400 nm is less than 80%, the number of protrusions with an appropriate outer diameter is small and it is difficult to obtain the effect of the protrusions. Also, if the outer diameter of the protrusion is less than 100 nm, the protrusion is too small and the strength is insufficient or the resin exclusion property is difficult to obtain. If the outer diameter of the protrusion exceeds 400 nm, the protrusion is too large and the resin is excluded. May not be obtained, or the electrode may be deeply cut into the electrode and damage the electrode.
In addition, the outer diameter of the said protrusion shall measure the outer diameter which has appeared as a protrusion in the orthographic projection surface of electroconductive fine particles. Further, the outer diameter of the protrusion can be determined by a measuring method using an electron microscope described later.
本発明における隆起した突起は、導電性膜が芯物質を内包して突起を形成していてもよいし、芯物質が無く導電性膜が突起を形成していてもよい。なかでも、突起の高さ、形状、個数等を制御しやすいため、導電性膜が芯物質を内包して突起を形成していることが好ましい。 The raised protrusions in the present invention may be formed such that the conductive film contains the core substance to form protrusions, or the conductive film may have no protrusions and the conductive film may form protrusions. Especially, since it is easy to control the height, shape, number, and the like of the protrusions, the conductive film preferably includes the core material to form the protrusions.
上記芯物質の形状は、特に限定されず、例えば、球状、円盤状、柱状、板状、針状、立方体、直方体等の粒子状；複数の微小粒子が凝集した凝集塊、不定形の塊等の塊状等が挙げられる。なかでも、粒子状が好ましく、球状が特に好ましい。
従って、突起の形状は、特に限定されるものではないが、導電性膜が芯物質を内包して突起を形成している場合は、上記芯物質の形状に依存したものとなる。
The shape of the core substance is not particularly limited. For example, a spherical shape, a disk shape, a columnar shape, a plate shape, a needle shape, a cubic shape, a rectangular parallelepiped shape, or the like; Lumps and the like. Among these, particulate form is preferable, and spherical shape is particularly preferable.
Accordingly, the shape of the protrusion is not particularly limited. However, when the conductive film includes the core material to form the protrusion, the shape depends on the shape of the core material.
上記芯物質の材質は、特に限定されず、例えば、金属、金属の酸化物、黒鉛等の導電性非金属、ポリアセチレン等の導電性ポリマー等の導電性物質；樹脂、ガラス、シリカ、アルミナ等の非導電性物質が挙げられる。なかでも、接続抵抗の低い良好な導電性を得ることができるため、導電性物質が好ましい。
従って、本発明の導電性微粒子は、突起は、導電性物質を芯物質とすることが好ましい。
The material of the core substance is not particularly limited. For example, a conductive substance such as a metal, a metal oxide, a conductive nonmetal such as graphite, a conductive polymer such as polyacetylene; a resin, glass, silica, alumina, or the like. Non-conductive materials can be mentioned. Especially, since favorable electroconductivity with low connection resistance can be obtained, an electroconductive substance is preferable.
Therefore, in the conductive fine particles of the present invention, the protrusions preferably have a conductive substance as a core substance.
上記芯物質を構成する金属としては、特に限定されず、例えば、ニッケル、銅、金、銀、白金、亜鉛、鉄、鉛、錫、アルミニウム、コバルト、インジウム、クロム、チタン、アンチモン、ビスマス、ゲルマニウム、カドミウム等の金属；錫−鉛合金、錫−銅合金、錫−銀合金、錫−鉛−銀合金等の２種類以上の金属で構成される合金等が挙げられる。なかでも、適度な硬度と導電性が得られるので、ニッケル、銅、金、銀、亜鉛が好ましい。これらは単独で用いられてもよく、２種類以上が併用されてもよい。
従って、本発明の導電性微粒子は、突起は、ニッケル、銅、金、銀、及び亜鉛から選ばれる少なくとも１種の金属からなる金属粒子を芯物質とすることが好ましい。
The metal constituting the core material is not particularly limited. For example, nickel, copper, gold, silver, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, chromium, titanium, antimony, bismuth, germanium. And metals such as cadmium; alloys composed of two or more kinds of metals such as tin-lead alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and the like. Especially, since moderate hardness and electroconductivity are obtained, nickel, copper, gold | metal | money, silver, and zinc are preferable. These may be used alone or in combination of two or more.
Therefore, in the conductive fine particles of the present invention, the protrusions preferably have metal particles made of at least one metal selected from nickel, copper, gold, silver, and zinc as a core substance.
本発明における導電性膜を構成する金属としては、特に限定されず、例えば、ニッケル、銅、金、銀、白金、亜鉛、鉄、鉛、錫、アルミニウム、コバルト、インジウム、クロム、チタン、アンチモン、ビスマス、ゲルマニウム、カドミウム等の金属；錫−鉛合金、錫−銅合金、錫−銀合金、錫−鉛−銀合金等の２種類以上の金属で構成される合金等が挙げられる。なかでも、ニッケル、銅、金等が好ましい。 The metal constituting the conductive film in the present invention is not particularly limited. For example, nickel, copper, gold, silver, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, chromium, titanium, antimony, Examples include metals such as bismuth, germanium, and cadmium; alloys composed of two or more metals such as tin-lead alloy, tin-copper alloy, tin-silver alloy, and tin-lead-silver alloy. Of these, nickel, copper, gold and the like are preferable.
上記導電性膜を形成する方法は、特に限定されず、例えば、無電解メッキ、電気メッキ、スパッタリング等の方法が挙げられる。なかでも、基材微粒子が樹脂微粒子等の非導電性である場合は、無電解メッキにより形成する方法が好適に用いられる。なお、導電性膜を構成する金属には、非金属成分であるリン成分がさらに含有されていてもよい。なお、導電性膜がメッキ被膜である場合はメッキ液にリン成分は比較的一般的に含有されている。また、導電性膜を構成する金属には、その他にも非金属成分が含有されていてもよい。例えば、ホウ素成分等が含有されていてもよい。 The method for forming the conductive film is not particularly limited, and examples thereof include electroless plating, electroplating, and sputtering. Among these, when the substrate fine particles are non-conductive such as resin fine particles, a method of forming by electroless plating is preferably used. In addition, the metal which comprises a conductive film may further contain the phosphorus component which is a nonmetallic component. When the conductive film is a plating film, the plating solution contains a phosphorus component relatively generally. In addition, the metal constituting the conductive film may contain other non-metallic components. For example, a boron component or the like may be contained.
上記導電性膜の膜厚は、１０〜５００ｎｍであることが好ましい。１０ｎｍ未満であると、所望の導電性が得られ難くなることがあり、５００ｎｍを超えると、基材微粒子と導電性膜との熱膨張率の差から、この導電性膜が剥離し易くなることがある。 The thickness of the conductive film is preferably 10 to 500 nm. If the thickness is less than 10 nm, it may be difficult to obtain desired conductivity. If the thickness exceeds 500 nm, the conductive film may be easily peeled off due to the difference in thermal expansion coefficient between the base particle and the conductive film. There is.
本発明の導電性微粒子の製造方法として、例えば、導電性膜が芯物質を内包して突起を形成している導電性微粒子を製造する方法としては、特に限定されず、基材微粒子の表面に芯物質を付着させ、後述する無電解メッキにより導電性膜を被覆する方法；基材微粒子の表面を、無電解メッキにより導電性膜を被覆した後、芯物質を付着させ、更に無電解メッキにより導電性膜を被覆する方法；上述の方法において無電解メッキの代わりにスパッタリングにより導電性膜を被覆する方法等が挙げられる。 As a method for producing conductive fine particles of the present invention, for example, a method for producing conductive fine particles in which a conductive film encapsulates a core substance to form protrusions is not particularly limited. A method in which a core material is attached and a conductive film is coated by electroless plating, which will be described later; the surface of the substrate fine particles is coated with a conductive film by electroless plating, and then a core material is adhered, and further by electroless plating. A method of coating a conductive film; a method of coating a conductive film by sputtering instead of electroless plating in the above-described method, and the like.
上記の、基材微粒子の表面に芯物質を付着させる方法としては、特に限定されず、例えば、基材微粒子の分散液中に芯物質を添加し、基材微粒子の表面上に芯物質を例えばファンデルワールス力により集積させ付着させる方法；基材微粒子を入れた容器に芯物質を添加し、容器の回転等による機械的な作用により基材微粒子の表面上に芯物質を付着させる方法等が挙げられる。 The method for attaching the core substance to the surface of the substrate fine particles is not particularly limited. For example, the core substance is added to the dispersion of the substrate fine particles, and the core substance is added onto the surface of the substrate fine particles, for example. A method of collecting and adhering by van der Waals force; a method of adding a core substance to a container containing base material fine particles, and attaching a core substance on the surface of the base material fine particles by mechanical action such as rotation of the container Can be mentioned.
導電性膜中の芯物質の存在のしかたとしては、特に限定されず、例えば、基材微粒子の表面上に存在していてもよいし、基材微粒子の表面上から離れて存在していてもよい。なかでも、芯物質は基材微粒子に接触しているか、又は基材微粒子から５ｎｍ以内の距離に存在することが好ましい。また、導電性膜中の芯物質は２〜３個凝集していてもよいが、凝集個数は少ないほうが好ましい。
芯物質が基材微粒子に接触しているか、又は基材微粒子から５ｎｍ以内の距離に存在することにより、芯物質が確実に導電性膜で覆われることになり、隆起した突起の基材微粒子に対する密着性が優れた導電性微粒子を得ることができ、また、隆起した突起の高さが揃った導電性微粒子を得ることができる。従って、上記導電性微粒子を異方性導電材料として用いた電極間の接続時には、導電性微粒子の導電性能のばらつきが小さくなり、接続信頼性に優れるという効果が得られる。
The method for the presence of the core substance in the conductive film is not particularly limited. For example, the core substance may be present on the surface of the substrate fine particles, or may be present away from the surface of the substrate fine particles. Good. Especially, it is preferable that the core substance is in contact with the base particle or is present at a distance within 5 nm from the base particle. Moreover, although 2 or 3 core materials in the conductive film may be aggregated, it is preferable that the aggregate number is small.
When the core substance is in contact with the substrate fine particles or exists at a distance of 5 nm or less from the substrate fine particles, the core substance is surely covered with the conductive film, and the raised protrusions with respect to the substrate fine particles Conductive fine particles having excellent adhesion can be obtained, and conductive fine particles having raised protrusions of uniform height can be obtained. Therefore, at the time of connection between the electrodes using the conductive fine particles as an anisotropic conductive material, the variation in conductive performance of the conductive fine particles is reduced, and the effect of excellent connection reliability can be obtained.
本発明の導電性微粒子は、最表面を金層とする導電性膜が形成されてなることが好ましい。最表面を金層とすることにより、接続抵抗値の低減化や表面の安定化を図ることができる。
なお、導電性膜が、金層である場合は、あらためて金層を形成しなくても、上述の、接続抵抗値の低減化や表面の安定化を図ることができる。
The conductive fine particles of the present invention are preferably formed by forming a conductive film whose outermost surface is a gold layer. By making the outermost surface a gold layer, the connection resistance value can be reduced and the surface can be stabilized.
When the conductive film is a gold layer, the connection resistance value can be reduced and the surface can be stabilized without forming the gold layer again.
最表面を金層とする場合は、本発明における隆起した突起は、導電性微粒子の最表面の金層を突出させる。すなわち、導電性膜の表面に隆起した突起は、導電性微粒子の最表面に隆起した突起として現れる。 When the outermost surface is a gold layer, the raised protrusion in the present invention causes the outermost gold layer of the conductive fine particles to protrude. That is, the protrusion raised on the surface of the conductive film appears as a protrusion raised on the outermost surface of the conductive fine particles.
上記金層は、無電解メッキ、置換メッキ、電気メッキ、スパッタリング等の公知の方法により形成することができる。 The gold layer can be formed by a known method such as electroless plating, displacement plating, electroplating, or sputtering.
上記金層の膜厚は、特に限定されないが、１〜１００ｎｍが好ましく、より好ましくは１〜５０ｎｍである。１ｎｍ未満であると、例えば下地ニッケル層の酸化を防止することが困難となることがあり、接続抵抗値が高くなったりすることがある。１００ｎｍを超えると、例えば置換メッキの場合下地ニッケル層を侵食し基材微粒子と下地ニッケル層との密着を悪くすることがある。 Although the film thickness of the said gold layer is not specifically limited, 1-100 nm is preferable, More preferably, it is 1-50 nm. If it is less than 1 nm, for example, it may be difficult to prevent oxidation of the underlying nickel layer, and the connection resistance value may increase. When the thickness exceeds 100 nm, for example, in the case of displacement plating, the underlying nickel layer may be eroded and adhesion between the substrate fine particles and the underlying nickel layer may be deteriorated.
本発明における基材微粒子としては、適度な弾性率、弾性変形性及び復元性を有するものであれば、無機材料であっても有機材料であってもよく特に限定されないが、樹脂からなる樹脂微粒子であることが好ましい。 The substrate fine particles in the present invention are not particularly limited as long as they have an appropriate elastic modulus, elastic deformability, and resilience, and may be inorganic materials or organic materials. It is preferable that
上記樹脂微粒子としては特に限定されず、例えば、ポリエチレン、ポリプロピレン、ポリスチレン、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリテトラフルオロエチレン、ポリイソブチレン、ポリブタジエン、ポリアルキレンテレフタレート、ポリスルホン、ポリカーボネート、ポリアミド、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；（メタ）アクリル酸エステル重合体；ジビニルベンゼン重合体；ジビニルベンゼン−スチレン共重合体、ジビニルベンゼン−（メタ）アクリル酸エステル共重合体等のジビニルベンゼン系重合体等からなるものが挙げられる。上記（メタ）アクリル酸エステルは必要に応じて架橋型、非架橋型いずれを用いてもよく、これらを混合して用いてもよい。なかでも、（メタ）アクリル酸エステル重合体、ジビニルベンゼン重合体、ジビニルベンゼン系重合体からなる微粒子が好ましく用いられる。ここで、（メタ）アクリル酸エステルとはメタクリル酸エステル又はアクリル酸エステルを意味する。
これらの樹脂微粒子は、単独で用いられてもよく、２種以上が併用されてもよい。
The resin fine particles are not particularly limited. For example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyisobutylene, polybutadiene, polyalkylene terephthalate, polysulfone, polycarbonate, polyamide, phenol formaldehyde resin, Divinylbenzene such as melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin; (meth) acrylic acid ester polymer; divinylbenzene polymer; divinylbenzene-styrene copolymer, divinylbenzene- (meth) acrylic acid ester copolymer The thing which consists of a system polymer etc. is mentioned. The (meth) acrylic acid ester may be either a crosslinked type or a non-crosslinked type, if necessary, and a mixture thereof may be used. Of these, fine particles comprising a (meth) acrylic acid ester polymer, a divinylbenzene polymer, and a divinylbenzene polymer are preferably used. Here, (meth) acrylic acid ester means methacrylic acid ester or acrylic acid ester.
These resin fine particles may be used independently and 2 or more types may be used together.
上記基材微粒子の平均粒子径は１〜２０μｍが好ましく、より好ましくは１〜１０μｍである。平均粒子径が１μｍ未満であると、例えば無電解メッキをする際に凝集しやすく、単粒子としにくくなることがあり、２０μｍを超えると、異方性導電材料として基板電極間等で用いられる範囲を超えてしまうことがある。 The average particle size of the substrate fine particles is preferably 1 to 20 μm, more preferably 1 to 10 μm. When the average particle diameter is less than 1 μm, for example, it is easy to aggregate when performing electroless plating, and it may be difficult to form single particles. When it exceeds 20 μm, it is used as an anisotropic conductive material between substrate electrodes and the like. May be exceeded.
（特性の測定方法）
本発明における導電性微粒子の各種特性、例えば、導電性膜の膜厚、金層の膜厚、基材微粒子の平均粒子径、導電性微粒子の平均粒子径、突起による被覆率、突起の高さ、突起の外径等は、電子顕微鏡による導電性微粒子の粒子観察又は断面観察により得ることができる。
(Characteristic measurement method)
Various characteristics of the conductive fine particles in the present invention, for example, the thickness of the conductive film, the thickness of the gold layer, the average particle size of the substrate fine particles, the average particle size of the conductive fine particles, the coverage by the protrusions, the height of the protrusions The outer diameter of the protrusions can be obtained by observing particles or cross sections of conductive fine particles with an electron microscope.
上記断面観察を行うための試料の作製法としては、導電性微粒子を熱硬化型の樹脂に埋め込み加熱硬化させ、所定の研磨紙や研磨剤を用いて観察可能な鏡面状態にまで試料を研磨する方法等が挙げられる。 As a method of preparing a sample for performing the cross-sectional observation, conductive fine particles are embedded in a thermosetting resin and cured by heating, and the sample is polished to a specular state that can be observed using a predetermined abrasive paper or abrasive. Methods and the like.
導電性微粒子の粒子観察は、走査電子顕微鏡（ＳＥＭ）により行い、倍率としては、観察しやすい倍率を選べばよいが、例えば、４０００倍で観察することにより行う。また、導電性微粒子の断面観察は、透過電子顕微鏡（ＴＥＭ）により行い、倍率としては、観察しやすい倍率を選べばよいが、例えば、２０万倍で観察することにより行う。 The observation of the conductive fine particles is performed with a scanning electron microscope (SEM). As the magnification, an easily observable magnification may be selected. For example, observation is performed at 4000 times. Further, the cross-sectional observation of the conductive fine particles is performed with a transmission electron microscope (TEM), and as the magnification, an easily observable magnification may be selected. For example, the observation is performed at 200,000 times.
上記導電性微粒子の導電性膜や金層の平均膜厚は、無作為に選んだ１０個の粒子について測定し、それを算術平均した膜厚である。なお、個々の導電性微粒子の膜厚にむらがある場合には、その最大膜厚と最小膜厚を測定し、算術平均した値を膜厚とする。 The average film thickness of the conductive film or the gold layer of the conductive fine particles is a film thickness obtained by measuring 10 randomly selected particles and arithmetically averaging them. In addition, when the film thickness of each electroconductive fine particle has nonuniformity, the maximum film thickness and the minimum film thickness are measured, and let the film thickness be the arithmetic average value.
上記基材微粒子の平均粒子径は、無作為に選んだ２０個の基材微粒子について粒子径を測定し、それを算術平均したものとする。
上記導電性微粒子の平均粒子径は、無作為に選んだ２０個の導電性微粒子について粒子径を測定し、それを算術平均したものとする。
The average particle size of the above-mentioned substrate fine particles is obtained by measuring the particle size of 20 randomly selected substrate fine particles and arithmetically averaging them.
The average particle size of the conductive fine particles is obtained by measuring the particle size of 20 randomly selected conductive fine particles and arithmetically averaging them.
上記突起による被覆率は、導電性微粒子の正投影面において突起として現れている部分の面積の比率を測定する。このとき、突起を付与した効果が得られるものとして、導電性微粒子の平均粒子径に対し２％以上のものを突起として選ぶものとする。 The coverage by the protrusions is a ratio of the area of the portion appearing as protrusions on the orthographic projection surface of the conductive fine particles. At this time, it is assumed that the effect of providing the projection is obtained, and the projection having an average particle diameter of 2% or more is selected as the projection.
上記突起の高さは、導電性微粒子において最表面を形成する導電性膜の基準表面から突起として現れている高さを測定する。このとき、突起を付与した効果が得られるものとして、導電性微粒子の平均粒子径に対し２％以上のものを突起として選ぶものとする。
突起の平均高さは、確認された多数の突起のなかで、ほぼ全体が観察された２０個の突起について高さを測定し、それを算術平均して突起の平均高さとする。
The height of the protrusion is measured by measuring the height appearing as a protrusion from the reference surface of the conductive film forming the outermost surface in the conductive fine particles. At this time, it is assumed that the effect of providing the projection is obtained, and the projection having an average particle diameter of 2% or more is selected as the projection.
The average height of the protrusions is the average height of the protrusions obtained by measuring the heights of 20 protrusions that were observed almost entirely from among the many protrusions that were confirmed.
上記突起の外径は、導電性微粒子の正投影面において突起として現れている外径を測定する。このとき、突起を付与した効果が得られるものとして、導電性微粒子の平均粒子径に対し２％以上のものを突起として選ぶものとする。 The outer diameter of the protrusion is measured by the outer diameter appearing as a protrusion on the orthographic projection surface of the conductive fine particles. At this time, it is assumed that the effect of providing the projection is obtained, and the projection having an average particle diameter of 2% or more is selected as the projection.
（無電解メッキ）
本発明における導電性膜の形成は、例えば、無電解ニッケルメッキ法により形成することができる。上記無電解ニッケルメッキを行う方法としては、例えば、次亜リン酸ナトリウムを還元剤として構成される無電解ニッケルメッキ液を所定の方法にしたがって建浴、加温したところに、触媒付与された基材微粒子を浸漬し、Ｎｉ2+＋Ｈ2ＰＯ2 -＋Ｈ2Ｏ→Ｎｉ＋Ｈ2ＰＯ3 -＋２Ｈ+ からなる還元反応でニッケル層を析出させる方法等が挙げられる。
(Electroless plating)
The conductive film in the present invention can be formed by, for example, an electroless nickel plating method. As a method for performing the electroless nickel plating, for example, an electroless nickel plating solution composed of sodium hypophosphite as a reducing agent is erected and heated according to a predetermined method. Examples include a method of immersing material fine particles and depositing a nickel layer by a reduction reaction of Ni 2+ + H 2 PO 2 − + H 2 O → Ni + H 2 PO 3 − + 2H + .
上記触媒付与を行う方法としては、例えば、樹脂からなる基材微粒子に、アルカリ脱脂、酸中和、二塩化スズ（ＳｎＣｌ2 ）溶液におけるセンシタイジング、二塩化パラジウム（ＰｄＣｌ2）溶液におけるアクチベイチングからなる無電解メッキ前処理工程を行う方法等が挙げられる。なお、センシタイジングとは、絶縁物質の表面にＳｎ2+イオンを吸着させる工程であり、アクチベイチングとは、Ｓｎ2+＋Ｐｄ2+→Ｓｎ4+＋Ｐｄ0なる反応を絶縁物質表面に起こしてパラジウムを無電解メッキの触媒核とする工程である。 Examples of the method for applying the catalyst include, for example, alkali degreasing, acid neutralization, sensitizing in a tin dichloride (SnCl 2 ) solution, and activator in a palladium dichloride (PdCl 2 ) solution. For example, a method of performing an electroless plating pretreatment step consisting of ching. Sensitizing is a process of adsorbing Sn 2+ ions on the surface of the insulating material, and activating causes a reaction of Sn 2+ + Pd 2+ → Sn 4+ + Pd 0 on the surface of the insulating material. In this process, palladium is used as a catalyst core for electroless plating.
（異方性導電材料）
次に、本発明の異方性導電材料は、上述した本発明の導電性微粒子が樹脂バインダーに分散されてなるものである。
(Anisotropic conductive material)
Next, the anisotropic conductive material of the present invention is obtained by dispersing the above-described conductive fine particles of the present invention in a resin binder.
上記異方性導電材料としては、本発明の導電性微粒子が樹脂バインダーに分散されていれば特に限定されるものではなく、例えば、異方性導電ペースト、異方性導電インク、異方性導電粘接着剤、異方性導電フィルム、異方性導電シート等が挙げられる。 The anisotropic conductive material is not particularly limited as long as the conductive fine particles of the present invention are dispersed in a resin binder. For example, anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive An adhesive, an anisotropic conductive film, an anisotropic conductive sheet, etc. are mentioned.
本発明の異方性導電材料の作製方法としては、特に限定されるものではないが、例えば、絶縁性の樹脂バインダー中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、異方性導電粘接着剤等とする方法や、絶縁性の樹脂バインダー中に本発明の導電性微粒子を添加し、均一に混合して導電性組成物を作製した後、この導電性組成物を必要に応じて有機溶媒中に均一に溶解（分散）させるか、又は加熱溶融させて、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、必要に応じて乾燥や冷却等を行って、例えば、異方性導電フィルム、異方性導電シート等とする方法等が挙げられ、作製しようとする異方性導電材料の種類に対応して、適宜の作製方法をとればよい。また、絶縁性の樹脂バインダーと、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 an insulating resin binder, and mixed and dispersed uniformly. For example, a method of using an anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, etc., or adding the conductive fine particles of the present invention to an insulating resin binder and mixing them uniformly. After preparing the conductive composition, the conductive composition is uniformly dissolved (dispersed) in an organic solvent as necessary, or heated and melted to release a release material such as release paper or release film. Applying to the mold processing surface so as to have a predetermined film thickness, and performing drying or cooling as necessary, for example, an anisotropic conductive film, an anisotropic conductive sheet, etc. Depending on the type of anisotropic conductive material to be produced, Manufacturing methods may Taking. Further, the insulating resin binder and the conductive fine particles of the present invention may be used separately without being mixed to form an anisotropic conductive material.
上記絶縁性の樹脂バインダーの樹脂としては、特に限定されるものではないが、例えば、酢酸ビニル系樹脂、塩化ビニル系樹脂、アクリル系樹脂、スチレン系樹脂等のビニル系樹脂；ポリオレフィン系樹脂、エチレン−酢酸ビニル共重合体、ポリアミド系樹脂等の熱可塑性樹脂；エポキシ系樹脂、ウレタン系樹脂、ポリイミド系樹脂、不飽和ポリエステル系樹脂及びこれらの硬化剤からなる硬化性樹脂；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、これらの水素添加物等の熱可塑性ブロック共重合体；スチレン−ブタジエン共重合ゴム、クロロプレンゴム、アクリロニトリル−スチレンブロック共重合ゴム等のエラストマー類（ゴム類）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。また、上記硬化性樹脂は、常温硬化型、熱硬化型、光硬化型、湿気硬化型等のいずれの硬化形態であってもよい。 The resin of the insulating resin binder is not particularly limited. For example, vinyl resins such as vinyl acetate resins, vinyl chloride resins, acrylic resins, styrene resins; polyolefin resins, ethylene -Thermoplastic resins such as vinyl acetate copolymers and polyamide resins; Epoxy resins, urethane resins, polyimide resins, unsaturated polyester resins, and curable resins composed of these curing agents; styrene-butadiene-styrene blocks Thermoplastic block copolymers such as copolymers, styrene-isoprene-styrene block copolymers, and hydrogenated products thereof; elastomers such as styrene-butadiene copolymer rubber, chloroprene rubber, acrylonitrile-styrene block copolymer rubber ( Rubbers). These resins may be used alone or in combination of two or more. The curable resin may be in any curing form such as a room temperature curing type, a thermosetting type, a photocuring type, and a moisture curing type.
本発明の異方性導電材料には、絶縁性の樹脂バインダー、及び、本発明の導電性微粒子に加えるに、本発明の課題達成を阻害しない範囲で必要に応じて、例えば、増量剤、軟化剤（可塑剤）、粘接着性向上剤、酸化防止剤（老化防止剤）、熱安定剤、光安定剤、紫外線吸収剤、着色剤、難燃剤、有機溶媒等の各種添加剤の１種又は２種以上が併用されてもよい。 In addition to the insulating resin binder and the conductive fine particles of the present invention, the anisotropic conductive material of the present invention includes, for example, a bulking agent, a softening agent, etc. 1 type of various additives such as additives (plasticizers), tackifiers, antioxidants (anti-aging agents), heat stabilizers, light stabilizers, UV absorbers, colorants, flame retardants, organic solvents, etc. Or 2 or more types may be used together.
本発明は、上述の構成よりなるので、異方性導電フィルム等により電極に熱圧着した際に、樹脂排除性に優れ、かつ電極との接続面積が多く接続信頼性が優れた導電性微粒子を得ることができる。また、電極に熱圧着した際に、樹脂排除性に優れ、かつ電極との接続面積が多く接続信頼性が優れた該導電性微粒子を用いた異方性導電材料を得ることが可能となった。 Since this invention consists of the above-mentioned composition, when thermocompression bonding to an electrode with an anisotropic conductive film etc., it is excellent in resin exclusion nature, and there are many connection areas with an electrode, and conductive fine particles which were excellent in connection reliability. Obtainable. In addition, it is possible to obtain an anisotropic conductive material using the conductive fine particles having excellent resin exclusion property and a large connection area with the electrode and excellent connection reliability when thermocompression bonded to the electrode. .
以下、実施例を挙げて本発明をより詳しく説明する。なお、本発明は以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.
（実施例１）
（無電解メッキ前処理工程）
平均粒子径４μｍのジビニルベンゼン系重合体からなる基材微粒子１０ｇに、水酸化ナトリウム水溶液によるアルカリ脱脂、酸中和、二塩化スズ溶液におけるセンシタイジングを行った。その後、二塩化パラジウム溶液におけるアクチベイチングからなる無電解メッキ前処理を施し、濾過洗浄後、粒子表面にパラジウムを付着させた基材微粒子を得た。
Example 1
(Electroless plating pretreatment process)
Alkali degreasing with a sodium hydroxide aqueous solution, acid neutralization, and sensitizing in a tin dichloride solution were performed on 10 g of base material fine particles made of a divinylbenzene polymer having an average particle size of 4 μm. Thereafter, an electroless plating pretreatment consisting of activation in a palladium dichloride solution was performed, and after filtering and washing, substrate fine particles having palladium adhered to the particle surfaces were obtained.
（芯物質複合化工程）
得られた基材微粒子を脱イオン水３００ｍｌで攪拌により３分間分散させた後、その水溶液に芯物質としてニッケル粒子（三井金属社製「２００７ＳＵＳ」、平均粒子径５０ｎｍ）２．２５ｇを添加し、芯物質を付着させた基材微粒子を得た。
(Core material compounding process)
After the obtained base material fine particles were dispersed with 300 ml of deionized water by stirring for 3 minutes, 2.25 g of nickel particles (“2007SUS” manufactured by Mitsui Kinzoku Co., Ltd., average particle size 50 nm) were added to the aqueous solution as a core substance, Substrate fine particles having a core substance attached thereto were obtained.
（無電解ニッケルメッキ工程）
得られた基材微粒子を更に水１２００ｍｌで希釈し、メッキ安定剤４ｍｌを添加後、この水溶液に硫酸ニッケル４５０ｇ／ｌ、次亜リン酸ナトリウム１５０ｇ／ｌ、クエン酸ナトリウム１１６ｇ／ｌ、メッキ安定剤６ｍｌの混合溶液１２０ｍｌを８１ｍｌ／分の添加速度で定量ポンプを通して添加した。その後、ｐＨが安定するまで攪拌し、水素の発泡が停止するのを確認し、無電解メッキ前期工程を行った。
(Electroless nickel plating process)
The obtained substrate fine particles were further diluted with 1200 ml of water, and after adding 4 ml of plating stabilizer, nickel sulfate 450 g / l, sodium hypophosphite 150 g / l, sodium citrate 116 g / l, plating stabilizer were added to this aqueous solution. 120 ml of a 6 ml mixed solution was added through a metering pump at an addition rate of 81 ml / min. Then, it stirred until pH became stable, it confirmed that hydrogen foaming stopped, and the electroless-plating pre-process was performed.
次いで、更に硫酸ニッケル４５０ｇ／ｌ、次亜リン酸ナトリウム１５０ｇ／ｌ、クエン酸ナトリウム１１６ｇ／ｌ、メッキ安定剤３５ｍｌの混合溶液６５０ｍｌを２７ｍｌ／分の添加速度で定量ポンプを通して添加した。その後、ｐＨが安定するまで攪拌し、水素の発泡が停止するのを確認し、無電解メッキ後期工程を行った。 Subsequently, 650 ml of a mixed solution of 450 g / l of nickel sulfate, 150 g / l of sodium hypophosphite, 116 g / l of sodium citrate, and 35 ml of plating stabilizer was added through a metering pump at an addition rate of 27 ml / min. Then, it stirred until pH became stable, it confirmed that hydrogen foaming stopped, and the electroless-plating late process was performed.
次いで、メッキ液を濾過し、濾過物を水で洗浄した後、８０℃の真空乾燥機で乾燥してニッケルメッキされた導電性微粒子を得た。 Next, the plating solution was filtered, and the filtrate was washed with water, and then dried with a vacuum dryer at 80 ° C. to obtain nickel-plated conductive fine particles.
（金メッキ工程）
その後、更に、置換メッキ法により表面に金メッキを施し、導電性微粒子を得た。
(Gold plating process)
Thereafter, the surface was further plated with gold by a displacement plating method to obtain conductive fine particles.
（比較例１）
芯物質複合化工程において、ニッケル粒子（「２００７ＳＵＳ」、平均粒子径５０ｎｍ）２．２５ｇを添加する代わりに０．３７５ｇを添加したこと以外は実施例１と同様にして、ニッケルメッキされた導電性微粒子を得た。
その後、更に、置換メッキ法により表面に金メッキを施し、導電性微粒子を得た。
(Comparative Example 1)
In the core material compounding step, nickel-plated conductivity was obtained in the same manner as in Example 1 except that 0.375 g was added instead of adding 2.25 g of nickel particles (“2007SUS”, average particle diameter 50 nm). Fine particles were obtained.
Thereafter, the surface was further plated with gold by a displacement plating method to obtain conductive fine particles.
（比較例２）
基材微粒子に無電解メッキ前処理工程の後、芯物質複合化工程を行わなかったこと以外は実施例１と同様にして、ニッケルメッキされた導電性微粒子を得た。
その後、更に、置換メッキ法により表面に金メッキを施し、導電性微粒子を得た。
(Comparative Example 2)
Nickel-plated conductive fine particles were obtained in the same manner as in Example 1 except that the core material composite step was not performed after the electroless plating pretreatment step on the base fine particles.
Thereafter, the surface was further plated with gold by a displacement plating method to obtain conductive fine particles.
（導電性微粒子の評価）
実施例及び比較例で得られた導電性微粒子について、日本電子データム社製透過電子顕微鏡（ＴＥＭ）による断面観察、及び日立ハイテクノロジーズ社製走査電子顕微鏡（ＳＥＭ）による粒子観察を行った。
その結果、実施例１及び比較例１の導電性微粒子は、メッキ被膜の表面に隆起した突起が観察されたが、比較例２の導電性微粒子は、突起が観察されなかった。
また、これらの導電性微粒子の、ニッケル被膜の膜厚、金層の膜厚、突起による被覆率、突起の高さ、及び、突起の外径を調べた。突起の高さからは、高さ１００〜４００ｎｍの突起の個数割合を、突起の外径からは、外径１００〜４００ｎｍの突起の個数割合を、それぞれ求めた。
これらの結果を表１に示した。また、実施例１のＳＥＭ写真を図１に、比較例１のＳＥＭ写真を図２にそれぞれ示した。
(Evaluation of conductive fine particles)
About the electroconductive fine particles obtained by the Example and the comparative example, the cross-sectional observation by the JEOL datum company transmission electron microscope (TEM) and the particle | grain observation by Hitachi High-Technologies scanning electron microscope (SEM) were performed.
As a result, the conductive fine particles of Example 1 and Comparative Example 1 were observed to have protrusions protruding on the surface of the plating film, but the conductive fine particles of Comparative Example 2 were not observed to have protrusions.
Further, the thickness of the nickel coating, the thickness of the gold layer, the coverage by the protrusions, the height of the protrusions, and the outer diameter of the protrusions of these conductive fine particles were examined. From the height of the protrusion, the ratio of the number of protrusions having a height of 100 to 400 nm was obtained, and from the outer diameter of the protrusion, the ratio of the number of protrusions having an outer diameter of 100 to 400 nm was determined.
These results are shown in Table 1. The SEM photograph of Example 1 is shown in FIG. 1, and the SEM photograph of Comparative Example 1 is shown in FIG.
（異方性導電材料の評価）
実施例及び比較例で得られた導電性微粒子を用いて異方性導電材料を作製し、電極間の抵抗値を評価した。
(Evaluation of anisotropic conductive materials)
An anisotropic conductive material was produced using the conductive fine particles obtained in Examples and Comparative Examples, and the resistance value between the electrodes was evaluated.
樹脂バインダーの樹脂としてエポキシ樹脂（油化シェルエポキシ社製、「エピコート８２８」）１００重量部、トリスジメチルアミノエチルフェノール２重量部、及びトルエン１００重量部を、遊星式攪拌機を用いて充分に混合した後、離型フィルム上に乾燥後の厚さが１０μｍとなるように塗布し、トルエンを蒸発させて接着性フィルムを得た。
次いで、樹脂バインダーの樹脂としてエポキシ樹脂（油化シェルエポキシ社製、「エピコート８２８」）１００重量部、トリスジメチルアミノエチルフェノール２重量部、及びトルエン１００重量部に、得られたそれぞれの導電性微粒子を添加し、遊星式攪拌機を用いて充分に混合した後、離型フィルム上に乾燥後の厚さが７μｍとなるように塗布し、トルエンを蒸発させて導電性微粒子を含有する接着性フィルムを得た。なお、導電性微粒子の配合量は、フィルム中の含有量が５万個／ｃｍ2 となるようにした。
得られた接着性フィルムと導電性微粒子を含有する接着性フィルムとを常温でラミネートすることにより、２層構造を有する厚さ１７μｍの異方性導電フィルムを得た。
As a resin binder resin, 100 parts by weight of an epoxy resin (“Epicoat 828” manufactured by Yuka Shell Epoxy Co., Ltd.), 2 parts by weight of trisdimethylaminoethylphenol, and 100 parts by weight of toluene were sufficiently mixed using a planetary stirrer. Then, it apply | coated so that the thickness after drying might be set to 10 micrometers on a release film, and toluene was evaporated, and the adhesive film was obtained.
Next, 100 parts by weight of an epoxy resin (“Epicoat 828” manufactured by Yuka Shell Epoxy Co., Ltd.), 2 parts by weight of trisdimethylaminoethylphenol, and 100 parts by weight of toluene as a resin binder resin were obtained. And then thoroughly mixed using a planetary stirrer, and then coated on the release film so that the thickness after drying is 7 μm, and the adhesive film containing conductive fine particles is evaporated by evaporating toluene. Obtained. In addition, the compounding quantity of electroconductive fine particles was made for the content in a film to be 50,000 pieces / cm < 2 >.
By laminating the obtained adhesive film and an adhesive film containing conductive fine particles at room temperature, an anisotropic conductive film having a two-layer structure and a thickness of 17 μm was obtained.
得られた異方性導電フィルムを５×５ｍｍの大きさに切断した。これを、一方に抵抗測定用の引き回し線を有した幅２００μｍ、長さ１ｍｍ、高さ０．２μｍ、Ｌ／Ｓ２０μｍのアルミニウム電極のほぼ中央に貼り付けた後、ＩＴＯ電極を有するガラス基板を、電極同士が重なるように位置あわせをしてから貼り合わせた。
このガラス基板の接合部を、１０Ｎ、１００℃の圧着条件で熱圧着した後、電極間の抵抗値を評価した。
また、作製した試験片に対して信頼性試験（８０℃、９５％ＲＨの高温高湿環境下で１０００時間保持）を行った後、電極間の抵抗値を評価した。
これらの結果を表１に示した。
The obtained anisotropic conductive film was cut into a size of 5 × 5 mm. After affixing this to approximately the center of an aluminum electrode having a width of 200 μm, a length of 1 mm, a height of 0.2 μm, and an L / S of 20 μm having a lead wire for resistance measurement, a glass substrate having an ITO electrode is obtained. After aligning the electrodes so that they overlap each other, they were bonded together.
The bonded portion of this glass substrate was thermocompression bonded under pressure bonding conditions of 10 N and 100 ° C., and then the resistance value between the electrodes was evaluated.
Moreover, after performing the reliability test (80 degreeC, 95% RH high temperature high-humidity environment hold | maintained for 1000 hours) with respect to the produced test piece, the resistance value between electrodes was evaluated.
These results are shown in Table 1.
表１より、実施例の導電性微粒子は、導電性微粒子の表面積の７０〜９０％が隆起した突起で覆われており突起による被覆率が高いため、接続信頼性が優れていることがわかる。 From Table 1, it can be seen that the conductive fine particles of Examples have excellent connection reliability because 70 to 90% of the surface area of the conductive fine particles is covered with raised protrusions and the coverage by the protrusions is high.
本発明によれば、異方性導電フィルム等により電極に熱圧着した際に、樹脂排除性に優れ、かつ電極との接続面積が多く接続信頼性が優れた導電性微粒子、及び該導電性微粒子を用いた異方性導電材料を提供できる。 According to the present invention, when thermally bonded to an electrode with an anisotropic conductive film or the like, the conductive fine particles having excellent resin rejection and a large connection area with the electrode and excellent connection reliability, and the conductive fine particles An anisotropic conductive material using can be provided.
Claims (8)
導電性微粒子の表面積の７０〜９０％が隆起した突起で覆われており、
突起の外径が１００〜４００ｎｍである突起の個数割合が、８０％以上であることを特徴とする導電性微粒子。 The surface of the substrate fine particles is coated with a conductive film, and the conductive film is a conductive fine particle having protrusions raised on the surface,
70 to 90% of the surface area of the conductive fine particles is covered with raised protrusions ,
The ratio of the number of projections having an outer diameter of 100~400nm projections, conductive fine particles, characterized in der Rukoto 80% or more.
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| KR20160006614A (en) | 2014-07-09 | 2016-01-19 | 히타치가세이가부시끼가이샤 | Conductive particle, insulating coated conductive particle, anisotropic conductive adhesive, connecting structure, and method for producing conductive particle |
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