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JP2004265844A - Anisotropic conductive film and method for manufacturing the same - Google Patents

Anisotropic conductive film and method for manufacturing the same Download PDF

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Publication number
JP2004265844A
JP2004265844A JP2003096173A JP2003096173A JP2004265844A JP 2004265844 A JP2004265844 A JP 2004265844A JP 2003096173 A JP2003096173 A JP 2003096173A JP 2003096173 A JP2003096173 A JP 2003096173A JP 2004265844 A JP2004265844 A JP 2004265844A
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film
porous
conductive
conductive metal
porous structure
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JP2003096173A
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JP4039293B2 (en
Inventor
Takeshi Haga
剛 羽賀
Yasuhito Masuda
泰人 増田
Fumihiro Hayashi
文弘 林
Yasuhiro Okuda
泰弘 奥田
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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Priority to JP2003096173A priority Critical patent/JP4039293B2/en
Application filed by Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
Priority to EP04720240A priority patent/EP1612891B1/en
Priority to CA2522239A priority patent/CA2522239C/en
Priority to PCT/JP2004/003356 priority patent/WO2004088795A1/en
Priority to KR1020057018041A priority patent/KR101011923B1/en
Priority to HK06107734.0A priority patent/HK1087538B/en
Priority to US10/551,459 priority patent/US7563487B2/en
Priority to CNB2004800089109A priority patent/CN100369329C/en
Priority to TW093108603A priority patent/TWI342054B/en
Publication of JP2004265844A publication Critical patent/JP2004265844A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide anisotropic conductive film which has elasticity in the film thickness direction, in which conductivity in the film thickness direction with a low compressive load is possible, furthermore in which elasticity recovery is possible, and which is suitable for frequent uses. <P>SOLUTION: An electrically insulating porous film formed of a synthetic resin is made the base film, and conductive parts which are made of a conductive metal adhered to the resin part of a porous structure in a state of penetrating from a first surface through a second surface at a plurality of places of the base film, and which are capable of giving conductivity in the film thickness direction are respectively installed independently. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【0001】
【発明の属する技術分野】
本発明は、異方性導電膜とその製造方法に関し、さらに詳しくは、半導体デバイスのバーンイン試験などに好適に使用することができる異方性導電膜とその製造方法に関する。
【0002】
【従来の技術】
半導体ディバイスの初期故障を取り除くスクリーニング手法の一つとして、バーンイン試験が行われている。バーンイン試験では、半導体ディバイスの動作条件よりも高温かつ高圧の加速ストレスを印加し、故障発生を加速して短時間で不良品を取り除いている。例えば、パッケージングされた半導体ディバイスをバーンインボードに多数個配置し、高温槽中にて、外部から加速ストレストなる電源電圧及び入力信号を一定時間印加する。その後、半導体ディバイスを外部に取り出して、良品と不良品との判定試験を行う。判定試験では、半導体ディバイスの欠陥によるリーク電流の増加、多層配線の欠陥による不良品、コンタクトの欠陥などを判定する。バーンイン試験は、半導体ウェハの状態でも行われている。
【0003】
例えば、半導体ウェハのバーンイン試験を行う場合、半導体ウェハ表面のアルミニウムなどからなる電極パッドを介して試験を行う。その際、半導体ウェハの電極パッドと測定装置のヘッド電極との間の電極高さのバラツキによる接触不良を補うため、通常、これらの電極間に、膜厚方向のみに導電性を有するコンタクトシートを挟んで試験を行う。このコンタクトシートは、表面電極に対応するパターンに従って配置された導通部(「導電路」または「電極部」ともいう)において、膜厚方向のみに導電性を示すという特性により、異方性導電膜(「異方性導電シート」ともいう)と呼ばれる。
【0004】
従来、エレクトロニクス技術分野において、パッケージされた集積回路をプリント配線板に接続するなどの目的で、図6に示すように、平坦な多孔質可撓性材料63を非導電性の絶縁部とし、少なくとも1つの鉛直方向(Z軸方向)に画定された断面内に導電性金属を充填し、かつ、エポキシ樹脂などの接着剤を充填して固定した導通部62を形成した異方性導電部材61が知られている(例えば、特許文献1参照。)。しかし、この異方性導電部材61は、バーンイン試験用の異方性導電膜として使用すると、検査時の押圧によって導通部62が座屈して、弾性回復しないため、検査毎に使い捨てにせざるを得ない。そのため、検査にコストがかかりすぎることになる。したがって、この異方性導電部材61は、頻回の使用が求められるバーンイン試験用の異方性導電膜には適していない。
【0005】
また、図7に示すように、エポキシ系樹脂材料など熱硬化性樹脂から形成された封止用絶縁シート74の膜厚方向に複数の貫通孔を設け、これらの貫通孔の中に、エラストマーに導電性粒子73を分散させた導電路形成用材料を充填して、導電路72を形成した構造の半導体素子実装用シート71が提案されている(例えば、特許文献2参照。)。導電性粒子としては、例えば、金属や合金の粒子、あるいはポリマー粒子の表面を導電性金属でめっきした構造のカプセル型導電性粒子などが使用されている。
【0006】
半導体素子実装用シート71を膜厚方向に押圧すると、導電路72のエラストマーが圧縮されて導電性粒子73が連結することにより、導電路の膜厚方向のみに電気的導通が得られる。しかし、この半導体素子実装用シート71は、バーンイン試験用の異方性導電膜として使用すると、膜厚方向に導通を得るのに高圧縮荷重を必要とし、しかもエラストマーの劣化により弾性が低下するため、頻回の使用ができない。したがって、このような構造の半導体素子実装用シートは、半導体ウェハなどのバーンイン試験用の異方性導電膜としては適していない。
【0007】
他方、半導体ウェハなどのバーンイン試験用インターポーザ(interposer)などとして用いられる異方性導電膜には、半導体ウェハの表面電極を測定装置のヘッド電極に接続したり、半導体ウェハからの配線を半導体パッケージの端子と接続することなどに加えて、応力緩和の作用も求められている。そのため、異方性導電膜には、膜厚方向に弾力性があり、低圧縮荷重で膜厚方向の導通が可能であること、さらには、弾性回復が可能で、頻回の使用に適していることが求められている。また、高密度実装などに伴って、検査に使用する異方性導電膜の各導通部の大きさやピッチなどのパターンをファイン化することが要求されている。しかし、従来技術では、これらの要求に充分に応えることができる異方性導電膜を開発することができなかった。
【0008】
【特許文献1】
特表平10−503320号公報 (第1−3頁、図4)
【特許文献2】
特開平10−12673号公報 (第1−2頁、図1)
【0009】
【発明が解決しようとする課題】
本発明の目的は、主として半導体ウェハなどの検査に用いられる異方性導電膜であって、膜厚方向に弾力性があり、低圧縮荷重で膜厚方向の導通が可能で、さらには、弾性回復が可能で、頻回の使用に適している異方性導電膜を提供することにある。また、本発明の目的は、各導通部の大きさやピッチなどをファイン化することができる異方性導電膜を提供することにある。
【0010】
本発明者らは、前記目的を達成するために鋭意研究する過程で、合成樹脂から形成された電気絶縁性の多孔質膜が適度の弾性を有し、弾性回復が可能なため、異方導電性膜の基膜として適していることに着目した。しかし、多孔質膜の特定部位の多孔質構造内に導電性金属を充填して、導電性金属塊からなる導通部を形成する方法では、圧縮荷重時に導電性金属塊が座屈して弾性回復しないため、繰り返し使用することができない。
【0011】
そこで、さらに研究を続けた結果、多孔質膜の複数箇所に、膜厚方向に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させる方法により、導通部を形成すると、導通部での多孔質構造を保持することができることを見出した。もちろん、導通部においては、多孔質構造の樹脂部には導電性金属が付着しているため、多孔質膜が本来有している多孔質構造を完全には保持することができないものの、ある程度の範囲で多孔質構造を保持させることができる。すなわち、本発明の異方性導電膜は、導通部が多孔質状となっている。
【0012】
したがって、本発明の異方性導電膜は、基膜だけではなく、導通部も弾性と弾性回復性を有しており、頻回の使用が可能である。また、本発明の異方性導電膜は、低圧縮荷重で膜厚方向の導通が可能である。さらに、本発明の異方性導電膜は、導通部や導通部間のピッチなどをファイン化することもできる。本発明は、これらの知見に基づいて完成するに至ったものである。
【0013】
【課題を解決するための手段】
本発明によれば、合成樹脂から形成された電気絶縁性の多孔質膜を基膜とし、該基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に付着した導電性金属により形成され、膜厚方向に導電性を付与することが可能な導通部がそれぞれ独立して設けられていることを特徴とする異方性導電膜が提供される。
【0014】
また、本発明によれば、合成樹脂から形成された電気絶縁性の多孔質膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法が提供される。
【0015】
さらに、本発明によれば、下記1〜3に示される異方性導電膜の製造方法が提供される。
【0016】
1.(1)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層としてポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、
(2)一方のマスク層の表面から、所定のパターン状にそれぞれ独立した複数の光透過部を有する光遮蔽シートを介して、シンクロトロン放射光または波長250nm以下のレーザ光を照射することにより、積層体にパターン状の貫通孔を形成する工程、
(3)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、
(4)両面のマスク層を剥離する工程、及び
(5)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程
の各工程により、多孔質ポリテトラフルオロエチレン膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。
【0017】
2.(I)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層としてポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、
(II)先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、積層体にパターン状の貫通孔を形成する工程、
(III)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、
(IV)両面のマスク層を剥離する工程、及び
(V)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程
の各工程により、多孔質ポリテトラフルオロエチレン膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。
【0018】
3.(i)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層として多孔質ポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、
(ii)積層体の多孔質内に液体を染み込ませて、該液体を凍結させる工程、
(iii)先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、積層体にパターン状の貫通孔を形成する工程、
(iv)積層体を昇温して、多孔質内の凍結体を液体に戻して除去する工程、
(V)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、
(vi)両面のマスク層を剥離する工程、及び
(vii)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程
の各工程により、多孔質ポリテトラフルオロエチレン膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。
【0019】
【発明の実施の形態】
1.多孔質膜(基膜)
半導体ウェハなどのバーンイン試験用異方性導電膜は、基膜の耐熱性に優れていることが好ましい。異方性導電膜は、横方向(膜厚方向とは垂直方向)に電気絶縁性であることが必要である。したがって、多孔質膜を形成する合成樹脂は、電気絶縁性であることが必要である。
【0020】
基膜として使用する多孔質膜を形成する合成樹脂材料としては、ポリテトラフルオロエチレン(PTFE)、テトラフルオロエチレン/ヘキサフルオロプロピレン共重合体(FEP)、テトラフルオロエチレン/パーフルオロアルキルビニルエーテル共重合体(PFA)、ポリふっ化ビニリデン(PVDF)、ポリふっ化ビニリデン共重合体、エチレン/テトラフルオロエチレン共重合体(ETFE樹脂)などのフッ素樹脂;ポリイミド(PI)、ポリアミドイミド(PAI)、ポリアミド(PA)、変性ポリフェニレンエーテル(mPPE)、ポリフェニレンスルフィド(PPS)、ポリエーテルエーテルケトン(PEEK)、ポリスルホン(PSU)、ポリエーテルスルホン(PES)、液晶ポリマー(LCP)などのエンジニアリングプラスチック;などが挙げられる。これらの中でも、耐熱性、加工性、機械的特性、誘電特性などの観点から、PTFEが好ましい。
【0021】
合成樹脂からなる多孔質膜を作製する方法としては、造孔法、相分離法、溶媒抽出法、延伸法、レーザ照射法などが挙げられる。合成樹脂を用いて多孔質膜を形成することにより、膜厚方向に弾性を持たせることができるとともに、誘電率を更に下げることができる。
【0022】
異方性導電膜の基膜として使用する多孔質膜は、気孔率が20〜80%程度であることが好ましい。多孔質膜は、平均孔径が10μm以下あるいはバブルポイントが2kPa以上であることが好ましく、導通部のファインピッチ化の観点からは、平均孔径が1μm以下あるいはバブルポイントが10kPa以上であることがより好ましい。多孔質膜の膜厚は、使用目的や使用箇所に応じて適宜選択することができるが、通常、3mm以下、好ましくは1mm以下である。特にバーンイン試験用の異方性導電膜では、多孔質膜の膜厚は、多くの場合、好ましくは5〜500μm、より好ましくは10〜200μm、特に好ましくは15〜100μm程度である。
【0023】
多孔質膜の中でも、延伸法により得られた多孔質ポリテトラフルオロエチレン膜(以下、「多孔質PTFE膜」と略記)は、耐熱性、加工性、機械的特性、誘電特性などに優れ、しかも均一な孔径分布を有する多孔質膜が得られ易いため、異方性導電膜の基膜として最も優れた材料である。
【0024】
本発明で使用する多孔質PTFE膜は、例えば、特公昭42−13560号公報に記載の方法により製造することができる。まず、PTFEの未焼結粉末に液体潤滑剤を混合し、ラム押し出しによってチューブ状または板状に押し出す。厚みの薄いシートが所望な場合は、圧延ロールによって板状体の圧延を行う。押出圧延工程の後、必要に応じて、押出品または圧延品から液体潤滑剤を除去する。こうして得られた押出品または圧延品を少なくとも一軸方向に延伸すると、未焼結の多孔質PTFEが膜状で得られる。未焼結の多孔質PTFE膜は、収縮が起こらないように固定しながら、PTFEの融点である327℃以上の温度に加熱して、延伸した構造を焼結・固定すると、強度の高い多孔質PTFE膜が得られる。多孔質PTFE膜がチューブ状である場合には、チューブを切り開くことにより、平らな膜にすることができる。
【0025】
延伸法により得られた多孔質PTFE膜は、それぞれPTFEにより形成された非常に細い繊維(フィブリル)と該繊維によって互いに連結された結節(ノード)とからなる微細繊維状組織を有している。多孔質PTFE膜は、この微細繊維状組織が多孔質構造を形成している。
【0026】
2.導通部(電極部)の形成
本発明では、合成樹脂から形成された電気絶縁性の多孔質膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設ける。
【0027】
基膜の複数箇所に導通部を形成するには、先ず、導電性金属を付着する位置を特定する必要がある。導電性金属を付着させる位置を特定する方法としては、例えば、多孔質膜に液体レジストを含浸させて、パターン状に露光し、現像して、レジスト除去部を導電性金属の付着位置とする方法がある。本発明では、多孔質膜の特定位置の膜厚方向に微細な貫通孔を形成して、該貫通孔の壁面を導電性金属の付着位置とする方法を好適に採用することができる。多孔質膜に多数の貫通孔を形成する本発明の方法は、フォトリソグラフィ技術を用いる前者の方法に比べて、ファインピッチで導電性金属を付着させる場合に適している。また、多孔質膜に多数の貫通孔を形成する方法は、例えば、30μm以下、さらには25μm以下の微細な直径の導通部を形成するのに適している。
【0028】
本発明では、多孔質膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて導通部を形成する。フォトリソグラフィ技術を用いる方法では、無電解めっき法などによりレジスト除去部に導電性金属粒子を析出させて、多孔質構造の樹脂部に導電性金属を連続して付着させる。この場合、レジスト除去部の第一表面から第二表面に貫通する状態となるように、多孔質構造の樹脂部に導電性金属を連続して付着させる。貫通孔を形成する本発明に特有の方法では、貫通孔の壁面に露出している多孔質構造の樹脂部に、無電解めっき法などにより導電性金属粒子を析出させる方法により付着させる。
【0029】
多孔質構造の樹脂部とは、多孔質膜の多孔質構造を形成している骨格部を意味している。多孔質構造の樹脂部の形状は、多孔質膜の種類や多孔質膜の形成方法によって異なっている。例えば、延伸法による多孔質PTFE膜の場合には、多孔質構造は、それぞれPTFEからなる多数のフィブリルと該フィブリルによって互に連結された多数のノードとから形成されているので、その樹脂部は、これらのフィブリルとノードである。
【0030】
多孔質構造の樹脂部に導電性金属を付着させて導通部を形成する。この際、導電性金属の付着量を適度に制御することによって、導通部での多孔質構造を保持することができる。本発明の異方性導電膜では、導電性金属が多孔質構造の樹脂部の表面に沿って付着しているため、導電性金属層が多孔質構造と一体となって多孔質状構造となっており、その結果、導通部が多孔質状となっているということができる。
【0031】
無電解めっき法などを採用すると、導電性金属粒子が多孔質構造の樹脂部に付着する。本発明の異方性導電膜では、多孔質膜を構成する多孔質構造(多孔性)をある程度維持したまま、導電性金属粒子が付着した状態が得られる。多孔質構造の樹脂部の太さ(例えば、フィブリルの太さ)は、50μm以下であることが好ましい。導電性金属粒子の粒子径は、0.001〜5μm程度であることが好ましい。導電性金属粒子の付着量は、多孔性と弾性を維持するために、0.01〜4.0g/ml程度とすることが好ましい。基膜となる多孔質膜の気孔率にもよるが、導電性金属粒子の付着量が多すぎると、異方性導電膜の弾性が大きくなりすぎて、通常の使用圧縮荷重では、異方性導電膜の弾性回復性能が著しく低下する。導電性金属粒子の付着量が少なすぎると、圧縮荷重を加えても膜厚方向への導通を得ることが困難になる。
【0032】
貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる方法について、図面を参照しながら説明する。図1は、貫通孔が形成された多孔質膜の斜視図である。多孔質膜(基膜)1には、第一表面2から第二表面3にかけて貫通する貫通孔4が複数箇所に形成されてる。これらの貫通孔は、一般に、所定のパターンで多孔質膜に形成される。図2は、図1のA−A′線に沿った断面図であり、貫通孔の壁面で多孔質構造の樹脂部に導電性金属粒子が付着して導通部を形成している状態を示している。図2において、多孔質膜6は、基膜となっており、所定の複数箇所に貫通孔4が設けられており、貫通孔壁面の多孔質構造の樹脂部には導電性金属粒子が付着して導通部5が形成されている。この導通部は、多孔質構造の樹脂部の表面に付着して形成されているため、多孔質としての特性を有しており、膜厚方向に圧力(圧縮荷重)を加えることにより、膜厚方向のみに導電性が付与される。圧力を除去すると、導通部を含む異方性導電膜全体が弾性回復するので、本発明の異方性導電膜は、繰り返して使用することができる。
【0033】
図3は、図2の1つの導通部の拡大断面図であり、aは、貫通孔の直径を表わし、bは、導電性金属粒子が付着して形成された導通部(電極)の直径(外径)を表わす。導電性金属粒子は、貫通孔の壁面において、多孔質構造の中に若干浸透した状態で付着するため、導通部の直径bは、貫通孔の直径aより大きい。
【0034】
本発明の異方性導電膜は、圧縮荷重が加えられていない状態では、導通部の抵抗値が大きく、所定の圧縮荷重を加えた時に導通部の抵抗値が0.5Ω以下となることが望ましい。導通部の抵抗値の測定は、図5に示す導通確認装置を用いて行うが、その詳細は、実施例において説明する。
【0035】
図1に示すように、多孔質膜の複数箇所に貫通孔を設けただけでは、無電解めっき法などで貫通孔の壁面のみに導電性金属を付着させることは困難である。例えば、多孔質膜として多孔質PTFE膜を使用すると、無電解めっきにより、貫通孔の壁面だけではなく、全体の多孔質構造の樹脂部に導電性金属粒子が析出してしまう。そこで、本発明では、例えば、マスク層を用いて、貫通孔の壁面のみに導電性金属を付着させる方法を提案する。具体的には、貫通孔の壁面のみに導電性金属を析出させるため、無電解めっきにおける化学還元反応を促進する触媒粒子が基膜の表面に付着しないよう、基膜の両表面にマスク層を形成する。
【0036】
例えば、基膜として延伸法による多孔質PTFE膜を使用する場合、マスク層として使用する材料は、基膜との密着性が良好であり、基膜と同時に貫通孔が形成でき、マスク層としての役割を終えたあとには基膜との剥離が容易であることから、基膜と同材料のPTFE膜であることが好ましい。また、貫通孔を形成するエッチング速度を高めることができ、マスク層としての役割を終えたあと基膜との剥離をさらに容易にすることができる点から、マスク層は多孔質PTFE膜であることがより好ましい。マスク層の多孔質PTFE膜は、剥離し易さの観点から、気孔率20〜80%程度のものが好ましく、その膜厚は、3mm以下であることが好ましく、1mm以下であることがより好ましく、100μm以下であることが特に好ましい。また、その平均孔径は、マスク層としての耐水性の観点から、10μm以下(あるいはバブルポイントが2kPa以上)であることが好ましい。
【0037】
延伸法により得られた多孔質PTFE膜(A)を基膜として使用し、同じ材質のPTFE膜、好ましくは多孔質PTFE膜(B)及び(C)をマスク層として使用する場合について、図4を参照しながら説明する。図4に示すように、多孔質PTFE膜(A)43からなる基膜の両面に、マスク層として多孔質PTFE膜(B)44及び(C)45を融着させて3層構成の積層体を形成する。より具体的に、これらの多孔質PTFE膜を図4に示すように3層に重ね合わせ、その両面を2枚のステンレス板41,42で挟む。各ステンレス板は、平行面を有している。各ステンレス板を320〜380℃の温度で30分間以上加熱することにより、3層の多孔質PTFE膜を互いに融着させる。多孔質PTFE膜の機械的強度を高めるために、加熱処理後は冷却水などで急冷することが好ましい。このようにして、3層構成の積層体を形成する。
【0038】
多孔質膜の特定位置の膜厚方向に貫通孔を形成する方法としては、例えば、化学エッチング法、熱分解法、レーザ光や軟X線照射によるアブレーション法、超音波法などが挙げられる。基膜として延伸法による多孔質PTFE膜を使用する場合には、シンクロトロン放射光または波長250nm以下のレーザ光を照射する方法、及び超音波法が好ましい。
【0039】
多孔質PTFE膜を基膜として使用し、かつ、シンクロトロン放射光または波長250nm以下のレーザ光の照射により貫通孔を形成する工程を含む異方性導電膜の製造方法は、好ましくは、(1)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層としてポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、(2)一方のマスク層の表面から、所定のパターン状にそれぞれ独立した複数の光透過部を有する光遮蔽シートを介して、シンクロトロン放射光または波長250nm以下のレーザ光を照射することにより、積層体にパターン状の貫通孔を形成する工程、(3)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、(4)両面のマスク層を剥離する工程、及び(5)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程を含む製造方法である。
【0040】
光遮蔽シートとしては、例えば、タングステンシートが好ましい。タングステンシートにパターン状の複数の開口部を形成して、該開口部を光透過部(以下、単に「開口部」ということがある)とする。光遮蔽シートの複数の開口部より光が透過し照射された箇所は、エッチングされて貫通孔が形成される。
【0041】
光遮断シートの開口部のパターンは、円形、星型、八角形、六角形、四角形、三角形など任意の形状が可能である。開口部の孔径は、一辺もしくは径が0.1μm以上で、使用する多孔質PTFE膜の平均孔径より大きければよい。貫通孔の孔径は、作製される異方性導電膜の導通部(電極)のサイズを決定するので、作製したい導通部のサイズに応じて適宜形成すればよいが、異方性導電膜を、例えば半導体ウェハのバーンイン試験用インターポーザとして使用する場合などには、5〜100μmが好ましく、5〜30μmがより好ましい。導通部(電極)間ピッチは、5〜100μmが好ましい。
【0042】
超音波法により、多孔質膜の特定位置の膜厚方向に貫通孔を形成するには、図10に示すように、先端部に少なくとも1本のロッド102を取り付けた超音波ヘッド101を用いて、該ロッド102の先端を多孔質膜103の表面に押付けて超音波エネルギーを加える。貫通孔を形成する工程では、多孔質膜103は、例えば、シリコン、セラミックス、ガラス等の硬質材料から形成された板状体104の上に載置する。板状体を用いる代わりに、多孔質膜の上下にロッド同士を対向させてもよい。
【0043】
ロッドとしては、金属、セラミックス、ガラス等の無機材料で形成された棒状体が好ましい。ロッドの直径は、特に限定されないが、ロッドの強度、作業性、所望とする貫通孔の孔径などの観点から、通常0.05〜0.5mmの範囲から選択される。ロッドの断面形状は、一般に円形であるが、それ以外に、星型、八角形、六角形、四角形、三角形など任意の形状であってもよい。超音波ヘッド101の先端部には、ロッド102を1本だけ取り付けるのではなく、多数本のロッドを取り付けて、多孔質膜に多数の開口部を一括加工により成形してもよい。
【0044】
ロッド102の押付け圧力は、ロッド1本当り通常1gf〜1kgf、好ましくは1〜100gfの範囲内である。超音波の周波数は、通常5〜500kHz、好ましくは10〜50kHzの範囲内である。超音波の出力は、ロッド1本当り通常1〜100W、好ましくは5〜50Wの範囲内である。
【0045】
ロッド102を多孔質膜103の表面に押し付けて超音波ヘッドを稼動させると、ロッドの先端が押し付けられた多孔質膜の付近のみに超音波エネルギーが加えられて、超音波による振動エネルギーによって局所的に温度が上昇し、その部分の樹脂成分が溶融、蒸発等により分解して、多孔質膜に貫通孔が形成される。
【0046】
一般に、多孔質PTFE膜は、機械加工により貫通孔を形成することが困難である。例えば、通常のパンチング法により多孔質PTFE膜に貫通孔を形成すると、バリが発生して、綺麗で正確な形状の貫通孔を形成することが困難である。これに対して、前述の超音波法により加工すると、多孔質PTFE膜に容易かつ安価に所望の形状の貫通孔を形成することができる。
【0047】
貫通孔の断面形状は、円形、星型、八角形、六角形、四角形、三角形など任意である。貫通孔の孔径は、小さな孔径が適した用途分野では、通常5〜100μm、好ましくは5〜30μm程度にすることができ、他方、比較的大きな孔径が適した分野では、通常100〜1000μm、好ましくは300〜800μm程度にすることができる。
【0048】
多孔質PTFE膜を基膜として使用し、かつ、超音波法により多孔質膜の特定位置の膜厚方向に貫通孔を形成する工程を含む異方性導電膜の製造方法は、好ましくは、(I)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層としてポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、(II)先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、積層体にパターン状の貫通孔を形成する工程、(III)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、(IV)両面のマスク層を剥離する工程、及び(V)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程を含む製造方法である。
【0049】
多孔質PTFE膜を基膜として使用し、かつ、超音波法により多孔質膜の特定位置の膜厚方向に貫通孔を形成する工程を含む異方性導電膜の他の好ましい製造方法としては、例えば、(i)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層として多孔質ポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、(ii)積層体の多孔質内に液体を染み込ませて、該液体を凍結させる工程、(iii)先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、積層体にパターン状の貫通孔を形成する工程、(iv)積層体を昇温して、多孔質内の凍結体を液体に戻して除去する工程、(V)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、(vi)両面のマスク層を剥離する工程、及び(vii)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程を含む製造方法が挙げられる。
【0050】
3層構成の積層体を用いる場合、図10に示す貫通孔の形成方法では、先端部に少なくとも1本のロッド102を取り付けた超音波ヘッド101を用いて、該ロッド102の先端を積層体(通常、3層構成の多孔質PTFE膜)103の表面に押付けて超音波エネルギーを加える。
【0051】
積層体の多孔質内に液体を染み込ませて、該液体を凍結させる工程を含む製造方法では、3層構成の多孔質PTFE膜からなる積層体の多孔質内部に水またはアルコール(例えば、メタノール、エタノール、イソプロパノールなどの低級アルコール)等の有機溶媒などの液体を染み込ませ、冷却して液体を凍結させる。染み込ませた液体が凍結状態にある間に、先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、加工性が改善され、パターン状の貫通孔を綺麗に形成することができる。冷却温度は、液体として水を使用する場合、零度以下、好ましくは−10℃以下にまで冷却して凍結させると、加工性が良好となる。アルコール等の有機溶媒の場合には、−50℃以下、望ましくは液体窒素温度まで冷却すると、加工性が良好となる。有機溶媒は、常温で液体であるものが好ましい。アルコール等の有機溶媒は、2種以上の混合物であってもよく、あるいは水を含有しているものでもよい。
【0052】
電気絶縁性の多孔質膜を導電化する方法としては、スパッタ法、イオンプレーティング法、無電解めっき法などが挙げられるが、多孔質構造の樹脂部に導電性金属を析出させて付着させるには、無電解めっき法が好ましい。無電解めっき法では、通常、めっきを析出させたい箇所に化学還元反応を促進する触媒を付与する必要がある。多孔質膜の特定の箇所の多孔質構造の樹脂部のみにめっきを行うには、当該箇所のみに触媒を付与する方法が有効である。
【0053】
例えば、膜厚方向に任意の形の微細な貫通孔が形成された多孔質PTFE膜の壁面(孔壁)のみを無電解銅めっきにて導電性を付与する場合、マスク層を形成した3層融着状態の積層体に貫通孔を形成し、そして、この積層体をパラジウム−スズコロイド触媒付与液に十分撹拌しながら浸漬する。触媒付与液に浸漬後、両表面のマスク層(B)及び(C)を剥離すると、貫通孔の壁面のみに触媒コロイド粒子が付着した多孔質PTFE膜(A)を得ることができる。該多孔質PTFE膜(A)をめっき液に浸漬することにより、貫通孔の壁面のみに銅を析出させることができ、それによって、筒状の導通部(電極)が形成される。銅以外に、ニッケル、銀、金、ニッケル合金などでも、同様の方法により導通部を形成することができるが、特に高導電性が必要な場合は、銅を使用することが好ましい。3層構成の積層体に貫通孔を形成する方法としては、シンクロトロン放射光もしくは250mm以下のレーザ光を照射する方法、及び超音波法が好ましい。
【0054】
めっき粒子(結晶粒)は、初め多孔質PTFE膜の貫通孔の壁面に露出した微細繊維(フィブリル)に絡むように析出するので、めっき時間をコントロールすることにより、導電性金属の付着状態をコントロールすることができる。無電解めっき時間が短すぎると、膜厚方向への導電性を得ることが困難になる。無電解めっき時間が長すぎると、導電性金属が多孔質状ではなく金属塊になり、通常の使用圧縮荷重では弾性回復が困難になる。適度なめっき量とすることにより、多孔質状の導電性金属層が形成され、弾性とともに膜厚方向への導電性も与えることが可能となる。
【0055】
上記のように作製された筒状の導通部(電極)は、酸化防止及び電気的接触性を高めるため、酸化防止剤を使用するか、貴金属もしくは貴金属の合金で被覆しておくことが好ましい。貴金属としては、電気抵抗の小さい点で、パラジウム、ロジウム、金が好ましい。貴金属等の被覆層の厚さは、0.005〜0.5μmが好ましく、0.01〜0.1μmがより好ましい。この被覆層の厚みが薄すぎると、電気的接触性の改善効果が小さく、厚すぎると、被覆層が剥離しやすくなるため、いずれも好ましくない。例えば、導通部を金で被覆する場合、8nm程度のニッケルで導電性金属層を被覆した後、置換金めっきを行う方法が効果的である。
【0056】
【実施例】
以下に実施例及び比較例を挙げて、本発明についてより具体的に説明するが、本発明は、これらの実施例のみに限定されるものではない。物性の測定法は、以下の通りである。
【0057】
(1)バブルポイント(BP):
延伸法による多孔質PTFE膜のバブルポイントは、イソプロピルアルコールを使用して、ASTM−F−316−76に従って測定した。
【0058】
(2)気孔率:
延伸法による多孔質PTFE膜の気孔率は、ASTM D−792に従って測定した。
【0059】
(3)導通開始荷重:
図5に示す導通確認装置を用いて、異方性導電膜の導通開始荷重を測定した。図5に示す導通確認装置において、異方性導電膜51を、金めっきを施した銅板(「Au板」と呼ぶ)52上に置く、その全体を重量計56上に載置する。プローブとして外径3mmφの銅柱53を使用し、荷重を加える。異方性導電膜の抵抗値を4針法により測定する。抵抗値が0.5Ω以下を示した荷重から押圧荷重圧を算出し、導通開始荷重圧とした。図5において、54は定電流電源を示し、55は電圧計を示す。
【0060】
(4)導通試験回数:
異方性導電膜を5mm角に切り取り、試料とした。セイコーインスツルメンツ(株)製TMA/SS120Cを使用し、常温、窒素ガス雰囲気下、3mmφの石英を押し込みプローブとして使用し、針入法により弾性回復性能を検証した。各異方性導電膜が導通するように、膜厚歪みが38%となる荷重で加重と未加重を10回繰り返し、その後の膜厚変化と導通開始荷重での再導通試験を行った。
【0061】
[実施例1]
面積10cm角で、気孔率60%、平均孔径0.1μm(BP=150kPa)、膜厚30μmの延伸法による多孔質PTFE膜3枚を重ね合わせて、厚さ3mm、縦150mm、横100mmのステンレス板2枚の間に挟み、ステンレス板の荷重とともに350℃で30分間加熱処理した。加熱後、ステンレス板の上から水にて急冷し、3層に融着された多孔質PTFE膜の積層体を得た。
【0062】
次いで、開口率9%、開口径15μmφ、ピッチ80μmで均等配列に開口したタングステンシートを積層体の片面に重ねて、シンクロトロン放射光を照射して、膜厚さ方向へ孔径15μmφ、80μmピッチで均等に配置された貫通孔を形成した。
【0063】
15μmφの貫通孔を形成した積層体をエタノールに1分間浸漬して親水化した後、100ml/Lに希釈したメルテックス(株)製メルプレートPC−321に、60℃の温度で4分間浸漬し脱脂処理を行った。さらに、積層体を10%硫酸に1分間浸漬した後、プレディップとして、0.8%塩酸にメルテックス(株)製エンプレートPC−236を180g/Lの割合で溶解した液に2分間浸漬した。
【0064】
さらに、積層体を、メルテックス(株)製エンプレートアクチベータ444を3%、エンプレートアクチベータアディティブを1%、塩酸を3%溶解した水溶液にメルテックス(株)製エンプレートPC−236を150g/Lの割含で溶解した液に5分間浸漬して、触媒粒子を積層体の表面及び貫通孔の壁面に付着させた。次に、積層体をメルテックス(株)製エンプレートPA−360の5%溶液に5分間浸漬し、パラジウム触媒核の活性化を行った。その後、第1層と第3膚のマスク層を剥離して、貫通孔の壁面のみに触媒パラジウム粒子が付着した多孔質PTFE膜(基膜)を得た。
【0065】
メルテックス(株)製メルプレートCu−3000A、メルプレートCu−3000B、メルプレートCu−3000C、メルプレートCu−3000Dをそれぞれ5%、メルプレートCu−3000スタビライザーを0.1%で建浴した無電解銅めっき液に、十分エアー撹拌を行いながら、上記基膜を20分間浸漬して、15μmφの貫通孔の壁面のみを銅粒子にて導電化した(電極の外径=25μm)。さらに、5ml/Lで建浴したメルテックス(株)製エンテックCu−56に30秒間浸漬して、防錆処理して、多孔質PTFE膜を基膜とする異方性導電膜を得た。
【0066】
めっき工程において、無電解鋼めっきのプレディップ工程と触媒付与工程の間以外の各液浸漬後は、蒸留水にて30秒間から1分間程度水洗を行った。各液の温度は、脱脂処理を除いて全て常温(20〜30℃)で行った。
【0067】
上記のようにして得られた多孔質PTFE膜を基膜とする異方性導電膜を10mm角に切り取り、図5に示す装置にて導通開始荷重を測定した。プローブは、3mmφの銅柱を使用し、抵抗値を4針法にて測定した。低抗値が0.5Ω以下となった荷重から押圧荷重を算出し、導通開始荷重圧とすることとした。その結果、導通開始荷重圧は6kPaであった。
【0068】
また、異方性導電膜を5mm角に切り取り、セイコーインスツルメンツ(株)製TMA/SS120Cを使用し、常温、窒素ガス雰囲気下、石英3mmφを押し込みプローブとして使用し、針入法により弾性回復性能を検証した。合計10回の加重と未加重を繰り返し、その各回で膜厚変位と膜厚方向導通試験を行った。抵抗値は、上記同様0.5Ω以下を示せば導通ありとした。その結果、導通開始荷重圧は、6kPaであった。十分な導通が得られ、かつ、膜厚歪みが38%となる荷重圧の27.7kPaで10回の加重と未加重を繰り返した後も、未加重時は試験前の膜厚を実質的に維持し、導通開始荷重圧の6kPaでも導通が確認できた。
【0069】
[実施例2]
実施例1と同様の方法、同様の条件にて、多孔質PTFE膜3枚を融着して積層体を形成した。この積層体に10μmφの貫通孔を形成し、次いで、めっき前処理を行った。マスク層の剥離後、無電解銅めっき液に十分エアー撹拌を行いながら基膜を20分間浸漬し、10μmφの貫通孔の壁面のみに銅粒子を付着させて導電化し(電極の外径=17μm)、さらに実施例1と同様の防錆処理を施して、延伸法による多孔質PTFE膜を基膜とする異方性導電膜を得た。得られた異方性導電膜を用いて、実施例1と同様の試験を行ったところ、導通開始荷重圧は、6kPaであった。十分な導通が得られ、かつ、膜厚歪みが38%となる荷重圧の27.7kPaで10回の加重と未加重を繰り返した後も、未加重時は試験前の膜厚を実質的に維持し、導通開始荷重圧の6kPaでも導通が確認できた。
【0070】
[比較例1]
面積10cm角で、気孔率60%、平均孔径0.1μm(BP=150kPa)、膜厚30μmの延伸法による多孔質PTFE膜3枚を積層し、厚さ3mm、縦150mm、横100mmのステンレス板2枚の間に挟み、ステンレス板の荷重とともに350℃で30分間加熱処理した。加熱後、ステンレス板の上から水にて急冷し、3枚が融着し積層体を得た。
【0071】
次いで、開口率9%、開口径25μmφ、ピッチ60μmで均等配列に開口したタングステンシートを積層体の片面に重ねて、シンクロトロン放射光を照射して、膜厚方向へ孔径25μmφ、60μmピッチで均等に配置された貫通孔を形成した。
【0072】
25μmφの孔を形成した積層体をエタノールに1分間浸漬し親水化した後、100ml/Lに希釈したメルテックス(株)製メルプレートPC−321に、水温60℃で4分間浸漬し、脱脂処理を行った。さらに、積層体を10%硫酸に1分間浸漬した後、プレディップとして0.8%塩酸にメルテックス(株)製エンプレートPC−236を180g/Lの割合で溶解した液に2分間浸漬した。
【0073】
次に、メルテックス(株)製エンプレートアクチベータ444を3%、エンプレートアクチベータアディティブを1%、塩酸を3%溶解した水溶液にメルテックス(株)製エンプレートPC−236を150g/Lの割合で溶解した液に、積層体を5分間浸漬して、触媒粒子を積層体の表面及び貫通孔の壁面に付着させた。さらに、積層体をメルテックス(株)製エンプレートPA−360の5%溶液に2分間浸漬し、パラジウム触媒核の活性化を行った。
【0074】
メルテックス(株)製メルプレートCu−3000A、メルプレートCu−3000B、メルプレートCu−3000C、メルプレートCu−3000Dをそれぞれ5%、メルプレートCu−3000スタビライザーを0.1%で建浴した無電解銅めっき液に十分エアー撹拌を行いながら上記積層体を5分間浸漬し、表面及び貫通孔の壁面を銅粒子にて導電化した。
【0075】
次いで、電気銅めっき液として、メルテックス(株)製カッパークリームCLXを使用し、電流密度2A/dmにて30分間、電気銅めっきにて貫通孔を銅で充填した。マスク表面への過剰めっきを10%硫酸溶液に目視でマスク層の表面が見えるまで浸漬しエッチングしてから手で裂くようにマスク層を剥離し、膜厚方向に導通する外径25μmφの電極によって膜厚方向へのみ導電性を有し、かつ、膜表面に7μmの突起電極をもった異方性導電膜を得た。
【0076】
この異方性導電膜を5ml/Lで建浴したメルテックス(株)製エンテックCu−56に30秒間浸漬して防錆処理し、延伸法による多孔質PTFE膜を基膜とし、各貫通孔に導電性金属が充填された異方性導電膜を得た。
【0077】
めっき工程において、無電解銅めっきのプレディップ工程と触媒付与工程の間以外の各液浸漬後は、蒸留水にて30秒間から1分間程度水洗を行った。各液の温度は、脱脂処理を除いて全て常温(20〜30℃)で行った。
【0078】
このようにして、図8に示すように、多孔質PTFE膜83を基膜とし、各貫通孔に導電性金属が充填され、かつ、両面に突起がある導通部(電極)82を有する異方性導電膜81を得た。この異方性導電膜を用いて、実施例1と同様の試験を行ったところ、導通開始荷重圧は3kPaであった。十分な導通が得られ、かつ、膜厚歪みが38%となる荷重圧の37.0kPaで10回の加重と未加重を繰り返した後は、膜厚が6.1μm減少し、導通開始荷重圧の3kPaでは導通が得られなかった。
【0079】
[比較例2]
所定量の架橋剤を添加したシリコーンゴム〔信越ポリマー(株)製、付加型RTVゴム KE1206〕にニッケル粒子〔日本アトマイズ加工(株)製、平均粒径10μm〕が80vol%となるように室温で配合し混合した。このコンパウンドをガラス板上にギャップ25μmのドクターナイフでキャスティング後、80℃の恒温槽内で1時間硬化させ、厚さ約22μmの金属粒子がシリコーンエラストマー中に分散した異方性導電膜を得た。
【0080】
このようにして、図9に示すように、シリコーンゴムからなる基膜92の中に導電性粒子93が分散した構造の異方性導電膜91を得た。この異方性導電膜を用いて、実施例1と同様の試験を行ったところ、導通開始荷重圧は25kPaであった。十分な導通が得られ、かつ、膜厚歪みが38%となる荷重圧の28.0kPaで10回の加重と未加重を繰り返した後は、膜厚が0.7μm減少し、導通開始荷重圧の25kPaでは導通が得られなかった。
【0081】
【表1】

Figure 2004265844
【0082】
(脚注)比較例1の膜厚は、導通部の突起高さを含む。
【0083】
【発明の効果】
本発明によれば、膜厚方向に弾力性があり、低圧縮荷重で膜厚方向の導通が可能で、さらには、弾性回復が可能で、頻回の使用に適している異方性導電膜が提供される。また、本発明によれば、各導通部の大きさやピッチなどをファイン化することができる異方性導電膜が提供される。本発明の異方性導電膜は、主に半導体ウェハなどの検査用異方性導電膜として、低圧縮荷重で膜厚方向の電気的導通が得られ、かつ、繰り返し荷重負荷でも、弾性により膜厚が復帰し、検査に繰り返し使用が可能である。
【図面の簡単な説明】
【図1】図1は、貫通孔が形成された多孔質膜の斜視図である。
【図2】図2は、本発明の異方性導電膜において、各貫通孔の壁面で多孔質構造の樹脂部に導電性金属粒子が付着して導通部を形成している状態を示す断面図である。
【図3】図3は、貫通孔の直径aと導通部(電極)の外径bとの関係を示す説明図である。
【図4】図4は、基膜を中心層とする積層体の製造工程を示す断面図である。
【図5】図5は、異方性導電膜の導通確認装置の断面略図である。
【図6】図6は、従来の異方性導電膜の一例を示す断面図である。
【図7】図7は、従来の異方性導電膜の他の一例を示す断面図である。
【図8】比較例1で作製した異方性導電シートの断面図である。
【図9】比較例2で作製した異方性導電シートの断面図である。
【図10】超音波法により、多孔質膜に貫通孔を形成する方法を示す説明図である。
【符号の説明】
1:多孔質膜(基膜)、2:第一表面、3:第二表面、
4:貫通孔、5:導電性金属が付着した導通部、6:多孔質膜、
41,42:SUS板、43:基膜、44,45:マスク層、
51:異方性導電膜、52:Au板、53:銅柱、
54:定電流電源、55:電圧計、56:重量計、
61:異方性導電膜、62:導電性金属の塊(導通部)、63:多孔質膜、
71:異方性導電膜、72:導電路形成部、
73:カプセル型導電性粒子、74:熱硬化性樹脂からなる絶縁部、
81:異方性導電膜、82:導電性金属の塊(導通部)、83:多孔質膜、
91:異方性導電膜、92:シリコーンゴム、93:導電粒子、
101:超音波ヘッド、102:ロッド、103:多孔質膜、104:板状体。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an anisotropic conductive film and a method of manufacturing the same, and more particularly, to an anisotropic conductive film and a method of manufacturing the same that can be suitably used for a burn-in test of a semiconductor device.
[0002]
[Prior art]
A burn-in test is performed as one of screening methods for removing an initial failure of a semiconductor device. In the burn-in test, an accelerated stress at a higher temperature and a higher pressure than the operating conditions of the semiconductor device is applied to accelerate the occurrence of a failure and remove defective products in a short time. For example, a large number of packaged semiconductor devices are arranged on a burn-in board, and a power supply voltage and an input signal that are subjected to accelerated stress are applied from outside in a high-temperature bath for a certain period of time. After that, the semiconductor device is taken out and a test for judging a good product and a defective product is performed. In the determination test, an increase in leakage current due to a defect in a semiconductor device, a defective product due to a defect in a multilayer wiring, a defect in a contact, and the like are determined. The burn-in test is also performed on a semiconductor wafer.
[0003]
For example, when performing a burn-in test on a semiconductor wafer, the test is performed via an electrode pad made of aluminum or the like on the surface of the semiconductor wafer. At that time, in order to compensate for poor contact due to variations in electrode height between the electrode pad of the semiconductor wafer and the head electrode of the measuring device, a contact sheet having conductivity only in the film thickness direction is usually provided between these electrodes. The test is carried out by sandwiching. This contact sheet has an anisotropic conductive film due to the property of exhibiting conductivity only in the film thickness direction in a conductive portion (also referred to as “conductive path” or “electrode portion”) arranged according to a pattern corresponding to the surface electrode. (Also called “anisotropic conductive sheet”).
[0004]
Conventionally, in the field of electronics technology, for the purpose of connecting a packaged integrated circuit to a printed wiring board or the like, as shown in FIG. 6, a flat porous flexible material 63 is used as a non-conductive insulating portion, An anisotropic conductive member 61 having a conductive portion 62 formed by filling a conductive metal in a section defined in one vertical direction (Z-axis direction) and filling it with an adhesive such as an epoxy resin is fixed. It is known (for example, refer to Patent Document 1). However, when the anisotropic conductive member 61 is used as an anisotropic conductive film for a burn-in test, the conductive portion 62 buckles due to pressing during the test and does not recover elasticity, and therefore must be disposable for each test. Absent. Therefore, the cost of the inspection becomes too high. Therefore, the anisotropic conductive member 61 is not suitable for an anisotropic conductive film for a burn-in test that needs to be used frequently.
[0005]
As shown in FIG. 7, a plurality of through holes are provided in the film thickness direction of the sealing insulating sheet 74 formed of a thermosetting resin such as an epoxy resin material. A semiconductor element mounting sheet 71 having a structure in which a conductive path 72 is formed by filling a conductive path forming material in which conductive particles 73 are dispersed has been proposed (for example, see Patent Document 2). As the conductive particles, for example, metal or alloy particles, or capsule-type conductive particles having a structure in which the surfaces of polymer particles are plated with a conductive metal are used.
[0006]
When the semiconductor element mounting sheet 71 is pressed in the thickness direction, the elastomer of the conductive path 72 is compressed and the conductive particles 73 are connected, so that electrical conduction is obtained only in the thickness direction of the conductive path. However, when the semiconductor element mounting sheet 71 is used as an anisotropic conductive film for a burn-in test, a high compressive load is required to obtain conduction in the film thickness direction, and the elasticity decreases due to deterioration of the elastomer. , Cannot be used frequently. Therefore, a semiconductor element mounting sheet having such a structure is not suitable as an anisotropic conductive film for a burn-in test such as a semiconductor wafer.
[0007]
On the other hand, for an anisotropic conductive film used as a burn-in test interposer for a semiconductor wafer or the like, a surface electrode of the semiconductor wafer is connected to a head electrode of a measuring device, and wiring from the semiconductor wafer is connected to a semiconductor package. In addition to connecting to terminals, the effect of stress relaxation is also required. Therefore, the anisotropic conductive film has elasticity in the film thickness direction, is capable of conducting in the film thickness direction with a low compressive load, and is capable of elastic recovery, and is suitable for frequent use. Is required. Further, along with high-density mounting and the like, finer patterns such as the size and pitch of each conductive portion of an anisotropic conductive film used for inspection are required. However, the prior art has not been able to develop an anisotropic conductive film that can sufficiently meet these requirements.
[0008]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 10-503320 (pages 1-3, FIG. 4)
[Patent Document 2]
Japanese Patent Application Laid-Open No. 10-12773 (Page 1-2, FIG. 1)
[0009]
[Problems to be solved by the invention]
An object of the present invention is an anisotropic conductive film mainly used for inspection of semiconductor wafers and the like, which has elasticity in a film thickness direction, can conduct electricity in a film thickness direction with a low compressive load, and further has an elasticity. An object of the present invention is to provide an anisotropic conductive film which can be recovered and is suitable for frequent use. Another object of the present invention is to provide an anisotropic conductive film that can make the size and pitch of each conductive portion finer.
[0010]
The present inventors have conducted intensive research to achieve the above-mentioned object, and have found that an electrically insulating porous film formed of a synthetic resin has an appropriate elasticity and is capable of recovering elasticity. We paid attention to its suitability as a base film for conductive films. However, in a method in which a conductive metal is filled in a porous structure in a specific portion of a porous film to form a conductive portion formed of a conductive metal lump, the conductive metal lump does not buckle and elastically recover during a compressive load. Therefore, it cannot be used repeatedly.
[0011]
Therefore, as a result of further research, if a conductive part is formed by attaching a conductive metal to the resin part of the porous structure in a state penetrating in the film thickness direction at a plurality of locations of the porous film, a conductive part is formed. Was found to be able to maintain the porous structure. Of course, in the conductive portion, since the conductive metal adheres to the resin portion of the porous structure, the porous structure inherent in the porous film cannot be completely retained, but to a certain extent, The porous structure can be maintained in the range. That is, the conductive portion of the anisotropic conductive film of the present invention has a porous shape.
[0012]
Therefore, in the anisotropic conductive film of the present invention, not only the base film but also the conductive portion has elasticity and elastic recovery, and can be used frequently. Further, the anisotropic conductive film of the present invention can conduct in the thickness direction with a low compression load. Furthermore, the anisotropic conductive film of the present invention can also make fine the pitch between conductive portions and between conductive portions. The present invention has been completed based on these findings.
[0013]
[Means for Solving the Problems]
According to the present invention, an electrically insulating porous film formed of a synthetic resin is used as a base film, and a resin portion having a porous structure is formed at a plurality of locations of the base film so as to penetrate from the first surface to the second surface. An anisotropic conductive film is provided in which conductive portions formed of a conductive metal adhered to a conductive layer and capable of imparting conductivity in a film thickness direction are independently provided.
[0014]
Further, according to the present invention, a plurality of portions of a base film made of an electrically insulating porous film formed of a synthetic resin are electrically connected to a resin portion having a porous structure while penetrating from a first surface to a second surface. A method for producing an anisotropic conductive film is provided, wherein conductive portions capable of imparting conductivity in the film thickness direction are provided independently by attaching a conductive metal.
[0015]
Further, according to the present invention, there are provided the following methods 1 to 3 for producing an anisotropic conductive film.
[0016]
1. (1) Polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of a base film made of a porous polytetrafluoroethylene film (A) to form a three-layer laminate. Process,
(2) By irradiating synchrotron radiation light or laser light having a wavelength of 250 nm or less from the surface of one of the mask layers via a light shielding sheet having a plurality of independent light transmission portions in a predetermined pattern, Forming a patterned through-hole in the laminate,
(3) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes;
(4) removing the mask layers on both sides, and
(5) A step of attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through hole by electroless plating
By each of the steps, a conductive metal is attached to the resin portion of the porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations of the base film made of the porous polytetrafluoroethylene film, A method for producing an anisotropic conductive film, wherein conductive portions capable of imparting conductivity in directions are independently provided.
[0017]
2. (I) Polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of a base film made of a porous polytetrafluoroethylene film (A) to form a three-layer laminate. Process,
(II) Using a ultrasonic head having at least one rod at the tip, pressing the tip of the rod against the surface of the laminate and applying ultrasonic energy to form a patterned through hole in the laminate. The process of
(III) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes;
(IV) a step of removing the mask layers on both sides, and
(V) A step of attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through hole by electroless plating
By each of the steps, a conductive metal is attached to the resin portion of the porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations of the base film made of the porous polytetrafluoroethylene film, A method for producing an anisotropic conductive film, wherein conductive portions capable of imparting conductivity in directions are independently provided.
[0018]
3. (I) Porous polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of a base film composed of a porous polytetrafluoroethylene film (A) to form a three-layer laminate. Forming,
(Ii) impregnating a liquid into the porous body of the laminate and freezing the liquid;
(Iii) Using an ultrasonic head having at least one rod at the tip, pressing the tip of the rod against the surface of the laminate and applying ultrasonic energy to form a patterned through hole in the laminate. Process,
(Iv) a step of raising the temperature of the laminate and returning the frozen body in the porous body to a liquid to remove the frozen body;
(V) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes;
(Vi) a step of peeling off the mask layers on both sides, and
(Vii) A step of attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through hole by electroless plating
By each of the steps, a conductive metal is attached to the resin portion of the porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations of the base film made of the porous polytetrafluoroethylene film, A method for producing an anisotropic conductive film, wherein conductive portions capable of imparting conductivity in directions are independently provided.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
1. Porous membrane (base membrane) ;
An anisotropic conductive film for a burn-in test such as a semiconductor wafer preferably has excellent heat resistance of the base film. The anisotropic conductive film needs to be electrically insulating in the lateral direction (perpendicular to the film thickness direction). Therefore, the synthetic resin forming the porous film needs to be electrically insulating.
[0020]
Polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and tetrafluoroethylene / perfluoroalkylvinyl ether copolymer are used as synthetic resin materials for forming a porous film used as a base film. (PFA), fluororesins such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride copolymer, ethylene / tetrafluoroethylene copolymer (ETFE resin); polyimide (PI), polyamideimide (PAI), polyamide ( PA), modified polyphenylene ether (mPPE), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polysulfone (PSU), polyether sulfone (PES), liquid crystal polymer (LCP), etc. Plastic; and the like. Among these, PTFE is preferred from the viewpoint of heat resistance, workability, mechanical properties, dielectric properties, and the like.
[0021]
Examples of a method for producing a porous membrane made of a synthetic resin include a pore forming method, a phase separation method, a solvent extraction method, a stretching method, and a laser irradiation method. By forming a porous film using a synthetic resin, elasticity can be provided in the film thickness direction, and the dielectric constant can be further reduced.
[0022]
The porosity of the porous film used as the base film of the anisotropic conductive film is preferably about 20 to 80%. The porous membrane preferably has an average pore diameter of 10 μm or less or a bubble point of 2 kPa or more, and more preferably has an average pore diameter of 1 μm or less or a bubble point of 10 kPa or more from the viewpoint of fine pitching of the conductive portion. . The thickness of the porous film can be appropriately selected according to the purpose of use and the place of use, but is usually 3 mm or less, preferably 1 mm or less. Particularly, in the case of an anisotropic conductive film for a burn-in test, the thickness of the porous film is often preferably 5 to 500 μm, more preferably 10 to 200 μm, and particularly preferably about 15 to 100 μm.
[0023]
Among porous films, a porous polytetrafluoroethylene film (hereinafter abbreviated as “porous PTFE film”) obtained by a stretching method is excellent in heat resistance, workability, mechanical properties, dielectric properties, and the like, and Since it is easy to obtain a porous film having a uniform pore size distribution, it is the most excellent material as a base film of an anisotropic conductive film.
[0024]
The porous PTFE membrane used in the present invention can be produced, for example, by the method described in JP-B-42-13560. First, a liquid lubricant is mixed with the unsintered PTFE powder, and the mixture is extruded into a tube or a plate by ram extrusion. When a sheet having a small thickness is desired, the plate is rolled by a rolling roll. After the extrusion rolling step, the liquid lubricant is removed from the extruded or rolled product as necessary. When the thus obtained extruded product or rolled product is stretched in at least one direction, unsintered porous PTFE is obtained in the form of a film. The unsintered porous PTFE film is heated to a temperature of 327 ° C. or more, which is the melting point of PTFE, while fixing so that it does not shrink, and the stretched structure is sintered and fixed to obtain a high-strength porous material. A PTFE film is obtained. When the porous PTFE membrane has a tubular shape, a flat membrane can be formed by cutting and opening the tube.
[0025]
The porous PTFE membrane obtained by the drawing method has a fine fibrous structure composed of very fine fibers (fibrils) formed by PTFE and nodes (nodes) connected to each other by the fibers. In the porous PTFE membrane, this fine fibrous structure forms a porous structure.
[0026]
2. Formation of conductive part (electrode part) :
According to the present invention, a conductive metal is attached to a resin portion of a porous structure in a state of penetrating from a first surface to a second surface at a plurality of positions of a base film made of an electrically insulating porous film formed of a synthetic resin. In this way, conductive portions capable of providing conductivity in the film thickness direction are provided independently.
[0027]
In order to form conductive portions at a plurality of locations on the base film, first, it is necessary to specify a position where the conductive metal is to be attached. As a method of specifying the position where the conductive metal is to be attached, for example, a method in which a porous film is impregnated with a liquid resist, exposed in a pattern, developed, and the resist removal portion is set as the conductive metal attachment position There is. In the present invention, it is possible to suitably employ a method in which a fine through-hole is formed at a specific position of the porous film in the thickness direction, and the wall surface of the through-hole is set as a conductive metal attachment position. The method of the present invention in which a large number of through holes are formed in a porous film is more suitable for depositing a conductive metal at a fine pitch than the former method using a photolithography technique. Further, the method of forming a large number of through holes in the porous film is suitable for forming a conductive portion having a fine diameter of, for example, 30 μm or less, and more preferably 25 μm or less.
[0028]
In the present invention, a conductive metal is attached to a resin part of a porous structure in a state of penetrating from a first surface to a second surface at a plurality of positions of a base film made of a porous film to form a conductive part. In a method using a photolithography technique, conductive metal particles are deposited on a resist removal portion by an electroless plating method or the like, and a conductive metal is continuously attached to a resin portion having a porous structure. In this case, the conductive metal is continuously attached to the resin portion having the porous structure so as to penetrate from the first surface to the second surface of the resist removing portion. In a method peculiar to the present invention for forming a through-hole, the conductive metal particles are attached to a resin portion of a porous structure exposed on the wall surface of the through-hole by a method such as electroless plating.
[0029]
The resin part having a porous structure means a skeleton part forming a porous structure of a porous film. The shape of the resin portion of the porous structure differs depending on the type of the porous film and the method of forming the porous film. For example, in the case of a porous PTFE membrane formed by a stretching method, the porous structure is formed of a large number of fibrils each composed of PTFE and a large number of nodes connected to each other by the fibrils. , These fibrils and nodes.
[0030]
A conductive portion is formed by attaching a conductive metal to the resin portion having a porous structure. At this time, the porous structure in the conduction portion can be maintained by appropriately controlling the amount of the conductive metal attached. In the anisotropic conductive film of the present invention, since the conductive metal adheres along the surface of the resin portion of the porous structure, the conductive metal layer is integrated with the porous structure to form a porous structure. As a result, it can be said that the conductive portion is porous.
[0031]
When the electroless plating method or the like is adopted, the conductive metal particles adhere to the resin portion having the porous structure. In the anisotropic conductive film of the present invention, a state in which the conductive metal particles adhere is obtained while maintaining the porous structure (porosity) of the porous film to some extent. The thickness of the resin portion of the porous structure (eg, the thickness of fibrils) is preferably 50 μm or less. The particle diameter of the conductive metal particles is preferably about 0.001 to 5 μm. The amount of the conductive metal particles attached is preferably about 0.01 to 4.0 g / ml in order to maintain porosity and elasticity. Depending on the porosity of the porous film as the base film, if the amount of the conductive metal particles attached is too large, the elasticity of the anisotropic conductive film becomes too large. The elastic recovery performance of the conductive film is significantly reduced. If the amount of the conductive metal particles attached is too small, it is difficult to obtain conduction in the film thickness direction even when a compressive load is applied.
[0032]
A method for attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through hole will be described with reference to the drawings. FIG. 1 is a perspective view of a porous film in which a through hole is formed. In the porous film (base film) 1, through holes 4 penetrating from the first surface 2 to the second surface 3 are formed at a plurality of locations. These through holes are generally formed in a porous film in a predetermined pattern. FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1 and shows a state in which conductive metal particles adhere to a resin portion of a porous structure on the wall surface of the through hole to form a conductive portion. ing. In FIG. 2, the porous film 6 is a base film, the through-holes 4 are provided at a plurality of predetermined locations, and conductive metal particles adhere to the resin portion of the porous structure on the through-hole wall surface. As a result, a conductive portion 5 is formed. Since the conductive portion is formed by adhering to the surface of the resin portion having a porous structure, the conductive portion has a characteristic of being porous. Conductivity is provided only in the direction. When the pressure is removed, the entire anisotropic conductive film including the conductive portion recovers elastically, so that the anisotropic conductive film of the present invention can be used repeatedly.
[0033]
FIG. 3 is an enlarged cross-sectional view of one conductive portion of FIG. 2, wherein a represents the diameter of a through hole, and b represents the diameter of a conductive portion (electrode) formed by attaching conductive metal particles ( Outside diameter). Since the conductive metal particles adhere to the wall surface of the through hole while slightly penetrating into the porous structure, the diameter b of the conductive portion is larger than the diameter a of the through hole.
[0034]
In the anisotropic conductive film of the present invention, when no compressive load is applied, the resistance of the conductive portion is large, and when a predetermined compressive load is applied, the resistance of the conductive portion may be 0.5Ω or less. desirable. The measurement of the resistance value of the conduction portion is performed using the conduction confirmation device shown in FIG. 5, and details thereof will be described in Examples.
[0035]
As shown in FIG. 1, it is difficult to attach a conductive metal only to the wall surface of a through-hole by electroless plating or the like simply by providing through-holes at a plurality of locations of the porous film. For example, when a porous PTFE film is used as the porous film, the electroless plating causes conductive metal particles to precipitate not only on the wall surface of the through hole but also on the resin portion of the entire porous structure. Therefore, the present invention proposes, for example, a method of attaching a conductive metal only to the wall surface of a through hole using a mask layer. Specifically, a mask layer is formed on both surfaces of the base film so that catalyst particles that promote a chemical reduction reaction in electroless plating do not adhere to the surface of the base film in order to deposit a conductive metal only on the wall surfaces of the through holes. Form.
[0036]
For example, when a porous PTFE film formed by a stretching method is used as the base film, the material used as the mask layer has good adhesion to the base film, through holes can be formed simultaneously with the base film, and It is preferable to use a PTFE film made of the same material as the base film because the film can be easily separated from the base film after completing the role. In addition, the mask layer must be a porous PTFE film because the etching rate for forming the through-hole can be increased and the separation from the base film after the role as the mask layer can be further facilitated. Is more preferred. The porous PTFE film of the mask layer preferably has a porosity of about 20 to 80% from the viewpoint of easy peeling, and the film thickness is preferably 3 mm or less, more preferably 1 mm or less. , 100 μm or less. Further, the average pore diameter is preferably 10 μm or less (or the bubble point is 2 kPa or more) from the viewpoint of the water resistance of the mask layer.
[0037]
FIG. 4 shows a case where the porous PTFE film (A) obtained by the stretching method is used as a base film, and a PTFE film of the same material, preferably, the porous PTFE films (B) and (C) are used as a mask layer. This will be described with reference to FIG. As shown in FIG. 4, a three-layer laminate is formed by fusing porous PTFE films (B) 44 and (C) 45 as mask layers on both surfaces of a base film made of a porous PTFE film (A) 43. To form More specifically, these porous PTFE films are overlapped in three layers as shown in FIG. 4, and both surfaces thereof are sandwiched between two stainless steel plates 41 and 42. Each stainless plate has a parallel surface. By heating each stainless plate at a temperature of 320 to 380 ° C. for 30 minutes or more, three porous PTFE membranes are fused to each other. In order to increase the mechanical strength of the porous PTFE membrane, it is preferable to rapidly cool the porous PTFE membrane with cooling water after the heat treatment. Thus, a laminate having a three-layer structure is formed.
[0038]
Examples of a method for forming a through-hole in a film thickness direction at a specific position of the porous film include a chemical etching method, a thermal decomposition method, an ablation method using laser light or soft X-ray irradiation, and an ultrasonic method. When using a porous PTFE film by a stretching method as the base film, a method of irradiating synchrotron radiation light or laser light having a wavelength of 250 nm or less, and an ultrasonic method are preferable.
[0039]
Preferably, the method for producing an anisotropic conductive film using a porous PTFE film as a base film and including a step of forming through holes by irradiation with synchrotron radiation or laser light having a wavelength of 250 nm or less is preferably (1) A) a step of fusing the polytetrafluoroethylene films (B) and (C) as mask layers on both surfaces of the base film made of the porous polytetrafluoroethylene film (A) to form a three-layer laminate; (2) By irradiating synchrotron radiation light or laser light having a wavelength of 250 nm or less from the surface of one of the mask layers via a light shielding sheet having a plurality of independent light transmitting portions in a predetermined pattern, A step of forming a patterned through-hole in the laminate, (3) a step of adhering catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surface of the through-hole, and (4) both steps. A step of peeling the mask layer, and (5) a production method comprising a step of adhering a conductive metal to the resin portion of the porous structure in the wall surface of the through-hole by electroless plating.
[0040]
As the light shielding sheet, for example, a tungsten sheet is preferable. A plurality of pattern-shaped openings are formed in a tungsten sheet, and the openings are used as light-transmitting portions (hereinafter sometimes simply referred to as “openings”). A portion where light is transmitted through a plurality of openings of the light shielding sheet and irradiated is etched to form a through hole.
[0041]
The pattern of the opening of the light-blocking sheet may be any shape such as a circle, a star, an octagon, a hexagon, a quadrangle, and a triangle. The pore diameter of the opening may be 0.1 μm or more on one side or diameter and larger than the average pore diameter of the porous PTFE membrane used. Since the hole diameter of the through hole determines the size of the conductive portion (electrode) of the anisotropic conductive film to be manufactured, it may be appropriately formed according to the size of the conductive portion to be manufactured. For example, when used as an interposer for a burn-in test of a semiconductor wafer, the thickness is preferably 5 to 100 μm, more preferably 5 to 30 μm. The pitch between the conductive portions (electrodes) is preferably 5 to 100 μm.
[0042]
In order to form a through hole in a film thickness direction at a specific position of a porous film by an ultrasonic method, as shown in FIG. 10, an ultrasonic head 101 having at least one rod 102 attached to a distal end portion is used. Then, the tip of the rod 102 is pressed against the surface of the porous film 103 to apply ultrasonic energy. In the step of forming the through-hole, the porous film 103 is placed on a plate-like body 104 formed of a hard material such as silicon, ceramics, and glass. Instead of using a plate-like body, the rods may be opposed to each other above and below the porous membrane.
[0043]
As the rod, a rod-shaped body formed of an inorganic material such as metal, ceramics, and glass is preferable. The diameter of the rod is not particularly limited, but is usually selected from the range of 0.05 to 0.5 mm from the viewpoint of the strength of the rod, workability, a desired diameter of the through hole, and the like. The cross-sectional shape of the rod is generally circular, but may be any other shape such as a star, an octagon, a hexagon, a quadrangle, and a triangle. Instead of attaching only one rod 102 to the tip of the ultrasonic head 101, a large number of rods may be attached and a large number of openings may be formed in the porous film by batch processing.
[0044]
The pressing pressure of the rod 102 is usually in the range of 1 gf to 1 kgf, preferably 1 to 100 gf per rod. The frequency of the ultrasonic wave is usually in the range of 5 to 500 kHz, preferably 10 to 50 kHz. The output of the ultrasonic wave is usually in the range of 1 to 100 W, preferably 5 to 50 W per rod.
[0045]
When the ultrasonic head is operated by pressing the rod 102 against the surface of the porous film 103, ultrasonic energy is applied only to the vicinity of the porous film against which the tip of the rod is pressed, and the local energy is generated by the vibration energy by the ultrasonic wave. Then, the temperature rises, and the resin component in that portion is decomposed by melting, evaporation, or the like, and a through-hole is formed in the porous film.
[0046]
Generally, it is difficult for a porous PTFE membrane to form a through hole by machining. For example, when a through hole is formed in a porous PTFE film by a normal punching method, burrs are generated, and it is difficult to form a clean and accurate through hole. On the other hand, when processing is performed by the above-described ultrasonic method, a through hole having a desired shape can be formed easily and inexpensively in the porous PTFE film.
[0047]
The cross-sectional shape of the through-hole is arbitrary such as a circle, a star, an octagon, a hexagon, a quadrangle, and a triangle. The pore size of the through-holes can be usually about 5 to 100 μm, preferably about 5 to 30 μm in the application field where a small pore diameter is suitable, while it is usually 100 to 1000 μm, preferably in the field where a relatively large pore diameter is suitable. Can be about 300 to 800 μm.
[0048]
Preferably, the method for producing an anisotropic conductive film using a porous PTFE film as a base film and including a step of forming a through hole in a film thickness direction at a specific position of the porous film by an ultrasonic method is preferably ( I) Step of fusing polytetrafluoroethylene films (B) and (C) as mask layers on both surfaces of a base film made of porous polytetrafluoroethylene film (A) to form a three-layer laminate (II) Using an ultrasonic head having at least one rod at the distal end thereof, pressing the distal end of the rod against the surface of the laminated body and applying ultrasonic energy to form a patterned through hole in the laminated body. Forming; (III) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes; (IV) removing the mask layers on both surfaces; and (V) electroless. Penetration by plating In the wall surface in the resin portion of the porous structure is a manufacturing method including the step of depositing a conductive metal.
[0049]
Another preferred method for producing an anisotropic conductive film using a porous PTFE film as a base film, and including a step of forming a through hole in a film thickness direction at a specific position of the porous film by an ultrasonic method, For example, (i) the porous polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of the base film composed of the porous polytetrafluoroethylene film (A) to form a three-layer structure. Forming a body, (ii) impregnating a liquid into the porous body of the laminate, and freezing the liquid, and (iii) using an ultrasonic head having at least one rod at the tip. Pressing the tip of the rod against the surface of the laminate and applying ultrasonic energy to form a patterned through-hole in the laminate, (iv) raising the temperature of the laminate and freezing the frozen body in the porous body; A process of returning to liquid and removing it, V) a step of adhering catalyst particles for promoting the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes, (vi) a step of peeling off the mask layers on both surfaces, and (vii) electroless plating of the through holes. A manufacturing method including a step of attaching a conductive metal to a resin portion having a porous structure on a wall surface is exemplified.
[0050]
When a laminate having a three-layer structure is used, in the method of forming a through hole shown in FIG. 10, the tip of the rod 102 is attached to the laminate using an ultrasonic head 101 having at least one rod 102 attached to the tip. Usually, ultrasonic energy is applied by pressing against the surface of a porous PTFE film (three-layer structure) 103.
[0051]
In a manufacturing method including a step of impregnating a liquid into the porous body of the laminate and freezing the liquid, water or alcohol (for example, methanol, methanol, or the like) is contained inside the porous body of the three-layered porous PTFE membrane. A liquid such as an organic solvent such as a lower alcohol such as ethanol and isopropanol is impregnated and cooled to freeze the liquid. While the impregnated liquid is in a frozen state, processing is performed by applying ultrasonic energy by pressing the tip of the rod against the surface of the laminate using an ultrasonic head having at least one rod at the tip. Thus, the pattern-like through-holes can be formed neatly. When water is used as the liquid, if the liquid is cooled to zero degree or less, preferably to -10 ° C. or less and frozen, workability is improved. In the case of an organic solvent such as an alcohol, the workability is improved by cooling to −50 ° C. or lower, preferably to the temperature of liquid nitrogen. The organic solvent is preferably a liquid at ordinary temperature. The organic solvent such as alcohol may be a mixture of two or more kinds, or may contain water.
[0052]
Examples of a method for making the electrically insulating porous film conductive include a sputtering method, an ion plating method, and an electroless plating method. Is preferably an electroless plating method. In the electroless plating method, usually, it is necessary to provide a catalyst that promotes a chemical reduction reaction to a portion where plating is to be deposited. In order to perform plating only on a resin portion having a porous structure in a specific portion of the porous film, a method of applying a catalyst only to the portion is effective.
[0053]
For example, when only the wall surface (hole wall) of a porous PTFE film in which fine through holes of an arbitrary shape are formed in the film thickness direction is given electroconductivity by copper plating, three layers with a mask layer are formed. A through hole is formed in the laminated body in the fused state, and the laminated body is immersed in a palladium-tin colloid catalyst-providing liquid with sufficient stirring. When the mask layers (B) and (C) on both surfaces are peeled off after immersion in the catalyst application liquid, a porous PTFE film (A) having the catalyst colloid particles adhered only to the wall surfaces of the through holes can be obtained. By immersing the porous PTFE film (A) in the plating solution, copper can be deposited only on the wall surface of the through-hole, thereby forming a tubular conductive portion (electrode). In addition to copper, nickel, silver, gold, a nickel alloy, or the like can form a conducting portion by the same method. However, when high conductivity is required, copper is preferably used. As a method of forming a through-hole in the three-layered laminated body, a method of irradiating synchrotron radiation light or laser light of 250 mm or less, and an ultrasonic method are preferable.
[0054]
The plating particles (crystal grains) are deposited so as to be entangled with the fine fibers (fibrils) exposed on the wall surfaces of the through-holes of the porous PTFE membrane. Therefore, by controlling the plating time, the state of adhesion of the conductive metal can be controlled. can do. If the electroless plating time is too short, it becomes difficult to obtain conductivity in the film thickness direction. If the electroless plating time is too long, the conductive metal is not porous but becomes a metal lump, and it is difficult to recover elasticity under a normal applied compressive load. By setting an appropriate plating amount, a porous conductive metal layer is formed, and it is possible to provide elasticity and conductivity in the film thickness direction.
[0055]
It is preferable to use an antioxidant or coat a noble metal or a noble metal alloy on the tubular conductive portion (electrode) manufactured as described above in order to prevent oxidation and enhance electrical contact. As the noble metal, palladium, rhodium, and gold are preferable because of their low electric resistance. The thickness of the coating layer of a noble metal or the like is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.1 μm. If the thickness of the coating layer is too small, the effect of improving the electrical contact is small, and if the thickness is too large, the coating layer is liable to peel off. For example, when the conductive portion is covered with gold, a method of covering the conductive metal layer with about 8 nm of nickel and then performing displacement gold plating is effective.
[0056]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples. The measuring method of the physical properties is as follows.
[0057]
(1) Bubble point (BP):
The bubble point of the porous PTFE membrane by the stretching method was measured according to ASTM-F-316-76 using isopropyl alcohol.
[0058]
(2) Porosity:
The porosity of the porous PTFE membrane by the stretching method was measured according to ASTM D-792.
[0059]
(3) Conduction start load:
The conduction start load of the anisotropic conductive film was measured using the conduction confirmation device shown in FIG. 5, the anisotropic conductive film 51 is placed on a gold-plated copper plate (referred to as “Au plate”) 52, and the whole is placed on a weighing scale 56. A copper column 53 having an outer diameter of 3 mm is used as a probe, and a load is applied. The resistance value of the anisotropic conductive film is measured by a four-needle method. The pressing load pressure was calculated from the load having a resistance value of 0.5Ω or less, and was defined as the conduction start load pressure. In FIG. 5, reference numeral 54 denotes a constant current power supply, and 55 denotes a voltmeter.
[0060]
(4) Number of continuity tests:
The anisotropic conductive film was cut into a 5 mm square to obtain a sample. Using TMA / SS120C manufactured by Seiko Instruments Inc., at room temperature and in a nitrogen gas atmosphere, 3 mm diameter quartz was used as a probe and the elastic recovery performance was verified by a needle insertion method. Loading and unloading were repeated 10 times with a load that caused the film thickness distortion to be 38% so that each anisotropic conductive film would conduct, and then a re-conductivity test was performed with a change in film thickness and a load at which conduction started.
[0061]
[Example 1]
A 10 cm square area, a porosity of 60%, an average pore diameter of 0.1 μm (BP = 150 kPa), a thickness of 30 μm, and a stack of three porous PTFE films by a stretching method are superposed to form a 3 mm thick, 150 mm long, 100 mm wide stainless steel. The sheet was sandwiched between two plates and heat-treated at 350 ° C. for 30 minutes with the load of the stainless plate. After heating, the stainless steel plate was rapidly cooled with water to obtain a laminate of a porous PTFE membrane fused to three layers.
[0062]
Next, a tungsten sheet having an aperture ratio of 9%, an opening diameter of 15 μmφ, and a pitch of 80 μm, which are uniformly arranged, is superposed on one side of the laminate, and is irradiated with synchrotron radiation to form a film with a hole diameter of 15 μmφ and a pitch of 80 μm in the thickness direction. Through holes were evenly arranged.
[0063]
The laminate having a through-hole of 15 μmφ was immersed in ethanol for 1 minute to hydrophilize, and then immersed in Meltex PC-321 diluted to 100 ml / L at a temperature of 60 ° C. for 4 minutes. A degreasing treatment was performed. Further, the laminate was immersed in 10% sulfuric acid for 1 minute, and then as a pre-dip, immersed in a solution of Enplate PC-236 manufactured by Meltex Co., Ltd. in 0.8% hydrochloric acid at a rate of 180 g / L for 2 minutes. did.
[0064]
Further, the laminate was dissolved in an aqueous solution in which 3% of Enplate Activator 444 manufactured by Meltex Co., 1% of Enplate Activator Additive and 3% of hydrochloric acid were dissolved, and 150 g of Enplate PC-236 manufactured by Meltex Co., Ltd. was dissolved. The catalyst particles were immersed for 5 minutes in a solution dissolved in a proportion of L to adhere the catalyst particles to the surface of the laminate and the wall surfaces of the through holes. Next, the laminate was immersed in a 5% solution of Enplate PA-360 manufactured by Meltex Co., Ltd. for 5 minutes to activate the palladium catalyst nucleus. Thereafter, the first and third mask layers were peeled off to obtain a porous PTFE membrane (base film) having catalytic palladium particles adhered only to the wall surfaces of the through holes.
[0065]
Meltex Cu-3000A, Mel-plate Cu-3000B, Mel-plate Cu-3000C, Mel-plate Cu-3000D manufactured by Meltex Co., Ltd. 5% each, Mel-plate Cu-3000 stabilizer 0.1% The base film was immersed in an electrolytic copper plating solution for 20 minutes while sufficiently stirring with air, and only the wall surfaces of the 15 μmφ through-holes were made conductive with copper particles (outer diameter of the electrode = 25 μm). Further, it was immersed for 30 seconds in Entec Cu-56 manufactured by Meltex Co., Ltd., which was bathed at 5 ml / L, and treated for rust prevention to obtain an anisotropic conductive film having a porous PTFE film as a base film.
[0066]
In the plating step, after immersion in each solution except between the pre-dipping step of electroless steel plating and the catalyst applying step, washing with distilled water was performed for about 30 seconds to about 1 minute. The temperature of each liquid was all room temperature (20 to 30 ° C.) except for the degreasing treatment.
[0067]
An anisotropic conductive film having a porous PTFE film as a base film obtained as described above was cut into a 10 mm square, and the conduction start load was measured by the apparatus shown in FIG. The probe used a copper column of 3 mmφ, and the resistance value was measured by a four-needle method. The pressing load was calculated from the load at which the low resistance value became 0.5Ω or less, and was determined as the conduction start load pressure. As a result, the conduction start load pressure was 6 kPa.
[0068]
Further, the anisotropic conductive film was cut into a square of 5 mm, and using TMA / SS120C manufactured by Seiko Instruments Inc., at room temperature and in a nitrogen gas atmosphere, 3 mmφ of quartz was used as a probe, and the elastic recovery performance was measured by a needle insertion method. Verified. Loading and unloading were repeated a total of 10 times, and each time a film thickness displacement and a film thickness direction conduction test were performed. If the resistance value is 0.5Ω or less as in the above case, it is determined that there is conduction. As a result, the conduction start load pressure was 6 kPa. Even after 10 times of repeated loading and unloading at a load pressure of 27.7 kPa at which sufficient conduction is obtained and the film thickness distortion becomes 38%, the film thickness before the test is substantially unchanged when no load is applied. Maintained, conduction was confirmed even at the conduction start load pressure of 6 kPa.
[0069]
[Example 2]
Under the same method and the same conditions as in Example 1, three porous PTFE films were fused to form a laminate. A through-hole of 10 μmφ was formed in this laminate, and then a pre-plating treatment was performed. After the mask layer is peeled off, the base film is immersed in an electroless copper plating solution for 20 minutes while sufficiently stirring with air, and copper particles are adhered only to the wall surfaces of the 10 μmφ through-holes to make them conductive (electrode outer diameter = 17 μm). Further, the same rust prevention treatment as in Example 1 was performed to obtain an anisotropic conductive film having a porous PTFE film as a base film by a stretching method. When a test similar to that of Example 1 was performed using the obtained anisotropic conductive film, the conduction start load pressure was 6 kPa. Even after 10 times of repeated loading and unloading at a load pressure of 27.7 kPa at which sufficient conduction is obtained and the film thickness distortion becomes 38%, the film thickness before the test is substantially unchanged when no load is applied. Maintained, conduction was confirmed even at the conduction start load pressure of 6 kPa.
[0070]
[Comparative Example 1]
Three 10 cm square, porosity of 60%, average pore diameter of 0.1 μm (BP = 150 kPa), and a 30 μm thick porous PTFE film are laminated by a stretching method, and a 3 mm thick, 150 mm long, 100 mm wide stainless steel plate is laminated. The sheet was sandwiched between two sheets and heat-treated at 350 ° C. for 30 minutes with a load on a stainless steel plate. After heating, the plate was rapidly cooled with water from above the stainless plate, and three sheets were fused to obtain a laminate.
[0071]
Next, a tungsten sheet having an aperture ratio of 9%, an aperture diameter of 25 μmφ, and a pitch of 60 μm, which are uniformly arranged, is superposed on one side of the laminate, and is irradiated with synchrotron radiation, and is uniformly distributed in the film thickness direction with a hole diameter of 25 μmφ and a pitch of 60 μm. Was formed.
[0072]
The laminate having a hole having a diameter of 25 μm was immersed in ethanol for 1 minute to make it hydrophilic, and then immersed in a Melplate PC-321 diluted to 100 ml / L at a water temperature of 60 ° C. for 4 minutes to perform degreasing treatment. Was done. Further, after the laminate was immersed in 10% sulfuric acid for 1 minute, it was immersed as a pre-dip for 2 minutes in a solution in which Enplate PC-236 manufactured by Meltex Co., Ltd. was dissolved in 0.8% hydrochloric acid at a rate of 180 g / L. .
[0073]
Next, 150 g / L of Melplate's Enplate PC-236 was added to an aqueous solution in which 3% of Enplate Activator 444 manufactured by Meltex Co., 1% of Enplate Activator Additive and 3% of hydrochloric acid were dissolved. The laminate was immersed in the liquid dissolved in the above for 5 minutes to cause the catalyst particles to adhere to the surface of the laminate and the wall surfaces of the through holes. Further, the laminate was immersed in a 5% solution of Enplate PA-360 manufactured by Meltex Co., Ltd. for 2 minutes to activate the palladium catalyst nucleus.
[0074]
Meltex Cu-3000A, Mel-plate Cu-3000B, Mel-plate Cu-3000C, Mel-plate Cu-3000D manufactured by Meltex Co., Ltd. 5% each, Mel-plate Cu-3000 stabilizer 0.1% The laminate was immersed in an electrolytic copper plating solution for 5 minutes while sufficiently stirring with air, and the surface and the wall surfaces of the through holes were made conductive with copper particles.
[0075]
Next, as an electrolytic copper plating solution, copper cream CLX manufactured by Meltex Co., Ltd. was used, and the current density was 2 A / dm. 2 For 30 minutes, the through holes were filled with copper by electrolytic copper plating. Excessive plating on the mask surface is immersed in a 10% sulfuric acid solution until the surface of the mask layer is visually observed, etched, and then peeled off by hand to separate the mask layer. An anisotropic conductive film having conductivity only in the film thickness direction and having a 7 μm protruding electrode on the film surface was obtained.
[0076]
This anisotropic conductive film was immersed for 30 seconds in Entec Cu-56 manufactured by Meltex Co., Ltd. with a bath of 5 ml / L to prevent rust, and a porous PTFE film formed by a stretching method was used as a base film. To obtain an anisotropic conductive film filled with a conductive metal.
[0077]
In the plating step, after immersion in each solution except between the pre-dipping step of electroless copper plating and the catalyst applying step, washing with distilled water was performed for about 30 seconds to about 1 minute. The temperature of each liquid was all room temperature (20 to 30 ° C.) except for the degreasing treatment.
[0078]
In this way, as shown in FIG. 8, anisotropically having a conductive portion (electrode) 82 having a porous PTFE film 83 as a base film, a conductive metal filled in each through-hole, and projections on both surfaces. The conductive film 81 was obtained. When a test similar to that of Example 1 was performed using this anisotropic conductive film, the conduction start load pressure was 3 kPa. After sufficient loading and unloading were repeated 10 times at a load pressure of 37.0 kPa at which sufficient conduction was obtained and the film thickness distortion was 38%, the film thickness was reduced by 6.1 μm, and the conduction start load pressure was reduced. At 3 kPa, conduction was not obtained.
[0079]
[Comparative Example 2]
At room temperature, nickel particles (manufactured by Shin-Etsu Polymer Co., Ltd., KE 1206, addition type RTV rubber) to which a predetermined amount of a cross-linking agent has been added are adjusted to 80 vol% with nickel particles (manufactured by Nippon Atomize K.K. Compounded and mixed. This compound was cast on a glass plate with a doctor knife having a gap of 25 μm, and then cured for 1 hour in a constant temperature bath at 80 ° C. to obtain an anisotropic conductive film in which metal particles having a thickness of about 22 μm were dispersed in a silicone elastomer. .
[0080]
In this way, as shown in FIG. 9, an anisotropic conductive film 91 having a structure in which conductive particles 93 were dispersed in a base film 92 made of silicone rubber was obtained. When a test similar to that of Example 1 was performed using this anisotropic conductive film, the conduction start load pressure was 25 kPa. After 10 cycles of loading and unloading at a load pressure of 28.0 kPa at which sufficient conduction is obtained and the film thickness distortion becomes 38%, the film thickness decreases by 0.7 μm and the conduction start load pressure is reduced. No conduction was obtained at 25 kPa.
[0081]
[Table 1]
Figure 2004265844
[0082]
(Footnote) The film thickness of Comparative Example 1 includes the projection height of the conductive portion.
[0083]
【The invention's effect】
According to the present invention, an anisotropic conductive film which has elasticity in the film thickness direction, can conduct in the film thickness direction with a low compressive load, can recover elasticity, and is suitable for frequent use Is provided. Further, according to the present invention, there is provided an anisotropic conductive film capable of reducing the size, pitch, and the like of each conductive portion. The anisotropic conductive film of the present invention is mainly used as an anisotropic conductive film for inspection of semiconductor wafers or the like. The thickness returns, and it can be used repeatedly for inspection.
[Brief description of the drawings]
FIG. 1 is a perspective view of a porous film in which a through hole is formed.
FIG. 2 is a cross-sectional view of the anisotropic conductive film of the present invention, showing a state in which conductive metal particles are attached to a resin portion having a porous structure on a wall surface of each through hole to form a conductive portion. FIG.
FIG. 3 is an explanatory diagram showing a relationship between a diameter a of a through hole and an outer diameter b of a conduction portion (electrode).
FIG. 4 is a cross-sectional view showing a manufacturing process of a laminate having a base film as a central layer.
FIG. 5 is a schematic cross-sectional view of a device for confirming conduction of an anisotropic conductive film.
FIG. 6 is a sectional view showing an example of a conventional anisotropic conductive film.
FIG. 7 is a cross-sectional view showing another example of the conventional anisotropic conductive film.
FIG. 8 is a cross-sectional view of the anisotropic conductive sheet manufactured in Comparative Example 1.
FIG. 9 is a cross-sectional view of the anisotropic conductive sheet produced in Comparative Example 2.
FIG. 10 is an explanatory view showing a method of forming a through hole in a porous film by an ultrasonic method.
[Explanation of symbols]
1: porous membrane (base membrane), 2: first surface, 3: second surface,
4: through-hole, 5: conductive part with conductive metal attached, 6: porous membrane,
41, 42: SUS plate, 43: base film, 44, 45: mask layer,
51: anisotropic conductive film, 52: Au plate, 53: copper pillar,
54: constant current power supply, 55: voltmeter, 56: weigh scale,
61: anisotropic conductive film, 62: lump of conductive metal (conductive portion), 63: porous film,
71: anisotropic conductive film, 72: conductive path forming portion,
73: capsule-type conductive particles, 74: insulating portion made of thermosetting resin,
81: anisotropic conductive film, 82: conductive metal lump (conductive portion), 83: porous film,
91: anisotropic conductive film, 92: silicone rubber, 93: conductive particles,
101: ultrasonic head, 102: rod, 103: porous film, 104: plate.

Claims (21)

合成樹脂から形成された電気絶縁性の多孔質膜を基膜とし、該基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に付着した導電性金属により形成され、膜厚方向に導電性を付与することが可能な導通部がそれぞれ独立して設けられていることを特徴とする異方性導電膜。An electrically insulating porous film formed of a synthetic resin as a base film, and a conductive metal adhered to a resin portion of a porous structure at a plurality of locations of the base film in a state of penetrating from a first surface to a second surface. And conductive portions capable of imparting conductivity in the film thickness direction are provided independently of each other. 各導通部が、該基膜の複数箇所に、第一表面から第二表面に貫通する貫通孔の壁面で多孔質構造の樹脂部に付着した導電性金属により形成されている請求項1記載の異方性導電膜。2. The conductive film according to claim 1, wherein each conductive portion is formed at a plurality of locations of the base film by a conductive metal adhered to a resin portion having a porous structure at a wall surface of a through hole penetrating from the first surface to the second surface. Anisotropic conductive film. 各導通部が、多孔質構造の樹脂部に連続して付着した導電性金属の粒子により形成されている請求項1または2記載の異方性導電膜。3. The anisotropic conductive film according to claim 1, wherein each conductive portion is formed of conductive metal particles continuously attached to the resin portion having a porous structure. 導電性金属の粒子が、導電性金属の無電解めっき粒子である請求項3記載の異方性導電膜。The anisotropic conductive film according to claim 3, wherein the conductive metal particles are electroless plated particles of the conductive metal. 多孔質膜が、多孔質ポリテトラフルオロエチレン膜である請求項1乃至4のいずれか1項に記載の異方性導電膜。The anisotropic conductive film according to any one of claims 1 to 4, wherein the porous film is a porous polytetrafluoroethylene film. 多孔質構造の樹脂部が、それぞれポリテトラフルオロエチレンからなるフィブリルと該フィブリルによって互に連結されたノードとから形成された多孔質構造の該フィブリルとノードである請求項5記載の異方性導電膜。6. The anisotropic conductive material according to claim 5, wherein the resin portion of the porous structure is a fibril and a node of a porous structure formed of fibrils each made of polytetrafluoroethylene and nodes connected to each other by the fibrils. film. 導通部が、多孔質膜の多孔質構造を保持した状態で、多孔質構造の樹脂部に付着した導電性金属により形成されている請求項1乃至6のいずれか1項に記載の異方性導電膜。The anisotropic material according to claim 1, wherein the conductive portion is formed of a conductive metal attached to the resin portion of the porous structure while maintaining a porous structure of the porous film. Conductive film. 膜厚方向に圧力を加えることにより、膜厚方向にのみ導電性が付与される請求項1乃至7のいずれか1項に記載の異方性導電膜。The anisotropic conductive film according to any one of claims 1 to 7, wherein conductivity is imparted only in the thickness direction by applying pressure in the thickness direction. 合成樹脂から形成された電気絶縁性の多孔質膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。At a plurality of locations of the base film made of an electrically insulating porous film formed of a synthetic resin, a conductive metal is adhered to the resin portion of the porous structure while penetrating from the first surface to the second surface, A method for producing an anisotropic conductive film, wherein conductive portions capable of imparting conductivity in the thickness direction are independently provided. 該基膜の複数箇所に、第一表面から第二表面に貫通する貫通孔を形成し、該貫通孔の壁面で多孔質構造の樹脂部に導電性金属を連続して付着させることにより、導通部を設ける請求項9記載の製造方法。At a plurality of locations of the base film, through holes are formed that penetrate from the first surface to the second surface, and a conductive metal is continuously attached to the resin portion of the porous structure on the wall surfaces of the through holes, thereby providing conduction. The manufacturing method according to claim 9, wherein a portion is provided. 該基膜の複数箇所に、シンクロトロン放射光もしくは波長250nm以下のレーザ光を照射して、第一表面から第二表面に貫通する貫通孔を形成する請求項10記載の製造方法。The method according to claim 10, wherein a plurality of portions of the base film are irradiated with synchrotron radiation or laser light having a wavelength of 250 nm or less to form a through hole penetrating from the first surface to the second surface. 該基膜の複数箇所に、超音波加工により、第一表面から第二表面に貫通する貫通孔を形成する請求項10記載の製造方法。The manufacturing method according to claim 10, wherein through holes are formed in a plurality of portions of the base film from the first surface to the second surface by ultrasonic processing. 多孔質構造の樹脂部に導電性金属の粒子を付着させることにより、導通部を設ける請求項9乃至12のいずれか1項に記載の製造方法。The method according to claim 9, wherein the conductive portion is provided by attaching conductive metal particles to the resin portion having a porous structure. 各貫通孔の壁面で多孔質構造の樹脂部に、無電解めっきにより導電性金属を付着させる請求項10乃至13のいずれか1項に記載の製造方法。14. The manufacturing method according to claim 10, wherein a conductive metal is attached to the resin portion having a porous structure on the wall surface of each through hole by electroless plating. 各貫通孔の壁面で多孔質構造の樹脂部に、化学還元反応を促進する触媒粒子を付着させた後、化学還元反応による無電解めっきにより導電性金属を付着させる請求項14記載の製造方法。The production method according to claim 14, wherein after the catalyst particles for promoting the chemical reduction reaction are attached to the resin portion of the porous structure on the wall surface of each through-hole, the conductive metal is attached by electroless plating by the chemical reduction reaction. 多孔質膜が、多孔質ポリテトラフルオロエチレン膜である請求項9乃至15のいずれか1項に記載の製造方法。The method according to any one of claims 9 to 15, wherein the porous film is a porous polytetrafluoroethylene film. (1)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層としてポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、
(2)一方のマスク層の表面から、所定のパターン状にそれぞれ独立した複数の光透過部を有する光遮蔽シートを介して、シンクロトロン放射光または波長250nm以下のレーザ光を照射することにより、積層体にパターン状の貫通孔を形成する工程、
(3)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、
(4)両面のマスク層を剥離する工程、及び
(5)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程
の各工程により、多孔質ポリテトラフルオロエチレン膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。
(1) Polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of a base film made of a porous polytetrafluoroethylene film (A) to form a three-layer laminate. Process,
(2) By irradiating synchrotron radiation light or laser light having a wavelength of 250 nm or less from the surface of one of the mask layers via a light shielding sheet having a plurality of independent light transmission portions in a predetermined pattern, Forming a patterned through-hole in the laminate,
(3) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes;
(4) a step of removing the mask layers on both sides, and (5) a step of attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through hole by electroless plating, thereby forming porous polytetrafluoroethylene. It is possible to impart conductivity in the thickness direction by attaching a conductive metal to the resin portion of the porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations of the base film made of the film. A method for manufacturing an anisotropic conductive film, wherein conductive portions are provided independently of each other.
(I)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層としてポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、
(II)先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、積層体にパターン状の貫通孔を形成する工程、
(III)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、
(IV)両面のマスク層を剥離する工程、及び
(V)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程
の各工程により、多孔質ポリテトラフルオロエチレン膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。
(I) Polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of a base film made of a porous polytetrafluoroethylene film (A) to form a three-layer laminate. Process,
(II) Using a ultrasonic head having at least one rod at the tip, pressing the tip of the rod against the surface of the laminate and applying ultrasonic energy to form a patterned through hole in the laminate. The process of
(III) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes;
(IV) a step of removing the mask layers on both sides, and (V) a step of attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through-hole by electroless plating, thereby forming porous polytetrafluoroethylene. It is possible to impart conductivity in the thickness direction by attaching a conductive metal to the resin portion of the porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations of the base film made of the film. A method for manufacturing an anisotropic conductive film, wherein conductive portions are provided independently of each other.
(i)多孔質ポリテトラフルオロエチレン膜(A)からなる基膜の両面に、マスク層として多孔質ポリテトラフルオロエチレン膜(B)及び(C)を融着させて3層構成の積層体を形成する工程、
(ii)積層体の多孔質内に液体を染み込ませて、該液体を凍結させる工程、
(iii)先端部に少なくとも1本のロッドを有する超音波ヘッドを用いて、該ロッドの先端を積層体の表面に押付けて超音波エネルギーを加えることにより、積層体にパターン状の貫通孔を形成する工程、
(iv)積層体を昇温して、多孔質内の凍結体を液体に戻して除去する工程、
(V)貫通孔の壁面を含む積層体の全表面に化学還元反応を促進する触媒粒子を付着させる工程、
(vi)両面のマスク層を剥離する工程、及び
(vii)無電解めっきにより貫通孔の壁面で多孔質構造の樹脂部に導電性金属を付着させる工程
の各工程により、多孔質ポリテトラフルオロエチレン膜からなる基膜の複数箇所に、第一表面から第二表面に貫通する状態で多孔質構造の樹脂部に導電性金属を付着させて、膜厚方向に導電性を付与することが可能な導通部をそれぞれ独立して設けることを特徴とする異方性導電膜の製造方法。
(I) Porous polytetrafluoroethylene films (B) and (C) are fused as mask layers on both surfaces of a base film composed of a porous polytetrafluoroethylene film (A) to form a three-layer laminate. Forming,
(Ii) impregnating a liquid into the porous body of the laminate and freezing the liquid;
(Iii) Using an ultrasonic head having at least one rod at the tip, pressing the tip of the rod against the surface of the laminate and applying ultrasonic energy to form a patterned through hole in the laminate. Process,
(Iv) a step of raising the temperature of the laminate and returning the frozen body in the porous body to a liquid to remove the frozen body;
(V) attaching catalyst particles that promote the chemical reduction reaction to the entire surface of the laminate including the wall surfaces of the through holes;
(Vi) a step of peeling off the mask layers on both sides, and (vii) a step of attaching a conductive metal to the resin portion of the porous structure on the wall surface of the through hole by electroless plating to form a porous polytetrafluoroethylene. It is possible to impart conductivity in the thickness direction by attaching a conductive metal to the resin portion of the porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations of the base film made of the film. A method for manufacturing an anisotropic conductive film, wherein conductive portions are provided independently of each other.
前記工程(ii)において、多孔質内に染み込ませる液体として、水または有機溶剤を使用する請求項19記載の製造方法。20. The method according to claim 19, wherein in the step (ii), water or an organic solvent is used as the liquid to be impregnated into the porous material. 多孔質構造の樹脂部に導電性金属を付着させるに際し、粒子径0.001〜5μmの導電性金属粒子を付着量0.001〜4.0g/mlで付着させる請求項9乃至20のいずれか1項に記載の製造方法。21. The conductive metal particles having a particle diameter of 0.001 to 5 [mu] m at a deposition amount of 0.001 to 4.0 g / ml when the conductive metal is deposited on the resin portion having a porous structure. Item 2. The production method according to item 1.
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