JP4709339B2 - Thermally conductive adhesive, bonding method, and electronic component - Google Patents

Thermally conductive adhesive, bonding method, and electronic component Download PDF

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Publication number
JP4709339B2
JP4709339B2 JP25601199A JP25601199A JP4709339B2 JP 4709339 B2 JP4709339 B2 JP 4709339B2 JP 25601199 A JP25601199 A JP 25601199A JP 25601199 A JP25601199 A JP 25601199A JP 4709339 B2 JP4709339 B2 JP 4709339B2
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Prior art keywords
conductive adhesive
heat
adhesive
polybenzazole
electronic component
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JP2001081435A (en
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恒久 木村
正文 山登
雅之 飛田
秀明 小嶋
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Polymatech Co Ltd
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Polymatech Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
    • H01L24/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L24/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32245—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73253—Bump and layer connectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73265—Layer and wire connectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/91—Methods for connecting semiconductor or solid state bodies including different methods provided for in two or more of groups H01L2224/80 - H01L2224/90
    • H01L2224/92—Specific sequence of method steps
    • H01L2224/922—Connecting different surfaces of the semiconductor or solid-state body with connectors of different types
    • H01L2224/9222—Sequential connecting processes
    • H01L2224/92242—Sequential connecting processes the first connecting process involving a layer connector
    • H01L2224/92247—Sequential connecting processes the first connecting process involving a layer connector the second connecting process involving a wire connector
    • H—ELECTRICITY
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    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/73—Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/30—Technical effects
    • H01L2924/35—Mechanical effects
    • H01L2924/351—Thermal stress

Abstract

PROBLEM TO BE SOLVED: To obtain an electrical-insulating heat-conductive adhesive capable of effectively dissipating heat generated from parts of semiconductor elements, power sources, light sources and the like which are used in electric appliances, a bonding method, and an electronic part having excellent heat dissipation properties. SOLUTION: A heat-conductive adhesive is obtained by compounding polybenzazole staple fibers with an adhesive polymer. A bonding method comprises allowing a heat-conductive adhesive obtained by compounding polybenzazole staple fibers with an adhesive polymer to be present between adherends to effect bonding in a state that the polybenzazole staple fibers in the heat conducting adhesive have been oriented to a definite direction by an external magnetic field. An electronic part is obtained by allowing a heat- conductive adhesive obtained by compounding polybenzazole short fibers with an adhesive polymer to be present between an exothermic element and a heat transfer member to effect bonding in a state that the polybenzazole staple fibers in the heat-conductive adhesive have been oriented in a definite direction by an external magnetic field.

Description

【０００１】
【発明の属する技術分野】
本発明は高い熱伝導性が要求される熱伝導性接着剤および接着方法ならびに電子部品に関する。さらに詳しくは、電気製品に使用される半導体素子や電源、光源などの部品から発生する熱を効果的に放散させる熱伝導性接着剤および接着方法ならびに放熱性にすぐれる電子部品に関する。
【０００２】
【従来の技術】
従来より、発熱する半導体素子や電子部品と放熱させる伝熱部材とを接合させる目的で接着性高分子をマトリックスとした熱伝導性接着剤が使用されている。これらの接着剤には、熱伝導性を高めるために、銀、銅、金、アルミニウム、ニッケルなどの熱伝導率の大きい金属や合金、化合物、あるいは酸化アルミニウム、酸化マグネシウム、酸化ケイ素、窒化ホウ素、窒化アルミニウム、窒化ケイ素、炭化ケイ素などのセラミックス製の粉末状の充填剤、カーボンブラックやダイヤモンドなどの粉粒体形状や繊維形状の熱伝導性充填剤が配合されている。
【０００３】
熱伝導性充填材として炭素材料を接着性高分子に配合する熱伝導性接着剤は公知であり、たとえば、特開昭６３−３０５５２０号公報では炭素系の微粉末や炭素繊維を充填したダイボンド材料、特開平６−２１２１３７号公報ではメソフェーズピッチを基材とした３次元構造の炭素繊維を充填した接着性材料が提唱されている。また、特開平９−３２４１２７号公報は、特定の高分子材料を熱処理して得られるグラファイトを使用した半導体素子用ダイボンド材である。
【０００４】
さらに、特開平５−２０９１５７号公報、特開平６−２９９１２９号公報によれば、含有させる炭素繊維や金属繊維の構造を、かたまり状や糸まり状、あるいは織布や不織布の形状に特定することによって放熱特性を一層改善した電子デバイス用接着剤が開示されている。
一方、特開昭６２−１９４６５３号公報、特開昭６３−６２７６２号公報によれば、ニッケルなどの磁性体粉末を含む接着剤を磁場中で厚み方向に配向させて熱伝導率を向上させる接着方法が開示されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記の特開昭６３−３０５５２０号公報、特開平６−２１２１３７号公報、特開平９−３２４１２７号公報、特開平５−２０９１５７号公報、特開平６−２９９１２９号公報、特開昭６２−１９４６５３号公報、特開昭６３−６２７６２号公報などの接着剤や接着方法は、いずれも導電性の高い炭素材料、金属系の繊維、磁性体粉末などを配合するために電気絶縁性を要求される用途には応用できなかった。
【０００６】
また、特開平２−４５５８１号公報は、有機質短繊維としてレーヨン、ビニロン、綿糸、ポリエステル繊維、ポリアミド繊維などの電気絶縁性の短繊維を配合した制振用複合金属板の制振接着層として用いられるものである。しかし熱伝導性を改良したものではなかった。
【０００７】
すなわち、電気絶縁性が良好で高い熱伝導特性を有する接着剤が開発されていないために、半導体素子などの電子部品からの多大な発熱によって、電気化学的なマイグレーションが加速されたり、配線やパッド部の腐食が促進されたり、発生する熱応力によって構成材料にクラックが生じたり、破壊したり、構成材料の接合部の界面が剥離して電子部品の寿命を損なう様々なトラブルが発生していた。
【０００８】
一方、本出願人による特願平１１−８５１０７号公報の熱伝導性接着剤では、熱伝導率が２０Ｗ／ｍ・Ｋ以上の反磁性充填材を接着剤中に配合させているけれども、反磁性充填材としてポリベンザゾール短繊維は対象として考えていなかった。
【０００９】
【課題を解決するための手段】
本発明は、上述の課題を解決する目的で、電気製品に使用される半導体素子や電源、光源などの部品から発生する熱を効果的に放散させる電気絶縁性の熱伝導性接着剤および接着方法ならびに放熱特性にすぐれる電子部品を提供するものである。
【００１０】
【発明の実施の形態】
すなわち、本発明は、ポリベンザゾール短繊維と接着性高分子とを配合してなることを特徴とする熱伝導性接着剤である。さらに本発明は、被着体間に、ポリベンザゾール短繊維と接着性高分子とを配合してなる熱伝導性接着剤を介在させ、外部磁場によって熱伝導性接着剤中のポリベンザゾール短繊維を一定方向に配向させた状態で接着させることを特徴とする接着方法である。さらに本発明は、発熱する素子と伝熱部材間に、ポリベンザゾール短繊維と接着性高分子とを配合してなる熱伝導性接着剤を介在させ、外部磁場によって熱伝導性接着剤中のポリベンザゾール短繊維を一定方向に配向させた状態で接着させた構造を特徴とする電子部品である。
【００１１】
本発明で使用するポリベンザゾール短繊維は、ポリベンザゾールポリマーより構成される短繊維であり、ポリベンザゾール（ＰＢＺ）とは、ポリベンゾオキサゾールホモポリマー（ＰＢＯ）、ポリベンゾチアゾールホモポリマー（ＰＢＴ）およびそれらＰＢＯ、ＰＢＴのランダムコポリマー、シーケンシャルコポリマー、ブロックコポリマーあるいはグラフトコポリマーを意味するものである。ポリベンザゾール短繊維の長さ、直径、断面形状等ついては特定するものではないけれども、ポリベンザゾール短繊維の長さは１ｍｍ以下であることが好ましい。１ｍｍよりも長いポリベンザゾール短繊維を用いると、接着性高分子に均一に分散しにくく、接着剤組成物としての粘度が上昇して作業性が悪化するので好ましくない。より好ましいポリベンザゾール短繊維の長さは０.８ｍｍ以下、さらに好ましくは０.５ｍｍ以下、さらに好ましくは０.２ｍｍ以下である。
【００１２】
また、ポリベンザゾール短繊維の形状は、通常の短繊維形状のほか、ウィスカー形状やパルプ形状のポリベンザゾール短繊維も使用することができる。本発明の熱伝導性接着剤に含有させるポリベンザゾール短繊維の量は、接着性高分子１００重量部に対して０.１〜５０重量部が好ましい。０．１重量部よりも少ないと熱伝導性の向上効果が小さく、５０重量部を越えて含有させると接着剤組成物の粘度が増大して流動性が損なわれて作業性が悪化し、かつ気泡の混入が避けられないので不適である。さらに好ましいポリベンザゾール短繊維の添加量は０.５〜３０重量部、さらに好ましくは１〜２０重量部である。
【００１３】
ポリベンザゾール短繊維は、ポリベンザゾール長繊維を一定長さに切断する方法などによって製造することが可能であり、市販品（東洋紡績株式会社製 商品名＝ザイロン）として容易に入手することができる。ポリベンザゾール短繊維の引張強度については、４ＧＰａ以上でかつ初期引張弾性率が１４０ＧＰａ以上を有することが好ましい。引張強度、初期引張弾性率がこの範囲であるポリベンザゾール短繊維を使用することによって、本発明の熱伝導性接着剤および電子部品は高い熱伝導性を発現することができる。
【００１４】
なお、ポリベンザゾール短繊維以外の繊維として、少量のアラミド繊維やポリエステル繊維、脂肪族ポリアミド繊維、ビニロン繊維などの有機繊維、天然繊維、炭素繊維、金属繊維、セラミック繊維、さらにこれらの繊維を複合した複合繊維からなる短繊維や長繊維、あるいはそれらの少量の織布や不織布などを混在させることも可能である。しかしながら、本発明の熱伝導性接着剤は電気絶縁性にすぐれることも特徴のひとつであり、導電性の高い炭素繊維、金属繊維、金属被覆繊維などはなるべく混在させない方が好ましい。
【００１５】
マトリックスとなる接着性高分子としては、エポキシ系、ポリイミド系、アクリル系、ポリ酢酸ビニルなどのビニル系、ウレタン系、シリコーン系、オレフィン系、ポリアミド系、ポリアミドイミド系、フェノール系、アミノ系、ビスマレイミド系、ポリイミドシリコーン系、飽和および不飽和ポリエステル系、ジアリルフタレート系、尿素系、メラミン系、アルキッド系、ベンゾシクロブテン系、ポリブタジエンやクロロプレンゴム、ニトリルゴムなどの合成ゴム系、天然ゴム系、スチレン系熱可塑性エラストマーなどの公知の樹脂やゴムからなる液体状あるいは固体状の材料が好ましい。
【００１６】
硬化形態については、熱硬化性、熱可塑性、紫外線や可視光硬化性、常温硬化性、湿気硬化性など公知のあらゆる硬化形態の接着性高分子を使用できる。なかでも、電子部品を構成する材料の各種金属やセラミックス、各種プラスチックやゴム、エラストマーとの接着性が良好なエポキシ系、ポリイミド系、アクリル系、ウレタン系あるいはシリコーン系より選ばれる少なくとも１種の接着性高分子が好適である。
【００１７】
また、ポリベンザゾール短繊維の表面処理を目的として、ポリベンザゾール短繊維の表面をあらかじめ脱脂や洗浄処理したり、紫外線照射、コロナ放電処理、プラズマ処理、火炎処理あるいはイオン注入などの活性化処理を施すことが好ましい。さらにシラン系、チタン系あるいはアルミニウム系などの公知のカップリング剤やサイジング剤で処理することによって接着剤高分子との濡れ性を向上させたり充填性を改良することも可能である。さらに、本発明の熱伝導性接着剤には、チキソトロピー性付与剤、分散剤、硬化剤、硬化促進剤、遅延剤、粘着付与剤、可塑剤、難燃剤、酸化防止剤、安定剤、着色剤など公知の添加剤を配合することができる。
【００１８】
さらに、粉末形状の金属やセラミックス、具体的には、銀、銅、金、酸化アルミニウム、酸化マグネシウム、窒化アルミニウム、炭化ケイ素などや金属被覆樹脂などの従来の熱伝導性接着剤に使用されている充填剤などを適宜併用することも可能である。しかしながら、本発明の熱伝導性接着剤は電気絶縁性にすぐれることも特徴のひとつであり、導電性の高い金属などの充填剤はなるべく混在させない方が好ましい。
また、接着剤の粘度を低下させるためには、揮発性の有機溶剤や反応性可塑剤を添加すると作業性が向上して効果的である。
【００１９】
本発明の接着方法は、被着体間に、ポリベンザゾール短繊維と接着性高分子とを配合してなる熱伝導性接着剤を介在させ、外部磁場によって熱伝導性接着剤中のポリベンザゾール短繊維を一定方向に配向させた状態で接着させることを特徴とする接着方法である。
外部磁場によって、接着剤中のポリベンザゾール短繊維を磁力線に沿って配向させることによって、配向したポリベンザゾール短繊維の繊維方向の高い熱伝導性を生かして接着剤の熱伝導率を向上させることができる。被着体の間隙方向すなわち接着剤の厚み方向にポリベンザゾール短繊維を立てるように揃えて配向させるには、厚み方向に永久磁石や電磁石のＮ極とＳ極を対向させ磁力線の向きが所望のポリベンザゾール短繊維の配向方向に対応するように設置する。
【００２０】
一方、接着剤の面内方向の熱伝導性を向上させる場合には、厚み方向に対して垂直の方向に磁石のＮ極とＳ極を対向させればポリベンザゾール短繊維を面内方向に揃えて配向させることができる。あるいは、磁石のＮ極とＮ極、またはＳ極とＳ極を厚み方向に対向させてもポリベンザゾール短繊維を面内方向に揃えることができる。また、磁石については必ずしも両側に対向させる必要はなく、片側のみに配置した磁石によっても接着剤中のポリベンザゾール短繊維を配向させることが可能である。
【００２１】
外部磁場として使用する磁場発生手段としては永久磁石でも電磁石でも差し支えないけれども、磁束密度としては０．０５テスラ〜３０テスラの範囲が実用的なポリベンザゾール短繊維の配向が達成できる。また、本発明は磁性としてはポリベンザゾール短繊維の非常に弱い異方性磁化率を利用するので、１テスラ以上のより高磁場を用いて、ポリベンザゾール短繊維を十分に配向させてから、熱硬化反応や冷却させてマトリックスの接着性高分子を固化させて被着体を接着させる必要がある。
なお、参考までに本発明者らがポリベンザゾール繊維（東洋紡績株式会社製 ザイロンＨＭ）の異方性磁化率χａを磁気異方性トルク計（株式会社玉川製作所）で測定した結果は６．１×１０−７であった。
【００２２】
本発明の熱伝導性接着剤は、接着性高分子中に所定量のポリベンザゾール短繊維を混合して均一に分散させることによって製造することができる。混合あるいは混練して分散するときには、減圧あるいは加圧して混入した気泡を除去する公知の工程を加えることが好ましい。
発熱する素子と伝熱部材間に、本発明のポリベンザゾール短繊維と接着性高分子からなる熱伝導性接着剤を介在させ、外部磁場によって熱伝導性接着剤中のポリベンザゾール短繊維を一定方向に配向させた状態で接着させることによって図５(６)、図７(６)のような本発明の電子部品を製造することができる。
【００２３】
なお、熱伝導性接着剤はスクリーン印刷やパッド印刷、ディスペンサー塗布、ポッティング、スプレー塗装などの公知の方法によって被着体間に介在させることができる。発熱する素子としては、半導体素子、電源あるいは光源など、伝熱部材としては、通常の放熱器や冷却器、ヒートシンク、ヒートスプレッダー、ダイパッド、プリント基板、冷却ファン、ヒートパイプあるいは筐体などが挙げられる。
【００２４】
図１に本発明の熱伝導性接着剤をボールグリッドアレイ型半導体パッケージ２と放熱器４の接着に使用した電子部品の例を示す。
図２に本発明の熱伝導性接着剤をチップサイズ型半導体パッケージ２とプリント基板１の接着に使用した電子部品の例を示す。
図３に本発明の熱伝導性接着剤をピングリッドアレイ型半導体パッケージ２とヒートシンク５の接着に使用した電子部品の例を示す。
図４に本発明の熱伝導性接着剤を半導体チップ８とダイパッド７の接着に使用した電子部品の例を示す。
以下、実施例をあげて本発明をさらに詳細に説明する。以下、熱伝導率はレーザーフラッシュ法、体積抵抗率はＪＩＳ−Ｋ６９１１に準拠して測定した。
【００２５】
【実施例１】
エタノールで脱脂洗浄したポリベンザゾール短繊維（東洋紡績株式会社製 ザイロンＨＭ：直径１１μｍ、長さ５０μｍ）４重量部と、接着性高分子としてアミン系硬化剤を含むビスフェノールＦ型エポキシ樹脂１００重量部を混合し、真空脱泡して熱伝導性接着剤を調製した。テフロンコーティングしたアルミニウム製の厚み０．５ｍｍ、縦２０ｍｍ、横２０ｍｍの板状の金型内に調製した熱伝導性接着剤を充填し、厚み方向に磁束密度６テスラの磁石のＮ極とＳ極が対向する磁場雰囲気でポリベンザゾール短繊維を配向させて、加熱硬化させた。硬化物の熱伝導率は１．４Ｗ／ｍ・Ｋ、体積抵抗率は１０１２Ω・ｃｍであった。
【００２６】
【実施例２〜１２】
実施例１と同様に、表１に記す配合組成のポリベンザゾール短繊維と接着性高分子からなる熱伝導性接着剤を調製し、テフロンコーティングしたアルミニウム製の厚み０．５ｍｍ、縦２０ｍｍ、横２０ｍｍの板状の金型内に充填し、厚み方向に磁石のＮ極とＳ極が対向する表１に記載した磁束密度の磁場雰囲気でポリベンザゾール短繊維を配向させて、加熱硬化させた。測定した硬化物の熱伝導率と体積抵抗率を表１に記した。なお、表１で使用した長さの異なるポリベンザゾール短繊維は、東洋紡績株式会社製のザイロンＨＭ（直径１１μｍ）を切断して作製したものである。接着性高分子として用いた材料は、エポキシはアミン系硬化剤を含むビスフェノールＦ型エポキシ樹脂、シリコーンは付加型の液状シリコーンゴム、ポリイミドは加熱硬化型の液状ポリイミド、アクリルはシアノアクリレート系接着剤である。
【００２７】
【比較例１】
アミン系硬化剤を含むビスフェノールＦ型エポキシ樹脂製の接着性高分子１００重量部を、テフロンコーティングしたアルミニウム製の厚み０．５ｍｍ、縦２０ｍｍ、横２０ｍｍの板状の金型内に充填して加熱硬化させた。硬化物の熱伝導率は０．２Ｗ／ｍ・Ｋ、体積抵抗率は１０１２Ω・ｃｍであった。
【００２８】
【比較例２】
エタノールで脱脂洗浄したポリベンザゾール短繊維（東洋紡績株式会社製 ザイロンＨＭ：直径１１μｍ、長さ５０μｍ）４重量部と、接着性高分子としてアミン系硬化剤を含むビスフェノールＦ型エポキシ樹脂１００重量部を混合し、真空脱泡して熱伝導性接着剤を調製した。テフロンコーティングしたアルミニウム製の厚み０．５ｍｍ、縦２０ｍｍ、横２０ｍｍの板状の金型内に充填して磁場を印加せずに加熱硬化させた。硬化物の熱伝導率は０．３Ｗ／ｍ・Ｋ、体積抵抗率は１０１２Ω・ｃｍであった。
【００２９】
【比較例３】
エタノールで脱脂洗浄したポリベンザゾール短繊維（東洋紡績株式会社製 ザイロンＨＭ：直径１１μｍ、長さ５０μｍ）４重量部と、接着性高分子として付加型の液状シリコーンゴム１００重量部を混合し、真空脱泡して熱伝導性接着剤を調製した。テフロンコーティングしたアルミニウム製の厚み０．５ｍｍ、縦２０ｍｍ、横２０ｍｍの板状の金型内に充填して磁場を印加せずに加熱硬化させた。硬化物の熱伝導率は０．２Ｗ／ｍ・Ｋ、体積抵抗率は１０１２Ω・ｃｍであった。
【００３０】
【実施例１３】
図５（１）〜（５）に本実施例における製造方法を示す。プリント基板１に実装したボールグリッドアレイ型の半導体パッケージ２上に、本発明の実施例２のシリコーン系熱伝導性接着剤３をディスペンサーで塗布した（図５（２））。図５（３）のように熱伝導性接着剤３の上部に放熱器１を配置して加圧し、図５（４）のように磁束密度６テスラの磁石１１のＮ極とＳ極を対向させた磁場雰囲気でポリベンザゾール短繊維を配向させ、熱伝導性接着剤３を加熱硬化させて電子部品（図５（５））を作製した。
装置に通電して６分後の熱抵抗を測定した結果、０．３１℃／Ｗであった。
硬化した熱伝導性接着剤中のポリベンザゾール短繊維は図５（５）のように厚み方向に揃って配向していた。
【００３１】
【比較例４】
実施例１３と同様に、プリント基板に実装したボールグリッドアレイ型の半導体パッケージ上に表１の比較例３のシリコーン系熱伝導性接着剤を塗布した。熱伝導性接着剤の上部に放熱器４を配置して加圧し、熱伝導性接着剤を加熱硬化させて電子部品を製造した。
実施例１３と同様に、装置に通電して６分後の熱抵抗を測定した結果、０．４３℃／Ｗであった。
硬化した熱伝導性接着剤中のポリベンザゾール短繊維は図６のようにランダムに分散していた。
【００３２】
【実施例１４】
図７（１）〜（５）に本実施例における製造方法を示す。リードフレーム６のダイパッド７上に、本発明の実施例１のエポキシ系熱伝導性接着剤３をスクリーン印刷した（図７（１））。図７（２）のように熱伝導性接着剤３の上部に半導体チップ８を配置して加圧し、図７（３）のように磁束密度６テスラの磁石１１のＮ極とＳ極を対向させた磁場雰囲気でポリベンザゾール短繊維を配向させ、熱伝導性接着剤３を加熱硬化させた。さらにボンディングワイヤー９で半導体チップ８の電極部とリードフレーム１１のリード部を電気的に接続し（図７（４））、エポキシ系封止剤１０でトランスファーモールドして電子部品（図７（５））を製造した。
装置に通電して６分後の熱抵抗を測定した結果、０．３７℃／Ｗであった。
硬化した熱伝導性接着剤中のポリベンザゾール短繊維は図７（５）のように厚み方向に揃って配向していた。
【００３３】
【比較例５】
実施例１４と同様に、リードフレームのダイパッド上に表１の比較例２のエポキシ系熱伝導性接着剤をスクリーン印刷した。熱伝導性接着剤の上部に半導体チップを配置して加圧し、熱伝導性接着剤を加熱硬化させて電子部品を製造した。
実施例１４と同様に、装置に通電して６分後の熱抵抗を測定した結果、０．４４℃／Ｗであった。
硬化した熱伝導性接着剤中のポリベンザゾール短繊維は図８のようにランダムに分散していた。
【００３４】
【発明の効果】
表１に記したように、本発明のポリベンザゾール短繊維と接着性高分子から構成される熱伝導性接着剤を使用して熱伝導性と電気絶縁性にすぐれる熱伝導性接着剤を得ることができる。また、本発明の接着方法によって、発熱量が大きい半導体パッケージとヒートシンクなどの放熱器との接着、あるいは半導体チップとダイパッド部との接着に応用することが可能になり、熱抵抗が小さく放熱特性にすぐれる有用な電子部品を提供することができる。
【表１】

Figure 0004709339

【図面の簡単な説明】
【図１】本発明の熱伝導性接着剤を使用した電子部品の例
【図２】本発明の熱伝導性接着剤を使用した電子部品の例
【図３】本発明の熱伝導性接着剤を使用した電子部品の例
【図４】本発明の熱伝導性接着剤を使用した電子部品の例
【図５】図１の本発明の電子部品を製造する方法およびポリベンザゾール短繊維の配向状態を示す概略図
【図６】従来の配向していないポリベンザゾール短繊維を含む熱伝導性接着剤を使用した電子部品の例
【図７】図４の本発明の電子部品を製造する方法およびポリベンザゾール短繊維の配向状態を示す概略図
【図８】従来の配向していないポリベンザゾール短繊維を含む熱伝導性接着剤を使用した電子部品の例
【符号の説明】
１ プリント基板
２ 電子部品
３ 熱伝導性接着剤
４ 放熱器
５ ヒートシンク
６ リードフレーム
７ ダイパッド
８ 半導体チップ
９ ボンディングワイヤー
１０ 封止剤
１１ 磁石
１２ 配向しているポリベンザゾール短繊維
１３ 配向していないポリベンザゾール短繊維[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat conductive adhesive and a bonding method that require high heat conductivity, and an electronic component. More specifically, the present invention relates to a thermally conductive adhesive and bonding method for effectively dissipating heat generated from components such as semiconductor elements, power supplies, and light sources used in electrical products, and an electronic component having excellent heat dissipation.
[0002]
[Prior art]
Conventionally, a heat conductive adhesive using an adhesive polymer as a matrix has been used for the purpose of bonding a heat generating semiconductor element or electronic component to a heat transfer member for radiating heat. These adhesives have high thermal conductivity metals and alloys, compounds such as silver, copper, gold, aluminum, nickel, or aluminum oxide, magnesium oxide, silicon oxide, boron nitride, A powdery filler made of ceramics such as aluminum nitride, silicon nitride, and silicon carbide, and a heat conductive filler in the form of particles and fibers such as carbon black and diamond are blended.
[0003]
As a heat conductive filler, a heat conductive adhesive for blending a carbon material into an adhesive polymer is known. For example, in JP-A 63-305520, a die bond material filled with carbon-based fine powder or carbon fiber is known. JP-A-6-212137 proposes an adhesive material filled with carbon fibers having a three-dimensional structure using a mesophase pitch as a base material. Japanese Patent Laid-Open No. 9-324127 is a die bond material for semiconductor elements using graphite obtained by heat-treating a specific polymer material.
[0004]
Furthermore, according to JP-A-5-209157 and JP-A-6-299129, the structure of carbon fiber or metal fiber to be contained is specified as a lump shape, a string shape, or a woven fabric or non-woven fabric shape. Discloses an adhesive for electronic devices with further improved heat dissipation characteristics.
On the other hand, according to Japanese Patent Application Laid-Open Nos. Sho 62-194653 and 63-62762, an adhesive containing magnetic powder such as nickel is oriented in the thickness direction in a magnetic field to improve thermal conductivity. A method is disclosed.
[0005]
[Problems to be solved by the invention]
However, the above-mentioned JP-A-63-305520, JP-A-6-212137, JP-A-9-324127, JP-A-5-209157, JP-A-6-299129, JP-A-62-2. The adhesives and bonding methods disclosed in Japanese Patent No. 194653 and Japanese Patent Laid-Open No. 63-62762 require electrical insulation in order to blend carbon materials, metal fibers, magnetic powders, etc. with high conductivity. It could not be applied to other applications.
[0006]
JP-A-2-45581 uses as a vibration-damping adhesive layer of a vibration-damping composite metal plate in which electrically short fibers such as rayon, vinylon, cotton yarn, polyester fiber and polyamide fiber are blended as organic short fibers. It is what However, the thermal conductivity was not improved.
[0007]
In other words, because no adhesive has been developed that has good electrical insulation and high heat conduction characteristics, electrochemical migration is accelerated due to a large amount of heat generated from electronic components such as semiconductor elements, wiring, pads, etc. Corrosion of parts has been accelerated, cracks have occurred in the component material due to the generated thermal stress, and various troubles have occurred that impair the life of the electronic component due to separation of the interface of the joint part of the component material .
[0008]
On the other hand, in the thermally conductive adhesive disclosed in Japanese Patent Application No. 11-85107 by the present applicant, a diamagnetic filler having a thermal conductivity of 20 W / m · K or more is blended in the adhesive. Polybenzazole short fibers were not considered as a filler.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an electrically insulating thermally conductive adhesive and an adhesion method that effectively dissipate heat generated from components such as semiconductor elements, power supplies, and light sources used in electrical products. In addition, an electronic component having excellent heat dissipation characteristics is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
That is, this invention is a heat conductive adhesive characterized by mix | blending polybenzazole short fiber and adhesive polymer. Furthermore, the present invention provides a polybenzazole short fiber in a thermally conductive adhesive by an external magnetic field with a thermally conductive adhesive formed by blending polybenzazole short fibers and an adhesive polymer interposed between adherends. The bonding method is characterized in that the fibers are bonded in a state of being oriented in a certain direction. Furthermore, the present invention interposes a heat conductive adhesive comprising a polybenzazole short fiber and an adhesive polymer between the heat generating element and the heat transfer member, and the heat conductive adhesive in the heat conductive adhesive by an external magnetic field. An electronic component characterized by a structure in which polybenzazole short fibers are bonded in a state of being oriented in a certain direction.
[0011]
The polybenzazole short fiber used in the present invention is a short fiber composed of a polybenzazole polymer. Polybenzazole (PBZ) is a polybenzoxazole homopolymer (PBO), a polybenzothiazole homopolymer (PBT). ) And their PBO, PBT random copolymer, sequential copolymer, block copolymer or graft copolymer. Although the length, diameter, cross-sectional shape and the like of the polybenzazole short fiber are not specified, the length of the polybenzazole short fiber is preferably 1 mm or less. Use of a short polybenzazole fiber longer than 1 mm is not preferable because it is difficult to uniformly disperse in the adhesive polymer, and the viscosity as the adhesive composition is increased to deteriorate the workability. More preferably, the length of the polybenzazole short fiber is 0.8 mm or less, more preferably 0.5 mm or less, and further preferably 0.2 mm or less.
[0012]
In addition to the normal short fiber shape, the polybenzazole short fiber may be a whisker-shaped or pulp-shaped polybenzazole short fiber. The amount of the polybenzazole short fiber to be contained in the heat conductive adhesive of the present invention is preferably 0.1 to 50 parts by weight with respect to 100 parts by weight of the adhesive polymer. If the amount is less than 0.1 parts by weight, the effect of improving the thermal conductivity is small. If the amount exceeds 50 parts by weight, the viscosity of the adhesive composition increases, the fluidity is impaired, and the workability deteriorates. It is not suitable because air bubbles are unavoidable. The addition amount of the polybenzazole short fiber is more preferably 0.5 to 30 parts by weight, and further preferably 1 to 20 parts by weight.
[0013]
Polybenzazole staple fibers can be produced by a method of cutting polybenzazole filaments into a certain length, and can be easily obtained as a commercial product (trade name = Zylon, manufactured by Toyobo Co., Ltd.). it can. The tensile strength of the polybenzazole short fiber is preferably 4 GPa or more and the initial tensile elastic modulus is 140 GPa or more. By using the polybenzazole short fiber whose tensile strength and initial tensile elastic modulus are within this range, the heat conductive adhesive and the electronic component of the present invention can exhibit high heat conductivity.
[0014]
As fibers other than short polybenzazole fibers, a small amount of organic fiber such as aramid fiber, polyester fiber, aliphatic polyamide fiber, vinylon fiber, natural fiber, carbon fiber, metal fiber, ceramic fiber, and these fibers are combined. It is also possible to mix short fibers and long fibers made of composite fibers, or a small amount of those woven or non-woven fabrics. However, the heat-conductive adhesive of the present invention is also characterized by excellent electrical insulation, and it is preferable that carbon fibers, metal fibers, metal-coated fibers, etc. with high conductivity are not mixed as much as possible.
[0015]
Adhesive polymers that can be used as matrices include epoxy, polyimide, acrylic, polyvinyl acetate and other vinyl, urethane, silicone, olefin, polyamide, polyamideimide, phenol, amino, and bis. Maleimides, polyimide silicones, saturated and unsaturated polyesters, diallyl phthalates, ureas, melamines, alkyds, benzocyclobutenes, synthetic rubbers such as polybutadiene, chloroprene rubber, nitrile rubber, natural rubbers, styrene A liquid or solid material made of a known resin such as a thermoplastic elastomer and rubber is preferred.
[0016]
As for the curing form, any known curing polymer such as thermosetting, thermoplastic, ultraviolet or visible light curable, room temperature curable, and moisture curable can be used. Among them, at least one kind of adhesive selected from epoxy, polyimide, acrylic, urethane, or silicone, which has good adhesion to various metals and ceramics, various plastics, rubbers, and elastomers as materials constituting electronic components. A functional polymer is preferred.
[0017]
In addition, for the purpose of surface treatment of polybenzazole short fibers, the surface of polybenzazole short fibers is pre-degreased and washed, and activation treatment such as ultraviolet irradiation, corona discharge treatment, plasma treatment, flame treatment or ion implantation. It is preferable to apply. Furthermore, it is possible to improve the wettability with the adhesive polymer or improve the filling property by treating with a known coupling agent or sizing agent such as silane, titanium or aluminum. Further, the heat conductive adhesive of the present invention includes a thixotropic agent, a dispersant, a curing agent, a curing accelerator, a retarder, a tackifier, a plasticizer, a flame retardant, an antioxidant, a stabilizer, and a colorant. Such known additives can be blended.
[0018]
Furthermore, it is used in conventional heat conductive adhesives such as powdered metals and ceramics, specifically silver, copper, gold, aluminum oxide, magnesium oxide, aluminum nitride, silicon carbide, and metal-coated resins. A filler or the like can be used in combination as appropriate. However, the heat conductive adhesive of the present invention is also excellent in electrical insulation, and it is preferable not to mix fillers such as highly conductive metals as much as possible.
Further, in order to reduce the viscosity of the adhesive, it is effective to improve workability by adding a volatile organic solvent or a reactive plasticizer.
[0019]
In the bonding method of the present invention, a thermally conductive adhesive comprising a polybenzazole short fiber and an adhesive polymer is interposed between adherends. The bonding method is characterized in that the sol short fibers are bonded in a state of being oriented in a certain direction.
By orienting the polybenzazole short fibers in the adhesive along the magnetic field lines by an external magnetic field, the thermal conductivity of the oriented polybenzazole short fibers is utilized to improve the thermal conductivity of the adhesive. be able to. In order to align the polybenzazole short fibers so as to stand in the gap direction of the adherend, that is, in the adhesive thickness direction, the N pole and S pole of the permanent magnet or electromagnet are opposed to each other in the thickness direction, and the direction of the lines of magnetic force is desired. It is installed so as to correspond to the orientation direction of the short polybenzazole fibers.
[0020]
On the other hand, in order to improve the thermal conductivity in the in-plane direction of the adhesive, the polybenzazole short fibers are moved in the in-plane direction if the N pole and S pole of the magnet are opposed to each other in a direction perpendicular to the thickness direction. It can be aligned and aligned. Alternatively, the polybenzazole short fibers can be aligned in the in-plane direction even when the N-pole and N-pole of the magnet or the S-pole and S-pole are opposed to each other in the thickness direction. Further, the magnets do not necessarily have to be opposed to both sides, and the polybenzazole short fibers in the adhesive can be oriented by a magnet arranged only on one side.
[0021]
The magnetic field generating means used as the external magnetic field may be a permanent magnet or an electromagnet, but a practical polybenzazole short fiber orientation can be achieved when the magnetic flux density is in the range of 0.05 Tesla to 30 Tesla. In addition, since the present invention uses the very weak anisotropic magnetic susceptibility of polybenzazole short fibers as magnetism, the polybenzazole short fibers are sufficiently oriented using a higher magnetic field of 1 Tesla or higher. It is necessary to bond the adherend by solidifying the adhesive polymer of the matrix by thermosetting reaction or cooling.
For reference, the results of the measurement of the anisotropic magnetic susceptibility χ a of polybenzazole fiber (Toyobo Co., Ltd., Zylon HM) by the inventors using a magnetic anisotropic torque meter (Tamagawa Seisakusho Co., Ltd.) were 6 1 × 10 −7 .
[0022]
The heat conductive adhesive of the present invention can be produced by mixing a predetermined amount of polybenzazole short fibers in an adhesive polymer and uniformly dispersing the mixture. When mixing or kneading to disperse, it is preferable to add a known step of removing bubbles mixed under reduced pressure or pressure.
A heat conductive adhesive comprising the polybenzazole short fiber of the present invention and an adhesive polymer is interposed between the heat generating element and the heat transfer member, and the polybenzazole short fiber in the heat conductive adhesive is bonded by an external magnetic field. The electronic components of the present invention as shown in FIGS. 5 (6) and 7 (6) can be manufactured by bonding them in a state oriented in a certain direction.
[0023]
In addition, a heat conductive adhesive can be interposed between adherends by well-known methods, such as screen printing, pad printing, dispenser application | coating, potting, and spray coating. Examples of elements that generate heat include semiconductor elements, power supplies, and light sources. Examples of heat transfer members include ordinary radiators and coolers, heat sinks, heat spreaders, die pads, printed boards, cooling fans, heat pipes, and housings. .
[0024]
FIG. 1 shows an example of an electronic component using the thermally conductive adhesive of the present invention for bonding the ball grid array type semiconductor package 2 and the radiator 4.
FIG. 2 shows an example of an electronic component using the thermally conductive adhesive of the present invention for bonding the chip size type semiconductor package 2 and the printed circuit board 1.
FIG. 3 shows an example of an electronic component using the thermally conductive adhesive of the present invention for bonding the pin grid array type semiconductor package 2 and the heat sink 5.
FIG. 4 shows an example of an electronic component using the thermally conductive adhesive of the present invention for bonding the semiconductor chip 8 and the die pad 7.
Hereinafter, the present invention will be described in more detail with reference to examples. Hereinafter, the thermal conductivity was measured according to the laser flash method, and the volume resistivity was measured according to JIS-K6911.
[0025]
[Example 1]
4 parts by weight of polybenzazole short fiber (Toyobo Co., Ltd. Zylon HM: diameter 11 μm, length 50 μm) degreased and washed with ethanol and 100 parts by weight of bisphenol F type epoxy resin containing an amine-based curing agent as an adhesive polymer Were mixed and vacuum degassed to prepare a heat conductive adhesive. A Teflon-coated aluminum plate with a thickness of 0.5 mm, length of 20 mm, and width of 20 mm is filled with the prepared heat conductive adhesive, and the N pole and S pole of a magnet with a magnetic flux density of 6 Tesla in the thickness direction. The polybenzazole short fibers were oriented in a magnetic field atmosphere facing each other and cured by heating. The cured product had a thermal conductivity of 1.4 W / m · K and a volume resistivity of 10 12 Ω · cm.
[0026]
Examples 2 to 12
In the same manner as in Example 1, a heat conductive adhesive composed of polybenzazole short fibers and an adhesive polymer having the composition shown in Table 1 was prepared and made of Teflon-coated aluminum having a thickness of 0.5 mm, a length of 20 mm, and a width. Filled in a 20 mm plate-shaped mold, oriented polybenzazole short fibers in a magnetic field atmosphere of magnetic flux density described in Table 1 where the north and south poles of the magnet face each other in the thickness direction, and heat cured. . Table 1 shows the measured thermal conductivity and volume resistivity of the cured product. In addition, the polybenzazole short fiber from which the length used in Table 1 differs was produced by cut | disconnecting Zylon HM (diameter 11 micrometers) made by Toyobo Co., Ltd. The materials used as the adhesive polymer are bisphenol F type epoxy resin containing amine curing agent, epoxy is addition type liquid silicone rubber, polyimide is heat curing type liquid polyimide, acrylic is cyanoacrylate type adhesive. is there.
[0027]
[Comparative Example 1]
Fill and heat 100 parts by weight of an adhesive polymer made of bisphenol F type epoxy resin containing an amine-based curing agent into a Teflon-coated aluminum plate having a thickness of 0.5 mm, a length of 20 mm, and a width of 20 mm. Cured. The cured product had a thermal conductivity of 0.2 W / m · K and a volume resistivity of 10 12 Ω · cm.
[0028]
[Comparative Example 2]
4 parts by weight of polybenzazole short fiber (Toyobo Co., Ltd. Zylon HM: diameter 11 μm, length 50 μm) degreased and washed with ethanol and 100 parts by weight of bisphenol F type epoxy resin containing an amine-based curing agent as an adhesive polymer Were mixed and vacuum degassed to prepare a heat conductive adhesive. A Teflon-coated aluminum plate having a thickness of 0.5 mm, a length of 20 mm, and a width of 20 mm was filled and cured by heating without applying a magnetic field. The cured product had a thermal conductivity of 0.3 W / m · K and a volume resistivity of 10 12 Ω · cm.
[0029]
[Comparative Example 3]
4 parts by weight of polybenzazole short fibers (Toyobo Co., Ltd., Zylon HM: diameter 11 μm, length 50 μm) degreased and washed with ethanol are mixed with 100 parts by weight of addition-type liquid silicone rubber as an adhesive polymer, and vacuum mixed. A heat conductive adhesive was prepared by defoaming. A Teflon-coated aluminum plate having a thickness of 0.5 mm, a length of 20 mm, and a width of 20 mm was filled and cured by heating without applying a magnetic field. The cured product had a thermal conductivity of 0.2 W / m · K and a volume resistivity of 10 12 Ω · cm.
[0030]
Example 13
The manufacturing method in a present Example is shown to FIG. 5 (1)-(5). On the ball grid array type semiconductor package 2 mounted on the printed circuit board 1, the silicone-based thermally conductive adhesive 3 of Example 2 of the present invention was applied with a dispenser (FIG. 5 (2)). As shown in FIG. 5 (3), the radiator 1 is placed on the upper part of the heat conductive adhesive 3 and pressed, and the N pole and the S pole of the magnet 11 having a magnetic flux density of 6 Tesla are opposed as shown in FIG. 5 (4). The polybenzazole short fibers were oriented in the magnetic field atmosphere, and the heat conductive adhesive 3 was cured by heating to produce an electronic component (FIG. 5 (5)).
It was 0.31 degreeC / W as a result of measuring the thermal resistance 6 minutes after supplying with electricity to an apparatus.
The polybenzazole short fibers in the cured thermally conductive adhesive were aligned in the thickness direction as shown in FIG. 5 (5).
[0031]
[Comparative Example 4]
Similarly to Example 13, the silicone-based thermally conductive adhesive of Comparative Example 3 in Table 1 was applied onto a ball grid array type semiconductor package mounted on a printed circuit board. An electronic component was manufactured by disposing and pressurizing the radiator 4 on the upper part of the heat conductive adhesive and heating and curing the heat conductive adhesive.
As in Example 13, the device was energized and the thermal resistance measured 6 minutes later was 0.43 ° C./W.
The polybenzazole short fibers in the cured thermally conductive adhesive were randomly dispersed as shown in FIG.
[0032]
Example 14
7 (1) to 7 (5) show the manufacturing method in this example. On the die pad 7 of the lead frame 6, the epoxy heat conductive adhesive 3 of Example 1 of the present invention was screen printed (FIG. 7 (1)). As shown in FIG. 7 (2), the semiconductor chip 8 is placed on the heat conductive adhesive 3 and pressed, and the N pole and S pole of the magnet 11 having a magnetic flux density of 6 Tesla are opposed to each other as shown in FIG. 7 (3). The polybenzazole short fibers were oriented in a magnetic field atmosphere, and the heat conductive adhesive 3 was cured by heating. Furthermore, the electrode part of the semiconductor chip 8 and the lead part of the lead frame 11 are electrically connected by the bonding wire 9 (FIG. 7 (4)), and transfer molded with the epoxy-based sealant 10 to form an electronic component (FIG. 7 (5) )) Was manufactured.
It was 0.37 degreeC / W as a result of measuring the thermal resistance 6 minutes after supplying with electricity to an apparatus.
The polybenzazole short fibers in the cured heat conductive adhesive were aligned in the thickness direction as shown in FIG. 7 (5).
[0033]
[Comparative Example 5]
In the same manner as in Example 14, the epoxy heat conductive adhesive of Comparative Example 2 in Table 1 was screen-printed on the die pad of the lead frame. An electronic component was manufactured by placing a semiconductor chip on top of the thermally conductive adhesive and applying pressure thereto, and heat-curing the thermally conductive adhesive.
As in Example 14, the device was energized and the thermal resistance measured 6 minutes later was 0.44 ° C./W.
The polybenzazole short fibers in the cured heat conductive adhesive were randomly dispersed as shown in FIG.
[0034]
【The invention's effect】
As shown in Table 1, using a heat conductive adhesive composed of the polybenzazole short fiber of the present invention and an adhesive polymer, a heat conductive adhesive excellent in heat conductivity and electrical insulation is obtained. Obtainable. In addition, the bonding method of the present invention can be applied to bonding a semiconductor package with a large amount of heat generation to a heat sink such as a heat sink, or bonding between a semiconductor chip and a die pad portion, and has low heat resistance and heat dissipation characteristics. It is possible to provide excellent and useful electronic components.
[Table 1]
Figure 0004709339

[Brief description of the drawings]
1 is an example of an electronic component using the heat conductive adhesive of the present invention. FIG. 2 is an example of an electronic component using the heat conductive adhesive of the present invention. FIG. 3 is a heat conductive adhesive of the present invention. Fig. 4 shows an example of an electronic component using the thermally conductive adhesive of the present invention. Fig. 5 shows a method for manufacturing the electronic component of the present invention shown in Fig. 1 and orientation of polybenzazole short fibers. FIG. 6 is a schematic diagram showing a state. FIG. 6 is an example of an electronic component using a conventional heat conductive adhesive containing non-oriented polybenzazole short fibers. FIG. 7 is a method of manufacturing the electronic component of the present invention shown in FIG. And FIG. 8 is a schematic diagram showing the orientation state of polybenzazole short fibers. FIG. 8 is an example of an electronic component using a conventional heat conductive adhesive containing non-oriented polybenzazole short fibers.
DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Electronic component 3 Thermal conductive adhesive 4 Radiator 5 Heat sink 6 Lead frame 7 Die pad 8 Semiconductor chip 9 Bonding wire 10 Sealant 11 Magnet 12 Oriented polybenzazole short fiber 13 Unoriented poly Benzazole staple fiber

Claims (6)

被着体間に、ポリベンザゾール短繊維と接着性高分子とを配合してなる熱伝導性接着剤を介在させ、外部磁場によって熱伝導性接着剤中のポリベンザゾール短繊維を一定方向に配向させた状態で接着させることを特徴とする接着方法。  A thermal conductive adhesive composed of polybenzazole short fibers and an adhesive polymer is interposed between the adherends, and the polybenzazole short fibers in the thermal conductive adhesive are oriented in a certain direction by an external magnetic field. A bonding method comprising bonding in an oriented state. 熱伝導性接着剤が、接着性高分子１００重量部に対してポリベンザゾール短繊維０．１〜５０重量部である請求項１に記載の接着方法。The bonding method according to claim 1 , wherein the heat conductive adhesive is 0.1 to 50 parts by weight of polybenzazole short fibers with respect to 100 parts by weight of the adhesive polymer. 接着性高分子が、エポキシ系、ポリイミド系、アクリル系、ウレタン系あるいはシリコーン系より選ばれる少なくとも１種である請求項１あるいは２に記載の接着方法。The adhesion method according to claim 1 or 2 , wherein the adhesive polymer is at least one selected from the group consisting of epoxy, polyimide, acrylic, urethane, and silicone. 発熱する素子と伝熱部材間に、ポリベンザゾール短繊維と接着性高分子とを配合してなる熱伝導性接着剤を介在させ、外部磁場によって熱伝導性接着剤中のポリベンザゾール短繊維を一定方向に配向させた状態で接着させた構造を特徴とする電子部品。  A polybenzazole short fiber in a heat conductive adhesive is formed by an external magnetic field by interposing a heat conductive adhesive comprising a polybenzazole short fiber and an adhesive polymer between the heat generating element and the heat transfer member. An electronic component characterized by a structure in which the materials are bonded in a state in which they are oriented in a certain direction. 熱伝導性接着剤が、接着性高分子１００重量部に対してポリベンザゾール短繊維０．１〜５０重量部である請求項４に記載の電子部品。The electronic component according to claim 4 , wherein the heat conductive adhesive is 0.1 to 50 parts by weight of polybenzazole short fibers with respect to 100 parts by weight of the adhesive polymer. 接着性高分子が、エポキシ系、ポリイミド系、アクリル系、ウレタン系あるいはシリコーン系より選ばれる少なくとも１種である請求項４あるいは５に記載の電子部品。6. The electronic component according to claim 4 , wherein the adhesive polymer is at least one selected from an epoxy system, a polyimide system, an acrylic system, a urethane system, and a silicone system.
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