JP4014484B2 - Heat-dissipating resin sheet - Google Patents

Description

（式（１）中、Ｒは、メチル基、エチル基を示す。）
【００１３】
【化６】

（式（２）中、Ｒ₁は、メチル基、エチル基を示し、Ｒ₂は、水素原子、メチル基を示す）。
【００１４】
【化７】

（式（３）中、Ｒ₃は、メチル基、エチル基を示し、Ｒ₄は、水素原子、メチル基を示す）。
【００１５】
【化８】

（式（４）中、Ｒ₅はメチル基、エチル基を示し、Ｒ₆はＣ８〜Ｃ２０のアルキル基を示す。）
【００１６】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明に使用される炭素原子数２〜１２のα−オレフィンとしては、例えば、エチレン、プロピレン、１−ブテン、１−ペンテン、３−メチル−１−ブテン、１−ヘキセン、４−メチルー１−ペンテン、３−メチルー１−ペンテン、１−ペンテン、１−オクテン、１−デセン、１−ドデセン等が挙げられる。これらのα―オレフィン共重合体の樹脂成分における含有割合は、通常、３０重量％以上、好ましくは５０重量％以上である。
【００１７】
上記炭素原子数２〜１２のα−オレフィンは、少なくとも2種のα-オレフィンを主成分として、α-オレフィン共重合体を形成する。その組合せとしてエチレン、１−ブテン、および炭素原子数５〜１２のα−オレフィンの３成分からなる共重合体、エチレン、プロピレンおよび炭素原子数５〜１２のα−オレフィンの３成分からなる共重合体、プロピレン、１−ブテンおよび炭素原子数５〜１２のα−オレフィンの３成分からなる共重合体等が挙げられるが、その中でもプロピレン、１−ブテンおよび炭素原子数５〜１２のα−オレフィンの３成分からなる共重合体を主材とする樹脂成分が好ましい。
【００１８】
炭素原子数５〜１２のα−オレフィンとしては、１−ペンテン、３−メチル−１−ブテン、１−ヘキセン、４−メチルー１−ペンテン、３−メチルー１−ペンテン、１−ペンテン、１−オクテン、１−デセン、１−ドデセン等が挙げられるが、その中でも、４−メチル−１−ペンテンが好ましい。
【００１９】
α−オレフィン共重合体が、プロピレン、１−ブテンおよび炭素原子数５〜１２のα−オレフィンの３成分からなる共重合体を用いる場合、プロピレン１０〜８５モル％、１−ブテン３〜６０モル％および炭素原子数５〜１２のα−オレフィン１０〜８５モル％（但、すべての合計は１００％である）の組成を有する共重合体が、室温付近での粘着特性に優れる点で好ましく、さらに好ましくは、プロピレン１５〜７０モル％、１−ブテン５〜５０モル％および炭素原子数５〜１２のα−オレフィン１５〜７０モル％（但、すべての合計は１００％である）の組成を有する共重合体が好ましい。
【００２０】
プロピレン、１−ブテンおよび炭素原子数５〜１２のα−オレフィンの３成分からなる共重合体を主材とする場合、樹脂成分に占めるこの共重合体の含有割合は、樹脂成分中通常、３０重量％以上、好ましくは５０重量％以上である。
【００２１】
前記のほかに、その他のα-オレフィン共重合体を組み合わせて使用することも可能である。使用可能な好ましいα−オレフィン共重合体として、ａ）エチレン、プロピレンおよび１−ブテンから選ばれる少なくとも2種からなる共重合体、ｂ）エチレンとα−オレフィンのコオリゴマーおよびｃ）スチレン・ジエン系共重合体またはその水素添加物から選ばれる少なくとも1種以上の共重合体等が挙げられる。これらを組み合わせることにより、電子部品の作動温度に対する軟化温度の調整、および低温における初期粘着強度を向上させることが可能となる。
【００２２】
これらのα−オレフィン共重合体の中でも特に好ましいのは、ｃ）スチレン・ジエン系共重合体またはその水素添加物であり、その具体例としてはシェル化学株式会社製、商品名クレイトンＧに代表されるスチレン・エチレン・ブチレン・スチレンブロック共重合体（以下、ＳＥＢＳと略）、シェル化学株式会社製、製品名クレイトンＤに代表されるスチレン・イソプレン・スチレンブロック共重合体（以下、ＳＩＳと略）等が挙げられる。
【００２３】
ＳＥＢＳは、スチレン・ブタジエン・スチレンブロック共重合体を水素添加してなるものであり、スチレン系重合体ブロックを平均分子量に換算して１２０００〜１０００００程度、エチレン・ブチレン重合体ブロックを平均分子量に換算して１００００〜３０００００程度含むものである。この（Ｄ）ＳＥＢＳにおけるスチレン重合体ブロック／エチレン・ブチレン重合体ブロックの含有割合は、通常、重量比で５〜５０／５０〜９５であり、好ましくは１０〜３０／７０〜９０である。
【００２４】
ＳＩＳは、スチレン重合体ブロックとイソプレン重合体ブロックとを有するブロック共重合体であり、スチレン重合体ブロックを平均分子量に換算して１２０００〜１０００００程度、イソプレン重合体ブロックを平均分子量に換算して１００００〜３０００００程度含むものである。このＳＩＳにおけるスチレン重合体ブロック／イソプレン重合体ブロックの含有割合は、通常、重量比で５〜５０／５０〜９５であり、好ましくは１０〜３０／７０〜９０である。
尚、これらは単独ないし2種以上組合せて使用しても構わない。
【００２５】
上記ＳＥＢＳを用いる場合、ＳＥＢＳの樹脂成分に占める含有量は、好ましくは０〜５０重量％、更に好ましくは０〜４５重量％である。また、ＳＩＳを用いる場合、ＳＩＳ樹脂成分に占める含有量は、好ましくは０〜５０重量％、更に好ましくは、０〜３０重量％程度である。但し、前記ＳＥＢＳとＳＩＳを同時に用いる場合には、両者の合計量が樹脂成分に占める割合は、４５重量％以下となることが好ましい。
【００２６】
前記の（ａ）エチレン、プロピレンおよび１−ブテンから選ばれる少なくとも２種からなる共重合体の具体例として、エチレン・プロピレン共重合体、エチレン・１−ブテン共重合体、プロピレン・１−ブテン共重合体等が挙げられる。この（ａ）共重合体の具体例として、三井化学（株）から商品名：タフマーＰ（登録商標）、タフマーＳ（登録商標）、タフマーＡ（登録商標）、タフマーＸＲ（登録商標）等で市販されているものなどが挙げられる。
【００２７】
また、前記の（ｂ）エチレンとα−オレフィンのコオリゴマーは、エチレンとα−オレフィンとの低分子量共重合体であって、常温で液体状のものである。α−オレフィンとしては、例えば、プロピレン、１−ブテン、１−ペンテン、１−ヘキセン、１−オクテン、１−デセン、１−ドデセン、１−テトラデセン、１−ヘキサデセン、１−オクタデセン、４−メチル−１−ペンテン等の炭素数３〜２０のα−オレフィンが挙げられる。これらの中でも、炭素数３〜１４のα−オレフィンが好ましい。
【００２８】
この（ｂ）コオリゴマーは、下記式（１）：
【００２９】
【化９】

【００３０】
で表される構造単位を有するものである。前記式（１）中、ＲはＣn Ｈ2n+1（ｎは正の整数である）で表される基であり、ｘ、ｙおよびｐは正の整数である。
【００３１】
この（ｂ）コオリゴマーは、通常、数平均分子量が１００〜１００００の範囲のものであり、好ましくは数平均分子量が２００〜５０００の範囲のものである。また、この（ｂ）コオリゴマー中のエチレン含有量は、通常、３０〜７０モル％、好ましくは４０〜６０モル％である。
【００３２】
本発明のフィルムの粘着層の構成成分として、他のα−オレフィン共重合体として、前記（ｂ）コオリゴマーを用いる場合、この（ｂ）コオリゴマーの粘着層に占める含有割合は、通常、０〜２０重量％、好ましくは０〜１０重量％である。
【００３３】
本発明において、炭素原子数２〜１２のα−オレフィンから選ばれる少なくとも２種のα−オレフィンを主成分としてできるα-オレフィン共重合体は、そのＸ線回折による結晶化度の値が１０％以下であるものであり、十分な初期粘着強度を得る為には、結晶化度が５％以下であるものが好ましい。
【００３４】
Ｘ線回折による結晶化度の測定は、Ｓ，Ｌ．ＡＧＧＡＲＷＡＬ：Ｊ．Ｐｏｌｙｍｅｒ Ｓｃｉ．１８，１７，１９５５に記載の方法によって測定することができる。
【００３５】
本発明の放熱性樹脂シートを構成する熱伝導性充填材としては、無機窒化物、無機酸化物、金属から選ばれる一種又は二種以上のものであることあることが好ましく、具体例としては、窒化アルミ、窒化ホウ素等の無機窒化物、アルミナ、酸化ケイ素、酸化マグネシウム等の無機酸化物、金、銀、ニッケル、アルミニウム等の金属が挙げられる。なかでも絶縁性と高熱伝導を示す窒化アルミが好ましい。さらに好ましくは耐水性向上の為、表面処理された窒化アルミが挙げられる。これらは、1種或いは２種以上混合して使用しても構わない。
【００３６】
本発明においては、これらの熱伝導性充填材の表面を下記一般式（１）〜（４）で表される表面改質剤により被覆されることが重要である。
【００３７】
【化１０】

（式（１）中、Ｒは、メチル基、エチル基を示す。）
【００３８】
【化１１】

（式（２）中、Ｒ₁は、メチル基、エチル基を示し、Ｒ₂は、水素原子、メチル基を示す）。
【００３９】
【化１２】

（式（３）中、Ｒ₃は、メチル基、エチル基を示し、Ｒ₄は、水素原子、メチル基を示す）。
【００４０】
【化１３】

（式（４）中、Ｒ₅はメチル基、エチル基を示し、Ｒ₆はＣ８〜Ｃ２０のアルキル基を示す。）
【００４１】
式（４）中、Ｒ₆は、炭素数８から２０のアルキル基であり、好ましくは、炭素数１２〜１８のアルキル基であり、より好ましい具体例例としてはＣ１８のステアリル基が挙げられる。
【００４２】
一般式（１）〜（４）で表される化合物の具体的としては、ビニルトリメトキシシラン、ビニルトリエトキシシラン、３−メタクリロキシプロピルメチルジメトキシシラン、３−メタクリロキシプロピルトリメトキシシラン、３−メタクリロキシプロピルメチルジエトキシシラン、３−メタクリロキシプロピルトリエトキシシラン、３−アクリロキシプロピルメチルジメトキシシラン、３−アクリロキシプロピルトリメトキシシラン、３−アクリロキシプロピルメチルジエトキシシラン、３−アクリロキシプロピルトリエトキシシラン、ｎ−ラウリルトリメトキシシラン、ｎ−ミリスチルトリメトキシシラン、ｎ−セチルトリメトキシシラン、ｎ−ステアリルトリメトキシシラン、ｎ−ラウリルトリエトキシシラン、ｎ−ミリスチルトリエトキシシラン、ｎ−セチルトリエトキシシラン、ｎ−ステアリルトリエトキシシラン等が挙げられる。
好ましくは、ｎ−ステアリルトリメトキシシラン、ｎ−ステアリルトリエトキシシランである。尚、これらは一種又は二種以上混合して使用しても構わない。
【００４３】
これらの表面改質剤は熱伝導性充填材に直接処理されても、樹脂成分と熱伝導性充填材の配合時添加されても良い。直接処理する場合には、ミキサー中で熱伝導性充填材を攪拌しながら、表面改質剤の原液、アルコール溶液または水溶液を滴下または噴霧し、処理する方法、或いは表面改質剤の原液、アルコール溶液または水溶液中に熱伝導性充填材を浸漬し、その後ろ過、乾燥を行う事により処理を終了する方法が例として挙げられる。
【００４４】
表面改質剤の配合量は、直接処理の場合には、好ましくは熱伝導性充填材１００重量部に対し０．５〜２．０重量部であり、より好ましくは、０．７〜１．５重量部である。配合時添加の場合には、好ましくは、熱伝導性充填材１００重量部に対し１．０〜８．０重量部、より好ましくは、３．０〜６．０重量部である。このようにして表面改質された熱伝導性充填材は、シートの熱伝導率が１Ｗ／ｍＫ以上となるように配合される。好ましくは、樹脂成分と熱伝導性充填材の重量比率が５：９５〜５０：５０、より好ましい範囲は８：９２〜３０：７０である。
【００４５】
樹脂シートの熱伝導率は、１．０Ｗ／ｍＫ以上である方が好ましく、より好ましくは、１．５Ｗ／ｍＫ以上、５０Ｗ／ｍＫ以下である。１．０Ｗ／ｍＫ未満の場合は、熱伝導率が低く放熱の性能を十分に発揮する事が出来ない可能性がある。
【００４６】
本発明の放熱性樹脂シートの製造方法は、特に限定されるものではないが、通常、樹脂成分へ熱伝導性充填材が配合される。分散は、例えばリボンブレンダー、ヘンシェルミキサー、タンブラーミキサー、バンバリーミキサー、プラネタリミキサー、ニーダー、２本ロール等の方法を用いて行われ、Ｔ−ダイ成型、プレス成型、カレンダー成型等の方法にてシート化され、両面に保護の意味で離型フィルムが貼られる事により放熱性樹脂シートを得る。また、本発明の樹脂成分をトルエン、キシレン等の芳香族系溶剤、ｎ−ヘプタン、ｎ−オクタン等の炭化水素系溶剤の１種以上の溶剤に溶解し、熱伝導性充填材を配合、３本ロール、ボールミル、プラネタリミキサー、ヘンシェルミキサー等の混合装置を用いて分散し、離型フィルム上に塗布、乾燥して放熱性樹脂シートを得る事も出来る。ここで使用される離型フィルムとしては、特に限定はしないが通常、厚さ１０〜１００μｍ程度のポリエステルフィルム、ポリエチレンフィルム等が使用される。
【００４７】
このようにして得られた本発明の放熱性樹脂シートの厚さは、好ましくは１０μｍから１０００μｍ、より好ましくは５０μｍから５００μｍであり、両面に離型フィルムが貼られた形態で市場に供される.。
【００４８】
本発明の放熱性樹脂シートは、２３℃におけるアルミ板への初期粘着力は、５ｇ／２５ｍｍ以上であることが好ましく、５ｇ以下では、部品への仮固定が困難となり実装性に乏しくなる可能性がある。上限は特に限定されないが、通常、１０００ｇ／２５ｍｍ以下程度が再剥離を行う際の容易さと電子部品への損傷防止の面より好ましい。
【００４９】
また、更に本発明の放熱性樹脂シートは、２ｋｇ／ｃｍ²の加圧と６０℃の加温を１０日間与えた後の粘着力の上昇率が０〜３０％であることが好ましい。加圧、加熱後の粘着力上昇率が３０％より大きくとなるとリペアー時の剥離性が低下し、作業性の低下、部品の破損等の問題を生ずる場合がある。粘度が低下する場合は、電子部品との界面に微小な空気層が形成され熱抵抗が上がる問題を生ずる可能性が生じる。
【００５０】
【実施例】
次に、本発明を実施例により詳細に説明するが、本発明はこれにより何ら制限されるものではない。
（実施例１〜４）
各例においてプロピレン、１−ブテンおよび４−メチル−１−ペンテンを表１に示すモル％で含むα−オレフィン共重合体を樹脂成分とし、熱伝導性充填材を表１に示される重量比にて配合した。熱伝導性充填材は、窒化アルミ（三井化学株式会社製、ＭＡＮ２Ａと東洋アルミ株式会社製、ＵＭＳを重量比で３０：７０にて配合）を、表１に示される表面改質剤を直接処理する事により得た。配合後、リボンブレンダーにより混合分散し、Ｔ−ダイフィルム成型法により１８０℃の押出し温度にて厚さ１００μｍの放熱性樹脂シートを成型した。
【００５１】
樹脂成分のＸ線回折法（Ｓ，Ｌ．ＡＧＧＡＲＷＡＬ：Ｊ．Ｐｏｌｙｍｅｒ Ｓｃｉ．１８，１７，１９５５に準ずる）によって測定した結晶化度の結果を表１に示す。さらに得られた放熱性樹脂シートの初期粘着強度、加圧加熱粘着強度上昇率、熱伝導率および熱軟化温度について、下記の方法にて測定した結果についても表１に示す。
【００５２】
初期粘着強度の測定 ： ２ｍｍ厚のアルミ板と０．１ｍｍ厚のアルミ板を本発明の放熱性樹脂シートを介して貼り合わせ、１８０度引き剥がし法によって測定した。
加圧加温経時変化評価 ： 前記、初期粘着強度測定用サンプルを用いた。０．１ｍｍ厚のアルミ板上に厚さ３ｍｍのシリコンゴム板を重ね均一に２ｋｇ／ｃｍ²の圧力を６０℃に加温した加熱プレスで加えた状態で、２４０時間保持した後に取出し、２〜５時間内に１８０度引き剥がし法により粘着強度を測定した。粘着強度の上昇率は［（加圧加熱後の粘着強度−初期粘着強度）／初期粘着強度］×１００（％）にて算出した。
熱伝導率 ： 京都電子工業株式会社社製レーザーフラッシュ法熱伝導率測定装置により測定した。
熱軟化温度 ： レオメトリック・サイエンティフィック・エフ・イー社製粘弾性測定装置ＲＭＳ−８００を用いて、直径８ｍｍのパラレルプレートを使用し、プレート間のギャップを１．５ｍｍとし、試験片には８ｍｍφ×１．５ｍｍ(厚さ)の円板を用い、周波数ω=１００rad/secで、測定温度２０℃から１５０℃における貯蔵弾性率Ｇ'（Ｐａ）の変曲点により求めた。
【００５３】
実施例５
プロピレン５０モル％、１−ブテン２０モル％および４−メチル−１−ペンテン３０モル％からなるα−オレフィン共重合体をｎ−ヘプタンに溶解し、固形分５０ｗｔ％の溶液を作成した。本溶液２０重量部に対し、表面改質をされていない耐水性窒化アルミ粉（三井化学社製、ＭＡＮ−２Ａ ４００重量部、東洋アルミ社製、ＵＭＳ ８００重量部）を混合し、さらに３−メタクリロキシプロピルトリメトキシシラン４２重量部添加して、３本ロールにより分散した。分散物を５０μｍ厚のポリエチレンテレフタレートフィルム上に塗布乾燥し放熱性樹脂シートを得た。シートの厚さは２００μｍであった。本シートを測定した結果を表１に示す。
【００５４】
実施例６
プロピレン５０モル％、１−ブテン２０モル％および４−メチル−１−ペンテン３０モル％からなるα−オレフィン共重合体５０重量部、エチレン８０モル％、プロピレン２０モル％からなる共重合体２０重量部、ＳＥＢＳ（シェル化学株式会社製、Ｇ−１６５７）２０重量部およびＳＩＳ（日本合成ゴム株式会社製、ＳＩＳ５０００）１０重量部の混合物からなる樹脂成分１００重量部に、ビニルトリメトキシシランの１％水溶液中で処理し、ろ過、乾燥を行ったアルミナを１１００重量部を加え、実施例−１と同様にして放熱性樹脂シートを得た。本シートを測定した結果を表１に示す。
【００５５】
比較例１
エチレン・α−オレフィン・非共役ポリエンランダム共重合体ＥＰＴ−４０１０（三井化学株式会社製）２０重量部、エチレン・α−オレフィン共重合体としてルーカントＨＣ３０００Ｘ（三井化学株式会社製）３０重量部、α−オレフィンとして炭素原子数１７〜２５であるダイヤレン２０８(三菱化学株式会社製)３０モル％および炭素原子数３０〜４０であるダイヤレン３０(三菱化学株式会社製)２０重量部からなる樹脂成分１００重量部に無処理の窒化アルミ１１００重量部を実施例−１と同様に混合、シート化し放熱性樹脂シートを得た。本シートの測定した結果を表１に示す。
【００５６】
【表１】

【００５７】
【発明の効果】
本発明により、室温では固体であり仮固定に十分なる粘着性を示すとともに、長期の熱圧環境下に曝露された後もブリードによる汚染が無く、容易に再剥離可能であり、かつ電子部品の作動温度にて軟化し、界面の接触熱抵抗を低下させる、更に熱伝導性充填材と樹脂の濡れ性が改善される為と考えられ、分散性ひいては熱伝導性を向上させた放熱シートを提供することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-dissipating resin sheet having sufficient thermal conductivity and adhesiveness used for heat dissipation of electronic components.
[0002]
[Prior art]
In recent years, LSIs such as MPUs, memories, ASICs, and chip sets have been mounted with high density due to light and thin electronic devices, and power consumption has increased due to higher signal processing speeds associated with an increase in the amount of information. The amount of heat generated from these LSIs cannot be ignored for normal operation of the LSI, and the problem of heat dissipation is highlighted.
[0003]
Conventionally, heat generated from electronic components such as LSIs, transistors, diodes, and transformers is radiated into the air by heat radiating fins, casings, heat pipes, and the like called metal heat sinks. At this time, a thermally conductive member is used in order to reduce the thermal resistance at the interface between the electronic component and the radiating fin. As this member, a silicone rubber sheet or silicone grease in which a heat conductive filler such as alumina, silica, boron nitride or the like is dispersed is used.
[0004]
However, the silicone rubber sheet has insufficient adhesion at the interface due to its hardness, and the thermal resistance at the interface cannot be lowered sufficiently. In addition, silicone grease has a problem that it easily protrudes and deteriorates in appearance and characteristics, and further solidifies due to long-time heating and pressurization, causing problems when replacing electronic parts or heat radiating fins.
[0005]
Recently, in order to improve thermal conductivity, it is solid at normal temperature, softened or liquefied at electronic component operating temperature, obtaining good contact at the interface, and reducing heat resistance by thinning the thermal conductive layer Attempts have been made to solve with members. For example, a method using a thermoplastic silicone resin and a waxy silicone resin (see Patent Document 1), a method using a wax or a softening agent and a tackifier added to a thermoplastic resin or rubber (see Patent Document 2), and a wax (See Patent Document 3 and Patent Document 4), etc., but the wettability of the matrix resin component to the heat conductive filler is poor and an air layer is generated microscopically. It is conceivable and does not have sufficient thermal conductivity.
[0006]
In addition, low molecular weight waxes, softeners and tackifiers tend to bleed at high temperatures, cause electronic components to be contaminated and increase in heat resistance, increase in adhesive strength over time, and are difficult to remove in the re-peeling process. Has the problem of causing damage to the parts.
[0007]
There is also an example in which a solution is attempted using polyolefin (see Patent Document 5). However, the α-olefin, which is a heat softening component in the polyolefin used, has a total carbon atom number of 19 to 53, and if it is less than 19, there is a description that bleed occurs because it is liquid. Actually, an example of less than 19 is not illustrated. In addition, it is necessary to add a liquid polyolefin to give initial tackiness with 19 or more carbon atoms, and it has been found that the problem of bleeding occurs as described above, and it is desired to solve these problems. It was.
[0008]
[Patent Document 1]
JP 2000-327917 A [Patent Document 2]
JP 2000-336279 A [Patent Document 3]
JP 2001-291807 A [Patent Document 4]
JP 2002-20625 A [Patent Document 5]
Japanese Patent Laid-Open No. 2002-121332 [0009]
[Problems to be solved by the invention]
The problem of the present invention is that, as described above, it is solid at room temperature and exhibits sufficient tackiness for temporary fixation, and is not easily contaminated by bleed even after being exposed to a long-term hot-pressed environment and can be easily removed again. There is a heat dissipation sheet that softens at the operating temperature of electronic components, lowers the contact thermal resistance at the interface, and further improves the dispersibility and thus the thermal conductivity by improving the wettability of the thermally conductive filler and resin. Is to provide.
[0010]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the inventors have formulated a heat-dissipating resin sheet that satisfies the above conditions by blending a thermally conductive filler coated with a surface modifier having a specific structure. As a result, the present invention was completed.
[0011]
That is, the present invention comprises an α-olefin copolymer having a main component of at least two α-olefins selected from α-olefins having 2 to 12 carbon atoms and a crystallinity of 10% or less. It is related with the heat-radiating resin sheet characterized by mix | blending the heat conductive filler coat | covered with the surface modifier represented by following General formula (1)-(4) with the resin component to do.
[0012]
[Chemical formula 5]

(In formula (1), R represents a methyl group or an ethyl group.)
[0013]
[Chemical 6]

(In formula (2), R ₁ represents a methyl group or an ethyl group, and R ₂ represents a hydrogen atom or a methyl group).
[0014]
[Chemical 7]

(In formula (3), R ₃ represents a methyl group or an ethyl group, and R ₄ represents a hydrogen atom or a methyl group).
[0015]
[Chemical 8]

(In formula (4), R ₅ represents a methyl group or an ethyl group, and R ₆ represents a C8 to C20 alkyl group.)
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
Examples of the α-olefin having 2 to 12 carbon atoms used in the present invention include ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1- Examples include pentene, 3-methyl-1-pentene, 1-pentene, 1-octene, 1-decene, 1-dodecene and the like. The content of these α-olefin copolymers in the resin component is usually 30% by weight or more, preferably 50% by weight or more.
[0017]
The α-olefin having 2 to 12 carbon atoms forms an α-olefin copolymer having at least two kinds of α-olefins as main components. As a combination thereof, a copolymer composed of three components of ethylene, 1-butene, and an α-olefin having 5 to 12 carbon atoms, a copolymer composed of three components of ethylene, propylene, and an α-olefin having 5 to 12 carbon atoms And a copolymer composed of three components of a compound, propylene, 1-butene and an α-olefin having 5 to 12 carbon atoms, among them, propylene, 1-butene and an α-olefin having 5 to 12 carbon atoms. A resin component mainly composed of a copolymer consisting of these three components is preferred.
[0018]
Examples of the α-olefin having 5 to 12 carbon atoms include 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-pentene and 1-octene. , 1-decene, 1-dodecene and the like, among which 4-methyl-1-pentene is preferable.
[0019]
When the α-olefin copolymer is a copolymer composed of three components of propylene, 1-butene and an α-olefin having 5 to 12 carbon atoms, 10 to 85 mol% of propylene, 3 to 60 mol of 1-butene % And a copolymer having a composition of 10 to 85 mol% of an α-olefin having 5 to 12 carbon atoms (however, the total is 100%) is preferable in that it has excellent adhesive properties near room temperature, More preferably, the composition is 15 to 70 mol% of propylene, 5 to 50 mol% of 1-butene and 15 to 70 mol% of an α-olefin having 5 to 12 carbon atoms (however, the total is 100%). The copolymer which has is preferable.
[0020]
When the main component is a copolymer composed of three components of propylene, 1-butene and an α-olefin having 5 to 12 carbon atoms, the content of the copolymer in the resin component is usually 30 in the resin component. % By weight or more, preferably 50% by weight or more.
[0021]
In addition to the above, other α-olefin copolymers may be used in combination. Preferred α-olefin copolymers that can be used include: a) a copolymer comprising at least two selected from ethylene, propylene, and 1-butene; b) a co-oligomer of ethylene and α-olefin; and c) a styrene-diene system. Examples thereof include at least one copolymer selected from a copolymer or a hydrogenated product thereof. By combining these, it is possible to adjust the softening temperature with respect to the operating temperature of the electronic component and to improve the initial adhesive strength at low temperatures.
[0022]
Among these α-olefin copolymers, c) a styrene / diene copolymer or a hydrogenated product thereof is particularly preferable, and a specific example thereof is represented by the trade name Kraton G manufactured by Shell Chemical Co., Ltd. Styrene / Ethylene / Butylene / Styrene Block Copolymer (hereinafter abbreviated as SEBS), manufactured by Shell Chemical Co., Ltd., styrene / isoprene / styrene block copolymer represented by Clayton D (hereinafter abbreviated as SIS) Etc.
[0023]
SEBS is formed by hydrogenating a styrene / butadiene / styrene block copolymer. The styrene polymer block is converted to an average molecular weight of about 12,000 to 100,000, and the ethylene / butylene polymer block is converted to an average molecular weight. About 10,000 to 300,000. The content ratio of the styrene polymer block / ethylene / butylene polymer block in (D) SEBS is usually 5 to 50/50 to 95, preferably 10 to 30/70 to 90, in weight ratio.
[0024]
SIS is a block copolymer having a styrene polymer block and an isoprene polymer block. The styrene polymer block is converted to an average molecular weight of about 12,000 to 100,000, and the isoprene polymer block is converted to an average molecular weight of 10,000. About 300,000 is included. The content ratio of the styrene polymer block / isoprene polymer block in this SIS is usually 5 to 50/50 to 95, preferably 10 to 30/70 to 90, by weight.
These may be used alone or in combination of two or more.
[0025]
When SEBS is used, the content of SEBS in the resin component is preferably 0 to 50% by weight, more preferably 0 to 45% by weight. When SIS is used, the content of the SIS resin component is preferably 0 to 50% by weight, more preferably about 0 to 30% by weight. However, when the SEBS and SIS are used simultaneously, the ratio of the total amount of both to the resin component is preferably 45% by weight or less.
[0026]
Specific examples of the copolymer (a) comprising at least two kinds selected from ethylene, propylene and 1-butene include ethylene / propylene copolymer, ethylene / 1-butene copolymer, propylene / 1-butene copolymer. A polymer etc. are mentioned. As specific examples of the copolymer (a), Mitsui Chemicals Co., Ltd. has trade names: Tuffmer P (registered trademark), Tuffmer S (registered trademark), Tuffmer A (registered trademark), Tuffmer XR (registered trademark), etc. The thing marketed etc. are mentioned.
[0027]
The (b) co-oligomer of ethylene and α-olefin is a low molecular weight copolymer of ethylene and α-olefin and is liquid at room temperature. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 4-methyl- C3-C20 alpha olefins, such as 1-pentene, are mentioned. Among these, a C3-C14 alpha olefin is preferable.
[0028]
This (b) co-oligomer has the following formula (1):
[0029]
[Chemical 9]

[0030]
It has a structural unit represented by these. In the formula (1), R is a group represented by Cn H2n + 1 (n is a positive integer), and x, y and p are positive integers.
[0031]
This (b) co-oligomer usually has a number average molecular weight in the range of 100 to 10,000, preferably a number average molecular weight in the range of 200 to 5,000. Further, the ethylene content in this (b) co-oligomer is usually 30 to 70 mol%, preferably 40 to 60 mol%.
[0032]
When the (b) co-oligomer is used as another α-olefin copolymer as a constituent component of the adhesive layer of the film of the present invention, the content ratio of the (b) co-oligomer in the adhesive layer is usually 0. -20% by weight, preferably 0-10% by weight.
[0033]
In the present invention, an α-olefin copolymer comprising as a main component at least two α-olefins selected from α-olefins having 2 to 12 carbon atoms has a crystallinity value of 10% by X-ray diffraction. In order to obtain sufficient initial adhesive strength, those having a crystallinity of 5% or less are preferable.
[0034]
Measurement of crystallinity by X-ray diffraction is described in S, L. et al. AGGARWAL: J.A. Polymer Sci. 18, 17, 1955.
[0035]
The thermally conductive filler constituting the heat-dissipating resin sheet of the present invention is preferably one or two or more selected from inorganic nitrides, inorganic oxides, and metals. As a specific example, Examples thereof include inorganic nitrides such as aluminum nitride and boron nitride, inorganic oxides such as alumina, silicon oxide and magnesium oxide, and metals such as gold, silver, nickel and aluminum. Of these, aluminum nitride showing insulation and high thermal conductivity is preferable. More preferably, surface-treated aluminum nitride is used to improve water resistance. These may be used alone or in combination.
[0036]
In the present invention, it is important that the surface of these thermally conductive fillers is coated with a surface modifier represented by the following general formulas (1) to (4).
[0037]
Embedded image

(In formula (1), R represents a methyl group or an ethyl group.)
[0038]
Embedded image

(In formula (2), R ₁ represents a methyl group or an ethyl group, and R ₂ represents a hydrogen atom or a methyl group).
[0039]
Embedded image

(In formula (3), R ₃ represents a methyl group or an ethyl group, and R ₄ represents a hydrogen atom or a methyl group).
[0040]
Embedded image

(In formula (4), R ₅ represents a methyl group or an ethyl group, and R ₆ represents a C8 to C20 alkyl group.)
[0041]
In the formula (4), R ₆ is an alkyl group having 8 to 20 carbon atoms, preferably an alkyl group having 12 to 18 carbon atoms, and a more preferable specific example includes a C18 stearyl group.
[0042]
Specific examples of the compounds represented by the general formulas (1) to (4) include vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3- Methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldiethoxysilane, 3-acryloxypropyl Triethoxysilane, n-lauryltrimethoxysilane, n-myristyltrimethoxysilane, n-cetyltrimethoxysilane, n-stearyltrimethoxysilane, n-lauryltriethoxysilane, n-myristyl lithoate Shishiran, n- cetyl triethoxysilane, n- stearyl triethoxysilane and the like.
Preferred are n-stearyl trimethoxysilane and n-stearyl triethoxysilane. In addition, you may use these 1 type or in mixture of 2 or more types.
[0043]
These surface modifiers may be directly processed into the heat conductive filler, or may be added when the resin component and the heat conductive filler are blended. In the case of direct treatment, the surface modifying agent stock solution, alcohol solution or aqueous solution is dropped or sprayed while stirring the heat conductive filler in the mixer, or the surface modifying agent stock solution, alcohol An example is a method of ending the treatment by immersing the thermally conductive filler in a solution or an aqueous solution, followed by filtration and drying.
[0044]
In the case of direct treatment, the blending amount of the surface modifier is preferably 0.5 to 2.0 parts by weight, more preferably 0.7 to 1. part by weight based on 100 parts by weight of the heat conductive filler. 5 parts by weight. In the case of addition at the time of blending, the amount is preferably 1.0 to 8.0 parts by weight, more preferably 3.0 to 6.0 parts by weight with respect to 100 parts by weight of the heat conductive filler. The surface-modified thermal conductive filler is blended so that the thermal conductivity of the sheet is 1 W / mK or more. Preferably, the weight ratio of the resin component to the thermally conductive filler is 5:95 to 50:50, and a more preferable range is 8:92 to 30:70.
[0045]
The thermal conductivity of the resin sheet is preferably 1.0 W / mK or more, and more preferably 1.5 W / mK or more and 50 W / mK or less. If it is less than 1.0 W / mK, there is a possibility that the thermal conductivity is low and the performance of heat dissipation cannot be fully exhibited.
[0046]
Although the manufacturing method of the heat dissipation resin sheet of this invention is not specifically limited, Usually, a heat conductive filler is mix | blended with a resin component. Dispersion is performed using a method such as ribbon blender, Henschel mixer, tumbler mixer, Banbury mixer, planetary mixer, kneader, two rolls, etc., and formed into a sheet by a method such as T-die molding, press molding, calendar molding, etc. And a heat-radiating resin sheet is obtained by sticking a release film on both sides for protection. In addition, the resin component of the present invention is dissolved in one or more solvents such as aromatic solvents such as toluene and xylene, and hydrocarbon solvents such as n-heptane and n-octane, and a thermally conductive filler is blended. The heat-dissipating resin sheet can also be obtained by dispersing using a mixing device such as a roll, ball mill, planetary mixer, Henschel mixer, etc., and applying and drying on a release film. Although it does not specifically limit as a release film used here, Usually, a 10-100-micrometer-thick polyester film, a polyethylene film, etc. are used.
[0047]
The thickness of the heat-dissipating resin sheet of the present invention thus obtained is preferably 10 μm to 1000 μm, more preferably 50 μm to 500 μm, and is provided to the market in a form in which a release film is pasted on both sides. ..
[0048]
In the heat-dissipating resin sheet of the present invention, the initial adhesive strength to the aluminum plate at 23 ° C. is preferably 5 g / 25 mm or more, and if it is 5 g or less, it is difficult to temporarily fix the parts, and the mountability may be poor. There is. Although an upper limit is not specifically limited, Usually, about 1000 g / 25 mm or less is preferable from the surface of the ease at the time of performing re-peeling, and the damage prevention to an electronic component.
[0049]
Furthermore, it is preferable that the heat-radiating resin sheet of the present invention has an increase rate of adhesive strength of 0 to 30% after applying a pressure of ² kg / cm ² and heating at 60 ° C. for 10 days. If the rate of increase in adhesive strength after pressurization and heating is greater than 30%, the releasability at the time of repair is lowered, and there are cases where problems such as deterioration in workability and breakage of parts may occur. When the viscosity is lowered, there is a possibility that a minute air layer is formed at the interface with the electronic component to cause a problem that the thermal resistance is increased.
[0050]
【Example】
EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not restrict | limited at all by this.
(Examples 1-4)
In each example, an α-olefin copolymer containing propylene, 1-butene and 4-methyl-1-pentene in mol% shown in Table 1 was used as a resin component, and the heat conductive filler was adjusted to the weight ratio shown in Table 1. And blended. The thermally conductive filler is aluminum nitride (manufactured by Mitsui Chemicals, MAN2A and Toyo Aluminum, blended with UMS at a weight ratio of 30:70), and directly treated with the surface modifier shown in Table 1. It was obtained by doing. After blending, the mixture was dispersed by a ribbon blender, and a heat-dissipating resin sheet having a thickness of 100 μm was molded at an extrusion temperature of 180 ° C. by a T-die film molding method.
[0051]
Table 1 shows the results of the crystallinity measured by the X-ray diffraction method of the resin component (according to S, L. AGGAWARAL: J. Polymer Sci. 18, 17, 1955). Further, Table 1 also shows the results of measuring the initial adhesive strength, the pressure heating adhesive strength increase rate, the thermal conductivity, and the thermal softening temperature of the obtained heat-dissipating resin sheet by the following methods.
[0052]
Measurement of initial adhesive strength: A 2 mm-thick aluminum plate and a 0.1 mm-thick aluminum plate were bonded together via the heat-dissipating resin sheet of the present invention, and measured by a 180-degree peeling method.
Pressurizing and warming change evaluation: The sample for measuring the initial adhesive strength was used. A silicon rubber plate having a thickness of 3 mm is laminated on a 0.1 mm thickness aluminum plate, and is taken out after being kept for 240 hours in a state where a pressure of ² kg / cm ² is applied with a heating press heated to 60 ° C. The adhesive strength was measured by a 180 degree peeling method within 5 hours. The increase rate of the adhesive strength was calculated by [(Adhesive strength after heating under pressure−Initial adhesive strength) / Initial adhesive strength] × 100 (%).
Thermal conductivity: Measured with a laser flash method thermal conductivity measuring device manufactured by Kyoto Electronics Industry Co., Ltd.
Thermal softening temperature: Using a rheometric scientific FM viscoelasticity measuring device RMS-800, a parallel plate with a diameter of 8 mm was used, the gap between the plates was 1.5 mm, Using a disk of 8 mmφ × 1.5 mm (thickness), it was obtained from the inflection point of the storage elastic modulus G ′ (Pa) at a frequency ω = 100 rad / sec and a measurement temperature of 20 ° C. to 150 ° C.
[0053]
Example 5
An α-olefin copolymer composed of 50 mol% of propylene, 20 mol% of 1-butene and 30 mol% of 4-methyl-1-pentene was dissolved in n-heptane to prepare a solution having a solid content of 50 wt%. Water-resistant aluminum nitride powder (Mitsui Chemicals Co., Ltd., MAN-2A 400 parts by weight, Toyo Aluminum Co., Ltd., UMS 800 parts by weight) that has not been surface-modified is mixed with 20 parts by weight of this solution. 42 parts by weight of methacryloxypropyltrimethoxysilane was added and dispersed with three rolls. The dispersion was applied onto a 50 μm thick polyethylene terephthalate film and dried to obtain a heat-dissipating resin sheet. The thickness of the sheet was 200 μm. The results of measuring this sheet are shown in Table 1.
[0054]
Example 6
50 parts by weight of an α-olefin copolymer consisting of 50 mol% of propylene, 20 mol% of 1-butene and 30 mol% of 4-methyl-1-pentene, 20 wt% of a copolymer consisting of 80 mol% of ethylene and 20 mol% of propylene. 1 part of vinyltrimethoxysilane to 100 parts by weight of a resin component consisting of a mixture of 20 parts by weight, SEBS (manufactured by Shell Chemical Co., Ltd., G-1657) and 10 parts by weight of SIS (manufactured by Nippon Synthetic Rubber Co., Ltd., SIS5000) 1100 parts by weight of alumina which had been treated in an aqueous solution, filtered and dried was added, and a heat-dissipating resin sheet was obtained in the same manner as in Example-1. The results of measuring this sheet are shown in Table 1.
[0055]
Comparative Example 1
20 parts by weight of ethylene / α-olefin / non-conjugated polyene random copolymer EPT-4010 (manufactured by Mitsui Chemicals), 30 parts by weight of Lucant HC3000X (manufactured by Mitsui Chemicals) as the ethylene / α-olefin copolymer, α -100 parts by weight of resin component consisting of 30 parts by mole of dialen 208 (Mitsubishi Chemical Corporation) having 17 to 25 carbon atoms as an olefin and 20 parts by weight of Dialen 30 (Mitsubishi Chemical Corporation) having 30 to 40 carbon atoms In the same manner, 1100 parts by weight of untreated aluminum nitride was mixed and sheeted as in Example 1 to obtain a heat-dissipating resin sheet. Table 1 shows the measurement results of this sheet.
[0056]
[Table 1]

[0057]
【The invention's effect】
According to the present invention, it is solid at room temperature and exhibits sufficient adhesiveness for temporary fixing, and is not easily contaminated by bleed even after being exposed to a long-term hot-pressed environment, and can be easily removed again. Providing a heat-dissipating sheet that softens at the operating temperature, lowers the contact thermal resistance at the interface, and improves the wettability of the heat-conductive filler and resin, and improves the dispersibility and thus the heat conductivity. We were able to.

Claims (4)

A resin component mainly composed of an α-olefin copolymer having a main component of at least two α-olefins selected from α-olefins having 2 to 12 carbon atoms and a crystallinity of 10% or less, A heat-dissipating resin sheet comprising a thermally conductive filler coated with a surface modifier represented by general formulas (1) to (4).

(In formula (1), R represents a methyl group or an ethyl group.)

(In formula (2), R ₁ represents a methyl group or an ethyl group, and R ₂ represents a hydrogen atom or a methyl group).

(In formula (3), R ₃ represents a methyl group or an ethyl group, and R ₄ represents a hydrogen atom or a methyl group).

(In formula (4), R ₅ represents a methyl group or an ethyl group, and R ₆ represents a C8 to C20 alkyl group.) The heat-radiating resin sheet according to claim 1, wherein the α-olefin copolymer is composed of propylene, 1-butene, and an α-olefin having 5 to 12 carbon atoms. An α-olefin copolymer comprising a resin component of propylene, 1-butene, and an α-olefin having 5 to 12 carbon atoms;
(A) a copolymer comprising at least two selected from ethylene, propylene, and 1-butene;
(B) a co-oligomer of ethylene and α-olefin,
The heat-radiating resin sheet according to any one of claims 1 to 3, comprising (c) at least one copolymer selected from styrene-diene copolymers or hydrogenated products thereof. . The heat-dissipating resin sheet according to any one of claims 1 to 3, wherein the heat conductive filler is any one of an inorganic nitride, an inorganic oxide, and a metal.