JP2004079641A

JP2004079641A - Heat radiating member and connection structure

Info

Publication number: JP2004079641A
Application number: JP2002235150A
Authority: JP
Inventors: Kenichi Azuma; 東　賢一; Atsushi Hasegawa; 長谷川　淳; Shunji Hyozu; 俵頭　俊司
Original assignee: Sekisui Chemical Co Ltd
Current assignee: Sekisui Chemical Co Ltd
Priority date: 2002-08-12
Filing date: 2002-08-12
Publication date: 2004-03-11

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiating member which can efficiently conduct the heat generated from a heating element to a heat sink by adhering closely to the heating element and heat sink due to its high flexibility when the member is interposed between the heating element and heat sink, has excellent operability at a normal temperature, and is also excellent in keepability, and to provide a connection structure constituted by connecting the heating element and heat sink to each other through the heat radiating member. <P>SOLUTION: The heat radiating member is composed of a thermoplastic resin composition containing a thermoplastic resin, fine heat-conductive particles, and a thixotropy imparting agent and not containing such a compound that has a melting temperature of 40-100°C. At 23°C, the member has a storage elastic modulus of ≥5,000 Pa at 0.1 Hz and maintains ain infinite form. At 80°C, the storage elastic modulus becomes ≤1,000 Pa at 0.1 Hz and the member does not maintain the infinite form when a fixed pressure is applied to the member. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、発熱体と放熱体との間に介在し、高い柔軟性を有することにより発熱体及び放熱体に密着して効率よく発熱体から発生した熱を放熱体に伝導することができ、かつ、常温においては優れた取り扱い性を有し、保管性にも優れる放熱用部材、及び、該放熱用部材により発熱体と放熱体とを接続してなる接続構造体に関する。
【０００２】
【従来の技術】
電気・電子部品等の発熱体と放熱体の間に介在させ、発熱体から発生する熱を放散させる目的で、放熱シート等の放熱用部材が利用されている。しかし、電気・電子部品に限らず、多くの発熱体や放熱体の表面は平滑でないため放熱用部材が発熱体及び放熱体に密着できず、発熱体や放熱体と放熱用部材との間の接触面積が減少すると、発熱体から放熱体への熱伝達効率が低下し、放熱用部材が有する放熱性能が充分に発揮できない。
【０００３】
発熱体と放熱体の間の熱的な抵抗は熱抵抗と呼ばれ、熱抵抗が小さいほど、発熱体から放熱体への熱伝達が優れ、高い放熱効果が得られる。そのため熱抵抗を小さくするためには、放熱用部材に対して優れた柔軟性が要求されている。そこで、従来は、放熱用部材として熱伝導性徴粒子を含有した放熱グリース；シリコンゴムやアクリル酸エステル系樹脂等の柔軟かつ復元力のある樹脂に熱伝導性徴粒子を分散させた放熱シート等が用いられていた。
【０００４】
放熱グリースとしては、例えば、特公平６−３９５９１号公報にシリコンオイルをベースとし、亜鉛華、アルミナ、窒化アルミニウム等の熱伝導性徴粒子を含有させたものが開示されている。このような放熱グリースは流動性のある粘稠な物質であるため、発熱体と放熱体の間に介在させた際に大きな接触面積が得られることから優れた熱抵抗性能を発現可能である。しかしながら、発熱体や放熱体に塗布させる際に、周辺部位の汚れなどが生じて作業性が低いことや、作業のばらつきが生じて熱抵抗性能が変化する可能性が高い等の問題があった。
【０００５】
放熱シートとしては、例えば、特開平６−８８０６１号公報にアクリル酸エステル系樹脂に熱伝導性徴粒子をランダムに分散させた熱伝導テープが開示されている。このような放熱シートは定形のシートであるため、発熱体や放熱体に容易に貼り付けることができ、発熱体と放熱体の間に介在させる際に一定の間隙にすることができるため、安定した熱抵抗性能を発現することができる。しかしながら、流動性がないため、放熱グリースほどの高い柔軟性が得られず、高い熱抵抗性能を発現することが困難であった。
【０００６】
これに対し、特表２０００−５０９２０９号公報にはアクリル系感圧性粘着成分に対し、約５０〜６０℃に融解温度を有するαオレフィン系熱可塑性成分や約６０〜７０℃の融解温度を有するパラフィン系ロウ成分等の化合物を混合した放熱用部材が開示されている。これらの放熱用部材は、電圧を印加することで発熱体の温度が上がり、混合しているαオレフィン系熱可塑性成分やパラフィン系ロウ成分の融解温度に達すると急激に軟化し、柔軟性が向上して熱抵抗性能が向上するというものである。
【０００７】
しかしながら、このような融解温度を持つ化合物は、発熱体や放熱体への貼付作業を行う２３℃付近の温度では接着性のない固体であるため、これを含有するアクリル系感圧性粘着成分の粘着性が損なわれ、貼付作業性か低下する。また、発熱体の温度が上がって融解温度を超える際に、化合物がすべて融解するまでに若干の時間がかかることから、発熱体の温度がいったんは急上昇する。そして、融解温度を有する化合物が溶けて放熱用部材の柔軟性が向上し、発熱体と放熱体の間が密着して熱伝達率が向上すると発熱体の温度は急降下する。そのため短時間ではあるが、発熱体に温度負荷がかかるという問題があった。
【０００８】
【発明が解決しようとする課題】
本発明者らはこれまでに、熱可塑性樹脂と熱伝導性微粒子とを含有し、４０〜１００℃に融解温度を有する化合物を含有しない熱可塑性樹脂組成物からなる放熱用部材であって、２３℃においては、０．１Ｈｚ時の貯蔵弾性率が５０００Ｐａ以上であり、かつ、定形を保持しており、８０℃においては、０．１Ｈｚ時の貯蔵弾性率が１０００Ｐａ以下であり、かつ、不定形である放熱用部材を発明し、提案してきた。この放熱用部材は、発熱体や放熱体への貼付作業を行う２３℃付近の温度では定形のシート状にして用いることができ優れた貼付作業性を示し、一方で、電圧を印加することにより発熱体の温度が上がると放熱用部材は急速に軟化し、８０℃以上の温度に達すると柔軟性が更に向上するため発熱体と放熱体に対する接触面積が向上し、優れた熱抵抗性能を発現することができるというものであった。
しかし、この放熱部材は発熱体と放熱体との接合に極めて優れた性能を発揮できる一方で、温度がかかることにより軟化することから、保管時に変形等が起こることがあるという問題があった。
本発明は、上記現状に鑑み、発熱体と放熱体との間に介在し、高い柔軟性を有することにより発熱体及び放熱体に密着して効率よく発熱体から発生した熱を放熱体に伝導することができ、かつ、常温においては優れた取り扱い性を有し、保管性にも優れる放熱用部材、及び、該放熱用部材により発熱体と放熱体とを接続してなる接続構造体を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明は、熱可塑性樹脂、熱伝導性微粒子及びチキソトロピー性付与剤とを含有し、４０〜１００℃に融解温度を有する化合物を含有しない熱可塑性樹脂組成物からなる放熱用部材であって、２３℃においては、０．１Ｈｚ時の貯蔵弾性率が５０００Ｐａ以上であり、かつ、定形を保持しており、８０℃においては、０．１Ｈｚ時の貯蔵弾性率が１０００Ｐａ以下であり、かつ、一定の圧力を加えた場合においては不定形である放熱用部材である。
以下に本発明を詳述する。
【００１０】
本発明の放熱部材は、２３℃においては、０．１Ｈｚ時の貯蔵弾性率が５０００Ｐａ以上であり、かつ、定形を保持しており、８０℃においては、０．１Ｈｚ時の貯蔵弾性率が１０００Ｐａ以下であり、かつ、一定の圧力を加えた場合においては不定形である。これにより、発熱体や放熱体への貼付作業を行う２３℃付近の温度では定形のシート状にして用いることができ優れた貼付作業性を示し、一方で、電圧を印加することにより発熱体の温度が上がると同時に圧力を加えることにより放熱用部材は急速に軟化し、８０℃以上の温度に達すると柔軟性が更に向上するため発熱体と放熱体に対する接触面積が向上し、優れた熱抵抗性能を発現することができる。また、軟化には熱だけでなく同時に圧力を加えることを要することから、保管時に熱がかかることがあっても変形等が起こることがなく、保管性も極めて優れる。なお、上記圧力を加える方法としては特に限定されないが、例えば、本発明の放熱用部材を介して発熱体と放熱体とを接合する際にクリップ等を用いて挟み込むようにすれば、圧力を加えることができる。
上記貯蔵弾性率は、例えばレオメトリックス社製のダイナミック・アナライザーＲＤＡＩＩ等の動的粘弾性測定装置で測定することができる。
【００１１】
２３℃の温度における０．１Ｈｚ時の貯蔵弾性率が５０００Ｐａ未満であると、柔らかすぎて取り扱いにくくなり、貼付作業も行いにくくなる。また、８０℃で一定の圧力を加えた場合の０．１Ｈｚ時の貯蔵弾性率が１０００Ｐａを超えると、放熱用部材の柔軟性が低く発熱体や放熱体に密着できず、充分な熱抵抗性能が得られない。
【００１２】
２３℃と８０℃との間に、相転移現象を伴わずにこのような急速な貯蔵弾性率の変化が起こることから、発熱体の温度の上昇にあわせて放熱用部材がしだいに密着していき、発熱体の温度の上昇と、放熱用部材が軟化して発熱体と放熱体に対する接触面積が向上し優れた熱抵抗性能を発現するまでの間に時間の遅れが生じないため、発熱体の温度が急上昇してしまうことがなく、発熱体に温度負荷がかかることがない。
また、相転移現象を伴わない熱可塑性樹脂組成物では、室温や室温よりわずかに加熱しただけで柔らかくなったり、樹脂表面に粘着性が現れることがあり放熱用部材として取り扱いにくいことが多いが、本発明の放熱用部材は、熱と同時に圧力を加えることにより軟化するものであることから、取扱い性及び保管性にも優れる。
【００１３】
なお、上記熱可塑性樹脂組成物に４０〜１００℃に融解温度を有する化合物が添加されると、融解という相転移現象に伴う潜熱吸収が起こるため、融解が充分に進むまで放熱用部材が軟化しないので、発熱体の温度の上昇と、放熱用部材が軟化して発熱体と放熱体に対する接触面積が向上し優れた熱抵抗性能を発現するまでの間に時間の遅れが生じてしまい、発熱体に温度負荷がかかってしまう。したがって、上記熱可塑性樹脂組成物は、４０〜１００℃に融解温度を有する化合物を含有しない。
【００１４】
本発明の放熱用部材は、２３℃における対アルミニウム接着力が０．５Ｎ／ｃｍ^２以上であることが好ましい。これにより、発熱体及び放熱体に対して高い接着性を有することとなり、発熱体及び放熱体に放熱用部材を貼り付ける際の貼付作業性が向上する。
【００１５】
本発明の放熱用部材は、特に限定されないが、シート状に加工して用いることが好ましい。シート状にすることにより、貼付作業性が著しく向上する。
シート状にして用いる場合、シートが薄くなりすぎると取り扱い性が低下するとともに、発熱体と放熱体との間に介在させた際に、隙間を充分に埋めることが難しくなり、また、シートが厚すぎると熱抵抗性能が低下する傾向にある。したがって、本発明の放熱用部材の厚さは下限が２０μｍ、上限が４００μｍであることが好ましい。
【００１６】
本発明の放熱用部材は、熱可塑性樹脂、熱伝導性微粒子及びチキソトロピー性付与剤を含有する熱可塑性樹脂組成物からなる。
上記熱可塑性樹脂としては、（メタ）アクリル酸エステル系共重合体；スチレン−ブタジエン−スチレンブロック共重合体、スチレン−イソプレン−スチレンブロック共重合体等のスチレン系ブロック共重合体；エチレン−酢酸ビニル樹脂、ブタジエン系樹脂、イソブチレン系樹脂、オレフィン系樹脂、ウレタン系樹脂、エポキシ系樹脂、酢酸ビニル系樹脂、スチレン系樹脂、ブチラ−ル系樹脂、ポリビニルアルコール系樹脂、シリコン系樹脂；これらの変性樹脂等が挙げられる。これらは単独で用いられてもよいし、２種類以上を併用してもよい。なかでも、上述の貯蔵弾性率を実現できる設計が比較的容易であることから、アクリル酸エステル系共重合体、スチレン系ブロック共重合体、ブチルゴム系樹脂が好適である。例えば、アクリル酸エステル系共重合体であれば、共重合体の重量平均分子量を２０万以下にすれば、上述の貯蔵弾性率を発現することができる。
【００１７】
なお、上記熱可塑性樹脂はＩＣ等の電子部品の高温側の動作限界温度付近に融点を有する樹脂ではないことが好ましい。また、ガラス転移温度を有する樹脂の場合においても、示差熱量計を用いて測定されるガラス転移温度がＩＣ等の電子部品の高温側の動作限界温度付近にないことが好ましい。これらの樹脂の融解やガラス転移現象における潜熱吸収もまた、発熱体や放熱体と放熱用部材との間が密着するまでに時間の遅れを生じさせる原因となることがある。また、流動性が高い樹脂の場合は放熱用部材が発熱体と放熱体の間から流れ出してしまう恐れもある。例えば、ガラス転移温度を有する樹脂の場合は、示差熱量計を用いて測定されるガラス転移温度が４０℃以下又は６０℃以上であることが好ましい。なお、低い温度ではより好ましくは３０℃以下、更に好ましくは２０℃以下であり、高い温度ではより好ましくは７０℃以上、更に好ましくは８０℃以上である。
【００１８】
また、上記熱可塑性樹脂として、スチレン系ブロック共重合体、ブチルゴム等の２３℃において固形状の芳香族熱可塑性樹脂を用いる場合には、更に２３℃において液状の芳香族化合物を含有することが好ましい。
例えば、スチレン系ブロック共重合体であればアルキルベンゼン等を添加することによって、ブチルゴムであればプロセスオイル等を添加することによって、上述の貯蔵弾性率の挙動においてより急激な変化を発現させることができる。これは、２３℃において固形状の芳香族熱可塑性樹脂と２３℃において液状の芳香族化合物とを混合して使用すると、それぞれの芳香環同士の相互作用によって２３℃では固形状態を保つが、温度を上昇させるとしだいに相互作用が弱まり、ある温度領域で相転移現象を伴うことなく相互作用が急激に弱まり軟化するためである。ただし、熱伝導性微粒子の配合量が増えると、種類によっては高温での弾性率が低下する傾向にあるので、本発明の放熱用部材の弾性率挙動は、熱可塑性樹脂の種類、液状の芳香族化合物の種類及び配合量により適当に調整する必要がある。
【００１９】
上記熱伝導性微粒子としては、例えば、窒化ホウ素、窒化アルミニウム、アルミナ、アルミニウム、炭化珪素、酸化亜鉛、銅、金属水酸化物から選ばれる少なくとも１種類以上の熱伝導性微粒子が挙げられる。
上記金属水酸化物としては、例えば、水酸化マグネシウム、水酸化アルミニウム等が挙げられる。
また、これらの熱伝導性微粒子は、高い配合割合で均一に混合できるように表面処理されていることが好ましい。
【００２０】
上記熱可塑性樹脂組成物における上記熱伝導性微粒子の配合量の好ましい下限は１０体積％、上限は９０体積％である。１０体積％未満であると、充分な熱伝導率が得られないことがあり、９０体積％を超えると、得られる放熱用部材の対アルミニウム接着力が低下して貼付作業性が低下することがある。
【００２１】
上記熱可塑性樹脂組成物は、チキソトロピー性付与剤を含有する。
本明細書においてチキソトロピー性とは、外力が加えられずに静置されているときと比較して、圧力等の外力が加えられたときに軟化するような特性を意味し、チキソトロピー性付与剤とは、添加することで樹脂にチキソトロピー性を発現させ得る物質を意味する。
このようなチキソトロピー性付与剤を含有する熱可塑性樹脂組成物からなることにより、本発明の放熱用部材は、温度が上昇したのみでは軟化せず、温度と圧力とが加わったときにのみ軟化するという性質を発現することができる。
【００２２】
上記チキソトロピー性付与剤としては特に限定されず、例えば、親水性シリカ、水添ひまし油、アマイドワックス又はポリエチレンファイバー等が挙げられる。なかでも、親水性シリカが好適に用いられる。上記親水性シリカのうち市販されているものとしては、例えば、アエロジル（日本アエロジル社製）等が挙げられる。これらのチキソトロピー剤は単独で用いられてもよく、２種以上が併用されてもよい。
【００２３】
上記チキソトロピー性付与剤の含有量としては、上記親水性シリカを用いる場合には好ましい下限は０．５体積％、好ましい上限は３．５体積％であり、上記水添ひまし油を用いる場合には好ましい下限は１体積％、好ましい上限は４体積％であり、上記アマイドワックスを用いる場合には好ましい下限は２体積％、好ましい上限は６体積％であり、上記ポリエチレンファイバーを用いる場合には好ましい下限は１体積％、好ましい上限は２体積％である。この範囲内のチキソトロピー性付与剤を含有させることにより、本発明の放熱用部材は熱及び圧力を加えたときにはじめて軟化する性質を発現しやすい。これらの下限値未満であると、圧力を加えずとも加熱により軟化してしまうことがあり、これらの上限値を超えると、接着力が低下し貼付作業性が低下することがある。
【００２４】
上記熱可塑性樹脂組成物は、所望の弾性率と接着力を損なわない鞄囲であれば、必要に応じて、ハロゲン系化合物、リン酸エステル系化合物、金属水酸化物、酸化チタン等の難燃材；カーボンブラック、ホワイトカーボン等の着色剤；シラン系、チタネート系カップリング剤等の粉体表面改質剤；ビスフェノール系、ヒンダード・フェノール系等の酸化防止剤；クロマン樹脂、テルペンフェノール樹脂、フェノール樹脂、ロジン、テルペン樹脂、脂肪族炭化水素、脂環式炭化水素等の粘着付与剤等を含有してもよい。
【００２５】
本発明の放熱用部材の製造方法としては特に限定されず、例えば、所定量の熱可塑性樹脂、熱伝導性徴粒子、チキソトロピー性付与剤を、２本ロール、３本ロール、プラストミル、ニーダー、プラネタリーミキサー、バンバリーミキサー等を用いて混合し、それをコーティング成形、押し出し成形、プレス成形等によって所望の厚さのシート状に成形する方法等が挙げられる。
【００２６】
本発明の放熱用部材は、２３℃付近の常温においては定形であり極めて取り扱い性に優れ、効率よく発熱体と放熱体とを接続した接続構造体を作製することができる。
この接続構造体の発熱体の温度を上昇させ同時に圧力を加えると、一定温度以上になった時点で、ガラス転移現象や融解等の潜熱吸収を伴う相転移現象を伴うことなく急速に本発明の放熱用部材が軟化して発熱体及び放熱体との接触面積が大きくなり、更にそれに伴って放熱用部材の厚みが減少して、優れた熱抵抗性能を発現することができる。しかも、かかる放熱用部材の変化は急速であり、発熱体の温度が発熱体にとって負荷となる温度に達するまで上昇してしまう前に起こることから、発熱体に温度負荷がかかることがない。
かかる、本発明の放熱用部材により発熱体と放熱体とを接続してなる接続構造体であって、上記放熱用部材は、発熱体の発熱と圧力を加えることにより、上記発熱前よりも厚みが減少することが可能である接続構造体もまた、本発明の１つである。
また、本発明の放熱用部材により発熱体と放熱体とを接続してなる接続構造体であって、上記放熱用部材は、発熱体が発熱し、圧力が加わったことにより、上記発熱前よりも既に厚みが減少しているものである接続構造体もまた、本発明の１つである。
【００２７】
【実施例】
以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。
【００２８】
（実施例１）
スチレン−イソプレン−スチレンブロック共重合体１９重量部、ドデシルベンゼン８０重量部、アルミナ（住友化学工業社製、商品名：アドバンストアルミナＡＡ１８（粒子径１８μｍ）とＡＡ２（粒子径２μｍ）の混合物）６００重量部及びチキソトロピー性付与剤として親水性シリカ（日本アエロジル社製、商品名：ＡＥＲＯＳＩＬ２００）１重量部をプラストミルで混合しスラリー状物を得た。このスラリー状物においてアルミナの体積比率は６０％であった。
更にスラリー状物を３本ロール（ノリタケカンパニーリミテッド社製、商品名：ＮＲ−１２０Ａ）を用いて回転数３０ｒｐｍで混練した。３本ロールにて回転した回数は２回以上とした。
次いで、プレス板の上に離型ポリエチレンテレフタレート（ＰＥＴ）フィルムを敷き、その上に厚みが１００μｍの金属枠を載せ、金属枠内に得られたスラリー状物を流し込んだ。次いで離型ＰＥＴフィルムをその上に載せ、上下からプレス板で挟み込み室温下でプレス成形を行った。これにより両面に離型ＰＥＴフィルムがついた厚さ１００μｍのシート状の放熱用部材を得た。
【００２９】
（実施例２）
スチレン−イソプレン−スチレンブロック共重合体１８重量部、ドデシルベンゼン７７重量部、アルミナ（住友化学工業社製、商品名：アドバンストアルミナＡＡ１８（粒子径１８μｍ）とＡＡ２（粒子径２μｍ）の混合物）６００重量部及びチキソトロピー性付与剤として水添ひまし油（楠本化成社製、商品名：ディスパロン４１１０）５重量部をプラストミルで混合しスラリー状物を得た。このスラリー状物においてアルミナの体積比率は６０％であった。
更にスラリー状物を３本ロール（ノリタケカンパニーリミテッド社製、商品名：ＮＲ−１２０Ａ）を用いて回転数３０ｒｐｍで混練した。３本ロールにて回転した回数は２回以上とした。
このスラリー状物を用いて実施例１と同様の方法により両面に離型ＰＥＴフィルムがついた厚さ１００μｍのシート状の放熱用部材を得た。
【００３０】
（実施例３）
スチレン−イソプレン−スチレンブロック共重合体１８重量部、ドデシルベンゼン７２重量部、アルミナ（住友化学工業社製、商品名：アドバンストアルミナＡＡ１８（粒子径１８μｍ）とＡＡ２（粒子径２μｍ）の混合物）６００重量部及びチキソトロピー性付与剤としてアマイドワックス（楠本化成社製、商品名：ディスパロン６７００）１０重量部をプラストミルで混合しスラリー状物を得た。このスラリー状物においてアルミナの体積比率は６０％であった。
更にスラリー状物を３本ロール（ノリタケカンパニーリミテッド社製、商品名：ＮＲ−１２０Ａ）を用いて回転数３０ｒｐｍで混練した。３本ロールにて回転した回数は２回以上とした。
このスラリー状物を用いて実施例１と同様の方法により両面に離型ＰＥＴフィルムがついた厚さ１００μｍのシート状の放熱用部材を得た。
【００３１】
（実施例４）
スチレン−イソプレン−スチレンブロック共重合体１８重量部、ドデシルベンゼン７７重量部、アルミナ（住友化学工業社製、商品名：アドバンストアルミナＡＡ１８（粒子径１８μｍ）とＡＡ２（粒子径２μｍ）の混合物）６００重量部及びチキソトロピー性付与剤としてポリエチレンファイバー（三井化学社製、商品名：ケミベストＦＤＳＳ５）５重量部をプラストミルで混合しスラリー状物を得た。このスラリー状物においてアルミナの体積比率は６０％であった。
更にスラリー状物を３本ロール（ノリタケカンパニーリミテッド社製、商品名：ＮＲ−１２０Ａ）を用いて回転数３０ｒｐｍで混練した。３本ロールにて回転した回数は２回以上とした。
このスラリー状物を用いて実施例１と同様の方法により両面に離型ＰＥＴフィルムがついた厚さ１００μｍのシート状の放熱用部材を得た。
【００３２】
（比較例１）
スチレン−イソプレン−スチレンブロック共重合体２０重量部、ドデシルベンゼン８０重量部及びアルミナ（住友化学工業社製、商品名：アドバンストアルミナＡＡ１８（粒子径１８μｍ）とＡＡ２（粒子径２μｍ）の混合物）６００重量部をプラストミルで混合しスラリー状物を得た。このスラリー状物においてアルミナの体積比率は６０％であった。
更にスラリー状物を３本ロール（ノリタケカンパニーリミテッド社製、商品名：ＮＲ−１２０Ａ）を用いて回転数３０ｒｐｍで混練した。３本ロールにて回転した回数は２回以上とした。
このスラリー状物を用いて実施例１と同様の方法により両面に離型ＰＥＴフィルムがついた厚さ１００μｍのシート状の放熱用部材を得た。
【００３３】
＜評　価＞
実施例１〜４及び比較例１で得られた放熱用部材について、以下の方法により、熱抵抗及び貯蔵弾性率、保存性を評価した。
結果を表１に示した。
【００３４】
（熱抵抗の測定）
熱抵抗は、図１に示す測定装置により測定した。すなわち、アルミニウム製の冷却器１の上に離型ＰＥＴフィルムを剥がした放熱用部材２を貼り付け、更にその上に熱源となるＩＣを積層し、ボルト３により締め付けトルク１Ｎ・ｍで締め付けた。
ＩＣに電源を入れて８０Ｗ／ｈの電力を供給し、６０分後に、ＩＣの温度Ｔ１と、冷却器１の放熱用部材の近傍温度Ｔ２を測定した。なお、冷却器１は、内部に恒温水槽４から２３℃の水が供給循環されるようになっている。測定結果から熱抵抗を下記式で求めた。
【００３５】
【数１】

【００３６】
（貯蔵弾性率の測定）
ダイナミック・アナライザーＲＤＡＩＩ（レオメトリックス社製）を用い、０．１Ｈｚの条件で放熱用部材の貯蔵弾性率を測定し、２３℃及び８０℃における放熱用部材の貯蔵弾性率を求めた。
【００３７】
（保存性の評価）
図２に示したように、アルミニウムからなる正立方体のブロックの側面に片面の離型ＰＥＴフィルムを剥がした放熱用部材を貼り付けた。このアルミニウムブロックを８０℃の恒温槽に保管し、１週間経過後に放熱用部材の流れ落ちの有無を目視にて観察した。
【００３８】
【表１】

【００３９】
【発明の効果】
本発明によれば、発熱体と放熱体との間に介在し、高温では高い柔軟性を有することにより発熱体及び放熱体に密着して効率よく発熱体から発生した熱を放熱体に伝導することができ、かつ、常温においては優れた取り扱い性を有し、保管性にも優れる放熱用部材、及び、該放熱用部材により発熱体と放熱体とを接続してなる接続構造体を提供できる。
【図面の簡単な説明】
【図１】放熱用部材の熱抵抗の測定に用いた測定装置を示す模式図である。
【図２】実施例における保存性の評価の方法を説明する模式図である。
【符号の説明】
１　冷却器
２　放熱用部材
３　ボルト
４　恒温水槽
５　アルミニウムブロック[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is interposed between the heating element and the heat radiator, and has high flexibility, so that the heat generated from the heating element can be efficiently transferred to the heat radiator by being in close contact with the heating element and the heat radiator, In addition, the present invention relates to a heat dissipating member having excellent handleability at room temperature and excellent storage stability, and a connection structure formed by connecting a heating element and a heat dissipating member with the heat dissipating member.
[0002]
[Prior art]
BACKGROUND ART A heat-dissipating member such as a heat-dissipating sheet is used for the purpose of interposing between a heat-generating element such as an electric / electronic component and a heat-dissipating element and dissipating heat generated from the heat-generating element. However, not only electric and electronic parts, but also the surfaces of many heat generating elements and heat radiating elements are not smooth, so that the heat radiating element cannot be in close contact with the heat generating element and the heat radiating element. When the contact area is reduced, the heat transfer efficiency from the heat generating element to the heat radiating element is reduced, and the heat radiating performance of the heat radiating member cannot be sufficiently exhibited.
[0003]
The thermal resistance between the heating element and the heat radiator is called thermal resistance. The smaller the thermal resistance, the better the heat transfer from the heating element to the heat radiator, and the higher the heat radiation effect. Therefore, in order to reduce the thermal resistance, the heat dissipating member is required to have excellent flexibility. Therefore, conventionally, a heat-dissipating grease containing heat-conducting particles as a heat-dissipating member; a heat-dissipating sheet or the like in which the heat-conducting particles are dispersed in a flexible and resilient resin such as silicone rubber or an acrylate resin are used. Had been.
[0004]
As the heat radiation grease, for example, Japanese Patent Publication No. 6-39591 discloses a grease based on silicon oil and containing thermally conductive particles such as zinc white, alumina and aluminum nitride. Since such a heat radiation grease is a fluid viscous substance, a large contact area can be obtained when the heat radiation grease is interposed between the heating element and the heat radiation element, so that excellent heat resistance performance can be exhibited. However, when applied to a heating element or a heat radiating element, there is a problem that dirt or the like in a peripheral portion is generated and workability is low, and there is a high possibility that a variation in work occurs and thermal resistance performance is changed. .
[0005]
As a heat radiation sheet, for example, JP-A-6-88061 discloses a heat conductive tape in which heat conductive particles are randomly dispersed in an acrylate resin. Since such a heat radiation sheet is a fixed sheet, it can be easily attached to a heating element or a heat radiating body, and can have a constant gap when interposed between the heating element and the heat radiating body. It is possible to exhibit the improved heat resistance performance. However, since there is no fluidity, it is not possible to obtain high flexibility like heat radiation grease, and it is difficult to exhibit high heat resistance performance.
[0006]
On the other hand, JP-T-2000-509209 discloses an α-olefin thermoplastic component having a melting temperature of about 50 to 60 ° C. and a paraffin having a melting temperature of about 60 to 70 ° C. with respect to an acrylic pressure-sensitive adhesive component. A heat dissipating member in which a compound such as a system wax component is mixed is disclosed. These heat-dissipating members increase the temperature of the heating element by applying a voltage, and when they reach the melting temperature of the mixed alpha-olefin-based thermoplastic component and paraffin-based wax component, they soften rapidly, improving their flexibility. Thus, the heat resistance performance is improved.
[0007]
However, since a compound having such a melting temperature is a solid having no adhesive property at a temperature around 23 ° C. at which the compound is attached to a heating element or a heat radiating element, the pressure of the acrylic pressure-sensitive adhesive component containing the compound is low. The workability is impaired, and the workability of application is reduced. Further, when the temperature of the heating element rises and exceeds the melting temperature, it takes some time until all the compounds are melted, so that the temperature of the heating element once rises rapidly. Then, when the compound having a melting temperature is melted and the flexibility of the heat radiating member is improved, and the heat generating body and the heat radiating body are in close contact with each other to improve the heat transfer coefficient, the temperature of the heat generating body rapidly drops. For this reason, there is a problem that the heat load is applied to the heating element for a short time.
[0008]
[Problems to be solved by the invention]
The present inventors have previously disclosed a heat-dissipating member comprising a thermoplastic resin composition containing a thermoplastic resin and heat conductive fine particles, and not containing a compound having a melting temperature of 40 to 100 ° C; At 0 ° C., the storage elastic modulus at 0.1 Hz is 5000 Pa or more and retains a fixed shape. At 80 ° C., the storage elastic modulus at 0.1 Hz is 1000 Pa or less, and Has been invented and proposed. This heat-dissipating member can be used in the form of a fixed sheet at a temperature of around 23 ° C. for performing the work of sticking to the heating element or the heat-dissipating body, and shows excellent sticking workability. On the other hand, by applying a voltage, When the temperature of the heating element rises, the heat-dissipating member softens rapidly, and when the temperature reaches 80 ° C or higher, the flexibility further improves, so that the contact area between the heating element and the heat-dissipating element increases, and excellent heat resistance performance is exhibited. Could be done.
However, this heat dissipating member can exhibit extremely excellent performance for joining the heat generating element and the heat dissipating element, but has a problem in that the heat dissipating member is softened by the application of temperature and may be deformed during storage.
In view of the above situation, the present invention is provided between a heating element and a heat radiator, and has high flexibility, so that the heat generated from the heating element is efficiently transferred to the heat radiator by closely adhering to the heating element and the heat radiator. A heat-dissipating member having excellent handling properties at room temperature and excellent storage stability, and a connection structure formed by connecting a heating element and a heat-dissipating element with the heat-dissipating member. The purpose is to do.
[0009]
[Means for Solving the Problems]
The present invention is a heat dissipating member comprising a thermoplastic resin composition containing a thermoplastic resin, heat conductive fine particles, and a thixotropic agent, and not containing a compound having a melting temperature of 40 to 100 ° C. At 0 ° C., the storage elastic modulus at 0.1 Hz is 5,000 Pa or more and keeps a fixed shape, and at 80 ° C., the storage elastic modulus at 0.1 Hz is 1000 Pa or less, and a constant. This is a heat dissipating member that is indefinite when pressure is applied.
Hereinafter, the present invention will be described in detail.
[0010]
The heat radiating member of the present invention has a storage elastic modulus at 0.1 Hz of not less than 5000 Pa at 23 ° C. and has a fixed form, and has a storage elastic modulus of 1000 Pa at 0.1 Hz at 80 ° C. Below, and when a certain pressure is applied, it is amorphous. Thereby, at a temperature around 23 ° C. where the work of sticking to the heating element or the heat radiator is performed, the sheet can be used in the form of a fixed sheet and excellent sticking workability is exhibited. By applying pressure at the same time as the temperature rises, the heat dissipating member softens rapidly, and when the temperature reaches 80 ° C or higher, the flexibility further improves, so that the contact area between the heating element and the heat dissipating element is improved, and excellent heat resistance is obtained. Performance can be exhibited. Further, since softening requires not only heat but also application of pressure at the same time, even if heat is applied during storage, there is no deformation or the like, and storage properties are extremely excellent. The method for applying the pressure is not particularly limited. For example, when the heating element and the heat radiator are joined using the clip or the like when the heat radiator and the heat radiator are joined via the heat radiating member of the present invention, the pressure is applied. be able to.
The storage elastic modulus can be measured by a dynamic viscoelasticity measuring device such as a dynamic analyzer RDAII manufactured by Rheometrics.
[0011]
If the storage elastic modulus at 0.1 Hz at a temperature of 23 ° C. is less than 5000 Pa, it is too soft and difficult to handle, and it is difficult to perform the sticking operation. Further, when the storage elastic modulus at 0.1 Hz when applying a constant pressure at 80 ° C. exceeds 1000 Pa, the flexibility of the heat radiation member is low, and the heat radiation member cannot adhere to the heat radiator or heat radiator, and has a sufficient thermal resistance performance. Can not be obtained.
[0012]
Since such a rapid change in storage modulus occurs between 23 ° C. and 80 ° C. without a phase transition phenomenon, the heat dissipating member gradually adheres to the rise in the temperature of the heating element. Since there is no time delay between the rise in the temperature of the heating element and the softening of the heat dissipating member, the contact area between the heating element and the heat dissipating element is improved and excellent heat resistance performance is exhibited. The temperature of the heating element does not rise suddenly, and no temperature load is applied to the heating element.
Further, in a thermoplastic resin composition not accompanied by a phase transition phenomenon, it is often difficult to handle as a heat-dissipating member, which may be softened by only slightly heating at room temperature or room temperature, or that the resin surface may show adhesiveness, Since the heat-dissipating member of the present invention is softened by applying pressure simultaneously with heat, it is excellent in handling and storage.
[0013]
When a compound having a melting temperature of 40 to 100 ° C. is added to the thermoplastic resin composition, latent heat absorption accompanying a phase transition phenomenon called melting occurs, so that the heat dissipation member does not soften until melting is sufficiently advanced. Therefore, there is a delay between the time when the temperature of the heating element rises and the heat dissipating member is softened and the contact area between the heating element and the heat dissipating element is improved and excellent heat resistance performance is exhibited. Temperature load. Therefore, the thermoplastic resin composition does not contain a compound having a melting temperature of 40 to 100 ° C.
[0014]
The heat-dissipating member of the present invention preferably has an adhesive strength to aluminum at 23 ° C. of 0.5 N / cm ² or more. Thereby, it has high adhesiveness to the heating element and the heat radiator, and the sticking workability when attaching the heat radiating member to the heating element and the heat radiator is improved.
[0015]
The heat-dissipating member of the present invention is not particularly limited, but is preferably processed into a sheet and used. By making it into a sheet shape, the sticking workability is remarkably improved.
When used in the form of a sheet, if the sheet is too thin, the handleability will be reduced, and it will be difficult to sufficiently fill the gap when interposed between the heating element and the heat radiating element. If too large, the thermal resistance performance tends to decrease. Therefore, it is preferable that the lower limit of the thickness of the heat radiation member of the present invention is 20 μm and the upper limit is 400 μm.
[0016]
The heat-dissipating member of the present invention comprises a thermoplastic resin composition containing a thermoplastic resin, thermally conductive fine particles, and a thixotropic agent.
Examples of the thermoplastic resin include (meth) acrylate ester copolymers; styrene block copolymers such as styrene-butadiene-styrene block copolymer and styrene-isoprene-styrene block copolymer; ethylene-vinyl acetate Resin, butadiene resin, isobutylene resin, olefin resin, urethane resin, epoxy resin, vinyl acetate resin, styrene resin, butyral resin, polyvinyl alcohol resin, silicon resin; modified resins of these And the like. These may be used alone or in combination of two or more. Among them, acrylic ester-based copolymers, styrene-based block copolymers, and butyl rubber-based resins are preferable because they are relatively easy to design to realize the above storage elastic modulus. For example, in the case of an acrylate-based copolymer, if the weight average molecular weight of the copolymer is 200,000 or less, the above-mentioned storage modulus can be exhibited.
[0017]
It is preferable that the thermoplastic resin is not a resin having a melting point near the operating limit temperature on the high temperature side of an electronic component such as an IC. Further, even in the case of a resin having a glass transition temperature, it is preferable that the glass transition temperature measured using a differential calorimeter is not near the operating limit temperature on the high temperature side of an electronic component such as an IC. The melting of these resins and the latent heat absorption in the glass transition phenomenon may also cause a delay in the time until the heating element or the heat dissipating member and the heat dissipating member come into close contact with each other. Further, in the case of a resin having a high fluidity, there is a possibility that the heat radiating member flows out from between the heat generating body and the heat radiating body. For example, in the case of a resin having a glass transition temperature, the glass transition temperature measured using a differential calorimeter is preferably 40 ° C or lower or 60 ° C or higher. The temperature is more preferably 30 ° C. or lower at a low temperature, more preferably 20 ° C. or lower, and more preferably 70 ° C. or higher, further preferably 80 ° C. or higher at a high temperature.
[0018]
Further, in the case of using a solid aromatic thermoplastic resin at 23 ° C. such as a styrene-based block copolymer or butyl rubber as the thermoplastic resin, it is preferable to further contain a liquid aromatic compound at 23 ° C. .
For example, by adding an alkylbenzene or the like in the case of a styrene-based block copolymer, or by adding a process oil or the like in the case of a butyl rubber, a more rapid change in the behavior of the storage elastic modulus can be developed. . This is because, when a mixture of an aromatic thermoplastic resin in a solid state at 23 ° C. and an aromatic compound in a liquid state at 23 ° C. is used, the solid state is maintained at 23 ° C. due to the interaction between the respective aromatic rings. Is increased, the interaction is weakened, and the interaction is rapidly weakened and softened without a phase transition phenomenon in a certain temperature range. However, when the blending amount of the heat conductive fine particles increases, the elastic modulus at a high temperature tends to decrease depending on the type. Therefore, the elastic modulus behavior of the heat dissipation member of the present invention depends on the type of the thermoplastic resin and the liquid aromatic. It is necessary to adjust appropriately according to the kind and the compounding amount of the group compound.
[0019]
Examples of the heat conductive fine particles include at least one or more heat conductive fine particles selected from boron nitride, aluminum nitride, alumina, aluminum, silicon carbide, zinc oxide, copper, and metal hydroxide.
Examples of the metal hydroxide include magnesium hydroxide and aluminum hydroxide.
Further, it is preferable that these heat conductive fine particles have been subjected to a surface treatment so as to be uniformly mixed at a high blending ratio.
[0020]
The preferred lower limit of the amount of the heat conductive fine particles in the thermoplastic resin composition is 10% by volume, and the upper limit is 90% by volume. If the content is less than 10% by volume, sufficient thermal conductivity may not be obtained. If the content is more than 90% by volume, the resulting heat-radiating member may have low adhesive strength to aluminum and may have poor sticking workability. is there.
[0021]
The thermoplastic resin composition contains a thixotropic agent.
In the present specification, thixotropy refers to a property of softening when an external force such as pressure is applied as compared with a case where the apparatus is left standing without applying an external force, and a thixotropy-imparting agent. Means a substance capable of causing a resin to exhibit thixotropic properties when added.
By comprising a thermoplastic resin composition containing such a thixotropic agent, the heat-dissipating member of the present invention does not soften only when the temperature rises, but only when temperature and pressure are applied. Property can be expressed.
[0022]
The thixotropic agent is not particularly restricted but includes, for example, hydrophilic silica, hydrogenated castor oil, amide wax or polyethylene fiber. Among them, hydrophilic silica is preferably used. Commercially available hydrophilic silicas include, for example, Aerosil (manufactured by Nippon Aerosil Co., Ltd.). These thixotropic agents may be used alone or in combination of two or more.
[0023]
As the content of the thixotropic agent, the lower limit is preferably 0.5% by volume when the hydrophilic silica is used, and the upper limit is preferably 3.5% by volume, when the hydrogenated castor oil is used. The lower limit is 1% by volume and the preferred upper limit is 4% by volume. When the amide wax is used, the preferred lower limit is 2% by volume, and the preferred upper limit is 6% by volume. When the polyethylene fiber is used, the preferred lower limit is 1% by volume, and a preferred upper limit is 2% by volume. By including a thixotropic agent within this range, the heat-dissipating member of the present invention tends to exhibit a property of softening only when heat and pressure are applied. If it is less than these lower limits, it may be softened by heating without applying pressure, and if it exceeds these upper limits, the adhesive strength may be reduced and the workability in sticking may be reduced.
[0024]
The thermoplastic resin composition may be a flame retardant such as a halogen compound, a phosphate compound, a metal hydroxide, or titanium oxide, if necessary, as long as the bag does not impair the desired elastic modulus and adhesive strength. Colorants such as carbon black and white carbon; powder surface modifiers such as silane and titanate coupling agents; antioxidants such as bisphenols and hindered phenols; chroman resins, terpene phenol resins and phenol It may contain a tackifier such as resin, rosin, terpene resin, aliphatic hydrocarbon, and alicyclic hydrocarbon.
[0025]
The method for producing the heat-dissipating member of the present invention is not particularly limited. For example, a predetermined amount of a thermoplastic resin, thermally conductive particles, and a thixotropy-imparting agent may be obtained by two-roll, three-roll, plastmill, kneader, and planetary. Mixing using a mixer, Banbury mixer, or the like, and forming the mixture into a sheet having a desired thickness by coating molding, extrusion molding, press molding, or the like.
[0026]
The heat-dissipating member of the present invention has a fixed shape at room temperature around 23 ° C., is extremely excellent in handleability, and can efficiently produce a connection structure in which the heat-generating element and the heat-dissipating element are connected.
When the temperature of the heating element of the connection structure is increased and pressure is applied at the same time, when the temperature reaches a certain temperature or higher, the glass transition phenomenon and the phase transition phenomenon accompanied by latent heat absorption such as melting rapidly occur according to the present invention. The heat dissipating member is softened, the contact area between the heat dissipating member and the heat radiating member is increased, and the thickness of the heat dissipating member is further reduced, whereby excellent heat resistance performance can be exhibited. Moreover, such a change of the heat radiating member is rapid, and occurs before the temperature of the heating element rises until it reaches a temperature that becomes a load on the heating element, so that no temperature load is applied to the heating element.
Such a connection structure in which a heat-generating member and a heat-radiator are connected by the heat-radiating member of the present invention, wherein the heat-radiating member has a thickness greater than that before the heat is generated by applying heat and pressure of the heat-generating member. A connection structure capable of reducing the pressure is also one of the present invention.
Further, the heat dissipation member of the present invention is a connection structure that connects the heating element and the heat dissipation element, wherein the heat dissipation member generates heat and pressure is applied, so that the heat dissipation member is heated before the heat generation. A connection structure whose thickness has already been reduced is also an aspect of the present invention.
[0027]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[0028]
(Example 1)
19 parts by weight of styrene-isoprene-styrene block copolymer, 80 parts by weight of dodecylbenzene, 600 parts by weight of alumina (trade name: Advanced alumina AA18 (particle size: 18 μm) and AA2 (particle size: 2 μm) manufactured by Sumitomo Chemical Co., Ltd.) And 1 part by weight of hydrophilic silica (trade name: AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) as a thixotropic agent, was mixed with a plastmill to obtain a slurry. The volume ratio of alumina in this slurry was 60%.
Further, the slurry was kneaded using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-120A) at a rotation speed of 30 rpm. The number of rotations with three rolls was two or more.
Next, a release polyethylene terephthalate (PET) film was laid on the press plate, a metal frame having a thickness of 100 μm was placed thereon, and the obtained slurry was poured into the metal frame. Next, a release PET film was placed thereon, and sandwiched from above and below by a press plate, and press-formed at room temperature. As a result, a sheet-shaped heat-dissipating member having a thickness of 100 μm and having a release PET film on both sides was obtained.
[0029]
(Example 2)
18 parts by weight of styrene-isoprene-styrene block copolymer, 77 parts by weight of dodecylbenzene, 600 parts by weight of alumina (trade name: Advanced Alumina AA18 (particle size: 18 μm) and AA2 (particle size: 2 μm) manufactured by Sumitomo Chemical Co., Ltd.) Parts and 5 parts by weight of hydrogenated castor oil (manufactured by Kusumoto Kasei Co., Ltd., trade name: Dispalon 4110) as a thixotropic agent, were mixed with a plast mill to obtain a slurry. The volume ratio of alumina in this slurry was 60%.
Further, the slurry was kneaded using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-120A) at a rotation speed of 30 rpm. The number of rotations with three rolls was two or more.
Using this slurry-like material, a sheet-like heat radiation member having a thickness of 100 μm and having a release PET film on both surfaces was obtained in the same manner as in Example 1.
[0030]
(Example 3)
18 parts by weight of styrene-isoprene-styrene block copolymer, 72 parts by weight of dodecylbenzene, 600 parts by weight of alumina (trade name: Advanced Alumina AA18 (particle size: 18 μm) and AA2 (particle size: 2 μm) manufactured by Sumitomo Chemical Co., Ltd.) And 10 parts by weight of amide wax (manufactured by Kusumoto Kasei Co., Ltd., trade name: Dispalon 6700) as a thixotropic agent, were mixed with a plast mill to obtain a slurry. The volume ratio of alumina in this slurry was 60%.
Further, the slurry was kneaded using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-120A) at a rotation speed of 30 rpm. The number of rotations with three rolls was two or more.
Using this slurry-like material, a sheet-like heat radiation member having a thickness of 100 μm and having a release PET film on both surfaces was obtained in the same manner as in Example 1.
[0031]
(Example 4)
18 parts by weight of styrene-isoprene-styrene block copolymer, 77 parts by weight of dodecylbenzene, 600 parts by weight of alumina (trade name: Advanced Alumina AA18 (particle size: 18 μm) and AA2 (particle size: 2 μm) manufactured by Sumitomo Chemical Co., Ltd.) Parts and 5 parts by weight of polyethylene fiber (trade name: Chemibest FDSS5, manufactured by Mitsui Chemicals, Inc.) as a thixotropic agent were mixed with a plastmill to obtain a slurry. The volume ratio of alumina in this slurry was 60%.
Further, the slurry was kneaded using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-120A) at a rotation speed of 30 rpm. The number of rotations with three rolls was two or more.
Using this slurry-like material, a sheet-like heat radiation member having a thickness of 100 μm and having a release PET film on both surfaces was obtained in the same manner as in Example 1.
[0032]
(Comparative Example 1)
20 parts by weight of a styrene-isoprene-styrene block copolymer, 80 parts by weight of dodecylbenzene, and 600 parts by weight of alumina (trade name: Advanced Alumina AA18 (particle size: 18 μm) and AA2 (particle size: 2 μm) manufactured by Sumitomo Chemical Co., Ltd.) The parts were mixed with a plastmill to obtain a slurry. The volume ratio of alumina in this slurry was 60%.
Further, the slurry was kneaded using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-120A) at a rotation speed of 30 rpm. The number of rotations with three rolls was two or more.
Using this slurry-like material, a sheet-like heat radiation member having a thickness of 100 μm and having a release PET film on both surfaces was obtained in the same manner as in Example 1.
[0033]
<Evaluation>
The heat-dissipating members obtained in Examples 1 to 4 and Comparative Example 1 were evaluated for thermal resistance, storage modulus, and storage stability by the following methods.
The results are shown in Table 1.
[0034]
(Measurement of thermal resistance)
The thermal resistance was measured by the measuring device shown in FIG. That is, a heat-dissipating member 2 from which a release PET film was peeled was adhered onto a cooler 1 made of aluminum, and an IC serving as a heat source was further laminated thereon, and tightened with a bolt 3 with a tightening torque of 1 N · m.
Power was supplied to the IC to supply 80 W / h, and after 60 minutes, the temperature T1 of the IC and the temperature T2 near the heat radiation member of the cooler 1 were measured. The cooler 1 is configured such that water at 23 ° C. is supplied and circulated from the thermostatic water tank 4 inside. From the measurement results, the thermal resistance was determined by the following equation.
[0035]
(Equation 1)

[0036]
(Measurement of storage modulus)
Using a dynamic analyzer RDAII (manufactured by Rheometrics), the storage elastic modulus of the heat radiating member was measured at 0.1 Hz, and the storage elastic modulus of the heat radiating member at 23 ° C. and 80 ° C. was determined.
[0037]
(Evaluation of shelf life)
As shown in FIG. 2, a heat-dissipating member from which a release PET film was peeled off on one side was attached to the side surface of a cubic block made of aluminum. The aluminum block was stored in a constant temperature bath at 80 ° C., and after one week, the flow of the heat-dissipating member was visually observed to see if it had flowed off.
[0038]
[Table 1]

[0039]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it intervenes between a heating element and a heat radiator, and has high flexibility at high temperature, adheres to a heat generator and a heat radiator, and efficiently conducts the heat generated from the heat generator to the heat radiator. A heat-dissipating member having excellent handleability at room temperature and excellent storage properties, and a connection structure formed by connecting a heat-generating element and a heat-dissipating element with the heat-dissipating member can be provided. .
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a measuring device used for measuring the thermal resistance of a heat radiation member.
FIG. 2 is a schematic diagram illustrating a method for evaluating storage stability in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cooler 2 Heat dissipation member 3 Bolt 4 Constant temperature water tank 5 Aluminum block

Claims

A heat dissipation member comprising a thermoplastic resin composition containing a thermoplastic resin, heat conductive fine particles and a thixotropic agent, and not containing a compound having a melting temperature of 40 to 100 ° C.
At 23 ° C., the storage elastic modulus at 0.1 Hz is 5000 Pa or more, and has a fixed shape,
A heat dissipating member characterized by having a storage elastic modulus at 0.1 Hz of not more than 1000 Pa at 80 ° C. and being indefinite when a constant pressure is applied.

The heat-dissipating member according to claim 1, wherein the thermoplastic resin is at least one resin selected from the group consisting of an acrylate-based copolymer, a styrene-based block copolymer, and a butyl rubber-based resin. .

The heat-dissipating member according to claim 1, wherein the thermoplastic resin composition mainly contains a solid aromatic thermoplastic resin at 23 ° C. and further contains a liquid aromatic compound at 23 ° C. 4. .

4. The heat dissipation member according to claim 1, wherein the thixotropic agent is hydrophilic silica, hydrogenated castor oil, amide wax or polyethylene fiber.

A connection structure formed by connecting a heat generator and a heat radiator with the heat radiating member according to claim 1, 2, 3, or 4,
The connection structure, wherein the heat dissipating member can be reduced in thickness as compared to before the heat generation by applying heat and pressure of a heating element.

A connection structure formed by connecting a heat generator and a heat radiator with the heat radiating member according to claim 1, 2, 3, or 4,
The connection structure, wherein the heat radiating member has a thickness already reduced before the heat generation due to a heat generated by the heat generating body and further pressure applied thereto.