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JP2005032791A - Heat dissipating member, circuit board, and semiconductor device - Google Patents

Heat dissipating member, circuit board, and semiconductor device Download PDF

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Publication number
JP2005032791A
JP2005032791A JP2003193378A JP2003193378A JP2005032791A JP 2005032791 A JP2005032791 A JP 2005032791A JP 2003193378 A JP2003193378 A JP 2003193378A JP 2003193378 A JP2003193378 A JP 2003193378A JP 2005032791 A JP2005032791 A JP 2005032791A
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Japan
Prior art keywords
heat
plate
ceramic plate
heat dissipating
heat radiating
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Pending
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JP2003193378A
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Japanese (ja)
Inventor
Tetsuya Kato
哲也 加藤
Tomoo Tanaka
智雄 田中
Masaya Ito
正也 伊藤
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Niterra Co Ltd
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NGK Spark Plug Co Ltd
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Priority to JP2003193378A priority Critical patent/JP2005032791A/en
Publication of JP2005032791A publication Critical patent/JP2005032791A/en
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    • 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
    • H01L2224/32225—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 non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1304—Transistor
    • H01L2924/1305—Bipolar Junction Transistor [BJT]
    • H01L2924/13055—Insulated gate bipolar transistor [IGBT]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1304—Transistor
    • H01L2924/1306—Field-effect transistor [FET]
    • H01L2924/13091—Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]

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  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To enable a heat dissipating member for a circuit board used for forming a semiconductor module to be improved in heat dissipating properties and insulating properties even it is used at a high voltage. <P>SOLUTION: Ceramic plates 3 and 4 are bonded on the top surface and undersurface of a heat dissipating plate 2 of metal respectively for the formation of the heat dissipating member 1. The heat dissipating member 1 can be prevented from warping by this configuration. A circuit layer 6 is formed on the top surface of the heat dissipating member 1 for the formation of a circuit board, and a semiconductor element 7 is mounted on the circuit board for the formation of a semiconductor device 11. When the semiconductor device 11 is attached to a heat sink 12 through the intermediary of the heat dissipating member 1, the trouble wherein a deterioration is caused by warpage in heat dissipating properties hardly occurs in the semiconductor device 11. The end faces of the heat dissipating plate 2 are set back from those of the ceramic plate 3 by a prescribed size through all the periphery of the heat dissipating plate 2. Therefore, the electrical insulation of the circuit layer 6 from the heat sink 12 can be improved, so that the semiconductor element 7 operates normally and stably even when it operates on a high voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、放熱部材、回路基板および半導体装置に関する。詳しくは、発熱性の電子部品が搭載される放熱部材、又は上面に回路層が形成されて放熱部材付きの回路基板をなす放熱部材、及びこのような放熱部材を用いた回路基板、さらにはこのような回路基板に半導体素子を搭載した半導体装置に関する。
【０００２】
【従来技術】
リードフレームを用いたディスクリート半導体（ＴＯ−３Ｐ、ＴＯ−２２０等）に代表される、比較的小型の半導体部品においては、放熱性を向上させるために、Ｃｕまたは、Ｃｕ合金を主成分とした厚み１ｍｍ程度の放熱板がエポキシモールドにより一体化成型されている。この放熱板の一方の面には、半導体チップ部品がはんだ付けにより実装されている。このため、放熱板は電位を持つが、放熱性を向上させるため、非絶縁の状態でヒートシンクに取り付けられるのが一般的である。
【０００３】
このような半導体部品において、感電に対する安全性等を考慮し、絶縁を望む用途向けには、例えば、これら表面に露出している通電個所の全体、及びヒートシンクヘの取り付け穴も含め、エポキシやポリイミド系の絶縁材料を皮膜形成する処理がなされる。
【０００４】
一方、ＩＧＢＴやＭＯＳＦＥＴに代表される、比較的大型のパワー半導体モジュール（以下、単にモジュールともいう）においては、高電圧に対する絶縁機能と、半導体素子が発生する熱を効率よく放熱する放熱性とが要求される。このため、このようなモジュールをなす回路基板には、酸化アルミニウム、窒化アルミニウム、及び、窒化珪素に代表されるセラミック基板の両面に金属が接合されたセラミック回路基板が用いられ、安価なＣｕ又はＣｕ−Ｆｅ合金製の放熱板上にはんだ付けによって実装する形態が一般的である。しかし、近年、前述のパワー半導体モジュールが、産業用機械から、電鉄やハイブリッドカー、および燃料電池車等に適用が拡大されるにあたって、より高い放熱性とヒートサイクルにおける信頼性の向上が強く求められている。
【０００５】
ところが、このようなパワー半導体モジュールにおいては、金属層、セラミック層、はんだ層、及び、放熱板といった、それぞれ、熱膨張率の異なる材質からなる部材で形成されている。このため、半導体等の電子部品の発熱時に、その発熱に起因する熱応力が各部に発生し、接合層、セラミック基板、及び、はんだ層等にクラックが発生する場合があった。これらのクラックは、絶縁不良による地絡事故の発生や、熱抵抗の増大を招き、これらに起因して放熱特性が大幅に悪化し、半導体素子の熱破壊を引き起こす原因となることがあった。
【０００６】
このような熱応力に起因する問題点を改善する手段として、軟質金属であるＡｌを金属板として用い、セラミックと金属板との接合部に生じる応力緩和を促す技術が提案されている（特許文献１）。 また、放熱板に熱膨張率の小さい、Ａｌ−ＳｉＣ、Ｃｕ−Ｗ、Ｃｕ−Ｍｏなどの複合材を適用する技術も提案されている（特許文献２）。
【０００７】
このような構成のモジュールは、従来のものと比較し、熱応力が緩和されることから、ヒートサイクルにおける信頼性が高い。特に放熱板に適用される、Ａｌ−ＳｉＣ、Ｃｕ−Ｗ、Ｃｕ−Ｍｏといった複合材の熱膨張率は、９〜１１ｐｐｍ／Ｋ程度であり、Ｃｕ、または、Ｃｕ−Ｆｅ合金の熱膨張率（熱膨張率＝１６〜１７ｐｐｍ／Ｋ）に比較すると小さいため、セラミック回路基板−放熱板間のはんだ層への応力を低減することができる。
【０００８】
その他の技術として、クラックが発生しやすい、セラミック回路基板と放熱板間のはんだ層自体が信頼性低下の要因である、との考え方から、セラミック回路基板と放熱板を、ハンダ付けに代えて、ろう付けにより接合する技術も提案されている（特許文献３）。
【０００９】
さらには、接合時に凹凸に形成された治具を用いて、本来、反りが発生する方向と反対方向に高い圧力をかけながら、セラミック回路基板と、放熱板を低温接合することで反りの発生を防止する技術も提案されている。
【００１０】
【特許文献１】
特許３１７１２３４号公報
【特許文献２】
特許３１８０６７７号公報
【特許文献３】
特開平９−９７８６５号公報
【００１１】
【発明が解決しようとする課題】
上記した従来技術のうち、エポキシやポリイミド系の絶縁材料で皮膜を形成する絶縁では、ヒートシンクと放熱板間に介在することになるその絶縁材料の熱伝導率が、０．５Ｗ／ｍＫ以下程度と低いため、放熱板の放熱特性が低下し、熱抵抗値が非絶縁タイプに比べると数倍以上に増大する。更には、絶縁層がモジュールの外皮表面で形成されているため、外部応力による、キズやへこみ等による絶縁劣化の可能性もあり、信頼性において十分ではない。
【００１２】
また、上述したように、比較的小型の半導体部品においては、絶縁機能及び放熱性に優れるセラミック層を放熱板上に形成することが望ましいが、放熱板の一方の面にセラミックを接合した場合には、両者の熱膨張の差から、放熱板のうち、ヒートシンクと接する面が凹となす大きな反りを生じてしまい、放熱特性が低下するという問題がある。
【００１３】
一方、軟質金属であるＡｌを金属板として適用してセラミックとその金属板の接合部に生じる応力緩和を促す方法や、放熱板に熱膨張率の小さいＡｌ−ＳｉＣや、Ｃｕ−Ｗ、Ｃｕ−Ｍｏなど複合材を適用する方式では、それらの製造工程が複雑となる。しかも、回路基板との接合においては、特殊な表面処理が必要となる。このため、Ｃｕ、又は、Ｃｕ−Ｆｅ合金からなる放熱板を用いる場合に比べると、数倍程度の高価格となりコスト的に不利である。さらに、熱膨張率の小さい複合材を放熱板として使用しているため、その熱伝導率は１５０〜２５０Ｗ／ｍＫ程度であり、Ｃｕ、Ｃｕ−Ｆｅ合金の熱伝導率（３５０〜４００Ｗ／ｍＫ）に比べて劣り、熱拡散効果を低減させ、放熱特性を悪化させるという重大な問題がある。
【００１４】
すなわち、このような複合材を放熱板として使用することで、セラミック回路基板−放熱板間のはんだ層のヒートサイクルの信頼性は向上できるものの、放熱特性は従来の形態のものよりも悪化するという重大な問題がある。
【００１５】
また、Ｃｕ、Ａｌ、又は、Ｃｕ−Ｆｅ合金製の放熱板にセラミック回路基板を接合した場合には、両者の熱膨張率の差から、放熱板の裏面が凹となす大きな反りを生ずる。この反りは、モジュール製作時には半導体チップ搭載時のはんだボイドの発生の要因となり、モジュールをヒートシンクに取り付ける際には、ヒートシンクとの接触が不十分となり、熱抵抗が増大し、放熱特性を大幅に悪化させるという問題がある。
【００１６】
さらに、圧力をかけながら、セラミック回路基板と、放熱板を低温接合する手法では、次のような問題がある。すなわち、反り量は、接合されるセラミック回路基板の材料や、放熱板の材質、厚み、及び面積によっても変化するため、加圧条件が複雑となり、実用的ではない。また、各種回路基板と放熱板間に、応力緩和を目的とした中間層を設ける構造においても、十分な反り抑制効果は得られないし、その中間層が放熱特性を悪化させるという問題がある。
【００１７】
上記したように、セラミック回路基板を用いたパワー半導体モジュールにおいて、熱膨張率の小さい放熱板を適用した場合には、ヒートサイクルの信頼性の向上は図られるものの、放熱特性や製造コストの面で問題がある。また、安価な金属を放熱板に用いて、セラミック回路基板とその放熱板とをはんだ層を介在させず、接合する方式においては、熱膨張差に起因する大きな反りが発生してしまう。
【００１８】
本発明は、こうした問題点に鑑みてなされたもので、半導体素子を放熱部材、又はその放熱部材を用いた回路基板に搭載してなる半導体装置を、その放熱部材を介して空冷方式又は水冷方式のヒートシンクに取りつけた際において、放熱部材の反りに起因する放熱特性上の問題点の解消することにある。また、その半導体素子が高電圧下で使用される場合の回路層とヒートシンク間との電気的な絶縁性を高めること、さらにはヒートサイクル特性の向上を図ることをその目的としている。
【００１９】
【課題を解決するための手段】
本発明の請求項１に係る発明は、金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面のうち、前記上部セラミック板の上面に設けられる回路層の側縁であって該上部セラミック板の側縁に沿って形成される部位に対応して存在する部位を、
前記上、下両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたことを特徴とする放熱部材である。
【００２０】
このような放熱部材においては、放熱板の両面にセラミック板を接合した構成を有している。したがって、上下のセラミック板を、例えば、同材質で同様の厚みのものとし、これらを同時にロウ付けなどによって放熱板に接合する。こうすることで、接合に起因して各部材に発生する内部応力の上下におけるアンバランスが起きないので、問題となる反りのない放熱部材となすことができる。また、上部セラミック板（以下、上のセラミック板ともいう）の上面に回路層（回路板）を形成（接合）することで、反りのない放熱部材付きの回路基板が得られるが、このような回路基板においては、反りがないことからその回路層に半導体素子をハンダ付けする際においても問題なくその接合ができる。さらに、このような半導体素子が搭載されたモジュールにおいても、反りがないため、その下部セラミック板（以下、下のセラミック板ともいう）の下面を介して、水冷方式又は空冷方式のヒートシンク（冷却部材）の取り付け面に密着状にして取付けることができる。このため、効率良く放熱できることから、発熱する電子部品の放熱特性の向上を図ることができる。
【００２１】
なお、放熱部材のヒートシンクに対する取り付けは、放熱部材の両側（両端）又は四つの角寄り部位においてネジ部材をネジ締めすることによるのが普通である。したがって、下のセラミック板の下面に許容される微小な反り（１０μｍ／ｃｍ以下の反り量とされる）を付与する場合には、そのネジ締めによる同下面のヒートシンク取付け面への密着が図られるように、同下面には下向きに凸となす反りが付与されるようにするのが好ましい。なお、放熱性向上の手段として、或いは、ヒートシンクとの密着性の向上のため、下部セラミック板のヒートシンクと対面する面（下面）には金属層を形成してもよい。さらに、放熱板は、セラミック板との接合性の向上、及び防錆等のため、メッキ処理や、メタライズ処理を施したものを用いるとよい。なお、放熱板の材質は、Ｃｕ、Ａｌ、Ｎｉ、Ｗ、又はＭｏ、或いはこれらのいずれかを主成分とする合金が例示される。また、セラミック板の材質としては、窒化珪素、窒化アルミニウム、酸化アルミニウム、又は炭化珪素が例示される。
【００２２】
請求項１に係る放熱部材においては、上記した効果に加えて、次のような特有の効果もある。すなわち、上部セラミック板の上面に、回路層（回路板）を形成して回路基板とし、その回路層に半導体素子を搭載してモジュールとし、このモジュールをなす放熱部材の下部セラミック板の下面を介してヒートシンクの取付け面に接合する。このとき、請求項１に係る放熱部材においては、前記放熱板の側面のうち、前記上部セラミック板の上面に設けられる回路層の側縁であって該上部セラミック板の側縁に沿って形成される部位に対応して存在する部位を、前記上、下両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させている。ここで、「回路層の側縁」とは、回路層のうち上部セラミック板の側縁寄りの端をいい、「上部セラミック板の側縁」とは、上部セラミック板の上面の外周の端をいう。そして、「上部セラミック板の側縁に沿って」とは、上部セラミック板の上面の外周の端と平面視において一致して（側面が面一であること）、という意味、及び略一致して、という意味である。
【００２３】
このように、請求項１に係る放熱部材においては、上部セラミック板の上面の全面に回路層が形成されたとしても、その回路層と、ヒートシンクとの間における絶縁が問題となる部位の絶縁沿面距離、すなわち回路層とヒートシンクとの間において、露出するセラミックの表面に沿う絶縁のための距離（最短の距離）が、両セラミック板の側面における厚さ方向に沿う寸法より大きくなる。つまり、絶縁が問題となる部位の絶縁沿面距離は、この両セラミック板の厚さの合計寸法に加えて、放熱板の側面がセラミック板の側面より内側に存在している分、大きく確保されている。
【００２４】
したがって、本発明の放熱部材を用い、その上部セラミック板の上面の全面に回路層を設けて回路基板として半導体素子を搭載し、その放熱部材の下面を介して、金属製のヒートシンクの取付け面に取付けたときは、回路層とシートシンクとの絶縁沿面距離は十分確保される。このため、回路層に、例えば２．５ｋＶといった高電圧の電流が流れたとしても、回路層とヒートシンクとの間において放電が発生することを有効に防止できる。因みに、必要な絶縁沿面距離は、例えば、回路層に流れる電圧が２．５ｋｖの場合には、３ｍｍ以上といわれているが、このような寸法は容易に確保できる。このように、本発明においては、上記の構成により、絶縁沿面距離を大きく確保できるため、電気的な絶縁効果が極めて高い放熱部材となすことができる。その結果、放熱特性の向上に加えて、半導体装置を正常に安定して作動させることができる。なお、高電圧に絶え得る絶縁沿面距離を確保する手段としては、請求項２〜９に係る発明がある。
【００２５】
請求項２に係る発明は、金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面を、その周囲全体にわたって、前記上、下両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたことを特徴とする放熱部材である。
【００２６】
このように形成したことで、上部セラミック板の上面の全面に回路層が形成される場合でも、問題なく絶縁沿面距離を確保することができる。つまり、請求項１に記載の放熱部材においては、絶縁沿面距離を確保する必要のある部位に対応させて、放熱板の側面を、上、下両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたものである。このため、請求項１に係る発明では、形成される回路層のパターンを考慮して、放熱板の側面をセラミック板の側面よりも内側に存在させる必要があるのに対して、請求項２に係る発明ではその必要がない。
【００２７】
請求項３に係る発明は、請求項１又は２において、前記両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたことに代えて、前記両セラミック板の側面よりも内側に存在させたことを特徴とする放熱部材である。絶縁沿面距離の確保のため、放熱板の側面を、このように上下両セラミック板の側面よりも内側に存在させたため、絶縁沿面距離の確保がより容易となる。また、両セラミック板を同材質、同サイズのものとして容易に共用することができる。なお、このように形成する場合においては、請求項４〜６のいずれかのものとすると一層よい。
【００２８】
請求項４に係る発明は、前記セラミック板の側面よりも内側に存在させた前記放熱板の側面を、前記上部セラミック板の上面に垂直な平面で切断した断面において外向きに凸となす円弧状又は多角形状に形成したことを特徴とする請求項３に記載の放熱部材である。
【００２９】
このように、外向きに凸となす円弧状又は多角形状に形成したものとすることで、放熱板の側面に電荷の集中が起き易い鋭角部がなくなるため、放電の発生の防止効果が一層高いものとなり、より高い高電圧にも使用できることになる。
【００３０】
請求項５に係る発明は、前記セラミック板の側面よりも内側に存在させた前記放熱板の側面と交わる該放熱板の上面及び下面とのなすそれぞれの角に、面取りを形成したことを特徴とする請求項３に記載の放熱部材である。このようにしても、請求項４に記載の放熱部材と同様の効果が得られる。
【００３１】
請求項６に係る発明は、前記セラミック板の側面よりも内側に存在させた前記放熱板の側面を、前記上部セラミック板の上面に垂直な平面で切断した断面において凹溝状としかつその凹溝における上下の溝壁のそれぞれを、凹溝開口に向うにしたがって薄くなるように形成したことを特徴とする請求項３に記載の放熱部材である。
【００３２】
このようにすることで、放熱板の側面は、セラミック板との接合端に近づくほどその厚みが薄くなるため、セラミック板の側面寄り部位（エッジ寄り部位）における内部応力の発生を緩和或いは低減できる。このため、同部位近傍におけるセラミックの割れ等の破損防止が図られる。
【００３３】
請求項７に係る発明は、前記セラミック板の側面よりも内側に存在させた前記放熱板の側面を、絶縁材で被覆したことを特徴とする請求項１〜６のいずれか１項に記載の放熱部材である。
【００３４】
請求項７に係る発明のように、前記放熱板の側面を、絶縁材（絶縁皮膜）で被覆したものとすることで、より一層、絶縁沿面距離を大きくできる。また、このように放熱板の側面を、絶縁材で被覆したものとする場合には、請求項８又は９に記載の放熱部材のように、前記放熱板の側面を前記セラミック板の側面よりも内側に存在させることなくその被覆をすることとしてもよい。なお、絶縁材としては、ゴム（シリコンゴム等）又は樹脂（ポリイミド樹脂等）を用い、これを塗布等することで被覆すればよい。
【００３５】
請求項８に係る発明は、金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面のうち、前記上部セラミック板の上面に設けられる回路層の側縁であって該上部セラミック板の側縁に沿って形成される部位に対応して存在する部位を絶縁材で被覆したことを特徴とする放熱部材である。
【００３６】
請求項９に係る発明は、金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面をその周囲全体にわたって絶縁材で被覆したことを特徴とする放熱部材である。
【００３７】
また、請求項１０に係る本発明は、請求項１〜９のいずれか１項に記載の放熱部材における上部セラミック板の上面に回路層を形成したことを特徴とする回路基板である。
【００３８】
さらに、請求項１１に係る本発明は、請求項１〜９のいずれか１項に記載の放熱部材の上部セラミック板の上面に、または、請求項１０に記載の回路基板の上面に、半導体素子を搭載したことを特徴とする半導体装置である。
【００３９】
【発明の実施の形態】
第１の実施の形態
以下、本発明にかかる放熱部材の第１の実施の形態（例）について、図１〜３に基づいて詳細に説明する。この放熱部材１は、全体としてみると、一定厚さの矩形平板形状を呈しており、金属製（例えば、Ｃｕ（銅）製）で、一定厚さの矩形をなす放熱板２の上、下の両面に、一定厚さのセラミック板（例えば、窒化珪素板）３、４が例えば活性ロウ（図示せず）によるロウ付けで接合されて一体化されている。ここに、放熱板２はその厚さが例えば３ｍｍとされ、両セラミック板３、４は厚さが、ともに０．２５ｍｍとされている。なお、活性ロウとしては、例えばＣｕ−Ｓｎ系活性金属ロウが使用される。
【００４０】
ただし、本形態では、放熱板２の側面２ａと下のセラミック板４の側面４ａとは、面一とされているが、上のセラミック板３の側面（エッジ）３ａは、放熱板２の側面２ａより、側面の周囲全体にわたって外側に一定寸法（Ｓ）突出している。すなわち、本形態では、放熱板２の側面２ａを、その周囲全体にわたって上のセラミック板３の側面３ａよりも一定寸法Ｓだけ内側に引き下がって存在させている。この引き下がり寸法Ｓは、例えば、２．５ｍｍとされている。また、放熱板２は、平面が例えば、縦横、３２ｍｍ、９０ｍｍとされている。なお、平面視において、両端寄り部位に、取付け用の貫通孔５が形成されている。
【００４１】
このような本形態の放熱部材１は、セラミック板３、４のうち、放熱板２に接する面３ｂ、４ｃにＣｕ−Ｓｎ系活性金属ペースト（活性ロウ）を印刷しておいて、各部材を重ね、所定の錘を載せて例えば真空雰囲気下にて所定の温度に加熱して活性ロウを溶融し、その後、冷却することで形成される。このとき、放熱板２とセラミック板３、４とにおけるヤング率及び熱膨張係数の相違に基づき、接合、冷却後においては、各部材に内部応力が発生するが、このような積層構造を有するため、上下においてその応力にアンバランスを発生させない。したがって、問題となる反りのない放熱部材１となすことができる。
【００４２】
そして、このような放熱部材１は、その上部セラミック板３の上面３ｃに、図３に示したように回路層６を設けることで回路基板１０となる。なお、回路層６を形成する場合には、例えば、上部セラミック板３の上面３ｃにも活性ロウをスクリーン印刷しておき、その上に回路層形成用のＣｕ板を重ねて、上下のセラミック板３、４と同時に接合し、その後、所望とする回路パターンにエッチング処理することで形成される。また、このような放熱部材１は、図４に示したように、同上部セラミック板３の上面３ｃに、回路層６を設けるとともに半導体素子７をハンダ層８を介して搭載することで半導体装置１１が形成される。そして、この形成においては次のようである。すなわち、このような放熱部材１の上部セラミック板３の上面３ｃに回路層６を形成する。そして、その回路層６に半導体素子７をハンダ付けする際においては、放熱部材１に問題となる反りがないことから、半導体素子７を問題なく、ハンダ付けできる。
【００４３】
そして、このように形成されたモジュールは、図５に示したように、下のセラミック板４の下面４ｂをヒートシンク（冷却部材）１２に、熱伝導性のグリース１３を介在させ、ネジ部材１４を貫通孔５に通してねじ込むことで取付けられるのであるが、この取付けにおいても、問題となる反りがなく、モジュールとヒートシンク１２との密着性が保たれる。したがって、その使用に際して半導体から発熱する熱は、回路層６及び放熱部材１を介してヒートシンク１２に効率良く伝達されるため、高い冷却効果が得られる。
【００４４】
さらに、このような基本的効果に加えて次のような特有の効果も得られる。すなわち、このようにモジュールとされてヒートシンク１２に取付けられた際において、回路層６に高電圧の電流が流れる場合においては、その回路層６とヒートシンク１２との電気的な絶縁の確保が重要となる。一方、本形態の放熱部材１においては、放熱板２の上下にセラミック板（絶縁板）３、４があるというだけでなく、放熱板２の側面２ａが上のセラミック板３の側面３ａよりも内側に存在している。このため、上下のセラミック板３、４の側面３ａ、４ａにおける上下の各寸法（各セラミック板３、４の厚さ）３Ｅ、４Ｅに加えて、上のセラミック板３が放熱板２から相対的に寸法Ｓだけ突出しているため、その突出寸法Ｓ分、絶縁沿面距離を大きく確保している。したがって、絶縁沿面距離は、例えば、各セラミック板３、４の厚さ３Ｅ、４Ｅを加算した寸法に加えて、上のセラミック板３の下面３ｂが、放熱板２の側面２ａから突出している寸法Ｓ分だけ広く確保されている。このため、回路層６に、例えば２．５ｋＶといった高電圧の電流が流れたとしても、回路層６とヒートシンク１２間における放電の発生を有効に防止できるという効果がある。すなわち、本形態においては、回路層６が上部セラミック板３の上面３ｃの全面に形成されても、その回路層６とヒートシンク１２との絶縁沿面距離は、各セラミック板３、４の厚さ３Ｅ、４Ｅの合計寸法に加えて寸法Ｓが加算されているため、放電の発生もなく、上面の回路層６に接合した半導体素子７等の電子部品を正常に安定して作動させることができるという効果がある。
【００４５】
なお、上記の放熱部材１の製造におけるロウ付けにあたっては、カーボン製ジグなど、耐熱性のあるジグを用いて、各部材を同図の配置となるように位置決めしつつ重ねてロウ付けすればよい。また、放熱板２に、上のセラミック板３と同じ平面形状、寸法のものを用いてロウ付けした後、エッチング処理することで、放熱板２の側面２ａを上部セラミック板３の側面３ａより内側に存在させるようにしてもよい。なお、前記形態では、セラミック板を窒化珪素製としたが、窒化アルミニウム、酸化アルミニウムなどを用いてもよい。また、放熱板２の材料としては、Ａｌ（アルミニウム）或いはＡｌ合金など、熱伝導性の高い金属から適宜のものを選択して用いればよい。なお、このように放熱板２をＡｌ製又はＡｌ合金製とする場合には、セラミック板における接合面に、例えば、Ｔｉ、Ｍｏ、Ｎｉの順に各金属層（例えば各１００ｎｍ厚さ）を蒸着によって形成しておき、Ａｌ−Ｓｉ系ロウ材でロウ付けすればよい。
【００４６】
前記した実施の形態においては、放熱板２の側面２ａの周囲全体を、上のセラミック板３の側面３ａよりも内側に存在させたため、回路層６を全面に形成しても、或いはその回路層６のパターン或いは形成エリアに関係なく、絶縁沿面距離を確保できる。ただし、このようにその側面２ａの全体を内側に存在させることは必ずしも必要とされない。すなわち、本発明においては、放熱板２の側面２ａの周囲のうち、絶縁沿面距離が問題とならない部位、例えば、図２中、１点鎖線で示した部位のうち、形成される回路層６の側縁が上部セラミック板３の側縁（側面）３ａより十分に内側に位置している部位（図２中のＡの部位）については、絶縁沿面距離は既に十分に確保されている。このため、このような部位を除いた部位、つまり、放熱板２の側面２ａのうち、上部セラミック板３の上面３ｃに設けられる回路層６の側縁であって上部セラミック板３の側縁に沿って形成される部位（図２中のＢの部位）に対応して存在する部位を、上、下両セラミック板３、４のうちの少なくとも一方のものの側面よりも内側に存在させれば十分である。以下、本発明の放熱部材１において、絶縁沿面距離を確保する構成の別の実施の形態について説明する。
【００４７】
第２の実施の形態
図６は、本発明にかかる放熱部材の第２の実施の形態を示したものである。ただし、この放熱部材２１は、上記した第１の実施の形態において、上のセラミック板３に代えて、下のセラミック板４の側面４ａを放熱板２の側面２ａから所定量Ｓ突出させた点のみが相違するだけであり、本質的相違はないことから、同一の部位には、同一の符号を付すに止め、詳細な説明は省略する。以下においても同様とする。すなわち、このようにしても、同様に絶縁沿面距離を長くできる。
【００４８】
また、図７は、本発明にかかる放熱部材の第３の実施の形態を示したものである。この放熱部材３１は、放熱板２の側面２ａを、上、下の両セラミック板３、４の側面３ａ、４ａよりも内側に存在させたものである。このものにおいては、上記の各形態におけるものと同様の突出量Ｓとした場合には、絶縁沿面距離をさらに大きく確保できるため、より高電圧の電流に対しても、十分な放電防止効果が期待される。一方、このものにおいては、上記した形態と同様の絶縁沿面距離を確保する場合には、図示から明らかなように、両セラミック板３、４の突出量を半分にできる。すなわち、セラミック板の突出を小さくできる分、放熱部材２のサイズを小さくするとともに、その突出部分の割れ等の破損の防止が図られる。
【００４９】
図８は、本発明にかかる放熱部材の第４の実施の形態を示したものである。この放熱部材４１は、第３の実施の形態において、放熱板２の側面２ａを、上部セラミック板３の上面３ｃに垂直な平面で切断した断面において外向きに凸となす（膨出状）円弧状に形成したものである。このものにおいても、前記形態と同様の効果があるが、さらに、このものでは、放熱板２の側面２ａに鋭角をなす角がないため、電荷の集中を防止できる。このため、一層、優れた放電防止効果が得られる。なお、図示はしないが、このような外向きに凸となす円弧状のものに代えて、外向きに凸となす多角形状に形成しても同様の効果がある。また、外向きに凸となす円弧状とする場合には、その半径を放熱板２の厚みの半分とするか、又はその半分より大きい半径として、円弧状をなすように設定するとよい。また、多角形状にする場合にはなるべく多くの角のあるものにするのが好ましい。このような放熱部材４１を上記したように回路基板として、或いは半導体素子７を搭載してヒートシンク１２に取付けて使用されるときには、電荷の集中を防止できるため、放電の発生の防止効果が一層高いものとなる。
【００５０】
図９は、本発明にかかる放熱部材の第５の実施の形態を示したものであり、前記形態の変形例とでも言うべきものである。すなわち、この放熱部材５１では、放熱板２の側面２ａと交わる該放熱板２の上面２ｃ及び下面２ｂとのなすそれぞれの角に、面取りを形成したものである。このものにおいても、放熱板２の側面２ａに鋭角をなす角ができないため、電荷の集中が防止できるなど、前記の第４の実施の形態のものと同様の効果がある。さらに、このものでは、面取りとしたことで、その形成、製造が容易となるといった、製造上の効果もある。なお、図示はしないが、このような面取りは、傾斜面取りに代えて、アール面取り（円弧状面取り）としても同様の効果が得られる。
【００５１】
図１０は、本発明にかかる放熱部材の第６の実施の形態を示したものである。この放熱部材６１は、放熱板２の側面２ａを、上部セラミック板３の上面３ｃに垂直な平面で切断した断面において、凹溝状としかつその凹溝における上下の溝壁２ｋのそれぞれを、凹溝開口に向うにしたがって薄くなるように形成したものである。同図のものでは、放熱板２の側面２ａが同断面において、外向きに凹となす円弧状に形成されており、上下のセラミック板３、４の側面３ａ、４ａ寄り部位に近接するほど、接合された放熱板２の厚みが薄くなるように形成されている。このため、放熱板２との接合後におけるセラミック板３、４の側面３ａ、４ａ寄り部位における内部応力を緩和ないし低減できることから、セラミック板における同部位近傍の剥離或いは破損防止効果があり、接合の信頼性が高められる。
【００５２】
なお、図１１は、本発明にかかる放熱部材の第７の実施の形態を示したものであり、前記形態の変形例とでもいうべきものである。この放熱部材７１は、同断面において、放熱板２の側面２ａを、外向きに凹となす多角形に形成したものであるが、このようにしても同様の効果が得られる。なお、本例のものも含め、放熱板２の側面２ａを外向きに凸形状又は凹形状とする場合には、接合前に又は後で所定の形状に研削等により形成すればよい。ただし、凹とする場合には、放熱部材１においてその側面をブラスト処理することでも形成できる。
【００５３】
図１２は、本発明にかかる放熱部材の第８の実施の形態を示したものである。この放熱部材８１は、図７に示した実施の形態のものにおいて、放熱板２の側面２ａを絶縁材８２で被覆したものである。このように、放熱板２の側面２ａを、絶縁材（絶縁皮膜）８２で被覆したものとすることで、さらに絶縁沿面距離を大きくできる。このため、回路層とヒートシンク間の絶縁が確実に保持される。また、このように放熱板２の側面２ａを、絶縁材８２で被覆したものとする場合には、放熱板２の側面２ａをセラミック板の側面よりも内側に存在させなくともよい。
【００５４】
図１３は、その１例を示したものである。このものは、上下の両セラミック板３、４と放熱板２に、同一平面形状、同一平面寸法のものを用い、これらの側面３ａ、４ａ、２ａを揃えて接合し、その後で、放熱板２の側面２ａを覆う形で絶縁材８２で被覆したものである。すなわち、このものは、放熱板２の側面２ａを、上下のセラミック板３、４の側面３ａ、４ａと面一としておき、放熱板２自体の側面２ａが露出しないように、絶縁材８２で被覆したものである。このものにおいても、絶縁沿面距離を長くできる。なお、このような形態においても、放熱板２の側面２ａの周囲全体を絶縁材で被覆、形成する必要は必ずしもなく、絶縁沿面距離が問題となる部位のみ、その側面を絶縁材で被覆すればよい。ただし、放熱板２の側面２ａの周囲全体を絶縁材で被覆しておくのが、より好ましい。なお、絶縁材８２としては、特に限定されるものではないが、シリコンゴム又はポリイミド樹脂等、耐熱性の高いゴム、樹脂などを用い、これを塗布等することで被覆すればよい。
【００５５】
さて次に、上記した各形態１〜７の放熱部材（実施例１〜７）を作り、上のセラミック板３の上面３ｃに回路層６を形成し、その回路層６に半導体素子７をハンダ付けにより搭載してモジュールとし、回路層全面と下のセラミック板４の下面４ｂの全面に電極を接触させて、高電圧の電流を流して両セラミック板間の絶縁抵抗試験を実施し、絶縁沿面距離の増大による効果（絶縁性能）の確認をした。
【００５６】
ただし、この試験には絶縁耐電圧試験器を用い、試験電圧は、１ＫＶ〜４．５ＫＶとし、印加時間は１分間とした。結果は、表１に示したとおりである。なお、放熱板２は、Ｃｕ製で、厚さは３ｍｍ、上下のセラミック板３、４は窒化珪素製で、厚さ０．２５ｍｍ、回路層６はＣｕ製で、厚さは、０．４ｍｍとし、上のセラミック板３の上面の全面に形成した。なお、比較例１は、図１４に示したように、放熱板２の側面２ａと上下のセラミック板３、４の側面３ａ、４ａを一致させた（揃えた）点のみが、実施例１〜７のものと異なるだけである。また、比較例２は図１５に示したように、放熱板２の側面２ａを上下のセラミック板３、４の側面３ａ、４ａより、外側に１．０ｍｍ突出させた点のみが、実施例１〜７のものと異なるだけである。
【００５７】
また、実施例１〜３のもの（図１、図６、図７）は、上、又は下のセラミック板３、４の側面３ａ、４ａから放熱板２の側面２ａまでの引き下がり量Ｓは１ｍｍである。
実施例４〜７における引き下がりは次のようである。
実施例４（図８参照）は、放熱板２の側面２ａを外向き凸となす円弧状断面としたもので、上のセラミック板３の下面３ｂ及び下のセラミック板４の上面４ｃに接する位置における放熱板２の引き下がり量Ｓ４が２ｍｍとなるように、半径１．５ｍｍで外向き凸となす円弧状断面としたものである。放熱板２の厚さは３ｍｍである。これにより、放熱板２の側面２ａの中間高さ部位の外端は上下のセラミック板３、４の側面３ａ、４ａから０．５ｍｍ引き下がっている。
実施例５（図９参照）は、放熱板２の側面２ａと交わる該放熱板２の上面２ｃ及び下面２ｂとのなすそれぞれの角に面取りを形成したもので、上のセラミック板３の下面３ｂ及び下のセラミック板４の上面４ｃに接する位置における放熱板２の引き下がり量Ｓ５が２ｍｍとなるように、水平に対する角度θが３０度で、水平幅１．７３ｍｍ、高さ１．０ｍｍをなす面取りを付与したものである。これにより、放熱板２の側面２ａは上下のセラミック板３、４の側面３ａ、４ａから約０．２７ｍｍ引き下がっている。
実施例６（図１０参照）は、放熱板２の側面２ａを外向きに凹となす円弧状に形成したもので、上のセラミック板３の下面３ｂ及び下のセラミック板４の上面４ｃに接する位置における放熱板２の引き下がり量Ｓ６が１ｍｍとなるようにし、そこから、半径１．５ｍｍで外向き凹となす円弧状断面としたものである。これにより、セラミック板３、４の側面３ａ、４ａから最大深さが２．５ｍｍの凹溝となっている。
実施例７（図１１参照）は、放熱板２の側面２ａを外向きに凹となす台形状に形成したもので、上のセラミック板３の下面３ｂ及び下のセラミック板４の上面４ｃに接する位置における放熱板２の引き下がり量Ｓ７が１ｍｍとなるように、そこから、溝深さ２ｍｍで、溝底の幅２ｍｍ、開口幅３ｍｍの底が狭い台形溝としたものである。
なお、いずれも、放熱板２の周囲の側面全体について内側に存在させた。
【００５８】
【表１】

Figure 2005032791
【００５９】
表１に示したように、１ＫＶ、１．５ＫＶでは、試験を実施したいずれの実施例１〜３、及び比較例１、２においても、絶縁の問題は発生せず、ＯＫ（合格）であった。また、２．５ＫＶでは、本発明の実施例１〜７においては、いずれも絶縁の問題は発生しなかったのに対し、比較例１、２では放電による絶縁不良が発生し、ＮＧ（不合格）であった。そして、３．５ＫＶでは、本発明の実施例３〜７においては、絶縁の問題は発生しなかったのに対し、実施例、１、２、及び比較例１、２において、放電による絶縁不良が発生した。さらに４ＫＶでは、本発明の実施例４、５においては絶縁の問題は発生しなかったのに対し、実施例、１〜３、６、７において、放電による絶縁不良が発生した。なお、表中の「実施せず」は、試験をしなかったことを表している。
【００６０】
この試験結果から、本発明の放熱部材によれば、絶縁特性が確実に高められるとともに、２．５ＫＶであればいずれのものでも問題ないことが分かる。一方、３．５ＫＶといった高電圧に対しては、放熱板２の側面２ａを、上下両セラミック板３、４の側面３ａ、４ａより内側に存在させるのが好ましいことがわかる。さらに、放熱板２の側面２ａを外向きに凸となす円弧または多角形状とした場合には、４ＫＶといった高電圧でも問題がなく、最も好結果が得られることが判明した。これらのことは、とりもなおさず本発明の放熱部材の効果を実証するものである。
【００６１】
さらに、実施例６、７のものについて、熱サイクル試験をして、セラミック板の剥離の有無について確認した。ただし、熱サイクル試験は、−４０度〜ＲＴ（室温）〜３５０度を１サイクルとし、各温度において３０分間保持した。結果は、表２に示したとおりである。なお、放熱板、セラミック板間の界面の剥離は、１０サイクル実施ごとに、その発生の有無を超音波探傷装置で評価した。
【００６２】
【表２】
Figure 2005032791
【００６３】
表２に示したように、実施例６、７のものについては、７０サイクルまで、「剥離なし」、であったが、比較例１、２では、３０サイクルで、剥離の発生がみられた。これより、実施例６、７のもののように、放熱板２の側面２ａを形成することで、ヒートサイクルに対し、高い信頼性が得られることも実証された。すなわち、このようにすることで、確実にセラミック板に発生する応力の緩和或いは低減が図られる。
【００６４】
本発明は上記した各実施の形態のものに限定されるものではなく、適宜に設計変更して具体化できる。また、放熱板の材質、寸法（厚み等）、セラミック板の材質、寸法（厚み等）、あるいはこれらの接合法についても、適宜に変更して具体化すればよい。
【００６５】
【発明の効果】
以上の説明から明らかなように、本発明の放熱部材によれば、反りの発生を有効に防止できる。このため、本発明の放熱部材を使用して回路基板を形成し、さらに半導体素子を搭載して半導体装置とし、これをその放熱部材を介して空冷方式又は水冷方式のヒートシンクに取りつけた際においては、反りに起因する放熱特性上の問題を解消できる。また、その回路層とヒートシンク間との電気的な絶縁性を高めることができるため、高電圧下で使用される半導体素子を正常に安定して作動させることができる。さらに、ヒートサイクル特性の向上を図ることもできるため、信頼性の高い半導体装置となすことができる。
【図面の簡単な説明】
【図１】本発明にかかる放熱部材の第１の実施の形態の側面図、及び要部拡大断面図。
【図２】図１の放熱部材の平面図。
【図３】図１の放熱部材の上面に回路層を形成してなる回路基板の側面図。
【図４】図１の放熱部材の上面に回路層を形成して回路基板とするともに、その上面に半導体素子をハンダ付けしてなる半導体装置の側面図。
【図５】半導体装置をヒートシンクに取付けた状態の断面図。
【図６】本発明にかかる放熱部材の第２の実施の形態の断面要部拡大図。
【図７】本発明にかかる放熱部材の第３の実施の形態の断面要部拡大図。
【図８】本発明にかかる放熱部材の第４の実施の形態の断面要部拡大図。
【図９】本発明にかかる放熱部材の第５の実施の形態の断面要部拡大図。
【図１０】本発明にかかる放熱部材の第６の実施の形態の断面要部拡大図。
【図１１】本発明にかかる放熱部材の第７の実施の形態の断面要部拡大図。
【図１２】本発明にかかる放熱部材の第８の実施の形態の断面要部拡大図。
【図１３】本発明にかかる放熱部材の第９の実施の形態の断面要部拡大図。
【図１４】放熱部材の比較例１を示す断面要部拡大図。
【図１５】放熱部材の比較例２を示す断面要部拡大図。
【符号の説明】
１、２１、３１、４１、５１、６１、７１、８１、９１ 放熱部材
２ 放熱板
２ａ 放熱板の側面
２ｃ 放熱板の上面
２ｂ 放熱板の下面
３ 上部セラミック板
３ａ 上部セラミック板の側面
３ｃ 上部セラミック板の上面
３ｂ 上部セラミック板の下面
４ 下部セラミック板
４ａ 下部セラミック板の側面
４ｃ 下部セラミック板の上面
４ｂ 下部セラミック板の下面
６ 回路層
１０ 回路基板
１１ 半導体装置
１２ ヒートシンク
８２ 絶縁材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat dissipation member, a circuit board, and a semiconductor device. Specifically, a heat radiating member on which heat-generating electronic components are mounted, a heat radiating member having a circuit layer formed on the upper surface to form a circuit board with a heat radiating member, a circuit board using such a heat radiating member, and this The present invention relates to a semiconductor device in which a semiconductor element is mounted on such a circuit board.
[0002]
[Prior art]
In a relatively small semiconductor component typified by a discrete semiconductor (TO-3P, TO-220, etc.) using a lead frame, in order to improve heat dissipation, the thickness is mainly composed of Cu or a Cu alloy. A heat sink of about 1 mm is integrally molded by an epoxy mold. A semiconductor chip component is mounted on one surface of the heat sink by soldering. For this reason, although a heat sink has an electric potential, in order to improve heat dissipation, it is common to attach to a heat sink in a non-insulated state.
[0003]
In such semiconductor parts, considering the safety against electric shock, etc., for applications where insulation is desired, for example, the entire energized location exposed on these surfaces and the mounting holes for heat sinks, epoxy and polyimide A process of forming a film of the insulating material of the system is performed.
[0004]
On the other hand, relatively large power semiconductor modules (hereinafter also simply referred to as modules) represented by IGBTs and MOSFETs have an insulating function against high voltages and heat dissipation that efficiently dissipates heat generated by semiconductor elements. Required. For this reason, a ceramic circuit board in which metal is bonded to both surfaces of a ceramic substrate typified by aluminum oxide, aluminum nitride, and silicon nitride is used as a circuit board forming such a module. A form of mounting on a heat sink made of -Fe alloy by soldering is common. However, in recent years, when the application of the power semiconductor module described above is expanded from industrial machinery to electric railways, hybrid cars, and fuel cell vehicles, there is a strong demand for higher heat dissipation and improved reliability in heat cycles. ing.
[0005]
However, such a power semiconductor module is formed of members made of materials having different coefficients of thermal expansion, such as a metal layer, a ceramic layer, a solder layer, and a heat sink. For this reason, when an electronic component such as a semiconductor generates heat, thermal stress due to the generated heat is generated in each part, and cracks may occur in the bonding layer, the ceramic substrate, the solder layer, and the like. These cracks may cause ground faults due to poor insulation and increase in thermal resistance, resulting in a significant deterioration in heat dissipation characteristics and causing thermal destruction of the semiconductor element.
[0006]
As a means for improving such problems caused by thermal stress, a technique has been proposed in which Al, which is a soft metal, is used as a metal plate to promote stress relaxation that occurs at the joint between the ceramic and the metal plate (Patent Literature). 1). Moreover, the technique which applies composite materials, such as Al-SiC, Cu-W, Cu-Mo, with a small thermal expansion coefficient to a heat sink is also proposed (patent document 2).
[0007]
The module having such a configuration is more reliable in heat cycle because the thermal stress is relieved as compared with the conventional module. In particular, the thermal expansion coefficient of a composite material such as Al—SiC, Cu—W, and Cu—Mo applied to a heat sink is about 9 to 11 ppm / K, and the thermal expansion coefficient of Cu or Cu—Fe alloy ( Therefore, the stress on the solder layer between the ceramic circuit board and the heat sink can be reduced.
[0008]
As another technology, from the idea that the solder layer itself between the ceramic circuit board and the heat sink is prone to decrease in reliability, and the ceramic circuit board and the heat sink are replaced by soldering. A technique for joining by brazing has also been proposed (Patent Document 3).
[0009]
In addition, using a jig formed in irregularities at the time of bonding, while applying high pressure in the direction opposite to the direction in which warpage originally occurs, warping is generated by low-temperature bonding the ceramic circuit board and the heat sink. Techniques for preventing it have also been proposed.
[0010]
[Patent Document 1]
Japanese Patent No. 3171234
[Patent Document 2]
Japanese Patent No. 3180677
[Patent Document 3]
Japanese Patent Laid-Open No. 9-97865
[0011]
[Problems to be solved by the invention]
Among the above-described conventional techniques, in the insulation in which a film is formed with an epoxy or polyimide insulating material, the thermal conductivity of the insulating material that is interposed between the heat sink and the heat sink is about 0.5 W / mK or less. Since it is low, the heat dissipation characteristic of the heat sink is lowered, and the thermal resistance value is increased several times more than that of the non-insulated type. Furthermore, since the insulating layer is formed on the outer surface of the module, there is a possibility of deterioration of insulation due to scratches or dents due to external stress, which is not sufficient in reliability.
[0012]
In addition, as described above, in a relatively small semiconductor component, it is desirable to form a ceramic layer having excellent insulating function and heat dissipation on the heat sink, but when ceramic is bonded to one surface of the heat sink. However, due to the difference in thermal expansion between the two, there is a problem that a large warp in which the surface of the heat radiating plate that comes into contact with the heat sink becomes concave, resulting in a deterioration in heat radiation characteristics.
[0013]
On the other hand, Al, which is a soft metal, is applied as a metal plate to promote relaxation of stress generated at the joint between the ceramic and the metal plate, Al-SiC having a low coefficient of thermal expansion, Cu-W, Cu- In the method of applying a composite material such as Mo, the manufacturing process thereof is complicated. In addition, a special surface treatment is required for bonding to the circuit board. For this reason, compared with the case where the heat sink which consists of Cu or a Cu-Fe alloy is used, it becomes about several times as expensive and is disadvantageous in cost. Furthermore, since a composite material having a low coefficient of thermal expansion is used as a heat sink, its thermal conductivity is about 150 to 250 W / mK, and the thermal conductivity of Cu and Cu—Fe alloys (350 to 400 W / mK). There is a serious problem that the thermal diffusion effect is reduced and the heat dissipation characteristics are deteriorated.
[0014]
That is, by using such a composite material as a heat sink, the reliability of the heat cycle of the solder layer between the ceramic circuit board and the heat sink can be improved, but the heat dissipation characteristics are worse than those of the conventional form. There is a serious problem.
[0015]
In addition, when a ceramic circuit board is joined to a heat sink made of Cu, Al, or Cu—Fe alloy, a large warp is generated in which the back surface of the heat sink becomes concave due to the difference in thermal expansion coefficient between the two. This warpage causes solder voids when mounting the semiconductor chip when the module is manufactured. When the module is attached to the heat sink, the contact with the heat sink becomes insufficient, the thermal resistance increases, and the heat dissipation characteristics are greatly deteriorated. There is a problem of making it.
[0016]
Furthermore, the technique of low-temperature bonding the ceramic circuit board and the heat sink while applying pressure has the following problems. That is, the amount of warpage varies depending on the material of the ceramic circuit board to be joined and the material, thickness, and area of the heat sink, so that the pressurizing condition becomes complicated and is not practical. Further, even in a structure in which an intermediate layer for stress relaxation is provided between various circuit boards and a heat sink, there is a problem that a sufficient warp suppressing effect cannot be obtained and the intermediate layer deteriorates heat dissipation characteristics.
[0017]
As described above, in a power semiconductor module using a ceramic circuit board, when a heat sink with a low coefficient of thermal expansion is applied, the reliability of the heat cycle can be improved, but in terms of heat dissipation characteristics and manufacturing cost. There's a problem. Further, in a method in which an inexpensive metal is used for the heat sink and the ceramic circuit board and the heat sink are joined without using a solder layer, a large warp due to a difference in thermal expansion occurs.
[0018]
The present invention has been made in view of such problems, and a semiconductor device in which a semiconductor element is mounted on a heat dissipation member or a circuit board using the heat dissipation member is air-cooled or water-cooled via the heat dissipation member. It is intended to eliminate the problem in heat dissipation characteristics caused by warpage of the heat dissipation member when mounted on the heat sink. Another object of the present invention is to improve the electrical insulation between the circuit layer and the heat sink when the semiconductor element is used under a high voltage, and to improve the heat cycle characteristics.
[0019]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is a heat dissipation member used for forming a circuit board by providing a circuit layer on the upper surface of an upper ceramic plate joined to the upper surface of a metal heat dissipation plate, or the upper portion A heat dissipating member used to form a semiconductor device by providing a circuit layer and mounting a semiconductor element on an upper surface of a ceramic plate,
While joining a lower ceramic plate to the lower surface of the heat sink,
Of the side surface of the heat radiating plate, a side edge of a circuit layer provided on the upper surface of the upper ceramic plate and a portion existing corresponding to a portion formed along the side edge of the upper ceramic plate,
The heat dissipating member is characterized in that it is present inside a side surface of at least one of the upper and lower ceramic plates.
[0020]
Such a heat radiating member has a structure in which ceramic plates are joined to both surfaces of the heat radiating plate. Therefore, for example, the upper and lower ceramic plates are made of the same material and have the same thickness, and these are simultaneously joined to the heat sink by brazing or the like. By doing so, since there is no unbalance between the top and bottom of the internal stress generated in each member due to the joining, it is possible to provide a heat radiating member that does not cause a problem. Further, by forming (joining) a circuit layer (circuit board) on the upper surface of the upper ceramic plate (hereinafter also referred to as the upper ceramic plate), a circuit board with a heat dissipation member without warping can be obtained. Since there is no warping in the circuit board, the bonding can be performed without any problem even when the semiconductor element is soldered to the circuit layer. Further, even in a module in which such a semiconductor element is mounted, since there is no warping, a water-cooling or air-cooling heat sink (cooling member) is provided via the lower surface of the lower ceramic plate (hereinafter also referred to as the lower ceramic plate). ) Can be attached in close contact with the mounting surface. For this reason, since it can thermally radiate efficiently, it is possible to improve the heat dissipation characteristics of the electronic parts that generate heat.
[0021]
Note that the attachment of the heat radiating member to the heat sink is usually performed by screwing the screw member on both sides (both ends) of the heat radiating member or at four corners. Therefore, in the case where an allowable minute warp (with a warp amount of 10 μm / cm or less) is applied to the lower surface of the lower ceramic plate, the lower surface is closely attached to the heat sink mounting surface by screw tightening. As described above, it is preferable that the lower surface is provided with a warp that protrudes downward. A metal layer may be formed on the surface (lower surface) facing the heat sink of the lower ceramic plate as a means for improving heat dissipation or for improving adhesion to the heat sink. Furthermore, the heat sink may be plated or metallized to improve the bondability with the ceramic plate and prevent rust. In addition, the material of the heat sink is exemplified by Cu, Al, Ni, W, Mo, or an alloy mainly containing any of these. Examples of the material for the ceramic plate include silicon nitride, aluminum nitride, aluminum oxide, and silicon carbide.
[0022]
The heat dissipating member according to claim 1 has the following specific effects in addition to the effects described above. That is, a circuit layer (circuit board) is formed on the upper surface of the upper ceramic plate to form a circuit board, a semiconductor element is mounted on the circuit layer to form a module, and the lower surface of the lower ceramic plate of the heat radiating member forming this module is interposed therebetween. To the heat sink mounting surface. At this time, in the heat dissipating member according to claim 1, the heat dissipating member is formed along a side edge of a circuit layer provided on an upper surface of the upper ceramic plate among side surfaces of the heat dissipating plate. The part which exists corresponding to the part which exists is made to exist inside the side surface of at least one of the upper and lower ceramic plates. Here, the “side edge of the circuit layer” means the end of the circuit layer near the side edge of the upper ceramic plate, and the “side edge of the upper ceramic plate” means the end of the outer periphery of the upper surface of the upper ceramic plate. Say. And, “along the side edge of the upper ceramic plate” means that it coincides with the outer peripheral edge of the upper surface of the upper ceramic plate in a plan view (the side surfaces are flush), and substantially coincides with it. It means that.
[0023]
As described above, in the heat radiating member according to claim 1, even if the circuit layer is formed on the entire upper surface of the upper ceramic plate, the insulation creepage of the portion where the insulation between the circuit layer and the heat sink becomes a problem. The distance, that is, the distance for insulation along the exposed ceramic surface (shortest distance) between the circuit layer and the heat sink is larger than the dimension along the thickness direction on the side surfaces of both ceramic plates. In other words, in addition to the total thickness of the two ceramic plates, the insulation creepage distance of the part where insulation is a problem is secured to the extent that the side surface of the heat sink exists inside the side surface of the ceramic plate. Yes.
[0024]
Therefore, using the heat dissipating member of the present invention, a circuit layer is provided on the entire upper surface of the upper ceramic plate, a semiconductor element is mounted as a circuit board, and the mounting surface of the metal heat sink is provided via the lower surface of the heat dissipating member. When attached, the insulation creepage distance between the circuit layer and the sheet sink is sufficiently secured. For this reason, even if a high-voltage current of 2.5 kV, for example, flows through the circuit layer, it is possible to effectively prevent discharge from occurring between the circuit layer and the heat sink. Incidentally, the necessary insulation creepage distance is said to be 3 mm or more when the voltage flowing through the circuit layer is 2.5 kv, for example, but such a dimension can be easily secured. As described above, according to the present invention, since the insulation creepage distance can be largely secured by the above-described configuration, a heat radiating member having an extremely high electrical insulation effect can be obtained. As a result, in addition to improving the heat dissipation characteristics, the semiconductor device can be operated normally and stably. In addition, there exists the invention which concerns on Claims 2-9 as a means to ensure the insulation creepage distance which can endure to a high voltage.
[0025]
The invention according to claim 2 is a heat dissipation member used for forming a circuit board by providing a circuit layer on the upper surface of an upper ceramic plate joined to the upper surface of a metal heat dissipation plate, or the upper ceramic plate A heat dissipating member used for forming a semiconductor device by providing a circuit layer on the upper surface and mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
The heat radiating member is characterized in that the side surface of the heat radiating plate is present inside the side surface of at least one of the upper and lower ceramic plates over the entire periphery thereof.
[0026]
By forming in this way, even when the circuit layer is formed on the entire upper surface of the upper ceramic plate, the insulation creepage distance can be secured without any problem. That is, in the heat radiating member according to claim 1, the side surface of the heat radiating plate is made to be more than the side surface of at least one of the upper and lower ceramic plates so as to correspond to a portion where the insulation creepage distance needs to be secured. It was made to exist inside. For this reason, in the invention according to claim 1, in consideration of the pattern of the circuit layer to be formed, the side surface of the heat sink needs to be present inside the side surface of the ceramic plate. This is not necessary in such an invention.
[0027]
The invention according to claim 3 exists in the inner side of the side surfaces of the two ceramic plates instead of being present inside the side surfaces of at least one of the two ceramic plates in the first or second aspect. It is the heat radiating member characterized by having made it. In order to ensure the insulation creepage distance, the side surface of the heat sink is thus located inside the side surfaces of the upper and lower ceramic plates, so that the insulation creepage distance can be secured more easily. Further, both ceramic plates can be easily shared by using the same material and the same size. In addition, in the case of forming in this way, it is better to make it any one of claims 4 to 6.
[0028]
The invention according to claim 4 is an arc shape in which a side surface of the heat radiating plate existing inside the side surface of the ceramic plate is convex outward in a cross section cut by a plane perpendicular to the upper surface of the upper ceramic plate. Or it is formed in polygonal shape, It is a heat radiating member of Claim 3.
[0029]
In this way, by forming an arc shape or a polygonal shape that protrudes outward, there is no sharp angle portion on the side surface of the heat radiating plate where concentration of electric charges tends to occur. It can be used for higher voltages.
[0030]
The invention according to claim 5 is characterized in that chamfering is formed at each corner formed by the upper surface and the lower surface of the heat radiating plate that intersects the side surface of the heat radiating plate that is present inside the side surface of the ceramic plate. The heat dissipating member according to claim 3. Even if it does in this way, the effect similar to the heat radiating member of Claim 4 will be acquired.
[0031]
According to a sixth aspect of the present invention, the side surface of the heat radiating plate that is present inside the side surface of the ceramic plate is formed into a concave groove shape in a cross section cut by a plane perpendicular to the upper surface of the upper ceramic plate, and the concave groove 4. The heat radiating member according to claim 3, wherein each of the upper and lower groove walls is formed so as to become thinner toward the groove opening.
[0032]
By doing in this way, since the thickness of the side surface of the heat sink becomes thinner as it approaches the joint end with the ceramic plate, the generation of internal stress at the side portion (edge portion) of the ceramic plate can be reduced or reduced. . For this reason, it is possible to prevent damage such as cracking of the ceramic in the vicinity of the same part.
[0033]
The invention according to claim 7 is characterized in that the side surface of the heat radiating plate that is present inside the side surface of the ceramic plate is covered with an insulating material. It is a heat dissipation member.
[0034]
As in the invention according to claim 7, the insulation creepage distance can be further increased by covering the side surface of the heat radiating plate with an insulating material (insulating film). Further, when the side surface of the heat radiating plate is coated with an insulating material as described above, the side surface of the heat radiating plate is made to be more than the side surface of the ceramic plate as in the heat radiating member according to claim 8 or 9. The coating may be performed without being present inside. In addition, what is necessary is just to coat | cover by using rubber | gum (silicon rubber etc.) or resin (polyimide resin etc.) as an insulating material, and apply | coating this.
[0035]
The invention according to claim 8 is a heat dissipation member used for forming a circuit board by providing a circuit layer on the upper surface of an upper ceramic plate joined to the upper surface of a metal heat dissipation plate, or the upper ceramic plate A heat dissipating member used for forming a semiconductor device by providing a circuit layer on the upper surface and mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
Of the side surface of the heat radiating plate, an insulating material is a side edge of a circuit layer provided on the upper surface of the upper ceramic plate and corresponding to a portion formed along the side edge of the upper ceramic plate. It is the heat radiating member characterized by having coat | covered.
[0036]
The invention according to claim 9 is a heat dissipation member used for forming a circuit board by providing a circuit layer on an upper surface of an upper ceramic plate joined to an upper surface of a metal heat dissipation plate, or of the upper ceramic plate. A heat dissipating member used for forming a semiconductor device by providing a circuit layer on the upper surface and mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
The heat radiating member is characterized in that the side surface of the heat radiating plate is covered with an insulating material over the entire periphery thereof.
[0037]
The present invention according to claim 10 is a circuit board characterized in that a circuit layer is formed on the upper surface of the upper ceramic plate in the heat dissipation member according to any one of claims 1 to 9.
[0038]
Furthermore, the present invention according to claim 11 is directed to a semiconductor element on the upper surface of the upper ceramic plate of the heat radiating member according to any one of claims 1 to 9 or on the upper surface of the circuit board according to claim 10. This is a semiconductor device characterized by mounting.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
First embodiment
Hereinafter, a first embodiment (example) of a heat dissipation member according to the present invention will be described in detail with reference to FIGS. The heat radiating member 1 has a rectangular plate shape with a constant thickness when viewed as a whole, and is made of metal (for example, made of Cu (copper)) above and below the heat radiating plate 2 having a rectangular shape with a constant thickness. Ceramic plates (for example, silicon nitride plates) 3 and 4 having a certain thickness are joined to and integrated with both surfaces by brazing using, for example, active brazing (not shown). Here, the thickness of the heat radiating plate 2 is 3 mm, for example, and both the ceramic plates 3 and 4 are 0.25 mm in thickness. As the active solder, for example, a Cu—Sn based active metal solder is used.
[0040]
However, in this embodiment, the side surface 2a of the heat radiating plate 2 and the side surface 4a of the lower ceramic plate 4 are flush with each other, but the side surface (edge) 3a of the upper ceramic plate 3 is the side surface of the heat radiating plate 2. From 2a, a certain dimension (S) protrudes outward over the entire periphery of the side surface. That is, in this embodiment, the side surface 2a of the heat radiating plate 2 is made to be present inwardly by a certain dimension S from the side surface 3a of the upper ceramic plate 3 over the entire periphery. The pull-down dimension S is, for example, 2.5 mm. Further, the heat sink 2 has a flat surface of, for example, vertical and horizontal, 32 mm, and 90 mm. In plan view, mounting through-holes 5 are formed near the both ends.
[0041]
The heat radiating member 1 of this embodiment has a Cu-Sn-based active metal paste (active brazing) printed on the surfaces 3b and 4c of the ceramic plates 3 and 4 that are in contact with the heat radiating plate 2, and each member is attached to the surface. It is formed by stacking and placing a predetermined weight, for example, heating to a predetermined temperature in a vacuum atmosphere to melt the active wax, and then cooling. At this time, internal stress is generated in each member after joining and cooling based on the difference in Young's modulus and thermal expansion coefficient between the heat radiating plate 2 and the ceramic plates 3 and 4, because of such a laminated structure. , It does not cause unbalance in the stress at the top and bottom. Therefore, it can be set as the heat radiating member 1 without the problem curvature.
[0042]
And such a heat radiating member 1 becomes the circuit board 10 by providing the circuit layer 6 on the upper surface 3c of the upper ceramic board 3 as shown in FIG. When the circuit layer 6 is formed, for example, an active solder is screen-printed also on the upper surface 3c of the upper ceramic plate 3, and a Cu plate for forming a circuit layer is stacked on the upper and lower ceramic plates. 3 and 4 are formed at the same time, and then etched into a desired circuit pattern. In addition, as shown in FIG. 4, such a heat radiating member 1 is provided with a circuit layer 6 on the upper surface 3 c of the upper ceramic plate 3 and a semiconductor element 7 mounted via a solder layer 8. 11 is formed. And in this formation, it is as follows. That is, the circuit layer 6 is formed on the upper surface 3 c of the upper ceramic plate 3 of the heat dissipation member 1. When the semiconductor element 7 is soldered to the circuit layer 6, the heat radiating member 1 does not have a problem of warping, so that the semiconductor element 7 can be soldered without any problem.
[0043]
In the module formed in this way, as shown in FIG. 5, the lower surface 4b of the lower ceramic plate 4 is interposed in the heat sink (cooling member) 12, the thermally conductive grease 13 is interposed, and the screw member 14 is attached. Although it is attached by screwing it through the through hole 5, there is no warping which becomes a problem even in this attachment, and the adhesion between the module and the heat sink 12 is maintained. Therefore, the heat generated from the semiconductor during use is efficiently transferred to the heat sink 12 through the circuit layer 6 and the heat radiating member 1, so that a high cooling effect is obtained.
[0044]
Further, in addition to such basic effects, the following specific effects can also be obtained. That is, when a high voltage current flows through the circuit layer 6 when the module is mounted on the heat sink 12 as described above, it is important to ensure electrical insulation between the circuit layer 6 and the heat sink 12. Become. On the other hand, in the heat radiating member 1 of this embodiment, not only the ceramic plates (insulating plates) 3 and 4 are above and below the heat radiating plate 2, but also the side surface 2a of the heat radiating plate 2 is higher than the side surface 3a of the upper ceramic plate 3. Exists inside. Therefore, in addition to the upper and lower dimensions (thicknesses of the ceramic plates 3 and 4) 3E and 4E on the side surfaces 3 a and 4 a of the upper and lower ceramic plates 3 and 4, the upper ceramic plate 3 is relative to the heat sink 2. Therefore, a large insulation creepage distance is secured by the protrusion dimension S. Therefore, the insulation creepage distance is, for example, a dimension in which the lower surface 3b of the upper ceramic plate 3 protrudes from the side surface 2a of the radiator plate 2 in addition to the dimension obtained by adding the thicknesses 3E and 4E of the ceramic plates 3 and 4. Widely secured by S. For this reason, even if a high voltage current of 2.5 kV, for example, flows through the circuit layer 6, there is an effect that the occurrence of discharge between the circuit layer 6 and the heat sink 12 can be effectively prevented. That is, in this embodiment, even if the circuit layer 6 is formed on the entire upper surface 3c of the upper ceramic plate 3, the insulation creepage distance between the circuit layer 6 and the heat sink 12 is the thickness 3E of the ceramic plates 3 and 4. Since the dimension S is added in addition to the total dimension of 4E, no electrical discharge occurs, and electronic components such as the semiconductor element 7 bonded to the circuit layer 6 on the upper surface can be normally and stably operated. effective.
[0045]
In addition, when brazing in manufacturing the heat radiating member 1 described above, heat-resistant jigs such as carbon jigs may be used, and each member may be overlapped and brazed while being positioned so as to be arranged as shown in FIG. . Further, the heat sink 2 is brazed with the same shape and dimensions as those of the upper ceramic plate 3, and then etched, so that the side surface 2 a of the heat sink 2 is located inside the side surface 3 a of the upper ceramic plate 3. You may make it exist in. In the above embodiment, the ceramic plate is made of silicon nitride, but aluminum nitride, aluminum oxide, or the like may be used. Moreover, as a material of the heat sink 2, an appropriate material selected from metals having high thermal conductivity such as Al (aluminum) or Al alloy may be used. In addition, when the heat sink 2 is made of Al or Al alloy in this way, for example, each metal layer (for example, each 100 nm thick) is deposited on the bonding surface of the ceramic plate in the order of Ti, Mo, and Ni. It may be formed and brazed with an Al—Si brazing material.
[0046]
In the above-described embodiment, the entire periphery of the side surface 2a of the heat radiating plate 2 is present inside the side surface 3a of the upper ceramic plate 3, so that the circuit layer 6 may be formed on the entire surface or the circuit layer. The insulation creepage distance can be ensured regardless of the pattern 6 or the formation area. However, it is not always necessary for the entire side surface 2a to be present inside. That is, in the present invention, of the periphery of the side surface 2a of the heat radiating plate 2, the portion of the circuit layer 6 to be formed among the portions where the insulation creepage distance does not matter, for example, the portion indicated by the one-dot chain line in FIG. The insulation creepage distance is already sufficiently secured for the portion (the portion A in FIG. 2) where the side edge is located sufficiently inside the side edge (side surface) 3a of the upper ceramic plate 3. For this reason, a portion excluding such a portion, that is, a side edge of the circuit layer 6 provided on the upper surface 3c of the upper ceramic plate 3 in the side surface 2a of the heat sink 2 and a side edge of the upper ceramic plate 3 is provided. It suffices if a portion corresponding to a portion formed along the portion (B portion in FIG. 2) is present inside the side surface of at least one of the upper and lower ceramic plates 3 and 4. It is. Hereinafter, another embodiment of the configuration for securing the insulation creepage distance in the heat dissipating member 1 of the present invention will be described.
[0047]
Second embodiment
FIG. 6 shows a second embodiment of the heat dissipating member according to the present invention. However, the heat radiating member 21 is different from the upper ceramic plate 3 in the first embodiment described above in that the side surface 4a of the lower ceramic plate 4 is protruded from the side surface 2a of the heat radiating plate 2 by a predetermined amount S. Since only the differences are present and there is no essential difference, the same parts are only given the same reference numerals, and detailed description thereof is omitted. The same applies to the following. That is, even in this case, the insulation creepage distance can be increased similarly.
[0048]
FIG. 7 shows a third embodiment of the heat dissipating member according to the present invention. This heat radiating member 31 has the side surface 2a of the heat radiating plate 2 inside the side surfaces 3a, 4a of the upper and lower ceramic plates 3, 4. In this case, when the projecting amount S is the same as that in each of the above embodiments, the insulation creepage distance can be further secured, so that a sufficient discharge preventing effect is expected even for a higher voltage current. Is done. On the other hand, in this case, when the same insulation creepage distance as that of the above-described embodiment is ensured, the protruding amount of both ceramic plates 3 and 4 can be halved as is apparent from the drawing. That is, it is possible to reduce the size of the heat radiating member 2 as much as the protrusion of the ceramic plate can be reduced, and to prevent damage such as cracking of the protruding portion.
[0049]
FIG. 8 shows a fourth embodiment of the heat dissipating member according to the present invention. In the third embodiment, the heat radiating member 41 has a side surface 2a of the heat radiating plate 2 that protrudes outwardly (a bulging shape) in a cross section cut by a plane perpendicular to the upper surface 3c of the upper ceramic plate 3. It is formed in an arc shape. In this case, the same effect as in the above embodiment is obtained. However, in this case, since the side surface 2a of the heat radiating plate 2 does not have an acute angle, concentration of electric charges can be prevented. For this reason, the further superior discharge prevention effect is acquired. Although not shown in the drawing, the same effect can be obtained by forming a polygonal shape projecting outward instead of the arc-shaped projecting projecting outward. Further, in the case of an arc shape projecting outward, the radius may be set to be half the thickness of the heat radiating plate 2 or a radius larger than the half so as to form an arc shape. Further, in the case of a polygonal shape, it is preferable to have as many corners as possible. When such a heat dissipating member 41 is used as a circuit board as described above or mounted on the heat sink 12 with the semiconductor element 7 mounted, the concentration of electric charges can be prevented, so that the effect of preventing the occurrence of discharge is further enhanced. It will be a thing.
[0050]
FIG. 9 shows a fifth embodiment of the heat dissipating member according to the present invention, and should be said to be a modification of the above embodiment. That is, in this heat radiating member 51, chamfering is formed at each corner formed by the upper surface 2 c and the lower surface 2 b of the heat radiating plate 2 that intersects the side surface 2 a of the heat radiating plate 2. Also in this case, since the acute angle cannot be formed on the side surface 2a of the heat radiating plate 2, there is an effect similar to that of the fourth embodiment, such as prevention of charge concentration. Furthermore, in this case, since it is chamfered, there is also an effect in manufacturing such that the formation and manufacture become easy. Although not shown, such chamfering can provide the same effect as round chamfering (arc-shaped chamfering) instead of inclined chamfering.
[0051]
FIG. 10 shows a sixth embodiment of the heat dissipating member according to the present invention. The heat radiating member 61 has a groove shape in a cross section obtained by cutting the side surface 2a of the heat radiating plate 2 along a plane perpendicular to the upper surface 3c of the upper ceramic plate 3, and the upper and lower groove walls 2k in the groove are respectively recessed. It is formed so as to become thinner toward the groove opening. In the same figure, the side surface 2a of the heat radiating plate 2 is formed in an arc shape that is concave outward in the same cross section, and the closer to the side portions 3a, 4a of the upper and lower ceramic plates 3, 4, It is formed so that the thickness of the joined heat sink 2 is reduced. For this reason, since the internal stress in the portions near the side surfaces 3a and 4a of the ceramic plates 3 and 4 after joining to the heat radiating plate 2 can be reduced or reduced, there is an effect of preventing peeling or breakage in the vicinity of the same portions in the ceramic plate. Reliability is improved.
[0052]
FIG. 11 shows a seventh embodiment of the heat dissipating member according to the present invention, which should be called a modified example of the above embodiment. The heat radiating member 71 is formed by forming the side surface 2a of the heat radiating plate 2 into a polygon that is concave outward in the same cross section, but the same effect can be obtained in this way. In addition, when the side surface 2a of the heat radiating plate 2 including the one in this example has an outwardly convex shape or a concave shape, it may be formed into a predetermined shape by grinding or the like before or after joining. However, when making it concave, it can also be formed by blasting the side surface of the heat dissipating member 1.
[0053]
FIG. 12 shows an eighth embodiment of the heat dissipating member according to the present invention. The heat radiating member 81 is obtained by covering the side surface 2a of the heat radiating plate 2 with an insulating material 82 in the embodiment shown in FIG. In this way, the insulation creepage distance can be further increased by covering the side surface 2a of the heat radiating plate 2 with the insulating material (insulating film) 82. For this reason, the insulation between the circuit layer and the heat sink is reliably maintained. Further, when the side surface 2a of the heat sink 2 is covered with the insulating material 82 as described above, the side surface 2a of the heat sink 2 does not have to be present inside the side surface of the ceramic plate.
[0054]
FIG. 13 shows one example. In this case, the upper and lower ceramic plates 3 and 4 and the heat radiating plate 2 have the same planar shape and the same planar dimensions, and these side surfaces 3a, 4a and 2a are aligned and joined. This is covered with an insulating material 82 so as to cover the side surface 2a. That is, in this case, the side surface 2a of the heat radiating plate 2 is flush with the side surfaces 3a, 4a of the upper and lower ceramic plates 3, 4, and is covered with an insulating material 82 so that the side surface 2a of the heat radiating plate 2 itself is not exposed. It is a thing. Also in this case, the insulation creepage distance can be increased. Even in such a configuration, it is not always necessary to cover and form the entire periphery of the side surface 2a of the heat radiating plate 2 with an insulating material, and only the portion where the insulation creepage distance is a problem is covered with the insulating material. Good. However, it is more preferable that the entire periphery of the side surface 2a of the heat sink 2 is covered with an insulating material. The insulating material 82 is not particularly limited, but may be covered by applying a heat-resistant rubber, resin, or the like such as silicon rubber or polyimide resin.
[0055]
Next, the heat dissipating members (Examples 1 to 7) of the above-described modes 1 to 7 are formed, the circuit layer 6 is formed on the upper surface 3c of the upper ceramic plate 3, and the semiconductor element 7 is soldered to the circuit layer 6 The module is mounted by mounting, and an electrode is brought into contact with the entire surface of the circuit layer and the entire lower surface 4b of the lower ceramic plate 4, and a high voltage current is applied to conduct an insulation resistance test between the two ceramic plates. The effect (insulation performance) by increasing the distance was confirmed.
[0056]
However, an insulation withstand voltage tester was used for this test, the test voltage was 1 KV to 4.5 KV, and the application time was 1 minute. The results are as shown in Table 1. The heat sink 2 is made of Cu, the thickness is 3 mm, the upper and lower ceramic plates 3 and 4 are made of silicon nitride, the thickness is 0.25 mm, the circuit layer 6 is made of Cu, and the thickness is 0.4 mm. And formed on the entire upper surface of the upper ceramic plate 3. In addition, as shown in FIG. 14, the comparative example 1 is only the point which made the side surface 2a of the heat sink 2 and the side surfaces 3a and 4a of the upper and lower ceramic plates 3 and 4 correspond (aligned). Only 7 is different. Further, as shown in FIG. 15, Comparative Example 2 is the same as Example 1 except that the side surface 2 a of the heat radiating plate 2 protrudes 1.0 mm outward from the side surfaces 3 a and 4 a of the upper and lower ceramic plates 3 and 4. Only the ones of ~ 7 are different.
[0057]
Further, in Examples 1 to 3 (FIGS. 1, 6, and 7), the amount S of pulling down from the side surface 3a, 4a of the upper or lower ceramic plate 3, 4 to the side surface 2a of the heat radiating plate 2 is 1 mm. It is.
The pull-down in Examples 4-7 is as follows.
In Example 4 (see FIG. 8), the side surface 2a of the heat radiating plate 2 has an arcuate cross section that is convex outward, and the position is in contact with the lower surface 3b of the upper ceramic plate 3 and the upper surface 4c of the lower ceramic plate 4. The arcuate cross section has a radius of 1.5 mm and an outward convexity so that the amount of pull-down S4 of the heat sink 2 is 2 mm. The thickness of the heat sink 2 is 3 mm. Thereby, the outer end of the intermediate height part of the side surface 2a of the heat sink 2 is pulled down 0.5 mm from the side surfaces 3a, 4a of the upper and lower ceramic plates 3, 4.
In Example 5 (see FIG. 9), chamfering is formed at each corner formed by the upper surface 2c and the lower surface 2b of the heat sink 2 that intersects the side surface 2a of the heat sink 2, and the lower surface 3b of the upper ceramic plate 3 is formed. Chamfering with an angle θ to the horizontal of 30 degrees, a horizontal width of 1.73 mm, and a height of 1.0 mm so that the amount of pulling down S5 of the heat sink 2 at a position in contact with the upper surface 4c of the lower ceramic plate 4 is 2 mm. Is given. Thereby, the side surface 2a of the heat sink 2 is pulled down from the side surfaces 3a and 4a of the upper and lower ceramic plates 3 and 4 by about 0.27 mm.
In Example 6 (see FIG. 10), the side surface 2a of the heat radiating plate 2 is formed in an arc shape that is concave outward, and is in contact with the lower surface 3b of the upper ceramic plate 3 and the upper surface 4c of the lower ceramic plate 4. The amount of pull-down S6 of the heat radiating plate 2 at the position is set to 1 mm, and from there, an arc-shaped cross section is formed with a radius of 1.5 mm and an outwardly concave. Thereby, it becomes a ditch | groove whose maximum depth is 2.5 mm from the side surfaces 3a and 4a of the ceramic plates 3 and 4.
The seventh embodiment (see FIG. 11) is formed in a trapezoidal shape in which the side surface 2a of the heat radiating plate 2 is concave outward, and is in contact with the lower surface 3b of the upper ceramic plate 3 and the upper surface 4c of the lower ceramic plate 4. A trapezoidal groove having a groove depth of 2 mm, a groove bottom width of 2 mm, and an opening width of 3 mm is narrow so that the amount S7 of the heat sink 2 at the position is 1 mm.
In addition, all were made to exist inside the whole side surface around the heat sink 2.
[0058]
[Table 1]
Figure 2005032791
[0059]
As shown in Table 1, at 1 KV and 1.5 KV, no insulation problem occurred in any of Examples 1 to 3 and Comparative Examples 1 and 2 in which the test was performed, and it was OK (pass). It was. In addition, at 2.5 KV, in Examples 1 to 7 of the present invention, insulation problems did not occur, whereas in Comparative Examples 1 and 2, an insulation failure due to discharge occurred and NG (failed) )Met. At 3.5 KV, insulation problems did not occur in Examples 3 to 7 of the present invention, whereas in Examples 1 and 2 and Comparative Examples 1 and 2, there was an insulation failure due to discharge. Occurred. Furthermore, at 4 KV, insulation problems did not occur in Examples 4 and 5 of the present invention, whereas insulation failures due to discharge occurred in Examples 1 to 3, 6 and 7. “Not implemented” in the table indicates that the test was not performed.
[0060]
From this test result, it can be seen that according to the heat radiating member of the present invention, the insulation characteristics can be reliably improved, and any member of 2.5 KV will pose no problem. On the other hand, for a high voltage of 3.5 KV, it can be seen that it is preferable that the side surface 2a of the heat radiating plate 2 exists inside the side surfaces 3a, 4a of the upper and lower ceramic plates 3, 4. Further, it has been found that when the side surface 2a of the heat radiating plate 2 has an arc or polygonal shape that protrudes outward, there is no problem even at a high voltage of 4 KV, and the best result is obtained. These things just prove the effect of the heat radiating member of the present invention.
[0061]
Furthermore, about the thing of Example 6, 7, the thermal cycle test was done and the presence or absence of peeling of a ceramic board was confirmed. However, in the thermal cycle test, -40 degrees to RT (room temperature) to 350 degrees was set as one cycle and held at each temperature for 30 minutes. The results are as shown in Table 2. In addition, peeling of the interface between a heat sink and a ceramic board evaluated the presence or absence of the generation | occurrence | production for every 10 cycles with the ultrasonic flaw detector.
[0062]
[Table 2]
Figure 2005032791
[0063]
As shown in Table 2, the samples of Examples 6 and 7 were “no peeling” up to 70 cycles, but in Comparative Examples 1 and 2, the occurrence of peeling was observed in 30 cycles. . From this, it was also demonstrated that high reliability can be obtained for the heat cycle by forming the side surface 2a of the heat radiating plate 2 as in Examples 6 and 7. That is, by doing so, the stress generated in the ceramic plate can be reliably relaxed or reduced.
[0064]
The present invention is not limited to the embodiments described above, and can be embodied with appropriate design changes. Further, the material and dimensions (thickness, etc.) of the heat sink, the material, dimensions (thickness, etc.) of the ceramic plate, and their joining methods may be appropriately changed and embodied.
[0065]
【The invention's effect】
As is apparent from the above description, the heat dissipation member of the present invention can effectively prevent warpage. For this reason, when a circuit board is formed using the heat dissipating member of the present invention, and further a semiconductor element is mounted to form a semiconductor device, and this is attached to an air-cooled or water-cooled heat sink via the heat dissipating member. The problem of heat dissipation characteristics due to warpage can be solved. Moreover, since the electrical insulation between the circuit layer and the heat sink can be enhanced, the semiconductor element used under a high voltage can be operated normally and stably. Furthermore, since heat cycle characteristics can be improved, a highly reliable semiconductor device can be obtained.
[Brief description of the drawings]
FIG. 1 is a side view and an enlarged cross-sectional view of a main part of a first embodiment of a heat dissipation member according to the present invention.
2 is a plan view of the heat dissipating member of FIG. 1. FIG.
3 is a side view of a circuit board in which a circuit layer is formed on the upper surface of the heat dissipating member of FIG. 1;
4 is a side view of a semiconductor device in which a circuit layer is formed on the upper surface of the heat dissipation member of FIG. 1 to form a circuit board, and a semiconductor element is soldered on the upper surface.
FIG. 5 is a cross-sectional view of the semiconductor device attached to a heat sink.
FIG. 6 is an enlarged cross-sectional view of a main part of a second embodiment of a heat dissipation member according to the present invention.
FIG. 7 is an enlarged cross-sectional view of a main part of a third embodiment of a heat dissipating member according to the present invention.
FIG. 8 is an enlarged cross-sectional view of a main part of a fourth embodiment of a heat dissipating member according to the present invention.
FIG. 9 is an enlarged cross-sectional view of a main part of a fifth embodiment of a heat dissipating member according to the present invention.
FIG. 10 is an enlarged cross-sectional view of a main part of a sixth embodiment of a heat dissipating member according to the present invention.
FIG. 11 is an enlarged cross-sectional view of a seventh embodiment of a heat dissipation member according to the present invention.
FIG. 12 is an enlarged view of a main part of a cross section of an eighth embodiment of a heat dissipation member according to the present invention.
FIG. 13 is an enlarged view of a principal part of a cross section of a ninth embodiment of a heat dissipation member according to the present invention.
FIG. 14 is an enlarged view of a principal part of a cross section showing a comparative example 1 of the heat radiating member.
FIG. 15 is an enlarged cross-sectional view showing a comparative example 2 of the heat radiating member.
[Explanation of symbols]
1, 21, 31, 41, 51, 61, 71, 81, 91
2 Heat sink
2a Side of heat sink
2c Top surface of heat sink
2b Underside of heat sink
3 Upper ceramic plate
3a Side of upper ceramic plate
3c Top surface of the upper ceramic plate
3b Lower surface of upper ceramic plate
4 Lower ceramic plate
4a Side of the lower ceramic plate
4c Upper surface of the lower ceramic plate
4b Lower surface of the lower ceramic plate
6 Circuit layer
10 Circuit board
11 Semiconductor devices
12 Heat sink
82 Insulation

Claims (11)

金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面のうち、前記上部セラミック板の上面に設けられる回路層の側縁であって該上部セラミック板の側縁に沿って形成される部位に対応して存在する部位を、
前記上、下両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたことを特徴とする放熱部材。A heat dissipating member used to form a circuit board by providing a circuit layer on the upper surface of the upper ceramic plate joined to the upper surface of the metal heat dissipating plate, or a circuit layer on the upper surface of the upper ceramic plate A heat dissipation member used to form a semiconductor device by mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
Of the side surface of the heat radiating plate, a side edge of a circuit layer provided on the upper surface of the upper ceramic plate and a portion existing corresponding to a portion formed along the side edge of the upper ceramic plate,
A heat dissipating member, wherein the heat dissipating member is present inside a side surface of at least one of the upper and lower ceramic plates. 金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面を、その周囲全体にわたって、前記上、下両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたことを特徴とする放熱部材。A heat dissipating member used to form a circuit board by providing a circuit layer on the upper surface of the upper ceramic plate joined to the upper surface of the metal heat dissipating plate, or a circuit layer on the upper surface of the upper ceramic plate A heat dissipation member used to form a semiconductor device by mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
A heat radiating member characterized in that the side surface of the heat radiating plate is present inside the side surface of at least one of the upper and lower ceramic plates over the entire periphery thereof. 請求項１又は２において、前記両セラミック板のうちの少なくとも一方のものの側面よりも内側に存在させたことに代えて、
前記両セラミック板の側面よりも内側に存在させたことを特徴とする放熱部材。In Claim 1 or 2, instead of being present inside the side surface of at least one of the two ceramic plates,
A heat dissipating member, wherein the heat dissipating member is present inside the side surfaces of the two ceramic plates. 前記セラミック板の側面よりも内側に存在させた前記放熱板の側面を、前記上部セラミック板の上面に垂直な平面で切断した断面において外向きに凸となす円弧状又は多角形状に形成したことを特徴とする請求項３に記載の放熱部材。The side surface of the heat radiating plate that exists inside the side surface of the ceramic plate is formed in an arc shape or a polygonal shape that protrudes outward in a cross section cut by a plane perpendicular to the upper surface of the upper ceramic plate. The heat radiating member according to claim 3, wherein 前記セラミック板の側面よりも内側に存在させた前記放熱板の側面と交わる該放熱板の上面及び下面とのなすそれぞれの角に、面取りを形成したことを特徴とする請求項３に記載の放熱部材。The heat radiation according to claim 3, wherein chamfering is formed at each corner formed by an upper surface and a lower surface of the heat radiating plate that intersects a side surface of the heat radiating plate that is present inside the side surface of the ceramic plate. Element. 前記セラミック板の側面よりも内側に存在させた前記放熱板の側面を、前記上部セラミック板の上面に垂直な平面で切断した断面において凹溝状としかつその凹溝における上下の溝壁のそれぞれを、凹溝開口に向うにしたがって薄くなるように形成したことを特徴とする請求項３に記載の放熱部材。The side surface of the heat radiating plate that is present inside the side surface of the ceramic plate is formed in a groove shape in a cross section cut by a plane perpendicular to the upper surface of the upper ceramic plate, and each of the upper and lower groove walls in the groove is formed. The heat radiating member according to claim 3, wherein the heat radiating member is formed so as to become thinner toward the groove opening. 前記セラミック板の側面よりも内側に存在させた前記放熱板の側面を絶縁材で被覆したことを特徴とする請求項１〜６のいずれか１項に記載の放熱部材。The heat radiating member according to any one of claims 1 to 6, wherein a side surface of the heat radiating plate existing inside a side surface of the ceramic plate is covered with an insulating material. 金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面のうち、前記上部セラミック板の上面に設けられる回路層の側縁であって該上部セラミック板の側縁に沿って形成される部位に対応して存在する部位を絶縁材で被覆したことを特徴とする放熱部材。A heat dissipating member used to form a circuit board by providing a circuit layer on the upper surface of the upper ceramic plate joined to the upper surface of the metal heat dissipating plate, or a circuit layer on the upper surface of the upper ceramic plate A heat dissipation member used to form a semiconductor device by mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
Of the side surface of the heat radiating plate, an insulating material is a side edge of a circuit layer provided on the upper surface of the upper ceramic plate and corresponding to a portion formed along the side edge of the upper ceramic plate. A heat radiating member characterized by being coated. 金属製の放熱板の上面に接合された上部セラミック板の上面に、回路層を設けて回路基板を形成するのに用いられる放熱部材、又は、該上部セラミック板の上面に、回路層を設けるとともに半導体素子を搭載することで半導体装置を形成するのに用いられる放熱部材であって、
前記放熱板の下面に下部セラミック板を接合するとともに、
前記放熱板の側面をその周囲全体にわたって絶縁材で被覆したことを特徴とする放熱部材。A heat dissipating member used to form a circuit board by providing a circuit layer on the upper surface of the upper ceramic plate joined to the upper surface of the metal heat dissipating plate, or a circuit layer on the upper surface of the upper ceramic plate A heat dissipation member used to form a semiconductor device by mounting a semiconductor element,
While joining a lower ceramic plate to the lower surface of the heat sink,
A heat dissipating member, wherein the side surface of the heat dissipating plate is covered with an insulating material over the entire periphery thereof. 請求項１〜９のいずれか１項に記載の放熱部材における上部セラミック板の上面に回路層を形成したことを特徴とする回路基板。A circuit board, wherein a circuit layer is formed on an upper surface of an upper ceramic plate in the heat dissipating member according to claim 1. 請求項１〜９のいずれか１項に記載の放熱部材の上部セラミック板の上面に、または、請求項１０に記載の回路基板の回路層の上面に、半導体素子を搭載したことを特徴とする半導体装置。A semiconductor element is mounted on the upper surface of the upper ceramic plate of the heat dissipating member according to claim 1 or on the upper surface of the circuit layer of the circuit board according to claim 10. Semiconductor device.
JP2003193378A 2003-07-08 2003-07-08 Heat dissipating member, circuit board, and semiconductor device Pending JP2005032791A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011061139A (en) * 2009-09-14 2011-03-24 Kansai Electric Power Co Inc:The Semiconductor device
JP2012049436A (en) * 2010-08-30 2012-03-08 Mitsubishi Materials Corp Substrate for power module and method of manufacturing substrate for power module with heat sink
JP2012069517A (en) * 2010-08-25 2012-04-05 Sumitomo Chemical Co Ltd Manufacturing method of cathode material powder for fine lithium secondary battery
JP2013098423A (en) * 2011-11-02 2013-05-20 Mitsubishi Materials Corp Substrate for power module, substrate for power module having heat sink, and manufacturing method for substrate for power module
WO2022209765A1 (en) * 2021-03-29 2022-10-06 株式会社富士通ゼネラル Electric motor

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011061139A (en) * 2009-09-14 2011-03-24 Kansai Electric Power Co Inc:The Semiconductor device
JP2012069517A (en) * 2010-08-25 2012-04-05 Sumitomo Chemical Co Ltd Manufacturing method of cathode material powder for fine lithium secondary battery
JP2012049436A (en) * 2010-08-30 2012-03-08 Mitsubishi Materials Corp Substrate for power module and method of manufacturing substrate for power module with heat sink
JP2013098423A (en) * 2011-11-02 2013-05-20 Mitsubishi Materials Corp Substrate for power module, substrate for power module having heat sink, and manufacturing method for substrate for power module
WO2022209765A1 (en) * 2021-03-29 2022-10-06 株式会社富士通ゼネラル Electric motor
JP2022152646A (en) * 2021-03-29 2022-10-12 株式会社富士通ゼネラル Electric motor
JP7255622B2 (en) 2021-03-29 2023-04-11 株式会社富士通ゼネラル Electric motor

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