JP2004146737A - Power module substrate, and power module - Google Patents

Power module substrate, and power module Download PDF

Info

Publication number
JP2004146737A
JP2004146737A JP2002312594A JP2002312594A JP2004146737A JP 2004146737 A JP2004146737 A JP 2004146737A JP 2002312594 A JP2002312594 A JP 2002312594A JP 2002312594 A JP2002312594 A JP 2002312594A JP 2004146737 A JP2004146737 A JP 2004146737A
Authority
JP
Japan
Prior art keywords
thermal expansion
radiator
power module
insulating substrate
low thermal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2002312594A
Other languages
Japanese (ja)
Other versions
JP3912255B2 (en
Inventor
Yoshiyuki Nagatomo
長友　義幸
Takeshi Negishi
根岸　健
Toshiyuki Nagase
長瀬　敏之
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Materials Corp
Original Assignee
Mitsubishi Materials Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Materials Corp filed Critical Mitsubishi Materials Corp
Priority to JP2002312594A priority Critical patent/JP3912255B2/en
Publication of JP2004146737A publication Critical patent/JP2004146737A/en
Application granted granted Critical
Publication of JP3912255B2 publication Critical patent/JP3912255B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
    • H01L23/3735—Laminates or multilayers, e.g. direct bond copper ceramic substrates
    • 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
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H01L23/14—Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
    • H01L23/15—Ceramic or glass substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
    • H01L23/473—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids by flowing liquids

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To restrict deformation irrespective of the difference between thermal expansion coefficients of both of an insulating substrate and a heat radiator, and further suppress the lowering of thermal conductivity. <P>SOLUTION: In the power module substrate 10 including a circuit layer 12 provided on the upper surface of the insulating substrate 11 and the heat radiator 16 provided on the lower surface of the insulating substrate 11, a low thermal expansion member 18 is laminated on a radiator body 17 of the heat radiator 16, and the low thermal expansion member 18 is made of a material having the quality of a low thermal expansion coefficient than that of the radiator body 17, for example invar alloy. In the low thermal expansion member 18, there is provided a stepped portion 20 in the direction of the thickness of a region facing the insulating substrate 11. A disposition position of the stepped portion 20 in the direction along the stepped portion 20 and in the direction along the lamination is determined by the disposition position in the direction along the surface of the insulating substrate 11 and a difference between the thermal expansion coefficients of the insulating substrate 11 and the radiator 16. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、大電圧・大電流を制御する半導体装置に用いられるパワーモジュール用基板に係り、特に半導体チップ等の発熱体から発生する熱を放散させる放熱体を有するパワーモジュール用基板及びパワーモジュールに関する。
【０００２】
【従来の技術】
この種のパワーモジュール用基板にあっては、セラミックス材料からなる絶縁基板（セラミックス基板）の一方の面に回路層を、他方の面に放熱体を各々備え、この放熱体の絶縁基板形成面と対向する面に、冷却水等の冷却手段を備えた冷却シンク部を備えた構成のものが一般的である。しかしながら、絶縁基板に放熱体をはんだ等で積層接着する際に、そのときの熱と、絶縁基板と放熱体との熱膨張係数の差とに起因して、放熱体が絶縁基板に向けて反り、放熱体と絶縁基板との間に間隙が生じる場合があった。この場合、回路層上に設けられた半導体チップが発熱した際の熱を放熱体に良好に伝達することができないという問題があった。
【０００３】
このような問題を解決するための手段として、例えば特許文献１のような技術が開示されている。この文献には、前述の構成において、放熱体の絶縁基板形成面と対向する面に、絶縁基板と略同一の熱膨張係数を有する金属板（例えば、４２アロイ）を設けた構成が開示されている。この構成により、絶縁基板と放熱体との間に熱膨張係数の差があったとしても、放熱体の反り発生を抑制することができるというものである。
【０００４】
【特許文献１】
特開平１−２８６３４８号公報（第２−４頁、図１〜図３）
【０００５】
【発明が解決しようとする課題】
ところで、前記に示す従来のパワーモジュール用基板は、放熱体の絶縁基板形成面と対向する面に前記金属板を設けているので、回路層上に設けられた半導体チップの発熱による熱をパワーモジュール用基板の積層方向に良好に伝達することができないという問題があった。すなわち、半導体チップから絶縁基板に伝達された熱が放熱体に達した後、この熱が前記金属板で留まり良好に放熱できないという問題があった。この場合、パワーモジュール用基板全体の温度が上昇し、その結果、放熱体の絶縁基板へ向けた反りが更に発生し、更なる放熱体の熱伝導率の低下を招く問題があった。
【０００６】
この発明は、このような事情を考慮してなされたもので、その目的は、絶縁基板及び放熱体の双方の熱膨張係数差があっても、これに拘わることなく反りを抑制することができると共に、熱伝導率が低下することを抑制できるパワーモジュール用基板及びパワーモジュールを提供することにある。
【０００７】
【課題を解決するための手段】
前記目的を達成するために、この発明は以下の手段を提案している。
請求項１に係る発明は、絶縁基板と、該絶縁基板の一方の面に設けられた放熱体と、前記絶縁基板の他方の面に設けられた回路層とを備えたパワーモジュール用基板であって、前記放熱体は、放熱体本体に該放熱体本体の熱膨張係数より低い材質からなる低熱膨張材を積層して構成されていることを特徴とする。
【０００８】
この発明に係るパワーモジュール用基板によれば、放熱体が、放熱体本体と低熱膨張材とを積層した構成となっているので、放熱体全体の熱膨張係数を確実に下げ、絶縁基板と放熱体全体との熱膨張係数の差が可及的に小さくなる。このため、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することになる。
【０００９】
請求項２に係る発明は、請求項１記載のパワーモジュール用基板において、前記低熱膨張材の厚さは、前記放熱体本体の厚さの０．１倍以下で形成されていることを特徴とする。
【００１０】
この発明に係るパワーモジュール用基板によれば、低熱膨張材の厚さが、放熱体本体の厚さの０．１倍以下で形成されているので、放熱体全体の熱膨張係数を確実に下げるとともに、放熱体全体の熱伝導率の低下を最小限に抑制することになる。これにより、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを抑制するとともに、必要最小限の熱伝導率を有した放熱体を備えたパワーモジュール用基板を提供することができる。
【００１１】
請求項３に係る発明は、請求項１又は２に記載のパワーモジュール用基板において、前記低熱膨張材の積層方向の厚さは、前記放熱体本体の積層方向の厚さの０．０５倍以上で形成されていることを特徴とする。
【００１２】
この発明に係るパワーモジュール用基板によれば、低熱膨張材の厚さが、放熱体本体の厚さの０．０５倍以上で形成されているので、放熱体全体の熱膨張係数に寄与する低熱膨張材の影響を最小限維持することになり、放熱体全体としての熱膨張係数を確実に下げ、絶縁基板と放熱体全体との熱膨張係数の差が可及的に小さくなる。このため、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することになる。
【００１３】
請求項４に係る発明は、請求項１から３のいずれかに記載のパワーモジュール用基板において、前記低熱膨張材の絶縁基板と対応する領域に、放熱体側の熱膨張係数と絶縁基板側の熱膨張係数との差に基づき、段差部が設けられていることを特徴とする。
【００１４】
この発明に係るパワーモジュール用基板によれば、低熱膨張材の絶縁基板と対応する領域に、放熱体と絶縁基板との熱膨張係数の差に基づいて段差部を設けたので、前記領域における放熱体と絶縁基板との熱膨張係数の差を緩和することになる。これにより、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することになる。
【００１５】
請求項５に係る発明は、請求項１から４のいずれかに記載のパワーモジュール用基板において、前記段差部は、放熱体において、絶縁基板側の熱膨張係数が放熱体側の熱膨張係数より小さいとき、低熱膨張材の前記絶縁基板と対応する領域を、絶縁基板から遠ざかる方向に凹ませて形成する一方、絶縁基板側の熱膨張係数より放熱体側の熱膨張係数が小さいとき、低熱膨張材の前記絶縁基板と対応する領域を、絶縁基板に近づく方向に隆起させて形成することを特徴とする。
【００１６】
この発明に係るパワーモジュール用基板によれば、絶縁基板側の熱膨張係数と放熱体側の熱膨張係数との差に応じて、低熱膨張材の段差部の積層方向に対する配設位置を変えるので、放熱体の絶縁基板と対応する領域における熱膨張係数に与える低熱膨張材の影響を調整することができ、放熱体の熱膨張係数を見かけ上調整できる構成となっている。これにより、絶縁基板と、この絶縁基板と対応する領域における放熱体との熱膨張係数の差を確実に緩和することができ、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することになる。
【００１７】
請求項６に係る発明は、請求項１から５のいずれかに記載のパワーモジュール用基板において、前記低熱膨張材には、これを貫通する孔が穿設されていることを特徴とする。
【００１８】
この発明に係るパワーモジュール用基板によれば、低熱膨張材に設けられた孔に放熱体本体を充填し、低熱膨張材を放熱体本体に鋳ぐませる構成とすることができ、これにより、低熱膨張材の孔を介して絶縁基板からの熱を確実に放熱体の積層方向に伝達し、この熱を外部に良好に放熱することになる。以上により、放熱体の熱膨張係数の低下と熱伝導率の低下抑制とを確実に実現することになる。また、低熱膨張材に設けられた孔に放熱体本体を鋳ぐませる構成の他、前記孔に放熱体本体と同一材質の平板又は粉末材料を低熱膨張材の厚さ分だけ充填した後、この低熱膨張材の上下面に放熱体本体をろう材を介して積層接合させた構成としても前述と同様の作用を奏することになる。
【００１９】
請求項７に係る発明は、請求項１から６のいずれかに記載のパワーモジュール用基板において、前記低熱膨張材は、リブを有していることを特徴とする。
【００２０】
この発明に係るパワーモジュール用基板によれば、低熱膨張材がリブを有していると、放熱体全体としての剛性が上がり、強度を増大させることになるので、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを一層確実に抑制することになる。
【００２１】
請求項８に係る発明は、請求項６又は７に記載のパワーモジュール用基板において、前記孔は、前記低熱膨張材において、絶縁基板と対応する領域に設けられた断面積より、該対応領域の周辺領域に設けられた断面積を大きくさせていることを特徴とする。
【００２２】
この発明に係るパワーモジュール用基板によれば、低熱膨張材において、絶縁基板との対応領域に設けられた孔の断面積が、その対応領域の周辺領域に設けられた孔の断面積より小さくなっているので、放熱体の前記対応領域における曲げに対する剛性の低下を最小限に抑制することになる。これにより、絶縁基板からの熱の影響で、前記対応領域が熱変形を受けて反りが発生することを抑制することになる一方、前記対応領域より周辺領域に設けられた孔の断面積が大きくなることで、放熱体本体間の熱伝達を一層良好にさせることになる。以上により、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することになるとともに、放熱体の熱伝達を良好に行うことになる。
【００２３】
請求項９に係る発明は、絶縁基板と、該絶縁基板の一方の面に設けられた放熱体と、前記絶縁基板の他方の面に設けられた回路層とを備えたパワーモジュール用基板であって、前記放熱体は、放熱体本体と、該放熱体本体の熱膨張係数より低い材質からなる低熱膨張材とを備え、該低熱膨張材は、前記一方の面と他方の面とに亘る厚み方向と連絡し、かつ該厚み方向と交差方向で互いに連なる連絡開口部を有して設けられ、かつ該連絡開口部を介して放熱体本体に鋳ぐまれる構成としたことを特徴とする。
【００２４】
この発明に係るパワーモジュール用基板によれば、放熱体に低熱膨張材が設けられているとともに、低熱膨張材に連絡開口部を設け、この連絡開口部を介して放熱体本体を充填し、低熱膨張材が放熱体本体に鋳ぐまれる構成としたので、放熱体全体としての熱膨張係数を確実に下げることになるとともに、熱伝導率の低下を確実に抑制することになる。従って、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生するのを確実に抑制することができるとともに、放熱体自体の熱伝導率が低下することを抑制することができる。
【００２５】
請求項１０に係る発明は、請求項９記載のパワーモジュール用基板において、前記低熱膨張材は、帯状の単位板状体を同列位置で互いに組付けて前記連絡開口部を連続的に有する連鎖状体に形成し、該連鎖状体を同一平面上で複数列設けると共に、互いに隣接する列毎に前記連絡開口部の位置をずらして配設することを特徴とする。
【００２６】
この発明に係るパワーモジュール用基板によれば、帯状の単位板状体を同列位置で互いに組付けて連絡開口部を連続的に有する連鎖状体に形成し、該連鎖状体を同一平面上で複数列設けるとともに、互いに隣接する列毎に前記連絡開口部の位置をずらして配設したので、一方の面と他方の面とに亘る厚み方向に互いに連なる連絡開口部を有する低熱膨張材を確実に形成できる。
【００２７】
請求項１１に係る発明は、請求項１から１０記載のパワーモジュール用基板上にチップを搭載してなることを特徴とする。
【００２８】
この発明に係るパワーモジュールによれば、絶縁基板と放熱体との熱膨張係数の差に拘わることなく、両者の反りを可及的に抑えつつ良好な熱伝導率を有するパワーモジュールが得られる。
【００２９】
【発明の実施の形態】
以下、図面を参照し、この発明の実施の形態について説明する。図１はこの発明の第一実施形態に係るパワーモジュール用基板を適用したパワーモジュールを示す全体図である。
本第一実施形態のパワーモジュールＰにおいて、パワーモジュール用基板１０は、大別すると図１に示すように、絶縁基板１１と，放熱体１６とを備える。
絶縁基板１１は、例えばＡｌＮ，Ａｌ２Ｏ３，Ｓｉ３Ｎ４，ＳｉＣ等により所望の大きさに形成され、その上面に回路層１２が積層接合される。回路層１２は、純Ａｌ，Ａｌ合金，Ｃｕ等により形成されている。
【００３０】
絶縁基板１１の回路層１２上にはんだ１４によって半導体チップ３０が搭載される一方、絶縁基板１１の下面にはんだ１５によって、或いはろう付けや拡散接合等によって放熱体１６が接合され、更に、この放熱体１６が冷却シンク部３１に取り付けられて使用され、該冷却シンク部３１内の冷却水（或いは冷却空気）３２により、放熱体１６に伝達される熱が外部に放熱されることで、パワーモジュールＰが構成されている。放熱体１６は、冷却シンク部３１に取付ねじ３３によって密着した状態で取り付けられる。
【００３１】
また、放熱体１６の放熱体本体１７に低熱膨張材１８が、図示しないろう材を介して積層接合されている。放熱体本体１７は、例えば純Ａｌ，Ａｌ合金，Ｃｕ等，好ましくは純度９９．５％以上のＡｌ合金のような熱伝導性の良好な材質，いわゆる高熱伝導材によって形成されている。高熱伝導材としては、熱伝導率が例えば、１００Ｗ／ｍ・Ｋ以上、好ましくは１５０Ｗ／ｍ・Ｋ以上のものである。
【００３２】
一方、低熱膨張材１８は、放熱体本体１７の熱膨張係数より低い熱膨張係数の材質からなっており、放熱体本体１７に積層することで、放熱体１６全体の熱膨張係数と絶縁基板１１の熱膨張係数との差を可及的に近づけさせるためのものであり、例えばインバー合金からなっていて、熱膨張係数がおよそ５×１０−６／℃以下である。
ここで、インバー合金とは、室温付近でほとんど熱膨張が生じない合金であって、Ｆｅが６４．６ｍｏｌ％で、Ｎｉが３５．４ｍｏｌ％の組成率となっている。但し、Ｆｅ中には、それ以外の不可避不純物が含まれたものもインバー合金と呼ばれている。
【００３３】
このような材質からなる低熱膨張材１８は、図１に示すように、放熱体本体１７と１７との間に接合されている。従って、放熱体１６は二枚の放熱体本体１７と一枚の低熱膨張材１８との三層構造であって、絶縁基板１１側と冷却シンク部３１側とに放熱体本体１７が配置された構成となっている。
【００３４】
また、この低熱膨張材１８の積層方向の厚さＡは、放熱体本体１７の積層方向の厚さＢの０．０５倍以上０．１倍以下で形成されている。これは、放熱体１６自体に低熱膨張材１８を設けると、それだけ熱伝導率が低下するため、この熱伝導率の低下を極力抑えるためであるとともに、この熱伝導率の低下を抑えるために、徒に低熱膨張材１８の厚さＡを薄くすると、放熱体１６自体の熱膨張係数に寄与する低熱膨張材１８の影響が小さくなり、放熱体１６自体の熱膨張係数が放熱体本体１７の熱膨張係数と略同一となることを回避するためである。
すなわち、低熱膨張材１８の厚さＡを放熱体本体の厚さＢの０．０５倍以上０．１倍以下とすることにより、低熱膨張材１８による放熱体１６自体の熱膨張係数の低下，すなわち放熱体１６の反り発生抑制と、放熱体１６自体の熱伝導率の低下抑制とを図る構成となっている。
【００３５】
以上説明したように、本第一実施形態によるパワーモジュール用基板によれば、放熱体１６が、放熱体本体１７と低熱膨張材１８とを互いに積層して形成されているので、放熱体１６全体としての熱膨張係数を確実に下げることができ、絶縁基板１１と放熱体１６全体との熱膨張係数の差を可及的に小さくすることができる。
【００３６】
このため、絶縁基板１１と放熱体１６とをはんだ１５（若しくはろう付けや拡散接合等）によって接合した場合、放熱体１６に絶縁基板１１に向かう反りが発生することを確実に抑制することができる。これにより、放熱体１６を冷却シンク部３１に取り付けても、冷却シンク部３１と放熱体１６との間に間隙が発生することを防止することができ、放熱体１６から冷却シンク部３１への熱の伝導効率低下を抑制することができる。
【００３７】
しかも、低熱膨張材１８が金属であってかつ相応の熱伝導率を有しているので、絶縁基板１１上の半導体チップ３０からの発熱が、回路層１２，絶縁基板１１，はんだ１５，放熱体１６及び冷却シンク部３１を介して外部に良好に放熱されることになる。すなわち、パワーモジュール用基板１０全体としての熱伝導率が低下することを抑制することができ、パワーモジュール用基板１０全体としての温度上昇を抑制することができる。この結果、絶縁基板１１と放熱体１６との熱膨張係数に差があっても、放熱体１６の温度上昇を抑制することができるため、放熱体１６の反り発生抑制効果を備えた，良好なパワーモジュール用基板１０を得ることができる。
【００３８】
また、低熱膨張材１８の積層方向の厚さＡは、放熱体本体１７の積層方向の厚さＢの０．０５倍以上０．１倍以下で形成されているので、放熱体１６自体の熱伝導率を低下させることなく、熱膨張係数の低下を図ることができる。
すなわち、低熱膨張材１８の厚さＡを、放熱体本体１７の厚さＢの０．０５倍以下で形成すると、放熱体１６自体の熱伝導率の低下を抑制することはできるが、放熱体１６自体の熱膨張係数に寄与する低熱膨張材１８の影響が小さくなり、放熱体１６自体の熱膨張係数が、高熱膨張材である放熱体本体１７のものと略同一となる。また、低熱膨張材１８の厚さＡを、放熱体本体１７の厚さＢの０．１倍以上で形成すると、放熱体１６自体の熱膨張係数の低下を図ることができるが、放熱体１６自体の熱伝導率が低下することになる。以上により、前記厚さＡと厚さＢとを前記範囲に設定することにより、放熱体１６の熱膨張係数の低下，すなわち放熱体１６の反り発生抑制と、放熱体１６の熱伝導率の低下抑制とを両立させた，良好なパワーモジュール用基板１０を得ることができる。
【００３９】
次に、本発明の第二実施形態について説明するが、前述の第一実施形態と同様の部位には、同一符号を付し、その説明を省略する。
本第二実施形態によるパワーモジュール用基板は、図２，図３に示すように、低熱膨張材１８の絶縁基板１１と対応する領域に、積層方向に段差部２０が設けられている。この段差部２０は、絶縁基板１１側の熱膨張係数が低熱膨張材１８を有する放熱体１６側の熱膨張係数より大きい場合、図２に示すように、放熱体１６内において、低熱膨張材１８の絶縁基板１１と対応する領域が、冷却シンク部３１に近づくように、つまり、絶縁基板１１から遠ざかるように凹んで形成される。
【００４０】
反対に、放熱体１６側の熱膨張係数が絶縁基板１１側の熱膨張係数より大きい場合、段差部２０は、図３に示すように、放熱体１６内において、低熱膨張材１８の絶縁基板１１との対応領域を、冷却シンク部３１から遠ざかるように、つまり絶縁基板１１側に近づくように隆起して形成される。
【００４１】
つまり、放熱体１６内における低熱膨張材１８の段差部２０の位置は、絶縁基板１１側の熱膨張係数α１と放熱体１６側の熱膨張係数α２との大きさに基づいて決定され、例えばα１＜α２のとき（図２）、ｔ１（放熱体１６において絶縁基板１１との接合面から段差部２０までの厚み方向の寸法）＞ｔ２（放熱体１６において冷却シンク部３１との接合面から段差部２０までの厚み方向の寸法）となる一方、α１＞α２のとき（図３）、ｔ１＜ｔ２となる。このｔ１及びｔ２の寸法は、具体的には、α１及びα２の大きさの比率に基づいて適宜決定されることとなる。
なお、図２及び図３は、低熱膨張材１８における段差部２０の積層方向における配設位置が異なるだけであり、それ以外は同様に構成されている。
【００４２】
以上説明したように、本第二実施形態によるパワーモジュール用基板によれば、放熱体１６に低熱膨張材１８が設けられているので、基本的には前述した第一実施形態と同様の作用効果が得られる。
ところが、放熱体１６側の熱膨張係数と、絶縁基板１１側の熱膨張係数との差は、放熱体１６に低熱膨張材１８を用いているにも拘わらず、必然的に差が生じしてしまうことになる。
【００４３】
しかし、本第二実施形態では、前述のように、放熱体１６内の低熱膨張材１８において、絶縁基板１１と対応する領域に、絶縁基板１１側の熱膨張係数α１と放熱体１６側の熱膨張係数α２との大きさに基づき、絶縁基板１１側と冷却シンク部３１側とのいずれかに近づくよう段差部２０が設けられているので、以下の作用が得られる。
【００４４】
即ち、図２に示すように、絶縁基板１１側の熱膨張係数α１が低熱膨張材１８を有する放熱体１６側の熱膨張係数α２より小さい場合、低熱膨張材１８の段差部２０が、絶縁基板１１と対応する領域を、絶縁基板１１から遠ざかる方向に凹んで形成されていると、放熱体１６において、絶縁基板１１が搭載されている面と反対側の面近傍での熱膨張係数が見かけ上、下がることになる。これにより、絶縁基板１１側から放熱体１６にかけた領域は、熱膨張係数が異なる３層に分けられた構成となる。すなわち、絶縁基板１１側と、放熱体１６において絶縁基板１１が搭載されている面の反対側の面近傍との２層の低熱膨張層と、この低熱膨張層を除く放熱体１６の１層の高熱膨張層とである。従って、前記高熱膨張層が、前記２層の低熱膨張層に挟まれた構成となり、前記低熱膨張層の熱膨張係数を、パワーモジュール１０全体としての熱膨張係数に対して支配的とする構成を実現することができる。
【００４５】
これにより、絶縁基板１１側と放熱体１６側とに熱膨張係数の差があっても、放熱体１６に反りが発生することを抑制することができ、また、低熱膨張材１８が金属であってかつ相応の熱伝導率を有していることから、絶縁基板１１上の半導体チップ３０からの発熱が、回路層１２，絶縁基板１１，はんだ１５，放熱体１６及び冷却シンク部３１を介して外部に良好に放熱されることになる。すなわち、パワーモジュール用基板１０全体としての熱伝導率が低下することを抑制することができ、パワーモジュール用基板１０全体としての温度上昇を抑制することができる。この結果、絶縁基板１１と放熱体１６との熱膨張係数に差があっても、放熱体１６の温度上昇を抑制することができるため、放熱体１６の反り発生抑制効果を備えた，良好なパワーモジュール用基板１０を得ることができる。
【００４６】
一方、図３に示すように、放熱体１６側の熱膨張係数α２が絶縁基板１１側の熱膨張係数α１より小さい場合、低熱膨張材１８の段差部２０が、絶縁基板１１との対応領域を絶縁基板１１側に近づく方向に隆起して形成されていると、放熱体１６において、絶縁基板１１が搭載されている面と反対側の面近傍での熱膨張係数が見かけ上、上がることになる。これにより、絶縁基板１１側から放熱体１６にかけた領域は、熱膨張係数が異なる３層に分けられた構成となる。すなわち、絶縁基板１１側と、放熱体１６において絶縁基板１１が搭載されている面の反対側の面近傍との２層の高熱膨張層と、この高熱膨張層を除く放熱体１６の１層の低熱膨張層とである。すなわち、前記低熱膨張層が、前記２層の高熱膨張層に挟まれた構成となり、前記高熱膨張層の熱膨張係数を、パワーモジュール１０全体としての熱膨張係数に対して支配的とする構成を実現することができる。
【００４７】
その結果、絶縁基板１１と放熱体１６との熱膨張係数の差に拘わることなく、放熱体１６の反り発生抑制と熱伝導率の低下の抑制とを両立させた，良好なパワーモジュール用基板１０を得ることができる。
【００４８】
次に、本発明の第三実施形態について説明するが、前述の第一，第二実施形態と同様の部位には、同一符号を付し、その説明を省略する。
本第三実施形態によるパワーモジュール用基板は、図４，図５に示すように、低熱膨張材１８にこれを貫通する孔１９が複数穿設され、この孔１９に放熱体本体１７が充填され、低熱膨張材１８が放熱体本体１７に鋳ぐまれた構成となっている。孔１９は、放熱体１６自体に低熱膨張材１８を設けると、それだけ熱伝導率が低下するので、その熱伝導率が低下するのを極力抑えるようにするためのものである。また、孔１９は、図５に示すように、低熱膨張材１８において、絶縁基板１１と対応する領域Ａには孔１９の穿設される数を少なくするとともに、前記対応領域Ａの周辺領域Ｂには孔１９の穿設される数を多くしている。
【００４９】
つまり、低熱膨張材１８において絶縁基板１１との対応領域Ａと、これを除く周辺領域Ｂとでは、孔１９の断面積の分布が異なった構成となっている。これは、対応領域Ａにおける放熱体１６の曲げに対する剛性低下と、放熱体１６全体の熱伝導率の低下とを最小限に抑制するためのものである。ここで、低熱膨張材１８に穿設される孔１９の数が徒らに増えると、低熱膨張材としての機能を果たし難くなることから、低熱膨張材１８の表面積に対し、絶縁基板１１，放熱体本体１７及び低熱膨張材１８の材質等に基づき、およそ２０〜５０％の割合の面積で孔１９が形成されることが好ましい。なお、孔１９は、本実施形態では丸孔をなしているが、その形状は任意である。また、図４は、図３に対応させて図示しており、冷却シンク部３１が省略されている。
【００５０】
以上説明したように、本第三実施形態によるパワーモジュール用基板によれば、低熱膨張材１８に段差部２０が設けられているので、放熱体１６側と絶縁基板１１側との熱膨張係数差を見かけ上小さくすることができ、放熱体１６の反り発生を抑制することができる。
これに加え、低熱膨張材１８に孔１９が設けられ、この孔１９に放熱体本体１７を充填し低熱膨張材１８を放熱体本体１７により鋳ぐるませた構成となっているので、絶縁基板１１側の放熱体本体１７から冷却シンク部３１側の放熱体本体１７への熱伝達を良好に行うことができ、これによって、放熱体１６本来の放熱効果を的確に果たすことができる。
【００５１】
しかも孔１９は、図５に示すように、絶縁基板１１との対応領域Ａでは、その周辺領域Ｂより少ない個数で穿設され、孔１９の断面積が周辺領域Ｂでのそれより少なくした構成となっているので、放熱体１６の対応領域Ａにおける曲げに対する剛性の低下を最小限に抑制することができる一方、周辺領域Ｂ内の孔１９の断面積が対応領域Ａより大きくなることで、放熱体１６全体の熱伝導率の低下を最小限に抑制することができる。
【００５２】
なお、本実施形態においては、低熱膨張材１８に設けられた孔１９に放熱体本体１７を鋳ぐませた構成を示したが、孔１９に放熱体本体１７と同一材質の平板又は粉末材料を低熱膨張材１８の厚さ分だけ充填した後、この低熱膨張材１８の上下面に放熱体本体１７をろう材を介して積層接合させた構成としてもよい。
【００５３】
次に、本発明の第四実施形態について説明するが、前述の第一〜第三実施形態と同様の部位には、同一符号を付し、その説明を省略する。
本第四実施形態によるパワーモジュール用基板は、図６，図７に示すように、放熱体１６に設けられた低熱膨張材１８がリブ（符示せず）を有している。
リブは、低熱膨張材１８に設けられる孔１９を形成する際に、予め所定の厚みに形成された板材に図６に示す切り込み（１８ａ、１８ｂ）を形成し、この切り込みを利用することで形成される。即ち、予め設けられた切り込みを上下方向に立上げたり，立下げたりして折り曲げることで、立上げ片１８ａ及び立下げ片１８ｂが共に形成され、これらからなるリブを有する低熱膨張材１８が形成される。
そして、この低熱膨張材１８が放熱体本体１７と１７との間に挟着され、この際、立ち上げ片１８ａ，立ち下げ片１８ｂ及び孔１９を有する低熱膨張材１８全体が放熱体本体１７に鋳ぐまれることで、放熱体１６が形成される。
【００５４】
以上説明したように、本第四実施形態によるパワーモジュール用基板によれば、放熱体１６が、放熱体本体１７と孔１９を備えた低熱膨張材１８とを備え、放熱体本体１７が孔１９に充填され低熱膨張材１８を鋳ぐるんだ構成をなしているので、基本的は前述した第三実施形態と同様の作用効果が得られる。
これに加え、低熱膨張材１８が立上げ片１８ａ及び立下げ片１８ｂからなるリブを有しているので、放熱体１６全体としての剛性が上がり、強度を増大させることができるので、これによっても、絶縁基板１１の熱による反りをより一層抑えることができる。
【００５５】
なお、低熱膨張材１８は、本第四実施形態では、放熱体本体１７間に積層されたり、また放熱体本体１７間に挟着することで設けられた例を示したが、これに限らず、例えば、粉末冶金によって孔１９付き板を焼成した後、これにリブを後付けして設けるようにしてもよく、又は、ダイカスト鋳造法によって形成することもでき、更には、熱間鍛造により高温処理される溶融鍛造法によって形成することもできる。それ以外として、以下に示すように放熱体１６を構成することもできる。
【００５６】
次に、本発明の第五実施形態について説明するが、前述の第一〜第四実施形態と同様の部位には、同一符号を付し、その説明を省略する。
本第五実施形態によるパワーモジュール用基板は、図８，図９に示すように、低熱膨張材１８が、絶縁基板１１側の放熱体本体１７と接合される一方の面と、冷却シンク部３１側の放熱体本体１７と接合される他方の面とに亘る厚み方向に連絡すると共に、該厚み方向と交差方向で互いに連なる開口空間部４０を有して設けられ、かつ該開口空間部４０に放熱体本体１７が充填されることで、図８に示すように、放熱体本体１７に鋳ぐまれる構成となっている。
【００５７】
具体的に述べると、低熱膨張材１８は、図９に示すように、例えば二枚からなる帯状の単位板状体４１，４２を前記厚み方向に沿って組付けることで連結開口部４０を連続的に有する連鎖状体４３が形成される。そして、これら連鎖状体４３が同一平面上で複数列設けられると共に、連設開口部４０を互いに隣接する列毎に互い違いに配列して形成される。
【００５８】
このように形成された低熱膨張材１８は、放熱体１６の形成時、放熱体本体１７の材料が注入されると、その材料が連結開口部４０内に側方から充填される。そして、この低熱膨張材１８は、側面から見たとき、図８に示すように、絶縁基板１１側である上層の放熱体本体１７と、冷却シンク部３１側である下層の放熱体本体１７との間に埋設されることになる。
【００５９】
以上説明したように本第五実施形態によるパワーモジュール用基板によれば、低熱膨張材１８が前記厚み方向に沿って放熱体本体１７に鋳ぐまれているので、放熱体１６全体の熱膨張係数を下げることができ、また連絡開口部４０により放熱体本体１７が絶縁基板１１からの熱を良好に受けると共に、その熱を冷却シンク部３１に対して伝達させることができる。従って、放熱体１６の反りを抑えつつ熱伝達が良好となり、基本的には前述した第一〜第四実施形態と同様の作用効果が得られる。
【００６０】
なお、前述の第一〜第五実施形態では、放熱体に積層された低熱膨張材として、インバーを用いた例を示したが、他の低熱膨張材、例えば高炭素鋼（Ｆｅ−Ｃ）、４２合金、モリブデン（Ｍｏ）、タングステン（Ｗ）等で構成しても、同様の作用効果が得られる。
また、放熱体１６表面に冷却シンク部３１を設けた構成を示したが、この形態に限らず、放熱体１６表面にろう材を介してコルゲートフィンを設けた構成としてもよい。すなわち、放熱体１６表面に図示しないろう材を介して接合された接合部と、接合部の一端に設けられ接合部と直交して立上がる立上がり部と、立上がり部の上端に設けられ接合部に平行且つ離間する方向に延びる平坦部と、平坦部の一端に設けられ平坦部に直交且つ放熱体１６に向かって折返る折返し部とを備えた突出部を、放熱体１６の沿面方向に沿って繰返し連続して設けた構成としてもよい。なお、この構成においては、立上がり部と平坦部と折返し部と放熱体１６表面とが空間を形成することになる。
さらに、前述した第五実施形態に示す低熱膨張材１８に替えて，いわゆるコルゲート，コルゲートルーバ，厚さ方向にエキスパンドした断面矩形の連絡開口部４０を有するエキスパンド構造，若しくは第五実施形態で示したいわゆる，ハニカム構造を一層設けたもの，又は前記構造のうちの一つを複数積層させた構成としてもよい。
【００６１】
【発明の効果】
以上説明したように、請求項１に係る発明によれば、放熱体全体の熱膨張係数を確実に下げ、絶縁基板と放熱体全体との熱膨張係数の差を可及的に小さくすることができる。このため、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することができる。
【００６２】
請求項２に係る発明によれば、放熱体全体の熱膨張係数を確実に下げるとともに、放熱体全体の熱伝導率の低下を最小限に抑制することができる。これにより、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを抑制するとともに、必要最小限の熱伝導率を有した放熱体を備えたパワーモジュール用基板を提供することができる。
【００６３】
請求項３に係る発明によれば、放熱体全体の熱膨張係数に寄与する低熱膨張材の影響を必要最小限維持することになり、放熱体全体としての熱膨張係数を確実に下げ、絶縁基板と放熱体全体との熱膨張係数の差を可及的に小さくすることができる。このため、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することができる。
【００６４】
請求項４に係る発明によれば、絶縁基板とこの絶縁基板と対応する領域における放熱体との熱膨張係数の差を確実に緩和することができる。これにより、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することができる。
【００６５】
請求項５に係る発明によれば、低熱膨張材が、放熱体の絶縁基板と対応した領域における熱膨張係数に与える影響を調整することができ、放熱体の熱膨張係数を見かけ上調整できる構成となっている。これにより、絶縁基板と、この絶縁基板と対応する領域における放熱体との熱膨張係数の差を緩和することができ、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することができる。
【００６６】
請求項６に係る発明によれば、低熱膨張材の上下面に各々放熱体本体を設け、低熱膨張材に設けられた孔に放熱体本体を充填し、低熱膨張材を放熱体本体で鋳ぐむ構成とすることができ、これにより、孔を介して放熱体の上下面に配設される放熱体本体同士を直接接する構成とすることができる。従って、絶縁基板からの熱を確実に放熱体の積層方向に伝達し、この熱を外部に効率的に放熱することができる。以上により、放熱体の熱膨張係数の低下と熱伝導率の低下抑制とを確実に実現することができる。
【００６７】
請求項７に係る発明によれば、低熱膨張材がリブを有しているので、放熱体全体としての剛性を上げ、強度を増大させることができるので、放熱体の絶縁基板に向かう反り発生を確実に抑制することができる。
【００６８】
請求項８に係る発明によれば、低熱膨張材において、絶縁基板との対応領域に設けられた孔の断面積が、その対応領域の周辺領域に設けられた孔の断面積より少なくなっているので、放熱体の前記対応領域における曲げに対する剛性の低下を最小限に抑制することができる。これにより、絶縁基板からの熱の影響で、前記対応領域が熱変形を受けて反りが発生することを抑制することができる一方、前記対応領域より周辺領域に設けられた孔の断面積が大きくなることで、放熱体の熱伝導率の低下を最小限に抑制するできる。
【００６９】
請求項９に係る発明によれば、放熱体全体としての熱膨張係数を確実に下げることができるとともに、熱伝導率の低下を確実に抑制することができる。従って、絶縁基板と放熱体とをはんだ等によって接合した場合、放熱体に絶縁基板に向かう反りが発生することを確実に抑制することができるとともに、放熱体自体の熱伝導率が低下することを抑制することができる。
【００７０】
請求項１０に係る発明によれば、帯状の単位板状体を同列位置で互いに組付けて連絡開口部を連続的に有する連鎖状体に形成し、該連鎖状体を同一平面上で複数列設けるとともに、互いに隣接する列毎に前記連絡開口部の位置をずらして配設したので、一方の面と他方の面とに亘る厚み方向に互いに連なる連絡開口部を有する低熱膨張材を確実に形成できる。
【００７１】
請求項１１に係る発明によれば、絶縁基板と放熱体との熱膨張係数の差に拘わることなく、両者の反りを可及的に抑えつつ良好な熱伝導率を有するパワーモジュールが得られる。
【図面の簡単な説明】
【図１】この発明の第一実施形態に係るパワーモジュール用基板を適用したパワーモジュールを示す全体図である。
【図２】この発明の第二実施形態に係るパワーモジュール用基板を適用したパワーモジュールを示す全体図であって、絶縁基板側の熱膨張係数が放熱体側の熱膨張係数より大きい場合を示す図である。
【図３】この発明の第二実施形態に係るパワーモジュール用基板を適用したパワーモジュールを示す全体図であって、放熱体側の熱膨張係数が絶縁基板側の熱膨張係数より大きい場合を示す図である。
【図４】この発明の第三実施形態に係るパワーモジュール用基板を適用したパワーモジュール示す全体図である。
【図５】図４に示す低熱膨張材の平面図である。
【図６】この発明の第四実施形態に係るパワーモジュール用基板を適用したパワーモジュールを示す全体図である。
【図７】図６に示す低熱膨張材の平面図である。
【図８】この発明の第五実施形態に係るパワーモジュール用基板を構成する放熱体の断面側面図である。
【図９】図８に示す低熱膨張材の要部を示す斜視図である。
【符号の説明】
Ｐ　　パワーモジュール
１０　パワーモジュール用基板
１１　絶縁基板
１６　放熱体
１７　放熱体本体（高熱伝導材）
１８　低熱膨張材
１８ａ　立ち上げ片（リブ）
１８ｂ　立ち下げ片（リブ）
１９　孔
２０　段差部
３０　半導体チップ（チップ）
４０　連絡開口部
４１，４２　板状体
４３　連鎖状体
α１　絶縁基板側の熱膨張係数
α２　放熱体側の熱膨張係数
Ａ　低熱膨張材の積層方向の厚さ
Ｂ　放熱体本体（高熱伝導材）の積層方向の厚さ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power module substrate used in a semiconductor device for controlling a large voltage and a large current, and more particularly to a power module substrate and a power module having a radiator for dissipating heat generated from a heating element such as a semiconductor chip. .
[0002]
[Prior art]
In this type of power module substrate, a circuit layer is provided on one surface of an insulating substrate (ceramic substrate) made of a ceramic material, and a radiator is provided on the other surface. In general, a cooling sink having a cooling means such as cooling water is provided on the facing surface. However, when the radiator is laminated and bonded to the insulating substrate with solder or the like, the radiator warps toward the insulating substrate due to the heat at that time and the difference in the coefficient of thermal expansion between the insulating substrate and the radiator. In some cases, a gap may be formed between the radiator and the insulating substrate. In this case, there is a problem that heat generated when the semiconductor chip provided on the circuit layer generates heat cannot be transmitted to the heat radiator satisfactorily.
[0003]
As means for solving such a problem, for example, a technique as disclosed in Patent Document 1 is disclosed. This document discloses a configuration in which a metal plate (for example, a 42 alloy) having substantially the same thermal expansion coefficient as the insulating substrate is provided on a surface of the radiator facing the insulating substrate forming surface in the above-described configuration. I have. With this configuration, even if there is a difference in the coefficient of thermal expansion between the insulating substrate and the radiator, it is possible to suppress the warpage of the radiator.
[0004]
[Patent Document 1]
JP-A-1-286348 (pages 2-4, FIGS. 1-3)
[0005]
[Problems to be solved by the invention]
By the way, in the conventional power module substrate described above, since the metal plate is provided on the surface of the heat radiator opposite to the surface on which the insulating substrate is formed, heat generated by the heat generated by the semiconductor chip provided on the circuit layer is removed by the power module. However, there is a problem that it cannot be transmitted well in the stacking direction of the substrate. That is, there is a problem that after the heat transmitted from the semiconductor chip to the insulating substrate reaches the radiator, the heat stops at the metal plate and cannot be radiated well. In this case, the temperature of the entire power module substrate rises, and as a result, warping of the heat radiator toward the insulating substrate further occurs, causing a problem that the heat conductivity of the heat radiator further decreases.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to suppress warpage regardless of a difference in thermal expansion coefficient between an insulating substrate and a radiator. It is another object of the present invention to provide a power module substrate and a power module that can suppress a decrease in thermal conductivity.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 is a power module substrate including an insulating substrate, a radiator provided on one surface of the insulating substrate, and a circuit layer provided on the other surface of the insulating substrate. The radiator is characterized in that a low thermal expansion material made of a material having a lower thermal expansion coefficient than the radiator main body is laminated on the radiator main body.
[0008]
According to the power module substrate of the present invention, since the radiator has a configuration in which the radiator body and the low thermal expansion material are laminated, the thermal expansion coefficient of the entire radiator is reliably reduced, and the insulating substrate and the radiator The difference in the coefficient of thermal expansion from the whole body becomes as small as possible. For this reason, when the insulating substrate and the heat radiator are joined by solder or the like, it is possible to surely prevent the heat radiator from warping toward the insulating substrate.
[0009]
According to a second aspect of the present invention, in the power module substrate according to the first aspect, a thickness of the low thermal expansion material is formed to be 0.1 times or less a thickness of the radiator body. I do.
[0010]
According to the power module substrate of the present invention, since the thickness of the low thermal expansion material is formed to be 0.1 times or less the thickness of the radiator body, the thermal expansion coefficient of the entire radiator is reliably reduced. At the same time, a decrease in the thermal conductivity of the entire radiator is suppressed to a minimum. In this way, when the insulating substrate and the heat radiator are joined by solder or the like, the heat radiator is prevented from warping toward the insulating substrate, and the power provided with the heat radiator having the minimum necessary thermal conductivity. A module substrate can be provided.
[0011]
According to a third aspect of the present invention, in the power module substrate according to the first or second aspect, the thickness of the low thermal expansion material in the stacking direction is 0.05 times or more the thickness of the heat radiator body in the stacking direction. It is characterized by being formed by.
[0012]
According to the power module substrate of the present invention, the thickness of the low thermal expansion material is formed to be at least 0.05 times the thickness of the radiator main body, so that the low thermal expansion material contributes to the thermal expansion coefficient of the entire radiator. Since the influence of the expansion material is kept to a minimum, the thermal expansion coefficient of the entire radiator is reliably reduced, and the difference in the thermal expansion coefficient between the insulating substrate and the entire radiator is reduced as much as possible. For this reason, when the insulating substrate and the heat radiator are joined by solder or the like, it is possible to surely prevent the heat radiator from warping toward the insulating substrate.
[0013]
According to a fourth aspect of the present invention, in the power module substrate according to any one of the first to third aspects, the thermal expansion coefficient on the heat radiator side and the heat on the insulating substrate side are provided in a region corresponding to the insulating substrate of the low thermal expansion material. A step portion is provided based on a difference from an expansion coefficient.
[0014]
According to the power module substrate of the present invention, the stepped portion is provided in the region corresponding to the insulating substrate of the low thermal expansion material based on the difference in thermal expansion coefficient between the radiator and the insulating substrate. This reduces the difference in the coefficient of thermal expansion between the body and the insulating substrate. Thus, when the insulating substrate and the radiator are joined by solder or the like, it is possible to reliably suppress the occurrence of warpage of the radiator toward the insulating substrate.
[0015]
According to a fifth aspect of the present invention, in the power module substrate according to any one of the first to fourth aspects, in the heat sink, the step portion has a thermal expansion coefficient on the insulating substrate side smaller than that on the heat radiator side. When the region corresponding to the insulating substrate of the low thermal expansion material is formed so as to be depressed in a direction away from the insulating substrate, while the thermal expansion coefficient of the radiator side is smaller than the thermal expansion coefficient of the insulating substrate side, the low thermal expansion material A region corresponding to the insulating substrate is formed so as to protrude in a direction approaching the insulating substrate.
[0016]
According to the power module substrate according to the present invention, the disposition position of the low thermal expansion material in the stacking direction is changed according to the difference between the thermal expansion coefficient on the insulating substrate side and the thermal expansion coefficient on the radiator side. The effect of the low thermal expansion material on the thermal expansion coefficient in the region corresponding to the insulating substrate of the radiator can be adjusted, and the thermal expansion coefficient of the radiator can be apparently adjusted. This makes it possible to reliably reduce the difference in the coefficient of thermal expansion between the insulating substrate and the radiator in a region corresponding to the insulating substrate. The occurrence of warpage toward the insulating substrate is surely suppressed.
[0017]
According to a sixth aspect of the present invention, in the power module substrate according to any one of the first to fifth aspects, the low thermal expansion material has a hole formed therethrough.
[0018]
ADVANTAGE OF THE INVENTION According to the board | substrate for power modules which concerns on this invention, it can be set as the structure which fills the hole provided in the low thermal expansion material with the radiator main body, and casts the low thermal expansion material into the radiator main body, The heat from the insulating substrate is surely transmitted in the laminating direction of the radiator through the hole of the expansion material, and this heat is radiated well to the outside. As described above, the reduction of the thermal expansion coefficient of the radiator and the suppression of the reduction of the thermal conductivity are reliably realized. Further, in addition to the configuration in which the radiator body is cast into the hole provided in the low thermal expansion material, a flat plate or a powder material of the same material as the radiator body is filled into the hole by the thickness of the low thermal expansion material, The same effect as described above can also be achieved by a configuration in which the radiator body is laminated and joined to the upper and lower surfaces of the low thermal expansion material via a brazing material.
[0019]
The invention according to claim 7 is the power module substrate according to any one of claims 1 to 6, wherein the low thermal expansion material has a rib.
[0020]
According to the power module substrate of the present invention, if the low-thermal-expansion material has ribs, the rigidity of the entire radiator is increased, and the strength is increased. In the case of joining by such as above, the occurrence of warpage toward the insulating substrate in the radiator is more reliably suppressed.
[0021]
According to an eighth aspect of the present invention, in the power module substrate according to the sixth or seventh aspect, the hole is formed in a region corresponding to the insulating substrate in the low thermal expansion material, based on a cross-sectional area provided in the region corresponding to the insulating substrate. The cross-sectional area provided in the peripheral area is increased.
[0022]
According to the power module substrate of the present invention, in the low thermal expansion material, the cross-sectional area of the hole provided in the region corresponding to the insulating substrate is smaller than the cross-sectional area of the hole provided in the peripheral region of the corresponding region. Therefore, a decrease in rigidity of the heat radiator against bending in the corresponding region is suppressed to a minimum. This suppresses the occurrence of warpage due to thermal deformation of the corresponding region due to the influence of heat from the insulating substrate, while the cross-sectional area of the hole provided in the peripheral region is larger than that of the corresponding region. As a result, the heat transfer between the radiator main bodies is further improved. As described above, when the insulating substrate and the heat radiator are joined by solder or the like, it is possible to reliably suppress the occurrence of warpage of the heat radiator toward the insulating substrate, and to achieve good heat transfer of the heat radiator. Become.
[0023]
The invention according to claim 9 is a power module substrate including an insulating substrate, a radiator provided on one surface of the insulating substrate, and a circuit layer provided on the other surface of the insulating substrate. The radiator includes a radiator body and a low-thermal-expansion material made of a material having a lower thermal expansion coefficient than the radiator body, and the low-thermal-expansion material has a thickness extending between the one surface and the other surface. A communication opening is provided so as to communicate with the direction and intersect with the thickness direction, and is formed so as to be cast into the radiator body through the communication opening.
[0024]
According to the power module substrate of the present invention, the radiator is provided with the low thermal expansion material, the low thermal expansion material is provided with a communication opening, and the radiator main body is filled through the communication opening to reduce the heat dissipation. Since the expansion material is cast into the radiator body, the thermal expansion coefficient of the radiator as a whole can be reliably reduced, and a decrease in thermal conductivity can be reliably suppressed. Therefore, when the insulating substrate and the heat radiator are joined by solder or the like, it is possible to reliably prevent the heat radiator from warping toward the insulating substrate, and to reduce the thermal conductivity of the heat radiator itself. Can be suppressed.
[0025]
According to a tenth aspect of the present invention, in the power module substrate according to the ninth aspect, the low thermal expansion material has a chain-shaped unit plate-like body assembled to each other at the same row position to continuously have the communication opening. And a plurality of rows of the chain-like bodies are provided on the same plane, and the positions of the communication openings are shifted from each other in adjacent rows.
[0026]
ADVANTAGE OF THE INVENTION According to the board | substrate for power modules which concerns on this invention, a strip | belt-shaped unit plate-shaped object is assembled | attached to the same row position mutually, and it forms in the chain-shaped body which has a communication opening continuously, and the said chain-shaped body on the same plane Since a plurality of rows are provided and the positions of the communication openings are shifted from each other in adjacent rows, a low-thermal-expansion material having communication openings that are continuous with each other in the thickness direction across one surface and the other surface is reliably provided. Can be formed.
[0027]
An eleventh aspect of the present invention is characterized in that a chip is mounted on the power module substrate according to any one of the first to tenth aspects.
[0028]
ADVANTAGE OF THE INVENTION According to the power module which concerns on this invention, the power module which has favorable thermal conductivity, suppressing the curvature of both as much as possible, regardless of the difference of the thermal expansion coefficient of an insulating substrate and a heat sink.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall view showing a power module to which a power module substrate according to a first embodiment of the present invention is applied.
In the power module P according to the first embodiment, the power module substrate 10 includes an insulating substrate 11 and a radiator 16 as roughly shown in FIG.
The insulating substrate 11 is made of, for example, AlN, Al 2 O 3 , Si 3 N 4 , SiC or the like, and the circuit layer 12 is laminated and joined to the upper surface thereof. The circuit layer 12 is formed of pure Al, an Al alloy, Cu, or the like.
[0030]
The semiconductor chip 30 is mounted on the circuit layer 12 of the insulating substrate 11 by solder 14, and the radiator 16 is bonded to the lower surface of the insulating substrate 11 by solder 15 or by brazing or diffusion bonding. The body 16 is used by being attached to the cooling sink portion 31, and the heat transmitted to the radiator 16 is radiated to the outside by the cooling water (or cooling air) 32 in the cooling sink portion 31, so that the power module is P is configured. The heat radiator 16 is attached to the cooling sink portion 31 in a state of being in close contact with the attachment screw 33.
[0031]
Further, a low thermal expansion material 18 is laminated and joined to a radiator body 17 of the radiator 16 via a brazing material (not shown). The radiator body 17 is made of a material having good heat conductivity, such as pure Al, an Al alloy, Cu, or the like, preferably an Al alloy having a purity of 99.5% or more, that is, a so-called high heat conductive material. The high thermal conductive material has a thermal conductivity of, for example, 100 W / m · K or more, preferably 150 W / m · K or more.
[0032]
On the other hand, the low thermal expansion material 18 is made of a material having a lower thermal expansion coefficient than the thermal expansion coefficient of the radiator main body 17. Is made to be as close as possible to the difference in thermal expansion coefficient, for example, made of an Invar alloy and having a thermal expansion coefficient of about 5 × 10 -6 / ° C or lower.
Here, the invar alloy is an alloy that hardly undergoes thermal expansion near room temperature, and has a composition ratio of 64.6 mol% of Fe and 35.4 mol% of Ni. However, Fe containing other unavoidable impurities is also called an Invar alloy.
[0033]
As shown in FIG. 1, the low thermal expansion material 18 made of such a material is joined between the radiator bodies 17. Therefore, the heat radiator 16 has a three-layer structure of two heat radiator bodies 17 and one low thermal expansion material 18, and the heat radiator bodies 17 are arranged on the insulating substrate 11 side and the cooling sink part 31 side. It has a configuration.
[0034]
The thickness A of the low thermal expansion material 18 in the stacking direction is formed to be 0.05 times or more and 0.1 times or less the thickness B of the heat radiator body 17 in the stacking direction. This is because when the low thermal expansion material 18 is provided on the heat radiator 16 itself, the thermal conductivity is reduced accordingly, so that the reduction in the thermal conductivity is suppressed as much as possible. However, if the thickness A of the low thermal expansion material 18 is reduced, the influence of the low thermal expansion material 18 contributing to the thermal expansion coefficient of the heat radiator 16 itself is reduced, and the thermal expansion coefficient of the heat radiator 16 itself is reduced by the heat of the radiator body 17. This is to prevent the coefficient of expansion from being substantially the same.
That is, by setting the thickness A of the low thermal expansion material 18 to 0.05 times or more and 0.1 times or less of the thickness B of the radiator main body, the low thermal expansion material 18 reduces the thermal expansion coefficient of the radiator 16 itself, That is, the configuration is designed to suppress the occurrence of warpage of the heat radiator 16 and to suppress a decrease in the thermal conductivity of the heat radiator 16 itself.
[0035]
As described above, according to the power module substrate of the first embodiment, the radiator 16 is formed by laminating the radiator main body 17 and the low thermal expansion material 18 on each other. Can be reliably reduced, and the difference in the coefficient of thermal expansion between the insulating substrate 11 and the entire radiator 16 can be made as small as possible.
[0036]
For this reason, when the insulating substrate 11 and the radiator 16 are joined by the solder 15 (or brazing, diffusion bonding, or the like), it is possible to reliably suppress the radiator 16 from warping toward the insulating substrate 11. . Thereby, even if the heat radiator 16 is attached to the cooling sink 31, it is possible to prevent a gap from being generated between the cooling sink 31 and the heat radiator 16. A decrease in heat conduction efficiency can be suppressed.
[0037]
Moreover, since the low thermal expansion material 18 is made of metal and has a suitable thermal conductivity, heat generated from the semiconductor chip 30 on the insulating substrate 11 is generated by the circuit layer 12, the insulating substrate 11, the solder 15, and the radiator. The heat is satisfactorily radiated to the outside via the cooling sink 16 and the cooling sink portion 31. That is, a decrease in the thermal conductivity of the entire power module substrate 10 can be suppressed, and a rise in the temperature of the entire power module substrate 10 can be suppressed. As a result, even if there is a difference in the coefficient of thermal expansion between the insulating substrate 11 and the heat radiator 16, the temperature rise of the heat radiator 16 can be suppressed. The power module substrate 10 can be obtained.
[0038]
Further, the thickness A of the low thermal expansion material 18 in the stacking direction is formed to be 0.05 times or more and 0.1 times or less the thickness B of the heat radiator body 17 in the stacking direction. The thermal expansion coefficient can be reduced without lowering the conductivity.
That is, when the thickness A of the low thermal expansion material 18 is formed to be 0.05 times or less of the thickness B of the radiator main body 17, a decrease in the thermal conductivity of the radiator 16 itself can be suppressed. The influence of the low thermal expansion material 18 that contributes to the thermal expansion coefficient of the heat radiator 16 itself is reduced, and the thermal expansion coefficient of the heat radiator 16 itself becomes substantially the same as that of the heat radiator body 17 that is a high thermal expansion material. Further, when the thickness A of the low thermal expansion material 18 is formed to be 0.1 times or more the thickness B of the radiator body 17, the thermal expansion coefficient of the radiator 16 itself can be reduced. The thermal conductivity of itself will decrease. As described above, by setting the thickness A and the thickness B within the above range, the thermal expansion coefficient of the heat radiator 16 is reduced, that is, the warpage of the heat radiator 16 is suppressed, and the thermal conductivity of the heat radiator 16 is reduced. It is possible to obtain a good power module substrate 10 that achieves both suppression and improvement.
[0039]
Next, a second embodiment of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.
In the power module substrate according to the second embodiment, as shown in FIGS. 2 and 3, a step portion 20 is provided in a region corresponding to the insulating substrate 11 of the low thermal expansion material 18 in the laminating direction. When the thermal expansion coefficient on the side of the insulating substrate 11 is larger than the thermal expansion coefficient on the side of the heat radiator 16 having the low thermal expansion material 18, as shown in FIG. The region corresponding to the insulating substrate 11 is formed so as to be recessed so as to approach the cooling sink portion 31, that is, away from the insulating substrate 11.
[0040]
Conversely, when the thermal expansion coefficient on the heat radiator 16 side is larger than the thermal expansion coefficient on the insulating substrate 11 side, as shown in FIG. Is formed so as to protrude away from the cooling sink portion 31, that is, closer to the insulating substrate 11 side.
[0041]
That is, the position of the step portion 20 of the low thermal expansion material 18 in the heat radiator 16 is determined based on the magnitude of the thermal expansion coefficient α1 on the insulating substrate 11 side and the thermal expansion coefficient α2 on the heat radiator 16 side. <Α2 (FIG. 2), t1 (dimension in the thickness direction from the joint surface with the insulating substrate 11 to the step portion 20 in the heat radiator 16)> t2 (step from the joint surface with the cooling sink portion 31 in the heat radiator 16) On the other hand, when α1> α2 (FIG. 3), t1 <t2. Specifically, the dimensions of t1 and t2 are appropriately determined based on the ratio of the magnitudes of α1 and α2.
2 and 3 are different from each other only in the arrangement position of the stepped portion 20 in the low thermal expansion material 18 in the laminating direction.
[0042]
As described above, according to the power module substrate according to the second embodiment, since the heat radiator 16 is provided with the low thermal expansion material 18, basically the same operation and effect as those of the first embodiment described above. Is obtained.
However, the difference between the thermal expansion coefficient on the heat radiator 16 side and the thermal expansion coefficient on the insulating substrate 11 side inevitably occurs even though the low thermal expansion material 18 is used for the heat radiator 16. Will be lost.
[0043]
However, in the second embodiment, as described above, in the low thermal expansion material 18 in the heat radiator 16, the area corresponding to the insulating substrate 11 has a thermal expansion coefficient α1 on the insulating substrate 11 side and a heat expansion coefficient on the heat radiator 16 side. Since the step portion 20 is provided so as to approach either the insulating substrate 11 side or the cooling sink portion 31 side based on the magnitude of the expansion coefficient α2, the following operation is obtained.
[0044]
That is, as shown in FIG. 2, when the thermal expansion coefficient α1 on the insulating substrate 11 side is smaller than the thermal expansion coefficient α2 on the radiator 16 side having the low thermal expansion material 18, the step 20 of the low thermal expansion material 18 If the area corresponding to 11 is recessed in the direction away from the insulating substrate 11, the thermal expansion coefficient of the radiator 16 near the surface opposite to the surface on which the insulating substrate 11 is mounted will be apparent. , Will go down. Thus, the region extending from the insulating substrate 11 side to the heat radiator 16 is configured to be divided into three layers having different thermal expansion coefficients. That is, two low-thermal-expansion layers on the insulating substrate 11 side and near the surface opposite to the surface on which the insulating substrate 11 is mounted on the radiator 16, and one layer of the radiator 16 excluding the low-thermal-expansion layer High thermal expansion layer. Therefore, the high thermal expansion layer is sandwiched between the two low thermal expansion layers, and the thermal expansion coefficient of the low thermal expansion layer is dominant to the thermal expansion coefficient of the power module 10 as a whole. Can be realized.
[0045]
Thereby, even if there is a difference in the coefficient of thermal expansion between the insulating substrate 11 side and the radiator 16 side, it is possible to prevent the radiator 16 from being warped, and the low thermal expansion material 18 is made of metal. And has a suitable thermal conductivity, the heat generated from the semiconductor chip 30 on the insulating substrate 11 is generated via the circuit layer 12, the insulating substrate 11, the solder 15, the radiator 16, and the cooling sink 31. Good heat is radiated to the outside. That is, a decrease in the thermal conductivity of the entire power module substrate 10 can be suppressed, and a rise in the temperature of the entire power module substrate 10 can be suppressed. As a result, even if there is a difference in the coefficient of thermal expansion between the insulating substrate 11 and the heat radiator 16, the temperature rise of the heat radiator 16 can be suppressed. The power module substrate 10 can be obtained.
[0046]
On the other hand, as shown in FIG. 3, when the thermal expansion coefficient α2 on the radiator 16 side is smaller than the thermal expansion coefficient α1 on the insulating substrate 11 side, the step portion 20 of the low thermal expansion material 18 When the heat radiator 16 is formed so as to protrude in the direction approaching the insulating substrate 11 side, the thermal expansion coefficient in the vicinity of the surface opposite to the surface on which the insulating substrate 11 is mounted is apparently increased. . Thus, the region extending from the insulating substrate 11 side to the heat radiator 16 is configured to be divided into three layers having different thermal expansion coefficients. That is, two layers of the high thermal expansion layer on the side of the insulating substrate 11 and near the surface opposite to the surface on which the insulating substrate 11 is mounted on the heat radiator 16, and one layer of the heat radiator 16 excluding the high thermal expansion layer And a low thermal expansion layer. That is, the low thermal expansion layer is sandwiched between the two high thermal expansion layers, and the thermal expansion coefficient of the high thermal expansion layer is dominant to the thermal expansion coefficient of the power module 10 as a whole. Can be realized.
[0047]
As a result, regardless of the difference in the coefficient of thermal expansion between the insulating substrate 11 and the radiator 16, a good power module substrate 10 that achieves both suppression of warpage of the radiator 16 and suppression of a decrease in thermal conductivity. Can be obtained.
[0048]
Next, a third embodiment of the present invention will be described. Parts similar to those in the above-described first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.
In the power module substrate according to the third embodiment, as shown in FIGS. 4 and 5, a plurality of holes 19 penetrating through the low thermal expansion material 18 and the radiator body 17 is filled in the holes 19. The heat radiator body 17 has a low thermal expansion material 18 cast therein. The holes 19 are provided to reduce the thermal conductivity as much as possible when the low thermal expansion material 18 is provided in the heat radiator 16 itself. As shown in FIG. 5, the holes 19 are formed in the low thermal expansion material 18 in a region A corresponding to the insulating substrate 11 by reducing the number of holes 19 to be formed and in the peripheral region B of the corresponding region A. The number of holes 19 is increased.
[0049]
That is, the distribution of the cross-sectional area of the hole 19 is different between the region A corresponding to the insulating substrate 11 in the low thermal expansion material 18 and the peripheral region B other than the region A. This is for minimizing a decrease in rigidity of the heat radiator 16 against bending in the corresponding region A and a decrease in thermal conductivity of the entire heat radiator 16. Here, if the number of holes 19 formed in the low-thermal-expansion material 18 increases unnecessarily, the function as the low-thermal-expansion material is difficult to be achieved. The holes 19 are preferably formed in an area of about 20 to 50% based on the material of the body 17 and the low thermal expansion material 18. Although the hole 19 is formed as a round hole in the present embodiment, its shape is arbitrary. FIG. 4 corresponds to FIG. 3, and the cooling sink unit 31 is omitted.
[0050]
As described above, according to the power module substrate of the third embodiment, since the step portion 20 is provided in the low thermal expansion material 18, the thermal expansion coefficient difference between the radiator 16 side and the insulating substrate 11 side is obtained. Can be apparently reduced, and the warpage of the heat radiator 16 can be suppressed.
In addition to this, a hole 19 is provided in the low thermal expansion material 18, and the hole 19 is filled with the radiator body 17 and the low thermal expansion material 18 is cast by the radiator body 17. Heat can be satisfactorily transmitted from the radiator main body 17 on the side to the radiator main body 17 on the side of the cooling sink 31, whereby the radiator 16 inherently radiates heat.
[0051]
Moreover, as shown in FIG. 5, the holes 19 are formed in a region A corresponding to the insulating substrate 11 in a smaller number than the peripheral region B, and the sectional area of the holes 19 is smaller than that in the peripheral region B. Therefore, a decrease in rigidity of the radiator 16 against bending in the corresponding area A can be suppressed to a minimum, while the cross-sectional area of the hole 19 in the peripheral area B becomes larger than that of the corresponding area A, A reduction in the thermal conductivity of the entire radiator 16 can be minimized.
[0052]
In the present embodiment, a configuration is shown in which the heat radiator body 17 is cast into the hole 19 provided in the low thermal expansion material 18, but a flat plate or a powder material of the same material as the heat radiator body 17 is used in the hole 19. After filling by the thickness of the low thermal expansion material 18, the radiator body 17 may be laminated and joined to the upper and lower surfaces of the low thermal expansion material 18 via a brazing material.
[0053]
Next, a fourth embodiment of the present invention will be described. The same parts as those in the above-described first to third embodiments are denoted by the same reference numerals, and description thereof will be omitted.
In the power module substrate according to the fourth embodiment, as shown in FIGS. 6 and 7, the low thermal expansion material 18 provided on the heat radiator 16 has a rib (not shown).
The ribs are formed by forming cuts (18a, 18b) shown in FIG. 6 in a plate material formed in advance to a predetermined thickness when forming the holes 19 provided in the low thermal expansion material 18, and using the cuts. Is done. That is, by raising and lowering the cuts provided in advance in the vertical direction and bending the cuts, the rising pieces 18a and the falling pieces 18b are formed together, and the low thermal expansion material 18 having the ribs made of these pieces is formed. Is done.
The low thermal expansion material 18 is sandwiched between the radiator main bodies 17 and 17. At this time, the entire low thermal expansion material 18 having the rising pieces 18 a, the falling pieces 18 b, and the holes 19 is attached to the radiator main body 17. The radiator 16 is formed by being cast.
[0054]
As described above, according to the power module substrate according to the fourth embodiment, the radiator 16 includes the radiator body 17 and the low thermal expansion material 18 having the hole 19, and the radiator body 17 includes the hole 19. And the low thermal expansion material 18 is filled in, so that basically the same operational effects as in the third embodiment described above can be obtained.
In addition, since the low thermal expansion material 18 has the rib composed of the rising piece 18a and the falling piece 18b, the rigidity of the heat radiator 16 as a whole increases, and the strength can be increased. In addition, warpage of the insulating substrate 11 due to heat can be further suppressed.
[0055]
In the fourth embodiment, the example in which the low thermal expansion material 18 is provided by being laminated between the radiator main bodies 17 or provided by being sandwiched between the radiator main bodies 17 has been described. For example, after sintering a plate with holes 19 by powder metallurgy, a rib may be provided afterwards, or it may be formed by a die casting method, and furthermore, a high temperature treatment by hot forging may be performed. It can also be formed by the melt forging method performed. Alternatively, the heat radiator 16 can be configured as described below.
[0056]
Next, a fifth embodiment of the present invention will be described. Parts similar to those of the above-described first to fourth embodiments are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIGS. 8 and 9, the power module substrate according to the fifth embodiment includes a low-thermal-expansion material 18, one surface of which is joined to the radiator body 17 on the insulating substrate 11 side, and a cooling sink 31. The radiator body 17 is provided with an opening space 40 which communicates with the thickness direction across the other surface to be joined to the heat radiator body 17 on the side, and which is continuous with the thickness direction in a direction crossing the thickness direction. When the radiator body 17 is filled, the radiator body 17 is cast into the radiator body 17, as shown in FIG.
[0057]
More specifically, as shown in FIG. 9, the low thermal expansion material 18 continuously connects the connection openings 40 by assembling, for example, two strip-shaped unit plate-like bodies 41 and 42 along the thickness direction. Thus, a chain 43 is formed. A plurality of the chain members 43 are provided on the same plane, and the continuous openings 40 are alternately arranged in adjacent columns.
[0058]
When the material of the heat radiator main body 17 is injected into the heat radiator 16 during the formation of the heat radiator 16, the low thermal expansion material 18 thus formed is filled into the connection opening 40 from the side. When viewed from the side, the low-thermal-expansion material 18 has an upper radiator main body 17 on the insulating substrate 11 side and a lower radiator main body 17 on the cooling sink 31 side, as shown in FIG. It will be buried between.
[0059]
As described above, according to the power module substrate according to the fifth embodiment, since the low thermal expansion material 18 is cast in the radiator body 17 along the thickness direction, the thermal expansion coefficient of the entire radiator 16 is increased. The communication opening 40 allows the radiator body 17 to receive the heat from the insulating substrate 11 satisfactorily and to transmit the heat to the cooling sink 31. Therefore, the heat transfer is improved while suppressing the warpage of the heat radiator 16, and basically the same operation and effects as those of the above-described first to fourth embodiments can be obtained.
[0060]
In the above-described first to fifth embodiments, an example in which invar is used as the low thermal expansion material laminated on the heat radiator has been described. However, other low thermal expansion materials, for example, high carbon steel (Fe-C), The same function and effect can be obtained by using a 42 alloy, molybdenum (Mo), tungsten (W) or the like.
Further, the configuration in which the cooling sink portion 31 is provided on the surface of the heat radiator 16 has been described. However, the present invention is not limited to this, and a configuration in which corrugated fins are provided on the surface of the heat radiator 16 via a brazing material may be used. That is, a joining portion joined to the surface of the heat radiator 16 via a brazing material (not shown), a rising portion provided at one end of the joining portion and rising perpendicular to the joining portion, and a joining portion provided at the upper end of the rising portion. A protruding portion having a flat portion extending in a direction parallel to and separated from the flat portion and a folded portion provided at one end of the flat portion and orthogonal to the flat portion and turned toward the heat radiator 16 is formed along the surface direction of the heat radiator 16. It may be configured to be provided repeatedly and continuously. In this configuration, the rising portion, the flat portion, the folded portion, and the surface of the heat radiator 16 form a space.
Further, in place of the low thermal expansion material 18 shown in the above-described fifth embodiment, a so-called corrugate, a corrugated louver, an expanded structure having a communication opening 40 with a rectangular cross section expanded in the thickness direction, or shown in the fifth embodiment. A so-called honeycomb structure may be provided as a single layer, or one of the above-described structures may be stacked in a plurality.
[0061]
【The invention's effect】
As described above, according to the first aspect of the present invention, it is possible to reliably lower the thermal expansion coefficient of the entire radiator and to minimize the difference in the thermal expansion coefficient between the insulating substrate and the entire radiator. it can. For this reason, when the insulating substrate and the radiator are joined by solder or the like, it is possible to reliably suppress the radiator from warping toward the insulating substrate.
[0062]
According to the second aspect of the present invention, the thermal expansion coefficient of the entire radiator can be reliably reduced, and a decrease in the thermal conductivity of the entire radiator can be minimized. In this way, when the insulating substrate and the heat radiator are joined by solder or the like, the heat radiator is prevented from warping toward the insulating substrate, and the power provided with the heat radiator having the minimum necessary thermal conductivity. A module substrate can be provided.
[0063]
According to the third aspect of the present invention, the influence of the low thermal expansion material that contributes to the thermal expansion coefficient of the entire radiator is kept to a necessary minimum, and the thermal expansion coefficient of the entire radiator is reliably reduced. The difference in the coefficient of thermal expansion between the radiator and the entire radiator can be made as small as possible. For this reason, when the insulating substrate and the radiator are joined by solder or the like, it is possible to reliably suppress the radiator from warping toward the insulating substrate.
[0064]
According to the invention according to claim 4, a difference in thermal expansion coefficient between the insulating substrate and the radiator in a region corresponding to the insulating substrate can be reliably reduced. Accordingly, when the insulating substrate and the heat radiator are joined by solder or the like, it is possible to reliably suppress the occurrence of warpage of the heat radiator toward the insulating substrate.
[0065]
According to the fifth aspect of the present invention, it is possible to adjust the effect of the low thermal expansion material on the thermal expansion coefficient in a region corresponding to the insulating substrate of the heat radiator, so that the thermal expansion coefficient of the heat radiator can be apparently adjusted. It has become. This makes it possible to reduce the difference in the coefficient of thermal expansion between the insulating substrate and the radiator in a region corresponding to the insulating substrate. When the insulating substrate and the radiator are joined by solder or the like, the insulating substrate is attached to the radiator. The occurrence of the warp toward the direction can be surely suppressed.
[0066]
According to the invention according to claim 6, the radiator body is provided on each of the upper and lower surfaces of the low thermal expansion material, the radiator body is filled into the holes provided in the low thermal expansion material, and the low thermal expansion material is cast with the radiator body. The heat radiator main bodies disposed on the upper and lower surfaces of the heat radiator can be directly in contact with each other via the holes. Therefore, the heat from the insulating substrate can be reliably transmitted in the stacking direction of the radiator, and the heat can be efficiently radiated to the outside. As described above, a reduction in the thermal expansion coefficient of the radiator and a suppression of a reduction in the thermal conductivity can be reliably realized.
[0067]
According to the invention according to claim 7, since the low-thermal-expansion material has the ribs, the rigidity of the radiator as a whole can be increased and the strength can be increased. It can be suppressed reliably.
[0068]
According to the invention of claim 8, in the low thermal expansion material, the cross-sectional area of the hole provided in the region corresponding to the insulating substrate is smaller than the cross-sectional area of the hole provided in the peripheral region of the corresponding region. Therefore, it is possible to minimize a decrease in rigidity of the radiator against bending in the corresponding region. Accordingly, it is possible to suppress the occurrence of warpage due to the thermal deformation of the corresponding region due to the influence of heat from the insulating substrate, while the cross-sectional area of the hole provided in the peripheral region is larger than that of the corresponding region. Accordingly, a decrease in the thermal conductivity of the radiator can be suppressed to a minimum.
[0069]
According to the ninth aspect of the present invention, the thermal expansion coefficient of the entire radiator can be reliably reduced, and a decrease in thermal conductivity can be reliably suppressed. Therefore, when the insulating substrate and the radiator are joined by solder or the like, it is possible to reliably suppress the occurrence of warpage of the radiator toward the insulating substrate, and to reduce the thermal conductivity of the radiator itself. Can be suppressed.
[0070]
According to the invention according to claim 10, the belt-like unit plate-like bodies are assembled to each other at the same row position to form a chain-like body having continuous communication openings, and the chain-like body is arranged in a plurality of rows on the same plane. In addition to the provision of the connection openings, the connection openings are shifted from each other in adjacent rows, so that a low-thermal-expansion material having connection openings continuous with each other in the thickness direction across one surface and the other surface is reliably formed. it can.
[0071]
According to the eleventh aspect, it is possible to obtain a power module having good thermal conductivity while suppressing warpage of the insulating substrate and the radiator as much as possible, irrespective of the difference in thermal expansion coefficient.
[Brief description of the drawings]
FIG. 1 is an overall view showing a power module to which a power module substrate according to a first embodiment of the present invention is applied.
FIG. 2 is an overall view showing a power module to which a power module substrate according to a second embodiment of the present invention is applied, showing a case where a thermal expansion coefficient on an insulating substrate side is larger than a thermal expansion coefficient on a radiator side. It is.
FIG. 3 is an overall view showing a power module to which a power module substrate according to a second embodiment of the present invention is applied, showing a case where a thermal expansion coefficient on a radiator side is larger than a thermal expansion coefficient on an insulating substrate side. It is.
FIG. 4 is an overall view showing a power module to which a power module substrate according to a third embodiment of the present invention is applied.
FIG. 5 is a plan view of the low thermal expansion material shown in FIG.
FIG. 6 is an overall view showing a power module to which a power module substrate according to a fourth embodiment of the present invention is applied.
FIG. 7 is a plan view of the low thermal expansion material shown in FIG.
FIG. 8 is a cross-sectional side view of a radiator constituting a power module substrate according to a fifth embodiment of the present invention.
FIG. 9 is a perspective view showing a main part of the low thermal expansion material shown in FIG.
[Explanation of symbols]
P power module
10. Power module substrate
11 Insulating substrate
16 Heat radiator
17 Heatsink body (high thermal conductive material)
18 Low thermal expansion material
18a Starting piece (rib)
18b Falling piece (rib)
19 holes
20 steps
30 Semiconductor chip (chip)
40 communication opening
41, 42 plate
43 Chain
α1 Thermal expansion coefficient of insulating substrate
α2 Thermal expansion coefficient on the radiator side
A Thickness of low thermal expansion material in the laminating direction
B Thickness in the stacking direction of the radiator body (high thermal conductive material)

Claims (11)

絶縁基板と、該絶縁基板の一方の面に設けられた放熱体と、前記絶縁基板の他方の面に設けられた回路層とを備えたパワーモジュール用基板であって、
前記放熱体は、放熱体本体に該放熱体本体の熱膨張係数より低い材質からなる低熱膨張材を積層して構成されていることを特徴とするパワーモジュール用基板。An insulating substrate, a power module substrate including a radiator provided on one surface of the insulating substrate, and a circuit layer provided on the other surface of the insulating substrate,
A power module substrate, wherein the radiator is formed by laminating a low thermal expansion material made of a material having a lower thermal expansion coefficient on the radiator body. 請求項１記載のパワーモジュール用基板において、
前記低熱膨張材の厚さは、前記放熱体本体の厚さの０．１倍以下で形成されていることを特徴とするパワーモジュール用基板。The power module substrate according to claim 1,
The substrate for a power module, wherein the thickness of the low thermal expansion material is formed to be 0.1 times or less the thickness of the radiator body. 請求項１又は２に記載のパワーモジュール用基板において、
前記低熱膨張材の厚さは、前記放熱体本体の厚さの０．０５倍以上で形成されていることを特徴とするパワーモジュール用基板。The power module substrate according to claim 1 or 2,
The substrate for a power module, wherein the thickness of the low thermal expansion material is at least 0.05 times the thickness of the radiator body. 請求項１から３のいずれかに記載のパワーモジュール用基板において、
前記低熱膨張材の絶縁基板と対応する領域に、放熱体側の熱膨張係数と絶縁基板側の熱膨張係数との差に基づき、段差部が設けられていることを特徴とするパワーモジュール用基板。The power module substrate according to any one of claims 1 to 3,
A power module substrate, wherein a stepped portion is provided in a region corresponding to the insulating substrate of the low thermal expansion material, based on a difference between a thermal expansion coefficient on a radiator side and a thermal expansion coefficient on an insulating substrate side. 請求項１から４のいずれかに記載のパワーモジュール用基板において、
前記段差部は、放熱体において、絶縁基板側の熱膨張係数が放熱体側の熱膨張係数より小さいとき、低熱膨張材の前記絶縁基板と対応する領域を、絶縁基板から遠ざかる方向に凹ませて形成する一方、
絶縁基板側の熱膨張係数より放熱体側の熱膨張係数が小さいとき、低熱膨張材の前記絶縁基板と対応する領域を、絶縁基板に近づく方向に隆起させて形成することを特徴とするパワーモジュール用基板。The power module substrate according to any one of claims 1 to 4,
When the thermal expansion coefficient on the insulating substrate side is smaller than the thermal expansion coefficient on the radiator side, the step portion is formed by denting a region of the low thermal expansion material corresponding to the insulating substrate in a direction away from the insulating substrate. While
When the thermal expansion coefficient on the radiator side is smaller than the thermal expansion coefficient on the insulating substrate side, a region corresponding to the insulating substrate of the low thermal expansion material is formed by being raised in a direction approaching the insulating substrate. substrate. 請求項１から５のいずれかに記載のパワーモジュール用基板において、
前記低熱膨張材には、これを貫通する孔が穿設されていることを特徴とするパワーモジュール用基板。The power module substrate according to any one of claims 1 to 5,
A power module substrate, wherein the low thermal expansion material has a hole penetrating therethrough. 請求項１から６のいずれかに記載のパワーモジュール用基板において、
前記低熱膨張材は、リブを有していることを特徴とするパワーモジュール用基板。The power module substrate according to any one of claims 1 to 6,
The power module substrate, wherein the low thermal expansion material has a rib. 請求項６又は７に記載のパワーモジュール用基板において、
前記孔は、前記低熱膨張材において、絶縁基板と対応する領域に設けられた断面積より、該対応領域の周辺領域に設けられた断面積を大きくさせていることを特徴とするパワーモジュール用基板。The power module substrate according to claim 6, wherein
The power module substrate, wherein the hole has a cross-sectional area provided in a peripheral region of the corresponding region larger than a cross-sectional area provided in a region corresponding to the insulating substrate in the low thermal expansion material. . 絶縁基板と、該絶縁基板の一方の面に設けられた放熱体と、前記絶縁基板の他方の面に設けられた回路層とを備えたパワーモジュール用基板であって、
前記放熱体は、放熱体本体と、該放熱体本体の熱膨張係数より低い材質からなる低熱膨張材とを備え、
該低熱膨張材は、前記一方の面と他方の面とに亘る厚み方向と連絡し、かつ該厚み方向と交差方向で互いに連なる連絡開口部を有して設けられ、かつ該連絡開口部を介して放熱体本体に鋳ぐまれる構成としたことを特徴とするパワーモジュール用基板。An insulating substrate, a power module substrate including a radiator provided on one surface of the insulating substrate, and a circuit layer provided on the other surface of the insulating substrate,
The radiator includes a radiator main body and a low thermal expansion material made of a material having a lower thermal expansion coefficient than the radiator main body,
The low thermal expansion material is provided with a communication opening communicating with the thickness direction across the one surface and the other surface, and communicating with each other in a direction crossing the thickness direction, and via the communication opening. A power module substrate characterized in that it is configured to be cast into a radiator body. 請求項９記載のパワーモジュール用基板において、
前記低熱膨張材は、帯状の単位板状体を同列位置で互いに組付けて前記連絡開口部を連続的に有する連鎖状体に形成し、該連鎖状体を同一平面上で複数列設けると共に、互いに隣接する列毎に前記連絡開口部の位置をずらして配設することを特徴とするパワーモジュール用基板。The power module substrate according to claim 9,
The low-thermal-expansion material is formed into a chain-like body having the communication openings continuously by assembling the band-like unit plate-like bodies at the same row position, and providing the chain-like body in a plurality of rows on the same plane, A power module substrate, wherein the positions of the communication openings are shifted from each other in adjacent rows. 請求項１から１０記載のパワーモジュール用基板上にチップを搭載してなることを特徴とするパワーモジュール。A power module comprising a chip mounted on the power module substrate according to claim 1.
JP2002312594A 2002-10-28 2002-10-28 Power module substrate and power module Expired - Lifetime JP3912255B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002312594A JP3912255B2 (en) 2002-10-28 2002-10-28 Power module substrate and power module

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002312594A JP3912255B2 (en) 2002-10-28 2002-10-28 Power module substrate and power module

Publications (2)

Publication Number Publication Date
JP2004146737A true JP2004146737A (en) 2004-05-20
JP3912255B2 JP3912255B2 (en) 2007-05-09

Family

ID=32457447

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002312594A Expired - Lifetime JP3912255B2 (en) 2002-10-28 2002-10-28 Power module substrate and power module

Country Status (1)

Country Link
JP (1) JP3912255B2 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006216659A (en) * 2005-02-02 2006-08-17 Mitsubishi Materials Corp Insulating circuit substrate and power module
JP2006245099A (en) * 2005-03-01 2006-09-14 Mitsubishi Materials Corp Insulating circuit board and power module
JP2009164413A (en) * 2008-01-08 2009-07-23 Mitsubishi Materials Corp Power module substrate and power module
CN105874592A (en) * 2014-06-19 2016-08-17 富士电机株式会社 Cooler and cooler fixing method
WO2023112224A1 (en) * 2021-12-15 2023-06-22 日立Astemo株式会社 Semiconductor device and insulating member

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006216659A (en) * 2005-02-02 2006-08-17 Mitsubishi Materials Corp Insulating circuit substrate and power module
JP2006245099A (en) * 2005-03-01 2006-09-14 Mitsubishi Materials Corp Insulating circuit board and power module
JP2009164413A (en) * 2008-01-08 2009-07-23 Mitsubishi Materials Corp Power module substrate and power module
CN105874592A (en) * 2014-06-19 2016-08-17 富士电机株式会社 Cooler and cooler fixing method
WO2023112224A1 (en) * 2021-12-15 2023-06-22 日立Astemo株式会社 Semiconductor device and insulating member

Also Published As

Publication number Publication date
JP3912255B2 (en) 2007-05-09

Similar Documents

Publication Publication Date Title
EP2306512B1 (en) Heat radiator and power module
JP4558012B2 (en) Semiconductor package heat dissipation plate and semiconductor device
KR100993499B1 (en) Semiconductor module
US20080290499A1 (en) Semiconductor device
JP2009043851A (en) Semiconductor package
JP2008135511A (en) Power module substrate and power module
JP2004153075A (en) Substrate for power module and power module
JP2004022973A (en) Ceramic circuit board and semiconductor module
JP6183166B2 (en) Power module substrate with heat sink and manufacturing method thereof
JP3912255B2 (en) Power module substrate and power module
JP4605009B2 (en) Power module manufacturing method
JP3975910B2 (en) Radiator
JP3960192B2 (en) Radiator
JP3938079B2 (en) Power module substrate manufacturing method
JP3933031B2 (en) Radiator
JP2010238965A (en) Substrate for power module, method for manufacturing substrate for power module, and power module
JP2005328087A (en) Power module substrate
JP2004152969A (en) Power module substrate and power module
JP2004207619A (en) Power module and substrate therefor
JP3901109B2 (en) Manufacturing method of heat radiator, heat radiator, power module substrate and power module using the heat radiator
JP6139331B2 (en) Power module
JP4179055B2 (en) Power module substrate, radiator and method of manufacturing the radiator
JP2004296493A (en) Heat sink, method of manufacturing the same, power module, and method of manufacturing the same
JP3873870B2 (en) Radiator
JP3901078B2 (en) Power module substrate and power module

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20050318

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20060929

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20061010

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20061208

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20070109

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20070122

R150 Certificate of patent or registration of utility model

Ref document number: 3912255

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100209

Year of fee payment: 3

S531 Written request for registration of change of domicile

Free format text: JAPANESE INTERMEDIATE CODE: R313531

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100209

Year of fee payment: 3

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100209

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110209

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120209

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120209

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130209

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140209

Year of fee payment: 7

EXPY Cancellation because of completion of term