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JP3934966B2 - Ceramic circuit board - Google Patents

Ceramic circuit board Download PDF

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Publication number
JP3934966B2
JP3934966B2 JP2002081863A JP2002081863A JP3934966B2 JP 3934966 B2 JP3934966 B2 JP 3934966B2 JP 2002081863 A JP2002081863 A JP 2002081863A JP 2002081863 A JP2002081863 A JP 2002081863A JP 3934966 B2 JP3934966 B2 JP 3934966B2
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Prior art keywords
circuit board
metal
ceramic
metal plate
heat
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JP2003283063A (en
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貴幸 宮尾
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Kyocera Corp
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Kyocera Corp
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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
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48225—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
    • H01L2224/48227—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 connecting the wire to a bond pad of the item
    • 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]
    • 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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Description

【０００１】
【発明の属する技術分野】
本発明は、セラミック基板に金属回路板を接合したセラミック回路基板に関するものである。
【０００２】
【従来の技術】
近年、パワーモジュール用基板やスイッチングモジュール用基板等の回路基板として、セラミック基板上に活性金属ロウ材を介して銅等から成る金属回路板を直接接合させたセラミック回路基板が用いられている。
【０００３】
図３に従来のセラミック回路基板を用いた半導体モジュールの例を断面図で示す。図３において、11はセラミック回路基板を示し、このセラミック回路基板11は、セラミック基板12と、その上面に取着された複数の金属回路板13と、セラミック基板12の下面にこれら金属回路板13と対向させて取着された金属板14とから構成されている。そして、このようなセラミック回路基板11は、金属回路板13上に半導体素子17等の電子部品が搭載され、放熱部材16上に金属板14との間に伝熱性組成物15を介在させて接合実装されることにより、半導体モジュールとして使用される。
【０００４】
かかるセラミック回路基板11は、酸化アルミニウム質焼結体から成るセラミック基板12を用いる場合には、具体的には以下の方法によって製作される。
【０００５】
まず、酸化アルミニウム・酸化珪素・酸化マグネシウム・酸化カルシウム等の原料粉末に適当な有機バインダ・可塑剤・溶剤等を添加混合して泥漿状と成すとともに、これを従来周知のドクターブレード法やカレンダーロール法等のテープ成形技術を採用して複数のセラミックグリーンシートを得た後、所定寸法に成形し、次に、セラミックグリーンシートを必要に応じて上下に積層するとともに還元雰囲気中にて約1600℃の温度で焼成し、セラミックグリーンシートを焼結一体化させて酸化アルミニウム質焼結体から成るセラミック基板12を作製する。
【０００６】
次に、銀−銅合金にチタン・ジルコニウム・ハフニウムおよびこれらの水素化物の少なくとも１種を添加した活性金属粉末に有機溶剤・溶媒を添加混合してロウ材ペーストを調製し、セラミック基板12の両主面上に塗布する。
【０００７】
次に、セラミック基板12上面にロウ材ペーストを間に挟んで銅等から成る複数の金属回路板13を載置し、一方、これに対向するセラミック基板12の下面には同様にロウ材ペーストを間に挟んで銅等から成る金属板14を配置する。
【０００８】
そして最後に、セラミック基板12と金属回路板13との間およびセラミック基板12と金属板14との間に配されているロウ材ペーストを非酸化性雰囲気中にて約900℃の温度に加熱して溶融させ、このロウ材でセラミック基板12と金属回路板13とを、およびセラミック基板12と金属板14とを接合することによって製作される。
【０００９】
このように製作されたセラミック回路基板11は、ＩＧＢＴ（Insulated Gate Bipolar Transistor）やＭＯＳ−ＦＥＴ（Metal Oxide Semiconductor - Field Effect Transistor）等の半導体素子17等の電子部品を半田等の接着剤を介して接合した後、例えば、アルミニウム等の放熱部材16に半田で接合されることにより、半導体素子17の動作時の発熱を良好に放熱させる半導体モジュールとなる。
【００１０】
しかしながら、セラミック回路基板11（熱膨張係数が約３〜10×10-6／℃）と放熱部材16（熱膨張係数が約18〜23×10-6／℃）の熱膨張係数が大きく相違することから、セラミック回路基板11と放熱部材16との間の半田にクラックが発生し、剥離が生じて信頼性が著しく劣化する場合がある。このため、半田に変えてグリース状の伝熱性組成物15を介してセラミック回路基板11と放熱部材16とを接合実装する構成が採用されている。
【００１１】
【発明が解決しようとする課題】
しかしながら、グリース状の伝熱性組成物15は低熱伝導のため、セラミック回路基板11と放熱部材16との間の伝熱性組成物15が厚くなると、半導体素子17からの放熱経路が遮断されて良好な熱放散を行なえなくなってしまい、半導体素子17に熱破壊や特性の劣化を招来して半導体素子17を安定に信頼性よく作動させることができなくなるという問題点を有していた。
【００１２】
また、セラミック基板12自体に若干のうねりが生じていること、また、セラミック基板12のサイズや金属回路板13の回路パターンおよびセラミック基板12の厚みにより、最適な金属回路板13や金属板14の厚みを設計する必要があるが、セラミック回路基板11の裏面を完全に平坦にすることは非常に困難である。従って、伝熱性組成物15を介してセラミック回路基板11を放熱部材16に接合する際、セラミック回路基板11を押さえつけても、半導体素子17の温度上昇に影響のある半導体素子17の下方の伝熱性組成物15は、伝熱性組成物15自体の粘性、さらにはセラミック基板12のうねりが障害になるため、十分に金属板14より外に流れ出ない傾向があり、その結果、半導体素子17の下方の伝熱性組成物15の厚みを薄くするのが困難であるという問題点もあった。
【００１３】
本発明は以上のような従来の技術における問題点を解決すべく案出されたものであり、その目的は、熱伝導率が相対的に低い伝熱性組成物を薄くして熱抵抗の増加を防ぐことができ、放熱特性が良好であり、金属回路板上に搭載される半導体素子等の電子部品を長期にわたり安定して作動させることができるセラミック回路基板を提供することにある。
【００１４】
【課題を解決するための手段】
本発明は、金属板と、該金属板上に搭載されたセラミック基板と、該セラミック基板上に搭載されるとともに、上面に電子部品の搭載領域を有する金属回路板とを備え、前記金属板の下面に伝熱性組成物が入り込むための溝が形成されたセラミック回路基板において、前記電子部品の搭載領域における前記金属板の下面から前記金属回路板の上面までの厚みがＨであるときに、前記電子部品の搭載領域の外辺から平面視で距離Ｈだけ離間した位置に、前記溝の電子部品側の端部が位置することを特徴とする。
【００１５】
また本発明は、下面に伝熱性組成物が入り込むための溝が形成された金属板と、該金属板上に搭載されたセラミック基板と、該セラミック基板上に搭載された金属回路板と、該金属回路板上に搭載された電子部品と、前記金属板の下面に前記伝熱性組成物を介して接合される放熱部材とを備えたモジュールであって、前記電子部品の搭載領域における前記金属板の下面から前記金属回路板の上面までの厚みがＨであるときに、前記電子部品の外辺から平面視で距離Ｈだけ離間した位置に、前記溝の電子部品側の端部が位置することを特徴とする。
【００１６】
本発明のセラミック回路基板によれば、上記構成により半導体素子７で発生した熱は、放熱部材６側へ伝導する際に約 45 °の角度で広がるのに対し、その熱伝導経路に溝８により金属板４の厚みが薄くなっている部分がないので、また伝熱性組成物５が侵入して存在している溝８がないので、金属板４における熱伝導が阻害されることはない。
【００１８】
このような構成により、本発明のセラミック回路基板によれば、放熱特性が良好であり、金属回路板上に搭載される半導体素子等の電子部品を長期にわたり安定して作動させることができるものとなる。
【００１９】
【発明の実施の形態】
次に、本発明のセラミック回路基板の実施の形態の例を添付図面に基づき詳細に説明する。
【００２０】
図１は、本発明のセラミック回路基板１を用いた半導体モジュールの一例を示す断面図であり、２はセラミック基板、３は金属回路板、４は金属板、５は伝熱性組成物、６は放熱部材、７は電子部品としての半導体素子、８は溝である。また、図２は本発明のセラミック回路基板１を金属板４側から見た場合の金属板４の平面図である。
【００２１】
セラミック基板２は、金属回路板３および金属板４を支持する支持部材として機能し、酸化アルミニウム（Ａｌ2Ｏ3）質焼結体・ムライト（３Ａｌ2Ｏ3・２ＳｉＯ2）質焼結体・炭化珪素（ＳｉＣ）質焼結体・窒化アルミニウム（ＡｌＮ）質焼結体・窒化珪素（Ｓｉ3Ｎ4）質焼結体等のセラミック材料で形成されている。
【００２２】
セラミック基板２は、機械的強度が強く、高靭性な窒化珪素質焼結体で形成されていることが好ましい。また、金属回路板３上に搭載される半導体素子７が発生する熱を金属回路板３から金属板４へと有効に伝導して放散させ、セラミック回路基板１の放熱特性を向上させるためには、セラミック基板２の熱伝導率が少なくとも60Ｗ／ｍ・Ｋ以上であることが好ましく、特に80Ｗ／ｍ・Ｋ以上、さらには100Ｗ／ｍ・Ｋ以上であることが好ましい。
【００２３】
セラミック基板２は、例えば窒化珪素質焼結体で形成されている場合であれば、まず、窒化珪素粉末に希土類酸化物粉末や酸化アルミニウム粉末等の焼結助剤を添加・混合して窒化珪素質焼結体原料粉末を調整する。次いで、窒化珪素質焼結体原料粉末に有機バインダおよび分散媒を添加・混合してペースト化し、このペーストをドクターブレード法等の通常の成形法でシート状に成形して窒化珪素質グリーンシートを作製する。このような窒化珪素質グリーンシートを必要枚数積層し、プレス加工等を施して圧着（加圧接着）して窒化珪素質成形体を作製する。この後、窒化珪素質成形体を空気中もしくは窒素雰囲気等の非酸化性雰囲気中で脱脂処理した後、窒素雰囲気等の非酸化性雰囲気中で焼成して、目的とするセラミック基板２を得る。
【００２４】
また、セラミック基板２は、セラミック回路基板１の機械的強度を向上させつつ放熱特性を劣化させないためには、その厚みを0.2〜1.0ｍｍとすることが好ましい。0.2ｍｍ未満では、セラミック基板２と金属回路板３および金属板４とを接合したときに発生する応力により、セラミック基板２に割れ等が発生しやすくなる傾向がある。他方、1.0ｍｍを超えると、半導体素子７から発生する熱を良好に放熱部材６に伝達することが困難となる傾向がある。
【００２５】
本発明のセラミック回路基板１は、上記のように製造したセラミック基板２の上面および下面に、直接接合法や活性金属法を用いて導電性を有する銅やアルミニウム等の金属材料から成る金属回路板３および金属板４をそれぞれ一体的に接合して製造される。
【００２６】
例えば、活性金属法を用いる場合であれば、銀−銅合金粉末等から成る銀ロウ粉末や、アルミニウム−シリコン合金粉末等から成るアルミニウムロウ粉末に、チタン・ジルコニウム・ハフニウム等の活性金属やその水素化物の少なくとも１種からなる活性金属粉末を２〜５重量％添加した活性金属ロウ材に、適当な有機溶剤・溶媒を添加混合して得た活性金属ロウ材ペーストを、セラミック基板２の上下面に従来周知のスクリーン印刷技術を用いて金属回路板３および金属板４に対応させた所定パターンに印刷する。
【００２７】
その後、金属回路板３および金属板４を活性金属ロウ材ペーストのパターン上に載置し、これを真空中または中性もしくは還元雰囲気中で、所定温度（銀ロウの場合であれば約900℃、アルミニウムロウ材の場合であれば約600℃）で加熱処理し、活性金属ロウ材を溶融させて、セラミック基板２の上下面と金属回路板３および金属板４とを接合させる。これにより、セラミック基板２の上下面に金属回路板３および金属板４が取着されることとなる。
【００２８】
銅やアルミニウム等から成る金属回路板３および金属板４は、銅やアルミニウム等のインゴット（塊）に圧延加工法や抜き打ち加工法等の従来周知の金属加工法を施すことによって、例えば、標準の厚さが0.5ｍｍで、回路パターンの形状または回路パターンおよびその回路間の形状に対応する所定のパターン形状に製作される。金属回路板３および金属板４の標準の厚さは、大電流による金属回路板３の発熱を抑制し、金属回路板３と窒化珪素質焼結体等から成るセラミック基板２の接合時に接合界面に発生する熱負荷によるクラックの発生を抑制するためには、0.1〜1.0ｍｍであることが好ましい。厚みが0.1ｍｍ未満では、金属回路板３の電気抵抗が大きくなるため半導体素子７からの高電流信号を伝播しにくくなる傾向がある。他方、1.0ｍｍを超えると、セラミック基板２と金属回路板３および金属板４とを接合したときに発生する応力により、セラミック基板２に割れ等が発生しやすくなる傾向がある。
【００２９】
金属回路板３および金属板４は、銅から成る場合であれは、これを無酸素銅で形成しておくと、無酸素銅はロウ付けの際に銅の表面が銅中に存在する酸素により酸化されることなくロウ材との濡れ性が良好となるので、セラミック基板２とのロウ材を介しての接合が強固になる。したがって、金属回路板３および金属板４は、これを無酸素銅で形成しておくことが好ましい。
【００３０】
金属回路板３および金属板４の標準の厚みと材質は、活性金属によるロウ付け時や半導体素子７等の電子部品を搭載するためのリフロー時の加熱による反りを抑制するために、同じ材質の場合には、金属板４の厚みは金属回路板３の厚みより薄くすることが好ましい。
【００３１】
また、金属回路板３は、その表面にニッケルから成る良導電性で、かつ耐蝕性およびロウ材との濡れ性が良好な金属をメッキ法により被着させておくと、金属回路板３と外部電気回路との電気的接続を良好とすることができるとともに、金属回路板３に半導体素子７等の電子部品を半田を介して強固に接着させることができる。従って、金属回路板３は、その表面にニッケルから成る良導電性で、かつ耐蝕性およびロウ材との濡れ性が良好な金属をメッキ法により被着させておくことが好ましい。
【００３２】
金属板４は、放熱部材６に実装される面に、半導体素子７の外周からセラミック回路基板１の全厚みの距離（図１および図２にＨで示す）の部位に溝８（図２では白抜き部で示す）が形成されている。このように溝８を形成したことにより、セラミック回路基板１を放熱部材６に伝熱性組成物５を介して接合する際に、金属板４の溝８にその周りから伝熱性組成物５が侵入するため、半導体素子７の直下およびその周囲に介在する、熱伝導率が相対的に低い伝熱性組成物７の厚みを薄くして接合することが可能となる。そのため、熱抵抗の増加を防ぐことができ、放熱性を改善したセラミック回路基板１を提供することができる。
【００３３】
半導体素子７で発生した熱は、放熱部材６側へ伝導する際に約45°の角度で広がるのに対し、その熱伝導経路に溝８により金属板４の厚みが薄くなっている部分がないので、また伝熱性組成物５が侵入して存在している溝８がないので、金属板４における熱伝導が阻害されることはない。
【００３４】
溝８の半導体素子７側の端部が、半導体素子７の搭載領域の外辺から平面視で距離Ｈだけ離間した位置より半導体素子７の搭載領域に近い側にあると、伝熱性組成物５が存在する溝８の影響を受けて金属板４における熱拡散が阻害されることとなるため、熱抵抗が増加する傾向にある。また、溝８の半導体素子７側の端部が、半導体素子７の搭載領域の外辺から平面視で距離Ｈだけ離間した位置より半導体素子７の搭載領域に遠い側にあると、セラミック回路基板１を放熱部材６に伝熱性組成物５を介して接合する際に、半導体素子７の直下およびその周囲にある伝熱性組成物５が外側に向かって広がって溝８と放熱部材６との隙間に侵入するのが困難になり、半導体素子７の直下およびその周囲の金属板４と放熱部材６との間に介在する伝熱性組成物７の厚みを充分に薄くすることができなくなる。
【００３８】
上記のようにして作製された本発明のセラミック回路基板１は、金属板４上にグリース状の伝熱性組成物５を塗布した後、アルミニウム等から成る放熱部材６に接合されて半導体素子モジュールとなる。このとき、伝熱性組成物５は溝８を避けて金属板４上に、その塗布厚みを調整して均一に塗布しておくと、半導体素子７の直下およびその周囲にある伝熱性組成物５が溝８に効率よく侵入するため、半導体素子７の直下およびその周囲に介在する、熱伝導率が相対的に低い伝熱性組成物７の厚みを薄くして接合することが可能となる。
【００４９】
なお、本発明は上述の実施の形態の例に限定されるものではなく、本発明の趣旨を逸脱しない範囲であれば種々の変更は可能である。
【００５０】
例えば、上述の例ではセラミック基板２が窒化珪素質焼結体で形成された例を示したが、半導体素子７が多量の熱を発し、この熱を効率良く放熱したい場合には、セラミック基板２を熱伝達率の高い窒化アルミニウム質焼結体や窒化珪素質焼結体で形成すればよい。また、上述の例ではセラミック基板２に活性金属ロウ材を介して直接に金属回路板３および金属板４をロウ付けしたが、これをセラミック基板２の表面に予めタングステンまたはモリブデン等のメタライズ金属層を被着させておき、このメタライズ金属層に金属回路板３および金属板４をロウ材を介して接合させてもよい。また、セラミック基板２に活性金属ロウ材を介してあらかじめ回路配線のパターン形状に形成された金属回路板３をロウ付けすることにより、回路配線のパターン形成を行なってもよい。
【００５１】
【発明の効果】
本発明のセラミック回路基板によれば、半導体素子７で発生した熱は、放熱部材６側へ伝導する際に約45°の角度で広がるのに対し、その熱伝導経路に溝８により金属板４の厚みが薄くなっている部分がないので、また伝熱性組成物５が侵入して存在している溝８がないので、金属板４における熱伝導が阻害されることはない。
【００５３】
このような構成により、本発明のセラミック回路基板によれば、放熱特性が良好であり、金属回路板上に搭載される半導体素子等の電子部品を長期にわたり安定して作動させることができるものとなる。
【００５４】
【図面の簡単な説明】
【図１】本発明のセラミック回路基板を用いた半導体モジュールの一例を示す断面図である。
【図２】図１に示すセラミック回路基板１を金属板４側から見た場合の金属板４の平面図である。
【図３】従来のセラミック回路基板を用いた半導体モジュールの一例を示す断面図である。
【符号の説明】
１：セラミック回路基板
２：セラミック基板
３：金属回路板
４：金属板
５：伝熱性組成物
６：放熱部材
７：半導体素子
８：溝
Ｔ：溝の深さ
Ｓ：溝の幅
Ｌ：半導体素子の外辺の長さ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ceramic circuit board in which a metal circuit board is bonded to a ceramic board.
[0002]
[Prior art]
In recent years, a ceramic circuit board in which a metal circuit board made of copper or the like is directly bonded to a ceramic board via an active metal brazing material is used as a circuit board such as a power module board or a switching module board.
[0003]
FIG. 3 is a sectional view showing an example of a conventional semiconductor module using a ceramic circuit board. In FIG. 3, reference numeral 11 denotes a ceramic circuit board. The ceramic circuit board 11 includes a ceramic board 12, a plurality of metal circuit boards 13 attached to the upper surface of the ceramic board 12, and the metal circuit boards 13 on the lower surface of the ceramic board 12. And a metal plate 14 attached to face each other. Such a ceramic circuit board 11 has electronic components such as a semiconductor element 17 mounted on the metal circuit board 13, and is joined to the heat radiating member 16 with the heat conductive composition 15 interposed between the metal board 14. By being mounted, it is used as a semiconductor module.
[0004]
The ceramic circuit board 11 is specifically manufactured by the following method when the ceramic substrate 12 made of an aluminum oxide sintered body is used.
[0005]
First, an appropriate organic binder, plasticizer, solvent, etc. are added to the raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide to form a slurry, and this is made into a conventionally known doctor blade method or calendar roll. After obtaining a plurality of ceramic green sheets by adopting a tape forming technique such as the method, the ceramic green sheets are molded to a predetermined size, and then stacked as needed up and down at about 1600 ° C in a reducing atmosphere The ceramic substrate 12 made of an aluminum oxide sintered body is manufactured by sintering at a temperature of 1 mm and sintering and integrating the ceramic green sheets.
[0006]
Next, a brazing paste is prepared by adding an organic solvent / solvent to an active metal powder in which at least one of titanium, zirconium, hafnium and hydrides thereof is added to a silver-copper alloy. Apply on the main surface.
[0007]
Next, a plurality of metal circuit boards 13 made of copper or the like are placed on the upper surface of the ceramic substrate 12 with the brazing material paste interposed therebetween, while the brazing material paste is similarly applied to the lower surface of the ceramic substrate 12 facing this. A metal plate 14 made of copper or the like is disposed between them.
[0008]
Finally, the brazing paste disposed between the ceramic substrate 12 and the metal circuit board 13 and between the ceramic substrate 12 and the metal plate 14 is heated to a temperature of about 900 ° C. in a non-oxidizing atmosphere. The ceramic substrate 12 and the metal circuit board 13 and the ceramic substrate 12 and the metal plate 14 are joined together with the brazing material.
[0009]
The ceramic circuit board 11 manufactured in this way is used to attach electronic components such as semiconductor elements 17 such as IGBTs (Insulated Gate Bipolar Transistors) and MOS-FETs (Metal Oxide Semiconductors-Field Effect Transistors) via an adhesive such as solder. After joining, for example, by joining to a heat radiating member 16 such as aluminum by soldering, a semiconductor module that radiates heat generated during operation of the semiconductor element 17 is obtained.
[0010]
However, the thermal expansion coefficients of the ceramic circuit board 11 (thermal expansion coefficient is about 3 to 10 × 10 −6 / ° C.) and the heat radiating member 16 (thermal expansion coefficient is about 18 to 23 × 10 −6 / ° C.) are greatly different. For this reason, a crack may be generated in the solder between the ceramic circuit board 11 and the heat radiating member 16, peeling may occur, and reliability may be significantly deteriorated. Therefore, a configuration is adopted in which the ceramic circuit board 11 and the heat radiating member 16 are bonded and mounted via a grease-like heat transfer composition 15 instead of solder.
[0011]
[Problems to be solved by the invention]
However, the grease-like heat transfer composition 15 is low in heat conduction, and therefore, if the heat transfer composition 15 between the ceramic circuit board 11 and the heat dissipation member 16 becomes thick, the heat dissipation path from the semiconductor element 17 is blocked and is good. Heat dissipation cannot be performed, which causes a problem that the semiconductor element 17 cannot be operated stably and reliably due to thermal destruction or deterioration of characteristics of the semiconductor element 17.
[0012]
In addition, the ceramic substrate 12 itself has some undulation, and the optimum metal circuit board 13 and metal plate 14 are formed depending on the size of the ceramic substrate 12, the circuit pattern of the metal circuit board 13, and the thickness of the ceramic substrate 12. Although it is necessary to design the thickness, it is very difficult to make the back surface of the ceramic circuit board 11 completely flat. Therefore, when the ceramic circuit board 11 is bonded to the heat dissipation member 16 via the heat transfer composition 15, the heat conductivity below the semiconductor element 17 that affects the temperature rise of the semiconductor element 17 even if the ceramic circuit board 11 is pressed. The composition 15 has a tendency not to flow out of the metal plate 14 sufficiently because the viscosity of the heat transfer composition 15 itself and further the undulation of the ceramic substrate 12 are obstructed. There is also a problem that it is difficult to reduce the thickness of the heat transfer composition 15.
[0013]
The present invention has been devised in order to solve the above-described problems in the prior art, and its purpose is to reduce the heat conductive composition having a relatively low thermal conductivity to increase the thermal resistance. An object of the present invention is to provide a ceramic circuit board that can be prevented, has good heat dissipation characteristics, and can stably operate electronic components such as semiconductor elements mounted on a metal circuit board over a long period of time.
[0014]
[Means for Solving the Problems]
The present invention includes a metal plate, a ceramic substrate mounted on the metal plate, and a metal circuit plate mounted on the ceramic substrate and having an electronic component mounting area on the upper surface thereof. In the ceramic circuit board in which the groove for entering the heat transfer composition is formed on the lower surface, when the thickness from the lower surface of the metal plate to the upper surface of the metal circuit plate in the mounting region of the electronic component is H, The end of the groove on the electronic component side is located at a position separated from the outer side of the electronic component mounting area by a distance H in plan view.
[0015]
The present invention also includes a metal plate having a groove formed on the lower surface for allowing the heat conductive composition to enter, a ceramic substrate mounted on the metal plate, a metal circuit plate mounted on the ceramic substrate, A module comprising: an electronic component mounted on a metal circuit board; and a heat dissipating member joined to the lower surface of the metal plate via the heat conductive composition, wherein the metal plate in a mounting area of the electronic component When the thickness from the lower surface of the metal circuit board to the upper surface of the metal circuit board is H, the end of the groove on the electronic component side is located at a position separated from the outer side of the electronic component by a distance H in plan view. It is characterized by.
[0016]
According to the ceramic circuit board of the present invention, the heat generated in the semiconductor element 7 due to the above configuration spreads at an angle of about 45 ° when conducted to the heat radiating member 6 side. Since there is no portion where the thickness of the metal plate 4 is thin, and there is no groove 8 in which the heat transfer composition 5 has entered, heat conduction in the metal plate 4 is not hindered.
[0018]
With such a configuration, according to the ceramic circuit board of the present invention, heat dissipation characteristics are good, and electronic components such as semiconductor elements mounted on the metal circuit board can be stably operated over a long period of time. Become.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, an example of an embodiment of the ceramic circuit board of the present invention will be described in detail with reference to the accompanying drawings.
[0020]
FIG. 1 is a cross-sectional view showing an example of a semiconductor module using a ceramic circuit board 1 of the present invention, in which 2 is a ceramic substrate, 3 is a metal circuit board, 4 is a metal plate, 5 is a heat transfer composition, and 6 is A heat radiating member, 7 is a semiconductor element as an electronic component, and 8 is a groove. FIG. 2 is a plan view of the metal plate 4 when the ceramic circuit board 1 of the present invention is viewed from the metal plate 4 side.
[0021]
The ceramic substrate 2 functions as a support member for supporting the metal circuit board 3 and the metal plate 4, and is an aluminum oxide (Al 2 O 3 ) sintered body, a mullite (3Al 2 O 3 .2SiO 2 ) sintered body, It is formed of a ceramic material such as a silicon carbide (SiC) sintered body, an aluminum nitride (AlN) sintered body, or a silicon nitride (Si 3 N 4 ) sintered body.
[0022]
The ceramic substrate 2 is preferably formed of a silicon nitride sintered body having high mechanical strength and high toughness. In order to effectively dissipate and dissipate the heat generated by the semiconductor element 7 mounted on the metal circuit board 3 from the metal circuit board 3 to the metal plate 4, thereby improving the heat dissipation characteristics of the ceramic circuit board 1. The thermal conductivity of the ceramic substrate 2 is preferably at least 60 W / m · K, particularly preferably 80 W / m · K or more, more preferably 100 W / m · K or more.
[0023]
If the ceramic substrate 2 is formed of, for example, a silicon nitride-based sintered body, first, a silicon nitride powder is added and mixed with a sintering aid such as a rare earth oxide powder or an aluminum oxide powder. The material sintered compact raw material powder is adjusted. Next, an organic binder and a dispersion medium are added to and mixed with the silicon nitride-based sintered raw material powder to form a paste, and this paste is formed into a sheet shape by a normal forming method such as a doctor blade method to obtain a silicon nitride-based green sheet. Make it. A required number of such silicon nitride green sheets are laminated, pressed, etc., and subjected to pressure bonding (pressure bonding) to produce a silicon nitride molded body. Thereafter, the silicon nitride-based molded body is degreased in air or a non-oxidizing atmosphere such as a nitrogen atmosphere, and then fired in a non-oxidizing atmosphere such as a nitrogen atmosphere to obtain the target ceramic substrate 2.
[0024]
The ceramic substrate 2 preferably has a thickness of 0.2 to 1.0 mm in order to improve the mechanical strength of the ceramic circuit substrate 1 and not to deteriorate the heat dissipation characteristics. If it is less than 0.2 mm, the ceramic substrate 2 tends to be easily cracked due to the stress generated when the ceramic substrate 2 is bonded to the metal circuit board 3 and the metal plate 4. On the other hand, if it exceeds 1.0 mm, it tends to be difficult to transfer heat generated from the semiconductor element 7 to the heat radiating member 6 satisfactorily.
[0025]
The ceramic circuit board 1 of the present invention is a metal circuit board made of a metal material such as copper or aluminum having conductivity on the upper and lower surfaces of the ceramic substrate 2 manufactured as described above by using a direct bonding method or an active metal method. 3 and the metal plate 4 are integrally joined to each other.
[0026]
For example, when the active metal method is used, an active metal such as titanium, zirconium or hafnium or its hydrogen is added to a silver braze powder made of silver-copper alloy powder or an aluminum braze powder made of aluminum-silicon alloy powder. An active metal brazing paste obtained by adding and mixing an appropriate organic solvent / solvent with an active metal brazing material to which 2 to 5% by weight of an active metal powder comprising at least one chemical compound is added is mixed with the upper and lower surfaces of the ceramic substrate 2. In addition, printing is performed in a predetermined pattern corresponding to the metal circuit board 3 and the metal plate 4 by using a conventionally known screen printing technique.
[0027]
Thereafter, the metal circuit board 3 and the metal board 4 are placed on the pattern of the active metal brazing paste, and this is placed in a vacuum or in a neutral or reducing atmosphere at a predetermined temperature (about 900 ° C. in the case of silver brazing). In the case of the aluminum brazing material, the heat treatment is performed at about 600 ° C. to melt the active metal brazing material, and the upper and lower surfaces of the ceramic substrate 2 are bonded to the metal circuit board 3 and the metal plate 4. Thereby, the metal circuit board 3 and the metal plate 4 are attached to the upper and lower surfaces of the ceramic substrate 2.
[0028]
The metal circuit board 3 and the metal board 4 made of copper, aluminum, or the like can be obtained, for example, by applying a conventionally known metal processing method such as a rolling method or a punching method to an ingot such as copper or aluminum. The thickness is 0.5 mm, and the circuit pattern is formed in a predetermined pattern shape corresponding to the shape of the circuit pattern or the circuit pattern and the shape between the circuits. The standard thickness of the metal circuit board 3 and the metal board 4 suppresses heat generation of the metal circuit board 3 due to a large current, and the joining interface is formed when the metal circuit board 3 and the ceramic substrate 2 made of a silicon nitride sintered body are joined. In order to suppress the occurrence of cracks due to the heat load generated in the film, the thickness is preferably 0.1 to 1.0 mm. If the thickness is less than 0.1 mm, the electric resistance of the metal circuit board 3 is increased, so that a high current signal from the semiconductor element 7 tends to be difficult to propagate. On the other hand, when the thickness exceeds 1.0 mm, the ceramic substrate 2 tends to be cracked due to the stress generated when the ceramic substrate 2 is bonded to the metal circuit board 3 and the metal plate 4.
[0029]
If the metal circuit board 3 and the metal board 4 are made of copper, if the metal circuit board 3 and the metal board 4 are made of oxygen-free copper, the oxygen-free copper is caused by oxygen existing in the copper surface during brazing. Since the wettability with the brazing material is improved without being oxidized, the bonding with the ceramic substrate 2 through the brazing material is strengthened. Therefore, the metal circuit board 3 and the metal board 4 are preferably formed of oxygen-free copper.
[0030]
The standard thickness and material of the metal circuit board 3 and the metal board 4 are the same material in order to suppress warpage due to heating during brazing with active metal or reflow for mounting electronic components such as the semiconductor element 7. In this case, it is preferable that the thickness of the metal plate 4 is smaller than the thickness of the metal circuit plate 3.
[0031]
Further, the metal circuit board 3 is formed on the surface of the metal circuit board 3 and the outside by depositing a metal having good conductivity made of nickel and having good corrosion resistance and wettability with the brazing material. The electrical connection with the electric circuit can be improved, and the electronic component such as the semiconductor element 7 can be firmly bonded to the metal circuit board 3 via the solder. Therefore, the metal circuit board 3 is preferably coated with a metal having good conductivity made of nickel and having good corrosion resistance and wettability with the brazing material on the surface thereof.
[0032]
The metal plate 4 has a groove 8 (in FIG. 2) on the surface mounted on the heat radiating member 6 at a distance of the entire thickness of the ceramic circuit board 1 from the outer periphery of the semiconductor element 7 (indicated by H in FIGS. 1 and 2). (Indicated by a white portion). By forming the groove 8 in this manner, when the ceramic circuit board 1 is joined to the heat radiating member 6 via the heat conductive composition 5, the heat conductive composition 5 enters the groove 8 of the metal plate 4 from the periphery thereof. Therefore, it becomes possible to reduce the thickness of the heat-conductive composition 7 that is interposed immediately below and around the semiconductor element 7 and has a relatively low thermal conductivity, and to perform bonding. Therefore, an increase in thermal resistance can be prevented, and the ceramic circuit board 1 with improved heat dissipation can be provided.
[0033]
Heat generated in the semi-conductor element 7, while spreading at an angle of approximately 45 ° when conducted to the heat radiation member 6 side, the portion where the thickness of the metal plate 4 is thinner by a groove 8 in the heat conduction path In addition, since there is no groove 8 in which the heat transfer composition 5 has entered, heat conduction in the metal plate 4 is not hindered.
[0034]
When the end of the groove 8 on the semiconductor element 7 side is closer to the mounting area of the semiconductor element 7 than the position separated from the outer side of the mounting area of the semiconductor element 7 by a distance H in plan view, the heat transfer composition 5 The thermal diffusion in the metal plate 4 is hindered by the influence of the grooves 8 in which there is a tendency to increase the thermal resistance. If the end of the groove 8 on the semiconductor element 7 side is on the side farther from the outer side of the mounting area of the semiconductor element 7 by a distance H in plan view than the mounting area of the semiconductor element 7, the ceramic circuit board 1 is bonded to the heat radiating member 6 via the heat conductive composition 5, the heat conductive composition 5 immediately below and around the semiconductor element 7 spreads outward and the gap between the groove 8 and the heat radiating member 6. It becomes difficult to penetrate into the semiconductor element 7 and the thickness of the heat transfer composition 7 directly below and around the semiconductor element 7 and between the metal plate 4 and the heat radiating member 6 cannot be sufficiently reduced.
[0038]
The ceramic circuit board 1 of the present invention manufactured as described above is coated with a heat conductive composition 5 in the form of grease on a metal plate 4 and then bonded to a heat radiating member 6 made of aluminum or the like, Become. At this time, if the heat transfer composition 5 is applied uniformly on the metal plate 4 while avoiding the grooves 8 by adjusting the coating thickness, the heat transfer composition 5 immediately below and around the semiconductor element 7 is applied. Efficiently penetrates into the groove 8, it becomes possible to reduce the thickness of the heat conductive composition 7 that is interposed immediately below and around the semiconductor element 7 and has a relatively low thermal conductivity, thereby allowing bonding.
[0049]
Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
[0050]
For example, in the above example, the ceramic substrate 2 is formed of a silicon nitride sintered body. However, when the semiconductor element 7 generates a large amount of heat and wants to efficiently dissipate this heat, the ceramic substrate 2 May be formed of an aluminum nitride sintered body or a silicon nitride sintered body having a high heat transfer coefficient. In the above example, the metal circuit board 3 and the metal board 4 are brazed directly to the ceramic substrate 2 via the active metal brazing material. The metal circuit board 3 and the metal board 4 may be joined to the metallized metal layer via a brazing material. Alternatively, the circuit wiring pattern may be formed by brazing the ceramic circuit board 2 with the metal circuit board 3 formed in advance in the pattern shape of the circuit wiring through the active metal brazing material.
[0051]
【The invention's effect】
According to the ceramic circuit board of the present invention, heat generated in the semi-conductor element 7, while spreading at an angle of approximately 45 ° when conducted to the heat radiation member 6 side, the metal plate by a groove 8 in the heat conduction path Since there is no portion in which the thickness of 4 is reduced, and there is no groove 8 in which the heat transfer composition 5 has entered, heat conduction in the metal plate 4 is not hindered.
[0053]
With such a configuration, according to the ceramic circuit board of the present invention, heat dissipation characteristics are good, and electronic components such as semiconductor elements mounted on the metal circuit board can be stably operated over a long period of time. Become.
[0054]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a semiconductor module using a ceramic circuit board of the present invention.
FIG. 2 is a plan view of the metal plate 4 when the ceramic circuit board 1 shown in FIG. 1 is viewed from the metal plate 4 side.
FIG. 3 is a cross-sectional view showing an example of a semiconductor module using a conventional ceramic circuit board.
[Explanation of symbols]
1: Ceramic circuit board 2: Ceramic board 3: Metal circuit board 4: Metal board 5: Heat transfer composition 6: Heat radiation member 7: Semiconductor element 8: Groove T: Groove depth S: Groove width L: Semiconductor element The outer length of

Claims (2)

金属板と、該金属板上に搭載されたセラミック基板と、該セラミック基板上に搭載されるとともに、上面に電子部品の搭載領域を有する金属回路板とを備え、  A metal plate, a ceramic substrate mounted on the metal plate, and a metal circuit plate mounted on the ceramic substrate and having an electronic component mounting region on the upper surface;
前記金属板の下面に伝熱性組成物が入り込むための溝が形成されたセラミック回路基板において、  In the ceramic circuit board formed with grooves for the heat conductive composition to enter the lower surface of the metal plate,
前記電子部品の搭載領域における前記金属板の下面から前記金属回路板の上面までの厚みがＨであるときに、前記電子部品の搭載領域の外辺から平面視で距離Ｈだけ離間した位置に、前記溝の電子部品側の端部が位置することを特徴とするセラミック回路基板。  When the thickness from the lower surface of the metal plate to the upper surface of the metal circuit board in the electronic component mounting region is H, at a position separated from the outer side of the electronic component mounting region by a distance H in plan view, An end of the groove on the electronic component side is located. 下面に伝熱性組成物が入り込むための溝が形成された金属板と、該金属板上に搭載されたセラミック基板と、該セラミック基板上に搭載された金属回路板と、該金属回路板上に搭載された電子部品と、前記金属板の下面に前記伝熱性組成物を介して接合される放熱部材とを備えたモジュールであって、  A metal plate having a groove for entering the heat transfer composition on the lower surface, a ceramic substrate mounted on the metal plate, a metal circuit plate mounted on the ceramic substrate, and on the metal circuit plate A module comprising a mounted electronic component and a heat dissipating member joined to the lower surface of the metal plate via the heat conductive composition;
前記電子部品の搭載領域における前記金属板の下面から前記金属回路板の上面までの厚みがＨであるときに、前記電子部品の外辺から平面視で距離Ｈだけ離間した位置に、前記溝の電子部品側の端部が位置することを特徴とするモジュール。  When the thickness from the lower surface of the metal plate to the upper surface of the metal circuit board is H in the mounting area of the electronic component, the groove is located at a position separated from the outer side of the electronic component by a distance H in plan view. An electronic component side end portion is located.
JP2002081863A 2002-03-22 2002-03-22 Ceramic circuit board Expired - Fee Related JP3934966B2 (en)

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JP2006128571A (en) * 2004-11-01 2006-05-18 Toyota Motor Corp Semiconductor device
JP4793037B2 (en) * 2006-03-13 2011-10-12 株式会社豊田自動織機 Electronics
JP4941827B2 (en) * 2007-03-27 2012-05-30 日立金属株式会社 Semiconductor module
KR101207993B1 (en) 2010-11-09 2012-12-04 (주)엔비텍이앤씨 LED package having radiation function
KR101259052B1 (en) * 2011-03-30 2013-04-29 박재훈 Light emitting diode package with reflector having thermal radiation funtion, light emitting diode package assembly with reflector having thermal radiation funtion and method of manufacturing the same
CN110275371A (en) * 2018-03-18 2019-09-24 宁波舜宇光电信息有限公司 Projection arrangement and its manufacturing method and depth information device
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