JP2006073810A - Power semiconductor module and manufacturing method thereof - Google Patents

Power semiconductor module and manufacturing method thereof Download PDF

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JP2006073810A
JP2006073810A JP2004255687A JP2004255687A JP2006073810A JP 2006073810 A JP2006073810 A JP 2006073810A JP 2004255687 A JP2004255687 A JP 2004255687A JP 2004255687 A JP2004255687 A JP 2004255687A JP 2006073810 A JP2006073810 A JP 2006073810A
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power semiconductor
semiconductor element
metal plate
temperature
semiconductor module
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Katsuhiko Nishiyama
克彦 西山
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Toyota Motor Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—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
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L24/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • 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
    • H01L2924/013—Alloys
    • H01L2924/0132—Binary Alloys
    • H01L2924/01322—Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
    • 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
    • H01L2924/1301—Thyristor
    • 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]

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable power semiconductor module by preventing improper conduction from taking place between a power semiconductor element and a metallic plate, even if cracks are generated in a joining member for joining the power semiconductor element and the metallic plate by stress caused by a heat cycle. <P>SOLUTION: The power semiconductor module 1 is provided with the power semiconductor element 2; the metallic plate 3 for forming an electrode; and the joining member 4 whose melting point is lower than the element operation permissible temperature of the power semiconductor element, and which conductively joins the power semiconductor element with the metallic plate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、パワー半導体モジュールの技術に関する。
より詳細には、熱サイクルに起因するストレスによりパワー半導体素子と金属板とを接合する接合部材に発生するクラックを防止し、パワー半導体モジュールの信頼性を向上させる技術に関する。 The present invention relates to a technology of a power semiconductor module.
More specifically, the present invention relates to a technique for preventing a crack generated in a joining member that joins a power semiconductor element and a metal plate due to stress caused by a thermal cycle, and improving the reliability of the power semiconductor module.

従来、ＩＧＢＴ、ＦＥＴ、ダイオード、サイリスタ等のパワー半導体素子と、電極を形成する金属板等と、をはんだ等の接合部材により導通可能に接合したパワー半導体モジュールの技術は公知となっている。例えば、特許文献１に記載の如くである。
特開２０００−３４９２０９号公報 Conventionally, a technique of a power semiconductor module in which a power semiconductor element such as an IGBT, FET, diode, or thyristor and a metal plate that forms an electrode are joined so as to be conductive by a joining member such as solder has been publicly known. For example, as described in Patent Document 1.
JP 2000-349209 A

近年、パワー半導体モジュールは大電流に対応することが求められ、大電流を流した場合の発熱対策として、該電極を形成する金属板の断面積（厚さ）を大きくする傾向がある。   In recent years, power semiconductor modules are required to cope with a large current, and there is a tendency to increase the cross-sectional area (thickness) of a metal plate forming the electrode as a countermeasure against heat generation when a large current is passed.

しかし、パワー半導体モジュールに流す電流を大きくすると、以下の如き問題が発生する。
パワー半導体素子を構成する代表的な材料であるシリコンの線膨張係数（約４ｐｐｍ／℃）は、電極を形成する金属板を構成する代表的な材料である銅の線膨張係数（約１６ｐｐｍ／℃）またはアルミニウムの線膨張係数（約２３ｐｐｍ／℃）との差が大きい。
そのため、パワー半導体モジュールに流す大電流をオン・オフすることによりパワー半導体素子や金属板の温度が上昇と下降とを繰り返す（熱サイクル）と、パワー半導体素子と金属板とを接合している接合部材は、パワー半導体素子と金属板の線膨張係数の差により、剪断方向（パワー半導体素子または金属板との接合面に平行な方向）にストレスを受ける。そして、当該ストレスにより接合部材にはクラックが生じ、最終的にパワー半導体素子と金属板との間の導通不良を起こす場合が考えられる。 However, when the current flowing through the power semiconductor module is increased, the following problems occur.
The linear expansion coefficient (about 4 ppm / ° C.) of silicon, which is a typical material constituting a power semiconductor element, is the linear expansion coefficient (about 16 ppm / ° C.) of copper, which is a typical material constituting a metal plate forming an electrode. ) Or the linear expansion coefficient of aluminum (about 23 ppm / ° C.).
For this reason, when the large current flowing through the power semiconductor module is turned on and off, the temperature of the power semiconductor element and the metal plate repeatedly rise and fall (thermal cycle), and the power semiconductor element and the metal plate are joined. The member is stressed in the shearing direction (direction parallel to the joint surface with the power semiconductor element or the metal plate) due to the difference in linear expansion coefficient between the power semiconductor element and the metal plate. Then, it is conceivable that a crack is generated in the joining member due to the stress, and a conduction failure is finally caused between the power semiconductor element and the metal plate.

上記接合部材のクラックを防止する方法の一つとして、パワー半導体素子を構成する材料（主にシリコン、ＳｉＣ）の線膨張係数に近い線膨張係数を持つＡｌＮ（約５ｐｐｍ／℃）やＳｉＯ（約７ｐｐｍ／℃）等のセラミックスからなる絶縁基板に該金属板を接合し、該金属板の「見かけの線膨張係数」を、パワー半導体素子を構成する材料の線膨張係数に近づける方法が挙げられる。
しかし、この方法はパワー半導体モジュールの金属板が厚くなると（厚さが０．５ｍｍ以上の場合には）有効でない。これは、金属板の一方の面に絶縁基板を接合することによる“金属板の「見かけの線膨張係数」を絶縁基板の線膨張係数に近づける効果”が、金属板において絶縁基板と接合されている方の面の近傍（厚さ方向において約０．５ｍｍの範囲）にしか及ばないことによる。
従って、パワー半導体モジュールに大電流を流すことを想定して金属板を厚くする場合には、上記方法により接合部材のクラックの発生を防止することが困難となる。 As one of the methods for preventing the crack of the joining member, AlN (about 5 ppm / ° C.) or SiO (about about a linear expansion coefficient close to the linear expansion coefficient of the material (mainly silicon, SiC) constituting the power semiconductor element. The metal plate is joined to an insulating substrate made of ceramics such as 7 ppm / ° C., and the “apparent linear expansion coefficient” of the metal plate is brought close to the linear expansion coefficient of the material constituting the power semiconductor element.
However, this method is not effective when the metal plate of the power semiconductor module becomes thick (when the thickness is 0.5 mm or more). This is because the “effect of bringing the“ apparent linear expansion coefficient ”of the metal plate close to the linear expansion coefficient of the insulating substrate” by bonding the insulating substrate to one surface of the metal plate is bonded to the insulating substrate in the metal plate. This is because it extends only to the vicinity of the surface on the other side (a range of about 0.5 mm in the thickness direction).
Therefore, when the metal plate is thickened assuming that a large current flows through the power semiconductor module, it becomes difficult to prevent the joining member from cracking by the above method.

本発明は以上の如き状況に鑑み、熱サイクルに起因するストレスによりパワー半導体素子と金属板とを接合する接合部材にクラックが発生した場合でも、パワー半導体素子と金属板との間の導通不良を起こすことを防止し、信頼性の高いパワー半導体モジュールを提供するものである。   In view of the situation as described above, the present invention eliminates poor conduction between the power semiconductor element and the metal plate even when a crack occurs in the joining member that joins the power semiconductor element and the metal plate due to stress caused by thermal cycling. It is an object of the present invention to provide a highly reliable power semiconductor module that prevents the occurrence of the occurrence.

本発明の解決しようとする課題は以上の如くであり、次にこの課題を解決するための手段を説明する。   The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

即ち、請求項１においては、パワー半導体素子と、電極を形成する金属板と、融点が該パワー半導体素子の素子動作許容温度よりも低く、該パワー半導体素子と該金属板とを導通可能に接合する接合部材と、を具備するものである。   That is, in claim 1, the power semiconductor element, the metal plate forming the electrode, and the melting point is lower than the element operation allowable temperature of the power semiconductor element, and the power semiconductor element and the metal plate are joined to be conductive. And a joining member to be provided.

請求項２においては、前記接合部材の融点は前記パワー半導体素子の定格動作温度よりも高いものである。   According to a second aspect of the present invention, the melting point of the joining member is higher than the rated operating temperature of the power semiconductor element.

請求項３においては、前記接合部材は、５２Ｉｎ−４８Ｓｎ合金、５０Ｂｉ−２８Ｐｂ−２２Ｓｎ合金、４０Ｂｉ−４０Ｐｂ−１１．５Ｓｎ−８．５Ｃｄ合金、４７．７Ｂｉ−３３．２Ｐｂ−１８．８Ｓｎ−０．３Ｓｂ合金のうちのいずれかの合金、または、これらと同様または近似の合金からなるものである。   According to a third aspect of the present invention, the joining member includes 52In-48Sn alloy, 50Bi-28Pb-22Sn alloy, 40Bi-40Pb-11.5Sn-8.5Cd alloy, 47.7Bi-33.2Pb-18.8Sn-0. It is made of any alloy of 3Sb alloys, or an alloy similar to or similar to these alloys.

請求項４においては、前記接合部材の表面において、前記パワー半導体素子および前記金属板のいずれにも接していない部分を被覆し、かつ、該パワー半導体素子と該金属板とを接合する絶縁部材を具備するものである。   The insulating member that covers a portion of the surface of the joining member that is not in contact with either the power semiconductor element or the metal plate and that joins the power semiconductor element and the metal plate. It has.

請求項５においては、前記絶縁部材は、ガラス転移点が前記接合部材の融点よりも高い熱硬化性樹脂からなるものである。   According to a fifth aspect of the present invention, the insulating member is made of a thermosetting resin having a glass transition point higher than the melting point of the bonding member.

請求項６においては、前記接合部材を融点以上の温度に加熱する加熱手段を具備するものである。   According to a sixth aspect of the invention, there is provided heating means for heating the bonding member to a temperature equal to or higher than the melting point.

請求項７においては、前記パワー半導体素子が前記加熱手段を兼ね、該パワー半導体素子のスイッチング周波数を変えることにより該パワー半導体素子の温度を上昇させるものである。   According to a seventh aspect of the present invention, the power semiconductor element also serves as the heating means, and raises the temperature of the power semiconductor element by changing a switching frequency of the power semiconductor element.

請求項８においては、接合部材によりパワー半導体素子と電極を形成する金属板とを導通可能に接合する第一の工程と、絶縁部材により該接合部材の表面において該パワー半導体素子および該金属板のいずれにも接していない部分を被覆するとともに、該パワー半導体素子と該金属板とを接合する第二の工程と、を具備するものである。   In claim 8, the first step of joining the power semiconductor element and the metal plate forming the electrode with the joining member so as to be conductive, and the insulating member on the surface of the joining member of the power semiconductor element and the metal plate. A second step of covering a portion that is not in contact with any of the two and joining the power semiconductor element and the metal plate.

本発明の効果として、以下に示すような効果を奏する。   As effects of the present invention, the following effects can be obtained.

請求項１においては、接合部材にクラックが発生すると接合部材が溶融して再び凝固することにより、該クラックを無くし、パワー半導体素子と金属板との間の導通不良を防止することが可能である。   In claim 1, when a crack occurs in the joining member, the joining member melts and solidifies again, thereby eliminating the crack and preventing a conduction failure between the power semiconductor element and the metal plate. .

請求項２においては、通電時に接合部材にクラックが発生していない場合には、該接合部材を固体状に保持することが可能である。   According to the second aspect of the present invention, when no crack is generated in the joining member during energization, the joining member can be held in a solid state.

請求項３においては、接合部材にクラックが発生すると接合部材が溶融して再び凝固することにより、該クラックを無くし、パワー半導体素子と金属板との間の導通不良を防止することが可能である。   In claim 3, when a crack occurs in the joining member, the joining member melts and solidifies again, thereby eliminating the crack and preventing a poor conduction between the power semiconductor element and the metal plate. .

請求項４においては、溶融した状態の接合部材が大気に触れて酸化し、パワー半導体素子および金属板との濡れ性の低下、ひいては電気的接触の悪化に起因する導通不良を防止することが可能である。
また、接合部材が溶融した状態でも、パワー半導体素子と金属板との位置関係を保持することが可能である。
さらに、溶融した状態の接合部材がパワー半導体素子と金属板とを接合している場所から流出することを防止することが可能である。 According to the fourth aspect of the present invention, it is possible to prevent the poor connection due to the deterioration of the wettability between the power semiconductor element and the metal plate and the deterioration of the electrical contact when the molten joining member is exposed to the atmosphere and oxidized. It is.
Further, the positional relationship between the power semiconductor element and the metal plate can be maintained even when the bonding member is melted.
Furthermore, it is possible to prevent the molten joining member from flowing out from the place where the power semiconductor element and the metal plate are joined.

請求項５においては、製造時における作業性に優れる。   In Claim 5, it is excellent in workability | operativity at the time of manufacture.

請求項６においては、任意の時に接合部材を溶融させ、再び凝固させてクラックを無くすことが可能であり、信頼性が向上する。   According to the sixth aspect of the present invention, it is possible to melt the joining member at any time and solidify it again to eliminate cracks, thereby improving the reliability.

請求項７においては、任意の時に接合部材を溶融させ、再び凝固させてクラックを無くすことが可能であり、信頼性が向上する。   According to the seventh aspect of the present invention, it is possible to melt the joining member at any time and solidify it again to eliminate cracks, thereby improving the reliability.

請求項８においては、接合部材にクラックが発生すると接合部材が溶融して再び凝固することにより、該クラックを無くし、パワー半導体素子と金属板との間の導通不良を防止することが可能である。   In claim 8, when a crack occurs in the joining member, the joining member melts and solidifies again, thereby eliminating the crack and preventing poor conduction between the power semiconductor element and the metal plate. .

以下では、図１を用いて本発明に係るパワー半導体モジュールの実施の一形態であるパワー半導体モジュール１について説明する。
パワー半導体モジュール１は主にパワー半導体素子２、金属板３、接合部材４、絶縁部材５等を具備する。
パワー半導体モジュール１は、熱サイクルに起因するストレスによりパワー半導体素子２と金属板３とを接合する接合部材４にクラックが発生した場合でも、接合部材４が溶融することにより該クラックを無くすことが可能であり、該クラックが進展して最終的にパワー半導体素子２と金属板３との間の導通不良（導通不能）を起こすことを防止できる。
以下、パワー半導体モジュール１の各構成部材について説明する。 Below, the power semiconductor module 1 which is one Embodiment of the power semiconductor module which concerns on this invention using FIG. 1 is demonstrated.
The power semiconductor module 1 mainly includes a power semiconductor element 2, a metal plate 3, a joining member 4, an insulating member 5, and the like.
The power semiconductor module 1 can eliminate the crack by melting the bonding member 4 even when a crack is generated in the bonding member 4 that bonds the power semiconductor element 2 and the metal plate 3 due to stress caused by the thermal cycle. It is possible to prevent the crack from progressing and finally causing a conduction failure (impossibility of conduction) between the power semiconductor element 2 and the metal plate 3.
Hereinafter, each component of the power semiconductor module 1 will be described.

パワー半導体素子２は、主にシリコンやＳｉＣ等の半導体からなる素子である。パワー半導体素子２の具体例としてはＩＧＢＴ（Ｉｎｓｕｌａｔｅｄ（またはＩｎｅｒｔｅｄ） Ｇａｔｅ Ｂｉｐｏｌａｒ Ｔｒａｎｓｉｓｔｏｒ）、ＢＴ（Ｂｉｐｏｌａｒ Ｔｒａｎｓｉｓｔｏｒ）、ＦＥＴ（Ｆｉｅｌｄ Ｅｆｆｅｃｔ Ｔｒａｎｓｉｓｔｏｒ）、ダイオード、ＧＴＯサイリスタ（Ｇａｔｅ Ｔｕｒｎ Ｏｆｆ Ｔｈｙｒｉｓｔｏｒ）、その他のサイリスタ等が挙げられる。   The power semiconductor element 2 is an element mainly made of a semiconductor such as silicon or SiC. Specific examples of the power semiconductor element 2 include an IGBT (Insulated (or Interted) Gate Bipolar Transistor), a BT (Bipolar Transistor), an FET (Field Effect Transistor), a diode, a GTO thyristor (Gate Turn thyristor), and the like. Can be mentioned.

金属板３は銅やアルミニウム等の導電性の金属からなる板状の部材（金属板）であり、パワー半導体素子２の電極（導電経路）を形成する。該金属板３はパワー半導体モジュール１を構成する他の部材であるブスバーや電気配線（図示せず）に接続され、パワー半導体モジュール１の外部と導通可能となっている。
また、金属板３はパワー半導体素子２にて発生する熱を逃がすための放熱経路としての機能を兼ねる。 The metal plate 3 is a plate-like member (metal plate) made of a conductive metal such as copper or aluminum, and forms an electrode (conductive path) of the power semiconductor element 2. The metal plate 3 is connected to a bus bar or an electrical wiring (not shown) which is another member constituting the power semiconductor module 1 and can be electrically connected to the outside of the power semiconductor module 1.
The metal plate 3 also functions as a heat dissipation path for releasing heat generated in the power semiconductor element 2.

接合部材４はパワー半導体素子２と金属板３とを導通可能に接合する部材である。接合部材４は、その融点がパワー半導体素子２の素子動作許容温度よりも低い材料により構成される。また、接合部材４はパワー半導体素子２にて発生する熱を熱伝導により逃がすための放熱経路を兼ねる。
ここで、「素子動作許容温度」とは、パワー半導体素子２が所定の機能を保証するために許容し得る上限の温度（パワー半導体素子２が壊れる下限の温度）をいう。なお、本実施例のパワー半導体素子２の素子動作許容温度は１５０℃であるが、素子動作許容温度はパワー半導体素子２の種類により異なるものであり、１５０℃に限定されるものではない。 The joining member 4 is a member that joins the power semiconductor element 2 and the metal plate 3 so as to be conductive. The bonding member 4 is made of a material whose melting point is lower than the element operation allowable temperature of the power semiconductor element 2. The joining member 4 also serves as a heat dissipation path for releasing heat generated in the power semiconductor element 2 by heat conduction.
Here, the “element operation allowable temperature” refers to an upper limit temperature that can be allowed for the power semiconductor element 2 to guarantee a predetermined function (a lower limit temperature at which the power semiconductor element 2 is broken). In addition, although element operating allowable temperature of the power semiconductor element 2 of a present Example is 150 degreeC, element operating allowable temperature changes with kinds of the power semiconductor element 2, and is not limited to 150 degreeC.

パワー半導体モジュール１は、設計段階においてパワー半導体モジュール１の放熱量を十分に確保する（例えば、放熱板や冷却水路を設ける）等して、パワー半導体モジュール１の定格動作温度を素子動作許容温度よりも低い温度に設定し、パワー半導体素子２が所定の機能を果たさなくなる事態が起こる（壊れる）ことを防止している。
ここで、「定格動作温度」とは、通常の使用環境下でパワー半導体モジュール１を使用した場合におけるパワー半導体素子２の温度を指す。定格動作温度はパワー半導体モジュール１の周囲の雰囲気温度、パワー半導体モジュール１を流れる電流値、放熱板や冷却水等によるパワー半導体モジュール１からの放熱量、等の要因により決定される。
パワー半導体素子２にて発生した熱は、熱伝導により接合部材４および金属板３を経て放熱されることから、接合部材４および金属板３の温度は通常、パワー半導体素子２の温度よりも低くなる。 The power semiconductor module 1 ensures a sufficient heat dissipation amount of the power semiconductor module 1 at the design stage (for example, by providing a heat sink or a cooling water channel), and the rated operating temperature of the power semiconductor module 1 is made higher than the element operation allowable temperature. Is set to a low temperature to prevent the power semiconductor element 2 from failing to break (destruct).
Here, the “rated operating temperature” refers to the temperature of the power semiconductor element 2 when the power semiconductor module 1 is used under a normal use environment. The rated operating temperature is determined by factors such as the ambient temperature around the power semiconductor module 1, the value of the current flowing through the power semiconductor module 1, the amount of heat released from the power semiconductor module 1 by a heat sink or cooling water, and the like.
Since the heat generated in the power semiconductor element 2 is radiated through the bonding member 4 and the metal plate 3 by heat conduction, the temperature of the bonding member 4 and the metal plate 3 is usually lower than the temperature of the power semiconductor element 2. Become.

従来のパワー半導体モジュールにおいても、本実施例のパワー半導体モジュール１と同様に、パワー半導体素子の保護を目的として、パワー半導体モジュールの定格動作温度を素子動作許容温度よりも低い温度に設定している。
従来のパワー半導体モジュールの接合部材にクラックが発生すると、パワー半導体素子で発生した熱を逃がす放熱経路の断面積が小さくなり、パワー半導体素子および接合部材の温度が上昇し、さらに線膨張係数の差に起因するストレスが大きくなる。
しかし、従来のパワー半導体モジュールは、パワー半導体素子と電極とを接合する接合部材として、一般的なはんだ（錫−鉛合金）あるいは鉛フリーはんだ（錫−銀合金、錫−銅合金、錫−銀−銅合金、錫−アンチモン合金）等を用いており、これら一般的なはんだあるいは鉛フリーはんだは、いずれもその融点がパワー半導体素子の素子動作許容温度よりも高い。例えば、Ｓｎ−Ｐｂ共晶はんだの融点は１８３℃であり、Ｓｎ−Ａｇはんだの融点は２２０℃である。よって、従来のパワー半導体モジュールは、使用時に接合部材（はんだや鉛はんだ）が溶融することは無い。
結果として、パワー半導体素子と電極とを接合する接合部材にクラックが一度発生すると、該クラックは熱サイクルによりさらに進展していき、最終的には接合部材が破断してパワー半導体素子と金属板との間の導通不良を起こす場合がある。 Also in the conventional power semiconductor module, the rated operating temperature of the power semiconductor module is set to a temperature lower than the element operation allowable temperature for the purpose of protecting the power semiconductor element, similarly to the power semiconductor module 1 of the present embodiment. .
When cracks occur in the joining member of a conventional power semiconductor module, the cross-sectional area of the heat dissipation path for releasing the heat generated in the power semiconductor element is reduced, the temperature of the power semiconductor element and the joining member is increased, and the difference in linear expansion coefficient is increased. The stress caused by is increased.
However, the conventional power semiconductor module has a general solder (tin-lead alloy) or lead-free solder (tin-silver alloy, tin-copper alloy, tin-silver) as a joining member for joining the power semiconductor element and the electrode. -Copper alloy, tin-antimony alloy), etc., and these general solders or lead-free solders all have a melting point higher than the element operation allowable temperature of the power semiconductor element. For example, the melting point of Sn—Pb eutectic solder is 183 ° C., and the melting point of Sn—Ag solder is 220 ° C. Therefore, the conventional power semiconductor module does not melt the bonding member (solder or lead solder) during use.
As a result, once a crack occurs in the joining member that joins the power semiconductor element and the electrode, the crack further develops due to the thermal cycle, and eventually the joining member breaks and the power semiconductor element and the metal plate May cause poor conduction.

これに対して、本実施例のパワー半導体モジュール１の場合、接合部材４にクラックが発生して接合部材４の温度が上昇し、融点に達すると接合部材４が溶融し、液体状となる。
しかし、接合部材４の融点は素子動作許容温度よりも低いので、パワー半導体素子２が機能不全となることは無い。
そして、溶融した状態の接合部材４の放熱経路の断面積はクラックが発生した固体状の接合部材４よりも大きいので、パワー半導体素子２および接合部材４の温度が下降する。従って、溶融した状態の接合部材４は再び凝固してクラックの無い固体状の接合部材４となる。
このように、本実施例のパワー半導体モジュール１は、接合部材４にクラックが発生すると接合部材４が溶融して再び凝固することにより、該クラックを無くすことが可能である。従って、パワー半導体モジュール１は、接合部材４のクラックの進展により最終的にパワー半導体素子２と金属板３との間の導通不良を起こすことを防止することが可能であり、信頼性が高い。
また、接合部材４が溶融する際には周囲から潜熱を吸収するので、パワー半導体素子２の発熱量が急に増加し、熱伝導による放熱ではパワー半導体素子２の冷却が間に合わない場合でも、ある程度パワー半導体素子２の温度上昇を抑制することが可能である。 On the other hand, in the case of the power semiconductor module 1 of the present embodiment, cracks occur in the joining member 4 and the temperature of the joining member 4 rises. When the melting point is reached, the joining member 4 melts and becomes liquid.
However, since the melting point of the bonding member 4 is lower than the element operation allowable temperature, the power semiconductor element 2 does not malfunction.
And since the cross-sectional area of the thermal radiation path | route of the joining member 4 of the fuse | melted state is larger than the solid joining member 4 which the crack generate | occur | produced, the temperature of the power semiconductor element 2 and the joining member 4 falls. Therefore, the molten joining member 4 is solidified again to become a solid joining member 4 without cracks.
As described above, in the power semiconductor module 1 according to the present embodiment, when a crack occurs in the joining member 4, the joining member 4 melts and solidifies again, thereby eliminating the crack. Therefore, the power semiconductor module 1 can prevent the occurrence of poor conduction between the power semiconductor element 2 and the metal plate 3 due to the development of cracks in the bonding member 4 and has high reliability.
In addition, since the latent heat is absorbed from the surroundings when the bonding member 4 is melted, the amount of heat generated by the power semiconductor element 2 suddenly increases, and even if the power semiconductor element 2 cannot be cooled by heat dissipation due to heat conduction to some extent. It is possible to suppress the temperature rise of the power semiconductor element 2.

接合部材４に好適な材料の具体例としては、以下の（１）から（５）に記載の合金が挙げられる。
（１） ５２Ｉｎ−４８Ｓｎ合金：５２重量％のインジウムと４８重量％の錫からなる合金（融点１１７℃）
（２） ５０Ｂｉ−２８Ｐｂ−２２Ｓｎ合金：５０重量％のビスマスと２８重量％の鉛と２２重量％の錫からなる合金（融点１２４℃）
（３） ４０Ｂｉ−４０Ｐｂ−１１．５Ｓｎ−８．５Ｃｄ合金：４０重量％のビスマスと４０重量％の鉛と１１．５重量％の錫と８．５重量％のカドミウムからなる合金（融点１３０℃）
（４） ４７．７Ｂｉ−３３．２Ｐｂ−１８．８Ｓｎ−０．３Ｓｂ合金：４７．７重量％のビスマスと３３．２重量％の鉛と１８．８重量％の錫と０．３重量％のアンチモンからなる合金（融点１３０℃）
（５） 上記（１）から（４）に記載の合金と同様または近似の合金 Specific examples of materials suitable for the bonding member 4 include the alloys described in (1) to (5) below.
(1) 52In-48Sn alloy: Alloy composed of 52 wt% indium and 48 wt% tin (melting point 117 ° C)
(2) 50Bi-28Pb-22Sn alloy: Alloy consisting of 50% by weight of bismuth, 28% by weight of lead and 22% by weight of tin (melting point 124 ° C.)
(3) 40Bi-40Pb-11.5Sn-8.5Cd alloy: Alloy consisting of 40% by weight bismuth, 40% by weight lead, 11.5% by weight tin and 8.5% by weight cadmium (melting point 130 ° C. )
(4) 47.7Bi-33.2Pb-18.8Sn-0.3Sb alloy: 47.7 wt% bismuth, 33.2 wt% lead, 18.8 wt% tin and 0.3 wt% Antimony alloy (melting point 130 ° C)
(5) An alloy similar to or similar to the alloy described in (1) to (4) above

ここで、「（１）から（４）に記載の合金と同様の合金」とは、（１）から（４）に記載の合金と組成が異なるが、導通可能であり、融点がパワー半導体素子２の素子動作許容温度よりも低い材料を含む。
また、「（１）から（４）に記載の合金と近似の合金」とは、（１）から（４）に記載の合金に近似の組成を有する合金であって、融点がパワー半導体素子２の素子動作許容温度よりも低い材料を含む。ここで、「近似の組成を有する合金」とは、（ａ）合金に含まれる元素の組み合わせは同じであるが各元素の重量比が若干異なる場合、または、（ｂ）合金に含まれる元素の組み合わせの一部を別の元素に置換または合金に含まれる元素の組み合わせに一種類以上の別の元素を追加したもの、が挙げられる。 Here, “alloy similar to the alloy described in (1) to (4)” is different in composition from the alloy described in (1) to (4), but is conductive and has a melting point of a power semiconductor element. 2 containing the material lower than the element operation allowable temperature.
The “alloy similar to the alloy described in (1) to (4)” is an alloy having an approximate composition to the alloy described in (1) to (4), and has a melting point of the power semiconductor element 2. A material having a temperature lower than the allowable device operation temperature is included. Here, the “alloy having an approximate composition” means that (a) the combination of elements contained in the alloy is the same, but the weight ratio of each element is slightly different, or (b) the element contained in the alloy A combination of a part of the combination with another element or a combination of elements contained in the alloy with one or more other elements added.

上記（１）から（５）に記載の合金は、いずれも、その融点が本実施例のパワー半導体素子２の素子動作許容温度よりも低いという特徴を有する。   Any of the alloys described in the above (1) to (5) has a feature that the melting point thereof is lower than the element operation allowable temperature of the power semiconductor element 2 of the present embodiment.

また、接合部材４は、その融点がパワー半導体素子２の定格動作温度よりも高い材料により構成されることが好ましい。これは、以下の理由による。
接合部材４の融点がパワー半導体素子２の定格動作温度よりも低いと、パワー半導体モジュール１の使用時には接合部材４が常に溶融していることとなるが、この場合でも、接合部材４のクラックの進展により最終的にパワー半導体素子２と金属板３との間の導通不良を起こすことを防止することが可能である。
しかし、溶融した状態の接合部材４の熱伝導率はクラックが無い固体状の接合部材４の熱伝導率よりも小さいので、接合部材４を、融点がパワー半導体素子２の定格動作温度よりも高い材料で構成することにより、通電時に接合部材４にクラックが発生していない場合には、接合部材４を固体状に保持し、パワー半導体モジュール１の発熱量をより小さくし、エネルギーロスを小さくすることが好ましい。 The joining member 4 is preferably made of a material whose melting point is higher than the rated operating temperature of the power semiconductor element 2. This is due to the following reason.
If the melting point of the bonding member 4 is lower than the rated operating temperature of the power semiconductor element 2, the bonding member 4 is always melted when the power semiconductor module 1 is used. It is possible to prevent a conduction failure between the power semiconductor element 2 and the metal plate 3 from being finally caused by the progress.
However, since the thermal conductivity of the molten bonding member 4 is smaller than the thermal conductivity of the solid bonding member 4 without cracks, the melting point of the bonding member 4 is higher than the rated operating temperature of the power semiconductor element 2. By being composed of a material, when no crack is generated in the joining member 4 during energization, the joining member 4 is held in a solid state, the heat generation amount of the power semiconductor module 1 is further reduced, and the energy loss is reduced. It is preferable.

絶縁部材５は接合部材４の表面においてパワー半導体素子２および金属板３のいずれにも接していない部分（露出部分）を被覆し、かつ、パワー半導体素子２と金属板３とを接合する絶縁性の材料からなる部材である。
絶縁部材５は接合部材４の表面を被覆することにより、溶融した状態の接合部材４を構成する材料が大気に触れて酸化し、パワー半導体素子２および金属板３との濡れ性の低下、ひいては電気的接触の悪化に起因する導通不良を防止する。
また、接合部材４が溶融すると、接合部材４がパワー半導体素子２と金属板３との位置関係を保持する（パワー半導体素子２を金属板３に固定する）機能を果たさなくなるが、絶縁部材５が、接合部材４が溶融した状態でも、パワー半導体素子２と金属板３との位置関係を保持する（パワー半導体素子２を金属板３に固定する）。
さらに、絶縁部材５は、溶融した状態の接合部材４がパワー半導体素子２と金属板３とを接合している場所（本実施例の場合、パワー半導体素子２と金属板３との間）から流出することを防止する。これは、接合部材４がパワー半導体素子２と金属板３とを接合している場所から流出すると、パワー半導体素子と金属板とを接合している場所にある接合部材が減少して、パワー半導体素子２と金属板３との間の導通不良を起こしたり、該流出した接合部材が他の導通経路を短絡させたりする場合があるからである。 Insulating member 5 covers a portion (exposed portion) that is not in contact with any of power semiconductor element 2 and metal plate 3 on the surface of bonding member 4, and also insulates power semiconductor element 2 and metal plate 3. It is the member which consists of material.
The insulating member 5 covers the surface of the bonding member 4, so that the material constituting the molten bonding member 4 is oxidized by exposure to the atmosphere, thereby reducing the wettability with the power semiconductor element 2 and the metal plate 3. It prevents continuity failure due to deterioration of electrical contact.
When the bonding member 4 is melted, the bonding member 4 does not perform the function of maintaining the positional relationship between the power semiconductor element 2 and the metal plate 3 (fixing the power semiconductor element 2 to the metal plate 3). However, even when the bonding member 4 is melted, the positional relationship between the power semiconductor element 2 and the metal plate 3 is maintained (the power semiconductor element 2 is fixed to the metal plate 3).
Furthermore, the insulating member 5 starts from a location where the molten joining member 4 joins the power semiconductor element 2 and the metal plate 3 (between the power semiconductor element 2 and the metal plate 3 in this embodiment). Prevent spillage. This is because when the joining member 4 flows out from the place where the power semiconductor element 2 and the metal plate 3 are joined, the joining member at the place where the power semiconductor element and the metal plate 3 are joined decreases, and the power semiconductor This is because poor conduction between the element 2 and the metal plate 3 may occur, or the flowed-out joining member may short-circuit other conduction paths.

絶縁部材５を構成する材料の好適な例としては熱硬化性樹脂が挙げられる。硬化前の熱硬化性樹脂は低温でも流動性があるため、接合部材４の表面においてパワー半導体素子２および金属板３のいずれにも接していない部分（露出部分）を被覆するのが容易であり、パワー半導体モジュール１の製造時における作業性に優れることによる。   A suitable example of the material constituting the insulating member 5 is a thermosetting resin. Since the thermosetting resin before curing is fluid even at a low temperature, it is easy to cover a portion (exposed portion) that is not in contact with either the power semiconductor element 2 or the metal plate 3 on the surface of the bonding member 4. This is because the workability at the time of manufacturing the power semiconductor module 1 is excellent.

熱硬化性樹脂で絶縁部材５を構成する場合、該熱硬化性樹脂のガラス転移温度（熱硬化性樹脂が軟化する温度）は、少なくとも接合部材４を構成する材料の融点よりも高いことが好ましく、パワー半導体素子２の素子動作許容温度よりも高いことがより好ましい。
これは、熱硬化性樹脂のガラス転移温度（熱硬化性樹脂が軟化する温度）が、接合部材４を構成する材料の融点よりも低いと、接合部材４が溶融する温度（融点）において絶縁部材５が変形したり破れたりして、接合部材４が大気に触れたり、溶融した接合部材４が絶縁部材５の外部に流出する場合があるからである。
絶縁部材５を構成する熱硬化性樹脂のガラス転移温度がパワー半導体素子２の素子動作許容温度よりも高い場合には、パワー半導体モジュール１の使用時において絶縁部材５が変形したり破れたりすることが無い。
絶縁部材５を構成する材料として好適な熱硬化性樹脂の一例としては、エポキシ樹脂が挙げられる。 When the insulating member 5 is composed of a thermosetting resin, the glass transition temperature of the thermosetting resin (the temperature at which the thermosetting resin softens) is preferably higher than at least the melting point of the material constituting the bonding member 4. It is more preferable that the temperature is higher than the element operation allowable temperature of the power semiconductor element 2.
This is because when the glass transition temperature of the thermosetting resin (the temperature at which the thermosetting resin softens) is lower than the melting point of the material constituting the bonding member 4, the insulating member is at the temperature (melting point) at which the bonding member 4 melts. This is because 5 may be deformed or torn, and the bonding member 4 may come into contact with the atmosphere, or the molten bonding member 4 may flow out of the insulating member 5.
When the glass transition temperature of the thermosetting resin constituting the insulating member 5 is higher than the element operation allowable temperature of the power semiconductor element 2, the insulating member 5 is deformed or broken when the power semiconductor module 1 is used. There is no.
An example of a thermosetting resin suitable as a material constituting the insulating member 5 is an epoxy resin.

パワー半導体モジュール１は、上記パワー半導体素子２、金属板３、接合部材４、絶縁部材５を複数組（例えば、一般的なインバータとして使用する場合には六組）具備する他、パワー半導体モジュール１を構成する部材を収容する樹脂等の絶縁材料からなる筐体、パワー半導体素子２や金属板３を外部の装置と導通させるためのブスバーや電気配線、パワー半導体素子２へ電圧を印可することによりスイッチング（パワー半導体素子２を流れる電流のオン・オフ）を行うための制御基板等を具備する。
また、場合によっては、パワー半導体素子２や金属板３等の発熱する部材を冷却するための冷却水路が形成される。 The power semiconductor module 1 includes a plurality of sets (for example, six sets when used as a general inverter) of the power semiconductor element 2, the metal plate 3, the bonding member 4, and the insulating member 5. By applying a voltage to the casing made of an insulating material such as a resin that accommodates the members constituting the power supply, the bus bar and the electric wiring for connecting the power semiconductor element 2 and the metal plate 3 to an external device, and the power semiconductor element 2 A control board or the like for performing switching (ON / OFF of current flowing through the power semiconductor element 2) is provided.
Further, depending on the case, a cooling water channel for cooling a heat generating member such as the power semiconductor element 2 or the metal plate 3 is formed.

また、パワー半導体モジュール１に、接合部材４を融点以上の温度に加熱する加熱手段（ヒータ等）を具備することも可能である。
このように構成することにより、接合部材４に発生したクラックが進展する等してパワー半導体素子２の温度が上昇した場合の他にも、任意の時に接合部材４を溶融させ、再び凝固させてクラックを無くすことが可能であり、信頼性が向上する。 Further, the power semiconductor module 1 can be provided with a heating means (heater or the like) for heating the bonding member 4 to a temperature higher than the melting point.
By configuring in this way, in addition to the case where the temperature of the power semiconductor element 2 rises due to the development of cracks generated in the joining member 4, the joining member 4 is melted and solidified again at any time. Cracks can be eliminated and reliability is improved.

上記加熱手段により接合部材４を溶融させ、再び凝固させるタイミングとしては、（Ａ）所定の期間経過毎、（Ｂ）接合部材４が固体の状態を保持している（融点以下の温度を保持している）期間を計測し、該期間が所定の期間を超えた時、（Ｃ）接合部材の温度がクラックが発生する可能性がある温度まで上昇した時、等が挙げられる。   Timing for melting and solidifying the joining member 4 by the heating means is as follows: (A) The joining member 4 is kept in a solid state every time a predetermined period elapses (a temperature below the melting point is kept). Measurement period), when the period exceeds a predetermined period, (C) when the temperature of the joining member rises to a temperature at which cracks may occur, and the like.

上記（Ａ）の場合、パワー半導体モジュール１は時間を計測する手段を具備する。
また、上記（Ｂ）の場合、パワー半導体モジュール１はパワー半導体素子２および接合部材４のうち、少なくとも一方の温度を検出する温度検出手段（例えば、熱電対等の温度センサ）と、該温度センサにより検出された温度に係る情報に基づいて接合部材４が固体の状態を保持している（融点以下の温度を保持している）期間を計測し、該期間が所定の期間を超えたか否かを判断する手段を具備する。
また上記（Ｃ）の場合、（Ａ）の場合、パワー半導体モジュール１は接合部材４の温度を測定する手段を具備する。 In the case of (A) above, the power semiconductor module 1 includes means for measuring time.
In the case of (B), the power semiconductor module 1 includes a temperature detecting means (for example, a temperature sensor such as a thermocouple) that detects the temperature of at least one of the power semiconductor element 2 and the bonding member 4, and the temperature sensor. Based on the information relating to the detected temperature, a time period during which the bonding member 4 maintains a solid state (a temperature below the melting point) is measured, and whether or not the time period exceeds a predetermined period. Means for determining are provided.
In the case of (C) above, in the case of (A), the power semiconductor module 1 includes means for measuring the temperature of the bonding member 4.

また、上記加熱手段の別実施例として、パワー半導体素子２を加熱手段として用いることができる。すなわち、図２に示す如く、同じ電流値の場合、パワー半導体素子２はスイッチング周波数が大きいほど損失（発熱量）が大きいので、パワー半導体素子２の周波数を通常の使用時よりも大きくして発熱量を増大させることにより、接合部材４を溶融させることが可能である。
なお、パワー半導体モジュール１をハイブリッド車に用いる場合、パワー半導体モジュール１に通電される電流値は運転者のアクセルやブレーキの操作により変化するが、スイッチング周波数はアクセルやブレーキの操作と独立して変化させることが可能であるため、使用時の任意のタイミングで運転者の操作に影響を与えずにスイッチング周波数を変化させることが可能である。 As another example of the heating means, the power semiconductor element 2 can be used as the heating means. That is, as shown in FIG. 2, in the case of the same current value, the power semiconductor element 2 has a larger loss (heat generation amount) as the switching frequency is larger, so the power semiconductor element 2 generates heat by increasing the frequency of the power semiconductor element 2 than in normal use. By increasing the amount, the joining member 4 can be melted.
When the power semiconductor module 1 is used in a hybrid vehicle, the current value supplied to the power semiconductor module 1 changes depending on the driver's accelerator or brake operation, but the switching frequency changes independently of the accelerator or brake operation. Therefore, it is possible to change the switching frequency without affecting the operation of the driver at any timing during use.

以下では、図３を用いてパワー半導体素子２を加熱手段として用いた場合のスイッチング周波数制御方法について説明する。   Below, the switching frequency control method at the time of using the power semiconductor element 2 as a heating means is demonstrated using FIG.

ステップＳ１１０において、パワー半導体モジュール１に具備され、パワー半導体素子２のスイッチング操作を行う制御基板（以後、単に「制御基板」という。）は、温度検出手段により検出されたパワー半導体素子２の温度と、接合部材４の融点とを比較する。
ここで、「温度検出手段」は、例えば端子電圧によりパワー半導体素子の温度検出に使用する温度検出用ダイオードでも良く、公知の技術を使用した温度検出用センサでも良い。
制御基板は、温度検出手段により検出されたパワー半導体素子２の温度と、接合部材４の融点とを比較した結果、パワー半導体素子２の温度が接合部材４の融点以下の場合にはステップＳ１２０に移行し、パワー半導体素子２の温度が接合部材４の融点よりも高い場合にはステップＳ１３０に移行する。 In step S110, the control board (hereinafter simply referred to as “control board”) provided in the power semiconductor module 1 and performing the switching operation of the power semiconductor element 2 is the temperature of the power semiconductor element 2 detected by the temperature detecting means. The melting point of the joining member 4 is compared.
Here, the “temperature detection means” may be, for example, a temperature detection diode used for temperature detection of the power semiconductor element by a terminal voltage, or may be a temperature detection sensor using a known technique.
When the temperature of the power semiconductor element 2 is equal to or lower than the melting point of the bonding member 4 as a result of comparing the temperature of the power semiconductor element 2 detected by the temperature detection means and the melting point of the bonding member 4, the control board proceeds to step S <b> 120. If the temperature of the power semiconductor element 2 is higher than the melting point of the bonding member 4, the process proceeds to step S130.

ステップＳ１２０において、制御基板は、パワー半導体素子２の温度が接合部材４の融点以下の状態が継続していることを示すカウント数を１だけ上昇させ、ステップＳ１４０に移行する。   In step S120, the control board increases the count number indicating that the temperature of the power semiconductor element 2 is kept below the melting point of the bonding member 4 by 1, and proceeds to step S140.

ステップＳ１３０において、制御基板は、パワー半導体素子２の温度が接合部材４の融点以下の状態が継続していることを示すカウント数をゼロに戻し、ステップＳ１４０に移行する。   In step S130, the control board returns the count number indicating that the temperature of the power semiconductor element 2 is kept below the melting point of the bonding member 4 to zero, and proceeds to step S140.

ステップＳ１４０において、制御基板は、パワー半導体素子２の温度が接合部材４の融点以下の状態が継続していることを示すカウント数と、設定値（所定のカウント数）とを比較する。ここで、設定値は、接合部材４の予想寿命（通常の使用環境下において使用開始から熱サイクルにより接合部材４が破断して導通不良を起こすまでの予想期間）よりも短い時間に対応するカウント数とする。
制御基板は、パワー半導体素子２の温度が接合部材４の融点以下の状態が継続していることを示すカウント数と、設定値（所定のカウント数）とを比較した結果、該カウント数が設定値より小さい場合にはステップＳ１５０に移行し、該カウント数が設定値以上の場合にはステップＳ１６０に移行する。 In step S140, the control board compares a count value indicating that the temperature of the power semiconductor element 2 is kept below the melting point of the bonding member 4 with a set value (predetermined count number). Here, the set value is a count corresponding to a shorter time than the expected life of the joining member 4 (expected period from the start of use to the time when the joining member 4 breaks due to a thermal cycle and causes poor conduction in a normal use environment). It is a number.
The control board compares the count number indicating that the temperature of the power semiconductor element 2 is kept below the melting point of the bonding member 4 with a set value (predetermined count number). As a result, the count number is set. If it is smaller than the value, the process proceeds to step S150, and if the count is greater than or equal to the set value, the process proceeds to step S160.

ステップＳ１５０において、制御基板は、パワー半導体素子２のスイッチング周波数を通常の使用時の周波数に設定して、ステップＳ１１０に移行する。   In step S150, the control board sets the switching frequency of the power semiconductor element 2 to a frequency during normal use, and proceeds to step S110.

ステップＳ１６０において、制御基板は、パワー半導体素子２のスイッチング周波数を接合部材４を溶融させるための周波数（通常の使用時の周波数より高い周波数）に設定して、ステップＳ１１０に移行する。   In step S160, the control board sets the switching frequency of the power semiconductor element 2 to a frequency for melting the bonding member 4 (a frequency higher than the frequency during normal use), and proceeds to step S110.

以上の如く構成することにより、パワー半導体モジュール１は、パワー半導体素子２の温度が接合部材４の融点以下の状態（換言すれば、接合部材４が全て固体の状態、または一部が溶融した状態）が所定期間（所定のカウント数）継続した場合にはパワー半導体素子２のスイッチング周波数が高くなり、発熱量が上昇して接合部材４を溶融させ、その後は再びパワー半導体素子２の温度が接合部材４の融点以下の状態が継続していることを示すカウント数が設定値を超えるまでパワー半導体素子２のスイッチング周波数を通常使用時のスイッチング周波数に戻し、接合部材４を再び凝固させることが可能である。   By configuring as described above, the power semiconductor module 1 is in a state in which the temperature of the power semiconductor element 2 is equal to or lower than the melting point of the bonding member 4 (in other words, the bonding member 4 is entirely in a solid state or partially melted). ) Continues for a predetermined period (predetermined number of counts), the switching frequency of the power semiconductor element 2 is increased, the amount of generated heat is increased and the bonding member 4 is melted, and then the temperature of the power semiconductor element 2 is bonded again. It is possible to return the switching frequency of the power semiconductor element 2 to the switching frequency at the time of normal use until the count number indicating that the state below the melting point of the member 4 is continued exceeds the set value, and to solidify the joining member 4 again. It is.

以下では、図４および図５を用いて、パワー半導体モジュール１の製造方法の第一実施例および第二実施例について説明する。なお、図４および図５における絶縁材料５はエポキシ樹脂からなるものとする。   Below, the 1st Example of the manufacturing method of the power semiconductor module 1 and a 2nd Example are described using FIG. 4 and FIG. 4 and 5, the insulating material 5 is made of an epoxy resin.

図４に示すパワー半導体モジュール１の製造方法の第一実施例、および、図５に示すパワー半導体モジュール１の製造方法の第二実施例は、いずれも、接合部材４によりパワー半導体素子２と金属板３とを導通可能に接合する第一の工程と、絶縁部材５により接合部材４の表面においてパワー半導体素子２および金属板３のいずれにも接していない部分４ａを被覆するとともに、パワー半導体素子２と金属板３とを接合する第二の工程と、
を具備する。 The first embodiment of the method for manufacturing the power semiconductor module 1 shown in FIG. 4 and the second embodiment of the method for manufacturing the power semiconductor module 1 shown in FIG. A first step of joining the plate 3 so as to be conductive; and a portion 4a of the surface of the joining member 4 that is not in contact with either the power semiconductor element 2 or the metal plate 3 by the insulating member 5; 2nd process of joining 2 and metal plate 3,
It comprises.

図４に示すパワー半導体モジュール１の製造方法の第一実施例、および、図５に示すパワー半導体モジュール１の製造方法の第二実施例は、第一工程については略同様であり、シート状に形成された接合部材４をパワー半導体素子２と金属板３の間に挟んで炉に所定時間入れ、加熱した後冷却する。シート状の接合部材４は炉内で溶融し、その後凝固してパワー半導体素子２と金属板３とを導通可能に接合する。
このとき、炉の保持温度を、接合部材４の融点以上かつ素子動作許容温度以下とすることにより、パワー半導体素子２が壊れて所定の機能を果たさなくなることが無い。 The first embodiment of the method for manufacturing the power semiconductor module 1 shown in FIG. 4 and the second embodiment of the method for manufacturing the power semiconductor module 1 shown in FIG. The formed bonding member 4 is sandwiched between the power semiconductor element 2 and the metal plate 3 and placed in a furnace for a predetermined time, heated and then cooled. The sheet-like joining member 4 is melted in the furnace and then solidified to join the power semiconductor element 2 and the metal plate 3 so as to be conductive.
At this time, by setting the holding temperature of the furnace to be equal to or higher than the melting point of the bonding member 4 and equal to or lower than the element operation allowable temperature, the power semiconductor element 2 is not broken and does not perform a predetermined function.

図４に示すパワー半導体モジュール１の製造方法の第一実施例の第二工程においては、いわゆる「樹脂ポッティング」が行われる。すなわち、接合部材４の表面においてパワー半導体素子２および金属板３のいずれにも接していない部分４ａを被覆するように硬化前のエポキシ樹脂を塗布する。
このとき、塗布された硬化前のエポキシ樹脂は、パワー半導体素子２および金属板３のいずれにも接触し、硬化前のエポキシ樹脂と、パワー半導体素子２と金属板３とで囲まれた空間に接合部材４を封入する格好になっている。
続いて、硬化前のエポキシ樹脂を加熱した後冷却することによりエポキシ樹脂を硬化させ、絶縁部材５とする。硬化前のエポキシ樹脂を加熱する温度はエポキシ樹脂が硬化する温度以上かつ接合部材４の融点以下であり、接合部材４が溶融することが無く、パワー半導体素子２が壊れて所定の機能を果たさなくなることが無い。 In the second step of the first embodiment of the method for manufacturing the power semiconductor module 1 shown in FIG. 4, so-called “resin potting” is performed. That is, the epoxy resin before curing is applied so as to cover the portion 4 a that is not in contact with either the power semiconductor element 2 or the metal plate 3 on the surface of the bonding member 4.
At this time, the applied epoxy resin before curing contacts both the power semiconductor element 2 and the metal plate 3, and is in a space surrounded by the epoxy resin before curing, the power semiconductor element 2 and the metal plate 3. The joining member 4 is enclosed.
Subsequently, the epoxy resin before curing is heated and then cooled to cure the epoxy resin, whereby the insulating member 5 is obtained. The temperature at which the epoxy resin before curing is heated is not lower than the temperature at which the epoxy resin is cured and not higher than the melting point of the joining member 4, so that the joining member 4 is not melted and the power semiconductor element 2 is broken and does not perform a predetermined function. There is nothing.

図５に示すパワー半導体モジュール１の製造方法の第二実施例の第二工程においては、いわゆる「トランスファーモールド」により絶縁部材５が形成される。すなわち、接合部材４により接合されたパワー半導体素子２および金属板３を金型内に収容し、該金型内に硬化前のエポキシ樹脂を流し込み、該エポキシ樹脂を加熱してある程度硬化させた時点で金型から取り外し、再び加熱してから冷却することによりエポキシ樹脂を硬化させ、絶縁部材５とする。絶縁部材５は接合部材４の表面においてパワー半導体素子２および金属板３のいずれにも接していない部分を被覆するとともに、パワー半導体素子２と金属板３とを接合している。硬化前のエポキシ樹脂を加熱する温度はエポキシ樹脂が硬化する温度以上かつ接合部材４の融点以下であり、接合部材４が溶融することが無く、パワー半導体素子２が壊れて所定の機能を果たさなくなることが無い。   In the second step of the second embodiment of the method for manufacturing the power semiconductor module 1 shown in FIG. 5, the insulating member 5 is formed by so-called “transfer molding”. That is, when the power semiconductor element 2 and the metal plate 3 joined by the joining member 4 are accommodated in a mold, an epoxy resin before curing is poured into the mold, and the epoxy resin is heated and cured to some extent. Then, the epoxy resin is cured by removing from the mold, heating again, and cooling to obtain the insulating member 5. The insulating member 5 covers a portion of the surface of the bonding member 4 that is not in contact with either the power semiconductor element 2 or the metal plate 3 and bonds the power semiconductor element 2 and the metal plate 3 together. The temperature at which the epoxy resin before curing is heated is not lower than the temperature at which the epoxy resin is cured and not higher than the melting point of the joining member 4, so that the joining member 4 is not melted and the power semiconductor element 2 is broken and does not perform a predetermined function. There is nothing.

本発明に係るパワー半導体モジュールの実施の一形態を示す模式図。The schematic diagram which shows one Embodiment of the power semiconductor module which concerns on this invention. パワー半導体素子のスイッチング周波数と発熱量との関係を示す図。The figure which shows the relationship between the switching frequency of a power semiconductor element, and the emitted-heat amount. スイッチング周波数選択制御のフロー図。The flowchart of switching frequency selection control. 本発明に係るパワー半導体モジュールの製造方法の第一実施例を示す模式図。The schematic diagram which shows the 1st Example of the manufacturing method of the power semiconductor module which concerns on this invention. 本発明に係るパワー半導体モジュールの製造方法の第二実施例を示す模式図。The schematic diagram which shows the 2nd Example of the manufacturing method of the power semiconductor module which concerns on this invention.

符号の説明Explanation of symbols

１ パワー半導体モジュール
２ パワー半導体素子
３ 金属板
４ 接合部材 DESCRIPTION OF SYMBOLS 1 Power semiconductor module 2 Power semiconductor element 3 Metal plate 4 Joining member

Claims (8)

パワー半導体素子と、
電極を形成する金属板と、
融点が該パワー半導体素子の素子動作許容温度よりも低く、該パワー半導体素子と該金属板とを導通可能に接合する接合部材と、
を具備する、ことを特徴とするパワー半導体モジュール。 A power semiconductor element;
A metal plate forming an electrode;
A melting member having a melting point lower than an element operation allowable temperature of the power semiconductor element, and a joining member that joins the power semiconductor element and the metal plate in a conductive manner;
A power semiconductor module comprising: 前記接合部材の融点は前記パワー半導体素子の定格動作温度よりも高い、ことを特徴とする請求項１に記載のパワー半導体モジュール。   The power semiconductor module according to claim 1, wherein a melting point of the joining member is higher than a rated operating temperature of the power semiconductor element. 前記接合部材は、
５２Ｉｎ−４８Ｓｎ合金、５０Ｂｉ−２８Ｐｂ−２２Ｓｎ合金、４０Ｂｉ−４０Ｐｂ−１１．５Ｓｎ−８．５Ｃｄ合金、４７．７Ｂｉ−３３．２Ｐｂ−１８．８Ｓｎ−０．３Ｓｂ合金のうちのいずれかの合金、または、これらと同様または近似の合金からなる、ことを特徴とする請求項１または請求項２に記載のパワー半導体モジュール。 The joining member is
52In-48Sn alloy, 50Bi-28Pb-22Sn alloy, 40Bi-40Pb-11.5Sn-8.5Cd alloy, 47.7Bi-33.2Pb-18.8Sn-0.3Sb alloy, or The power semiconductor module according to claim 1, wherein the power semiconductor module is made of an alloy similar to or similar to these. 前記接合部材の表面において、前記パワー半導体素子および前記金属板のいずれにも接していない部分を被覆し、かつ、該パワー半導体素子と該金属板とを接合する絶縁部材を具備する、ことを特徴とする請求項１から請求項３までのいずれか一項に記載のパワー半導体モジュール。   An insulating member that covers a portion of the surface of the joining member that is not in contact with either the power semiconductor element or the metal plate and that joins the power semiconductor element and the metal plate is provided. The power semiconductor module according to any one of claims 1 to 3. 前記絶縁部材は、ガラス転移点が前記接合部材の融点よりも高い熱硬化性樹脂からなる、ことを特徴とする請求項４に記載のパワー半導体モジュール。   The power semiconductor module according to claim 4, wherein the insulating member is made of a thermosetting resin having a glass transition point higher than a melting point of the bonding member. 前記接合部材を融点以上の温度に加熱する加熱手段を具備する、ことを特徴とする請求項１から請求項５までのいずれか一項に記載のパワー半導体モジュール。   The power semiconductor module according to claim 1, further comprising a heating unit that heats the bonding member to a temperature equal to or higher than a melting point. 前記パワー半導体素子が前記加熱手段を兼ね、該パワー半導体素子のスイッチング周波数を変えることにより該パワー半導体素子の温度を上昇させる、ことを特徴とする請求項６に記載のパワー半導体モジュール。   The power semiconductor module according to claim 6, wherein the power semiconductor element also serves as the heating unit, and the temperature of the power semiconductor element is increased by changing a switching frequency of the power semiconductor element. 接合部材によりパワー半導体素子と電極を形成する金属板とを導通可能に接合する第一の工程と、
絶縁部材により該接合部材の表面において該パワー半導体素子および該金属板のいずれにも接していない部分を被覆するとともに、該パワー半導体素子と該金属板とを接合する第二の工程と、
を具備することを特徴とするパワー半導体モジュールの製造方法。 A first step of joining the power semiconductor element and the metal plate forming the electrode by a joining member so as to be conductive;
Covering a portion of the surface of the bonding member that is not in contact with either the power semiconductor element or the metal plate with an insulating member, and a second step of bonding the power semiconductor element and the metal plate;
The manufacturing method of the power semiconductor module characterized by comprising.
JP2004255687A 2004-09-02 2004-09-02 Power semiconductor module and manufacturing method thereof Pending JP2006073810A (en)

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DE112008000743B4 (en) * 2007-03-22 2013-12-24 Toyota Jidosha Kabushiki Kaisha Power module and inverter for vehicles
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CN111373526A (en) * 2017-11-28 2020-07-03 三菱电机株式会社 System and method for allowing restoration of interconnections of die of power supply module
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CN111373529B (en) * 2017-11-28 2023-12-05 三菱电机株式会社 System for allowing recovery of interconnects of dies of a power module

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