JP2005203570A - Semiconductor module - Google Patents

Abstract

A semiconductor module excellent in heat dissipation and electromagnetic noise shielding is provided.
A semiconductor module (100) according to the present invention includes a power circuit unit (1) including a wiring board (11) on which a semiconductor element (12) serving as a heat source is mounted, and a semiconductor element side of the power circuit unit. Thermally conductive injecting material (4) that conducts heat that is injected and that is generated in the power circuit section, and electromagnetic shielding member that is embedded in the thermally conductive injecting material apart from the semiconductor element and absorbs heat from the thermally conductive injecting material A heat absorbing member (3) that also serves as a heat sink, and a heat radiating body (7) that is connected to the heat absorbing member and radiates heat received from the heat absorbing member to the outside. Since heat is transferred from the heat conductive injecting material to both surfaces of the heat absorbing member, a large amount of heat is conducted from the heat absorbing member to the heat radiating member and efficiently radiated. Further, since the heat absorbing member also serves as an electromagnetic shielding member, an electromagnetic noise shielding effect is also obtained.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor module in which heat dissipation of a power circuit unit including a semiconductor element (power MOSFET, IGBT, etc.) is improved. The present invention also relates to a semiconductor module that can improve heat dissipation and improve reliability by reducing electromagnetic noise.

  Since semiconductor elements such as power MOSFETs and IGBTs are elements that control a large current, they generate a large amount of heat. For example, in the case of a semiconductor module used in an inverter circuit or the like of an inverter device, a large current of several tens to several hundreds A flows through the semiconductor element, and the semiconductor element is accompanied by a considerably large heat generation. Moreover, there is a demand for miniaturization and high integration of semiconductor modules, and it is becoming difficult to ensure sufficient heat dissipation with conventional structures.

  Therefore, various semiconductor modules having improved heat dissipation from the semiconductor elements in order to ensure the operation of the semiconductor elements and increase the reliability of the semiconductor modules are disclosed in, for example, the following Patent Documents 1 to 4. .

  In the semiconductor module disclosed in Patent Document 1, a wiring board is bonded to both electrode surfaces of a semiconductor element, both the wiring boards are thermally connected by a heat conductor made of a metal column or the like, and heat generation of the semiconductor element is performed on both sides. So that heat can be efficiently dissipated. A similar structure is also described in Patent Document 2.

  Patent Document 3 discloses a semiconductor module in which a power circuit portion and a control circuit portion are partially connected with a high thermal conductive resin. However, Patent Document 3 only describes that heat is radiated from the control circuit unit to the power circuit unit via the high thermal conductive resin. In addition, since a control circuit unit connected to another radiator is not disclosed, a heat dissipation path from the power circuit unit to the control circuit unit is not configured. Therefore, even if the semiconductor module of patent document 3 can improve the heat dissipation from the shunt resistor, the wire, etc. in the power circuit section, it does not improve the heat dissipation from the semiconductor element itself which is the most heat generating source. Can not.

  Patent Document 4 discloses a module in which an electronic component that is a heat source and a metal case are connected by a high thermal conductive resin, and heat generated by the electronic component is transmitted to the metal case to dissipate heat. However, since the high thermal conductive resin is only in contact with a part of the inner wall surface of the metal case, it cannot be a path for sufficiently transmitting the heat generated by the electronic component.

  In addition, when a large current flowing through the semiconductor element is switched or the like, electromagnetic noise is generated, and the electromagnetic noise causes malfunction of the control circuit unit. As a countermeasure, Patent Document 5 discloses providing a metal member that absorbs or shields electromagnetic noise. However, Patent Document 5 merely focuses on the suppression of electromagnetic noise, and does not disclose any measures for improving the heat dissipation of the semiconductor element.

Japanese Patent Laid-Open No. 2002-164485 JP-A-10-56131 Japanese Patent Laid-Open No. 2003-243609 JP-A-8-167680 JP-A-8-293578

  This invention is made | formed in view of such a situation, and it aims at providing the semiconductor module which can further improve the heat dissipation of the electric power circuit part provided with a semiconductor element.

  As a result of extensive research and trial and error to solve the above problems, the present inventor has come up with the idea that the heat generated by the semiconductor element is dissipated through the thermally conductive injecting material and the heat absorbing member, thereby completing the present invention. .

  That is, the semiconductor module according to the present invention includes a power circuit unit including a semiconductor element serving as a heat generation source and a wiring substrate having a main wiring pattern to which the semiconductor element is bonded, and the power circuit unit in contact with the power circuit unit. A thermally conductive injecting material that conducts the generated heat, a heat absorbing member that is at least partially embedded in the thermally conductive injecting material apart from the power circuit portion, and absorbs heat from the thermally conductive injecting material, And a heat radiator that is at least thermally connected to the heat absorbing member and radiates heat received from the heat absorbing member to the outside.

  In the case of the semiconductor module of the present invention, heat generated in the semiconductor element or the like of the power circuit unit is transmitted to the heat conductive injection material, and is thermally conducted in the heat conductive injection material. The heat received by the thermally conductive injecting material is absorbed by the heat absorbing member embedded therein, and the heat received by the heat absorbing member is transferred to the heat radiating body connected thereto and radiated from the heat radiating body to the outside. The

  As a result, for example, a semiconductor element (or wiring board) separate from a conventional heat dissipation path (main heat dissipation path) that is directed from the main wiring pattern (wiring pattern to which the semiconductor element is bonded) side of the wiring board to the opposite surface side. ) → thermally conductive injecting material → heat absorbing member → heat radiator, a new heat radiation path (sub-heat radiation path) is formed. Conversely, when a heat sink or the like is in direct contact with the semiconductor element, the semiconductor element (or wiring board) is separated from the conventional heat dissipation path (main heat dissipation path) from the semiconductor element toward the heat sink. A new heat radiation path (sub-heat radiation path) is formed: main wiring pattern → thermally conductive injecting material → heat absorbing member → heat radiator. In any case, the heat generated in the power circuit portion (especially the semiconductor element) can be dissipated through the sub heat dissipation path.

  Here, in the case of the present invention, heat transfer from the heat conductive injecting material to the heat absorbing member is not performed only from the contact surface on the power circuit portion side (main surface side). Since the heat absorbing member of the present invention is embedded in the heat conductive injecting material, the heat absorbing member receives heat from the heat conductive injecting material at a plurality of contact surfaces (at least two surfaces) in contact with the heat conductive injecting material. Therefore, as the contact area between the heat-absorbing member and the heat-conductive injecting material is increased, the heat transfer from the heat-conductive injecting material to the heat-absorbing member is improved, and more heat flows to the heat-absorbing member, Heat is effectively radiated from the radiator. Thus, in the case of the present invention, in addition to newly providing a heat dissipation path, the heat dissipation performance of the heat dissipation path is improved.

  As described above, in order to efficiently dissipate heat generated from the semiconductor element, it is preferable that a plurality of heat dissipation paths exist. Therefore, the power circuit unit includes a heat sink that is bonded to a surface that is not in contact with the thermally conductive injection material, and the heat sink is at least thermally connected to the heat radiator or at least a part of the heat radiator. Is preferable.

  Here, when the heat sink is thermally connected to the radiator, heat input to the heat sink is radiated from the radiator. On the other hand, when the heat sink constitutes a part or all of the heat radiating body, at least a part of the heat input to the heat sink is directly radiated from the heat sink to the outside.

The heat absorption by the heat absorbing member is made from a thermally conductive injecting material that is in contact with the respective surfaces on both the main surface side facing the power circuit portion and the sub-surface side opposite to the main surface side. Here, the heat input to the heat conductive injecting material on the sub surface side does not have to be conducted directly from the heat conductive injecting material on the main surface side. There may be heat input from the heat conductive injecting material on the main surface side to the heat conductive injecting material on the sub surface side through another heat conductive member (for example, a metal column, a housing) or the like. However, direct heat conduction from the heat conductive injecting material on the main surface side to the heat conductive injecting material on the sub surface side can efficiently absorb heat generated by the semiconductor element to the heat absorbing member. . Therefore, the heat absorbing member has a communication portion that communicates a main surface side facing the power circuit portion and a sub surface side that is the opposite surface side of the main surface, and through this communication portion, the main surface of the heat absorbing member. It is preferable that heat conduction is performed from the heat conductive injection material on the side to the heat conductive injection material on the sub surface side.
In this case, the heat conductive injecting material on the main surface side and the heat conductive injecting material on the sub surface side become a continuous body through the communicating portion, and heat generated by the semiconductor element is efficiently transmitted to the heat absorbing member.

  By the way, in a power circuit part, electromagnetic noise is generated by switching a large current flowing through a semiconductor element. When this electromagnetic noise is propagated to a control circuit unit that controls a power circuit unit (particularly, a semiconductor element), the control circuit unit may cause an inversion of the output and malfunction. Therefore, it is preferable to provide an electromagnetic shielding member capable of absorbing or shielding such electromagnetic noise between the power circuit unit and the control circuit unit. Moreover, it is more preferable to use the heat absorbing member of the present invention as the electromagnetic shielding member.

  That is, the semiconductor module of the present invention includes a control circuit unit provided separately from the power circuit unit, and the heat absorbing member is disposed at least between the control circuit unit and the power circuit unit, and is generated in the power circuit unit. It is preferable that the electromagnetic shielding member suppresses propagation of electromagnetic noise to the control circuit unit.

  Further, it is more preferable that this electromagnetic shielding member together with the heat radiator forms a shielding space that surrounds the power circuit portion and suppresses leakage of electromagnetic noise from the power circuit portion to the control circuit portion. This is because by confining the power circuit section in the shielding space, electromagnetic noise such as leakage, detour or diffraction can be more effectively prevented from being propagated to the control circuit section. Although the shielding space is preferably a sealed space, a sufficient shielding effect can be obtained even if the control circuit unit is provided close to the electromagnetic shielding member.

  The material of such a heat absorbing member or electromagnetic shielding member is not limited, but the heat absorbing member is preferably excellent in thermal conductivity from the viewpoint of improving heat dissipation. It may be made of ceramics such as SiC, but if it is made of metal, it is excellent in terms of cost, workability or formability. Moreover, if it is metal, it can fully function as an electromagnetic shielding member simultaneously. The metal material may be a magnetic material such as iron (Fe) or nickel (Ni), or a nonmagnetic material (paramagnetic material) such as aluminum (Al) or copper (Cu). Specifically, pure Al, Al alloy, Cu alloy such as pure Cu and brass, pure Fe, mild steel and the like may be used. The same applies not only to the heat absorbing member but also to the heat radiator. However, it is not necessary that the heat absorbing member and the radiator are the same material. Of course, if there is a material other than a metal that simultaneously satisfies thermal conductivity and electromagnetic shielding properties, it may be used.

  Here, the electromagnetic shielding member is preferably grounded (that is, grounded). Thereby, the electric potential of an electromagnetic shielding member is stabilized and the suppression effect of electromagnetic noise becomes high. Moreover, if the heat radiator that forms the shielding space together with the electromagnetic shielding member is also electrically connected, the effect of suppressing electromagnetic noise is similarly increased.

  Furthermore, if the housing of the semiconductor module is used as a heat radiator as referred to in the present invention, both reduction in the number of parts and improvement in heat dissipation can be achieved. In addition, if a cooling fin etc. are formed in the whole surface or a part of outer surface of a heat radiator or a housing | casing, and the surface area is expanded, heat dissipation can be improved more.

  As a means for newly providing a heat dissipation path, there is one as described in Patent Document 1 or 2 described above. However, in the conventional semiconductor module, in order to provide the heat dissipation path, the semiconductor element has to be face-down or reversely mounted, which is not always an easy method to employ. On the other hand, the semiconductor module of the present invention employs a heat conductive injection material in a part of the heat dissipation path, like the conventional semiconductor module, and therefore employs wire bonding or the like when mounting the semiconductor element. The degree of freedom in designing a semiconductor module is also great. Therefore, in the present invention, it is also possible to use a semiconductor element provided with at least one electrode to be wire-bonded on the non-joint surface side that is not joined to the main wiring pattern.

  The thermally conductive injecting material may be in the form of a gel or hardened after injection, but the higher the thermal conductivity, the better. For example, there are various resins, gels, greases and the like excellent in thermal conductivity. Specifically, silicon gel (thermal conductivity of 0.2 W / m · K or more), high thermal conductivity gel (manufactured by GELTEC, thermal conductivity: 6.15 W / m · K), high heat dissipation gel TSE3081 (manufactured by GE Toshiba Silicone) , Thermal conductivity: 1.26 W / m · K), high heat dissipation gel SE4445CV (manufactured by Toray Dow Corning, thermal conductivity: 1.26 W / m · K), grease G765 (manufactured by Shin-Etsu Chemical, thermal conductivity: 2 .9 W / m · K), epoxy resin KE-870 (manufactured by Toshiba Chemical Co., Ltd., thermal conductivity: 3.4 W / m · K), and the like.

  The type of semiconductor element, allowable current, etc. are not concerned. For example, power elements such as MOSFETs, IGBTs, and diodes that perform switching and amplification are typical. The control circuit unit is typically a drive circuit that drives the power circuit unit, but may be composed of a separate control circuit independent of the power circuit unit.

  The wiring board is preferably excellent in thermal conductivity. The type of metal base substrate, ceramic substrate, etc. is not limited. In the case of a metal base substrate, an aluminum base substrate or the like is typical. A wiring layer such as a main wiring pattern is provided on the insulating layer formed on the surface of the metal base. Furthermore, a metal base substrate is preferable because it is relatively inexpensive and has a high shielding effect against electromagnetic noise. In the case of a ceramic substrate, a copper-clad ceramic substrate such as a DBC substrate is typical. Wiring layers such as Cu and Al are provided on both surfaces of a ceramic substrate having excellent thermal conductivity such as silicon carbide, aluminum nitride and silicon nitride. Of course, the wiring board is not limited to the above, and may be a board made of a composite material such as metal and ceramics, or a board made of a composite material such as metal and Invar alloy.

  The shape of the heat absorbing member (or electromagnetic shielding member) is not limited. Although it is common to make it flat plate shape parallel to the wiring board of a power circuit part, the surface area may be expanded by providing unevenness and fins on the surface. By enlarging the surface area, heat transfer from the heat conductive injecting material to the heat absorbing member can be improved, and the heat dissipation can be further improved. Moreover, it becomes possible to function as a heat sink by providing an appropriate thickness to the heat absorbing member. Further, the endothermic member may be a net shape, a honeycomb shape, a porous shape, or the like. The surface area through which heat is transferred can be adjusted by changing the mesh, honeycomb roughness, porous pore diameter, and the like. When the heat absorbing member is an electromagnetic shielding member, it is preferable that the mesh or the hole diameter is small in order to suppress leakage of electromagnetic noise to the control circuit unit.

  The communication part does not simply mean a hole. It suffices if the main surface side and the sub surface side of the power circuit portion are connected by the heat conductive injection material. For example, it may be connected at the end of the heat absorbing member.

  The connection between the heat absorbing member and the heat radiating member may be soldering, welding or the like in addition to screwing. If the radiator is a bottomed container (concave shape) and the electromagnetic shielding member (heat absorbing member) is a lid, an electromagnetic noise shielding space is easily formed. This heat radiating body may be integrated or divided. You may utilize the heat sink mentioned above for some heat radiators. Use of a housing as such a heat radiating body is advantageous in that the number of parts can be reduced.

  The present invention will be described in more detail with reference to embodiments of the invention. It should be noted that which form shown in the present specification is the best depends on the object, required performance, and the like.

  FIG. 1 shows a cross-sectional view of a main part of a semiconductor module 100 according to an embodiment of the present invention. This semiconductor module 100 is used in an inverter device for drive control of a three-phase induction motor (three-phase motor). FIG. 1 shows the half phase.

  The semiconductor module 100 includes a power circuit unit 1, a control circuit unit 2, an endothermic conductor 3, a silicon gel 4, a heat sink 5, a frame body 6, and a housing (heat radiator) 7.

  The power circuit unit 1 includes a DBC (Direct Bond Copper) substrate 11 and a semiconductor element 12 mounted thereon. The DBC substrate 11 is obtained by directly bonding a copper plate to both surfaces of the ceramic substrate 110. By this copper plate, a first wiring pattern 111 (main wiring pattern) and a second wiring pattern 112 are formed on the upper surface of the ceramic substrate 110 (upper and lower are based on FIG. 1 and so on). A third wiring pattern 113 is formed. The semiconductor element 12 is an IGBT (Insulated Gate Bipolar Transistor) as a power switching element. An upper surface (non-joint surface) has an emitter electrode (not shown) as a main electrode and a gate electrode (not shown) as a control electrode, and a collector electrode (not shown) as a main electrode is provided on the lower surface. The emitter electrode is connected to the second relay terminal 86 by a wire 82, a second wiring pattern 112, and a wire 83. The collector electrode is soldered to the first wiring pattern 111. The collector electrode is connected to the first relay terminal 85 by the first wiring pattern 111 and the wire 81. In FIG. 1, only one wire is shown, but normally there are a plurality of wires, and the type and number of wires are adjusted according to the amount of current flowing. Although not shown, the gate electrode is connected to the control circuit unit 2 (solder bonding or the like) by a wire and a third relay terminal.

  The control circuit unit 2 includes various electronic elements mounted on a printed wiring board, and includes a drive circuit that drives the semiconductor element 12 and a protection circuit that protects the semiconductor element 12. A gate signal or the like for driving the semiconductor element 12 is output from the drive circuit to the power circuit unit 1.

  The heat-absorbing conductor 3 includes a rectangular flat plate portion 31 (heat-absorbing member) and a rectangular annular connecting portion 32 extending in the shape of a bowl in the outer periphery. The endothermic conductor 3 of the present embodiment is an integrally formed product of an aluminum plate, but may be one obtained by joining or combining divided parts. The flat plate portion 31 is formed with a plurality of communication holes (communication portions) 33 in the outer peripheral portion, the central portion, or the like. A first relay terminal 85, a second relay terminal 86, and the like are inserted through a part of the communication hole 33. The endothermic conductor 3 corresponds to the endothermic member of the present invention.

  The silicon gel 4 has a higher thermal conductivity than a general insulating sealant. Specifically, high thermal conductive gel (GELTEC, thermal conductivity: 6.15 W / m · K), high heat dissipation gel TSE3081 (GE Toshiba Silicone, thermal conductivity: 1.26 W / m · K), high heat dissipation Gel SE4445CV (manufactured by Toray Dow Corning, thermal conductivity: 1.26 W / m · K). The silicon gel 4 is injected from the communication hole 33 of the endothermic conductor 3. After the lower surface side (main surface side) of the flat plate portion 31 is filled, the upper surface side (sub surface side) of the flat plate portion 31 is filled. Thus, the endothermic conductor 3 is buried with the silicon gel 4.

  The frame 6 is made of resin and is a square annular member having a stepped cross section. A first relay terminal 85, a second relay terminal 86, and the like are insert-molded inside the frame 6, and the heat-absorbing conductor 3 and the control circuit unit 2 are respectively screwed (not shown) in the upper end opening. It is fixed by.

  The casing 7 is a concave container made of an aluminum alloy casting. The endothermic conductor 3 is fixed to the upper end of the opening of the housing 7 with a screw 71 at the connecting portion 32. A heat sink 5 made of ceramic or metal (Cu or CuMo) or the like is fixed to the upper surface of the inner bottom of the housing 7. The third wiring pattern of the DBC substrate 11 is soldered to the center of the upper surface of the heat sink 5, and the frame 6 is fixed to the outer peripheral side of the heat sink 5.

  The endothermic conductor 3 and the housing 7 are connected not only thermally but also electrically. And since the housing | casing 7 is earth | grounded, the electric potential of the heat absorption conductor 3 connected to it is also stable.

  Next, heat dissipation and electromagnetic noise shielding properties of the semiconductor module 100 will be described. In the case of the semiconductor module 100 of the present embodiment, the heat generated by the semiconductor element 12 is first transmitted from the first wiring pattern 111 on the lower surface side to the heat sink 5 and the casing 7 through the ceramic substrate 110 and the third wiring pattern 113, Heat is radiated from the body 7 to the outside. This becomes the main heat dissipation path of the semiconductor module 100.

  Next, the upper surfaces of the semiconductor element 12 and the DBC substrate 11 are filled with silicon gel 4. Therefore, the heat generated by the semiconductor element 12 is transmitted to the silicon gel 4 through the upper surface and the upper surface of the DBC substrate 11. The silicon gel 4 radiates the heat to the endothermic conductor 3. Here, since the flat plate portion 31 of the endothermic conductor 3 is embedded in the silicon gel 4, heat is input from the silicon gel 4 to the upper and lower surfaces of the flat plate portion 31. Accordingly, the heat generated by the semiconductor element 12 and the like is efficiently transmitted to the flat plate portion 31 via the silicon gel 4, and the heat absorbing conductor 3 guides more heat to the housing 7, and the housing 7 generates more heat. Is dissipated. This is a sub heat dissipation path of the semiconductor module 100. In this way, the semiconductor module 100 can efficiently dissipate the heat generated by the semiconductor element 12 through the main heat dissipation path and the sub heat dissipation path.

  In addition, at the beginning of the operation of the semiconductor module 100, it is expected that the silicon gel 4 on the lower surface side of the flat plate portion 31 becomes hotter than the upper surface side. However, after a lapse of a considerable time, the temperature gradient is substantially eliminated on the upper surface side and the lower surface side of the flat plate portion 31, and it is considered that the heat input from the silicon gel 4 to the upper surface of the flat plate portion 31 also increases.

  By the way, the power circuit unit 1 of the semiconductor module 100 of this embodiment is in a state of being housed in the shielding space S that is almost completely sealed by the housing 7 and the heat absorbing conductor 3 (electromagnetic shielding member). For this reason, electromagnetic noise generated from the power circuit unit 1 with the operation of the semiconductor element 12 is absorbed by the metal body composed of the heat absorbing conductor 3 and the housing 7, and leakage to the outside is suppressed. As a result, the control circuit unit 2 does not receive the propagation of the electromagnetic noise, and malfunction is prevented.

  Further, the endothermic conductor 3 of the present embodiment has a wide area in contact with the silicon gel 4 on the upper surface side of the flat plate portion 31 because the connecting portion 32 has a saddle shape in cross section. As a result, heat is transferred more efficiently.

  As described above, in the semiconductor module 100 of the present embodiment, excellent heat dissipation and electromagnetic noise shielding are ensured while having a simple structure.

It is sectional drawing which shows embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power circuit part 11 DBC board | substrate 12 Semiconductor element 2 Control circuit part 3 Endothermic conductor (endothermic member)
31 Flat plate part 32 Connection part 33 Communication hole (communication part)
4 Silicon gel (thermally conductive injection material)
5 Heatsink 6 Frame 7 Case (Heat Dissipator)
100 Semiconductor module S Shielded space

Claims (8)

A power circuit unit comprising a semiconductor element serving as a heat generation source and a wiring board having a main wiring pattern to which the semiconductor element is joined;
A thermally conductive injecting material that contacts the power circuit portion and conducts heat generated in the power circuit portion;
A heat absorbing member that is at least partially embedded in the thermally conductive injecting material apart from the power circuit portion and absorbs heat from the thermally conductive injecting material;
A heat radiator that is at least thermally connected to the heat absorbing member and radiates heat received from the heat absorbing member to the outside;
A semiconductor module comprising: The heat absorbing member has a communication portion that communicates a main surface side facing the power circuit portion and a sub surface side that is the opposite surface side of the main surface side,
2. The semiconductor module according to claim 1, wherein the semiconductor module is thermally conducted through the communication portion from the heat conductive injection material on the main surface side of the heat absorbing member to the heat conductive injection material on the sub surface side. Furthermore, a control circuit unit provided separately from the power circuit unit is provided,
The heat absorbing member is an electromagnetic shielding member that is disposed at least between the control circuit unit and the power circuit unit and suppresses electromagnetic noise generated in the power circuit unit from being propagated to the control circuit unit. The semiconductor module according to claim 1. 4. The semiconductor module according to claim 3, wherein the electromagnetic shielding member and the heat radiator form a shielding space that surrounds the power circuit unit and suppresses leakage of electromagnetic noise from the power circuit unit to the control circuit unit. 5. .   The semiconductor module according to claim 3, wherein the electromagnetic shielding member is grounded.   The semiconductor module according to claim 1, wherein the semiconductor element includes at least one electrode to be wire-bonded on a non-joint surface side that is not joined to the main wiring pattern.   The semiconductor module according to claim 1, wherein the heat radiator is a housing. The power circuit unit includes a heat sink that is bonded to a surface that is not in contact with the thermally conductive injection material,
The semiconductor module according to claim 1, wherein the heat sink is at least thermally connected to the heat radiating body or constitutes at least a part of the heat radiating body.

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