JP5397340B2 - Semiconductor cooling device - Google Patents

Description

  The present invention relates to a semiconductor cooling device in which a semiconductor element and a heat storage material are mounted on an electrode portion.

  Conventionally, for example, Patent Document 1 proposes a power conversion device in which a metal substrate and an insulating substrate are sequentially stacked on a cooler, and a semiconductor element is provided on the insulating substrate via an electrode.

  In this power converter, the heat accumulator is provided on the semiconductor element or on the insulating substrate around the semiconductor element. The heat accumulator temporarily absorbs the heat of the semiconductor element by the phase change from solid to liquid at a temperature slightly lower than the usable upper limit temperature of the semiconductor element, and the absorbed heat is thereafter To be released.

  As described above, since the heat storage device is provided in the power conversion device, when the semiconductor element generates heat and the temperature rapidly increases, the heat of the semiconductor element is transferred to the heat storage device on the semiconductor element or the heat storage device around the semiconductor element. Since it is temporarily absorbed, a rapid temperature rise of the semiconductor element is suppressed.

JP 2002-270765 A

  However, in the above conventional technique, the heat accumulator provided around the semiconductor element is disposed on the insulating substrate having a lower thermal conductivity than the metal, so that the heat of the semiconductor element is transferred to the heat accumulator around the semiconductor element. There was a problem that it was difficult to conduct. In addition, when a transient temperature rise that suddenly becomes high in a short time occurs in a semiconductor element, heat cannot be absorbed by only the regenerator above the semiconductor element, and heat is also conducted to the regenerator around the semiconductor element. Therefore, the operation limit temperature of the semiconductor element is easily reached.

  Further, when the semiconductor element is downsized or when the current flowing through the semiconductor element is increased, the heat generation density of the semiconductor element increases. For this reason, when a transient temperature rise occurs in the semiconductor element as described above, the semiconductor element easily reaches the operating limit temperature before the heat of the semiconductor element is conducted to the regenerator.

  In JP 2008-227342 A, a semiconductor element and a heat accumulator are provided on a metal electrode, and the heat accumulator and the electrode are made of the same material is proposed. This reduces the thermal resistance of the bonding interface between the electrode and the heat accumulator, but there is a limit to the thermal conductivity of the metal, so when the heat generation density of the semiconductor element increases as described above, the transient of the semiconductor element There is a problem that the heat cannot be smoothly conducted to the regenerator and the semiconductor element fails due to the transient temperature rise.

  An object of this invention is to provide the semiconductor cooling device which can conduct the transient heat which generate | occur | produces in a semiconductor element to a thermal storage material efficiently in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, an electrode portion (55) that abuts the semiconductor element (51) on one surface (55a) and is electrically connected to the semiconductor element (51), and one surface A cooler (10) provided on the other surface (55b) side of the electrode part (55) different from (55a) and cooling the semiconductor element (51) via the electrode part (55). The cooling device is characterized by the following.

  That is, the electrode part (55) is a heat diffusion plate that diffuses heat from the semiconductor element (51) by heat conduction, and among heat conduction, heat conduction in a first direction parallel to the surface direction of one surface (55a). , And a first thermal conductivity and a second thermal conductivity respectively defining heat conduction in the second direction from one surface (55a) to the other surface (55b). The heat diffusion plate is configured such that the first and second thermal conductivities are larger than any thermal conductivities that respectively define the heat conductance in directions other than the first and second directions. Features.

  According to this, when a transient heat generation occurs in the semiconductor element (51), the heat is transferred from the semiconductor element (51) to the heat diffusion plate and is also thermally diffused along the first and second directions which are high heat conduction directions. Since the heat is conducted through the plate, the transient heat of the semiconductor element (51) can be efficiently released from the semiconductor element (51) to the heat diffusion plate. For this reason, it is possible to prevent the semiconductor element (51) from easily reaching the operation limit temperature due to transient heat.

  And like invention of Claim 2, a heat | fever diffusion plate can be comprised so that a 1st direction may cross | intersect the direction along the maximum width of the contact surface with a semiconductor element (51). .

  In this case, as in the third aspect of the invention, the thermal diffusion plate can be configured such that the angle formed by the intersecting directions is a right angle. According to this, since the width of the heat diffusion plate that conducts heat in the first direction is maximized on one surface (55a) of the electrode portion (55), the heat of the semiconductor element (51) is efficiently conducted to the heat diffusion plate. can do.

Moreover, in invention of Claim 1 , it is comprised with the 1 or 2 or more heat storage material with respect to one semiconductor element (51) in the one surface in the thermal-diffusion plate as an electrode part ( 55 ), The heat absorption part (56) which absorbs the heat | fever from a semiconductor element (51) through a thermal diffusion board is arrange | positioned, It is characterized by the above-mentioned.

  According to this, since heat is conducted from the semiconductor element (51) to the heat absorption part (56) through the heat diffusion plate, the transient heat of the semiconductor element (51) is efficiently released to the heat absorption part (56). Can do. For this reason, it is possible to prevent the semiconductor element (51) from easily reaching the operation limit temperature due to transient heat.

Further, characterized in that in the invention according to claim 1, the heat absorbing section (56), which from the contact position of the semiconductor element (51) in one surface of the heat diffusion plate disposed on an extension line along the first direction And Thereby, the heat conducted to the heat diffusion plate is conducted along the first direction, so that the heat can be efficiently absorbed by the heat absorbing portion (56).

Furthermore, in the invention according to claim 1 , the heat absorption part (56) has a maximum width in a direction perpendicular to the first direction in the surface occupied by the heat absorption part (56) with respect to one surface of the heat diffusion plate. And the semiconductor element (51) are configured to be larger than the maximum width in the direction orthogonal to the first direction.

  According to this, since at least the heat absorption part (56) is located over the entire width in which heat is conducted from the semiconductor element (51) in the first direction, the heat released from the semiconductor element (51) is efficiently absorbed. Can be absorbed.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing of the semiconductor cooling device which concerns on 1st Embodiment of this invention. It is an AA arrow line view of FIG. It is the figure which showed melting | fusing point-latent heat map of the latent heat storage material. It is the figure which showed the characteristic of erythritol. It is the figure which showed the manufacturing method of the graphite thermal diffusion plate. It is a schematic diagram of the heat | fever path | route which conducts a graphite thermal diffusion plate. It is a top view of the electrode part which concerns on 2nd Embodiment of this invention. It is the figure which showed the manufacturing method of the graphite thermal diffusion plate shown by FIG. It is a top view of the electrode part which concerns on 3rd Embodiment of this invention. It is the figure which showed the manufacturing method of the graphite thermal diffusion plate shown by FIG. In other embodiment, it is the figure which showed the variation of arrangement | positioning with a semiconductor element and a thermal storage material. It is sectional drawing of the semiconductor cooling device which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The semiconductor cooling device shown below is applied to a power conversion device such as an inverter device, for example.

  FIG. 1 is a cross-sectional view of the semiconductor cooling device according to the present embodiment. Moreover, FIG. 2 is an AA arrow view of FIG.

  As shown in FIG. 1, the semiconductor cooling device includes a first cooler 10, a second cooler 20, a first insulating part 30, a second insulating part 40, and a semiconductor module 50. .

  The first cooler 10 and the second cooler 20 cool each semiconductor element 51. The first cooler 10 and the second cooler 20 are provided with a passage therein, and for example, water flows as a refrigerant in the passage. The first cooler 10 and the second cooler 20 are disposed at a predetermined interval, and the semiconductor module 50 is disposed between the first cooler 10 and the second cooler 20.

  The first insulating unit 30 and the second insulating unit 40 are insulating sheets for insulating the coolers 10 and 20 from the semiconductor module 50. The first insulating unit 30 is disposed on the first cooler 10 and plays a role of insulating the first cooler 10 and the semiconductor module 50. On the other hand, the second insulating unit 40 is disposed on the second cooler 20 and plays a role of insulating the second cooler 20 and the semiconductor module 50.

  As such a first insulating part 30 and a second insulating part 40, those having both high thermal conductivity and insulation, such as a ceramic substrate, a sheet in which an epoxy resin is mixed with a ceramic filler, and an alumina sprayed film, are used.

  The semiconductor module 50 is a semiconductor mounting body in which a plurality of semiconductor elements 51 are sealed with a sealing material 52. In addition to the semiconductor element 51 and the sealing material 52, the semiconductor module 50 includes an electrode portion 55 including a metal substrate 53 and a graphite heat diffusion plate 54, a plurality of heat absorbing portions 56, a plurality of spacers 57 and 58, and the above electrode portions. Metal substrates 59a and 59b other than 55 and a plurality of graphite heat diffusion plates 60 and 61 are provided.

  The electrode portion 55 is a plate-like electrode member having one surface 55a and another surface 55b different from the one surface 55a, and having both roles of electric conduction and heat conduction. In the present embodiment, the electrode portion 55 is configured by laminating a graphite heat diffusion plate 54 on a metal substrate 53. Therefore, the surface of the graphite heat diffusion plate 54 opposite to the metal substrate 53 corresponds to one surface 55 a of the electrode portion 55, and the surface of the metal substrate 53 opposite to the graphite heat diffusion plate 54 is the electrode portion 55. It corresponds to the other surface 55b. The electrode portion 55 is in contact with the semiconductor element 51 on one surface 55 a and is electrically connected to the semiconductor element 51. The first cooler 10 is provided on the other surface 55 b side of the electrode portion 55.

  The metal substrate 53 is exposed from the sealing material 52 and is disposed on the first insulating part 30. Such a metal substrate 53 is formed of copper (Cu), aluminum (Al), or the like so that it can function as a wiring and also as a heat spreader.

  The graphite heat diffusion plate 54 electrically connects the semiconductor element 51 and the metal substrate 53 to heat conduction for conducting (diffusing) the heat generated in the semiconductor element 51 to the heat absorbing portion 56 and the first cooler 10. It is a member that has both the role of electrical conduction. By using a graphite material having a thermal conductivity of 1700 to 2000 W / mK, the heat conduction to the heat absorbing portion 56 is faster than when a metal is used.

  In the present embodiment, the graphite heat diffusion plate 54 has one direction parallel to the surface direction of the one surface 55a of the electrode portion 55 and the thickness direction from the semiconductor element 51 to the first cooler 10 in one direction and the thickness direction. Is a high heat conduction direction with higher thermal conductivity than different directions. In other words, the graphite heat diffusion plate 54 defines heat conduction in one direction parallel to the surface direction of the one surface 55a of the electrode portion 55 and heat conduction in the thickness direction from the one surface 55a of the electrode portion 55 to the other surface 55b. The first thermal conductivity and the second thermal conductivity are provided. That is, the graphite heat diffusing plate 54 conducts heat in two directions at a high temperature so that the first and second heat conductivities are larger than any of the heat conductivities that define heat conductance in directions other than the one direction and the thickness direction. It is configured. In addition, the thickness direction should just be a direction which goes to the 1st cooler 10 from the semiconductor element 51, and is a direction perpendicular | vertical to the one surface 55a of the electrode part 55 in this embodiment.

  Originally, the graphite material has a characteristic of high thermal conductivity in the x direction and the y direction perpendicular to the x direction, for example, based on the crystal structure, but has a characteristic that heat is hardly conducted in the z direction. Therefore, a graphite sheet simply formed of graphite is less likely to conduct heat in the thickness direction of the sheet even if it has good heat conduction in two directions parallel to the surface of the sheet. The graphite heat diffusion plate 54 according to the present embodiment is not a graphite material itself but a new heat diffusion plate manufactured using a graphite material. A method for manufacturing the graphite thermal diffusion plate 54 will be described in detail later.

  Note that the metal substrate 53 is not essential for the configuration of the electrode portion 55, and the electrode portion 55 may be composed of only the graphite heat diffusion plate 54.

  The semiconductor element 51 is a semiconductor chip on which elements such as IGBTs, power MOS transistors, and diode elements are formed. The semiconductor element 51 is formed with a pad such as a gate and an electrode, and is electrically connected to the outside via a bonding wire (not shown). Further, the semiconductor element 51 is soldered to one surface 55 a of the electrode portion 55 and is electrically connected to the electrode portion 55. Note that a lead (not shown) is electrically connected to the semiconductor element 51.

  The heat absorption part 56 plays a role of temporarily absorbing heat from the semiconductor element 51 via the graphite heat diffusion plate 54, and is disposed on one surface 55 a of the graphite heat diffusion plate 54 with respect to one semiconductor element 51. It is composed of one or more heat storage materials. The heat absorbing portion 56 is disposed on one surface 55 a of the electrode portion 55, that is, on the graphite heat diffusion plate 54. In the present embodiment, as shown in FIG. 2, the heat absorbing portion 56 is disposed next to the semiconductor element 51.

  As described above, the graphite heat diffusing plate 54 has a high heat conduction direction in the surface direction of the one surface 55a of the electrode portion 55. Therefore, the heat absorbing portion 56 is at least a semiconductor of the one surface 55a of the electrode portion 55. It arrange | positions on the extended line of one direction from the arrangement | positioning location (contact position) of the element 51. FIG. As a result, the heat generated in the semiconductor element 51 is conducted to the graphite thermal diffusion plate 54 and conducted to the heat absorbing portion 56 along one direction which is a high thermal conduction direction.

  As the heat absorption part 56, a latent heat storage material using latent heat that causes a phase change from solid to liquid or from liquid to gas is used. Furthermore, the heat absorption part 56 is preferably a latent heat storage material having a melting point lower than the operation limit temperature of the semiconductor element 51.

  There are many types of latent heat storage materials. FIG. 3 is a diagram showing a melting point-latent heat map of the latent heat storage material. The horizontal axis shows the melting point (Melting point), and the vertical axis shows the latent heat. Since the operation limit temperature of the semiconductor element 51 is 150 ° C., for example, erythritol having the melting point closest to 150 ° C. and the highest latent heat among the latent heat storage materials having a melting point of 150 ° C. or less can be used as the latent heat storage material. Therefore, the heat absorption part 56 is comprised as what contained the erythritol in the metal container, for example.

  As shown in FIG. 4, since erythritol has a large heat of fusion of 502.904 J / cc, a large amount of heat is required to change the phase from a solid to a liquid. Can be absorbed. Of course, in the design of the semiconductor module 50, the latent heat storage material shown in FIG. Further, a metal plate such as Cu may be adopted as the heat absorbing portion 56.

  The spacers 57 and 58 are members provided on the semiconductor element 51. Specifically, the spacers 57 and 58 function as a heat sink that receives the heat of the semiconductor element 51 and releases the heat to the graphite heat diffusion plates 60 and 61 on the spacers 57 and 58, and the semiconductor element 51 and the metal substrates 59 a and 59 b. It serves as a wiring for electrically connecting the two.

  A graphite heat diffusion plate 60 is joined on the spacer 57, and a graphite heat diffusion plate 61 is joined on the spacer 58. These graphite heat diffusion plates 60 and 61 also have a high heat conduction direction in one direction and the thickness direction as described above. Further, a heat absorbing portion 56 is provided on the surface of the graphite heat diffusion plates 60 and 61 on the electrode portion 55 side. In the present embodiment, one direction is parallel to one side of the rectangular semiconductor element 51.

  Since the spacers 57 and 58 are joined to the graphite heat diffusion plates 60 and 61, each heat absorption part 56 provided on each graphite heat diffusion plate 60 and 61 is at least one from the place where the spacers 57 and 58 are arranged. It is arranged on the extension line of each direction.

  The metal substrates 59 a and 59 b are the same as the metal substrate 53. In this embodiment, the metal substrate 59a is integrated with the graphite heat diffusion plate 60 to form an electrode portion, and the metal substrate 59b is integrated with the graphite heat diffusion plate 60 to form an electrode portion.

  The sealing material 52 makes the appearance of the semiconductor module 50. The sealing material 52 is formed on each of the metal substrates 53 and 59 and the semiconductor element 51 so that the surface of the metal substrates 53 and 59 opposite to the surface to which the graphite heat diffusion plates 54, 60 and 61 are bonded is exposed. The graphite heat diffusion plates 54, 60, 61, the heat absorbing portion 56, and the spacers 57, 58 are sealed. As such a sealing material 52, for example, a thermosetting resin such as an epoxy resin is used.

  A semiconductor cooling device is obtained by sandwiching the semiconductor module 50 having such a configuration between the coolers 10 and 20. That is, the first insulating unit 30 is stacked between the first cooler 10 and the first metal substrate 53, and the second insulating unit 40 is stacked so as to be sandwiched between the second cooler 20 and the metal substrate 59. ing. The above is the overall configuration of the semiconductor cooling device according to the present embodiment.

  Next, a manufacturing method of the graphite heat diffusion plates 54, 60, 61 having a high heat conduction direction in one direction parallel to the surface direction of the one surface 55a of the electrode portion 55 and in the thickness direction perpendicular to the one surface 55a of the electrode portion 55 will This will be described with reference to FIG.

  Hydrocarbon is thermally decomposed in a high-temperature heating furnace, and high-purity graphite crystals grown in a vapor phase on a high-temperature substrate at the atomic level are stacked as shown in FIG. Looking at only one layer, it is a graphite sheet having high heat conduction directions in the x and y directions. This graphite sheet is laminated high in the z direction to form a laminate 70.

  The stacked body 70 has high heat conduction directions in the x and y directions on the xy plane, but the z direction is not a high heat conduction direction due to the crystal structure. And if the laminated body 70 is cut | disconnected in parallel to a yz surface, the board whose cut surface will be a yz surface is obtained. That is, the plate has a high heat conduction direction in the y direction and the z direction. This plate is the graphite thermal diffusion plate 54, 60, 61. Therefore, the y direction of the laminate 70 is one direction of the graphite heat diffusion plates 54, 60, 61, and the x direction is the thickness direction.

  In the above description, the stacked body 70 is cut in parallel to the yz plane, but the stacked body 70 may be cut in parallel to the xz plane. In this case, the x direction of the laminate 70 is one direction of the graphite heat diffusion plates 54, 60, 61, and the y direction is the thickness direction.

  The graphite heat diffusion plate 54 obtained as described above is joined to the metal substrate 53 by soldering or a conductive adhesive to form the electrode portion 55. Similarly, the graphite heat diffusion plates 60 and 61 are bonded to the metal substrates 53 and 59.

  Next, a conduction path of heat generated in the semiconductor element 51 in the semiconductor cooling device will be described with reference to FIG. 6A corresponds to the AA arrow view of FIG. 1, and FIG. 6B is a cross-sectional view of the semiconductor cooling device on the AA arrow side. In FIG. 6, the sealing material 52 is omitted.

  As described above, the high heat conduction direction of the graphite thermal diffusion plate 54 constituting the electrode portion 55 is one direction in the surface direction of the one surface 55a of the electrode portion 55 as shown in FIGS. 6 (a) and 6 (b). And the thickness direction of the electrode portion 55.

  Then, when heat is generated in the semiconductor element 51, the heat is conducted to the graphite heat diffusion plate 54 and spreads in one direction in the graphite heat diffusion plate 60 as shown in FIG. 6 (a). As shown in FIG. 4, the heat is conducted in the thickness direction and discharged to the first cooler 10. In this case, the heat conducted through the graphite heat diffusion plate 54 is also temporarily absorbed by the heat absorption part 56. The heat temporarily absorbed by the heat absorption part 56 is conducted again to the graphite heat diffusion plate 54 and conducted in the thickness direction of the graphite heat diffusion plate 54, and is released to the first cooler 10. Thus, heat is conducted to the graphite heat diffusion plate 54.

  In addition, since the spacers 57 and 58 are joined to the semiconductor element 51, the heat generated in the semiconductor element 51 is conducted to the graphite heat diffusion plates 60 and 61 via the spacers 57 and 58, and spreads in one direction. Conducted in the direction is also discharged to the second cooler 20.

  Then, when the semiconductor element 51 is overloaded, the temperature of the semiconductor element 51 rises instantaneously. When such transient heat is generated in the semiconductor element 51, heat is conducted only in one direction in the surface direction of the one surface 55a of the electrode portion 55 in the graphite heat diffusion plate 54. It efficiently conducts along one direction to the heat absorption part 56 located on the extension line of the element 51.

  Of course, the heat conducted to the graphite heat diffusion plates 60 and 61 through the spacers 57 and 58 bonded to the semiconductor element 51 is bonded to the graphite heat diffusion plates 60 and 61 along one direction of the graphite heat diffusion plates 60 and 61. The heat absorption part 56 is also efficiently discharged.

  As described above, the transient heat generated in the semiconductor element 51 is temporarily absorbed by the heat absorption part 56 joined to the graphite heat diffusion plates 54, 60, 61, so that the semiconductor element 51 exceeds the operating limit temperature. It will not become inoperable. The heat absorbed by the heat absorption unit 56 is discharged to the first cooler 10 and the second cooler 20 over time as described above.

  As described above, in the present embodiment, high heat is better in heat conduction than the other directions in one direction parallel to the surface direction of the one surface 55a of the electrode portion 55 and in the thickness direction perpendicular to the one surface 55a of the electrode portion 55. The graphite heat diffusion plate 54 having a conduction direction is used as the electrode portion 55.

  Thereby, even if transient heat generation occurs in the semiconductor element 51, heat is conducted from the semiconductor element 51 to the graphite heat diffusion plates 54, 60, 61 and to the heat absorbing portion 56 along one direction which is a high heat conduction direction. Since the heat can be conducted, the transient heat of the semiconductor element 51 can be efficiently released to the heat absorbing portion 56. For this reason, it is possible to prevent the semiconductor element 51 from easily reaching the operation limit temperature due to transient heat.

  In particular, when the semiconductor element 51 is downsized or when the current passed through the semiconductor element 51 is increased, the heat generation density of the semiconductor element 51 increases. As described above, the semiconductor element 51 passes through the graphite heat diffusion plate 54. Since heat can be efficiently conducted to the heat absorption part 56, the semiconductor element 51 does not easily reach the operation limit temperature before the heat of the semiconductor element 51 is conducted to the heat absorption part 56.

  Regarding the correspondence between the description of the present embodiment and the description of the scope of claims, the graphite heat diffusion plate 54 of the electrode portion 55 corresponds to the “thermal diffusion plate” of the scope of claims. The first cooler 10 corresponds to a “cooler” in the claims. Furthermore, one direction corresponds to the “first direction” in the claims, and the thickness direction corresponds to the “second direction” in the claims.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. FIG. 7 is a plan view of the electrode unit 55 according to the present embodiment. In the present embodiment, the graphite heat diffusion plate 54 is configured such that one direction intersects the direction along the maximum width of the contact surface with the semiconductor element 51. In particular, as shown in FIGS. 7A and 7B, one direction which is the heat conduction direction of the graphite thermal diffusion plate 54 according to the present embodiment is relative to the direction along the maximum width of the semiconductor element 51. Is vertical. In other words, the graphite heat diffusing plate 54 is configured such that an angle formed by a direction along which the direction along the maximum width of the contact surface of the semiconductor element 51 with the graphite heat diffusing plate 54 intersects one direction is a right angle. Has been.

  As a specific example of this, as shown in FIG. 7A, when the long side of the graphite thermal diffusion plate 54 and one side of the semiconductor element 51 are arranged in parallel or at right angles, the high heat conduction direction is obtained. Some have the direction inclined with respect to the long side of the graphite thermal diffusion plate 54. Further, as shown in FIG. 7B, when the long side of the graphite heat diffusion plate 54 and one direction which is a high heat conduction direction are parallel, one side of the semiconductor element 51 is the long side of the graphite heat diffusion plate 54. Some are tilted against.

  The width of the heat absorption part 56 is the same as the maximum width of the semiconductor element 51, and the heat absorption part 56 is arranged on an extension line in one direction from the place where the semiconductor element 51 is arranged. That is, in the graphite heat diffusing plate 54, the heat absorbing portion 56 is arranged so that one direction which is a high heat conduction direction is oriented in a direction in which the heat transfer area from the semiconductor element 51 to the heat absorbing portion 56 can be increased.

  As indicated by the hatched portion (region where two lines intersect) in FIG. 7, the planar shape of the heat absorbing portion 56 is along the outer shape of the semiconductor element 51 and the outer shape of the electrode portion 55. Moreover, the heat absorption part 56 has the shape extended in one direction which is a high heat conduction direction. For this reason, the heat conducted in one direction, which is a high heat conduction direction, can be absorbed by the heat absorbing portion 56 extending in one direction.

  Next, a method for manufacturing the graphite thermal diffusion plate 54 shown in FIG. 7A will be described with reference to FIG. As shown in the first embodiment, a graphite laminate 70 is formed, and this laminate 70 is cut parallel to the yz plane. In the plate thus obtained, one direction which is a high heat conduction direction is the y direction. Accordingly, a new plate is cut out by inclining this one direction at a predetermined angle with respect to the y direction, whereby a graphite thermal diffusion plate 54 with one direction facing the predetermined direction is obtained.

  Note that the graphite thermal diffusion plate 54 shown in FIG. 7B can be manufactured by the method shown in FIG. 5 shown in the first embodiment.

  As described above, by arranging one direction which is a high heat conduction direction perpendicular to an arbitrary direction along the maximum width of the semiconductor element 51, the width of the semiconductor element 51 to conduct heat in one direction is maximized. Become. Therefore, the heat of the semiconductor element 51 can be efficiently conducted to the heat absorption part 56.

(Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. In each of the above embodiments, the one direction that is the high heat conduction direction of the graphite heat diffusing plate 54 faces the same direction everywhere on one surface 55a of the electrode portion 55, but in this embodiment, the semiconductor element 51 is the center. The feature is that the high heat conduction directions are oriented radially.

  FIG. 9 is a plan view of the electrode unit 55 according to the present embodiment. As shown in this figure, the semiconductor cooling device according to the present embodiment has a first cooling from the semiconductor element 51 and the radiation direction centered on the semiconductor element 51 in the surface direction of the one surface 55a of the electrode part 55 as the electrode part 55. A graphite thermal diffusion plate 54 is used in which the thickness direction toward the vessel 10 is a high thermal conductivity direction having a higher thermal conductivity than the radial direction and the direction different from the thickness direction.

  Further, the heat absorption part 56 is disposed around the semiconductor element 51 so as to surround the semiconductor element 51. That is, the endothermic part 56 has a donut-shaped planar shape, and the semiconductor element 51 is disposed in the donut-shaped window.

  In this embodiment, spacers 57 and 58 are bonded to the semiconductor element 51, and the spacers 57 and 58 are bonded to the upper graphite thermal diffusion plates 60 and 61.

  Next, a method for manufacturing the graphite thermal diffusion plate 54 according to this embodiment will be described with reference to FIG. As shown in FIG. 5, a graphite laminate 70 is formed, and this laminate 70 is cut parallel to the yz plane (or xz plane).

  And the board cut | disconnected from the laminated body 70 is cut out to a triangular prism shape as FIG. 10 (a) shows. As a result, as shown in FIG. 10B, a plurality of triangular prism parts are obtained. One triangular prism part has a high heat conduction direction in one direction and the thickness direction.

  Subsequently, as shown in FIG. 10C, a plurality of triangular prism parts are combined and bonded. After that, by cutting out an arbitrary quadrangular shape centering on the center where the triangular prism parts are combined, as shown in FIG. As a result, a graphite heat diffusion plate 54 in which the conduction direction is oriented is obtained.

  As described above, the heat conduction direction of the graphite heat diffusion plate 54 in the surface direction of the one surface 55a of the electrode portion 55 is made radial, and the heat transfer area to the heat absorption portion 56 is widened to increase the heat capacity of the heat absorption portion 56. it can. In addition, since the heat of the semiconductor element 51 is diffused radially, there is also an advantage that the temperature distribution of the graphite heat diffusion plate 54 is difficult.

  In the present embodiment, the heat absorption part 56 surrounds the semiconductor element 51. However, the block-like heat absorption part 56 may be disposed at least on the extended line in the radial direction from the position where the semiconductor element 51 is disposed. Further, regarding the correspondence between the description of the present embodiment and the description of the claims, the radial direction corresponds to the “first direction” of the claims, and the thickness direction corresponds to the “second direction” of the claims. ".

(Other embodiments)
The configuration of the semiconductor cooling device described in each of the above embodiments is merely an example, and the present invention is not limited to the configuration described above, and other structures including the characteristics of the present invention may be employed. For example, the widths of the semiconductor element 51 and the heat absorption part 56 perpendicular to one direction which is a high heat conduction direction can be set as appropriate. Moreover, the structure of the electrode part 55 may be comprised only with the graphite thermal diffusion plate 54 as mentioned above. On the other hand, a thin metal substrate such as Cu may be laminated on the graphite heat diffusion plate 54. In this case, the semiconductor element 51 and the heat absorption part 56 are mounted on this thin metal substrate.

FIG. 11 is a diagram showing a variation of the arrangement of the semiconductor element 51 and the heat absorption part 56. In FIG. 11, the heat absorbing portion 56 is indicated by hatching.
As shown in FIG. 11A, in the graphite thermal diffusion plate 54 in which one direction is oriented in a direction perpendicular to the maximum width of the semiconductor element 51, heat absorption is performed around the semiconductor element 51 so as to surround the semiconductor element 51. The part 56 can be arranged. A heat transfer area from the semiconductor element 51 to the heat absorption unit 56 can be increased, and an amount of heat that can be absorbed by the heat absorption unit 56 can be secured.

  Further, as shown in FIG. 11B, when the semiconductor element 51 has a rectangular shape with a high aspect ratio, one direction can be oriented in a direction perpendicular to the long side of the semiconductor element 51. Further, the endothermic portion 56 has a width equal to or larger than the width of the semiconductor element 51 as viewed from one direction which is a high heat conduction direction. And when the semiconductor element 51 and the heat absorption part 56 are seen from one direction which is a high heat conduction direction, the heat absorption part 56 is one direction from the arrangement place of the semiconductor element 51 so that the semiconductor element 51 is included in the width of the heat absorption part 56. It is arranged on the extension line. As a result, the path width through which the heat from the semiconductor element 51 to the heat absorption part 56 does not narrow, so that the heat released from the semiconductor element 51 can be efficiently absorbed by the heat absorption part 56.

  Thus, the maximum width in the direction orthogonal to one direction on the surface occupied by the heat absorbing portion 56 with respect to one surface of the graphite heat diffusion plate 54 (that is, one surface 55a of the electrode portion 55) is the distance between the one surface 55a and the semiconductor element 51. The heat absorption part 56 can be configured to be larger than the maximum width of the contact surface in a direction orthogonal to one direction.

  The relationship in which the width of the heat absorbing portion 56 is equal to or larger than the width of the semiconductor element 51 is not limited to FIG. 11B, but is also illustrated in FIGS. 2, 7, 11A, 11C, and The same applies to what is shown in 11 (d). 2 and 7, the width of the semiconductor element 51 and the width of the heat absorbing portion 56 are the same.

  In addition, as shown in FIG. 11C, the semiconductor element 51 may be positioned at the center in the longitudinal direction of the electrode portion 55, and the heat absorbing portion 56 may be disposed so as to sandwich the semiconductor element 51. Thereby, since the heat absorption part 56 increases the part along one direction, the efficiency of heat absorption with respect to the heat conduction direction is improved.

  Then, as shown in FIG. 11D, the semiconductor element 51 may be positioned at the end of the electrode portion 55 in the longitudinal direction. Thereby, in the heat absorption part 56 joined to the graphite thermal diffusion plate 54, the width | variety of the heat absorption part 56 in one direction can be lengthened. For this reason, the heat conducted in one direction can be efficiently absorbed by the heat absorbing portion 56.

  The graphite heat diffusion plate 54 shown in FIG. 11 can also be applied to the graphite heat diffusion plates 60 and 61 to which the spacers 57 and 58 are joined.

  Further, in each of the above embodiments, the semiconductor cooling device has a structure in which the semiconductor module 50 is sandwiched between the coolers 10 and 20, but the semiconductor module 50 is only the first cooler 10 as shown in FIG. It can also be set as the structure cooled by. In this case, the semiconductor element 51 and the heat absorption part 56 are sealed with the sealing material 62. In this way, a so-called single-sided cooling structure can be obtained.

10 1st cooler 51 Semiconductor element 54 Graphite thermal diffusion plate (thermal diffusion plate)
55 Electrode part 55a One side of electrode part 55b Other side of electrode part 56 Heat absorption part

Claims (3)

An electrode portion (55) that is in contact with the semiconductor element (51) at one surface (55a) and electrically connected to the semiconductor element (51);
A cooler (10) which is provided on the other surface (55b) side of the electrode portion (55) different from the one surface (55a) and cools the semiconductor element (51) via the electrode portion (55); A semiconductor cooling device comprising:
The electrode part (55) is a heat diffusing plate that diffuses heat from the semiconductor element (51) by heat conduction. Of the heat conduction, the electrode part (55) has a first direction parallel to the surface direction of the one surface (55a). A first thermal conductivity and a second thermal conductivity respectively defining heat conduction and heat conduction in the second direction from the one surface (55a) to the other surface (55b);
The thermal diffusion plate is configured such that the first and second thermal conductivities are greater than any thermal conductivities that define thermal conductance in directions other than the first and second directions, respectively .
One surface of the heat diffusion plate as the electrode portion (55) is composed of one or two or more heat storage materials for one semiconductor element (51), and the heat diffusion plate is interposed through the heat diffusion plate. An endothermic part (56) that absorbs heat from the semiconductor element (51) is provided,
The heat absorption part (56) is disposed on an extension line along the first direction from the contact position of the semiconductor element (51) on one surface of the heat diffusion plate,
The heat absorption part (56) has a maximum width in a direction perpendicular to the first direction in the surface occupied by the heat absorption part (56) with respect to one surface of the thermal diffusion plate, and the one surface and the semiconductor element (51). The semiconductor cooling device is configured to be larger than a maximum width in a direction orthogonal to the first direction on the contact surface .   2. The semiconductor according to claim 1, wherein the heat diffusion plate is configured such that the first direction intersects a direction along a maximum width of a contact surface with the semiconductor element (51). Cooling system.   The semiconductor cooling device according to claim 2, wherein the heat diffusion plate is configured such that an angle formed between the intersecting directions is a right angle.

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