JP2012109451A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device capable of effectively accumulating heat generated by semiconductor elements in a latent heat storage material when the heating values of the semiconductor elements rapidly increase in a short time.SOLUTION: In insulating fluid 50 composed of EHD fluid in a case 10, microcapsules are dispersed. In each of the microcapsules, a latent heat storage material, which accumulates heat from semiconductor elements 20 as latent heat accompanied by a phase change, is enclosed. The forced convection flow of the insulating fluid 50 caused by applying a voltage between a needle electrode 81 and an annular electrode 82 interchanges the microcapsules near top surfaces 20b of the semiconductor elements 20.

Description

  The present invention relates to a semiconductor device including a semiconductor element cooling structure using a latent heat storage material.

  As a prior art, for example, there is a semiconductor device provided with a semiconductor element cooling structure disclosed in Patent Document 1 below. The semiconductor device includes a semiconductor element, a heat sink on which the semiconductor element is mounted, and a heat storage member including a latent heat storage material attached to the semiconductor element so as to be located on the opposite side of the heat sink with respect to the semiconductor element. The heat storage member is configured by filling the case with a latent heat storage material. With such a configuration, when the calorific value of the semiconductor element increases rapidly in a short time, the latent heat storage material of the heat storage member absorbs heat and suppresses the temperature increase of the semiconductor element.

JP 2008-193017 A

  However, the conventional semiconductor device has a problem that heat cannot be efficiently stored in the latent heat storage material when the heat generation amount of the semiconductor element increases rapidly in a short time. This is because the latent heat storage material has relatively low thermal conductivity, so the heat generated by the semiconductor element is transferred to the latent heat storage material near the semiconductor element in the case, but the latent heat storage material near the semiconductor element becomes a thermal resistance. This is because it is difficult to transmit to the entire latent heat storage material.

  The present invention has been made in view of the above points, and efficiently stores heat in a latent heat storage material of heat generated by a semiconductor element when the calorific value of the semiconductor element increases rapidly in a short time. An object of the present invention is to provide a semiconductor device capable of performing

In order to achieve the above object, in the invention described in claim 1,
A semiconductor element (20);
A casing (10) for housing the semiconductor element therein;
A heat sink (40) disposed on the first surface (20a) side which is one surface of the semiconductor element and dissipating heat generated by the semiconductor element to the outside of the casing;
An insulating fluid (50) filled in the casing so as to contact the second surface (20b) opposite to the first surface of the semiconductor element and capable of convection in the casing,
The insulating fluid is characterized in that microcapsules (55) enclosing a latent heat storage material (56) that stores heat received from the semiconductor element as latent heat accompanying phase change are dispersed.

  According to this, steady cooling of the semiconductor element (20) is performed by the heat sink (40), and when the calorific value of the semiconductor element increases rapidly in a short time, the microcapsules in the insulating fluid (50) ( 55) The latent heat storage material (56) enclosed in 55) undergoes a phase change and absorbs heat, thereby suppressing an increase in the temperature of the semiconductor element. Since the microcapsules are dispersed in the insulating fluid capable of convection, the microcapsules enclosing the latent heat storage material that has already been subjected to latent heat storage in accordance with the convection of the insulating fluid in the casing are used as the second microcapsules. A microcapsule enclosing a latent heat storage material that has not been subjected to latent heat storage yet can be supplied to the vicinity of the second surface of the semiconductor element while being away from the vicinity of the surface. Thus, by replacing the microcapsules enclosing the latent heat storage material in the vicinity of the second surface of the semiconductor element, it is possible to suppress the microcapsules enclosing the latent heat storage material that has already performed latent heat storage from becoming thermal resistance. Can do. Therefore, when the calorific value of the semiconductor element increases rapidly in a short time, the heat generated by the semiconductor element can be efficiently stored in the latent heat storage material.

  The invention described in claim 2 is characterized by comprising forced convection means (81, 82) for forcibly convection of the insulating fluid in the casing. According to this, the microcapsules enclosing the latent heat storage material are actively replaced in the vicinity of the second surface of the semiconductor element by forcibly convection the insulating fluid in the casing by the forced convection means (81, 82). be able to. Therefore, it is possible to reliably suppress the heat resistance of the microcapsules enclosing the latent heat storage material that has already been subjected to latent heat storage, and when the heat generation amount of the semiconductor element increases rapidly in a short time, the semiconductor It is possible to more efficiently store the heat generated by the element into the latent heat storage material.

  In the invention according to claim 3, the insulating fluid is a fluid exhibiting an electrohydrodynamic phenomenon, and the forced convection means is provided in the casing, and a voltage is applied to the insulating fluid to apply the electrohydrodynamic phenomenon. It is characterized by being a pair of electrodes (81, 82) for flowing an insulating fluid. According to this, the insulating fluid can be easily and forcibly convected in the casing by the electrohydrodynamic phenomenon only by applying a voltage between the pair of electrodes (81, 82).

  Here, the electrohydrodynamics (abbreviated as EHD) phenomenon is, for example, “Electrical Society of Japan, Institute of Electrical Engineers Technical Report (Part II) No. 56 (June 1977)” As described in “EHD Research Expert Committee, Kiwaki, et al.”, Charged particles are contained in a fluid that moves according to the laws of fluid dynamics, and an electric field that follows the laws of electrostatic fields is created. This refers to a phenomenon that occurs when a person moves according to the laws of mechanics.

  The invention according to claim 4 is characterized in that the insulating fluid is further added with a high thermal conductive filler (50a) having insulating properties and higher thermal conductivity than the insulating fluid. . According to this, the insulating fluid that receives the heat from the semiconductor element is enclosed in the microcapsules dispersed in the insulating fluid via the high thermal conductive filler (50a) having a higher thermal conductivity than the insulating fluid. Heat can be quickly transferred to the latent heat storage material. Therefore, heat storage of the heat generated by the semiconductor element to the latent heat storage material can be performed more efficiently.

  Further, the invention described in claim 5 is characterized by comprising a heat radiating means (60) for radiating the heat of the insulating fluid to the outside of the casing. According to this, the heat of the latent heat storage material in the microcapsules dispersed in the insulating fluid can be transmitted by the heat radiating means (60) through the insulating fluid and radiated to the outside of the casing by the heat radiating means. it can. Therefore, it is possible to easily recover the heat absorption capability by changing the phase of the latent heat storage material in the microcapsule in the direction opposite to that during heat absorption.

  The invention according to claim 6 further includes heat transfer promoting means (70) that protrudes from the second surface of the semiconductor element into the insulating fluid and promotes heat transfer from the semiconductor element to the insulating fluid. It is characterized by that. According to this, the heat transfer area is increased by the heat transfer promoting means (70), and heat transfer from the semiconductor element to the latent heat storage material enclosed in the microcapsules dispersed in the insulating fluid can be promoted. it can. Therefore, heat storage of the heat generated by the semiconductor element to the latent heat storage material can be performed more efficiently.

  Further, in the invention according to claim 7, a gel-like sealing member that covers the entire surface of the insulating fluid opposite to the side in contact with the semiconductor element and seals the insulating fluid inside the casing ( 51). According to this, the insulating fluid can be easily held in the casing by the gel-like sealing member (51) while accommodating the volume change accompanying the temperature change of the insulating fluid and the volume change accompanying the phase change of the latent heat storage material. can do.

  In the invention according to claim 8, the heat sink is the first heat sink (40), and is disposed on the second surface side of the semiconductor element, and dissipates heat generated by the semiconductor element from the second surface to the outside of the casing. The second heat sink (41) is provided. Thus, also in the semiconductor device that cools the semiconductor element from both sides by the first and second heat sinks (40, 41), the latent fluid is stored in the vicinity of the second surface of the semiconductor element by convection with the insulating fluid. By replacing the encapsulated microcapsules, it is possible to suppress the microcapsules enclosing the latent heat storage material that has already been subjected to latent heat storage from becoming thermal resistance. Thus, when the calorific value of the semiconductor element increases rapidly in a short time, the heat generated by the semiconductor element can be efficiently stored in the latent heat storage material.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is sectional drawing which shows schematic structure of the semiconductor device in 1st Embodiment to which this invention is applied. It is sectional drawing which shows typically the principal part structure of a semiconductor device. It is sectional drawing which shows schematic structure of the semiconductor device in 2nd Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device in 3rd Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device in 4th Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device in 5th Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device in other embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device in other embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device in other embodiment to which this invention is applied.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. In the case where only a part of the configuration is described in each embodiment, the other parts of the configuration are the same as those described previously. In addition to the combination of parts specifically described in each embodiment, the embodiments may be partially combined as long as the combination is not particularly troublesome.

(First embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a semiconductor device 1 according to a first embodiment to which the present invention is applied. FIG. 2 schematically illustrates a schematic configuration in an insulating fluid 50 that is a main part of the semiconductor device 1. FIG. A semiconductor device 1 according to the present embodiment constitutes a control circuit of a control device mounted on a vehicle, for example, and is, for example, a semiconductor element such as an IGBT element (insulated gate bipolar transistor element) or a diode element constituting a switching circuit. 20. The semiconductor device 1 shown in FIG. 1 illustrates a device in which two IGBT elements are connected in parallel, or an IGBT element and a diode are connected in parallel.

  As shown in FIG. 1, the semiconductor device 1 includes a case 10 made of resin, for example, which is a casing that houses a semiconductor element 20 therein. The case 10 has a substantially rectangular tube shape that is relatively low in height (relatively small in the vertical direction in the figure), and is made of metal (for example, copper or A flat heat sink 40 (made of an aluminum material) is provided.

  The semiconductor element 20 is mounted on the circuit board 30. The circuit board 30 includes an insulating substrate 31 made of, for example, an insulator (for example, ceramic) and a conductor pattern 32 made of, for example, a copper foil or a conductive paste fired body formed on the upper surface of the insulating substrate 31 in the figure. The lower surface 20a (corresponding to the first surface of the present invention) of the semiconductor element 20 is electrically connected to the conductor pattern 32 by soldering or the like.

  Thus, the circuit board 30 on which the semiconductor element 20 is mounted is disposed in the case 10 so that the non-mounting surface of the circuit board 30 contacts the heat sink 40 over the entire area. That is, the heat sink 40 is disposed on the lower surface 20a side, which is one surface of the semiconductor element 20, so that the heat generated by the semiconductor element 20 is received through the circuit board 30 and radiated to the outside of the case 10. It has become.

  The case 10 is insert-molded with a metal lead frame 11 (for example, made of copper or aluminum) having electrode terminals. Between the terminal portion on the inner side of the case 10 of the lead frame 11 and the upper surface 20 b of the semiconductor element 20, between the terminal portion on the inner side of the case 10 of the lead frame 11 and the conductor pattern 32 of the circuit board 30, etc. The circuit in the semiconductor device 1 is configured by being electrically connected by the bonding wire 12. A part of the lead frame 11 protrudes outward from the case 10 to form an external connection terminal 11a.

  The case 10 is filled with an insulating fluid 50 having electrical insulating properties. As is apparent from FIG. 1, the insulating fluid 50 covers the entire upper surface of the circuit board 30 on which the semiconductor element 20 is mounted, and the upper surface 20b opposite to the lower surface 20a of the semiconductor element 20 (in the present invention). The case 10 is filled so as to be in direct contact with the second surface. The insulating fluid 50 is filled so that all circuit components in the case 10 including the bonding wires 12 are buried (soaked).

  The insulating fluid 50 of the present embodiment is a so-called EHD fluid that exhibits an electrohydrodynamic phenomenon (EHD phenomenon). As the insulating fluid 50, for example, fluorinate, n-butyl dodecanoate, xylene, silicone oil, or the like can be used.

  On the circuit board 30 in the case 10, a pair of needle electrodes 81 and an annular electrode 82 are disposed. As shown in FIG. 1, the needle-like electrode 81 is disposed to face the annular electrode 82 in such a direction as to indicate the center of the annular electrode 82.

  Both the electrodes 81 and 82 are made of, for example, metal, the needle electrode 81 is electrically connected to the upper surface of the semiconductor element 20, and the annular electrode 82 is electrically connected to the conductor pattern 32. Thereby, when a voltage is applied to both surfaces of the semiconductor element 20, a potential difference is generated between the needle electrode 81 and the annular electrode 82.

  When there is a potential difference between the needle electrode 81 and the annular electrode 82, a voltage is applied to the insulating fluid 50 between the electrodes 81, 82, and the insulating fluid 50 made of EHD fluid has a relatively high flow rate due to the EHD phenomenon. Forms a so-called jet stream. Thereby, in the case 10, the insulating fluid 50 is forced to be convected.

  In FIG. 1, the flow of the insulating fluid 50 formed by the electrodes 81 and 82 is shown along the upper surface 20b of the semiconductor element 20, but the insulating fluid 50 in contact with the upper surface 20b of the semiconductor element 20 is switched. As long as it flows like this. For example, if the insulating fluid 50 flows so as to collide with the upper surface 20b of the semiconductor element 20 from the upper side to the lower side in the drawing, the insulating fluid 50 in contact with the upper surface 20b of the semiconductor element 20 is surely replaced.

  A pair of electrodes 81 and an annular electrode 82 that apply a voltage to the insulating fluid 50 and cause the insulating fluid 50 to flow by an electrohydrodynamic phenomenon correspond to forced convection means in the present embodiment.

  The electrode for applying a voltage to the insulating fluid 50 is not limited to the combination of the needle-like electrode 81 and the annular electrode 82, and any other shape can be used as long as the voltage can be applied to the insulating fluid 50. It doesn't matter. Further, as long as a voltage can be applied to the insulating fluid 50, the electrical connection portions of the electrodes 81 and 82 are not limited to the above-described positions.

  Moreover, the electrode which applies a voltage to the insulating fluid 50 should just be provided with at least one pair of electrodes, and may be a plurality of pairs of electrodes. Further, the number of electrodes forming the anode and the number of electrodes forming the cathode may be different.

  Although not shown in FIG. 1, as shown in FIG. 2, microcapsules 55 are dispersed in the insulating fluid 50. The microcapsule 55 is made of, for example, a resin such as a polyamide resin, has an electrical insulating property, and has a substantially spherical shape.

  Inside the microcapsule 55, a latent heat storage material 56 capable of storing heat received from the semiconductor element 20 as latent heat accompanying a phase change from a solid phase to a liquid phase is enclosed. As the latent heat storage material 56, for example, erythritol, xylitol, paraffin or the like can be employed.

  As shown in FIG. 1, the inside of the case 10 covers the entire upper surface of the insulating fluid 50, that is, the surface of the insulating fluid 50 opposite to the side in contact with the semiconductor element 20. A flexible gel-like sealing member 51 (corresponding to the gel-like sealing member of the present invention) for sealing 50 inside the case 10 is provided in layers. For the sealing member 51, for example, silicone gel can be used.

  In the above-described configuration, when the semiconductor element 20 is constantly generating heat with operation, the heat generated by the semiconductor element 20 is mainly radiated to the outside of the case 10 by the heat sink 40, and the semiconductor element 20 is cooled. . When the calorific value of the semiconductor element 20 rapidly increases in a short time, the latent heat storage material 56 in the microcapsule 55 dispersed in the insulating fluid 50 forcedly convected in the case 10 is solidified. The phase change from the phase to the liquid phase absorbs heat and suppresses the temperature rise of the semiconductor element 20.

  According to the semiconductor device 1 having the above-described configuration, the insulating fluid 50 made of the EHD fluid in the case 10 stores the heat received from the semiconductor element 20 as latent heat accompanying the phase change from the solid phase to the liquid phase. The microcapsules 55 enclosing the heat storage material 56 are dispersed. Then, the insulating fluid 50 is forcibly convected by the EHD phenomenon generated by applying a voltage between the needle electrode 81 and the annular electrode 82. Along with the forced convection of the insulating fluid 50, the microcapsule 55 enclosing the latent heat storage material 56 that has already stored latent heat is moved away from the vicinity of the upper surface 20b of the semiconductor element 20, and the latent heat that has not yet been stored. The microcapsule 55 enclosing the heat storage material 56 can be supplied to the vicinity of the upper surface 20 b of the semiconductor element 20.

  In this way, by actively replacing the microcapsule 55 enclosing the latent heat storage material 56 in the vicinity of the upper surface 20b of the semiconductor element 20, the microcapsule 56 enclosing the latent heat storage material 56 that has already performed latent heat storage becomes the thermal resistance. It can be suppressed. Therefore, when the calorific value of the semiconductor element 20 rapidly increases in a short time, the heat generated by the semiconductor element 20 can be efficiently stored in the latent heat storage material 56.

  Further, the entire upper surface of the insulating fluid 50 is covered with a gel-like sealing member 51 to seal the insulating fluid 50 in the case 10. Therefore, the insulating fluid 50 can be reliably held in the case 10 by the sealing member 51. Further, since the sealing member 51 is in a gel form, even if there is a volume change accompanying a temperature change of the insulating fluid 50 or a volume change accompanying a phase change of the latent heat storage material 56 in the microcapsule 55, these are bent and these It is possible to cope with the volume change, and the insulating fluid 50 can be stably held in the case 10.

(Second Embodiment)
Next, a second embodiment will be described based on FIG.

  The second embodiment is different from the first embodiment in that a heat radiating means for radiating the heat of the insulating fluid 50 to the outside of the case 10 is added. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 3, the semiconductor device of this embodiment includes a radiator 60 that is a radiator. The radiator 60 includes a heat pipe 61 extending in the vertical direction in the figure and a fin 62 thermally joined to the heat pipe 61. The heat pipe 61 is configured, for example, by enclosing water as a working fluid inside a copper pipe member closed at both ends.

  Although not shown in FIG. 3, the microcapsules 55 in which the latent heat storage material 56 is sealed are dispersed in the insulating fluid 50 as in the first embodiment.

  The illustrated lower end portion of the heat pipe 61 is located in the insulating fluid 50 in which the microcapsules 55 (see FIG. 2) are dispersed, and the illustrated upper end portion is located above the upper surface of the sealing member 51. For example, copper-made plate-like fins 62 are joined to a portion of the heat pipe 51 located in the insulating fluid 50 and a portion protruding upward from the sealing member 51.

  According to the semiconductor device of this embodiment, since the heat radiator 60 that radiates the heat of the insulating fluid 50 to the outside of the case 10 is provided, the latent heat storage material 56 (see FIG. 2) in the microcapsule 55 has. Heat is transferred to the radiator 60 through the insulating fluid 50 and the microcapsule 55 (mainly via the microcapsule 55 with respect to the microcapsule 55 that has touched the radiator 60) and radiated to the outside of the case 10. Can do. Therefore, the latent heat storage material 56 in the microcapsule 55 can be phase-changed from the liquid phase to the solid phase, contrary to the endothermic state, so that the heat absorption capability can be easily recovered.

  Moreover, since the heat radiator 60 has the fin 62 in each of the part located in the insulating fluid 50, and the part which protrudes upwards rather than the sealing member 51, the heat absorption and air from the insulating fluid 50 are carried out. Can be efficiently dissipated.

  Moreover, although the insulating fluid 50 has fluidity at all times, since the radiator 60 is supported by the sealing member 51, the position is not greatly displaced. The radiator 60 is not limited to that supported only by the sealing member 51, and may be attached to and supported by the case 10. The configuration of the heat radiating means is not limited to the configuration of the radiator 60 having the heat pipe 61, and the heat of the insulating fluid 50 (specifically, the heat of the latent heat storage material 56) is transferred to the outside of the case 10. Any material that can dissipate heat may be used.

  In the semiconductor device of this embodiment, the insulating fluid 50 in contact with the upper surface 20b of the semiconductor element 20 is surely replaced, and the insulating fluid 50 in contact with the fins 62 of the radiator 60 is surely replaced. It is preferable to convect the insulating fluid 50 in FIG.

(Third embodiment)
Next, a third embodiment will be described based on FIG.

  The third embodiment is different from the first embodiment described above in that heat transfer promotion means for promoting heat transfer from the semiconductor element 20 to the latent heat storage material 56 is added. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 4, the semiconductor device of this embodiment includes heat transfer fins 70 that are heat transfer promoting means. The heat transfer fins 70 are made of, for example, a copper material or an aluminum material, and a plurality of wall portions are erected upward from the flat plate portion extending along the upper surface 20b of the semiconductor element 20, and the cross-sectional shape is comb-like. There is no. In the heat transfer fin 70, the above-described flat plate portion is joined to a part of the upper surface 20b of the semiconductor element 20 by, for example, soldering.

  Although not shown in FIG. 4, the microcapsules 55 in which the latent heat storage material 56 is enclosed are dispersed in the insulating fluid 50 as in the first embodiment.

  According to the semiconductor device of the present embodiment, the heat transfer fins 70 that protrude from the upper surface 20 b of the semiconductor element 20 into the insulating fluid 50 are provided, and the contact area between the heat transfer fins 70 and the insulating fluid 50 is provided. Is larger than the bonding area between the upper surface 20 b of the semiconductor element 20 and the heat transfer fins 70. That is, by providing the heat transfer fins 70, the heat transfer area from the semiconductor element 20 to the insulating fluid 50 is increased, and the latent heat storage material 56 (in the microcapsule 55 dispersed in the insulating fluid 50 from the semiconductor element 20 ( Heat transfer to (see Fig. 2) can be promoted. Therefore, heat storage of the heat generated by the semiconductor element 20 to the latent heat storage material 56 can be performed more efficiently.

  The heat transfer accelerating means is not limited to the heat transfer fin 70 having the above-described configuration, and may be formed of a high heat conductive material having a higher thermal conductivity than the insulating fluid 50 and can increase the contact area with the insulating fluid 50. That's fine. For example, a metal heat transfer fin in which a plurality of needle-like portions project from the insulating fluid 50 may be used.

  In the semiconductor device of the present embodiment, the insulating fluid 50 in contact with the upper surface 20b of the semiconductor element 20 is reliably replaced, and the insulating fluid 50 in contact with the heat transfer fins 70 is reliably replaced in the case 10 so as to be insulated. It is preferable to convect the sex fluid 50.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG.

  The fourth embodiment is different from the first embodiment described above in that an insulating high thermal conductive filler is added to the insulating fluid 50. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, in the semiconductor device of this embodiment, a high thermal conductive filler 50 a having electrical insulation and higher thermal conductivity than the insulating fluid 50 is added to the insulating fluid 50. The high thermal conductive filler 50a is, for example, a ceramic filler made of aluminum nitride, boron nitride, silica, or the like, and preferably has a needle shape (thin wire shape) or a disk shape.

  In FIG. 5, the high thermal conductive filler 50a is shown relatively large so that it can be easily understood. For example, a ceramic filler having a relatively high aspect ratio with a diameter of about 1 μm and a length of about 100 μm can be used. It is preferable that the high thermal conductive filler 50 a is dispersed almost uniformly in the insulating fluid 50.

  Although not shown in FIG. 5, the microcapsules 55 in which the latent heat storage material 56 is enclosed are also dispersed in the insulating fluid 50 as in the first embodiment.

  According to the semiconductor device of the present embodiment, the insulating fluid 50 that has received heat from the semiconductor element 20 is dispersed in the insulating fluid 50 via the high thermal conductive filler 50 a having a higher thermal conductivity than the insulating fluid 50. Heat can be quickly transferred to the latent heat storage material 56 in the microcapsule 55. Therefore, heat stored in the latent heat storage material 56 by the heat generated by the semiconductor element 20 can be more efficiently performed. Further, since the high thermal conductive filler 50a has an insulating property, even if a high aspect ratio filler is used, the circuit of the semiconductor device will not be short-circuited.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to FIG.

  The fifth embodiment is an example in which the present invention is applied to a double-sided cooling type semiconductor device. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 6, the semiconductor device of this embodiment includes a heat sink 40 (corresponding to a first heat sink) disposed on the lower surface 20 a side of the semiconductor element 20 and a heat sink 41 (first electrode) disposed on the upper surface 20 b side of the semiconductor element 20. 2 equivalent to a heat sink).

  Each of the heat sinks 40 and 41 is, for example, a flat plate member made of copper, and the heat sink 40 is in direct contact with the lower surface 20 a of the semiconductor element 20. The heat sink 41 is in contact with the upper surface 20b of the semiconductor element 20 via, for example, a copper spacer 42. The spacer 42 is in direct contact with a part of the upper surface 20 b of the semiconductor element 20.

  As is apparent from FIG. 6, the semiconductor device of this embodiment does not have the circuit board 30 described in the first embodiment, and the heat sinks 40 and 41 and the spacer 42 have the same function as the conductor pattern. Have. Therefore, the external connection terminal 11a is electrically connected to the heat sinks 40 and 41.

  In the present embodiment, the needle electrode 81 is electrically connected to the heat sink 41, and the annular electrode 82 is electrically connected to the heat sink 40 to apply the voltage of the insulating fluid 50.

  Also in this embodiment, the electrode for applying a voltage to the insulating fluid 50 is not limited to the combination of the needle-like electrode 81 and the annular electrode 82, and any electrode that can apply a voltage to the insulating fluid 50 is used. Other shapes may be used. Further, as long as a voltage can be applied to the insulating fluid 50, the electrical connection portions of the electrodes 81 and 82 are not limited to the above-described positions.

  Moreover, the electrode which applies a voltage to the insulating fluid 50 should just be provided with at least one pair of electrodes, and may be a plurality of pairs of electrodes. Further, the number of electrodes forming the anode and the number of electrodes forming the cathode may be different.

  In the present embodiment, the case 10 is molded so as to seal the entire periphery between the outer peripheral edges of the pair of heat sinks 40 and 41 sandwiching the semiconductor element 20. The external connection terminal 11a described above is insert-molded in the case 10. A space surrounded by the pair of heat sinks 40 and 41 and the case 10 is filled with the insulating fluid 50.

  In order to fill the inner space with the insulating fluid 50, for example, the process of forming the case 10 includes a step of forming a state having an insulating fluid filling path, and a step of closing the filling path. Has steps.

  In addition, since the semiconductor device of this embodiment uses the heat sinks 40 and 41 as a part of the electrical conduction circuit, it is necessary to insulate the heat sinks 40 and 41 from the outside. Therefore, an insulating plate 43 made of, for example, a ceramic material having insulating properties and excellent thermal conductivity is provided so as to cover the entire outer surface in the stacking direction of the heat sinks 40 and 41.

  Although not shown in FIG. 6, as in the first embodiment, the microcapsules 55 in which the latent heat storage material 56 is enclosed are also dispersed in the insulating fluid 50.

  According to the semiconductor device of the present embodiment, the semiconductor element 20 includes the heat sink 40 that contacts the entire area of the lower surface 20a of the semiconductor element 20 and the heat sink 41 that contacts a part of the upper surface 20b of the semiconductor element 20 via the spacer 42. In the microcapsule 55 dispersed in the insulating fluid 50 in direct contact with the upper surface 20b of the semiconductor element 20 when the heat generation amount of the semiconductor element 20 suddenly increases in a short time. The latent heat storage material 56 can quickly absorb heat from the semiconductor element 20.

  Since the insulating fluid 50 is convected in the case 10, the latent heat storage that has already performed latent heat storage is performed by actively replacing the microcapsules 55 enclosing the latent heat storage material 56 in the vicinity of the upper surface 20 b of the semiconductor element 20. It can suppress that the microcapsule 56 which enclosed the material 56 becomes thermal resistance. In this way, even in a double-sided cooling type semiconductor device, when the amount of heat generated by the semiconductor element 20 suddenly increases in a short time, the heat generated by the semiconductor element 20 is efficiently stored in the latent heat storage material 56. Can be done.

  Further, since the insulating fluid 50 is convected in the case 10, the microcapsule 56 enclosing the latent heat storage material 56 that has already stored latent heat is brought close to or collided with the heat sinks 40 and 41, and the microcapsule 55. It is possible to dissipate the heat of the inner latent heat storage material 56 to the outside of the case 10 and restore the heat absorption capability.

  Therefore, in the semiconductor device according to the present embodiment, the insulating fluid 50 in contact with the upper surface 20b of the semiconductor element 20 is reliably replaced, and the insulating fluid 50 in contact with the heat sinks 40 and 41 is reliably replaced in the case 10. It is preferable to convect the sex fluid 50.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the first to fourth embodiments, the insulating fluid 50 is sealed with the gel-like sealing member 51. However, the present invention is not limited to this. For example, as shown in FIG. It can be abolished. When the semiconductor device is mounted on a vehicle and used, such as when vibration is applied or the mounting posture is inclined, it is preferable to seal with a gel-like sealing member 51, but when used stationary It is also possible not to use the sealing member 51. In addition, even when the vehicle is mounted, the upper end opening of the case 10 can be closed with a cover member or the like without using the sealing member 51.

  Moreover, in each said embodiment, although a pair of electrode of the acicular electrode 81 and the annular electrode 82 was provided as a forced means means, it is not limited to this. For example, as shown in FIG. 8, pump means such as a micropump 90 may be adopted as forced convection means. In this case, the insulating fluid 50 may not be a fluid that exhibits the EHD phenomenon.

  Further, for example, as shown in FIG. 9, forced convection means is not employed, and the density reduction accompanying the temperature rise of the insulating fluid 50 or the density reduction accompanying the phase change of the latent heat storage material 56 from the solid phase to the liquid phase. May be used for natural convection of the insulating fluid 50. Also in this case, the insulating fluid 50 may not be a fluid exhibiting the EHD phenomenon.

  7 to 9, the microcapsules 55 enclosing the latent heat storage material 56 (not shown) are naturally dispersed in the insulating fluid 50.

  For each of the semiconductor devices that do not use the gel-like sealing member 51 illustrated in FIGS. 7 to 9, the gel-like sealing member of the first embodiment, the heat dissipation means of the second embodiment, the first The heat transfer promoting means of the third embodiment, the high thermal conductive filler of the fourth embodiment, and the double-sided cooling structure of the fifth embodiment are applied in combination, or two or more. It doesn't matter.

  In each of the above embodiments, the latent heat storage material 56 enclosed in the microcapsules 55 stores heat by changing the phase from the solid phase to the liquid phase, but stores heat by changing the phase from the liquid phase to the gas phase. You may do.

1 Semiconductor device 10 Case (casing)
20 Semiconductor element 20a Lower surface (first surface of semiconductor element)
20b Upper surface (second surface of semiconductor element)
40 Heat sink (first heat sink)
41 Heat sink (second heat sink)
50 Insulating fluid 50a High thermal conductive filler 51 Sealing member (gel-like sealing member)
55 Microcapsule 56 Latent heat storage material 60 Radiator (Heat dissipation means)
70 Heat transfer fin (heat transfer promotion means)
81 Needle electrode (part of forced convection means)
82 Annular electrode (part of forced convection means)
90 Micropump (forced convection means)

Claims (8)

A semiconductor element (20);
A casing (10) for housing the semiconductor element therein;
A heat sink (40) disposed on the first surface (20a) side which is one surface of the semiconductor element and dissipating heat generated by the semiconductor element to the outside of the casing;
An insulating fluid (50) filled in the casing so as to be in contact with the second surface (20b) opposite to the first surface of the semiconductor element and capable of convection in the casing;
The semiconductor device, wherein microcapsules (55) encapsulating a latent heat storage material (56) that stores heat received from the semiconductor element as latent heat accompanying phase change are dispersed in the insulating fluid.   The semiconductor device according to claim 1, further comprising forced convection means (81, 82) for forcibly convection the insulating fluid within the casing. The insulating fluid is a fluid exhibiting an electrohydrodynamic phenomenon,
The forced convection means is a pair of electrodes (81, 82) provided in the casing and applying a voltage to the insulating fluid to flow the insulating fluid by the electrohydrodynamic phenomenon. The semiconductor device according to claim 2.   4. The insulating fluid according to claim 1, further comprising a high thermal conductive filler (50a) having an insulating property and higher thermal conductivity than the insulating fluid. The semiconductor device as described in any one.   The semiconductor device according to any one of claims 1 to 4, further comprising a heat radiating means (60) for radiating heat of the insulating fluid to the outside of the casing.   The heat transfer promoting means (70) is provided to protrude from the second surface of the semiconductor element into the insulating fluid and promote heat transfer from the semiconductor element to the latent heat storage material. The semiconductor device according to any one of claims 1 to 5.   A gel-like sealing member (51) for covering the entire surface of the insulating fluid opposite to the side in contact with the semiconductor element and sealing the insulating fluid inside the casing is provided. A semiconductor device according to claim 1, wherein: The heat sink is a first heat sink (40);
The second heat sink (41) is provided on the second surface side of the semiconductor element, and dissipates heat generated by the semiconductor element from the second surface to the outside of the casing. The semiconductor device according to claim 7.

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