JP2012099612A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which improves heat storage responsiveness of a latent heat storage material storing heat generated from a semiconductor element when a heat value of the semiconductor element rapidly increases in a short time.SOLUTION: A heat sink 40, which steadily cools a semiconductor element 20, is disposed on the lower surface 20a side of the semiconductor element 20, and a heat storage body 50 formed by a latent heat storage material, which stores heat received from the semiconductor element 20 as latent heat resulting from a change from a solid phase to a liquid phase, directly contacts with an upper surface 20b of the semiconductor element 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, in the semiconductor device of the above prior art, when the calorific value of the semiconductor element suddenly increases in a short time, the heat generated by the semiconductor element is transmitted to the latent heat storage material through the case, and the latent heat storage material becomes the latent heat. There is a problem that the response time until the heat storage effect is exhibited becomes long.

  The present invention has been made in view of the above points, and improves the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element when the heat generation amount of the semiconductor element increases rapidly in a short time. An object of the present invention is to provide a semiconductor device that can be used.

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;
A heat storage body (50) made of a latent heat storage material filled in the casing so as to be in contact with the second surface (20b) opposite to the first surface of the semiconductor element,
The latent heat storage material has an insulating property and stores heat received from a semiconductor element as latent heat accompanying a change from a solid phase to a liquid phase.

  According to this, steady cooling of the semiconductor element (20) is performed by the heat sink (40), and when the heat generation amount of the semiconductor element increases rapidly in a short time, the latent heat storage material forming the heat storage body (50) is reduced. The phase change from the solid phase to the liquid phase absorbs heat and can suppress the temperature rise of the semiconductor element. Since the heat storage body made of the latent heat storage material has an insulating property and directly touches the second surface (20b) of the semiconductor element, when the amount of heat generated by the semiconductor element increases rapidly in a short time, the semiconductor element Can absorb heat quickly. Thus, the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element can be improved.

  Further, the invention according to claim 2 is characterized in that the heat storage body is further added with a high thermal conductive filler (50a) having insulating properties and higher thermal conductivity than the latent heat storage material. According to this, the heat storage body which received the heat | fever from a semiconductor element can transmit heat | fever rapidly to the whole heat storage body via the high heat conductive filler (50a) whose heat conductivity is higher than a latent heat storage material. Therefore, the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element can be further improved.

  Moreover, in invention of Claim 3, it has the thermal radiation means (60) which thermally radiates the heat which a thermal storage body has to the exterior of a casing, It is characterized by the above-mentioned. According to this, by the heat radiation by the heat radiation means (60), the heat storage body composed of the latent heat storage material that has absorbed heat from the semiconductor element and changed in phase from the solid phase to the liquid phase is cooled, and the latent heat storage material is changed from the liquid phase to the solid phase. It is possible to easily recover the endothermic ability by changing the phase.

  The invention according to claim 4 further includes heat transfer promotion means (70) that protrudes from the second surface of the semiconductor element into the heat storage body and promotes heat transfer from the semiconductor element to the heat storage body. It is a feature. According to this, the heat transfer area can be increased by the heat transfer promotion means (70), and heat transfer from the semiconductor element to the latent heat storage material forming the heat storage body can be promoted. Therefore, the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element can be further improved.

  Further, in the invention according to claim 5, the gel-like sealing member (51) for covering the entire surface of the heat storage body opposite to the side in contact with the semiconductor element and sealing the heat storage body inside the casing. It is characterized by having. According to this, even if the latent heat storage material forming the heat storage body becomes a liquid phase due to heat absorption, the gel-like sealing member (51) casings the heat storage body while accommodating the volume change accompanying the phase change of the heat storage body. Can be easily held inside.

  In the invention according to claim 6, 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. As described above, even in the semiconductor device in which the semiconductor element is cooled from both sides by the first and second heat sinks (40, 41), the latent heat that has insulation and directly touches the second surface (20b) of the semiconductor element. When the calorific value of the semiconductor element increases rapidly in a short time due to the heat storage body made of the heat storage material, the semiconductor element can quickly absorb heat. Thus, the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element can be improved.

  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 1 in 1st Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device 1 in 2nd Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device 1 in 3rd Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device 1 in 4th Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device 1 in 5th Embodiment to which this invention is applied. It is sectional drawing which shows schematic structure of the semiconductor device 1 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 showing a schematic configuration of a semiconductor device 1 according to a first embodiment to which the present invention is applied. 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.

  A heat storage body 50 is filled in the case 10. As apparent from FIG. 1, the heat storage body 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 (the first embodiment of the present invention). The case 10 is filled so as to directly contact (corresponding to two surfaces).

  The heat storage body 50 is made of a latent heat storage material that has an insulating property and can store heat received from the semiconductor element 20 as latent heat accompanying a change from a solid phase to a liquid phase. As the latent heat storage material, for example, erythritol, xylitol, paraffin or the like can be employed. In addition, the heat storage body 50 is filled so that all the circuit components in the case 10 including the bonding wire 12 may be buried.

  The inside of the case 10 covers the entire upper surface of the heat storage body 50, that is, the surface of the heat storage body 50 opposite to the side in contact with the semiconductor element 20, and seals the heat storage body 50 inside the case 10. A flexible gel-like sealing member 51 (corresponding to the gel-like sealing member of the present invention) 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 suddenly increases in a short time, the latent heat storage material forming the heat storage body 50 changes its phase from the solid phase to the liquid phase and absorbs heat, thereby suppressing the temperature rise of the semiconductor element 20.

  According to the semiconductor device 1 having the above-described configuration, the heat storage body 50 made of a latent heat storage material capable of storing heat received from the semiconductor element 20 as latent heat associated with the change from the solid phase to the liquid phase is provided on the upper surface 20 b of the semiconductor element 20. Directly touching. Therefore, when the calorific value of the semiconductor element 20 rapidly increases in a short time, the heat storage body 50 can quickly absorb heat from the semiconductor element 20. Thus, the heat storage responsiveness in which the latent heat storage material forming the heat storage body 50 stores the heat generated by the semiconductor element 20 can be improved.

  Further, the entire upper surface of the heat storage body 50 is covered with a gel-like sealing member 51 to seal the heat storage body 50 in the case 10. Therefore, even if the latent heat storage material forming the heat storage body 50 becomes a liquid phase due to heat absorption, it can be 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 phase change between the solid phase and the liquid phase of the heat storage body 50, it is possible to flex and respond to the volume change. 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 heat storage body 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. 2, the semiconductor device 1 of the present embodiment includes a radiator 60 that is a heat radiating unit. 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.

  The illustrated lower end portion of the heat pipe 61 is located in the heat storage body 50, and the illustrated upper end portion is located above the upper surface of the sealing member 51. For example, a plate-like fin 62 made of copper is joined to a portion of the heat pipe 51 located in the heat storage body 50 and a portion protruding upward from the sealing member 51.

  According to the semiconductor device 1 of the present embodiment, since the heat sink 60 that dissipates the heat of the heat storage body 50 to the outside of the case 10 is provided, the phase is changed from the solid phase to the liquid phase by absorbing heat from the semiconductor element 20. The heat storage body 50 made of the latent heat storage material can be cooled to change the phase of the latent heat storage material from the liquid phase to the solid phase, thereby easily recovering the heat absorption capability.

  Moreover, since the heat radiator 60 has the fin 62 in each of the part located in the thermal storage body 50, and the part which protrudes upwards rather than the sealing member 51, the heat absorption from the thermal storage body 50 and to air | atmosphere are carried out. Heat dissipation can be performed efficiently.

  Further, even if the heat storage body 50 made of a latent heat storage material may temporarily be entirely in a liquid phase state, the radiator 60 is supported by the sealing member 51, so that the position is greatly displaced. Absent. 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. Further, the configuration of the heat radiating means is not limited to the configuration of the heat radiator 60 having the heat pipe 61, as long as the heat of the heat storage body 50 can be radiated to the outside of the case 10.

(Third embodiment)
Next, a third embodiment will be described with reference to 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 heat storage body 50 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 1 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.

  According to the semiconductor device 1 of this embodiment, the heat transfer fins 70 are provided so as to protrude from the upper surface 20b of the semiconductor element 20 into the heat storage body 50, and the contact area between the heat transfer fins 70 and the heat storage body 50 is as follows. The bonding area between the upper surface 20b of the semiconductor element 20 and the heat transfer fin 70 is larger. That is, by providing the heat transfer fins 70, the heat transfer area from the semiconductor element 20 to the heat storage body 50 can be increased, and heat transfer from the semiconductor element 20 to the heat storage body 50 can be promoted. Therefore, the heat storage responsiveness in which the latent heat storage material forming the heat storage body 50 stores the heat generated by the semiconductor element 20 can be reliably improved.

  The heat transfer accelerating means is not limited to the heat transfer fin 70 having the above-described configuration, and any heat transfer promoting means may be used as long as it is formed of a high heat conductive material having a higher thermal conductivity than the heat storage body 50 and can increase the contact area with the heat storage body 50. . For example, it may be a metal heat transfer fin in which a plurality of needle-like portions protrudes inside the heat storage body 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 heat storage body 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. 4, in the semiconductor device 1 of the present embodiment, a high heat conductive filler 50 a having an insulating property and higher thermal conductivity than the latent heat storage material is added to the latent heat storage material forming the heat storage body 50. Yes. 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. 4, 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 substantially uniformly in the latent heat storage material forming the heat storage body 50.

  According to the semiconductor device 1 of the present embodiment, the heat storage body 50 that has received heat from the semiconductor element 20 quickly transfers heat to the entire heat storage body 50 via the high thermal conductive filler 50a having a higher thermal conductivity than the latent heat storage material. can do. Therefore, the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element 20 can be reliably improved. In addition, since the high thermal conductive filler 50a has insulating properties, even if a high aspect ratio filler is used, the circuit of the semiconductor device 1 is not 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. 5, the semiconductor device 1 of the present embodiment includes a heat sink 40 (corresponding to a first heat sink) disposed on the lower surface 20a side of the semiconductor element 20 and a heat sink 41 (corresponding to the upper surface 20b side of the semiconductor element 20). Equivalent to a second 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. 5, the semiconductor device 1 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 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 a heat storage body 50 made of an insulating latent heat storage material.

  In order to fill the internal space with the latent heat storage material, for example, the step of forming the case 10 includes a plurality of steps including a step of forming the latent heat storage material filling path and a step of closing the filling path. have.

  In addition, since the semiconductor device 1 of this embodiment uses the heat sinks 40 and 41 as a part of the electric 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.

  According to the semiconductor device 1 of the present embodiment, the semiconductor element 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. When the amount of heat generated by the semiconductor element 20 is rapidly increased in a short time, heat storage is made of a latent heat storage material that has insulating properties and directly touches the upper surface 20b of the semiconductor element 20. The body 50 can quickly absorb heat from the semiconductor element 20. Thus, also in the double-sided cooling type semiconductor device 1, it is possible to improve the heat storage responsiveness in which the latent heat storage material stores the heat generated by the semiconductor element 20.

(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 said 1st-4th embodiment, although the heat storage body 50 was sealed with the gel-like sealing member 51, not only this but the sealing member 51 is abolished, for example, as shown in FIG. It doesn't matter. When the semiconductor device 1 is mounted on a vehicle and used such as when vibration is applied or the mounting posture is inclined, it is preferably sealed with a gel-like sealing member 51, but is used stationary. In some cases, the sealing member 51 may not be used. 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.

  Further, for the semiconductor device 1 that does not use the gel-like sealing member 51 illustrated in FIG. 6, the gel-like sealing member of the first embodiment, the heat dissipation means of the second embodiment, and the third embodiment. The heat transfer facilitating means, the high thermal conductivity filler of the fourth embodiment, and the two-sided cooling structure of the fifth embodiment may be applied in combination.

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 thermal storage 50a high thermal conductive filler 51 sealing member (gel sealing member)
60 Radiator (Heat dissipation means)
70 Heat transfer fin (heat transfer promotion means)

Claims (6)

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;
A heat storage body (50) made of a latent heat storage material filled in the casing so as to be in contact with the second surface (20b) opposite to the first surface of the semiconductor element,
The latent heat storage material has an insulating property and stores heat received from the semiconductor element as latent heat accompanying a change from a solid phase to a liquid phase.   2. The semiconductor device according to claim 1, wherein a high heat conductive filler (50 a) having an insulating property and higher thermal conductivity than the latent heat storage material is added to the heat storage body.   The semiconductor device according to claim 1, further comprising a heat radiating unit (60) that radiates heat of the heat storage body to the outside of the casing.   2. A heat transfer promoting means (70) that protrudes from the second surface of the semiconductor element into the heat storage body and promotes heat transfer from the semiconductor element to the heat storage body. The semiconductor device according to claim 3.   A gel-like sealing member (51) that covers the entire surface of the heat storage body opposite to the side in contact with the semiconductor element and seals the heat storage body inside the casing is provided. The semiconductor device according to claim 1. 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 5.

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