Patent Publication Number: US-2022216130-A1

Title: Semiconductor module

Description:
TECHNICAL FIELD 
     The present disclosure relates to a semiconductor module. 
     BACKGROUND ART 
     Semiconductor modules including semiconductor elements such as insulated gate bipolar transistors (IGBTs) and a cooler for cooling the semiconductor devices are conventionally known. 
     For example, a semiconductor module disclosed in WO2017/094370 includes a power module including a semiconductor device and a radiator, and a cooling device having a cooling passage through which coolant water flows. 
     The semiconductor device is sealed by a package that is a sealing member, and the radiator is disposed on the lower surface of the package. The radiator includes a mounting portion on which the package is mounted, a stepped portion formed on the lower surface side of the mounting portion, and a plurality of cooling fins formed at the stepped portion. 
     The cooling device has an opening that reaches the cooling passage, and the radiator of the semiconductor device is attached to the opening. Specifically, the stepped portion of the radiator is fitted in the opening of the cooling device, and the cooling fins are disposed in the cooling passage. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: WO2017/094370 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In the semiconductor module described in WO2017/094370, the mounting portion on which the package is mounted has a stepped portion protruding downward, and the cooling fins are formed on the lower surface of the stepped portion. Since the stepped portion is formed between the mounting surface on which the package is mounted and the cooling fins, the distance between the mounting surface and the cooling fins is long. As a result, the heat transfer path for dissipating heat of the semiconductor device in the package from the cooling fins to the cooling water is long, which makes it difficult to dissipate the heat of the semiconductor. 
     The present disclosure is made in view of the problem described above and an object of the present disclosure is to provide a semiconductor module including a semiconductor element and a cooling jacket, in which heat from the semiconductor element can be dissipated well. 
     Solution to Problem 
     A semiconductor module according to the present disclosure includes: a refrigerant jacket including a refrigerant passage through which a refrigerant circulates and an opening extending from an outer surface to the refrigerant passage; a base mounted on the refrigerant jacket and closing the opening; and a semiconductor element provided at the base. The base includes a peripheral wall in an annular shape positioned inside the opening, a bottom plate connected to an end portion of the peripheral wall on a side closer to the refrigerant passage, and a fin protrusion protruding from the bottom plate toward inside of the refrigerant passage and formed on the bottom plate. The base has a recess formed with the peripheral wall and the bottom plate and extending toward the opening. The semiconductor element is disposed at the bottom plate inside the recess. 
     In the semiconductor module described above, the semiconductor element is provided at the bottom plate positioned at the bottom portion of the recess, and the semiconductor element is provided at a position closer to the refrigerant passage than the upper end of the fixing portion. With this configuration, heat of the semiconductor element is dissipated well to the refrigerant. 
     Advantageous Effects of Invention 
     According to the present disclosure, in a semiconductor module including a semiconductor element and a cooling jacket, heat from the semiconductor element can be dissipated well. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a semiconductor module  1  according to a first embodiment. 
         FIG. 2  is an exploded perspective view of semiconductor module  1 . 
         FIG. 3  is a cross-sectional view of semiconductor module  1 . 
         FIG. 4  is a cross-sectional view of a semiconductor module  1 A according to a modification of semiconductor module  1 . 
         FIG. 5  is an exploded perspective view of a semiconductor module  1 B according to a second embodiment. 
         FIG. 6  is a perspective view of an electrode case  50 . 
         FIG. 7  is a cross-sectional view of semiconductor module  1 B. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Referring to  FIG. 1  to  FIG. 7 , a semiconductor module according to embodiments of the present invention will be described. In the configurations shown in  FIG. 1  to  FIG. 7 , the same or substantially same configuration is denoted by the same reference sign and an overlapping description is not repeated. 
     First Embodiment 
       FIG. 1  is a perspective view of a semiconductor module  1  according to a first embodiment. Semiconductor module  1  includes a refrigerant jacket  2  in the inside of which a refrigerant C flows, a base  3  mounted on refrigerant jacket  2 , and a plurality of semiconductor elements  4  provided at base  3 . 
       FIG. 2  is an exploded perspective view of semiconductor module  1 . Refrigerant jacket  2  has a refrigerant passage  6  through which refrigerant C flows, and an opening  7  extending from an outer surface of refrigerant jacket  2  to refrigerant passage  6 . 
     In the example shown in  FIG. 2 , refrigerant jacket  2  is formed in the shape of a rectangular parallelepiped. Refrigerant jacket  2  has an upper surface  10 , a lower surface  11 , a side surface  12  positioned at one end in the width direction W of refrigerant jacket  2 , a side surface  13  positioned at the other end in the width direction W, an end surface  14  positioned at one end in the longitudinal direction L of refrigerant jacket  2 , and an end surface  15  positioned at the other end in the longitudinal direction L. 
     Refrigerant passage  6  is formed to extend from end surface  14  to end surface  15 . An inner surface of refrigerant passage  6  includes a top surface  30  positioned on the side closer to upper surface  10 , a bottom surface  31  positioned on the side closer to lower surface  11 , an inner side surface  32  positioned on the side closer to side surface  12 , and an inner side surface  33  positioned on the side closer to side surface  13 . Opening  7  is formed in upper surface  10 , and upper surface  10  has a ring groove  8  and a plurality of screw holes  16 . 
     Ring groove  8  is formed annularly along the opening edge of opening  7 , and an O ring  9  is attached to ring groove  8 . A plurality of screw holes  16  are spaced apart from each other along ring groove  8 . 
     Base  3  has a recess  23 . Base  3  has a flange  20  extending annually, a bottom plate  22 , a peripheral wall  21  connecting flange  20  and bottom plate  22 , and a plurality of fin protrusions  24  formed on bottom plate  22 . 
     A plurality of semiconductor elements  4  are disposed in recess  23 , and a plurality of semiconductor elements  4  are disposed at bottom plate  22 . In the present first embodiment, semiconductor module  1  is an inverter for vehicles and an inverter for a three-phase motor. As shown in  FIG. 1 , a plurality of semiconductor elements  4  are six IGBTs  4 A and six free-wheeling diodes (FwDis)  4 B. In the width direction W, FwDis  4 B are disposed closer to the center of refrigerant passage  6  than IGBTs  4 A. 
       FIG. 3  is a cross-sectional view of semiconductor module  1 . Referring to  FIG. 2  and  FIG. 3 , flange  20  is disposed on upper surface  10  of refrigerant jacket  2  and formed annually along the opening edge of opening  7 . 
     Peripheral wall  21  is formed to extend from the opening edge of flange  20  toward refrigerant passage  6 . Peripheral wall  21  is disposed in contact with an inner peripheral surface of opening  7 , and peripheral wall  21  is formed annually. 
     Bottom plate  22  is connected to an end portion of peripheral wall  21  on the side closer to refrigerant passage  6 . Bottom plate  22  is formed to close the opening of peripheral wall  21  positioned on the side closer to refrigerant passage  6 . Here, the thickness T 2  of bottom plate  22  is smaller than the thickness T 0  of flange  20  and the thickness T 3  of peripheral wall  21 . The thickness T 2  of bottom plate  22  is smaller than the thickness T 4  between upper surface  10  and top surface  30  of refrigerant jacket  2 . 
     Recess  23  is formed with peripheral wall  21  and bottom plate  22 . Recess  23  is formed to extend from the outer surface of flange  20  toward opening  7 . 
     Bottom plate  22  has a placement surface  25  forming a part of the inner surface of recess  23  and a cooling surface  26  disposed on the side closer to refrigerant passage  6 . 
     Semiconductor elements  4  are disposed at placement surface  25  with a substrate  19  interposed. Substrate  19  is provided on the upper surface of placement surface  25 . Substrate  19  includes an insulating plate and circuit wiring formed on the upper surface of the insulating plate. The circuit wiring electrically connects semiconductor elements  4 . 
     A plurality of fin protrusions  24  are formed on cooling surface  26 . Specifically, a plurality of fin protrusions  24  are spaced apart from each other and arranged in an array. 
     Here, bottom plate  22  is disposed such that cooling surface  26  of bottom plate  22  is flush with the inner surface of refrigerant passage  6 . In the present embodiment, cooling surface  26  is flush with top surface  30  of refrigerant passage  6 . As used herein “flush” not only means that there is no step between cooling surface  26  and top surface  30  but also means that there is substantially no step between cooling surface  26  and top surface  30 . “There is substantially no step” means that, for example, there is only a step as small as a few mm between cooling surface  26  and top surface  30 . 
     O ring  9  is disposed in ring groove  8  and is in intimate contact with flange  20 . O ring  9  suppresses leakage of refrigerant C from between upper surface  10  of refrigerant jacket  2  and flange  20 . 
     Flange  20  has screw holes  17 . In a state in which peripheral wall  21  of base  3  is attached to opening  7 , screw hole  17  is communicatively connected to screw hole  16  formed in upper surface  10 . A screw groove is formed in the inner peripheral surface of screw hole  16 ,  17 . 
     Screw  5  is inserted in screw hole  16  and screw hole  17  to fix base  3  to refrigerant jacket  2 . 
     In semiconductor module  1  configured as described above, when semiconductor elements  4  such as IGBTs  4 A and FwDis  4 B perform switching, semiconductor elements  4  produce heat. On the other hand, semiconductor elements  4  are disposed at bottom plate  22  that is a bottom portion of recess  23  formed in base  3 . In other words, semiconductor elements  4  are provided at a position closer to refrigerant passage  6  than the upper end of peripheral wall  21 . In a different point of view, semiconductor elements  4  are provided at a position closer to refrigerant passage  6  than upper surface  10  of refrigerant jacket  2 . 
     Heat from semiconductor elements  4  are dissipated well to refrigerant C from cooling surface  26  of bottom plate  22  and a plurality of fin protrusions  24  formed on bottom plate  22 . Specifically, since the thickness T 2  of bottom plate  22  is smaller than thickness T 0  of flange  20  and thickness T 1  of peripheral wall  21 , the heat transfer path for heat from semiconductor elements  4  to reach refrigerant C is relatively short. Therefore, heat from semiconductor elements  4  is dissipated well to refrigerant C. Furthermore, since the thickness T 2  of bottom plate  22  is smaller than the thickness T 4  between upper surface  10  and top surface  30  of refrigerant jacket  2 , heat from semiconductor elements  4  can be dissipated to refrigerant C better than, for example, when the thickness T 2  of bottom plate  22  is equivalent to the thickness T 4 . 
     Since the inner surface of refrigerant passage  6  is flush with cooling surface  26  of bottom plate  22 , increase of circulation resistance when refrigerant C passes through a boundary between the inner surface of refrigerant passage  6  and cooling surface  26  is suppressed. 
     If a step is formed between the inner surface of refrigerant passage  6  and cooling surface  26 , it is likely that refrigerant C collides against the step or refrigerant C swirls, and the circulation resistance of refrigerant C becomes high. As a result, the cooling performance of refrigerant C tends to deteriorate. On the other hand, in semiconductor module  1  according to the present first embodiment, increase of circulation resistance of refrigerant C is suppressed, and deterioration of cooling performance of refrigerant C is suppressed. 
     Since refrigerant passage  6  extends linearly, the flow rate of refrigerant C passing through refrigerant passage  6  increases toward the center in the width direction W in refrigerant passage  6 . Referring to  FIG. 1 , FwDis  4 B are positioned closer to the center of refrigerant passage  6  than IGBTs  4 A in the width direction W. The higher the flow rate of refrigerant C is, the higher the cooling performance of refrigerant C is. FwDis  4 B thus can be cooled actively. IGBTs  4 A may be disposed closer to the center of refrigerant passage  6  than FwDis  4 B in the width direction W. In this case, IGBTs  4 A can be cooled actively. 
       FIG. 4  is a cross-sectional view of a semiconductor module  1 A according to a modification of semiconductor module  1 . In semiconductor module  1 A, recess  23  is filled with filling resin  28 , and semiconductor elements  4  and substrate  19  are covered with filling resin  28 . This configuration can suppress adhesion of foreign substances such as water and dust to semiconductor elements  4  and substrate  19 . 
     Second Embodiment 
       FIG. 5  is an exploded perspective view of a semiconductor module  1 B according to a second embodiment. Semiconductor module  1 B further includes an electrode case  50  and a control substrate  51  in semiconductor module  1  according to the foregoing first embodiment. 
     Electrode case  50  is disposed in recess  23  of base  3 , and control substrate  51  is disposed above electrode case  50 . 
       FIG. 6  is a perspective view of electrode case  50 . Electrode case  50  includes a body resin  55  formed in an annular shape, and a plurality of control terminals  56  and a plurality of electrode terminals  57  provided in body resin  55 . 
     Body resin  55  is formed of an insulating material such as resin. Body resin  55  has an upper surface  60  and a lower surface  61 . Body resin  55  has a hollow portion  58  extending from upper surface  60  to lower surface  61 . Body resin  55  has an outer peripheral surface  62  and an inner peripheral surface  63  formed with hollow portion  58 . A plurality of bosses  59  are formed on upper surface  60  of body resin  55 . 
     Each control terminal  56  has an end portion  65  and an end portion  66 . End portion  65  is positioned inside hollow portion  58 . Control terminal  56  extends from end portion  65  toward inner peripheral surface  63  and is bent in body resin  55  so as to be flexed upward. Each control terminal  56  is formed to protrude outward and extend upward from upper surface  60 . 
     Each electrode terminal  57  has an end portion  67  and an end portion  68 . End portion  67  is positioned inside hollow portion  58 . Electrode terminal  57  extends from end portion  67  toward inner peripheral surface  63  and is bent in body resin  55  to be flexed upward. Each electrode terminal  57  is formed to protrude outward from upper surface  60  and then extend horizontally. 
     In  FIG. 5 , end portion  65  of control terminal  56  and end portion  67  of electrode terminal  57  are electrically connected to IGBT  4 A or FwDi  4 B. Specifically, control terminal  56  and electrode terminal  57  are connected to the circuit wiring formed on the substrate and are electrically connected to IGBT  4 A and FwDi  4 B through the circuit wiring. 
     Control substrate  51  is shaped like a flat plate. A plurality of through holes  53  and a plurality of screw holes  54  are formed in control substrate  51 . The end portion  66  side of control terminal  56  is inserted in each through hole  53 . Control substrate  51  transmits a control signal for controlling switching of IGBT  4 A and FwDi  4 B through control terminal  56 . End portion  68  of electrode terminal  57  is electrically connected to, for example, a three-phase motor or a boost converter. 
     Control substrate  51  is fixed to electrode case  50  by screws  40 . Specifically, screw  40  is inserted in screw hole  54  and boss  59  and screwed in a threaded groove formed in the inner surface of boss  59 . 
       FIG. 7  is a cross-sectional view of semiconductor module  1 B. Upper surface  60  of body resin  55  is flush with the upper surface of flange  20  of base  3 . Lower surface  61  of body resin  55  is disposed to face placement surface  25  of bottom plate  22 . Specifically, lower surface  61  is disposed to face a portion of placement surface  25  that is positioned between semiconductor element  4  and peripheral wall  21 . Outer peripheral surface  62  extending annually is in contact with the inner peripheral surface of peripheral wall  21 , for example, at two or more places. In the example shown in  FIG. 7 , outer peripheral surface  62  is in contact with the inner peripheral surface of peripheral wall  21  over substantially the entire periphery. 
     Hollow portion  58  of body resin  55  is filled with filling resin  49 . Semiconductor elements  4 , substrate  19 , parts of control terminals  56 , and parts of electrode terminals  57  are covered with filling resin  49 . Since semiconductor elements  4  and substrate  19  are covered with filling resin  49 , adhesion of foreign substances such as water and dust to semiconductor elements  4  and substrate  19  is suppressed. 
     In semiconductor module  1 B configured as described above, body resin  55  of electrode case  50  is positioned inside recess  23 , and increase in height dimension of semiconductor module  1 B is suppressed even when body resin  55  is attached to base  3 . 
     A manufacturing process of manufacturing semiconductor module  1 B includes an alignment process of aligning electrode case  50  with base  3  and a fixing process of fixing electrode case  50  to base  3  in the aligned state. 
     In the present second embodiment, since outer peripheral surface  62  of electrode case  50  is in contact with the inner peripheral surface of peripheral wall  21  at multiple places, electrode case  50  can be aligned with base  3  by inserting electrode case  50  into recess  23  in the alignment process. In this way, the alignment process is very simple in semiconductor module  1 B. 
     In the fixing process, electrode case  50  can be fixed to base  3  by filling hollow portion  58  with filling resin  49  with electrode case  50  inserted in recess  23 . 
     Semiconductor module  1 B according to the second embodiment has a configuration similar to that of semiconductor module  1 , and semiconductor module  1 B also achieves operation and effect similar to that of semiconductor module  1 . 
     Embodiments disclosed here should be understood as being illustrative rather than being limitative in all respects. The scope of the present disclosure is shown in the claims, and it is intended that all modifications that come within the meaning and range of equivalence to the claims are embraced here. 
     REFERENCE SIGNS LIST 
       1 ,  1 A,  1 B semiconductor module,  2  refrigerant jacket,  3  base,  4  semiconductor element,  6  refrigerant passage,  7  opening,  8  ring groove,  9  ring,  10 ,  60  upper surface,  11 ,  61  lower surface,  12 ,  13  side surface,  14 ,  15  end surface,  16 ,  17 ,  54  screw hole,  18 ,  40  screw,  19  substrate,  20  flange,  21  peripheral wall,  22  bottom plate,  23  recess,  24  fin protrusion,  25  placement surface,  26  cooling surface,  28 ,  49  filling resin,  30  top surface,  31  bottom surface,  32 ,  33  inner side surface,  50  electrode case,  51  control substrate,  53  through hole,  55  body resin,  56  control terminal,  57  electrode terminal,  58  hollow portion,  59  boss,  62  outer peripheral surface,  63  inner peripheral surface,  65 ,  66 ,  67 ,  68  end portion, C refrigerant, L longitudinal direction, T 0 , T 1 , T 2  thickness, W width direction.