Power module and power conversion device equipped with same

Abstract

A power module (1) comprises a semiconductor element (9), a heat spreader (3), a resin-impregnated composite (13), a metal plate (15), and a sealing material (21), and is further provided with resin traps (31) for capturing a resin (25) impregnated into the resin-impregnated composite (13). Recesses (33) and the like are provided as the resin traps (31). The recesses (33) include a first recess (35a) and a second recess (35b). The first recess (35a) is formed in a second main surface (5b) of the heat spreader (3). The second recess (35b) is formed in a third main surface (17a) of the metal plate (15).

Description

Power module and power conversion device including the same

[0001] The present disclosure relates to a power module and a power conversion device including the same.

[0002] In a power module used for power conversion, etc., a power semiconductor element is bonded to a heat spreader having thermal conductivity. A metal plate is bonded to the heat spreader with an insulator interposed therebetween. To dissipate heat generated by the semiconductor element mounted in the power module, the metal plate is bonded to a radiator such as a heat sink.

[0003] The insulator in the power module is required to efficiently conduct heat generated in the semiconductor element from the heat spreader to the heat sink, and also to provide electrical insulation between the heat spreader, to which the semiconductor element is electrically connected, and the metal plate joined to the heat sink.

[0004] Patent Document 1 proposes a power module that uses, as such an insulator, a resin-impregnated composite formed by impregnating a porous ceramic sintered body with a resin.

[0005] Japanese Patent Application Laid-Open No. 2023-54418

[0006] Power modules that use resin-impregnated composites are required to have even better heat dissipation properties.

[0007] The present disclosure has been made based on such development, and one object is to provide a power module that can more effectively dissipate heat generated in semiconductor elements, and another object is to provide a power conversion device equipped with such a power module.

[0008] The power module according to the present disclosure includes a heat spreader, a semiconductor element, a resin-impregnated composite, a metal plate, and a sealing material. The heat spreader has opposing first and second main surfaces. The semiconductor element is bonded to the first main surface of the heat spreader. The resin-impregnated composite is bonded to the second main surface of the heat spreader. The metal plate has a third main surface, and the third main surface is bonded to the side of the resin-impregnated composite opposite to the side to which the heat spreader is bonded. The sealing material seals the semiconductor element, the heat spreader, the resin-impregnated composite, and the metal plate. A resin trap is provided between at least one of the resin-impregnated composite and the heat spreader and the resin-impregnated composite and the metal plate to capture resin impregnated in the resin-impregnated composite.

[0009] The power conversion device according to the present disclosure includes the power module, a main conversion circuit that converts input power and outputs it, and a control circuit that outputs a control signal to the main conversion circuit to control the main conversion circuit.

[0010] According to the power module of the present disclosure, a resin trap for capturing the resin impregnated in the resin-impregnated composite is provided between the resin-impregnated composite and the heat spreader and / or between the resin-impregnated composite and the metal plate. This prevents resin from seeping out of the resin-impregnated composite, capturing the resin in the resin trap. This prevents the formation of a resin layer consisting solely of resin. This effectively dissipates heat generated in the semiconductor element.

[0011] According to the power conversion device according to the present disclosure, by including the above-described power module, heat is dissipated effectively, which can contribute to stabilizing the operation of the power conversion device.

[0012] 1 is a cross-sectional view of a power module according to a first embodiment; FIG. 1 is a cross-sectional view of a power module according to a comparative example; FIG. 2 is a partially enlarged cross-sectional view showing the inside of a circle shown in FIG. 1; FIG. 2 is a cross-sectional view of a power module according to a modified example of the same embodiment; FIG. 3 is a cross-sectional view of a power module according to a second embodiment; FIG. 4 is a plan view of a heat spreader in which a first groove is formed in the same embodiment; FIG. 5 is a plan view of a metal plate in which a second groove is formed in the same embodiment; FIG. 6 is a first partially enlarged cross-sectional view for explaining the flow of resin and the behavior of bubbles in the same embodiment; FIG. 7 is a second partially enlarged cross-sectional view for explaining the flow of resin and the behavior of bubbles in the same embodiment; FIG. 8 is a cross-sectional view of a power module according to a third embodiment; FIG. 9 is a plan view of a heat spreader in which a first hole is formed in the same embodiment; FIG. 10 is a plan view of a metal plate in which a second hole is formed in the same embodiment; FIG. 11 is a cross-sectional view of a power module according to a fourth embodiment; FIG. 12 is a cross-sectional view of a power module according to a fifth embodiment; FIG. 13 is a plan view of a heat spreader in which a first protrusion is formed in the same embodiment; FIG. 14 is a plan view of a metal plate in which a second protrusion is formed in the same embodiment; FIG. 15 is a partially enlarged cross-sectional view of a power module according to the same embodiment; FIG. 16 is a plan view of a heat spreader in which a first protrusion is formed in a power module according to a modified example of the same embodiment. Fig. 10 is a plan view of a metal plate on which second protrusions are formed in a power module according to a modified example in the same embodiment. Fig. 11 is a cross-sectional view of a power module according to embodiment 6. Fig. 12 is a plan view of first metal fibers in the same embodiment. Fig. 13 is a block diagram of a power conversion device according to embodiment 7.

[0013] First Embodiment. An example of a power module according to a first embodiment will be described. As shown in FIG. 1 , the power module 1 includes a semiconductor element 9, a heat spreader 3, a resin-impregnated composite 13, a metal plate 15, and a sealing material 21. The heat spreader 3 has thermal conductivity. The heat spreader 3 is formed, for example, from a material with high electrical conductivity, such as copper or aluminum. The heat spreader 3 is plate-shaped and has opposing first and second main surfaces 5a and 5b. The semiconductor element 9 is bonded to the first main surface 5a of the heat spreader 3 by a bonding material 7. Leads 11a are electrically connected to the semiconductor element 9 by wires 19. Leads 11b are electrically connected to the heat spreader 3.

[0014] The resin-impregnated composite 13 is bonded (joined) to the second main surface 5b of the heat spreader 3. The resin-impregnated composite 13 is a composite in which a porous ceramic sintered body is impregnated with resin. The resin is, for example, a thermosetting resin. The metal plate 15 is formed, for example, from copper or the like. The metal plate 15 has opposing third and fourth main surfaces 17a and 17b. The third main surface 17a of the metal plate 15 is bonded (joined) to the resin-impregnated composite 13. The metal plate 15 is bonded (joined) to the side of the resin-impregnated composite 13 opposite to the side to which the heat spreader 3 is bonded. A heat sink or other such heat sink is to be bonded to the fourth main surface 17b of the metal plate 15.

[0015] Furthermore, the power module 1 is provided with resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13. The resin traps 31 are provided both between the resin-impregnated composite 13 and the heat spreader 3 and between the resin-impregnated composite 13 and the metal plate 15. In other words, the resin traps 31 are provided on both the side of the resin-impregnated composite 13 where the heat spreader 3 is located and the side of the resin-impregnated composite 13 where the metal plate 15 is located.

[0016] A recess 33 is formed as the resin trap 31. The recess 33 includes a first recess 35a and a second recess 35b. The first recess 35a is formed in the second main surface 5b of the heat spreader 3. The second recess 35b is formed in the third main surface 17a of the metal plate 15. The depth of each of the first recess 35a and the second recess 35b is, for example, approximately several tens of μm. The recess 33 may be a hole or a groove. The sealing material 21 seals the semiconductor element 9, the heat spreader 3, the resin-impregnated composite 13, and the metal plate 15 in a manner that exposes the fourth main surface 17b of the metal plate 15. The power module 1 according to the first embodiment is configured as described above.

[0017] In the above-described power module 1, even if resin seeps out of the resin-impregnated composite 13 when pressure is applied by a press or the like under high temperature conditions in the process of manufacturing the power module 1, the resin is captured in the resin trap 31, thereby further improving the heat dissipation performance of the power module 1. This will be explained in comparison with a power module 101 according to a comparative example.

[0018] The power module 101 (see FIG. 2) according to the comparative example has the same structure as the power module 1 (see FIG. 1) according to the first embodiment, except for the heat spreader 103 and the metal plate 115. The main structure of the power module 101 will be described.

[0019] 2, in the power module 101, a semiconductor element 109 is bonded to a first main surface 105a of a heat spreader 103 by a bonding material 107. A resin-impregnated composite 113 is bonded to a second main surface 105b of the heat spreader 103. A third main surface 117a of a metal plate 115 is bonded to the resin-impregnated composite 113. The semiconductor element 109 and the like are sealed with a sealing material 121 in a manner that exposes a fourth main surface 117b of the metal plate 115. The power module 101 according to the comparative example is configured as described above.

[0020] According to the evaluation by the inventors, it was found that in the manufacturing process of the power module 101, when pressure is applied by a press or the like under high temperature conditions, the resin impregnated in the resin-impregnated composite 113 may seep out of the resin-impregnated composite 113, and a resin layer 125 (see FIG. 3) consisting only of resin may be formed.

[0021] That is, as shown in Fig. 3, it was found that a resin layer 125 consisting only of resin may be formed between the resin-impregnated composite 113 and the heat spreader 103. It was also found that a resin layer 125 consisting only of resin may be formed between the resin-impregnated composite 113 and the metal plate 115. Note that Fig. 3 shows the structure within the circular frame S shown in Fig. 2.

[0022] If a resin layer 125 made only of resin is formed, the resin layer 125 may hinder the heat generated in the semiconductor element 109 from being dissipated to the heat sink 123, and the desired heat dissipation performance may not be achieved.

[0023] Unlike the power module 101 according to the comparative example, the power module 1 according to the first embodiment has recesses 33 formed as resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13, and the recesses 33 include a first recess 35a and a second recess 35b. The first recess 35a is formed on the second main surface 5b of the heat spreader 3, which faces the resin-impregnated composite 13. The second recess 35b is formed on the third main surface 17a of the metal plate 15, which faces the resin-impregnated composite 13.

[0024] As a result, even if resin seeps out of the resin-impregnated composite 13 when pressurized under high temperature conditions during the process of manufacturing the power module 1, the seeped resin 25 will be captured in the first recess 35a or the second recess 35b, respectively.

[0025] By capturing the resin 25 in the first recess 35 a, it is possible to prevent a resin layer consisting only of resin from being formed in a region between the resin-impregnated composite 13 and the heat spreader 3 other than the region where the first recess 35 a is located. Furthermore, by capturing the resin 25 in the second recess 35 b, it is possible to prevent a resin layer consisting only of resin from being formed in a region between the resin-impregnated composite 13 and the metal plate 15 other than the region where the second recess 35 b is located.

[0026] By suppressing the formation of a resin layer that inhibits heat dissipation, the heat generated in the semiconductor element 9 can be effectively dissipated to the heat sink 23. As a result, the heat dissipation performance of the power module 1 can be improved. Note that it is desirable to estimate the capacity (volume) of the recess 33 in advance, taking into account the amount of resin that may seep out, so that the recess 33 does not remain as a void (cavity).

[0027] In the above-described power module 1, the recess 33 having a rectangular cross-sectional shape has been described as an example. The cross-sectional shape of the recess 33 may be such that the sidewalls 34 of the recess 33 (first recess 35a and second recess 35b) are inclined. That is, as shown in FIG. 4 , each of the first recess 35a and the second recess 35b may have a sidewall 34 that is inclined so as to widen toward the resin-impregnated composite 13. The tapered recess 33 having the inclined sidewall 34 can improve electrical insulation. This will be described later.

[0028] Second Embodiment An example of a power module according to a second embodiment will be described. Here, an example of a variation of the recess 33 serving as the resin trap 31 will be described.

[0029] 5, in the power module 1, recesses 33 are formed as resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13, and the recesses 33 include a first groove 37a and a second groove 37b. The first groove 37a is formed in the second main surface 5b of the heat spreader 3. The second groove 37b is formed in the third main surface 17a of the metal plate 15. Each of the first groove 37a and the second groove 37b has a sidewall 34 that is sloped so as to widen toward the resin-impregnated composite 13. The cross-sectional shape of each of the first groove 37a and the second groove 37b is V-shaped (tapered groove).

[0030] As shown in Fig. 6, the first groove 37a extends along the outer edge of the heat spreader 3 and is formed continuously so as to describe a rectangle. As shown in Fig. 7, the second groove 37b extends along the outer edge of the metal plate 15 and is formed continuously so as to describe a rectangle. Note that the first groove 37a and the second groove 37b do not necessarily have to be formed continuously. The rest of the configuration is the same as the configuration of the power module 1 shown in Fig. 1, so the same members are designated by the same reference numerals, and description thereof will not be repeated unless necessary.

[0031] In the above-described power module 1, a first groove 37a and a second groove 37b are formed as recesses 33 (resin traps 31) for capturing the resin impregnated in the resin-impregnated composite 13. The first groove 37a is formed in the second main surface 5b of the heat spreader 3, which faces the resin-impregnated composite 13. The second groove 37b is formed in the third main surface 17a of the metal plate 15, which faces the resin-impregnated composite 13.

[0032] As a result, even if resin seeps out of the resin-impregnated composite 13 when pressurized under high temperature conditions during the process of manufacturing the power module 1, the seeped resin 25 will be captured in the first groove 37a or the second groove 37b, respectively.

[0033] By capturing the resin 25 in the first groove 37a, it is possible to prevent a resin layer consisting only of resin from being formed in a region between the resin-impregnated composite 13 and the heat spreader 3 other than the region where the first groove 37a is located. Furthermore, by capturing the resin 25 in the second groove 37b, it is possible to prevent a resin layer consisting only of resin from being formed in a region between the resin-impregnated composite 13 and the metal plate 15 other than the region where the second groove 37b is located.

[0034] By suppressing the formation of a resin layer that inhibits heat dissipation, the heat generated in the semiconductor element 9 can be effectively dissipated to the heat sink 23. As a result, the heat dissipation performance of the power module 1 can be improved.

[0035] Furthermore, in the above-described power module 1, the cross-sectional shape of the recess 33 (first groove 37a and second groove 37b) is V-shaped (tapered groove), and the side wall 34 of the recess 33 (first groove 37a and second groove 37b) is sloped in a manner that widens toward the resin-impregnated composite 13. This can further improve the electrical insulation of the power module 1. This will be explained.

[0036] When the resin 25 seeping out of the resin-impregnated composite 13 is captured in the recess 33, the flow of the resin may cause air bubbles to form in the recess 33. In this case, if the cross-sectional shape of the second groove 37b (recess 33) is substantially rectangular as shown in Fig. 8, air bubbles BL may remain at the bottom edge of the second groove 37b (recess 33). The same applies to the first groove 37a (see Fig. 5).

[0037] 9, in the second groove 37b (recess 33) having a V-shaped cross section, the side wall 34 of the second groove 37b (recess 33) is sloped in a manner that widens toward the resin-impregnated composite 13. As a result, even if air bubbles BL are generated by the flow of the resin 25 when the resin 25 that has seeped out of the resin-impregnated composite 13 is captured in the second groove 37b (recess 33), the flow of the resin 25 makes it easier for the air bubbles BL to be discharged from the second groove 37b (recess 33).

[0038] By discharging the air bubbles BL, the amount of air bubbles BL remaining in the second groove 37b (recess 33) is reduced. The same applies to the first groove 37a. As a result, the risk of the air bubbles BL deteriorating the electrical insulation is reduced, and the electrical insulation of the power module 1 can be improved.

[0039] Embodiment 3 An example of a power module according to embodiment 3 will be described. Here, other variations of the recess 33 as the resin trap 31 will be described.

[0040] 10 , in the power module 1, a recess 33 is formed as a resin trap 31 for capturing the resin impregnated in the resin-impregnated composite 13, and a first hole 39a and a second hole 39b are formed as the recess 33. The first hole 39a is formed in the second main surface 5b of the heat spreader 3. The second hole 39b is formed in the third main surface 17a of the metal plate 15. Each of the first hole 39a and the second hole 39b has a sidewall 34 that is sloped such that the opening size increases toward the resin-impregnated composite 13.

[0041] As shown in Fig. 11 , the first holes 39a are formed at intervals from one another along the outer edge of the heat spreader 3. As shown in Fig. 12 , the second holes 39b are formed at intervals from one another along the outer edge of the metal plate 15. Note that the rest of the configuration is similar to that of the power module 1 shown in Fig. 1 , and therefore the same members are denoted by the same reference numerals, and description thereof will not be repeated unless necessary.

[0042] In the above-described power module 1, a first hole 39a and a second hole 39b are formed as recesses 33 (resin traps 31) for capturing the resin impregnated in the resin-impregnated composite 13. The first hole 39a is formed in the second main surface 5b of the heat spreader 3, which faces the resin-impregnated composite 13. The second hole 39b is formed in the third main surface 17a of the metal plate 15, which faces the resin-impregnated composite 13.

[0043] As a result, even if resin 25 seeps out of resin-impregnated composite 13 when pressurized under high temperature conditions during the process of manufacturing power module 1, the seeped resin 25 will be captured in first hole 39a or second hole 39b, respectively.

[0044] By capturing the resin 25 in the first holes 39 a, it is possible to prevent the formation of a resin layer consisting only of the resin 25 in regions between the resin-impregnated composite 13 and the heat spreader 3 other than the region where the first holes 39 a are located. Furthermore, by capturing the resin 25 in the second holes 39 b, it is possible to prevent the formation of a resin layer consisting only of the resin in regions between the resin-impregnated composite 13 and the metal plate 15 other than the region where the second holes 39 b are located.

[0045] By suppressing the formation of a resin layer that inhibits heat dissipation, the heat generated in the semiconductor element 9 can be effectively dissipated to the heat sink 23. As a result, the heat dissipation performance of the power module 1 can be improved.

[0046] Furthermore, each of the first hole 39a and the second hole 39b has a sidewall 34 that is sloped so as to widen toward the resin-impregnated composite 13. As a result, even if bubbles are generated by the flow of the resin 25 when the resin 25 that has seeped out of the resin-impregnated composite 13 is captured in the first hole 39a or the second hole 39b (recess 33), the flow of the resin 25 makes it easier to expel the bubbles from the recess 33. This reduces the number of bubbles remaining in the first hole 39a or the second hole 39b (recess 33), suppressing the risk of a decrease in electrical insulation. As a result, the electrical insulation of the power module 1 can be improved.

[0047] Fourth Embodiment An example of a power module according to a fourth embodiment will be described. Here, an example of a variation in the arrangement of the recesses 33 will be described.

[0048] 13 , in the power module 1, a first groove 37a and a second groove 37b are formed as recesses 33 (resin traps 31) for capturing the resin impregnated in the resin-impregnated composite 13. The first groove 37a is formed in the second main surface 5b of the heat spreader 3. The second groove 37b is formed in the third main surface 17a of the metal plate 15.

[0049] The first groove 37a and the second groove 37b are formed in a region located outside the heat conduction region HR through which heat generated from the semiconductor element 9 is mainly conducted toward the heat sink 23. The heat generated from the semiconductor element 9 is conducted through the region (heat conduction region HR) of the heat spreader 3, the resin-impregnated composite 13, and the metal plate 15 in a manner that the heat spreader 3 spreads obliquely at approximately 45 degrees from the end of the semiconductor element 9 toward the metal plate 15 (heat sink 23).

[0050] The first groove 37 a and the second groove 37 b are formed in a region outside the heat conduction region HR. Since the other configurations are the same as those of the power module 1 shown in Fig. 1, the same members are denoted by the same reference numerals, and the description thereof will not be repeated unless necessary.

[0051] In the above-described power module 1, in particular, the first grooves 37a are formed on the second main surface 5b of the heat spreader 3 outside the region where heat is mainly conducted from the semiconductor elements 9 to the heat sink 23. In addition, the second grooves 37b are formed on the third main surface 17a of the metal plate 15 outside the region where heat is mainly conducted from the semiconductor elements 9 to the heat sink 23.

[0052] This prevents the trapped resin 25, which has a relatively low thermal conductivity, from interfering with heat conduction even if the resin 25 seeps out of the resin-impregnated composite 13 and is trapped in the first groove 37 a or the second groove 37 b. As a result, the heat generated by the semiconductor element 9 can be more effectively dissipated to the heat sink 23.

[0053] Although the first groove 37 a and the second groove 37 b have been described as examples in the power module 1, it is preferable to form the first recess 35 a and the second recess 35 b in regions outside the heat conduction region as well. It is also preferable to form the first hole 39 a and the second hole 39 b in regions outside the heat conduction region as well.

[0054] Fifth Embodiment An example of a power module according to a fifth embodiment will be described. Here, another example of a variation of the resin trap 31 will be described.

[0055] 14 , in the power module 1, protrusions 41 are formed as resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13, and the protrusions 41 include a first protrusion 43 a and a second protrusion 43 b. The first protrusion 43 a is formed on the second main surface 5 b of the heat spreader 3. The second protrusion 43 b is formed on the third main surface 17 a of the metal plate 15.

[0056] As shown in Figure 15, a plurality of pyramidal first protrusions 43a are arranged at intervals from one another on the second main surface 5b of the heat spreader 3. The first protrusions 43a have sloped sidewalls 42. As shown in Figure 16, a plurality of pyramidal second protrusions 43b are arranged at intervals from one another on the third main surface 17a of the metal plate 15. The second protrusions 43b have sloped sidewalls 42. Note that the rest of the configuration is similar to that of the power module 1 shown in Figure 1, and therefore the same components are designated by the same reference numerals, and description thereof will not be repeated unless necessary.

[0057] In the above-described power module 1, first protrusions 43a and second protrusions 43b are formed as resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13. The first protrusions 43a are arranged in a matrix with spaces between them on the second main surface 5b of the heat spreader 3, which faces the resin-impregnated composite 13. The second protrusions 43b are arranged in a matrix with spaces between them on the third main surface 17a of the metal plate 15, which faces the resin-impregnated composite 13.

[0058] As a result, even if resin 25 seeps out of resin-impregnated composite 13 when pressurized under high-temperature conditions in the process of manufacturing power module 1, the seeped resin 25 will be trapped in the recesses between first protrusions 43 a on the heat spreader 3 side, as shown in Fig. 17. Similarly, on the metal plate 15 side, the seeped resin 25 will be trapped in the recesses between second protrusions 43 b (see Fig. 14). That is, the seeped resin 25 will be trapped in the recesses formed between adjacent sloped side walls 42.

[0059] Here, since the first protrusions 43a are arranged in a matrix pattern over the entire surface of the second main surface 5b of the heat spreader 3, the recesses formed between the side walls 44 of adjacent first protrusions 43a and the side walls 44 of the first protrusions 43a are arranged almost uniformly over the entire surface of the second main surface 5b.

[0060] Furthermore, since the second protrusions 43b are arranged in a matrix pattern over the entire surface of the third main surface 17a of the metal plate 15, the depressions formed between adjacent second protrusions 43b (side walls 44) are arranged almost uniformly over the entire surface of the third main surface 17a.

[0061] The recesses for capturing the resin are arranged almost uniformly over the entire surface of each of the second main surface 5 b and the third main surface 17 a, so that the captured resin can be dispersed uniformly. This makes it possible to suppress variations in the heat dissipation performance of the power module 1, and contributes to improving the heat dissipation performance of the power module 1.

[0062] In the above-described power module, the first protrusions 43 a are disposed over the entire second main surface 5 b of the heat spreader 3. The second protrusions 43 b are disposed over the entire third main surface 17 a of the metal plate 15.

[0063] As described in the fourth embodiment, the first protrusions 43a and the second protrusions 43b may be arranged in a manner that excludes the heat conduction region HR (see FIG. 13). That is, as shown in FIG. 18, the first protrusions 43a may be arranged on the second main surface 5b of the heat spreader 3 so as to surround the heat conduction region HR in a manner that excludes the heat conduction region HR.

[0064] 19 , the second protrusions 43b may be arranged on the third main surface 17a of the metal plate 15 so as to surround the heat conduction region HR, with the heat conduction region HR being excluded. This prevents the resin from impeding heat conduction, and allows the heat generated by the semiconductor element 9 to be dissipated to the heat sink 23 more effectively.

[0065] Sixth Embodiment An example of a power module according to a sixth embodiment will be described. Here, still another example of a variation of the resin trap 31 will be described.

[0066] As shown in Figures 20, 21, and 22, in the power module 1, metal fibers 45 are arranged as resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13. The metal fibers 45 are formed by processing fibrous metal into a sheet shape, such as a copper fiber sheet. The metal fibers 45 include first metal fibers 45a and second metal fibers 45b. Note that Figures 20 to 22 show the fibrous metal processed into a sheet shape as an image, and in reality, the fibers are intricately tangled together.

[0067] The first metal fibers 45a are arranged so as to be interposed between the heat spreader 3 and the resin-impregnated composite 13. The second metal fibers 45b are arranged so as to be interposed between the metal plate 15 and the resin-impregnated composite 13. In other words, the first metal fibers 45a are arranged on the side of the resin-impregnated composite 13 where the heat spreader 3 is located. The second metal fibers 45b are arranged on the side of the resin-impregnated composite 13 where the metal plate 15 is located. Note that the rest of the configuration is the same as the configuration of the power module 1 shown in FIG. 1 , so the same members are denoted by the same reference numerals, and their description will not be repeated unless necessary.

[0068] In the above-described power module 1, first metal fibers 45a and second metal fibers 45b are arranged as resin traps 31 for capturing the resin impregnated in the resin-impregnated composite 13. The first metal fibers 45a are arranged between the heat spreader 3 and the resin-impregnated composite 13. The second metal fibers 45b are arranged between the metal plate 15 and the resin-impregnated composite 13.

[0069] As a result, even if resin 25 seeps out of the resin-impregnated composite 13 when pressurized under high temperature conditions during the process of manufacturing the power module 1, the seeped resin 25 will be captured by the first metal fiber 45a or the second metal fiber 45b, respectively.

[0070] The resin 25 is trapped between the fibers of the first metal fibers 45a, which prevents a resin layer consisting only of resin that inhibits heat conduction from being formed in the region between the resin-impregnated composite 13 and the heat spreader 3. On the other hand, the first metal fibers 45a themselves form a heat conduction path.

[0071] Furthermore, since the resin 25 is trapped between the fibers of the second metal fibers 45b, it is possible to prevent a resin layer consisting only of resin that inhibits heat conduction from being formed in the region between the resin-impregnated composite 13 and the metal plate 15. On the other hand, the second metal fibers 45b themselves form a heat conduction path.

[0072] The formation of a resin layer that inhibits heat dissipation is suppressed, while the formation of a heat conduction path allows the heat generated in the semiconductor element 9 to be more effectively dissipated to the heat sink 23. As a result, the heat dissipation performance of the power module 1 can be improved.

[0073] In the above-described power module 1, the metal fibers 45 are arranged as the resin traps 31, but instead of arranging the metal fibers 45, each of the second main surface 5b of the heat spreader 3 and the third main surface 17a of the metal plate 15 may be processed into a fibrous form. Also, the first metal fibers 45a may be arranged to avoid the heat conduction region HR (see FIG. 13), and the second metal fibers 45b may be arranged to avoid the heat conduction region HR (see FIG. 13).

[0074] Seventh Embodiment In a seventh embodiment, a power conversion device to which the power module 1 described in the first to sixth embodiments is applied will be described. Although the present disclosure is not limited to a specific power conversion device, the case where the present disclosure is applied to a three-phase inverter will be described here.

[0075] 23 is a block diagram showing the configuration of a power conversion system to which the power conversion device 200 is applied. The power conversion system shown in FIG.

[0076] The power supply 300 is a DC power supply that supplies DC power to the power conversion device 200. The power supply 300 can be configured from a variety of elements. For example, the power supply 300 can be configured from a DC system, a solar cell, or a storage battery. The power supply 300 may also be configured from a rectifier circuit connected to an AC system or an AC / DC converter. The power supply 300 may also be configured from a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0077] The load 400 is a three-phase electric motor driven by AC power supplied from the power conversion device 200. The load 400 is not limited to a specific application. The load 400 is an electric motor mounted on various electrical devices. The load 400 is used as an electric motor for a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioning device, for example.

[0078] The power conversion device 200 is a three-phase inverter connected between a power source 300 and a load 400. The power conversion device 200 converts DC power supplied from the power source 300 into AC power and supplies the AC power to the load 400. As shown in Fig. 23 , the power conversion device 200 has a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal for controlling the main conversion circuit 201 to the main conversion circuit 201.

[0079] Next, a detailed description will be given of the configuration of the power conversion device 200. The main conversion circuit 201 has a switching element and a free wheel diode (neither of which is shown). The main conversion circuit 201 converts DC power supplied from the power source 300 into AC power by switching the switching element, and supplies the AC power to the load 400.

[0080] There are various specific circuit configurations for the main conversion circuit 201, but the main conversion circuit 201 according to this embodiment is a two-level three-phase full-bridge circuit. The main conversion circuit 201 is composed of six switching elements and six freewheeling diodes connected in antiparallel to each switching element.

[0081] At least one of the switching element and the free wheel diode of the main conversion circuit 201 is the switching element or the free wheel diode of the semiconductor module 202 corresponding to the power module 1 according to any one of the first to sixth embodiments.

[0082] The six switching elements form upper and lower arms, with two switching elements connected in series. Each upper and lower arm forms one phase (U phase, V phase, W phase) of the full-bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 201, are connected to the load 400.

[0083] The main conversion circuit 201 has a drive circuit (not shown) that drives each switching element. This drive circuit may be built into the semiconductor module 202, or may be configured separately from the semiconductor module 202. The drive circuit generates drive signals that drive the switching elements of the main conversion circuit 201, and supplies the signals to the control electrodes of the switching elements of the main conversion circuit 201.

[0084] More specifically, the drive circuit outputs a drive signal that turns the switching element on and a drive signal that turns the switching element off to the control electrode of each switching element in accordance with a control signal from a control circuit 203 (described later). When maintaining a switching element in the on state, the drive signal is a voltage signal (on signal) that is equal to or higher than the threshold voltage of the switching element. When maintaining a switching element in the off state, the drive signal is a voltage signal (off signal) that is equal to or lower than the threshold voltage of the switching element.

[0085] The control circuit 203 controls the switching elements of the main conversion circuit 201 so that the desired power is supplied to the load 400. More specifically, the control circuit 203 calculates the time (on time) that each switching element of the main conversion circuit 201 should be in the on state based on the power to be supplied to the load 400. For example, the main conversion circuit 201 can be controlled by PWM control, which modulates the on time of the switching elements according to the voltage to be output.

[0086] The control circuit 203 outputs a control command (control signal) to a drive circuit provided in the main conversion circuit 201 so that an ON signal is output to a switching element that should be in an ON state at each point in time, and an OFF signal is output to a switching element that should be in an OFF state at each point in time. In accordance with this control signal, the drive circuit outputs an ON signal or an OFF signal as a drive signal to the control electrode of each switching element.

[0087] In the power conversion device 200 according to this embodiment, the power module 1 according to any one of the first to sixth embodiments is applied as the semiconductor module 202 that constitutes the main conversion circuit 201. This allows the main conversion circuit 201 to dissipate heat effectively, which can contribute to stabilizing the operation of the power conversion device 200.

[0088] In the present embodiment, an example in which the present disclosure is applied to a two-level three-phase inverter has been described, but the present disclosure is not limited to this and can be applied to various power conversion devices. In the present embodiment, a two-level power conversion device is described, but a three-level or multi-level power conversion device may also be used. In addition, when supplying power to a single-phase load, the present disclosure may also be applied to a single-phase inverter. Furthermore, when supplying power to a DC load, etc., the present disclosure may also be applied to a DC / DC converter or an AC / DC converter.

[0089] Furthermore, the power conversion device to which the present disclosure is applied is not limited to cases in which the above-mentioned load is an electric motor, but can also be used, for example, as a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a non-contact power supply system, and can also be used as a power conditioner for a solar power generation system, a power storage system, etc.

[0090] The power module 1 described in each embodiment can be combined in various ways as needed. For example, the resin trap 31 may be a combination of the recess 33 and the protrusion 41. Alternatively, the recess 33 and the metal fiber 45 may be combined. Alternatively, the protrusion 41 and the metal fiber 45 may be combined. Furthermore, these three may be combined.

[0091] The above description has been given with reference to an example in which the resin trap 31 is provided both between the resin-impregnated composite 13 and the heat spreader 3 and between the resin-impregnated composite 13 and the metal plate 15. The resin trap 31 may be provided at least either between the resin-impregnated composite 13 and the heat spreader 3 or between the resin-impregnated composite 13 and the metal plate 15. That is, the resin trap 31 may be provided on either the side of the resin-impregnated composite 13 where the heat spreader 3 is located or the side of the resin-impregnated composite 13 where the metal plate 15 is located.

[0092] The embodiments disclosed herein are examples and are not intended to be limiting. The scope of the present disclosure is defined by the scope of the claims, not the scope described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0093] The present disclosure is effectively utilized in a power module having a resin-impregnated composite.

[0094] 1 Power module, 3 Heat spreader, 5a First main surface, 5b Second main surface, 7 Bonding material, 9 Semiconductor element, 11a Lead, 11b Lead, 13 Resin-impregnated composite, 15 Metal plate, 17a Third main surface, 17b Fourth main surface, 19 Wire, 21 Sealant, 23 Heat sink, 25 Resin, 31 Resin trap, 33 Recess, 34 Side wall, 35a First recess, 35b Second recess, 37a First groove, 37b Second groove, 39a First hole, 39b Second hole, 41 Protrusion, 42 Side wall, 43a First protrusion, 43b Second protrusion, 45 Metal fiber, 45a First metal fiber, 45b Second metal fiber, S Circular frame, HR Heat conduction area, BL Air bubble, 200 Power conversion device, 201 Main conversion circuit, 202 semiconductor module, 203 control circuit, 300 power supply, 400 load.

Claims

1. A heat spreader having opposing first and second main surfaces, a semiconductor element bonded to the first main surface of the heat spreader, a resin-impregnated composite bonded to the second main surface of the heat spreader, a metal plate having a third main surface, the third main surface being bonded to the side of the resin-impregnated composite opposite to the side to which the heat spreader is bonded, and a sealing material for sealing the semiconductor element, the heat spreader, the resin-impregnated composite, and the metal plate, and having a resin trap for capturing the resin impregnated in the resin-impregnated composite between at least one of the resin-impregnated composite and the heat spreader and between the resin-impregnated composite and the metal plate, a power module.

2. The power module according to claim 1, wherein the resin trap includes a recess having side walls formed on at least one of the second main surface of the heat spreader and the third main surface of the metal plate.

3. The power module according to claim 2, wherein the recess includes a plurality of holes formed at intervals from each other.

4. The power module according to claim 3, wherein the recess includes the hole having side walls with a gradient such that an opening size increases toward the resin-impregnated composite.

5. The power module according to claim 2, wherein the recess includes a groove extending in one direction.

6. The power module according to claim 5, wherein the recess includes the groove having side walls with a gradient that expands toward the resin-impregnated composite.

7. The power module according to claim 1, wherein the resin trap includes a plurality of protrusions formed on at least one of the second main surface of the heat spreader and the third main surface of the metal plate and arranged at intervals from each other.

8. The power module according to claim 1, wherein the resin trap includes metal fibers interposed between at least one of the resin-impregnated composite and the heat spreader and between the resin-impregnated composite and the metal plate.

9. The resin trap is formed in an outer region located outside a heat conduction region that conducts heat from the heat generated by the semiconductor element in a manner that spreads obliquely at 45 degrees from an end portion of the semiconductor element toward the metal plate through the heat spreader, the resin-impregnated composite, and the metal plate, according to any one of claims 1 to 8, of the power module.

10. The resin trap is formed between both the resin-impregnated composite and the heat spreader, and between the resin-impregnated composite and the metal plate, according to any one of claims 1 to 9, of the power module.

11. The metal plate has a fourth main surface facing the third main surface, and the sealing material seals the metal plate in a manner that exposes the fourth main surface, according to any one of claims 1 to 10, of the power module.

12. A radiator is to be joined to the fourth main surface of the metal plate, according to claim 11, of the power module.

13. A power conversion device comprising a main conversion circuit that has the power module according to any one of claims 1 to 12 and converts and outputs input power, and a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

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