Semiconductor device

Abstract

A semiconductor device (100) comprises: a power module (101) with a plurality of semiconductor elements; and a heat sink (14) with a cooling surface (20) to which the power module (101) is thermally connected to a solder material via a connecting element (15). The plurality of semiconductor elements are arranged in such a way that they do not overlap when viewed in a direction perpendicular to the cooling surface (20). The cooling surface (20) has a recessed section (17), and the recessed section (17) is in such a way that it overlaps with the connecting element (15) provided between the cooling surface (20) and the power module (101), and that it does not overlap with any of the plurality of semiconductor elements when viewed in a direction perpendicular to the cooling surface (20).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a semiconductor device. BACKGROUND

[0002] In recent years, the capacities of semiconductor devices equipped with high-performance semiconductor elements have been gradually increased. To conduct a large current through a semiconductor element of a semiconductor device with increased capacity, the heat generated in the semiconductor element must be efficiently transferred to a cooler. Given this need, in such a semiconductor device with increased capacity, it is necessary to reduce the thermal resistance of a connecting element provided between the semiconductor element and the cooler, which connects the structural elements.

[0003] A semiconductor device configuration that achieves a reduction in the thermal resistance of a connecting member with a solder material has been disclosed (see, for example, Patent Document 1). In the configuration disclosed in Patent Document 1, a plating layer, such as nickel or copper plating, is provided on a surface of a power module to be connected to a cooler. This improves wettability by the solder. This improvement achieves the following effects: improving the reliability of the connection between the power module and the cooler and reducing the thermal resistance of the connecting member. CITATION LISTPATENT DOCUMENT

[0004] Patent Document 1: Japanese Patent No. 6183556 SUMMARY OF THE INVENTION OBJECT OF THE INVENTION

[0005] In the above-mentioned Patent Document 1, solderability can be improved because the plating layer is provided on the surface of the power module to be connected. The semiconductor device provided with the plating layer must be subjected to a soldering technique using formic acid reduction equipment or a vacuum soldering technique using a high-activity flux. However, either technique results in a change in solder wettability, and the connecting member includes the solder material. The occurrence of such a change in solder wettability leads to the generation of a solder hole. Specifically, in the case of providing a plating layer, gas is generated from an organic component contained in the plating layer at a temperature at which the solder is melted, and if the gas is not discharged to the outside, the gas forms a solder cavity.If such a solder void is created between a semiconductor element and the cooler, the solder void will hinder cooling of the semiconductor element and increase thermal resistance. Consequently, the problem arises that the quality of the semiconductor device may be reduced.

[0006] In view of this problem, it is an object of the present disclosure to provide a semiconductor device in which the connection quality of a connecting element with a solder material is improved and in which a reduction in the thermal resistance of the connecting element is realized. MEANS FOR SOLVING THE TASK

[0007] A semiconductor device according to the present disclosure includes: a power module having a plurality of semiconductor elements; and a cooler having a cooling surface to which the power module is thermally connected via a connecting member with a solder material. The plurality of semiconductor elements are arranged at positions such that they do not overlap with each other when viewed in a direction perpendicular to the cooling surface, the cooling surface has a depressed portion, and the depressed portion is arranged at a position such that it overlaps with the connecting member provided between the cooling surface and the power module and does not overlap with any of the plurality of semiconductor elements when viewed in the direction perpendicular to the cooling surface. EFFECT OF THE INVENTION

[0008] The semiconductor device according to the present disclosure includes: a power module having a plurality of semiconductor elements; and a cooler having a cooling surface to which the power module is thermally connected via a connecting member with a solder material. The plurality of semiconductor elements are arranged at positions such that they do not overlap in a direction perpendicular to the cooling surface, the cooling surface having a depressed portion, and the depressed portion is arranged at a position such that it overlaps with the connecting member provided between the cooling surface and the power module and does not overlap with any of the plurality of semiconductor elements when viewed in the direction perpendicular to the cooling surface.Consequently, the recessed portion serves as a path through which gas generated between the power module and the cooler is discharged to the outside via the connecting member at the time of connecting the power module and the cooler to each other. This path inhibits the generation of a void remaining between the cooler and one of the plurality of semiconductor elements when the connecting member solidifies. Therefore, the connection quality of the connecting member can be improved, and a reduction in the thermal resistance of the connecting member can be realized. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. 1 is a plan view schematically showing a semiconductor device according to Embodiment 1. [ Fig. 2] Fig. 2 is a sectional view of the semiconductor device taken at the section position AA in Fig. 1 was recorded. [ Fig. 3] Fig. 3 is a sectional view schematically showing another semiconductor device according to Embodiment 1. [ Fig. 4] Fig. 4 is a sectional view schematically showing a semiconductor device according to Embodiment 2. [ Fig. 5] Fig. 5 is a schematic sectional view of a semiconductor device according to Embodiment 3. [ Fig. 6] Fig. 6 is a schematic plan view of a semiconductor device according to Embodiment 4. [ Fig. 7] Fig. 7 is a schematic plan view of a semiconductor device according to Embodiment 5. [ Fig. 8] Fig. Fig. 8 is a sectional view of the semiconductor device taken at the cutting position BB in Fig. 7. [ Fig. 9] Fig. 9 is a plan view schematically showing another semiconductor device according to Embodiment 5. [ Fig. 10] Fig. 10 is a sectional view schematically showing a semiconductor device according to Embodiment 6. DESCRIPTION OF THE EMBODIMENTS

[0009] Hereinafter, semiconductor devices according to embodiments of the present disclosure will be described with reference to the drawings. The description will be given while the same or related elements and portions in the drawings are denoted by the same reference numerals. Embodiment 1

[0010] Fig. Fig. 1 is a schematic plan view showing a semiconductor device 100 according to Embodiment 1. With respect to a sealing resin 13, Fig. 1 only its external form. Fig. 2 is a sectional view of the semiconductor device 100 taken at the section position AA in Fig. 1. The semiconductor device 100 is, for example, a device for converting input current from direct current to alternating current or from alternating current to direct current or for converting input voltage to another voltage. <Halbleitervorrichtung 100>

[0011] As in Fig. 2, the semiconductor device 100 includes: a power module 101 having a plurality of semiconductor elements; and a cooler 14. The cooler 14 has a cooling surface 20 to which the power module 101 is thermally connected via a connecting element 15 with a solder material. In this way, the power module 101 and the cooler 14 are connected and integrated to form the semiconductor device 100. The plurality of semiconductor elements includes two semiconductor elements arranged to be adjacent to each other, wherein one of the two semiconductor elements is defined as a first semiconductor element and another of the two semiconductor elements is defined as a second semiconductor element. As shown in Fig. 1, the power module 101 in the present embodiment includes first semiconductor elements 1 and 2 and second semiconductor elements 5 and 6. Although the first semiconductor element is thus composed of the two first semiconductor elements 1 and 2, and the second semiconductor element is thus composed of the two second semiconductor elements 5 and 6, the present disclosure is not limited thereto, and both the first semiconductor element and the second semiconductor element may be composed of one semiconductor element. <Leistungsmodul 101>

[0012] The power module 101 includes the first semiconductor elements 1 and 2, a first heat spreader 3, the second semiconductor elements 5 and 6, a second heat spreader 7, an insulating member 11, a copper plate 12, and the sealing resin 13. The first semiconductor elements 1 and 2 are each electrically connected to a one-sided surface of the first heat spreader 3 via a chip connection member (not shown). The second semiconductor elements 5 and 6 are each electrically connected to a one-sided surface of the second heat spreader 7 via a chip connection member (not shown). The second heat spreader 7 is arranged side by side with the first heat spreader 3 with a gap therebetween on a same plane. For each of the chip connection members, for example, a solder or a sintered material composed of Ag nanoparticles or Cu nanoparticles is used. As shown in Fig. As shown in Figure 2, the insulating member 11 has one surface thereof thermally bonded to another surface of the first heat spreader 3 and another surface of the second heat spreader 7. The copper plate 12 has one surface thereof thermally bonded to another surface of the insulating member 11. The sealing resin 13, in a state where another surface of the copper plate 12 is exposed, serves as a cover for the first heat spreader 3, the second heat spreader 7, the first semiconductor elements 1 and 2, the second semiconductor elements 5 and 6, and the insulating member 11. The heat generated during operation of each of the semiconductor elements is transferred, in this order, to the corresponding chip connection member, the corresponding element of the first heat spreader 3 and the second heat spreader 7, the insulating member 11, and the copper plate 12.The heat is then transferred via the connecting element 15 to the cooling surface 20 and dissipated by the cooler 14.

[0013] In the present embodiment, the power module 101 has a configuration of a so-called 2-in-1 module, and as shown in Fig. As shown in Figure 1, the first semiconductor element 1 and the second semiconductor element 5 are connected in antiparallel as switching elements, and the first semiconductor element 2 and the second semiconductor element 6 are connected in antiparallel as rectifying elements, whereby the power module 101 has two pairs of elements. The configuration of the power module 101 is not limited to this, and a required number of first semiconductor elements and a required number of second semiconductor elements can be mounted according to the use of the semiconductor device 100.

[0014] Configurations of lead frames as connecting elements in the power module 101 will be described. In the present embodiment, the power module 101 includes a first lead frame 4, a second lead frame 8, a third lead frame 9, and a fourth lead frame 10. The configurations of the lead frames are not limited thereto, and in a case where the number of mounted semiconductor elements is changed as described above, the configurations of the lead frames may be changed according to the number of mounted semiconductor elements.

[0015] The first lead frame 4 has one end electrically connected to the one-sided surface of the first heat spreader 3 via a lead connection member (not shown); and another end protruding from the sealing resin 13. The second lead frame 8 electrically connects to a one-sided surface of each of the first semiconductor elements 1 and 2 via a corresponding chip connection member (not shown), and electrically connects to the one-sided surface of the second heat spreader 7 via lead connection members (not shown) to electrically connect these one-sided surfaces to each other. The third lead frame 9 has one end electrically connected to a one-sided surface of each of the second semiconductor elements 5 and 6 via a corresponding chip connection member (not shown); and another end protruding from the sealing resin 13.The fourth lead frame 10 has one end electrically connected to the one-sided surface of the second heat spreader 7 via a lead connecting member (not shown); and the other end protruding from the sealing resin 13. The connecting members of the leads are realized, for example, by connecting members each comprising a solder material to ensure electrical connection between the lead frames and the heat spreaders. Without being limited to the connection via the lead connecting members, metal bonding using an ultrasonic wave, a laser, or the like may be employed.

[0016] Each of the elements of the power module 101 will be described in detail. For the first semiconductor element 1 and the second semiconductor element 5, for example, a power semiconductor element that is a semiconductor element for power control, such as an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field-effect transistor (MOSFET), is used. The present embodiment uses a configuration in which: a switching element without a parasitic diode, such as an IGBT, is used; and a rectifying element, such as a freewheeling diode, is provided in parallel. However, without being limited to this configuration, a reverse-conducting IGBT (RC-IGBT) in which a switching element and a freewheeling diode are integrated may be used. Alternatively, a configuration in which a MOSFET is used and a parasitic diode of the MOSFET is used as a freewheeling diode may be used.In case of using an RC-IGBT or the like, each of the first semiconductor elements and the second semiconductor elements consists of a semiconductor element.

[0017] The first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 are formed on semiconductor substrates each made of a material such as silicon, silicon carbide (SiC), or gallium nitride (GaN). Wide bandgap semiconductor elements each made of a material such as silicon carbide with a wider bandgap than silicon can be used. By using such wide bandgap semiconductor elements, a temporal change amount di / dt of the current generated during switching can be made larger than when using elements each made of silicon. In addition, each of the wide bandgap semiconductor elements has a low on-resistance and a high allowable current density, has low power loss, and generates little heat, so the chip area can be reduced. Since the chip area is reduced, the power module 101 can be downsized.

[0018] The first heat spreader 3, the second heat spreader 7, the first lead frame 4, the second lead frame 8, the third lead frame 9, and the fourth lead frame 10 are each formed from any metal material with excellent electrical conductivity. Among the metals with excellent electrical conductivity, a copper material is particularly desirable as the material of these spreaders and lead frames from the viewpoints of electrical resistance, processability, cost, and the like. Here, the copper material refers to pure copper or a copper alloy containing copper as a main component.

[0019] As the sealing resin 13, a resin having a linear expansion coefficient close to that of each of the first heat spreader 3, the second heat spreader 7, the first lead frame 4, the second lead frame 8, the third lead frame 9, and the fourth lead frame 10 is preferably used to prevent an increase in thermal degradation force due to the difference between the linear expansion coefficients. Since pure copper has a linear expansion coefficient of 16 [ppm / K] to 17 [ppm / K], the linear expansion coefficient of the sealing resin 13 is preferably 15 [ppm / K] to 18 [ppm / K]. The sealing resin 13 is, for example, an inorganic filler contained in a thermosetting resin such as an epoxy resin.

[0020] The insulating member 11 must have heat dissipation capability, that is, the heat generated during the operation of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 must be transferred and dissipated to the cooling device 14, while at the same time ensuring electrical insulation between the semiconductor element side and the copper plate 12 side. The insulating member 11 is obtained, for example, by filling a thermosetting resin with an inorganic filler having high thermal conductivity and insulating properties. The insulating member 11 adheres the copper plate 12 and both the first heat spreader 3 and the second heat spreader 7 through a thermosetting reaction of the resin.Here, the insulating member 11 is formed from a material that has both heat dissipation properties, insulation properties, and adhesive properties, and has a structure in which an inorganic powder filler with high thermal conductivity, such as ceramic particles, is contained in a thermosetting resin, such as an epoxy resin. Suitable inorganic fillers with high thermal conductivity include ceramic particles of aluminum nitride, silicon nitride, boron nitride, aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, zinc oxide, titanium oxide, or the like. Each of these types of inorganic fillers can be used individually, or two or more of these types of inorganic fillers can be mixed and used. <Kühler 14>

[0021] The cooler 14, with the cooling surface 20 to which the power module 101 is thermally connected, must have high cooling performance. The cooler 14 includes a plurality of heat dissipation fins (not shown) to efficiently dissipate the heat transferred from the power module 101. The heat dissipation fins are provided, for example, on a portion of the cooler 14 on a side opposite the side of the power module 101. The cooler 14 may be a liquid cooler or an air cooler. In the present embodiment, the cooler 14 is realized by a metal heat sink in the form of a flat plate. However, the cooler 14 is not limited to this and may be a liquid cooler having a flow path in which a cooling liquid flows. The cooler 14 is preferably formed, for example, from any material selected from the group consisting of copper, aluminum, copper alloys, and aluminum alloys.A particularly suitable material for the cooler 14 is aluminum or an aluminum alloy as an aluminum-containing alloy, both of which are lightweight and have excellent processability. In a case where the material of the cooler 14 is aluminum or an aluminum alloy, the weight of the semiconductor device 100 can be reduced. Furthermore, the productivity of the semiconductor device 100 can be improved.

[0022] The surface of the other side of the copper plate 12 of the power module 101, which is exposed from the sealing resin 13, is thermally connected to the cooling surface 20 of the cooler 14 via the connecting member 15. The cooling surface 20 of the cooler 14 must have high solder wettability in order to solder the power module 101 to the cooling surface 20 via the connecting member 15 with high connection quality. Therefore, it is desirable that the material of the cooler 14 be copper with solder wettability. However, in a case where the material of a body portion of the cooler 14 is aluminum or an aluminum alloy as described above, it is optimal to provide a plating layer 16 with solder wettability as the cooling surface 20 of the cooler 14, using copper as the material of the plating layer 16.Instead of providing the plating layer 16 directly on the aluminum or aluminum alloy, a nickel plating layer (not shown) may be provided as a base plating layer to improve the close contact properties of plating and the solder wettability of the surface.

[0023] In the present embodiment, the material of the radiator 14 is aluminum or an aluminum alloy, and, as shown in Fig. As shown in Figure 2, the plating layer 16 is provided on the power module 101 side of the cooler 14. Therefore, the cooling surface 20 is a surface of the plating layer 16 having solder wettability. That is, among the joint surfaces where the power module 101 and the cooler 14 are joined via the joint member 15, one joint surface is the surface on the other side of the copper plate 12, and the other joint surface, that is, the cooling surface 20, is the plating layer 16 provided on the surface of the cooler 14. <Vertiefter Abschnitt 17 der Kühlfläche 20>

[0024] A depressed portion 17 of the cooling surface 20, which is a main portion of the present disclosure, will be described. The first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 as a plurality of semiconductor elements are arranged at such positions that they do not overlap with each other when viewed in a direction perpendicular to the cooling surface 20. The cooling surface 20 has the depressed portion 17. The depressed portion 17 is arranged at such a position that it overlaps with the connecting member 15 provided between the cooling surface 20 and the power module 101 and does not overlap with any of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 when viewed in the direction perpendicular to the cooling surface 20. The depressed portion 17 penetrates the plating layer 16, so that an element on a lower side with respect to the plating layer 16 is exposed.The exposed member on the lower side has lower solder wettability than the plating layer 16. The exposed portion of the lower side member is a surface with a recessed portion 18. In the present embodiment, the exposed member on the lower side is made of aluminum or an aluminum alloy.

[0025] In the case of providing the plating layer 16, gas is generated from an organic component contained in the plating layer 16 at a temperature at which the solder is melted, and if the gas is not discharged to the outside, the gas forms a solder void. If such a solder void is generated between one of the semiconductor elements and the cooler 14, the cooling of the semiconductor element is hindered by the solder void, and the thermal resistance is increased. Consequently, the quality of the semiconductor device 100 is reduced. Cases where such a void is generated are not limited to the case where a void is generated by the plating layer 16, and also include a case where: at the time of melting of the connecting element 15, a gap exists between the connecting element 15 and another element; and a void is caused by the portion at the gap.

[0026] However, since the recessed portion 17 is located at a position on the cooling surface 20 such that it does not overlap with any of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6, the recessed portion 17 serves as a path through which gas generated between the power module 101 and the cooler 14 is discharged to the outside via the connecting member 15 at the time of connecting the power module 101 and the cooler 14 to each other. Consequently, even if a solder void is generated, the solder void is eliminated by the discharge to the outside through the recessed portion 17. Since the solder void is eliminated by the discharge to the outside through the recessed portion 17, it is possible to prevent the generation of a void remaining between the cooler 14 and any of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 when the connecting member 15 solidifies.Since the generation of a void remaining between the cooler 14 and each of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 is prevented, the space between the cooler 14 and each of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 is filled with the interconnecting member 15 and the plating layer 16. Therefore, the connection quality of the interconnecting member 15 with the solder material can be improved, and a reduction in the thermal resistance of the interconnecting member 15 can be achieved. In addition, since the space between the cooler 14 and each of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 is filled with the interconnecting member 15 and the plating layer 16, the heat generated in each of the semiconductor elements can be efficiently transferred to the cooler 14.

[0027] In the present embodiment, the recessed portion 17 is located between the first heat spreader 3 and the second heat spreader 7 at a position where it does not overlap with either the first heat spreader 3 or the second heat spreader 7, for example, in the direction perpendicular to the cooling surface 20. With such a configuration, the recessed portion 17 is not present between the radiator 14 and either the first heat spreader 3 or the second heat spreader 7, and the space between the radiator 14 and each of the first heat spreader 3 and the second heat spreader 7 is filled with the interconnection member 15 and the plating layer 16. Therefore, not only the heat generated in each of the semiconductor elements but also the heat generated in each of the lead frames and the heat spreader can be efficiently transferred to the radiator 14.The location of the recessed portion 17 is not limited thereto, and the recessed portion 17 may be located in another area as long as: the heat transfer through the recessed portion 17 is not hindered; and the area is located in a position where it does not overlap with any of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6. Even if the recessed portion 17 is located in another area, a reduction in the thermal resistance of the connecting member 15 and prevention of a solder void can be achieved.

[0028] In the present embodiment, the exposed member on the lower side is made of aluminum or an aluminum alloy and has lower solder wettability than the plating layer 16. In such a configuration, the connecting member 15 and the surface with the recessed portion 18 are not connected to each other in the recessed portion 17, whereby a path through which gas is discharged to the outside can be securely formed in the recessed portion 17.

[0029] In the present embodiment, the recessed portion 17 is a groove extending outward from the connecting member 15 and provided between the cooling surface 20 and the power module 101, viewed in the direction perpendicular to the cooling surface 20. Since the recessed portion 17 in such a configuration has a portion extending outward from the connecting member 15, gas can be easily discharged to the outside. Without being limited to the configuration in which the recessed portion 17 is arranged to extend outward from the connecting member 15, the recessed portion 17 may be arranged only inside the connecting member 15. In a case where the recessed portion 17 is arranged inside the connecting member 15, gas cannot be discharged to the outside, but it can be discharged into the recessed portion 17.In addition, in the case where the recessed portion 17 is disposed only inside the connecting member 15, water, foreign matter, or the like can be prevented from penetrating into the interior of the semiconductor device 100 from the outside through the recessed portion 17.

[0030] An example of a method for forming the recessed portion 17 in the cooler 14 will be described. The plating layer 16 is provided on the entirety of the cooler 14, and then a part of the plating layer 16 in a region to be formed as the recessed portion 17 is cut and removed, whereby the recessed portion 17 can be formed. By forming the recessed portion 17 in this way, the recessed portion 17 can be formed easily and inexpensively. In the present embodiment, the recessed portion 17 penetrates the plating layer 16, so that the element on the lower side with respect to the plating layer 16 is exposed, and by adopting this molding method, the recessed portion 17 can be easily molded, whereby the productivity of the semiconductor device 100 can be improved.The method for forming the recessed portion 17 is not limited thereto and may be a method including: masking a portion where the recessed portion 17 is to be formed at the time of plating; and plating portions of the cooler 14 except for the portion where the recessed portion 17 is to be formed.

[0031] In the present embodiment, the material of the cooler 14 is aluminum or an aluminum alloy, and the plating layer 16 is provided on the power module 101 side of the cooler 14. However, the material of the cooler 14 may be, but is not limited to, copper or a copper alloy, and a plating layer 16 containing nickel or tin may be provided on the power module 101 side of the cooler 14.

[0032] In the case where the material of the cooler 14 is copper or a copper alloy, the recessed portion 17 may be provided in the cooling surface 20, which is the surface on the power module 101 side of the cooler 14 made of the copper or the copper alloy, without providing the plating layer 16, as shown in FIG. Fig. 3 shown. Fig. 3 is a schematic sectional view showing another semiconductor device 100 according to Embodiment 1, and shows a cross section of the other semiconductor device 100 taken at the same position as in Fig. 2. In this configuration, the plating layer 16 is not provided, and therefore, gas generation from the plating layer 16 does not occur. However, there is also a case where: at the time of melting the connecting member 15, a gap exists between the connecting member 15 and another member; and a void is caused by the portion at the gap. This case is addressed; that is, such a void can be eliminated by discharging the depressed portion 17 to the outside. An aluminum layer may be formed on the surface 18 of the depressed portion 17 by sputtering or the like to surely form a path for eliminating a void by discharging in the depressed portion 17.

[0033] As described above, the semiconductor device 100 according to Embodiment 1 includes: the power module 101 including the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6; and the cooler 14 including the cooling surface 20 to which the power module 101 is thermally connected via the connecting member 15 with the solder material. The first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 are arranged at positions such that they do not overlap in the direction perpendicular to the cooling surface 20. The cooling surface 20 has the recessed portion 17, and the recessed portion 17 is positioned such that it overlaps with the connecting member 15 provided between the cooling surface 20 and the power module 101 and does not overlap with any of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6, as viewed in the direction perpendicular to the cooling surface 20.Consequently, the recessed portion 17 serves as a path through which gas generated between the power module 101 and the cooler 14 is discharged to the outside via the connecting member 15 at the time of connecting the power module 101 and the cooler 14 to each other. This path inhibits the generation of a void remaining between the cooler 14 and any one of the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 when the connecting member 15 solidifies. Therefore, the connection quality of the connecting member 15 can be improved, and a reduction in the thermal resistance of the connecting member 15 can be realized.

[0034] There is a case where: the power module 101 includes the first heat spreader 3 having a one-sided surface to which the first semiconductor elements 1 and 2 are electrically connected, and the second heat spreader 7 is arranged adjacent to the first heat spreader 3 with a gap therebetween on a same plane, the second heat spreader 7 having a one-sided surface to which the second semiconductor elements 5 and 6 are electrically connected; and the depressed portion 17 is arranged between the first heat spreader 3 and the second heat spreader 7 at a position where it does not overlap the first heat spreader 3 or the second heat spreader 7, for example, in the direction perpendicular to the cooling surface 20.In this case, the recessed portion 17 is not present between the cooler 14 and either the first heat spreader 3 or the second heat spreader 7, and thus not only the heat generated in each of the semiconductor elements but also the heat generated in each of the lead frames and the heat spreader can be efficiently transferred to the cooler 14.

[0035] In a case where the cooling surface 20 is a surface of the plating layer 16 having solder wettability and the depressed portion 17 penetrates the plating layer 16, for example, such that an element is exposed on a lower side with respect to the plating layer 16, the power module 101 can be soldered to the cooler 14 with high connection quality, and the depressed portion 17 can be easily and inexpensively formed.

[0036] In a case where the exposed member on the lower side has lower solder wettability than the plating layer 16, the connecting member 15 and the surface of the recessed portion 18 in the recessed portion 17 are not connected to each other, whereby a path through which gas is discharged to the outside can be securely formed in the recessed portion 17. In a case where the exposed member on the lower side is made of aluminum or an aluminum alloy, the weight of the semiconductor device 100 can be reduced and the productivity of the semiconductor device 100 can be improved.

[0037] In a case where the recessed portion 17 is a groove extending outward from the connecting member 15 provided between the cooling surface 20 and the power module 101 as viewed in the direction perpendicular to the cooling surface 20, the recessed portion 17 has a portion extending outward from the connecting member 15, and thus gas can be easily discharged to the outside. Embodiment 2

[0038] A semiconductor device 100 according to Embodiment 2 will be described. Fig. 4 is a schematic sectional view of the semiconductor device 100 according to Embodiment 2 and a sectional view of the semiconductor device 100 taken at the same position as in Fig. 2. The semiconductor device 100 according to Embodiment 2 has a configuration in which the cross-sectional shape of a recessed portion 17 differs from that in Embodiment 1.

[0039] The recessed portion 17 is also formed in the exposed member on the lower side. The surface 18 of the recessed portion in the recessed portion 17 is shifted further toward the cooler 14 side from a portion on the cooler 14 side of the plating layer 16. In such a configuration, the cross-sectional area of ​​the recessed portion 17 can be made larger than the cross-sectional area of ​​the recessed portion 17 described in Embodiment 1. Since the cross-sectional area of ​​the recessed portion 17 is made larger, gas generated at the time of connecting the power module 101 and the cooler 14 to each other via the connecting member 15 can be discharged to the outside more efficiently.

[0040] In the present embodiment, the cross-sectional shape of the recessed portion 17 is rectangular. However, the cross-sectional shape of the recessed portion 17 is not limited to a rectangular shape. The recessed portion 17 only needs to function as a path through which gas generated between the power module 101 and the radiator 14 is discharged to the outside. Therefore, the cross-sectional shape of the recessed portion 17 can be, for example, a V-shape or a U-shape.

[0041] An example of a method for forming the recessed portion 17 in the radiator 14 will be described. The plating layer 16 is provided on the entire radiator 14, and then parts of the plating layer 16 and the radiator 14 in a region to be formed as the recessed portion 17 are cut and removed, whereby the recessed portion 17 can be formed. By forming the recessed portion 17 in this way, the recessed portion 17 can be formed easily and inexpensively.The method for forming the depressed portion 17 is not limited thereto and may be a method comprising: providing in advance a groove to serve as the depressed portion 17, the groove being provided at a portion of the radiator 14 where the depressed part 17 is to be formed; covering the groove portion where the depressed part 17 is to be formed at the time of plating; and plating parts of the radiator 14 except for the part where the depressed part 17 is to be formed. Embodiment 3

[0042] A semiconductor device 100 according to Embodiment 3 will be described. Fig. 5 is a schematic sectional view of the semiconductor device 100 according to Embodiment 3 and a sectional view of the semiconductor device 100 taken at the same position as in Fig. 2. The semiconductor device 100 according to Embodiment 3 has a configuration in which a module-side recessed portion 19 is provided in the power module 101.

[0043] A surface on the connecting member 15 side of the power module 101 has the module-side recessed portion 19. The module-side recessed portion 19 is arranged at a position where it overlaps, for example, with the connecting member 15 provided between the cooling surface 20 and the power module 101, and does not overlap with any of the plurality of semiconductor elements when viewed in the direction perpendicular to the cooling surface 20. In the present embodiment, the module-side recessed portion 19 is located between: the first semiconductor elements 1 and 2; and the second semiconductor elements 5 and 6.

[0044] The module-side recessed portion 19 is a path through which gas generated at the time of connecting the power module 101 and the cooler 14 to each other via the connecting member 15 is discharged to the outside. With such a configuration, the path through which gas is discharged to the outside can be provided in addition to the recessed portion 17. Since the path through which gas is discharged to the outside is wider, gas generated at the time of connecting the power module 101 and the cooler 14 to each other can be discharged to the outside more efficiently than in Embodiment 1.

[0045] In the present embodiment, the module-side recessed portion 19 is located on the power module 101 side relative to the recessed portion 17. However, the location of the module-side recessed portion 19 is not limited to this. If necessary, the module-side recessed portion 19 may be arranged in a position other than the above. Also, the number of the module-side recessed portions 19 is not limited to one, and a plurality of the module-side recessed portions 19 may be provided.

[0046] In the present embodiment, the cross-sectional shape of the module-side recessed portion 19 is rectangular. However, the cross-sectional shape of the module-side recessed portion 19 is not limited to a rectangular shape. The module-side recessed portion 19 only needs to function as a path through which gas generated between the power module 101 and the radiator 14 is discharged to the outside. Therefore, the cross-sectional shape of the module-side recessed portion 19 can be a shape such as a V-shape or a U-shape.

[0047] In the present embodiment, an example in which the module-side recessed portion 19 is provided for the semiconductor device 100 described in Embodiment 1 has been described. However, without being limited thereto, the module-side recessed portion 19 may be provided for the semiconductor device 100 described in Embodiment 2. Embodiment 4

[0048] A semiconductor device 100 according to Embodiment 4 will be described. Fig. Fig. 6 is a plan view schematically showing the semiconductor device 100 according to Embodiment 4. Regarding the sealing resin 13, Fig. 6 only its external form. Fig. 6 does not show the lead frames. The semiconductor device 100 according to Embodiment 4 has a configuration in which a plurality of semiconductor elements and a plurality of recessed portions are provided.

[0049] In the present embodiment, the power module 101 has a configuration of a so-called 6-in-1 power module. On the top side in Fig. 6, first semiconductor elements 1a, 1b and 1c are arranged on the first heat spreader 3 with gaps between the first semiconductor elements 1a, 1b and 1c in the lateral direction of the first heat spreader 3. On the lower side in Fig. 6, second semiconductor elements 5a, 5b, and 5c are provided on second heat spreaders 7a, 7b, and 7c, respectively. The first semiconductor elements 1a, 1b, and 1c are provided at and around the centers of the respective three sections obtained by dividing the first heat spreader 3 into three sections in the lateral direction.

[0050] The arrangement of the recessed portions will be described. The recessed portion 17 is located between the first heat spreader 3 and the second heat spreaders 7a, 7b, and 7c at a position where it does not overlap with the first heat spreader 3 or the second heat spreaders 7a, 7b, and 7c in the direction perpendicular to the cooling surface 20. A recessed portion 17a is located between the second heat spreaders 7a and 7b at a position where it does not overlap with any of the second heat spreaders 7a and 7b, for example, in the direction perpendicular to the cooling surface 20. A recessed portion 17b is located between the second heat spreaders 7b and 7c at a position where it does not overlap with any of the second heat spreaders 7b and 7c, for example, in the direction perpendicular to the cooling surface 20.A recessed portion 17c is located between the first semiconductor elements 1a and 1b at a position where it does not overlap with any of the first semiconductor elements 1a and 1b, for example, in the direction perpendicular to the cooling surface 20. A recessed portion 17d is located between the first semiconductor elements 1b and 1c at a position where it does not overlap with any of the first semiconductor elements 1b and 1c, for example, in the direction perpendicular to the cooling surface 20.

[0051] In the present embodiment, without being limited to positions each between the associated semiconductor elements and the associated heat spreaders, recessed portions are also provided at positions each between the associated semiconductor elements, not between any of the heat spreaders. In a case where the semiconductor elements are arranged with wide gaps therebetween in this manner, recessed portions are also provided at positions each between the associated semiconductor elements, not between any of the heat spreaders, thereby enabling gas generated at the time of connecting the power module 101 and the cooler 14 to each other via the connecting member 15 to be discharged to the outside more efficiently.

[0052] The arrangement of the recessed sections is not limited to the Fig. 6, and may be another arrangement as long as each of the recessed portions is arranged at a position where it overlaps the connecting member 15 provided between the cooling surface 20 and the power module 101 and does not overlap with any of the plurality of semiconductor elements as viewed in the direction perpendicular to the cooling surface 20. In case of using another arrangement, reduction of the thermal resistance of the connecting member 15 and prevention of a solder void can be realized.

[0053] In the present embodiment, the recessed portions 17, 17a, 17b, 17c, and 17d extend outward from the connecting member 15 provided between the cooling surface 20 and the power module 101 in the direction perpendicular to the cooling surface 20. Without limiting the configuration in which the recessed portion 17 is arranged to extend outward from the connecting member 15, the recessed portion 17 may be arranged only inside the connecting member 15. In a case where the recessed portions 17, 17a, 17b, 17c, and 17d are arranged inside the connecting member 15, gas cannot be discharged to the outside but can be discharged into the recessed portions 17, 17a, 17b, 17c, and 17d.In addition, in the case where the recessed portions 17, 17a, 17b, 17c and 17d are arranged only inside the connecting member 15, water, foreign matter or the like can be prevented from entering the interior of the semiconductor device 100 from the outside through the recessed portions 17, 17a, 17b, 17c and 17d. Embodiment 5

[0054] Semiconductor devices 100 according to Embodiment 5 will be described. Fig. 7 is a plan view schematically showing a semiconductor device 100 according to Embodiment 5, and Fig. Fig. 8 is a sectional view of the semiconductor device 100 taken at the cutting position BB in Fig. 7. The semiconductor device 100 according to Embodiment 5 has a configuration in which the power module 101 has protruding portions 21.

[0055] In the present embodiment, as shown in Fig. 7, an outer edge portion of a gap between the cooling surface 20 and the power module 101 has non-connected regions 23 as regions where the connecting member 15 is not provided. The recessed portion 17 extends from a region where the connecting member 15 is provided to the non-connected regions 23 as viewed in the direction perpendicular to the cooling surface 20. In the present embodiment, the recessed portion 17 is also provided in portions of the cooling surface 20 that do not overlap with the power module 101 as viewed in the direction perpendicular to the cooling surface 20. The power module 101 has, in the non-connected regions 23, the protruding portions 21 protruding toward the depressed portion 17 side. In the present embodiment, one protruding portion 21 is provided in each of two non-connected regions 23 facing the depressed portion 17.A plurality of the protruding portions 21 may be provided in each of the non-connected areas 23.

[0056] As in Fig. As shown in Fig. 8, each of the protruding portions 21 is a portion of the sealing resin 13 that seals the parts constituting the power module 101, which protrudes toward the recessed portion 17 side. The protruding portions 21 are formed simultaneously with the sealing of the parts constituting the power module 101. The method for forming the protruding portions 21 is not limited to this. For example, portions each made of a metal material or the like may be sealed together with the portions constituting the power module 101 so as to have portions protruding from the sealing resin 13, and these portions may be used as the protruding portions 21. Alternatively, the portions to serve as the protruding portions 21 may be attached to portions of the sealing resin 13 in the non-bonded areas 23 facing the recessed portion 17.In a case where each of the protruding portions 21 is made of a metal with high solder wettability and is provided to be adjacent to the connecting member 15, the metal and the solder are wetted after gas is discharged, whereby the intrusion of foreign substances, such as water, into the interior of the recessed portion 17 can be prevented. In a case where the protruding portions 21 are formed from the sealing resin 13 simultaneously with the sealing of the parts constituting the power module 101, no other portions serving as the protruding portions 21 are required, whereby the productivity of the semiconductor device 100 can be improved. Therefore, the protruding portions 21 are preferably formed from the sealing resin 13.

[0057] By providing the protruding portions 21, it is possible to prevent a cleaning liquid from entering the space between the power module 101 and the recessed portion 17 in a cleaning step after joining, while maintaining the function of efficiently discharging gas generated at the time of joining the power module 101 and the cooler 14 to each other via the connecting member 15. Since the penetration of a cleaning liquid is prevented, a cleaning liquid can be prevented from adhering to a surface of the power module 101 by ejecting the cleaning liquid from the space between the power module 101 and the recessed portion 17 during subsequent drying.Since a cleaning liquid can be prevented from adhering to the surface of the power module 101, the leakage current insulation properties of the power module 101 can be improved.

[0058] Although each of the above sections 21 in Fig. 7 is arranged at a central portion of the associated non-connected portion 23 in the direction in which the recessed portion 17 extends, the position of the projecting portion 21 is not limited to the central portion of the non-connected portion 23. As in Fig. 9, the protruding portion 21 may be arranged at an outer end portion of the non-connected portion 23. Fig. 9 is a schematic plan view showing another semiconductor device 100 according to Embodiment 5. With such a configuration, the area allowing the entry of a cleaning liquid can be reduced, thereby further improving the leakage current isolation performance of the power module 101. The closer the position of the protruding portion 21 is to the outer end portion of the non-connected portion 23, the greater the effect of reducing the area allowing the entry of a cleaning liquid.

[0059] In the present embodiment, as shown in Fig. 8, the protruding portion 21 has a height greater than a depth of the recessed portion 17, and a gap is present between the protruding portion 21 and an inner surface of the recessed portion 17. Fig. 8 shows the cross-sectional shapes of the protruding portion 21 and the recessed portion 17. Simply providing the protruding portion 21 can prevent a cleaning liquid from entering the space between the power module 101 and the recessed portion 17. However, if the protruding portion 21 has a height greater than the depth of the recessed portion 17, and a gap exists between the protruding portion 21 and the inner surface of the recessed portion 17, the effect of preventing the penetration of a cleaning liquid can be further enhanced. A specific dimension is as follows. That is, a dimension between a top surface 21a of the protruding portion 21 and a bottom surface 22 of the recessed portion is less than 0.22 mm. With this dimension, water enters but is not discharged to the outside. Consequently, the insulation properties can be improved.In addition, when the dimension between the top surface 21a of the protruding portion 21 and the bottom surface 22 of the depressed portion is 0.08 mm or smaller, the intrusion of water can be prevented, whereby a higher effect in terms of improving the insulating properties can be achieved.

[0060] In the present embodiment, as shown in Fig. As shown in Figure 8, the vertical cross-sectional shape of the protruding portion 21 is rectangular. However, the vertical cross-sectional shape of the protruding portion 21 is not limited to a rectangular shape. The protruding portion 21 only needs to have the function of preventing the intrusion of a cleaning liquid from the outside while maintaining the function of the path through which gas generated between the power module 101 and the radiator 14 is discharged to the outside. Thus, the vertical cross-sectional shape of the protruding portion 21 can be a shape such as a V-shape or a U-shape, for example.

[0061] In the present embodiment, as shown in Fig. As shown in Figure 7, the horizontal cross-sectional shape of the protruding portion 21 is circular. However, the horizontal cross-sectional shape of the protruding portion 21 is not limited to a circular shape. The protruding portion 21 only needs to function to prevent the penetration of a cleaning liquid from the outside while maintaining the function of the path through which gas generated between the power module 101 and the radiator 14 is discharged to the outside. Thus, the horizontal cross-sectional shape of the protruding portion 21 can be a shape such as a quadrangular shape or a hexagonal shape, for example.In a case where the top surface 21a of the protruding portion 21 is located on an inner side of the depressed portion 17, the horizontal cross-sectional shape of the protruding portion 21 is such that a gap is present between each of the side walls of the depressed portion 17 and the corresponding side wall of the protruding portion 21, and as the gap becomes smaller, the effect of preventing the penetration of a cleaning liquid can be enhanced. Embodiment 6

[0062] A semiconductor device 100 according to Embodiment 6 will be described. Fig. 10 is a schematic sectional view of the semiconductor device 100 according to Embodiment 6 and a sectional view of the semiconductor device 100 taken at the same position as in Fig.8. The semiconductor device 100 according to Embodiment 6 has a configuration in which the position of the top surface 21a of each of the protruding portions 21 is defined.

[0063] The upper surface 21a of the protruding portion 21 is located on the inner side of the recessed portion 17, and a gap is provided between the protruding portion 21 and the inner surface of the recessed portion 17. In such a configuration, the distance between the upper surface 21a of the protruding portion 21 and the lower surface 22 of the recessed portion can be shortened. Since the distance between the upper surface 21a of the protruding portion 21 and the lower surface 22 of the recessed portion is shortened, it is possible to further improve the effect of preventing the ingress of a cleaning liquid while maintaining the function of the path through which gas generated between the power module 101 and the radiator 14 is discharged to the outside. Since the effect of inhibiting the ingress of a cleaning liquid is further enhanced, the leakage current insulation properties of the power module 101 can be further improved.

[0064] The present embodiment is also such that, similar to Embodiment 5, the protruding portion 21 has a height greater than the depth of the recessed portion 17, and a gap is provided between the protruding portion 21 and the inner surface of the recessed portion 17. Thus, the present embodiment has the same advantageous effects as those in Embodiment 5. Although the vertical cross-sectional shape of the protruding portion 21 is a rectangular shape in the present embodiment, the vertical cross-sectional shape of the protruding portion 21 is not limited to a rectangular shape. The vertical cross-sectional shape of the protruding portion 21 may be a shape such as a V-shape or a U-shape, for example.

[0065] Although the disclosure is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects, and functions described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead may be applied alone or in various combinations to one or more of the embodiments of the disclosure. It is therefore understood that numerous modifications not exemplified may be developed without departing from the scope of the present disclosure. For example, at least one of the components may be modified, added, or removed. At least one of the components mentioned in at least one of the preferred embodiments may be selected and combined with the components mentioned in another preferred embodiment.

[0066] The modes of the present disclosure are summarized below as additional notes. (Additional Note 1)

[0067] A semiconductor device comprising: a power module comprising a plurality of semiconductor elements; and a cooler with a cooling surface to which the power module is thermally connected via a connecting element with a soldering material, wherein the plurality of semiconductor elements are arranged at such positions that they do not overlap in a direction perpendicular to the cooling surface, the cooling surface has a depressed portion, and the depressed portion is arranged at a position such that it overlaps with the connecting member provided between the cooling surface and the power module and does not overlap with any of the plurality of semiconductor elements when viewed in the direction perpendicular to the cooling surface. (Additional Note 2)

[0068] The semiconductor device according to Additional Note 1, wherein the semiconductor elements comprise two semiconductor elements arranged so as to be adjacent to one another, wherein one of the two semiconductor elements is defined as a first semiconductor element, another of the two semiconductor elements is defined as a second semiconductor element, the performance module includes the first semiconductor element, a first heat spreader having a one-sided surface to which the first semiconductor element is electrically connected, the second semiconductor element, a second heat spreader arranged side by side with the first heat spreader with a gap therebetween on a same plane, the second heat spreader having a one-sided surface to which the second semiconductor element is electrically connected, an insulating element having a one-sided surface to which another side surface of the first heat spreader and another side surface of the second heat spreader are thermally connected, a copper plate having a one-sided surface to which another side surface of the insulating element is thermally connected, and a sealing resin cover, in a state in which another side surface of the copper plate thereof is exposed, wherein the first heat spreader, the second heat spreader, the first semiconductor element, the second semiconductor element and the insulating element and the recessed portion is located between the first heat spreader and the second heat spreader at a position where it does not overlap with either the first heat spreader or the second heat spreader, for example in the direction perpendicular to the cooling surface. (Additional Note 3)

[0069] The semiconductor device according to Additional Note 1 or 2, wherein the cooling surface is a surface of a plating layer with solder wettability and the recessed part penetrates the plating layer, for example, so that an element is exposed on a lower side with respect to the plating layer. (Additional Note 4)

[0070] The semiconductor device according to Additional Note 3, wherein the exposed element on the lower side has lower solder wettability than the plating layer. (Additional Note 5)

[0071] A semiconductor device according to Additional Note 4, in which the exposed element on the lower side is made of aluminum or an aluminum alloy. (Additional Note 6)

[0072] A semiconductor device according to any one of Additional Notes 3 to 5, wherein the recessed portion is also formed in the exposed element on the lower side. (Additional Note 7)

[0073] The semiconductor device according to any one of Additional Notes 1 to 6, wherein the depressed portion is a groove extending outward from the connecting member provided between the cooling surface and the power module in a direction perpendicular to the cooling surface. (Additional Note 8)

[0074] The semiconductor device according to any one of Additional Notes 1 to 7, wherein a surface on the side of the connecting element of the power module has a module-side recessed portion and the module-side recessed portion is located at a position where it overlaps with the connecting member provided between the cooling surface and the power module and does not overlap with any of the plurality of semiconductor elements, viewed in the direction perpendicular to the cooling surface. (Additional Note 9)

[0075] The semiconductor device according to any one of Additional Notes 1 to 7, wherein an outer edge portion of a gap between the cooling surface and the power module has a non-connected area in which the connecting element is not provided, the recessed portion extends from a region in which the connecting element is provided to the non-connected region, viewed in the direction perpendicular to the cooling surface, and the power module has a protruding portion in the non-connected area that protrudes to the side of the recessed portion. (Additional Note 10)

[0076] A semiconductor device according to Additional Note 9, wherein the protruding portion has a height greater than the depth of the recessed portion, and there is a gap between the protruding portion and an inner surface of the recessed portion. (Additional Note 11)

[0077] A semiconductor device according to Additional Note 9, wherein an upper surface of the protruding portion is disposed on an inner surface of the recessed portion, and a gap is provided between the protruding portion and an inner surface of the recessed portion. (Additional Note 12)

[0078] The semiconductor device according to any one of Additional Notes 9 to 11, wherein the protruding portion is located at an outer end portion of the non-bonded region. DESCRIPTION OF REFERENCE SYMBOLS 1, 1a, 1b, 1c, 2 first semiconductor element 3 first heat distributor 4 first ladder frame 5, 5a, 5b, 5c, 6 second semiconductor element 7, 7a, 7b, 7c second heat distributor 8 second ladder frame 9 third ladder frame 10 fourth ladder frame 11 Insulating element 12 copper plate 13 Sealing resin 14 coolers 15 Connecting element 16 coating layer 17, 17a, 17b, 17c, 17d in-depth section 18 Surface of the recessed section 19 Module-side recessed section 20 cooling surface 21 preceding section 21a top 22 Bottom of the recessed section 23 unconnected area 100 semiconductor devices 101 Power Module QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6183556

[0004]

Claims

[1] A semiconductor device comprising: a power module comprising a plurality of semiconductor elements; and a cooler with a cooling surface to which the power module is thermally connected via a connecting element with a soldering material, wherein the plurality of semiconductor elements are arranged at such positions that they do not overlap in a direction perpendicular to the cooling surface, the cooling surface has a recessed section and the recessed portion is arranged at such a position that it overlaps with the connecting member provided between the cooling surface and the power module and does not overlap with any of the plurality of semiconductor elements as viewed in the direction perpendicular to the cooling surface. [2] A semiconductor device according to claim 1, wherein the semiconductor elements comprise two semiconductor elements arranged so as to be adjacent to one another, wherein one of the two semiconductor elements is defined as a first semiconductor element, another of the two semiconductor elements is defined as a second semiconductor element, the performance module includes the first semiconductor element, a first heat spreader having a one-sided surface to which the first semiconductor element is electrically connected, the second semiconductor element, a second heat spreader disposed adjacent to the first heat spreader with a gap therebetween on a same plane, the second heat spreader having a one-sided surface to which the second semiconductor element is electrically connected, an insulating element having a one-sided surface to which another side surface of the first heat spreader and another side surface of the second heat spreader are thermally connected, a copper plate having a one-sided surface to which another side surface of the insulating element is thermally connected, and a sealing resin covering, in a state where another side surface of the copper plate is exposed, the first heat spreader, the second heat spreader, the first semiconductor element, the second semiconductor element and the insulating element, and the recessed portion is located between the first heat spreader and the second heat spreader at a position such that it does not overlap with either the first heat spreader or the second heat spreader, as viewed in the direction perpendicular to the cooling surface. [3] A semiconductor device according to claim 1 or 2, wherein the cooling surface is a surface of a plating layer with a solder wettability and the recessed portion penetrates the plating layer so that an element is exposed on a lower side relative to the plating layer. [4] The semiconductor device according to claim 3, wherein the exposed element on the lower side has lower solder wettability than the plating layer. [5] A semiconductor device according to claim 4, wherein the exposed member on the lower side is made of aluminum or an aluminum alloy. [6] A semiconductor device according to any one of claims 3 to 5, wherein the recessed portion is also formed in the exposed member on the lower side. [7] The semiconductor device according to any one of claims 1 to 6, wherein the recessed portion is a groove extending outwardly from the connecting member provided between the cooling surface and the power module as viewed in the direction perpendicular to the cooling surface. [8] A semiconductor device according to any one of claims 1 to 7, wherein a surface on the side of the connecting element of the power module has a module-side recessed portion and the module-side recessed portion is located at a position where it overlaps with the connecting member provided between the cooling surface and the power module and does not overlap with any of the plurality of semiconductor elements as viewed in the direction perpendicular to the cooling surface. [9] A semiconductor device according to any one of claims 1 to 7, wherein an outer edge portion of a gap between the cooling surface and the power module has a non-connected area as an area in which the connecting element is not provided, the recessed portion extends from a region in which the connecting element is provided to the non-connected region, as seen in the direction perpendicular to the cooling surface, and the power module has a protruding portion in the non-connected area that protrudes to the side of the recessed portion. [10] A semiconductor device according to claim 9, wherein the protruding portion has a height greater than a depth of the recessed portion, and a gap exists between the protruding portion and an inner surface of the recessed portion. [11] A semiconductor device according to claim 9, wherein an upper side of the projecting portion is arranged on an inner side of the recessed portion and a gap exists between the protruding portion and an inner surface of the recessed portion. [12] A semiconductor device according to any one of claims 9 to 11, wherein the protruding portion is arranged at an outer end portion of the non-bonded region.

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